Comparative analysis of diversity and utilization of edible plants in arid and semi-arid areas in Benin.

PubMed

Segnon, Alcade C; Achigan-Dako, Enoch G

2014-12-23

Agrobiodiversity is said to contribute to the sustainability of agricultural systems and food security. However, how this is achieved especially in smallholder farming systems in arid and semi-arid areas is rarely documented. In this study, we explored two contrasting regions in Benin to investigate how agroecological and socioeconomic contexts shape the diversity and utilization of edible plants in these regions. Data were collected through focus group discussions in 12 villages with four in Bassila (semi-arid Sudano-Guinean region) and eight in Boukoumbé (arid Sudanian region). Semi-structured interviews were carried out with 180 farmers (90 in each region). Species richness and Shannon-Wiener diversity index were estimated based on presence-absence data obtained from the focus group discussions using species accumulation curves. Our results indicated that 115 species belonging to 48 families and 92 genera were used to address food security. Overall, wild species represent 61% of edible plants collected (60% in the semi-arid area and 54% in the arid area). About 25% of wild edible plants were under domestication. Edible species richness and diversity in the semi-arid area were significantly higher than in the arid area. However, farmers in the arid area have developed advanced resource-conserving practices compared to their counterparts in the semi-arid area where slash-and-burn cultivation is still ongoing, resulting in natural resources degradation and loss of biodiversity. There is no significant difference between the two areas for cultivated species richness. The interplay of socio-cultural attributes and agroecological conditions explains the diversity of food plants selected by communities. We conclude that if food security has to be addressed, the production and consumption policies must be re-oriented toward the recognition of the place of wild edible plants. For this to happen we suggest a number of policy and strategic decisions as well as research and development actions such as a thorough documentation of wild edible plants and their contribution to household diet, promotion of the ''bringing into cultivation" practices, strengthening of livestock-crop integration.

Applying an Avian Index of Biological Integrity to Assess and Monitor Arid and Semi-arid Riparian Ecosystems

DTIC Science & Technology

2009-01-01

Fausch et al . 1984; Miller et al . 1988; O’Connell et al . 2000; Bryce et al . 2002 ; Bryce 2006; Lussier et al . 2006). Once...the IHD assessed (Karr and Chu 1999; Bryce et al . 2002 ; Bryce 2006). From this assessment, usually a small subset of the biological metrics (e.g., 6...grazing, water impoundments and diversions, and other human land-use practices (Saab et al . 1995; Rich 2002 ;

Competing effects of groundwater withdrawals and climate change on water availability in semi-arid India

NASA Astrophysics Data System (ADS)

Sishodia, R. P.; Shukla, S.

2017-12-01

India, a global leader in groundwater use (250 km3/yr), is experiencing groundwater depletion. There has been a 130-fold increase in number of irrigation wells since 1960. Anticipated future increase in groundwater demand is likely to exacerbate the water availability in the semi-arid regions of India. Depending on the direction of change, future climate change may either worsen or enhance the water availability. This study uses an integrated hydrologic modeling approach (MIKE SHE MIKE 11) to compare and combine the effects of future (2040-2069) increased groundwater withdrawals and climate change on surface and groundwater flows and availability for an agricultural watershed in semi-arid south India. Modeling results showed that increased groundwater withdrawals in the future resulted in reduced surface flows (25%) and increased frequency and duration (90 days/yr) of well drying. In contrast, projected future increase in rainfall (7-43%) under the changed climate showed increased groundwater recharge (15-67%) and surface flows (9-155%). Modeling results suggest that the positive effects of climate change may enhance the water availability in this semi-arid region of India. However, in combination with increased withdrawals, climate change was shown to increase the well drying and reduce the water availability especially during dry years. A combination of management options such as flood to drip conversion, energy subsidy reductions and water storage can support increased groundwater irrigated area in the future while mitigating the well drying. A cost-benefit analysis showed that dispersed water storage and flood to drip conversion can be highly cost-effective in this semi-arid region. The study results suggest that the government and management policies need to be focused towards an integrated management of demand and supply to create a sustainable food-water-energy nexus in the region.

How Green Water Flows structure be a decision indicator for ecological water allocation in arid Ejina Delta, China.

NASA Astrophysics Data System (ADS)

Yu, J.; Du, C.; Zhang, Y.; Liu, X.

2014-12-01

Green water flows, a key ecohydrological process, dominates the hydrological cycle in arid region. The structure of green water flows reflects the landscape water consumption characteristics and can be easily obtained by means of remote sensing approach. In arid region, limited fresh water and fragile environment resulted in sharp contradictions between economy and natural ecosystem concerning water demands. To rationally allocate economic and ecological water use, to maximize the regional freshwater use efficiency, is the route one must take for sustainable development in arid area. The pursuit of the most necessary ecological protection function and the maximum ecological water use efficiency is the key to ecological water allocation. However, we are short of simple and quick detectable variables or indexes to assess ecological water allocation decision. This paper introduced the green water flows structure as a decision variable, chose Heihe river flow allocation to downstream Ejina Delta for ecological protection as an example, put forward why and how green water flows structure could be used for ecological water allocation decision. The authors expect to provide reference for integrated fresh water resources management practice in arid region.

Individual based, long term monitoring of acacia trees in hyper arid zone: Integration of a field survey and a remote sensing approach

NASA Astrophysics Data System (ADS)

Isaacson, Sivan; Blumberg, Dan G.; Ginat, Hanan; Shalmon, Benny

2013-04-01

Vegetation in hyper arid zones is very sparse as is. Monitoring vegetation changes in hyper arid zones is important because any reduction in the vegetation cover in these areas can lead to a considerable reduction in the carrying capacity of the ecological system. This study focuses on the impact of climate fluctuations on the acacia population in the southern Arava valley, Israel. The period of this survey includes a sequence of dry years with no flashfloods in most of the plots that ended in two years with vast floods. Arid zone acacia trees play a significant role in the desert ecosystem by moderating the extreme environmental conditions including radiation, temperature, humidity and precipitation. The trees also provide nutrients for the desert dwellers. Therefore, acacia trees in arid zones are considered to be `keystone species', because they have major influence over both plants and animal species, i.e., biodiversity. Long term monitoring of the acacia tree population in this area can provide insights into long term impacts of climate fluctuations on ecosystems in arid zones. Since 2000, a continuous yearly based survey on the three species of acacia population in seven different plots is conducted in the southern Arava (established by Shalmon, ecologist of the Israel nature and parks authority). The seven plots representing different ecosystems and hydrological regimes. A yearly based population monitoring enabled us to determine the mortality and recruitment rate of the acacia populations as well as growing rates of individual trees. This survey provides a unique database of the acacia population dynamics during a sequence of dry years that ended in a vast flood event during the winter of 2010. A lack of quantitative, nondestructive methods to estimate and monitor stress status of the acacia trees, led us to integrate remote sensing tools (ground and air-based) along with conventional field measurements in order to develop a long term monitoring of acacia trees in hyper arid zones. This study includes further work on the development of ground based remote sensing as a new tool to monitor stress indicators as part of long term ecological research. Since acacia trees are long lived, we were able to identify individual trees in satellite images from 1968 (corona) and expand our monitoring "into the past". Remote sensing expands the spatial and temporal database and is thus a powerful tool for long term monitoring in arid zones, where access is limited and long-term ground data are rare.

Modeling the Surface Water-Groundwater Interaction in Arid and Semi-Arid Regions Impacted by Agricultural Activities

NASA Astrophysics Data System (ADS)

Tian, Y.; Wu, B.; Zheng, Y.

2013-12-01

In many semi-arid and arid regions, interaction between surface water and groundwater plays an important role in the eco-hydrological system. The interaction is often complicated by agricultural activities such as surface water diversion, groundwater pumping, and irrigation. In existing surface water-groundwater integrated models, simulation of the interaction is often simplified, which could introduce significant simulation uncertainty under certain circumstance. In this study, GSFLOW, a USGS model coupling PRMS and MODFLOW, was improved to better characterize the surface water-groundwater interaction. The practices of water diversion from rivers, groundwater pumping and irrigation are explicitly simulated. In addition, the original kinematic wave routing method was replaced by a dynamic wave routing method. The improved model was then applied in Zhangye Basin (the midstream part of Heihe River Baisn), China, where the famous 'Silk Road' came through. It is a typical semi-arid region of the western China, with extensive agriculture in its oasis. The model was established and calibrated using the data in 2000-2008. A series of numerical experiments were conducted to evaluate the effect of those improvements. It has been demonstrated that with the improvements, the observed streamflow and groundwater level were better reproduced by the model. The improvements have a significant impact on the simulation of multiple fluxes associated with the interaction, such as groundwater discharge, riverbed seepage, infiltration, etc. Human activities were proved to be key elements of the water cycle in the study area. The study results have important implications to the water resources modeling and management in semi-arid and arid basins.

A Comparison of Nannochloropsis salina Growth Performance in Two Outdoor Pond Designs: Conventional Raceways versus the ARID Pond with Superior Temperature Management

DOE PAGES

Crowe, Braden; Attalah, Said; Agrawal, Shweta; ...

2012-01-01

The present study examines how climatic conditions and pond design affect the growth performance of microalgae. From January to April of 2011, outdoor batch cultures of Nannochloropsis salina were grown in three replicate 780 L conventional raceways, as well as in an experimental 7500 L algae raceway integrated design (ARID) pond. The ARID culture system utilizes a series of 8-20 cm deep basins and a 1.5 m deep canal to enhance light exposure and mitigate temperature variations and extremes. The ARID culture reached the stationary phase 27 days earlier than the conventional raceways, which can be attributed to its superiormore » temperature management and shallower basins. On a night when the air temperature dropped to -9°C, the water temperature was 18°C higher in the ARID pond than in the conventional raceways. Lipid and fatty acid content ranged from 16 to 25% and from 5 to15%, respectively, as a percentage of AFDW. Palmitic, palmitoleic, and eicosapentaenoic acids comprised the majority of fatty acids. While the ARID culture system achieved nearly double the volumetric productivity relative to the conventional raceways (0.023 versus 0.013 g L -1day -1), areal biomass productivities were of similar magnitude in both pond systems (3.47 versus 3.34 g m -2day -1), suggesting that the ARID pond design has to be further optimized, most likely by increasing the culture depth or operating at higher cell densities while maintaining adequate mixing.« less

A comparison of Nannochloropsis salina growth performance in two outdoor pond designs: conventional raceways versus the ARID pond with superior temperature management

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crowe, Braden J.; Attalah, Said; Agrawal, Shweta

2012-10-01

The present study examines how climatic conditions and pond design affect the growth performance of microalgae. From January to April of 2011, outdoor batch cultures of Nannochloropsis salina were grown in three replicate 780 L conventional raceways, as well as in an experimental 7500 L ARID (Algae Raceway Integrated Design) pond. The ARID culture system utilizes a series of 8 to 20 cm deep basins and a 1.5 m deep canal to enhance light exposure and mitigate temperature variations and extremes. The ARID culture reached the stationary phase 27 days earlier than the conventional raceways, which can be attributed tomore » its superior temperature management and shallower basins. On a night when the air temperature dropped to -9 °C, the water temperature was 18 °C higher in the ARID pond than in the conventional raceways. Lipid and fatty acid content ranged from 16 - 25 % and 5 - 15 %, respectively, as a percentage of AFDW. Palmitic, palmitoleic, and eicosapentaenoic acid comprised the majority of fatty acids. While the ARID culture system achieved nearly double the volumetric productivity relative to the conventional raceways (0.023 vs 0.013 g L-1day-1), areal biomass productivities were of similar magnitude in both pond systems (3.34 vs. 3.47 g m-2day-1), suggesting that the ARID pond design has to be further optimized, most likely by increasing the culture depth or operating at higher cell densities while maintaining adequate mixing.« less

Sustainability or Collapse: Interplay Between Decadal Climate Variability and Human Activities Matters

NASA Astrophysics Data System (ADS)

Lu, Y.; Hu, H.; Tian, F.

2016-12-01

The Aral Sea Crisis and the deterioration of Tarim River Basin are representative cases of emergent water deficit problems in arid areas. Comparing cases of water deficit problems in different regions and considering the in the perspective of socio-hydrology is helpful to obtain guidance on integrated management of arid area basins. Analyzing the interplay between decadal climate variability and human activities in both basins, the important role of human activities is observed. Decadal climate variability tempts people to adapt fast to increasing water resources and slowly to decreasing water resources, while using unsustainable technical measures to offset water shortage. Due to this asymmetry the situation deteriorates with technically enhanced capabilities of societies to exploit water resources, and more integrated long-term management capacity is in high demand.

Significant Impacts of Increasing Aridity on the Arid Soil Microbiome.

PubMed

Neilson, Julia W; Califf, Katy; Cardona, Cesar; Copeland, Audrey; van Treuren, Will; Josephson, Karen L; Knight, Rob; Gilbert, Jack A; Quade, Jay; Caporaso, J Gregory; Maier, Raina M

2017-01-01

Global deserts occupy one-third of the Earth's surface and contribute significantly to organic carbon storage, a process at risk in dryland ecosystems that are highly vulnerable to climate-driven ecosystem degradation. The forces controlling desert ecosystem degradation rates are poorly understood, particularly with respect to the relevance of the arid-soil microbiome. Here we document correlations between increasing aridity and soil bacterial and archaeal microbiome composition along arid to hyperarid transects traversing the Atacama Desert, Chile. A meta-analysis reveals that Atacama soil microbiomes exhibit a gradient in composition, are distinct from a broad cross-section of nondesert soils, and yet are similar to three deserts from different continents. Community richness and diversity were significantly positively correlated with soil relative humidity (SoilRH). Phylogenetic composition was strongly correlated with SoilRH, temperature, and electrical conductivity. The strongest and most significant correlations between SoilRH and phylum relative abundance were observed for Acidobacteria , Proteobacteria , Planctomycetes , Verrucomicrobia , and Euryarchaeota (Spearman's rank correlation [ r s ] = >0.81; false-discovery rate [ q ] = ≤0.005), characterized by 10- to 300-fold decreases in the relative abundance of each taxon. In addition, network analysis revealed a deterioration in the density of significant associations between taxa along the arid to hyperarid gradient, a pattern that may compromise the resilience of hyperarid communities because they lack properties associated with communities that are more integrated. In summary, results suggest that arid-soil microbiome stability is sensitive to aridity as demonstrated by decreased community connectivity associated with the transition from the arid class to the hyperarid class and the significant correlations observed between soilRH and both diversity and the relative abundances of key microbial phyla typically dominant in global soils. IMPORTANCE We identify key environmental and geochemical factors that shape the arid soil microbiome along aridity and vegetation gradients spanning over 300 km of the Atacama Desert, Chile. Decreasing average soil relative humidity and increasing temperature explain significant reductions in the diversity and connectivity of these desert soil microbial communities and lead to significant reductions in the abundance of key taxa typically associated with fertile soils. This finding is important because it suggests that predicted climate change-driven increases in aridity may compromise the capacity of the arid-soil microbiome to sustain necessary nutrient cycling and carbon sequestration functions as well as vegetative cover in desert ecosystems, which comprise one-third of the terrestrial biomes on Earth.

Scaling up semi-arid grassland biochemical content from the leaf to the canopy level: challenges and opportunities.

PubMed

He, Yuhong; Mui, Amy

2010-01-01

Remote sensing imagery is being used intensively to estimate the biochemical content of vegetation (e.g., chlorophyll, nitrogen, and lignin) at the leaf level. As a result of our need for vegetation biochemical information and our increasing ability to obtain canopy spectral data, a few techniques have been explored to scale leaf-level biochemical content to the canopy level for forests and crops. However, due to the contribution of non-green materials (i.e., standing dead litter, rock, and bare soil) from canopy spectra in semi-arid grasslands, it is difficult to obtain information about grassland biochemical content from remote sensing data at the canopy level. This paper summarizes available methods used to scale biochemical information from the leaf level to the canopy level and groups these methods into three categories: direct extrapolation, canopy-integrated approach, and inversion of physical models. As for semi-arid heterogeneous grasslands, we conclude that all methods are useful, but none are ideal. It is recommended that future research should explore a systematic upscaling framework which combines spatial pattern analysis, canopy-integrated approach, and modeling methods to retrieve vegetation biochemical content at the canopy level.

Operational User Requirements and Priorities for a Soldier’s Integrated Headwear System (Priorites et Exigences Operationnelles du Casque Integre du Soldat)

DTIC Science & Technology

2006-11-21

considerations included thermal comfort in the heat, given the higher potential for heat casualties in hot, arid environments of ongoing and future conflicts...26 3.9.1 Thermal Comfort ...................................................................................................27...23 1. THERMAL COMFORT ................................................................................................. A-23 2. PHYSICAL COMFORT

Impacts of agricultural land use on biological integrity: A causal analysis

USGS Publications Warehouse

Riseng, C.M.; Wiley, M.J.; Black, R.W.; Munn, M.D.

2011-01-01

Agricultural land use has often been linked to nutrient enrichment, habitat degradation, hydrologic alteration, and loss of biotic integrity in streams. The U.S. Geological Survey's National Water Quality Assessment Program sampled 226 stream sites located in eight agriculture-dominated study units across the United States to investigate the geographic variability and causes of agricultural impacts on stream biotic integrity. In this analysis we used structural equation modeling (SEM) to develop a national and set of regional causal models linking agricultural land use to measured instream conditions. We then examined the direct, indirect, and total effects of agriculture on biotic integrity as it acted through multiple water quality and habitat pathways. In our nation-wide model, cropland affected benthic communities by both altering structural habitats and by imposing water quality-related stresses. Regionspecific modeling demonstrated that geographic context altered the relative importance of causal pathways through which agricultural activities affected stream biotic integrity. Cropland had strong negative total effects on the invertebrate community in the national, Midwest, and Western models, but a very weak effect in the Eastern Coastal Plain model. In theWestern Arid and Eastern Coastal Plain study regions, cropland impacts were transmitted primarily through dissolved water quality contaminants, but in the Midwestern region, they were transmitted primarily through particulate components of water quality. Habitat effects were important in the Western Arid model, but negligible in the Midwest and Eastern Coastal Plain models. The relative effects of riparian forested wetlands also varied regionally, having positive effects on biotic integrity in the Eastern Coastal Plain andWestern Arid region models, but no statistically significant effect in the Midwest. These differences in response to cropland and riparian cover suggest that best management practices and planning for the mitigation of agricultural land use impacts on stream ecosystems should be regionally focused. ?? 2011 by the Ecological Society of America.

Integrated test plan for directional boring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Volk, B.W.

This integrated test plan describes the field testing of the DITCH WITCH Directional Boring System. DITCH WITCH is a registered trademark of The Charles Machine Works, Inc., Perry, Oklahoma. The test is being conducted as a coordinated effort between Charles Machine Works (CMW), Sandia National Laboratories (SNL), and the Westinghouse Hanford Company (WHC). Funding for the WHC portion of the project is through the Volatile Organic Compound-Arid Integrated Demonstration (VOC-Arid ID). The purpose of the test is to evaluate the performance of the directional boring system for possible future use on environmental restoration projects at Hanford and other Department ofmore » Energy (DOE) sites. The test will be conducted near the 200 Areas Fire Station located between the 200 East and 200 West Area of the Hanford Site. The directional boring system will be used to drill and complete (with fiberglass casing) two horizontal boreholes. A third borehole will be drilled to test sampling equipment but will not be completed with casing.« less

Hydraulic integration and shrub growth form linked across continental aridity gradients.

Treesearch

H. Jochen Schenk; Susana Espino; Christine M. Goedhart; Marisa Nordenstahl; Hugo I. Martinez Cabrera; Cynthia S. Jones

2009-01-01

Both engineered hydraulic systems and plant hydraulic systems are protected against failure by resistance, reparability, and redundancy. A basic rule of reliability engineering is that the level of...

Estimates of Ground-Water Recharge in Wadis of Arid, Mountainous Areas Using the Chloride Mass-Balance Approach

NASA Astrophysics Data System (ADS)

Wood, W. W.; Wood, W. W.

2001-05-01

Evaluation of ground-water supply in arid areas requires estimation of annual recharge. Traditional physical-based hydrologic estimates of ground-water recharge result in large uncertainties when applied in arid, mountainous environments because of infrequent, intense rainfall events, destruction of water-measuring structures associated with those events, and consequent short periods of hydrologic records. To avoid these problems and reduce the uncertainty of recharge estimates, a chloride mass-balance (CMB) approach was used to provide a time-integrated estimate. Seven basins exhibiting dry-stream beds (wadis) in the Asir and Hijaz Mountains, western Saudi Arabia, were selected to evaluate the method. Precipitation among the basins ranged from less than 70 mm/y to nearly 320 mm/y. Rain collected from 35 locations in these basins averaged 2.0 mg/L chloride. Ground water from 140 locations in the wadi alluvium averaged 200 mg/L chloride. This chloride concentration ratio of precipitation to ground water suggests that on average, approximately 1 percent of the rainfall is recharged, while the remainder is lost to evaporation. Ground-water recharge from precipitation in individual basins ranged from less than 1 to nearly 4 percent and was directly proportional to total precipitation. Independent calculations of recharge using Darcy's Law were consistent with these findings and are within the range typically found in other arid areas of the world. Development of ground water has lowered the water level beneath the wadis and provided more storage thus minimizing chloride loss from the basin by river discharge. Any loss of chloride from the basin results in an overestimate of the recharge flux by the chloride-mass balance approach. In well-constrained systems recharge in arid, mountainous areas where the mass of chloride entering and leaving the basin is known or can be reasonably estimated, the CMB approach provides a rapid, inexpensive method for estimating time-integrated ground-water recharge.

Preface paper to the Semi-Arid Land-Surface-Atmosphere (SALSA) Program special issue

USGS Publications Warehouse

Goodrich, D.C.; Chehbouni, A.; Goff, B.; MacNish, B.; Maddock, T.; Moran, S.; Shuttleworth, W.J.; Williams, D.G.; Watts, C.; Hipps, L.H.; Cooper, D.I.; Schieldge, J.; Kerr, Y.H.; Arias, H.; Kirkland, M.; Carlos, R.; Cayrol, P.; Kepner, W.; Jones, B.; Avissar, R.; Begue, A.; Bonnefond, J.-M.; Boulet, G.; Branan, B.; Brunel, J.P.; Chen, L.C.; Clarke, T.; Davis, M.R.; DeBruin, H.; Dedieu, G.; Elguero, E.; Eichinger, W.E.; Everitt, J.; Garatuza-Payan, J.; Gempko, V.L.; Gupta, H.; Harlow, C.; Hartogensis, O.; Helfert, M.; Holifield, C.; Hymer, D.; Kahle, A.; Keefer, T.; Krishnamoorthy, S.; Lhomme, J.-P.; Lagouarde, J.-P.; Lo, Seen D.; Luquet, D.; Marsett, R.; Monteny, B.; Ni, W.; Nouvellon, Y.; Pinker, R.; Peters, C.; Pool, D.; Qi, J.; Rambal, S.; Rodriguez, J.; Santiago, F.; Sano, E.; Schaeffer, S.M.; Schulte, M.; Scott, R.; Shao, X.; Snyder, K.A.; Sorooshian, S.; Unkrich, C.L.; Whitaker, M.; Yucel, I.

2000-01-01

The Semi-Arid Land-Surface-Atmosphere Program (SALSA) is a multi-agency, multi-national research effort that seeks to evaluate the consequences of natural and human-induced environmental change in semi-arid regions. The ultimate goal of SALSA is to advance scientific understanding of the semi-arid portion of the hydrosphere-biosphere interface in order to provide reliable information for environmental decision making. SALSA approaches this goal through a program of long-term, integrated observations, process research, modeling, assessment, and information management that is sustained by cooperation among scientists and information users. In this preface to the SALSA special issue, general program background information and the critical nature of semi-arid regions is presented. A brief description of the Upper San Pedro River Basin, the initial location for focused SALSA research follows. Several overarching research objectives under which much of the interdisciplinary research contained in the special issue was undertaken are discussed. Principal methods, primary research sites and data collection used by numerous investigators during 1997-1999 are then presented. Scientists from about 20 US, five European (four French and one Dutch), and three Mexican agencies and institutions have collaborated closely to make the research leading to this special issue a reality. The SALSA Program has served as a model of interagency cooperation by breaking new ground in the approach to large scale interdisciplinary science with relatively limited resources.

Leaf water storage increases with salinity and aridity in the mangrove Avicennia marina: integration of leaf structure, osmotic adjustment and access to multiple water sources.

PubMed

Nguyen, Hoa T; Meir, Patrick; Sack, Lawren; Evans, John R; Oliveira, Rafael S; Ball, Marilyn C

2017-08-01

Leaf structure and water relations were studied in a temperate population of Avicennia marina subsp. australasica along a natural salinity gradient [28 to 49 parts per thousand (ppt)] and compared with two subspecies grown naturally in similar soil salinities to those of subsp. australasica but under different climates: subsp. eucalyptifolia (salinity 30 ppt, wet tropics) and subsp. marina (salinity 46 ppt, arid tropics). Leaf thickness, leaf dry mass per area and water content increased with salinity and aridity. Turgor loss point declined with increase in soil salinity, driven mainly by differences in osmotic potential at full turgor. Nevertheless, a high modulus of elasticity (ε) contributed to maintenance of high cell hydration at turgor loss point. Despite similarity among leaves in leaf water storage capacitance, total leaf water storage increased with increasing salinity and aridity. The time that stored water alone could sustain an evaporation rate of 1 mmol m -2  s -1 ranged from 77 to 126 min from subspecies eucalyptifolia to ssp. marina, respectively. Achieving full leaf hydration or turgor would require water from sources other than the roots, emphasizing the importance of multiple water sources to growth and survival of Avicennia marina across gradients in salinity and aridity. © 2017 John Wiley & Sons Ltd.

Effect of integrating straw into agricultural soils on soil infiltration and evaporation.

PubMed

Cao, Jiansheng; Liu, Changming; Zhang, Wanjun; Guo, Yunlong

2012-01-01

Soil water movement is a critical consideration for crop yield in straw-integrated fields. This study used an indoor soil column experiment to determine soil infiltration and evaporation characteristics in three forms of direct straw-integrated soils (straw mulching, straw mixing and straw inter-layering). Straw mulching is covering the land surface with straw. Straw mixing is mixing straw with the top 10 cm surface soil. Then straw inter-layering is placing straw at the 20 cm soil depth. There are generally good correlations among the mulch integration methods at p < 0.05, and with average errors/biases <10%. Straw mixing exhibited the best effect in terms of soil infiltration, followed by straw mulching. Due to over-burden weight-compaction effect, straw inter-layering somehow retarded soil infiltration. In terms of soil water evaporation, straw mulching exhibited the best effect. This was followed by straw mixing and then straw inter-layering. Straw inter-layering could have a long-lasting positive effect on soil evaporation as it limited the evaporative consumption of deep soil water. The responses of the direct straw integration modes to soil infiltration and evaporation could lay the basis for developing efficient water-conservation strategies. This is especially useful for water-scarce agricultural regions such as the arid/semi-arid regions of China.

Contribution to the hydrodynamic modeling of groundwater in the Ain El Bel syncline Wilaya of Djelfa (Algeria)

NASA Astrophysics Data System (ADS)

Azlaoui, Mohamed; Nezli, Imed Eddine; Djelita, Belkhier; Boutoutaou, Djamel

2017-02-01

In arid and semi-arid areas, the protection and preservation of water resources is based on integrated resource managements, which will prove a fruitful way to deal with pollution and shortage of water-the source of life for man on Earth. Djelfa region, and particularly Ain El Bel, the potential water has not able to satisfy human needs,and agriculture, and industry. This article is a contribution to hydrodynamic modeling of the Barremian aquifer of Ain El Bel syncline, with "Modflow" software wich provides a deterministic two-dimensional numerical simulation in steady state and transient of underground water in the studied aquifer. The main results provided a better view of different scenarios to the piezometrics fluctuations. The established predictions show an alarming state of this aquifer, where the need for integrated management of groundwater resources is, to ensure sustainable development.

Assessment of trends in desertification: A proposed methodology

NASA Astrophysics Data System (ADS)

Dejong, Andrew Gordon

Desertification is most commonly accepted as "land degradation that occurs in arid, semi-arid, and dry sub-humid areas as a result of climatic variations and human activities." Primary influences include over-grazing, over-cultivation, exploitation of water resources and climate. Such influences lead to reduced productive capacity of land and potentially, desert-like conditions. Once degraded, the recovery of these natural systems may take decades or centuries. This research focused on two environments as case studies, Saskatchewan, Canada, and Bangladesh. Forecasts of desertification were depicted by integrating observed meteorological data, general circulation model (GCM) projections and a range of physical, biological and social indicators to create maps that depict the regions at greatest risk of desertification. Using GIS software, a thematic layer was employed for each indicator and they were integrated to form a single map of desertification. This methodology was found capable for identifying areas at risk of desertification in Saskatchewan and Bangladesh.

1994 conceptual model of the carbon tetrachloride contamination in the 200 West Area at the Hanford Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rohay, V.J.

1994-08-01

Between 1955 and 1973, a total of 363,000 to 580,000 L (577,000 to kg) of liquid carbon tetrachloride, in mixtures with other organic and aqueous, actinide-bearing fluids, were discharged to the soil column at three disposal facilities -- the 216-Z-9 Trench, the 216-Z-lA TiTe Field, and the 216-Z-18 Crib -- in the 200 West Area at the Hanford Site. In the mid-1980`s, dissolved carbon tetrachloride was found in the uppermost aquifer beneath the disposal facilities, and in late 1990, the US Environmental Protection Agency and the Washington State Department of Ecology requested that the US Department of Energy proceed withmore » planning and implementation of an expedited response action (ERA) to minimize additional carbon tetrachloride contamination of the groundwater. In February 1992, soil vapor extraction was initiated to remove carbon tetrachloride from the unsaturated zone beneath these disposal facilities. By May 1994, a total of 10,560 L (16,790 kg) of carbon tetrachloride had been removed, amounting to an estimated 2% of the discharged inventory. In the spring of 1991, the Volatile Organic Compounds -- Arid Integrated Demonstration (VOC-Arid ID) program selected the carbon tetrachloride-contaminated site for demonstration and deployment of new technologies for evaluation and cleanup of volatile organic compounds and associated contaminants in soils and groundwater at arid sites. Site investigations conducted in support of both the ERA and the VOC-Arid ID have been integrated because of their shared objective to refine the conceptual model of the site and to promote efficiency. Site characterization data collected in fiscal year 1993 have supported and led to refinement of the conceptual model of the carbon tetrachloride site.« less

Investigating Ecosystems Services in the Arid Southwest

EPA Science Inventory

The Southwest Ecosystem Services Project (SwESP) is an integrated, multi-disciplinary, multi-agency project focused on how to identify, characterize, and quantify the ecosystem services in the southwestern United States and northern Mexico. The southwestern landscape is highly d...

Integrated Spatial Models of Non Native Plant Invasion, Fire Risk, and Wildlife Habitat to Support Conservation of Military and Adjacent Lands in the Arid Southwest

DTIC Science & Technology

2015-12-01

FINAL REPORT Integrated spatial models of non-native plant invasion, fire risk, and wildlife habitat to support conservation of military and...as reflecting the official policy or position of the Department of Defense. Reference herein to any specific commercial product, process, or service...2. REPORT TYPE Final 3. DATES COVERED (From - To) 26/4/2010 – 25/10/2015 4. TITLE AND SUBTITLE Integrated Spatial Models of Non-Native Plant

Assessing the hydrogeochemical processes affecting groundwater pollution in arid areas using an integration of geochemical equilibrium and multivariate statistical techniques.

PubMed

El Alfy, Mohamed; Lashin, Aref; Abdalla, Fathy; Al-Bassam, Abdulaziz

2017-10-01

Rapid economic expansion poses serious problems for groundwater resources in arid areas, which typically have high rates of groundwater depletion. In this study, integration of hydrochemical investigations involving chemical and statistical analyses are conducted to assess the factors controlling hydrochemistry and potential pollution in an arid region. Fifty-four groundwater samples were collected from the Dhurma aquifer in Saudi Arabia, and twenty-one physicochemical variables were examined for each sample. Spatial patterns of salinity and nitrate were mapped using fitted variograms. The nitrate spatial distribution shows that nitrate pollution is a persistent problem affecting a wide area of the aquifer. The hydrochemical investigations and cluster analysis reveal four significant clusters of groundwater zones. Five main factors were extracted, which explain >77% of the total data variance. These factors indicated that the chemical characteristics of the groundwater were influenced by rock-water interactions and anthropogenic factors. The identified clusters and factors were validated with hydrochemical investigations. The geogenic factors include the dissolution of various minerals (calcite, aragonite, gypsum, anhydrite, halite and fluorite) and ion exchange processes. The anthropogenic factors include the impact of irrigation return flows and the application of potassium, nitrate, and phosphate fertilizers. Over time, these anthropogenic factors will most likely contribute to further declines in groundwater quality. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development and implementation of a monitoring and information system to increase water use efficiency in arid and semi-arid areas in Limarí, Central Chile (WEIN)

NASA Astrophysics Data System (ADS)

Berger, Erich; Balmert, David; Richter, Jürgen

2016-10-01

The project WEIN was funded by the Federal Ministry of Education and Research (BMBF | Berlin, Germany) in the framework of the high-tech strategy of Germany's program "KMU-Innovativ". The project started in 2012 and was completed in 2014. In the scope of the project, an integrated system for analysis, monitoring and information at river basin level was developed, which provides relevant information for all stakeholders that are concerned with water resource issues. The main objective of the project was to improve water use efficiency and hence ensure the agricultural production in the region. The pilot region, in which this system was implemented, is the semi-arid Limarí basin in Northern Central Chile. One of the main parts of the project was the development and implementation of a web- and app-based irrigation water ordering and accounting system for local farmers.

Airborne laser-diode-array illuminator assessment for the night vision's airborne mine-detection arid test

NASA Astrophysics Data System (ADS)

Stetson, Suzanne; Weber, Hadley; Crosby, Frank J.; Tinsley, Kenneth; Kloess, Edmund; Nevis, Andrew J.; Holloway, John H., Jr.; Witherspoon, Ned H.

2004-09-01

The Airborne Littoral Reconnaissance Technologies (ALRT) project has developed and tested a nighttime operational minefield detection capability using commercial off-the-shelf high-power Laser Diode Arrays (LDAs). The Coastal System Station"s ALRT project, under funding from the Office of Naval Research (ONR), has been designing, developing, integrating, and testing commercial arrays using a Cessna airborne platform over the last several years. This has led to the development of the Airborne Laser Diode Array Illuminator wide field-of-view (ALDAI-W) imaging test bed system. The ALRT project tested ALDAI-W at the Army"s Night Vision Lab"s Airborne Mine Detection Arid Test. By participating in Night Vision"s test, ALRT was able to collect initial prototype nighttime operational data using ALDAI-W, showing impressive results and pioneering the way for final test bed demonstration conducted in September 2003. This paper describes the ALDAI-W Arid Test and results, along with processing steps used to generate imagery.

EVALUATING LANDSCAPE CHANGE AND HYDROLOGICAL CONSEQUENCES IN A SEMI-ARID ENVIRONMENT

EPA Science Inventory

During the past two decades, important advances in the integration of remote imagery, computer processing, and spatial analysis technologies have been used to better understand the distribution of natural communities and ecosystems, and the ecological processes that affect these ...

Evaluating the influence of geo-environmental factors on gully erosion in a semi-arid region of Iran: An integrated framework.

PubMed

Rahmati, Omid; Tahmasebipour, Naser; Haghizadeh, Ali; Pourghasemi, Hamid Reza; Feizizadeh, Bakhtiar

2017-02-01

Despite the importance of soil erosion in sustainable development goals in arid and semi-arid areas, the study of the geo-environmental conditions and factors influencing gully erosion occurrence is rarely undertaken. As effort to this challenge, the main objective of this study is to apply an integrated approach of Geographic Object-Based Image Analysis (GEOBIA) together with high-spatial resolution imagery (SPOT-5) for detecting gully erosion features at the Kashkan-Poldokhtar watershed, Iran. We also aimed to apply a Conditional Probability (CP) model for establishing the spatial relationship between gullies and the Geo-Environmental Factors (GEFs). The gully erosion inventory map prepared using GEOBIA and field surveying was randomly partitioned into two subsets: (1) part 1 that contains 70% was used in the training phase of the CP model; (2) part 2 is a validation dataset (30%) for validation of the model and to confirm its accuracy. Prediction performances of the GEOBIA and CP model were checked by overall accuracy and Receiver Operating Characteristics (ROC) curve methods, respectively. In addition, the influence of all GEFs on gully erosion was evaluated by performing a sensitivity analysis model. The validation findings illustrated that overall accuracy for GEOBIA approach and the area under the ROC curve for the CP model were 92.4% and 89.9%, respectively. Also, based on sensitivity analysis, soil texture, drainage density, and lithology represent significantly effects on the gully erosion occurrence. This study has shown that the integrated framework can be successfully used for modeling gully erosion occurrence in a data-poor environment. Copyright © 2016 Elsevier B.V. All rights reserved.

INTEGRATING A LANDSCAPE HYDROLOGIC ANALYSIS FOR WATERSHED ASSESSMENT

EPA Science Inventory

Methods to provide linkages between a hydrologic modeling tool (AGW A) and landscape assessment tool (A TtILA) for determining the vulnerability of semi-arid landscapes to natural and human-induced landscape pattern changes have been developed. The objective of this study is to ...

Spatial patterns and natural recruitment of native shrubs in a semi-arid sandy land.

PubMed

Wu, Bo; Yang, Hongxiao

2013-01-01

Passive restoration depending on native shrubs is an attractive approach for restoring desertified landscapes in semi-arid sandy regions. We sought to understand the relationships between spatial patterns of native shrubs and their survival ability in sandy environments. Furthermore, we applied our results to better understand whether passive restoration is feasible for desertified landscapes in semi-arid sandy regions. The study was conducted in the semi-arid Mu Us sandy land of northern China with the native shrub Artemisia ordosica. We analyzed population structures and patterns of A. ordosica at the edges and centers of land patches where sand was stabilized by A. ordosica-dominated vegetation. Saplings were more aggregated than adults, and both were more aggregated at the patch edges than at the patch centers. At the patch edges, spatial association of the saplings with the adults was mostly positive at distances 0.3-6.6 m, and turned from positive to neutral, and even negative, at other distances. At the patch centers, the saplings were spaced almost randomly around the adults, and their distances from the adults did not seem to affect their locations. A greater number of A. ordosica individuals emerged at the patch edges than at the patch centers. Such patterns may have resulted from their integrative adjustment to specific conditions of soil water supply and sand drift intensity. These findings suggest that in semi-arid sandy regions, native shrubs that are well-adapted to local environments may serve as low-cost and competent ecological engineers that can promote the passive restoration of surrounding patches of mobile sandy land.

The influence of aridity and fire on Holocene prairie communities in the eastern Prairie Peninsula

USGS Publications Warehouse

Nelson, D.M.; Feng, S.H.; Grimm, E.C.; Curry, B. Brandon; Slate, J.E.

2006-01-01

The role of climate and fire in the development, maintenance, and species composition of prairie in the eastern axis of the tallgrass Prairie Peninsula intrigued early North American ecologists. However, evaluation of the long-standing hypotheses about the region's environmental history has been hampered by the scarcity of paleorecords. We conducted multiproxy analyses on early and middle Holocene sediments from two Illinois, USA, lakes to assess long-term climatic, vegetational, and fire variability in the region. Sediment mineral composition, carbonate ??18O, ostracode assemblages, and diatom assemblages were integrated to infer fluctuations in moisture availability. Pollen and charcoal ??13C were used to reconstruct vegetation composition, and charcoal influx was used to reconstruct fire. Results indicate that fire-sensitive trees (e.g., Ulmus, Ostrya, Fraxinus, and Acer saccharum) declined and prairie taxa expanded with increased aridity from 10 000 yr BP to 8500 yr BP. Between ???8500 yr BP and ???6200 yr BP, aridity declined, and prairie coexisted with fire-sensitive and fire-tolerant (e.g., Quercus and Carya) trees. After ???6200 yr BP, prairie taxa became dominant, although aridity was not more severe than it was around 8500 yr BP. Along with aridity, fire appears to have played an important role in the establishment and maintenance of prairie communities in the eastern Prairie Peninsula, consistent with the speculations of the early ecologists. Comparison of our data with results from elsewhere in the North American midcontinent indicates that spatial heterogeneity is a characteristic feature of climatic and vegetational variations on millennial time scales. ?? 2006 by the Ecological Society of America.

Modeling Ecosystem Services in an Arid Landscape Using the InVEST Tool

EPA Science Inventory

In this paper we describe the US Environmental Protection Agency’s Southwest Ecosystem Services Program (SwESP) initial efforts to use the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) tool to quantify and map the values of multiple ecosystem services in the S...

Integrated reclamation: Approaching ecological function?

Treesearch

Ann L. Hild; Nancy L. Shaw; Ginger B. Paige

2009-01-01

Attempts to reclaim arid and semiarid lands have traditionally targeted plant species composition. Much research attention has been directed to seeding rates, species mixes and timing of seeding. However, in order to attain functioning systems, attention to structure and process must compliment existing efforts. We ask how to use a systems approach to enhance...

Oasis dynamics change and its influence on landscape pattern on Jinta oasis in arid China from 1963a to 2010a: Integration of multi-source satellite images

NASA Astrophysics Data System (ADS)

Xie, Yuchu; Gong, Jie; Sun, Peng; Gou, Xiaohua

2014-12-01

As one of the vital research highlights of global land use and cover change, oasis change and its interaction with landscape pattern have been regarded as an important content of regional environmental change research in arid areas. Jinta oasis, a typical agricultural oasis characterized by its dramatic exploitation and use of water and land resources in Hexi corridor, northwest arid region in China, was selected as a case to study the spatiotemporal oasis change and its effects on oasis landscape pattern. Based on integration of Keyhole satellite photographs, KATE-200 photographs, Landsat MSS, TM and ETM+ images, we evaluated and analyzed the status, trend and spatial pattern change of Jinta oasis and the characteristics of landscape pattern change by a set of mathematical models and combined this information with landscape metrics and community surveys. During the period of 1963a-2010a, Jinta oasis expanded gradually with an area increase of 219.15 km2, and the conversion between oasis and desert was frequent with a state of “imbalance-balance-extreme imbalance conditions”. Moreover, most of the changes took place in the ecotone between oasis and desert and the interior of oasis due to the reclamation of abandoned land, such as Yangjingziwan and Xiba townships. Furthermore, the area, size and spatial distribution of oasis were influenced by human activities and resulted in fundamental changes of oasis landscape pattern. The fractal characteristics, dispersion degree and fragmentation of Jinta oasis decreased and the oasis landscape tended to be simple and uniform. Oasis change trajectories and its landscape pattern were mainly influenced by water resource utilization, policies (especially land policies), demographic factors, technological advancements, as well as regional economic development. We found that time series analysis of multi-source remote sensing images and the application of an oasis change model provided a useful approach to monitor oasis change over a long-term period in arid area. It is recommended that the government and farmers should pay more attention to the fragility of the natural system and the government should enhance the leading role of environmental considerations in the development process of oasis change, particularly with respect to the utilization of the limited water and land resources in arid China.

Physiological Stress in Koala Populations near the Arid Edge of Their Distribution

PubMed Central

Davies, Nicole Ashley; Gramotnev, Galina; McAlpine, Clive; Seabrook, Leonie; Baxter, Greg; Lunney, Daniel; Rhodes, Jonathan R.; Bradley, Adrian

2013-01-01

Recent research has shown that the ecology of stress has hitherto been neglected, but it is in fact an important influence on the distribution and numbers of wild vertebrates. Environmental changes have the potential to cause physiological stress that can affect population dynamics. Detailed information on the influence of environmental variables on glucocorticoid levels (a measure of stress) at the trailing edge of a species’ distribution can highlight stressors that potentially threaten species and thereby help explain how environmental challenges, such as climate change, will affect the survival of these populations. Rainfall determines leaf moisture and/or nutritional content, which in turn impacts on cortisol concentrations. We show that higher faecal cortisol metabolite (FCM) levels in koala populations at the trailing arid edge of their range in southwestern Queensland are associated with lower rainfall levels (especially rainfall from the previous two months), indicating an increase in physiological stress when moisture levels are low. These results show that koalas at the semi-arid, inland edge of their geographic range, will fail to cope with increasing aridity from climate change. The results demonstrate the importance of integrating physiological assessments into ecological studies to identify stressors that have the potential to compromise the long-term survival of threatened species. This finding points to the need for research to link these stressors to demographic decline to ensure a more comprehensive understanding of species’ responses to climate change. PMID:24265749

Toward irrigation retrieval by combining multi-sensor remote sensing data into a land surface model over a semi-arid region

NASA Astrophysics Data System (ADS)

Malbéteau, Y.; Lopez, O.; Houborg, R.; McCabe, M.

2017-12-01

Agriculture places considerable pressure on water resources, with the relationship between water availability and food production being critical for sustaining population growth. Monitoring water resources is particularly important in arid and semi-arid regions, where irrigation can represent up to 80% of the consumptive uses of water. In this context, it is necessary to optimize on-farm irrigation management by adjusting irrigation to crop water requirements throughout the growing season. However, in situ point measurements are not routinely available over extended areas and may not be representative at the field scale. Remote sensing approaches present as a cost-effective technique for mapping and monitoring broad areas. By taking advantage of multi-sensor remote sensing methodologies, such as those provided by MODIS, Landsat, Sentinel and Cubesats, we propose a new method to estimate irrigation input at pivot-scale. Here we explore the development of crop-water use estimates via these remote sensing data and integrate them into a land surface modeling framework, using a farm in Saudi Arabia as a demonstration of what can be achieved at larger scales.

Assessing Hydrologic Impacts of Land Configuration Changes Using an Integrated Hydrologic Model at the Rocky Flats Environmental Technology Site, Colorado

NASA Astrophysics Data System (ADS)

Prucha, R. H.; Dayton, C. S.; Hawley, C. M.

2002-12-01

The Rocky Flats Environmental Technology Site (RFETS) in Golden, Colorado, a former Department of Energy nuclear weapons manufacturing facility, is currently undergoing closure. The natural semi-arid interaction between surface and subsurface flow at RFETS is complex and complicated by the industrial modifications to the flow system. Using a substantial site data set, a distributed parameter, fully-integrated hydrologic model was developed to assess the hydrologic impact of different hypothetical site closure configurations on the current flow system and to better understand the integrated hydrologic behavior of the system. An integrated model with this level of detail has not been previously developed in a semi-arid area, and a unique, but comprehensive, approach was required to calibrate and validate the model. Several hypothetical scenarios were developed to simulate hydrologic effects of modifying different aspects of the site. For example, some of the simulated modifications included regrading the current land surface, changing the existing surface channel network, removing subsurface trenches and gravity drain flow systems, installing a slurry wall and geotechnical cover, changing the current vegetative cover, and converting existing buildings and pavement to permeable soil areas. The integrated flow model was developed using a rigorous physically-based code so that realistic design parameters can simulate these changes. This code also permitted evaluation of changes to complex integrated hydrologic system responses that included channelized and overland flow, pond levels, unsaturated zone storage, groundwater heads and flow directions, and integrated water balances for key areas. Results generally show that channel flow offsite decreases substantially for different scenarios, while groundwater heads generally increase within the reconfigured industrial area most of which is then discharged as evapotranspiration. These changes have significant implications to site closure and operation.

Spatial Patterns and Natural Recruitment of Native Shrubs in a Semi-arid Sandy Land

PubMed Central

Wu, Bo; Yang, Hongxiao

2013-01-01

Passive restoration depending on native shrubs is an attractive approach for restoring desertified landscapes in semi-arid sandy regions. We sought to understand the relationships between spatial patterns of native shrubs and their survival ability in sandy environments. Furthermore, we applied our results to better understand whether passive restoration is feasible for desertified landscapes in semi-arid sandy regions. The study was conducted in the semi-arid Mu Us sandy land of northern China with the native shrub Artemisia ordosica. We analyzed population structures and patterns of A. ordosica at the edges and centers of land patches where sand was stabilized by A. ordosica-dominated vegetation. Saplings were more aggregated than adults, and both were more aggregated at the patch edges than at the patch centers. At the patch edges, spatial association of the saplings with the adults was mostly positive at distances 0.3–6.6 m, and turned from positive to neutral, and even negative, at other distances. At the patch centers, the saplings were spaced almost randomly around the adults, and their distances from the adults did not seem to affect their locations. A greater number of A. ordosica individuals emerged at the patch edges than at the patch centers. Such patterns may have resulted from their integrative adjustment to specific conditions of soil water supply and sand drift intensity. These findings suggest that in semi-arid sandy regions, native shrubs that are well-adapted to local environments may serve as low-cost and competent ecological engineers that can promote the passive restoration of surrounding patches of mobile sandy land. PMID:23505489

Highly Arid Oasis Yield, Soil Mineral N Accumulation and N Balance in a Wheat-Cotton Rotation with Drip Irrigation and Mulching Film Management

PubMed Central

Lv, Jinling; Liu, Hua; Wang, Xihe; Li, Kaihui; Tian, Changyan; Liu, Xuejun

2016-01-01

Few systematic studies have been carried out on integrated N balance in extremely arid oasis agricultural areas. A two-year field experiment was conducted to evaluate the N input and output balances under long-term fertilization conditions. Five treatments were chosen, namely CK (no fertilizer), NPK, NPKS (10% straw return N and 90% chemical N), NPKM (one third urea-N, two thirds sheep manure) and NPKM+ (1.5 times NPKM). The results show an abundance of dry and wet N deposition (33 kg N ha-1 yr-1) in this area. All treatments (excluding CK) showed no significant difference in wheat production (P>0.05). NPKM gave higher cotton yields (P<0.05). In both crops, NPKM and NPKS treatments had a relatively higher N harvest index (NHI). 15N-labeled results reveal that the fertilizer N in all N treatments leached to<1 m depth and a high proportion of fertilizer-N remained in the top 60 cm of the soil profile. The NPKM+ treatment had the highest residual soil mineral N (Nmin, 558 kg Nd ha-1), and NPKM and NPKS treatments had relatively low soil Nmin values (275 and 293 kg N ha-1, respectively). Most of the treatments exhibited very high apparent N losses, especially the NPKM+ treatment (369kg N ha-1). Our arid research area had a strikingly high N loss compared to less arid agricultural areas. Nitrogen inputs therefore need careful reconsideration, especially the initial soil Nmin, fertilizer N inputs, dry and wet deposition, and appropriate organic and straw inputs which are all factors that must be taken into account under very arid conditions. PMID:27798654

Irrigation in the arid regions of Tunisia impacts the abundance and apparent density of sand fly vectors of Leishmania infantum

PubMed Central

Barhoumi, Walid; Qualls, Whitney A.; Archer, Reginald; Fuller, Douglas O.; Chelbi, Ifhem; Cherni, Saifedine; Derbali, Mohamed; Arheart, Kristopher L.; Zhioua, Elyes; Beier, John C.

2015-01-01

The distribution expansion of important human visceral leishmaniasis (HVL) and sporadic cutaneous leishmaniasis (SCL) vector species, Phlebotomus perfiliewi and P. perniciosus, throughout central Tunisia is a major public health concern. This study was designed to investigate if the expansion of irrigation influences the abundance of sand fly species potentially involved in the transmission of HVL and SCL located in arid bioclimatic regions. Geographic and remote sensing approaches were used to predict the density of visceral leishmaniasis vectors in Tunisia. Entomological investigations were performed in the governorate of Sidi Bouzid, located in the arid bioclimatic region of Tunisia. In 2012, sand flies were collected by CDC light traps located at nine irrigated and nine non-irrigated sites to determine species abundance. Eight species in two genera were collected. Among sand flies of the subgenus Larroussius, P. perfiliewi was the only species collected significantly more in irrigated areas. Trap data were then used to develop Poisson regression models to map the apparent density of important sand fly species as a function of different environmental covariates including climate and vegetation density. The density of P. perfiliewi is predicted to be moderately high in the arid regions. These results highlight that the abundance of P. perfiliewi is associated with the development of irrigated areas and suggests that the expansion of this species will continue to more arid areas of the country as irrigation sites continue to be developed in the region. The continued increase in irrigated areas in the Middle East and North Africa region deserves attention, as it is associated with the spread of L. infantum vector P. perfiliewi. Integrated vector management strategies targeting irrigation structures to reduce sand fly vector populations should be evaluated in light of these findings. PMID:25447265

The Soil Program of the Restoration Seedbank Initiative: addressing knowledge gaps in degraded soils for use in dryland restoration

NASA Astrophysics Data System (ADS)

Muñoz-Rojas, Miriam; Bateman, Amber; Erickson, Todd E.; Turner, Shane; Merritt, David J.

2017-04-01

Global environmental changes and other anthropogenic impacts are rapidly transforming the structure and functioning of ecosystems worldwide. These changes are leading to land degradation with an estimated 25 % of the global land surface being affected. Landscape-scale restoration of these degraded ecosystems has therefore been recognised globally as an international priority. In the resource-rich biodiverse semi-arid Pilbara region of north-west Western Australia hundreds of thousands of hectares are disturbed due to established and emerging iron-ore mine operations. At this scale, the need to develop cost-effective large-scale solutions to restore these landscapes becomes imperative to preserve biodiversity and achieve functionality and sustainability of these ecosystems. The Restoration Seedbank Initiative (RSB) (http://www.plants.uwa.edu.au/ research/restoration-seedbank-initiative) is a five-year multidisciplinary research project that aims to build knowledge and design strategies to restore mine-impacted landscapes in the Pilbara and other arid and semi-arid landscapes worldwide (Kildiseheva et al., 2016). The RSB comprises four research programs that focus on seedbank management and curation, seed storage, seed enhancement, and the use of alternative soil substrates (soil or growing medium program) respectively. These multi-disciplinary programs address the significant challenges of landscape scale restoration in arid systems. In the soil program we follow an integrated approach that includes the characterization of undisturbed ecosystems, assessment of restored soils with the use of soil quality indicators, and design of alternative soil substrates to support the establishment of native plant communities. A series of glasshouse studies and field trials have been conducted in the last three years to advance our knowledge on soil limitations and to provide solutions to effectively overcome these challenges in arid ecosystem restoration. These studies include (i) the determination of ecophysiological indicators influencing drought responses of arid native plants in reconstructed soils (Bateman et al, 2016), ii) the analysis of the influence of climate and edaphic factors in the recruitment of arid zone seedlings (Muñoz-Rojas et al., 2016a) and (ii) the evaluation of soil physicochemical and microbiological indicators to assess functionality of restored soils in degraded semiarid ecosystems (Muñoz-Rojas et al., 2016b). Here, we summarize our latest results in the soil program of the RSB, and propose recommendations for integrating soil science in cost-effective landscape-scale restoration practices in ecosystems worldwide. References Bateman A, Lewandrowski W, Stevens J, Muñoz-Rojas M (2016b) Ecophysiological indicators to assess drought responses of arid zone native seedlings in reconstructed soils. Land Degradation & Development, in press, DOI: 10.1002/ldr.2660. Kildisheva OA, Erickson TE, Merritt DJ, Dixon KW (2016), Setting the scene for dryland recovery: an overview and key findings from a workshop targeting seed-based restoration. Restoration Ecology 24, S36-S42. Muñoz-Rojas M, Erickson TE, Dixon KW, Merritt DJ (2016) Soil quality indicators to assess functionality of restored soils in degraded semiarid ecosystems. Restoration Ecology 24, S43-S52. DOI: 10.1111/rec.12368 Muñoz-Rojas M, Erickson TE, Martini DC, Dixon KW, Merritt DJ (2016a) Climate and soil factors influencing seedling recruitment of plant species used for dryland restoration. SOIL 2, 287-298. DOI: 10.5194/soil-2016-25

ARID1B is a specific vulnerability in ARID1A-mutant cancers

PubMed Central

Helming, Katherine C.; Wang, Xiaofeng; Wilson, Boris G.; Vazquez, Francisca; Haswell, Jeffrey R.; Manchester, Haley E.; Kim, Youngha; Kryukov, Gregory V.; Ghandi, Mahmoud; Aguirre, Andrew J.; Jagani, Zainab; Wang, Zhong; Garraway, Levi A.; Hahn, William C.; Roberts, Charles W. M.

2014-01-01

Summary Recent studies have revealed that ARID1A is frequently mutated across a wide variety of human cancers and also has bona fide tumor suppressor properties. Consequently, identification of vulnerabilities conferred by ARID1A mutation would have major relevance for human cancer. Here, using a broad screening approach, we identify ARID1B, a related but mutually exclusive homolog of ARID1A in the SWI/SNF chromatin remodeling complex, as the number one gene preferentially required for the survival of ARID1A-mutant cancer cell lines. We show that loss of ARID1B in ARID1A-deficient backgrounds destabilizes SWI/SNF and impairs proliferation. Intriguingly, we also find that ARID1A and ARID1B are frequently co-mutated in cancer, but that ARID1A-deficient cancers retain at least one ARID1B allele. These results suggest that loss of ARID1A and ARID1B alleles cooperatively promotes cancer formation but also results in a unique functional dependence. The results further identify ARID1B as a potential therapeutic target for ARID1A-mutant cancers. PMID:24562383

ARID1B is a specific vulnerability in ARID1A-mutant cancers.

PubMed

Helming, Katherine C; Wang, Xiaofeng; Wilson, Boris G; Vazquez, Francisca; Haswell, Jeffrey R; Manchester, Haley E; Kim, Youngha; Kryukov, Gregory V; Ghandi, Mahmoud; Aguirre, Andrew J; Jagani, Zainab; Wang, Zhong; Garraway, Levi A; Hahn, William C; Roberts, Charles W M

2014-03-01

Recent studies have revealed that ARID1A, encoding AT-rich interactive domain 1A (SWI-like), is frequently mutated across a variety of human cancers and also has bona fide tumor suppressor properties. Consequently, identification of vulnerabilities conferred by ARID1A mutation would have major relevance for human cancer. Here, using a broad screening approach, we identify ARID1B, an ARID1A homolog whose gene product is mutually exclusive with ARID1A in SWI/SNF complexes, as the number 1 gene preferentially required for the survival of ARID1A-mutant cancer cell lines. We show that loss of ARID1B in ARID1A-deficient backgrounds destabilizes SWI/SNF and impairs proliferation in both cancer cells and primary cells. We also find that ARID1A and ARID1B are frequently co-mutated in cancer but that ARID1A-deficient cancers retain at least one functional ARID1B allele. These results suggest that loss of ARID1A and ARID1B alleles cooperatively promotes cancer formation but also results in a unique functional dependence. The results further identify ARID1B as a potential therapeutic target for ARID1A-mutant cancers.

Image processing and classification procedures for analysis of sub-decimeter imagery acquired with an unmanned aircraft over arid rangelands

USDA-ARS?s Scientific Manuscript database

Using five centimeter resolution images acquired with an unmanned aircraft system (UAS), we developed and evaluated an image processing workflow that included the integration of resolution-appropriate field sampling, feature selection, object-based image analysis, and processing approaches for UAS i...

Linking community and national park development: A case from the Dominican Republic

Treesearch

John Schelhas; Ruth E. Sherman; Timothy J. Fahey; James P. Lassoie

2002-01-01

National parks have complex relationships with local communities that impact both conservation success and community well-being. Integrated conservation arid development projects have been a key approach to managing these relationships, although their effectiveness has been increasingly questioned. Park-people relationships of the Armando Bermudez National Park in the...

Stormwater Management for TMDLs in an Arid Climate: A Case Study Application of SUSTAIN in Albuquerque, New Mexico - report

EPA Science Inventory

This case study for the Albuquerque, New Mexico area was conducted under contract with the U.S. Environmental Protection Agency (EPA) Office of Research and Development using the System for Urban Stormwater Treatment and Integration Analysis (SUSTAIN). The effort focuses on inve...

Soil, plant, and structural considerations for surface barriers in arid environments: Application of results from studies in the Mojave Desert near Beatty, Nevada

USGS Publications Warehouse

Andraski, Brian J.; Prudic, David E.; ,

1997-01-01

The suitability of a waste-burial site depends on hydrologic processes that can affect the near-surface water balance. In addition, the loss of burial trench integrity by erosion and subsidence of trench covers may increase the likelihood of infiltration and percolation, thereby reducing the effectiveness of the site in isolating waste. Although the main components of the water balance may be defined, direct measurements can be difficult, and actual data for specific locations are seldom available. A prevalent assumption is that little or no precipitation will percolate to buried wastes at an arid site. Thick unsaturated zones, which are common to arid regions, are thought to slow water movement and minimize the risk of waste migration to the underlying water table. Thus, reliance is commonly placed on the natural system to isolate contaminants at waste-burial sites in the arid West.Few data are available to test assumptions about the natural soil-water flow systems at arid sites, and even less is known about how the natural processes are altered by construction of a waste-burial facility. The lack of data is the result of technical complexity of hydraulic characterization of the dry, stony soils, and insufficient field studies that account for the extreme temporal and spatial variations in precipitation, soils, and plants in arid regions. In 1976, the U.S. Geological Survey (USGS) began a long-term study at a waste site in the Mojave Desert. This paper summarizes the findings of ongoing investigations done under natural-site and waste-burial conditions, and discusses how this information may be applied to the design of surface barriers for waste sites in arid environments.The waste-burial site is in one of the most arid parts of the United States and is about 40 km northeast of Death Valley, near Beatty, Nev. (Figure 1). Precipitation averaged 108 mm/yr during 1981-1992. The water table is 85-115 m below land surface (Fischer, 1992). Sediments are largely alluvial and fluvial deposits (Nichols, 1987). Vegetation is sparse; creosote bush is the dominant species. The waste facility has been used for burial of low-level radioactive waste (1962-1992) and hazardous chemical waste (1970 to present). Burial-trench construction includes excavation of native soil, emplacement of waste, and backfilling with previously stockpiled soil. Only the most recently closed hazardous-waste trench (1991) incorporates a plastic liner in the cover. The surfaces of completed burial trenches and perimeter areas are kept free of vegetation.

Groundwater quality assessment in semi-arid regions using integrated approaches: the case of Grombalia aquifer (NE Tunisia).

PubMed

Kammoun, Siwar; Trabelsi, Rim; Re, Viviana; Zouari, Kamel; Henchiri, Jihed

2018-01-19

As many arid and semi-arid regions in the Mediterranean Basin, the Grombalia coastal aquifer (NE Tunisia) is affected by severe groundwater exploitation and contamination. Therefore, quality assessments are becoming increasingly important as the long-term protection of water resources is at stake. Multidisciplinary investigations, like the one presented in this paper, are particularly effective in identifying the different origins of mineralization within an aquifer and investigating the impact of anthropogenic activities on groundwater quality. An integrated assessment, focused on the combined use of geostatistical, geochemical and isotopic (δ 18 O, δ 2 H and 3 H) tools, was performed in the Grombalia aquifer between February and March 2014. The overall goal was to study the main processes controlling aquifer salinization, with special focus to nitrate contamination. Results indicate a persisting deterioration of water quality over the whole basin except the south-eastern zone juxtaposing the recharge area of the aquifer. Nitrate contents exceed the drinking water standard (50 mg/l) in 70% of groundwater samples, mainly due to the excessive use of fertilizers and urban activities. Stable isotope measurements showed the contribution of modern rainwater to aquifer recharge and proved the presence of evaporation contributing to the salinity increase. Tritium values of groundwater samples suggested two hypotheses: the existence of mixture between old and recent water or/and the existence of two recharge periods of the aquifer, pre- and post-nuclear weapons test. Principal component analysis confirmed the geochemical interpretation, highlighting that water-rock interaction evaporation effect and intensive anthropogenic activities constitute the main processes controlling the regional groundwater mineralization.

Mitigating Climate Change in the Arid Lands of Namibia

NASA Astrophysics Data System (ADS)

Schneider, Martin B.; Sorensen, Marten

2014-05-01

Mitigating Climate Change in the Arid Lands of Namibia Namibia is the most arid country south of the Sahara, with scarce rainfall and perennial rivers only at its borders, > 80% of the area relies solely on groundwater. This has had devastating economic effects limiting opportunities for sustainable rural livelihoods that keep the population majority living below the World Bank poverty line (IFAD, 2013). A primary example of climatic variability which affects agrarian productivity is increased bush encroachment of Namibia's arid grazing land. The result has been a severe biodiversity loss, increased desertification and diminished water-use efficiency and underground water tables. Given these factors, Namibia's arid lands provide a unique opportunity to assess and test innovative / appropriate adaptation and mitigation strategies. Working toward sustainable management, restoration, and maintenance of balanced, resilient arid ecosystems in Namibia will also be a means to support and expand economic sectors incl. opportunities for job creation and potentially provide a model for similar arid regions. Main vegetation zones are: desert (46%), savannah (37%), and dry woodlands and forests (17%), i.e. < 2% is arable. Also, government protected areas cover 13.8% of the land surface. Current climate models suggest that Namibia faces serious risks, e.g. increased temperatures, hyper-arid conditions, and more frequent and extreme weather events (Pamaccafrica, 2013). The Namibian government, civil society organizations, and the scientific community attempt to address these risks and a certain level of institutional and human capacities are already in place. However, overall climate variability appears significantly higher than current plans and policies take into account. To improve livelihoods, reduce poverty, and food insecurity for rural Namibians in marginal/hyper-arid lands through sustainable climate change adaptation these objectives will be implemented: 1. Identify, assess and evaluate indigenous management strategies currently used by rural communities. 2. Capture and assess cultural and gender dimensions of management strategies within stakeholder groups using participatory approaches. 3. Determine science-based alternatives for adaptive land management strategies and test their acceptability to local communities and within the current policy framework. 4. Integrate identified indigenous knowledge with appropriate science and new emerging technologies to develop a training toolkit of effective strategies relevant to all stakeholders. 5. Utilize training sessions, education workshops, curriculum revisions, and appropriate information and communication technologies (ICTs) including social media outlets to disseminate the toolkit strategies. 6. Apply a modified logic model approach within a value chain analysis process to evaluate program effectiveness and impacts at both formative and summative levels. 7. Disseminate lessons learned, and results achieved to the international community through all recognized knowledge sharing outlets. Goal and objectives - accomplished by implementation of a variety of integrated action steps each linked to specific performance impact measures that assess short, medium, and long-term impacts (modified logic model). Impact measures to be monitored using formative and summative techniques within a value chain analysis process. Improved teaching and training practices, research outputs and incorporation of value chain approaches will be tracked to capture trend data in these areas. New means of ongoing and interactive communication to be established with local communities incl. use of modern media. Management strategies need to include: 1) reduced bush encroachment and biomass conversion into electricity; 2) managing costs of water catchments; 3) improving rangeland management efficiencies; 4) improved provisions of water to off-farm economic needs; 5) contribute to provision of energy supply; 6) restore and protect biodiversity and; 7) providing employment. IFAD (2013) Rural poverty Portal - Rural poverty in Namibia [http://www.ruralpovertyportal.org/country/home/tags/namibia#] Pamaccafrica (2013) Namibia commits to fight desertification [http://pamaccafrica.blogspot.dk/2013/06/namibia-commits-to-fight-desertification.html

Developing ecological fingerprints for ecoclimatic zones in Australian drylands to inform land restoration

NASA Astrophysics Data System (ADS)

Muñoz-Rojas, Miriam; Escribano Velasco, Paula; Garcia, Monica

2017-04-01

With more than 25% of the global surface affected by land degradation processes, there is an urgent need to restore disturbed ecosystems worldwide. Increased arid conditions in projected scenarios of climate change need to be acknowledged in restoration programs; this is particularly critical in dryland ecosystems where significant changes are expected in their structure and functioning worldwide. Australia is the driest inhabited continent in the world with 70% of the country classified as arid or semi-arid (average annual rainfall of 250 mm or less). Moreover, Australia has undergone massive land-use changes in the last decades and the landscape is highly degraded and fragmented. These conditions position the country as one of the climate change vulnerable "hot spots" globally. In this research, we aim to evaluate a broad range of ecological indicators in natural Australian dryland ecosystems (both disturbed and undisturbed) that allow us to i) identify those areas most vulnerable to potential and environmental changes and ii) tracking the effectiveness of restoration practices. The most relevant indicators will be selected to inform decision-making in the design of management strategies to address the potential negative effects of climate change and further land degradation. These ecological indicators will be measured in 10 Australian ecoclimatic units that combine the main vegetation functional types and climate zones based on the aridity index as follows: hum¬mock grasslands in the hyper-arid zone; acacia shrublands, hummock grasslands and tussock grasslands in the arid zone; chenopod shrubs, hummock grasslands, mallee woodlands and tussock grasslands in the semi-arid zone and eucalyptus and acacia forest in the dry sub-humid zone. A set of fingerprints will be created to diagnose each ecoclimatic unit using a wide range of ecological indicators related with the ecosystem's composition, structure and function. We will combine novel technologies and methodologies on remote sensing data acquisition of the land surface (e.g. high spatial resolution hyperspectral imaging), satellite and climate time series, biophyisical models and field measurements of soil physicochemical and microbiological properties, plant ecophysiological parameters and biogeochemical processes. This multidisciplinary approach will allow us to establish the fingerprints more sensitive to degradation processes and recovery. The outcome of this research will provide a valuable tool to stakeholders and managers on conserva¬tion and restoration that will allow integrating adequate measures of climate change adaptation and mitigation in environmental planning.

Topography alters tree growth–climate relationships in a semi-arid forested catchment

DOE PAGES

Adams, Hallie R.; Barnard, Holly R.; Loomis, Alexander K.

2014-11-26

Topography and climate play an integral role in the spatial variability and annual dynamics of aboveground carbon sequestration. Despite knowledge of vegetation–climate–topography relationships on the landscape and hillslope scales, little is known about the influence of complex terrain coupled with hydrologic and topoclimatic variation on tree growth and physiology at the catchment scale. Climate change predictions for the semi-arid, western United States include increased temperatures, more frequent and extreme drought events, and decreases in snowpack, all of which put forests at risk of drought induced mortality and enhanced susceptibility to disturbance events. In this study, we determine how species-specific treemore » growth patterns and water use efficiency respond to interannual climate variability and how this response varies with topographic position. We found that Pinus contorta and Pinus ponderosa both show significant decreases in growth with water-limiting climate conditions, but complex terrain mediates this response by controlling moisture conditions in variable topoclimates. Foliar carbon isotope analyses show increased water use efficiency during drought for Pinus contorta, but indicate no significant difference in water use efficiency of Pinus ponderosa between a drought year and a non-drought year. The responses of the two pine species to climate indicate that semi-arid forests are especially susceptible to changes and risks posed by climate change and that topographic variability will likely play a significant role in determining the future vegetation patterns of semi-arid systems.« less

Holocene aridification of India

USGS Publications Warehouse

Ponton, C.; Giosan, L.; Eglinton, T.I.; Fuller, D.Q.; Johnson, J.E.; Kumar, P.; Collett, T.S.

2012-01-01

Spanning a latitudinal range typical for deserts, the Indian peninsula is fertile instead and sustains over a billion people through monsoonal rains. Despite the strong link between climate and society, our knowledge of the long-term monsoon variability is incomplete over the Indian subcontinent. Here we reconstruct the Holocene paleoclimate in the core monsoon zone (CMZ) of the Indian peninsula using a sediment core recovered offshore from the mouth of Godavari River. Carbon isotopes of sedimentary leaf waxes provide an integrated and regionally extensive record of the flora in the CMZ and document a gradual increase in aridity-adapted vegetation from ???4,000 until 1,700 years ago followed by the persistence of aridity-adapted plants after that. The oxygen isotopic composition of planktonic foraminifer Globigerinoides ruber detects unprecedented high salinity events in the Bay of Bengal over the last 3,000 years, and especially after 1,700 years ago, which suggest that the CMZ aridification intensified in the late Holocene through a series of sub-millennial dry episodes. Cultural changes occurred across the Indian subcontinent as the climate became more arid after ???4,000 years. Sedentary agriculture took hold in the drying central and south India, while the urban Harappan civilization collapsed in the already arid Indus basin. The establishment of a more variable hydroclimate over the last ca. 1,700 years may have led to the rapid proliferation of water-conservation technology in south India. Copyright 2012 by the American Geophysical Union.

Humans in changing shrubland ecosystems

Treesearch

Rosemary L. Pendleton; Stanley G. Kitchen; Andres F. Cibils

2014-01-01

Emerging arid-land research and management approaches are increasingly shaped by the recognition of the fact that humans are an integral part of ecosystems. The thrust to study the coupled natural-human dynamics of such systems1 and the growing awareness of the social-ecological nature of rangeland ecosystems2 are prompting a shift in the way we think about current and...

Prospects for phenological monitoring in an arid southwestern U.S. rangeland using field observations with hyperspatial and moderate resolution imagery

USDA-ARS?s Scientific Manuscript database

Relating field observations of plant phenological events to remotely sensed depictions of land surface phenology remains a challenge to the vertical integration of data from disparate sources. This research conducted at the Jornada Basin Long-Term Ecological Research site in southern New Mexico cap...

Prospects for phenological monitoring in an arid southwestern U.S. rangeland using field observations with hyperspatial and moderate resolution imagery

USDA-ARS?s Scientific Manuscript database

Relating field observations of plan phonological events to remotely sensed depictions of land surface phenology remains a challenge to the vertical integration of data from disparate sources. This research conducted at the Jornada Basin Long-Term Ecological Research site in southern New Mexico capit...

Hydraulic integration and shrub growth form linked across continental aridity gradients

Treesearch

H. Jochen Schenk; Christine M. Goedhart; Marisa Nordenstahl; Hugo I. Martinez Cabrera; Cynthia S. Jones

2008-01-01

Both engineered hydraulic systems and plant hydraulic systems are protected against failure by resistance, reparability, and redundancy. A basic rule of reliability engineering is that the level of independent redundancy should increase with increasing risk of fatal system failure. Here we show that hydraulic systems of plants function as predicted by this engineering...

Modelling hydrologic and hydrodynamic processes in basins with large semi-arid wetlands

NASA Astrophysics Data System (ADS)

Fleischmann, Ayan; Siqueira, Vinícius; Paris, Adrien; Collischonn, Walter; Paiva, Rodrigo; Pontes, Paulo; Crétaux, Jean-François; Bergé-Nguyen, Muriel; Biancamaria, Sylvain; Gosset, Marielle; Calmant, Stephane; Tanimoun, Bachir

2018-06-01

Hydrological and hydrodynamic models are core tools for simulation of large basins and complex river systems associated to wetlands. Recent studies have pointed towards the importance of online coupling strategies, representing feedbacks between floodplain inundation and vertical hydrology. Especially across semi-arid regions, soil-floodplain interactions can be strong. In this study, we included a two-way coupling scheme in a large scale hydrological-hydrodynamic model (MGB) and tested different model structures, in order to assess which processes are important to be simulated in large semi-arid wetlands and how these processes interact with water budget components. To demonstrate benefits from this coupling over a validation case, the model was applied to the Upper Niger River basin encompassing the Niger Inner Delta, a vast semi-arid wetland in the Sahel Desert. Simulation was carried out from 1999 to 2014 with daily TMPA 3B42 precipitation as forcing, using both in-situ and remotely sensed data for calibration and validation. Model outputs were in good agreement with discharge and water levels at stations both upstream and downstream of the Inner Delta (Nash-Sutcliffe Efficiency (NSE) >0.6 for most gauges), as well as for flooded areas within the Delta region (NSE = 0.6; r = 0.85). Model estimates of annual water losses across the Delta varied between 20.1 and 30.6 km3/yr, while annual evapotranspiration ranged between 760 mm/yr and 1130 mm/yr. Evaluation of model structure indicated that representation of both floodplain channels hydrodynamics (storage, bifurcations, lateral connections) and vertical hydrological processes (floodplain water infiltration into soil column; evapotranspiration from soil and vegetation and evaporation of open water) are necessary to correctly simulate flood wave attenuation and evapotranspiration along the basin. Two-way coupled models are necessary to better understand processes in large semi-arid wetlands. Finally, such coupled hydrologic and hydrodynamic modelling proves to be an important tool for integrated evaluation of hydrological processes in such poorly gauged, large scale basins. We hope that this model application provides new ways forward for large scale model development in such systems, involving semi-arid regions and complex floodplains.

Performance of fenugreek bioinoculated with Rhizobium meliloti strains under semi-arid condition.

PubMed

Singh, N K; Patel, D B

2016-01-01

Rhizobium meliloti strains were isolated from the fields of S.D. Agricultural University (Gujarat, India) and were maintained in the Congo Red Yeast Extract Mannitol Agar medium. These strains were tested for their effectiveness for fenugreek crop grown under semi-arid condition. Among the six Rhizobium strains, FRS-7 strain showed best plant growth parameters like shoot length, shoot dry weight, shoot total nitrogen, root length, root dry weight, root total nitrogen, seed yield, 1000 grain weight, number of root nodules, and nodules fresh and dry weight. The performance of this strain was better as compared to 20 kgN ha(-1) treatment through urea and was even far better over control plot. Seed yields obtained with FRS-7 during two years were 10.14 and 9.66 q ha(-1); which was about 36.8% and 45.9% high over control. This strain resulted in saving of about 20 kgN ha(-1) accompanied with better crop yield and soil health. Results of the present experiments can be utilized in integrated nutrient management for cultivation of fenugreek in semi-arid areas to provide sustainability to agricultural productivity in such regions.

Spatial and temporal variations of aridity indices in Iraq

NASA Astrophysics Data System (ADS)

Şarlak, Nermin; Mahmood Agha, Omar M. A.

2017-06-01

This study investigates the spatial and temporal variations of the aridity indices to reveal the desertification vulnerability of Iraq region. Relying on temperature and precipitation data taken from 28 meteorological stations for 31 years, the study aims to determine (1) dry land types and their delineating boundaries and (2) temporal change in aridity conditions in Iraq. Lang's aridity (Im), De Martonne's aridity (Am), United Nations Environmental Program (UNEP) aridity (AIu), and Erinç aridity (IE) indices were selected in this study because of the scarcity of the observed data. The analysis of the spatial variation of aridity indices exhibited that the arid and semi-arid regions cover about 97% of the country's areas. As for temporal variations, it was observed that the aridity indices tend to decrease (statistically significant or not) for all stations. The cumulative sum charts (CUSUMs) were applied to detect the year on which the climate pattern of aridity indices had changed from one pattern to another. The abrupt change point was detected around year 1997 for the majority of the stations. Thus, the spatial and temporal aridity characteristics in Iraq were examined for the two periods 1980-1997 and 1998-2011 (before and after the change-point year) to observe the influence of abrupt change point on aridity phenomena. The spatial variation after 1997 was observed from semi-arid (dry sub humid) to arid (semi-arid) especially at the stations located in northern Iraq, while hyper-arid and arid climatic conditions were still dominant over southern and central Iraq. Besides, the negative temporal variations of the two periods 1980-1997 and 1998-2011 were obtained for almost every station. As a result, it was emphasized that Iraq region, like other Middle East regions, has become drier after 1997. The observed reduction in precipitation and increase in temperature for this region seem to make the situation worse in future.

