Grassland Sustainability

Treesearch

Deborah U. Potter; Paulette L. Ford

2004-01-01

In this chapter we discuss grassland sustainability in the Southwest, grassland management for sustainability, national and local criteria and indicators of sustainable grassland ecosystems, and monitoring for sustainability at various scales. Ecological sustainability is defined as: [T]he maintenance or restoration of the composition, structure, and processes of...

Grassland to shrubland state transitions enhance carbon sequestration in the northern Chihuahuan Desert.

PubMed

Petrie, M D; Collins, S L; Swann, A M; Ford, P L; Litvak, M E

2015-03-01

The replacement of native C4 -dominated grassland by C3 -dominated shrubland is considered an ecological state transition where different ecological communities can exist under similar environmental conditions. These state transitions are occurring globally, and may be exacerbated by climate change. One consequence of the global increase in woody vegetation may be enhanced ecosystem carbon sequestration, although the responses of arid and semiarid ecosystems may be highly variable. During a drier than average period from 2007 to 2011 in the northern Chihuahuan Desert, we found established shrubland to sequester 49 g C m(-2) yr(-1) on average, while nearby native C4 grassland was a net source of 31 g C m(-2) yr(-1) over this same period. Differences in C exchange between these ecosystems were pronounced--grassland had similar productivity compared to shrubland but experienced higher C efflux via ecosystem respiration, while shrubland was a consistent C sink because of a longer growing season and lower ecosystem respiration. At daily timescales, rates of carbon exchange were more sensitive to soil moisture variation in grassland than shrubland, such that grassland had a net uptake of C when wet but lost C when dry. Thus, even under unfavorable, drier than average climate conditions, the state transition from grassland to shrubland resulted in a substantial increase in terrestrial C sequestration. These results illustrate the inherent tradeoffs in quantifying ecosystem services that result from ecological state transitions, such as shrub encroachment. In this case, the deleterious changes to ecosystem services often linked to grassland to shrubland state transitions may at least be partially offset by increased ecosystem carbon sequestration. © 2014 John Wiley & Sons Ltd.

Export of dissolved organic carbon and nitrogen from drained and re-wetted bog sites in Lower Saxony (Germany)

NASA Astrophysics Data System (ADS)

Frank, Stefan; Tiemeyer, Bärbel; Freibauer, Annette

2014-05-01

Today, nearly all peatlands in Germany are drained for agriculture, forestry and peat cutting. The export of dissolved organic carbon (C) and nitrogen (N) may be important for the overall C and N balances and affects downstream ecosystems. While drainage generally increases solute losses, there is nearly no C and N export data of raised bogs in Germany which can be used to evaluate both the impact of drainage associated with intensive land use and the re-wetting of peat cutting sites. In the "Ahlenmoor" (North-Western Germany), four sampling points were chosen. Three sampling points represent a deeply drained intensively used grassland at various scales ranging from a drainage pipe (DP, 0.08 ha) and a drainage ditch (DD, 6.8 ha) to a collector ditch (CD, 20 ha). The fourth sampling point (RW) is a former peat cutting site (23 ha) re-wetted 10 years ago. At this site, polder technique was used to establish water tables at the soil surface. Sampling and discharge measurements were conducted bi-weekly from June 2011 to June 2013. Water table levels were recorded with automatic pressure sensors, and rating curves between discharge and water levels were used to calculate continuous discharge values. Samples were analyzed for dissolved organic carbon (DOC), particulate organic carbon (POC), dissolved organic nitrogen (DON), ammonium (NH4+), nitrate (NO3-), sulphate (SO42-), pH, electric conductivity (EC) and specific UV absorbance (SUVA). The discharge did not vary strongly between the sampling points and was slightly lower in the second year. Concentrations of all measured solutes were higher at the intensive grassland (DP, DD and CD) than at the re-wetted site. Surprisingly, SUVA showed no difference between all sites, while the DOC to DON ratio was narrower at DP, DD and CD than at RW. This indicates an export of more degraded dissolved organic matter (DOM) from the drained area. At the grassland sites, no statistical differences were found between the three scales

Energy exchange of an alpine grassland on the northeastern Qinghai-Tibetan Plateau

NASA Astrophysics Data System (ADS)

Shang, Lunyu; Zhang, Yu; Lv, Shihua; Wang, Shaoying

2014-05-01

The seasonal variability in the surface energy exchange of an alpine grassland on the northeastern Qinghai-Tibetan Plateau was investigated using eddy covariance measurements. Based on the change of air temperature and the seasonal distribution of precipitation, a winter season and wet season were identified, which were separated by transitional periods. For each period, the surface energy exchange exhibited distinct patterns. Daily mean net radiation (Rn) was almost always positive throughout the year. Sensible heat flux (H) was almost always greater than latent heat flux (LE) during the winter season, and LE was always greater than H during the wet season. Ground heat flux (G0) was relatively low throughout the year. The annual mean net radiation was about 39% of the annual mean solar radiation (Rs). Rn was relatively low during the winter season (21% of Rs) compared to the wet season (55% of Rs), which can be explained by the difference in surface albedo and moisture condition between the two seasons. H and LE had different roles during different periods of the year. Annually, the main consumer of net radiation was LE. During the winter season, H was dominant because of the frozen soil condition and lack of precipitation. During the wet season LE was dominant due to increased temperature and sufficient rainfall coupling with vegetation development. LE was strongly controlled by Rn from June to August though surface conductance (gc) and soil water content (θv) were high. During the transitional periods, H and LE were nearly equally partitioned in the energy balance. The results also suggested that the freeze-thaw condition of soil and the seasonal distribution of precipitation had important impacts on the energy exchange in this alpine grassland.

Does interspecific competition alter effects of early season ozone exposure on plants from wet grasslands? Results of a three-year experiment in open-top chambers.

PubMed

Tonneijck, A E G; Franzaring, J; Brouwer, G; Metselaar, K; Dueck, Th A

2004-09-01

Chronic effects of ozone on wet grassland species early in the growing season might be altered by interspecific competition. Individual plants of Holcus lanatus, Lychnis flos-cuculi, Molinia caerulea and Plantago lanceolata were grown in monocultures and in mixed cultures with Agrostis capillaris. Mesocosms were exposed to charcoal-filtered air plus 25 nl l(-1) ozone (CF+25), non-filtered air (NF), non-filtered air plus 25 nl l(-1) ozone (NF+25) and non-filtered air plus 50 nl l(-1) ozone (NF+50) early in the growing seasons of 2000 through 2002. Ozone-enhanced senescence and visible foliar injury were recorded on some of the target plants in the first year only. Ozone effects on biomass production were minimal and plant response to ozone did not differ between monocultures and mixed cultures. After three years, above-ground biomass of the plants in mixed culture compared to monocultures was three times greater for H. lanatus and two to four times smaller for the other species.

Vegetation-climate feedbacks in the conversion of tropical savanna to grassland

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

Hoffmann, W.A.; Jackson, R.B.

2000-05-01

Tropical savannas have been heavily impacted by human activity, with large expanses transformed from a mixture of trees and grasses to open grassland and agriculture. The National Center for Atmospheric Research (NCAR) CCM3 general circulation model, coupled with the NCAR Land Surface Model, was used to simulate the effects of this conversion on regional climate. Conversion of savanna to grassland reduced precipitation by approximately 10% in four of the five savanna regions under study; only the northern African savannas showed no significant decline. Associated with this decline was an increase in the frequency of dry periods within the wet season,more » a change that could be particularly damaging to shallow-rooted crops. The overall decline in precipitation is almost equally attributable to changes in albedo and roughness length. Conversion to grassland increased mean surface air temperature of all the regions by 0.5 C, primarily because of reductions in surface roughness length. Rooting depth, which decreases dramatically with the conversion of savanna to grassland, contributed little to the overall effect of savanna conversion, but deeper rooting had a small positive effect on latent heat flux with a corresponding reduction in sensible heat flux. The authors propose that the interdependence of climate and vegetation in these regions is manifested as a positive feedback loop in which anthropogenic impacts on savanna vegetation are exacerbated by declines in precipitation.« less

Methane fluxes from a wet puna ecosystem in the Peruvian Andes

NASA Astrophysics Data System (ADS)

Jones, Sam; Diem, Torsten; Priscila Huaraca Quispe, Lidia; Quispe Ccahuana, Adan Julian; Meir, Patrick; Arn Teh, Yit

2014-05-01

Discrepancies exist between top-down and bottom-up estimates of the tropical South American atmospheric methane budget. This suggests that current source-sink inventories fail to adequately characterise the landscapes of the region. This may be particularly true of Andean environments where very few field observations have been made. The high tropical Andes, between tree and permanent snow-lines, is home to diverse grass, shrub and giant rosette dominated ecosystems known variously from Venezuela to northern Chile and Argentina as paramo, jalca and puna. In humid regions these are characterised by wet, organic-rich mineral soils, peat-forming wetlands and shallow lakes. Such conditions are likely to promote methane production and potentially represent a regionally significant source to the atmosphere that should be considered. We report on methane fluxes from a bunch-grass dominated puna habitat at 3500 m above sea level in south-eastern Peru. Mean annual temperature and precipitation are 11 °C and 2500 mm, respectively. Temperature is aseasonal but experiences considerable diurnal variations with overnight frosting common-place. In contrast, rainfall is intensely episodic and has a pronounced wet season between September and March. Sampling encompassed a range of topographic features, such as grassland on freely draining, gently inclined or steep slopes and depressions containing bogs, over a 3 ha ridge to basin transition. Monthly sampling was carried out between January 2011 and June 2013 to investigate seasonal variability in methane fluxes. Intensive sampling campaigns were conducted to investigate spatial and short-term variations on a daily basis in two nine-day campaigns during wet and dry season. The site was a net source of methane to the atmosphere during the period of study. Methane fluxes were dominated by emissions from bogs, whereas, freely draining grassland exhibited weak source or marginal sink activity. Temporal variations were most notable at

Asymmetric Responses of Primary Productivity to Altered Precipitation Simulated by Land Surface Models across Three Long-term Grassland Sites

NASA Astrophysics Data System (ADS)

Wu, D.; Ciais, P.; Viovy, N.; Knapp, A.; Wilcox, K.; Bahn, M.; Smith, M. D.; Ito, A.; Arneth, A.; Harper, A. B.; Ukkola, A.; Paschalis, A.; Poulter, B.; Peng, C.; Reick, C. H.; Hayes, D. J.; Ricciuto, D. M.; Reinthaler, D.; Chen, G.; Tian, H.; Helene, G.; Zscheischler, J.; Mao, J.; Ingrisch, J.; Nabel, J.; Pongratz, J.; Boysen, L.; Kautz, M.; Schmitt, M.; Krohn, M.; Zeng, N.; Meir, P.; Zhang, Q.; Zhu, Q.; Hasibeder, R.; Vicca, S.; Sippel, S.; Dangal, S. R. S.; Fatichi, S.; Sitch, S.; Shi, X.; Wang, Y.; Luo, Y.; Liu, Y.; Piao, S.

2017-12-01

Changes in precipitation variability including the occurrence of extreme events strongly influence plant growth in grasslands. Field measurements of aboveground net primary production (ANPP) in temperate grasslands suggest a positive asymmetric response with wet years resulting in ANPP gains larger than ANPP declines in dry years. Whether land surface models used for historical simulations and future projections of the coupled carbon-water system in grasslands are capable to simulate such non-symmetrical ANPP responses remains an important open research question. In this study, we evaluate the simulated responses of grassland primary productivity to altered precipitation with fourteen land surface models at the three sites of Colorado Shortgrass Steppe (SGS), Konza prairie (KNZ) and Stubai Valley meadow (STU) along a rainfall gradient from dry to wet. Our results suggest that: (i) Gross primary production (GPP), NPP, ANPP and belowground NPP (BNPP) show nonlinear response curves (concave-down) in all the models, but with different curvatures and mean values. In contrast across the sites, primary production increases and then saturates along increasing precipitation with a flattening at the wetter site. (ii) Slopes of spatial relationships between modeled primary production and precipitation are steeper than the temporal slopes (obtained from inter-annual variations). (iii) Asymmetric responses under nominal precipitation range with modeled inter-annual primary production show large uncertainties, and model-ensemble median generally suggests negative asymmetry (greater declines in dry years than increases in wet years) across the three sites. (iv) Primary production at the drier site is predicted to more sensitive to precipitation compared to wetter site, and median sensitivity consistently indicates greater negative impacts of reduced precipitation than positive effects of increased precipitation under extreme conditions. This study implies that most models

Introduction to Grassland Management. Instructor Guide, Student Reference [and] Crop and Grassland Plant Identification Manual.

ERIC Educational Resources Information Center

Suits, Susie

This packet contains an Instructor guide and student reference for a course in introduction to grassland management, as well as a crop and grassland plant identification manual. The three-unit curriculum contains the following 11 lessons: (unit I, grasslands and grassland plants): (1) an introduction to grasslands; (2) plant classification; (3)…

The effect of nitrification inhibitors on nitrous oxide emissions from cattle urine depositions to grassland under summer conditions in the UK.

PubMed

Barneze, A S; Minet, E P; Cerri, C C; Misselbrook, T

2015-01-01

Nitrous oxide (N2O) has become the prime ozone depleting atmospheric emission and the third most important anthropogenic greenhouse gas, with a global warming potential approximately 300 times higher than CO2. Nitrification and denitrification are processes responsible for N2O emission from the soil after nitrogen input. The application of a nitrification inhibitor can reduce N2O emissions from these processes. The objective of this study was to assess the effect of two different nitrification inhibitors (dicyandiamide (DCD) and a commercial formulation containing two pyrazole derivatives (PD), 1H-1,2,4-triazole and 3-methylpyrazole) on N2O emissions from cattle urine applications for summer grazing conditions in the UK. Experiments were conducted under controlled conditions in a laboratory incubator and under field conditions on a grassland soil. The N2O emissions showed similar temporal dynamics in both experiments. DCD concentration in the soil showed an exponential degradation during the experiment, with a half-life of the order of only 10d (air temperature c. 15 °C). DCD (10 kg ha(-1)) and PD at the highest application rate (3.76 kg ha(-1)) reduced N2O emissions by 13% and 29% in the incubation experiment and by 33% and 6% in the field experiment, respectively, although these reductions were not statistically significant (P>0.05). Under UK summer grazing conditions, these nitrification inhibitors appear to be less effective at reducing N2O emissions than reported for other conditions elsewhere in the literature, presumably due to the higher soil temperature. Copyright © 2014 Elsevier Ltd. All rights reserved.

Carbon balance of a grazed savanna grassland ecosystem in South Africa

NASA Astrophysics Data System (ADS)

Räsänen, Matti; Aurela, Mika; Vakkari, Ville; Beukes, Johan P.; Tuovinen, Juha-Pekka; Van Zyl, Pieter G.; Josipovic, Miroslav; Venter, Andrew D.; Jaars, Kerneels; Siebert, Stefan J.; Laurila, Tuomas; Rinne, Janne; Laakso, Lauri

2017-03-01

Tropical savannas and grasslands are estimated to contribute significantly to the total primary production of all terrestrial vegetation. Large parts of African savannas and grasslands are used for agriculture and cattle grazing, but the carbon flux data available from these areas are limited. This study explores carbon dioxide fluxes measured with the eddy covariance method for 3 years at a grazed savanna grassland in Welgegund, South Africa. The tree cover around the measurement site, grazed by cattle and sheep, was around 15 %. The night-time respiration was not significantly dependent on either soil moisture or soil temperature on a weekly temporal scale, whereas on an annual timescale higher respiration rates were observed when soil temperatures were higher. The carbon dioxide balances of the years 2010-2011, 2011-2012 and 2012-2013 were -85 ± 16, 67 ± 20 and 139 ± 13 gC m-2 yr-1, respectively. The yearly variation was largely determined by the changes in the early wet season fluxes (September to November) and in the mid-growing season fluxes (December to January). Early rainfall enhanced the respiratory capacity of the ecosystem throughout the year, whereas during the mid-growing season high rainfall resulted in high carbon uptake.

Water relations in grassland and desert ecosystems exposed to elevated atmospheric CO2.

PubMed

Morgan, J A; Pataki, D E; Körner, C; Clark, H; Del Grosso, S J; Grünzweig, J M; Knapp, A K; Mosier, A R; Newton, P C D; Niklaus, P A; Nippert, J B; Nowak, R S; Parton, W J; Polley, H W; Shaw, M R

2004-06-01

Atmospheric CO2 enrichment may stimulate plant growth directly through (1) enhanced photosynthesis or indirectly, through (2) reduced plant water consumption and hence slower soil moisture depletion, or the combination of both. Herein we describe gas exchange, plant biomass and species responses of five native or semi-native temperate and Mediterranean grasslands and three semi-arid systems to CO2 enrichment, with an emphasis on water relations. Increasing CO2 led to decreased leaf conductance for water vapor, improved plant water status, altered seasonal evapotranspiration dynamics, and in most cases, periodic increases in soil water content. The extent, timing and duration of these responses varied among ecosystems, species and years. Across the grasslands of the Kansas tallgrass prairie, Colorado shortgrass steppe and Swiss calcareous grassland, increases in aboveground biomass from CO2 enrichment were relatively greater in dry years. In contrast, CO2-induced aboveground biomass increases in the Texas C3/C4 grassland and the New Zealand pasture seemed little or only marginally influenced by yearly variation in soil water, while plant growth in the Mojave Desert was stimulated by CO2 in a relatively wet year. Mediterranean grasslands sometimes failed to respond to CO2-related increased late-season water, whereas semiarid Negev grassland assemblages profited. Vegetative and reproductive responses to CO2 were highly varied among species and ecosystems, and did not generally follow any predictable pattern in regard to functional groups. Results suggest that the indirect effects of CO2 on plant and soil water relations may contribute substantially to experimentally induced CO2-effects, and also reflect local humidity conditions. For landscape scale predictions, this analysis calls for a clear distinction between biomass responses due to direct CO2 effects on photosynthesis and those indirect CO2 effects via soil moisture as documented here.

Response of alpine grassland to elevated nitrogen deposition and water supply in China.

PubMed

Li, Kaihui; Liu, Xuejun; Song, Ling; Gong, Yanming; Lu, Chunfang; Yue, Ping; Tian, Changyan; Zhang, Fusuo

2015-01-01

Species composition and productivity are influenced by water and N availability in semi-arid grasslands. To assess the effects of increased N deposition and water supply on plant species composition and productivity, two field experiments with four N addition treatments, and three N and water combination treatments were conducted in alpine grassland in the mid Tianshan mountains, northwest China. When considering N addition alone, aboveground biomass (AGB) of forbs (F(AGB)) responded less to N addition than AGB of grasses (G(AGB)). G(AGB) increased as an effect of N combined with water addition but F(AGB) did not show such an effect, reflecting a stronger response of grasses to the interaction of water availability and N than forbs. Under all treatments, N allocation to the aboveground tissue did not change for either forbs or grasses. N deposition and water addition did not alter species richness in the present study. These results suggest that N addition generally promoted AGB but had little effect on species richness in wet years. Snowfall in winter combined with rainfall in the early growing season likely plays a critical role in regulating plant growth of the subsequent year in the alpine grassland.

Songbird abundance in native and planted grassland varies with type and amount of grassland in the surrounding landscape

USGS Publications Warehouse

Davis, Stephen K.; Fisher, Ryan; Skinner, Susan; Shaffer, Terry L.; Brigham, R. Mark

2013-01-01

Agriculture and wildlife conservation programs have converted vast amounts of cropland into grasslands planted with exotic species. Understanding how landscape context influences avian use of native and planted grasslands is essential for developing effective conservation strategies in agricultural landscapes. Our primary objective was to determine the extent to which the amount and type of grassland in the surrounding landscape influences the abundance of grassland songbird species on native and planted grassland parcels in southern Saskatchewan and Alberta, Canada. Bird abundance was more strongly influenced by the amount and type of grassland within 400 m of breeding parcels than at larger spatial scales. Grassland specialists responded similarly to habitat and landscape type over both years and provinces. Sprague's pipit (Anthus spragueii) and Baird's sparrow (Ammodramus bairdii) were most common in native grassland parcels surrounded by native grassland and were more likely to occur in planted grasslands surrounded by native grassland. Bobolinks (Dolichonyx oryzivorus) were most common in planted grassland parcels, but their abundance increased with the amount of native grassland surrounding these parcels. Our findings indicate that the suitability of planted grasslands for these species is influenced by their proximity to native grassland. Grassland generalists showed mixed responses to habitat and landscape type over the 2 years (Le Conte's sparrow [Ammodramus leconteii]) and between provinces (Savannah sparrow [Passerculus sandwichensis] and western meadowlark [Sturnella neglecta]). Management to benefit grassland specialists should therefore consider the landscape context when seeding cultivated land to non-native grassland and conserve extant native grassland.

Grassland Management and Conversion into Grassland: Effects on Soil Carbon

DOE Data Explorer

Conant, Richard T. [Natural Resource Ecology Laboratory, Colorada State University, Fort Collins, CO (USA); Paustian, Keith [Natural Resource Ecology Laboratory, Colorada State University, Fort Collins, CO (USA); Elliott, Edward T. [Natural Resource Ecology Laboratory, Colorada State University, Fort Collins, CO (USA)

2003-01-01

Grasslands are heavily relied upon for food and forage production. A key component for sustaining production in grassland ecosystems is the maintenance of soil organic matter (SOM), which can be strongly influenced by management. Many management techniques intended to increase forage production may potentially increase SOM, thus sequestering atmospheric carbon (C). Further, conversion from either cultivation or native vegetation into grassland could also sequester atmospheric carbon. We reviewed studies examining the influence of improved grassland management practices and conversion into grasslands on soil C worldwide to assess the potential for C sequestration. Results from 115 studies containing over 300 data points were analyzed. Management improvements included fertilization (39%), improved grazing management (24%), conversion from cultivation (15%) and native vegetation (15%), sowing of legumes (4%) and grasses (2%), earthworm introduction (1%), and irrigation (1%). Soil C content and concentration increased with improved management in 74% of the studies, and mean soil C increased with all types of improvement. Carbon sequestration rates were highest during the first 40 y after treatments began and tended to be greatest in the top 10 cm of soil. Impacts were greater in woodland and grassland biomes than in forest, desert, rain forest, or shrubland biomes. Conversion from cultivation, the introduction of earthworms, and irrigation resulted in the largest increases. Rates of C sequestration by type of improvement ranged from 0.11 to 3.04 Mg C · ha^–1 y^–1, with a mean of 0.54 Mg C · ha ^–1 · y^–1, and were highly influenced by biome type and climate. We conclude that grasslands can act as a significant carbon sink with the implementation of improved management.

Action versus Result-Oriented Schemes in a Grassland Agroecosystem: A Dynamic Modelling Approach

PubMed Central

Sabatier, Rodolphe; Doyen, Luc; Tichit, Muriel

2012-01-01

Effects of agri-environment schemes (AES) on biodiversity remain controversial. While most AES are action-oriented, result-oriented and habitat-oriented schemes have recently been proposed as a solution to improve AES efficiency. The objective of this study was to compare action-oriented, habitat-oriented and result-oriented schemes in terms of ecological and productive performance as well as in terms of management flexibility. We developed a dynamic modelling approach based on the viable control framework to carry out a long term assessment of the three schemes in a grassland agroecosystem. The model explicitly links grazed grassland dynamics to bird population dynamics. It is applied to lapwing conservation in wet grasslands in France. We ran the model to assess the three AES scenarios. The model revealed the grazing strategies respecting ecological and productive constraints specific to each scheme. Grazing strategies were assessed by both their ecological and productive performance. The viable control approach made it possible to obtain the whole set of viable grazing strategies and therefore to quantify the management flexibility of the grassland agroecosystem. Our results showed that habitat and result-oriented scenarios led to much higher ecological performance than the action-oriented one. Differences in both ecological and productive performance between the habitat and result-oriented scenarios were limited. Flexibility of the grassland agroecosystem in the result-oriented scenario was much higher than in that of habitat-oriented scenario. Our model confirms the higher flexibility as well as the better ecological and productive performance of result-oriented schemes. A larger use of result-oriented schemes in conservation may also allow farmers to adapt their management to local conditions and to climatic variations. PMID:22496746

Soil moisture and fungi affect seed survival in California grassland annual plants.

PubMed

Mordecai, Erin A

2012-01-01

Survival of seeds in the seed bank is important for the population dynamics of many plant species, yet the environmental factors that control seed survival at a landscape level remain poorly understood. These factors may include soil moisture, vegetation cover, soil type, and soil pathogens. Because many soil fungi respond to moisture and host species, fungi may mediate environmental drivers of seed survival. Here, I measure patterns of seed survival in California annual grassland plants across 15 species in three experiments. First, I surveyed seed survival for eight species at 18 grasslands and coastal sage scrub sites ranging across coastal and inland Santa Barbara County, California. Species differed in seed survival, and soil moisture and geographic location had the strongest influence on survival. Grasslands had higher survival than coastal sage scrub sites for some species. Second, I used a fungicide addition and exotic grass thatch removal experiment in the field to tease apart the relative impact of fungi, thatch, and their interaction in an invaded grassland. Seed survival was lower in the winter (wet season) than in the summer (dry season), but fungicide improved winter survival. Seed survival varied between species but did not depend on thatch. Third, I manipulated water and fungicide in the laboratory to directly examine the relationship between water, fungi, and survival. Seed survival declined from dry to single watered to continuously watered treatments. Fungicide slightly improved seed survival when seeds were watered once but not continually. Together, these experiments demonstrate an important role of soil moisture, potentially mediated by fungal pathogens, in driving seed survival.

Use of the Cropland Data Layer to monitor grassland conversion in the U.S. Western Corn Belt (Invited)

NASA Astrophysics Data System (ADS)

Wright, C.; Wimberly, M. C.

2013-12-01

The U.S. Department of Agriculture's Cropland Data Layer (CDL) provides new opportunities for monitoring land cover/land use change (LCLUC) related to U.S. agricultural policy, bioenergy development, and recent commodity price increases. We used the CDL to assess the conversion of grasslands to corn/soy cultivation along the western periphery of the U.S. Corn Belt. Here, we find rapid grassland conversion (1-5% annually) as the Corn Belt expands westward and northward into North Dakota and South Dakota. This LCLUC is occurring in close proximity to wetlands in the Prairie Pothole Region. In most counties in the eastern Dakotas, grassland conversion exceeds declines in land area enrolled in the Conservation Reserve Program (CRP). Within the core corn/soy growing area in Iowa and southern Minnesota, LCLUC is occurring on marginal lands characterized by high erosion potential and less-productive soils. In Minnesota, particularly, corn/soy production is increasing on lands previously too wet to farm without an expansion of agricultural drainage practices. Over the period 2006-2011, we estimate a net greenhouse gas impact of grassland conversion in the Western Corn Belt of approximately 4*106 metric tons CO2-equivalent. Although not designed for monitoring grasslands, we suggest that the CDL can be used judiciously to identify grassland conversion at farm- to sub-county scales, and, in conjunction with other national-level datasets (e.g., the National Wetlands Inventory and SSURGO database), to provide timely feedback to policymakers and the public on likely environmental impacts of U.S. agricultural policies and shifting market forces.

Southwestern Grassland Ecology

Treesearch

Paulette L. Ford; Deborah U. Potter; Rosemary Pendleton; Burton Pendleton; Wayne A. Robbie; Gerald J. Gottfried

2004-01-01

This chapter provides a brief overview, and selected in-depth coverage, of the factors and processes that have formed, and continue to shape, our Southwestern grasslands. In general, this chapter looks at how distributions of grasslands are regulated by soils and climate, and modified by disturbance (natural and/or anthropogenic). The attendant ecological components of...

Seasonal exports of phosphorus from intensively fertilised nested grassland catchments.

PubMed

Lewis, Ciaran; Rafique, Rashad; Foley, Nelius; Leahy, Paul; Morgan, Gerard; Albertson, John; Kumar, Sandeep; Kiely, Gerard

2013-09-01

We carried out a one year (2002) study of phosphorus (P) loss from soil to water in three nested grassland catchments with known P input in chemical fertilizer and animal liquid slurry applications. Chemical fertilizer was applied to the grasslands between March and September and animal slurry was applied over the twelve months. The annual chemical P fertilizer applications for the 17 and 211 ha catchments were 16.4 and 23.7 kg P/ha respectively and the annual slurry applications were 10.7 and 14.0 kg P/ha, respectively. The annual total phosphorus (TP) export in stream-flow was 2.61, 2.48 and 1.61 kg P/ha for the 17, 211 and 1524 ha catchments, respectively, compared with a maximum permissible (by regulation) annual export of ca. 0.35 kg P/ha. The export rate (ratio of P export to P in land applications) was 9.6% and 6.6% from the 17 and 211 ha catchments, respectively. On average, 70% of stream flow and 85% of the P export occurred during the five wet months (October to February) indicating that when precipitation is much greater than evaporation, the hydrological conditions are most favourable for P export. However the soil quality and land use history may vary the results. Particulate P made up 22%, 43% and 37% of the TP export at the 17, 211 and 1524 ha catchment areas, respectively. As the chemical fertilizer was spread during the grass growth months (March to September), it has less immediate impact on stream water quality than the slurry applications. We also show that as the catchment scale increases, the P concentrations and P export decrease, confirming dilution due to increasing rural catchment size. In the longer term, the excess P from fertilizer maintains high soil P levels, an antecedent condition favourable to P loss from soil to water. This study confirms the significant negative water quality impact of excess P applications, particularly liquid animal slurry applications in wet winter months. The findings suggest that restricted P application in

The potential of small-Unmanned Aircraft Systems for the rapid detection of threatened unimproved grassland communities using an Enhanced Normalized Difference Vegetation Index.

PubMed

Strong, Conor J; Burnside, Niall G; Llewellyn, Dan

2017-01-01

The loss of unimproved grassland has led to species decline in a wide range of taxonomic groups. Agricultural intensification has resulted in fragmented patches of remnant grassland habitat both across Europe and internationally. The monitoring of remnant patches of this habitat is critically important, however, traditional surveying of large, remote landscapes is a notoriously costly and difficult task. The emergence of small-Unmanned Aircraft Systems (sUAS) equipped with low-cost multi-spectral cameras offer an alternative to traditional grassland survey methods, and have the potential to progress and innovate the monitoring and future conservation of this habitat globally. The aim of this article is to investigate the potential of sUAS for rapid detection of threatened unimproved grassland and to test the use of an Enhanced Normalized Difference Vegetation Index (ENDVI). A sUAS aerial survey is undertaken at a site nationally recognised as an important location for fragmented unimproved mesotrophic grassland, within the south east of England, UK. A multispectral camera is used to capture imagery in the visible and near-infrared spectrums, and the ENDVI calculated and its discrimination performance compared to a range of more traditional vegetation indices. In order to validate the results of analysis, ground quadrat surveys were carried out to determine the grassland communities present. Quadrat surveys identified three community types within the site; unimproved grassland, improved grassland and rush pasture. All six vegetation indices tested were able to distinguish between the broad habitat types of grassland and rush pasture; whilst only three could differentiate vegetation at a community level. The Enhanced Normalized Difference Vegetation Index (ENDVI) was the most effective index when differentiating grasslands at the community level. The mechanisms behind the improved performance of the ENDVI are discussed and recommendations are made for areas of future

The potential of small-Unmanned Aircraft Systems for the rapid detection of threatened unimproved grassland communities using an Enhanced Normalized Difference Vegetation Index

PubMed Central

Strong, Conor J.; Llewellyn, Dan

2017-01-01

The loss of unimproved grassland has led to species decline in a wide range of taxonomic groups. Agricultural intensification has resulted in fragmented patches of remnant grassland habitat both across Europe and internationally. The monitoring of remnant patches of this habitat is critically important, however, traditional surveying of large, remote landscapes is a notoriously costly and difficult task. The emergence of small-Unmanned Aircraft Systems (sUAS) equipped with low-cost multi-spectral cameras offer an alternative to traditional grassland survey methods, and have the potential to progress and innovate the monitoring and future conservation of this habitat globally. The aim of this article is to investigate the potential of sUAS for rapid detection of threatened unimproved grassland and to test the use of an Enhanced Normalized Difference Vegetation Index (ENDVI). A sUAS aerial survey is undertaken at a site nationally recognised as an important location for fragmented unimproved mesotrophic grassland, within the south east of England, UK. A multispectral camera is used to capture imagery in the visible and near-infrared spectrums, and the ENDVI calculated and its discrimination performance compared to a range of more traditional vegetation indices. In order to validate the results of analysis, ground quadrat surveys were carried out to determine the grassland communities present. Quadrat surveys identified three community types within the site; unimproved grassland, improved grassland and rush pasture. All six vegetation indices tested were able to distinguish between the broad habitat types of grassland and rush pasture; whilst only three could differentiate vegetation at a community level. The Enhanced Normalized Difference Vegetation Index (ENDVI) was the most effective index when differentiating grasslands at the community level. The mechanisms behind the improved performance of the ENDVI are discussed and recommendations are made for areas of future

Satellite-based assessment of grassland yields

NASA Astrophysics Data System (ADS)

Grant, K.; Siegmund, R.; Wagner, M.; Hartmann, S.

2015-04-01

Cutting date and frequency are important parameters determining grassland yields in addition to the effects of weather, soil conditions, plant composition and fertilisation. Because accurate and area-wide data of grassland yields are currently not available, cutting frequency can be used to estimate yields. In this project, a method to detect cutting dates via surface changes in radar images is developed. The combination of this method with a grassland yield model will result in more reliable and regional-wide numbers of grassland yields. For the test-phase of the monitoring project, a study area situated southeast of Munich, Germany, was chosen due to its high density of managed grassland. For determining grassland cutting robust amplitude change detection techniques are used evaluating radar amplitude or backscatter statistics before and after the cutting event. CosmoSkyMed and Sentinel-1A data were analysed. All detected cuts were verified according to in-situ measurements recorded in a GIS database. Although the SAR systems had various acquisition geometries, the amount of detected grassland cut was quite similar. Of 154 tested grassland plots, covering in total 436 ha, 116 and 111 cuts were detected using CosmoSkyMed and Sentinel-1A radar data, respectively. Further improvement of radar data processes as well as additional analyses with higher sample number and wider land surface coverage will follow for optimisation of the method and for validation and generalisation of the results of this feasibility study. The automation of this method will than allow for an area-wide and cost efficient cutting date detection service improving grassland yield models.

36 CFR 222.52 - National Grasslands.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 2 2010-07-01 2010-07-01 false National Grasslands. 222.52 Section 222.52 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE RANGE MANAGEMENT Grazing Fees § 222.52 National Grasslands. Grazing fees for National Grasslands will be...

36 CFR 222.52 - National Grasslands.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 2 2012-07-01 2012-07-01 false National Grasslands. 222.52 Section 222.52 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE RANGE MANAGEMENT Grazing Fees § 222.52 National Grasslands. Grazing fees for National Grasslands will be...

Impact of two centuries of intensive agriculture on soil carbon, nitrogen and phosphorus cycling in the UK.