Problems and Prospects of SWAT Model Application on an Arid/Semi-Arid Watershed in Arizona

EPA Science Inventory

In arid/semi-arid regions, precipitation mainly occurs during two periods: long-duration, low-intensity rainfall in winter; and short-duration, high-intensity rainfall in summer. Watersheds in arid/semi-arid regions often release water almost immediately after a storm due to spa...

Alterations in flowering strategies and sexual allocation of Caragana stenophylla along a climatic aridity gradient.

PubMed

Xie, Lina; Guo, Hongyu; Ma, Chengcang

2016-09-15

Plant can alter reproductive strategies for adaptation to different environments. However, alterations in flowering strategies and sexual allocation for the same species growing in different environments still remain unclear. We examined the sexual reproduction parameters of Caragana stenophylla across four climatic zones from semi-arid, arid, very arid, to intensively arid zones in the Inner Mongolia Steppe, China. Under the relatively favorable climatic conditions of semi-arid zone, C. stenophylla took a K-strategy for flowering (fewer but bigger flowers, and higher seed set). In contrast, under the harsher climatic conditions of intensively arid zone, C. stenophylla took an r-strategy for flowering (more but smaller flowers, and lower seed set). In arid and very arid zones, C. stenophylla exhibited intermediate flowering strategies between K- and r-strategies. In semi-arid, arid and very arid zones, sexual allocation and sexual allocation efficiency (SAE) of C. stenophylla were high, and the population recruitment might be mainly through sexual reproduction; in intensively arid zone, however, sexual allocation and SAE were very low, seed production was very limited, and clonal reproduction might compensate for the decrease in sexual reproduction. Our results suggested that C. stenophylla adapted to the climatic aridity gradient by alterations in flowering strategies and reproductive allocation.

The Tumor Suppressor ARID1A Controls Global Transcription via Pausing of RNA Polymerase II.

PubMed

Trizzino, Marco; Barbieri, Elisa; Petracovici, Ana; Wu, Shuai; Welsh, Sarah A; Owens, Tori A; Licciulli, Silvia; Zhang, Rugang; Gardini, Alessandro

2018-06-26

AT-rich interactive domain-containing proteins 1A and 1B (ARID1A and ARID1B) are mutually exclusive subunits of the chromatin remodeler SWI/SNF. ARID1A is the most frequently mutated chromatin regulator across all cancers, and ovarian clear cell carcinoma (OCCC) carries the highest prevalence of ARID1A mutations (∼57%). Despite evidence implicating ARID1A in tumorigenesis, the mechanism remains elusive. Here, we demonstrate that ARID1A binds active regulatory elements in OCCC. Depletion of ARID1A represses RNA polymerase II (RNAPII) transcription but results in modest changes to accessibility. Specifically, pausing of RNAPII is severely impaired after loss of ARID1A. Compromised pausing results in transcriptional dysregulation of active genes, which is compensated by upregulation of ARID1B. However, a subset of ARID1A-dependent genes is not rescued by ARID1B, including many p53 and estrogen receptor (ESR1) targets. Our results provide insight into ARID1A-mediated tumorigenesis and unveil functions of SWI/SNF in modulating RNAPII dynamics. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

A "total parameter estimation" method in the varification of distributed hydrological models

NASA Astrophysics Data System (ADS)

Wang, M.; Qin, D.; Wang, H.

2011-12-01

Conventionally hydrological models are used for runoff or flood forecasting, hence the determination of model parameters are common estimated based on discharge measurements at the catchment outlets. With the advancement in hydrological sciences and computer technology, distributed hydrological models based on the physical mechanism such as SWAT, MIKESHE, and WEP, have gradually become the mainstream models in hydrology sciences. However, the assessments of distributed hydrological models and model parameter determination still rely on runoff and occasionally, groundwater level measurements. It is essential in many countries, including China, to understand the local and regional water cycle: not only do we need to simulate the runoff generation process and for flood forecasting in wet areas, we also need to grasp the water cycle pathways and consumption process of transformation in arid and semi-arid regions for the conservation and integrated water resources management. As distributed hydrological model can simulate physical processes within a catchment, we can get a more realistic representation of the actual water cycle within the simulation model. Runoff is the combined result of various hydrological processes, using runoff for parameter estimation alone is inherits problematic and difficult to assess the accuracy. In particular, in the arid areas, such as the Haihe River Basin in China, runoff accounted for only 17% of the rainfall, and very concentrated during the rainy season from June to August each year. During other months, many of the perennial rivers within the river basin dry up. Thus using single runoff simulation does not fully utilize the distributed hydrological model in arid and semi-arid regions. This paper proposed a "total parameter estimation" method to verify the distributed hydrological models within various water cycle processes, including runoff, evapotranspiration, groundwater, and soil water; and apply it to the Haihe river basin in China. The application results demonstrate that this comprehensive testing method is very useful in the development of a distributed hydrological model and it provides a new way of thinking in hydrological sciences.

Implications of mitochondrial DNA polyphyly in two ecologically undifferentiated but morphologically distinct migratory birds, the masked and white-browed woodswallows Artamus spp. of inland Australia

USGS Publications Warehouse

Joseph, Leo; Wilke, Thomas; Ten Have, Jose; Chesser, R. Terry

2006-01-01

The white-browed woodswallow Artamus superciliosus and masked woodswallow A. personatus(Passeriformes: Artamidae) are members of Australia's diverse arid- and semi-arid zone avifauna. Widely sympatric and among Australia's relatively few obligate long-distance temperate-tropical migrants, the two are well differentiated morphologically but not ecologically and vocally. They are pair breeders unlike other Artamus species, which are at least facultative cooperative breeders. For these reasons they are an excellent case in which to use molecular data in integrative study of their evolution from ecological and biogeographical perspectives. We used mitochondrial DNA (mtDNA) to test whether they are each other's closest relatives, whether they evolved migration independently, whether they have molecular signatures of population expansions like some other Australian arid zone birds, and to estimate the timing of any inferred population expansions. Their mtDNAs are monophyletic with respect to other species of Artamusbut polyphyletic with respect to each other. The two species appear not to have evolved migration independently of each other but their morphological and mtDNA evolution have been strongly decoupled. Some level of hybridization and introgression cannot be dismissed outright as being involved in their mtDNA polyphyly but incomplete sorting of their most recent common ancestor's mtDNA is a simpler explanation consistent with their ecology. Bayesian phylogenetic inference and analyses of diversity within the two species (n=77) with conventional diversity statistics, statistical parsimony, and tests for population expansion vs stability (Tajima's D, Fu's Fsand Ramos-Onsin and Rozas's R2) all favour recent population increases. However, a non-starlike network suggests expansion(s) relatively early in the Pleistocene. Repeated population bottlenecks corresponding with multiple peaks of Pleistocene aridity could explain our findings, which add a new dimension to accruing data on the effects of Pleistocene aridity on the Australian biota.

Searching for microbial biological control candidates for invasive grasses: coupling expanded field research with strides in biotechnology and grassland restoration

USDA-ARS?s Scientific Manuscript database

Highly invasive grasses (e.g. Bromus spp., Pennisetum ciliare, Taeniatherum caput-medusae) are largely unabated in much of the arid Western U.S., despite more than 70 years of control attempts with a wide array of tools and management practices. The development and sustained integration of new appro...

Biofuel as an Integrated Farm Drainage Management crop: A bioeconomic analysis

NASA Astrophysics Data System (ADS)

Levers, L. R.; Schwabe, K. A.

2017-04-01

Irrigated agricultural lands in arid regions often suffer from soil salinization and lack of drainage, which affect environmental quality and productivity. Integrated Farm Drainage Management (IFDM) systems, where drainage water generated from higher-valued crops grown on high quality soils are used to irrigate salt-tolerant crops grown on marginal soils, is one possible strategy for managing salinity and drainage problems. If the IFDM crop were a biofuel crop, both environmental and private benefits may be generated; however, little is known about this possibility. As such, we develop a bioeconomic programming model of irrigated agricultural production to examine the role salt-tolerant biofuel crops might play within an IFDM system. Our results, generated by optimizing profits over land, water, and crop choice decisions subject to resource constraints, suggest that based on the private profits alone, biofuel crops can be a competitive alternative to the common practices of land retirement and nonbiofuel crop production under both low to high drainage water salinity. Yet IFDM biofuel crop production generates 30-35% fewer GHG emissions than the other strategies. The private market competitiveness coupled with the public good benefits may justify policy changes encouraging the growth of IFDM biofuel crops in arid agricultural areas globally.

Integrated use of soil physical and water isotope methods for ecohydrological characterization of desertified areas

NASA Astrophysics Data System (ADS)

Külls, Christoph; Nunes, Alice; Köbel-Batista, Melanie; Branquinho, Cristina; Bianconi, Nadja; Costantini, Eduardo

2014-05-01

Measures for monitoring desertification and soil degradation require a thorough understanding of soil physical properties and of the water balance in order to guide restoration efforts (Costantini et al. 2009). It is hypothesized that long term restoration success on degraded land depends on a series of interacting factors such as exposition, soil type, soil hydrology including lateral flow on hill-slope catenae. Recently, new soil water isotope measurement techniques have been developed (Garvelmann et al. 2012) that provide much faster and reliable stable water isotope profiles in soils. This technique yield information on groundwater recharge, soil water balance and on the origin of water available for plants, which in combination with conservative chemical tracers (chloride) can be validated. A multidisciplinary study including ecologists, soil physicists and hydrologists of the COST Action Desert Restoration Hub was carried out on four semi-arid sites in Portugal. A comparative characterization of soil physical parameters, soil water isotope and chloride profiles was performed in order to estimate pedoclimate, soil aridity, soil water balance and groundwater recharge. In combination with soil physical data a comprehensive and cross-validated characterization of pedoclimate and soil aridity was obtained. These indicators were then integrated and related to plant cover. The long-term rainfall of the four sites ranges from 512 to 638 mm, whereas air temperature is from 15.8 to 17.0°C. The De Martonne index of aridity spans from 19.3 to 24.6, pointing to semiarid to moderately arid climatic conditions. The long-term average number of days when the first 0.50 m of soil is dry ranges from 110 to 134, while the mean annual soil temperature at 0.50 m spans from 15.8 and 19.1°C. The studied profiles show different hydrological characteristics, in particular, the estimated hydraulic conductivity ranges from 0.1-1 to 10-100 µm/s. Three out of four profiles show a marked decrease in water permeability at 0.04, 0.20, or 0.40 m depth. Soil isotope profiles indicated that percolation beneath the root zone and groundwater recharge ranges from 21.7 mm/y to 29.7 mm/y. The recharge rate was positively related to mean annual rainfall and soil organic matter, and interestingly, increased with aridity and desertification. The difference between mean annual rainfall and percolation was positively related to plant cover and in inverse proportion to the aridity index. Our results highlight the importance of combining different methods of site characterization by soil physics, soil water isotopes and soil water chemistry (chloride) with vegetation data, providing a more specific analysis of ecohydrological conditions and their relation to ecosystem functioning and recovery potential. The field protocol applied can provide relevant information for guiding restoration strategies. Costantini, E. A. C., Urbano, F., Aramini, G., Barbetti, R., Bellino, F., Bocci, M., & Tascone, F. (2009). Rationale and methods for compiling an atlas of desertification in Italy. Land Degradation & Development, 20(3), 261-276. Garvelmann, J., Külls, C., & Weiler, M. (2012). A porewater-based stable isotope approach for the investigation of subsurface hydrological processes. Hydrology and Earth System Sciences, 16(2), 631-640.

Land degradation assessment by geo-spatially modeling different soil erodibility equations in a semi-arid catchment.

PubMed

Saygın, Selen Deviren; Basaran, Mustafa; Ozcan, Ali Ugur; Dolarslan, Melda; Timur, Ozgur Burhan; Yilman, F Ebru; Erpul, Gunay

2011-09-01

Land degradation by soil erosion is one of the most serious problems and environmental issues in many ecosystems of arid and semi-arid regions. Especially, the disturbed areas have greater soil detachability and transportability capacity. Evaluation of land degradation in terms of soil erodibility, by using geostatistical modeling, is vital to protect and reclaim susceptible areas. Soil erodibility, described as the ability of soils to resist erosion, can be measured either directly under natural or simulated rainfall conditions, or indirectly estimated by empirical regression models. This study compares three empirical equations used to determine the soil erodibility factor of revised universal soil loss equation prediction technology based on their geospatial performances in the semi-arid catchment of the Saraykoy II Irrigation Dam located in Cankiri, Turkey. A total of 311 geo-referenced soil samples were collected with irregular intervals from the top soil layer (0-10 cm). Geostatistical analysis was performed with the point values of each equation to determine its spatial pattern. Results showed that equations that used soil organic matter in combination with the soil particle size better agreed with the variations in land use and topography of the catchment than the one using only the particle size distribution. It is recommended that the equations which dynamically integrate soil intrinsic properties with land use, topography, and its influences on the local microclimates, could be successfully used to geospatially determine sites highly susceptible to water erosion, and therefore, to select the agricultural and bio-engineering control measures needed.

Decomposition of standing litter in arid grasslands: Interactions between sunlight, non-rainfall moisture, microbes, and plant traits

NASA Astrophysics Data System (ADS)

Logan, J. R. V.; Jacobson, P. J.; Jacobson, K. M.; Evans, S.

2017-12-01

Although arid lands make up 40% of the Earth's land surface, we still lack a strong understanding of carbon cycling and plant decomposition in these systems. One reason for this is that field studies typically only focus on decomposition at or below the ground surface even though standing dead litter (material that has not yet fallen to the ground) accounts for more than 50% of total necromass in many of these systems. While recent work has begun to recognize the important and unique aspects of standing litter decomposition, few studies have investigated specific mechanisms controlling rates of mass loss. We hypothesized that initial photodegradation of the outer plant cuticle of standing litter is an important determinant of litter decomposition because this process increases moisture absorption and subsequent opportunities for biological decomposition. Our preliminary results offer support for this hypothesis. We found that standing grass stems with their cuticles artificially removed had greater water absorbance and more than 400% greater mass loss over a 6-month period relative to controls with intact cuticles. Additionally, spectroscopic measurements of cuticle integrity showed damage to the litter surface after a period of extended photodegradation, allowing increased moisture uptake during simulated fog/dew events. These findings are especially important in the context of recent work by us and others showing that non-rainfall moisture (fog, dew, and water vapor) plays a much larger role in arid land decomposition than previously thought. Improving our understanding of the mechanisms driving decomposition of standing litter will enable us to develop a more predictive understanding of carbon storage in arid lands.

Modeling water scarcity and droughts for policy adaptation to climate change in arid and semiarid regions

NASA Astrophysics Data System (ADS)

Kahil, Mohamed Taher; Dinar, Ariel; Albiac, Jose

2015-03-01

Growing water extractions combined with emerging demands for environment protection increase competition for scarce water resources worldwide, especially in arid and semiarid regions. In those regions, climate change is projected to exacerbate water scarcity and increase the recurrence and intensity of droughts. These circumstances call for methodologies that can support the design of sustainable water management. This paper presents a hydro-economic model that links a reduced form hydrological component, with economic and environmental components. The model is applied to an arid and semiarid basin in Southeastern Spain to analyze the effects of droughts and to assess alternative adaptation policies. Results indicate that drought events have large impacts on social welfare, with the main adjustments sustained by irrigation and the environment. The water market policy seems to be a suitable option to overcome the negative economic effects of droughts, although the environmental effects may weaken its advantages for society. The environmental water market policy, where water is acquired for the environment, is an appealing policy to reap the private benefits of markets while protecting ecosystems. The current water management approach in Spain, based on stakeholders' cooperation, achieves almost the same economic outcomes and better environmental outcomes compared to a pure water market. These findings call for a reconsideration of the current management in arid and semiarid basins around the world. The paper illustrates the potential of hydro-economic modeling for integrating the multiple dimensions of water resources, becoming a valuable tool in the advancement of sustainable water management policies.

Adaptive policy responses to water shortage mitigation in the arid regions--a systematic approach based on eDPSIR, DEMATEL, and MCDA.

PubMed

Azarnivand, Ali; Chitsaz, Nastaran

2015-02-01

Most of the arid and semi-arid regions are located in the developing countries, while the availability of water in adequate quantity and quality is an essential condition to approach sustainable development. In this research, "enhanced Driving force-Pressure-State-Impact-Response (eDPSIR)" sustainability framework was applied to deal with water shortage in Yazd, an arid province of Iran. Then, the Decision Making Trial and Evaluation Laboratory (DEMATEL) technique was integrated into the driven components of eDPSIR, to quantify the inter-linkages among fundamental anthropogenic indicators (i.e. causes and effects). The paper's structure included: (1) identifying the indicators of DPSIR along with structuring eDPSIR causal networks, (2) using the DEMATEL technique to evaluate the inter-relationships among the causes and effects along with determining the key indicators, (3) decomposing the problem into a system of hierarchies, (4) employing the analytic hierarchy process (AHP) technique to evaluate the weight of each criterion, and (5) applying complex proportional assessment with Grey interval numbers (COPRAS-G) method to obtain the most conclusive adaptive policy response. The systematic quantitative analysis of causes and effects revealed that the root sources of water shortage in the study area were the weak enforcement of law and regulations, decline of available freshwater resources for development, and desertification consequences. According to the results, mitigating the water shortage in Yazd could be feasible by implementation of such key adaptive policy-responses as providing effective law enforcement, updating the standards and regulations, providing social learning, and boosting stakeholders' collaboration.

The response of arid soil communities to climate change: Chapter 8

USGS Publications Warehouse

Steven, Blaire; McHugh, Theresa Ann; Reed, Sasha C.

2017-01-01

Arid and semiarid ecosystems cover approximately 40% of Earth’s terrestrial surface and are present on each of the planet’s continents [1]. Drylands are characterized by their aridity, but there is substantial geographic, edaphic, and climatic variability among these vast ecosystems, and these differences underscore substantial variation in dryland soil microbial communities, as well as in the future climates predicted among arid and semiarid systems globally. Furthermore, arid ecosystems are commonly patchy at a variety of spatial scales [2,3]. Vascular plants are widely interspersed in drylands and bare soil, or soil that is covered with biological soil crusts, fill these spaces. The variability acts to further enhance spatial heterogeneity, as these different zones within dryland ecosystems differ in characteristics such as water retention, albedo, and nutrient cycling [4–6]. Importantly, the various soil patches of an arid landscape may be differentially sensitive to climate change. Soil communities are only active when enough moisture is available, and drylands show large spatial variability in soil moisture, with potentially long dry periods followed by pulses of moisture. The pulse dynamics associated with this wetting and drying affect the composition, structure, and function of dryland soil communities, and integrate biotic and abiotic processes via pulse-driven exchanges, interactions, transitions, and transfers. Climate change will likely alter the size, frequency, and intensity of future precipitation pulses, as well as influence non-rainfall sources of soil moisture, and aridland ecosystems are known to be highly sensitive to such climate variability. Despite great heterogeneity, arid ecosystems are united by a key parameter: a limitation in water availability. This characteristic may help to uncover unifying aspects of dryland soil responses to global change. The dryness of an ecosystem can be described by its aridity index (AI). Several AIs have been proposed, but the most widely used metrics determine the difference between average precipitation and potential evapotranspiration, where evapotranspiration is the sum of evaporation and plant transpiration, both of which move water from the ecosystem to the atmosphere [7–9]. Because evapotranspiration can be affected by various environmental factors such as temperature and incident radiation (Fig. 10.1), regions that receive the same average precipitation may have significantly different AI values [10,11]. Multiple studies have documented that mean annual precipitation, and thus AI, is highly correlated with biological diversity and net primary productivity [12–15]. Accordingly, AI is considered to be a central regulator of the diversity, structure, and productivity of an ecosystem, playing an especially influential role in arid ecosystems. Thus, the climate parameters that drive alterations in the AI of a region are likely to play an disproportionate role in shaping the response of arid soil communities to a changing climate. In this chapter we consider climate parameters that have been shown to be altered through climate change, with a focus on how these parameters are likely to affect dryland soil communities, including microorganisms and invertebrates. In particular, our goal is to highlight dryland soil community structure and function in the context of climate change, and we will focus on community relationships with increased atmospheric CO2 concentrations (a primary driver of climate change), temperature, and sources of soil moisture.

Integrated assessment of policy interventions for promoting sustainable irrigation in semi-arid environments: a hydro-economic modeling approach.

PubMed

Blanco-Gutiérrez, Irene; Varela-Ortega, Consuelo; Purkey, David R

2013-10-15

Sustaining irrigated agriculture to meet food production needs while maintaining aquatic ecosystems is at the heart of many policy debates in various parts of the world, especially in arid and semi-arid areas. Researchers and practitioners are increasingly calling for integrated approaches, and policy-makers are progressively supporting the inclusion of ecological and social aspects in water management programs. This paper contributes to this policy debate by providing an integrated economic-hydrologic modeling framework that captures the socio-economic and environmental effects of various policy initiatives and climate variability. This modeling integration includes a risk-based economic optimization model and a hydrologic water management simulation model that have been specified for the Middle Guadiana basin, a vulnerable drought-prone agro-ecological area with highly regulated river systems in southwest Spain. Namely, two key water policy interventions were investigated: the implementation of minimum environmental flows (supported by the European Water Framework Directive, EU WFD), and a reduction in the legal amount of water delivered for irrigation (planned measure included in the new Guadiana River Basin Management Plan, GRBMP, still under discussion). Results indicate that current patterns of excessive water use for irrigation in the basin may put environmental flow demands at risk, jeopardizing the WFD's goal of restoring the 'good ecological status' of water bodies by 2015. Conflicts between environmental and agricultural water uses will be stressed during prolonged dry episodes, and particularly in summer low-flow periods, when there is an important increase of crop irrigation water requirements. Securing minimum stream flows would entail a substantial reduction in irrigation water use for rice cultivation, which might affect the profitability and economic viability of small rice-growing farms located upstream in the river. The new GRBMP could contribute to balance competing water demands in the basin and to increase economic water productivity, but might not be sufficient to ensure the provision of environmental flows as required by the WFD. A thoroughly revision of the basin's water use concession system for irrigation seems to be needed in order to bring the GRBMP in line with the WFD objectives. Furthermore, the study illustrates that social, economic, institutional, and technological factors, in addition to bio-physical conditions, are important issues to be considered for designing and developing water management strategies. The research initiative presented in this paper demonstrates that hydro-economic models can explicitly integrate all these issues, constituting a valuable tool that could assist policy makers for implementing sustainable irrigation policies. Copyright © 2013 Elsevier Ltd. All rights reserved.

Identification and functional characterization of a novel bipartite nuclear localization sequence in ARID1A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bateman, Nicholas W.; The John P. Murtha Cancer Center, Walter Reed National Military Medical Center, 8901 Wisconsin Avenue, Bethesda 20889, MD; Shoji, Yutaka

2016-01-01

AT-rich interactive domain-containing protein 1A (ARID1A) is a recently identified nuclear tumor suppressor frequently altered in solid tumor malignancies. We have identified a bipartite-like nuclear localization sequence (NLS) that contributes to nuclear import of ARID1A not previously described. We functionally confirm activity using GFP constructs fused with wild-type or mutant NLS sequences. We further show that cyto-nuclear localized, bipartite NLS mutant ARID1A exhibits greater stability than nuclear-localized, wild-type ARID1A. Identification of this undescribed functional NLS within ARID1A contributes vital insights to rationalize the impact of ARID1A missense mutations observed in patient tumors. - Highlights: • We have identified a bipartitemore » nuclear localization sequence (NLS) in ARID1A. • Confirmation of the NLS was performed using GFP constructs. • NLS mutant ARID1A exhibits greater stability than wild-type ARID1A.« less

Genomic and proteomic characterization of ARID1A chromatin remodeller in ampullary tumors

PubMed Central

Nastase, Anca; Teo, Jin Yao; Heng, Hong Lee; Ng, Cedric Chuan Young; Myint, Swe Swe; Rajasegaran, Vikneswari; Loh, Jia Liang; Lee, Ser Yee; Ooi, London Lucien; Chung, Alexander Yaw Fui; Chow, Pierce Kah Hoe; Cheow, Peng Chung; Wan, Wei Keat; Azhar, Rafy; Khoo, Avery; Xiu, Sam Xin; Alkaff, Syed Muhammad Fahmy; Cutcutache, Ioana; Lim, Jing Quan; Ong, Choon Kiat; Herlea, Vlad; Dima, Simona; Duda, Dan G; Teh, Bin Tean; Popescu, Irinel; Lim, Tony Kiat Hon

2017-01-01

AT rich interactive domain 1A (ARID1A) is one of the most commonly mutated genes in a broad variety of tumors. The mechanisms that involve ARID1A in ampullary cancer progression remains elusive. Here, we evaluated the frequency of ARID1A and KRAS mutations in ampullary adenomas and adenocarcinomas and in duodenal adenocarcinomas from two cohorts of patients from Singapore and Romania, correlated with clinical and pathological tumor features, and assessed the functional role of ARID1A. In the ampullary adenocarcinomas, the frequency of KRAS and ARID1A mutations was 34.7% and 8.2% respectively, with a loss or reduction of ARID1A protein in 17.2% of the cases. ARID1A mutational status was significantly correlated with ARID1A protein expression level (P=0.023). There was a significant difference in frequency of ARID1A mutation between Romania and Singapore (2.7% versus 25%, P=0.04), suggestive of different etiologies. One somatic mutation was detected in the ampullary adenoma group. In vitro studies indicated the tumor suppressive role of ARID1A. Our results warrant further investigation of this chromatin remodeller as a potential early biomarker of the disease, as well as identification of therapeutic targets in ARID1A mutated ampullary cancers. PMID:28401006

Genomic and proteomic characterization of ARID1A chromatin remodeller in ampullary tumors.

PubMed

Nastase, Anca; Teo, Jin Yao; Heng, Hong Lee; Ng, Cedric Chuan Young; Myint, Swe Swe; Rajasegaran, Vikneswari; Loh, Jia Liang; Lee, Ser Yee; Ooi, London Lucien; Chung, Alexander Yaw Fui; Chow, Pierce Kah Hoe; Cheow, Peng Chung; Wan, Wei Keat; Azhar, Rafy; Khoo, Avery; Xiu, Sam Xin; Alkaff, Syed Muhammad Fahmy; Cutcutache, Ioana; Lim, Jing Quan; Ong, Choon Kiat; Herlea, Vlad; Dima, Simona; Duda, Dan G; Teh, Bin Tean; Popescu, Irinel; Lim, Tony Kiat Hon

2017-01-01

AT rich interactive domain 1A (ARID1A) is one of the most commonly mutated genes in a broad variety of tumors. The mechanisms that involve ARID1A in ampullary cancer progression remains elusive. Here, we evaluated the frequency of ARID1A and KRAS mutations in ampullary adenomas and adenocarcinomas and in duodenal adenocarcinomas from two cohorts of patients from Singapore and Romania, correlated with clinical and pathological tumor features, and assessed the functional role of ARID1A . In the ampullary adenocarcinomas, the frequency of KRAS and ARID1A mutations was 34.7% and 8.2% respectively, with a loss or reduction of ARID1A protein in 17.2% of the cases. ARID1A mutational status was significantly correlated with ARID1A protein expression level (P=0.023). There was a significant difference in frequency of ARID1A mutation between Romania and Singapore (2.7% versus 25%, P=0.04), suggestive of different etiologies. One somatic mutation was detected in the ampullary adenoma group. In vitro studies indicated the tumor suppressive role of ARID1A . Our results warrant further investigation of this chromatin remodeller as a potential early biomarker of the disease, as well as identification of therapeutic targets in ARID1A mutated ampullary cancers.

Climate change mitigation by carbon stock - the case of semi-arid West Africa

NASA Astrophysics Data System (ADS)

Lykke, A. M.; Barfod, A. S.; Tinggaard Svendsen, G.; Greve, M.; Svenning, J.-C.

2009-11-01

Semi-arid West Africa has not been integrated into the afforestation/reforestation (AR) carbon market. Most projects implemented under the Clean Development Mechanism (CDM) have focused on carbon emission reductions from industry and energy consumption, whereas only few (only one in West Africa) have been certified for AR carbon sequestration. A proposed mechanism, Reducing Emissions from Deforestation and Degradation (REDD) to be discussed under COP15 aims to reduce emissions by conserving already existing forests. REDD has high potential for carbon stocking at low costs, but focuses primarily on rain forest countries and excludes semi-arid West Africa from the preliminary setup. African savannas have potential to store carbon in the present situation with degrading ecosystems and relatively low revenues from crops and cattle, especially if it is possible to combine carbon stocking with promotion of secondary crops such as food resources and traditional medicines harvested on a sustainable basis. Methods for modelling and mapping of potential carbon biomass are being developed, but are still in a preliminary state. Although economic benefits from the sale of carbon credits are likely to be limited, carbon stocking is an interesting option if additional benefits are considered such as improved food security and protection of biodiversity.

Signals of impending change

USGS Publications Warehouse

Grace, James B.

2017-01-01

Society has an increasing awareness that there are finite limits to what we can expect the planet to absorb and still provide goods and services at current rates1. Both historical reconstructions and contemporary events continue to remind us that ecological regime changes are often abrupt rather than gradual. This reality motivates researchers who seek to discover leading indicators for impending ecosystem change. Berdugo et al.2 report an important advance in our ability to anticipate the conversion of arid lands from self-organized, self-maintaining and productive ecosystems, to a state characterized by disorganization and low functionality. Such conversions have important implications for our understanding of ‘desertification’ — which is a shift from arid to desert-like conditions.Theoretical studies have suggested that patterns in the patchiness of vegetation might indicate how close a system is to making an abrupt change to desert-like conditions3,4,5. Empirical studies, however, have tended to show instead that simply the total cover of vegetation, rather than its arrangement, often foretells the state of the system4,5,6,7,8,9. Berdugo et al.2 combine these competing ideas into one integrated perspective. They show how major environmental drivers, such as aridity, influence both vegetation cover and patchiness, as well as where self-organizing, stabilizing forces in the vegetation are likely to be found.

Vascular plants mediate the effects of aridity and soil properties on ammonia-oxidizing bacteria and archaea.

PubMed

Delgado-Baquerizo, Manuel; Gallardo, Antonio; Wallenstein, Matthew D; Maestre, Fernando T

2013-08-01

An integrated perspective of the most important factors driving the abundance of ammonia-oxidizing bacteria (AOB) and archaea (AOA) in natural ecosystems is lacking, especially in drylands. We evaluated how different climatic, abiotic, and nutrient-related factors determine AOA and AOB abundance in bare and vegetated microsites from grasslands throughout the Mediterranean Basin. We found a strong negative relationship between the abundance of AOA genes and soil fertility (availability of C, N, and P). Aridity and other abiotic factors (pH, sand content, and electrical conductivity) were more important than soil fertility in modulating the AOA/AOB ratio. AOB were more abundant under vegetated microsites, while AOA, highly resistant to stressful conditions, were more abundant in bare ground areas. These results suggest that AOA may carry out nitrification in less fertile microsites, while AOB predominate under more fertile conditions. Our results indicate that the influence of aridity and pH on the relative dominance of AOA and AOB genes is ultimately determined by local-scale environmental changes promoted by perennial vegetation. Thus, in spatially heterogeneous ecosystems such as drylands, there is a mutual exclusion and niche division between these microorganisms, suggesting that they may be functionally complementary. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Symbiotic fungi that influence vigor, biomass and reproductive potential of native bunch grasses for remediation of degraded semiarid rangelands

Treesearch

Jerry R. Barrow; Mary E. Lucero; Isaac Reyes-Vera

2008-01-01

A steady decline of perennial bunch grasses in arid rangelands has resulted in losses of productivity and germplasm. Remediation is costly and rarely successful. Cryptic symbiotic fungi, structurally integrated with cells and organs of native plants cannot be separated from host plant tissue. However, they were successfully transferred from cell cultures of native...

Prospects for phenological monitoring in an arid southwestern U.S. rangeland using field observations with hyperspatial and moderate resolution imagery

NASA Astrophysics Data System (ADS)

Browning, D. M.; Laliberte, A. S.; Rango, A.; Herrick, J. E.

2009-12-01

Relating field observations of plant phenological events to remotely sensed depictions of land surface phenology remains a challenge to the vertical integration of data from disparate sources. This research conducted at the Jornada Basin Long-Term Ecological Research site in southern New Mexico capitalizes on legacy datasets pertaining to reproductive phenology and biomass and hyperspatial imagery. Large amounts of exposed bare soil and modest cover from shrubs and grasses in these arid and semi-arid ecosystems challenge the integration of field observations of phenology and remotely sensed data to monitor changes in land surface phenology. Drawing on established field protocols for reproductive phenology, hyperspatial imagery (4 cm), and object-based image analysis, we explore the utility of two approaches to scale detailed observations (i.e., field and 4 cm imagery) to the extent of long-term field plots (50 x 50m) and moderate resolution Landsat Thematic Mapper (TM) imagery (30 x 30m). Very high resolution color-infrared imagery was collected June 2007 across 15 LTER study sites that transect five distinct vegetation communities along a continuum of grass to shrub dominance. We examined two methods for scaling spectral vegetation indices (SVI) at 4 cm resolution: pixel averaging and object-based integration. Pixel averaging yields the mean SVI value for all pixels within the plot or TM pixel. Alternatively, the object-based method is based on a weighted average of SVI values that correspond to discrete image objects (e.g., individual shrubs or grass patches). Object-based image analysis of 4 cm imagery provides a detailed depiction of ground cover and allows us to extract species-specific contributions to upscaled SVI values. The ability to discern species- or functional-group contributions to remotely sensed signals of vegetation greenness can greatly enhance the design of field sampling protocols for phenological research. Furthermore, imagery from unmanned aerial vehicles (UAV) is a cost-effective and increasingly available resource and generation of UAV mosaics has been accomplished so that larger study areas can be addressed. This technology can provide a robust basis for scaling relationships for phenology-based research applications.

Distribution of ticks infesting ruminants and risk factors associated with high tick prevalence in livestock farms in the semi-arid and arid agro-ecological zones of Pakistan.

PubMed

Rehman, Abdul; Nijhof, Ard M; Sauter-Louis, Carola; Schauer, Birgit; Staubach, Christoph; Conraths, Franz J

2017-04-19

Tick infestation is the major problem for animal health that causes substantial economic losses, particularly in tropical and subtropical countries. To better understand the spatial distribution of tick species and risk factors associated with tick prevalence in livestock in Pakistan, ticks were counted and collected from 471 animals, including 179 cattle, 194 buffaloes, 80 goats and 18 sheep, on 108 livestock farms in nine districts, covering both semi-arid and arid agro-ecological zones. In total, 3,807 ticks representing four species were collected: Hyalomma anatolicum (n = 3,021), Rhipicephalus microplus (n = 715), Hyalomma dromedarii (n = 41) and Rhipicephalus turanicus (n = 30). The latter species is reported for the first time from the study area. Rhipicephalus microplus was the predominant species in the semi-arid zone, whereas H. anatolicum was the most abundant species in the arid zone. The overall proportion of tick-infested ruminants was 78.3% (369/471). It was highest in cattle (89.9%), followed by buffaloes (81.4%), goats (60.0%) and sheep (11.1%). The median tick burden significantly differed among animal species and was highest in cattle (median 58), followed by buffaloes (median 38), goats (median 19) and sheep (median 4.5). Female animals had significantly higher tick burdens than males and, in large ruminants, older animals carried more ticks than younger animals. The intensity of infestation was significantly lower in indigenous animals compared to exotic and crossbred cows. Analysis of questionnaire data revealed that the absence of rural poultry, not using any acaricides, traditional rural housing systems and grazing were potential risk factors associated with a higher tick prevalence in livestock farms. Absence of rural poultry, not performing acaricide treatments, traditional rural housing systems and grazing were important risk factors associated with higher tick prevalence in livestock farms. Age, gender, breed and animal species significantly affected the intensity of tick infestation. This report also describes the presence of R. turanicus in the Punjab Province of Pakistan for the first time. The outcomes of this study will be useful in the planning of integrated control strategies for ticks and tick-borne diseases in Pakistan.

Geomorphic threshold conditions for gully erosion in Southwestern Iran (Boushehr-Samal watershed)

NASA Astrophysics Data System (ADS)

Nazari Samani, Aliakbar; Ahmadi, Hassan; Jafari, Mohammad; Boggs, Guy; Ghoddousi, Jamal; Malekian, Arash

2009-06-01

Globally, a large amount of research has been dedicated to furthering our understanding of the factors and mechanisms affecting gully erosion. However, despite the importance of gully erosion in arid and semi arid regions of Iran there has been no comprehensive study of the geomorphic threshold conditions and factors influencing gully initiation. The aim of this article is to investigate the gullying processes and threshold conditions of permanent gullies in an arid region of Iran based upon examination of the slope-area ( S = αA-β) relationship. The data were collected through field and laboratory studies as well as Digital Elevation Model (DEM) analyses. In total, 97 active headcuts were identified across the three study sites and classified based on dominant initiation process including piping, landsliding and overland flow. Soil properties, including EC, SAR and soil texture, as well as landuse practices were found to be the major factors initiating piping and bank gullies. All gullies initiated by landsliding and seepage processes were found to be located in steep areas (28-40% slope) with their distribution further influenced by the lithology and presence of a cohesionless sand layer within the soil profile. An inverse relationship between upslope area ( A) and local slope ( S), in which the α and β coefficients varied, was further investigated based on the dominant gullying process and land use. Gullies occurring in the rangelands that were dominated by overland flow had the strongest relationship while landsliding dominated gullies did not have a statistically significant S- A relationship. In comparison to theoretical and literature based relationships for gully initiation, relatively low values for β were obtained (-0.182 to -0.266), possibly influenced by the presence of seepage and subsurface processes in many gullies. However, this is consistent with other studies in arid regions and may reflect greater potential for gullying in arid zones due to low vegetation cover and high variation in rainfall. In addition, the soil attributes together with land use practices influenced gully initiation thresholds. Application of the solved S- A relation for predicting vulnerable areas to gullying indicates that it is possible to predict the location of gullies with an acceptable level of accuracy; however other environmental factors should be integrated with the S- A relationship to more accurately identify the location of permanent gullies in arid regions.

Simulated changes in aridity from the last glacial maximum to 4xCO2

NASA Astrophysics Data System (ADS)

Greve, Peter; Roderick, Michael L.; Seneviratne, Sonia I.

2017-11-01

Aridity is generally defined as the ‘degree to which a climate lacks moisture to sustain life in terrestrial ecosystems’. Several recent studies using the ‘aridity index’ (the ratio of potential evaporation to precipitation), have concluded that aridity will increase with CO2 because of increasing temperature. However, the ‘aridity index’ is—counterintuitively—not a direct measure of aridity per se (when defined as above) and there is widespread evidence that contradicts the ‘warmer is more arid’ interpretation. We provide here an assessment of multi-model changes in a broad set of aridity metrics over a large range of atmospheric CO2 concentrations ranging from conditions at the last glacial maximum to 4xCO2, using an ensemble of simulations from state-of-the-art Earth system models. Most measures of aridity do not show increasing aridity on global scales under conditions of increasing atmospheric CO2 concentrations and related global warming, although we note some varying responses depending on the considered variables. The response is, furthermore, more nuanced at regional scales, but in the majority of regions aridity does not increase with CO2 in the majority of metrics. Our results emphasize that it is not the climate models that project overwhelming increases of aridity with increasing CO2, but rather a secondary, offline, impact model—the ‘aridity index’—that uses climate model output as input.

Alkaloid diversity in the leaves of Australian Flindersia (Rutaceae) species driven by adaptation to aridity.

PubMed

Robertson, Luke P; Hall, Casey R; Forster, Paul I; Carroll, Anthony R

2018-05-04

The genus Flindersia (Rutaceae) comprises 17 species of mostly Australian endemic trees. Although most species are restricted to rainforests, four have evolved to grow in semi-arid and arid environments. In this study, the leaf alkaloid diversity of rainforest and semi-arid/arid zone adapted Australian Flindersia were compared by LC/MS-MS and NMR spectroscopy. Contrary to expectations, Flindersia alkaloid diversity was strongly correlated with environmental aridity, where species predominating in drier regions produced more alkaloids than their wet rainforest congenerics. Rainforest species were also more chemically similar to each other than were the four semi-arid/arid zone species. There was a significant relationship between the presence of alkaloid structural classes and phylogenetic distance, suggesting that alkaloid profiles are influenced by both genetic and environmental factors. The results suggest that the radiation of Flindersia species out of the rainforest and into drier environments has promoted the evolution of unique alkaloid diversity. Plants growing in arid and semi-arid regions of Australia may represent an untapped source of undescribed specialised metabolites. Copyright © 2018 Elsevier Ltd. All rights reserved.

Structure and DNA-Binding Sites of the SWI1 AT-rich Interaction Domain (ARID) Suggest Determinants for Sequence-Specific DNA Recognition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Suhkmann; Zhang, Ziming; Upchurch, Sean

2004-04-16

2 ARID is a homologous family of DNA-binding domains that occur in DNA binding proteins from a wide variety of species, ranging from yeast to nematodes, insects, mammals and plants. SWI1, a member of the SWI/SNF protein complex that is involved in chromatin remodeling during transcription, contains the ARID motif. The ARID domain of human SWI1 (also known as p270) does not select for a specific DNA sequence from a random sequence pool. The lack of sequence specificity shown by the SWI1 ARID domain stands in contrast to the other characterized ARID domains, which recognize specific AT-rich sequences. We havemore » solved the three-dimensional structure of human SWI1 ARID using solution NMR methods. In addition, we have characterized non-specific DNA-binding by the SWI1 ARID domain. Results from this study indicate that a flexible long internal loop in ARID motif is likely to be important for sequence specific DNA-recognition. The structure of human SWI1 ARID domain also represents a distinct structural subfamily. Studies of ARID indicate that boundary of the DNA binding structural and functional domains can extend beyond the sequence homologous region in a homologous family of proteins. Structural studies of homologous domains such as ARID family of DNA-binding domains should provide information to better predict the boundary of structural and functional domains in structural genomic studies. Key Words: ARID, SWI1, NMR, structural genomics, protein-DNA interaction.« less

Multi-gauge Calibration for modeling the Semi-Arid Santa Cruz Watershed in Arizona-Mexico Border Area Using SWAT

USGS Publications Warehouse

Niraula, Rewati; Norman, Laura A.; Meixner, Thomas; Callegary, James B.

2012-01-01

In most watershed-modeling studies, flow is calibrated at one monitoring site, usually at the watershed outlet. Like many arid and semi-arid watersheds, the main reach of the Santa Cruz watershed, located on the Arizona-Mexico border, is discontinuous for most of the year except during large flood events, and therefore the flow characteristics at the outlet do not represent the entire watershed. Calibration is required at multiple locations along the Santa Cruz River to improve model reliability. The objective of this study was to best portray surface water flow in this semiarid watershed and evaluate the effect of multi-gage calibration on flow predictions. In this study, the Soil and Water Assessment Tool (SWAT) was calibrated at seven monitoring stations, which improved model performance and increased the reliability of flow, in the Santa Cruz watershed. The most sensitive parameters to affect flow were found to be curve number (CN2), soil evaporation and compensation coefficient (ESCO), threshold water depth in shallow aquifer for return flow to occur (GWQMN), base flow alpha factor (Alpha_Bf), and effective hydraulic conductivity of the soil layer (Ch_K2). In comparison, when the model was established with a single calibration at the watershed outlet, flow predictions at other monitoring gages were inaccurate. This study emphasizes the importance of multi-gage calibration to develop a reliable watershed model in arid and semiarid environments. The developed model, with further calibration of water quality parameters will be an integral part of the Santa Cruz Watershed Ecosystem Portfolio Model (SCWEPM), an online decision support tool, to assess the impacts of climate change and urban growth in the Santa Cruz watershed.

Human health risk assessment of lead from mining activities at semi-arid locations in the context of total lead exposure.

PubMed

Zheng, Jiajia; Huynh, Trang; Gasparon, Massimo; Ng, Jack; Noller, Barry

2013-12-01

Lead from historical mining and mineral processing activities may pose potential human health risks if materials with high concentrations of bioavailable lead minerals are released to the environment. Since the Joint Expert Committee on Food Additives of Food and Agriculture Organization/World Health Organization withdrew the Provisional Tolerable Weekly Intake of lead in 2011, an alternative method was required for lead exposure assessment. This study evaluated the potential lead hazard to young children (0-7 years) from a historical mining location at a semi-arid area using the U.S. EPA Integrated Exposure Uptake Biokinetic (IEUBK) Model, with selected site-specific input data. This study assessed lead exposure via the inhalation pathway for children living in a location affected by lead mining activities and with specific reference to semi-arid conditions and made comparison with the ingestion pathway by using the physiologically based extraction test for gastro-intestinal simulation. Sensitivity analysis for major IEUBK input parameters was conducted. Three groups of input parameters were classified according to the results of predicted blood concentrations. The modelled lead absorption attributed to the inhalation route was lower than 2 % (mean ± SE, 0.9 % ± 0.1 %) of all lead intake routes and was demonstrated as a less significant exposure pathway to children's blood, compared with ingestion. Whilst dermal exposure was negligible, diet and ingestion of soil and dust were the dominant parameters in terms of children's blood lead prediction. The exposure assessment identified the changing role of dietary intake when house lead loadings varied. Recommendations were also made to conduct comprehensive site-specific human health risk assessment in future studies of lead exposure under a semi-arid climate.

Land cover controls on summer discharge and runoff solution chemistry of semi-arid urban catchments

NASA Astrophysics Data System (ADS)

Gallo, Erika L.; Brooks, Paul D.; Lohse, Kathleen A.; McLain, Jean E. T.

2013-04-01

SummaryRecharge of urban runoff to groundwater as a stormwater management practice has gained importance in semi-arid regions where water resources are scarce and urban centers are growing. Despite this trend, the importance of land cover in controlling semi-arid catchment runoff quantity and quality remains unclear. Here we address the question: How do land cover characteristics control the amount and quality of storm runoff in semi-arid urban catchments? We monitored summertime runoff quantity and quality from five catchments dominated by distinct urban land uses: low, medium, and high density residential, mixed use, and commercial. Increasing urban land cover increased runoff duration and the likelihood that a rainfall event would result in runoff, but did not increase the time to peak discharge of episodic runoff. The effect of urban land cover on hydrologic responses was tightly coupled to the magnitude of rainfall. At distinct rainfall thresholds, roads, percent impervious cover and the stormwater drainage network controlled runoff frequency, runoff depth and runoff ratios. Contrary to initial expectations, runoff quality did not vary in repose to impervious cover or land use. We identified four major mechanisms controlling runoff quality: (1) variable solute sourcing due to land use heterogeneity and above ground catchment connectivity; (2) the spatial extent of pervious and biogeochemically active areas; (3) the efficiency of overland flow and runoff mobilization; and (4) solute flushing and dilution. Our study highlights the importance of the stormwater drainage systems characteristics in controlling urban runoff quantity and quality; and suggests that enhanced wetting and in-stream processes may control solute sourcing and retention. Finally, we suggest that the characteristics of the stormwater drainage system should be integrated into stormwater management approaches.

Synthetic Lethal Therapeutic Approaches for ARID1A-Mutated Ovarian Cancer

DTIC Science & Technology

2017-10-01

formation by the indicated cells (c). (d-f) ARID1A protein expression in parental and ARID1A CRISPR OVCA429 cells (d). Colony formation assay using...ovarian tumor cultures with (VOA4841) and without (XVOA295) ARID1A expression. n=3 independent experiments. (f) Control and ARID1A CRISPR OVCA429 cells

Arid and semiarid land stewardship: A 10-year review of accomplishments and contributions of the lnternational Arid Lands Consortium

Treesearch

Peter F. Ffolliott; Jeffrey O. Dawson; James T. Fisher; Itshack Moshe; Darrell W. DeBoers; Timothy. E. Fulbright; John Tracy; Abdullah Al Musa; Carter Johnson; Jim P. M. Chamie

2001-01-01

The International Arid Lands Consortium (IALC) was established in 1990 to promote research, education, and training activities related to the development, management, and restoration or reclamation of arid and semiarid lands worldwide. The IALC, a leading international organization, supports ecological sustainability and development of arid and semiarid lands. Building...

Repurposing Pan-HDAC Inhibitors for ARID1A-Mutated Ovarian Cancer.

PubMed

Fukumoto, Takeshi; Park, Pyoung Hwa; Wu, Shuai; Fatkhutdinov, Nail; Karakashev, Sergey; Nacarelli, Timothy; Kossenkov, Andrew V; Speicher, David W; Jean, Stephanie; Zhang, Lin; Wang, Tian-Li; Shih, Ie-Ming; Conejo-Garcia, Jose R; Bitler, Benjamin G; Zhang, Rugang

2018-03-27

ARID1A, a subunit of the SWI/SNF complex, is among the most frequently mutated genes across cancer types. ARID1A is mutated in more than 50% of ovarian clear cell carcinomas (OCCCs), diseases that have no effective therapy. Here, we show that ARID1A mutation confers sensitivity to pan-HDAC inhibitors such as SAHA in ovarian cancers. This correlated with enhanced growth suppression induced by the inhibition of HDAC2 activity in ARID1A-mutated cells. HDAC2 interacts with EZH2 in an ARID1A status-dependent manner. HDAC2 functions as a co-repressor of EZH2 to suppress the expression of EZH2/ARID1A target tumor suppressor genes such as PIK3IP1 to inhibit proliferation and promote apoptosis. SAHA reduced the growth and ascites of the ARID1A-inactivated OCCCs in both orthotopic and genetic mouse models. This correlated with a significant improvement of survival of mice bearing ARID1A-mutated OCCCs. These findings provided preclinical rationales for repurposing FDA-approved pan-HDAC inhibitors for treating ARID1A-mutated cancers. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Environmental and socio-economic methodologies and solutions towards integrated water resources management.

PubMed

Friesen, Jan; Rodriguez Sinobas, Leonor; Foglia, Laura; Ludwig, Ralf

2017-03-01

Semi-arid regions are facing the challenge of managing water resources under conditions of increasing scarcity and drought. These are recently pressured by the impact of climate change favoring the shifting from using surface water to groundwater without taking sustainability issues into account. Likewise, water scarcity raises the competition for water among users, increasing the risk of social conflicts, as the availability of fresh water in sufficient quality and quantity is already one of the major factors limiting socio-economic development. In terms of hydrology, semi-arid regions are characterized by very complex hydro- and hydrogeological systems. The complexity of the water cycle contrasts strongly with the poor data availability, (1) which limits the number of analysis techniques and methods available to researchers, (2) limits the accuracy of models and predictions, and (3) consequently challenges the capabilities to develop appropriate management measures to mitigate or adapt the environment to scarcity and drought conditions. Integrated water resources management is a holistic approach to focus on both environmental as well as on socio-economic factors influencing water availability and supply. The management approaches and solutions adopted, e.g. in form of decision support for specific water resources systems, are often highly specific for individual case studies. Copyright © 2016 Elsevier B.V. All rights reserved.

Integrated water resources management and water users' associations in the arid region of northwest China: a case study of farmers' perceptions.

PubMed

Hu, Xiao-Jun; Xiong, You-Cai; Li, Yong-Jin; Wang, Jian-Xin; Li, Feng-Min; Wang, Hai-Yang; Li, Lan-Lan

2014-12-01

Water scarcity is a critical policy issue in the arid regions of northwest China. The local government has widely adopted integrated water resources management (IWRM), but lacks support from farmers and farm communities. We undertook a case study in the Minqin oasis of northwest China to examine farmers' responses to IWRM and understand why farmer water users' associations (WUAs) are not functioning effectively at the community level. Results of quantitative and qualitative surveys of 392 farmers in 27 administrative villages showed that over 70% of farmers disapprove of the IWRM market-based reforms. In particular, the failure of farmer WUAs can be attributed to overlapping organizational structures between the WUAs and the villagers' committees; mismatches between the organizational scale of the WUAs and practical irrigation management by the farmers themselves; marginalization of rural women in water decision-making processes; and the inflexibility of IWRM implementation. An important policy implication from this study is that rebuilding farmer WUAs is key to overcoming the difficulties of IWRM. The current water governance structure, which is dominated by administrative systems, must be thoroughly reviewed to break the vicious cycle of tension and distrust between farmers and the government. Copyright © 2014 Elsevier Ltd. All rights reserved.

Aridity increases below-ground niche breadth in grass communities

USGS Publications Warehouse

Butterfield, Bradley J.; Bradford, John B.; Munson, Seth M.; Gremer, Jennifer R.

2017-01-01

Aridity is an important environmental filter in the assembly of plant communities worldwide. The extent to which root traits mediate responses to aridity, and how they are coordinated with leaf traits, remains unclear. Here, we measured variation in root tissue density (RTD), specific root length (SRL), specific leaf area (SLA), and seed size within and among thirty perennial grass communities distributed along an aridity gradient spanning 190–540 mm of climatic water deficit (potential minus actual evapotranspiration). We tested the hypotheses that traits exhibited coordinated variation (1) among species, as well as (2) among communities varying in aridity, and (3) functional diversity within communities declines with increasing aridity, consistent with the “stress-dominance” hypothesis. Across communities, SLA and RTD exhibited a coordinated response to aridity, shifting toward more conservative (lower SLA, higher RTD) functional strategies with increasing aridity. The response of SRL to aridity was more idiosyncratic and was independent of variation in SLA and RTD. Contrary to the stress-dominance hypothesis, the diversity of SRL values within communities increased with aridity, while none of the other traits exhibited significant diversity responses. These results are consistent with other studies that have found SRL to be independent of an SLA–RTD axis of functional variation and suggest that the dynamic nature of soil moisture in arid environments may facilitate a wider array of resource capture strategies associated with variation in SRL.

Arid Zone Hydrology

USDA-ARS?s Scientific Manuscript database

Arid zone hydrology encompasses a wide range of topics and hydro-meteorological and ecological characteristics. Although arid and semi-arid watersheds perform the same functions as those in humid environments, their hydrology and sediment transport characteristics cannot be readily predicted by inf...

Clinicopathologic and prognostic relevance of ARID1A protein loss in colorectal cancer.

PubMed

Wei, Xiao-Li; Wang, De-Shen; Xi, Shao-Yan; Wu, Wen-Jing; Chen, Dong-Liang; Zeng, Zhao-Lei; Wang, Rui-Yu; Huang, Ya-Xin; Jin, Ying; Wang, Feng; Qiu, Miao-Zhen; Luo, Hui-Yan; Zhang, Dong-Sheng; Xu, Rui-Hua

2014-12-28

To explore the association between AT-rich interactive domain 1A (ARID1A) protein loss by immunohistochemistry and both clinicopathologic characteristics and prognosis in patients with colorectal cancer. We retrospectively collected clinicopathologic data and archived paraffin-embedded primary colorectal cancer samples from 209 patients, including 111 patients with colon cancer and 98 patients with rectal cancer. The tumor stage ranged from stage I to stage IV according to the 7(th) edition of the American Joint Committee on Cancer tumor-node-metastasis (TNM) staging system. All patients underwent resection of primary colorectal tumors. The expression of ARID1A protein in primary colorectal cancer tissues was examined by immunohistochemical staining. The clinicopathologic association and survival relevance of ARID1A protein loss in colorectal cancer were analyzed. ARID1A loss by immunohistochemistry was not rare in primary colorectal cancer tumors (25.8%). There were 7.4%, 24.1%, 22.2% and 46.3% of patients with ARID1A loss staged at TNM stage I, II, III and IV, respectively, compared with 20.0%, 22.6%, 27.7% and 29.7% of patients without ARID1A loss staged at TNM stage I, II, III and IV, respectively. In patients with ARID1A loss, the distant metastasis rate was 46.3%. However, only 29.7% of patients without ARID1A loss were found to have distant metastasis. In terms of pathologic differentiation, there were 25.9%, 66.7% and 7.4% with poorly, moderately and well differentiated tumors in patients with ARID1A loss, and 14.2%, 72.3% and 13.5% with poorly, moderately and well differentiated tumors in patients without ARID1A loss, respectively. ARID1A loss was associated with late TNM stage (P = 0.020), distant metastasis (P = 0.026), and poor pathological classification (P = 0.035). However, patients with positive ARID1A had worse overall survival compared to those with negative ARID1A in stage IV colorectal cancer (HR = 2.49, 95%CI: 1.13-5.51). ARID1A protein loss is associated with clinicopathologic characteristics in colorectal cancer patients and with survival in stage IV patients.

Identification and functional characterization of a novel bipartite nuclear localization sequence in ARID1A.

PubMed

Bateman, Nicholas W; Shoji, Yutaka; Conrads, Kelly A; Stroop, Kevin D; Hamilton, Chad A; Darcy, Kathleen M; Maxwell, George L; Risinger, John I; Conrads, Thomas P

2016-01-01

AT-rich interactive domain-containing protein 1A (ARID1A) is a recently identified nuclear tumor suppressor frequently altered in solid tumor malignancies. We have identified a bipartite-like nuclear localization sequence (NLS) that contributes to nuclear import of ARID1A not previously described. We functionally confirm activity using GFP constructs fused with wild-type or mutant NLS sequences. We further show that cyto-nuclear localized, bipartite NLS mutant ARID1A exhibits greater stability than nuclear-localized, wild-type ARID1A. Identification of this undescribed functional NLS within ARID1A contributes vital insights to rationalize the impact of ARID1A missense mutations observed in patient tumors. Copyright © 2015 Elsevier Inc. All rights reserved.

A Framework Predicting Water Availability in a Rapidly Growing, Semi-Arid Region under Future Climate Change

NASA Astrophysics Data System (ADS)

Han, B.; Benner, S. G.; Glenn, N. F.; Lindquist, E.; Dahal, K. R.; Bolte, J.; Vache, K. B.; Flores, A. N.

2014-12-01

Climate change can lead to dramatic variations in hydrologic regime, affecting both surface water and groundwater supply. This effect is most significant in populated semi-arid regions where water availability are highly sensitive to climate-induced outcomes. However, predicting water availability at regional scales, while resolving some of the key internal variability and structure in semi-arid regions is difficult due to the highly non-linearity relationship between rainfall and runoff. In this study, we describe the development of a modeling framework to evaluate future water availability that captures elements of the coupled response of the biophysical system to climate change and human systems. The framework is built under the Envision multi-agent simulation tool, characterizing the spatial patterns of water demand in the semi-arid Treasure Valley area of Southwest Idaho - a rapidly developing socio-ecological system where urban growth is displacing agricultural production. The semi-conceptual HBV model, a population growth and allocation model (Target), a vegetation state and transition model (SSTM), and a statistically based fire disturbance model (SpatialAllocator) are integrated to simulate hydrology, population and land use. Six alternative scenarios are composed by combining two climate change scenarios (RCP4.5 and RCP8.5) with three population growth and allocation scenarios (Status Quo, Managed Growth, and Unconstrained Growth). Five-year calibration and validation performances are assessed with Nash-Sutcliffe efficiency. Irrigation activities are simulated using local water rights. Results show that in all scenarios, annual mean stream flow decreases as the projected rainfall increases because the projected warmer climate also enhances water losses to evapotranspiration. Seasonal maximum stream flow tends to occur earlier than in current conditions due to the earlier peak of snow melting. The aridity index and water deficit generally increase in the irrigated area. The most sensitive area is along the Boise Foothill which is the transitioning zone from water deficit to water abundant. However, these trends vary significantly between scenarios in space and time. The outcome of the study will serve as a reference for local stakeholders to make decisions on future land use.

Climate, niche evolution, and diversification of the "bird-cage" evening primroses (Oenothera, sections Anogra and Kleinia).

PubMed

Evans, Margaret E K; Smith, Stephen A; Flynn, Rachel S; Donoghue, Michael J

2009-02-01

We integrate climatic niche models and dated phylogenies to characterize the evolution of climatic niches in Oenothera sections Anogra and Kleinia (Onagraceae), and from that we make inferences on diversification in relation to climate. The evolution of climatic tolerances in Anogra + Kleinia has been heterogeneous, across phylogenetic groups and across different dimensions of climate. All the extant taxa occur in semiarid to arid conditions (annual precipitation of 10.1-49.1 cm and high temperatures in the warmest month of 28.5 degrees-40.1 degrees C), but there is striking variation among taxa in their climatic tolerances, especially temperature (minimum temperatures in the coldest month of -14.0 degrees to 5.3 degrees C) and summer versus winter precipitation (precipitation in the warmest quarter of 0.6-19.4 cm). Climatic disparity is especially pronounced in two subclades (californica, deltoides) that radiated in the southwestern United States and California, apparently including both divergent and convergent evolution of climatic tolerances. This niche evolution is remarkable, given the probable timescale of the radiation (approximately 1 million years). We suggest that the spatiotemporal climatic heterogeneity of western North America has served as a driver of diversification. Our data are also consistent with Axelrod's hypothesis that the spread of arid conditions in western North America stimulated diversification of arid-adapted lineages.

Optimizing Irrigation Water Allocation under Multiple Sources of Uncertainty in an Arid River Basin

NASA Astrophysics Data System (ADS)

Wei, Y.; Tang, D.; Gao, H.; Ding, Y.

2015-12-01

Population growth and climate change add additional pressures affecting water resources management strategies for meeting demands from different economic sectors. It is especially challenging in arid regions where fresh water is limited. For instance, in the Tailanhe River Basin (Xinjiang, China), a compromise must be made between water suppliers and users during drought years. This study presents a multi-objective irrigation water allocation model to cope with water scarcity in arid river basins. To deal with the uncertainties from multiple sources in the water allocation system (e.g., variations of available water amount, crop yield, crop prices, and water price), the model employs a interval linear programming approach. The multi-objective optimization model developed from this study is characterized by integrating eco-system service theory into water-saving measures. For evaluation purposes, the model is used to construct an optimal allocation system for irrigation areas fed by the Tailan River (Xinjiang Province, China). The objective functions to be optimized are formulated based on these irrigation areas' economic, social, and ecological benefits. The optimal irrigation water allocation plans are made under different hydroclimate conditions (wet year, normal year, and dry year), with multiple sources of uncertainty represented. The modeling tool and results are valuable for advising decision making by the local water authority—and the agricultural community—especially on measures for coping with water scarcity (by incorporating uncertain factors associated with crop production planning).

Advancing the Food-Energy-Water Nexus: Closing Nutrient Loops in Arid River Corridors.

PubMed

Mortensen, Jacob G; González-Pinzón, Ricardo; Dahm, Clifford N; Wang, Jingjing; Zeglin, Lydia H; Van Horn, David J

2016-08-16

Closing nutrient loops in terrestrial and aquatic ecosystems is integral to achieve resource security in the food-energy-water (FEW) nexus. We performed multiyear (2005-2008), monthly sampling of instream dissolved inorganic nutrient concentrations (NH4-N, NO3-N, soluble reactive phosphorus-SRP) along a ∼ 300-km arid-land river (Rio Grande, NM) and generated nutrient budgets to investigate how the net source/sink behavior of wastewater and irrigated agriculture can be holistically managed to improve water quality and close nutrient loops. Treated wastewater on average contributed over 90% of the instream dissolved inorganic nutrients (101 kg/day NH4-N, 1097 kg/day NO3-N, 656 kg/day SRP). During growing seasons, the irrigation network downstream of wastewater outfalls retained on average 37% of NO3-N and 45% of SRP inputs, with maximum retention exceeding 60% and 80% of NO3-N and SRP inputs, respectively. Accurate quantification of NH4-N retention was hindered by low loading and high variability. Nutrient retention in the irrigation network and instream processes together limited downstream export during growing seasons, with total retention of 33-99% of NO3-N inputs and 45-99% of SRP inputs. From our synoptic analysis, we identify trade-offs associated with wastewater reuse for agriculture within the scope of the FEW nexus and propose strategies for closing nutrient loops in arid-land rivers.

Speciation on the Rocks: Integrated Systematics of the Heteronotia spelea Species Complex (Gekkota; Reptilia) from Western and Central Australia

PubMed Central

Pepper, Mitzy; Doughty, Paul; Fujita, Matthew K.; Moritz, Craig; Keogh, J. Scott

2013-01-01

The isolated uplands of the Australian arid zone are known to provide mesic refuges in an otherwise xeric landscape, and divergent lineages of largely arid zone taxa have persisted in these regions following the onset of Miocene aridification. Geckos of the genus Heteronotia are one such group, and have been the subject of many genetic studies, including H. spelea, a strongly banded form that occurs in the uplands of the Pilbara and Central Ranges regions of the Australian arid zone. Here we assess the systematics of these geckos based on detailed examination of morphological and genetic variation. The H. spelea species complex is a monophyletic lineage to the exclusion of the H. binoei and H. planiceps species complexes. Within the H. spelea complex, our previous studies based on mtDNA and nine nDNA loci found populations from the Central Ranges to be genetically divergent from Pilbara populations. Here we supplement our published molecular data with additional data gathered from central Australian samples. In the spirit of integrative species delimitation, we combine multi-locus, coalescent-based lineage delimitation with extensive morphological analyses to test species boundaries, and we describe the central populations as a new species, H. fasciolatus sp. nov. In addition, within the Pilbara there is strong genetic evidence for three lineages corresponding to northeastern (type), southern, and a large-bodied melanic population isolated in the northwest. Due to its genetic distinctiveness and extreme morphological divergence from all other Heteronotia, we describe the melanic form as a new species, H. atra sp. nov. The northeastern and southern Pilbara populations are morphologically indistinguishable with the exception of a morpho-type in the southeast that has a banding pattern resembling H. planiceps from the northern monsoonal tropics. Pending more extensive analyses, we therefore treat Pilbara H. spelea as a single species with phylogenetic structure and morphological heterogeneity. PMID:24244289

Prognostic role and implications of mutation status of tumor suppressor gene ARID1A in cancer: a systematic review and meta-analysis

PubMed Central

Luchini, Claudio; Veronese, Nicola; Solmi, Marco; Cho, Hanbyoul; Kim, Jae-Hoon; Chou, Angela; Gill, Anthony J.; Faraj, Sheila F.; Chaux, Alcides; Netto, George J.; Nakayama, Kentaro; Kyo, Satoru; Lee, Soo Young; Kim, Duck-Woo; Yousef, George M.; Scorilas, Andreas; Nelson, Gregg S.; Köbel, Martin; Kalloger, Steve E.; Schaeffer, David F.; Yan, Hai-Bo; Liu, Feng; Yokoyama, Yoshihito; Zhang, Xianyu; Pang, Da; Lichner, Zsuzsanna; Sergi, Giuseppe; Manzato, Enzo; Capelli, Paola; Wood, Laura D.; Scarpa, Aldo; Correll, Christoph U.

2015-01-01

Loss of the tumor suppressor gene AT-rich interactive domain-containing protein 1A (ARID1A) has been demonstrated in several cancers, but its prognostic role is unknown. We aimed to investigate the risk associated with loss of ARID1A (ARID1A−) for all-cause mortality, cancer-specific mortality and recurrence of disease in subjects with cancer. PubMed and SCOPUS search from database inception until 01/31/2015 without language restriction was conducted, contacting authors for unpublished data. Eligible were prospective studies reporting data on prognostic parameters in subjects with cancer, comparing participants with presence of ARID1A (ARID1A+) vs. ARID1A−, assessed either via immunohistochemistry (loss of expression) or with genetic testing (presence of mutation). Data were summarized using risk ratios (RR) for number of deaths/recurrences and hazard ratios (HR) for time-dependent risk related to ARID1A− adjusted for potential confounders. Of 136 hits, 25 studies with 5,651 participants (28 cohorts; ARID1A−: n = 1,701; ARID1A+: n = 3,950), with a mean follow-up period of 4.7 ± 1.8 years, were meta-analyzed. Compared to ARID1A+, ARID1A− significantly increased cancer-specific mortality (studies = 3; RR = 1.55, 95% confidence interval (CI) = 1.19–2.00, I2 = 31%). Using HRs adjusted for potential confounders, ARID1A− was associated with a greater risk of cancer-specific mortality (studies = 2; HR = 2.55, 95%CI = 1.19–5.45, I2 = 19%) and cancer recurrence (studies = 10; HR = 1.93, 95%CI = 1.22–3.05, I2 = 76%). On the basis of these results, we have demonstrated that loss of ARID1A shortened time to cancer-specific mortality, and to recurrence of cancer when adjusting for potential confounders. For its role, this gene should be considered as an important potential target for personalized medicine in cancer treatment. PMID:26384299

The role of the "socio" in socio-hydrology: a review, critique, and notes from the semi-arid American West

NASA Astrophysics Data System (ADS)

Lindquist, E.

2016-12-01

"Socio-hydrology" as a concept has been in vogue for the past 10-15 years and has been defined as a means to better integrate hydrological and societal processes and connections. Rarely, however, do we reflect on the balance between the two elements in the concept, and all too often the "socio" is seen as a necessary evil in support of the hydrological sciences, rather than as an equal partner in the co-production of knowledge. This contribution will review and assess the "socio" component of socio-hydrology in order to better develop meaningful collaborations and research design, implementation and impact. A brief history of the term and related research is outlined (is it really new?), followed by a discussion of the current balance between socio and hydrology in this science, and directions for future research and integration. This contribution also introduces the concept of a "water policy cycle" as a way to integrate the "socio" into the more traditional (and engineering and bio-physical biased) hydrological cycle. Finally, we use an ongoing case of coproduction of knowledge and decision making in the semi-arid West, through the illustration of a dynamic and complex river basin in southwest Idaho, to relate the opportunities and challenges of socio-hydrology at the local and regional scale. Lessons learned at the forefront of real-time "socio-hydrology" will be articulated and generalized for a broader perspective and reflection. This contribution will address the coupled-natural processes and critical transitions and challenges for sustainable water management themes of HO61.

Use of remote sensing and GIS in mapping the environmental sensitivity areas for desertification of Egyptian territory

NASA Astrophysics Data System (ADS)

Gad, A.; Lotfy, I.

2008-06-01

Desertification is defined in the first art of the convention to combat desertification as "land degradation in arid, semiarid and dry sub-humid areas resulting from climatic variations and human activities". Its consequence include a set of important processes which are active in arid and semi arid environment, where water is the main limiting factor of land use performance in such ecosystem . Desertification indicators or the groups of associated indicators should be focused on a single process. They should be based on available reliable information sources, including remotely sensed images, topographic data (maps or DEM'S), climate, soils and geological data. The current work aims to map the Environmental Sensitivity Areas (ESA's) to desertification in whole territory of Egypt at a scale of 1:1 000 000. ETM satellite images, geologic and soil maps were used as main sources for calculating the index of Environmental Sensitivity Areas (ESAI) for desertification. The algorism is adopted from MEDALLUS methodology as follows; ESAI = (SQI * CQI * VQI)1/3 Where SQI is the soil quality index, CQI is the climate quality index and VQI is the vegetation quality index. The SQI is based on rating the parent material, slope, soil texture, and soil depth. The VQI is computed on bases of rating three categories (i.e. erosion protection, drought resistance and plant cover). The CQI is based on the aridity index, derived from values of annual rainfall and potential evapotranspiration. Arc-GIS 9 software was used for the computation and sensitivity maps production. The results show that the soil of the Nile Valley are characterized by a moderate SQI, however the those in the interference zone are low soil quality indexed. The dense vegetation of the valley has raised its VQI to be good, however coastal areas are average and interference zones are low. The maps of ESA's for desertification show that 86.1% of Egyptian territory is classified as very sensitive areas, while 4.3% as Moderately sensitive, and 9.6% as sensitive. It can be concluded that implementing the maps of sensitivity to desertification is rather useful in the arid and semi arid areas as they give more likely quantitative trend for frequency of sensitive areas. The integration of different factors contributing to desertification sensitivity may lead to plan a successful combating. The usage of space data and GIS proved to be suitable tools to rely estimation and to fulfill the needed large computational requirements. They are also useful in visualizing the sensitivity situation of different desertification parameters.

Diverse Responses of Belowground Internal Nitrogen Cycling to Increasing Aridity

NASA Astrophysics Data System (ADS)

Kou, D.; Peng, Y.; Wang, G.; Ding, J.; Chen, Y.; Yang, G.; Fang, K.; Liu, L.; Zhang, B.; Müller, C.; Zhang, J.; Yang, Y.

2017-12-01

Belowground microbial nitrogen (N) dynamics play key roles in regulating structure and function of terrestrial ecosystems, however, our understanding on their responses to global change remains limited. This gap is particularly true for drylands, which constitute the largest biome in terrestrial ecosystems and are sensitive to predicted increase in aridity. Here, responding patterns and controls of six gross N transformation rates were explored along an aridity gradient in Tibetan drylands. Our results showed that gross N rates responded diversely to the changing aridity. Both mineralization (MN) and ammonium immobilization (INH4) declined as aridity increased. Aridity affected MN through its association with plant cover, clay content, soil organic matter (SOM), dissolved organic nitrogen (DON) and total microbial biomass, while regulated INH4 mainly through its effects on SOM and NH4+. Autotrophic nitrification (ONH4) exhibited a bell-shaped pattern along the gradient with a tipping point at aridity index = 0.47. Such a pattern was induced by aridity effects on the abundance of ammonia oxidizing archaea (AOA) and ammonia supplying capacity. Different from above N transformations, rates of nitrate immobilization (INO3) and dissimilatory nitrate reduction to ammonium (DNRA) had no responses to changing aridity, largely regulated by soil DON availability and clay content, respectively. Overall, these results suggest that predicted increase in aridity will exert different effects on various soil internal N cycling processes. The diverse patterns point to different responses of ecosystem N cycle with respect to aridity, and thus potentially have profound impact on structure and function of dryland ecosystems.

Assessment of Dry Wells for Stormwater Capture and Aquifer Recharge in the Arid and Semi-Arid Southwest

EPA Science Inventory

GOAL: to evaluate the utility of innovative, distributed, low impact development (LID) infrastructure and best management practices (BMPs) for wet weather capture and drinking water aquifer recharge in the arid and semi-arid southwestern USA OBJECTIVES: Design, build, monitor t...

Defining Scenarios: Linking Integrated Models, Regional Concerns, and Stakeholders

NASA Astrophysics Data System (ADS)

Hartmann, H. C.; Stewart, S.; Liu, Y.; Mahmoud, M.

2007-05-01

Scenarios are important tools for long-term planning, and there is great interest in using integrated models in scenario studies. However, scenario definition and assessment are creative, as well as scientific, efforts. Using facilitated creative processes, we have worked with stakeholders to define regionally significant scenarios that encompass a broad range of hydroclimatic, socioeconomic, and institutional dimensions. The regional scenarios subsequently inform the definition of local scenarios that work with context-specific integrated models that, individually, can address only a subset of overall regional complexity. Based on concerns of stakeholders in the semi-arid US Southwest, we prioritized three dimensions that are especially important, yet highly uncertain, for long-term planning: hydroclimatic conditions (increased variability, persistent drought), development patterns (urban consolidation, distributed rural development), and the nature of public institutions (stressed, proactive). Linking across real-world decision contexts and integrated modeling efforts poses challenges of creatively connecting the conceptual models held by both the research and stakeholder communities.

Involving stakeholders in evaluating environmental restoration technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCabe, G.H.; Serie, P.J.

1993-02-01

Involving citizens, interest groups, and regulators in environmental restoration and waste management programs is a challenge for government agencies and the organizations that support them. To be effective, such involvement activities must identify all individuals and groups who have a stake in the cleanup. Their participation must be early, substantive, and meaningful. Stockholders must be able to see how their input was considered and used, and feel that a good- faith effort was made to reconcile conflicting objectives. The Integrated Demonstration for Cleanup of Volatile Organic Compounds at Arid Sites (VOC-Arid ID) is a Department of Energy Office of Technologymore » Development project located at Hanford. Along with technical evaluation of innovative cleanup technologies, the program is conducting an institutional assessment of regulatory and public acceptance of new technologies. Through a series of interviews and workshops, and use of a computerized information management tool, stakeholders are having a voice in the evaluation. Public and regulatory reaction has been positive.« less

Aridification across the Carboniferous-Permian transition in central equatorial Pangea: The Catalan Pyrenean succession (NE Iberian Peninsula)

NASA Astrophysics Data System (ADS)

Mujal, Eudald; Fortuny, Josep; Marmi, Josep; Dinarès-Turell, Jaume; Bolet, Arnau; Oms, Oriol

2018-01-01

The Carboniferous-Permian terrestrial successions record a global climatic shift from icehouse to hothouse conditions. Our multidisciplinary study documents an aridification trend throughout the 1000 m thick composite terrestrial succession of the western Catalan Pyrenees (NE Iberian Peninsula), representing this time period. The detailed stratigraphic framework integrates sedimentology, paleopedology, biochronology (plant fossils and tetrapod footprints) and geochronology (paleomagnetism). Additional absolute age correlation is also carried out. The new and reviewed data show that the late Carboniferous wet environments (with short drought periods) progressively changed to a strong seasonal semi-arid and arid climate (with short humid periods) through the early Permian. This paleoclimatic trend supports the previously suggested aridification of the Pangean pan-tropical belt, and supports the hypothesis of the influence of the recurrent climatic fluctuations in Central Pangea, being tentatively correlated to the Southern Gondwanan glaciation-deglaciation periods. Therefore, the Carboniferous-Permian terrestrial succession from the Catalan Pyrenees emerges as a continuous record that can help to constrain late Paleozoic paleoenvironmental events.

Keeping Sediment and Nutrients out of Streams in Arid/Semi-Arid United States: Application of Low Impact Development/Green Infrastructure Practices

EPA Science Inventory

Climatic and hydrological characteristics in the arid/semi-arid areas create unique challenges to soil, water and biodiversity conservation. These areas are environmentally sensitive, but very valuable for the ecosystems services they provide to society. Some of these areas are...

Arid1b haploinsufficiency disrupts cortical interneuron development and mouse behavior.

PubMed

Jung, Eui-Man; Moffat, Jeffrey Jay; Liu, Jinxu; Dravid, Shashank Manohar; Gurumurthy, Channabasavaiah Basavaraju; Kim, Woo-Yang

2017-12-01

Haploinsufficiency of the AT-rich interactive domain 1B (ARID1B) gene causes autism spectrum disorder and intellectual disability; however, the neurobiological basis for this is unknown. Here we generated Arid1b-knockout mice and examined heterozygotes to model human patients. Arid1b-heterozygous mice showed a decreased number of cortical GABAergic interneurons and reduced proliferation of interneuron progenitors in the ganglionic eminence. Arid1b haploinsufficiency also led to an imbalance between excitatory and inhibitory synapses in the cerebral cortex. Furthermore, we found that Arid1b haploinsufficiency suppressed histone H3 lysine 9 acetylation (H3K9ac) overall and particularly reduced H3K9ac of the Pvalb promoter, resulting in decreased transcription. Arid1b-heterozygous mice exhibited abnormal cognitive and social behaviors, which were rescued by treatment with a positive allosteric GABA A receptor modulator. Our results demonstrate a critical role for Arid1b in interneuron development and behavior and provide insight into the pathogenesis of autism spectrum disorder and intellectual disability.