PubMed

Muhammed, Shibu E; Coleman, Kevin; Wu, Lianhai; Bell, Victoria A; Davies, Jessica A C; Quinton, John N; Carnell, Edward J; Tomlinson, Samuel J; Dore, Anthony J; Dragosits, Ulrike; Naden, Pamela S; Glendining, Margaret J; Tipping, Edward; Whitmore, Andrew P

2018-09-01

This paper describes an agricultural model (Roth-CNP) that estimates carbon (C), nitrogen (N) and phosphorus (P) pools, pool changes, their balance and the nutrient fluxes exported from arable and grassland systems in the UK during 1800-2010. The Roth-CNP model was developed as part of an Integrated Model (IM) to simulate C, N and P cycling for the whole of UK, by loosely coupling terrestrial, hydrological and hydro-chemical models. The model was calibrated and tested using long term experiment (LTE) data from Broadbalk (1843) and Park Grass (1856) at Rothamsted. We estimated C, N and P balance and their fluxes exported from arable and grassland systems on a 5km×5km grid across the whole of UK by using the area of arable of crops and livestock numbers in each grid and their management. The model estimated crop and grass yields, soil organic carbon (SOC) stocks and nutrient fluxes in the form of NH 4 -N, NO 3 -N and PO 4 -P. The simulated crop yields were compared to that reported by national agricultural statistics for the historical to the current period. Overall, arable land in the UK have lost SOC by -0.18, -0.25 and -0.08MgCha -1 y -1 whereas land under improved grassland SOC stock has increased by 0.20, 0.47 and 0.24MgCha -1 y -1 during 1800-1950, 1950-1970 and 1970-2010 simulated in this study. Simulated N loss (by leaching, runoff, soil erosion and denitrification) increased both under arable (-15, -18 and -53kgNha -1 y -1 ) and grass (-18, -22 and -36kgNha -1 y -1 ) during different time periods. Simulated P surplus increased from 2.6, 10.8 and 18.1kgPha -1 y -1 under arable and 2.8, 11.3 and 3.6kgPha -1 y -1 under grass lands 1800-1950, 1950-1970 and 1970-2010. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Changing precipitation pattern alters soil microbial community response to wet-up under a Mediterranean-type climate.

PubMed

Barnard, Romain L; Osborne, Catherine A; Firestone, Mary K

2015-03-17

A large soil CO2 pulse is associated with rewetting soils after the dry summer period under a Mediterranean-type climate, significantly contributing to grasslands' annual carbon budget. Rapid reactivation of soil heterotrophs and a pulse of available carbon are both required to fuel the CO2 pulse. Understanding of the effects of altered summer precipitation on the metabolic state of indigenous microorganisms may be important in predicting changes in carbon cycling. Here, we investigated the effects of extending winter rainfall into the normally dry summer period on soil microbial response to a controlled rewetting event, by following the present (DNA-based) and potentially active (rRNA-based) soil bacterial and fungal communities in intact soil cores (from a California annual grassland) previously subjected to three different precipitation patterns over 4 months (full summer dry season, extended wet season and absent dry season). Phylogenetic marker genes for bacteria and fungi were sequenced before and after rewetting, and the abundance of these genes and transcripts was measured. After having experienced markedly different antecedent water conditions, the potentially active bacterial communities showed a consistent wet-up response. We found a significant positive relation between the extent of change in the structure of the potentially active bacterial community and the magnitude of the CO2 pulse upon rewetting dry soils. We suggest that the duration of severe dry summer conditions characteristic of the Mediterranean climate is important in conditioning the response potential of the soil microbial community to wet-up as well as in framing the magnitude of the associated CO2 pulse.

[Spatiotemporal characteristics of MODIS NDVI in Hulunber Grassland].

PubMed

Zhang, Hong-Bin; Yang, Gui-Xia; Wu, Wen-Bin; Li, Gang; Chen, Bao-Rui; Xin, Xiao-Ping

2009-11-01

Time-series MODIS NDVI datasets from 2000 to 2008 were used to study the spatial change trend, fluctuation degree, and occurrence time of the annual NDVImax of four typical grassland types, i.e., lowland meadow, temperate steppe, temperate meadow steppe, and upland meadow, in Hulunber Grassland. In 2000-2008, the vegetation in Hulunber Grassland presented an obvious deterioration trend. The mean annual NDVImax of the four grassland types had a great fluctuation, especially in temperate steppe where the maximum change in the mean value of annual NDVImax approximated to 50%. As for the area change of different grade grasslands, the areas with NDVImax between 0.4 and 1 accounted for about 91% of the total grassland area, which suggested the good vegetation coverage in the Grassland. However, though the areas with NDVImax values in (0.4, 0.8) showed an increasing trend, the areas with NDVImax values in (0.2, 0.4) and (0.8, 1) decreased greatly in the study period. Overall, the deteriorating grassland took up about 66.25% of the total area, and the restoring grassland took the rest. There was about 62.85% of the grassland whose NDVImax occurred between the 193rd day and the 225th day in each year, indicating that this period was the most important vegetation growth season in Hulunber Grassland.

Bird Communities and Biomass Yields in Potential Bioenergy Grasslands

PubMed Central

Blank, Peter J.; Sample, David W.; Williams, Carol L.; Turner, Monica G.

2014-01-01

Demand for bioenergy is increasing, but the ecological consequences of bioenergy crop production on working lands remain unresolved. Corn is currently a dominant bioenergy crop, but perennial grasslands could produce renewable bioenergy resources and enhance biodiversity. Grassland bird populations have declined in recent decades and may particularly benefit from perennial grasslands grown for bioenergy. We asked how breeding bird community assemblages, vegetation characteristics, and biomass yields varied among three types of potential bioenergy grassland fields (grass monocultures, grass-dominated fields, and forb-dominated fields), and assessed tradeoffs between grassland biomass production and bird habitat. We also compared the bird communities in grassland fields to nearby cornfields. Cornfields had few birds compared to perennial grassland fields. Ten bird Species of Greatest Conservation Need (SGCN) were observed in perennial grassland fields. Bird species richness and total bird density increased with forb cover and were greater in forb-dominated fields than grass monocultures. SGCN density declined with increasing vertical vegetation density, indicating that tall, dense grassland fields managed for maximum biomass yield would be of lesser value to imperiled grassland bird species. The proportion of grassland habitat within 1 km of study sites was positively associated with bird species richness and the density of total birds and SGCNs, suggesting that grassland bioenergy fields may be more beneficial for grassland birds if they are established near other grassland parcels. Predicted total bird density peaked below maximum biomass yields and predicted SGCN density was negatively related to biomass yields. Our results indicate that perennial grassland fields could produce bioenergy feedstocks while providing bird habitat. Bioenergy grasslands promote agricultural multifunctionality and conservation of biodiversity in working landscapes. PMID:25299593

The cost-effectiveness of sacral nerve stimulation (SNS) for the treatment of idiopathic medically refractory overactive bladder (wet) in the UK.

PubMed

Autiero, Silke Walleser; Hallas, Natalie; Betts, Christopher D; Ockrim, Jeremy L

2015-12-01

To estimate the long-term cost-effectiveness of specialised treatment options for medically refractory idiopathic overactive bladder (OAB) wet. The cost-effectiveness of competing treatment options for patients with medically refractory idiopathic OAB wet was estimated from the perspective of the National Health Service in the UK. We compared sacral nerve stimulation (SNS) with percutaneous nerve evaluation (PNE) or tined-lead evaluation (TLE) with optimal medical therapy (OMT), botulinum toxin type A (BoNT-A) injections, and percutaneous tibial nerve stimulation (PTNS). We used a Markov model with a 10-year time horizon for all treatment options with the exception of PTNS, which has a time horizon of 5 years. Costs and effects (measured as quality-adjusted life years) were calculated to derive incremental cost-effectiveness ratios (ICERs). Direct medical resources included are: device and drug acquisition costs, pre-procedure and procedure costs, and the cost of managing adverse events. Deterministic sensitivity analyses were performed to test robustness of results. At 5 years, SNS (PNE or TLE) was more effective and less costly than PTNS. Compared with OMT at 10 years, SNS (PNE or TLE) was more costly and more effective, and compared with BoNT-A, SNS PNE was less costly and more effective, and SNS TLE was more costly and more effective. Decreasing the BoNT-A dose from 150 to 100 IU marginally increased the 10 year ICERs for SNS TLE and PNE (SNS PNE was no longer dominant). However, both SNS options remained cost-effective. In the management of patients with idiopathic OAB wet, the results of this cost-utility analysis favours SNS (PNE or TLE) over PTNS or OMT, and the most efficient treatment strategy is SNS PNE over BoNT-A over a 10-year period. © 2015 The Authors BJU International © 2015 BJU International Published by John Wiley & Sons Ltd.

Seasonality of Fire Weather Strongly Influences Fire Regimes in South Florida Savanna-Grassland Landscapes

PubMed Central

Platt, William J.; Orzell, Steve L.; Slocum, Matthew G.

2015-01-01

Fire seasonality, an important characteristic of fire regimes, commonly is delineated using seasons based on single weather variables (rainfall or temperature). We used nonparametric cluster analyses of a 17-year (1993–2009) data set of weather variables that influence likelihoods and spread of fires (relative humidity, air temperature, solar radiation, wind speed, soil moisture) to explore seasonality of fire in pine savanna-grassland landscapes at the Avon Park Air Force Range in southern Florida. A four-variable, three-season model explained more variation within fire weather variables than models with more seasons. The three-season model also delineated intra-annual timing of fire more accurately than a conventional rainfall-based two-season model. Two seasons coincided roughly with dry and wet seasons based on rainfall. The third season, which we labeled the fire season, occurred between dry and wet seasons and was characterized by fire-promoting conditions present annually: drought, intense solar radiation, low humidity, and warm air temperatures. Fine fuels consisting of variable combinations of pyrogenic pine needles, abundant C4 grasses, and flammable shrubs, coupled with low soil moisture, and lightning ignitions early in the fire season facilitate natural landscape-scale wildfires that burn uplands and across wetlands. We related our three season model to fires with different ignition sources (lightning, military missions, and prescribed fires) over a 13-year period with fire records (1997–2009). Largest wildfires originate from lightning and military ignitions that occur within the early fire season substantially prior to the peak of lightning strikes in the wet season. Prescribed ignitions, in contrast, largely occur outside the fire season. Our delineation of a pronounced fire season provides insight into the extent to which different human-derived fire regimes mimic lightning fire regimes. Delineation of a fire season associated with timing of

Seasonality of fire weather strongly influences fire regimes in South Florida savanna-grassland landscapes.

PubMed

Platt, William J; Orzell, Steve L; Slocum, Matthew G

2015-01-01

Fire seasonality, an important characteristic of fire regimes, commonly is delineated using seasons based on single weather variables (rainfall or temperature). We used nonparametric cluster analyses of a 17-year (1993-2009) data set of weather variables that influence likelihoods and spread of fires (relative humidity, air temperature, solar radiation, wind speed, soil moisture) to explore seasonality of fire in pine savanna-grassland landscapes at the Avon Park Air Force Range in southern Florida. A four-variable, three-season model explained more variation within fire weather variables than models with more seasons. The three-season model also delineated intra-annual timing of fire more accurately than a conventional rainfall-based two-season model. Two seasons coincided roughly with dry and wet seasons based on rainfall. The third season, which we labeled the fire season, occurred between dry and wet seasons and was characterized by fire-promoting conditions present annually: drought, intense solar radiation, low humidity, and warm air temperatures. Fine fuels consisting of variable combinations of pyrogenic pine needles, abundant C4 grasses, and flammable shrubs, coupled with low soil moisture, and lightning ignitions early in the fire season facilitate natural landscape-scale wildfires that burn uplands and across wetlands. We related our three season model to fires with different ignition sources (lightning, military missions, and prescribed fires) over a 13-year period with fire records (1997-2009). Largest wildfires originate from lightning and military ignitions that occur within the early fire season substantially prior to the peak of lightning strikes in the wet season. Prescribed ignitions, in contrast, largely occur outside the fire season. Our delineation of a pronounced fire season provides insight into the extent to which different human-derived fire regimes mimic lightning fire regimes. Delineation of a fire season associated with timing of

Factors influencing soil invertebrate communities in riparian grasslands of the central platte river floodplain

USGS Publications Warehouse

Davis, C.A.; Austin, J.E.; Buhl, D.A.

2006-01-01

In the Platte River Valley of central Nebraska, USA, riparian grasslands (also known as wet meadows) have been severely impacted by a reduction in river flows, causing lower ground-water levels and altered seasonal hydroperiods. The potential impacts of these hydrologic changes, as well as the environmental factors that influence wet meadow soil invertebrate communities, are not well understood. An understanding of the ecological processes that influence these invertebrate communities is crucial for maintaining and restoring wet meadows along the Platte River. Our objectives were to describe the soil invertebrate community of wet meadows throughout the growing season and to examine the relative roles of abiotic factors in determining patterns in invertebrate community structure. We conducted the study in 12 wet meadows along the Platte River during 1999 and 2000. We identified 73 invertebrate taxa; 39 were considered soil inhabitants. Total biomass was primarily composed of earthworms, Scarabaeidae, Isopoda, and Elateridae, with earthworms and Scarabaeidae accounting for >82%. Differences in river flow and precipitation patterns influenced some soil invertebrates. Earthworms and Scarabaeidae declined dramatically from 1999 (wet year) to 2000 (dry year). The topographic gradient created by the ridge-swale complex affected several soil invertebrate taxa; Scarabaeidae, Diplopoda, and Lepidoptera biomasses were greatest on drier ridges, while Tipulidae and Isopoda biomasscs were greatest in wetter sloughs. Responses of earthworm taxa to the topographic gradient were variable, but generally, greater biomasses occurred on ridges and mid-elevations. Water-table depth and soil moisture were the most important variables influencing wet meadow soil invertebrates. Because these communities are linked to the hydrologic processes of the Platte River, future alterations of wet meadow hydrology could shift the distribution patterns of many of these invertebrates and possibly

Analysis of Grassland Ecosystem Physiology at Multiple Scales Using Eddy Covariance, Stable Isotope and Remote Sensing Techniques

NASA Astrophysics Data System (ADS)

Flanagan, L. B.; Geske, N.; Emrick, C.; Johnson, B. G.

2006-12-01

Grassland ecosystems typically exhibit very large annual fluctuations in above-ground biomass production and net ecosystem productivity (NEP). Eddy covariance flux measurements, plant stable isotope analyses, and canopy spectral reflectance techniques have been applied to study environmental constraints on grassland ecosystem productivity and the acclimation responses of the ecosystem at a site near Lethbridge, Alberta, Canada. We have observed substantial interannual variation in grassland productivity during 1999-2005. In addition, there was a strong correlation between peak above-ground biomass production and NEP calculated from eddy covariance measurements. Interannual variation in NEP was strongly controlled by the total amount of precipitation received during the growing season (April-August). We also observed significant positive correlations between a multivariate ENSO index and total growing season precipitation, and between the ENSO index and annual NEP values. This suggested that a significant fraction of the annual variability in grassland productivity was associated with ENSO during 1999-2005. Grassland productivity varies asymmetrically in response to changes in precipitation with increases in productivity during wet years being much more pronounced than reductions during dry years. Strong increases in plant water-use efficiency, based on carbon and oxygen stable isotope analyses, contribute to the resilience of productivity during times of drought. Within a growing season increased stomatal limitation of photosynthesis, associated with improved water-use efficiency, resulted in apparent shifts in leaf xanthophyll cycle pigments and changes to the Photochemical Reflectance Index (PRI) calculated from hyper-spectral reflectance measurements conducted at the canopy-scale. These shifts in PRI were apparent before seasonal drought caused significant reductions in leaf area index (LAI) and changes to canopy-scale "greenness" based on NDVI values. With

Research on the Mechanism of Cross Regional Grassland Ecological Compensation

NASA Astrophysics Data System (ADS)

Yang, Ran; Ma, Jun

2018-01-01

In recent years, grassland environmental damage has become serious, and grassland resources protection task has become heavy, grassland ecological compensation has become an effective way to solve this problem; but the current grassland ecological compensation standards were low, the effect is poor. The fundamental reason is the model of administrative division destroys the integrity of grassland. Based on the analysis of the status quo of grassland compensation, this paper tries to protect the grassland integrity, breaks the administrative division restriction, implements the space regulation, constructs the framework of cross-regional grassland ecological compensation mechanism, describes its operation process. It provides new way to realize the sustainable development of the grassland environment.

Molecular Investigation of the Short-term Sequestration of Natural Abundance 13C -labelled Cow Dung in the Surface Horizons of a Temperate Grassland Soil

NASA Astrophysics Data System (ADS)

Dungait, J.; Bol, R.; Evershed, R. P.

2004-12-01

An adequate understanding of the carbon (C) sequestration potential of grasslands requires that the quantity and residence times of C inputs be measured. Herbivore dung is largely comprised of plant cell wall material, a significant source of stable C in intensively grazed temperate grassland ecosystems that contributes to the soil carbon budget. Our work uses compound-specific isotope analysis to identify the pattern of input of dung-derived compounds from natural abundance 13C/-labelled cow dung into the surface horizons of a temperate grassland soil over one year. C4 dung (δ 13C \\-12.6 ‰ ) from maize fed cows was applied to a temperate grassland surface (δ 13C \\-29.95 ‰ ) at IGER-North Wyke (Devon, UK), and dung remains and soil cores beneath the treatments collected at ŧ = 7, 14, 28, 56, 112, 224 and 372 days. Bulk dung carbon present in the 0\\-1 cm and 1\\-5 cm surface horizons of a grassland soil over one year was estimated using Δ 13C between C4 dung and C3 dung, after Bol {\\et al.} (2000). The major biochemical components of dung were quantified using proximate forage fibre analyses, after Goering and Van Soest (1970) and identified using `wet' chemical and GC-MS methods. Plant cell wall polysaccharides and lignin were found to account for up to 67 {%} of dung dry matter. Hydrolysed polysaccharides were prepared as alditol acetates for analyses (after Docherty {\\et al.}, 2001), and a novel application of an off-line pyrolysis method applied to measure lignin-derived phenolic compounds (after Poole & van Bergen, 2002). This paper focuses on major events in the incorporation of dung carbon, estimated using natural abundance 13C&-slash;labelling technique. This revealed a major bulk input of dung carbon after a period of significant rainfall with a consequent decline in bulk soil δ 13C values until the end of the experiment (Dungait {\\et al.}, submitted). Findings will be presented revealing contribution of plant cell wall polysaccharides and

Some insights on grassland health assessment based on remote sensing.

PubMed

Xu, Dandan; Guo, Xulin

2015-01-29

Grassland ecosystem is one of the largest ecosystems, which naturally occurs on all continents excluding Antarctica and provides both ecological and economic functions. The deterioration of natural grassland has been attracting many grassland researchers to monitor the grassland condition and dynamics for decades. Remote sensing techniques, which are advanced in dealing with the scale constraints of ecological research and provide temporal information, become a powerful approach of grassland ecosystem monitoring. So far, grassland health monitoring studies have mostly focused on different areas, for example, productivity evaluation, classification, vegetation dynamics, livestock carrying capacity, grazing intensity, natural disaster detecting, fire, climate change, coverage assessment and soil erosion. However, the grassland ecosystem is a complex system which is formed by soil, vegetation, wildlife and atmosphere. Thus, it is time to consider the grassland ecosystem as an entity synthetically and establish an integrated grassland health monitoring system to combine different aspects of the complex grassland ecosystem. In this review, current grassland health monitoring methods, including rangeland health assessment, ecosystem health assessment and grassland monitoring by remote sensing from different aspects, are discussed along with the future directions of grassland health assessment.

Some Insights on Grassland Health Assessment Based on Remote Sensing

PubMed Central

Xu, Dandan; Guo, Xulin

2015-01-01

Grassland ecosystem is one of the largest ecosystems, which naturally occurs on all continents excluding Antarctica and provides both ecological and economic functions. The deterioration of natural grassland has been attracting many grassland researchers to monitor the grassland condition and dynamics for decades. Remote sensing techniques, which are advanced in dealing with the scale constraints of ecological research and provide temporal information, become a powerful approach of grassland ecosystem monitoring. So far, grassland health monitoring studies have mostly focused on different areas, for example, productivity evaluation, classification, vegetation dynamics, livestock carrying capacity, grazing intensity, natural disaster detecting, fire, climate change, coverage assessment and soil erosion. However, the grassland ecosystem is a complex system which is formed by soil, vegetation, wildlife and atmosphere. Thus, it is time to consider the grassland ecosystem as an entity synthetically and establish an integrated grassland health monitoring system to combine different aspects of the complex grassland ecosystem. In this review, current grassland health monitoring methods, including rangeland health assessment, ecosystem health assessment and grassland monitoring by remote sensing from different aspects, are discussed along with the future directions of grassland health assessment. PMID:25643060

Temporal and spatial variations of canopy temperature over a C3C4 mixture grassland

NASA Astrophysics Data System (ADS)

Shimoda, S.; Oikawa, T.

2006-10-01

This study discusses the photosynthetic pathway types involved in canopy temperature measurements on a mixed grassland consisting of C3 and C4 plants (dominant species in biomass were Solidago altissima (C3), Miscanthus sinensis (C4), and Imperata cylindrica (C4)). In the wet conditions immediately after the rainy season, the mean canopy temperature for S. altissima was the lowest among the dominant species, mainly due to its leaf conductance being twice as large as the other two species. Despite using the same C4 photosynthetic pathway, M. sinensis had a lower apparent canopy temperature than I. cylindrica due to a smaller proportion of sunlit elements in the field of view. In the dry conditions during late July, the mean canopy temperatures of the three dominant species were within 0.3 °C of one another. These results can be explained by poor water conditions for C3 species (S. altissima). The simultaneous survey of vegetation and thermal imaging can help clarify characteristics of C3 and C4 canopy temperature over complicated grassland.

North American Grasslands & Biogeographic Regions

USDA-ARS?s Scientific Manuscript database

North American grasslands are the product of a long interaction among land, people, and animals. Covering over one billion hectares across Canada, the United States, and Mexico, a defining trait of the realm is its vast surface area. From subtropical grasslands interspersed with wetlands in the sout...

Assessing the Effects of Grassland Management on Forage Production and Environmental Quality to Identify Paths to Ecological Intensification in Mountain Grasslands.

PubMed

Loucougaray, Grégory; Dobremez, Laurent; Gos, Pierre; Pauthenet, Yves; Nettier, Baptiste; Lavorel, Sandra

2015-11-01

Ecological intensification in grasslands can be regarded as a process for increasing forage production while maintaining high levels of ecosystem functions and biodiversity. In the mountain Vercors massif, where dairy cattle farming is the main component of agriculture, how to achieve forage autonomy at farm level while sustaining environmental quality for tourism and local dairy products has recently stimulated local debate. As specific management is one of the main drivers of ecosystem functioning, we assessed the response of forage production and environmental quality at grassland scale across a wide range of management practices. We aimed to determine which components of management can be harnessed to better match forage production and environmental quality. We sampled the vegetation of 51 grasslands stratified across 13 grassland types. We assessed each grassland for agronomic and environmental properties, measuring forage production, forage quality, and indices based on the abundance of particular plant species such as timing flexibility, apiarian potential, and aromatic plants. Our results revealed an expected trade-off between forage production and environmental quality, notably by stressing the contrasts between sown and permanent grasslands. However, strong within-type variability in both production and environmental quality as well as in flexibility of timing of use suggests possible ways to improve this trade-off at grassland and farm scales. As achieving forage autonomy relies on increasing both forage production and grassland resilience, our results highlight the critical role of the ratio between sown and permanent grasslands as a major path for ecological intensification in mountain grasslands.

Avian assemblages on altered grasslands

USGS Publications Warehouse

Knopf, Fritz L.

1994-01-01

Grasslands comprise 17% of the North American landscape but provide primary habitat for only 5% of native bird species. On the Great Plains, grasslands include an eastern component of tall grasses and a western component of short grasses, both of which have been regionally altered by removing native grazers, plowing sod, draining wetlands, and encouraging woody vegetation. As a group, populations of endemic bird species of the grasslands have declined more than others (including neotropical migrants) in the last quarter century. Individually, populations of the Upland Sandpiper and McCown’s Longspur have increased; the wetlands-associated Marbled Godwit and Wilson’s Phalarope appear stable; breeding ranges are shifting for the Ferruginous Hawk, Mississippi Kite, Short-eared Owl, Upland Sandpiper, Horned Lark, Vesper, Savannah, and Henslow’s sparrows, and Western Meadowlark; breeding habitats are disappearing locally for Franklin’s Gull, Dickcissel, Henslow’s and Grasshopper sparrows. Lark Bunting, and Eastern Meadowlark; and populations are declining throughout the breeding ranges for Mountain Plover, and Cassin’s and Clay-colored sparrows. Declines of these latter three species, and also the Franklin’s Gull, presumably are due to ecological phenomena on their respective wintering areas. Unlike forest species that winter in the neotropics, most birds that breed in the North American grasslands also winter on the continent and problems driving declines in grassland species are associated almost entirely with North American processes. Contemporary programs and initiatives hold promise for the conservation of breeding habitats for these birds. Ecological ignorance of wintering habits and habitats clouds the future of the endemic birds of grasslands, especially those currently experiencing widespread declines across breeding locales.

Effects of leafy spurge infestation on grassland birds

USGS Publications Warehouse

Scheiman, D.M.; Bollinger, E.K.; Johnson, D.H.

2003-01-01

Grassland bird populations are declining. Invasive plant species may be contributing to these declines by altering habitat quality. However, the effects of invasive plants on grassland birds are largely unknown. Leafy spurge (Euphorbia esula) is an exotic, invasive weed in the northern Great Plains. We examined the effects of leafy spurge infestation on densities of breeding birds, nest-site selection, and nest success in grasslands on the Sheyenne National Grassland (SNG), North Dakota, USA, 1999-2000. We categorized spurge-infested grasslands into 3 groups (low, medium, high), based on the area covered by spurge patches. We surveyed 75 100-m-radius circular points (25 in each group), and searched for nests in 6 16-ha plots (2 in each group). Grasshopper sparrow (Ammodramus savannarum) and savannah sparrow (Passerculus sandwichensis) densities were lower on high-spurge points than on low- and medium-spurge points. Bobolink (Dolichonyx oryzivorus) and western meadowlark (Sturnella neglecta) densities were not significantly different among spurge cover groups. Spurge cover did not appear to be an important factor in nest-site selection. However, western meadowlark nest success was positively associated with spurge cover. Vegetation structure is an important indicator of habitat quality and resource availability for grassland birds. Changes in vegetation structure caused by introduced plant species, such as spurge, can alter resource availability and hence affect bird community composition. Managers of spurge-infested grasslands should continue current spurge control measures to help prevent further declines in grassland habitat quality and grassland bird populations.

Habitat associations of migrating and overwintering grassland birds in southern Texas

USGS Publications Warehouse

Igl, L.D.; Ballard, B.M.

1999-01-01

We report on the habitat associations of 21 species of grassland birds overwintering in or migrating through southern Texas, during 1991-1992 and 1992-1993. Ninety percent of our grassland bird observations were made during winter and spring, and only 10% occurred during fall. Grassland species made up a high proportion of the total bird densities in grassland and shrub-grassland habitats, but much lower proportions in the habitats with more woody vegetation. Fewer grassland species were observed in grassland and woodland than in brushland, parkland, and shrub-grassland habitats. Grassland birds generally were found in higher densities in habitats that had woody canopy coverage of < 30%; densities of grassland birds were highest in shrub-grassland habitat and lowest in woodland habitat. Species that are grassland specialists on their breeding grounds tended to be more habitat specific during the nonbreeding season compared to shrub-grassland specialists, which were more general in their nonbreeding-habitat usage. Nonetheless, our data demonstrate that grassland birds occur in a variety of habitats during the nonbreeding season and seem to occupy a broader range of habitats than previously described.

Habitat associations of migrating and overwintering grassland birds in Southern Texas

USGS Publications Warehouse

Igl, Lawrence D.; Ballard, Bart M.

1999-01-01

We report on the habitat associations of 21 species of grassland birds overwintering in or migrating through southern Texas, during 1991-1992 and 1992-1993. Ninety percent of our grassland bird observations were made during winter and spring, and only 10% occurred during fall. Grassland species made up a high proportion of the total bird densities in grassland and shrub-grassland habitats, but much lower proportions in the habitats with more woody vegetation. Fewer grassland species were observed in grassland and woodland than in brushland, parkland, and shrub-grassland habitats. Grassland birds generally were found in higher densities in habitats that had woody canopy coverage of < 30%; densities of grassland birds were highest in shrub-grassland habitat and lowest in woodland habitat. Species that are grassland specialists on their breeding grounds tended to be more habitat specific during the nonbreeding season compared to shrub-grassland specialists, which were more general in their nonbreeding-habitat usage. Nonetheless, our data demonstrate that grassland birds occur in a variety of habitats during the nonbreeding season and seem to occupy a broader range of habitats than previously described.

Grassland Assessment Categories and Extent

Treesearch

Wayne A. Robbie

2004-01-01

This chapter establishes a general framework for describing the various kinds of grasslands outlined in subsequent chapters. This framework outlines the major categories or classes of grasslands that occur as part of Southwestern terrestrial ecosystems within National Forest System lands and provides an ecological and environmental context in regards to how they differ...

Fog-drip contributions to soil moisture as determined through passive fog collector measurements, leaf wetness data, and soil moisture at Pepperwood Preserve, Sonoma County, California.

NASA Astrophysics Data System (ADS)

Micheli, L.; Dodge, C.; Fernandez, D.; Weiss, P. L.; Flint, L. E.; Flint, A. L.; Torregrosa, A.

2016-12-01

Summertime coastal fog advects from the ocean and transports water inland in the form of fog droplets to forests and grasslands. The amount of fog water delivered to the soil through fog drip from foliage and other surfaces that have captured and accumulated the droplets is often difficult to quantify due to many challenges including the difficulty of measuring the relatively small variations in soil moisture that accompany fog events. This study details summer season records collected from 4 sites at the Pepperwood Preserve in Santa Rosa, CA. Fog drip volumes were measured using 1 m2 standard fog collectors located at a grassland site for the past three summers. Soil moisture measurements were collected for portions of the three summer seasons from three sites: two oak woodland understory sites and a grassland site on the edge of a forest. One oak woodland site was within 400 m of the standard fog collector grassland site. Leaf wetness sensors (LWS) were co-located at all soil moisture sites. We observe a much higher frequency of wet periods at the grassland site than at the nearby oak woodland site during the summer fog season. One hypothesis is that the oak canopy acts to protect the LWS at the oak woodland site from nocturnal radiative cooling, thereby reducing condensation and dew formation. Another hypothesis is that the oak woodland canopy tends sheltered the understory during light fog events, resulting in edge effects that may tend to reduce fog deposition within the canopy. Leaf and soil moisture measurements both during fog events and during periods without fog but when dew point is reached may provide a more complete picture of non-rain mechanisms of moisture delivery to the foliage and the soil. Investigations are on-going to include corresponding meteorological data (wind speed and direction, relative humidity and temperature) to understand relative contributions to the soil associated with both fog and dew and to better distinguish between fog and

Habitat and landscape effects on abundance of Missouri's grassland birds

USGS Publications Warehouse

Jacobs, R.B.; Thompson, F.R.; Koford, Rolf R.; La Sorte, F.A.; Woodward, H.D.; Fitzgerald, J.A.

2012-01-01

Of 6 million ha of prairie that once covered northern and western Missouri, <36,500 ha remain, with planted, managed, and restored grasslands comprising most contemporary grasslands. Most grasslands are used as pasture or hayfields. Native grasses largely have been replaced by fescue (Festuca spp.) on most private lands (almost 7 million ha). Previously cropped fields set aside under the Conservation Reserve Program (CRP) varied from a mix of cool-season grasses and forbs, or mix of native warm-season grasses and forbs, to simple tall-grass monocultures. We used generalized linear mixed models and distance sampling to assess abundance of 8 species of breeding grassland birds on 6 grassland types commonly associated with farm practices in Missouri and located in landscapes managed for grassland-bird conservation. We selected Bird Conservation Areas (BCAs) for their high percentage of grasslands and grassland-bird species, and for <5% forest cover. We used an information-theoretic approach to assess the relationship between bird abundance and 6 grassland types, 3 measures of vegetative structure, and 2 landscape variables (% grassland and edge density within a 1-km radius). We found support for all 3 levels of model parameters, although there was less support for landscape than vegetation structure effects likely because we studied high-percentage-grassland landscapes (BCAs). Henslow's sparrow (Ammodramus henslowii) counts increased with greater percentage of grassland, vegetation height-density, litter depth, and shrub cover and lower edge density. Henslow's sparrow counts were greatest in hayed native prairie. Dickcissel (Spiza americana) counts increased with greater vegetation height-density and were greatest in planted CRP grasslands. Grasshopper sparrow (A. savannarum) counts increased with lower vegetation height, litter depth, and shrub cover. Based on distance modeling, breeding densities of Henslow's sparrow, dickcissel, and grasshopper sparrow in the 6

Habitat and landscape effects on abundance of Missouri's grassland birds

USGS Publications Warehouse

Jacobson, Robert B.; Thompson, Frank R.; Koford, Rolf R.; La Sorte, Frank A.; Woodward, Hope D.; Fitzgerald, Jane A.

2012-01-01

Of 6 million ha of prairie that once covered northern and western Missouri, <36,500 ha remain, with planted, managed, and restored grasslands comprising most contemporary grasslands. Most grasslands are used as pasture or hayfields. Native grasses largely have been replaced by fescue (Festuca spp.) on most private lands (almost 7 million ha). Previously cropped fields set aside under the Conservation Reserve Program (CRP) varied from a mix of cool-season grasses and forbs, or mix of native warm-season grasses and forbs, to simple tall-grass monocultures. We used generalized linear mixed models and distance sampling to assess abundance of 8 species of breeding grassland birds on 6 grassland types commonly associated with farm practices in Missouri and located in landscapes managed for grassland-bird conservation. We selected Bird Conservation Areas (BCAs) for their high percentage of grasslands and grassland-bird species, and for <5% forest cover. We used an information-theoretic approach to assess the relationship between bird abundance and 6 grassland types, 3 measures of vegetative structure, and 2 landscape variables (% grassland and edge density within a 1-km radius). We found support for all 3 levels of model parameters, although there was less support for landscape than vegetation structure effects likely because we studied high-percentage-grassland landscapes (BCAs). Henslow's sparrow (Ammodramus henslowii) counts increased with greater percentage of grassland, vegetation height-density, litter depth, and shrub cover and lower edge density. Henslow's sparrow counts were greatest in hayed native prairie. Dickcissel (Spiza americana) counts increased with greater vegetation height-density and were greatest in planted CRP grasslands. Grasshopper sparrow (A. savannarum) counts increased with lower vegetation height, litter depth, and shrub cover. Based on distance modeling, breeding densities of Henslow's sparrow, dickcissel, and grasshopper sparrow in the 6

Grassland agriculture

USDA-ARS?s Scientific Manuscript database

Agriculture in grassland environments is facing multiple stresses from: shifting demographics, declining and fragmented agricultural landscapes, declining environmental quality, variable and changing climate, volatile and increasing energy costs, marginal economic returns, and globalization. Degrad...

Importance and functions of European grasslands.

PubMed

Carlier, L; De Vliegher, A; Van Cleemput, O; Boeckx, P

2005-01-01

The European agricultural policy is not simple and needs to accommodate also social and environmental requirements. Grassland will continue to be an important form of land use in Europe, but with increased diversity in management objectives and systems used. Besides its role as basic nutrient for herbivores and ruminants grasslands have opportunities for adding value by exploiting positive health characteristics in animal products from grassland and through the delivery of environmental benefits. In fact grasslands contribute to a high degree to the struggle against erosion and to the regularizing of water regimes, to the purification of fertilizers and pesticides and to biodiversity. Finally they have aesthetic role and recreational function as far as they provide public access that other agricultural uses do not allow. But even for grassland it is very difficult to create a good frame for its different tasks (1) the provision of forage for livestock, (2) protection and conservation of soil and water resources, (3) furnishing a habitat for wildlife, both flora and fauna and (4) contribution to the attractiveness of the landscape. Nevertheless it is the only crop, able to fulfil so many tasks and to fit so many requirements.