Integrated subsurface water solutions for coastal environments through integrated pump&treat and aquifer storage and recovery (ASR) schemes

NASA Astrophysics Data System (ADS)

Perdikaki, Martha; Kallioras, Andreas; Christoforidis, Christophoros; Iossifidis, Dimitris; Zafeiropoulos, Anastasios; Dimitriadis, Klisthenis; Makropoulos, Christos; Raat, Klaasjan; van den Berg, Gerard

2016-04-01

Coastal wetlands in semi-arid regions, as in Circum-Mediterranean, are considered important ecosystems that provide valuable services to human population and the environment, such as: flood protection, erosion control, wildlife habitat, water quality, recreation and carbon sequestration. Un-managed surface and groundwater exploitation in these areas usually leads to deterioration of such sensitive ecosystems by means of water resources degradation and/or increased salinity. Groundwater usually plays a vital role for the sustainability of these hydrological systems, as the underlying aquifers operate as regulators for both quantity and quality of their waters. Multi-layer and multi-objective Managed Aquifer Recharge (MAR) systems can be proved effective groundwater engineered solutions for the restoration of deteriorated coastal wetlands in semi- and arid regions. The plain of Marathon is a typical Mediterranean environment that hosts a naturally occurring -and today degraded- coastal wetland with the characteristics of a distinct ecosystem linked to a typical coastal hydrogeological system of a semi-arid region; and therefore can serve as a model for similar systems world-wide. The geo-hydrological setting of the area involves a multi-layer aquifer system consisting of (i) an upper un-consolidated formation of depositional unit dominated mostly by fluvial sediments and (ii) the surrounding and underlying karstified marbles; both being linked to the investigated wetland and also subjected to seawater encroachment. A smart engineered MAR system via an optimised Pump & Treat system integrated with an Aquifer Storage and Recovery (ASR) scheme in this area would include the abstraction of brackish groundwater from the deeper karst aquifer at a location close to the shoreline and direct treatment with Reverse Osmosis (RO). for desalination. Two-fold re-use scheme of the purified effluent can then be engineered for (i) the restoration of the coastal wetland; and (ii) managed aquifer recharge of the upper un-consolidated formation to sustain irrigation at the upstream area for agriculture. This facility will demonstrate how MAR can be used to sustain groundwater dependent ecosystems (and/or prevent their further degradation), while at the same time safeguarding water supply. Acknowledgements: This research is part of SUBSOL-bringing coastal SUBsurface water SOLutions to the market. SUBSOL has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 642228

Chromatin-Remodeling-Factor ARID1B Represses Wnt/β-Catenin Signaling.

PubMed

Vasileiou, Georgia; Ekici, Arif B; Uebe, Steffen; Zweier, Christiane; Hoyer, Juliane; Engels, Hartmut; Behrens, Jürgen; Reis, André; Hadjihannas, Michel V

2015-09-03

The link of chromatin remodeling to both neurodevelopment and cancer has recently been highlighted by the identification of mutations affecting BAF chromatin-remodeling components, such as ARID1B, in individuals with intellectual disability and cancer. However, the underlying molecular mechanism(s) remains unknown. Here, we show that ARID1B is a repressor of Wnt/β-catenin signaling. Through whole-transcriptome analysis, we find that in individuals with intellectual disability and ARID1B loss-of-function mutations, Wnt/β-catenin target genes are upregulated. Using cellular models of low and high Wnt/β-catenin activity, we demonstrate that knockdown of ARID1B activates Wnt/β-catenin target genes and Wnt/β-catenin-dependent transcriptional reporters in a β-catenin-dependent manner. Reciprocally, forced expression of ARID1B inhibits Wnt/β-catenin signaling downstream of the β-catenin destruction complex. Both endogenous and exogenous ARID1B associate with β-catenin and repress Wnt/β-catenin-mediated transcription through the BAF core subunit BRG1. Accordingly, mutations in ARID1B leading to partial or complete deletion of its BRG1-binding domain, as is often observed in intellectual disability and cancers, compromise association with β-catenin, and the resultant ARID1B mutant proteins fail to suppress Wnt/β-catenin signaling. Finally, knockdown of ARID1B in mouse neuroblastoma cells leads to neurite outgrowth through β-catenin. The data suggest that aberrations in chromatin-remodeling factors, such as ARID1B, might contribute to neurodevelopmental abnormalities and cancer through deregulation of developmental and oncogenic pathways, such as the Wnt/β-catenin signaling pathway. Copyright © 2015 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

Chromatin-Remodeling-Factor ARID1B Represses Wnt/β-Catenin Signaling

PubMed Central

Vasileiou, Georgia; Ekici, Arif B.; Uebe, Steffen; Zweier, Christiane; Hoyer, Juliane; Engels, Hartmut; Behrens, Jürgen; Reis, André; Hadjihannas, Michel V.

2015-01-01

The link of chromatin remodeling to both neurodevelopment and cancer has recently been highlighted by the identification of mutations affecting BAF chromatin-remodeling components, such as ARID1B, in individuals with intellectual disability and cancer. However, the underlying molecular mechanism(s) remains unknown. Here, we show that ARID1B is a repressor of Wnt/β-catenin signaling. Through whole-transcriptome analysis, we find that in individuals with intellectual disability and ARID1B loss-of-function mutations, Wnt/β-catenin target genes are upregulated. Using cellular models of low and high Wnt/β-catenin activity, we demonstrate that knockdown of ARID1B activates Wnt/β-catenin target genes and Wnt/β-catenin-dependent transcriptional reporters in a β-catenin-dependent manner. Reciprocally, forced expression of ARID1B inhibits Wnt/β-catenin signaling downstream of the β-catenin destruction complex. Both endogenous and exogenous ARID1B associate with β-catenin and repress Wnt/β-catenin-mediated transcription through the BAF core subunit BRG1. Accordingly, mutations in ARID1B leading to partial or complete deletion of its BRG1-binding domain, as is often observed in intellectual disability and cancers, compromise association with β-catenin, and the resultant ARID1B mutant proteins fail to suppress Wnt/β-catenin signaling. Finally, knockdown of ARID1B in mouse neuroblastoma cells leads to neurite outgrowth through β-catenin. The data suggest that aberrations in chromatin-remodeling factors, such as ARID1B, might contribute to neurodevelopmental abnormalities and cancer through deregulation of developmental and oncogenic pathways, such as the Wnt/β-catenin signaling pathway. PMID:26340334

Optimized estimation and its uncertainties of gross primary production over oasis-desert ecosystems in an arid region of China

NASA Astrophysics Data System (ADS)

Wang, H.; Li, X.; Xiao, J.; Ma, M.

2017-12-01

Arid and semi-arid ecosystems cover more than one-third of the Earth's land surface, it is of great important to the global carbon cycle. However, the magnitude of carbon sequestration and its contribution to global atmospheric carbon cycle is poorly understood due to the worldwide paucity of measurements of carbon exchange in the arid ecosystems. Accurate and continuous monitoring the production of arid ecosystem is of great importance for regional carbon cycle estimation. The MOD17A2 product provides high frequency observations of terrestrial Gross Primary Productivity (GPP) over the world. Although there have been plenty of studies to validate the MODIS GPP products with ground based measurements over a range of biome types, few have comprehensively validated the performance of MODIS estimates in arid and semi-arid ecosystems. Thus, this study examined the performance of the MODIS-derived GPP comparing with the EC observed GPP at different timescales for the main arid ecosystems in the arid and semi-arid ecosystems in China, and optimized the performance of the MODIS GPP calculations by using the in-situ metrological forcing data, and optimization of biome-specific parameters with the Bayesian approach. Our result revealed that the MOD17 algorithm could capture the broad trends of GPP at 8-day time scales for all investigated sites on the whole. However, the GPP product was underestimated in most ecosystems in the arid region, especially the irrigated cropland and forest ecosystems, while the desert ecosystem was overestimated in the arid region. On the annual time scale, the best performance was observed in grassland and cropland, followed by forest and desert ecosystems. On the 8-day timescale, the RMSE between MOD17 products and in-situ flux observations of all sites was 2.22 gC/m2/d, and R2 was 0.69. By using the in-situ metrological data driven, optimizing the biome-based parameters of the algorithm, we improved the performances of the MODIS GPP calculation over the main ecosystems in arid region of China.

Tradeoffs and synergies between biofuel production and large-scale solar infrastructure in deserts

NASA Astrophysics Data System (ADS)

Ravi, S.; Lobell, D. B.; Field, C. B.

2012-12-01

Solar energy installations in deserts are on the rise, fueled by technological advances and policy changes. Deserts, with a combination of high solar radiation and availability of large areas unusable for crop production are ideal locations for large scale solar installations. For efficient power generation, solar infrastructures require large amounts of water for operation (mostly for cleaning panels and dust suppression), leading to significant moisture additions to desert soil. A pertinent question is how to use the moisture inputs for sustainable agriculture/biofuel production. We investigated the water requirements for large solar infrastructures in North American deserts and explored the possibilities for integrating biofuel production with solar infrastructure. In co-located systems the possible decline in yields due to shading by solar panels may be offsetted by the benefits of periodic water addition to biofuel crops, simpler dust management and more efficient power generation in solar installations, and decreased impacts on natural habitats and scarce resources in deserts. In particular, we evaluated the potential to integrate solar infrastructure with biomass feedstocks that grow in arid and semi-arid lands (Agave Spp), which are found to produce high yields with minimal water inputs. To this end, we conducted detailed life cycle analysis for these coupled agave biofuel - solar energy systems to explore the tradeoffs and synergies, in the context of energy input-output, water use and carbon emissions.

Integrating policy, disintegrating practice: water resources management in Botswana

NASA Astrophysics Data System (ADS)

Swatuk, Larry A.; Rahm, Dianne

Botswana is generally regarded as an African ‘success story’. Nearly four decades of unabated economic growth, multi-party democracy, conservative decision-making and low-levels of corruption have made Botswana the darling of the international donor community. One consequence of rapid and sustained economic development is that water resources use and demands have risen dramatically in a primarily arid/semi-arid environment. Policy makers recognize that supply is limited and that deliberate steps must be taken to manage demand. To this end, and in line with other members of the Southern African Development Community (SADC), Botswana devised a National Water Master Plan (NWMP) and undertook a series of institutional and legal reforms throughout the 1990s so as to make water resources use more equitable, efficient and sustainable. In other words, the stated goal is to work toward Integrated Water Resources Management (IWRM) in both policy and practice. However, policy measures have had limited impact on de facto practice. This paper reflects our efforts to understand the disjuncture between policy and practice. The information presented here combines a review of primary and secondary literatures with key informant interviews. It is our view that a number of constraints-cultural, power political, managerial-combine to hinder efforts toward sustainable forms of water resources use. If IWRM is to be realized in the country, these constraints must be overcome. This, however, is no small task.

Green Infrastructure Management Techniques in Arid and Semi-arid Regions: Software Implementation and Demonstration using the AGWA/KINEROS2 Watershed Model

EPA Science Inventory

Increasing urban development in the arid and semi-arid regions of the southwestern United States has led to greater demand for water in a region with limited water resources and has fundamentally altered the hydrologic response of developed watersheds. Green Infrastructure (GI) p...

International Arid Lands Consortium: Better land stewardship in water and watershed management

Treesearch

Peter F. Ffolliott; James T. Fisher; Menachem Sachs; Darrell W. DeBoer; Jeffrey O. Dawson; Timothy E. Fulbright; John Tracy

2000-01-01

The International Arid Lands Consortium (IALC) was established in 1990 to promote research, education, and training for the development, management, and restoration of arid and semi-arid lands throughout the world. One activity of IALC members and cooperators is to support research and development and demonstration projects that enhance management of these fragile...

Representing Green Infrastructure Management Techniques in Arid and Semi-arid Regions: Software Implementation and Demonstration using the AGWA/KINEROS2 Watershed Model

EPA Science Inventory

Increasing urban development in the arid and semi-arid regions of the southwestern United States has led to greater demand for water from a region of limited water resources which has fundamentally altered the hydrologic response of developed watersheds. Green Infrastructure (GI)...

Arid Green Infrastructure for Water Control and Conservation ...

EPA Pesticide Factsheets

Green infrastructure is an approach to managing wet weather flows using systems and practices that mimic natural processes. It is designed to manage stormwater as close to its source as possible and protect the quality of receiving waters. Although most green infrastructure practices were first developed in temperate climates, green infrastructure also can be a cost-effective approach to stormwater management and water conservation in arid and semi-arid regions, such as those found in the western and southwestern United States. Green infrastructure practices can be applied at the site, neighborhood and watershed scales. In addition to water management and conservation, implementing green infrastructure confers many social and economic benefits and can address issues of environmental justice. The U.S. Environmental Protection Agency (EPA) commissioned a literature review to identify the state-of-the science practices dealing with water control and conservation in arid and semi-arid regions, with emphasis on these regions in the United States. The search focused on stormwater control measures or practices that slow, capture, treat, infiltrate and/or store runoff at its source (i.e., green infrastructure). The material in Chapters 1 through 3 provides background to EPA’s current activities related to the application of green infrastructure practices in arid and semi-arid regions. An introduction to the topic of green infrastructure in arid and semi-arid regions i

Development of vegetation based soil quality indices for mineralized terrane in arid and semi-arid regions

Treesearch

S. W. Blecker; L. L. Stillings; M. C. Amacher; J. A. Ippolito; N. M. DeCrappeo

2012-01-01

Soil quality indices (SQIs) are often management driven and attempt to describe key relationships between above- and below-ground parameters. In terrestrial systems, indices that were initially developed and modified for agroecosystems have been applied to non-agricultural systems in increasing number. We develop an SQI in arid and semi-arid ecosystems of the Western...

ENSO elicits opposing responses of semi-arid vegetation between Hemispheres

NASA Astrophysics Data System (ADS)

Zhang, Anzhi; Jia, Gensuo; Epstein, Howard E.; Xia, Jiangjiang

2017-02-01

Semi-arid ecosystems are key contributors to the global carbon cycle and may even dominate the inter-annual variability (IAV) and trends of the land carbon sink, driven largely by the El Niño-Southern Oscillation (ENSO). The linkages between dynamics of semi-arid ecosystems and climate at the hemispheric scale however are not well known. Here, we use satellite data and climate observations from 2000 to 2014 to explore the impacts of ENSO on variability of semi-arid ecosystems, using the Ensemble Empirical Mode Decomposition method. We show that the responses of semi-arid vegetation to ENSO occur in opposite directions, resulting from opposing controls of ENSO on precipitation between the Northern Hemisphere (positively correlated to ENSO) and the Southern Hemisphere (negatively correlated to ENSO). Also, the Southern Hemisphere, with a robust negative coupling of temperature and precipitation anomalies, exhibits stronger and faster responses of semi-arid ecosystems to ENSO than the Northern Hemisphere. Our findings suggest that natural coherent variability in semi-arid ecosystem productivity responded to ENSO in opposite ways between two hemispheres, which may imply potential prediction of global semi-arid ecosystem variability, particularly based on variability in tropical Pacific Sea Surface Temperatures.

Arid5b facilitates chondrogenesis by recruiting the histone demethylase Phf2 to Sox9-regulated genes

NASA Astrophysics Data System (ADS)

Hata, Kenji; Takashima, Rikako; Amano, Katsuhiko; Ono, Koichiro; Nakanishi, Masako; Yoshida, Michiko; Wakabayashi, Makoto; Matsuda, Akio; Maeda, Yoshinobu; Suzuki, Yutaka; Sugano, Sumio; Whitson, Robert H.; Nishimura, Riko; Yoneda, Toshiyuki

2013-11-01

Histone modification, a critical step for epigenetic regulation, is an important modulator of biological events. Sox9 is a transcription factor critical for endochondral ossification; however, proof of its epigenetic regulation remains elusive. Here we identify AT-rich interactive domain 5b (Arid5b) as a transcriptional co-regulator of Sox9. Arid5b physically associates with Sox9 and synergistically induces chondrogenesis. Growth of Arid5b-/- mice is retarded with delayed endochondral ossification. Sox9-dependent chondrogenesis is attenuated in Arid5b-deficient cells. Arid5b recruits Phf2, a histone lysine demethylase, to the promoter region of Sox9 target genes and stimulates H3K9me2 demethylation of these genes. In the promoters of chondrogenic marker genes, H3K9me2 levels are increased in Arid5b-/- chondrocytes. Finally, we show that Phf2 knockdown inhibits Sox9-induced chondrocyte differentiation. Our findings establish an epigenomic mechanism of skeletal development, whereby Arid5b promotes chondrogenesis by facilitating Phf2-mediated histone demethylation of Sox9-regulated chondrogenic gene promoters.

Changes in precipitation recycling over arid regions in the Northern Hemisphere

NASA Astrophysics Data System (ADS)

Li, Ruolin; Wang, Chenghai; Wu, Di

2018-01-01

Changes of precipitation recycling (PR) in Northern Hemisphere from 1981 to 2010 are investigated using a water recycling model. The temporal and spatial characteristics of recycling in arid regions are analyzed. The results show that the regional precipitation recycling ratio (PRR) in arid regions is larger than in wet regions. PRR in arid regions has obvious seasonal variation, ranging from more than 25 % to less than 1 %. Furthermore, in arid regions, PRR is significantly negatively correlated with precipitation (correlation coefficient r = -0.5, exceeding the 99 % significance level). Moreover, the trend of PRR is related to changes in precipitation in two ways. PRR decreases with increasing precipitation in North Africa, which implies that less locally evaporated vapor converts into actual precipitation. However, in Asian arid regions, the PRR increases as precipitation reduces, which implies that more locally evaporated vapor converts into rainfall. Further, as PRR mainly depends on evapotranspiration, the PRR trend in Asian arid regions develops as temperature increases and more evaporated vapor enters the atmosphere to offset the reduced rainfall.

Deep Percolation in Arid Piedmont Slopes: Multiple Lines of Evidence Show How Land Use Change and Ecohydrological Properties Affect Groundwater Recharge

NASA Astrophysics Data System (ADS)

Schreiner-McGraw, A.; Vivoni, E. R.; Browning, D. M.

2017-12-01

A critical hydrologic process in arid regions is the contribution of episodic streamflow in ephemeral channels to groundwater recharge. This process has traditionally been studied in channels that drain large watersheds (10s to 100s km2). In this study, we aim to characterize the provision of the ecosystem services of surface and groundwater supply in a first-order watershed (4.6 ha) in an arid piedmont slope of the Jornada Experimental Range (JER). We use an observational and modeling approach to estimate deep percolation. During a 6 year study period, we observed 428 mm of percolation (P) and 39 mm of runoff (Q); ratios of P to rainfall (R) of P/R = 0.27 and Q/R = 0.02. Utilizing an instrument network and site measurements, we determine that percolation occurs primarily inside channel reaches when these receive runoff from upland hillslopes and find that a monthly rainfall threshold of 62 mm is needed for significant percolation to be generated. In order to quantify the mechanisms leading to this threshold response, we develop a channel transmission loss module for the TIN-based Real-time Integrated Basin Simulator (tRIBS) and test the model thoroughly against the available observations over the study period. For these purposes, we make use of image classifications from Unmanned Aerial Vehicle flights, a ground-based phenocam, and species-level measurements to parameterize vegetation processes in the model. We then conduct an extensive set of sensitivity experiments to determine the relative roles of channel, soil, and vegetation properties on modifying the relation between monthly rainfall and percolation. Additionally, we test how the observed vegetation transitions in the JER over the last 150 years affect the deep percolation and runoff estimates. By quantifying mechanisms through which vegetation changes affect water resource provision, this work provides new insights on the ecohydrological controls on the water yield of arid piedmont slopes.

Multi-resolution integrated modeling for basin-scale water resources management and policy analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Hoshin V.; Brookshire, David S.; Springer, E. P.

Approximately one-third of the land surface of the Earth is considered to be arid or semi-arid with an annual average of less than 12-14 inches of rainfall. The availability of water in such regions is of course, particularly sensitive to climate variability while the demand for water is experiencing explosive population growth. The competition for available water is exerting considerable pressure on the water resources management. Policy and decision makers in the southwestern U.S. increasingly have to cope with over-stressed rivers and aquifers as population and water demands grow. Other factors such as endangered species and Native American water rightsmore » further complicate the management problems. Further, as groundwater tables are drawn down due to pumping in excess of natural recharge, considerable (potentially irreversible) environmental impacts begin to be felt as, for example, rivers run dry for significant portions of the year, riparian habitats disappear (with consequent effects on the bio-diversity of the region), aquifers compact resulting in large scale subsidence, and water quality begins to suffer. The current drought (1999-2002) in the southwestern U.S. is raising new concerns about how to sustain the combination of agricultural, urban and in-stream uses of water that underlie the socio-economic and ecological structure in the region. The water stressed nature of arid and semi-arid environments means that competing water uses of various kinds vie for access to a highly limited resource. If basin-scale water sustainability is to be achieved, managers must somehow achieve a balance between supply and demand throughout the basin, not just for the surface water or stream. The need to move water around a basin such as the Rio Grande or Colorado River to achieve this balance has created the stimulus for water transfers and water markets, and for accurate hydrologic information to sustain such institutions [Matthews et al. 2002; Brookshire et al 2003; Krause, Chermak Brookshire, 2003].« less

Contrasting Responses of Ecosystem Carbon Gain (Input) and Soil Carbon Efflux (Output) to Warming and Drought Across a European Aridity Gradient

NASA Astrophysics Data System (ADS)

Cosby, J.; Reinsch, S.; Koehler, E.; de Dato, G.; Estiarte, M.; Guidolotti, G.; Kovacs-Lang, E.; Dukes, J.; Kröel-Dulay, G.; Larsen, K. S.; Lellei-Kovács, E.; Liberati, D.; Ransijn, J.; Schmidt, I. K.; Smith, A. R.; Sowerby, A.; Emmett, B.

2015-12-01

Understanding the relationship between aboveground and belowground processes are crucial to understand if we are to forecast feedbacks between terrestrial carbon (C) dynamics and future climate. To test if climate induced changes in annual aboveground net primary production (ANPP) will drive changes in C loss by soil respiration (Rs) we integrated data across a European temperature and precipitation gradient. Six European shrublands were exposed to year-round, night time warming (+1.5 oC) or repeated drought (-30% annual rain) during the plants growth season for over a decade, using an identical experimental approach. As a result, drought reduced ecosystem C gain as ANPP by 50% (compared to an untreated control) at the driest xeric site with effects reducing in intensity across the aridity gradient to a 15% ANPP-C gain at the wettest hydric site (slope=1.2, R2=0.76). In contrast, reductions in Rs-C loss were of a lower magnitude (0-15%) and increased in intensity across the aridity gradient (slope=-0.44, R2=0.76) if the hydric site was excluded. These results suggest (i) above and belowground C fluxes responses do not track each other in response to drought and (ii) whilst ANPP at our hydric sites follows that predicted from an aridity gradient, Rs responses did not. Results from the warming treatments were generally of lower magnitude and opposite direction indicating different mechanisms were driving responses. Overall, these results suggest that ANPP is more sensitive than Rs to climate stresses and soil respiration C fluxes are not predictable from changes in plant productivity. Indirect effects on soil properties and/or microbial communities need to be explored. As we observed no acclimation of either ANPP or Rs after over a decade of treatments, feedbacks between the terrestrial C cycle and climate may not weaken over decadal timescales at larger, continental scales.

The use of spatial empirical models to estimate soil erosion in arid ecosystems.

PubMed

Abdullah, Meshal; Feagin, Rusty; Musawi, Layla

2017-02-01

The central objective of this project was to utilize geographical information systems and remote sensing to compare soil erosion models, including Modified Pacific South-west Inter Agency Committee (MPSIAC), Erosion Potential Method (EPM), and Revised Universal Soil Loss Equation (RUSLE), and to determine their applicability for arid regions such as Kuwait. The northern portion of Umm Nigga, containing both coastal and desert ecosystems, falls within the boundaries of the de-militarized zone (DMZ) adjacent to Iraq and has been fenced off to restrict public access since 1994. Results showed that the MPSIAC and EPM models were similar in spatial distribution of erosion, though the MPSIAC had a more realistic spatial distribution of erosion and presented finer level details. The RUSLE presented unrealistic results. We then predicted the amount of soil loss between coastal and desert areas and fenced and unfenced sites for each model. In the MPSIAC and EPM models, soil loss was different between fenced and unfenced sites at the desert areas, which was higher at the unfenced due to the low vegetation cover. The overall results implied that vegetation cover played an important role in reducing soil erosion and that fencing is much more important in the desert ecosystems to protect against human activities such as overgrazing. We conclude that the MPSIAC model is best for predicting soil erosion for arid regions such as Kuwait. We also recommend the integration of field-based experiments with lab-based spatial analysis and modeling in future research.

Spatial complexities in aboveground carbon stocks of a semi-arid mangrove community: A remote sensing height-biomass-carbon approach

NASA Astrophysics Data System (ADS)

Hickey, S. M.; Callow, N. J.; Phinn, S.; Lovelock, C. E.; Duarte, C. M.

2018-01-01

Mangroves are integral to ecosystem services provided by the coastal zone, in particular carbon (C) sequestration and storage. Allometric relationships linking mangrove height to estimated biomass and C stocks have been developed from field sampling, while various forms of remote sensing has been used to map vegetation height and biomass. Here we combine both these approaches to investigate spatial patterns in living biomass of mangrove forests in a small area of mangrove in north-west Australia. This study used LiDAR data and Landsat 8 OLI (Operational Land Imager) with allometric equations to derive mangrove height, biomass, and C stock estimates. We estimated the study site, Mangrove Bay, a semi-arid site in north-western Australia, contained 70 Mg ha-1 biomass and 45 Mg C ha-1 organic C, with total stocks of 2417 Mg biomass and 778 Mg organic C. Using spatial statistics to identify the scale of clustering of mangrove pixels, we found that living biomass and C stock declined with increasing distance from hydrological features (creek entrance: 0-150 m; y = -0.00041x + 0.9613, R2 = 0.96; 150-770 m; y = -0.0008x + 1.6808, R2 = 0.73; lagoon: y = -0.0041x + 3.7943, R2 = 0.78). Our results illustrate a set pattern of living C distribution within the mangrove forest, and then highlight the role hydrologic features play in determining C stock distribution in the arid zone.

Green-blue water system innovations for upgrading of smallholder farming systems--a policy framework for development.

PubMed

Hatibu, N; Rockström, J

2005-01-01

Rainfed agriculture and other depletion of water by green flows have as yet an untapped potential for improving livelihoods in semi-arid areas through income and food security. A vivid evidence of this is seen in the fact that, although working full time on food production, majority of smallholder farmers are frequently affected by shortage of food or famines. At the same time enough examples exist to show that productivity of labor, water and land under rainfed farming can be doubled or even trebled through proper land management and improved agronomic inputs supported by modest investments to reduce impacts of dry spells. However, these shining examples remain small 'islands of success' across the entire semi-arid areas. Farmers have not adopted these systems due to poor ratio of benefit to costs brought about by inadequate development or complete lack of food trade among the rural areas. This paper argues that there is a need for policy, strategic and programmatic frameworks which facilitate integrated management of land, water and markets. For this kind of strategy to work, a local market for food should be ensured to absorb at competitive prices the surplus produced by farmers in years of good rains. This will promote wealth creation and asset building among the poor in semi-arid areas. A food-exchange "futures" mechanism based on the principle of virtual water trade is proposed as a basis for achieving this objective.

Irrigated agriculture and groundwater resources - towards an integrated vision and sustainable relationship.

PubMed

Foster, Stephen; Garduño, Héctor

2013-01-01

Globally, irrigated agriculture is the largest abstractor, and predominant consumer, of groundwater resources, with large groundwater-dependent agro-economies now having widely evolved especially in Asia. Such use is also causing resource depletion and degradation in more arid and drought-prone regions. In addition crop cultivation practices on irrigated land exert a major influence on groundwater recharge. The interrelationship is such that cross-sector action is required to agree more sustainable land and water management policies, and this paper presents an integrated vision of the challenges in this regard. It is recognised that 'institutional arrangements' are critical to the local implementation of management policies, although the focus here is limited to the conceptual understanding needed for formulation of an integrated policy and some practical interventions required to promote more sustainable groundwater irrigation.

Don’t bust the biological soil crust: Preserving and restoring an important desert resource

Treesearch

Sue Miller; Steve Warren; Larry St. Clair

2017-01-01

Biological soil crusts are a complex of microscopic organisms growing on the soil surface in many arid and semi-arid ecosystems. These crusts perform the important role of stabilizing soil and reducing or eliminating water and wind erosion. One of the largest threats to biological soil crusts in the arid and semi-arid areas of the western United States is mechanical...

Geoenvironmental and structural studies for developing new water resources in arid and semi-arid regions using remote sensing and GIS

NASA Astrophysics Data System (ADS)

Amer, Reda Mohammed

2011-12-01

Water crises are rising with increasing world population and decreasing of freshwater resources. This problem is magnified in the arid and semi-arid regions because surface water resources are very limited and highly unreliable and therefore groundwater is the primary source of water supply in these regions. This study presents an integrated approach for the identification of groundwater occurrences using remote sensing, geological, and geophysical data, and establishing sustainable paths to groundwater management. The Central Eastern Desert (CED) of Egypt was selected as a test site for this study because its climate is arid and there is an urgent need to identify potential areas for groundwater accumulations. Field investigations indicated that the CED has three types of aquifers; shallow alluvial (SA), and fracture zone (FZ) aquifers in the valley depressions, and deep aquifers in the sedimentary succession that range in age from Late Cretaceous to Recent in the marginal extensional sub-basins (ESB) along the Red Sea coast. I developed three models: (1) a Geographic Information System (GIS) model for groundwater potential in the SA and FZ shallow aquifers; (2) a kinematic model for the development of the ESB; and (3) a groundwater budget model for the ESB aquifers. The GIS model is based on the analysis of remote sensing data of the Phased Array L-band Synthetic Aperture Radar, the Landsat Enhanced Thematic Mapper Plus, and the Advanced Spaceborne Thermal Emission and Reflection Radiometer digital elevation model. The model was evaluated and proven successful against the existing shallow water wells, and by geophysical surveys using Ground Penetrating Radar and Geoelectric methods. The kinematic model indicated that the ESB were formed in the orthogonal rifting phase in the late Oligocene that is followed by oblique rifting phase during the early Miocene which resulted to the en-echelon pattern of the inland ESB and nucleation of the rift depression into segments separated by oblique-slip accommodation zones. The groundwater budget model shows that the ESB aquifers have considerable amounts of paleowater that can be purified and used for drinking. The renewable groundwater of SA and FZ aquifers can be used for herding, irrigation, and ore dressing in the mining zones.

VOCs in Non-Arid Soils Integrated Demonstration: Technology summary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1994-02-01

The Volatile Organic Compounds (VOCs) in Non-Arid Soils Integrated Demonstration (ID) was initiated in 1989. Objectives for the ID were to test the integrated demonstration concept, demonstrate and evaluate innovative technologies/systems for the remediation of VOC contamination in soils and groundwater, and to transfer technologies and systems to internal and external customers for use in fullscale remediation programs. The demonstration brought together technologies from DOE laboratories, other government agencies, and industry for demonstration at a single test bed. The Savannah River Site was chosen as the location for this ID as the result of having soil and groundwater contaminated withmore » VOCS. The primary contaminants, trichlorethylene and tetrachloroethylene, originated from an underground process sewer line servicing a metal fabrication facility at the M-Area. Some of the major technical accomplishments for the ID include the successful demonstration of the following: In situ air stripping coupled with horizontal wells to remediate sites through air injection and vacuum extraction; Crosshole geophysical tomography for mapping moisture content and lithologic properties of the contaminated media; In situ radio frequency and ohmic heating to increase mobility, of the contaminants, thereby speeding recovery and the remedial process; High-energy corona destruction of VOCs in the off-gas of vapor recovery wells; Application of a Brayton cycle heat pump to regenerate carbon adsorption media used to trap VOCs from the offgas of recovery wells; In situ permeable flow sensors and the colloidal borescope to determine groundwater flow; Chemical sensors to rapidly quantify chlorinated solvent contamination in the subsurface; In situ bioremediation through methane/nutrient injection to enhance degradation of contaminants by methanotrophic bateria.« less

Competing Influences of Anthropogenic Warming, ENSO, and Plant Physiology on Future Terrestrial Aridity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonfils, Céline; Anderson, Gemma; Santer, Benjamin D.

The 2011–16 California drought illustrates that drought-prone areas do not always experience relief once a favorable phase of El Niño–Southern Oscillation (ENSO) returns. In the twenty-first century, such an expectation is unrealistic in regions where global warming induces an increase in terrestrial aridity larger than the changes in aridity driven by ENSO variability. This premise is also flawed in areas where precipitation supply cannot offset the global warming–induced increase in evaporative demand. Here, atmosphere-only experiments are analyzed to identify land regions where aridity is currently sensitive to ENSO and where projected future changes in mean aridity exceed the range causedmore » by ENSO variability. Insights into the drivers of these changes in aridity are obtained using simulations with the incremental addition of three different factors to the current climate: ocean warming, vegetation response to elevated CO 2 levels, and intensified CO 2 radiative forcing. The effect of ocean warming overwhelms the range of ENSO-driven temperature variability worldwide, increasing potential evapotranspiration (PET) in most ENSO-sensitive regions. Additionally, about 39% of the regions currently sensitive to ENSO will likely receive less precipitation in the future, independent of the ENSO phase. Consequently aridity increases in 67%–72% of the ENSO-sensitive area. When both radiative and physiological effects are considered, the area affected by arid conditions rises to 75%–79% when using PET-derived measures of aridity, but declines to 41% when an aridity indicator for total soil moisture is employed. This reduction mainly occurs because plant stomatal resistance increases under enhanced CO 2 concentrations, resulting in improved plant water-use efficiency, and hence reduced evapotranspiration and soil desiccation. Imposing CO 2-invariant stomatal resistance may overestimate future drying in PET-derived indices.« less

Competing Influences of Anthropogenic Warming, ENSO, and Plant Physiology on Future Terrestrial Aridity

DOE PAGES

Bonfils, Céline; Anderson, Gemma; Santer, Benjamin D.; ...

2017-07-27

The 2011–16 California drought illustrates that drought-prone areas do not always experience relief once a favorable phase of El Niño–Southern Oscillation (ENSO) returns. In the twenty-first century, such an expectation is unrealistic in regions where global warming induces an increase in terrestrial aridity larger than the changes in aridity driven by ENSO variability. This premise is also flawed in areas where precipitation supply cannot offset the global warming–induced increase in evaporative demand. Here, atmosphere-only experiments are analyzed to identify land regions where aridity is currently sensitive to ENSO and where projected future changes in mean aridity exceed the range causedmore » by ENSO variability. Insights into the drivers of these changes in aridity are obtained using simulations with the incremental addition of three different factors to the current climate: ocean warming, vegetation response to elevated CO 2 levels, and intensified CO 2 radiative forcing. The effect of ocean warming overwhelms the range of ENSO-driven temperature variability worldwide, increasing potential evapotranspiration (PET) in most ENSO-sensitive regions. Additionally, about 39% of the regions currently sensitive to ENSO will likely receive less precipitation in the future, independent of the ENSO phase. Consequently aridity increases in 67%–72% of the ENSO-sensitive area. When both radiative and physiological effects are considered, the area affected by arid conditions rises to 75%–79% when using PET-derived measures of aridity, but declines to 41% when an aridity indicator for total soil moisture is employed. This reduction mainly occurs because plant stomatal resistance increases under enhanced CO 2 concentrations, resulting in improved plant water-use efficiency, and hence reduced evapotranspiration and soil desiccation. Imposing CO 2-invariant stomatal resistance may overestimate future drying in PET-derived indices.« less

Green Infrastructure for Arid Communities

EPA Pesticide Factsheets

how green infrastructure practices and the many associated benefits can be effective not only in wetter climates, but also for those communities in arid and semi-arid regions around the nation that have different precipitation patterns

Changes in Spatial Patterns of Caragana stenophylla along a Climatic Drought Gradient on the Inner Mongolian Plateau

PubMed Central

Xie, Li-Na; Guo, Hong-Yu; Gabler, Christopher A.; Li, Qing-Fang; Ma, Cheng-Cang

2015-01-01

Few studies have investigated the influence of water availability on plant population spatial patterns. We studied changes in the spatial patterns of Caragana stenophylla along a climatic drought gradient within the Inner Mongolian Plateau, China. We examined spatial patterns, seed density, “nurse effects” of shrubs on seedlings, transpiration rates and water use efficiency (WUE) of C. stenophylla across semi-arid, arid, and intensively arid zones. Our results showed that patches of C. stenophylla populations shifted from a random to a clumped spatial pattern towards drier environments. Seed density and seedling survival rate of C. stenophylla decreased from the semi-arid zone to the intensively arid zone. Across the three zones, there were more C. stenophylla seeds and seedlings underneath shrub canopies than outside shrub canopies; and in the intensively arid zone, there were almost no seeds or seedlings outside shrub canopies. Transpiration rates of outer-canopy leaves and WUE of both outer-canopy and inner-canopy leaves increased from the semi-arid zone to the intensively arid zone. In the intensively arid zone, transpiration rates and WUE of inner-canopy leaves were significantly lower and higher, respectively, than those of outer-canopy leaves. We conclude that, as drought stress increased, seed density decreased, seed proportions inside shrubs increased, and “nurse effects” of shrubs on seedlings became more important. These factors, combined with water-saving characteristics associated with clumped spatial patterns, are likely driving the changes in C. stenophylla spatial patterns. PMID:25785848

More than ten million years of hyper-aridity recorded in the Atacama Gravels

NASA Astrophysics Data System (ADS)

Sun, Tao; Bao, Huiming; Reich, Martin; Hemming, Sidney R.

2018-04-01

The Atacama Desert's hyper-aridity is closely linked to the development of world-class copper and nitrate/iodine ores and to regional tectonics and global paleoclimate changes in the Cenozoic era. The timing when the hyper-aridity commenced remains controversial, with proposed ages ranging from Late Oligocene to Pleistocene. In this study, we provide an independent constraint on the initiation of Atacama hyper-aridity utilizing a 100-m deep profile within the Atacama Gravels and underneath porphyry copper deposit in Spence, northern Chile. The overall high concentration of sulfate (up to 10 wt%) and a multimodal distribution of water soluble salt (sulfates, chlorides and nitrates) indicate multiple generations of sedimentation and salt accumulation events under semi-arid to hyper-arid climate conditions. The multiple sulfate isotope compositions (Δ17O, δ18O, δ34S) of the upper section (-15.0 to -34.5 m) are close to those of modern hyperarid surface sulfates, while the lower section (-34.5 to -65 m) displays a depth dependent isotope trend that is best interpreted as marking a period of climate change from semi-arid to hyper-arid. When these data are combined with new chronological 40Ar/39Ar dates obtained from a volcanic ash layer at depth of -28.0 m, our results show that hyper-arid condition in the Atacama Desert was prevailing at least prior to 9.47 Ma and may go back as old as the middle Miocene.

An integrated assessment of soil erosion dynamics with special emphasis on gully erosion: Case studies from South Africa and Iran

NASA Astrophysics Data System (ADS)

Maerker, Michael; Sommer, Christian; Zakerinejad, Reza; Cama, Elena

2017-04-01

Soil erosion by water is a significant problem in arid and semi arid areas of large parts of Iran. Water erosion is one of the most effective phenomena that leads to decreasing soil productivity and pollution of water resources. Especially in semiarid areas like in the Mazayjan watershed in the Southwestern Fars province as well as in the Mkomazi catchment in Kwa Zulu Natal, South Africa, gully erosion contributes to the sediment dynamics in a significant way. Consequently, the intention of this research is to identify the different types of soil erosion processes acting in the area with a stochastic approach and to assess the process dynamics in an integrative way. Therefore, we applied GIS, and satellite image analysis techniques to derive input information for the numeric models. For sheet and rill erosion the Unit Stream Power-based Erosion Deposition Model (USPED) was utilized. The spatial distribution of gully erosion was assessed using a statistical approach which used three variables (stream power index, slope, and flow accumulation) to predict the spatial distribution of gullies in the study area. The eroded gully volumes were estimated for a multiple years period by fieldwork and Google Earth high resolution images as well as with structure for motion algorithm. Finally, the gully retreat rates were integrated into the USPED model. The results show that the integration of the SPI approach to quantify gully erosion with the USPED model is a suitable method to qualitatively and quantitatively assess water erosion processes in data scarce areas. The application of GIS and stochastic model approaches to spatialize the USPED model input yield valuable results for the prediction of soil erosion in the test areas. The results of this research help to develop an appropriate management of soil and water resources in the study areas.

Achieving Sustainability in a Semi-Arid Basin in Northwest Mexico through an Integrated Hydrologic-Economic-Institutional Model

NASA Astrophysics Data System (ADS)

Munoz-Hernandez, A.; Mayer, A. S.

2008-12-01

The hydrologic systems in Northwest Mexico are at risk of over exploitation due to poor management of the water resources and adverse climatic conditions. The purpose of this work is to create and Integrated Hydrologic-Economic-Institutional Model to support future development in the Yaqui River basin, well known by its agricultural productivity, by directing the water management practices toward sustainability. The Yaqui River basin is a semi-arid basin with an area of 72,000 square kilometers and an average precipitation of 527 mm per year. The primary user of water is agriculture followed by domestic use and industry. The water to meet user demands comes from three reservoirs constructed, in series, along the river. The main objective of the integrated simulation-optimization model is to maximize the economic benefit within the basin, subject to physical and environmental constraints. Decision variables include the water allocation to major users and reservoirs as well as aquifer releases. Economic and hydrologic (including the interaction of the surface water and groundwater) simulation models were both included in the integrated model. The surface water model refers to a rainfall-runoff model created, calibrated, and incorporated into a MATLAB code that estimates the monthly storage in the main reservoirs by solving a water balance. The rainfall-runoff model was coupled with a groundwater model of the Yaqui Valley which was previously developed (Addams, 2004). This model includes flow in the main canals and infiltration to the aquifer. The economic benefit of water for some activities such as agricultural use, domestic use, hydropower generation, and environmental value was determined. Sensitivity analysis was explored for those parameters that are not certain such as price elasticities or population growth. Different water allocation schemes were created based on climate change, climate variability, and socio-economic scenarios. Addams L. 2004. Water resource policy evaluation using a combined hydrologic-economic-agronomic modeling framework: Yaqui Valley, Sonora, Mexico. Ph.D.dissertation, Stanford University.

[A research review on "fertile islands" of soils under shrub canopy in arid and semi-arid regions].

PubMed

Chen, Guangsheng; Zeng, Dehui; Chen, Fusheng; Fan, Zhiping; Geng, Haiping

2003-12-01

Due to the inclemency of climate and soil conditions and the intense disturbance of human beings, the soil resources heterogeneity in arid and semi-arid grassland ecosystems worldwide was gradually increased during the last century. The interaction between soil heterogeneity and shrubs induced the autogenic development of "fertile islands" and the increasing spread of shrubs in the grassland ecosystems. The development of "fertile islands" around individual shrubs could change the vegetation composition and structure, as well as the distribution patterns of soil resources, and thus, reinforced the changes of the ecosystem function and structure from a relative stable grassland ecosystem to a quasi-stable shrubland ecosystem. The study of "fertile islands" phenomenon would help us to understand the causes, consequences and processes of desertification in arid and semi-arid areas. In this paper, the causes of "fertile islands", its study methods and significance and its relationship with shrub spreading as well as the responses of vegetation to it were summarized. The problems which might occur in the study of this phenomenon were also pointed out. Our aim was to offer some references to the study of land desertification processes and vegetation restoration in the arid and semi-arid regions.

Enlargement of the semi-arid region in China from 1961 to 2010

NASA Astrophysics Data System (ADS)

Yin, Yunhe; Ma, Danyang; Wu, Shaohong

2018-02-01

Due to spatial and temporal heterogeneity in moisture conditions, the responses of arid/humid climate regions (AHCR) to climate change are complex. In this study, we delineated the AHCR of China using information about the balance of the atmospheric water supply and demand collected from 581 meteorological stations over the past 50 years. We also analyzed inter-decadal shifts and linear trends in the AHCR and examined the influence of precipitation and reference evapotranspiration. The results indicate that the semi-arid region expanded significantly over the last five decades, mainly in northwest China, northern China, and the Tibetan Plateau and, by the 2000s, had increased by 33.53% relative to its extent in the 1960s; in contrast, the arid region shrank by 20.75%. The semi-arid region grew mainly because of transfers from the arid region in western China and the sub-humid region in eastern China. The decreased reference evapotranspiration and significantly increased precipitation together contributed to the expansion of the semi-arid region in northwest China and the Tibetan Plateau over the last 50 years. In contrast, the expansion of the semi-arid region in Inner Mongolia and northern China reflects the counteractive influence of decreased reference evapotranspiration and decreased precipitation.

Impacts of Climate Anomalies on the Vegetation Patterns in the Arid and Semi-Arid Zones of Uzbekistan

NASA Astrophysics Data System (ADS)

Dildora, Aralova; Toderich, Kristina; Dilshod, Gafurov

2016-08-01

Steadily rising temperature anomalies in last decades are causing changes in vegetation patterns for sensitive to climate change in arid and semi-arid dryland ecosystems. After desiccation of the Aral Sea, Uzbekistan has been left with the challenge to develop drought and heat stress monitoring system and tools (e.g., to monitor vegetation status and/crop pattern dynamics) with using remote sensing technologies in broad scale. This study examines several climate parameters, NDVI and drought indexes within geostatistical method to predict further vegetation status in arid and semi-arid zones of landscapes. This approaches aimed to extract and utilize certain variable environmental data (temperature and precipitation) for assessment and inter-linkages of vegetation cover dynamics, specifically related to predict degraded and recovered zones or desertification process in the drylands due to scarcity of water resources and high risks of climate anomalies in fragile ecosystem of Uzbekistan.

a Proposed New Vegetation Index, the Total Ratio Vegetation Index (trvi), for Arid and Semi-Arid Regions

NASA Astrophysics Data System (ADS)

Fadaei, H.; Suzuki, R.; Sakai, T.; Torii, K.

2012-07-01

Vegetation indices that provide important key to predict amount vegetation in forest such as percentage vegetation cover, aboveground biomass, and leaf-area index. Arid and semi-arid areas are not exempt of this rule. Arid and semi-arid areas of northeast Iran cover about 3.4 million ha and are populated by two main tree species, the broadleaf Pistacia vera (pistachio) and the conifer Juniperus excelsa ssp. polycarpos (Persian juniper). Natural stands of pistachio in Iran are not only environmentally important but also genetically essential as seed sources for pistachio production in orchards. We investigated the relationships between tree density and vegetation indices in the arid and semi-arid regions in the northeast of Iran by analysing Advanced Land Observing Satellite (ALOS) data PRISM is a panchromatic radiometer with a 2.5 m spatial resolution at nadir, and has one band with a wavelength of 0.52-0.77 μm (JAXA EORC). AVNIR-2 is a visible and near infrared radiometer for observing land and coastal zones with a 10 m spatial resolution at nadir, and has four multispectral bands: blue (0.42-0.50 μm), green (0.52-0.60 μm), red (0.61-0.69 μm), and near infrared (0.76-0.89 μm) (JAXA EORC). In this study, we estimated various vegetation indices using maximum filtering algorithm (5×5) and examined. This study carried out of juniper forests and natural pistachio stand using Advanced Land Observing Satellite (ALOS) and field inventories. Have been compared linear regression model of vegetation indices and proposed new vegetation index for arid and semi-arid regions. Also, we estimated the densities of juniper forests and natural pistachio stands using remote sensing to help in the sustainable management and production of pistachio in Iran. We present a new vegetation index for arid and semi-arid regions with sparse forest cover, the Total Ratio Vegetation Index (TRVI), and we investigate the relationship of the new index to tree density by analysing data from the Advanced Land Observing Satellite (ALOS) using 5×5 maximum filtering algorithms. The results for pistachio forest showed the coefficient regression of NDVI, SAVI, MSAVI, OSAVI, and TRVI were (R2= 0.68, 0.67, 0.68, 0.68, and 0.71) respectively. The results for juniper forest showed the coefficient regression of NDVI, SAVI, MSAVI, OSAVI, and TRVI were (R2= 0.51, 0.52, 0.51, 0.52, and 0.56) respectively. I hope this research can provide decision of managers to helping sustainable management for arid and semi-arid regions in Iran.

Coffin-Siris syndrome and the BAF complex: genotype-phenotype study in 63 patients.

PubMed

Santen, Gijs W E; Aten, Emmelien; Vulto-van Silfhout, Anneke T; Pottinger, Caroline; van Bon, Bregje W M; van Minderhout, Ivonne J H M; Snowdowne, Ronelle; van der Lans, Christian A C; Boogaard, Merel; Linssen, Margot M L; Vijfhuizen, Linda; van der Wielen, Michiel J R; Vollebregt, M J Ellen; Breuning, Martijn H; Kriek, Marjolein; van Haeringen, Arie; den Dunnen, Johan T; Hoischen, Alexander; Clayton-Smith, Jill; de Vries, Bert B A; Hennekam, Raoul C M; van Belzen, Martine J

2013-11-01

De novo germline variants in several components of the SWI/SNF-like BAF complex can cause Coffin-Siris syndrome (CSS), Nicolaides-Baraitser syndrome (NCBRS), and nonsyndromic intellectual disability. We screened 63 patients with a clinical diagnosis of CSS for these genes (ARID1A, ARID1B, SMARCA2, SMARCA4, SMARCB1, and SMARCE1) and identified pathogenic variants in 45 (71%) patients. We found a high proportion of variants in ARID1B (68%). All four pathogenic variants in ARID1A appeared to be mosaic. By using all variants from the Exome Variant Server as test data, we were able to classify variants in ARID1A, ARID1B, and SMARCB1 reliably as being pathogenic or nonpathogenic. For SMARCA2, SMARCA4, and SMARCE1 several variants in the EVS remained unclassified, underlining the importance of parental testing. We have entered all variant and clinical information in LOVD-powered databases to facilitate further genotype-phenotype correlations, as these will become increasingly important because of the uptake of targeted and untargeted next generation sequencing in diagnostics. The emerging phenotype-genotype correlation is that SMARCB1 patients have the most marked physical phenotype and severe cognitive and growth delay. The variability in phenotype seems most marked in ARID1A and ARID1B patients. Distal limbs anomalies are most marked in ARID1A patients and least in SMARCB1 patients. Numbers are small however, and larger series are needed to confirm this correlation. © 2013 WILEY PERIODICALS, INC.

The disparity between extreme rainfall events and rare floods - with emphasis on the semi-arid American West

NASA Astrophysics Data System (ADS)

Osterkamp, W. R.; Friedman, J. M.

2000-10-01

Research beginning 40 years ago suggested that semi-arid lands of the USA have higher unit discharges for a given recurrence interval than occur in other areas. Convincing documentation and arguments for this suspicion, however, were not presented. Thus, records of measured rainfall intensities for specified durations and recurrence intervals, and theoretical depths of probable maximum precipitation for specified recurrence intervals and areal scales are considered here for comparing extreme rainfalls of semi-arid areas with those of other climatic areas. Runoff from semi-arid lands, as peaks of rare floods, is compared with that of other areas using various published records. Relative to humid areas, semi-arid parts of the conterminous USA have lower 100-year, 6-h rainfall intensities and smaller depths of 100-year probable maximum precipitation for 26-km2 areas. Nonetheless, maximum flood peaks, flash-flood potentials, and runoff potentials are generally larger in semi-arid areas than in more humid parts of the nation. Causes of this disparity between rainfall and runoff appear to be results of soil and vegetation that in humid areas absorb and intercept rainfall and attenuate runoff, but in semi-arid areas limit infiltration and enhance runoff from bare, crusted surfaces. These differences in soil and vegetation conditions are indicated by the relatively high curve numbers and drainage densities that are typical of semi-arid areas. Owing to soil and vegetation conditions, rare floods in semi-arid areas are more likely to cause landform change than are floods of similar magnitude elsewhere.

The disparity between extreme rainfall events and rare floods - with emphasis on the semi-arid American West

USGS Publications Warehouse

Osterkamp, W.R.; Friedman, J.M.

2000-01-01

Research beginning 40 years ago suggested that semi-arid lands of the USA have higher unit discharges for a given recurrence interval than occur in other areas. Convincing documentation and arguments for this suspicion, however, were not presented. Thus, records of measured rainfall intensities for specified durations and recurrence intervals, and theoretical depths of probable maximum precipitation for specified recurrence intervals and areal scales are considered here for comparing extreme rainfalls of semi-arid areas with those of other climatic areas. Runoff from semi-arid lands, as peaks of rare floods, is compared with that of other areas using various published records. Relative to humid areas, semi-arid parts of the conterminous USA have lower 100-year, 6-h rainfall intensities and smaller depths of 100-year probable maximum precipitation for 26-km2 areas. Nonetheless, maximum flood peaks, flash-flood potentials, and runoff potentials are generally larger in semi-arid areas than in more humid parts of the nation. Causes of this disparity between rainfall and runoff appear to be results of soil and vegetation that in humid areas absorb and intercept rainfall and attenuate runoff, but in semi-arid areas limit infiltration and enhance runoff from bare, crusted surfaces. These differences in soil and vegetation conditions are indicated by the relatively high curve numbers and drainage densities that are typical of semi-arid areas. Owing to soil and vegetation conditions, rare floods in semi-arid areas are more likely to cause landform change than are floods of similar magnitude elsewhere.

Investigations on the Aridity Paradox

NASA Astrophysics Data System (ADS)

Donohue, R. J.; Roderick, M. L.

2014-12-01

How global aridity might change in the immediate future is an important question. Several recent analyses have concluded that aridity will, in general, increase over land primarily because of increasing vapour pressure deficit. Taken at face value that result is difficult to understand because a warmer world is also anticipated to be a moister world. For example, at the global scale, climate model projections are for increasing rainfall and runoff. In this presentation we investigate this seeming paradox. We find that the previous analyses have not accounted for the biological impacts of elevated CO2 and when that is incorporated, the climate model projections are for a modest reduction in meteorological and hydrologic aridity and for larger reductions in biological aridity.

Productivity responses of desert vegetation to precipitation patterns across a rainfall gradient.

PubMed

Li, Fang; Zhao, Wenzhi; Liu, Hu

2015-03-01

The influences of previous-year precipitation and episodic rainfall events on dryland plants and communities are poorly quantified in the temperate desert region of Northwest China. To evaluate the thresholds and lags in the response of aboveground net primary productivity (ANPP) to variability in rainfall pulses and seasonal precipitation along the precipitation-productivity gradient in three desert ecosystems with different precipitation regimes, we collected precipitation data from 2000 to 2012 in Shandan (SD), Linze (LZ) and Jiuquan (JQ) in northwestern China. Further, we extracted the corresponding MODIS Normalized Difference Vegetation Index (NDVI, a proxy for ANPP) datasets at 250 m spatial resolution. We then evaluated different desert ecosystems responses using statistical analysis, and a threshold-delay model (TDM). TDM is an integrative framework for analysis of plant growth, precipitation thresholds, and plant functional type strategies that capture the nonlinear nature of plant responses to rainfall pulses. Our results showed that: (1) the growing season NDVIINT (INT stands for time-integrated) was largely correlated with the warm season (spring/summer) at our mildly-arid desert ecosystem (SD). The arid ecosystem (LZ) exhibited a different response, and the growing season NDVIINT depended highly on the previous year's fall/winter precipitation and ANPP. At the extremely arid site (JQ), the variability of growing season NDVIINT was equally correlated with the cool- and warm-season precipitation; (2) some parameters of threshold-delay differed among the three sites: while the response of NDVI to rainfall pulses began at about 5 mm for all the sites, the maximum thresholds in SD, LZ, and JQ were about 55, 35 and 30 mm respectively, increasing with an increase in mean annual precipitation. By and large, more previous year's fall/winter precipitation, and large rainfall events, significantly enhanced the growth of desert vegetation, and desert ecosystems should be much more adaptive under likely future scenarios of increasing fall/winter precipitation and large rainfall events. These results highlight the inherent complexity in predicting how desert ecosystems will respond to future fluctuations in precipitation.

Review of progress in soil inorganic carbon research

NASA Astrophysics Data System (ADS)

Bai, S. G.; Jiao, Y.; Yang, W. Z.; Gu, P.; Yang, J.; Liu, L. J.

2017-12-01

Soil inorganic carbon is one of the main carbon banks in the near-surface environment, and is the main form of soil carbon library in arid and semi-arid regions, which plays an important role in the global carbon cycle. This paper mainly focuses on the inorganic dynamic process of soil inorganic carbon in soil environment in arid and semi-arid regions, and summarized the composition and source of soil inorganic carbon, influence factors and soil carbon sequestration.

Biocrust-forming mosses mitigate the impact of aridity on soil microbial communities in drylands: observational evidence from three continents.

PubMed

Delgado-Baquerizo, Manuel; Maestre, Fernando T; Eldridge, David J; Bowker, Matthew A; Jeffries, Thomas C; Singh, Brajesh K

2018-04-02

Recent research indicates that increased aridity linked to climate change will reduce the diversity of soil microbial communities and shift their community composition in drylands, Earth's largest biome. However, we lack both a theoretical framework and solid empirical evidence of how important biotic components from drylands, such as biocrust-forming mosses, will regulate the responses of microbial communities to expected increases in aridity with climate change. Here we report results from a cross-continental (North America, Europe and Australia) survey of 39 locations from arid to humid ecosystems, where we evaluated how biocrust-forming mosses regulate the relationship between aridity and the community composition and diversity of soil bacteria and fungi in dryland ecosystems. Increasing aridity was negatively related to the richness of fungi, and either positively or negatively related to the relative abundance of selected microbial phyla, when biocrust-forming mosses were absent. Conversely, we found an overall lack of relationship between aridity and the relative abundance and richness of microbial communities under biocrust-forming mosses. Our results suggest that biocrust-forming mosses mitigate the impact of aridity on the community composition of globally distributed microbial taxa, and the diversity of fungi. They emphasize the importance of maintaining biocrusts as a sanctuary for soil microbes in drylands. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

Consistency between Sweat Rate and Wet Bulb Globe Temperature for the Assessment of Heat Stress of People Working Outdoor in Arid and Semi-arid Regions.

PubMed

Heidari, Hamidreza; Golbabaei, Farideh; Shamsipour, Aliakbar; Rahimi Forushani, Abbas; Gaeini, Abbasali

2018-01-01

Heat stress is common among workers in arid and semi-arid areas. In order to take every preventive measure to protect exposed workers against heat-related disorders, it is crucial to choose an appropriate index that accurately relates environmental parameters to physiological responses. To investigate the consistency between 2 heat stress and strain indices, ie , sweat rate and wet bulb globe temperature (WBGT), for the assessment of heat stress of people working outdoor in arid and semi-arid regions in Iran. During spring and summer, 136 randomly selected outdoor workers were enrolled in this study. Using a defined protocol, the sweat rate of these workers was measured 3 times a day. Simultaneously, the environmental parameters including WBGT index were recorded for each working station. The level of agreement between sweat rate and WBGT was poor ( κ <0.2). Based on sweat rate, no case exceeding the reference value was observed during the study. WBGT overestimated the heat stress in outdoor workers compared to sweat rate. It seems that the sweat rate standards may need some modifications related to real condition of work in arid and semi-arid regions in Iran. Moreover, it seems that judging workers solely based on monitoring their sweat rate in such regions, can probably result in underestimation of heat stress.

DOE Office of Scientific and Technical Information (OSTI.GOV)

McLellan, G.W.

This test plan describes the field demonstration of the sonic drilling system being conducted as a coordinated effort between the VOC-Arid ID (Integrated Demonstration) and the 200 West Area Carbon Tetrachloride ERA (Expedited Response Action) programs at Hanford. The purpose of this test is to evaluate the Water Development Corporation`s drilling system, modify components as necessary and determine compatible drilling applications for the sonic drilling method for use at facilities in the DOE complex. The sonic demonstration is being conducted as the first field test under the Cooperative Research and Development Agreement (CRADA) which involves the US Department of Energy,more » Pacific Northwest Laboratory, Westinghouse Hanford Company and Water Development Corporation. The sonic drilling system will be used to drill a 45 degree vadose zone well, two vertical wells at the VOC-Arid ID site, and several test holes at the Drilling Technology Test Site north of the 200 Area fire station. Testing at other locations will depend on the performance of the drilling method. Performance of this technology will be compared to the baseline drilling method (cable-tool).« less

Soil moisture dynamics modeling considering multi-layer root zone.

PubMed

Kumar, R; Shankar, V; Jat, M K

2013-01-01

The moisture uptake by plant from soil is a key process for plant growth and movement of water in the soil-plant system. A non-linear root water uptake (RWU) model was developed for a multi-layer crop root zone. The model comprised two parts: (1) model formulation and (2) moisture flow prediction. The developed model was tested for its efficiency in predicting moisture depletion in a non-uniform root zone. A field experiment on wheat (Triticum aestivum) was conducted in the sub-temperate sub-humid agro-climate of Solan, Himachal Pradesh, India. Model-predicted soil moisture parameters, i.e., moisture status at various depths, moisture depletion and soil moisture profile in the root zone, are in good agreement with experiment results. The results of simulation emphasize the utility of the RWU model across different agro-climatic regions. The model can be used for sound irrigation management especially in water-scarce humid, temperate, arid and semi-arid regions and can also be integrated with a water transport equation to predict the solute uptake by plant biomass.

Hydrological Connectivity and Science and Policy Integration Issues for Aquatic Resource Jurisdictional Determinations in a Semi-Arid Region of the Western U.S

NASA Astrophysics Data System (ADS)

Caruso, B. S.

2012-12-01

Rivers and streams are becoming increasingly stressed and degraded, and wetlands lost, due to human development and associated management policies and actions that are generally ineffective for aquatic resources protection and restoration. In the semi-arid western U.S., these issues are more severe due to the limited quantity of water and aquatic resources, the magnified role of their ecological services in drier landscapes, and increasing impacts from urbanization and energy development. However, a significant disconnect between policy and science exists that leads to continued degradation of surface waters. Supreme Court decisions and joint Federal agency guidance for determining jurisdiction as 'waters of the US' that can be protected under Clean Water Act Section 404 (permitting discharge of dredged and fill materials into wetlands and other waters) are good examples of this disconnect. The hydrological and ecological connectivity of intermittent and ephemeral streams and wetlands with downstream navigable waters is a critical issue that must be evaluated to determine jurisdiction, but this can be a complex endeavour in semi-arid regions. The hydrological connectivity and key science and policy integration issues for stream and wetland jurisdictional determinations (JDs) were evaluated for a semi-arid region of the western U.S. (Environmental Protection Agency [EPA] Region 8), including much of the Rocky Mountains, Great Plains and Colorado Plateau. The key scientific approaches recommended in the agency guidance were analyzed in detail. An evaluation was performed of a sample of JDs reviewed by EPA Region 8 and their outcomes in terms of aquatic resources that were considered non-jurisdictional. An analysis of stream types and characteristics across the region using available digital spatial analysis tools was performed. A subset of finalized JDs issued by COE was reviewed to analyze the scientific information used to evaluate connectivity to downstream waters and to develop the JDs. During 2007-2008, >1,200 JDs were evaluated by EPA Region 8 resulting in 793 wetlands considered non-jurisdictional due to isolation. Significant nexus evaluation was required for 441 waters, of which 49 wetlands, 66 streams and 14 other water bodies were considered non-jurisdictional. Intermittent streams that could non-jurisdictional due to isolation or inadequate hydrological connection comprise >3/4, and first order streams constitute >1/2 of the total stream length in the region, with the greatest proportion in the Dakotas and plains and desert ecoregions based on medium-resolution NHDPlus data. Many JDs don't contain or apply a range of important information that could be useful or needed. There are significant data gaps and inconsistencies in the types and quantification of scientific information and methods used across JDs. The primary science and policy integration issues include identification and evaluation of navigable waters, hydrologic permanence of perennial and intermittent/ ephemeral streams, stream order, significant nexus, aggregation of waters and effects, human impacts and changes, resource inventories and tools, and analysis of JD outcomes. One key recommendation to help address these issues is the continued development and application of digital spatial analysis tools.

Applications of monsoon research: Opportunities to inform decisionmaking and reduce regional vulnerability

NASA Astrophysics Data System (ADS)

Ray, A. J.; Garfin, G. M.; Wilder, M.; Lenart, M.; Vásquez-León, M.; Comrie, A. C.

2007-05-01

This presentation will describe ongoing efforts to understand interactions between the North American Monsoon and society, in order to develop applications for monsoon research in a highly complex, multicultural and binational region. The North American Monsoon is an annual precipitation regime that begins in early June in Mexico and progresses northward to the southwestern United States. The region includes stakeholders in large urban complexes, productive agricultural areas, and sparsely populated arid and semi-arid ecosystems. The political, cultural, and socioeconomic divisions between the U.S. and Mexico create a broad range of sensitivities to climate variability as well as capacities to use forecasts and other information to cope with climate. We will highlight methodologies to link climate science with society and analyze opportunities for monsoon science to benefit society in four sectors: natural hazards management, agriculture, public health, and water management. We present a synthesized list of stakeholder needs and a calendar of decisions to help scientists link user needs to potential forecasts and products. To ensure usability of forecasts and other research products, we recommend iterative scientist-stakeholder interactions, through integrated assessments. These knowledge- exchange interactions can improve the capacity for stakeholders to use forecasts thoughtfully and inform the development of research, and for the research community to obtain feedback on climate-related products and receive insights to guide research direction. We expect that integrated assessments can capitalize on the opportunities for monsoon science to inform decisionmaking, in the best instances, reduce regional climate vulnerabilities and enhance regional sustainability

Optimal integrated management of groundwater resources and irrigated agriculture in arid coastal regions

NASA Astrophysics Data System (ADS)

Grundmann, J.; Schütze, N.; Heck, V.

2014-09-01

Groundwater systems in arid coastal regions are particularly at risk due to limited potential for groundwater replenishment and increasing water demand, caused by a continuously growing population. For ensuring a sustainable management of those regions, we developed a new simulation-based integrated water management system. The management system unites process modelling with artificial intelligence tools and evolutionary optimisation techniques for managing both water quality and water quantity of a strongly coupled groundwater-agriculture system. Due to the large number of decision variables, a decomposition approach is applied to separate the original large optimisation problem into smaller, independent optimisation problems which finally allow for faster and more reliable solutions. It consists of an analytical inner optimisation loop to achieve a most profitable agricultural production for a given amount of water and an outer simulation-based optimisation loop to find the optimal groundwater abstraction pattern. Thereby, the behaviour of farms is described by crop-water-production functions and the aquifer response, including the seawater interface, is simulated by an artificial neural network. The methodology is applied exemplarily for the south Batinah re-gion/Oman, which is affected by saltwater intrusion into a coastal aquifer system due to excessive groundwater withdrawal for irrigated agriculture. Due to contradicting objectives like profit-oriented agriculture vs aquifer sustainability, a multi-objective optimisation is performed which can provide sustainable solutions for water and agricultural management over long-term periods at farm and regional scales in respect of water resources, environment, and socio-economic development.

A multi-structural and multi-functional integrated fog collection system in cactus

PubMed Central

Ju, Jie; Bai, Hao; Zheng, Yongmei; Zhao, Tianyi; Fang, Ruochen; Jiang, Lei

2012-01-01

Multiple biological structures have demonstrated fog collection abilities, such as beetle backs with bumps and spider silks with periodic spindle-knots and joints. Many Cactaceae species live in arid environments and are extremely drought-tolerant. Here we report that one of the survival systems of the cactus Opuntia microdasys lies in its efficient fog collection system. This unique system is composed of well-distributed clusters of conical spines and trichomes on the cactus stem; each spine contains three integrated parts that have different roles in the fog collection process according to their surface structural features. The gradient of the Laplace pressure, the gradient of the surface-free energy and multi-function integration endow the cactus with an efficient fog collection system. Investigations of the structure–function relationship in this system may help us to design novel materials and devices to collect water from fog with high efficiencies. PMID:23212376

A multi-structural and multi-functional integrated fog collection system in cactus.

PubMed

Ju, Jie; Bai, Hao; Zheng, Yongmei; Zhao, Tianyi; Fang, Ruochen; Jiang, Lei

2012-01-01

Multiple biological structures have demonstrated fog collection abilities, such as beetle backs with bumps and spider silks with periodic spindle-knots and joints. Many Cactaceae species live in arid environments and are extremely drought-tolerant. Here we report that one of the survival systems of the cactus Opuntia microdasys lies in its efficient fog collection system. This unique system is composed of well-distributed clusters of conical spines and trichomes on the cactus stem; each spine contains three integrated parts that have different roles in the fog collection process according to their surface structural features. The gradient of the Laplace pressure, the gradient of the surface-free energy and multi-function integration endow the cactus with an efficient fog collection system. Investigations of the structure-function relationship in this system may help us to design novel materials and devices to collect water from fog with high efficiencies.

Tropical Warm Semi-Arid Regions Expanding Over Temperate Latitudes In The Projected 21st Century

NASA Astrophysics Data System (ADS)

Rajaud, A.; de Noblet, N. I.

2015-12-01

Two billion people today live in drylands, where extreme climatic conditions prevail, and natural resources are limited. Drylands are expected to expand under several scenarios of climatic change. However, relevant adaptation strategies need to account for the aridity level: it conditions the equilibrium tree-cover density, ranging from deserts (hyper-arid) to dense savannas (sub-humid). Here we focus on the evolution of climatically defined warm semi-arid areas, where low-tree density covers can be maintained. We study the global repartition of these regions in the future and the bioclimatic shifts involved. We adopted a bioclimatological approach based on the Köppen climate classification. The warm semi-arid class is characterized by mean annual temperatures over 18°C and a rainfall-limitation criterion. A multi-model ensemble of CMIP5 projections for three representative concentration pathways was selected to analyze future conditions. The classification was first applied to the start, middle and end of the 20th and 21st centuries, in order to localize past and future warm semi-arid regions. Then, time-series for the classification were built to characterize trends and variability in the evolution of those regions. According to the CRU datasets, global expansion of the warm semi-arid area has already started (~+13%), following the global warming trend since the 1900s. This will continue according to all projections, most significantly so outside the tropical belt. Under the "business as usual" scenario, the global warm semi-arid area will increase by 30% and expand 12° poleward in the Northern Hemisphere, according to the multi-model mean. Drying drives the conversion from equatorial sub-humid conditions. Beyond 30° of latitude, cold semi-arid conditions become warm semi-arid through warming, and temperate conditions through combined warming and drying processes. Those various transitions may have drastic but also very distinct ecological and sociological impacts.

Adaptation of metabolism and evaporative water loss along an aridity gradient.

PubMed

Tieleman, B Irene; Williams, Joseph B; Bloomer, Paulette

2003-01-22

Broad-scale comparisons of birds indicate the possibility of adaptive modification of basal metabolic rate (BMR) and total evaporative water loss (TEWL) in species from desert environments, but these might be confounded by phylogeny or phenotypic plasticity. This study relates variation in avian BMR and TEWL to a continuously varying measure of environment, aridity. We test the hypotheses that BMR and TEWL are reduced along an aridity gradient within the lark family (Alaudidae), and investigate the role of phylogenetic inertia. For 12 species of lark, BMR and TEWL decreased along a gradient of increasing aridity, a finding consistent with our proposals. We constructed a phylogeny for 22 species of lark based on sequences of two mitochondrial genes, and investigated whether phylogenetic affinity played a part in the correlation of phenotype and environment. A test for serial independence of the data for mass-corrected TEWL and aridity showed no influence of phylogeny on our findings. However, we did discover a significant phylogenetic effect in mass-corrected data for BMR, a result attributable to common phylogenetic history or to common ecological factors. A test of the relationship between BMR and aridity using phylogenetic independent constrasts was consistent with our previous analysis: BMR decreased with increasing aridity.

ARID1B alterations identify aggressive tumors in neuroblastoma.

PubMed

Lee, Soo Hyun; Kim, Jung-Sun; Zheng, Siyuan; Huse, Jason T; Bae, Joon Seol; Lee, Ji Won; Yoo, Keon Hee; Koo, Hong Hoe; Kyung, Sungkyu; Park, Woong-Yang; Sung, Ki W

2017-07-11

Targeted panel sequencing was performed to determine molecular targets and biomarkers in 72 children with neuroblastoma. Frequent genetic alterations were detected in ALK (16.7%), BRCA1 (13.9%), ATM (12.5%), and PTCH1 (11.1%) in an 83-gene panel. Molecular targets for targeted therapy were identified in 16 of 72 patients (22.2%). Two-thirds of ALK mutations were known to increase sensitivity to ALK inhibitors. Sequence alterations in ARID1B were identified in 5 of 72 patients (6.9%). Four of five ARID1B alterations were detected in tumors of high-risk patients. Two of five patients with ARID1B alterations died of disease progression. Relapse-free survival was lower in patients with ARID1B alterations than in those without (p = 0.01). In analysis confined to high-risk patients, 3-year overall survival was lower in patients with an ARID1B alteration (33.3 ± 27.2%) or MYCN amplification (30.0 ± 23.9%) than in those with neither ARID1B alteration nor MYCN amplification (90.5 ± 6.4%, p = 0.05). These results provide possibilities for targeted therapy and a new biomarker identifying a subgroup of neuroblastoma patients with poor prognosis.

Event-based hydrological modeling for detecting dominant hydrological process and suitable model strategy for semi-arid catchments

NASA Astrophysics Data System (ADS)

Huang, Pengnian; Li, Zhijia; Chen, Ji; Li, Qiaoling; Yao, Cheng

2016-11-01

To simulate the hydrological processes in semi-arid areas properly is still challenging. This study assesses the impact of different modeling strategies on simulating flood processes in semi-arid catchments. Four classic hydrological models, TOPMODEL, XINANJIANG (XAJ), SAC-SMA and TANK, were selected and applied to three semi-arid catchments in North China. Based on analysis and comparison of the simulation results of these classic models, four new flexible models were constructed and used to further investigate the suitability of various modeling strategies for semi-arid environments. Numerical experiments were also designed to examine the performances of the models. The results show that in semi-arid catchments a suitable model needs to include at least one nonlinear component to simulate the main process of surface runoff generation. If there are more than two nonlinear components in the hydrological model, they should be arranged in parallel, rather than in series. In addition, the results show that the parallel nonlinear components should be combined by multiplication rather than addition. Moreover, this study reveals that the key hydrological process over semi-arid catchments is the infiltration excess surface runoff, a non-linear component.

The analysis of aridity in Central Serbia from 1949 to 2015

NASA Astrophysics Data System (ADS)

Radaković, Milica G.; Tošić, Ivana; Bačević, Nikola; Mladjan, Dragan; Gavrilov, Milivoj B.; Marković, Slobodan B.

2017-07-01

In this study, we apply De Martonne and Pinna combinative indices to analyze the aridity in Central Serbia. Our dataset consists of mean monthly surface air temperature (MMT) and mean monthly precipitation (MMP) for 26 meteorological stations during the period 1949-2015. MMT and MMP are used for calculating monthly, seasonal, and annual aridity indices for period of 66 years. According to the De Martonne climate classification, we determine five, three, and four types of climate on the monthly, seasonal, and annual basis, respectively. During the observed period, winter was extremely humid, spring and autumn were humid, and summer was semi-humid. Humid and semi-humid climate with Mediterranean vegetation are identified by the annual Pinna combinative index. We find that there is no change in aridity trend in Central Serbia for the period 1949-2015. Aridity indices are additionally compared with the North Atlantic Oscillation and El-Niño South Oscillation in order to establish a possible connection with the large-scale processes. Results are further compared with several earlier studies of aridity in Serbia. With this study, the analysis of aridity in whole Serbia has become complete.

Aridification of the Indian Subcontinent during the Holocene: Implications for Landscape Evolution, Sedimentation, Carbon Cycle, and Human Civilizations

DTIC Science & Technology

2012-06-01

of flora for both sites. For the Godavari River basin the  13 Cwax record shows a gradual increase in aridity- adapted vegetation from ~4,000 until...1,700 years ago followed by the persistence of aridity- adapted plants to the present. The oxygen isotopic composition of planktonic foraminifera...for a gradual increase in the proportion of aridity- adapted vegetation from ~4,000 until 1,700 years ago followed by the persistence of aridity

Characterization of a new ARID family transcription factor (Brightlike/ARID3C) that co-activates Bright/ARID3A-mediated immunoglobulin gene transcription

PubMed Central

Tidwell, Josephine A.; Schmidt, Christian; Heaton, Phillip; Wilson, Van; Tucker, Philip W.

2011-01-01

Two members, Bright/ARID3A and Bdp/ARID3B, of the ARID (AT-Rich Interaction Domain) transcription family are distinguished by their ability to specifically bind to DNA and to self-associate via a second domain, REKLES. Bright and Bdp positively regulate immunoglobulin heavy chain gene (IgH) transcription by binding to AT-rich motifs within Matrix Associating Regions (MARs) residing within a subset of VH promoters and the Eµ intronic enhancer. In addition, REKLES provides Bright nuclear export function, and a small pool of Bright is directed to plasma membrane sub-domains/lipid rafts where it associates with and modulates signaling of the B cell antigen receptor (BCR). Here, we characterize a third, highly conserved, physically condensed ARID3 locus, Brightlike/ARID3C. Brightlike encodes two alternatively spliced, SUMO-I-modified isoforms that include or exclude (Δ6) the REKLES-encoding exon 6. Brightlike transcripts and proteins are expressed preferentially within B lineage lymphocytes and coordinate with highest Bright expression--in activated follicular B cells. Brightlike, but not BrightlikeΔ6, undergoes nuclear-cytoplasmic shuttling with a fraction localizing within lipid rafts following BCR stimulation. Brightlike, but not BrightlikeΔ6, associates with Bright in solution, at common DNA binding sites in vitro, and is enriched at Bright binding sites in chromatin. Although possessing little transactivation capacity of its own, Brightlike significantly co-activates Bright-dependent IgH transcription with maximal activity mediated by the unsumoylated form. In sum, this report introduces Brightlike as an additional functional member of the family of ARID proteins, which should be considered in regulatory circuits, previously ascribed to be mediated by Bright. PMID:21955986

Kidney function and the role of arginine vasotocin in three agamid lizards from habitats of differing aridity in Western Australia.

PubMed

Ford, S S; Bradshaw, S D

2006-05-15

Western Australian agamid lizards are diverse and inhabit mesic to very arid areas of the state. Although reptilian kidneys are unable to elaborate hyperosmotic urine, we hypothesised that the renal system of lizards inhabiting arid areas would display an enhanced ability to conserve water under the control of the antidiuretic peptide hormone, arginine vasotocin (AVT). To examine this, the renal physiological and endocrine responses to osmotic challenge in three closely-related Australian agamid lizards inhabiting arid, semi-arid, and mesic environments were studied. The species studied were Pogona minor (mesic), Ctenophorus salinarum (semi-arid), and Ctenophorus nuchalis (arid). Circulating AVT was assayed and renal variables such as glomerular filtration rate (GFR), urine flow rate (V), and fractional reabsorption of filtrate FRH2O were measured in response to hypernatraemia, water load, and dehydration. Hypernatraemia and dehydration induced antidiuresis in all three species through similar mechanisms involving both glomerular and tubular responses. However, in salt-loaded P. minor the response was largely glomerular in nature, as FRH2O did not increase relative to the hydrated condition. The magnitude of the antidiuretic response was also greater in P. minor, indicating a greater sensitivity to osmotic challenge. Plasma concentrations of AVT were significantly correlated with FRH2O in P. minor (r2=0.38, P=0.025), but with GFR in C. nuchalis (r2=0.16, P=0.041). We found that the control and mechanisms of renal function among these lizards were largely similar, and there was little support for the hypothesis that arid lizards possess physiological adaptations not present in closely-related mesic lizards. Yet, differences remain in their response to hypernatraemia which may reflect the aridity of their different environments, or their varying habits.