Sustaining the grassland sea: Regional perspectives on identifying, protecting and restoring the Sky Island region's most intact grassland valley landscapes

Treesearch

Gitanjali S. Bodner; Peter Warren; David Gori; Karla Sartor; Steven Bassett

2013-01-01

Grasslands of the Sky Islands region once covered over 13 million acres in southeastern Arizona and adjacent portions of New Mexico, Sonora, and Chihuahua. Attempts to evaluate current ecological conditions suggest that approximately two thirds of these remain as intact or restorable grassland habitat. These grasslands provide watershed services such as flood control...

Birds of Cimarron National Grassland

Treesearch

Ted T. Cable; Scott Seltman; Kevin J. Cook

1996-01-01

Bird records for the Cimarron National Grassland were collected from literature searches and unpublished field notes submitted by cooperators. Almost 14,000 bird records were compiled in a data file. Based on these data, the status of each bird species reported to have occurred on the Cimarron National Grassland was established. In addition to the species accounts, the...

Negative global phosphorus budgets challenge sustainable intensification of grasslands

PubMed Central

Sattari, S. Z.; Bouwman, A. F.; Martinez Rodríguez, R.; Beusen, A. H. W.; van Ittersum, M. K.

2016-01-01

Grasslands provide grass and fodder to sustain the growing need for ruminant meat and milk. Soil nutrients in grasslands are removed through withdrawal in these livestock products and through animal manure that originates from grasslands and is spread in croplands. This leads to loss of soil fertility, because globally most grasslands receive no mineral fertilizer. Here we show that phosphorus (P) inputs (mineral and organic) in global grasslands will have to increase more than fourfold in 2050 relative to 2005 to achieve an anticipated 80% increase in grass production (for milk and meat), while maintaining the soil P status. Combined with requirements for cropland, we estimate that mineral P fertilizer use must double by 2050 to sustain future crop and grassland production. Our findings point to the need to better understand the role of grasslands and their soil P status and their importance for global food security. PMID:26882144

Grassland birds: An overview of threats and recommended management strategies

USGS Publications Warehouse

Vickery, P.D.; Herkert, J.R.; Knopf, F.L.; Ruth, J.; Keller, C.E.; Bonney, Rick; Pashley, David N.; Cooper, Robert; Niles, Larry

2000-01-01

Grassland ecosystems are dependent on periodic disturbance for habitat maintenance. Historically, grazing by native herbivores and prairie fires were the agents principally responsible for maintaining grassland areas. However, elimination of native herbivores, wide-spread fire suppression, and conversion for agriculture have greatly altered grasslands in the United States and Canada. Because of these landscape changes, many grassland birds are increasingly dependent on land managers for habitat creation, maintenance, and health. Grazing, prescribed burning, and mowing/haying are the most frequently used, and versatile, grassland management techniques. Grassland birds prefer a wide range of grass heights and densities, with some species preferring short sparse vegetation, and others preferring taller, more dense vegetation. Due to differences in species habitat preferences and regional differences in soils and floristics, the responses of individual grassland species to specific grassland management practices can be variable and often are regionally dependent. As a result, management of grassland areas is best directed toward the creation of a mosaic of grassland habitat types. This habitat mosaic is probably best maintained through some type of rotational management system in which sections of large grassland areas receive management on a regular schedule. Such a rotational system would provide a variety of habitat types in every year, would ensure the availability of suitable habitat for birds at either end of the grassland management spectrum, and also would provide habitat for birds whose preferences lie between these extremes.

[Research progress and trend on grassland agroecology].

PubMed

Ren, Jizhou; Li, Xianglin; Hou, Fujiang

2002-08-01

The connotation, progress, research frontiers and developmental trend of grassland agroecology are discussed in this paper. The interface theory, structure and function, coupling and discordance, and health assessment of grassland agroecosystems were recognized as the four research frontiers of the discipline. There exist three primary interfaces in a grassland agroecosystem, i.e., vegetation-site, grassland-animal and production-management. Research into a series of the ecological processes that occurred at these interfaces is the key to revealing the features of the system behavior. There are four sections in a grassland agroecosystem, i.e., pre-plant, plant, animal and post-biotic sections. System coupling and discordance are the two important concepts to describe interactions among the production sections. System coupling among the sections can lead to system improvement by exerting the potential of system capacity. Health of an ecosystem is a reflection of its structure and function, and health assessment is a measurement of its orderliness and service value.

Measuring grassland structure for recovery of grassland species at risk

NASA Astrophysics Data System (ADS)

Guo, Xulin; Gao, Wei; Wilmshurst, John

2005-09-01

An action plan for recovering species at risk (SAR) depends on an understanding of the plant community distribution, vegetation structure, quality of the food source and the impact of environmental factors such as climate change at large scale and disturbance at small scale, as these are fundamental factors for SAR habitat. Therefore, it is essential to advance our knowledge of understanding the SAR habitat distribution, habitat quality and dynamics, as well as developing an effective tool for measuring and monitoring SAR habitat changes. Using the advantages of non-destructive, low cost, and high efficient land surface vegetation biophysical parameter characterization, remote sensing is a potential tool for helping SAR recovery action. The main objective of this paper is to assess the most suitable techniques for using hyperspectral remote sensing to quantify grassland biophysical characteristics. The challenge of applying remote sensing in semi-arid and arid regions exists simply due to the lower biomass vegetation and high soil exposure. In conservation grasslands, this problem is enhanced because of the presence of senescent vegetation. Results from this study demonstrated that hyperspectral remote sensing could be the solution for semi-arid grassland remote sensing applications. Narrow band raw data and derived spectral vegetation indices showed stronger relationships with biophysical variables compared to the simulated broad band vegetation indices.

Land tenure reform and grassland degradation in Inner Mongolia, China

NASA Astrophysics Data System (ADS)

Liu, Min; Dries, Liesbeth; Heijman, Wim; Huang, Jikun; Zhu, Xueqin; Deng, Xiangzheng

2017-04-01

Since the start of the land tenure reform in the pastoral areas of China in the 1980s, grassland use rights have increasingly been assigned to individual households and subsequently more grasslands have been in private use. However, in the same period, most of the grasslands in China have experienced degradation. The question that this paper tries to address is whether the land tenure reform plays a significant role in grassland degradation. It is answered by an empirical analysis of the impact of land tenure reform on the changes in grassland condition, using data from 60 counties in Inner Mongolia between 1985 and 2008. Grassland condition is presented by grassland quantity and quality using spatial information based on remote sensing. The timing of the assignment of grassland use rights and the timing of the actual adoption of private use by households differ among counties. These timing differences and differences in grassland condition among counties allow disentangling the impact of the land tenure reform. A fixed effects model is used to control for climate, agricultural activity and the time-invariant heterogeneity among counties. The model results show that the private use of grasslands following the land tenure reform has had significantly negative effects on grassland quality and quantity in Inner Mongolia. Moreover, the negative effects did not disappear even after several years of experience with private use. In conclusion, our analysis reveals that the land tenure reform, namely privatisation of grassland use rights, is a significant driver of grassland degradation in Inner Mongolia in a long term, which presents "a tragedy of privatisation", as opposed to the well-known "tragedy of the commons".

Species Richness Responses to Structural or Compositional Habitat Diversity between and within Grassland Patches: A Multi-Taxon Approach

PubMed Central

Lengyel, Szabolcs; Déri, Eszter; Magura, Tibor

2016-01-01

Habitat diversity (spatial heterogeneity within and between habitat patches in a landscape, HD) is often invoked as a driver of species diversity at small spatial scales. However, the effect of HD on species richness (SR) of multiple taxa is not well understood. We quantified HD and SR in a wet-dry gradient of open grassland habitats in Hortobágy National Park (E-Hungary) and tested the effect of compositional and structural factors of HD on SR of flowering plants, orthopterans, true bugs, spiders, ground beetles and birds. Our dataset on 434 grassland species (170 plants, 264 animals) showed that the wet-dry gradient (compositional HD at the between-patch scale) was primarily related to SR in orthopterans, ground-dwelling arthropods, and all animals combined. The patchiness, or plant association richness, of the vegetation (compositional HD at the within-patch scale) was related to SR of vegetation-dwelling arthropods, whereas vegetation height (structural HD at the within-patch scale) was related to SR of ground-dwelling arthropods and birds. Patch area was related to SR only in birds, whereas management (grazing, mowing, none) was related to SR of plants and true bugs. All relationships between HD and SR were positive, indicating increasing SR with increasing HD. However, total SR was not related to HD because different taxa showed similar positive responses to different HD variables. Our findings, therefore, show that even though HD positively influences SR in a wide range of grassland taxa, each taxon responds to different compositional or structural measures of HD, resulting in the lack of a consistent relationship between HD and SR when taxon responses are pooled. The idiosyncratic responses shown here exemplify the difficulties in detecting general HD-SR relationships over multiple taxa. Our results also suggest that management and restoration aimed specifically to sustain or increase the diversity of habitats are required to conserve biodiversity in

Asymmetric responses of primary productivity to altered precipitation simulated by ecosystem models across three long-term grassland sites

NASA Astrophysics Data System (ADS)

Wu, Donghai; Ciais, Philippe; Viovy, Nicolas; Knapp, Alan K.; Wilcox, Kevin; Bahn, Michael; Smith, Melinda D.; Vicca, Sara; Fatichi, Simone; Zscheischler, Jakob; He, Yue; Li, Xiangyi; Ito, Akihiko; Arneth, Almut; Harper, Anna; Ukkola, Anna; Paschalis, Athanasios; Poulter, Benjamin; Peng, Changhui; Ricciuto, Daniel; Reinthaler, David; Chen, Guangsheng; Tian, Hanqin; Genet, Hélène; Mao, Jiafu; Ingrisch, Johannes; Nabel, Julia E. S. M.; Pongratz, Julia; Boysen, Lena R.; Kautz, Markus; Schmitt, Michael; Meir, Patrick; Zhu, Qiuan; Hasibeder, Roland; Sippel, Sebastian; Dangal, Shree R. S.; Sitch, Stephen; Shi, Xiaoying; Wang, Yingping; Luo, Yiqi; Liu, Yongwen; Piao, Shilong

2018-06-01

Field measurements of aboveground net primary productivity (ANPP) in temperate grasslands suggest that both positive and negative asymmetric responses to changes in precipitation (P) may occur. Under normal range of precipitation variability, wet years typically result in ANPP gains being larger than ANPP declines in dry years (positive asymmetry), whereas increases in ANPP are lower in magnitude in extreme wet years compared to reductions during extreme drought (negative asymmetry). Whether the current generation of ecosystem models with a coupled carbon-water system in grasslands are capable of simulating these asymmetric ANPP responses is an unresolved question. In this study, we evaluated the simulated responses of temperate grassland primary productivity to scenarios of altered precipitation with 14 ecosystem models at three sites: Shortgrass steppe (SGS), Konza Prairie (KNZ) and Stubai Valley meadow (STU), spanning a rainfall gradient from dry to moist. We found that (1) the spatial slopes derived from modeled primary productivity and precipitation across sites were steeper than the temporal slopes obtained from inter-annual variations, which was consistent with empirical data; (2) the asymmetry of the responses of modeled primary productivity under normal inter-annual precipitation variability differed among models, and the mean of the model ensemble suggested a negative asymmetry across the three sites, which was contrary to empirical evidence based on filed observations; (3) the mean sensitivity of modeled productivity to rainfall suggested greater negative response with reduced precipitation than positive response to an increased precipitation under extreme conditions at the three sites; and (4) gross primary productivity (GPP), net primary productivity (NPP), aboveground NPP (ANPP) and belowground NPP (BNPP) all showed concave-down nonlinear responses to altered precipitation in all the models, but with different curvatures and mean values. Our results

Comparison of phenothrin mousse, phenothrin lotion, and wet-combing for treatment of head louse infestation in the UK: a pragmatic randomised, controlled, assessor blind trial

PubMed Central

Burgess, Ian F.; Brown, Christine M.; Nair, Pat

2014-01-01

In this investigation of effectiveness of an alternative pediculicide dosage form, we recruited 228 children and 50 adult participants from Bedfordshire, UK, to a randomised, controlled, assessor blind trial comparing two insecticide products with mechanical removal of lice as a control group.  Participants using insecticide were treated with either the investigative 0.5% phenothrin mousse, for 30 minutes, or 0.2% phenothrin lotion, for 2 hours as the reference product.  Both treatments were applied only once, followed by shampoo washing.  Those treated by wet-combing with conditioner were combed 4 times over 12 days.  Parents/carers carried out the treatments to mimic normal consumer use.  The outcome measure was the absence of lice, 14 days after treatment for the insecticides, and up to 14 days after completion of combing.  Intention to treat analysis of the outcomes for 275 participants showed success for phenothrin mousse in 21/105 (20.0%), in 23/107 (21.5%) for phenothrin lotion, and in 12/63 (19.1%) for wet-combing.  People receiving mousse were 1.07 (95% CI, 0.63 to 1.81) times more likely to still have lice after treatment compared with those treated with lotion. The group of participants who received the wet combing treatment were 1.13 (95% CI, 0.61 to 2.11) times more likely to still have lice after the treatment.  None of the treatments was significantly (p < 0.05) more effective than any other. This study was carried out in an area where moderate resistance to phenothrin was demonstrated after the study by using a bioassay.  Analysis of post treatment assessments found that failure of insecticides to kill louse eggs had influenced the outcome. PMID:25254106

Exacerbated degradation and desertification of grassland in Central Asia

NASA Astrophysics Data System (ADS)

Zhang, G.; Xiao, X.; Biradar, C. M.; Dong, J.; Zhou, Y.; Qin, Y.; Zhang, Y.; Liu, F.; Ding, M.; Thomas, R. J.

2016-12-01

Grassland desertification is a complex process, including both state conversion (e.g., grasslands to deserts) and gradual within-state change (e.g., greenness dynamics). Existing studies generally did not separate the two components and analyzed them based on time series vegetation indices, which however cannot provide a clear and comprehensive picture for desertification. Here we proposed a desertification zone classification-based grassland degradation strategy to detect the grassland desertification process in Central Asia. First, annual spatially explicit maps of grasslands and deserts were generated to track the conversion between grasslands and deserts. The results showed that 13 % of grasslands were converted to deserts from 2000 to 2014, with an increasing desertification trend northward in the latitude range of 43-48°N. Second, a fragile and unstable Transitional zone was identified in southern Kazakhstan based on desert frequency maps. Third, gradual vegetation dynamics during the thermal growing season (EVITGS) were investigated using linear regression and Mann-Kendall approaches. The results indicated that grasslands generally experienced widespread degradation in Central Asia, with an additional hotspot identified in the northern Kazakhstan. Finally, attribution analyses of desertification were conducted by correlating vegetation dynamics with three different drought indices (Palmer Drought Severity Index (PDSI), Standardized Precipitation Index (SPI), and Drought Severity Index (DSI)), precipitation, and temperature, and showed that grassland desertification was exacerbated by droughts, and persistent drought was the main factor for grassland desertification in Central Asia. This study provided essential information for taking practical actions to prevent the further desertification and targeting right spots for better intervention to combat the land degradation in the region.

[Needles stable carbon isotope composition and traits of Pinus sylvestris var. mongolica in sparse wood grassland in south edge of Keerqin Sandy Land under the conditions of different precipitation].

PubMed

Song, Li-Ning; Zhu, Jiao-Jun; Li, Ming-Cai; Yan, Tao; Zhang, Jin-Xin

2012-06-01

A comparative study was conducted on the needles stable carbon isotope composition (delta13 C), specific leaf area (SLA), and dry matter content (DMC) of 19-year-old Pinus sylvestris var. mongolica trees in a sparse wood grassland in the south edge of Keerqin Sandy Land under the conditions of extreme drought and extreme wetness, aimed to understand the water use of Pinus sylvestris under the conditions of extreme precipitation. The soil water content and groundwater level were also measured. In the dry year (2009), the soil water content in the grassland was significantly lower than that in the wet year (2010), but the delta13C values of the current year-old needles had no significant difference between the two years and between the same months of the two years. The SLA of the current year-old needles was significantly lower in the dry year than in the wet year, but the DMC had no significant difference between the two years. Under the conditions of the two extreme precipitations, the water use efficiency of the trees did not vary remarkably, and the trees could change their needles SLA to adapt the variations of precipitation. For the test ecosystem with a groundwater level more than 3.0 m, extreme drought could have no serious impact on the growth and survival of the trees.

Estimation of Nitrous Oxide Emissions from US Grasslands.

PubMed

Mummey; Smith; Bluhm

2000-02-01

/ Nitrous oxide (N(2)O) emissions from temperate grasslands are poorly quantified and may be an important part of the atmospheric N(2)O budget. In this study N(2)O emissions were simulated for 1052 grassland sites in the United States using the NGAS model of Parton and others (1996) coupled with an organic matter decomposition model. N(2)O flux was calculated for each site using soil and land use data obtained from the National Resource Inventory (NRI) database and weather data obtained from NASA. The estimates were regionalized based upon temperature and moisture isotherms. Annual N(2)O emissions for each region were based on the grassland area of each region and the mean estimated annual N(2)O flux from NRI grassland sites in the region. The regional fluxes ranged from 0.18 to 1.02 kg N(2)O N/ha/yr with the mean flux for all regions being 0.28 kg N(2)O N/ha/yr. Even though fluxes from the western regions were relatively low, these regions made the largest contribution to total emissions due to their large grassland area. Total US grassland N(2)O emissions were estimated to be about 67 Gg N(2)O N/yr. Emissions from the Great Plains states, which contain the largest expanse of natural grassland in the United States, were estimated to average 0.24 kg N(2)O N/ha/yr. Using the annual flux estimate for the temperate Great Plains, we estimate that temperate grasslands worldwide may potentially produce 0.27 Tg N(2)O N/yr. Even though our estimate for global temperate grassland N(2)O emissions is less than published estimates for other major temperate and tropical biomes, our results indicate that temperate grasslands are a significant part of both United States and global atmospheric N(2)O budgets. This study demonstrates the utility of models for regional N(2)O flux estimation although additional data from carefully designed field studies is needed to further validate model results.