Aridity influences the recovery of vegetation and shrubland birds after wildfire

PubMed Central

Puig-Gironès, Roger; Brotons, Lluís

2017-01-01

Wildfires play a determining role in the composition and structure of many plant and animal communities. On the other hand, climate change is considered to be a major driver of current and future fire regime changes. Despite increases in drought in many areas of the world, the effects of aridity on post-fire colonization by animals have been rarely addressed. This study aims to analyse how a regional aridity gradient affects post-fire recovery of vegetation, bird species richness and the numbers of four early to middle-successional warbler species associated with the shrub cover. The database contains bird relative abundance and environmental variables from 3072 censuses in 695 transects located in 70 recently burnt areas (1 to 11 years after wildfire) in Catalonia (Spain), which were sampled between 2006 and 2013. Generalized linear mixed models (GLMMs) showed that plant cover was affected by time since fire, aridity and forest management. However, only the highest vegetation height layer (>100 cm) recovered slower in arid areas after fire. Time since fire positively influenced bird species richness and the relative abundance of the four focal species. The post-fire recovery of Melodious (Hippolais polyglotta) and Subalpine warblers (Sylvia cantillans) was hampered by aridity. Although this was not demonstrated for Dartford (S. undata) and Sardinian warblers (S. melanocephala), their occurrence was low in the driest areas during the first three years after fire. Overall, this study suggests that future increases in aridity can affect plant regeneration after fire and slow down the recovery of animal populations that depend on understorey and shrublands. Given the recently highlighted increases in aridity and fire frequency in Mediterranean-climate regions, improved knowledge on how aridity affects ecological succession is especially necessary. PMID:28355225

Aridity influences the recovery of vegetation and shrubland birds after wildfire.

PubMed

Puig-Gironès, Roger; Brotons, Lluís; Pons, Pere

2017-01-01

Wildfires play a determining role in the composition and structure of many plant and animal communities. On the other hand, climate change is considered to be a major driver of current and future fire regime changes. Despite increases in drought in many areas of the world, the effects of aridity on post-fire colonization by animals have been rarely addressed. This study aims to analyse how a regional aridity gradient affects post-fire recovery of vegetation, bird species richness and the numbers of four early to middle-successional warbler species associated with the shrub cover. The database contains bird relative abundance and environmental variables from 3072 censuses in 695 transects located in 70 recently burnt areas (1 to 11 years after wildfire) in Catalonia (Spain), which were sampled between 2006 and 2013. Generalized linear mixed models (GLMMs) showed that plant cover was affected by time since fire, aridity and forest management. However, only the highest vegetation height layer (>100 cm) recovered slower in arid areas after fire. Time since fire positively influenced bird species richness and the relative abundance of the four focal species. The post-fire recovery of Melodious (Hippolais polyglotta) and Subalpine warblers (Sylvia cantillans) was hampered by aridity. Although this was not demonstrated for Dartford (S. undata) and Sardinian warblers (S. melanocephala), their occurrence was low in the driest areas during the first three years after fire. Overall, this study suggests that future increases in aridity can affect plant regeneration after fire and slow down the recovery of animal populations that depend on understorey and shrublands. Given the recently highlighted increases in aridity and fire frequency in Mediterranean-climate regions, improved knowledge on how aridity affects ecological succession is especially necessary.

Multiple genomic signatures of selection in goats and sheep indigenous to a hot arid environment

PubMed Central

Kim, E-S; Elbeltagy, A R; Aboul-Naga, A M; Rischkowsky, B; Sayre, B; Mwacharo, J M; Rothschild, M F

2016-01-01

Goats and sheep are versatile domesticates that have been integrated into diverse environments and production systems. Natural and artificial selection have shaped the variation in the two species, but natural selection has played the major role among indigenous flocks. To investigate signals of natural selection, we analyzed genotype data generated using the caprine and ovine 50K SNP BeadChips from Barki goats and sheep that are indigenous to a hot arid environment in Egypt's Coastal Zone of the Western Desert. We identify several candidate regions under selection that spanned 119 genes. A majority of the genes were involved in multiple signaling and signal transduction pathways in a wide variety of cellular and biochemical processes. In particular, selection signatures spanning several genes that directly or indirectly influenced traits for adaptation to hot arid environments, such as thermo-tolerance (melanogenesis) (FGF2, GNAI3, PLCB1), body size and development (BMP2, BMP4, GJA3, GJB2), energy and digestive metabolism (MYH, TRHDE, ALDH1A3), and nervous and autoimmune response (GRIA1, IL2, IL7, IL21, IL1R1) were identified. We also identified eight common candidate genes under selection in the two species and a shared selection signature that spanned a conserved syntenic segment to bovine chromosome 12 on caprine and ovine chromosomes 12 and 10, respectively, providing, most likely, the evidence for selection in a common environment in two different but closely related species. Our study highlights the importance of indigenous livestock as model organisms for investigating selection sweeps and genome-wide association mapping. PMID:26555032

Thirteen thousand years of southeastern Mediterranean climate variability inferred from an integrative planktic foraminiferal-based approach

NASA Astrophysics Data System (ADS)

Mojtahid, Meryem; Manceau, Rose; Schiebel, Ralf; Hennekam, Rick; de Lange, Gert J.

2015-04-01

Over the past 13 ka, the hydrology for the southeastern Mediterranean was mainly regulated by Nile River runoff, which in turn was controlled by climate forcing. Being affected by orbital forcing, and the position of the Intertropical Convergence Zone (ITCZ), planktic foraminiferal data (assemblages, stable isotopes, and size properties) indicate three major periods. (1) From 13.0 to 11.5 ka, the upper water column was well-mixed, cold, and productive. (2) From 11.5 to 6.4 ka, hydrology and foraminifers were affected by intensified monsoonal circulation. The enhanced size of Globigerinoides ruber is interpreted as a response to environmental stress caused by low-saline waters. (3) After 6.4 ka, the southward retreat of the ITCZ caused a decrease in freshwater discharge and hence a return to ecological equilibrium. A drop in foraminifer diversity from 2.9 to 1.1 ka was related to more arid conditions, and limited supply of nutrients from the Nile River. We suggest a link to a negative North Atlantic Oscillation (NAO) marking the Roman Humid Period in the western Mediterranean, and in anti-phase with the southeastern Mediterranean aridity. Because Nile River runoff exerted major control on surface hydrology, a connection to Indian and Pacific climate systems partially controlling precipitation over the Nile catchment area is hypothesized. From 1.1 to 0.54 ka, high foraminifer diversity indicates humid conditions synchronous to the Medieval Climate Anomaly under a positive NAO state. Over the past 0.54 ka encompassing the Little Ice Age, another arid period is indicated by a drop in foraminifer diversity.

Niche conservatism and phylogenetic clustering in a tribe of arid-adapted marsupial mice, the Sminthopsini.

PubMed

García-Navas, Vicente; Westerman, Michael

2018-05-28

The progressive expansion of the Australian arid zone during the last 20 Ma appears to have spurred the diversification of several families of plants, vertebrates and invertebrates, yet such taxonomic groups appear to show limited niche radiation. Here, we test whether speciation is associated with niche conservatism (constraints on ecological divergence) or niche divergence in a tribe of marsupial mice (Sminthopsini; 23 taxa) that includes the most speciose genus of living dasyurids, the sminthopsins. To that end, we integrated phylogenetic data with ecological niche modelling, to enable us to reconstruct the evolution of climatic suitability within Sminthopsini. Niche overlap among species was low-moderate (but generally higher than expected given environmental background similarity), and the degree of phylogenetic clustering increased with aridity. Climatic niche reconstruction illustrates that there has been little apparent evolution of climatic tolerance within clades. Accordingly, climatic disparity tends to be accumulated among clades, suggesting considerable niche conservatism. Our results also indicate that evolution of climatic tolerances has been heterogeneous across different dimensions of climate (temperature vs. precipitation) and across phylogenetic clusters (Sminthopsis murina group vs. other groups). Although some results point to the existence of shifts in climatic niches during the speciation of sminthopsins, our study provides evidence for substantial phylogenetic niche conservatism in the group. We conclude that niche diversification had a low impact on the speciation of this tribe of small, but highly mobile marsupials. © 2018 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2018 European Society For Evolutionary Biology.

Flash Floods Simulation Using a Physical based hydrological Model at the Eastern Nile Basin: Case studies; Wadi Assiut, Egypt and Wadi Gumara, Lake Tana, Ethiopia.

NASA Astrophysics Data System (ADS)

Saber, M.; Sefelnasr, A.; Yilmaz, K. K.

2015-12-01

Flash flood is a natural hydrological phenomenon which affects many regions of the world. The behavior and effect of this phenomenon is different from one region to the other regions depending on several issues such as climatology and hydrological and topographical conditions at the target regions. Wadi assiut, Egypt as arid environment, and Gumara catchment, Lake Tana, Ethiopia, as humid conditions have been selected for application. The main target of this work is to simulate flash floods at both catchments considering the difference between them on the flash flood behaviors based on the variability of both of them. In order to simulate the flash floods, remote sensing data and a physical-based distributed hydrological model, Hydro-BEAM-WaS (Hydrological River Basin Environmental Assessment Model incorporating Wadi System) have been integrated used in this work. Based on the simulation results of flash floods in these regions, it was found that the time to reach the maximum peak is very short and consequently the warning time is very short as well. It was found that the flash floods starts from zero flow in arid environment, but on the contrary in humid arid, it starts from Base flow which is changeable based on the simulated events. Distribution maps of flash floods showing the vulnerable regions of these selected areas have been developed. Consequently, some mitigation strategies relying on this study have been introduced. The proposed methodology can be applied effectively for flash flood forecasting at different climate regions, however the paucity of observational data.

Vulnerabilities and adaptive capacities of southwest rangeland livestock production to climate change

USDA-ARS?s Scientific Manuscript database

The rangeland livestock industry across the southwestern US (California, Nevada, Arizona, Utah and New Mexico) consists of highly diverse production operations in these arid and semi-arid environments with low primary productivity. The vulnerabilities of this industry with projected increasing arid...

Herbivore-plant interactions and desertification in arid lands

USDA-ARS?s Scientific Manuscript database

Arid lands around the world have experienced or are currently experiencing degradation that is known as desertification. Animal-plant interactions that have an effect on desertification are among the most important function of animals in arid ecosystems. Desertification has been defined as land de...

Spatial analysis of the annual and seasonal aridity trends in Extremadura, southwestern Spain

NASA Astrophysics Data System (ADS)

Moral, Francisco J.; Paniagua, Luis L.; Rebollo, Francisco J.; García-Martín, Abelardo

2017-11-01

The knowledge of drought (or wetness) conditions is necessary not only for a rational use of water resources but also for explaining landscape and ecology characteristics. An increase in aridity in many areas of the world is expected because of climate change (global warming). With the aim of analysing annual and seasonal aridity trends in Extremadura, southwestern Spain, climate data from 81 locations within the 1951-2010 period were used. After computing the De Martonne aridity index at each location, a geographic information system (GIS) and multivariate geostatistics (regression kriging) were utilised to map this index throughout the region. Later, temporal trends were analysed using the Mann-Kendall test, and the Sen's estimator was utilised to estimate the magnitude of trends. Maps of aridity trends were generated by ordinary kriging algorithm, providing a visualisation of detected annual and seasonal tendencies. An increase in aridity, as the De Martonne aridity index decreased, was apparent during the study period, mainly in the more humid locations of the north of the region. An increase of the seasonal De Martonne aridity index was also found, but it was only statistically significant in some locations in spring and summer, with the highest decreasing rate in the north of Extremadura. Change year detection was achieved using cumulative sum graphs, obtaining that firstly the change point occurred in spring, in the mid-1970s, later in the annual period in the late 1970s and finally in summer at the end of the 1980s.

Predicting genotypes environmental range from genome-environment associations.

PubMed

Manel, Stéphanie; Andrello, Marco; Henry, Karine; Verdelet, Daphné; Darracq, Aude; Guerin, Pierre-Edouard; Desprez, Bruno; Devaux, Pierre

2018-05-17

Genome-environment association methods aim to detect genetic markers associated with environmental variables. The detected associations are usually analysed separately to identify the genomic regions involved in local adaptation. However, a recent study suggests that single-locus associations can be combined and used in a predictive way to estimate environmental variables for new individuals on the basis of their genotypes. Here, we introduce an original approach to predict the environmental range (values and upper and lower limits) of species genotypes from the genetic markers significantly associated with those environmental variables in an independent set of individuals. We illustrate this approach to predict aridity in a database constituted of 950 individuals of wild beets and 299 individuals of cultivated beets genotyped at 14,409 random Single Nucleotide Polymorphisms (SNPs). We detected 66 alleles associated with aridity and used them to calculate the fraction (I) of aridity-associated alleles in each individual. The fraction I correctly predicted the values of aridity in an independent validation set of wild individuals and was then used to predict aridity in the 299 cultivated individuals. Wild individuals had higher median values and a wider range of values of aridity than the cultivated individuals, suggesting that wild individuals have higher ability to resist to stress-aridity conditions and could be used to improve the resistance of cultivated varieties to aridity. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Increased anthropogenic disturbance and aridity reduce phylogenetic and functional diversity of ant communities in Caatinga dry forest.

PubMed

Arnan, Xavier; Arcoverde, Gabriela B; Pie, Marcio R; Ribeiro-Neto, José D; Leal, Inara R

2018-08-01

Anthropogenic disturbance and climate change are major threats to biodiversity. The Brazilian Caatinga is the world's largest and most diverse type of seasonally dry tropical forest. It is also one of the most threatened, but remains poorly studied. Here, we analyzed the individual and combined effects of anthropogenic disturbance (three types: livestock grazing, wood extraction, and miscellaneous use of forest resources) and increasing aridity on taxonomic, phylogenetic and functional ant diversity in the Caatinga. We found no aridity and disturbance effects on taxonomic diversity. In spite of this, functional diversity, and to a lesser extent phylogenetic diversity, decreased with increased levels of disturbance and aridity. These effects depended on disturbance type: livestock grazing and miscellaneous resource use, but not wood extraction, deterministically filtered both components of diversity. Interestingly, disturbance and aridity interacted to shape biodiversity responses. While aridity sometimes intensified the negative effects of disturbance, the greatest declines in biodiversity were in the wettest areas. Our results imply that anthropogenic disturbance and aridity interact in complex ways to endanger biodiversity in seasonally dry tropical forests. Given global climate change, neotropical semi-arid areas are habitats of concern, and our findings suggest Caatinga conservation policies must prioritize protection of the wettest areas, where biodiversity loss stands to be the greatest. Given the major ecological relevance of ants, declines in both ant phylogenetic and functional diversity might have downstream effects on ecosystem processes, insect populations, and plant populations. Copyright © 2018 Elsevier B.V. All rights reserved.

Emerging crops in the USDA arid lands germplasm collection

USDA-ARS?s Scientific Manuscript database

The USDA National Plant Germplasm System maintains collections of several emerging crops for arid lands at the National Arid Land Plant Genetic Resources Unit in Parlier, CA (NALPGRU). The guayule, jojoba, and prickly pear collections are most active in terms of current research and crop development...

Precipitation and nitrogen interactions in arid ecosystems

USDA-ARS?s Scientific Manuscript database

Arid and semi-arid ecosystems are among the most impoverished terrestrial systems in terms of water and nitrogen (N) availability. Productivity (NPP) is generally low, soil N pools are small and N loss through percolation is assumed to be negligible. Increased water availability can stimulate both N...

Post-Eocene climate change across continental Australia and the diversification of Australasian spiny trapdoor spiders (Idiopidae: Arbanitinae).

PubMed

Rix, Michael G; Cooper, Steven J B; Meusemann, Karen; Klopfstein, Seraina; Harrison, Sophie E; Harvey, Mark S; Austin, Andrew D

2017-04-01

The formation and spread of the Australian arid zone during the Neogene was a profoundly transformative event in the biogeographic history of Australia, resulting in extinction or range contraction in lineages adapted to mesic habitats, as well as diversification and range expansion in arid-adapted taxa (most of which evolved from mesic ancestors). However, the geographic origins of the arid zone biota are still relatively poorly understood, especially among highly diverse invertebrate lineages, many of which are themselves poorly documented at the species level. Spiny trapdoor spiders (Idiopidae: Arbanitinae) are one such lineage, having mesic 'on-the-continent' Gondwanan origins, while also having experienced major arid zone radiations in select clades. In this study, we present new orthologous nuclear markers for the phylogenetic inference of mygalomorph spiders, and use them to infer the phylogeny of Australasian Idiopidae with a 12-gene parallel tagged amplicon next-generation sequencing approach. We use these data to test the mode and timing of diversification of arid-adapted idiopid lineages across mainland Australia, and employ a continent-wide sampling of the fauna's phylogenetic and geographic diversity to facilitate ancestral area inference. We further explore the evolution of phenotypic and behavioural characters associated with both arid and mesic environments, and test an 'out of south-western Australia' hypothesis for the origin of arid zone clades. Three lineages of Idiopidae are shown to have diversified in the arid zone during the Miocene, one (genus Euoplos) exclusively in Western Australia. Arid zone Blakistonia likely had their origins in South Australia, whereas in the most widespread genus Aganippe, a more complex scenario is evident, with likely range expansion from southern Western Australia to southern South Australia, from where the bulk of the arid zone fauna then originated. In Aganippe, remarkable adaptations to phragmotic burrow-plugging in transitional arid zone taxa have evolved twice independently in Western Australia, while in Misgolas and Cataxia, burrow door-building behaviours have likely been independently lost at least three times in the eastern Australian mesic zone. We also show that the presence of idiopids in New Zealand (Cantuaria) is likely to be the result of recent dispersal from Australia, rather than ancient continental vicariance. By providing the first comprehensive, continental synopsis of arid zone biogeography in an Australian arachnid lineage, we show that the diversification of arbanitine Idiopidae was intimately associated with climate shifts during the Neogene, resulting in multiple Mio-Pliocene radiations. Copyright © 2017 Elsevier Inc. All rights reserved.

Problems and Prospects of SWAT Model Application on an Arid/Semi-arid Watershed in Arizona

EPA Science Inventory

Hydrological characteristics in the semi-arid southwest create unique challenges to watershed modelers. Streamflow in these regions is largely dependent on seasonal, short term, and high intensity rainfall events. The objectives of this study are: 1) to analyze the unique hydrolo...

International Arid Lands Consortium: A synopsis of accomplishments

Treesearch

Peter F. Ffolliott; Jeffrey O. Dawson; James T. Fisher; Itshack Moshe; Timothy E. Fulbright; W. Carter Johnson; Paul Verburg; Muhammad Shatanawi; Jim P. M. Chamie

2003-01-01

The International Arid Lands Consortium (IALC) was established in 1990 to promote research, education, and training activities related to the development, management, and reclamation of arid and semiarid lands in the Southwestern United States, the Middle East, and elsewhere in the world. The Consortium supports the ecological sustainability and environmentally sound...

Problems and Prospects of Swat Model Application on an Arid/Semi-Arid Watershed in Arizona

EPA Science Inventory

Hydrological characteristics in the semi-arid southwest create unique challenges to watershed modellers. Streamflow in these regions is largely dependent on seasonal, short term, and high intensity rainfall events. The objectives of this study are: 1) to analyze the unique hydrol...

Rapid warming accelerates tree growth decline in semi-arid forests of Inner Asia.

PubMed

Liu, Hongyan; Park Williams, A; Allen, Craig D; Guo, Dali; Wu, Xiuchen; Anenkhonov, Oleg A; Liang, Eryuan; Sandanov, Denis V; Yin, Yi; Qi, Zhaohuan; Badmaeva, Natalya K

2013-08-01

Forests around the world are subject to risk of high rates of tree growth decline and increased tree mortality from combinations of climate warming and drought, notably in semi-arid settings. Here, we assess how climate warming has affected tree growth in one of the world's most extensive zones of semi-arid forests, in Inner Asia, a region where lack of data limits our understanding of how climate change may impact forests. We show that pervasive tree growth declines since 1994 in Inner Asia have been confined to semi-arid forests, where growing season water stress has been rising due to warming-induced increases in atmospheric moisture demand. A causal link between increasing drought and declining growth at semi-arid sites is corroborated by correlation analyses comparing annual climate data to records of tree-ring widths. These ring-width records tend to be substantially more sensitive to drought variability at semi-arid sites than at semi-humid sites. Fire occurrence and insect/pathogen attacks have increased in tandem with the most recent (2007-2009) documented episode of tree mortality. If warming in Inner Asia continues, further increases in forest stress and tree mortality could be expected, potentially driving the eventual regional loss of current semi-arid forests. © 2013 John Wiley & Sons Ltd.

Adaptation of metabolism and evaporative water loss along an aridity gradient.

PubMed Central

Tieleman, B Irene; Williams, Joseph B; Bloomer, Paulette

2003-01-01

Broad-scale comparisons of birds indicate the possibility of adaptive modification of basal metabolic rate (BMR) and total evaporative water loss (TEWL) in species from desert environments, but these might be confounded by phylogeny or phenotypic plasticity. This study relates variation in avian BMR and TEWL to a continuously varying measure of environment, aridity. We test the hypotheses that BMR and TEWL are reduced along an aridity gradient within the lark family (Alaudidae), and investigate the role of phylogenetic inertia. For 12 species of lark, BMR and TEWL decreased along a gradient of increasing aridity, a finding consistent with our proposals. We constructed a phylogeny for 22 species of lark based on sequences of two mitochondrial genes, and investigated whether phylogenetic affinity played a part in the correlation of phenotype and environment. A test for serial independence of the data for mass-corrected TEWL and aridity showed no influence of phylogeny on our findings. However, we did discover a significant phylogenetic effect in mass-corrected data for BMR, a result attributable to common phylogenetic history or to common ecological factors. A test of the relationship between BMR and aridity using phylogenetic independent constrasts was consistent with our previous analysis: BMR decreased with increasing aridity. PMID:12590762

Hydrological Response of Semi-arid Degraded Catchments in Tigray, Northern Ethiopia

NASA Astrophysics Data System (ADS)

Teka, Daniel; Van Wesemael, Bas; Vanacker, Veerle; Hallet, Vincent

2013-04-01

To address water scarcity in the arid and semi-arid part of developing countries, accurate estimation of surface runoff is an essential task. In semi-arid catchments runoff data are scarce and therefore runoff estimation using hydrological models becomes an alternative. This research was initiated in order to characterize runoff response of semi-arid catchments in Tigray, North Ethiopia to evaluate SCS-CN for various catchments. Ten sub-catchments were selected in different river basins and rainfall and runoff were measured with automatic hydro-monitoring equipments for 2-3 years. The Curve Number was estimated for each Hydrological Response Unit (HRU) in the sub-catchments and runoff was modeled using the SCS-CN method at λ = 0.05 and λ = 0.20. The result showed a significant difference between the two abstraction ratios (P =0.05, df = 1, n= 132) and reasonable good result was obtained for predicted runoff at λ = 0.05 (NSE = -0.69; PBIAS = 18.1%). When using the CN values from literature runoff was overestimated compared to the measured value (e= -11.53). This research showed the importance of using measured runoff data to characterize semi-arid catchments and accurately estimate the scarce water resource. Key words: Hydrological response, rainfall-runoff, degraded environments, semi-arid, Ethiopia, Tigray

Arid1b haploinsufficient mice reveal neuropsychiatric phenotypes and reversible causes of growth impairment

PubMed Central

Celen, Cemre; Chuang, Jen-Chieh; Luo, Xin; Nijem, Nadine; Walker, Angela K; Chen, Fei; Zhang, Shuyuan; Chung, Andrew S; Nguyen, Liem H; Nassour, Ibrahim; Budhipramono, Albert; Sun, Xuxu; Bok, Levinus A; McEntagart, Meriel; Gevers, Evelien F; Birnbaum, Shari G; Eisch, Amelia J; Powell, Craig M; Ge, Woo-Ping; Santen, Gijs WE; Chahrour, Maria; Zhu, Hao

2017-01-01

Sequencing studies have implicated haploinsufficiency of ARID1B, a SWI/SNF chromatin-remodeling subunit, in short stature (Yu et al., 2015), autism spectrum disorder (O'Roak et al., 2012), intellectual disability (Deciphering Developmental Disorders Study, 2015), and corpus callosum agenesis (Halgren et al., 2012). In addition, ARID1B is the most common cause of Coffin-Siris syndrome, a developmental delay syndrome characterized by some of the above abnormalities (Santen et al., 2012; Tsurusaki et al., 2012; Wieczorek et al., 2013). We generated Arid1b heterozygous mice, which showed social behavior impairment, altered vocalization, anxiety-like behavior, neuroanatomical abnormalities, and growth impairment. In the brain, Arid1b haploinsufficiency resulted in changes in the expression of SWI/SNF-regulated genes implicated in neuropsychiatric disorders. A focus on reversible mechanisms identified Insulin-like growth factor (IGF1) deficiency with inadequate compensation by Growth hormone-releasing hormone (GHRH) and Growth hormone (GH), underappreciated findings in ARID1B patients. Therapeutically, GH supplementation was able to correct growth retardation and muscle weakness. This model functionally validates the involvement of ARID1B in human disorders, and allows mechanistic dissection of neurodevelopmental diseases linked to chromatin-remodeling. DOI: http://dx.doi.org/10.7554/eLife.25730.001 PMID:28695822

Apparent over-investment in leaf venation relaxes leaf morphological constraints on photosynthesis in arid habitats

NASA Astrophysics Data System (ADS)

de Boer, Hugo; Drake, Paul; Veneklaas, Erik

2017-04-01

The close relationship between leaf water status and stomatal conductance implies that the hydraulic architecture of leaves poses an important constraint on transpiration, specifically in arid environments with high evaporative demands. However, it remains uncertain how morphological, hydraulic and photosynthetic traits are coordinated to achieve optimal leaf functioning in arid environments. Critical is that leaf veins supply the mesophyll with water that evaporates when stomata are open to allow CO2 uptake for photosynthesis. Theoretical analyses suggest that water is optimally distributed in the mesophyll when the lateral distance between veins (dx) is equal to the distance from these veins to the epidermis (dy), expressed as dx:dy≈1. Although this theory is supported by observations on many derived angiosperms, we hypothesize that plants in arid environments may reduce dx:dy below unity owing to climate-specific functional adaptations of increased leaf thickness and increased vein density. To test our hypothesis we assembled leaf hydraulic, morphological and photosynthetic traits of 68 species from the Eucalyptus and Corymbia genera (termed eucalypts) along an aridity gradient in southwestern Australia. We inferred the potential gas exchange advantage of reducing dx beyond dy using a model that links leaf morphology and hydraulics to photosynthesis. Our observations reveal that eucalypts in arid environments have thick amphistomatous leaves with high vein densities, resulting in dx:dy ratios that range from 1.6 to 0.15 along the aridity gradient. Our model suggests that as leaves become thicker, the effect of reducing dx beyond dy is to offset the reduction in leaf gas exchange that would result from maintaining dx:dy at unity. This apparent over-investment in leaf venation may be explained from the selective pressure of aridity, under which traits associated with long leaf lifespan, high hydraulic and thermal capacitances, and high potential rates of leaf water transport confer a competitive advantage. Our results highlight the need to consider the specific leaf hydraulic architecture of aridity-adapted plants when studying ecohydrological processes in arid ecosystems.

Sustainability of Water Resources in Arid Ecosystems: A View from Hei River Basin, China (Invited)

NASA Astrophysics Data System (ADS)

Zheng, C.; Cheng, G.; Xiao, H.; Ma, R.

2009-12-01

The northwest of China is characterized by an arid climate and fragile ecosystems. With irrigated agriculture, the region is a prolific producer of cotton, wheat, and maize with some of the highest output per acre in the country. The region is also rich in ore deposits, with the reserves of numerous minerals ranked at or near the top in the country. However, the sustainability of irrigated agriculture and economic development in the region is threaten by severe eco-environmental problems resulting from both global changes and human activities, such as desertification, salinization, groundwater depletion, and dust storms. All these problems are a direct consequence of water scarcity. As global warming accelerates and rapid economic growth continues, the water shortage crisis is expected to worsen. To improve the bleak outlook for the health of ecosystem and environment in northwest China, the Chinese government has invested heavily in ecosystem restoration and watershed management in recent years. However, the effectiveness of such measures and actions depends on scientific understanding of the complex interplays among ecological, hydrological and socioeconomic factors. This presentation is intended to provide an overview of a major new research initiative supported by the National Natural Science Foundation of China to study the integration of ecological principles, hydrological processes and socioeconomic considerations toward more sustainable exploitation of surface water and groundwater resources in the Hei River Basin in northwest China. The Hei River Basin is an inland watershed located at the center of the arid region in East Asia, stretching from Qilianshan Mountains in the south to the desert in the north bordering China’s Inner Mongolia Autonomous Region and Mongolia. The total area of Hei River Basin is approximately 130,000 km2. The research initiative builds on existing research infrastructure and ecohydrological data and seeks to reveal complex interactions and feedbacks between ecosystem functioning and water resources in an arid inland watershed. The findings will provide scientific basis for sustainable water resource management that maximizes the economic benefits without irreparably damaging the ecosystem.

An integrative approach to characterize hydrological processes and water quality in a semi-arid watershed in Northeastern Brazil

NASA Astrophysics Data System (ADS)

Franklin, M. R.; Fernandes, N.; Veiga, L. H. S.; Melo, L. R.; Santos, A. C. S.; Araujo, V. P.

2014-12-01

Arid and semi-arid regions face serious challenges in the management of scarce water resources. This situation tends to become worse with the increasing population growth rates and consequently increasing water demand. Groundwater is the most important water resource in these areas and, therefore, the sustainability of its use depends on the effectiveness in which it is managed, both in terms of quantity and quality. The Caetité Experimental Basin (CEB), located in a semi-arid region of Northeastern Brazil, faces not only the challenges associated with water scarcity, but also changes in landscape and potential contamination processes due to mining activity. The only active uranium production center in Brazil (URA) is located in this watershed and the sustainability of mining and milling operations as well as the survival of the local community are highly dependent on the availability of groundwater resources. Hydrogeological studies in this area are scarce, and the potential contamination and overexploitation of groundwater can not be ruled out. Therefore, a national project was launched in order to improve the understanding and quantification of the interaction between the hydrogeological system and human health. The methodological approach involved hydrological and geochemical monitoring and characterization of the CEB, use of isotopic techniques, groundwater modeling, water quality diagnosis and human health risk assessment due to water ingestion. The results suggested that the groundwater in the CEB are not totally connected, with evidence of a mixture of recent and old waters. The Na-Ca-HCO3-Cl is the dominant water type (50%) followed by Ca-Na-HCO3-Cl water type (17%). The relevant non-radioactive contaminants are Mn, F, NO3 and Ba, mostly from natural origin, with the exception of NO3 that could be associated with the livestock activities. The estimated effective doses due to groundwater ingestion containing radionuclides are below the recommended reference level (1 mSv/year) for drinking water in existing exposure situation and do not represent significant radiological impact.

Spatial differences of aeolian desertification responses to climate in arid Asia

NASA Astrophysics Data System (ADS)

Wang, Xunming; Hua, Ting; Lang, Lili; Ma, Wenyong

2017-01-01

Most areas of arid Asia are covered by aeolian dunes, sand sheets, gravels, and desert steppes, and may jeopardize nearly 350 million people if climate change increases aeolian desertification. Although the aeolian desertification is mainly triggered by climate changes are extensively acknowledged, the responses of aeolian desertification to various climate scenarios are poorly understood. Based on the tight combinations of dune activity index (DAI) trends and of aeolian desertification, here the spatial differences of aeolian desertification responses on various climate scenarios were reported. The analyzed results show that the variations in temperature, precipitation and wind regime have no significant contributions on aeolian desertification in the extremely arid Asia. From the early to blooming periods of vegetation growth, although temperature rise may benefit vegetation growths in some high latitudes and altitudes, the temperature rise may increase aeolian desertification in most arid Asia regions such as Mongolia, West and Central Asia. In arid Asia, although precipitation increases may benefit the rehabilitation, decreases in precipitation is not the key role on aeolian desertification occurrences in extremely arid regions. From the early to blooming periods of vegetation growths, spatial trends of the sensitivity of aeolian desertification to wind regime varied. Generally, at the regional scales there are relative high sensitivities for aeolian desertification to climate changes in the eastern and western regions of arid Asia, and the climate changes may not play important roles on aeolian desertification occurrence in the central regions. The spatial differences of aeolian desertification responses to climate changes indicate various strategies for aeolian desertification combating are needed in different regions of arid Asia.

Whither the 100th Meridian: The once and future physical geography of America's arid-humid divide

NASA Astrophysics Data System (ADS)

Ting, M.; Lis, N.; Seager, R.; Feldman, J. R.

2016-12-01

The idea that the 100th Meridian is a dividing line between the arid west and humid east was first advanced by John Wesley Powell in 1890, and the 100th Meridian has remained as an informal division in aridity to the present day. Whether there is a scientifically sound, climatological and hydrological origin of this division is analyzed, and if so, whether climate change will cause the "Hundredth Meridian" to shift in the future. The potential evapotranspiration (PET) is first computed using a suite of three NLDAS-2 land surface models and the Penman-Monteith Equation, and the aridity index (AI), defined as precipitation divided by PET, is used as the aridity metric. There is a sharp gradient in aridity along and just east of the 100th Meridian, verifying Powell's observations. We further determined that this arid-humid boundary is primarily caused by strong spatial gradients in precipitation and humidity, which in turn are caused by the seasonal cycle in wind direction and moisture transport. Using CMIP5 climate model data, the future was projected in 20-year increments from the present through 2100. Models project that the arid-humid boundary will shift eastward by approximately 2 to 3 degrees by the end of the 21st Century, the gradient will weaken, and that the entire continental US will experience at least some degree of aridification. The relative contributions of precipitation, temperature, specific humidity and circulation change to the eastward shift of the "100th meridian" will be discussed.

Global and continental changes of arid areas using the FAO Aridity Index over the periods 1951-1980 and 1981-2010

NASA Astrophysics Data System (ADS)

Spinoni, Jonathan; Micale, Fabio; Carrao, Hugo; Naumann, Gustavo; Barbosa, Paulo; Vogt, Jürgen

2013-04-01

An increase in arid areas and progressing land degradation are two of the main consequences of global climate change. In the 2nd edition of the World Atlas of Desertification (WAD), published by the United Nation Environment Program (UNEP) in 1997, a global aridity map was presented. This map was based on the Food and Agriculture Organization (FAO) Aridity Index (AI) that takes into account the annual ratio between precipitation (RR) and Potential Evapo-Transpiration (PET). According to the long-term mean value of this ratio, climate is therefore classified in hyper-arid (<0.05), arid (0.05-0.2), semi-arid (0.2-0.5), dry sub-humid (0.5-0.65), and humid (>0.65); a special case are cold climates, which occur if the mean annual PET is below 400 mm. In the framework of the 3rd edition of the WAD, we computed new global aridity maps to improve and update the old version that was based on a single dataset (CRU dataset, Climate Research Unit of University of East Anglia) related to the 1951-80 period only. We computed the AI on two different time intervals (1951-80 and 1981-2010) in order to account for shifts in classes between the two periods and we used two different datasets: PET from CRU (version 3.2), and precipitation from the global 0.5˚x0.5˚ gridded monthly precipitation of the Global Precipitation Climatology Center (GPCC) of the Deutscher Wetterdienst (DWD). We used the GPCC Full Data Reanalysis Version 6.0, which showed a high reliability during many quality checks and is based on more stations than the CRU's precipitation counterpart. The results show that the "arid areas" (i.e. AI <0.5) globally increased from 28.4% to 29.6% and in Northern Hemisphere the cold climate areas decreased from 26.6% to 25.4%. Comparing the aridity maps of the two periods, the areas which most remarkably moved to lower AI values ("more arid" conditions) are: Canada, Brazil, the Mediterranean Region, Eastern Europe, almost all of Africa, the Middle East, Eastern China, Borneo, and Australia. At regional or country level, a shift of one class towards a "more arid" class can be found in Alaska (U.S.), Alberta (Canada), Patagonia (Argentina), Pernambuco (Brazil), Western Peru, Spain, the Southern Sahara and North-Eastern Kalahari deserts, Rajasthan and Madhya Pradesh (India), Mongolia, the Yang-Tze Basin (China), and the North-Eastern and South-Western Australian coasts. On the other hand, Central U.S., Paraguay and Northern Argentina, Scandinavia, Northern Australia, and Western China moved to a wetter climate in the last period. Due to the low data availability, we assumed that no changes took place in Antarctica, which is meant to be under a permanent ice cap, excluding the northernmost Graham Land.

International Arid Lands Consortium's contributions to Madrean Archipelago stewardship

Treesearch

Peter F. Ffolliott; Jeffery O. Dawson; Itshack Moshe; Timothy E. Fulbright; E. Carter Johnson; Paul Verburg; Muhannad Shatanawi; Donald F. Caccamise; Jim P. M. Chamie

2005-01-01

The International Arid Lands Consortium (IALC) was established in 1990 to promote research, education, and training activities related to the development, management, and reclamation of arid and semiarid lands worldwide. Building on a decade of experience, the IALC continues to increase the knowledge base for managers by funding research, development, and demonstration...

Arid Green Infrastructure for Water Control and Conservation State of the Science and Research Needs for Arid/Semi-Arid Regions

EPA Science Inventory

Green infrastructure is an approach to managing wet weather flows using systems and practices that mimic natural processes. It is designed to manage stormwater as close to its source as possible and protect the quality of receiving waters. Although most green infrastructure pract...

Patch scale turbulence over dryland and irrigated surfaces in a semi-arid landscape during BEAREX08

USDA-ARS?s Scientific Manuscript database

Quantifying turbulent fluxes of heat and water vapor over heterogeneous surfaces presents unique challenges. For example, in many arid and semi-arid regions, parcels of irrigated cropland are juxtaposed with hot, dry surfaces. Contrasting surface conditions can result in the advection of warm dry ai...

Plant functional traits and phylogenetic relatedness explain variation in associations with root fungal endophytes in an extreme arid environment

USDA-ARS?s Scientific Manuscript database

Since root endophytes may ameliorate drought stress, understanding which plants associate with endophytes is important, especially in arid ecosystems. Here we characterized the root endophytes of 42 plants from an arid region of Argentina. We related colonization by arbuscular mycorrhizal fungi (AMF...

MULTI-SCALE CONTROLS ON AND CONSEQUENCES OF AEOLIAN PROCESSES IN LANDSCAPE CHANGE IN ARID AND SEMI-ARID ENVIRONMENTS

EPA Science Inventory

This paper reviews the controls on aeolian processes and their consequences at plant-interspace, patch-landscape, and regional-global scales. Based on this review, we define the requirements for a cross-scale model of wind erosion in structurally complex arid and semiarid ecosyst...

Modeling Water Redistribution in a Near-Surface Arid Soil

NASA Astrophysics Data System (ADS)

Luo, Y.; Ghezzehei, T. A.; Berli, M.; Dijkema, J.; Koonce, J.

2017-12-01

Desert soils cover about one third of the Earth's land surface and play an important role in the ecology and hydrology of arid environments. Despite their large extend, relatively little is known about their near-surface (top centimeters to meter) water dynamics. Recent studies by Koonce (2016) and Dijkema et al. (2017) shed light on the water dynamics of near-surface arid soil but also revealed some of the challenges to simulate the water redistribution in arid soils. The goal of this study was to improve water redistribution simulations in near-surface arid soils by employing more advanced hydraulic conductivity functions. Expanding on the work by Dijkema et al. (2017), we used a HYDRUS-1D model with different hydraulic conductivity functions to simulate water redistribution within the soil as a function of precipitation, evaporation and drainage. Model calculations were compared with measured data from the SEPHAS weighing lysimeters in Boulder City, NV. Preliminary results indicate that water redistribution simulations of near-surface arid soils can be improved by using hydraulic conductivity functions that can capture capillary, film and vapor flow, like for example the Peter-Durner-Iden (PDI) model.

Evaluating the generalizability of GEP models for estimating reference evapotranspiration in distant humid and arid locations

NASA Astrophysics Data System (ADS)

Kiafar, Hamed; Babazadeh, Hosssien; Marti, Pau; Kisi, Ozgur; Landeras, Gorka; Karimi, Sepideh; Shiri, Jalal

2017-10-01

Evapotranspiration estimation is of crucial importance in arid and hyper-arid regions, which suffer from water shortage, increasing dryness and heat. A modeling study is reported here to cross-station assessment between hyper-arid and humid conditions. The derived equations estimate ET0 values based on temperature-, radiation-, and mass transfer-based configurations. Using data from two meteorological stations in a hyper-arid region of Iran and two meteorological stations in a humid region of Spain, different local and cross-station approaches are applied for developing and validating the derived equations. The comparison of the gene expression programming (GEP)-based-derived equations with corresponding empirical-semi empirical ET0 estimation equations reveals the superiority of new formulas in comparison with the corresponding empirical equations. Therefore, the derived models can be successfully applied in these hyper-arid and humid regions as well as similar climatic contexts especially in data-lack situations. The results also show that when relying on proper input configurations, cross-station might be a promising alternative for locally trained models for the stations with data scarcity.

A hydrologic and archeologic study of climate change in Al Ain, United Arab Emirates

NASA Astrophysics Data System (ADS)

Jorgensen, Donald G.; Yasin al-Tikiriti, Walid

2003-01-01

Aridity trends established for Al Ain, United Arab Emirates, for the past 4500 years correlate with the trends of increased well depths and declining groundwater levels. Depth of wells found at archeologic sites at Hili near Al Ain were correlated to groundwater levels. Trends of declining groundwater levels were related to trends of increasing aridity (climate change). The increasing aridity had a pronounced affect on man's development in Al Ain area as well. For example, nonirrigation farming could not be successfully sustained at the end of the Bronze Age. This thwarted the economic development until the falaj (a water conveyance structure) was introduced in the Iron Age. The aridity trends in Al Ain correspond to contemporaneous aridity trends noted in Mesopotamia and the Dead Sea area, as well as the Middle East, Mediterranean, and northern Africa, in general. Other global climatic changes that are contemporaneous with climate change at Al Ain have been noted. The increased aridity (desertification) trends at Al Ain are contemporaneous with increased atmospheric CO 2 trends as reported by Indermuhle et al. [Nature (398) 121].

Aridity changes in the Tibetan Plateau in a warming climate

DOE PAGES

Gao, Yanhong; Li, Xia; Leung, Lai-Yung R.; ...

2015-03-10

Desertification in the Tibetan Plateau (TP) has drawn increasing attention in the recent decades. It has been postulated as a consequence of climate aridity due to the observed warming. This study quantifies the aridity changes in the TP and attributes the changes to different climatic factors. Using the ratio of P/PET (precipitation to potential evapotranspiration) as an aridity index to indicate changes in dryness and wetness in a given area, P/PET was calculated using observed records at 83 stations in the TP, with PET calculated using the Penman–Monteith (PM) algorithm. Spatial and temporal changes of P/PET in 1979-2011 are analyzed.more » Results show that stations located in the arid and semi-arid northwestern TP are becoming significantly wetter and stations in the semi-humid southeastern TP are becoming drier, though not significantly, in the recent three decades. The aridity change patterns are significantly correlated with precipitation, sunshine duration and diurnal temperature range changes at confidence level of 99.9% from two-tail t-test. Temporal correlations also confirm the significant correlation between aridity changes with the three variables, with precipitation being the most dominant driver of P/PET changes at interannual time scale. PET changes are insignificant but negatively correlated with P/PET in the cold season. In the warm season, however, correlation between PET changes and P/PET changes are significant at confidence level of 99.9% when the cryosphere melts near the surface. Significant correlation between wind speed changes and aridity changes occurs in limited locations and months. Consistency in the climatology pattern and linear trends in surface air temperature and precipitation calculated using station data, gridded data, and nearest grid-to-stations for the TP average and across sub-basins indicate the robustness of the trends despite the large spatial heterogeneity in the TP that challenge climate monitoring.« less

Relationship between seed bank expression, adult longevity and aridity in species of Chaetanthera (Asteraceae) in central Chile.

PubMed

Arroyo, M T K; Chacon, P; Cavieres, L A

2006-09-01

Broad surveys have detected inverse relationships between seed and adult longevity and between seed size and adult longevity. However, low and unpredictable precipitation is also associated with seed bank (SB) expression in semi-arid and arid areas. The relationship between adult longevity, SB formation, seed mass and aridity is examined in annual and perennial herbs of Chaetanthera (Asteraceae) from the Chilean Mediterranean-type climate and winter-rainfall desert areas over a precipitation range of one order of magnitude. Seeds of 18 species and subtaxa (32 populations) were buried in field locations, and exhumed after two successive germination periods. Seeds not germinating in the field were tested in a growth chamber, and remnant intact seed tested for viability. Seed banks were classed as transient or persistent. The effect of life form, species, population and burial time on persistent SB size was assessed with factorial ANOVA. Persistent seed bank size was compared with the Martonne aridity index (shown to be a surrogate for inter-annual variation in precipitation) and seed size using linear regression. ANCOVA assessed the effect of life-form on SB size with aridity as covariate. Three species had a transient SB and 15 a persistent SB. ANOVA revealed a significant effect of life-form on SB size with annuals having larger SB size and greater capacity to form a persistent SB than perennials. Significant inter-population variation in SB size was found in 64% of cases. Seed mass was negatively correlated with persistent SB size. Persistent seed bank size was significantly correlated with the Martonne aridity index in the perennial and annual species, with species from more arid areas having larger persistent SBs. However, when aridity was considered as a covariate, ANCOVA revealed no significant differences between the annual and perennial herbs. Persistent seed bank size in Chaetanthera appears to reflect environmental selection rather than any trade-off with adult longevity.

Modeling Multiple Stresses Placed Upon A Groundwater System In A Semi-Arid Brackish Environment

NASA Astrophysics Data System (ADS)

Toll, M.; Salameh, E.; Sauter, M.

2008-12-01

In semi-arid areas groundwater systems are frequently not sufficiently characterized hydrogeologically and long term data records are generally not available. Long-term time series are necessary, however to design future groundwater abstraction scenarios or to predict the influence of future climate change effects on groundwater resources. To overcome these problems an integrated approach for the provision of a reliable database based on sparse and fuzzy data is proposed. This integrated approach is demonstrated in the lowermost area of the Jordan Valley. The Jordan Valley is part of the Jordan Dead Sea Wadi Araba Rift Valley, which extends from the Red Sea to lake Tiberias and beyond with a major 107 km sinistral strike-slip fault between the Arabian plate to the east and the northeastern part of the African plate to the west. Due to extensional forces a topographic depression was formed. As a result of an arid environment it is filled with evaporites, lacustrine sediments, and clastic fluvial components. A subtropical climate with hot, dry summers and mild humid winters with low amounts of rainfall provide excellent farming conditions. Therefore the Jordan Valley is considered as the food basket of Jordan and is used intensively for agriculture. As a result hundreds of shallow wells were drilled and large amounts of groundwater were abstracted since groundwater is the major source for irrigation. Consequently groundwater quality decreased rapidly since the sixties and signs of overpumping and an increase in soil salinity could clearly be seen. In order to achieve a sustainable state of water resources and to quantify the impact of climate change on water resources a proper assessment of the groundwater resources as well as their quality is a prerequisite. In order to sufficiently describe the complex hydrogeologic flow system an integrated approach, combining geological, geophysical, hydrogeological, historical, and chemical methods was chosen. The aquifer geometry and composition is described with the help of geological, hydochemical, and geophysical methods. As far as the water budget is concerned, the recharge to the considered aquifer is estimated with geological methods and available data sets, while the abstraction from the aquifer is estimated with the help of remote sensing techniques. A historical approach is used to detect the general conditions under which the groundwater system has been in the past. Afterwards this information is implemented into a flow model. On the basis of the findings a numerical 3-D transient model integrating all important features of the hydrogeological system was developed.3 In order to be able to give reliable predictions about the impacts of climate change scenarios on the groundwater system the flow model was tested against stress periods depicted during the historical review of the test area (model period: 1955 - 2008). These stress periods include periods of intense rainfall, of drought, and of anthropogenic impacts, like building of storage dams and of violent conflicts. Recommendations for future sustainable groundwater abstractions are given.

Assessment of vulnerability in karst aquifers using a quantitative integrated numerical model: catchment characterization and high resolution monitoring - Application to semi-arid regions- Lebanon.

NASA Astrophysics Data System (ADS)

Doummar, Joanna; Aoun, Michel; Andari, Fouad

2016-04-01

Karst aquifers are highly heterogeneous and characterized by a duality of recharge (concentrated; fast versus diffuse; slow) and a duality of flow which directly influences groundwater flow and spring responses. Given this heterogeneity in flow and infiltration, karst aquifers do not always obey standard hydraulic laws. Therefore the assessment of their vulnerability reveals to be challenging. Studies have shown that vulnerability of aquifers is highly governed by recharge to groundwater. On the other hand specific parameters appear to play a major role in the spatial and temporal distribution of infiltration on a karst system, thus greatly influencing the discharge rates observed at a karst spring, and consequently the vulnerability of a spring. This heterogeneity can only be depicted using an integrated numerical model to quantify recharge spatially and assess the spatial and temporal vulnerability of a catchment for contamination. In the framework of a three-year PEER NSF/USAID funded project, the vulnerability of a karst catchment in Lebanon is assessed quantitatively using a numerical approach. The aim of the project is also to refine actual evapotranspiration rates and spatial recharge distribution in a semi arid environment. For this purpose, a monitoring network was installed since July 2014 on two different pilot karst catchment (drained by Qachqouch Spring and Assal Spring) to collect high resolution data to be used in an integrated catchment numerical model with MIKE SHE, DHI including climate, unsaturated zone, and saturated zone. Catchment characterization essential for the model included geological mapping and karst features (e.g., dolines) survey as they contribute to fast flow. Tracer experiments were performed under different flow conditions (snow melt and low flow) to delineate the catchment area, reveal groundwater velocities and response to snowmelt events. An assessment of spring response after precipitation events allowed the estimation of the fast infiltration component. A series of laboratory tests were performed to acquire physical values to be used as a benchmark for model parameterization, such as laboratory tests on soils for conductivity at saturation and grain size analysis. Time series used for input or calibration were collected and computed from continuous high resolution monitoring of climatic data, moisture variation in the soil, and discharge at the investigated spring. This similar model approach used on a catchment site in Germany is to be applied and validated on two pilot karst catchments in Lebanon governed by semi-arid climatic conditions. References Doummar J., Sauter M., Geyer T., 2012. Simulation of flow processes in a large scale karst system with an integrated catchment model (Mike She) - Identification of relevant parameters influencing spring discharge. Journal of Hydrology, v. 426-427- p 112-123. Jukić, D., and Denić-Jukić, V., 2009. Groundwater balance estimation in karst by using a conceptual rainfall-runoff model. Journal of Hydrology, v. 373- p 302-315

Spatiotemporal trends in mean temperatures and aridity index over Rwanda

NASA Astrophysics Data System (ADS)

Muhire, I.; Ahmed, F.

2016-01-01

This study aims at quantifying the trends in mean temperatures and aridity index over Rwanda for the period of 1961-1992, based on analysis of climatic data (temperatures, precipitations, and potential evapotranspiration). The analysis of magnitude and significance of trends in temperatures and aridity index show the degree of climate change and mark the level of vulnerability to extreme events (e.g., droughts) in different areas of the country. The study reveals that mean temperatures increased in most parts of the country, with a significant increase observed in the eastern lowlands and in the southwestern parts. The highlands located in the northwest and the Congo-Nile crest showed a nonsignificant increase in mean temperatures. Aridity index increased only in March, April, October, and November, corresponding with the rainy seasons. The remaining months of the year showed a decreasing trend. At an annual resolution, the highlands and the western region showed a rise in aridity index with a decreasing pattern over the eastern lowlands and the central plateau. Generally, the highlands presented a nonsignificant increase in mean temperatures and aridity index especially during the rainy seasons. The eastern lowlands showed a significant increase in mean temperatures and decreasing trends in aridity index. Therefore, these areas are bound to experience more droughts, leading to reduced water and consequent decline in agricultural production. On the other hand, the north highlands and southwest region will continue to be more productive.

Hydrologic Connectivity: a Framework to Understand Threshold Behaviour in Semi-Arid Landscapes.

NASA Astrophysics Data System (ADS)

Saco, Patricia; Rodriguez, Jose; Keesstra, Saskia; Moreno-de las Heras, Mariano; Sandi, Steven; Baartman, Jantiene; Cerdà, Artemi

2017-04-01

Anthropogenic activities and climate change are imposing an unprecedented pressure on arid and semi-arid ecosystems, where shortage of water can trigger shifts in landscapes' structures and function leading to degradation and desertification. Hydrological connectivity is a useful framework for understanding water redistribution and scaling issues associated to runoff and sediment production, since human and/or natural disturbances alter the surface water availability and pathways increasing/decreasing connectivity. In this presentation, we illustrate the use of the connectivity framework for several examples of dryland systems that are analysed at a variety of spatial and temporal scales. In doing so, we draw particular attention to the analysis of co-evolution of system structures and function, and how they drive threshold behaviour leading to desertification and degradation. We first analyse the case of semi-arid rangelands, where feedbacks between decline in vegetation density and landscape erosion reinforces degradation processes driven by changes in connectivity until a threshold is crossed above which the return to a functional system is unlikely. We then focus on semi-arid wetlands, where decreases in water volumes promotes dryland vegetation encroachment that changes drainage conditions and connectivity potentially reinforcing redistribution of flow paths to other wetland areas. The examples presented highlight the need to incorporate a co-evolutionary framework for the analysis of changing connectivity patterns and the emergence of thresholds in arid and semi-arid systems.

Ecohydrology of dry regions of the United States: Precipitation pulses and intraseasonal drought

Treesearch

William K. Lauenroth; John B. Bradford

2009-01-01

Distribution of precipitation event sizes and interval lengths between events are important characteristics of arid and semi-arid climates. Understanding their importance will contribute to our ability to understand ecosystem dynamics in these regions. Our objective for this paper was to present a comprehensive analysis of the daily precipitation regimes of arid and...

A modeling framework for evaluating the drought resilience of a surface water supply system under non-stationarity

DOE PAGES

Zhao, Gang; Gao, Huilin; Kao, Shih -Chieh; ...

2018-05-23

Here, the future resilience of water supply systems is unprecedentedly challenged by non-stationary processes, such as fast population growth and a changing climate. A thorough understanding of how these non-stationarities impact water supply resilience is vital to support sustainable decision making, particularly for large cities in arid and/or semi-arid regions. In this study, a novel modeling framework, which integrates hydrological processes and water management, was established over a representative water limited metropolitan area to evaluate the impacts of water availability and water demand on reservoir storage and water supply reliability. In this framework, climate change induced drought events were selectedmore » from statistically downscaled Coupled Model Intercomparison Project Phase 5 outputs under the Representative Concentration Pathway 8.5 scenario, while future water demand was estimated by the product of projected future population and per capita water use. Compared with the first half of the 21st century (2000–2049), reservoir storage and water supply reliability during the second half century (2050–2099) are projected to reduce by 16.1% and 14.2%, respectively. While both future multi-year droughts and population growth will lower water supply resilience, the uncertainty associated with future climate projection is larger than that associated with urbanization. To reduce the drought risks, a combination of mitigation strategies (e.g., additional conservation, integrating new water sources, and water use redistribution) was found to be the most efficient approach and can significantly improve water supply reliability by as much as 15.9%.« less

A modeling framework for evaluating the drought resilience of a surface water supply system under non-stationarity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Gang; Gao, Huilin; Kao, Shih -Chieh

Here, the future resilience of water supply systems is unprecedentedly challenged by non-stationary processes, such as fast population growth and a changing climate. A thorough understanding of how these non-stationarities impact water supply resilience is vital to support sustainable decision making, particularly for large cities in arid and/or semi-arid regions. In this study, a novel modeling framework, which integrates hydrological processes and water management, was established over a representative water limited metropolitan area to evaluate the impacts of water availability and water demand on reservoir storage and water supply reliability. In this framework, climate change induced drought events were selectedmore » from statistically downscaled Coupled Model Intercomparison Project Phase 5 outputs under the Representative Concentration Pathway 8.5 scenario, while future water demand was estimated by the product of projected future population and per capita water use. Compared with the first half of the 21st century (2000–2049), reservoir storage and water supply reliability during the second half century (2050–2099) are projected to reduce by 16.1% and 14.2%, respectively. While both future multi-year droughts and population growth will lower water supply resilience, the uncertainty associated with future climate projection is larger than that associated with urbanization. To reduce the drought risks, a combination of mitigation strategies (e.g., additional conservation, integrating new water sources, and water use redistribution) was found to be the most efficient approach and can significantly improve water supply reliability by as much as 15.9%.« less

Integration of climatic water deficit and fine-scale physiography in process-based modeling of forest landscape resilience to large-scale tree mortality

NASA Astrophysics Data System (ADS)

Yang, J.; Weisberg, P.; Dilts, T.

2016-12-01

Climate warming can lead to large-scale drought-induced tree mortality events and greatly affect forest landscape resilience. Climatic water deficit (CWD) and its physiographic variations provide a key mechanism in driving landscape dynamics in response to climate change. Although CWD has been successfully applied in niche-based species distribution models, its application in process-based forest landscape models is still scarce. Here we present a framework incorporating fine-scale influence of terrain on ecohydrology in modeling forest landscape dynamics. We integrated CWD with a forest landscape succession and disturbance model (LANDIS-II) to evaluate how tree species distribution might shift in response to different climate-fire scenarios across an elevation-aspect gradient in a semi-arid montane landscape of northeastern Nevada, USA. Our simulations indicated that drought-intolerant tree species such as quaking aspen could experience greatly reduced distributions in the more arid portions of their existing ranges due to water stress limitations under future climate warming scenarios. However, even at the most xeric portions of its range, aspen is likely to persist in certain environmental settings due to unique and often fine-scale combinations of resource availability, species interactions and disturbance regime. The modeling approach presented here allowed identification of these refugia. In addition, this approach helped quantify how the direction and magnitude of fire influences on species distribution would vary across topoclimatic gradients, as well as furthers our understanding on the role of environmental conditions, fire, and inter-specific competition in shaping potential responses of landscape resilience to climate change.

Target genes discovery through copy number alteration analysis in human hepatocellular carcinoma.

PubMed

Gu, De-Leung; Chen, Yen-Hsieh; Shih, Jou-Ho; Lin, Chi-Hung; Jou, Yuh-Shan; Chen, Chian-Feng

2013-12-21

High-throughput short-read sequencing of exomes and whole cancer genomes in multiple human hepatocellular carcinoma (HCC) cohorts confirmed previously identified frequently mutated somatic genes, such as TP53, CTNNB1 and AXIN1, and identified several novel genes with moderate mutation frequencies, including ARID1A, ARID2, MLL, MLL2, MLL3, MLL4, IRF2, ATM, CDKN2A, FGF19, PIK3CA, RPS6KA3, JAK1, KEAP1, NFE2L2, C16orf62, LEPR, RAC2, and IL6ST. Functional classification of these mutated genes suggested that alterations in pathways participating in chromatin remodeling, Wnt/β-catenin signaling, JAK/STAT signaling, and oxidative stress play critical roles in HCC tumorigenesis. Nevertheless, because there are few druggable genes used in HCC therapy, the identification of new therapeutic targets through integrated genomic approaches remains an important task. Because a large amount of HCC genomic data genotyped by high density single nucleotide polymorphism arrays is deposited in the public domain, copy number alteration (CNA) analyses of these arrays is a cost-effective way to reveal target genes through profiling of recurrent and overlapping amplicons, homozygous deletions and potentially unbalanced chromosomal translocations accumulated during HCC progression. Moreover, integration of CNAs with other high-throughput genomic data, such as aberrantly coding transcriptomes and non-coding gene expression in human HCC tissues and rodent HCC models, provides lines of evidence that can be used to facilitate the identification of novel HCC target genes with the potential of improving the survival of HCC patients.

The water economy of South American desert rodents: from integrative to molecular physiological ecology.

PubMed

Bozinovic, Francisco; Gallardo, Pedro

2006-01-01

Rodents from arid and semi-arid habitats live under conditions where the spatial and temporal availability of free water is limited, or scarce, thus forcing these rodents to deal with the problem of water conservation. The response of rodents to unproductive desert environments and water deficits has been intensively investigated in many deserts of the world. However, current understanding of the cellular, systemic and organismal physiology of water economy relies heavily on short-term, laboratory-oriented experiments, which usually focus on responses at isolated levels of biological organization. In addition, studies in small South American mammals are scarce. Indeed xeric habitats have existed in South America for a long time and it is intriguing why present day South American desert rodents do not show the wide array of adaptive traits to desert life observed for rodents on other continents. Several authors have pointed out that South American desert rodents lack physiological and energetic specialization for energy and water conservation, hypothesizing that their success is based more on behavioral and ecological strategies. We review phenotypic flexibility and physiological diversity in water flux rate, urine osmolality, and expression of water channels in South American desert-dwelling rodents. As far as we know, this is the first review of integrative studies at cellular, systemic and organismal levels. Our main conclusion is that South American desert rodents possess structural as well as physiological systems for water conservation, which are as remarkable as those found in "classical" rodents inhabiting other desert areas of the world.

Differential antioxidative responses to dehydration-induced oxidative stress in core set of foxtail millet cultivars [Setaria italica (L.)].

PubMed

Lata, Charu; Jha, Sarita; Dixit, Vivek; Sreenivasulu, Nese; Prasad, Manoj

2011-10-01

Foxtail millet (Setaria italica L.) known as a relatively drought-tolerant crop across the world is grown in arid and semi-arid regions. To the best of our knowledge, no systematic study on drought tolerance screening of foxtail millet germplasm being a drought-tolerant crop has been reported so far. To explore genetic diversity of drought-induced oxidative stress tolerance in foxtail millet, we employed lipid peroxidation measure to assess membrane integrity under stress as biochemical marker to screen 107 cultivars and classified the genotypes as highly tolerant, tolerant, sensitive, and highly sensitive. From this comprehensive screening, four cultivars showing differential response to dehydration tolerance were selected to understand the physiological and biochemical basis of tolerance mechanisms. The dehydration-tolerant cultivars (IC-403579 and Prasad) showed considerably lower levels of lipid peroxidation and electrolyte leakage as compared with dehydration-sensitive cultivars (IC-480117 and Lepakshi), indicating better cell membrane integrity in tolerant cultivars. Correspondingly, tolerant genotypes maintained higher activity of catalase (EC 1.11.1.6), ascorbate peroxidase (APX; EC 1.11.1.11), and glutathione reductase (GR; EC 1.6.4.2) across different time-course period of polyethylene glycol (PEG) treatments in comparison to sensitive ones. The above biochemical results were further validated through quantitative real-time PCR analysis of APX and GR, whose transcripts were substantially induced by PEG treatments in tolerant cultivars. These results suggest that tolerant cultivars possess wider array of antioxidant machinery with efficient ascorbate-glutathione pathway to cope with drought-induced oxidative stress.

Improving the Projections of Vegetation Biogeography by Integrating Climate Envelope Models and Dynamic Global Vegetation Models

NASA Astrophysics Data System (ADS)

Case, M. J.; Kim, J. B.

2015-12-01

Assessing changes in vegetation is increasingly important for conservation planning in the face of climate change. Dynamic global vegetation models (DGVMs) are important tools for assessing such changes. DGVMs have been applied at regional scales to create projections of range expansions and contractions of plant functional types. Many DGVMs use a number of algorithms to determine the biogeography of plant functional types. One such DGVM, MC2, uses a series of decision trees based on bioclimatic thresholds while others, such as LPJ, use constraining emergent properties with a limited set of bioclimatic threshold-based rules. Although both approaches have been used widely, we demonstrate that these biogeography outputs perform poorly at continental scales when compared to existing potential vegetation maps. Specifically, we found that with MC2, the algorithm for determining leaf physiognomy is too simplistic to capture arid and semi-arid vegetation in much of the western U.S., as well as is the algorithm for determining the broadleaf and needleleaf mix in the Southeast. With LPJ, we found that the bioclimatic thresholds used to allow seedling establishment are too broad and fail to capture regional-scale biogeography of the plant functional types. In response, we demonstrate a new approach to determining the biogeography of plant functional types by integrating the climatic thresholds produced for individual tree species by a series of climate envelope models with the biogeography algorithms of MC2 and LPJ. Using this approach, we find that MC2 and LPJ perform considerably better when compared to potential vegetation maps.

Why are there so many coexisting species of lizards in Australian deserts?

PubMed

James, C D; Shine, R

2000-10-01

Because Australian skinks of the genus Ctenotus display very high local species richness in arid-zone spinifex grasslands but not in mesic habitats, these lizards have been used as "model organisms" to ask why ecologically similar taxa coexist under some circumstances but not others. Previous work has involved detailed studies within small areas, and has looked for differences in ecological processes between arid versus mesic habitats. We suggest a radically different explanation for the high species-richness of arid-zone Ctenotus, by shifting attention to a larger spatial scale: the regional species pool. Analyses of the geographic distributions of Ctenotus species confirm that more species coexist at sites in the arid-zone (mean =9.3 species per site) than in other climatic zones (means 2.4-7.6). However, the total number of species occurring within the arid-zone is actually lower, per km 2 of habitat, than is the case in some other climatic zones. That is, arid-zone Ctenotus show a higher local (alpha) species diversity, but a lower regional (gamma) diversity, than their mesic-habitat congeners. This apparent paradox occurs because most arid-zone species occur over vast areas (mean =1,035,000 km 2 ), whereas congeners from other climatic zones have smaller geographic ranges (200-373,000 km 2 ). The broad distributions of arid-zone taxa reflect the great spatial homogeneity in climatic conditions in this zone. That is, the "climate spaces" occupied are similar for Ctenotus species from all bioclimatic regions. Thus, a given amount of climatic space translates into a larger geographic distribution (and hence, more sympatry) in the arid-zone than in other areas. In summary, the high number of coexisting Ctenotus species in arid-zone habitats may simply reflect the facts that the arid zone is large (so that many species have evolved therein) and climatically homogeneous (so that any species evolving in that habitat type can disperse very widely, and thus overlap with many other species). Our approach explains much of the variance in local-assemblage species richness from regional to site scales; but explanations invoking biological attributes of the species concerned, the nature of their interactions with other species or with particular resources (such as prey or shelter) may still be significant at microhabitat scales. For lizard communities in Australia, species richness at a site may be determined more by continental biogeography rather than by ecological interactions.

Shallow Horizontal GCHP Effectiveness in Arid Climate Soils

NASA Astrophysics Data System (ADS)

North, Timothy James

Ground coupled heat pumps (GCHPs) have been used successfully in many environments to improve the heating and cooling efficiency of both small and large scale buildings. In arid climate regions, such as the Phoenix, Arizona metropolitan area, where the air condi-tioning load is dominated by cooling in the summer, GCHPs are difficult to install and operate. This is because the nature of soils in arid climate regions, in that they are both dry and hot, renders them particularly ineffective at dissipating heat. The first part of this thesis addresses applying the SVHeat finite element modeling soft-ware to create a model of a GCHP system. Using real-world data from a prototype solar-water heating system coupled with a ground-source heat exchanger installed in Menlo Park, California, a relatively accurate model was created to represent a novel GCHP panel system installed in a shallow vertical trench. A sensitivity analysis was performed to evaluate the accuracy of the calibrated model. The second part of the thesis involved adapting the calibrated model to represent an ap-proximation of soil conditions in arid climate regions, using a range of thermal properties for dry soils. The effectiveness of the GCHP in the arid climate region model was then evaluated by comparing the thermal flux from the panel into the subsurface profile to that of the prototype GCHP. It was shown that soils in arid climate regions are particularly inefficient at heat dissipation, but that it is highly dependent on the thermal conductivity inputted into the model. This demonstrates the importance of proper site characterization in arid climate regions. Finally, several soil improvement methods were researched to evaluate their potential for use in improving the effectiveness of shallow horizontal GCHP systems in arid climate regions.

Characteristics of precipitation recycling ratio with two evapotranspiration methods in Afro-Asian arid regions

NASA Astrophysics Data System (ADS)

Li, R.; Wang, C.

2016-12-01

The increasing precipitation in different arid regions has been observed in recent decades. While, the vapor sources, which can be classified into advective vapor and local vapor from evapotranspiration, are still uncertain in arid regions. To investigate the characteristics of local vapor in arid regions, precipitation recycling ratio (PRR) with two different evapotranspiration (ET) estimations, Penman-Monteith ET and a new approach which combined Penman-Monteith ET and surface soil moisture was calculated in arid regions of Afro-Asian continent, North Africa, West Asia and China-Mongolia, during 1980-2010. The results suggested that Penman-Monteith ET, which can be treated as regional potential ET, increased and showed an enhanced ET ability in arid regions. However, the ET calculated from the new approach, which can be treated as a reliable actual ET estimation, decreased, which means the local vapor has supplied less to total rainfall in target regions. Using the new approach ET data, PRR is calculated and analyzed. PRR in target regions ranges from 0.5% to 1.0%, which is less than the PRR calculated with Penman-Monteith ET, ranging from 3.7% to 5.6%. Meanwhile PRR decreased in China-Mongolia and North Africa while in West Asia increased in recent 30 years. Considering that a wetting trend existed in China-Mongolia and North Africa, and a drying trend occurred in West Asia, it can be concluded that PRR is a negative monitoring for Afro-Asian arid regions, where the decreasing PRR means that the more advective vapor enhanced the total precipitation, while the increasing PRR trend corresponds with less advective vapor and more local evapotranspiration contributes to increasing of total rainfall. Keywords: Afro-Asian Arid region, precipitation recycling, evapotranspiration, soil moisture.

Provisioning of bioavailable carbon between the wet and dry phases in a semi-arid floodplain.

PubMed

Baldwin, Darren S; Rees, Gavin N; Wilson, Jessica S; Colloff, Matthew J; Whitworth, Kerry L; Pitman, Tara L; Wallace, Todd A

2013-06-01

Ecosystem functioning on arid and semi-arid floodplains may be described by two alternate traditional paradigms. The pulse-reserve model suggests that rainfall is the main driver of plant growth and subsequent carbon and energy reserve formation in the soil of arid and semi-arid regions. The flood pulse concept suggests that periodic flooding facilitates the two-way transfer of materials between a river and its adjacent floodplain, but focuses mainly on the period when the floodplain is inundated. We compared the effects of both rainfall and flooding on soil moisture and carbon in a semi-arid floodplain to determine the relative importance of each for soil moisture recharge and the generation of a bioavailable organic carbon reserve that can potentially be utilised during the dry phase. Flooding, not rainfall, made a substantial contribution to moisture in the soil profile. Furthermore, the growth of aquatic macrophytes during the wet phase produced at least an order of magnitude more organic material than rainfall-induced pulse-reserve responses during the dry phase, and remained as recognizable soil carbon for years following flood recession. These observations have led us to extend existing paradigms to encompass the reciprocal provisioning of carbon between the wet and dry phases on the floodplain, whereby, in addition to carbon fixed during the dry phase being important for driving biogeochemical transformations upon return of the next wet phase, aquatic macrophyte carbon fixed during the wet phase is recognized as an important source of energy for the dry phase. Reciprocal provisioning presents a conceptual framework on which to formulate questions about the resistance and ecosystem resilience of arid and semi-arid floodplains in the face of threats like climate change and alterations to flood regimes.

Stable Isotopes as Indicators of Groundwater Recharge Mechanisms in Arid and Semi-arid Australia

NASA Astrophysics Data System (ADS)

Harrington, G. A.; Herczeg, A. L.

2001-05-01

The isotopic compositions of soil water and groundwaters in arid and semi-arid zones are always different from the mean composition of rainfall. Although evaporative processes always remove the lighter isotopes (1H and 16O) to the vapour phase, arid zone groundwaters are invariably depleted in the heavy isotopes (2H and 18O) relative to mean present day rainfall. We compare two sites, one in semi-arid South Australia and the other in arid Central Australia that have a similar mean annual rainfall (250 to 300 mm/a), very high potential evapotranspiration (2500 and 3500 mm/a respectively) but very different rainfall patterns (winter dominated versus summer monsoonal). We aim to evaluate whether inferences from groundwater \\delta2H and \\delta18O reveal information about palaeorecharge, or recharge mechanisms or a combination of both. Recharge to the unconfined limestone aquifer in the Mallee area of South Australia occurs annually via widespread (diffuse) infiltration of winter dominant rainfall. This process is reflected in soil and groundwater isotopic compositions that plot relatively close to both the Local Meteoric Water Line and the volume-weighted mean composition of winter rainfall, and have a deuterium excess (\\delta2H-8.\\delta18O) of between +2 and +8 for the freshest samples. Groundwater recharge to the arid Ti-Tree Basin occurs predominantly by inputs of partially-evaporated surface water from ephemeral rivers and flood-plains following rare, high-intensity storms that are derived from monsoonal activity to the north of Australia. These extreme events result in groundwater and soil water stable isotope compositions being significantly depleted in the heavy isotopes relative to the mean composition of rainfall and a deuterium excess of between minus 8 and +3 in the freshest groundwaters.

Progress and prospects of climate change impacts on hydrology in the arid region of northwest China.

PubMed

Chen, Yaning; Li, Zhi; Fan, Yuting; Wang, Huaijun; Deng, Haijun

2015-05-01

The arid region of Northwest China, located in the central Asia, responds sensitively to global climate change. Based on the newest research results, this paper analyzes the impacts of climate change on hydrology and the water cycle in the arid region of Northwest China. The analysis results show that: (1) In the northwest arid region, temperature and precipitation experienced "sharply" increasing in the past 50 years. The precipitation trend changed in 1987, and since then has been in a state of high volatility, during the 21st century, the increasing rate of precipitation was diminished. Temperature experienced a "sharply" increase in 1997; however, this sharp increasing trend has turned to an apparent hiatus since the 21st century. The dramatic rise in winter temperatures in the northwest arid region is an important reason for the rise in the average annual temperature, and substantial increases in extreme winter minimum temperature play an important role in the rising average winter temperature; (2) There was a significant turning point in the change of pan evaporation in the northwest arid area in 1993, i.e., in which a significant decline reversed to a significant upward trend. In the 21st century, the negative effects of global warming and increasing levels of evaporation on the ecology of the northwest arid region have been highlighted; (3) Glacier change has a significant impact on hydrology in the northwest arid area, and glacier inflection points have appeared in some rivers. The melting water supply of the Tarim River Basin possesses a large portion of water supplies (about 50%). In the future, the amount of surface water will probably remain at a high state of fluctuation. Copyright © 2015 Elsevier Inc. All rights reserved.

A novel microduplication of ARID1B: Clinical, genetic, and proteomic findings.

PubMed

Seabra, Catarina M; Szoko, Nicholas; Erdin, Serkan; Ragavendran, Ashok; Stortchevoi, Alexei; Maciel, Patrícia; Lundberg, Kathleen; Schlatzer, Daniela; Smith, Janice; Talkowski, Michael E; Gusella, James F; Natowicz, Marvin R

2017-09-01

Genetic alterations of ARID1B have been recently recognized as one of the most common mendelian causes of intellectual disability and are associated with both syndromic and non-syndromic phenotypes. The ARID1B protein, a subunit of the chromatin remodeling complex SWI/SNF-A, is involved in the regulation of transcription and multiple downstream cellular processes. We report here the clinical, genetic, and proteomic phenotypes of an individual with a unique apparent de novo mutation of ARID1B due to an intragenic duplication. His neurodevelopmental phenotype includes a severe speech/language disorder with full scale IQ scores 78-98 and scattered academic skill levels, expanding the phenotypic spectrum of ARID1B mutations. Haploinsufficiency of ARID1B was determined both by RNA sequencing and quantitative RT-PCR. Fluorescence in situ hybridization analysis supported an intragenic localization of the ARID1B copy number gain. Principal component analysis revealed marked differentiation of the subject's lymphoblast proteome from that of controls. Of 3426 proteins quantified, 1014 were significantly up- or down-regulated compared to controls (q < 0.01). Pathway analysis revealed highly significant enrichment for canonical pathways of EIF2 and EIF4 signaling, protein ubiquitination, tRNA charging and chromosomal replication, among others. Network analyses revealed down-regulation of: (1) intracellular components involved in organization of membranes, organelles, and vesicles; (2) aspects of cell cycle control, signal transduction, and nuclear protein export; (3) ubiquitination and proteosomal function; and (4) aspects of mRNA synthesis/splicing. Further studies are needed to determine the detailed molecular and cellular mechanisms by which constitutional haploinsufficiency of ARID1B causes syndromic and non-syndromic developmental disabilities. © 2017 Wiley Periodicals, Inc.

Increasingly Important Role of Atmospheric Aridity on Tibetan Alpine Grasslands

NASA Astrophysics Data System (ADS)

Ding, Jinzhi; Yang, Tao; Zhao, Yutong; Liu, Dan; Wang, Xiaoyi; Yao, Yitong; Peng, Shushi; Wang, Tao; Piao, Shilong

2018-03-01

Pronounced warming occurring on the Tibetan Plateau is expected to stimulate alpine grassland growth but could also increase atmospheric aridity that limits photosynthesis. But there lacks a systematic assessment of the impact of atmospheric aridity on alpine grassland productivity. Here we combine satellite observations, flux-tower-based productivity, and model simulations to quantify the effect of atmospheric aridity on grassland productivity and its temporal change between 1982 and 2011. We found a negative impact of atmospheric vapor pressure deficit on grassland productivity. This negative effect becomes increasingly intensified in terms of the impact severity and extent, suggesting an increasingly important role of atmospheric aridity on productivity. We further demonstrated that this negative effect is mitigated but cannot be overcompensated by the positive effect of rising CO2. Given that vapor pressure deficit is projected to further increase by 10-38% in the future, Tibetan alpine grasslands will face an increasing stress of atmospheric drought.

Modeling the distributed effects of forest thinning on the long-term water balance and streamflow extremes for a semi-arid basin in the southwestern US

NASA Astrophysics Data System (ADS)

Moreno, Hernan A.; Gupta, Hoshin V.; White, Dave D.; Sampson, David A.