Management of water resources for grasslands

USDA-ARS?s Scientific Manuscript database

Grasslands support essential food and fiber production, biodiversity, and water function. In general, urban areas and cropland occupies the most fertile, flattest, and humid lands, while planted or native grasslands are located on drier, steeper, or less fertile areas of any region. With continuin...

Grassland bats and land management in the Southwest

Treesearch

Alice L. Chung-MacCoubrey

1996-01-01

Of the bat research that has been conducted in the Southwestern states, few studies have addressed species inhabiting grasslands and the potential effects of management activities on these populations. Up to 17 bat species may be found regularly or occasionally in Southwestern grasslands or short-grass prairie. Main habitat requirements of grassland-dwelling bats are...

Phosphorus cycles of forest and upland grassland ecosystems and some effects of land management practices.

PubMed

Harrison, A F

The distribution of phosphorus capital and net annual transfers of phosphorus between the major components of two unfertilized phosphorus-deficient UK ecosystems, an oak--ash woodland in the Lake District and an Agrostis-Festuca grassland in Snowdonia (both on acid brown-earth soils), have been estimted in terms of kg P ha--1. In both ecosystems less than 3% of the phosphorus, totalling 1890 kg P ha--1 and 3040 kg P ha--1 for the woodland and grassland, respectively, is contained in the living biomass and half that is below ground level. Nearly all the phosphorus is in the soil matrix. Although the biomass phosphorus is mostly in the vegetation, the soil fauna and vegetation is slower (25%) than in the grassland vegetatation (208%). More than 85% of the net annual vegetation uptake of phosphorus from the soil is returned to the soil, mainly in organic debris, which in the grassland ecosystem is more than twice as rich in phosphorus (0.125% P) as in the woodland ecosystem (0.053% P). These concentrations are related to the rates of turnover (input/P content) of phosphorus in the litter layer on the soil surface; it is faster in the grassland (460%) than in the woodland (144%). In both cycles plant uptake of phosphorus largely depends on the release of phosphorus through decomposition of the organic matter returned to soil. In both the woodland and the grassland, the amount of cycling phosphorus is potentially reduced by its immobilization in tree and sheep production and in undecomposed organic matter accumulating in soil. It is assumed that the reductions are counterbalanced by the replenishment of cycling phosphorus by (i) some mineralization of organically bound phosphorus in the mineral soil, (ii) the income in rainfall and aerosols not being effectively lost in soil drainage waters and (iii) rock weathering. The effects of the growth of conifers and sheep grazing on the balance between decomposition and accumulation of organic matter returned to soil are

Incorporating grassland management in a global vegetation model

NASA Astrophysics Data System (ADS)

Chang, Jinfeng; Viovy, Nicolas; Vuichard, Nicolas; Ciais, Philippe; Wang, Tao; Cozic, Anne; Lardy, Romain; Graux, Anne-Isabelle; Klumpp, Katja; Martin, Raphael; Soussana, Jean-François

2013-04-01

Grassland is a widespread vegetation type, covering nearly one-fifth of the world's land surface (24 million km2), and playing a significant role in the global carbon (C) cycle. Most of grasslands in Europe are cultivated to feed animals, either directly by grazing or indirectly by grass harvest (cutting). A better understanding of the C fluxes from grassland ecosystems in response to climate and management requires not only field experiments but also the aid of simulation models. ORCHIDEE process-based ecosystem model designed for large-scale applications treats grasslands as being unmanaged, where C / water fluxes are only subject to atmospheric CO2 and climate changes. Our study describes how management of grasslands is included in the ORCHIDEE, and how management affects modeled grassland-atmosphere CO2 fluxes. The new model, ORCHIDEE-GM (Grassland Management) is capable with a management module inspired from a grassland model (PaSim, version 5.0), of accounting for two grassland management practices (cutting and grazing). The evaluation of the results of ORCHIDEE-GM compared with those of ORCHIDEE at 11 European sites equipped with eddy covariance and biometric measurements, show that ORCHIDEE-GM can capture realistically the cut-induced seasonal variation in biometric variables (LAI: Leaf Area Index; AGB: Aboveground Biomass) and in CO2 fluxes (GPP: Gross Primary Productivity; TER: Total Ecosystem Respiration; and NEE: Net Ecosystem Exchange). But improvements at grazing sites are only marginal in ORCHIDEE-GM, which relates to the difficulty in accounting for continuous grazing disturbance and its induced complex animal-vegetation interactions. Both NEE and GPP on monthly to annual timescales can be better simulated in ORCHIDEE-GM than in ORCHIDEE without management. At some sites, the model-observation misfit in ORCHIDEE-GM is found to be more related to ill-constrained parameter values than to model structure. Additionally, ORCHIDEE-GM is able to simulate

To what extent does urbanisation affect fragmented grassland functioning?

PubMed

van der Walt, L; Cilliers, S S; Kellner, K; Du Toit, M J; Tongway, D

2015-03-15

Urbanisation creates altered environments characterised by increased human habitation, impermeable surfaces, artificial structures, landscape fragmentation, habitat loss, resulting in different resource loss pathways. The vulnerable Rand Highveld Grassland vegetation unit in the Tlokwe Municipal area, South Africa, has been extensively affected and transformed by urbanisation, agriculture, and mining. Grassland fragments in urban areas are often considered to be less species rich and less functional than in the more untransformed or "natural" exurban environments, and are therefore seldom a priority for conservation. Furthermore, urban grassland fragments are often being more intensely managed than exurban areas, such as consistent mowing in open urban areas. Four urbanisation measures acting as indicators for patterns and processes associated with urban areas were calculated for matrix areas surrounding each selected grassland fragment to quantify the position of each grassland remnant along an urbanisation gradient. The grassland fragments were objectively classified into two classes of urbanisation, namely "exurban" and "urban" based on the urbanisation measure values. Grazing was recorded in some exurban grasslands and mowing in some urban grassland fragments. Unmanaged grassland fragments were present in both urban and exurban areas. Fine-scale biophysical landscape function was determined by executing the Landscape Function Analysis (LFA) method. LFA assesses fine-scale landscape patchiness (entailing resource conserving potential and erosion resistance) and 11 soil surface indicators to produce three main LFA parameters (stability, infiltration, and nutrient cycling), which indicates how well a system is functioning in terms of fine-scale biophysical soil processes and characteristics. The aim of this study was to determine the effects of urbanisation and associated management practices on fine-scale biophysical landscape function of urban and exurban

Grassland birds wintering at U.S. Navy facilities in southern Texas

USGS Publications Warehouse

Woodin, Marc C.; Skoruppa, Mary Kay; Bryan, Pearce D.; Ruddy, Amanda J.; Hickman, Graham C.

2010-01-01

Grassland birds have undergone widespread decline throughout North America during the past several decades. Causes of this decline include habitat loss and fragmentation because of conversion of grasslands to cropland, afforestation in the East, brush and shrub invasion in the Southwest and western United States, and planting of exotic grass species to enhance forage production. A large number of exotic plant species, including grasses, have been introduced in North America, but most research on the effects of these invasions on birds has been limited to breeding birds, primarily those in northern latitudes. Research on the effects of exotic grasses on birds in winter has been extremely limited.This is the first study in southern Texas to examine and compare winter bird responses to native and exotic grasslands. This study was conducted during a period of six years (2003–2009) on United States Navy facilities in southern Texas including Naval Air Station–Corpus Christi, Naval Air Station–Kingsville, Naval Auxiliary Landing Field Waldron, Naval Auxiliary Landing Field Orange Grove, and Escondido Ranch, all of which contained examples of native grasslands, exotic grasslands, or both. Data from native and exotic grasslands were collected and compared for bird abundance and diversity; ground cover, vegetation density, and floristic diversity; bird and vegetation relationships; diversity of insects and arachnids; and seed abundance and diversity. Effects of management treatments in exotic grasslands were evaluated by comparing numbers and diversity of birds and small mammals in mowed, burned, and control areas.To determine bird abundance and bird species richness, birds were surveyed monthly (December–February) during the winters of 2003–2008 in transects (100 meter × 20 meter) located in native and exotic grasslands distributed at all five U.S. Navy facilities. To compare vegetation in native and exotic grasslands, vegetation characteristics were measured

Grassland ecosystems of the Llano Estacado

Treesearch

Eileen Johnson

2007-01-01

The Llano Estacado, or Southern High Plains, has been a grassland throughout the Quaternary. The character of this grassland has varied through time, alternating between open, parkland, and savannah as the climate has changed. Different lines of evidence are used to reconstruct the climatic regimes and ecosystems, consisting of sediments and soils, vertebrate and...

Factors associated with grassland bird species richness: The relative roles of grassland area, landscape structure, and prey

Treesearch

Tammy L. Hamer; Curtis H. Flather; Barry R. Noon

2006-01-01

The factors responsible for widespread declines of grassland birds in the United States are not well understood. This study, conducted in the short-grass prairie of eastern Wyoming, was designed to investigate the relationship between variation in habitat amount, landscape heterogeneity, prey resources, and spatial variation in grassland bird species richness. We...

AmeriFlux US-Seg Sevilleta grassland

DOE Data Explorer

Litvak, Marcy [University of New Mexico

2016-01-01

This is the AmeriFlux version of the carbon flux data for the site US-Seg Sevilleta grassland. Site Description - The Sevilleta Desert Grassland site is located within the McKenzie Flats area of the Sevilleta National Wildlife Refuge (NWR), central New Mexico. Historically, this area has been used for livestock grazing; however, the McKenzie Flats have not been grazed since 1973 and the effects of this previous grazing are considered negligible for the purposes of this study. As the name suggests, McKenzie Flats is an extensive (~130 km2), nearly flat, mixed-species desert grassland bounded on the east by Los Pinos Mountains and on the west by the Rio Grande.

Future productivity and phenology changes in European grasslands for different warming levels: implications for grassland management and carbon balance.

PubMed

Chang, Jinfeng; Ciais, Philippe; Viovy, Nicolas; Soussana, Jean-François; Klumpp, Katja; Sultan, Benjamin

2017-12-01

Europe has warmed more than the global average (land and ocean) since pre-industrial times, and is also projected to continue to warm faster than the global average in the twenty-first century. According to the climate models ensemble projections for various climate scenarios, annual mean temperature of Europe for 2071-2100 is predicted to be 1-5.5 °C higher than that for 1971-2000. Climate change and elevated CO 2 concentration are anticipated to affect grassland management and livestock production in Europe. However, there has been little work done to quantify the European-wide response of grassland to future climate change. Here we applied ORCHIDEE-GM v2.2, a grid-based model for managed grassland, over European grassland to estimate the impacts of future global change. Increases in grassland productivity are simulated in response to future global change, which are mainly attributed to the simulated fertilization effect of rising CO 2 . The results show significant phenology shifts, in particular an earlier winter-spring onset of grass growth over Europe. A longer growing season is projected over southern and southeastern Europe. In other regions, summer drought causes an earlier end to the growing season, overall reducing growing season length. Future global change allows an increase of management intensity with higher than current potential annual grass forage yield, grazing capacity and livestock density, and a shift in seasonal grazing capacity. We found a continual grassland soil carbon sink in Mediterranean, Alpine, North eastern, South eastern and Eastern regions under specific warming level (SWL) of 1.5 and 2 °C relative to pre-industrial climate. However, this carbon sink is found to saturate, and gradually turn to a carbon source at warming level reaching 3.5 °C. This study provides a European-wide assessment of the future changes in productivity and phenology of grassland, and their consequences for the management intensity and the carbon

Precipitation-productivity Relation in Grassland in Northern China: Investigations at Multiple Spatiotemporal Scales

NASA Astrophysics Data System (ADS)

Hu, Z.

2017-12-01

Climate change is predicted to cause dramatic variability in precipitation regime, not only in terms of change in annual precipitation amount, but also in precipitation seasonal distribution and precipitation event characteristics (high frenquency extrem precipitation, larger but fewer precipitation events), which combined to influence productivity of grassland in arid and semiarid regions. In this study, combining remote sensing products with in-situ measurements of aboveground net primary productivity (ANPP) and gross primary productivity (GPP) data from eddy covariance system in grassland of northern China, we quantified the effects of spatio-temporal vairation in precipitation on productivity from local sites to region scale. We found that, for an individual precipitation event, the duration of GPP-response to the individual precipitation event and the maximum absolute GPP response induced by the individual precipitation event increased linearly with the size of precipitation events. Comparison of the productivity-precipitation relationships between multi-sites determined that the predominant characteristics of precipitation events (PEC) that affected GPP differed remarkably between the water-limited temperate steppe and the temperature-limited alpine meadow. The number of heavy precipitation events (>10 mm d-1) was the most important PEC to impact GPP in the temperate steppe through affecting soil moisture at different soil profiles, while precipitation interval was the factor that affected GPP most in the alpine meadow via its effects on temperature. At the region scale, shape of ANPP-precipitation relationship varies with distinct spatial scales, and besides annual precipitation, precipitation seasonal distribution also has comparable impacts on spatial variation in ANPP. Temporal variability in ANPP was lower at both the dry and wet end, and peaked at a precipitation of 243.1±3.5mm, which is the transition region between typical steppe and desert steppe

Grassland ecology and diversity (Ecologia y diversidad de pastizales)

Treesearch

Laurie B. Abbott

2006-01-01

Grasslands of the Chihuahuan Desert region are ecologically and economically important. These grasslands are valued for their rangeland, wildlife, watershed, and recreation resources. Biological diversity also raises the value of grassland communities. The potential for multiple uses within the region increases as the diversity of the resource base increases. In order...

The role of grasslands in food security and climate change.

PubMed

O'Mara, F P

2012-11-01

Grasslands are a major part of the global ecosystem, covering 37 % of the earth's terrestrial area. For a variety of reasons, mostly related to overgrazing and the resulting problems of soil erosion and weed encroachment, many of the world's natural grasslands are in poor condition and showing signs of degradation. This review examines their contribution to global food supply and to combating climate change. Grasslands make a significant contribution to food security through providing part of the feed requirements of ruminants used for meat and milk production. Globally, this is more important in food energy terms than pig meat and poultry meat. Grasslands are considered to have the potential to play a key role in greenhouse gas mitigation, particularly in terms of global carbon storage and further carbon sequestration. It is estimated that grazing land management and pasture improvement (e.g. through managing grazing intensity, improved productivity, etc) have a global technical mitigation potential of almost 1·5 Gt CO(2) equivalent in 2030, with additional mitigation possible from restoration of degraded lands. Milk and meat production from grassland systems in temperate regions has similar emissions of carbon dioxide per kilogram of product as mixed farming systems in temperate regions, and, if carbon sinks in grasslands are taken into account, grassland-based production systems can be as efficient as high-input systems from a greenhouse gas perspective. Grasslands are important for global food supply, contributing to ruminant milk and meat production. Extra food will need to come from the world's existing agricultural land base (including grasslands) as the total area of agricultural land has remained static since 1991. Ruminants are efficient converters of grass into humanly edible energy and protein and grassland-based food production can produce food with a comparable carbon footprint as mixed systems. Grasslands are a very important store of carbon, and

Does Evapotranspiration Increase When Forests are converted to Grasslands?

NASA Astrophysics Data System (ADS)

Varcoe, Robert; Sterling, Shannon

2017-04-01

The conversion of forests to grasslands (FGC) is a widespread land cover change (LCC) and is also among the most commonly studied changes with respect to its impact on ET; such research employs a variety of experimental approaches, including, paired catchment (PC), Budyko and land surface models (LSM), and measurement methods, including the catchment water balance (CWB), eddy covariance (EC) and remote sensing (RS). Until recently, there has been consensus in the scientific literature that rates of ET decrease when a forest is converted to grassland; however, this consensus has recently come into question. Williams (2012) applied the Budyko framework to a global network of eddy covariance measurements with the results that grasslands have a 9% greater evaporative index than forests. In addition, HadGEM2, a recent Hadley Centre LSM, produced increased ET in the northern Amazon Basin after simulating global scale tropical deforestation (Brovkin et al., 2015). Here we present an analysis of available estimates of how ET rates change with FGC to increase our understanding of the forest - grassland-ET paradigm. We used two datasets to investigate the impacts land cover change on ET. I compiled a dataset of change in ET with land cover change (ΔETLCC) using published experiments that compare forest and grassland ET under conditions controlled for meteorological and landscape influences. Using the ΔETLCC dataset, we show that, in all cases, forest ET is higher than grassland under controlled conditions. Results suggest that the eddy covariance method measures smaller changes in ET when forests are converted to grasslands, though more data are needed for this result to be statistically significant. Finally, GETA2.0, a new global dataset of annual ET, projects that forest ET is greater than grassland, except at high latitudes and areas where orography influences precipitation (P). The data included in this study represent the data available on forest and grassland ET

Effects of resource addition on recovery of production and plant functional composition in degraded semiarid grasslands.

PubMed

Chen, Qing; Hooper, David U; Li, Hui; Gong, Xiao Ying; Peng, Fei; Wang, Hong; Dittert, Klaus; Lin, Shan

2017-05-01

Degradation of semiarid ecosystems from overgrazing threatens a variety of ecosystem services. Rainfall and nitrogen commonly co-limit production in semiarid grassland ecosystems; however, few studies have reported how interactive effects of precipitation and nitrogen addition influence the recovery of grasslands degraded by overgrazing. We conducted a 6-year experiment manipulating precipitation (natural precipitation and simulated wet year precipitation) and nitrogen (0, 25 and 50 kg N ha -1 ) addition at two sites with different histories of livestock grazing (moderately and heavily grazed) in Inner Mongolian steppe. Our results suggest that recovery of plant community composition and recovery of production can be decoupled. Perennial grasses provide long-term stability of high-quality forage production in this system. Supplemental water combined with exclosures led, in the heavily grazed site, to the strongest recovery of perennial grasses, although widespread irrigation of rangeland is not a feasible management strategy in many semiarid and arid regions. N fertilization combined with exclosures, but without water addition, increased dominance of unpalatable annual species, which in turn retarded growth of perennial species and increased inter-annual variation in primary production at both sites. Alleviation of grazing pressure alone allowed recovery of desired perennial species via successional processes in the heavily grazed site. Our experiments suggest that recovery of primary production and desirable community composition are not necessarily correlated. The use of N fertilization for the management of overgrazed grassland needs careful and systematic evaluation, as it has potential to impede, rather than aid, recovery.

Evaluation of semiarid grassland degradation in North China from multiple perspectives

NASA Astrophysics Data System (ADS)

Han, D.; Wang, G.; Xue, B. L.; Xu, X.

2017-12-01

There has been increasing interest in grassland ecosystem degradation resulting from intensive human activity and climate change, especially in arid and semiarid regions. Species composition, grassland desertification, and aboveground biomass (AGB) are used as indicators of grassland degradation in this study. We comprehensively analyzed variations in these three indicators in semiarid grassland in North China, on multiple time scales, based on MODIS products and field sampling datasets. Since 1984, species composition has become simpler and species indicative of grassland degradation, such as Potentilla acaulis and Artemisia frigida, have become dominant. These changes indicate that serious grassland degradation has occurred since 1984. Grassland degradation was also analyzed on shorter time scales. Analyses of interannual variations during 2005-2015 showed that desertification decreased and average AGB in the growth season increased over the study area, indicating that grassland was recovering. Analyses of spatial variations showed that the position of slightly desertified grassland shifted and formed a band in the west, where the lowest AGB in the growth season was recorded but tendency ratio of AGB increased from 2005 to 2015. Climatic factors had critical effects on grassland degradation, as identified by the three indicators on different time scales. The simpler species composition resulted from the increase in average temperature and decrease in average precipitation over the past 30 years. For nearly a decade, an increase in precipitation and decreases in temperature and potential evapotranspiration reduced desertification and increased AGB in the growth season overall. Consequently, there has distinct difference in grassland degradation between analysis results on above two time scales, indicating multiple perspectives should be considered to accurately assess the state and characteristics of grassland degradation.

Biocrusts modulate warming and rainfall exclusion effects on soil respiration in a semi-arid grassland

PubMed Central

Escolar, Cristina; Maestre, Fernando T.; Rey, Ana

2015-01-01

Soil surface communities composed of cyanobacteria, algae, mosses, liverworts, fungi, bacteria and lichens (biocrusts) largely affect soil respiration in dryland ecosystems. Climate change is expected to have large effects on biocrusts and associated ecosystem processes. However, few studies so far have experimentally assessed how expected changes in temperature and rainfall will affect soil respiration in biocrust-dominated ecosystems. We evaluated the impacts of biocrust development, increased air temperature and decreased precipitation on soil respiration dynamics during dry (2009) and wet (2010) years, and investigated the relative importance of soil temperature and moisture as environmental drivers of soil respiration, in a semiarid grassland from central Spain. Soil respiration rates were significantly lower in the dry than during the wet year, regardless of biocrust cover. Warming increased soil respiration rates, but this response was only significant in biocrust-dominated areas (> 50% biocrust cover). Warming also increased the temperature sensitivity (Q10 values) of soil respiration in biocrust-dominated areas, particularly during the wet year. The combination of warming and rainfall exclusion had similar effects in low biocrust cover areas. Our results highlight the importance of biocrusts as a modulator of soil respiration responses to both warming and rainfall exclusion, and indicate that they must be explicitly considered when evaluating soil respiration responses to climate change in drylands. PMID:25914428

Dynamic of grassland vegetation degradation and its quantitative assessment in the northwest China

NASA Astrophysics Data System (ADS)

Zhou, Wei; Gang, Chengcheng; Zhou, Liang; Chen, Yizhao; Li, Jianlong; Ju, Weimin; Odeh, Inakwu

2014-02-01

Grasslands, one of the most widespread land cover types in China, are of great importance to natural environmental protection and socioeconomic development. An accurate quantitative assessment of the effects of inter-annual climate change and human activities on grassland productivity has great theoretical significance to understanding the driving mechanisms of grassland degradation. Net primary productivity (NPP) was selected as an indicator for analyzing grassland vegetation dynamics from 2001 to 2010. Potential NPP and the difference between potential NPP and actual NPP were used to represent the effects of climate and human factors, respectively, on grassland degradation. The results showed that 61.49% of grassland areas underwent degradation, whereas only 38.51% exhibited restoration. In addition, 65.75% of grassland degradation was caused by human activities whereas 19.94% was caused by inter-annual climate change. By contrast, 32.32% of grassland restoration was caused by human activities, whereas 56.56% was caused by climatic factors. Therefore, inter-annual climate change is the primary cause of grassland restoration, whereas human activities are the primary cause of grassland degradation. Grassland dynamics and the relative roles of climate and human factors in grassland degradation and restoration varied greatly across the five provinces studied. The contribution of human activities to grassland degradation was greater than that of climate change in all five provinces. Three outcomes were observed in grassland restoration: First, the contribution of climate to grassland restoration was greater than that of human activities, particularly in Qinghai, Inner Mongolia, and Xinjiang. Second, the contribution of human activities to grassland restoration was greater than that of climate in Gansu. Third, the two factors almost equally contributed to grassland restoration in Tibet. Therefore, the effectiveness of ecological restoration programs should be enhanced

Reforestation or conservation? The attributes of old growth grasslands in South Africa

PubMed Central

Zaloumis, Nicholas P.

2016-01-01

Deforestation as a result of burning and land conversion in the tropics and subtropics has been widely studied and active restoration of forests has been widely promoted. Besides other benefits, reforestation can sequester carbon thereby reducing CO2 emissions to the atmosphere. However, before grasslands are targeted for ‘reforestation', it is necessary to distinguish whether they are ancient natural grasslands or secondary vegetation colonizing deforested areas. Here we report the results of a study comparing primary grasslands in South Africa with 4–40 year old secondary grasslands recovering from afforestation with Pinus species. Primary grasslands had significantly higher plant species richness overall, especially of forb species. Ground cover of primary grasslands was more evenly distributed among species than secondary grasslands which tended to mono-dominance. Forbs with underground storage organs (USOs) were common in primary grasslands but conspicuously absent in the recovering systems. Comparison of secondary grasslands of different ages (up to 40 years) showed negligible recovery of the original species composition. Three key features distinguish old growth primary from secondary grasslands: total and forb species numbers, evenness of species contributions to cover and the presence of USOs. Old growth grasslands also differed in their fire response, showing significant post-burn resprouting and fire-stimulated flowering in contrast to secondary grasslands. Though similar contrasting attributes of ancient and secondary grasslands have been reported in South America, more studies are needed to explore their generality in other geographical regions. This article is part of the themed issue ‘Tropical grassy biomes: linking ecology, human use and conservation’. PMID:27502375

Effects of exotic grasses on soil seed banks in Southeastern Arizona grasslands

USGS Publications Warehouse

McLaughlin, S.P.; Bowers, Janice E.

2007-01-01

At the Appleton-Whittell Research Ranch, an ungrazed grassland preserve in southeastern Arizona, soil seed banks were sampled in June, August, and October 2002 and June 2003. Wildfire had previously burned 90% of the research ranch in May 2002. Seed density and species richness in burned native grassland (2 plots) were compared to those in burned exotic grassland (2 plots). Averaged over 4 sample dates, seed densities were as follows: burned native grassland, 591 ?? 243.1 seeds??m-2 and 784 ?? 334.9 seeds??m-2; burned exotic grassland, 501 ?? 198.9 seeds??m-2 and 196 ?? 123.8 seeds??m-2. Species richness in the seed bank, also averaged over 4 sample dates, was as follows: burned native grassland, 16.3 ?? 1.7 species??m -2 and 19.5 ?? 1.0 species??m-2; burned exotic grassland, 12.0 ?? 3.4 species??m-2 and 11.06 ?? 2.5 species??m-2. The seed bank of burned exotic grassland contained significantly fewer seeds and species than that of burned native grassland. In addition, the seed bank in burned exotic grassland comprised mainly exotic grasses, whereas annual and perennial herbs, most of them native, dominated the seed bank of burned native grassland. Of the 50 species detected in soil samples, only 20 had a persistent seed bank, and only 1 of these was a native perennial bunchgrass. The preponderance of transient species means that eradication of exotic grasses must be followed by reseeding of native grasses and herbs, perhaps repeatedly, if native grassland is to replace exotic grassland.

Stable carbon isotope as a signal index for monitoring grassland degradation

NASA Astrophysics Data System (ADS)

Yao, Hongyun; Wilkes, Andreas; Zhu, Guodong; Zhang, Hongdan; Liu, Xiaojuan; Dan Ding; Zhai, Xiajie; Tang, Shiming; Chen, Qing; Zhang, Yujuan; Huang, Ding; Wang, Chengjie

2016-08-01

Grassland degradation due to overgrazing is common in many areas of the world. This study analyzed the potential of the stable carbon isotope (δ13C) value as a structural microcosmic index to monitor processes of grassland degradation. The δ13C values of plant leaves, roots and soils in non-grazed (NG) and over-grazed (OG) grassland were measured from samples collected from the seven types of grassland in China. We found that the leaf δ13C values of palatable species (δ13Cleaf) and root δ13C values (δ13Croot) in OG grasslands were reduced compared with those from NG grasslands. Furthermore, the δ13Cleaf and δ13Csoil were positive correlation with elevation and latitude, δ13Croot was negative correlation with them at high altitude (3000~5000m), and δ13Croot and δ13Csoil were negative correlation with them at low altitude (0~2000m), respectively. Consequently, tracing of the δ13C variations in grassland ecosystem can provide a powerful tool to evaluate the degree of grassland degradation.

Stable carbon isotope as a signal index for monitoring grassland degradation.

PubMed

Yao, Hongyun; Wilkes, Andreas; Zhu, Guodong; Zhang, Hongdan; Liu, Xiaojuan; Dan Ding; Zhai, Xiajie; Tang, Shiming; Chen, Qing; Zhang, Yujuan; Huang, Ding; Wang, Chengjie

2016-08-16

Grassland degradation due to overgrazing is common in many areas of the world. This study analyzed the potential of the stable carbon isotope (δ(13)C) value as a structural microcosmic index to monitor processes of grassland degradation. The δ(13)C values of plant leaves, roots and soils in non-grazed (NG) and over-grazed (OG) grassland were measured from samples collected from the seven types of grassland in China. We found that the leaf δ(13)C values of palatable species (δ(13)Cleaf) and root δ(13)C values (δ(13)Croot) in OG grasslands were reduced compared with those from NG grasslands. Furthermore, the δ(13)Cleaf and δ(13)Csoil were positive correlation with elevation and latitude, δ(13)Croot was negative correlation with them at high altitude (3000~5000m), and δ(13)Croot and δ(13)Csoil were negative correlation with them at low altitude (0~2000m), respectively. Consequently, tracing of the δ(13)C variations in grassland ecosystem can provide a powerful tool to evaluate the degree of grassland degradation.

Stable carbon isotope as a signal index for monitoring grassland degradation

PubMed Central

Yao, Hongyun; Wilkes, Andreas; Zhu, Guodong; Zhang, Hongdan; Liu, Xiaojuan; Dan Ding; Zhai, Xiajie; Tang, Shiming; Chen, Qing; Zhang, Yujuan; Huang, Ding; Wang, Chengjie

2016-01-01

Grassland degradation due to overgrazing is common in many areas of the world. This study analyzed the potential of the stable carbon isotope (δ13C) value as a structural microcosmic index to monitor processes of grassland degradation. The δ13C values of plant leaves, roots and soils in non-grazed (NG) and over-grazed (OG) grassland were measured from samples collected from the seven types of grassland in China. We found that the leaf δ13C values of palatable species (δ13Cleaf) and root δ13C values (δ13Croot) in OG grasslands were reduced compared with those from NG grasslands. Furthermore, the δ13Cleaf and δ13Csoil were positive correlation with elevation and latitude, δ13Croot was negative correlation with them at high altitude (3000~5000m), and δ13Croot and δ13Csoil were negative correlation with them at low altitude (0~2000m), respectively. Consequently, tracing of the δ13C variations in grassland ecosystem can provide a powerful tool to evaluate the degree of grassland degradation. PMID:27527910

The role of grasslands in food security and climate change

PubMed Central

O'Mara, F. P.

2012-01-01

Background Grasslands are a major part of the global ecosystem, covering 37 % of the earth's terrestrial area. For a variety of reasons, mostly related to overgrazing and the resulting problems of soil erosion and weed encroachment, many of the world's natural grasslands are in poor condition and showing signs of degradation. This review examines their contribution to global food supply and to combating climate change. Scope Grasslands make a significant contribution to food security through providing part of the feed requirements of ruminants used for meat and milk production. Globally, this is more important in food energy terms than pig meat and poultry meat. Grasslands are considered to have the potential to play a key role in greenhouse gas mitigation, particularly in terms of global carbon storage and further carbon sequestration. It is estimated that grazing land management and pasture improvement (e.g. through managing grazing intensity, improved productivity, etc) have a global technical mitigation potential of almost 1·5 Gt CO2 equivalent in 2030, with additional mitigation possible from restoration of degraded lands. Milk and meat production from grassland systems in temperate regions has similar emissions of carbon dioxide per kilogram of product as mixed farming systems in temperate regions, and, if carbon sinks in grasslands are taken into account, grassland-based production systems can be as efficient as high-input systems from a greenhouse gas perspective. Conclusions Grasslands are important for global food supply, contributing to ruminant milk and meat production. Extra food will need to come from the world's existing agricultural land base (including grasslands) as the total area of agricultural land has remained static since 1991. Ruminants are efficient converters of grass into humanly edible energy and protein and grassland-based food production can produce food with a comparable carbon footprint as mixed systems. Grasslands are a very

AmeriFlux US-SRG Santa Rita Grassland

DOE Data Explorer

Scott, Russell [United States Department of Agriculture

2016-01-01

This is the AmeriFlux version of the carbon flux data for the site US-SRG Santa Rita Grassland. Site Description - Semidesert C4 grassland, lies in Pasture 1 on the Santa Rita Experimental Range. This is the companion site for US-SRM, but has much less mesquite encroachment.

Missouri's Approach to Grassland Bird Conservation Planning

Treesearch

Brad Jacobs

2005-01-01

Missouri?s state and federal agencies, nongovernmental organizations and citizens have a partnership called the Grasslands Coalition. The Grasslands Coalition was established to help preserve remaining tallgrass prairie. This includes applying a management regime that enhances natural functions and interactions. The coalition is a state-based effort co-sponsored by...

Desert grassland and shrubland ecosystems [chapter 5

Treesearch

Samuel R. Loftin; Richard Agllilar; Alice L. Chung-MacCoubrey; Wayne A. Robbie

1995-01-01

The productivity, stability, and health of the Middle Rio Grande Basin, arid and semiarid grassland and shrub land ecosystems depend upon complex interactions. These relationships occur between factors such as climate, domestic livestock, and wildlife use, and human activities such as urban development, agriculture, and recreation. These grassland/ shrub land...

Historic and Current Conditions of Southwestern Grasslands

Treesearch

Reggie Fletcher; Wayne A. Robbie

2004-01-01

Southwestern grasslands today share general differences from their pre-Euro-American settlement conditions. With few exceptions, grasslands--whether in the desert, prairie, or mountains--were, prior to non-Indian settlement, more diverse in plant and animal species composition, more productive, more resilient, and better able to absorb the impact of disturbances....

Grazing effects on carbon fluxes in a northern China grassland

USDA-ARS?s Scientific Manuscript database

Grazing is a widespread use of grasslands in northern China, but if stocking rate exceeds grassland carrying capacity, degradation and desertification can occur. As a result, grazing management is critical and can play a significant role in driving C sink and source activity in grassland ecosystems...

Quantification of Microbial Osmolytes in a Drought Impacted California Grassland

NASA Astrophysics Data System (ADS)

Boot, C. M.; Schaeffer, S. M.; Doyle, A. P.; Schimel, J. P.

2008-12-01

With drought frequency and severity likely increasing in the future, understanding its effect on terrestrial carbon (C) and nitrogen (N) cycling has become essential for accurately modeling ecosystem responses to climate change. Microbes respond to drought stress by accumulating internal solutes, or osmolytes, such as amino acids, betaines and polyols, to balance cell membrane water potential as the soil dries. However, when seasonal rains arrive, internal solutes are released and rapidly mineralized. We have been studying these processes in a California grassland. Beginning in summer 2007, we made monthly measurements of soil moisture, individual amino acid concentration in total soil and in microbial biomass, total dissolved organic carbon and nitrogen (DOC and DON), and microbial biomass carbon and nitrogen (MBC and MBN). We expected microbial concentrations of the known amino acid osmolytes glutamate (glu) and proline (pro) to fluctuate inversely with soil moisture. However, pro was only recovered in Mar 2008 (0.30 μg C g-1 dry soil) and the glu concentration varied proportionally with soil moisture: lowest during summer (0.06 g H2O g-1 dry soil, 2.22 μg glutamate-C g-1 dry soil) and highest in winter (0.27 g H2O g-1 dry soil, 4.43 μg glutamate-C g-1 dry soil). The trend from DOC, MBC, and DON measurements was opposite, however, with all concentrations decreasing as soil moisture shifted from dry to wet, (DOC: 64.61 to 32.49 μg C g-1 dry soil respectively). MBN was the exception to this trend, with concentrations staying nearly constant across seasons. These patterns suggest that the expected amino acids glu and pro are not being used for microbial osmoregulation in the CA grassland, and given the summer to winter decrease in MBC, the primary osmolyte source is likely to be either polyol-type compounds such as mannitol or betaines. The implications for terrestrial carbon cycle are considerable because as the frequency of drought increases, the accumulation

Carbon, Nitrogen, and Phosphorus Increase in Soil Physical Fractions Following Vegetation Change from Grassland to Woodland

NASA Astrophysics Data System (ADS)

Kantola, I. B.; Boutton, T. W.; Filley, T. R.; Hallmark, C. T.