2016-03-01

To achieve water resource sustainability in the water-limited southwestern US, it is critical to understand the potential effects of proposed forest thinning on the hydrology of semi-arid basins, where disturbances to headwater catchments can cause significant changes in the local water balance components and basinwise streamflows. In Arizona, the Four Forest Restoration Initiative (4FRI) is being developed with the goal of restoring 2.4 million acres of ponderosa pine along the Mogollon Rim. Using the physically based, spatially distributed triangulated irregular network (TIN)-based Real-time Integrated Basin Simulator (tRIBS) model, we examine the potential impacts of the 4FRI on the hydrology of Tonto Creek, a basin in the Verde-Tonto-Salt (VTS) system, which provides much of the water supply for the Phoenix metropolitan area. Long-term (20-year) simulations indicate that forest removal can trigger significant shifts in the spatiotemporal patterns of various hydrological components, causing increases in net radiation, surface temperature, wind speed, soil evaporation, groundwater recharge and runoff, at the expense of reductions in interception and shading, transpiration, vadose zone moisture and snow water equivalent, with south-facing slopes being more susceptible to enhanced atmospheric losses. The net effect will likely be increases in mean and maximum streamflow, particularly during El Niño events and the winter months, and chiefly for those scenarios in which soil hydraulic conductivity has been significantly reduced due to thinning operations. In this particular climate, forest thinning can lead to net loss of surface water storage by vegetation and snowpack, increasing the vulnerability of ecosystems and populations to larger and more frequent hydrologic extreme conditions on these semi-arid systems.

Resource pulses and mammalian dynamics: conceptual models for hummock grasslands and other Australian desert habitats.

PubMed

Letnic, M; Dickman, C R

2010-08-01

Resources are produced in pulses in many terrestrial environments, and have important effects on the population dynamics and assemblage structure of animals that consume them. Resource-pulsing is particularly dramatic in Australian desert environments owing to marked spatial and temporal variability in rainfall, and thus primary productivity. Here, we first review how Australia's desert mammals respond to fluctuations in resource production, and evaluate the merits of three currently accepted models (the ecological refuge, predator refuge and fire-mosaic models) as explanations of the observed dynamics. We then integrate elements of these models into a novel state-and-transition model and apply it to well-studied small mammal assemblages that inhabit the vast hummock grassland, or spinifex, landscapes of the continental inland. The model has four states that are defined by differences in species composition and abundance, and eight transitions or processes that prompt shifts from one state to another. Using this model as a template, we construct three further models to explain mammalian dynamics in cracking soil habitats of the Lake Eyre Basin, gibber plains of the Channel Country, and the chenopod shrublands of arid southern Australia. As non-equilibrium concepts that recognise the strongly intermittent nature of resource pulsing in arid Australia, state-and-transition models provide useful descriptors of both spatial and temporal patterns in mammal assemblages. The models should help managers to identify when and where to implement interventions to conserve native mammals, such as control burns, reduced grazing or predator management. The models also should improve understanding of the potential effects of future climate change on mammal assemblages in arid environments in general. We conclude by proposing several tests that could be used to refine the models and guide further research.

Hydraulic connectivity and evaporation control the water quality and sources of chromophoric dissolved organic matter in Lake Bosten in arid northwest China.

PubMed

Zhou, Lei; Zhou, Yongqiang; Hu, Yang; Cai, Jian; Bai, Chengrong; Shao, Keqiang; Gao, Guang; Zhang, Yunlin; Jeppesen, Erik; Tang, Xiangming

2017-12-01

Lake Bosten is the largest oligosaline lake in arid northwestern China, and water from its tributaries and evaporation control the water balance of the lake. In this study, water quality and chromophoric dissolved organic matter (CDOM) absorption and fluorescence were investigated in different seasons to elucidate how hydraulic connectivity and evaporation may affect the water quality and variability of CDOM in the lake. Mean suspended solids and turbidity were significantly higher in the upstream tributaries than in the lake, the difference being notably more pronounced in the wet than in the dry season. A markedly higher mean first principal component (PC1) score, which was significantly positively related to protein-like components, and a considerably lower fluorescence peak integration ratio - I C :I T , indicative of the terrestrial humic-like CDOM contribution percentage, were observed in the lake than in the upstream tributaries. Correspondingly, notably higher contribution percentages of terrestrial humic-like components were observed in the river mouth areas than in the remaining lake regions. Furthermore, significantly higher mean turbidity, and notably lower mean conductivity and salinity, were recorded in the southwestern Kaidu river mouth than in the remaining lake regions in the wet season. Notably higher mean salinity is recorded in Lake Bosten than in upstream tributaries. Autochthonous protein-like associated amino-acids and also PC1 scores increased significantly with increasing salinity. We conclude that the dynamics of water quality and CDOM composition in remote arid Lake Bosten are strongly driven by evaporation and also the hydraulic connectivity between the upstream tributaries and the downstream lake. Copyright © 2017 Elsevier Ltd. All rights reserved.

Understanding hydrologic budgets, dynamics in an arid basin and explore spatial scaling properties using Process-based Adaptive Watershed Simulator (PAWS)

NASA Astrophysics Data System (ADS)

Fang, K.; Shen, C.; Salve, R.

2013-12-01

The Southern California hot desert hosts a fragile ecosystem as well as a range of human economic activities, primarily mining, energy production and recreation. This inland arid landscape is characterized by occasional intensive precipitation events and year-round strong potential evapotranspiration. In this landscape, water and especially groundwater is vital for ecosystem functions and human use. However, the impact of recent development on the sustainability of groundwater resources in the area has not been thoroughly investigated. We apply an integrated, physically-based hydrologic-land surface model, the Process-based Adaptive Watershed Simulator + Community Land Model (PAWS+CLM) to evaluate the sustainability of the groundwater resources in the area. We elucidate the spatio-temporal patterns of hydrologic fluxes and budgets. The modeling results indicate that mountain front recharge is the essential recharging mechanism for the alluvial aquifer. Although pumping activities do not exceed annual-average recharge values, they are still expected to contribute significantly to groundwater drawdown in business-as-usual scenario. The impact of groundwater withdrawals is significant on the desert ecosystem. The relative importance of groundwater flow on NPP rises significantly as compared to other ecosystems. We further evaluate the fractal scaling properties of soil moisture in this very arid system and found the relationship to be much more static in time than that found in a humid continental climate system. The scaling exponents can be predicted using simple functions of the mean. Therefore, multi-scale model based on coarse-resolution surrogate model is expected to perform well in this system. The modeling result is also important for assessing the groundwater sustainability and impact of human activities in the desert environment.

Integrated double mulching practices optimizes soil temperature and improves soil water utilization in arid environments

NASA Astrophysics Data System (ADS)

Yin, Wen; Feng, Fuxue; Zhao, Cai; Yu, Aizhong; Hu, Falong; Chai, Qiang; Gan, Yantai; Guo, Yao

2016-09-01

Water shortage threatens agricultural sustainability in many arid and semiarid areas of the world. It is unknown whether improved water conservation practices can be developed to alleviate this issue while increasing crop productivity. In this study, we developed a "double mulching" system, i.e., plastic film coupled with straw mulch, integrated together with intensified strip intercropping. We determined (i) the responses of soil evaporation and moisture conservation to the integrated double mulching system and (ii) the change of soil temperature during key plant growth stages under the integrated systems. Experiments were carried out in northwest China in 2009 to 2011. Results show that wheat-maize strip intercropping in combination with plastic film and straw covering on the soil surface increased soil moisture (mm) by an average of 3.8 % before sowing, 5.3 % during the wheat and maize co-growth period, 4.4 % after wheat harvest, and 4.9 % after maize harvest, compared to conventional practice (control). The double mulching decreased total evapotranspiration of the two intercrops by an average of 4.6 % ( P < 0.05), compared to control. An added feature was that the double mulching system decreased soil temperature in the top 10-cm depth by 1.26 to 1.31 °C in the strips of the cool-season wheat, and by 1.31 to 1.51 °C in the strips of the warm-season maize through the 2 years. Soil temperature of maize strips higher as 1.25 to 1.94 °C than that of wheat strips in the top 10-cm soil depth under intercropping with the double mulching system; especially higher as 1.58 to 2.11 °C under intercropping with the conventional tillage; this allows the two intercrops to grow in a well "collaborative" status under the double mulching system during their co-growth period. The improvement of soil moisture and the optimization of soil temperature for the two intercrops allow us to conclude that wheat-maize intensification with the double mulching system can be used as an effective farming model in alleviating water shortage issues experiencing in water shortage areas.

Integrative Governance of Environmental Water in Australia's Murray-Darling Basin: Evolving Challenges and Emerging Pathways.

PubMed

Bischoff-Mattson, Zachary; Lynch, Amanda H

2017-07-01

Integration, a widely promoted response to the multi-scale complexities of social-environmental sustainability, is diversely and sometimes poorly conceptualized. In this paper we explore integrative governance, which we define as an iterative and contextual process for negotiating and advancing the common interest. We ground this definition in a discussion of institutional factors conditioning integrative governance of environmental water in Australia's Murray-Darling Basin. The Murray-Darling Basin is an iconic system of social-ecological complexity, evocative of large-scale conservation challenges in other developed arid river basins. Our critical assessment of integrative governance practices in that context emerges through analysis of interviews with policy participants and documents pertaining to environmental water management in the tri-state area of southwestern New South Wales, northwestern Victoria, and the South Australian Riverland. We identify four linked challenges: (i) decision support for developing socially robust environmental water management goals, (ii) resource constraints on adaptive practice, (iii) inter-state differences in participatory decision-making and devolution of authority, and (iv) representative inclusion in decision-making. Our appraisal demonstrates these as pivotal challenges for integrative governance in the common interest. We conclude by offering a perspective on the potential for supporting integrative governance through the bridging capacity of Australia's Commonwealth Environmental Water Holder.

CO2 and fire influence tropical ecosystem stability in response to climate change.

PubMed

Shanahan, Timothy M; Hughen, Konrad A; McKay, Nicholas P; Overpeck, Jonathan T; Scholz, Christopher A; Gosling, William D; Miller, Charlotte S; Peck, John A; King, John W; Heil, Clifford W

2016-07-18

Interactions between climate, fire and CO2 are believed to play a crucial role in controlling the distributions of tropical woodlands and savannas, but our understanding of these processes is limited by the paucity of data from undisturbed tropical ecosystems. Here we use a 28,000-year integrated record of vegetation, climate and fire from West Africa to examine the role of these interactions on tropical ecosystem stability. We find that increased aridity between 28-15 kyr B.P. led to the widespread expansion of tropical grasslands, but that frequent fires and low CO2 played a crucial role in stabilizing these ecosystems, even as humidity changed. This resulted in an unstable ecosystem state, which transitioned abruptly from grassland to woodlands as gradual changes in CO2 and fire shifted the balance in favor of woody plants. Since then, high atmospheric CO2 has stabilized tropical forests by promoting woody plant growth, despite increased aridity. Our results indicate that the interactions between climate, CO2 and fire can make tropical ecosystems more resilient to change, but that these systems are dynamically unstable and potentially susceptible to abrupt shifts between woodland and grassland dominated states in the future.

CO2 and fire influence tropical ecosystem stability in response to climate change

NASA Astrophysics Data System (ADS)

Shanahan, Timothy M.; Hughen, Konrad A.; McKay, Nicholas P.; Overpeck, Jonathan T.; Scholz, Christopher A.; Gosling, William D.; Miller, Charlotte S.; Peck, John A.; King, John W.; Heil, Clifford W.

2016-07-01

Interactions between climate, fire and CO2 are believed to play a crucial role in controlling the distributions of tropical woodlands and savannas, but our understanding of these processes is limited by the paucity of data from undisturbed tropical ecosystems. Here we use a 28,000-year integrated record of vegetation, climate and fire from West Africa to examine the role of these interactions on tropical ecosystem stability. We find that increased aridity between 28-15 kyr B.P. led to the widespread expansion of tropical grasslands, but that frequent fires and low CO2 played a crucial role in stabilizing these ecosystems, even as humidity changed. This resulted in an unstable ecosystem state, which transitioned abruptly from grassland to woodlands as gradual changes in CO2 and fire shifted the balance in favor of woody plants. Since then, high atmospheric CO2 has stabilized tropical forests by promoting woody plant growth, despite increased aridity. Our results indicate that the interactions between climate, CO2 and fire can make tropical ecosystems more resilient to change, but that these systems are dynamically unstable and potentially susceptible to abrupt shifts between woodland and grassland dominated states in the future.

Integration of remote sensing and hydrologic modeling through multi-disciplinary semiarid field campaigns: Moonsoon 1990, Walnut Gulch 1992, and SALSA-MEX

NASA Technical Reports Server (NTRS)

Moran, M. S.; Goodrich, D. C.; Kustas, W. P.

1994-01-01

A research and modeling strategy is presented for development of distributed hydrologic models given by a combination of remotely sensed and ground based data. In support of this strategy, two experiments Moonsoon'90 and Walnut Gulch'92 were conducted in a semiarid rangeland southeast of Tucson, Arizona, (U.S.) and a third experiment, the SALSA-MEX (Semi Arid Land Surface Atmospheric Mountain Experiment) was proposed. Results from the Moonsoon'90 experiment substantially advanced the understanding of the hydrologic and atmospheric fluxes in an arid environment and provided insight into the use of remote sensing data for hydrologic modeling. The Walnut Gulch'92 experiment addressed the seasonal hydrologic dynamics of the region and the potential of combined optical microwave remote sensing for hydrologic applications. SALSA-MEX will combine measurements and modeling to study hydrologic processes influenced by surrounding mountains, such as enhanced precipitation, snowmelt and recharge to ground water aquifers. The results from these experiments, along with the extensive experimental data bases, should aid the research community in large scale modeling of mass and energy exchanges across the soil-plant-atmosphere interface.

Potential impacts of global warming on water resources in southern California.

PubMed

Beuhler, M

2003-01-01

Global warming will have a significant impact on water resources within the 20 to 90-year planning period of many water projects. Arid and semi-arid regions such as Southern California are especially vulnerable to anticipated negative impacts of global warming on water resources. Long-range water facility planning must consider global climate change in the recommended mix of new facilities needed to meet future water requirements. The generally accepted impacts of global warming include temperature, rising sea levels, more frequent and severe floods and droughts, and a shift from snowfall to rain. Precipitation changes are more difficult to predict. For Southern California, these impacts will be especially severe on surface water supplies. Additionally, rising sea levels will exacerbate salt-water intrusion into freshwater and impact the quality of surface water supplies. Integrated water resources planning is emerging as a tool to develop water supplies and demand management strategies that are less vulnerable to the impacts of global warming. These tools include water conservation, conjunctive use of surface and groundwater and desalination of brackish water and possibly seawater. Additionally, planning for future water needs should include explicit consideration of the potential range of global warming impacts through techniques such as scenario planning.

Verification of watershed vegetation restoration policies, arid China

PubMed Central

Zhang, Chengqi; Li, Yu

2016-01-01

Verification of restoration policies that have been implemented is of significance to simultaneously reduce global environmental risks while also meeting economic development goals. This paper proposed a novel method according to the idea of multiple time scales to verify ecological restoration policies in the Shiyang River drainage basin, arid China. We integrated modern pollen transport characteristics of the entire basin and pollen records from 8 Holocene sedimentary sections, and quantitatively reconstructed the millennial-scale changes of watershed vegetation zones by defining a new pollen-precipitation index. Meanwhile, Empirical Orthogonal Function method was used to quantitatively analyze spatial and temporal variations of Normalized Difference Vegetation Index in summer (June to August) of 2000–2014. By contrasting the vegetation changes that mainly controlled by millennial-scale natural ecological evolution with that under conditions of modern ecological restoration measures, we found that vegetation changes of the entire Shiyang River drainage basin are synchronous in both two time scales, and the current ecological restoration policies met the requirements of long-term restoration objectives and showed promising early results on ecological environmental restoration. Our findings present an innovative method to verify river ecological restoration policies, and also provide the scientific basis to propose future emphasizes of ecological restoration strategies. PMID:27470948

Verification of watershed vegetation restoration policies, arid China

NASA Astrophysics Data System (ADS)

Zhang, Chengqi; Li, Yu

2016-07-01

Verification of restoration policies that have been implemented is of significance to simultaneously reduce global environmental risks while also meeting economic development goals. This paper proposed a novel method according to the idea of multiple time scales to verify ecological restoration policies in the Shiyang River drainage basin, arid China. We integrated modern pollen transport characteristics of the entire basin and pollen records from 8 Holocene sedimentary sections, and quantitatively reconstructed the millennial-scale changes of watershed vegetation zones by defining a new pollen-precipitation index. Meanwhile, Empirical Orthogonal Function method was used to quantitatively analyze spatial and temporal variations of Normalized Difference Vegetation Index in summer (June to August) of 2000-2014. By contrasting the vegetation changes that mainly controlled by millennial-scale natural ecological evolution with that under conditions of modern ecological restoration measures, we found that vegetation changes of the entire Shiyang River drainage basin are synchronous in both two time scales, and the current ecological restoration policies met the requirements of long-term restoration objectives and showed promising early results on ecological environmental restoration. Our findings present an innovative method to verify river ecological restoration policies, and also provide the scientific basis to propose future emphasizes of ecological restoration strategies.

Chemical Records in Snowpits from High Altitude Glaciers in the Tibetan Plateau and Its Surroundings.

PubMed

Zhang, Yulan; Kang, Shichang; Zhang, Qianggong; Gao, Tanguang; Guo, Junming; Grigholm, Bjorn; Huang, Jie; Sillanpää, Mika; Li, Xiaofei; Du, Wentao; Li, Yang; Ge, Xinlei

2016-01-01

Glaciochemistry can provide important information about climatic change and environmental conditions, as well as for testing regional and global atmospheric trace transport models. In this study, δ18O and selected chemical constituents records in snowpits collected from eight glaciers in the Tibetan Plateau and adjacent areas have been investigated. Drawing on the integrated data, our study summarized the seasonal and spatial characteristics of snow chemistry, and their potential sources. Distinct seasonal patterns of δ18O values in snowpits indicated more negative in the south TP controlled by Indian monsoon, and less negative in the north TP and Tien Shan. Overall increasing concentrations of microparticles and crustal ions from south to north indicated a strength of dust deposition on glaciers from semi-arid and arid regions. Principal component analysis and air mass trajectories suggested that chemical constituents were mainly attributable to crustal sources as demonstrated by the high concentrations of ions occurring during the non-monsoon seasons. Nevertheless, other sources, such as anthropogenic pollution, played an important role on chemical variations of glaciers near the human activity centers. This study concluded that air mass transport from different sources played important roles on the spatial distributions and seasonality of glaciochemistry.

Genome of the Cyanobacterium Microcoleus vaginatusFGP-2, a Photosynthetic Ecosystem Engineer of Arid Land Soil Biocrusts Worldwide▿

PubMed Central

Starkenburg, Shawn R.; Reitenga, Krista G.; Freitas, Tracey; Johnson, Shannon; Chain, Patrick S. G.; Garcia-Pichel, Ferran; Kuske, Cheryl R.

2011-01-01

The filamentous cyanobacterium Microcoleus vaginatusis found in arid land soils worldwide. The genome of M. vaginatusstrain FGP-2 allows exploration of genes involved in photosynthesis, desiccation tolerance, alkane production, and other features contributing to this organism's ability to function as a major component of biological soil crusts in arid lands. PMID:21705610

Functionally relevant climate variables for arid lands: Aclimatic water deficit approach for modelling desert shrub distributions

Treesearch

Thomas E. Dilts; Peter J. Weisberg; Camie M. Dencker; Jeanne C. Chambers

2015-01-01

We have three goals. (1) To develop a suite of functionally relevant climate variables for modelling vegetation distribution on arid and semi-arid landscapes of the Great Basin, USA. (2) To compare the predictive power of vegetation distribution models based on mechanistically proximate factors (water deficit variables) and factors that are more mechanistically removed...

ARID relative calibration experimental data and analysis

NASA Technical Reports Server (NTRS)

Doty, Keith L

1992-01-01

Several experiments measure the orientation error of the ARID end-frame as well as linear displacements in the Orbiter's y- and z-axes. In each experiment the position of the ARID on the trolley is fixed and the manipulator extends and retracts along the Orbiter's y-axis. A sensor platform consisting of four sonars arranged in a '+' pattern measures the platform pitch about the Orbiter's y-axis (angle b) and yaw about the Orbiter's x-axis (angle alpha). Corroborating measurements of the yaw error were performed using a carpenter's level to keep the platform perpendicular to the gravity vector at each ARID pose being measured.

On observed aridity changes over the semiarid regions of India in a warming climate

NASA Astrophysics Data System (ADS)

Ramarao, M. V. S.; Sanjay, J.; Krishnan, R.; Mujumdar, M.; Bazaz, Amir; Revi, Aromar

2018-05-01

In this study, a quantitative assessment of observed aridity variations over the semiarid regions of India is performed for the period 1951-2005 using a dimensionless ratio of annual precipitation (P) and potential evapotranspiration (PET), estimated from five different observed gridded precipitation data sets. The climatological values and changes of this aridity index are found to be sensitive to the choice of the precipitation observations. An assessment of P/PET estimated using the ensemble mean precipitation shows an increase in aridity over several semiarid regions of India, despite the sensitivity of P/PET variations across individual precipitation data sets. Our results indicate that precipitation variations over the semiarid regions of India are outpacing the changes in potential evapotranspiration and, thereby, influencing aridity changes in a significant manner. Our results further reveal a 10% expansion in the area of the semiarid regions during recent decades relative to previous decades, thus highlighting the need for better adaptation strategies and mitigation planning for the semiarid regions in India. The sensitivity of aridity index to multiple PET data sets can be an additional source of uncertainty and will be addressed in a future study.

Microbial Diversity in Soil, Sand Dune and Rock Substrates of the Thar Monsoon Desert, India.

PubMed

Rao, Subramanya; Chan, Yuki; Bugler-Lacap, Donnabella C; Bhatnagar, Ashish; Bhatnagar, Monica; Pointing, Stephen B

2016-03-01

A culture-independent diversity assessment of archaea, bacteria and fungi in the Thar Desert in India was made. Six locations in Ajmer, Jaisalmer, Jaipur and Jodhupur included semi-arid soils, arid soils, arid sand dunes, plus arid cryptoendolithic substrates. A real-time quantitative PCR approach revealed that bacteria dominated soils and cryptoendoliths, whilst fungi dominated sand dunes. The archaea formed a minor component of all communities. Comparison of rRNA-defined community structure revealed that substrate and climate rather than location were the most parsimonious predictors. Sequence-based identification of 1240 phylotypes revealed that most taxa were common desert microorganisms. Semi-arid soils were dominated by actinobacteria and alpha proteobacteria, arid soils by chloroflexi and alpha proteobacteria, sand dunes by ascomycete fungi and cryptoendoliths by cyanobacteria. Climatic variables that best explained this distribution were mean annual rainfall and maximum annual temperature. Substrate variables that contributed most to observed diversity patterns were conductivity, soluble salts, Ca(2+) and pH. This represents an important addition to the inventory of desert microbiota, novel insight into the abiotic drivers of community assembly, and the first report of biodiversity in a monsoon desert system.

Land–atmosphere feedbacks amplify aridity increase over land under global warming

USGS Publications Warehouse

Berg, Alexis; Findell, Kirsten; Lintner, Benjamin; Giannini, Alessandra; Seneviratne, Sonia I.; van den Hurk, Bart; Lorenz, Ruth; Pitman, Andy; Hagemann, Stefan; Meier, Arndt; Cheruy, Frédérique; Ducharne, Agnès; Malyshev, Sergey; Milly, Paul C. D.

2016-01-01

The response of the terrestrial water cycle to global warming is central to issues including water resources, agriculture and ecosystem health. Recent studies indicate that aridity, defined in terms of atmospheric supply (precipitation, P) and demand (potential evapotranspiration, Ep) of water at the land surface, will increase globally in a warmer world. Recently proposed mechanisms for this response emphasize the driving role of oceanic warming and associated atmospheric processes. Here we show that the aridity response is substantially amplified by land–atmosphere feedbacks associated with the land surface’s response to climate and CO2 change. Using simulations from the Global Land Atmosphere Coupling Experiment (GLACE)-CMIP5 experiment, we show that global aridity is enhanced by the feedbacks of projected soil moisture decrease on land surface temperature, relative humidity and precipitation. The physiological impact of increasing atmospheric CO2 on vegetation exerts a qualitatively similar control on aridity. We reconcile these findings with previously proposed mechanisms by showing that the moist enthalpy change over land is unaffected by the land hydrological response. Thus, although oceanic warming constrains the combined moisture and temperature changes over land, land hydrology modulates the partitioning of this enthalpy increase towards increased aridity.

"Global warming, continental drying? Interpreting projected aridity changes over land under climate change"

NASA Astrophysics Data System (ADS)

Berg, Alexis

2017-04-01

In recent years, a number of studies have suggested that, as climate warms, the land surface will globally become more arid. Such results usually rely on drought or aridity diagnostics, such as the Palmer Drought Severity Index or the Aridity Index (ratio of precipitation over potential evapotranspiration, PET), applied to climate model projections of surface climate. From a global perspective, the projected widespread drying of the land surface is generally interpreted as the result of the dominant, ubiquitous warming-induced PET increase, which overwhelms the slight overall precipitation increase projected over land. However, several lines of evidence, based on (paleo)observations and climate model projections, raise questions regarding this interpretation of terrestrial climate change. In this talk, I will review elements of the literature supporting these different perspectives, and will present recent results based on CMIP5 climate model projections regarding changes in aridity over land that shed some light on this discussion. Central to the interpretation of projected land aridity changes is the understanding of projected PET trends over land and their link with changes in other variables of the terrestrial water cycle (ET, soil moisture) and surface climate in the context of the coupled land-atmosphere system.

Latent heat loss of dairy cows in an equatorial semi-arid environment

NASA Astrophysics Data System (ADS)

da Silva, Roberto Gomes; Maia, Alex Sandro Campos; de Macedo Costa, Leonardo Lelis; de Queiroz, João Paulo A. Fernandes

2012-09-01

The present study aimed to evaluate evaporative heat transfer of dairy cows bred in a hot semi-arid environment. Cutaneous ( E S) and respiratory ( E R) evaporation were measured (810 observations) in 177 purebred and crossbred Holstein cows from five herds located in the equatorial semi-arid region, and one herd in the subtropical region of Brazil. Rectal temperature ( T R), hair coat surface temperature ( T S) and respiratory rate ( F R) were also measured. Observations were made in the subtropical region from August to December, and in the semi-arid region from April to July. Measurements were done from 1100 to 1600 hours, after cows remained in a pen exposed to the sun. Environmental variables measured in the same locations as the animals were black globe temperature ( T G), air temperature ( T A), wind speed ( U), and partial air vapour pressure ( P V). Data were analysed by mixed models, using the least squares method. Results showed that average E S and E R were higher in the semi-arid region (117.2 W m-2 and 44.0 W m-2, respectively) than in the subtropical region (85.2 W m-2 and 30.2 W m-2, respectively). Herds and individual cows were significant effects ( P < 0.01) for all traits in the semi-arid region. Body parts did not affect T S and E S in the subtropical region, but was a significant effect ( P < 0.01) in the semi-arid region. The average flank T S (42.8°C) was higher than that of the neck and hindquarters (39.8°C and 41.6°C, respectively). Average E S was higher in the neck (133.3 W m-2) than in the flank (116.2 W m-2) and hindquarters (98.6 W m-2). Coat colour affected significantly both T S and E S ( P < 0.01). Black coats had higher T S and E S in the semi-arid region (41.7°C and 117.2 W m-2, respectively) than white coats (37.2°C and 106.7 W m-2, respectively). Rectal temperatures were almost the same in both subtropical and semi-arid regions. The results highlight the need for improved management methods specific for semi-arid regions.

The 100th Meridian Climate Divide & Its Present and Future Impact on the Human Geography of the American Great Plains

NASA Astrophysics Data System (ADS)

Feldman, J. R.; Seager, R.; Ting, M.; Lis, N.

2016-12-01

The 100th meridian has been viewed historically as a symbolic boundary between the more arid western plains in the Midwestern United States, and the more humid eastern half of the country. The purpose of this project is to evaluate the true climatic characteristics of this divide, and to determine its implications for landscape and land use, with a focus on agriculture. An aridity index is first defined as precipitation divided by the potential evapotranspiration, P/PET, where PET is calculated with the Penman-Monteith equation using data from the North American Land Data Assimilation System Phase 2 (NLDAS-2) for the period 1979-2015. The NLDAS-2 is a compilation of observed climate data and output from three land surface models: NOAH, VIC, and MOSAIC. The three models agreed on a clear west-east gradient in aridity, with a boundary dryland boundary at approximately the 100th meridian. The aridity index was then compared to the soil moisture from each model, to determine how it impacts water storage, and the soil moisture was consistent both annually and seasonally. Using USDA data from the 2012 census, the longitudinal distribution of agricultural variables, such as farm size and percent corn of total cropland, were examined. Clear differences were observed in these variables across the aridity boundary, especially in the Northern Plains. We performed regressions between these variables and the aridity index, and found a close relationship between the aridity index and the percent of corn and wheat grown, as well as farm size. To project the potential future changes in agricultural practices due to changes in aridity, we used CMIP5 projections of the aridity index changes over the plains in the period 2040-2060. In tandem with the regression relation, we were able to predict that the percent corn of total cropland may decrease by as much as 20% at all longitudes, and it may not even be feasible to grow east of the 100th meridian. Farm size is expected to increase across the plains. Thus, we began to explore how the farm economy may be impacted by the shifting aridity gradient due to climate change in the coming century.

Seed germination, seedling traits, and seed bank of the tree Moringa peregrina (Moringaceae) in a hyper-arid environment.

PubMed

Gomaa, Nasr H; Picó, F Xavier

2011-06-01

Water-limited hot environments are good examples of hyper-aridity. Trees are scarce in these environments but some manage to survive, such as the tree Moringa peregrina. Understanding how trees maintain viable populations in extremely arid environments may provide insight into the adaptive mechanisms by which trees cope with extremely arid weather conditions. This understanding is relevant to the current increasing aridity in several regions of the world. Seed germination experiments were conducted to assess variation in seed mass, seed germination, and seedling traits of Moringa peregrina plants and the correlations among these traits. A seed burial experiment was also designed to study the fate of M. peregrina seeds buried at two depths in the soil for two time periods. On average, seeds germinated in three days and seedling shoots grew 0.7 cm per day over three weeks. Larger seeds decreased germination time and increased seedling growth rates relative to smaller seeds. Seeds remained quiescent in the soil and germination was very high at both depths and burial times. The after-ripening time of Moringa peregrina seeds is short and seeds germinate quickly after imbibition. Plants of M. peregrina may increase in hyper-arid environments from seeds with larger mass, shorter germination times, and faster seedling growth rates. The results also illustrate the adjustment in allocation to seed biomass and correlations among seed and seedling traits that allows M. peregrina to be successful in coping with aridity in its environment.

Assessment of the spatial distribution of soil microbial communities in patchy arid and semi-arid landscapes of the Negev Desert using combined PLFA and DGGE analyses.

PubMed

Ben-David, Eric A; Zaady, Eli; Sher, Yoni; Nejidat, Ali

2011-06-01

Arid and semi-arid ecosystems are often characterized by vegetation patchiness and variable availability of resources. Phospholipid fatty acid (PLFA) and 16S rRNA gene fragment analyses were used to compare the bulk soil microbial community structure at patchy arid and semi-arid landscapes. Multivariate analyses of the PLFA data and the 16S rRNA gene fragments were in agreement with each other, suggesting that the differences between bulk soil microbial communities were primarily related to shrub vs intershrub patches, irrespective of climatic or site differences. This suggests that the mere presence of a living shrub is the dominant driving factor for the differential adaptation of the microbial communities. Lipid markers suggested as indicators of Gram-positive bacteria were higher in soils under the shrub canopies, while markers suggested as indicators of cyanobacteria and anaerobic bacteria were elevated in the intershrub soils. Secondary differences between soil microbial communities were associated with intershrub characteristics and to a lesser extent with the shrub species. This study provides an insight into the multifaceted nature of the factors that shape the microbial community structure in patchy desert landscapes. It further suggests that these drivers not only act in concert but also in a way that is dependent on the aridity level. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Pearl millet genome sequence provides a resource to improve agronomic traits in arid environments

USDA-ARS?s Scientific Manuscript database

Pearl millet [Pennisetum glaucum (L.) R. Br., syn. Cenchrus americanus (L.) Morrone], is a staple food for over 90 million poor farmers in arid and semi-arid regions of sub-Saharan Africa and South Asia. We report the ~1.79 Gb genome sequence of reference genotype Tift 23D2B1-P1-P5, which contains a...

Retreating or standing: Responses of forest species and steppe species to climate change in arid eastern central Asia

Treesearch

Hong-Xiang Zhang; Ming-Li Zhang; Stewart C. Sanderson

2013-01-01

The temperature in arid Eastern Central Asia is projected to increase in the future, accompanied by increased variability of precipitation. To investigate the impacts of climate change on plant species in this area, we selected two widespread species as candidates, Clematis sibirica and C. songorica, from montane coniferous forest and arid steppe habitats respectively...

Can biochar be used as a seed coating to improve native plant germination and growth in arid conditions?

Treesearch

Mary I. Williams; R. Kasten Dumroese; Deborah S. Page-Dumroese; Stuart P. Hardegree

2016-01-01

Direct seeding is a common large-scale restoration practice for revegetating arid and semi-arid lands, but success can be limited by moisture and temperature. Seed coating technologies that use biochar may have the potential to overcome moisture and temperature limitations on native plant germination and growth. Biochar is a popular agronomic tool for improving soil...

Mathematical Modeling for Evaluation of Field Water Supply Alternatives (Arid and Semi-Arid Regions).

DTIC Science & Technology

1981-01-01

switch box would normally be required to operate the diatomite filter pumps. However, in hot arid regions where ambient water temperatures are re- latively...9 Tactical Water Distribution Systems...................... 9 Temperature of Waters in the Desert ..................... 10...concentration of FAC when loaded; daily FAC; daily water temperature in each tank; weekly pH determination; results of all chemical laboratory

Resistance Status of the Malaria Vector Mosquitoes, Anopheles stephensi and Anopheles subpictus Towards Adulticides and Larvicides in Arid and Semi-Arid Areas of India

PubMed Central

Tikar, S. N.; Mendki, M.J.; Sharma, A. K.; Sukumaran, D.; Veer, Vijay; Prakash, Shri; Parashar, B. D.

2011-01-01

Susceptibility studies of malaria vectors Anopheles stephensi Liston (Diptera: Culicidae) and An. subpictus Grassi collected during 2004–2007 from various locations of Arid and Semi-Arid Zone of India were conducted by adulticide bioassay of DDT, malathion, deltamethrin and larvicide bioassay of fenthion, temephos, chlorpyriphos and malathion using diagnostic doses. Both species from all locations exhibited variable resistance to DDT and malathion from majority of location. Adults of both the species were susceptible to Deltamethrin. Larvae of both the Anopheline species showed some evidence of resistance to chlorpyriphos followed by fenthion whereas susceptible to temephos and malathion. PMID:21870971

Model projections of an imminent transition to a more arid climate in southwestern North America.

PubMed

Seager, Richard; Ting, Mingfang; Held, Isaac; Kushnir, Yochanan; Lu, Jian; Vecchi, Gabriel; Huang, Huei-Ping; Harnik, Nili; Leetmaa, Ants; Lau, Ngar-Cheung; Li, Cuihua; Velez, Jennifer; Naik, Naomi

2007-05-25

How anthropogenic climate change will affect hydroclimate in the arid regions of southwestern North America has implications for the allocation of water resources and the course of regional development. Here we show that there is a broad consensus among climate models that this region will dry in the 21st century and that the transition to a more arid climate should already be under way. If these models are correct, the levels of aridity of the recent multiyear drought or the Dust Bowl and the 1950s droughts will become the new climatology of the American Southwest within a time frame of years to decades.

Calibration of the ARID robot

NASA Technical Reports Server (NTRS)

Doty, Keith L

1992-01-01

The author has formulated a new, general model for specifying the kinematic properties of serial manipulators. The new model kinematic parameters do not suffer discontinuities when nominally parallel adjacent axes deviate from exact parallelism. From this new theory the author develops a first-order, lumped-parameter, calibration-model for the ARID manipulator. Next, the author develops a calibration methodology for the ARID based on visual and acoustic sensing. A sensor platform, consisting of a camera and four sonars attached to the ARID end frame, performs calibration measurements. A calibration measurement consists of processing one visual frame of an accurately placed calibration image and recording four acoustic range measurements. A minimum of two measurement protocols determine the kinematics calibration-model of the ARID for a particular region: assuming the joint displacements are accurately measured, the calibration surface is planar, and the kinematic parameters do not vary rapidly in the region. No theoretical or practical limitations appear to contra-indicate the feasibility of the calibration method developed here.

A summary of methods for the collection and analysis of basic hydrologic data for arid regions

USGS Publications Warehouse

Rantz, S.E.; Eakin, T.E.

1971-01-01

This report summarizes and discusses current methods of collecting and analyzing the data required for a study of the basic hydrology of arid regions. The fundamental principles behind these methods are no different than those that apply to studies of humid regions, but in arid regions the infrequent occurrence of precipitation, the great variability of the many hydrologic elements, and the inaccessibility of most basins usually make it economically infeasible to use conventional levels of instrumentation. Because of these economic considerations hydrologic studies in arid regions have been commonly of the reconnaissance type; the more costly detailed studies are generally restricted to experimental basins and to those basins that now have major economic significance. A thorough search of the literature and personal communication with workers in the field of arid-land hydrology provided the basis for this summary of methods used in both reconnaissance and detailed hydrologic studies. The conclusions reached from a consideration of previously reported methods are interspersed in this report where appropriate.

Projected and Observed Aridity and Climate Change in the East Coast of South India under RCP 4.5.

PubMed

Ramachandran, A; Praveen, Dhanya; Jaganathan, R; Palanivelu, K

2015-01-01

In the purview of global warming, the present study attempts to project changes in climate and quantify the changes in aridity of two coastal districts in south India under the RCP 4.5 trajectory. Projected climate change output generated by RegCM 4.4 model, pertaining to 14 grid points located within the study area, was analyzed and processed for this purpose. The meteorological parameters temperature and precipitations were used to create De Martonne Aridity Index, to assess the spatial distribution of aridity. The original index values ranged from 13.7 to 16.4 mm/°C, characterizing this area as a semidry climate. The outcome from the changed scenario analysis under RCP 4.5 showed that, during the end of the 21st century, the aridity may be increased more as the index values tend to reduce. The increasing trend in the drying phenomenon may be attributed to the rising of mean annual temperatures.

Projected and Observed Aridity and Climate Change in the East Coast of South India under RCP 4.5

PubMed Central

Ramachandran, A.; Praveen, Dhanya; Jaganathan, R.; Palanivelu, K.

2015-01-01

In the purview of global warming, the present study attempts to project changes in climate and quantify the changes in aridity of two coastal districts in south India under the RCP 4.5 trajectory. Projected climate change output generated by RegCM 4.4 model, pertaining to 14 grid points located within the study area, was analyzed and processed for this purpose. The meteorological parameters temperature and precipitations were used to create De Martonne Aridity Index, to assess the spatial distribution of aridity. The original index values ranged from 13.7 to 16.4 mm/°C, characterizing this area as a semidry climate. The outcome from the changed scenario analysis under RCP 4.5 showed that, during the end of the 21st century, the aridity may be increased more as the index values tend to reduce. The increasing trend in the drying phenomenon may be attributed to the rising of mean annual temperatures. PMID:26771002

Organic Matter and Water Addition Enhance Soil Respiration in an Arid Region

PubMed Central

Lai, Liming; Wang, Jianjian; Tian, Yuan; Zhao, Xuechun; Jiang, Lianhe; Chen, Xi; Gao, Yong; Wang, Shaoming; Zheng, Yuanrun

2013-01-01

Climate change is generally predicted to increase net primary production, which could lead to additional C input to soil. In arid central Asia, precipitation has increased and is predicted to increase further. To assess the combined effects of these changes on soil CO2 efflux in arid land, a two factorial manipulation experiment in the shrubland of an arid region in northwest China was conducted. The experiment used a nested design with fresh organic matter and water as the two controlled parameters. It was found that both fresh organic matter and water enhanced soil respiration, and there was a synergistic effect of these two treatments on soil respiration increase. Water addition not only enhanced soil C emission, but also regulated soil C sequestration by fresh organic matter addition. The results indicated that the soil CO2 flux of the shrubland is likely to increase with climate change, and precipitation played a dominant role in regulating soil C balance in the shrubland of an arid region. PMID:24204907

Bioactive components, antioxidant and DNA damage inhibitory activities of honeys from arid regions.

PubMed

Habib, Hosam M; Al Meqbali, Fatima T; Kamal, Hina; Souka, Usama D; Ibrahim, Wissam H

2014-06-15

Honey serves as a good source of natural antioxidants, which are effective in reducing the risk of occurrence of several diseases. This study was undertaken to address the limited knowledge regarding the polyphenolic content, antioxidant and DNA damage inhibitory activities of honeys produced in arid regions and compare them with well-recognized honeys from non-arid regions. Different types of honey were assessed for their contents of total phenolics, total flavonoids, and certain types of phenolic compounds. The antioxidant capacity of honey was evaluated by ferric-reducing/antioxidant power assay (FRAP), free radical-scavenging activity (DPPH), nitric oxide (NO) radical-scavenging assay, total antioxidant activity, and DNA damage. Results clearly showed significant differences among honeys with all the evaluated parameters. Results also showed that one or more types of honey from arid regions contained higher levels of phenolic compounds, free radical-scavenging activities, or DNA damage inhibitory activities compared with the evaluated honeys from non-arid regions. Copyright © 2013 Elsevier Ltd. All rights reserved.

[Effects of climate and grazing on the vegetation cover change in Xilinguole League of Inner Mongolia, North China].

PubMed

Wang, Hai-Mei; Li, Zheng-Hai; Wang, Zhen

2013-01-01

Based on the monthly temperature and precipitation data of 15 meteorological stations and the statistical data of livestock density in Xilinguole League in 1981-2007, and by using ArcGIS, this paper analyzed the spatial distribution of the climate aridity and livestock density in the League, and in combining with the ten-day data of the normalized difference vegetation index (NDVI) in 1981-2007, the driving factors of the vegetation cover change in the League were discussed. In the study period, there was a satisfactory linear regression relationship between the climate aridity and the vegetation coverage. The NDVI and the livestock density had a favorable binomial regression relationship. With the increase of NDVI, the livestock density increased first and decreased then. The vegetation coverage had a complex linear relationship with livestock density and climate aridity. The NDVI had a positive correlation with climate aridity, but a negative correlation with livestock density. Compared with livestock density, climate aridity had far greater effects on the NDVI.

Multi Seasonal and Diurnal Characterization of Sensible Heat Flux in an Arid Land Environment

NASA Astrophysics Data System (ADS)

Al-Mashharawi, S.; Aragon, B.; McCabe, M.

2017-12-01

In sparsely vegetated arid and semi-arid regions, the available energy is transformed primarily into sensible heat, with little to no energy partitioned into latent heat. The characterization of bare soil arid environments are rather poorly understood in the context of both local, regional and global energy budgets. Using data from a long-term surface layer scintillometer and co-located meteorological installation, we examine the diurnal and seasonal patterns of sensible heat flux and the net radiation to soil heat flux ratio. We do this over a bare desert soil located adjacent to an irrigated agricultural field in the central region of Saudi Arabia. The results of this exploratory analysis can be used to inform upon remote sensing techniques for surface flux estimation, to derive and monitor soil heat flux dynamics, estimate the heat transfer resistance and the thermal roughness length over bare soils, and to better inform efforts that model the advective effects that complicate the accurate representation of agricultural energy budgets in the arid zone.

Impact of Lupinus leucophyllous on the nitrogen budgets of semi-arid plant communities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hinds, W.T.; Hinds, N.R.

1982-10-01

In the semi-arid grassland on the Arid Lands Ecology Reserve on the Hanford Site in south-central Washington State, three legume flushes occurred in the past decade. Estimates of leguminous nitrogen in both native and disturbed vegetation after a flush showed that nitrogen in the legume (above-ground) doubled the amount of nitrogen associated with vascular plant tissues. 21 references, 2 tables.

Predicting the Future Impact of Droughts on Ungulate Populations in Arid and Semi-Arid Environments

PubMed Central

Duncan, Clare; Chauvenet, Aliénor L. M.; McRae, Louise M.; Pettorelli, Nathalie

2012-01-01

Droughts can have a severe impact on the dynamics of animal populations, particularly in semi-arid and arid environments where herbivore populations are strongly limited by resource availability. Increased drought intensity under projected climate change scenarios can be expected to reduce the viability of such populations, yet this impact has seldom been quantified. In this study, we aim to fill this gap and assess how the predicted worsening of droughts over the 21st century is likely to impact the population dynamics of twelve ungulate species occurring in arid and semi-arid habitats. Our results provide support to the hypotheses that more sedentary, grazing and mixed feeding species will be put at high risk from future increases in drought intensity, suggesting that management intervention under these conditions should be targeted towards species possessing these traits. Predictive population models for all sedentary, grazing or mixed feeding species in our study show that their probability of extinction dramatically increases under future emissions scenarios, and that this extinction risk is greater for smaller populations than larger ones. Our study highlights the importance of quantifying the current and future impacts of increasing extreme natural events on populations and species in order to improve our ability to mitigate predicted biodiversity loss under climate change. PMID:23284700

Increased water use efficiency does not prevent growth decline of Pinus canariensis in a semi-arid treeline ecotone in Tenerife, Canary Islands (Spain).

PubMed

Brito, Patricia; Grams, Thorsten E E; Matysssek, Rainer; Jimenez, Maria S; Gonzalez-Rodríguez, Agueda M; Oberhuber, Walter; Wieser, Gerhard

2016-09-01

Intrinsic water-use efficiency of Pinus canariensis (Sweet ex Spreng.) growing at a semi-arid treeline has increased during the past 37 years. Tree-ring width by contrast has declined, likely caused by reduced stomatal conductance due to increasing aridity. Rising atmospheric CO 2 concentration ( C a ) has been related to tree growth enhancement accompanied by increasing intrinsic water-use-efficiency (iWUE). Nevertheless, the extent of rising C a on long-term changes in iWUE and growth has remained poorly understood to date in Mediterranean treeline ecosystems. This study aimed to examine radial growth and physiological responses of P. canariensis in relation to rising C a and increasing aridity at treeline in Tenerife, Canary Islands, Spain. We evaluated temporal changes in secondary growth (tree-ring width; TRW) and tree ring stable C isotope signature for assessing iWUE from 1975 through 2011. Precipitation was the main factor controlling secondary growth. Over the last 36 years P. canariensis showed a decline in TRW at enhanced iWUE, likely caused by reduced stomatal conductance due to increasing aridity. Our results indicate that increasing aridity has overridden the potential CO 2 fertilization on tree growth of P. canariensis at its upper distribution limit.

Halophytes Energy Feedstocks: Back to Our Roots

NASA Technical Reports Server (NTRS)

Hendricks, Robert C.; Bushnell, Dennis M.

2008-01-01

Of the Earth s landmass, approx.43% is arid or semi-arid, and 97% of the Earth s water is seawater. Halophytes are salt-tolerant plants (micro and macro) that can prosper in seawater or brackish waters and are common feedstocks for fuel and food (fuel-food feedstocks) in depressed countries. Two types, broadly classed as coastal and desert, can be found in marshes, coastal planes, inland lakes, and deserts. Major arid or semi-arid halophyte agriculture problems include pumping and draining the required high volumes of irrigation water from sea or ocean sources. Also, not all arid or semi-arid lands are suitable for crops. Benefits of halophyte agriculture include freeing up arable land and freshwater resources, cleansing the environment, decontaminating soils, desalinating brackish waters, and carbon sequestration. Sea and ocean halophyte agriculture problems include storms, transport, and diffuse harvesting. Benefits include available nutrients, ample water, and Sun. Careful attention to details and use of saline agriculture fuel feedstocks are required to prevent anthropogenic disasters. It is shown that the potential for fuel-food feedstock halophyte production is high; based on test plot data, it could supply 421.4 Quad, or 94% of the 2004 world energy consumption and sequester carbon, with major impact on the Triangle of Conflicts.

Relationship Between Job Burnout and Neuroendocrine Indicators in Soldiers in the Xinjiang Arid Desert: A Cross-Sectional Study.

PubMed

Tao, Ning; Zhang, Jianjiang; Song, Zhixin; Tang, Jinhua; Liu, Jiwen

2015-12-01

The purpose of this study was to explore the relationship between job burnout and neuroendocrine indicators in soldiers living in a harsh environment. Three hundred soldiers stationed in the arid desert and 600 in an urban area were recruited. They filled in the Chinese Maslach Burnout Inventory questionnaire. One hundred soldiers were randomly selected from each group to measure their levels of noradrenaline, serotonin, heat shock protein (HSP)-70, adrenocorticotropic hormone, and serum cortisol. Job burnout was more common in soldiers from urban areas than those from rural areas. Job burnout was significantly higher among soldiers stationed in the arid desert than those in urban areas. For soldiers in the arid desert, the levels of HSP-70, serum cortisol, and adrenocorticotropic hormone were significantly higher than in soldiers in urban areas. Correlation analyses showed that the degree of job burnout was weakly negatively correlated with the level of HSP-70. Being an only child, HSP-70 levels, cortisol levels, and ACTH levels were independently associated with job burnout in soldiers stationed in the arid desert. A higher level of job burnout in soldiers stationed in arid desert and a corresponding change in neuroendocrine indicators indicated a correlation between occupational stress and neurotransmitters.

Dominance of climate warming effects on recent drying trends over wet monsoon regions

NASA Astrophysics Data System (ADS)

Park, Chang-Eui; Jeong, Su-Jong; Ho, Chang-Hoi; Park, Hoonyoung; Piao, Shilong; Kim, Jinwon; Feng, Song

2017-09-01

Understanding changes in background dryness over land is key information for adapting to climate change because of its critical socioeconomic consequences. However, causes of continental dryness changes remain uncertain because various climate parameters control dryness. Here, we verify dominant climate variables determining dryness trends over continental eastern Asia, which is characterized by diverse hydroclimate regimes ranging from arid to humid, by quantifying the relative effects of changes in precipitation, solar radiation, wind speed, surface air temperature, and relative humidity on trends in the aridity index based on observed data from 189 weather stations for the period of 1961-2010. Before the early 1980s (1961-1983), change in precipitation is a primary condition for determining aridity trends. In the later period (1984-2010), the dominant climate parameter for aridity trends varies according to the hydroclimate regime. Drying trends in arid regions are mostly explained by reduced precipitation. In contrast, the increase in potential evapotranspiration due to increased atmospheric water-holding capacity, a secondary impact of warming, works to increase aridity over the humid monsoon region despite an enhanced water supply and relatively less warming. Our results show significant drying effects of warming over the humid monsoon region in recent decades; this also supports the drying trends over warm and water-sufficient regions in future climate.

Increased water use efficiency does not prevent growth decline of Pinus canariensis in a semi-arid treeline ecotone in Tenerife, Canary Islands (Spain)

PubMed Central

Brito, Patricia; Grams, Thorsten E.E.; Matysssek, Rainer; Jimenez, Maria S.; Gonzalez-Rodríguez, Agueda M.; Oberhuber, Walter; Wieser, Gerhard

2016-01-01

Key message Intrinsic water-use efficiency of Pinus canariensis (Sweet ex Spreng.) growing at a semi-arid treeline has increased during the past 37 years. Tree-ring width by contrast has declined, likely caused by reduced stomatal conductance due to increasing aridity. Context Rising atmospheric CO2 concentration (Ca) has been related to tree growth enhancement accompanied by increasing intrinsic water-use-efficiency (iWUE). Nevertheless, the extent of rising Ca on long-term changes in iWUE and growth has remained poorly understood to date in Mediterranean treeline ecosystems. Aims This study aimed to examine radial growth and physiological responses of P. canariensis in relation to rising Ca and increasing aridity at treeline in Tenerife, Canary Islands, Spain. Methods We evaluated temporal changes in secondary growth (tree-ring width; TRW) and tree ring stable C isotope signature for assessing iWUE from 1975 through 2011. Results Precipitation was the main factor controlling secondary growth. Over the last 36 years P. canariensis showed a decline in TRW at enhanced iWUE, likely caused by reduced stomatal conductance due to increasing aridity. Conclusion Our results indicate that increasing aridity has overridden the potential CO2 fertilization on tree growth of P. canariensis at its upper distribution limit. PMID:27482149

Experimental landfill caps for semi-arid and arid climates.

PubMed

Blight, Geoffrey E; Fourie, Andries B

2005-04-01

The United States EPA Subtitle D municipal solid waste landfill requirements specify that the permeability of a cap to a landfill be no greater than the permeability of the underliner. In recent years the concept of the evapotranspirative (ET) cap has been developed in which the cap is designed to store all rain infiltration and re-evapotranspire it during dry weather. Concern at the long period required for landfilled municipal solid waste to decompose and stabilize in arid and semi-arid climates has led to an extension of the concept of the ET cap. With the infiltrate-stabilize-evapotranspire (ISE) cap, rain infiltration during wet weather is permitted to enter the underlying waste, thus accelerating the decomposition and stabilization process. Excess infiltration is then removed from both waste and cap by evaporation during dry weather. The paper describes the construction and operation of two sets of experimental ISE caps, one in a winter rainfall semi-arid climate, and the other in a summer rainfall semi-arid climate. Observation of the rainfall, soil evaporation and amount of water stored in the caps has allowed water balances to be constructed for caps of various thicknesses. These observations show that the ISE concept is viable. In the limit, when there is insufficient rainfall to infiltrate the waste, an ISE cap operates as an ET cap.

Amphibian and reptile biodiversity in the semi-arid region of the municipality of Nopala de Villagrán, Hidalgo, Mexico.

PubMed

Roth-Monzón, Andrea J; Mendoza-Hernández, Andrés Alberto; Flores-Villela, Oscar

2018-01-01

Current global changes are putting both biodiversity and the processes that depend on it at risk. This is especially true for semi-arid regions and the flagship groups that inhabit them, such as amphibians and reptiles. Semi-arid regions are often thought to have lower biodiversity and thus have been overlooked, resulting in the underestimation of their biological richness. Therefore, the aim of this study was to conduct an inventory of amphibians and reptiles in the semi-arid municipality of Nopala de Villagrán, Mexico, and analyze its biodiversity in relation to the seasons, vegetation and microhabitat. During a year of fieldwork, we found 24 species in the area, most of them of low abundance, and one of which was recorded for the first time for the state of Hidalgo. We documented five amphibian species and 19 reptile species. We also found that observed species richness was higher in the rainy season and in xeric scrub vegetation, although only the season differences were significant according to rarefaction curves. Our findings highlight the importance of seasonality and vegetation type for the species that inhabit this semi-arid region. This study broadens our understanding of the importance of semi-arid regions and, by extension, that of other areas with similar characteristics.

Runoff sensitivity to climate change in the Nile River Basin

NASA Astrophysics Data System (ADS)

Hasan, Emad; Tarhule, Aondover; Kirstetter, Pierre-Emmanuel; Clark, Race; Hong, Yang

2018-06-01

In data scarce basins, such as the Nile River Basin (NRB) in Africa, constraints related to data availability, quality, and access often complicate attempts to estimate runoff sensitivity using conventional methods. In this paper, we show that by integrating the concept of the aridity index (AI) (derived from the Budyko curve) and climate elasticity, we can obtain the first order response of the runoff sensitivity using minimal data input and modeling expertise or experience. The concept of runoff elasticity relies on the fact that the energy available for evapotranspiration plays a major role in determining whether the precipitation received within a drainage basin generates runoff. The approach does not account for human impacts on runoff modification and or diversions. By making use of freely available gauge-corrected satellite data for precipitation, temperature, runoff, and potential evapotranspiration, we derived the sensitivity indicator (β) to determine the runoff response to changes in precipitation and temperature for four climatic zones in the NRB, namely, tropical, subtropical, semiarid and arid zones. The proposed sensitivity indicator can be partitioned into different elasticity components i.e: precipitation (εp), potential evapotranspiration (εETp), temperature (εT) and the total elasticity (εtot) . These elasticities allow robust quantification of the runoff response to the potential changes in precipitation and temperature with a high degree of accuracy. Results indicate that the tropical zone is energy-constrained with low sensitivity, (β < 1.0) , implying that input precipitation exceeds the amounts that can be evaporated given the available energy. The subtropical zone is subdivided into two distinct regions, the lowland (Machar and Sudd marshes), and the highland area (Blue Nile Basin), where each area has a unique sensitivity. The lowland area has high sensitivity, (β > 1.0) . The subtropical-highland zone moves between energy-limited to water-limited conditions during periods of wet and dry spells with varying sensitivity. The semiarid and arid zones are water limited, with high sensitivity, (β > 1.0) . The calculated runoff elasticities show that a 10% decrease in precipitation leads to a decrease in runoff of between 19% in the tropical zone and 30% in the arid zones. On the other hand, a 10% precipitation increase leads to a runoff increase of 14% in the tropical zone and 22% in the arid zone. The estimated runoff changes are consistent with the result obtained using other methods. Thus, the elasticity approach combines data parsimony and analytical simplicity to produce results that are practically useful for most purposes while facilitating communication with stakeholders with different levels of scientific knowledge. More research is needed to extend the application of the method to incorporate the effects of human activities, and land use change.

Inland Aridification of NW China Since the Late Middle Eocene: Stable Isotope Evidence from Western Qaidam Basin

NASA Astrophysics Data System (ADS)

Li, L.; Garzione, C. N.; Pullen, A. T.; Chang, H.; Molnar, P. H.

2014-12-01

Cenozoic paleoclimate reconstructions of China, based on pollens, fossils and sedimentary deposits, show a change from planetary aridity to inland aridity of NW China by the early Miocene. However, the initiation of this paleoclimate transition is not well-documented and might be much earlier. The surface uplift of the Tibetan Plateau, the retreat of the Para-Tethys sea, and global cooling have all been suggested to influence the establishment of this inland aridity, although their relative significance remains obscure. This paper presents a stable isotope study of a 4435 m long sedimentary section from the western Qaidam Basin, northern Tibetan Plateau, that spans from the late middle Eocene to late Miocene. The lowermost and uppermost parts of the section are dominated by fluvial and alluvial fan deposits, while the majority of the middle of the section represents palustrine, lower fan delta and marginal to shallow lacustrine fine-grained sediments intercalated with coarse sandstone and conglomerate. Our isotope data show sporadic aridity events in the late middle Eocene to early Oligocene, which might mark the transition from planetary aridity to, or the initiation of, inland aridity in NW China, due to the retreat of the Para-Tethys sea, a process that might be significantly influenced by the early topographic growth of the south-central Tibetan Plateau. A negative shift in oxygen isotope values around 19 Ma is also in accordance with other geological evidence suggesting the Oligocene-early Miocene growth of the Kunlun mountains south of the Qaidam basin. Later intensification of aridity occurred at ~12 Ma that corresponds with a regional climate change event, which we attribute to the upward and outward growth of the northern Tibetan Plateau. The final establishment of extreme inland aridity that is comparable to present day was most likely established at ~3.1-2.6 Ma in the Qaidam basin, and therefore global cooling and northern hemisphere glaciation is a major candidate for the cause.

Assessment of Plant Functional Types in Tropical Arid and Semi-Arid Ecosystems of India Using Remote Sensing Data and GIS

NASA Astrophysics Data System (ADS)

Sudhakar Reddy, C.; Krishna, P. Hari; Murthy, M. S. R.

2011-09-01

Tropical ecosystems undergo changes caused by season, climate or multiple anthropogenic impacts. Such changes may cause gradual or rapid shifts from one state to another. There has been a focus on functional classifications of plants to find tools for monitoring and assessing species status in changing environments. It has been recognised that plant biological characteristics can be related to their response to predominant environmental factors and interactions between other organisms. These findings have resulted in a search for plant functional types (PFTs) that are user-defined groups of species with similar response to environmental resources and disturbance associated to common biological traits. Now, identification of plant functional types is priority area in the climate change research. Satellite Earth observation data is an important tool in providing considerable information on extracting PFT information at global and regional levels. From the modelling perspective, some of the current needs are the refinement of processes that govern community assembly, such as natural and anthropogenic disturbances. PFTs used in large-scale models are insufficient to represent the diversity of responses in natural plant communities. The currently available MODIS PFT map was generated by re-labeling the IGBP land cover type classes. However, the error magnitudes of the MODIS PFT product and their spatial and temporal distributions have not been fully characterized. Remotely sensed derived information of the phenology, community composition and vegetation structure are the key inputs to integrate with the variability in precipitation and temperature to map the spatial distribution of Plant functional types. PFTs allows accurate representation of the land surface by separately specifying the composition and structure of PFTs within a grid cell. Very little research efforts are discernible in India that explicitly address the PFTs. In the present study five natural vegetation systems were studied along arid, semi-arid and sub-humid regions of Indian Desert and Aravallis of Rajasthan, India, with a distance of 600 km. The annual precipitation decreases from as high as 1600 mm in the south to 700 mm in the north-east and 100 mm in the west. The study is based on the integrated approach of remote sensing, GIS, and phytosociology. In the step 1, vegetation type map was prepared using multi-season IRS P6 LISS III data. Screening of plant traits was done based on field observations and literature. Phytosociological data pertains to 500 sample plots was used to identify plant functional traits of 900 species at morphological level. The vegetation classification scheme at regional level identified thorn forest, dry deciduous forest, broad leaved forest, woodland, shrubland and grasslands. Five plant traits selected in the study were significant for tropical environments. Attributes such as leaf size, leaf texture, spinescence, stem diameter and bark consistency were categorized systematically. Ordination analysis was carried out across the environmental gradient. Plant functional traits were measured on 20 individuals per species at each site. Environmental information was integrated to identify plant trait response. The spatial trends in PFTs were analysed and compared across the vegetation types, along the gradient of land surface temperature, climate, elevation and time integrated NDVI. Results established the occurrence of recurrent patterns of association among selected plant traits. Functional response groups were identified by summarizing results and relating them to individual species. Finally phytoclimatic map was prepared to represent spatial distribution of PFTs. The species with of functional traits of representing microphylls, sclerophyll, rough bark, spinescence and therophyte are demarcated as drought tolerant traits. Drought Intolerant PFTs are represented by macrophyll, malacophyll, smooth Bark, non spinescent stems and leaves. Biological spectrum of Desert national park, Jaisalmer and and Ajmer represents therophytic climate (below 600mm rainfall) while Sariska and Mt. Abu are of therophanerophytic (>600mm rainfall). The higher proportion of microphylls and therophytes are distributed within tropical arid environments. The dominance of the drought tolerant PFTs increased towards west while the dominance of the drought intolerant PFTs increased in southern and northern parts of Rajasthan. Detecting the change of spatial characteristics of plant species under precipitation gradients would be helpful to study species dynamics in a large region under environmental gradient. On the basis of easily-measured plant traits and phytosociological surveys, the present approach summarized the complexity of tropical vegetation into a relatively few PFTs. The present study open up new possibilities for understanding plant trait and environment relationship and developing PFT classification in tropical regions.

Analysis & Tools to Spur Increased Deployment of “Waste Heat” Rejection/Recycling Hybrid Ground-source Heat Pump Systems in Hot, Arid or Semiarid Climates Like Texas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masada, Glenn; Moon, Tess

2013-09-01

This project team analyzed supplemental heat rejection/recovery (SHR) devices or systems that could be used in hybrid ground source heat pump (HGHP) systems located in arid or semi-arid regions in southwestern U.S. Identification of effective SHR solutions would enhance the deployment of ground source heat pumps (GHP) in these regions. In a parallel effort, the team developed integrated GHP models that coupled the building load, heat pump, and ground loop subsystems and which could be applied to residential and commercial office buildings. Then GHP and HGHP performances could be compared in terms of operational performance and life-cycle costs. Several potentialmore » SHR devices were analyzed by applying two strategies: 1) to remove heat directly from the water in the ground loop before it enters the ground and 2) to remove heat in the refrigerant loop of the vapor compression cycle (VCC) of the heat pump so less heat is transferred to the water loop at the condenser of the VCC. Cooling towers, adsorption coolers, and thermoelectric liquid coolers were included in strategy 1, and expanded desuperheaters, thermosyphons, and an optimized VCC were included in strategy 2. Of all SHR devices analyzed, only the cooling tower provided a cost-effective performance enhancement. For the integrated GHP model, the project team selected the building load model HAMBASE and its powerful computational Simulink/MatLab platform, empirical performance map models of the heat pumps based upon manufacturers’ performance data, and a ground loop model developed by Oklahoma State University and rewritten for this project in Simulink/MatLab. The design process used GLHEPRO, also from Oklahoma State University, to size the borehole fields. The building load and ground loop models were compared with simulations from eQuest, ASHRAE 140-2008 standards, EnergyPlus, and GLHEPRO and were found to predict those subsystems’ performance well. The integrated GHP model was applied to a 195m 2 (2100ft 2) residential building and a 4,982m 2 (53,628ft 2) three-story commercial office building, and it ran 10-15 year simulations. The integrated GHP model and its Simulink platform provided residential data, ranging from seconds to years, and commercial office building data, ranging from minutes to years. A cooling tower model was coupled to the base case integrated GHP model for the residential building and the resulting HGHP system provided a cost-effective solution for the Austin, TX location. Simulations for both the residential and commercial building models were run with varying degrees of SHR (device/system not identified) and the results were found to significantly decrease installation costs, increase heat pump efficiency (lower entering water temperature), and prolong the lifetime of the borehole field. Lifetime cycle costs were estimated from the simulation results. Sensitivity studies on system operating performance and lifetime costs were performed on design parameters, such as construction materials, borehole length, borehole configuration and spacing, grout conductivity, and effects of SHR. While some of the results are intuitive, these studies provided quantitative estimates of improved performance and cost. One of the most important results of this sensitivity study is that overall system performance is very sensitive to these design parameters and that modeling and simulation are essential tools to design cost-effective systems.« less

Global patterns and environmental controls of perchlorate and nitrate co-occurrence in arid and semi-arid environments

NASA Astrophysics Data System (ADS)

Jackson, W. Andrew; Böhlke, J. K.; Andraski, Brian J.; Fahlquist, Lynne; Bexfield, Laura; Eckardt, Frank D.; Gates, John B.; Davila, Alfonso F.; McKay, Christopher P.; Rao, Balaji; Sevanthi, Ritesh; Rajagopalan, Srinath; Estrada, Nubia; Sturchio, Neil; Hatzinger, Paul B.; Anderson, Todd A.; Orris, Greta; Betancourt, Julio; Stonestrom, David; Latorre, Claudio; Li, Yanhe; Harvey, Gregory J.

2015-09-01

Natural perchlorate (ClO4-) is of increasing interest due to its wide-spread occurrence on Earth and Mars, yet little information exists on the relative abundance of ClO4- compared to other major anions, its stability, or long-term variations in production that may impact the observed distributions. Our objectives were to evaluate the occurrence and fate of ClO4- in groundwater and soils/caliche in arid and semi-arid environments (southwestern United States, southern Africa, United Arab Emirates, China, Antarctica, and Chile) and the relationship of ClO4- to the more well-studied atmospherically deposited anions NO3- and Cl- as a means to understand the prevalent processes that affect the accumulation of these species over various time scales. ClO4- is globally distributed in soil and groundwater in arid and semi-arid regions on Earth at concentrations ranging from 10-1 to 106 μg/kg. Generally, the ClO4- concentration in these regions increases with aridity index, but also depends on the duration of arid conditions. In many arid and semi-arid areas, NO3- and ClO4- co-occur at molar ratios (NO3-/ClO4-) that vary between ∼104 and 105. We hypothesize that atmospheric deposition ratios are largely preserved in hyper-arid areas that support little or no biological activity (e.g. plants or bacteria), but can be altered in areas with more active biological processes including N2 fixation, N mineralization, nitrification, denitrification, and microbial ClO4- reduction, as indicated in part by NO3- isotope data. In contrast, much larger ranges of Cl-/ClO4- and Cl-/NO3- ratios indicate Cl- varies independently from both ClO4- and NO3-. The general lack of correlation between Cl- and ClO4- or NO3- implies that Cl- is not a good indicator of co-deposition and should be used with care when interpreting oxyanion cycling in arid systems. The Atacama Desert appears to be unique compared to all other terrestrial locations having a NO3-/ClO4- molar ratio ∼103. The relative enrichment in ClO4- compared to Cl- or NO3- and unique isotopic composition of Atacama ClO4- may reflect either additional in-situ production mechanism(s) or higher relative atmospheric production rates in that specific region or in the geological past. Elevated concentrations of ClO4- reported on the surface of Mars, and its enrichment with respect to Cl- and NO3-, could reveal important clues regarding the climatic, hydrologic, and potentially biologic evolution of that planet. Given the highly conserved ratio of NO3-/ClO4- in non-biologically active areas on Earth, it may be possible to use alterations of this ratio as a biomarker on Mars and for interpreting major anion cycles and processes on both Mars and Earth, particularly with respect to the less-conserved NO3- pool terrestrially.

a System Dynamics Approach for Looking at the Human and Environmental Interactions of Community-Based Irrigation Systems in New Mexico

NASA Astrophysics Data System (ADS)

Ochoa, C. G.; Tidwell, V. C.

2012-12-01

In the arid southwestern United States community water management systems have adapted to cope with climate variability and with socio-cultural and economic changes that have occurred since the establishment of these systems more than 300 years ago. In New Mexico, the community-based irrigation systems were established by Spanish settlers and have endured climate variability in the form of low levels of precipitation and have prevailed over important socio-political changes including the transfer of territory between Spain and Mexico, and between Mexico and the United States. Because of their inherent nature of integrating land and water use with society involvement these community-based systems have multiple and complex economic, ecological, and cultural interactions. Current urban population growth and more variable climate conditions are adding pressure to the survival of these systems. We are conducting a multi-disciplinary research project that focuses on characterizing these intrinsically complex human and natural interactions in three community-based irrigation systems in northern New Mexico. We are using a system dynamics approach to integrate different hydrological, ecological, socio-cultural and economic aspects of these three irrigation systems. Coupled with intensive field data collection, we are building a system dynamics model that will enable us to simulate important linkages and interactions between environmental and human elements occurring in each of these water management systems. We will test different climate variability and population growth scenarios and the expectation is that we will be able to identify critical tipping points of these systems. Results from this model can be used to inform policy recommendations relevant to the environment and to urban and agricultural land use planning in the arid southwestern United States.

Technology Catalogue. First edition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1994-02-01

The Department of Energy`s Office of Environmental Restoration and Waste Management (EM) is responsible for remediating its contaminated sites and managing its waste inventory in a safe and efficient manner. EM`s Office of Technology Development (OTD) supports applied research and demonstration efforts to develop and transfer innovative, cost-effective technologies to its site clean-up and waste management programs within EM`s Office of Environmental Restoration and Office of Waste Management. The purpose of the Technology Catalogue is to provide performance data on OTD-developed technologies to scientists and engineers assessing and recommending technical solutions within the Department`s clean-up and waste management programs, asmore » well as to industry, other federal and state agencies, and the academic community. OTD`s applied research and demonstration activities are conducted in programs referred to as Integrated Demonstrations (IDs) and Integrated Programs (IPs). The IDs test and evaluate.systems, consisting of coupled technologies, at specific sites to address generic problems, such as the sensing, treatment, and disposal of buried waste containers. The IPs support applied research activities in specific applications areas, such as in situ remediation, efficient separations processes, and site characterization. The Technology Catalogue is a means for communicating the status. of the development of these innovative technologies. The FY93 Technology Catalogue features technologies successfully demonstrated in the field through IDs and sufficiently mature to be used in the near-term. Technologies from the following IDs are featured in the FY93 Technology Catalogue: Buried Waste ID (Idaho National Engineering Laboratory, Idaho); Mixed Waste Landfill ID (Sandia National Laboratories, New Mexico); Underground Storage Tank ID (Hanford, Washington); Volatile organic compound (VOC) Arid ID (Richland, Washington); and VOC Non-Arid ID (Savannah River Site, South Carolina).« less

The role of the water tankers market in water stressed semi-arid urban areas:Implications on water quality and economic burden.

PubMed

Constantine, Kinda; Massoud, May; Alameddine, Ibrahim; El-Fadel, Mutasem

2017-03-01

Population growth and development are associated with increased water demand that often exceeds the capacity of existing resources, resulting in water shortages, particularly in urban areas, where more than 60% of the world's population resides. In many developing communities, shortages often force households to depend on water tankers amongst other potential sources for the delivery of water for domestic and/or potable use. While water tankers have become an integral part of the water supply system in many countries, the sector is often unregulated and operates with little governmental supervision. Users are invariably unaware of the origin or the quality of purchased water. In an effort to better assess this sector, a field survey of water vending wells and tankers coupled with a water quality sampling and analysis program was implemented in a pilot semi-arid urban area (Beirut, Lebanon) to shed light on the environmental and socio-economic impacts of the water tanker sector. Total dissolved solids (TDS), chloride (Cl - ), and microbial loads exceeded drinking water quality standards. While TDS and Cl - levels were mostly due to saltwater intrusion in coastal wells, tankers were found to be a significant source of total coliforms. Delivered water costs varied depending on the tanker size, the quality of the distributed water, and pre-treatment used, with a markup of nearly 8-24 folds of the public water supply and an equivalent economic burden of 16% of the average household income excluding environmental externalities of water quality. The study concludes with a management framework towards consumer protection under integrated supply and demand side measures. Copyright © 2016 Elsevier Ltd. All rights reserved.

Source of humidity in the terrestrial water cycle over the forested monsoon arid of Sahel; changes in the water recycle and atmospheric instability

NASA Astrophysics Data System (ADS)

Yosef, G.; Avissar, R.; Walko, R. L.; Yakir, D.

2017-12-01

Land-cover change from low-level shrubs to forest over semi-arid monsoon regions such as the Sahel, can significantly influence the surface energy budget and, in turn, the local atmospheric circulation. These regions, influenced at the summer by the monsoon rain following the migration of the tropical convergence zones (ITCZ). And low-level easterly jet that acts as a barrier to the penetration of the precipitation into the semi arid areas. In this study we follow-up first the results of large-scale afforestation numerical experiment in the Sahel that changes the local and regional atmospheric circulation and, consequently, increasing of precipitation. We aim for explicitly investigation of the change in the sources and pathways of humidity in the terrestrial water cycle over the Sahel as result afforestation. The GCM OLAM was used to performing simulations of afforestation scenarios in the Sahel. The area (Sahel 2.6 E6 km2) was afforested with a mature pine forest, using the extensive data form the long-term semi-arid Yatir forest in Israel as a reference forest for surface parameterization. The regional effect of the afforestation was analyzed using the following parameters; the index of water recycling (WR), which refers to the contribution of local ET fluxes to precipitation; the Moist Static Energy (MSE), is the sum of the potential, inertial and latent energy; and the vertical motion. The result shows increases of the WR in the south of the afforested area and north of the footprint, mainly as consequences of increasing in the vertical integrated moist flux convergence (MFC). Explaining this mechanism in terms of MSE shows that although the forest area become cooler and stabilizes the atmospheric column, its shift and weaken the African Easterly Jet enable the penetration of additional humidity to increase the MFC. On the other hand positive MSE observed over the northern footprint area mainly as a results of increasing the leant energy (e.g. humidity). Over all the result shows a self-sustainable system, where water is recharged to the atmosphere through ET, supported by the convergence process, as can be seen over the west part of the Sahel. As a consequence the forest system is not reliant on external water alone and also uses recycled water from its own ET to increase precipitation.

A future climate assessment on the quality and quantity of CrVI contaminated groundwater in the eastern Mediterranean

NASA Astrophysics Data System (ADS)

Hatzaki, M.; Argyraki, A.; Gkiouleka, I.; Paternoster, M.; Hatipoglu Bagci, Z.; Shammout, M.; Moraetis, D.; Dermatas, D.; Christou, A.

2017-12-01

The shortage of water and the water quality problems in Mediterranean countries appear more severe under climate change due to the intensive agricultural activities and the urban and industrial development that require reforms in the water policy approach. The ERANETMED CrITERIA project aims to assist water management organizations and water users in decision making when coping with water scarcity, climate extremes and contaminated water. Case areas of Mediterranean countries (Italy, Greece, Turkey, Cyprus, Jordan) with Cr(VI) contaminated waters are used as an example of a specific water pressure problem that has to be tackled through integrated water resources management. Moreover, Oman represents the arid-end member in identifying the different pathways of Cr(VI) contamination in surface and groundwater due to arid conditions. Thus, areas of similar geology can be used as analogs of areas passing from semi-arid to arid conditions. From a climate change perspective, it is important to investigate the impacts of changing precipitation patterns and, thus, assess the vulnerability of the aquifers. Thus, a high spatial resolution analysis is performed with observational data and climate model simulations on several time-scales drought and extreme precipitation, providing a concise picture of drought and flooding events for the present and the future climate. We use CORDEX experiment simulations under RCPs 4.5 and 8.5, further downscaled over the case study areas providing high spatial resolution information. The case studies inter-comparison stresses the diverse needs on water management along the Mediterranean and at the same time identifies common messages related to the future changes on water resources. RCP 4.5 shows a mild decrease in precipitation that becomes more severe towards the end of the century, though under the RCP 8.5 intense decrease is explicit in most timescales. The significant increase of precipitation variability and short and long-term drought are likely to affect freshwater systems and water quality by intensifying surface runoff, aiding in the erosion of ophiolithic occurrences present in the studied areas, elevating and even inflicting changes in the groundwater table. Acknowledgment: The ERANETMED CrITERIA project (T3ERA-00004) is co-funded by Greece, the Scientific and Technological Research Council of Turkey-TÜBİTAK (Project No 115Y844) and the European Union.

Does GPM-based multi-satellite precipitation enhance rainfall estimates over Pakistan and Bolivia arid regions?

NASA Astrophysics Data System (ADS)

Hussain, Y.; Satgé, F.; Bonnet, M. P.; Pillco, R.; Molina, J.; Timouk, F.; Roig, H.; Martinez-Carvajal, H., Sr.; Gulraiz, A.

2016-12-01

Arid regions are sensitive to rainfall variations which are expressed in the form of flooding and droughts. Unfortunately, those regions are poorly monitored and high quality rainfall estimates are still needed. The Global Precipitation Measurement (GPM) mission released two new satellite rainfall products named Integrated Multisatellite Retrievals GPM (IMERG) and Global Satellite Mapping of Precipitation version 6 (GSMaP-v6) bringing the possibility of accurate rainfall monitoring over these countries. This study assessed both products at monthly scale over Pakistan considering dry and wet season over the 4 main climatic zones from 2014 to 2016. With similar climatic conditions, the Altiplano region of Bolivia is considered to quantify the influence of big lakes (Titicaca and Poopó) in rainfall estimates. For comparison, the widely used TRMM-Multisatellite Precipitation Analysis 3B43 (TMPA-3B43) version 7 is also involved in the analysis to observe the potential enhancement in rainfall estimate brought by GPM products. Rainfall estimates derived from 110 rain-gauges are used as reference to compare IMERG, GSMaP-v6 and TMPA-3B43 at the 0.1° and 0.25° spatial resolution. Over both regions, IMERG and GSMaP-v6 capture the spatial pattern of precipitation as well as TMPA-3B43. All products tend to over estimates rainfall over very arid regions. This feature is even more marked during dry season. However, during this season, both reference and estimated rainfall remain very low and do not impact seasonal water budget computation. On a general way, IMERG slightly outperforms TMPA-3B43 and GSMaP-v6 which provides the less accurate rainfall estimate. The TMPA-3B43 rainfall underestimation previously found over Lake Titicaca is still observed in IMERG estimates. However, GSMaP-v6 considerably decreases the underestimation providing the most accurate rainfall estimate over the lake. MOD11C3 Land Surface Temperature (LST) and ASTER Global Emissivity Dataset reveal strong LST and Emissivity anomaly over the lake in comparison with surrounding lands. These anomalies should explain rainfall underestimations tendency over this lake. LST and Emissivity of lake Poopó are closest to surrounding land and the slight observed rainfall overestimation appears to be related to the very arid context of the region.

An ethnobotanical survey of medicinal and edible plants of Yalo Woreda in Afar regional state, Ethiopia.

PubMed

Teklehaymanot, Tilahun

2017-07-05

The Afar people inhabit the sub-arid and arid part of Ethiopia. Recurrent drought and invasive encroaching plants are taking out plants that have cultural importance, and threaten the biodiversity and the associated traditional knowledge. Thus, the aim of the current study is to conduct an ethnobotanical survey and document medicinal and edible plants in Yalo Woreda in Afar regional state. A cross-sectional ethnobotanical study was carried out in eight kebeles of Yalo Woreda from October 2015 to December 2016. One hundred sixty informants were selected using purposive sampling. The data on diseases, medicinal and edible plants were collected using semi-structure interview and group discussion. The statistical methods, informant consensus factor, fidelity level, and preference ranking were conducted to analyze the data. One hundred and six plants were reported; gender and age differences had implication on the number of plants reported by informants. The knowledge of medicinal plants among informants of each kebele was not different (p < 0.5) and was not associated in particular with the religious establishment in the kebeles (informant*kebeles, Eta square = 0.19). Family Fabaceae was the major plant species, and shrubs (44%) were dominant plants reported. Leaf (52.94%) and oral (68%) were primary plant part used for remedy preparation and route of application, respectively. The plants with low fidelity values Indigofera articulata (0.25), Cadaba farinosa (0.22), Cadaba rotundifolia (0.19), and Acalypha fruticosa (0.15) were used to treat the category of diseases with high informant consensus value (0.69). Sixteen edible plants were identified that were consumed during wet and dry seasons. Balanites aegyptiaca, Balanites rotundifolia, and Dobera glabra were 'famine food' that were collected and stored for years. People in Yalo Woreda are more dependent on natural resources of the area for their livelihood. The threat of climatic change and encroaching invasive plants on medicinal and edible plants affects the traditional use of plants in the Yalo Woreda. The conservation of the plants in the home garden and natural habitat and integration of edible plants into agroforestry development programs in sub-arid and arid regions has to be encouraged to conserve plants of medical and economic importance.

Influences on the stable oxygen and carbon isotopes in gerbillid rodent teeth in semi-arid and arid environments: Implications for past climate and environmental reconstruction

NASA Astrophysics Data System (ADS)

Jeffrey, Amy; Denys, Christiane; Stoetzel, Emmanuelle; Lee-Thorp, Julia A.

2015-10-01

The stable isotope composition of small mammal tissues has the potential to provide detailed information about terrestrial palaeoclimate and environments, because their remains are abundant in palaeontological and archaeological sites, and they have restricted home ranges. Applications to the Quaternary record, however, have been sparse and limited by an acute lack of understanding of small mammal isotope ecology, particularly in arid and semi-arid environments. Here we document the oxygen and carbon isotope composition of Gerbillinae (gerbil) tooth apatite across a rainfall gradient in northwestern Africa, in order to test the relative influences of the 18O/16O in precipitation or moisture availability on gerbil teeth values, the sensitivity of tooth apatite 13C/12C to plant responses to moisture availability, and the influence of developmental period on the isotopic composition of gerbil molars and incisors. The results show that the isotopic composition of molars and incisors from the same individuals differs consistent with the different temporal periods reflected by the teeth; molar teeth are permanently rooted and form around the time of birth, whereas incisors grow continuously. The results indicate that tooth choice is an important consideration for applications as proxy Quaternary records, but also highlights a new potential means to distinguish seasonal contexts. The oxygen isotope composition of gerbil tooth apatite is strongly correlated with mean annual precipitation (MAP) below 600 mm, but above 600 mm the teeth reflect the oxygen isotope composition of local meteoric water instead. Predictably, the carbon isotope composition of the gerbil teeth reflected C3 and C4 dietary inputs, however arid and mesic sites could not be distinguished because of the high variability displayed in the carbon isotope composition of the teeth due to the microhabitat and short temporal period reflected by the gerbil. We show that the oxygen isotope composition of small mammal teeth strongly reflects moisture availability in semi-arid and arid environments and would provide an excellent record of palaeo-aridity in a terrestrial setting. The results illustrate that an understanding of an animal's physiology is essential for interpreting the animal's isotopic responses to external contexts, especially in arid zones.

Assessment of short- and long-term memory in trends of major climatic variables over Iran: 1966-2015

NASA Astrophysics Data System (ADS)

Mianabadi, Ameneh; Shirazi, Pooya; Ghahraman, Bijan; Coenders-Gerrits, A. M. J.; Alizadeh, Amin; Davary, Kamran

2018-02-01

In arid and semi-arid regions, water scarcity is the crucial issue for crop production. Identifying the spatial and temporal trends in aridity, especially during the crop-growing season, is important for farmers to manage their agricultural practices. This will become especially relevant when considering climate change projections. To reliably determine the actual trends, the influence of short- and long-term memory should be removed from the trend analysis. The objective of this study is to investigate the effect of short- and long-term memory on estimates of trends in two aridity indicators—the inverted De Martonne (ϕ IDM ) and Budyko (ϕ B ) indices. The analysis is done using precipitation and temperature data over Iran for a 50-year period (1966-2015) at three temporal scales: annual, wheat-growing season (October-June), and maize-growing season (May-November). For this purpose, the original and the modified Mann-Kendall tests (i.e., modified by three methods of trend free pre-whitening (TFPT), effective sample size (ESS), and long-term persistence (LTP)) are used to investigate the temporal trends in aridity indices, precipitation, and temperature by taking into account the effect of short- and long-term memory. Precipitation and temperature data were provided by the Islamic Republic of Iran Meteorological Organization (IRIMO). The temporal trend analysis showed that aridity increased from 1966 to 2015 at the annual and wheat-growing season scales, which is due to a decreasing trend in precipitation and an increasing trend in mean temperature at these two timescales. The trend in aridity indices was decreasing in the maize-growing season, since precipitation has an increasing trend for most parts of Iran in that season. The increasing trend in aridity indices is significant in Western Iran, which can be related to the significantly more negative trend in precipitation in the West. This increasing trend in aridity could result in an increasing crop water requirement and a significant reduction in the crop production and water use efficiency. Furthermore, the modified Mann-Kendall tests indicated that unlike temperature series, precipitation, ϕ IDM , and ϕ B series are not affected by short- and long-term memory. Our results can help decision makers and water resource managers to adopt appropriate policy strategies for sustainable development in the field of irrigated agriculture and water resources management.

ARID5B, CEBPE and PIP4K2A Germline Genetic Polymorphisms and Risk of Childhood Acute Lymphoblastic Leukemia in Mexican Patients: A MIGICCL Study.

PubMed

Bekker-Méndez, Vilma Carolina; Núñez-Enríquez, Juan Carlos; Torres Escalante, José Luis; Alvarez-Olmos, Enrique; González-Montalvoc, Pablo Miguel; Jiménez-Hernández, Elva; Sansón, Aurora Medina; Leal, Yelda A; Ramos-Cervantes, María Teresa; Guerra-Castillo, Francisco Xavier; Ortiz-Maganda, Mónica Patricia; Flores-Lujano, Janet; Pérez-Saldivar, Maria Luisa; Velazquez-Aviña, Martha Margarita; Bolea-Murga, Victoria; Torres-Nava, José Refugio; Amador-Sanchez, Raquel; Solis-Labastida, Karina Anastacia; Rámirez-Bello, Julian; Fragoso, José Manuel; Mejía-Aranguré, Juan Manuel

2016-11-01

Childhood acute lymphoblastic leukemia (ALL) is the leading cause of childhood cancer-related deaths worldwide. Multiples studies have shown that ALL seems to be originated by an interaction between environmental and genetic susceptibility factors. The ARID5B polymorphisms are among the most reproducible ALL associated-risk alleles in different populations. The aim of the present study was to examine the contribution of ARID5B, CEBPE, and PIP4K2 risk alleles for the development of ALL in children from Mexico City and Yucatan, Mexico. A study was conducted with a total of 761 unrelated subjects. Two hundred eighty five ALL cases (111 from Yucatan and 174 from Mexico City) and 476 healthy subjects. Genotyping included the rs7088318 (PIP4K2A), rs10821936 (ARID5B), rs7089424 (ARID5B) and rs2239633 (CEBPE) polymorphisms. Associations between ALL and rs10821936 and rs7089424 ARID5B SNPs were found (OR = 1.9, 95% CI (1.5-2.4) and OR = 2.0, 95% CI (1.6-2.5), respectively). Moreover, a higher risk was observed in the homozygous risk genotypes of carriers from Mexico City (OR = 3.1, 95% CI (2.0-4.9) and OR 3.1, CI 95% (2.0-4.8), respectively). Otherwise, the rs7088318 (PIP4K2A) and rs2239633 (CEBPE) polymorphisms were not associated with ALL risk. Our analysis suggests that ARID5B confers risk for childhood ALL in a Mexican population. Copyright © 2016 IMSS. Published by Elsevier Inc. All rights reserved.

Actinobacteria from Arid and Desert Habitats: Diversity and Biological Activity

PubMed Central

Mohammadipanah, Fatemeh; Wink, Joachim

2016-01-01

The lack of new antibiotics in the pharmaceutical pipeline guides more and more researchers to leave the classical isolation procedures and to look in special niches and ecosystems. Bioprospecting of extremophilic Actinobacteria through mining untapped strains and avoiding resiolation of known biomolecules is among the most promising strategies for this purpose. With this approach, members of acidtolerant, alkalitolerant, psychrotolerant, thermotolerant, halotolerant and xerotolerant Actinobacteria have been obtained from respective habitats. Among these, little survey exists on the diversity of Actinobacteria in arid areas, which are often adapted to relatively high temperatures, salt concentrations, and radiation. Therefore, arid and desert habitats are special ecosystems which can be recruited for the isolation of uncommon Actinobacteria with new metabolic capability. At the time of this writing, members of Streptomyces, Micromonospora, Saccharothrix, Streptosporangium, Cellulomonas, Amycolatopsis, Geodermatophilus, Lechevalieria, Nocardia, and Actinomadura are reported from arid habitats. However, metagenomic data present dominant members of the communities in desiccating condition of areas with limited water availability that are not yet isolated. Furthermore, significant diverse types of polyketide synthase (PKS) and non-ribosomal peptide synthetase (NRPS) genes are detected in xerophilic and xerotolerant Actinobacteria and some bioactive compounds are reported from them. Rather than pharmaceutically active metabolites, molecules with protection activity against drying such as Ectoin and Hydroxyectoin with potential application in industry and agriculture have also been identified from xerophilic Actinobacteria. In addition, numerous biologically active small molecules are expected to be discovered from arid adapted Actinobacteria in the future. In the current survey, the diversity and biotechnological potential of Actinobacteria obtained from arid ecosystems, along with the recent work trend on Iranian arid soils, are reported. PMID:26858692

Integrated terrain mapping with digital Landsat images in Queensland, Australia

USGS Publications Warehouse

Robinove, Charles Joseph

1979-01-01

Mapping with Landsat images usually is done by selecting single types of features, such as soils, vegetation, or rocks, and creating visually interpreted or digitally classified maps of each feature. Individual maps can then be overlaid on or combined with other maps to characterize the terrain. Integrated terrain mapping combines several terrain features into each map unit which, in many cases, is more directly related to uses of the land and to methods of land management than the single features alone. Terrain brightness, as measured by the multispectral scanners in Landsat 1 and 2, represents an integration of reflectance from the terrain features within the scanner's instantaneous field of view and is therefore more correlatable with integrated terrain units than with differentiated ones, such as rocks, soils, and vegetation. A test of the feasibilty of the technique of mapping integrated terrain units was conducted in a part of southwestern Queensland, Australia, in cooperation with scientists of the Queensland Department of Primary Industries. The primary purpose was to test the use of digital classification techniques to create a 'land systems map' usable for grazing land management. A recently published map of 'land systems' in the area (made by aerial photograph interpretation and ground surveys), which are integrated terrain units composed of vegetation, soil, topography, and geomorphic features, was used as a basis for comparison with digitally classified Landsat multispectral images. The land systems, in turn, each have a specific grazing capacity for cattle (expressed in beasts per km 2 ) which is estimated following analysis of both research results and property carrying capacities. Landsat images, in computer-compatible tape form, were first contrast-stretched to increase their visual interpretability, and digitally classified by the parallelepiped method into distinct spectral classes to determine their correspondence to the land systems classes and to areally smaller, but readily recognizable, 'land units.' Many land systems appeared as distinct spectral classes or as acceptably homogeneous combinations of several spectral classes. The digitally classified map corresponded to the general geographic patterns of many of the land systems. Statistical correlation of the digitally classified map and the published map was not possible because the published map showed only land systems whereas the digitally classified map showed some land units as well as systems. The general correspondence of spectral classes to the integrated terrain units means that the digital mapping of the units may precede fieldwork and act as a guide to field sampling and detailed terrain unit description as well as measuring of the location, area, and extent of each unit. Extension of the Landsat mapping and classification technique to other arid and semi-arid regions of the world may be feasible.

Climate trends in the wood anatomy of Acacia sensu stricto (Leguminosae: Mimosoideae)

PubMed Central

Warwick, Nigel W. M.; Hailey, Luke; Clarke, Kerri L.

2017-01-01

Abstract Background and Aims This study investigates the structural diversity of the secondary xylem of 54 species of Acacia from four taxonomic sections collected across five climate regions along a 1200 km E–W transect from sub-tropical [approx. 1400 mm mean annual precipitation (MAP)] to arid (approx. 240 mm MAP) in New South Wales, Australia. Acacia sensu stricto (s.s.) is a critical group for understanding the effect of climate and phylogeny on the functional anatomy of wood. Methods Wood samples were sectioned in transverse, tangential and radial planes for light microscopy and analysis. Key Results The wood usually has thick-walled vessels and fibres, paratracheal parenchyma and uniseriate and biseriate rays, occasionally up to four cells wide. The greater abundance of gelatinous fibres in arid and semi-arid species may have ecological significance. Prismatic crystals in chambered fibres and axial parenchyma increased in abundance in semi-arid and arid species. Whereas vessel diameter showed only a small decrease from the sub-tropical to the arid region, there was a significant 2-fold increase in vessel frequency and a consequent 3-fold decrease in the vulnerability index. Conclusions Although the underlying phylogeny determines the qualitative wood structure, climate has a significant influence on the functional wood anatomy of Acacia s.s., which is an ideal genus to study the effect of these factors. PMID:28334287

Amphibian and reptile biodiversity in the semi-arid region of the municipality of Nopala de Villagrán, Hidalgo, Mexico

PubMed Central

Mendoza-Hernández, Andrés Alberto; Flores-Villela, Oscar

2018-01-01

Current global changes are putting both biodiversity and the processes that depend on it at risk. This is especially true for semi-arid regions and the flagship groups that inhabit them, such as amphibians and reptiles. Semi-arid regions are often thought to have lower biodiversity and thus have been overlooked, resulting in the underestimation of their biological richness. Therefore, the aim of this study was to conduct an inventory of amphibians and reptiles in the semi-arid municipality of Nopala de Villagrán, Mexico, and analyze its biodiversity in relation to the seasons, vegetation and microhabitat. During a year of fieldwork, we found 24 species in the area, most of them of low abundance, and one of which was recorded for the first time for the state of Hidalgo. We documented five amphibian species and 19 reptile species. We also found that observed species richness was higher in the rainy season and in xeric scrub vegetation, although only the season differences were significant according to rarefaction curves. Our findings highlight the importance of seasonality and vegetation type for the species that inhabit this semi-arid region. This study broadens our understanding of the importance of semi-arid regions and, by extension, that of other areas with similar characteristics. PMID:29312825

On the Role of Hyper-arid Regions within the Virtual Water Trade Network

NASA Astrophysics Data System (ADS)

Aggrey, James; Alshamsi, Aamena; Molini, Annalisa

2016-04-01

Climate change, economic development, and population growth are bound to increasingly impact global water resources, posing a significant threat to the sustainable development of arid regions, where water consumption highly exceeds the natural carrying capacity, population growth rate is high, and climate variability is going to impact both water consumption and availability. Virtual Water Trade (VWT) - i.e. the international trade network of water-intensive products - has been proposed as a possible solution to optimize the allocation of water resources on the global scale. By increasing food availability and lowering food prices it may in fact help the rapid development of water-scarce regions. The structure of the VWT network has been analyzed by a number of authors both in connection with trade policies, socioeconomic constrains and agricultural efficiency. However a systematic analysis of the structure and the dynamics of the VWT network conditional to aridity, climatic forcing and energy availability, is still missing. Our goal is hence to analyze the role of arid and hyper-arid regions within the VWN under diverse climatic, demographic, and energy constraints with an aim to contribute to the ongoing Energy-Water-Food nexus discussion. In particular, we focus on the hyper-arid lands of the Arabian Peninsula, the role they play in the global network and the assessment of their specific criticalities, as reflected in the VWN resilience.

Stability measures in arid ecosystems

NASA Astrophysics Data System (ADS)

Nosshi, M. I.; Brunsell, N. A.; Koerner, S.

2015-12-01

Stability, the capacity of ecosystems to persist in the face of change, has proven its relevance as a fundamental component of ecological theory. Here, we would like to explore meaningful and quantifiable metrics to define stability, with a focus on highly variable arid and semi-arid savanna ecosystems. Recognizing the importance of a characteristic timescale to any definition of stability, our metrics will be focused scales from annual to multi-annual, capturing different aspects of stability. Our three measures of stability, in increasing order of temporal scale, are: (1) Ecosystem resistance, quantified as the degree to which the system maintains its mean state in response to a perturbation (drought), based on inter-annual variability in Normalized Difference Vegetation Index (NDVI). (2) An optimization approach, relevant to arid systems with pulse dynamics, that models vegetation structure and function based on a trade off between the ability to respond to resource availability and avoid stress. (3) Community resilience, measured as species turnover rate (β diversity). Understanding the nature of stability in structurally-diverse arid ecosystems, which are highly variable, yields theoretical insight which has practical implications.

The Impact of Urban Development in the Arid Zone and its Management.

NASA Astrophysics Data System (ADS)

Gat, J. R.

2002-05-01

From the experience in humid and semi-arid settings, the immediate impact of urbanization on the hydrological system is the interference with the natural direct infiltration pathways, resulting in a decrease of groundwater recharge as well as the possibility of surface flooding. In contrast, in the arid environment the limited rain amounts and number of rain events makes the contribution of rain of marginal importance in the city's water balance. The major impact of urbanization in the arid zone is the continuous excess of discharge of treated or untreated sewage or water spills, originating from the import of water to the city's water supply. Their effect can be advantageous if properly channeled. On the other hand, the polluting potential of these water excesses as well as the possibility of mobilizing stored salinity in the downstream locations is of concern, if the natural drainage network and its remediation capacity becomes overloaded. Further, since the arid zone hydrological cycle depends naturally on a discontinuous and episodal groundwater recharge pattern, the new situation requires the re-assessment of the eco-hydrological patterns in the downstream location.

Uncertainty in Ecohydrological Modeling in an Arid Region Determined with Bayesian Methods

PubMed Central

Yang, Junjun; He, Zhibin; Du, Jun; Chen, Longfei; Zhu, Xi

2016-01-01

In arid regions, water resources are a key forcing factor in ecosystem circulation, and soil moisture is the critical link that constrains plant and animal life on the soil surface and underground. Simulation of soil moisture in arid ecosystems is inherently difficult due to high variability. We assessed the applicability of the process-oriented CoupModel for forecasting of soil water relations in arid regions. We used vertical soil moisture profiling for model calibration. We determined that model-structural uncertainty constituted the largest error; the model did not capture the extremes of low soil moisture in the desert-oasis ecotone (DOE), particularly below 40 cm soil depth. Our results showed that total uncertainty in soil moisture prediction was improved when input and output data, parameter value array, and structure errors were characterized explicitly. Bayesian analysis was applied with prior information to reduce uncertainty. The need to provide independent descriptions of uncertainty analysis (UA) in the input and output data was demonstrated. Application of soil moisture simulation in arid regions will be useful for dune-stabilization and revegetation efforts in the DOE. PMID:26963523

A review of research on ecosystem of arid area using RS-GIS in China

NASA Astrophysics Data System (ADS)

Han, Hongling

2007-06-01

Arid area is classical mountain-oasis-desert ecosystem in North-west China. As the ecosystem has its nature geography character obviously, it has superior to research with remote-sensing and geography information system. The study on arid ecosystem in RS-GIS' way is focused on that the landscape spatial pattern of complex MODS ecosystem, the dynamic development of Land use/land cover, the security of ecological environment of eco-tone and so on. At the same time, the research on the single system is more and more, which has provided more ways and deeper fields of arid area using RS-GIS. Through the use of RS-GIS, desertification, oasis' development, urbanization etc. can be known, which would provide precaution for human-being and suitable ways to adjust the problems.

Global patterns and environmental controls of perchlorate and nitrate co-occurrence in arid and semi-arid environments

USGS Publications Warehouse

Jackson, W Andrew; Böhlke, John Karl; Andraski, Brian J.; Fahlquist, Lynne S.; Bexfield, Laura M.; Eckardt, Frank D.; Gates, John B.; Davila, Alfonso F.; McKay, Christopher P.; Rao, Balaji; Sevanthi, Ritesh; Rajagopalan, Srinath; Estrada, Nubia; Sturchio, Neil C.; Hatzinger, Paul B.; Anderson, Todd A.; Orris, Greta J.; Betancourt, Julio L.; Stonestrom, David A.; Latorre, Claudio; Li, Yanhe; Harvey, Gregory J.

2015-01-01

Natural perchlorate (ClO4−) is of increasing interest due to its wide-spread occurrence on Earth and Mars, yet little information exists on the relative abundance of ClO4− compared to other major anions, its stability, or long-term variations in production that may impact the observed distributions. Our objectives were to evaluate the occurrence and fate of ClO4− in groundwater and soils/caliche in arid and semi-arid environments (southwestern United States, southern Africa, United Arab Emirates, China, Antarctica, and Chile) and the relationship of ClO4− to the more well-studied atmospherically deposited anions NO3−and Cl− as a means to understand the prevalent processes that affect the accumulation of these species over various time scales. ClO4− is globally distributed in soil and groundwater in arid and semi-arid regions on Earth at concentrations ranging from 10−1to 106 μg/kg. Generally, the ClO4− concentration in these regions increases with aridity index, but also depends on the duration of arid conditions. In many arid and semi-arid areas, NO3− and ClO4− co-occur at molar ratios (NO3−/ClO4−) that vary between ∼104and 105. We hypothesize that atmospheric deposition ratios are largely preserved in hyper-arid areas that support little or no biological activity (e.g. plants or bacteria), but can be altered in areas with more active biological processes including N2 fixation, N mineralization, nitrification, denitrification, and microbial ClO4− reduction, as indicated in part by NO3− isotope data. In contrast, much larger ranges of Cl−/ClO4− and Cl−/NO3−ratios indicate Cl− varies independently from both ClO4− and NO3−. The general lack of correlation between Cl− and ClO4− or NO3− implies that Cl− is not a good indicator of co-deposition and should be used with care when interpreting oxyanion cycling in arid systems. The Atacama Desert appears to be unique compared to all other terrestrial locations having a NO3−/ClO4− molar ratio ∼103. The relative enrichment in ClO4−compared to Cl− or NO3− and unique isotopic composition of Atacama ClO4− may reflect either additional in-situ production mechanism(s) or higher relative atmospheric production rates in that specific region or in the geological past. Elevated concentrations of ClO4− reported on the surface of Mars, and its enrichment with respect to Cl− and NO3−, could reveal important clues regarding the climatic, hydrologic, and potentially biologic evolution of that planet. Given the highly conserved ratio of NO3−/ClO4− in non-biologically active areas on Earth, it may be possible to use alterations of this ratio as a biomarker on Mars and for interpreting major anion cycles and processes on both Mars and Earth, particularly with respect to the less-conserved NO3− pool terrestrially.

Landsat and GRACE observations of arid wetland dynamics in a dryland river system under multi-decadal hydroclimatic extremes

NASA Astrophysics Data System (ADS)

Xie, Zunyi; Huete, Alfredo; Ma, Xuanlong; Restrepo-Coupe, Natalia; Devadas, Rakhesh; Clarke, Kenneth; Lewis, Megan

2016-12-01

Arid wetlands are important for biodiversity conservation, but sensitive and vulnerable to climate variability and hydroclimatic events. Amplification of the water cycle, including the increasing frequency and severity of droughts and wet extremes, is expected to alter spatial and temporal hydrological patterns in arid wetlands globally, with potential threats to ecosystem services and their functioning. Despite these pressing challenges, the ecohydrological interactions and resilience of arid wetlands to highly variable water regimes over long time periods remain largely unknown. Recent broad-scale drought and floods over Australia provide unique opportunities to improve our understanding of arid wetland ecosystem responses to hydroclimatic extremes. Here we analysed the ecohydrological dynamics of the Coongie Lakes arid wetland in central Australia, one of the world's largest Ramsar-designated wetlands, using more than two decades (1988-2011) of vegetation and floodwater extent retrievals derived from Landsat satellite observations. To explore the impacts of large-scale hydrological fluctuations on the arid wetland, we further coupled Landsat measurements with Total Water Storage Anomaly (TWSA) data obtained from the Gravity Recovery and Climate Experiment (GRACE) satellites. Pronounced seasonal and inter-annual variabilities of flood and vegetation activities were observed over the wetland, with variations in vegetation growth extent highly correlated with flood extent (r = 0.64, p < 0.05) that ranged from nearly zero to 3456 km2. We reported the hydrological dynamics and associated ecosystem responses to be largely driven by the two phases (El Niño and La Niña) of the El Nino-Southern Oscillation (ENSO) ocean-atmosphere system. Changes in flood and vegetation extent were better explained by GRACE-TWSA (r = 0.8, lag = 0 month) than rainfall (r = 0.34, lag = 3 months) over the water source area, demonstrating that TWS is a valuable hydrological indicator for complex dryland river systems. The protracted Millennium Drought from 2001 to 2009 resulted in long-term absence of major flood events, which substantially suppressed wetland vegetation growth. However, the 2010-11 La Niña induced flooding events led to an exceptionally large resurgence of vegetation, with a mean vegetation growth extent anomaly exceeding the historical average (1988-2011) by more than 1.5 standard deviations, suggesting a significant resilience of arid wetland ecosystems to climate variability. This study showed the ecological functioning of arid wetlands is particularly sensitive to large-scale hydrological fluctuations and extreme drought conditions, and vulnerable to future altered water regimes due to climate change. The methods developed herein can be applied to arid wetlands located in other dryland river systems across the globe.

A comparison of integrated river basin management strategies: A global perspective

NASA Astrophysics Data System (ADS)

Zhao, Chunhong; Wang, Pei; Zhang, Guanghong

In order to achieve the integrated river basin management in the arid and rapid developing region, the Heihe River Basin (HRB) in Northwestern China, one of critical river basins were selected as a representative example, while the Murray-Darling Basin (MDB) in Australia and the Colorado River Basin (CRB) in the USA were selected for comparative analysis in this paper. Firstly, the comparable characters and hydrological contexts of these three watersheds were introduced in this paper. Then, based on comparative studies on the river basin challenges in terms of the drought, intensive irrigation, and rapid industrialization, the hydrological background of the MDB, the CRB and the HRB was presented. Subsequently, the river management strategies were compared in three aspects: water allocation, water organizations, and water act and scientific projects. Finally, we proposed recommendations for integrated river basin management for the HRB: (1) Water allocation strategies should be based on laws and markets on the whole basin; (2) Public participation should be stressed by the channels between governance organizations and local communities; (3) Scientific research should be integrated into river management to understand the interactions between the human and nature.

Drought versus heat: What's the major constraint on Mediterranean green roof plants?

PubMed

Savi, Tadeja; Dal Borgo, Anna; Love, Veronica L; Andri, Sergio; Tretiach, Mauro; Nardini, Andrea

2016-10-01

Green roofs are gaining momentum in the arid and semi-arid regions due to their multiple benefits as compared with conventional roofs. One of the most critical steps in green roof installation is the selection of drought and heat tolerant species that can thrive under extreme microclimate conditions. We monitored the water status, growth and survival of 11 drought-adapted shrub species grown on shallow green roof modules (10 and 13cm deep substrate) and analyzed traits enabling plants to cope with drought (symplastic and apoplastic resistance) and heat stress (root membrane stability). The physiological traits conferring efficiency/safety to the water transport system under severe drought influenced plant water status and represent good predictors of both plant water use and growth rates over green roofs. Moreover, our data suggest that high substrate temperature represents a stress factor affecting plant survival to a larger extent than drought per se. In fact, the major cause influencing seedling survival on shallow substrates was the species-specific root resistance to heat, a single and easy measurable trait that should be integrated into the methodological framework for screening and selection of suitable shrub species for roof greening in the Mediterranean. Copyright © 2016 Elsevier B.V. All rights reserved.

Mobile dune fixation by a fast-growing clonal plant: a full life-cycle analysis.

PubMed

Li, Shou-Li; Yu, Fei-Hai; Werger, Marinus J A; Dong, Ming; During, Heinjo J; Zuidema, Pieter A

2015-03-11

Desertification is a global environmental problem, and arid dunes with sparse vegetation are especially vulnerable to desertification. One way to combat desertification is to increase vegetation cover by planting plant species that can realize fast population expansion, even in harsh environments. To evaluate the success of planted species and provide guidance for selecting proper species to stabilize active dunes, demographic studies in natural habitats are essential. We studied the life history traits and population dynamics of a dominant clonal shrub Hedysarum laeve in Inner-Mongolia, northern China. Vital rates of 19057 ramets were recorded during three annual censuses (2007-2009) and used to parameterize Integral Projection Models to analyse population dynamics. The life history of H. laeve was characterized by high ramet turnover and population recruitment entirely depended on clonal propagation. Stochastic population growth rate was 1.32, suggesting that the populations were experiencing rapid expansion. Elasticity analysis revealed that clonal propagation was the key contributor to population growth. The capacity of high clonal propagation and rapid population expansion in mobile dunes makes H. laeve a suitable species to combat desertification. Species with similar life-history traits to H. laeve are likely to offer good opportunities for stabilizing active dunes in arid inland ecosystems.

Declining agricultural production in rapidly urbanizing semi-arid regions: policy tradeoffs and sustainability indicators

NASA Astrophysics Data System (ADS)

Dozier, André Q.; Arabi, Mazdak; Wostoupal, Benjamin C.; Goemans, Christopher G.; Zhang, Yao; Paustian, Keith

2017-08-01

In rapidly urbanizing semi-arid regions, increasing amounts of historically irrigated cropland lies permanently fallowed due to water court policies as agricultural water rights are voluntarily being sold to growing cities. This study develops an integrative framework for assessing the effects of population growth and land use change on agricultural production and evaluating viability of alternative management strategies, including alternative agricultural transfer methods, regional water ownership restrictions, and urban conservation. A partial equilibrium model of a spatially-diverse regional water rights market is built in application of the framework to an exemplary basin. The model represents agricultural producers as profit-maximizing suppliers and municipalities as cost-minimizing consumers of water rights. Results indicate that selling an agricultural water right today is worth up to two times more than 40 years of continued production. All alternative policies that sustain agricultural cropland and crop production decrease total agricultural profitability by diminishing water rights sales revenue, but in doing so, they also decrease municipal water acquisition costs. Defining good indicators and incorporating adequate spatial and temporal detail are critical to properly analyzing policy impacts. To best improve agricultural profit from production and sale of crops, short-term solutions include alternative agricultural transfer methods while long-term solutions incorporate urban conservation.

Monitoring Soil Infiltration In Semi-Arid Regions With Meteosat And A Coupled Model Approach Using PROMET And SLC

NASA Astrophysics Data System (ADS)

Klug, P.; Bach, H.; Migdall, S.

2013-12-01

In arid regions the infiltration of sparse rainfalls and resulting ground water recharge is a critical quantity for the water cycle. With the PROMET model the infiltration process can be simulated in detail, since 4 soil layers together with the hourly calculation time step allow simulating the vertical water transport. Wet soils are darker than dry soils. Using the SLC reflectance model this effect can be simulated and compared to temporal high resolution time series of measured reflectances from Meteosat in order to monitor the drying process. This study demonstrates how MSG can be used to better parameterize the simulation of the infiltration process and reduce uncertainties in ground water recharge estimation. The study is carried out in the frame of the EU FP7 project CLIMB (Climate Induced Changes on the Hydrology of Mediterranean Basins). According to climate projections, Mediterranean countries are at risk of changes in the hydrological budget, the agricultural productivity and drinking water supply in the future. The CLIMB FP-7 project coordinated by the University of Munich (LMU) aims at employing integrated hydrological modelling in a new framework to reduce existing uncertainties in climate change impact analysis of the Mediterranean region [1, 2].

Chemical Records in Snowpits from High Altitude Glaciers in the Tibetan Plateau and Its Surroundings

PubMed Central

Zhang, Yulan; Kang, Shichang; Zhang, Qianggong; Gao, Tanguang; Guo, Junming; Grigholm, Bjorn; Huang, Jie; Sillanpää, Mika; Li, Xiaofei; Du, Wentao; Li, Yang; Ge, Xinlei

2016-01-01

Glaciochemistry can provide important information about climatic change and environmental conditions, as well as for testing regional and global atmospheric trace transport models. In this study, δ18O and selected chemical constituents records in snowpits collected from eight glaciers in the Tibetan Plateau and adjacent areas have been investigated. Drawing on the integrated data, our study summarized the seasonal and spatial characteristics of snow chemistry, and their potential sources. Distinct seasonal patterns of δ18O values in snowpits indicated more negative in the south TP controlled by Indian monsoon, and less negative in the north TP and Tien Shan. Overall increasing concentrations of microparticles and crustal ions from south to north indicated a strength of dust deposition on glaciers from semi-arid and arid regions. Principal component analysis and air mass trajectories suggested that chemical constituents were mainly attributable to crustal sources as demonstrated by the high concentrations of ions occurring during the non-monsoon seasons. Nevertheless, other sources, such as anthropogenic pollution, played an important role on chemical variations of glaciers near the human activity centers. This study concluded that air mass transport from different sources played important roles on the spatial distributions and seasonality of glaciochemistry. PMID:27186638

Forestry as a possible solution to the environmental and energy difficulties facing semi-arid Africa. The case of Upper Volta

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weinstabel, P.E.; Zech, W.

1982-01-01

The total annual demand for wood in Upper Volta is about 4.2 million cubic m solid wood, 94% of the population depends on wood for energy (compared with 84% in the Sahel states as a whole), and more than 30% of income in urban areas is spent on acquiring wood. Any policy aimed at securing adequate food supplies for the population must therefore be accompanied by a programme for safeguarding energy supplies. Measures which should be included in an integrated energy programme are presented and details are given of Upper Volta's forestry programme. 21 references.

[Triatominae and Cactaceae: a risk for the transmission of the American trypanosomiasis in the peridomicilary space (Northeast Brazil)].

PubMed

Emperaire, L; Romaña, C A

2006-06-01

Field observations carried in semi-arid Brazil Northeast point out the frequent association, in the peridomiciliary space, between a cactus, Cereus jamacaru, the occurrence of nests in its branches and the occurrence of two species of insects vectors of Trypanosoma cruzi, pathogenic agent of Chagas disease: Rhodnius neglectus and Triatoma pseudomaculata. The analysis of the architectural variables of this Cactaceae shows that the presence of nests, and thus of insects, depends on the traditional practices of management of this cactus. This study underlines the relevance of an integrated approach of the ecology of Triatominae for the identification of factors of risk.

Experimental study on flat plate air solar collector using a thin sand layer

NASA Astrophysics Data System (ADS)

Lati, Moukhtar; Boughali, Slimane; Bouguettaia, Hamza; Mennouche, Djamel; Bechki, Djamel

2016-07-01

A flat plate air solar collector was constructed in the laboratory of New and Renewable Energy in Arid Zones LENREZA, Ouargla University-South East Algeria. The absorber of the flat plate air solar collector was laminated with a thin layer of local sand. This acted as a thermal storage system (packed bed) with a collecting area of 2.15 m2 (0.86 m × 2.5 m). It was noticed that the solar heater integrated with the thermal storage material delivered comparatively higher temperatures; thus, giving a better efficiency than the air heater without the thermal storage system.

Arid Lands--A Study in Ecological Disaster

ERIC Educational Resources Information Center

Eckholm, Erik

1977-01-01

Reports that over-grazing and unsound agricultural practices are increasing the world-wide amount of uninhabitable land. Cites some practices which have been used to successfully reclaim arid land areas. (CP)

Association of ARID5B gene variants with acute lymphoblastic leukemia in Yemeni children.

PubMed

Al-Absi, Boshra; Noor, Suzita M; Saif-Ali, Riyadh; Salem, Sameer D; Ahmed, Radwan H; Razif, Muhammad Fm; Muniandy, Sekaran

2017-04-01

Studies have shown an association between ARID5B gene polymorphisms and childhood acute lymphoblastic leukemia. However, the association between ARID5B variants and acute lymphoblastic leukemia among the Arab population still needs to be studied. The aim of this study was to investigate the association between ARID5B variants with acute lymphoblastic leukemia in Yemeni children. A total of 14 ARID5B gene single nucleotide polymorphisms (SNPs) were genotyped in 289 Yemeni children, of whom 136 had acute lymphoblastic leukemia and 153 were controls, using the nanofluidic Dynamic Array (Fluidigm 192.24 Dynamic Array). Using logistic regression adjusted for age and gender, the risks of acute lymphoblastic leukemia were presented as odds ratios and 95% confidence intervals. We found that nine SNPs were associated with acute lymphoblastic leukemia under additive genetic models: rs7073837, rs10740055, rs7089424, rs10821936, rs4506592, rs10994982, rs7896246, rs10821938, and rs7923074. Furthermore, the recessive models revealed that six SNPs were risk factors for acute lymphoblastic leukemia: rs10740055, rs7089424, rs10994982, rs7896246, rs10821938, and rs7923074. The gender-specific impact of these SNPs under the recessive genetic model revealed that SNPs rs10740055, rs10994982, and rs6479779 in females, and rs10821938 and rs7923074 in males were significantly associated with acute lymphoblastic leukemia risk. Under the dominant model, SNPs rs7073837, rs10821936, rs7896246, and rs6479778 in males only showed striking association with acute lymphoblastic leukemia. The additive model revealed that SNPs with significant association with acute lymphoblastic leukemia were rs10821936 (both males and females); rs7073837, rs10740055, rs10994982, and rs4948487 (females only); and rs7089424, rs7896246, rs10821938, and rs7923074 (males only). In addition, the ARID5B haplotype block (CGAACACAA) showed a higher risk for acute lymphoblastic leukemia. The haplotype (CCCGACTGC) was associated with protection against acute lymphoblastic leukemia. In conclusion, our study has shown that ARID5B variants are associated with acute lymphoblastic leukemia in Yemeni children with several gender biases of ARID5B single nucleotide polymorphisms reported.

Aridification as a driver of biodiversity: a case study for the cycad genus Dioon (Zamiaceae).

PubMed

Said Gutiérrez-Ortega, José; Yamamoto, Takashi; Vovides, Andrew P; Angel Pérez-Farrera, Miguel; Martínez, José F; Molina-Freaner, Francisco; Watano, Yasuyuki; Kajita, Tadashi

2018-01-25

Aridification is considered a selective pressure that might have influenced plant diversification. It is suggested that plants adapted to aridity diversified during the Miocene, an epoch of global aridification (≈15 million years ago). However, evidence supporting diversification being a direct response to aridity is scarce, and multidisciplinary evidence, besides just phylogenetic estimations, is necessary to support the idea that aridification has driven diversification. The cycad genus Dioon (Zamiaceae), a tropical group including species occurring from humid forests to arid zones, was investigated as a promising study system to understand the associations among habitat shifts, diversification times, the evolution of leaf epidermal adaptations, and aridification of Mexico. A phylogenetic tree was constructed from seven chloroplast DNA sequences and the ITS2 spacer to reveal the relationships among 14 Dioon species from habitats ranging from humid forests to deserts. Divergence times were estimated and the habitat shifts throughout Dioon phylogeny were detected. The epidermal anatomy among Dioon species was compared and correlation tests were performed to associate the epidermal variations with habitat parameters. Events of habitat shifts towards arid zones happened exclusively in one of the two main clades of Dioon. Such habitat shifts happened during the species diversification of Dioon, mainly during the Miocene. Comparative anatomy showed epidermal differences between species from arid and mesic habitats. The variation of epidermal structures was found to be correlated with habitat parameters. Also, most of the analysed epidermal traits showed significant phylogenetic signals. The diversification of Dioon has been driven by the aridification of Mexico. The Miocene timing corresponds to the expansion of arid zones that embedded the ancestral Dioon populations. As response, species in arid zones evolved epidermal traits to counteract aridity stress. This case study provides a robust body of evidence supporting the idea that aridification is an important driver of biodiversity. © The Authors 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The impact of anthropogenic climate change on wildfire across western US forests

NASA Astrophysics Data System (ADS)

Williams, P.; Abatzoglou, J. T.

2016-12-01

Increased forest fire activity across the western United States (US) in recent decades has contributed to widespread forest mortality, carbon emissions, periods of degraded air quality, and substantial fire suppression expenditures. The increase in forest fire activity has likely been enabled by a number of factors including the legacy of fire suppression and human settlement, changes in suppression policies, natural climate variability, and human-caused climate change. We use modeled climate projections to estimate the contribution of anthropogenic climate change to observed increases in eight fuel aridity metrics and forest fire area across the western US. Anthropogenic increases in temperature and vapor pressure deficit have significantly enhanced fuel aridity across western US forests over the past several decades. Comparing observational climate records to records recalculated after removal of modeled anthropogenic trends, we find that anthropogenic climate change accounted for approximately 55% of observed increases in the eight-metric mean fuel aridity during 1979-2015 across western US forests. This implicates anthropogenic climate change as an important driver of observed increases in fuel aridity, and also highlights the importance of natural multi-decadal climate variability in influencing trends in forest fire potential on the timescales of human lives. Based on a very strong (R2 = 0.76) and mechanistically reasonable relationship between interannual variability in the eight-metric mean fuel aridity and forest-fire area in the western US, we estimate that anthropogenic increases in fuel aridity contributed to an additional 4.2 million ha (95% confidence range: 2.7-6.5 million ha) of forest fire area during 1984-2015, nearly doubling the total forest fire area expected in the absence of anthropogenic climate change. The relationship between annual forest fire area and fuel aridity is exponential and the proportion of total forest area burned in a given year has grown rapidly over the past 32 years. Natural climate variability will continue to alternate between modulating and compounding anthropogenic increases in fuel aridity, but anthropogenic climate change has emerged as a chronic driver of increased forest fire activity and should continue to do so where fuels are not limiting.

Integrated double mulching practices optimizes soil temperature and improves soil water utilization in arid environments.

PubMed

Yin, Wen; Feng, Fuxue; Zhao, Cai; Yu, Aizhong; Hu, Falong; Chai, Qiang; Gan, Yantai; Guo, Yao

2016-09-01

Water shortage threatens agricultural sustainability in many arid and semiarid areas of the world. It is unknown whether improved water conservation practices can be developed to alleviate this issue while increasing crop productivity. In this study, we developed a "double mulching" system, i.e., plastic film coupled with straw mulch, integrated together with intensified strip intercropping. We determined (i) the responses of soil evaporation and moisture conservation to the integrated double mulching system and (ii) the change of soil temperature during key plant growth stages under the integrated systems. Experiments were carried out in northwest China in 2009 to 2011. Results show that wheat-maize strip intercropping in combination with plastic film and straw covering on the soil surface increased soil moisture (mm) by an average of 3.8 % before sowing, 5.3 % during the wheat and maize co-growth period, 4.4 % after wheat harvest, and 4.9 % after maize harvest, compared to conventional practice (control). The double mulching decreased total evapotranspiration of the two intercrops by an average of 4.6 % (P < 0.05), compared to control. An added feature was that the double mulching system decreased soil temperature in the top 10-cm depth by 1.26 to 1.31 °C in the strips of the cool-season wheat, and by 1.31 to 1.51 °C in the strips of the warm-season maize through the 2 years. Soil temperature of maize strips higher as 1.25 to 1.94 °C than that of wheat strips in the top 10-cm soil depth under intercropping with the double mulching system; especially higher as 1.58 to 2.11 °C under intercropping with the conventional tillage; this allows the two intercrops to grow in a well "collaborative" status under the double mulching system during their co-growth period. The improvement of soil moisture and the optimization of soil temperature for the two intercrops allow us to conclude that wheat-maize intensification with the double mulching system can be used as an effective farming model in alleviating water shortage issues experiencing in water shortage areas.

Are acid volatile sulfides (AVS) important trace metals sinks in semi-arid mangroves?

PubMed

Queiroz, Hermano Melo; Nóbrega, Gabriel Nuto; Otero, Xose L; Ferreira, Tiago Osório

2018-01-01

Acid-volatile sulfides (AVS) formation and its role on trace metals bioavailability were studied in semi-arid mangroves. The semi-arid climatic conditions at the studied sites, marked by low rainfall and high evapotranspiration rates, clearly limited the AVS formation (AVS contents varied from 0.10 to 2.34μmolg -1 ) by favoring oxic conditions (Eh>+350mV). The AVS contents were strongly correlated with reactive iron and organic carbon (r=0.84; r=0.83 respectively), evidencing their dominant role for AVS formation under semi-arid conditions. On the other hand, the recorded ΣSEM/AVS values remained >1 evidencing a little control of AVS over the bioavailability of trace metals and, thus, its minor role as a sink for toxic metals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biocrust-forming mosses mitigate the negative impacts of increasing aridity on ecosystem multifunctionality in drylands.

PubMed

Delgado-Baquerizo, Manuel; Maestre, Fernando T; Eldridge, David J; Bowker, Matthew A; Ochoa, Victoria; Gozalo, Beatriz; Berdugo, Miguel; Val, James; Singh, Brajesh K

2016-03-01

The increase in aridity predicted with climate change will have a negative impact on the multiple functions and services (multifunctionality) provided by dryland ecosystems worldwide. In these ecosystems, soil communities dominated by mosses, lichens and cyanobacteria (biocrusts) play a key role in supporting multifunctionality. However, whether biocrusts can buffer the negative impacts of aridity on important biogeochemical processes controlling carbon (C), nitrogen (N), and phosphorus (P) pools and fluxes remains largely unknown. Here, we conducted an empirical study, using samples from three continents (North America, Europe and Australia), to evaluate how the increase in aridity predicted by climate change will alter the capacity of biocrust-forming mosses to modulate multiple ecosystem processes related to C, N and P cycles. Compared with soil surfaces lacking biocrusts, biocrust-forming mosses enhanced multiple functions related to C, N and P cycling and storage in semiarid and arid, but not in humid and dry-subhumid, environments. Most importantly, we found that the relative positive effects of biocrust-forming mosses on multifunctionality compared with bare soil increased with increasing aridity. These results were mediated by plant cover and the positive effects exerted by biocrust-forming mosses on the abundance of soil bacteria and fungi. Our findings provide strong evidence that the maintenance of biocrusts is crucial to buffer negative effects of climate change on multifunctionality in global drylands. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Sensitivity of Vadose Zone Water Fluxes to Climate Shifts in Arid Settings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pfletschinger, H.; Prömmel, K.; Schüth, C.

2014-01-01

Vadose zone water fluxes in arid settings are investigated regarding their sensitivity to hydraulic soil parameters and meteorological data. The study is based on the inverse modeling of highly defined soil column experiments and subsequent scenario modeling comparing different climate projections for a defined arid region. In arid regions, groundwater resources are prone to depletion due to excessive water use and little recharge potential. Especially in sand dune areas, groundwater recharge is highly dependent on vadose zone properties and corresponding water fluxes. Nevertheless, vadose zone water fluxes under arid conditions are hard to determine owing to, among other reasons, deepmore » vadose zones with generally low fluxes and only sporadic high infiltration events. In this study, we present an inverse model of infiltration experiments accounting for variable saturated nonisothermal water fluxes to estimate effective hydraulic and thermal parameters of dune sands. A subsequent scenario modeling links the results of the inverse model with projections of a global climate model until 2100. The scenario modeling clearly showed the high dependency of groundwater recharge on precipitation amounts and intensities, whereas temperature increases are only of minor importance for deep infiltration. However, simulated precipitation rates are still affected by high uncertainties in the response to the hydrological input data of the climate model. Thus, higher certainty in the prediction of precipitation pattern is a major future goal for climate modeling to constrain future groundwater management strategies in arid regions.« less

Integrating geospatial and ground geophysical information as guidelines for groundwater potential zones in hard rock terrains of south India.

PubMed

Rashid, Mehnaz; Lone, Mahjoor Ahmad; Ahmed, Shakeel

2012-08-01

The increasing demand of water has brought tremendous pressure on groundwater resources in the regions were groundwater is prime source of water. The objective of this study was to explore groundwater potential zones in Maheshwaram watershed of Andhra Pradesh, India with semi-arid climatic condition and hard rock granitic terrain. GIS-based modelling was used to integrate remote sensing and geophysical data to delineate groundwater potential zones. In the present study, Indian Remote Sensing RESOURCESAT-1, Linear Imaging Self-Scanner (LISS-4) digital data, ASTER digital elevation model and vertical electrical sounding data along with other data sets were analysed to generate various thematic maps, viz., geomorphology, land use/land cover, geology, lineament density, soil, drainage density, slope, aquifer resistivity and aquifer thickness. Based on this integrated approach, the groundwater availability in the watershed was classified into four categories, viz. very good, good, moderate and poor. The results reveal that the modelling assessment method proposed in this study is an effective tool for deciphering groundwater potential zones for proper planning and management of groundwater resources in diverse hydrogeological terrains.

Decision Making Under Uncertainty and Complexity: A Model-Based Scenario Approach to Supporting Integrated Water Resources Management

NASA Astrophysics Data System (ADS)

Liu, Y.; Gupta, H.; Wagener, T.; Stewart, S.; Mahmoud, M.; Hartmann, H.; Springer, E.

2007-12-01

Some of the most challenging issues facing contemporary water resources management are those typified by complex coupled human-environmental systems with poorly characterized uncertainties. In other words, major decisions regarding water resources have to be made in the face of substantial uncertainty and complexity. It has been suggested that integrated models can be used to coherently assemble information from a broad set of domains, and can therefore serve as an effective means for tackling the complexity of environmental systems. Further, well-conceived scenarios can effectively inform decision making, particularly when high complexity and poorly characterized uncertainties make the problem intractable via traditional uncertainty analysis methods. This presentation discusses the integrated modeling framework adopted by SAHRA, an NSF Science & Technology Center, to investigate stakeholder-driven water sustainability issues within the semi-arid southwestern US. The multi-disciplinary, multi-resolution modeling framework incorporates a formal scenario approach to analyze the impacts of plausible (albeit uncertain) alternative futures to support adaptive management of water resources systems. Some of the major challenges involved in, and lessons learned from, this effort will be discussed.

Hazard analysis of Arid and semi-Arid (ASAL) regions of Kenya.

PubMed

Tabu, J S; Otwelo, J A; Koskei, P; Makokha, P

2013-06-01

This paper describes a situationanalysis on hazards in the Arid and semi-Arid lands of Kenya. The leading hazards affecting the Arid and semi-arid lands are mainly natural and include among others drought, floods, and landslides. Other hazards of importance were found to be war and conflict, HIV/AIDS and fires. Over 80% of these are weather related. The overall objective of this study was to prioritize hazards in the ASAL region. Specifically, the study identified the top ten hazards in the ASAL Districts of Kenya, determined Probability of occurrence; Analyzed the potential impact of the hazard and utilizing multiplier effect prioritized the Hazards using a hypothetical model. This was a descriptive study conducted in over half of the Kenya's ASAL Districts in four regions of Lower and Upper Eastern, North Eastern and part of the Coast region. Six Districts were purposively selected per region with six officers from each District all totaling one hundred and forty four. The sectors where respondents were sourced from were Agriculture, Health, local Government, and Provincial Administration, Environment and NGO. The members through a consensus process analyzed hazards in groups of their respective districts using a tool that had been developed and respondents trained on its use. One hundred and forty four (144) officers from Twenty four Districts in the four regions were recruited. One hundred twenty seven (81%) were male and only 27 (19% ) were female The representation of participants per sector was Governance 25% followed by Civil society organizations 21%, Health 16%, Agriculture and arid lands 15%, Research and scientific institutions 13%. The top Priority Hazards identified using the mean score were Drought and famine (5.4) Epidemics and epizootics (3.8), HIV/AIDS (3.6), War and conflict (2.5), Floods (2.5) CONCLUSIONS: The exercise confirmed the priority hazards in the Arid and semi-arid regions of Kenya and described vulnerability factors that included water scarcity, poverty and low educational levels. The region suffers from a variety of hazards in particular Drought and famine, Epidemics including HIV/AIDS and War and conflict. Environmental degradation though given a low score may be more of a perception. There is need to undertake a comprehensive hazard and Vulnerability analysis at regional and country level to inform interventions and other developmental activities. Women should be targeted at the community and leadership level, and efforts to empower them should be stepped up.

Correlations between microbial tetraether lipids and environmental variables in Chinese soils: Optimizing the paleo-reconstructions in semi-arid and arid regions

NASA Astrophysics Data System (ADS)

Yang, Huan; Pancost, Richard D.; Dang, Xinyue; Zhou, Xinying; Evershed, Richard P.; Xiao, Guoqiao; Tang, Changyan; Gao, Li; Guo, Zhengtang; Xie, Shucheng

2014-02-01

The bacterial membrane lipid-based continental paleothermometer, the MBT/CBT or MBT‧-CBT proxy (methylation index of branched tetraethers/cyclization of branched tetraethers), results in a large temperature deviation when applied in semiarid and arid regions. Here we propose new calibration models based on the investigation of >100 surface soils across a large climatic gradient, with a particular focus on semiarid and arid regions of China, and apply them to a loess-paleosol sequence. As reported elsewhere, MBT values exhibit a much higher correlation with MAAT than with summer temperature, suggesting a minimal seasonality bias; however, MBT is apparently insensitive to temperature <5 °C or >20 °C. Additional complexities are apparent in alkaline and arid soils, which are characterized by different relationships to climatic parameters than those in the complete Chinese (or global) dataset. For example, MBT and CBT indices exhibit a negative correlation in alkaline and arid soils, in contrast to their positive correlation in acid soils. Moreover, the cyclization ratio of bGDGTs (CBT), previously defined as a proxy for soil pH, is apparently primarily controlled by MAAT in these alkaline soils. Thus, we propose (1) a local Chinese calibration of the MBT-CBT proxy and (2) an alternative temperature proxy for use in semiarid and arid regions based on the fractional abundances of bGDGTs; the latter has a markedly higher determination factor and lower root mean square error in alkaline soils than the Chinese local calibration and is suggested to be preferred for paleotemperature reconstruction in Chinese loess/paleosol sequences. These new bGDGT proxies have been applied to the Weinan Holocene paleosol section of the Chinese Loess Plateau (CLP). The fractional abundance calibration, when applied in the Weinan Holocene paleosol, produces a total Holocene temperature variation of 5.2 °C and a temperature for the topmost sample that is consistent with the modern temperature. Previously, we showed that the ratio of archaeal isoprenoid GDGTs to bGDGTs (Ri/b) increases at MAP < 600 mm, and elevated Ri/b values (>0.5) in the CLP suggest the presence of enhanced aridity in the late Holocene in North China. In combination, the high Ri/b ratios (>0.5) and the associated low MBT values (<0.4) reveal the co-occurrence of dry and cold events, especially in the latest Holocene, in the loess-paleosol sequences in CLP, and probably also in cold and arid regions outside of CLP.

Sahra integrated modeling approach to address water resources management in semi-arid river basins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Springer, E. P.; Gupta, Hoshin V.; Brookshire, David S.

Water resources decisions in the 21Sf Century that will affect allocation of water for economic and environmental will rely on simulations from integrated models of river basins. These models will not only couple natural systems such as surface and ground waters, but will include economic components that can assist in model assessments of river basins and bring the social dimension to the decision process. The National Science Foundation Science and Technology Center for Sustainability of semi-Arid Hydrology and Riparian Areas (SAHRA) has been developing integrated models to assess impacts of climate variability and land use change on water resources inmore » semi-arid river basins. The objectives of this paper are to describe the SAHRA integrated modeling approach and to describe the linkage between social and natural sciences in these models. Water resources issues that arise from climate variability or land use change may require different resolution models to answer different questions. For example, a question related to streamflow may not need a high-resolution model whereas a question concerning the source and nature of a pollutant will. SAHRA has taken a multiresolution approach to integrated model development because one cannot anticipate the questions in advance, and the computational and data resources may not always be available or needed for the issue to be addressed. The coarsest resolution model is based on dynamic simulation of subwatersheds or river reaches. This model resolution has the advantage of simplicity and social factors are readily incorporated. Users can readily take this model (and they have) and examine the effects of various management strategies such as increased cost of water. The medium resolution model is grid based and uses variable grid cells of 1-12 km. The surface hydrology is more physically based using basic equations for energy and water balance terms, and modules are being incorporated that will simulate engineering components such as reservoirs or irrigation diversions and economic features such as variable demand. The fine resolution model is viewed as a tool to examine basin response using best available process models. The fine resolution model operates on a grid cell size of 100 m or less, which is consistent with the scale that our process knowledge has developed. The fine resolution model couples atmosphere, surface water and groundwater modules using high performance computing. The medium and fine resolution models are not expected at this time to be operated by users as opposed to the coarse resolution model. One of the objectives of the SAHRA integrated modeling task is to present results in a manner that can be used by those making decisions. The application of these models within SAHRA is driven by a scenario analysis and a place location. The place is the Rio Grande from its headwaters in Colorado to the New Mexico-Texas border. This provides a focus for model development and an attempt to see how the results from the various models relate. The scenario selected by SAHRA is the impact of a 1950's style drought using 1990's population and land use on Rio Grande water resources including surface and groundwater. The same climate variables will be used to drive all three models so that comparison will be based on how the three resolutions partition and route water through the river basin. Aspects of this scenario will be discussed and initial model simulation will be presented. The issue of linking economic modules into the modeling effort will be discussed and the importance of feedback from the social and economic modules to the natural science modules will be reviewed.« less

Contribution to the study of the zonal variation of the climate aridity in central northern Sahara (Algeria)

NASA Astrophysics Data System (ADS)

Benseghier-Hadjaidji, Fatiha; Talbi, Nadjib; Derridj, Arezki

2018-05-01

The environment degradation at the level of all its compartments which we notice at present, calls us to the risks that it would underestimate the climatic and consequently bioclimatic crisis there, in the North as in the South of the Mediterranean region. To protect the environment is not a luxury. In this respect, we wondered about the zonal variation of the climate aridity at the level of three bordering climatic stations: El-Oued, Touggourt and Ouargla. These are distant from 160 km on average some of the others. For that purpose, we based ourselves on the statistical tool the software "instat +" for the estimation of the ETP (PM) and afterward the determination of the pluvio-evapotranspiration "quotient P/ETP". For this analysis, the climatic data spread out over a period of 20 years. The results allowed to specify the aridity degree of the studied zone. So, they reveal a mitigation of the aridity of the climate in Touggourt and El-Oued while the hyper-aridity distinguishes well the Ouargla region. This approach contributes to a better knowledge of the dry ecosystems. This is important to indicate it to turn better in the eremologic search later.

Bias correction of precipitation data and its effects on aridity and drought assessment in China over 1961-2015.

PubMed

Yao, Ning; Li, Yi; Li, Na; Yang, Daqing; Ayantobo, Olusola Olaitan

2018-10-15

The accuracy of gauge-measured precipitation (P m ) affects drought assessment since drought severity changes due to precipitation bias correction. This research investigates how drought severity changes as the result of bias-corrected precipitation (P c ) using the Erinc's index I m and standardized precipitation evapotranspiration index (SPEI). Daily and monthly P c values at 552 sites in China were determined using daily P m and wind speed and air temperature data over 1961-2015. P c -based I m values were generally larger than P m -based I m for most sub-regions in China. The increased P c and P c -based I m values indicated wetter climate conditions than previously reported for China. After precipitation bias-correction, Climate types changed, e.g., 20 sites from severe-arid to arid, and 11 sites from arid to semi-arid. However, the changes in SPEI were not that obvious due to precipitation bias correction because the standardized index SPEI removed the effects of mean precipitation values. In conclusion, precipitation bias in different sub-regions of China changed the spatial and temporal characteristics of drought assessment. Copyright © 2018 Elsevier B.V. All rights reserved.

Dual control of pcdh8l/PCNS expression and function in Xenopus laevis neural crest cells by adam13/33 via the transcription factors tfap2α and arid3a.

PubMed

Khedgikar, Vikram; Abbruzzese, Genevieve; Mathavan, Ketan; Szydlo, Hannah; Cousin, Helene; Alfandari, Dominique

2017-08-22

Adam13/33 is a cell surface metalloprotease critical for cranial neural crest (CNC) cell migration. It can cleave multiple substrates including itself, fibronectin, ephrinB, cadherin-11, pcdh8 and pcdh8l (this work). Cleavage of cadherin-11 produces an extracellular fragment that promotes CNC migration. In addition, the adam13 cytoplasmic domain is cleaved by gamma secretase, translocates into the nucleus and regulates multiple genes. Here, we show that adam13 interacts with the arid3a/dril1/Bright transcription factor. This interaction promotes a proteolytic cleavage of arid3a and its translocation to the nucleus where it regulates another transcription factor: tfap2α. Tfap2α in turn activates multiple genes including the protocadherin pcdh8l (PCNS). The proteolytic activity of adam13 is critical for the release of arid3a from the plasma membrane while the cytoplasmic domain appears critical for the cleavage of arid3a. In addition to this transcriptional control of pcdh8l, adam13 cleaves pcdh8l generating an extracellular fragment that also regulates cell migration.

Dual control of pcdh8l/PCNS expression and function in Xenopus laevis neural crest cells by adam13/33 via the transcription factors tfap2α and arid3a

PubMed Central

Khedgikar, Vikram; Abbruzzese, Genevieve; Mathavan, Ketan; Szydlo, Hannah; Cousin, Helene

2017-01-01

Adam13/33 is a cell surface metalloprotease critical for cranial neural crest (CNC) cell migration. It can cleave multiple substrates including itself, fibronectin, ephrinB, cadherin-11, pcdh8 and pcdh8l (this work). Cleavage of cadherin-11 produces an extracellular fragment that promotes CNC migration. In addition, the adam13 cytoplasmic domain is cleaved by gamma secretase, translocates into the nucleus and regulates multiple genes. Here, we show that adam13 interacts with the arid3a/dril1/Bright transcription factor. This interaction promotes a proteolytic cleavage of arid3a and its translocation to the nucleus where it regulates another transcription factor: tfap2α. Tfap2α in turn activates multiple genes including the protocadherin pcdh8l (PCNS). The proteolytic activity of adam13 is critical for the release of arid3a from the plasma membrane while the cytoplasmic domain appears critical for the cleavage of arid3a. In addition to this transcriptional control of pcdh8l, adam13 cleaves pcdh8l generating an extracellular fragment that also regulates cell migration. PMID:28829038

Water management, purification, and conservation in arid climates. Volume 1: Water management

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goosen, M.F.A.; Shayya, W.H.

1999-07-01

Arid regions are already feeling the severe restraining effects of potable water shortages. In coming years, humid and sub-humid regions of the world will also have to face many of these same problems. In the future, serious conflicts may arise not because of a lack of oil, but due to water shortages. Are there solutions to these problems? Aside from increasing public awareness about the importance of water, society needs to take a three pronged approach: water needs to be effectively managed, it needs to be economically purified, and it needs to be conserved. Only by doing these three thingsmore » in unison can they hope to alleviate the water problems faced by arid regions of the world. This book presents information valuable to seeking, finding and using current technologies to help solve these problems now. Volume 1 examines water management problems in detail, along with water problems and water resources in arid climates, and includes chapters that cover aspects of water management. Water purification technology is another key issue. The economics of this technology is becoming more critical in arid areas due to increasing urbanization and industrialization.« less

Independent Transitions between Monsoonal and Arid Biomes Revealed by Systematic Revison of a Complex of Australian Geckos (Diplodactylus; Diplodactylidae)

PubMed Central

Oliver, Paul M.; Couper, Patrick J.; Pepper, Mitzy

2014-01-01

How the widespread expansion and intensification of aridity through the Neogene has shaped the Austral biota is a major question in Antipodean biogeography. Lineages distributed across wide aridity gradients provide opportunities to examine the timing, frequency, and direction of transitions between arid and mesic regions. Here, we use molecular genetics and morphological data to investigate the systematics and biogeography of a nominal Australian gecko species (Diplodactylus conspicillatus sensu lato) with a wide distribution spanning most of the Australian Arid Zone (AAZ) and Monsoonal Tropics (AMT). Our data support a minimum of seven genetically distinct and morphologically diagnosable taxa; we thus redefine the type species, ressurrect three names from synonymy, and describe three new species. Our inferred phylogeny suggests the history and diversification of lineages in the AAZ and AMT are intimately linked, with evidence of multiple independent interchanges since the late Miocene. However, despite this shared history, related lineages in these two regions also show evidence of broadly contrasting intra-regional responses to aridification; vicarance and speciation in older and increasingly attenuated mesic regions, versus a more dynamic history including independent colonisations and recent range expansions in the younger AAZ. PMID:25493936

Differentially regulated gene expression in quiescence versus senescence and identification of ARID5A as a quiescence associated marker.

PubMed

Anwar, Tarique; Sen, Bijoya; Aggarwal, Savera; Nath, Rhisita; Pathak, Niteen; Katoch, Ajay; Aiyaz, Mohamed; Trehanpati, Nirupma; Khosla, Sanjeev; Ramakrishna, Gayatri

2018-05-01

In multicellular organisms majority of the cells remain in a non-dividing states of either quiescence (reversible) or senescence (irreversible). In the present study, gene expression signatures unique to quiescence and senescence were identified using microarray in osteosarcoma cell line, U2OS. It was noted that certain genes and pathways like NOD pathway was shared by both the growth arrest conditions. A major highlight of the present study was increased expression of number of chemokines and cytokines in both quiescence and senescence. While senescence-associated secretory phenotype (SASP) is well known, the quiescence-associated secretory phenotype (QASP) is relatively unknown and appeared novel in this study. ARID5A, a subunit of SWI/SNF complex was identified as a quiescence associated gene. The endogenous expression of ARID5A increased during serum starved condition of quiescence. Overexpression of ARID5A resulted in more number of cells in G0/G1 phase of cell cycle. Further ARID5A overexpressing cells when subjected to serum starvation showed a pronounced secretory phenotype. Overall, the present work has identified gene expression signatures which can distinguish quiescence from senescence. © 2017 Wiley Periodicals, Inc.

Renal intraspecific variation along an aridity gradient detected by new renal indices in a desert herbivorous rodent.

PubMed

Tejo Riquelme, Patricia A; Diaz Isenrath, Gabriela B; Andino, Natalia; Borghi, Carlos E

2014-07-01

Mammals that live in arid and semi-arid environments in South America present physiological mechanisms that enable them to conserve water. Body water is lost through the kidneys, lungs, skin, and intestines. Regarding renal adaptation for water conservation, several indices have been used to estimate the capacity of the kidneys to produce a maximum urine concentration. Most studies were conducted at an inter-specific level, with only few performed at the intraspecific level. In this work, we compare renal function and morphology among five populations of Southern mountain cavy, Microcavia australis, present along an aridity gradient. We hypothesized that individuals from drier zones would present morphological and functional renal modifications that imply a greater capability to conserve body water. These features were studied considering the classical indices (RMT, PMT, PMA, and RMA) and three new indices that consider area measurements; the latter showed to be more adequate to reflect intraspecific differences. Our results suggest that the morphological modifications of kidneys, that is, the greater areas of renal inner medulla, would be related to the aridity gradient where populations of Southern mountain cavy occur. © 2014 Wiley Periodicals, Inc.

Improved highway design methods for desert storms

DOT National Transportation Integrated Search

2007-08-01

This report provides identification of desert hydrologic regions within the arid and semi-arid portions of California, as well as information and direction in choosing appropriate hydrologic and bulking methods specific to each identified desert regi...

Colonization patterns of soil microbial communities in the Atacama Desert.

PubMed

Crits-Christoph, Alexander; Robinson, Courtney K; Barnum, Tyler; Fricke, W Florian; Davila, Alfonso F; Jedynak, Bruno; McKay, Christopher P; Diruggiero, Jocelyne

2013-11-20

The Atacama Desert is one of the driest deserts in the world and its soil, with extremely low moisture, organic carbon content, and oxidizing conditions, is considered to be at the dry limit for life. Analyses of high throughput DNA sequence data revealed that bacterial communities from six geographic locations in the hyper-arid core and along a North-South moisture gradient were structurally and phylogenetically distinct (ANOVA test for observed operating taxonomic units at 97% similarity (OTU0.03), P <0.001) and that communities from locations in the hyper-arid zone displayed the lowest levels of diversity. We found bacterial taxa similar to those found in other arid soil communities with an abundance of Rubrobacterales, Actinomycetales, Acidimicrobiales, and a number of families from the Thermoleophilia. The extremely low abundance of Firmicutes indicated that most bacteria in the soil were in the form of vegetative cells. Integrating molecular data with climate and soil geochemistry, we found that air relative humidity (RH) and soil conductivity significantly correlated with microbial communities' diversity metrics (least squares linear regression for observed OTU0.03 and air RH and soil conductivity, P <0.001; UniFrac PCoA Spearman's correlation for air RH and soil conductivity, P <0.0001), indicating that water availability and salt content are key factors in shaping the Atacama soil microbiome. Mineralization studies showed communities actively metabolizing in all soil samples, with increased rates in soils from the southern locations. Our results suggest that microorganisms in the driest soils of the Atacama Desert are in a state of stasis for most of the time, but can potentially metabolize if presented with liquid water for a sufficient duration. Over geological time, rare rain events and physicochemical factors potentially played a major role in selecting micro-organisms that are most adapted to extreme desiccating conditions.

Impacts of the seasonal distribution of rainfall on vegetation productivity across the Sahel

NASA Astrophysics Data System (ADS)

Zhang, Wenmin; Brandt, Martin; Tong, Xiaoye; Tian, Qingjiu; Fensholt, Rasmus

2018-01-01

Climate change in drylands has caused alterations in the seasonal distribution of rainfall including increased heavy-rainfall events, longer dry spells, and a shifted timing of the wet season. Yet the aboveground net primary productivity (ANPP) in drylands is usually explained by annual-rainfall sums, disregarding the influence of the seasonal distribution of rainfall. This study tested the importance of rainfall metrics in the wet season (onset and cessation of the wet season, number of rainy days, rainfall intensity, number of consecutive dry days, and heavy-rainfall events) for growing season ANPP. We focused on the Sahel and northern Sudanian region (100-800 mm yr-1) and applied daily satellite-based rainfall estimates (CHIRPS v2.0) and growing-season-integrated normalized difference vegetation index (NDVI; MODIS) as a proxy for ANPP over the study period: 2001-2015. Growing season ANPP in the arid zone (100-300 mm yr-1) was found to be rather insensitive to variations in the seasonal-rainfall metrics, whereas vegetation in the semi-arid zone (300-700 mm yr-1) was significantly impacted by most metrics, especially by the number of rainy days and timing (onset and cessation) of the wet season. We analysed critical breakpoints for all metrics to test if vegetation response to changes in a given rainfall metric surpasses a threshold beyond which vegetation functioning is significantly altered. It was shown that growing season ANPP was particularly negatively impacted after > 14 consecutive dry days and that a rainfall intensity of ˜ 13 mm day-1 was detected for optimum growing season ANPP. We conclude that the number of rainy days and the timing of the wet season are seasonal-rainfall metrics that are decisive for favourable vegetation growth in the semi-arid Sahel and need to be considered when modelling primary productivity from rainfall in the drylands of the Sahel and elsewhere.

Water in the critical zone: soil, water and life from profile to planet

NASA Astrophysics Data System (ADS)

Kirkby, Mike

2015-04-01

Water is essential to the critical zone between bedrock and the atmosphere, and without water the soil is dead. Water provides the basis for the abundant life within the soil and, interacting with micro-organisms, drives the key processes in the critical zone. This review looks at the balances that control the flow of water through the soil, and how water movement is one of the major controls on the fluxes and transformations that control the formation, evolution and loss of material that controls the 'life' and 'health' of the soil. At regional scales, climate, acting largely through the soil hydrology, plays a major part in determining the type of soils developed - from hyper arid soils dominated by aeolian inputs, through arid and semi-arid soils with largely vertical water exchanges with the atmosphere, to temperate soils with substantial lateral drainage, and humid soils dominated by organic peats. Soil water balance controls the partition of precipitation between evaporative loss, lateral subsurface flow and groundwater recharge, and, in turn, has a major influence on the potential for plant growth and on the lateral connectivity between soils on a hillslope. Sediment and solute balances distinguish soils of accumulation from soils that tend towards a stable chemical depletion ratio. Reflecting the availability of water and the soil material, carbon balance plays a major role in soil horizonation and distinguishes soils dominated by mineral or organic components. At finer catena and catchment scales, lateral connectivity, or its absence, determines how soils evolve through the transfer of water and sediment downslope, creating more or less integrated landscapes in a balance between geomorphological and pedological processes. Within single soil profiles, the movement of water controls the processes of weathering and soil horizonation by ion diffusion, advective leaching and bioturbation, creating horizonation that, in turn, modifies the hydrological responses of both soil and landscape. For example, the soil hydrological regime helps to contrast soils that accumulate more and less soluble constituents of the parent material.

Unveiling the diversification dynamics of Australasian predaceous diving beetles in the Cenozoic.

PubMed

Toussaint, Emmanuel F A; Condamine, Fabien L; Hawlitschek, Oliver; Watts, Chris H; Porch, Nick; Hendrich, Lars; Balke, Michael

2015-01-01

During the Cenozoic, Australia experienced major climatic shifts that have had dramatic ecological consequences for the modern biota. Mesic tropical ecosystems were progressively restricted to the coasts and replaced by arid-adapted floral and faunal communities. Whilst the role of aridification has been investigated in a wide range of terrestrial lineages, the response of freshwater clades remains poorly investigated. To gain insights into the diversification processes underlying a freshwater radiation, we studied the evolutionary history of the Australasian predaceous diving beetles of the tribe Hydroporini (147 described species). We used an integrative approach including the latest methods in phylogenetics, divergence time estimation, ancestral character state reconstruction, and likelihood-based methods of diversification rate estimation. Phylogenies and dating analyses were reconstructed with molecular data from seven genes (mitochondrial and nuclear) for 117 species (plus 12 outgroups). Robust and well-resolved phylogenies indicate a late Oligocene origin of Australasian Hydroporini. Biogeographic analyses suggest an origin in the East Coast region of Australia, and a dynamic biogeographic scenario implying dispersal events. The group successfully colonized the tropical coastal regions carved by a rampant desertification, and also colonized groundwater ecosystems in Central Australia. Diversification rate analyses suggest that the ongoing aridification of Australia initiated in the Miocene contributed to a major wave of extinctions since the late Pliocene probably attributable to an increasing aridity, range contractions and seasonally disruptions resulting from Quaternary climatic changes. When comparing subterranean and epigean genera, our results show that contrasting mechanisms drove their diversification and therefore current diversity pattern. The Australasian Hydroporini radiation reflects a combination of processes that promoted both diversification, resulting from new ecological opportunities driven by initial aridification, and a subsequent loss of mesic adapted diversity due to increasing aridity. © The Author(s) 2014. Published by Oxford University Press, on behalf of the Society of Systematic Biologists. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Colonization patterns of soil microbial communities in the Atacama Desert

PubMed Central

2013-01-01

Background The Atacama Desert is one of the driest deserts in the world and its soil, with extremely low moisture, organic carbon content, and oxidizing conditions, is considered to be at the dry limit for life. Results Analyses of high throughput DNA sequence data revealed that bacterial communities from six geographic locations in the hyper-arid core and along a North-South moisture gradient were structurally and phylogenetically distinct (ANOVA test for observed operating taxonomic units at 97% similarity (OTU0.03), P <0.001) and that communities from locations in the hyper-arid zone displayed the lowest levels of diversity. We found bacterial taxa similar to those found in other arid soil communities with an abundance of Rubrobacterales, Actinomycetales, Acidimicrobiales, and a number of families from the Thermoleophilia. The extremely low abundance of Firmicutes indicated that most bacteria in the soil were in the form of vegetative cells. Integrating molecular data with climate and soil geochemistry, we found that air relative humidity (RH) and soil conductivity significantly correlated with microbial communities’ diversity metrics (least squares linear regression for observed OTU0.03 and air RH and soil conductivity, P <0.001; UniFrac PCoA Spearman’s correlation for air RH and soil conductivity, P <0.0001), indicating that water availability and salt content are key factors in shaping the Atacama soil microbiome. Mineralization studies showed communities actively metabolizing in all soil samples, with increased rates in soils from the southern locations. Conclusions Our results suggest that microorganisms in the driest soils of the Atacama Desert are in a state of stasis for most of the time, but can potentially metabolize if presented with liquid water for a sufficient duration. Over geological time, rare rain events and physicochemical factors potentially played a major role in selecting micro-organisms that are most adapted to extreme desiccating conditions. PMID:24451153

Prediction of daily spring hydrographs for future climatic scenarios based on an integrated numerical modelling approach: Application on a snow-governed semi- arid karst catchment area.

NASA Astrophysics Data System (ADS)

Doummar, J.; Kassem, A.; Gurdak, J. J.

2017-12-01

In the framework of a three-year USAID/NSF- funded PEER Science project, flow in a karst system in Lebanon (Assal Spring; discharge 0.2-2.5 m3/s yearly volume of 22-30 Mm3) dominated by snow and semi arid conditions was simulated using an integrated numerical model (Mike She 2016). The calibrated model (Nash-Sutcliffe coefficient of 0.77) is based on high resolution input data (2014-2017) and detailed catchment characterization. The approach is to assess the influence of various model parameters on recharge signals in the different hydrological karst compartments (Atmosphere, unsaturated zone, and saturated zone) based on an integrated numerical model. These parameters include precipitation intensity and magnitude, temperature, snow-melt parameters, in addition to karst specific spatially distributed features such as fast infiltration points, soil properties and thickness, topographical slopes, Epikarst and thickness of unsaturated zone, and hydraulic conductivity among others. Moreover, the model is currently simulated forward using various scenarios for future climate (Global Climate Models GCM; daily downscaled temperature and precipitation time series for Lebanon 2020-2045) in order to depict the flow rates expected in the future and the effect of climate change on hydrographs recession coefficients, discharge maxima and minima, and total spring discharge volume . Additionally, a sensitivity analysis of individual or coupled major parameters allows quantifying their impact on recharge or indirectly on the vulnerability of the system (soil thickness, soil and rock hydraulic conductivity appear to be amongst the highly sensitive parameters). This study particularly unravels the normalized single effect of rain magnitude and intensity, snow, and temperature change on the flow rate (e.g., a change of temperature of 3° on the catchment yields a Residual Mean Square Error RMSE of 0.15 m3/s in the spring discharge and a 16% error in the total annual volume with respect to the calibrated model). Finally, such a study can allow decision makers to implement best informed management practices, especially in complex karst systems, to overcome impacts of climate change on water resources.

Earth observing data and methods for advancing water harvesting technologies in the semi-arid rain-fed environments of India

USGS Publications Warehouse

Sharma, C.; Thenkabail, P.; Sharma, R. R.

2011-01-01

The paper develops approaches and methods of modeling and mapping land and water productivity of rain-fed crops in semi-arid environments of India using hyperspectral, hyperspatial, and advanced multispectral remote sensing data and linking the same to field-plot data and climate station data. The overarching goal is to provide information to advance water harvesting technologies in the agricultural croplands of the semi-arid environments of India by conducting research in a representative pilot site in Jodhpur, Rajasthan, India. ?? 2011 IEEE.

Vadose Zone Hydrology and Eco-hydrology in China

NASA Astrophysics Data System (ADS)

Wang, Wenke

2016-04-01

Vadose zone hydrology has long been a concern regarding groundwater recharge, evaporation, pollution, and the ecological effects induced by groundwater and water & salt contents in the unsaturated zone. The greater difference between day and night temperatures in arid and semi-arid areas influences water movement and heat transport in the vadose zone, and further influences the water and heat fluxes between the water table and the atmosphere as well as ecological environment. Unfortunately, these studies are lack in a systematic viewpoint in China. One of the main reasons is that the movement of water, vapor and heat from the surface to the water table is very complex in the arid and semi-arid areas. Another reason is lack of long term field observations for water content, vapor, heat, and soil matrix potential in the vadose zone. Three field observation sites, designed by the author, were set up to measure the changes in climate, water content , temperature and soil matrix potential of the unsaturated zone and groundwater level under the different conditions of climate and soil types over the period of 1-5 years. They are located at the Zhunngger Basin of Xinjing Uygur Autonomous Region in northwestern China, the Guanzhong Basin of Shaanxi Province in central China, and the Ordos Basin of the Inner Monggol Autonomous Region in north China, respectively. These three field observation sites have different climate and soil types in the vadose zone and the water table depth are also varied. Based on the observation data of climate, groundwater level, water content, temperature and soil matrix potential in the vadose zone from the three sites in associated with the field survey and numerical simulation method, the water movement and heat transport in the vadose zone, and the evaporation of phreatic water for different groundwater depths and soil types have been well explored. The differences in water movement of unsaturated zone between the bare surface soil and vegetation conditions were also compared. The concept of the ecological value of groundwater and unsaturated zone is presented in arid and semi-arid regions. This ecological value can be reflected in four aspects:(1) the maintenance of base flow in streams and areas of lakes and wetland;(2) the supply of physiological water demented by vegetation;(3) the regulation of soil moisture and salt content; and (4) the stability of the eco-environment. In addition, the threshold system between the ecological environment and multi-dimensional indices as variations in water and salt contents in the vadose zone, groundwater depth and quality as well as groundwater exploitation, are proposed in the arid and semi-arid areas. It is expected that this research could provide a scientific basis and technological support for better understanding on the movement of water, vapor and heat in the vadose zone in arid and semi-arid areas. It will also help to maintain sustainable development of the ecological environment and utilization of water resources.

Aridity and grazing as convergent selective forces: an experiment with an Arid Chaco bunchgrass.

PubMed

Quiroga, R Emiliano; Golluscio, Rodolfo A; Blanco, Lisandro J; Fernández, Roberto J

2010-10-01

It has been proposed that aridity and grazing are convergent selective forces: each one selects for traits conferring resistance to both. However, this conceptual model has not yet been experimentally validated. The aim of this work was to experimentally evaluate the effect of aridity and grazing, as selective forces, on drought and grazing resistance of populations of Trichloris crinita, a native perennial forage grass of the Argentinean Arid Chaco region. We collected seeds in sites with four different combinations of aridity and grazing history (semiarid/ subhumid x heavily grazed/lightly grazed), established them in pots in a common garden, and subjected the resulting plants to different combinations of drought and defoliation. Our results agreed with the convergence model. Aridity has selected T. crinita genotypes that respond better to drought and defoliation in terms of sexual reproduction and leaf growth, and that can evade grazing due to a lower shoot: root ratio and a higher resource allocation to reserves (starch) in stem bases. Similarly, grazing has selected genotypes that respond better to drought and defoliation in terms of sexual reproduction and that can evade grazing due to a lower digestibility of leaf blades. These results allow us to extend concepts of previous models in plant adaptation to herbivory to models on plant adaptation to drought. The only variable in which we obtained a result opposite to predictions was plant height, as plants from semiarid sites were taller (and with more erect tillers) than plants from subhumid sites; we hypothesize that this result might have been a consequence of the selection exerted by the high solar radiation and soil temperatures of semiarid sites. In addition, our work allows for the prediction of the effects of dry or wet growing seasons on the performance of T. crinita plants. Our results suggest that we can rely on dry environments for selecting grazing-resistant genotypes and on high grazing pressure history environments for selecting drought-resistant ones.

The Climate Effect of the Topographies at the Northern Margin of the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Sha, Y.; Shi, Z.; Liu, X.

2017-12-01

The Tibetan Plateau play a crucial role in the formation and evolution of the Asian monsoon-interior aridity climate system. However, the climate effect of other relatively smaller topographies receives less attention. Based on high-resolved general circulation models, we conducted a series of sensitive experiments as with/without mountains, which include the Mongolian Plateau and the Tian Shan Mountains. The numerical simulations reveal the important impacts of the mountain ranges at the northern margins of the Tibetan Plateau. Compared to the main body of the Tibetan Plateau, the uplift of the Mongolian Plateau is essential for the establishment of the strong Siberian High. The East Asian winter monsoon and the westerly jet over the North Pacific Ocean are also significantly strengthened. At present, the Tian Shan Mountains geographically separate the arid interior Asia to the west and east sub-regions. However, the arid west sub-region (Central Asia) and the east sub-region (arid northwestern China) was connected as one large arid region before the uplift of the Tian Shan Mountains. The large arid interior land shares the same precipitation seasonality, with most rains fall in spring and winter while lowest precipitation in summer. After the uplift of the Tian Shan, the large arid region is divided into the west and east sub-regions by the wetter uplifted mountain ranges. More importantly, the precipitation seasonality in the east of the Tian Shan is reversed to be the summer-peak type, which is opposite to that in the Central Asia. The precipitation alteration corresponds well with the change of vertical motion. By the conservation of potential vorticity, the atmosphere stationary waves are modulated. Thus, the remote East Asian monsoon is also modulated. Though enhanced southerly wind blows over East Asia, the monsoon precipitation over the east coast of China and subtropical western Pacific Ocean is significantly reduced as an anticyclonic circulation appears. The Tian Shan also contributes to the intensification of the East Asian winter monsoon.

Quality Variation of Goji (Fruits of Lycium spp.) in China: A Comparative Morphological and Metabolomic Analysis

PubMed Central

Yao, Ruyu; Heinrich, Michael; Zou, Yuanfeng; Reich, Eike; Zhang, Xiaolei; Chen, Yu; Weckerle, Caroline S.

2018-01-01

Goji (fruits of Lycium barbarum L. and L. chinense Mill.) has been used in China as food and medicine for millennia, and globally has been consumed increasingly as a healthy food. Ningxia, with a semi-arid climate, always had the reputation of producing best goji quality (daodi area). Recently, the increasing market demand pushed the cultivation into new regions with different climates. We therefore ask: How does goji quality differ among production areas of various climatic regions? Historical records are used to trace the spread of goji production in China over time. Quality measurements of 51 samples were correlated with the four main production areas in China: monsoon (Hebei), semi-arid (Ningxia, Gansu, and Inner Mongolia), plateau (Qinghai) and arid regions (Xinjiang). We include morphological characteristics, sugar and polysaccharide content, antioxidant activity, and metabolomic profiling to compare goji among climatic regions. Goji cultivation probably began in the East (Hebei) of China around 100 CE and later shifted westward to the semi-arid regions. Goji from monsoon, plateau and arid regions differ according to its fruit morphology, whereas semi-arid goji cannot be separated from the other regions. L. chinense fruits, which are exclusively cultivated in Hebei (monsoon), are significantly lighter, smaller and brighter in color, while the heaviest and largest fruits (L. barbarum) stem from the plateau. The metabolomic profiling separates the two species but not the regions of cultivation. Lycium chinense and samples from the semi-arid regions have significantly (p < 0.01) lower sugar contents and L. chinense shows the highest antioxidant activity. Our results do not justify superiority of a specific production area over other areas. Instead it will be essential to distinguish goji from different regions based on the specific morphological and chemical traits with the aim to understand what its intended uses are. PMID:29535631

Karst characterization in a semi-arid region using gravity, seismic, and resistivity geophysical techniques.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barnhart, Kevin Scott

2013-10-01

We proposed to customize emerging in situ geophysical monitoring technology to generate time-series data during sporadic rain events in a semi-arid region. Electrodes were to be connected to wireless \

Organic textile waste as a resource for sustainable agriculture in arid and semi-arid areas.

PubMed

Eriksson, Bo G

2017-03-01

New vegetation in barren areas offers possibilities for sequestering carbon in the soil. Arid and semi-arid areas (ASAs) are candidates for new vegetation. The possibility of agriculture in ASAs is reviewed, revealing the potential for cultivation by covering the surface with a layer of organic fibres. This layer collects more water from humidity in the air than does the uncovered mineral surface, and creates a humid environment that promotes microbial life. One possibility is to use large amounts of organic fibres for soil enhancement in ASAs. In the context of the European Commission Waste Framework Directive, the possibility of using textile waste from Sweden is explored. The costs for using Swedish textile waste are high, but possible gains are the sale of agricultural products and increased land prices as well as environmental mitigation. The findings suggest that field research on such agriculture in ASAs should start as soon as possible.

Three Millennia of Southwestern North American Dustiness and Future Implications

PubMed Central

Routson, Cody C.; Overpeck, Jonathan T.; Woodhouse, Connie A.; Kenney, William F.

2016-01-01

Two sediment records of dust deposition from Fish Lake, in southern Colorado, offer a new perspective on southwest United States (Southwest) aridity and dustiness over the last ~3000 years. Micro scanning X-ray fluorescence and grain size analysis provide separate measures of wind-deposited dust in the lake sediment. Together these new records confirm anomalous dustiness in the 19th and 20th centuries, associated with recent land disturbance, drought, and livestock grazing. Before significant anthropogenic influences, changes in drought frequency and aridity also generated atmospheric dust loading. Medieval times were associated with high levels of dustiness, coincident with widespread aridity. These records indicate the Southwest is naturally prone to dustiness. As global and regional temperatures rise and the Southwest shifts toward a more arid landscape, the Southwest will likely become dustier, driving negative impacts on snowpack and water availability, as well as human health. PMID:26886350

Increasing aridity reduces soil microbial diversity and abundance in global drylands.

PubMed

Maestre, Fernando T; Delgado-Baquerizo, Manuel; Jeffries, Thomas C; Eldridge, David J; Ochoa, Victoria; Gozalo, Beatriz; Quero, José Luis; García-Gómez, Miguel; Gallardo, Antonio; Ulrich, Werner; Bowker, Matthew A; Arredondo, Tulio; Barraza-Zepeda, Claudia; Bran, Donaldo; Florentino, Adriana; Gaitán, Juan; Gutiérrez, Julio R; Huber-Sannwald, Elisabeth; Jankju, Mohammad; Mau, Rebecca L; Miriti, Maria; Naseri, Kamal; Ospina, Abelardo; Stavi, Ilan; Wang, Deli; Woods, Natasha N; Yuan, Xia; Zaady, Eli; Singh, Brajesh K

2015-12-22

Soil bacteria and fungi play key roles in the functioning of terrestrial ecosystems, yet our understanding of their responses to climate change lags significantly behind that of other organisms. This gap in our understanding is particularly true for drylands, which occupy ∼41% of Earth´s surface, because no global, systematic assessments of the joint diversity of soil bacteria and fungi have been conducted in these environments to date. Here we present results from a study conducted across 80 dryland sites from all continents, except Antarctica, to assess how changes in aridity affect the composition, abundance, and diversity of soil bacteria and fungi. The diversity and abundance of soil bacteria and fungi was reduced as aridity increased. These results were largely driven by the negative impacts of aridity on soil organic carbon content, which positively affected the abundance and diversity of both bacteria and fungi. Aridity promoted shifts in the composition of soil bacteria, with increases in the relative abundance of Chloroflexi and α-Proteobacteria and decreases in Acidobacteria and Verrucomicrobia. Contrary to what has been reported by previous continental and global-scale studies, soil pH was not a major driver of bacterial diversity, and fungal communities were dominated by Ascomycota. Our results fill a critical gap in our understanding of soil microbial communities in terrestrial ecosystems. They suggest that changes in aridity, such as those predicted by climate-change models, may reduce microbial abundance and diversity, a response that will likely impact the provision of key ecosystem services by global drylands.

Increasing aridity reduces soil microbial diversity and abundance in global drylands

PubMed Central

Delgado-Baquerizo, Manuel; Jeffries, Thomas C.; Eldridge, David J.; Ochoa, Victoria; Gozalo, Beatriz; Quero, José Luis; García-Gómez, Miguel; Gallardo, Antonio; Ulrich, Werner; Bowker, Matthew A.; Arredondo, Tulio; Barraza-Zepeda, Claudia; Bran, Donaldo; Florentino, Adriana; Gaitán, Juan; Gutiérrez, Julio R.; Huber-Sannwald, Elisabeth; Jankju, Mohammad; Mau, Rebecca L.; Miriti, Maria; Naseri, Kamal; Ospina, Abelardo; Stavi, Ilan; Wang, Deli; Woods, Natasha N.; Yuan, Xia; Zaady, Eli; Singh, Brajesh K.

2015-01-01

Soil bacteria and fungi play key roles in the functioning of terrestrial ecosystems, yet our understanding of their responses to climate change lags significantly behind that of other organisms. This gap in our understanding is particularly true for drylands, which occupy ∼41% of Earth´s surface, because no global, systematic assessments of the joint diversity of soil bacteria and fungi have been conducted in these environments to date. Here we present results from a study conducted across 80 dryland sites from all continents, except Antarctica, to assess how changes in aridity affect the composition, abundance, and diversity of soil bacteria and fungi. The diversity and abundance of soil bacteria and fungi was reduced as aridity increased. These results were largely driven by the negative impacts of aridity on soil organic carbon content, which positively affected the abundance and diversity of both bacteria and fungi. Aridity promoted shifts in the composition of soil bacteria, with increases in the relative abundance of Chloroflexi and α-Proteobacteria and decreases in Acidobacteria and Verrucomicrobia. Contrary to what has been reported by previous continental and global-scale studies, soil pH was not a major driver of bacterial diversity, and fungal communities were dominated by Ascomycota. Our results fill a critical gap in our understanding of soil microbial communities in terrestrial ecosystems. They suggest that changes in aridity, such as those predicted by climate-change models, may reduce microbial abundance and diversity, a response that will likely impact the provision of key ecosystem services by global drylands. PMID:26647180

Determine the optimum spectral reflectance of juniper and pistachio in arid and semi-arid region

NASA Astrophysics Data System (ADS)

Fadaei, Hadi; Suzuki, Rikie

2012-11-01

Arid and semi-arid areas of northeast Iran cover about 3.4 million ha are populated by two main tree species, the broadleaf Pistacia vera. L (pistachio) and the conifer Juniperus excelsa ssp. polycarpos (Persian juniper). Natural stands of pistachio in Iran are not only environmentally important but genetically essential as seed sources for pistachio production in orchards. In this study, we estimated the optimum spectral reflectance of juniper forests and natural pistachio stands using remote sensing to help in the sustainable management and production of pistachio in Iran. In this research spectral reflectance are able to specify of multispectral from Advanced Land Observing Satellite (ALOS) that provided by JAXA. These data included PRISM is a panchromatic radiometer with a 2.5 m spatial resolution at nadir, has one band with a wavelength of 0.52-0.77 μm and AVNIR-2 is a visible and near infrared radiometer for observing land and coastal zones with a 10 m spatial resolution at nadir, has four multispectral bands: blue (0.42-0.50 μm), green (0.52-0.60 μm), red (0.61-0.69 μm), and near infrared (0.76-0.89 μm). Total ratio vegetation index (TRVI) of optimum spectral reflectance of juniper and pistachio have been evaluated. The result of TRVI for Pistachio and juniper were (R2= 0.71 and 0.55). I hope this research can provide decision of managers to helping sustainable management for arid and semi-arid regions in Iran.

Aridity under conditions of increased CO2

NASA Astrophysics Data System (ADS)

Greve, Peter; Roderick, Micheal L.; Seneviratne, Sonia I.

2016-04-01

A string of recent of studies led to the wide-held assumption that aridity will increase under conditions of increasing atmospheric CO2 concentrations and associated global warming. Such results generally build upon analyses of changes in the 'aridity index' (the ratio of potential evaporation to precipitation) and can be described as a direct thermodynamic effect on atmospheric water demand due to increasing temperatures. However, there is widespread evidence that contradicts the 'warmer is more arid' interpretation, leading to the 'global aridity paradox' (Roderick et al. 2015, WRR). Here we provide a comprehensive assessment of modeled changes in a broad set of dryness metrics (primarily based on a range of measures of water availability) over a large range of realistic atmospheric CO2 concentrations. We use an ensemble of simulations from of state-of-the-art climate models to analyse both equilibrium climate experiments and transient historical simulations and future projections. Our results show that dryness is, under conditions of increasing atmospheric CO2 concentrations and related global warming, generally decreasing at global scales. At regional scales we do, however, identify areas that undergo changes towards drier conditions, located primarily in subtropical climate regions and the Amazon Basin. Nonetheless, the majority of regions, especially in tropical and mid- to northern high latitudes areas, display wetting conditions in a warming world. Our results contradict previous findings and highlight the need to comprehensively assess all aspects of changes in hydroclimatological conditions at the land surface. Roderick, M. L., P. Greve, and G. D. Farquhar (2015), On the assessment of aridity with changes in atmospheric CO2, Water Resour. Res., 51, 5450-5463

New Possibilities for High-Resolution, Large-Scale Ecosystem Assessment of the World's Semi-Arid Regions

NASA Astrophysics Data System (ADS)

Burney, J. A.; Goldblatt, R.

2016-12-01

Understanding drivers of land use change - and in particular, levels of ecosystem degradation - in semi-arid regions is of critical importance because these agroecosystems (1) are home to the world's poorest populations, almost all of whom depend on agriculture for their livelihoods, (2) play a critical role in the global carbon and climate cycles, and (3) have in many cases seen dramatic changes in temperature and precipitation, relative to global averages, over the past several decades. However, assessing ecosystem health (or, conversely, degradation) presents a difficult measurement problem. Established methods are very labor intensive and rest on detailed questionnaires and field assessments. High-resolution satellite imagery has a unique role semi-arid ecosystem assessment in that it can be used for rapid (or repeated) and very simple measurements of tree and shrub density, an excellent overall indicator for dryland ecosystem health. Because trees and large shrubs are more sparse in semi-arid regions, sub-meter resolution imagery in conjunction with automated image analysis can be used to assess density differences at high spatial resolution without expensive and time-consuming ground-truthing. This could be used down to the farm level, for example, to better assess the larger-scale ecosystem impacts of different management practices, to assess compliance with REDD+ carbon offset protocols, or to evaluate implementation of conservation goals. Here we present results comparing spatial and spectral remote sensing methods for semi-arid ecosystem assessment across new data sources, using the Brazilian Sertão as an example, and the implications for large-scale use in semi-arid ecosystem science.

Microarray pathway analysis indicated that mitogen-activated protein kinase/extracellular signal-regulated kinase and insulin growth factor 1 signaling pathways were inhibited by small interfering RNA against AT-rich interactive domain 1A in endometrial cancer

PubMed Central

Yang, Ye; Bao, Wei; Sang, Zhengyu; Yang, Yongbing; Lu, Meng; Xi, Xiaowei

2018-01-01

Mutations in the gene encoding AT-rich interactive domain 1A (ARID1A) are frequently observed in endometrial cancer (EC) but the molecular mechanisms linking the genetic changes remain to be fully understood. The present study aimed to elucidate the influence of ARID1A mutations on signaling pathways. Missense, synonymous and nonsense heterozygous ARID1A mutations in the EC HEC-1-A cell line were verified by Sanger sequencing. Mutated ARID1A small interfering RNA was transfected into HEC-1-A cells. Biochemical microarray analysis revealed 13 upregulated pathways, 17 downregulated pathways, 14 significantly affected disease states and functions, 662 upstream and 512 downstream genes in mutated ARID1A-depleted HEC-1-A cells, among which the mitogen-activated protein kinase/extracellular signal-regulated kinase and insulin-like growth factor-1 (IGF1) signaling pathways were the 2 most downregulated pathways. Furthermore, the forkhead box protein O1 pathway was upregulated, while the IGF1 receptor, insulin receptor substrate 1 and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit b pathways were downregulated. Carcinoma tumorigenesis, tumor cell mitosis and tumor cell death were significantly upregulated disease states and functions, while cell proliferation and tumor growth were significantly downregulated. The results of the present study suggested that ARID1A may be a potential prognostic and therapeutic molecular drug target for the prevention of EC progression. PMID:29399196

Prognostic and Clinicopathological Significance of ARID1A in Endometrium-Related Gynecological Cancers: A Meta-Analysis.

PubMed

Liu, Guangquan; Xu, Pengfei; Fu, Ziyi; Hua, Xiangdong; Liu, Xiaoguang; Li, Wenqu; Zhang, Mi; Wu, Jiacong; Wen, Juan; Xu, Juan; Jia, Xuemei

2017-12-01

The tumor suppressor gene, AT Rich Interactive Domain 1A (ARID1A) mutation has been reported in a variety of cancers, especially the endometrium-related gynecological cancers, including the ovarian clear cell carcinoma, ovarian endometrioid carcinoma, and uterine endometrioid carcinoma. However, the prognostic value of ARID1A in endometrium-related gynecological cancers is still inconclusive. Therefore, we performed this meta-analysis to evaluate the clinical significance of ARID1A in endometrium-related gynecological cancers. By systematically searching all the relevant studies from Pubmed, Cochrane Library, and Web of Science up to September 2016, 11 studies with 1,432 patients were included. All the study characteristics and the prognostic data were extracted. Hazard ratios (HRs) and 95% confidence intervals (CIs) were pooled using the fixed-effect or random-effect model. Our results indicated that negative ARID1A expression predicted shorter Progression free survival (PFS, HR, 1.84; 95%CI, 1.32-2.57, P = 0.000) of patients with endometrium related gynecological cancers, especially the patiently with OCCC and the patients in Japan. Besides, a marginal trend towards the same direction was found in the Overall analysis (OS, HR, 1.34; 95%CI, 0.93-1.93, P = 0.112). Furthermore, the significant correlation was achieved between the negative ARID1A expression and the FIGO stage of endometrium-related gynecological cancers, but not the other characteristics. J. Cell. Biochem. 118: 4517-4525, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Apparent Overinvestment in Leaf Venation Relaxes Leaf Morphological Constraints on Photosynthesis in Arid Habitats1[OPEN

PubMed Central

de Boer, Hugo J.; Drake, Paul L.; Wendt, Erin; Price, Charles A.; Schulze, Ernst-Detlef; Turner, Neil C.; Nicolle, Dean

2016-01-01

Leaf veins supply the mesophyll with water that evaporates when stomata are open to allow CO2 uptake for photosynthesis. Theoretical analyses suggest that water is optimally distributed in the mesophyll when the lateral distance between veins (dx) is equal to the distance from these veins to the epidermis (dy), expressed as dx:dy ≈ 1. Although this theory is supported by observations of many derived angiosperms, we hypothesize that plants in arid environments may reduce dx:dy below unity owing to climate-specific functional adaptations of increased leaf thickness and increased vein density. To test our hypothesis, we assembled leaf hydraulic, morphological, and photosynthetic traits of 68 species from the Eucalyptus and Corymbia genera (termed eucalypts) along an aridity gradient in southwestern Australia. We inferred the potential gas-exchange advantage of reducing dx beyond dy using a model that links leaf morphology and hydraulics to photosynthesis. Our observations reveal that eucalypts in arid environments have thick amphistomatous leaves with high vein densities, resulting in dx:dy ratios that range from 1.6 to 0.15 along the aridity gradient. Our model suggests that, as leaves become thicker, the effect of reducing dx beyond dy is to offset the reduction in leaf gas exchange that would result from maintaining dx:dy at unity. This apparent overinvestment in leaf venation may be explained from the selective pressure of aridity, under which traits associated with long leaf life span, high hydraulic and thermal capacitances, and high potential rates of leaf water transport confer a competitive advantage. PMID:27784769

Weather and climate applications for rangeland restoration planning

USDA-ARS?s Scientific Manuscript database

Rangeland ecosystems generally have an arid or semi-arid climatology, and are characterized by relatively high variability in seasonal and annual patterns of precipitation. Weather variability during seedling establishment is universally acknowledged as a principal determinant of rangeland seeding...

Grassland-shrubland state transitions in arid rangelands: Competition matters

USDA-ARS?s Scientific Manuscript database

Background: State transition from grassland to shrubland is synonymous with desertification in many arid rangeland systems. Traditional desertification models emphasize abiotic feedbacks that modify the physical environment in ways that promote shrub proliferation and impede grass survival. Inherent...

Distribution of greenhouse gases in hyper-arid and arid areas of northern Chile and the contribution of the high altitude wetland microbiome (Salar de Huasco, Chile).

PubMed

Molina, Verónica; Eissler, Yoanna; Cornejo, Marcela; Galand, Pierre E; Dorador, Cristina; Hengst, Martha; Fernandez, Camila; Francois, Jean Pierre

2018-04-06

Northern Chile harbors different bioclimatic zones including hyper-arid and arid ecosystems and hotspots of microbial life, such as high altitude wetlands, which may contribute differentially to greenhouse gases (GHG) such as carbon dioxide (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O). In this study, we explored ground level GHG distribution and the potential role of a wetland situated at 3800 m.a.s.l, and characterized by high solar radiation < 1600 W m -2 , extreme temperature ranges (-12 to 24 °C) and wind stress (< 17 m s -1 ). The water source of the wetland is mainly groundwater springs, which generates streams and ponds surrounded by peatlands. These sites support a rich microbial aquatic life including diverse bacteria and archaea communities, which transiently form more complex structures, such as microbial mats. In this study, GHG were measured in the water and above ground level air at the wetland site and along an elevation gradient in different bioclimatic areas from arid to hyper-arid zones. The microbiome from the water and sediments was described by high-throughput sequencing 16S rRNA and rDNA genes. The results indicate that GHG at ground level were variable along the elevation gradient potentially associated with different bioclimatic zones, reaching high values at the high Andean steppe and variable but lower values in the Atacama Desert and at the wetland. The water areas of the wetland presented high concentrations of CH 4 and CO 2 , particularly at the spring areas and in air bubbles below microbial mats. The microbial community was rich (> 40 phyla), including archaea and bacteria potentially active in the different matrices studied (water, sediments and mats). Functional microbial groups associated with GHG recycling were detected at low frequency, i.e., < 2.5% of total sequences. Our results indicate that hyper-arid and arid areas of northern Chile are sites of GHG exchange associated with various bioclimatic zones and particularly in aquatic areas of the wetland where this ecosystem could represent a net sink of N 2 O and a source for CH 4 and CO 2 .

Green Infrastructure Design Evaluation Using the Automated Geospatial Watershed Assessment Tool

EPA Science Inventory

In arid and semi-arid regions, green infrastructure (GI) can address several issues facing urban environments, including augmenting water supply, mitigating flooding, decreasing pollutant loads, and promoting greenness in the built environment. An optimum design captures stormwat...

Evaluation of Green Infrastructure Designs Using the Automated Geospatial Watershed Assessment Tool

EPA Science Inventory

In arid and semi-arid regions, green infrastructure (GI) can address several issues facing urban environments, including augmenting water supply, mitigating flooding, decreasing pollutant loads, and promoting greenness in the built environment. An optimum design captures stormwat...

Gardens on the Arid Climate

NASA Astrophysics Data System (ADS)

Eka Saputra, Weldy

2017-12-01

Bahrain is located in the climate of the arid zone which rainfall is low and irregular. This paper discusses the approaches which response to the local context that has been implemented by the government of Bahrain to sustain the quality of the public garden in the arid climate, turning to green. Generally, the approach is an improvement in the central treatment of waste water system plant that used to irrigate the landscaping, agriculture as well as for industry use. These approaches are not the only technologically, but also involves the participation of community to achieve sustainable garden in this country.

Atmospheric Nitrogen Deposition at Two Sites in an Arid Environment of Central Asia.

PubMed

Li, Kaihui; Liu, Xuejun; Song, Wei; Chang, Yunhua; Hu, Yukun; Tian, Changyan

2013-01-01

Arid areas play a significant role in the global nitrogen cycle. Dry and wet deposition of inorganic nitrogen (N) species were monitored at one urban (SDS) and one suburban (TFS) site at Urumqi in a semi-arid region of central Asia. Atmospheric concentrations of NH3, NO2, HNO3, particulate ammonium and nitrate (pNH4 (+) and pNO3 (-)) concentrations and NH4-N and NO3-N concentrations in precipitation showed large monthly variations and averaged 7.1, 26.6, 2.4, 6.6, 2.7 µg N m(-3) and 1.3, 1.0 mg N L(-1) at both SDS and TFS. Nitrogen dry deposition fluxes were 40.7 and 36.0 kg N ha(-1) yr(-1) while wet deposition of N fluxes were 6.0 and 8.8 kg N ha(-1) yr(-1) at SDS and TFS, respectively. Total N deposition averaged 45.8 kg N ha(-1) yr(-1)at both sites. Our results indicate that N dry deposition has been a major part of total N deposition (83.8% on average) in an arid region of central Asia. Such high N deposition implies heavy environmental pollution and an important nutrient resource in arid regions.

Management implications of the ecology of free-roaming horses in semiarid ecosystems of the western United States

USGS Publications Warehouse

Beever, Erik

2003-01-01

Compared to other ungulates of North America, free-roaming horses (Equus caballus) possess a unique evolutionary history that has given rise to a distinct suite of behavioral, morphological, and physiological traits. Because of their unique combination of cecal digestion, an elongate head with flexible lips, and non-uniform use of the landscape, horses represent a unique disturbance agent in semi-arid ecosystems of the western United States. Consequently, it is inappropriate to assume that influences of horses on the structure, composition, function, and pattern of arid and semi-arid ecosystems will mirror influences of cattle or other artiodactyls. Although management areas for free-roaming horses occupy 18.6 million ha of land across western North America, we know relatively little about how western ecosystems and their components have responded to this uniquely managed ungulate. I draw on my research of horse habitats in the western Great Basin (U.S.A.) to examine predictions of horses' unique influence, and advocate for continued research to refine our understanding of synecological relationships among horses and diverse ecosystem components in arid and semi-arid regions. 

Precipitation and carbon-water coupling jointly control the interannual variability of global land gross primary production

NASA Astrophysics Data System (ADS)

Zhang, Yao; Xiao, Xiangming; Guanter, Luis; Zhou, Sha; Ciais, Philippe; Joiner, Joanna; Sitch, Stephen; Wu, Xiaocui; Nabel, Julia; Dong, Jinwei; Kato, Etsushi; Jain, Atul K.; Wiltshire, Andy; Stocker, Benjamin D.

2016-12-01

Carbon uptake by terrestrial ecosystems is increasing along with the rising of atmospheric CO2 concentration. Embedded in this trend, recent studies suggested that the interannual variability (IAV) of global carbon fluxes may be dominated by semi-arid ecosystems, but the underlying mechanisms of this high variability in these specific regions are not well known. Here we derive an ensemble of gross primary production (GPP) estimates using the average of three data-driven models and eleven process-based models. These models are weighted by their spatial representativeness of the satellite-based solar-induced chlorophyll fluorescence (SIF). We then use this weighted GPP ensemble to investigate the GPP variability for different aridity regimes. We show that semi-arid regions contribute to 57% of the detrended IAV of global GPP. Moreover, in regions with higher GPP variability, GPP fluctuations are mostly controlled by precipitation and strongly coupled with evapotranspiration (ET). This higher GPP IAV in semi-arid regions is co-limited by supply (precipitation)-induced ET variability and GPP-ET coupling strength. Our results demonstrate the importance of semi-arid regions to the global terrestrial carbon cycle and posit that there will be larger GPP and ET variations in the future with changes in precipitation patterns and dryland expansion.

A mesic maximum in biological water use demarcates biome sensitivity to aridity shifts.

PubMed

Good, Stephen P; Moore, Georgianne W; Miralles, Diego G

2017-12-01

Biome function is largely governed by how efficiently available resources can be used and yet for water, the ratio of direct biological resource use (transpiration, E T ) to total supply (annual precipitation, P) at ecosystem scales remains poorly characterized. Here, we synthesize field, remote sensing and ecohydrological modelling estimates to show that the biological water use fraction (E T /P) reaches a maximum under mesic conditions; that is, when evaporative demand (potential evapotranspiration, E P ) slightly exceeds supplied precipitation. We estimate that this mesic maximum in E T /P occurs at an aridity index (defined as E P /P) between 1.3 and 1.9. The observed global average aridity of 1.8 falls within this range, suggesting that the biosphere is, on average, configured to transpire the largest possible fraction of global precipitation for the current climate. A unimodal E T /P distribution indicates that both dry regions subjected to increasing aridity and humid regions subjected to decreasing aridity will suffer declines in the fraction of precipitation that plants transpire for growth and metabolism. Given the uncertainties in the prediction of future biogeography, this framework provides a clear and concise determination of ecosystems' sensitivity to climatic shifts, as well as expected patterns in the amount of precipitation that ecosystems can effectively use.

Evaporation as the transport mechanism of metals in arid regions.

PubMed

Lima, Ana T; Safar, Zeinab; Loch, J P Gustav

2014-09-01

Soils of arid regions are exposed to drought and drastic temperature oscillations throughout the year. Transport mechanisms in these soils are therefore very different from the ones in temperate regions, where rain dictates the fate of most elements in soils. Due to the low rainfall and high evaporation rates in arid regions, groundwater quality is not threatened and all soil contamination issues tend to be overlooked. But if soil contamination happens, where do contaminants go? This study tests the hypothesis of upward metal movement in soils when evaporation is the main transport mechanism. Laboratory evaporation tests were carried out with heavy metal spiked Saudi soil, using circulation of air as the driving force (Fig. 1). Main results show that loamy soil retains heavy metals quite well while evaporation drives heavy metals to the surface of a sandy soil. Evaporation transports heavy metals upward in sandy soils of arid regions, making them accumulate at the soil surface. Sand being the dominating type of soil in arid regions, soils can then be a potential source of contaminated aerosols and atmospheric pollution - a transboundary problem. Some other repercussions for this problem are foreseen, such as the public ingestion or inhalation of dust. Copyright © 2014 Elsevier Ltd. All rights reserved.

75 years of dryland science: Trends and gaps in arid ecology literature.

PubMed

Greenville, Aaron C; Dickman, Chris R; Wardle, Glenda M

2017-01-01

Growth in the publication of scientific articles is occurring at an exponential rate, prompting a growing need to synthesise information in a timely manner to combat urgent environmental problems and guide future research. Here, we undertake a topic analysis of dryland literature over the last 75 years (8218 articles) to identify areas in arid ecology that are well studied and topics that are emerging. Four topics-wetlands, mammal ecology, litter decomposition and spatial modelling, were identified as 'hot topics' that showed higher than average growth in publications from 1940 to 2015. Five topics-remote sensing, climate, habitat and spatial, agriculture and soils-microbes, were identified as 'cold topics', with lower than average growth over the survey period, but higher than average numbers of publications. Topics in arid ecology clustered into seven broad groups on word-based similarity. These groups ranged from mammal ecology and population genetics, broad-scale management and ecosystem modelling, plant ecology, agriculture and ecophysiology, to populations and paleoclimate. These patterns may reflect trends in the field of ecology more broadly. We also identified two broad research gaps in arid ecology: population genetics, and habitat and spatial research. Collaborations between population genetics and ecologists and investigations of ecological processes across spatial scales would contribute profitably to the advancement of arid ecology and to ecology more broadly.

Effects of climate on the productivity of desert truffles beneath hyper-arid conditions.

PubMed

Bradai, Lyès; Bissati, Samia; Chenchouni, Haroun; Amrani, Khaled

2015-07-01

Desert truffles are edible hypogenous fungi that are very well adapted to conditions of aridity in arid and semi-arid regions. This study aims to highlight the influence of climatic factors on the productivity of desert truffles under hyper-arid climatic conditions of the Sahara Desert in Algeria, with assumptions that the more varying climatic factors, mainly rainfall, are more crucial for the development and production of desert truffles. At seven separate sites, desert truffles were collected by systematic sampling between 2006 and 2012. The effects of climate parameters of each site on the productivities (g/ha/year) of desert truffle species were tested using generalized linear models (GLMs). The annual mean of the total production recorded for all three harvested species (Terfezia arenaria, Terfezia claveryi, and Tirmania nivea) was 785.43 ± 743.39 g/ha. Tirmania nivea was commonly present over the sampled sites with an occurrence of 70 ± 10.1%. GLMs revealed that total and specific productivities were closely positively related to autumnal precipitations occurring during October-December, which is the critical pre-breeding period for both desert truffles and host plant species. The other climatic parameters have statistically no effect on the annual variation of desert truffle productivity.

Arid3a is essential to execution of the first cell fate decision via direct embryonic and extraembryonic transcriptional regulation

PubMed Central

Rhee, Catherine; Lee, Bum-Kyu; Beck, Samuel; Anjum, Azeen; Cook, Kendra R.; Popowski, Melissa

2014-01-01

Despite their origin from the inner cell mass, embryonic stem (ES) cells undergo differentiation to the trophectoderm (TE) lineage by repression of the ES cell master regulator Oct4 or activation of the TE master regulator Caudal-type homeobox 2 (Cdx2). In contrast to the in-depth studies of ES cell self-renewal and pluripotency, few TE-specific regulators have been identified, thereby limiting our understanding of mechanisms underlying the first cell fate decision. Here we show that up-regulation and nuclear entry of AT-rich interactive domain 3a (Arid3a) drives TE-like transcriptional programs in ES cells, maintains trophoblast stem (TS) cell self-renewal, and promotes further trophoblastic differentiation both upstream and independent of Cdx2. Accordingly, Arid3a−/− mouse post-implantation placental development is severely impaired, resulting in early embryonic death. We provide evidence that Arid3a directly activates TE-specific and trophoblast lineage-specific genes while directly repressing pluripotency genes via differential regulation of epigenetic acetylation or deacetylation. Our results identify Arid3a as a critical regulator of TE and placental development through execution of the commitment and differentiation phases of the first cell fate decision. PMID:25319825

Relationships between primary production and crop yields in semi-arid and arid irrigated agro-ecosystems

NASA Astrophysics Data System (ADS)

Jaafar, H. H.; Ahmad, F. A.

2015-04-01

In semi-arid areas within the MENA region, food security problems are the main problematic imposed. Remote sensing can be a promising too early diagnose food shortages and further prevent the population from famine risks. This study is aimed at examining the possibility of forecasting yield before harvest from remotely sensed MODIS-derived Enhanced Vegetation Index (EVI), Net photosynthesis (net PSN), and Gross Primary Production (GPP) in semi-arid and arid irrigated agro-ecosystems within the conflict affected country of Syria. Relationships between summer yield and remotely sensed indices were derived and analyzed. Simple regression spatially-based models were developed to predict summer crop production. The validation of these models was tested during conflict years. A significant correlation (p<0.05) was found between summer crop yield and EVI, GPP and net PSN. Results indicate the efficiency of remotely sensed-based models in predicting summer yield, mostly for cotton yields and vegetables. Cumulative summer EVI-based model can predict summer crop yield during crisis period, with deviation less than 20% where vegetables are the major yield. This approach prompts to an early assessment of food shortages and lead to a real time management and decision making, especially in periods of crisis such as wars and drought.

Precipitation and Carbon-Water Coupling Jointly Control the Interannual Variability of Global Land Gross Primary Production

NASA Technical Reports Server (NTRS)

Zhang, Yao; Xiao, Xiangming; Guanter, Luis; Zhou, Sha; Ciais, Philippe; Joiner, Joanna; Sitch, Stephen; Wu, Xiaocui; Nabel, Julian; Dong, Jinwei;

Climate change and the collapse of the Akkadian empire: Evidence from the deep sea

NASA Astrophysics Data System (ADS)

Cullen, H. M.; Demenocal, P. B.; Hemming, S.; Hemming, G.; Brown, F. H.; Guilderson, T.; Sirocko, F.

2000-04-01

The Akkadian empire ruled Mesopotamia from the headwaters of the Tigris-Euphrates Rivers to the Persian Gulf during the late third millennium B.C. Archeological evidence has shown that this highly developed civilization collapsed abruptly near 4170 ± 150 calendar yr B.P., perhaps related to a shift to more arid conditions. Detailed paleoclimate records to test this assertion from Mesopotamia are rare, but changes in regional aridity are preserved in adjacent ocean basins. We document Holocene changes in regional aridity using mineralogic and geochemical analyses of a marine sediment core from the Gulf of Oman, which is directly downwind of Mesopotamian dust source areas and archeological sites. Our results document a very abrupt increase in eolian dust and Mesopotamian aridity, accelerator mass spectrometer radiocarbon dated to 4025 ± 125 calendar yr B.P., which persisted for ˜300 yr. Radiogenic (Nd and Sr) isotope analyses confirm that the observed increase in mineral dust was derived from Mesopotamian source areas. Geochemical correlation of volcanic ash shards between the archeological site and marine sediment record establishes a direct temporal link between Mesopotamian aridification and social collapse, implicating a sudden shift to more arid conditions as a key factor contributing to the collapse of the Akkadian empire.

Cavitation resistance and seasonal hydraulics differ among three arid Californian plant communities.

PubMed

Jacobsen, Anna L; Pratt, R Brandon; Davis, Stephen D; Ewers, Frank W

2007-12-01

Vulnerability to water stress-induced cavitation was measured on 27 woody shrub species from three arid plant communities including chaparral, coastal sage and Mojave Desert scrub. Dry season native embolism and pre-dawn water potential, and both wet and dry season xylem specific hydraulic conductivity (Ks) were measured. Cavitation resistance, estimated as water potential at 50% loss in conductivity (Psi50), was measured on all species during the wet season and on a subset of species during the dry season. Cavitation resistance varied with sampling season, with 8 of 13 sampled species displaying significant seasonal shifts. Native embolism and water potential were useful in identification of species displaying seasonal shifts. The Ks was not different among sites or seasons. The Psi50 varied among species and communities. Within communities, interspecific variation may be partially explained by differences in rooting depth or leaf habit (evergreen, semi-deciduous, deciduous). Communities diverged in their Psi50 with chaparral species displaying the greatest cavitation resistance regardless of sampling season. The greater cavitation resistance of chaparral species is surprising, considering the greater aridity of the Mojave Desert site. Adaptation to arid environments is due to many plant traits, and aridity does not necessarily lead to convergence in cavitation resistance.

Life at the hyperarid margin: novel bacterial diversity in arid soils of the Atacama Desert, Chile

USGS Publications Warehouse

Neilson, Julia W.; Quade, Jay; Ortiz, Marianyoly; Nelson, William M.; Legatzki, Antje; Tian, Fei; LaComb, Michelle; Betancourt, Julio L.; Wing, Rod A.; Soderlund, Carol A.; Maier, Raina M.

2012-01-01

Nearly half the earth's surface is occupied by dryland ecosystems, regions susceptible to reduced states of biological productivity caused by climate fluctuations. Of these regions, arid zones located at the interface between vegetated semiarid regions and biologically unproductive hyperarid zones are considered most vulnerable. The objective of this study was to conduct a deep diversity analysis of bacterial communities in unvegetated arid soils of the Atacama Desert, to characterize community structure and infer the functional potential of these communities based on observed phylogenetic associations. A 454-pyrotag analysis was conducted of three unvegetated arid sites located at the hyperarid-arid margin. The analysis revealed communities with unique bacterial diversity marked by high abundances of novel Actinobacteria and Chloroflexi and low levels of Acidobacteria and Proteobacteria, phyla that are dominant in many biomes. A 16S rRNA gene library of one site revealed the presence of clones with phylogenetic associations to chemoautotrophic taxa able to obtain energy through oxidation of nitrite, carbon monoxide, iron, or sulfur. Thus, soils at the hyperarid margin were found to harbor a wealth of novel bacteria and to support potentially viable communities with phylogenetic associations to non-phototrophic primary producers and bacteria capable of biogeochemical cycling.

Water relations, thallus structure and photosynthesis in Negev Desert lichens

NASA Technical Reports Server (NTRS)

Palmer, R. J. Jr; Friedmann, E. I.

1990-01-01

The role of lichen thallus structure in water relations and photosynthesis was studied in Ramalina maciformis (Del.) Bory and Teloschistes lacunosus (Rupr.) Sav. Water-vapour adsorption and photosynthesis are dependent upon thallus integrity and are significantly lower in crushed thalli. Cultured phycobiont (Trebouxia sp.) cells are capable of photosynthesis over the same relative humidity range (> 80% RH) as are intact lichens. Thus, water-vapour adsorption by the thallus and physiological adaptation of the phycobiont contribute to the ability of these lichens to photosynthesize in an arid environment. Despite differences in their anatomical structure and water-uptake characteristics, their CO2 incorporation is similar. The two lichens use liquid water differently and they occupy different niches.

Antecedent Moisture and Biological Inertia as Predictors of Plant and Ecosystem Productivity in Arid and Semiarid Systems

NASA Astrophysics Data System (ADS)

Ogle, K.

2011-12-01

Many plant and ecosystem processes in arid and semiarid systems may be affected by antecedent environmental conditions (e.g., precipitation patterns, soil water availability, temperature) that integrate over past days, weeks, months, seasons, or years. However, the importance of such antecedent exogenous effects relative to conditions occurring at the time of the observed process is relatively unexplored. Even less is known about the potential importance of antecedent endogenous effects that describe the influence of past ecosystem states on the current ecosystem state; e.g., how is current ecosystem productivity related to past productivity patterns? We hypothesize that incorporation of antecedent exogenous and endogenous factors can improve our predictive understanding of many plant and ecosystem processes, especially in arid and semiarid ecosystems. Furthermore, the common approach to quantifying the effects of antecedent (exogenous) variables relies on arbitrary, deterministic definitions of antecedent variables that (1) may not accurately describe the role of antecedent conditions and (2) ignore uncertainty associated with applying deterministic definitions. In this study, we employ a stochastic framework for (1) computing the antecedent variables that estimates the relative importance of conditions experienced each time unit into the past, also providing insight into potential lag responses, and (2) estimating the effect of antecedent factors on the response variable of interest. We employ this approach to explore the potential roles of antecedent exogenous and endogenous influences in three settings that illustrate the: (1) importance of antecedent precipitation for net primary productivity in the shortgrass steppe in northern Colorado, (2) dependency of tree growth on antecedent precipitation and past growth states for pinyon growing in western Colorado, and (3) influence of antecedent soil water and prior root status on observed root growth in the Mojave Desert FACE experiment. All three examples suggest that antecedent conditions are critical to predicting different indices of productivity such that the incorporation of antecedent effects explained an additional 20-40% of the variation in the productivity responses. Antecedent endogenous factors were important for understanding tree and root growth, suggesting a potential biological inertia effect that is likely linked to labile carbon storage and allocation strategies. The role of antecedent exogenous (water) variables suggests a lag response whose duration and timing differs according to the time scale of the response variable. In summary, antecedent water availability and past endogenous states appear critical to understanding plant and ecosystem productivity in arid and semiarid systems, and this study describes a stochastic framework for quantifying the potential influence of such antecedent conditions.

Assessment of the soil water balance by the combination of cosmic ray neutron sensing and eddy covariance technique in an irrigated citrus orchard (Marrakesh, Morocco)

NASA Astrophysics Data System (ADS)

Mroos, Katja; Baroni, Gabriele; Er-Raki, Salah; Francke, Till; Khabba, Said; Jarlan, Lionel; Hanich, Lahoucine; Oswald, Sascha E.

2014-05-01

Irrigation water requirement plays a crucial role in many agricultural areas and especially in arid and semi-arid landscapes. Improvements in the water management and the performance of the irrigation systems require a correct evaluation of the hydrological processes involved. However, some difficulties can arise due to the heterogeneity of the soil-plant system and of the irrigation scheme. To overcome these limitations, in this study, the soil water balance is analyzed by the combination of the Eddy Covariance technique (EC) and Cosmic Ray neutron Sensing (CRS). EC provides the measurement of the actual evapotranspiration over the area as it was presented in many field conditions. Moreover CRS showed to be a valuable approach to measure the root zone soil moisture integrated in a footprint of ~30 ha. In this way, the combination of the two methodologies should provide a better analysis of the soil water balance at field scale, as opposed to point observations, e.g. by TDR, evaporimeter and fluxmeter. Then, this could increase the capability to assess the irrigation efficiency and the agricultural water management. The study is conducted in a citrus orchard situated in a semi-arid region, 30 km southwest of Marrakesh (Morocco). The site is flat and planted with trees of same age growing in parallel rows with drip irrigation lines and application of fertilizer and pesticides. The original soil seems modified on the surface by the agricultural use, creating differences between trees, rows and lines. In addition, the drip irrigation creates also a spatial variability of the water flux distribution in the field, making this site an interesting area to test the methodology. Particular attention is given to the adaptation of the standard soil sampling campaign used for the calibration of the CRS and the introduction of a weighing function. Data were collected from June to December 2013, which corresponds to the high plant transpiration. Despite the intention of the farmer to maintain constant soil water contents in the root zone throughout the period, the CRS results showed a relatively strong dynamic of the soil water conditions at field scale and respond well to the EC measurements. Strong spatial heterogeneities and the difficulties of direct comparison between the different scales of measurements pose a challenge for full quantification of the water balance. Further analysis will address the assessment of the irrigation efficiency at different scales and of deep percolation. Keywords: Cosmic Ray Sensing, deep percolation, Eddy Covariance, evapotranspiration, irrigation, Morocco, soil moisture, semi-arid;

Evaluation of green infrastructure designs using the Automated Geospatial Watershed Assessment Tool

USDA-ARS?s Scientific Manuscript database

In arid and semi-arid regions, green infrastructure (GI) designs can address several issues facing urban environments, including augmenting water supply, mitigating flooding, decreasing pollutant loads, and promoting greenness in the built environment. An optimum design captures stormwater, addressi...

Applying animal behavior to arid rangeland mangement

USDA-ARS?s Scientific Manuscript database

Livestock production is one of many demands placed on today’s arid rangelands. Therefore, understanding plant and animal biology and their effects on biotic and abiotic landscape components is fundamental if rangelands are to remain ecologically sustainable. One limiting factor to accomplishing posi...

More than just consumers: Integrating local observations into drought monitoring to better support decision making

NASA Astrophysics Data System (ADS)

Ferguson, D. B.; Masayesva, A.; Meadow, A. M.; Crimmins, M.

2016-12-01

Drought monitoring and drought planning are complex endeavors. Measures of precipitation or streamflow provide little context for understanding how social and environmental systems impacted by drought are responding. In arid and semi-arid regions of the world, this challenge is particularly acute since social-ecological systems are already well-adapted to dry conditions. Understanding what drought means in these regions is an important first step in developing a decision-relevant monitoring system. Traditional drought indices may be of some use, but local observations may ultimately be more relevant for informing difficult decisions in response to unusually dry conditions. This presentation will focus on insights gained from a collaborative project between the University of Arizona and the Hopi Tribe-a Native American community in the U.S. Southwest-to develop a drought information system that is responsive to local needs. The primary goal of the project was to develop a system that: is based on how drought is experienced by Hopi citizens and resource managers, can incorporate local observations of drought impacts as well as conventional indicators, and brings together local expertise with conventional science-based observations. This kind of drought monitoring system can harnesses as much available information as possible to inform resource managers, political leaders, and citizens about drought conditions, but such a system can also engage these local drought stakeholders in observing, thinking about, and helping guide planning for drought.

Multi-criteria analysis for improving strategic environmental assessment of water programmes. A case study in semi-arid region of Brazil.

PubMed

Garfì, Marianna; Ferrer-Martí, Laia; Bonoli, Alessandra; Tondelli, Simona

2011-03-01

Multi-criteria analysis (MCA) is a family of decision-making tools that can be used in strategic environmental assessment (SEA) procedures to ensure that environmental, social and economic aspects are integrated into the design of human development strategies and planning, in order to increase the contribution of the environment and natural resources to poverty reduction. The aim of this paper is to highlight the contribution of a particular multi-criteria technique, the analytic hierarchy process (AHP), in two stages of the SEA procedure applied to water programmes in developing countries: the comparison of alternatives and monitoring. This proposal was validated through its application to a case study in Brazilian semi-arid region. The objective was to select and subsequently monitor the most appropriate programme for safe water availability. On the basis of the SEA results, a project was identified and implemented with successful results. In terms of comparisons of alternatives, AHP meets the requirements of human development programme assessment, including the importance of simplicity, a multidisciplinary and flexible approach, and a focus on the beneficiaries' concerns. With respect to monitoring, the study shows that AHP contributes to SEA by identifying the most appropriate indicators, in order to control the impacts of a project. Copyright © 2010 Elsevier Ltd. All rights reserved.

Molecular Mapping of Flowering Time Major Genes and QTLs in Chickpea (Cicer arietinum L.)

PubMed Central

Mallikarjuna, Bingi P.; Samineni, Srinivasan; Thudi, Mahendar; Sajja, Sobhan B.; Khan, Aamir W.; Patil, Ayyanagowda; Viswanatha, Kannalli P.; Varshney, Rajeev K.; Gaur, Pooran M.

2017-01-01

Flowering time is an important trait for adaptation and productivity of chickpea in the arid and the semi-arid environments. This study was conducted for molecular mapping of genes/quantitative trait loci (QTLs) controlling flowering time in chickpea using F2 populations derived from four crosses (ICCV 96029 × CDC Frontier, ICC 5810 × CDC Frontier, BGD 132 × CDC Frontier and ICC 16641 × CDC Frontier). Genetic studies revealed monogenic control of flowering time in the crosses ICCV 96029 × CDC Frontier, BGD 132 × CDC Frontier and ICC 16641 × CDC Frontier, while digenic control with complementary gene action in ICC 5810 × CDC Frontier. The intraspecific genetic maps developed from these crosses consisted 75, 75, 68 and 67 markers spanning 248.8 cM, 331.4 cM, 311.1 cM and 385.1 cM, respectively. A consensus map spanning 363.8 cM with 109 loci was constructed by integrating four genetic maps. Major QTLs corresponding to flowering time genes efl-1 from ICCV 96029, efl-3 from BGD 132 and efl-4 from ICC 16641 were mapped on CaLG04, CaLG08 and CaLG06, respectively. The QTLs and linked markers identified in this study can be used in marker-assisted breeding for developing early maturing chickpea. PMID:28729871

Hydroclimatic variability in loess δDwax records from the central Chinese Loess Plateau over the past 250 ka

NASA Astrophysics Data System (ADS)

Wang, Zheng; An, Zhisheng; Liu, Zhonghui; Qiang, Xiaoke; Zhang, Fan; Liu, Weiguo

2018-04-01

This study reports hydrogen isotopic records from the central Chinese Loess Plateau (CLP) over the past 250 ka. After eliminating the influence of ice and local temperatures, the δDwax records extracted from two loess sites at Xifeng and Luochuan can be taken to represent arid/humid alternations in the hydrological environment in this marginal Asian Summer Monsoon (ASM) region; they also contain integrated information on summer precipitation patterns and the corresponding responses to these changes by predominant vegetation cover types. These arid/humid alternations show 100 ka, 40 ka and 20 ka cycles. An increase in precipitation in association with an enhanced summer monsoon has historically been taken to be the major factor driving a humid environment in the central CLP. However, hydroclimatic changes in δDwax records differ for the central CLP, central China and southern China. Over a 20 ka cycle, the influence of solar insolation on hydroclimatic changes can be shown to be consistent throughout the central CLP. However, changes in the relative location of the land and sea may have caused different hydroclimatic responses between southern China and the central CLP on a glacial-interglacial scale. The hydroclimatic variability in the central CLP would suggest that an enhanced summer monsoon due to climatic warming is the key to understanding decreased drought degree in this marginal monsoonal region.

Pancreatic cancer genomes reveal aberrations in axon guidance pathway genes

PubMed Central

Biankin, Andrew V.; Waddell, Nicola; Kassahn, Karin S.; Gingras, Marie-Claude; Muthuswamy, Lakshmi B.; Johns, Amber L.; Miller, David K.; Wilson, Peter J.; Patch, Ann-Marie; Wu, Jianmin; Chang, David K.; Cowley, Mark J.; Gardiner, Brooke B.; Song, Sarah; Harliwong, Ivon; Idrisoglu, Senel; Nourse, Craig; Nourbakhsh, Ehsan; Manning, Suzanne; Wani, Shivangi; Gongora, Milena; Pajic, Marina; Scarlett, Christopher J.; Gill, Anthony J.; Pinho, Andreia V.; Rooman, Ilse; Anderson, Matthew; Holmes, Oliver; Leonard, Conrad; Taylor, Darrin; Wood, Scott; Xu, Qinying; Nones, Katia; Fink, J. Lynn; Christ, Angelika; Bruxner, Tim; Cloonan, Nicole; Kolle, Gabriel; Newell, Felicity; Pinese, Mark; Mead, R. Scott; Humphris, Jeremy L.; Kaplan, Warren; Jones, Marc D.; Colvin, Emily K.; Nagrial, Adnan M.; Humphrey, Emily S.; Chou, Angela; Chin, Venessa T.; Chantrill, Lorraine A.; Mawson, Amanda; Samra, Jaswinder S.; Kench, James G.; Lovell, Jessica A.; Daly, Roger J.; Merrett, Neil D.; Toon, Christopher; Epari, Krishna; Nguyen, Nam Q.; Barbour, Andrew; Zeps, Nikolajs; Kakkar, Nipun; Zhao, Fengmei; Wu, Yuan Qing; Wang, Min; Muzny, Donna M.; Fisher, William E.; Brunicardi, F. Charles; Hodges, Sally E.; Reid, Jeffrey G.; Drummond, Jennifer; Chang, Kyle; Han, Yi; Lewis, Lora R.; Dinh, Huyen; Buhay, Christian J.; Beck, Timothy; Timms, Lee; Sam, Michelle; Begley, Kimberly; Brown, Andrew; Pai, Deepa; Panchal, Ami; Buchner, Nicholas; De Borja, Richard; Denroche, Robert E.; Yung, Christina K.; Serra, Stefano; Onetto, Nicole; Mukhopadhyay, Debabrata; Tsao, Ming-Sound; Shaw, Patricia A.; Petersen, Gloria M.; Gallinger, Steven; Hruban, Ralph H.; Maitra, Anirban; Iacobuzio-Donahue, Christine A.; Schulick, Richard D.; Wolfgang, Christopher L.; Morgan, Richard A.; Lawlor, Rita T.; Capelli, Paola; Corbo, Vincenzo; Scardoni, Maria; Tortora, Giampaolo; Tempero, Margaret A.; Mann, Karen M.; Jenkins, Nancy A.; Perez-Mancera, Pedro A.; Adams, David J.; Largaespada, David A.; Wessels, Lodewyk F. A.; Rust, Alistair G.; Stein, Lincoln D.; Tuveson, David A.; Copeland, Neal G.; Musgrove, Elizabeth A.; Scarpa, Aldo; Eshleman, James R.; Hudson, Thomas J.; Sutherland, Robert L.; Wheeler, David A.; Pearson, John V.; McPherson, John D.; Gibbs, Richard A.; Grimmond, Sean M.

2012-01-01

Pancreatic cancer is a highly lethal malignancy with few effective therapies. We performed exome sequencing and copy number analysis to define genomic aberrations in a prospectively accrued clinical cohort (n = 142) of early (stage I and II) sporadic pancreatic ductal adenocarcinoma. Detailed analysis of 99 informative tumours identified substantial heterogeneity with 2,016 non-silent mutations and 1,628 copy-number variations. We define 16 significantly mutated genes, reaffirming known mutations (KRAS, TP53, CDKN2A, SMAD4, MLL3, TGFBR2, ARID1A and SF3B1), and uncover novel mutated genes including additional genes involved in chromatin modification (EPC1 and ARID2), DNA damage repair (ATM) and other mechanisms (ZIM2, MAP2K4, NALCN, SLC16A4 and MAGEA6). Integrative analysis with in vitro functional data and animal models provided supportive evidence for potential roles for these genetic aberrations in carcinogenesis. Pathway-based analysis of recurrently mutated genes recapitulated clustering in core signalling pathways in pancreatic ductal adenocarcinoma, and identified new mutated genes in each pathway. We also identified frequent and diverse somatic aberrations in genes described traditionally as embryonic regulators of axon guidance, particularly SLIT/ROBO signalling, which was also evident in murine Sleeping Beauty transposon-mediated somatic mutagenesis models of pancreatic cancer, providing further supportive evidence for the potential involvement of axon guidance genes in pancreatic carcinogenesis. PMID:23103869

Pancreatic cancer genomes reveal aberrations in axon guidance pathway genes.

PubMed

Biankin, Andrew V; Waddell, Nicola; Kassahn, Karin S; Gingras, Marie-Claude; Muthuswamy, Lakshmi B; Johns, Amber L; Miller, David K; Wilson, Peter J; Patch, Ann-Marie; Wu, Jianmin; Chang, David K; Cowley, Mark J; Gardiner, Brooke B; Song, Sarah; Harliwong, Ivon; Idrisoglu, Senel; Nourse, Craig; Nourbakhsh, Ehsan; Manning, Suzanne; Wani, Shivangi; Gongora, Milena; Pajic, Marina; Scarlett, Christopher J; Gill, Anthony J; Pinho, Andreia V; Rooman, Ilse; Anderson, Matthew; Holmes, Oliver; Leonard, Conrad; Taylor, Darrin; Wood, Scott; Xu, Qinying; Nones, Katia; Fink, J Lynn; Christ, Angelika; Bruxner, Tim; Cloonan, Nicole; Kolle, Gabriel; Newell, Felicity; Pinese, Mark; Mead, R Scott; Humphris, Jeremy L; Kaplan, Warren; Jones, Marc D; Colvin, Emily K; Nagrial, Adnan M; Humphrey, Emily S; Chou, Angela; Chin, Venessa T; Chantrill, Lorraine A; Mawson, Amanda; Samra, Jaswinder S; Kench, James G; Lovell, Jessica A; Daly, Roger J; Merrett, Neil D; Toon, Christopher; Epari, Krishna; Nguyen, Nam Q; Barbour, Andrew; Zeps, Nikolajs; Kakkar, Nipun; Zhao, Fengmei; Wu, Yuan Qing; Wang, Min; Muzny, Donna M; Fisher, William E; Brunicardi, F Charles; Hodges, Sally E; Reid, Jeffrey G; Drummond, Jennifer; Chang, Kyle; Han, Yi; Lewis, Lora R; Dinh, Huyen; Buhay, Christian J; Beck, Timothy; Timms, Lee; Sam, Michelle; Begley, Kimberly; Brown, Andrew; Pai, Deepa; Panchal, Ami; Buchner, Nicholas; De Borja, Richard; Denroche, Robert E; Yung, Christina K; Serra, Stefano; Onetto, Nicole; Mukhopadhyay, Debabrata; Tsao, Ming-Sound; Shaw, Patricia A; Petersen, Gloria M; Gallinger, Steven; Hruban, Ralph H; Maitra, Anirban; Iacobuzio-Donahue, Christine A; Schulick, Richard D; Wolfgang, Christopher L; Morgan, Richard A; Lawlor, Rita T; Capelli, Paola; Corbo, Vincenzo; Scardoni, Maria; Tortora, Giampaolo; Tempero, Margaret A; Mann, Karen M; Jenkins, Nancy A; Perez-Mancera, Pedro A; Adams, David J; Largaespada, David A; Wessels, Lodewyk F A; Rust, Alistair G; Stein, Lincoln D; Tuveson, David A; Copeland, Neal G; Musgrove, Elizabeth A; Scarpa, Aldo; Eshleman, James R; Hudson, Thomas J; Sutherland, Robert L; Wheeler, David A; Pearson, John V; McPherson, John D; Gibbs, Richard A; Grimmond, Sean M

2012-11-15

Pancreatic cancer is a highly lethal malignancy with few effective therapies. We performed exome sequencing and copy number analysis to define genomic aberrations in a prospectively accrued clinical cohort (n = 142) of early (stage I and II) sporadic pancreatic ductal adenocarcinoma. Detailed analysis of 99 informative tumours identified substantial heterogeneity with 2,016 non-silent mutations and 1,628 copy-number variations. We define 16 significantly mutated genes, reaffirming known mutations (KRAS, TP53, CDKN2A, SMAD4, MLL3, TGFBR2, ARID1A and SF3B1), and uncover novel mutated genes including additional genes involved in chromatin modification (EPC1 and ARID2), DNA damage repair (ATM) and other mechanisms (ZIM2, MAP2K4, NALCN, SLC16A4 and MAGEA6). Integrative analysis with in vitro functional data and animal models provided supportive evidence for potential roles for these genetic aberrations in carcinogenesis. Pathway-based analysis of recurrently mutated genes recapitulated clustering in core signalling pathways in pancreatic ductal adenocarcinoma, and identified new mutated genes in each pathway. We also identified frequent and diverse somatic aberrations in genes described traditionally as embryonic regulators of axon guidance, particularly SLIT/ROBO signalling, which was also evident in murine Sleeping Beauty transposon-mediated somatic mutagenesis models of pancreatic cancer, providing further supportive evidence for the potential involvement of axon guidance genes in pancreatic carcinogenesis.

Malaria vector abundance is associated with house structures in Baringo County, Kenya.

PubMed

Ondiba, Isabella M; Oyieke, Florence A; Ong'amo, George O; Olumula, Macrae M; Nyamongo, Isaac K; Estambale, Benson B A

2018-01-01

Malaria, a major cause of morbidity and mortality, is the most prevalent vector borne disease in Baringo County; a region which has varied house designs in arid and semi-arid areas. This study investigated the association between house structures and indoor-malaria vector abundance in Baringo County. The density of malaria vectors in houses with open eaves was higher than that for houses with closed eaves. Grass thatched roof houses had higher density of malaria vectors than corrugated iron sheet roofs. Similarly, mud walled houses had higher vector density than other wall types. Houses in the riverine zone were significantly associated with malaria vector abundance (p<0.000) possibly due to more varied house structures. In Kamnarok village within riverine zone, a house made of grass thatched roof and mud wall but raised on stilts with domestic animals (sheep/goats) kept at the lower level had lower mosquito density (5.8 per collection) than ordinary houses made of same materials but at ground level (30.5 mosquitoes per collection), suggestive of a change in behavior of mosquito feeding and resting. House modifications such as screening of eaves, improvement of construction material and building stilted houses can be incorporated in the integrated vector management (IVM) strategy to complement insecticide treated bed nets and indoor residual spray to reduce indoor malaria vector density.

Managing the livestock– Wildlife interface on rangelands

USGS Publications Warehouse

du Toit, Johan T.; Cross, Paul C.; Valeix, Marion

2017-01-01

On rangelands the livestock–wildlife interface is mostly characterized by management actions aimed at controlling problems associated with competition, disease, and depredation. Wildlife communities (especially the large vertebrate species) are typically incompatible with agricultural development because the opportunity costs of wildlife conservation are unaffordable except in arid and semi-arid regions. Ecological factors including the provision of supplementary food and water for livestock, together with the persecution of large predators, result in livestock replacing wildlife at biomass densities far exceeding those of indigenous ungulates. Diseases are difficult to eradicate from free-ranging wildlife populations and so veterinary controls usually focus on separating commercial livestock herds from wildlife. Persecution of large carnivores due to their depredation of livestock has caused the virtual eradication of apex predators from most rangelands. However, recent research points to a broad range of solutions to reduce conflict at the livestock–wildlife interface. Conserving wildlife bolsters the adaptive capacity of a rangeland by providing stakeholders with options for dealing with environmental change. This is contingent upon local communities being empowered to benefit directly from their wildlife resources within a management framework that integrates land-use sectors at the landscape scale. As rangelands undergo irreversible changes caused by species invasions and climate forcings, the future perspective favors a proactive shift in attitude towards the livestock–wildlife interface, from problem control to asset management.

Evaluation of flow mixing in an ARID-HV algal raceway using statistics of temporal and spatial distribution of fluid particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Ben; Li, Peiwen; Waller, Peter

2015-02-27

This paper analyzes and evaluates the flow mixing in an open channel algal raceway for biofuel production. The flow mixing governs the frequency of how algae cells are exposed to sunlight, due to the fluid movement between the surface and the bottom of the algal raceway, thereby affecting algal growth rate. In this work, we investigated the flow mixing performance in a table-sized model of the High Velocity Algae Raceway Integrated Design (ARID-HV). Various geometries of the raceway channels and dams were considered in both the CFD analysis and experimental flowvisualization. In the CFD simulation, the pathlines of fluid particlesweremore » analyzed to obtain the distribution of the number of times that particles passed across a critical water depth, Dc, defined as a cycle count. In addition, the distribution of the time period fraction that the fluid particles stayed in the zones above and below Dc was recorded. Such information was used to evaluate the flow mixing in the raceway. The CFD evaluation of the flow mixing was validated using experimental flow visualization, which showed a good qualitative agreement with the numerical results. In conclusion, this CFD-based evaluation methodology is recommended for flow field optimization for open channel algal raceways, as well as for other engineering applications in which flow mixing is an important concern.« less

Land desertification monitoring and assessment in Yulin of Northwest China using remote sensing and geographic information systems (GIS).

PubMed

Zhang, Yuanzhi; Chen, Zhengyi; Zhu, Boqin; Luo, Xiuyue; Guan, Yanning; Guo, Shan; Nie, Yueping

2008-12-01

The objective of this study is to develop techniques for assessing and analysing land desertification in Yulin of Northwest China, as a typical monitoring region through the use of remotely sensed data and geographic information systems (GIS). The methodology included the use of Landsat TM data from 1987, 1996 and 2006, supplemented by aerial photos in 1960, topographic maps, field work and use of other existing data. From this, land cover, the Normalised Difference Vegetation Index (NDVI), farmland, woodland and grassland maps at 1:100,000 were prepared for land desertification monitoring in the area. In the study, all data was entered into a GIS using ILWIS software to perform land desertification monitoring. The results indicate that land desertification in the area has been developing rapidly during the past 40 years. Although land desertification has to some extent been controlled in the area by planting grasses and trees, the issue of land desertification is still serious. The study also demonstrates an example of why the integration of remote sensing with GIS is critical for the monitoring of environmental changes in arid and semi-arid regions, e.g. in land desertification monitoring in the Yulin pilot area. However, land desertification monitoring using remote sensing and GIS still needs to be continued and also refined for the purpose of long-term monitoring and the management of fragile ecosystems in the area.

Socio-economic effect on socially-deprived communities of developing drinking water quality problems in arid and semi-arid area of central Rajasthan

NASA Astrophysics Data System (ADS)

Husain, I.; Husain, J.; Arif, M.

2014-09-01

Rajasthan is well known for its Great Thar desert. Central Rajasthan has an arid to semi-arid environment. The area faces either scarcity of water or poor quality of drinking water. In some areas water is transported 2 km or more, which uses time, energy and money. Rich people have their own sources, which is restricted for use by others. Such conditions are affecting socially-deprived communities, both socially and economically. Groundwater is a major source of drinking water due to the unavailability of surface water. There is a lack of groundwater quality knowledge in the community and the data available is hard to understand by consumers. The CCME Water Quality Index is a tool to simplify the water quality report by rating the water on quality standards. It provides meaningful summaries of overall water quality and trends, which is accessible to non-technical lay people. In the present study the objective is to examine the groundwater quality of six districts (Ajmer, Bhilwara, Pali, Rajasamand, Nagaur and Jodhpur), centrally located in Rajasthan, with arid and semi-arid conditions. CCME WQI is also evaluated to produce quality data in a form to be understood by the community. A total of 4369 groundwater sources in 1680 villages from six districts (76 546 km2) were collected and examined. Results are outlined in the Bureau of Indian Standards (BIS: 10500, 2012) and 2952 sources are unsafe for drinking. According to CCME WQI groundwater of 93 villages is poor, 343 villages are marginal, and 369 villages are fair in quality. Toxicological studies of unsafe drinking water and their remedial measures are also discussed. A tentative correlation between prevailing water-borne diseases and quality parameter has also been shown

Plan and Some Results of "Advanced Study on Precipitation Enhancement in Arid and Semi-Arid Regions"

NASA Astrophysics Data System (ADS)

Murakami, M.

2016-12-01

There are several technologies to secure water resources, including the desalination of seawater, recycling of industrial water and reuse of wastewater. However precipitation enhancement is the only way we can create a large amount of water for industrial use, for example, water for irrigation, provided we find clouds suitable for cloud seeding and apply appropriate and effective methods to increase precipitation. Therefore, rain enhancement research is critical in the quest for new water security options and innovative solutions in the UAE and other arid and semi-arid regions. The main objective of our project is to better evaluate, and ultimately improve, the effectiveness of rain enhancement in the UAE and other arid and semi-arid regions using hygroscopic and glaciogenic seeding techniques. One of the major questions regarding rain enhancement today is the effectiveness of hygroscopic seeding for warm and supercooled convective clouds. Our research will investigate the microphysical processes in seeded and unseeded clouds using a combination of laboratory experiments, numerical simulations and in-situ aircraft measurements in order to decipher the mechanism responsible for precipitation augmentation due to hygroscopic seeding. In our research, major elements of cloud seeding, e.g., assessment of seedability, development of optimal seeding methods and evaluation of seeding effects, will be investigated in the most efficient and realistic way, within three years, using mainly the numerical models with the sophisticated seeding scheme, which is developed on a basis of laboratory experiments and then validated against in-situ and remote sensing observations. In addition to the research plan, the outcomes of the research projects, which will be made available to the public at the end of the project and benefit the broader society, is discussed.

Apparent Overinvestment in Leaf Venation Relaxes Leaf Morphological Constraints on Photosynthesis in Arid Habitats.

PubMed

de Boer, Hugo J; Drake, Paul L; Wendt, Erin; Price, Charles A; Schulze, Ernst-Detlef; Turner, Neil C; Nicolle, Dean; Veneklaas, Erik J

2016-12-01

Leaf veins supply the mesophyll with water that evaporates when stomata are open to allow CO 2 uptake for photosynthesis. Theoretical analyses suggest that water is optimally distributed in the mesophyll when the lateral distance between veins (d x ) is equal to the distance from these veins to the epidermis (d y ), expressed as d x :d y ≈ 1. Although this theory is supported by observations of many derived angiosperms, we hypothesize that plants in arid environments may reduce d x :d y below unity owing to climate-specific functional adaptations of increased leaf thickness and increased vein density. To test our hypothesis, we assembled leaf hydraulic, morphological, and photosynthetic traits of 68 species from the Eucalyptus and Corymbia genera (termed eucalypts) along an aridity gradient in southwestern Australia. We inferred the potential gas-exchange advantage of reducing d x beyond d y using a model that links leaf morphology and hydraulics to photosynthesis. Our observations reveal that eucalypts in arid environments have thick amphistomatous leaves with high vein densities, resulting in d x :d y ratios that range from 1.6 to 0.15 along the aridity gradient. Our model suggests that, as leaves become thicker, the effect of reducing d x beyond d y is to offset the reduction in leaf gas exchange that would result from maintaining d x :d y at unity. This apparent overinvestment in leaf venation may be explained from the selective pressure of aridity, under which traits associated with long leaf life span, high hydraulic and thermal capacitances, and high potential rates of leaf water transport confer a competitive advantage. © 2016 American Society of Plant Biologists. All Rights Reserved.

Environmental proxies of antigen exposure explain variation in immune investment better than indices of pace of life.

PubMed

Horrocks, Nicholas P C; Hegemann, Arne; Ostrowski, Stéphane; Ndithia, Henry; Shobrak, Mohammed; Williams, Joseph B; Matson, Kevin D; Tieleman, B I

2015-01-01

Investment in immune defences is predicted to covary with a variety of ecologically and evolutionarily relevant axes, with pace of life and environmental antigen exposure being two examples. These axes may themselves covary directly or inversely, and such relationships can lead to conflicting predictions regarding immune investment. If pace of life shapes immune investment then, following life history theory, slow-living, arid zone and tropical species should invest more in immunity than fast-living temperate species. Alternatively, if antigen exposure drives immune investment, then species in antigen-rich tropical and temperate environments are predicted to exhibit higher immune indices than species from antigen-poor arid locations. To test these contrasting predictions we investigated how variation in pace of life and antigen exposure influence immune investment in related lark species (Alaudidae) with differing life histories and predicted risks of exposure to environmental microbes and parasites. We used clutch size and total number of eggs laid per year as indicators of pace of life, and aridity, and the climatic variables that influence aridity, as correlates of antigen abundance. We quantified immune investment by measuring four indices of innate immunity. Pace of life explained little of the variation in immune investment, and only one immune measure correlated significantly with pace of life, but not in the predicted direction. Conversely, aridity, our proxy for environmental antigen exposure, was predictive of immune investment, and larks in more mesic environments had higher immune indices than those living in arid, low-risk locations. Our study suggests that abiotic environmental variables with strong ties to environmental antigen exposure can be important correlates of immunological variation.

Systematic revision of the marbled velvet geckos (Oedura marmorata species complex, Diplodactylidae) from the Australian arid and semi-arid zones.

PubMed

Oliver, Paul M; Doughty, Paul

2016-03-08

Lizards restricted to rocky habitats often comprise numerous deeply divergent lineages, reflecting the disjunct nature of their preferred habitat and the capacity of rocky habitats to function as evolutionary refugia. Here we review the systematics and diversity of the predominantly saxicoline Australian marbled velvet geckos (genus Oedura) in the Australian arid and semi-arid zones using newly-gathered morphological data and previously published genetic data. Earlier work showed that four largely allopatric and genetically divergent lineages are present: Western (Pilbara and Gascoyne regions), Gulf (west and south of the Gulf of Carpentaria), Central (central ranges) and Eastern (Cooper and Darling Basins). None of these four populations are conspecific with true O. marmorata, a seperate species complex that is restricted to the Top End region of the Northern Territory. Top End forms share a short, bulbous tail whereas the other four lineages treated here possess a long, tapering tail. Morphological differences among the arid and semi-arid lineages include smaller body size, tapering lamellae and a shorter tail for the Gulf population, and a partially divided rostral scale in the Western population compared to the Central and Eastern populations. Accordingly, we resurrect O. cincta de Vis from synonymy for the Central and Eastern lineages, and regard this species as being comprised of two evolutionary significant units. We also describe the Gulf and Western lineages as new species: Oedura bella sp. nov. and O. fimbria sp. nov., respectively. We note that a predominantly arboreal lineage (the Eastern lineage of O. cincta) is more widely distributed than the other lineages and is phylogenetically nested within a saxicoline clade, but tends to have a deeper head and shorter limbs, consistent with morphological variation observed in other lizard radiations including both saxicoline and arboreal taxa.

Arid1a Inactivation in an Apc and Pten-defective Mouse Ovarian Cancer Model Enhances Epithelial Differentiation and Prolongs Survival

PubMed Central

Zhai, Yali; Kuick, Rork; Tipton, Courtney; Wu, Rong; Sessine, Michael; Wang, Zhong; Baker, Suzanne J.; Fearon, Eric R.; Cho, Kathleen R.

2015-01-01

Inactivation of the ARID1A tumor suppressor gene is frequent in ovarian endometrioid (OEC) and clear cell carcinomas (OCCC), often in conjunction with mutations activating the PI3K/AKT and/or canonical Wnt signaling pathways. Prior work has shown that conditional bi-allelic inactivation of the Apc and Pten tumor suppressor genes in the mouse ovarian surface epithelium (OSE) promotes outgrowth of tumors that reflect the biological behavior and gene expression profiles of human OECs harboring comparable Wnt and PI3K/AKT pathway defects, though the mouse tumors are more poorly differentiated than their human tumor counterparts. We found that conditional inactivation of one or both Arid1a alleles in OSE concurrently with Apc and Pten inactivation unexpectedly prolonged survival of tumor-bearing mice and promoted striking epithelial differentiation of the cancer cells, resulting in morphological features akin to those in human OECs. Enhanced epithelial differentiation was linked to reduced expression of mesenchymal markers N-cadherin and vimentin, and increased expression of epithelial markers Crb3 and E-cadherin. Global gene expression profiling showed enrichment for genes associated with mesenchymal-to-epithelial transition in the Arid1a-deficient tumors. We also found that an activating (E545K) Pik3ca mutation, unlike Pten inactivation or Pik3ca H1047R mutation, cannot cooperate with Arid1a loss to promote ovarian cancer development in the mouse. Our results indicate the Arid1a tumor suppressor gene has a key role in regulating OEC differentiation, and paradoxically the mouse cancers with more initiating tumor suppressor gene defects had a less aggressive phenotype than cancers arising from fewer gene alterations. PMID:26279473

Photochemically induced carbon dioxide production as a mechanism for carbon loss from plant litter in arid ecosystems

NASA Astrophysics Data System (ADS)

Brandt, L. A.; Bohnet, C.; King, J. Y.

2009-06-01

We investigated the potential for abiotic mineralization to carbon dioxide (CO2) via photodegradation to account for carbon (C) loss from plant litter under conditions typical of arid ecosystems. We exposed five species of grass and oak litter collected from arid and mesic sites to a factorial design of ultraviolet (UV) radiation (UV pass, UV block), and sterilization under dry conditions in the laboratory. UV pass treatments produced 10 times the amount of CO2 produced in UV block treatments. CO2 production rates were unaffected by litter chemistry or sterilization. We also exposed litter to natural solar radiation outdoors on clear, sunny days close to the summer solstice at midlatitudes and found that UV radiation (280-400 nm) accounted for 55% of photochemically induced CO2 production, while shortwave visible radiation (400-500 nm) accounted for 45% of CO2 production. Rates of photochemically induced CO2 production on a per-unit-mass basis decreased with litter density, indicating that rates depend on litter surface area. We found no evidence for leaching, methane production, or facilitation of microbial decomposition as alternative mechanisms for significant photochemically induced C loss from litter. We conclude that abiotic mineralization to CO2 is the primary mechanism by which C is lost from litter during photodegradation. We estimate that CO2 production via photodegradation could be between 1 and 4 g C m-2 a-1 in arid ecosystems in the southwestern United States. Taken together with low levels of litter production in arid systems, photochemical mineralization to CO2 could account for a significant proportion of annual carbon loss from litter in arid ecosystems.

Undifferentiated Endometrial Carcinomas Show Frequent Loss of Core Switch/Sucrose Nonfermentable Complex Proteins.

PubMed

Köbel, Martin; Hoang, Lien N; Tessier-Cloutier, Basile; Meng, Bo; Soslow, Robert A; Stewart, Colin J R; Lee, Cheng-Han

2018-01-01

Undifferentiated endometrial carcinoma is an aggressive type of endometrial carcinoma that typically presents with advanced stage disease and rapid clinical progression. In contrast to dedifferentiated endometrial carcinoma, undifferentiated carcinoma lacks a concurrent differentiated (typically low-grade endometrioid) carcinoma component, though the undifferentiated component of dedifferentiated carcinoma is similar histologically and immunophenotypically to pure undifferentiated carcinoma. We recently identified 3 mutually exclusive mechanisms of switch/sucrose nonfermentable (SWI/SNF) complex inactivation (BRG1 inactivation, INI1 inactivation or ARID1A/ARID1B co-inactivation) that are associated with histologic dedifferentiation in the majority of dedifferentiated endometrial carcinoma. In the current study, we aimed to determine by immunohistochemistry whether these patterns of SWI/SNF inactivation also occur in undifferentiated endometrial carcinomas. Of the 34 undifferentiated carcinomas examined, 17 (50%) exhibited SWI/SNF complex inactivation, with 11 tumors showing complete loss of both ARID1A and ARID1B, 5 showing complete loss of BRG1 and 1 showing complete loss of INI1. Ten of the remaining 17 undifferentiated carcinomas showed the following alterations: 5 tumors (15%) showed loss of ARID1A only with intact ARID1B, BRG1, and INI1 expression, 4 tumors (12%) showed mutated patterns of p53 staining with intact SWI/SNF protein expression, and 1 tumor (3%) harbored a POLE exonuclease domain mutation (P286R). SWI/SNF complex-inactivated tumors presented more frequently with extrauterine disease spread than those with intact expression (88% vs. 41%, respectively). In addition, patients with SWI/SNF complex-inactivated tumors had a significantly worse disease-specific survival (P=0.02). The findings here demonstrate frequent SWI/SNF complex inactivation in undifferentiated endometrial carcinomas, which has future implications regarding therapies that target chromatin remodelling and epigenetic control.

Variation in Onset of Summer Dormancy and Flowering Capacity Along an Aridity Gradient in Poa bulbosa L., a Geophytic Perennial Grass

PubMed Central

OFIR, MICHA; KIGEL, JAIME

2003-01-01

Variation in the onset of summer dormancy and flowering capacity of 16 populations of Poa bulbosa, collected along a steep north–south aridity gradient in Israel (810–110 mm rain year–1), was studied under controlled conditions in a phytotron (16 h daylength, 22/16 °C day/night) and under natural conditions in a garden experiment in a net‐house. Plant age at the onset of dormancy varied markedly amongst populations (7–16 weeks under controlled conditions) and was positively correlated with mean annual precipitation at the site of origin of the population, i.e. dormancy was earlier as aridity increased. Flowering capacity in the different populations was negatively correlated with rainfall in the original habitat and, consequently, also with the age at onset of dormancy, i.e. the lower the mean annual precipitation, the earlier the onset of dormancy and the higher the proportion of flowering plants and panicles per plant. Differences in xeromorphic leaf traits were also observed among populations from locations differing in aridity. Plants from the more arid sites (110–310 mm year–1) generally had greyish and curved leaves, whereas plants from more humid sites (500–810 mm year–1) tended to have green and straight leaves. Thus, plants with curved and/or greyish leaves generally had a higher flowering capacity and entered dormancy earlier than plants with straight and/or green leaves. The significance of the association among these traits for the adaptation of P. bulbosa to increasing aridity is discussed. PMID:12547692

The Jornada Basin long term ecological research program

USDA-ARS?s Scientific Manuscript database

Chihuahuan Desert landscapes exemplify the ecological conditions, vulnerability, and management challenges in arid and semi-arid regions around the world. The goal of the Jornada Basin Long Term Ecological Research program (JRN LTER) established in 1982 is to understand and quantify the key factors ...

Simplified spatiotemporal electromagnetic induction - salinity multi-field calibration

USDA-ARS?s Scientific Manuscript database

Salinity-affected farmlands are common in arid and semi-arid regions. To assure long-term sustainability of farming practices in these areas, soil salinity (ECe) should be routinely mapped and monitored. Salinity can be measured through soil sampling directed by geospatial measurements of apparent s...

A Total Water Management Analysis of the Las Vegas Wash Watershed, Nevada

EPA Science Inventory

Climate change, land use change, and population growth are fundamental factors affecting future hydrologic conditions in streams, especially in arid regions with scarce water resources. Located in the arid southwest, Las Vegas Valley located within the Las Vegas Wash watershed is...

Relating SMMR 37 GHz polarization difference to precipitation and atmospheric carbon dioxide concentration - A reappraisal

NASA Technical Reports Server (NTRS)

Tucker, C. J.

1992-01-01

The relations of Scanning Multi-channel Microwave Radiometer (SMMR) 37 GHz polarization difference to precipitation and atmospheric carbon dioxide (CO2) concentrations are reviewed. Annual precipitation data, a surrogate for green leaf vegetation density, are compared with the coincident SMMR 37 GHz polarization difference from arid and semi-arid West Africa for 1982-85. The SMMR 37 GHz polarization difference was found to be poorly correlated with precipitation in arid and semi-arid zones, contrary to previous reports. Coincident SMMR 37 GHz polarization difference and atmospheric CO2 concentration data from July 1981 to June 1983 are also reviewed. Previously suggested relations of the SMMR 37 GHz polarization difference to atmospheric CO2 concentrations were found to be heavily biased by winter conditions in the Northern Hemisphere. The use of the SMMR 37 GHz polarization difference for determining green leaf vegetation density, net primary production, atmospheric CO2 draw-down and related processes is questioned.

Deserts : geology and resources

USGS Publications Warehouse

Walker, Alta S.

1996-01-01

Approximately one-third of the Earth's land surface is desert, arid land with meager rainfall that supports only sparse vegetation and a limited population of people and animals. Deserts stark, sometimes mysterious worlds have been portrayed as fascinating environments of adventure and exploration from narratives such as that of Lawrence of Arabia to movies such as "Dune." These arid regions are called deserts because they are dry. They may be hot, they may be cold. They may be regions of sand or vast areas of rocks and gravel peppered with occasional plants. But deserts are always dry. Deserts are natural laboratories in which to study the interactions of wind and sometimes water on the arid surfaces of planets. They contain valuable mineral deposits that were formed in the arid environment or that were exposed by erosion. Because deserts are dry, they are ideal places for human artifacts and fossils to be preserved. Deserts are also fragile environments. The misuse of these lands is a serious and growing problem in parts of our world.

Geochemical sampling in arid environments by the U.S. Geological Survey

USGS Publications Warehouse

Hinkle, Margaret E.

1988-01-01

The U.S. Geological Survey (USGS) is responsible for the geochemical evaluations used for mineral resource assessments of large tracts of public lands in the Western United States. Many of these lands are administered by the Bureau of Land Management (BLM) and are studied to determine their suitability or nonsuitability for wilderness designation. Much of the Western United States is arid or semiarid. This report discusses various geochemical sample media that have been used for evaluating areas in arid environments and describes case histories in BLM wilderness study areas in which stream-sediment and heavy-mineral-concentrate sample media were compared. As a result of these case history studies, the nonmagnetic fraction of panned heavy-mineral concentrates was selected as the most effective medium for reconnaissance geochemical sampling for resources other than gold, in arid areas. Nonmagnetic heavy-mineral-concentrate samples provide the primary analytical information currently used in geochemical interpretations of mineral resource potential assessment of BLM lands.

Bacterial polyextremotolerant bioemulsifiers from arid soils improve water retention capacity and humidity uptake in sandy soil.

PubMed

Raddadi, Noura; Giacomucci, Lucia; Marasco, Ramona; Daffonchio, Daniele; Cherif, Ameur; Fava, Fabio

2018-05-31

Water stress is a critical issue for plant growth in arid sandy soils. Here, we aimed to select bacteria producing polyextremotolerant surface-active compounds capable of improving water retention and humidity uptake in sandy soils. From Tunisian desert and saline systems, we selected eleven isolates able to highly emulsify different organic solvents. The bioemulsifying activities were stable with 30% NaCl, at 4 and 120 °C and in a pH range 4-12. Applications to a sandy soil of the partially purified surface-active compounds improved soil water retention up to 314.3% compared to untreated soil. Similarly, after 36 h of incubation, the humidity uptake rate of treated sandy soil was up to 607.7% higher than untreated controls. Overall, results revealed that polyextremotolerant bioemulsifiers of bacteria from arid and desert soils represent potential sources to develop new natural soil-wetting agents for improving water retention in arid soils.

Energy and water in aestivating amphibians.

PubMed

Carvalho, José E; Navas, Carlos A; Pereira, Isabel C

2010-01-01

The physiological mechanisms, behavioral adjustments, and ecological associations that allow animal species to live in extreme environments have evoked the attention of many zoologists. Often, extreme environments are defined as those believed to be limiting to life in terms of water, energetic availability, and temperature. These three elements seem extreme in a number of arid and semi-arid settings that even so have been colonized by amphibians. Because this taxon is usually seen as the quintessential water-dependent ectotherm tetrapods, their presence in a number of semi-arid environments poses a number of intriguing questions regarding microhabitat choice and physiological plasticity, particularly regarding the ecological and physiological correlates of behaviors granting avoidance of the harshest conditions of semi-arid environments. Such avoidance states, generally associated to the concept of aestivation, are currently seen as a diverse and complex phenomena varying from species to species and involving numerous behavioral and metabolic adjustments that enhance survival during the drought. This chapter reviews the physiological ecology of anuran aestivation, mainly from the perspective of water and energy balance.

Effects of eco-friendly carbohydrate-based superabsorbent polymers on seed germination and seedling growth of maize.

PubMed

Tao, Jinghe; Zhang, Wenxu; Liang, Li; Lei, Ziqiang

2018-02-01

Desertification is the degradation of land in arid and semi-arid areas. Nowadays, lack of water and desertification are extreme problems for plant survival and growth in the arid and semi-arid areas of the world. It becomes increasingly important as to how to let the plant absorb moisture more effectively for keeping growth strong. We synthesized superabsorbent polymers (SAPs) with carbohydrate and characterized them by Fourier transform infrared spectra analyses, scanning electron microscopy and thermogravimetric/differential thermal analyses. Then, a completely randomized experiment was conducted to assess the effect of carbohydrate-based SAPs on seed germination and seedling growth of maize in an artificial climate chest. The results showed that adding an appropriate amount of SAPs could improve root length, shoot length, total biomass, germination potential and germination rate. It indicates that this SAP is not toxic to plants and can promote seed germination, and at the same time provides a possibility of replacing other substrates.

Effects of eco-friendly carbohydrate-based superabsorbent polymers on seed germination and seedling growth of maize

NASA Astrophysics Data System (ADS)

Tao, Jinghe; Zhang, Wenxu; Liang, Li; Lei, Ziqiang

2018-02-01

Desertification is the degradation of land in arid and semi-arid areas. Nowadays, lack of water and desertification are extreme problems for plant survival and growth in the arid and semi-arid areas of the world. It becomes increasingly important as to how to let the plant absorb moisture more effectively for keeping growth strong. We synthesized superabsorbent polymers (SAPs) with carbohydrate and characterized them by Fourier transform infrared spectra analyses, scanning electron microscopy and thermogravimetric/differential thermal analyses. Then, a completely randomized experiment was conducted to assess the effect of carbohydrate-based SAPs on seed germination and seedling growth of maize in an artificial climate chest. The results showed that adding an appropriate amount of SAPs could improve root length, shoot length, total biomass, germination potential and germination rate. It indicates that this SAP is not toxic to plants and can promote seed germination, and at the same time provides a possibility of replacing other substrates.

Effects of eco-friendly carbohydrate-based superabsorbent polymers on seed germination and seedling growth of maize

PubMed Central

Tao, Jinghe; Liang, Li; Lei, Ziqiang

2018-01-01

Desertification is the degradation of land in arid and semi-arid areas. Nowadays, lack of water and desertification are extreme problems for plant survival and growth in the arid and semi-arid areas of the world. It becomes increasingly important as to how to let the plant absorb moisture more effectively for keeping growth strong. We synthesized superabsorbent polymers (SAPs) with carbohydrate and characterized them by Fourier transform infrared spectra analyses, scanning electron microscopy and thermogravimetric/differential thermal analyses. Then, a completely randomized experiment was conducted to assess the effect of carbohydrate-based SAPs on seed germination and seedling growth of maize in an artificial climate chest. The results showed that adding an appropriate amount of SAPs could improve root length, shoot length, total biomass, germination potential and germination rate. It indicates that this SAP is not toxic to plants and can promote seed germination, and at the same time provides a possibility of replacing other substrates. PMID:29515838

Human evolution. Evolution of early Homo: an integrated biological perspective.

PubMed

Antón, Susan C; Potts, Richard; Aiello, Leslie C

2014-07-04

Integration of evidence over the past decade has revised understandings about the major adaptations underlying the origin and early evolution of the genus Homo. Many features associated with Homo sapiens, including our large linear bodies, elongated hind limbs, large energy-expensive brains, reduced sexual dimorphism, increased carnivory, and unique life history traits, were once thought to have evolved near the origin of the genus in response to heightened aridity and open habitats in Africa. However, recent analyses of fossil, archaeological, and environmental data indicate that such traits did not arise as a single package. Instead, some arose substantially earlier and some later than previously thought. From ~2.5 to 1.5 million years ago, three lineages of early Homo evolved in a context of habitat instability and fragmentation on seasonal, intergenerational, and evolutionary time scales. These contexts gave a selective advantage to traits, such as dietary flexibility and larger body size, that facilitated survival in shifting environments. Copyright © 2014, American Association for the Advancement of Science.

Integrative Genomic Analysis of Cholangiocarcinoma Identifies Distinct IDH-Mutant Molecular Profiles.

PubMed

Farshidfar, Farshad; Zheng, Siyuan; Gingras, Marie-Claude; Newton, Yulia; Shih, Juliann; Robertson, A Gordon; Hinoue, Toshinori; Hoadley, Katherine A; Gibb, Ewan A; Roszik, Jason; Covington, Kyle R; Wu, Chia-Chin; Shinbrot, Eve; Stransky, Nicolas; Hegde, Apurva; Yang, Ju Dong; Reznik, Ed; Sadeghi, Sara; Pedamallu, Chandra Sekhar; Ojesina, Akinyemi I; Hess, Julian M; Auman, J Todd; Rhie, Suhn K; Bowlby, Reanne; Borad, Mitesh J; Zhu, Andrew X; Stuart, Josh M; Sander, Chris; Akbani, Rehan; Cherniack, Andrew D; Deshpande, Vikram; Mounajjed, Taofic; Foo, Wai Chin; Torbenson, Michael S; Kleiner, David E; Laird, Peter W; Wheeler, David A; McRee, Autumn J; Bathe, Oliver F; Andersen, Jesper B; Bardeesy, Nabeel; Roberts, Lewis R; Kwong, Lawrence N

2017-03-14

Cholangiocarcinoma (CCA) is an aggressive malignancy of the bile ducts, with poor prognosis and limited treatment options. Here, we describe the integrated analysis of somatic mutations, RNA expression, copy number, and DNA methylation by The Cancer Genome Atlas of a set of predominantly intrahepatic CCA cases and propose a molecular classification scheme. We identified an IDH mutant-enriched subtype with distinct molecular features including low expression of chromatin modifiers, elevated expression of mitochondrial genes, and increased mitochondrial DNA copy number. Leveraging the multi-platform data, we observed that ARID1A exhibited DNA hypermethylation and decreased expression in the IDH mutant subtype. More broadly, we found that IDH mutations are associated with an expanded histological spectrum of liver tumors with molecular features that stratify with CCA. Our studies reveal insights into the molecular pathogenesis and heterogeneity of cholangiocarcinoma and provide classification information of potential therapeutic significance. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Transition from arid to hyper-arid environment in the southern Levant deserts as recorded by early Pleistocene cummulic Aridisols

NASA Astrophysics Data System (ADS)

Amit, Rivka; Simhai, Ori; Ayalon, Avner; Enzel, Yehouda; Matmon, Ari; Crouvi, Onn; Porat, Naomi; McDonald, Eric

2011-02-01

The time at which deserts established their current arid or hyper-arid conditions remains a fundamental question regarding the history of Earth. Cosmogenic isotope exposure ages of desert pavement and welded, calcic-gypsic-salic Reg soils that developed on relatively flat alluvial surfaces ˜2 Ma ago in the Negev Desert indicate long geomorphic stability under extremely dry conditions. Over a short interval during their initial stage of development between 1-2 Ma, these cumulative soils are characterized by calcic soils reaching maximum stage III of carbonate morphology. This interval is the only period when calcic soil horizons formed on stable abandoned alluvial surfaces in the southern Negev Desert. Since ˜1 Ma pedogenesis changed toward more arid soil environment and the formation of gypsic-salic soil horizons that were later followed by dust accumulation. The dichotomy of only moderately-developed calcic soil (stages II-III) during a relatively long time interval (10 5-10 6 years) indicates an arid environment that does not support continuous development but only occasional calcic soil formation. The very low δ18O and relatively high δ13C values of these early pedogenic carbonates support soil formation under arid climatic conditions. Such an environment was probably characterized by rare and relatively longer duration rainstorms which occasionally allowed deeper infiltration of rainwater and longer retention of soil moisture. This, in turn enabled the growth of sparse vegetation that enhanced deposition of pedogenic carbonate. At ˜1 Ma these rare events of slightly wetter conditions ceased and less atmospheric moisture reached the southern Negev Desert leading to deposition of soluble salts and dust deposited in the soils. The combination of long-term hyperaridity, scarcity of vegetation and lack of bioturbation, salts cementation, dust accumulation and tight desert pavement cover, has protected the surfaces from erosion forming one of the most remarkably stable landscapes on Earth, a landscape that essentially has not eroded, but accumulated salt and dust for more than 10 6 yr.

ARID5B polymorphism confers an increased risk to acquire specific MLL rearrangements in early childhood leukemia

PubMed Central

2014-01-01

Background Acute leukemia in early age (EAL) is characterized by acquired genetic alterations such as MLL rearrangements (MLL-r). The aim of this case-controlled study was to investigate whether single nucleotide polymorphisms (SNPs) of IKZF1, ARID5B, and CEBPE could be related to the onset of EAL cases (<24 months-old at diagnosis). Methods The SNPs (IKZF1 rs11978267, ARID5B rs10821936 and rs10994982, CEBPE rs2239633) were genotyped in 265 cases [169 acute lymphoblastic leukemia (ALL) and 96 acute myeloid leukaemia (AML)] and 505 controls by Taqman allelic discrimination assay. Logistic regression was used to evaluate the association between SNPs of cases and controls, adjusted on skin color and/or age. The risk was determined by calculating odds ratios (ORs) with 95% confidence interval (CI). Results Children with the IKZF1 SNP had an increased risk of developing MLL-germline ALL in white children. The heterozygous/mutant genotype in ARID5B rs10994982 significantly increased the risk for MLL-germline leukemia in white and non-white children (OR 2.60, 95% CI: 1.09-6.18 and OR 3.55, 95% CI: 1.57-8.68, respectively). The heterozygous genotype in ARID5B rs10821936 increased the risk for MLL-r leukemia in both white and non-white (OR 2.06, 95% CI: 1.12-3.79 and OR 2.36, 95% CI: 1.09-5.10, respectively). Furthermore, ARID5B rs10821936 conferred increased risk for MLL-MLLT3 positive cases (OR 7.10, 95% CI:1.54-32.68). Our data do not show evidence that CEBPE rs2239633 confers increased genetic susceptibility to EAL. Conclusions IKZF1 and CEBPE variants seem to play a minor role in genetic susceptibility to EAL, while ARID5B rs10821936 increased the risk of MLL-MLLT3. This result shows that genetic susceptibility could be associated with the differences regarding MLL breakpoints and partner genes. PMID:24564228

Life-history responses of insects to water-deficit stress: a case study with the aphid Sitobion avenae.

PubMed

Liu, Deguang; Dai, Peng; Li, Shirong; Ahmed, Syed Suhail; Shang, Zheming; Shi, Xiaoqin

2018-05-29

Drought may become one of the greatest challenges for cereal production under future warming scenarios, and its impact on insect pest outbreaks is still controversial. To address this issue, life-history responses of the English grain aphid, Sitobion avenae (Fabricius), from three areas of different drought levels were compared under three water treatments. Significant differences were identified in developmental time, fecundity and adult weight among S. avenae clones from moist, semiarid and arid areas under all the three water treatments. Semiarid and arid area clones tended to have higher heritability for test life-history traits than moist area clones. We identified significant selection of water-deficit on the developmental time of 1st instar nymphs and adult weight for both semiarid and arid area clones. The impact of intermediate and severe water-stress on S. avenae's fitness was neutral and negative (e.g., decreased fecundity and weight), respectively. Compared with arid-area clones, moist- and semiarid-area clones showed higher extents of adaptation to the water-deficit level of their respective source environment. Adult weight was identified as a good indicator for S. avenae's adaptation potential under different water-stress conditions. After their exposure to intermediate water-deficit stress for only five generations, adult weight and fecundity tended to decrease for moist- and semiarid-area clones, but increase for arid-area clones. It is evident from our study that S. avenae clones from moist, semiarid and arid areas have diverged under different water-deficit stress, and such divergence could have a genetic basis. The impact of drought on S. avenae's fitness showed a water-level dependent pattern. Clones of S. avenae were more likely to become adapted to intermediate water-deficit stress than severe water-deficit stress. After continuous water-deficit stress of only five generations, the adaptation potential of S. avenae tended to decrease for moist and semiarid area clones, but increase for arid area clones. The rapid shift of aphids' life-history traits and adaptation potential under drought could have significant implications for their evolutionary dynamics and outbreak risks in future climate change scenarios.

The Dynamics of a Semi-Arid Region in Response to Climate and Water - Use Policy

NASA Technical Reports Server (NTRS)

Mustard, John F.; Hamburg, Steve; Grant, John A.; Manning, Sara J.; Steinwand, Aaron; Howard, Chris

2000-01-01

The objectives of this project were to determine the response of semi-arid ecosystems to the combined forcings of climate variability and anthropogenic stress. Arid and semi-arid systems encompass close to 40% of the worlds land surface. The ecology of these regions are principally limited by water, and as the water resources wax and wane, so should the health and vigor of the ecosystems. Water, however, is a necessary and critical resource for humans living in these same regions. Thus for many and and semi-arid regions the natural systems and human systems are in direct competition for a limited resource. Increasing competition through development of and and semi-arid regions, export of water resources, as well as potential persistent changes in weather patterns are likely to lead to fundamental changes in carrying capacity, resilience, and ecology of these regions. A detailed understanding of these systems respond to forcing on a regional and local scale is required in order to better prepare for and manage future changes in the availability of water. In the Owens Valley CA, decadal changes in rainfall and increased use of groundwater resources by Los Angles (which derives 60-70% of its water from this region) have resulted in a large-scale experiment on the impacts of these changes in semi-arid ecosystems. This project works directly with the Inyo County Water Department (local water authority) and the Los Angles Department of Water and Power (regional demand on water resources) to understand changes, their causes, and impacts. Very detailed records have been kept for a number of selected sites in the valley which provide essential ground truth. These results are then scaled up through remote sensed data to regions scale to assess large scale patterns and link them to the fundamental decisions regarding the water resources of this region. A fundamental goal is to understand how resilient the native ecosystems are to large changes in water resources. Are they are on a spring (remove and return resources, do the systems return to the original state) or a vector (when water returns have the systems fundamentally changed).

Vegetative and reproductive phenology of a floodplain tree species Barringtonia acutangula from North East India.

PubMed

Nath, Shikhasmita; Nath, Arun Jyoti; Das, Ashesh Kumar

2016-03-01

Vegetative and reproductive phenology of Barringtonia acutangula, a floodplain tree species was studied at Chatla floodplain, Assam North East India with the aim to investigate vegetative and reproductive phenology under stressful environment of seasonal submergence and to assess the impact of environmental variables (temperature and precipitation) on tree phenophases. Quantitative assessment was made at 15 day interval for all the phenophases (leaf initiation, leaf-fall, flowering and fruiting) by tagging 40 (forty) trees over aperiod of two years (2012-14).To test seasonal influence on the phenology of Barringtonia acutangula different phenophases were correlated with environmental variables and statistical spearman's rank correlation coefficient was employed. Aridity index was computed that delineate influence of rainfall and temperature together on any phenophases. Leaf initiation showed positively significant correlation with temperature (r(s) = 0.601, p = < .05) during the year 2012-2013 whereas it was significantly correlated with rainfall (r(s) = 0.583, p = < .05) and aridity index (r(s) = 0.583, p = < .05) during the year 2013-2014. Leaf-fall was significant negatively correlated with temperature (r(s) = -0.623, p = < .05), rainfall (r(s) = -0.730, p = < .01) and aridity index (r(s) = -0.730, p = < .01) for both the studied years. Flowering was significantly influenced by temperature (r(s) = 0.639, p = < .05), rainfall (r(s) = 0.890, p = < .01) and aridity index (r(s) = 0.890, p = < .01) while in one month lag flowering was significantly correlated with rainfall (r(s) = 0.678, p = < .01) in 2012-13. Fruiting was also positively significant with temperature (r(s) = 0.795, P < .05), rainfall (r(s) = 0.835, P < .01) and aridity index (r(s) = 0.835, P < .01) for both the years. During one month lag period fruiting was positively correlated with temperature, rainfall and aridity index in both the years. Temperature, rainfall and aridity index were major determinants of the various vegetative and reproductive phenology of B. acutangula and any changes in these variables in future due to climate change, might have profound effect on phenophases of this tree species.

Climate Warming Threatens Semi-arid Forests in Inner Asia

NASA Astrophysics Data System (ADS)

WU, X.; Liu, H.; Qi, Z.; Li, X.

2014-12-01

A line of evidences reveal an increasing tree growth decline and tree mortality mainly attributable to climate warming and the warming-mediated changes in drought and other processes (such as fire and insect dynamics) in many parts of world tropical, temperate and boreal forests. However, the growth responses to climate change of the widely distributed semi-arid forests are unclear. Here, we synthetically investigate the tree growth patterns during past decades and its interannual response to climate variations in Inner Asia combining the ground truth field survey and samplings, remote sensing observations and climate data. We identified a pervasive tree growth decline since mid-1990s in semi-arid forests in Inner Asia. The widely observed tree growth decline is dominantly attributable to warming-induced water stress during pre- and early growing season. Tree growth of semi-arid forests in Inner Asia is particularly susceptible to spring warming and has been suffering a prolonged growth limitation in recent decades due to spring warming-mediated water conditions. Additionally, we identified a much slower growth rate in younger trees and a lack of tree regeneration in these semi-arid forests. The widely observed forest growth reduction and lack of tree regeneration over semi-arid forests in Inner Asia could predictably exert great effects on forest structure, regionally/globally biophysical and biochemical processes and the feedbacks between biosphere and atmosphere. Notably, further increases in forest stress and tree mortality could be reasonably expected, especially in context of the increase frequency and severity of high temperature and heat waves and changes in forest disturbances, potentially driving the eventual regional loss of current semi-arid forests. Given the potential risks of climate induced forest dieback, increased management attention to adaptation options for enhancing forest resistance and resilience to projected climate stress can be expected. However, the functionally realistic mechanisms beneath the pervasively climate-induced forest decline/dieback still remain unclear. Network-based long-term surveys and experiment studies are urgently needed for further understandings regarding the responses of forest/tree growth to climate warming/variations.

Salinity Management in Agriculture

USDA-ARS?s Scientific Manuscript database

Existing guidelines and standards for reclamation of saline soils and management to control salinity exist but have not been updated for over 25 years. In the past few years a looming water scarcity has resulted in questioning of the long term future of irrigation projects in arid and semi arid regi...

Genetic analysis of salinity responses in Medicago genotypes

USDA-ARS?s Scientific Manuscript database

Reduced availability of clean water in arid and semi-arid regions will require the use of low-quality/alternative waters for irrigation. The main consideration for using low-quality/alternative waters is often their salt concentration. Plants respond to salinity stress through a complex network of p...

Active old-field restoration in the most arid lands of the Great Basin

USDA-ARS?s Scientific Manuscript database

Restoration of former agricultural fields can be challenging, especially in arid systems, where factors such as wind erosion, water stress, soil alteration, and competition from weeds can strongly affect plant establishment and growth. Experiments were conducted in two former agricultural fields in ...

UVB exposure does not accelerate rates of litter decomposition in a semiarid riparian ecosystem

USDA-ARS?s Scientific Manuscript database

Aboveground litter decomposition is controlled mainly by substrate quality and climate factors across terrestrial ecosystems, but photodegradation from exposure to high-intensity ultraviolet-B (UVB) radiation may also be important in arid and semi-arid environments. We investigated the interactive e...

Extensive Green Roof Species and Soilless Media Evaluations in Semi-arid Colorado

EPA Science Inventory

In the high elevation, semi-arid climate of Colorado, green roofs have not been scientifically tested. This research examined alternative plant species, soilless media blends and plant interactions on an existing, modular-extensive (shallow, 10 cm deep) green roof in Denver, Colo...

A methodology for small scale rural land use mapping in semi-arid developing countries using orbital imagery. 1: Introduction

NASA Technical Reports Server (NTRS)

Vangenderen, J. L. (Principal Investigator); Lock, B. F.

1976-01-01

The author has identified the following significant results. This research program has developed a viable methodology for producing small scale rural land use maps in semi-arid developing countries using imagery obtained from orbital multispectral scanners.

Tillage and Residue Management Effects on Semi-Arid Mediterranean Soil Quality

USDA-ARS?s Scientific Manuscript database

No-tillage practices for semi-arid Mediterranean soils can conserve water and increase crop productivity, but producers are reluctant to adopt those practices because of concern regarding potential increases in penetration resistance and bulk density. We hypothesized that knowing more about all aspe...

A UNIFORM VERSUS AN AGGREGATED WATER BALANCE OF A SEMI-ARID WATERSHED. (R824784)

EPA Science Inventory

Hydrologists have long struggled with the problem of how to account for the effects of spatial variability in precipitation, vegetation and soils. This problem is particularly acute in snow-fed, semi-arid watersheds, which typically have considerable variability in snow distribut...

Aridity and decomposition processes in complex landscapes

NASA Astrophysics Data System (ADS)

Ossola, Alessandro; Nyman, Petter

2015-04-01

Decomposition of organic matter is a key biogeochemical process contributing to nutrient cycles, carbon fluxes and soil development. The activity of decomposers depends on microclimate, with temperature and rainfall being major drivers. In complex terrain the fine-scale variation in microclimate (and hence water availability) as a result of slope orientation is caused by differences in incoming radiation and surface temperature. Aridity, measured as the long-term balance between net radiation and rainfall, is a metric that can be used to represent variations in water availability within the landscape. Since aridity metrics can be obtained at fine spatial scales, they could theoretically be used to investigate how decomposition processes vary across complex landscapes. In this study, four research sites were selected in tall open sclerophyll forest along a aridity gradient (Budyko dryness index ranging from 1.56 -2.22) where microclimate, litter moisture and soil moisture were monitored continuously for one year. Litter bags were packed to estimate decomposition rates (k) using leaves of a tree species not present in the study area (Eucalyptus globulus) in order to avoid home-field advantage effects. Litter mass loss was measured to assess the activity of macro-decomposers (6mm litter bag mesh size), meso-decomposers (1 mm mesh), microbes above-ground (0.2 mm mesh) and microbes below-ground (2 cm depth, 0.2 mm mesh). Four replicates for each set of bags were installed at each site and bags were collected at 1, 2, 4, 7 and 12 months since installation. We first tested whether differences in microclimate due to slope orientation have significant effects on decomposition processes. Then the dryness index was related to decomposition rates to evaluate if small-scale variation in decomposition can be predicted using readily available information on rainfall and radiation. Decomposition rates (k), calculated fitting single pool negative exponential models, generally decreased with increasing aridity with k going from 0.0025 day-1 on equatorial (dry) facing slopes to 0.0040 day-1 on polar (wet) facing slopes. However, differences in temperature as a result of morning vs afternoon sun on east and west aspects, respectively, (not captured in the aridity metric) resulted in poor prediction of decomposition for the sites located in the intermediate aridity range. Overall the results highlight that relatively small differences in microclimate due to slope orientation can have large effects on decomposition. Future research will aim to refine the aridity metric to better resolve small scale variation in surface temperature which is important when up-scaling decomposition processes to landscapes.

Determination of actual crop evapotranspiration (ETc) and dual crop coefficients (Kc) for cotton, wheat and maize in Fergana Valley: integration of the FAO-56 approach and BUDGET

NASA Astrophysics Data System (ADS)

Kenjabaev, Shavkat; Dernedde, Yvonne; Frede, Hans-Georg; Stulina, Galina

2014-05-01

Determination of the actual crop evapotranspiration (ETc) during the growing period is important for accurate irrigation scheduling in arid and semi-arid regions. Development of a crop coefficient (Kc) can enhance ETc estimations in relation to specific crop phenological development. This research was conducted to determine daily and growth-stage-specific Kc and ETc values for cotton (Gossypium hirsutum L.), winter wheat (Triticum aestivum L.) and maize (Zea mays L.) for silage at fields in Fergana Valley (Uzbekistan). The soil water balance model - Budget with integration of the dual crop procedure of the FAO-56 was used to estimate the ETc and separate it into evaporation (Ec) and transpiration (Tc) components. An empirical equation was developed to determine the daily Kc values based on the estimated Ec and Tc. The ETc, Kc determination and comparison to existing FAO Kc values were performed based on 10, 5 and 6 study cases for cotton, wheat and maize, respectively. Mean seasonal amounts of crop water consumption in terms of ETc were 560±50, 509±27 and 243±39 mm for cotton, wheat and maize, respectively. The growth-stage-specific Kc for cotton, wheat and maize was 0.15, 0.27 and 0.11 at initial; 1.15, 1.03 and 0.56 at mid; and 0.45, 0.89 and 0.53 at late season stages. These values correspond to those reported by the FAO-56. Development of site specific Kc helps tremendously in irrigation management and furthermore provides precise water applications in the region. The developed simple approach to estimate daily Kc for the three main crops grown in the Fergana region was a first attempt to meet this issue. Keywords: Actual crop evapotranspiration, evaporation and transpiration, crop coefficient, model BUDGET, Fergana Valley.

Acclimation of Pistacia integerrima trees to frost in semi-arid environments depends on autumn's drought.

PubMed

Sperling, Or; Secchi, Francesca; Godfrey, Jessie; Zwieniecki, Maciej A

2017-03-01

Main conclusion Cold acclimation is revealed through induced stem respiration during pre-winter frost of native Pistacia integerrima trees in continental semi-arid environments. Semi-arid environments challenge vegetation by simultaneous abiotic stresses. In this study, we examine the combined effects of water stress and frost on the physiology of Pistacia integerrima stems. This species is native to semi-arid environments where drought and frost frequently co-occur. We quantified carbohydrates and proline in P. integerrima stems responding to frost and experiencing water potentials between -0.2 and -1.8 MPa. We report that dehydrated trees (i.e., Ψ stem  <=-1 MPa) had more soluble sugars and proline than the well-watered trees (-0.2 MPa). The dehydrated trees also froze at lower temperatures and were less damaged by freezing. Interestingly, we observed a significant increase in stem CO 2 efflux at near-freezing temperatures that could be linked to frost protection. This novel finding challenges current paradigm of plant respiration-kinetics which predicts, according to Arrhenius equation, lower respiration rates during frost. Our results support the notion that drought and frost are analogous stresses that can independently activate corresponding physiological processes in trees and amplify protection. This inevitable stress response 'collaboration' may be the key to understanding how non-dormant perennial plants survive the highly variable weather patterns of early winters in semi-arid environments.

Phylogenetic and morphological investigation of the Mochlus afer-sundevallii species complex (Squamata: Scincidae) across the arid corridor of sub-Saharan Africa.

PubMed

Freitas, Elyse S; Bauer, Aaron M; Siler, Cameron D; Broadley, Donald G; Jackman, Todd R

2018-06-02

The aridification of Africa resulted in the fragmentation of forests and the expansion of an arid corridor stretching from the northeast to southwest portion of sub-Saharan Africa, but the role this corridor has had in species-level diversification of southern African vertebrates is poorly understood. The skink species Mochlus afer and M. sundevallii inhabit wide areas of the arid corridor and are therefore an ideal species pair for studying patterns of genetic and phenotypic diversity associated with this landscape. However, species boundaries between these taxa have been controversial. Using multi-locus molecular and morphological datasets, we investigate diversification patterns of the M. afer-sundevallii Species Complex across the arid corridor. Although analyses of genetic data reveals some genetic structure among geographic populations, results of phylogenetic and morphological analyses provide little support for two distinct evolutionary lineages, suggesting that populations previously referred to as M. afer and M. sundevallii represent a single species, Mochlus sundevallii. Genetic diversity is unequally distributed across the arid corridor, with observed patterns consistent with aridification-facilitated diversification southward across southern Africa. Additional geographic and population-level sampling is necessary before more conclusive inferences can be drawn about the role historical climate transitions have played in skink diversification patterns across southern Africa. Copyright © 2018 Elsevier Inc. All rights reserved.

Deep Soil Recharge in Arid and Semi-Arid Regions: New Evidences in MU-US Sandy Land of China

NASA Astrophysics Data System (ADS)

Cheng, Y.; Yang, W.; Zhan, H.

2017-12-01

Precipitation induced recharge is an important source of groundwater budget but it is very difficult to quantify in arid and semiarid regions. In this study, a newly invented lysimeter was used to monitor deep soil recharge (DSR) under 200 cm depth in MU-US sandy land in western China under three kinds of landforms (mobile dune, semi-fixed dune, and fixed dune). We found that the annual DSRs in such three different kinds of landforms varied significantly. Specifically, the annual DSRs were 224.1 mm (50.5% of the annual precipitation), 71.1 mm (50.5% of the annual precipitation), and 1.3 mm (0.3% of the annual precipitation) in mobile dune, semi-fixed dune, and fixed dune, respectively. We also found that vegetation coverage and precipitation pattern significantly affected DSR. A 24-hr precipitation event with the precipitation amount greater than 8 mm was able to infiltrate soil deeper than 200 cm and contributed to ground water recharge directly. Vegetation was a dominant factor influencing infiltration in the fixed sand dune. Our research revealed that precipitation induced DSR in arid and semi-arid regions was a complex process that required long-term monitoring and innovative system analysis of interrelated factors such as precipitation strength and pattern, meteorological parameters, and dynamic soil moisture. Key words: Precipitation pattern, sand dune groundwater, deep soil recharge, infiltration.

Modeling daily soil temperature over diverse climate conditions in Iran—a comparison of multiple linear regression and support vector regression techniques

NASA Astrophysics Data System (ADS)

Delbari, Masoomeh; Sharifazari, Salman; Mohammadi, Ehsan

2018-02-01

The knowledge of soil temperature at different depths is important for agricultural industry and for understanding climate change. The aim of this study is to evaluate the performance of a support vector regression (SVR)-based model in estimating daily soil temperature at 10, 30 and 100 cm depth at different climate conditions over Iran. The obtained results were compared to those obtained from a more classical multiple linear regression (MLR) model. The correlation sensitivity for the input combinations and periodicity effect were also investigated. Climatic data used as inputs to the models were minimum and maximum air temperature, solar radiation, relative humidity, dew point, and the atmospheric pressure (reduced to see level), collected from five synoptic stations Kerman, Ahvaz, Tabriz, Saghez, and Rasht located respectively in the hyper-arid, arid, semi-arid, Mediterranean, and hyper-humid climate conditions. According to the results, the performance of both MLR and SVR models was quite well at surface layer, i.e., 10-cm depth. However, SVR performed better than MLR in estimating soil temperature at deeper layers especially 100 cm depth. Moreover, both models performed better in humid climate condition than arid and hyper-arid areas. Further, adding a periodicity component into the modeling process considerably improved the models' performance especially in the case of SVR.

Cultural innovation and megafauna interaction in the early settlement of arid Australia.

PubMed

Hamm, Giles; Mitchell, Peter; Arnold, Lee J; Prideaux, Gavin J; Questiaux, Daniele; Spooner, Nigel A; Levchenko, Vladimir A; Foley, Elizabeth C; Worthy, Trevor H; Stephenson, Birgitta; Coulthard, Vincent; Coulthard, Clifford; Wilton, Sophia; Johnston, Duncan

2016-11-10

Elucidating the material culture of early people in arid Australia and the nature of their environmental interactions is essential for understanding the adaptability of populations and the potential causes of megafaunal extinctions 50-40 thousand years ago (ka). Humans colonized the continent by 50 ka, but an apparent lack of cultural innovations compared to people in Europe and Africa has been deemed a barrier to early settlement in the extensive arid zone. Here we present evidence from Warratyi rock shelter in the southern interior that shows that humans occupied arid Australia by around 49 ka, 10 thousand years (kyr) earlier than previously reported. The site preserves the only reliably dated, stratified evidence of extinct Australian megafauna, including the giant marsupial Diprotodon optatum, alongside artefacts more than 46 kyr old. We also report on the earliest-known use of ochre in Australia and Southeast Asia (at or before 49-46 ka), gypsum pigment (40-33 ka), bone tools (40-38 ka), hafted tools (38-35 ka), and backed artefacts (30-24 ka), each up to 10 kyr older than any other known occurrence. Thus, our evidence shows that people not only settled in the arid interior within a few millennia of entering the continent, but also developed key technologies much earlier than previously recorded for Australia and Southeast Asia.

The recharge process in alluvial strip aquifers in arid Namibia and implication for artificial recharge

NASA Astrophysics Data System (ADS)

Sarma, Diganta; Xu, Yongxin

2017-01-01

Alluvial strip aquifers associated with ephemeral rivers are important groundwater supply sources that sustain numerous settlements and ecological systems in arid Namibia. More than 70 % of the population in the nation's western and southern regions depend on alluvial aquifers associated with ephemeral rivers. Under natural conditions, recharge occurs through infiltration during flood events. Due to the characteristic spatial and temporal variability of rainfall in arid regions, recharge is irregular making the aquifers challenging to manage sustainably and they are often overexploited. This condition is likely to become more acute with increasing water demand and climate change, and artificial recharge has been projected as the apparent means of increasing reliability of supply. The article explores, through a case study and numerical simulation, the processes controlling infiltration, significance of surface water and groundwater losses, and possible artificial recharge options. It is concluded that recharge processes in arid alluvial aquifers differ significantly from those processes in subhumid systems and viability of artificial recharge requires assessment through an understanding of the natural recharge process and losses from the aquifer. It is also established that in arid-region catchments, infiltration through the streambed occurs at rates dependent on factors such as antecedent conditions, flow rate, flow duration, channel morphology, and sediment texture and composition. The study provides an important reference for sustainable management of alluvial aquifer systems in similar regions.

The influence of foraging mode and arid adaptation on the basal metabolic rates of burrowing mammals.

PubMed

White, Craig R

2003-01-01

Two competing but nonexclusive hypotheses to explain the reduced basal metabolic rate (BMR) of mammals that live and forage underground (fossorial species) are examined by comparing this group with burrowing mammals that forage on the surface (semifossorial species). These hypotheses suggest that the low BMR of fossorial species either compensates for the enormous energetic demands of subterranean foraging (the cost-of-burrowing hypothesis) or prevents overheating in closed burrow systems (the thermal-stress hypothesis). Because phylogentically informed allometric analysis showed that arid burrowing mammals have a significantly lower BMR than mesic ones, fossorial and semifossorial species were compared within these groups. The BMRs of mesic fossorial and semifossorial mammals could not be reliably distinguished, nor could the BMRs of large (>77 g) arid fossorial and semifossorial mammals. This finding favours the thermal-stress hypothesis, because the groups appear to have similar BMRs despite differences in foraging costs. However, in support of the cost-of-burrowing hypothesis, small (<77 g) arid fossorial mammals were found to have a significantly lower BMR than semifossorial mammals of the similar size. Given the high mass-specific metabolic rates of small animals, they are expected to be under severe energy and water stress in arid environments. Under such conditions, the greatly reduced BMR of small fossorial species may compensate for the enormous energetic demands of subterranean foraging.

Agave proves to be a low recalcitrant lignocellulosic feedstock for biofuels production on semi-arid lands.

PubMed

Li, Hongjia; Pattathil, Sivakumar; Foston, Marcus B; Ding, Shi-You; Kumar, Rajeev; Gao, Xiadi; Mittal, Ashutosh; Yarbrough, John M; Himmel, Michael E; Ragauskas, Arthur J; Hahn, Michael G; Wyman, Charles E

2014-01-01

Agave, which is well known for tequila and other liquor production in Mexico, has recently gained attention because of its attractive potential to launch sustainable bioenergy feedstock solutions for semi-arid and arid lands. It was previously found that agave cell walls contain low lignin and relatively diverse non-cellulosic polysaccharides, suggesting unique recalcitrant features when compared to conventional C4 and C3 plants. Here, we report sugar release data from fungal enzymatic hydrolysis of non-pretreated and hydrothermally pretreated biomass that shows agave to be much less recalcitrant to deconstruction than poplar or switchgrass. In fact, non-pretreated agave has a sugar release five to eight times greater than that of poplar wood and switchgrass . Meanwhile, state of the art techniques including glycome profiling, nuclear magnetic resonance (NMR), Simon's Stain, confocal laser scanning microscopy and so forth, were applied to measure interactions of non-cellulosic wall components, cell wall hydrophilicity, and enzyme accessibility to identify key structural features that make agave cell walls less resistant to biological deconstruction when compared to poplar and switchgrass. This study systematically evaluated the recalcitrant features of agave plants towards biofuels applications. The results show that not only does agave present great promise for feeding biorefineries on semi-arid and arid lands, but also show the value of studying agave's low recalcitrance for developments in improving cellulosic energy crops.

75 years of dryland science: Trends and gaps in arid ecology literature

PubMed Central

Dickman, Chris R.; Wardle, Glenda M.

2017-01-01

Growth in the publication of scientific articles is occurring at an exponential rate, prompting a growing need to synthesise information in a timely manner to combat urgent environmental problems and guide future research. Here, we undertake a topic analysis of dryland literature over the last 75 years (8218 articles) to identify areas in arid ecology that are well studied and topics that are emerging. Four topics—wetlands, mammal ecology, litter decomposition and spatial modelling, were identified as ‘hot topics’ that showed higher than average growth in publications from 1940 to 2015. Five topics—remote sensing, climate, habitat and spatial, agriculture and soils-microbes, were identified as ‘cold topics’, with lower than average growth over the survey period, but higher than average numbers of publications. Topics in arid ecology clustered into seven broad groups on word-based similarity. These groups ranged from mammal ecology and population genetics, broad-scale management and ecosystem modelling, plant ecology, agriculture and ecophysiology, to populations and paleoclimate. These patterns may reflect trends in the field of ecology more broadly. We also identified two broad research gaps in arid ecology: population genetics, and habitat and spatial research. Collaborations between population genetics and ecologists and investigations of ecological processes across spatial scales would contribute profitably to the advancement of arid ecology and to ecology more broadly. PMID:28384186

The Sand Land Soil System and Society

NASA Astrophysics Data System (ADS)

Mahjoory, R. A.

Worldwide arid soils such as Latterites from African Savannas to the Xeralfs and Xererts of the Mediterranean Basin Ortents and Orthids of Asian Deserts are uniquely different in their strategic roles for utilizing the land in places where a delicate balance between annual climatic cycles and general trends toward desertification predominate Arid lands cover 1 3 of global land surface and contain irreplaceable natural resources with potential productivity of meeting the demands of more than two billion people and serving as sources and sinks of atmospheric CO2 to combat global warming The soil system in these arid areas are being degraded underutilized and kept in a stage of obliviousness due to inadequate public literacy and most importantly in-sufficient scientific evaluations based on pedology and soil taxonomy standards Implementation of food security projects and sustainable development programs on randomly selected sites and assessment of land degradation worldwide by powerful computers and satellite imagery techniques without field work and identification of Representative Soil Units are data producing and grant attracting but counter productive We live in a world in which there is an order out there and things are precisely measured and categorized for efficient utilization Why not the soils mainly in arid areas How we could generalize the world of soils under our feet by concept of soils are the same Expansion of educational programs quantification of multiple ecosystems within the arid regions through detailed and correlated

Impact of anthropogenic climate change on wildfire across western US forests.

PubMed

Abatzoglou, John T; Williams, A Park

2016-10-18

Increased forest fire activity across the western continental United States (US) in recent decades has likely been enabled by a number of factors, including the legacy of fire suppression and human settlement, natural climate variability, and human-caused climate change. We use modeled climate projections to estimate the contribution of anthropogenic climate change to observed increases in eight fuel aridity metrics and forest fire area across the western United States. Anthropogenic increases in temperature and vapor pressure deficit significantly enhanced fuel aridity across western US forests over the past several decades and, during 2000-2015, contributed to 75% more forested area experiencing high (>1 σ) fire-season fuel aridity and an average of nine additional days per year of high fire potential. Anthropogenic climate change accounted for ∼55% of observed increases in fuel aridity from 1979 to 2015 across western US forests, highlighting both anthropogenic climate change and natural climate variability as important contributors to increased wildfire potential in recent decades. We estimate that human-caused climate change contributed to an additional 4.2 million ha of forest fire area during 1984-2015, nearly doubling the forest fire area expected in its absence. Natural climate variability will continue to alternate between modulating and compounding anthropogenic increases in fuel aridity, but anthropogenic climate change has emerged as a driver of increased forest fire activity and should continue to do so while fuels are not limiting.

Contrasting responses of water use efficiency to drought across global terrestrial ecosystems

PubMed Central

Yang, Yuting; Guan, Huade; Batelaan, Okke; McVicar, Tim R.; Long, Di; Piao, Shilong; Liang, Wei; Liu, Bing; Jin, Zhao; Simmons, Craig T.

2016-01-01

Drought is an intermittent disturbance of the water cycle that profoundly affects the terrestrial carbon cycle. However, the response of the coupled water and carbon cycles to drought and the underlying mechanisms remain unclear. Here we provide the first global synthesis of the drought effect on ecosystem water use efficiency (WUE = gross primary production (GPP)/evapotranspiration (ET)). Using two observational WUE datasets (i.e., eddy-covariance measurements at 95 sites (526 site-years) and global gridded diagnostic modelling based on existing observation and a data-adaptive machine learning approach), we find a contrasting response of WUE to drought between arid (WUE increases with drought) and semi-arid/sub-humid ecosystems (WUE decreases with drought), which is attributed to different sensitivities of ecosystem processes to changes in hydro-climatic conditions. WUE variability in arid ecosystems is primarily controlled by physical processes (i.e., evaporation), whereas WUE variability in semi-arid/sub-humid regions is mostly regulated by biological processes (i.e., assimilation). We also find that shifts in hydro-climatic conditions over years would intensify the drought effect on WUE. Our findings suggest that future drought events, when coupled with an increase in climate variability, will bring further threats to semi-arid/sub-humid ecosystems and potentially result in biome reorganization, starting with low-productivity and high water-sensitivity grassland. PMID:26983909

Long-term forest resilience to climate change indicated by mortality, regeneration, and growth in semiarid southern Siberia.

PubMed

Xu, Chongyang; Liu, Hongyan; Anenkhonov, Oleg A; Korolyuk, Andrey Yu; Sandanov, Denis V; Balsanova, Larisa D; Naidanov, Bulat B; Wu, Xiuchen

2017-06-01

Several studies have documented that regional climate warming and the resulting increase in drought stress have triggered increased tree mortality in semiarid forests with unavoidable impacts on regional and global carbon sequestration. Although climate warming is projected to continue into the future, studies examining long-term resilience of semiarid forests against climate change are limited. In this study, long-term forest resilience was defined as the capacity of forest recruitment to compensate for losses from mortality. We observed an obvious change in long-term forest resilience along a local aridity gradient by reconstructing tree growth trend and disturbance history and investigating postdisturbance regeneration in semiarid forests in southern Siberia. In our study, with increased severity of local aridity, forests became vulnerable to drought stress, and regeneration first accelerated and then ceased. Radial growth of trees during 1900-2012 was also relatively stable on the moderately arid site. Furthermore, we found that smaller forest patches always have relatively weaker resilience under the same climatic conditions. Our results imply a relatively higher resilience in arid timberline forest patches than in continuous forests; however, further climate warming and increased drought could possibly cause the disappearance of small forest patches around the arid tree line. This study sheds light on climate change adaptation and provides insight into managing vulnerable semiarid forests. © 2016 John Wiley & Sons Ltd.

Spatial heterogeneity of physicochemical properties explains differences in microbial composition in arid soils from Cuatro Cienegas, Mexico.

PubMed

Pajares, Silvia; Escalante, Ana E; Noguez, Ana M; García-Oliva, Felipe; Martínez-Piedragil, Celeste; Cram, Silke S; Eguiarte, Luis Enrique; Souza, Valeria

2016-01-01

Arid ecosystems are characterized by high spatial heterogeneity, and the variation among vegetation patches is a clear example. Soil biotic and abiotic factors associated with these patches have also been well documented as highly heterogeneous in space. Given the low vegetation cover and little precipitation in arid ecosystems, soil microorganisms are the main drivers of nutrient cycling. Nonetheless, little is known about the spatial distribution of microorganisms and the relationship that their diversity holds with nutrients and other physicochemical gradients in arid soils. In this study, we evaluated the spatial variability of soil microbial diversity and chemical parameters (nutrients and ion content) at local scale (meters) occurring in a gypsum-based desert soil, to gain knowledge on what soil abiotic factors control the distribution of microbes in arid ecosystems. We analyzed 32 soil samples within a 64 m(2) plot and: (a) characterized microbial diversity using T-RFLPs of the bacterial 16S rRNA gene, (b) determined soil chemical parameters, and (c) identified relationships between microbial diversity and chemical properties. Overall, we found a strong correlation between microbial composition heterogeneity and spatial variation of cations (Ca(2), K(+)) and anions (HCO[Formula: see text], Cl(-), SO[Formula: see text]) content in this small plot. Our results could be attributable to spatial differences of soil saline content, favoring the patchy emergence of salt and soil microbial communities.

Impact of anthropogenic climate change on wildfire across western US forests

NASA Astrophysics Data System (ADS)

Abatzoglou, John T.; Park Williams, A.

2016-10-01

Increased forest fire activity across the western continental United States (US) in recent decades has likely been enabled by a number of factors, including the legacy of fire suppression and human settlement, natural climate variability, and human-caused climate change. We use modeled climate projections to estimate the contribution of anthropogenic climate change to observed increases in eight fuel aridity metrics and forest fire area across the western United States. Anthropogenic increases in temperature and vapor pressure deficit significantly enhanced fuel aridity across western US forests over the past several decades and, during 2000-2015, contributed to 75% more forested area experiencing high (>1 σ) fire-season fuel aridity and an average of nine additional days per year of high fire potential. Anthropogenic climate change accounted for ˜55% of observed increases in fuel aridity from 1979 to 2015 across western US forests, highlighting both anthropogenic climate change and natural climate variability as important contributors to increased wildfire potential in recent decades. We estimate that human-caused climate change contributed to an additional 4.2 million ha of forest fire area during 1984-2015, nearly doubling the forest fire area expected in its absence. Natural climate variability will continue to alternate between modulating and compounding anthropogenic increases in fuel aridity, but anthropogenic climate change has emerged as a driver of increased forest fire activity and should continue to do so while fuels are not limiting.

A transdisciplinary approach for supporting the integration of ecosystem services into land and water management

NASA Astrophysics Data System (ADS)

Fatt Siew, Tuck; Döll, Petra

2015-04-01

Transdisciplinary approaches are useful for supporting integrated land and water management. However, the implementation of the approach in practice to facilitate the co-production of useable socio-hydrological (and -ecological) knowledge among scientists and stakeholders is challenging. It requires appropriate methods to bring individuals with diverse interests and needs together and to integrate their knowledge for generating shared perspectives/understanding, identifying common goals, and developing actionable management strategies. The approach and the methods need, particularly, to be adapted to the local political and socio-cultural conditions. To demonstrate how knowledge co-production and integration can be done in practice, we present a transdisciplinary approach which has been implemented and adapted for supporting land and water management that takes ecosystem services into account in an arid region in northwestern China. Our approach comprises three steps: (1) stakeholder analysis and interdisciplinary knowledge integration, (2) elicitation of perspectives of scientists and stakeholders, scenario development, and identification of management strategies, and (3) evaluation of knowledge integration and social learning. Our adapted approach has enabled interdisciplinary and cross-sectoral communication among scientists and stakeholders. Furthermore, the application of a combination of participatory methods, including actor modeling, Bayesian Network modeling, and participatory scenario development, has contributed to the integration of system, target, and transformation knowledge of involved stakeholders. The realization of identified management strategies is unknown because other important and representative decision makers have not been involved in the transdisciplinary research process. The contribution of our transdisciplinary approach to social learning still needs to be assessed.

Demonstration of innovative monitoring technologies at the Savannah River Integrated Demonstration Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rossabi, J.; Jenkins, R.A.; Wise, M.B.

1993-12-31

The Department of Energy`s Office of Technology Development initiated an Integrated Demonstration Program at the Savannah River Site in 1989. The objective of this program is to develop, demonstrate, and evaluate innovative technologies that can improve present-day environmental restoration methods. The Integrated Demonstration Program at SRS is entitled ``Cleanup of Organics in Soils and Groundwater at Non-Arid Sites.`` New technologies in the areas of drilling, characterization, monitoring, and remediation are being demonstrated and evaluated for their technical performance and cost effectiveness in comparison with baseline technologies. Present site characterization and monitoring methods are costly, time-consuming, overly invasive, and often imprecise.more » Better technologies are required to accurately describe the subsurface geophysical and geochemical features of a site and the nature and extent of contamination. More efficient, nonintrusive characterization and monitoring techniques are necessary for understanding and predicting subsurface transport. More reliable procedures are also needed for interpreting monitoring and characterization data. Site characterization and monitoring are key elements in preventing, identifying, and restoring contaminated sites. The remediation of a site cannot be determined without characterization data, and monitoring may be required for 30 years after site closure.« less

Development and application of methods used to source prehistoric Southwestern maize: a review

USGS Publications Warehouse

Benson, Larry V.

2012-01-01

Archaeological cobs free of mineral contaminants should be used to source the soils in which they were grown. Mineral contaminants often contain much higher concentrations of metals than vegetal materials and can alter a cob’s apparent metal and heavy-isotope content. Cleaning a cob via immersion in an acid solution for more than a few minutes will result in the incongruent and sometimes complete leaching of metals, including strontium (Sr), from the cob. When using 87Sr/Sr to determine the location of potential agriculture fields, it is best to either integrate several depth-integrated soil samples or to integrate several vegetation samples from individual fields. Biologically labile Sr in semi-arid Southwestern soils largely originates from eolian source or sources and usually is not derived from underlying bedrock. Existing Sr-isotope data indicate that archaeological cobs from Aztec Ruins came from either the Mesa Verde-McElmo Dome or Totah areas, that Pueblo Bonito and Chetro Ketl cobs, from Chaco Canyon that predate A.D. 1130, probably came from the Rio Chaco corridor, and that cobs from Chaco Canyon, that postdate A.D. 1130, probably came from either the Totah or Zuni areas.

Hydrology of prairie wetlands: Understanding the integrated surface-water and groundwater processes

USGS Publications Warehouse

Hayashi, Masaki; van der Kamp, Garth; Rosenberry, Donald O.

2016-01-01

Wetland managers and policy makers need to make decisions based on a sound scientific understanding of hydrological and ecological functions of wetlands. This article presents an overview of the hydrology of prairie wetlands intended for managers, policy makers, and researchers new to this field (e.g., graduate students), and a quantitative conceptual framework for understanding the hydrological functions of prairie wetlands and their responses to changes in climate and land use. The existence of prairie wetlands in the semi-arid environment of the Prairie-Pothole Region (PPR) depends on the lateral inputs of runoff water from their catchments because mean annual potential evaporation exceeds precipitation in the PPR. Therefore, it is critically important to consider wetlands and catchments as highly integrated hydrological units. The water balance of individual wetlands is strongly influenced by runoff from the catchment and the exchange of groundwater between the central pond and its moist margin. Land-use practices in the catchment have a sensitive effect on runoff and hence the water balance. Surface and subsurface storage and connectivity among individual wetlands controls the diversity of pond permanence within a wetland complex, resulting in a variety of eco-hydrological functionalities necessary for maintaining the integrity of prairie-wetland ecosystems.

Integrated genomic and molecular characterization of cervical cancer.

PubMed

2017-03-16

Cervical cancer remains one of the leading causes of cancer-related deaths worldwide. Here we report the extensive molecular characterization of 228 primary cervical cancers, one of the largest comprehensive genomic studies of cervical cancer to date. We observed notable APOBEC mutagenesis patterns and identified SHKBP1, ERBB3, CASP8, HLA-A and TGFBR2 as novel significantly mutated genes in cervical cancer. We also discovered amplifications in immune targets CD274 (also known as PD-L1) and PDCD1LG2 (also known as PD-L2), and the BCAR4 long non-coding RNA, which has been associated with response to lapatinib. Integration of human papilloma virus (HPV) was observed in all HPV18-related samples and 76% of HPV16-related samples, and was associated with structural aberrations and increased target-gene expression. We identified a unique set of endometrial-like cervical cancers, comprised predominantly of HPV-negative tumours with relatively high frequencies of KRAS, ARID1A and PTEN mutations. Integrative clustering of 178 samples identified keratin-low squamous, keratin-high squamous and adenocarcinoma-rich subgroups. These molecular analyses reveal new potential therapeutic targets for cervical cancers.

Spatial patterns of grasses and shrubs in an arid grassland environment

USDA-ARS?s Scientific Manuscript database

In the Chihuahuan Desert of Mexico and New Mexico, shrub invasion is a common problem, and once-abundant grassland ecosystems are being replaced by shrub-dominated habitat. The spatial arrangement of grasses and shrubs in these arid grasslands can provide better insight into community dynamics and c...

Modifying landscape connectivity by reducing wind driven sediment redistribution, northern Chihuahuan Desert, USA

USDA-ARS?s Scientific Manuscript database

Shrub encroachment into perennial grasslands is occurring in many arid and semi-arid parts of the world. As shrubs displace perennial grasslands, bare patches coalesce to enhance soil erosion and sediment fluxes by wind and water transport. Reducing the connectedness of these sediment transport path...

Arid oil-field restoration: native perennial grasses suppress weeds and erosion, but also suppress native shrubs

USDA-ARS?s Scientific Manuscript database

1. Long-lived, drought-tolerant shrubs are dominant components of many arid ecosystems, and shrubs provide multiple ecosystem services (e.g., soil stabilization, herbaceous plant facilitation, carbon storage and wildlife habitat). On denuded sites, shrub restoration is hindered by abiotic (erosion ...

Thin scale ecohydrological data and relations at semi-arid regions: a methodological approach

USDA-ARS?s Scientific Manuscript database

In semi-arid regions worldwide the vegetation is organized in patches surrounded by bare soil with marked differences in their soil properties that play important roles in runoff and infiltration. Chihuahuan-Sonoran and Patagonian Monte deserts regions show floristic similarity greater than that ex...

Habitat use by Mexican criollo and British beef cattle breeds in arid-and semi-arid environments of New Mexico and Chihuahua

USDA-ARS?s Scientific Manuscript database

Background/Question/Methods Livestock grazing is the primary activity on rangelands that encompass nearly half of the Earth’s terrestrial surface and directly supports a quarter of the world’s population. With one person in t...

Fine dust emissions in sandy and silty agricultural soils

USDA-ARS?s Scientific Manuscript database

Dust emissions from strong winds are common in arid and semi-arid regions and occur under both natural and managed land systems. A portable field wind tunnel has been developed to allow measurements of dust emissions from soil surfaces to test the premise that dust concentrations are highly correlat...

The guayule plant : a renewable, domestic source of binder materials for flexible pavement mixtures.

DOT National Transportation Integrated Search

2013-01-01

The guayule (pronounced 'why-YOU-lee') plant grows in arid and semi-arid regions (e.g. the southwestern U.S.) and is a source of natural rubber. It was cultivated and processed during the World War II rubber shortage and is currently being processed ...

Response of the shortgrass steppe plant community to fire

USDA-ARS?s Scientific Manuscript database

Fire is an important driver of ecological pattern and process in grasslands worldwide, although its role in semi-arid systems is less well known. We utilized published studies and new experimental research to 1) provide a synthesis of existing knowledge of fire in the semi-arid grasslands of the Nor...

A Review of Applicability and Effectiveness of Low Impact Development/Green Infrastructure Practices in Arid/Semi-Arid United States

EPA Science Inventory

Southwestern/Western United States is among the fastest growing urbanized area and faces multiple water resource challenges. Low Impact Development (LID) /Green Infrastructure (GI) practices are increasingly popular technologies for managing stormwater; however, LID is often not ...

Revegetation Strategies and Technologies for Restoration of Aridic Saltcedar (Tamarix spp.) Infestation Sites

Treesearch

Kenneth D. Lair

2006-01-01

Critical knowledge gaps exist regarding vegetative recovery in aridic, monotypic saltcedar (Tamarix spp.) stands with no desirable understory plants. Formulation of revegetation strategies that provide site stabilization, resistance to further saltcedar and secondary weed infestation, and acceptable habitat values for affected wildlife species...

Exceedance probability of the standardized precipitation-evapotranspiration index in the Texas High Plains

USDA-ARS?s Scientific Manuscript database

Drought is a common occurrence in many arid and semi-arid regions that can have large negative impacts on water resources and agricultural production. Since agricultural drought is affected by both water supply and demand (precipitation and evapotranspiration), it is beneficial to include both in a...

Insight into sediment transport processes on saline rangeland hillslopes using three-dimensional soil microtopography changes

USDA-ARS?s Scientific Manuscript database

In arid and semi-arid rangeland environments, an accurate understanding of runoff generation and sediment transport processes is key to developing effective management actions and addressing ecosystem response to changes. Yet, many primary processes (namely sheet and splash and concentrated flow ero...

Ecohydrologic response and recovery of a semi-arid shrubland over a five year period following burning

USDA-ARS?s Scientific Manuscript database

Increasing trends in wildfire activity on semi-arid rangelands necessitate advancement in understanding of fire impacts on vegetation, soils, and runoff and erosion processes. This study used artificially applied rainfall and concentrated overland flow experiments to evaluate the ecohydrologic resp...

Influence of soft kernel texture on the flour and baking quality of durum wheat

USDA-ARS?s Scientific Manuscript database

Durum wheat is predominantly grown in semi-arid to arid environments where common wheat does not flourish, especially in the Middle East, North Africa, Mediterranean Basin, and portions of North America. Durum kernels are extraordinarily hard when compared to their common wheat counterparts. Due to ...

Impact of climate change on water quality of an impaired New Mexico river

USDA-ARS?s Scientific Manuscript database

Climate change is predicted to advance runoff timing in snowmelt basins and decrease available water, particularly in arid and semi-arid regions. Researchers have suggested that the impacts of climate change will degrade water quality by reducing dilution. We use coupled snowmelt and water quality m...

Introduction to Biological Soil Crusts

Science.gov Websites

Introduction to Biological Soil Crusts In more arid regions, vegetative cover is generally sparse. Open spaces are usually covered by biological soil crusts, a highly specialized community of cyanobacteria, mosses , and lichens (Figure 1). Biological soil crusts are commonly found in semiarid and arid environments

Monitoring scale-specific and temporal variation in electromagnetic conductivity images

USDA-ARS?s Scientific Manuscript database

In the semi-arid and arid landscapes of southwest USA, irrigation sustains agricultural activity; however, there are increasing demands on water resources. As such spatial temporal variation of soil moisture needs to be monitored. One way to do this is to use electromagnetic (EM) induction instrumen...

GLOBAL CHANGE RESEARCH NEWS #10: MULTIAGENCY, MULTINATIONAL GLOBAL CHANGE RESEARCH EFFORT IN THE UPPER SAN PEDRO BASIN

EPA Science Inventory

This edition reports on a multiagency, multinational global-change research effort that seeks to evaluate the consequences of natural and human-induced changes in semi-arid environments. The Semi-Arid Land-Surface-Atmosphere Program ("SALSA") is focused on the environmentally sen...

Polyacrylamide Molecular Weight and Phosphogypsum Effects on Infiltration and Erosion in Semi-Arid Soils

USDA-ARS?s Scientific Manuscript database

Seal formation at the surface of semi-arid soils during rainstorms reduces soil infiltration rate (IR) and causes runoff and erosion. Surface application of dry anionic polyacrylamide (PAM) with high molecular weight (MW) has been found to be effective in stabilizing soil aggregates, and decreasing ...

Polyacrylamide molecular weight and phosphogypsum effects on infiltration and erosion in semi-arid soils

USDA-ARS?s Scientific Manuscript database

Seal formation at the surface of semi-arid soils during rainstorms reduces soil infiltration rate (IR) and causes runoff and erosion. Surface application of dry anionic polyacrylamide (PAM) with high molecular weight (MW) has been found to be effective in stabilizing soil aggregates, and decreasing ...

Achievements and prospects of genomics-assisted breeding in three legume crops of the semi-arid tropics

USDA-ARS?s Scientific Manuscript database

Advances in sequencing and genotyping technologies have enabled generation of several thousand markers including SSRs, SNPs, DArTs, hundreds of thousands transcript reads and BAC-end sequences in chickpea, pigeonpea and groundnut, three major legume crops of the semi-arid tropics. Comprehensive tran...

Short-term soil responses to late-seeded cover crops in a semi-arid environment

USDA-ARS?s Scientific Manuscript database

Cover crops can expand ecosystem services, though sound management recommendations for their use within semi-arid cropping systems is currently constrained by a lack of information. This study was conducted to determine agroecosystem responses to late-summer seeded cover crops under no-till managem...

National Food Strategy: Kenya’s Approach to the Problem of Feeding the Nation

DTIC Science & Technology

1990-02-01

intercropping, agroforestry , preven- tion of soil erosion and rural afforestation. The new Arid and Semi Arid Lands Authority (ASAL) will establish irrigation...international organizations such as the International Council for Research in Agroforestry (ICRAF) has been beneficial. 13 To preserve Kenya’s forests, the

Intensifying a semi-arid dryland crop rotation by replacing fallow with pea

USDA-ARS?s Scientific Manuscript database

Increasing dryland cropping system intensity in the semi-arid central Great Plains by reducing frequency of fallow can add diversity to cropping systems and decrease erosion potential. However elimination of the periodic fallow phase has been shown to reduce yields of subsequent crops in this region...

The chemistry of salt-affected soils and waters

USDA-ARS?s Scientific Manuscript database

Knowledge of the chemistry of salt affected soils and waters is necessary for management of irrigation in arid and semi-arid regions. In this chapter we review the origin of salts in the landscape, the major chemical reactions necessary for prediction of the soil solution composition, and the use of...

Long term stability of microbial diversity and activity potential in severely disturbed arid lands of the southwest

USDA-ARS?s Scientific Manuscript database

Arid land cryptobiotic soil crusts govern water infiltration, soil aggregate stability and nutrient cycling between soil microbial communities and vascular plants. Surface mining involves removal of topsoil and associated crust and storage in mixed mounds for extended periods. The exposed subsoil an...

Phenotypic variations, heritability and correlations in dry biomass, rubber and resin production among guayule germplasm

USDA-ARS?s Scientific Manuscript database

Gauyaule (Parthenium argentatum Gray) originated in the Southern Texas and northern Mexico deserts, which suggests it as a good candidate for arid and semi-arid sustainable agricultural systems to produce natural rubber and industrial byproducts. Continued improvement of guayule for higher biomass, ...

A TEN-YEAR WATER BALANCE OF A MOUNTAINOUS SEMI-ARID WATERSHED. (R824784)

EPA Science Inventory

Quantifying water balance components, which is particularly challenging in snow-fed, semi-arid regions, is crucial to understanding the basic hydrology of a watershed. In this study, a water balance was computed using 10 years of data collected at the Upper Sheep Creek Water...

Regulation and Impact of Cytoplasmic ARID1A in Ovarian Cancer

DTIC Science & Technology

2016-03-01

verified in a xenograft murine model . Immunohistochemistry studies in OCCC showed that loss of nuclear ARID1A was associated with shorter progression-free...protein 1A; tumor suppressor; ovarian cancer; SWI/SNF – switch/sucrose non- fermentable complex; ovarian clear cell carcinoma; endometrioid ovarian

Information sources [Chapter 12

Treesearch

Daniel G. Neary; John N. Rinne; Alvin L. Medina

2012-01-01

The main information sources for the UVR consist of several web sites with general information and bibliographies. RMRS has publications on its Air, Water, Aquatic Environments (AWAE) Program Flagstaff web site. Another RMRS and University of Arizona website on semi-arid and arid watersheds contains a large, searchable bibliography of supporting information from the...

Impacts of Urbanization on Groundwater Quality and Recharge in a Semi-arid Alluvial Basin

USDA-ARS?s Scientific Manuscript database

The management of groundwater resources is paramount in semi-arid regions experiencing urban development. In the southwestern United States, enhancing recharge of urban storm runoff has been identified as a strategy for augmenting groundwater resources. An understanding of how urbanization may impac...

Gaussian process models for reference ET estimation from alternative meteorological data sources

USDA-ARS?s Scientific Manuscript database

Accurate estimates of daily crop evapotranspiration (ET) are needed for efficient irrigation management, especially in arid and semi-arid regions where crop water demand exceeds rainfall. Daily grass or alfalfa reference ET values and crop coefficients are widely used to estimate crop water demand. ...

Organizing for Education.

ERIC Educational Resources Information Center

Walker, W. Hugh

The arid areas of the world, especially the Middle East and North Africa, need to develop an educational system that is attuned to the needs of the people in order to improve human and institutional competencies required to solve social and economic problems. Since arid areas have special characteristics, it is necessary to find applicable…