2009-12-01

Woody plant encroachment has been pervasive in grass-dominated ecosystems around the world during the past century due to livestock grazing, fire suppression, and/or changes in climate and atmospheric chemistry. In the Rio Grande Plains of Texas, subtropical thorn woodlands dominated by N-fixing tree legumes have largely replaced grasslands. This dramatic land cover change has increased above- and belowground primary productivity and accelerated rates of biogeochemical processes in the soil. The purpose of this study was to assess the impact of this grassland to woodland transition on C, N, and P concentrations in soil physical fractions that differ in turnover rates. Soil samples (0-10 cm) were collected in remnant grasslands and near the centers of woody plant clusters ranging in age from 15 to 90 yrs in a subtropical savanna parkland in southern Texas. Soils were fractionated by wet sieving into five size and density classes: un-sieved whole soil, free light fraction (density <1 g/cm3), macroaggregates (>250 µm), microaggregates (53-250 µm), and free silt and clay (<53 µm). C and N concentrations in each of the fractions were determined by elemental analysis, and total P concentrations were determined by alkaline oxidation and sulfuric acid digestion coupled with ascorbic acid colorimetry. C, N, and P concentrations in whole soil were 2-3X greater in woody clusters than in grasslands. In addition, C, N, and P concentrations all increased linearly with time following woody plant invasion in all fractions except free silt and clay. Most of the newly accrued C, N, and P was in the relatively more labile light fractions and macroaggregates. C:P and N:P ratios increased following woody encroachment, indicating carbon and nitrogen accumulated at a faster rate than phosphorus. Since N and P are generally the most limiting nutrients in terrestrial ecosystems, increased stores of these elements are likely to alter rates of microbial processes, plant-microbe and plant

Application of Multi-Source Remote Sensing Image in Yunnan Province Grassland Resources Investigation

NASA Astrophysics Data System (ADS)

Li, J.; Wen, G.; Li, D.

2018-04-01

Trough mastering background information of Yunnan province grassland resources utilization and ecological conditions to improves grassland elaborating management capacity, it carried out grassland resource investigation work by Yunnan province agriculture department in 2017. The traditional grassland resource investigation method is ground based investigation, which is time-consuming and inefficient, especially not suitable for large scale and hard-to-reach areas. While remote sensing is low cost, wide range and efficient, which can reflect grassland resources present situation objectively. It has become indispensable grassland monitoring technology and data sources and it has got more and more recognition and application in grassland resources monitoring research. This paper researches application of multi-source remote sensing image in Yunnan province grassland resources investigation. First of all, it extracts grassland resources thematic information and conducts field investigation through BJ-2 high space resolution image segmentation. Secondly, it classifies grassland types and evaluates grassland degradation degree through high resolution characteristics of Landsat 8 image. Thirdly, it obtained grass yield model and quality classification through high resolution and wide scanning width characteristics of MODIS images and sample investigate data. Finally, it performs grassland field qualitative analysis through UAV remote sensing image. According to project area implementation, it proves that multi-source remote sensing data can be applied to the grassland resources investigation in Yunnan province and it is indispensable method.

Hijama therapy (wet cupping) - its potential use to complement British healthcare in practice, understanding, evidence and regulation.

PubMed

Sajid, Mohammed Imran

2016-05-01

Wet cupping was used in the nineteenth century for treatment of patients in the United Kingdom (UK) by a few experienced practitioners. Revival Hijama use by practitioners in the UK in recent years has been observed as well as interest from the public, with developments of specific certified training programmes, established businesses providing tailored Hijama therapy Clinical Waste disposal services, provisions of insurance cover, involvement of medical professionals and membership with the General Regulatory Council for Complementary Therapies (GRCCT). However, there has also been noted that there is not much in the way of guidance or regulation. Therefore, we would like to initiate some communication and understanding of Hijama (wet cupping) to benefit medical professionals, discussing recent research undertaken as a basis for potentially more in the future (evidence-based practice), in the likely event that a patient might request to be referred for this therapy during a consultation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Grazing-induced BVOC fluxes from a managed grassland

NASA Astrophysics Data System (ADS)

Mozaffar, Ahsan; Schoon, Niels; Bachy, Aurelie; Digrado, Anthony; Heinesch, Bernard; Aubinet, Marc; Fauconnier, Marie-laure; Delaplace, Pierre; Dujardin, Patrick; Amelynck, Crist

2017-04-01

Grassland ecosystems cover one fourth of the Earth's land surface and are both sources and sinks of Biogenic Volatile Organic Compounds (BVOCs) which play an important role in atmospheric chemistry and air pollution. The use of grassland for cattle breeding is a common practice in many parts of the world. As it has been widely demonstrated that plants emit large bursts of BVOCs when they are mechanically damaged, grass tearing and trampling during grazing are expected to induce large BVOC emissions as well. Nevertheless, to the best of our knowledge, no study has been performed on BVOC fluxes from grazed grassland yet. Therefore investigations were performed using automated dynamic chambers in a managed grassland in Belgium over the 2015 and 2016 growing season. BVOC fluxes, together with carbon dioxide (CO2) and water vapor (H2O) fluxes from grazed and undisturbed grassland were followed simultaneously using PTR-MS (Proton Transfer Reaction-Mass Spectrometry) and a LI-840 non-dispersive IR gas analyzer. In addition, air in the chamber was sampled occasionally for GC-MS (Gas Chromatography-Mass Spectrometry) analysis to assist compound identification. Significant differences between grazed and undisturbed grassland patches were observed in terms of BVOC, CO2 and H2O vapor fluxes. Grazing by cows was found to result in enhanced emissions of several BVOCs such as methanol, acetaldehyde, acetone, acetic acid and Green Leaf Volatiles (GLVs), and induced BVOC emissions generally lasted for around 5 days following a grazing event. Quantitative data on the impact of grazing on BVOC, CO2 and H2O exchange between grassland and the atmosphere will be presented, and correlations between BVOC fluxes and environmental conditions will be discussed.

Exacerbated grassland degradation and desertification in Central Asia during 2000-2014.

PubMed

Zhang, Geli; Biradar, Chandrashekhar M; Xiao, Xiangming; Dong, Jinwei; Zhou, Yuting; Qin, Yuanwei; Zhang, Yao; Liu, Fang; Ding, Mingjun; Thomas, Richard J

2018-03-01

Grassland degradation and desertification is a complex process, including both state conversion (e.g., grasslands to deserts) and gradual within-state change (e.g., greenness dynamics). Existing studies hardly separated the two components and analyzed it as a whole based on time series vegetation index data, which cannot provide a clear and comprehensive picture for grassland degradation and desertification. Here we propose an integrated assessment strategy, by considering both state conversion and within-state change of grasslands, to investigate grassland degradation and desertification process in Central Asia. First, annual maps of grasslands and sparsely vegetated land were generated to track the state conversions between them. The results showed increasing grasslands were converted to sparsely vegetated lands from 2000 to 2014, with the desertification region concentrating in the latitude range of 43-48° N. A frequency analysis of grassland vs. sparsely vegetated land classification in the last 15 yr allowed a recognition of persistent desert zone (PDZ), persistent grassland zone (PGZ), and transitional zone (TZ). The TZ was identified in southern Kazakhstan as one hotspot that was unstable and vulnerable to desertification. Furthermore, the trend analysis of Enhanced Vegetation Index during thermal growing season (EVI TGS ) was investigated in individual zones using linear regression and Mann-Kendall approaches. An overall degradation across the area was found; moreover, the second desertification hotspot was identified in northern Kazakhstan with significant decreasing in EVI TGS , which was located in PGZ. Finally, attribution analyses of grassland degradation and desertification were conducted by considering precipitation, temperature, and three different drought indices. We found persistent droughts were the main factor for grassland degradation and desertification in Central Asia. Considering both state conversion and gradual within-state change

Tropical grasslands: A pivotal place for a more multi-functional agriculture.

PubMed

Boval, Maryline; Angeon, Valérie; Rudel, Tom

2017-02-01

Tropical grasslands represent a pivotal arena for the sustainable intensification of agriculture in the coming decades. The abundant ecosystem services provided by the grasslands, coupled with the aversion to further forest destruction, makes sustainable intensification of tropical grasslands a high policy priority. In this article, we provide an inventory of agricultural initiatives that would contribute to the sustainable intensification of the tropical grassland agro-ecosystem, and we recommend a shift in the scientific priorities of animal scientists that would contribute to realization of a more agro-ecological and multi-functional agriculture in the world's tropical grasslands.

Climatic change controls productivity variation in global grasslands

PubMed Central

Gao, Qingzhu; Zhu, Wenquan; Schwartz, Mark W.; Ganjurjav, Hasbagan; Wan, Yunfan; Qin, Xiaobo; Ma, Xin; Williamson, Matthew A.; Li, Yue

2016-01-01

Detection and identification of the impacts of climate change on ecosystems have been core issues in climate change research in recent years. In this study, we compared average annual values of the normalized difference vegetation index (NDVI) with theoretical net primary productivity (NPP) values based on temperature and precipitation to determine the effect of historic climate change on global grassland productivity from 1982 to 2011. Comparison of trends in actual productivity (NDVI) with climate-induced potential productivity showed that the trends in average productivity in nearly 40% of global grassland areas have been significantly affected by climate change. The contribution of climate change to variability in grassland productivity was 15.2–71.2% during 1982–2011. Climate change contributed significantly to long-term trends in grassland productivity mainly in North America, central Eurasia, central Africa, and Oceania; these regions will be more sensitive to future climate change impacts. The impacts of climate change on variability in grassland productivity were greater in the Western Hemisphere than the Eastern Hemisphere. Confirmation of the observed trends requires long-term controlled experiments and multi-model ensembles to reduce uncertainties and explain mechanisms. PMID:27243565

Grassland bird densities in seral stages of mixed-grass prairie

Treesearch

Shawn C. Fritcher; Mark A. Rumble; Lester D. Flake

2004-01-01

Birds associated with prairie ecosystems are declining and the ecological condition (seral stage) of remaining grassland communities may be a factor. Livestock grazing intensity influences the seral stage of grassland communities and resource managers lack information to assess how grassland birds are affected by these changes. We estimated bird density, species...

Innovative grassland management systems for environmental and livelihood benefits

PubMed Central

Kemp, David R.; Guodong, Han; Xiangyang, Hou; Michalk, David L.; Fujiang, Hou; Jianping, Wu; Yingjun, Zhang

2013-01-01

Grasslands occupy 40% of the world’s land surface (excluding Antarctica and Greenland) and support diverse groups, from traditional extensive nomadic to intense livestock-production systems. Population pressures mean that many of these grasslands are in a degraded state, particularly in less-productive areas of developing countries, affecting not only productivity but also vital environmental services such as hydrology, biodiversity, and carbon cycles; livestock condition is often poor and household incomes are at or below poverty levels. The challenge is to optimize management practices that result in “win-win” outcomes for grasslands, the environment, and households. A case study is discussed from northwestern China, where it has been possible to reduce animal numbers considerably by using an energy-balance/market-based approach while improving household incomes, providing conditions within which grassland recovery is possible. This bottom-up approach was supported by informing and working with the six layers of government in China to build appropriate policies. Further policy implications are considered. Additional gains in grassland rehabilitation could be fostered through targeted environmental payment schemes. Other aspects of the livestock production system that can be modified are discussed. This work built a strategy that has implications for many other grassland areas around the world where common problems apply. PMID:23671092

Innovative grassland management systems for environmental and livelihood benefits.

PubMed

Kemp, David R; Guodong, Han; Xiangyang, Hou; Michalk, David L; Fujiang, Hou; Jianping, Wu; Yingjun, Zhang

2013-05-21

Grasslands occupy 40% of the world's land surface (excluding Antarctica and Greenland) and support diverse groups, from traditional extensive nomadic to intense livestock-production systems. Population pressures mean that many of these grasslands are in a degraded state, particularly in less-productive areas of developing countries, affecting not only productivity but also vital environmental services such as hydrology, biodiversity, and carbon cycles; livestock condition is often poor and household incomes are at or below poverty levels. The challenge is to optimize management practices that result in "win-win" outcomes for grasslands, the environment, and households. A case study is discussed from northwestern China, where it has been possible to reduce animal numbers considerably by using an energy-balance/market-based approach while improving household incomes, providing conditions within which grassland recovery is possible. This bottom-up approach was supported by informing and working with the six layers of government in China to build appropriate policies. Further policy implications are considered. Additional gains in grassland rehabilitation could be fostered through targeted environmental payment schemes. Other aspects of the livestock production system that can be modified are discussed. This work built a strategy that has implications for many other grassland areas around the world where common problems apply.

Madagascar's grasses and grasslands: anthropogenic or natural?

PubMed Central

Besnard, Guillaume; Forest, Félix; Malakasi, Panagiota; Moat, Justin; Clayton, W. Derek; Ficinski, Paweł; Savva, George M.; Nanjarisoa, Olinirina P.; Razanatsoa, Jacqueline; Randriatsara, Fetra O.; Kimeu, John M.; Luke, W. R. Quentin; Kayombo, Canisius; Linder, H. Peter

2016-01-01

Grasses, by their high productivity even under very low pCO2, their ability to survive repeated burning and to tolerate long dry seasons, have transformed the terrestrial biomes in the Neogene and Quaternary. The expansion of grasslands at the cost of biodiverse forest biomes in Madagascar is often postulated as a consequence of the Holocene settlement of the island by humans. However, we show that the Malagasy grass flora has many indications of being ancient with a long local evolutionary history, much predating the Holocene arrival of humans. First, the level of endemism in the Madagascar grass flora is well above the global average for large islands. Second, a survey of many of the more diverse areas indicates that there is a very high spatial and ecological turnover in the grass flora, indicating a high degree of niche specialization. We also find some evidence that there are both recently disturbed and natural stable grasslands: phylogenetic community assembly indicates that recently severely disturbed grasslands are phylogenetically clustered, whereas more undisturbed grasslands tend to be phylogenetically more evenly distributed. From this evidence, it is likely that grass communities existed in Madagascar long before human arrival and so were determined by climate, natural grazing and other natural factors. Humans introduced zebu cattle farming and increased fire frequency, and may have triggered an expansion of the grasslands. Grasses probably played the same role in the modification of the Malagasy environments as elsewhere in the tropics. PMID:26791612

Long-term resistance to simulated climate change in an infertile grassland.

PubMed

Grime, J Philip; Fridley, Jason D; Askew, Andrew P; Thompson, Ken; Hodgson, John G; Bennett, Chris R

2008-07-22

Climate shifts over this century are widely expected to alter the structure and functioning of temperate plant communities. However, long-term climate experiments in natural vegetation are rare and largely confined to systems with the capacity for rapid compositional change. In unproductive, grazed grassland at Buxton in northern England (U.K.), one of the longest running experimental manipulations of temperature and rainfall reveals vegetation highly resistant to climate shifts maintained over 13 yr. Here we document this resistance in the form of: (i) constancy in the relative abundance of growth forms and maintained dominance by long-lived, slow-growing grasses, sedges, and small forbs; (ii) immediate but minor shifts in the abundance of several species that have remained stable over the course of the experiment; (iii) no change in productivity in response to climate treatments with the exception of reduction from chronic summer drought; and (iv) only minor species losses in response to drought and winter heating. Overall, compositional changes induced by 13-yr exposure to climate regime change were less than short-term fluctuations in species abundances driven by interannual climate fluctuations. The lack of progressive compositional change, coupled with the long-term historical persistence of unproductive grasslands in northern England, suggests the community at Buxton possesses a stabilizing capacity that leads to long-term persistence of dominant species. Unproductive ecosystems provide a refuge for many threatened plants and animals and perform a diversity of ecosystem services. Our results support the view that changing land use and overexploitation rather than climate change per se constitute the primary threats to these fragile ecosystems.

Prevalence of wet litter and the associated risk factors in broiler flocks in the United Kingdom.

PubMed

Hermans, P G; Fradkin, D; Muchnik, I B; Organ, K L

2006-05-06

A postal questionnaire was sent to the managers of 857 broiler farms in the UK to determine the prevalence and risk factors for wet litter. The response rate was 75 per cent. Wet litter was reported by 75 per cent (95 per cent confidence interval [CI] 71.3 to 78.3) of the respondents in at least one flock during the year 2001 and 56.1 per cent (95 per cent CI 52.0 to 60.0) of them reported that they had an outbreak of wet litter in their most recently reared flock. Wet litter occurred more often during the winter months and farms using side ventilation systems were at an increased risk (odds ratio 1.74; 95 per cent CI 1.09 to 2.76). A multivariable analysis was carried out using two different definitions of wet litter as outcome variables - all cases of wet litter, and cases of wet litter associated with disease. Consistent risk factors for both outcomes were coccidiosis, feed equipment failures and the availability of separate farm clothing for each house. Cases of wet litter associated with disease were reported by 33.7 per cent (95 per cent CI 28.8 to 39.1) of the managers in their last flock and were associated with the use of hand sanitisers and broiler houses with walls made of concrete.

Effects of climate and water balance across grasslands of varying C3 and C4 grass cover

USGS Publications Warehouse

Witwicki, Dana L.; Munson, Seth M.; Thoma, David P.

2016-01-01

Climate change in grassland ecosystems may lead to divergent shifts in the abundance and distribution of C3 and C4 grasses. Many studies relate mean climate conditions over relatively long time periods to plant cover, but there is still much uncertainty about how the balance of C3and C4 species will be affected by climate at a finer temporal scale than season (individual events to months). We monitored cover at five grassland sites with co-dominant C3 and C4 grass species or only dominant C3 grass species for 6 yr in national parks across the Colorado Plateau region to assess the influence of specific months of climate and water balance on changes in grass cover. C4 grass cover increased and decreased to a larger degree than C3 grass cover with extremely dry and wet consecutive years, but this response varied by ecological site. Climate and water balance explained 10–49% of the inter-annual variability of cover of C3 and C4 grasses at all sites. High precipitation in the spring and in previous year monsoon storms influenced changes in cover of C4 grasses, with measures of water balance in the same months explaining additional variability. C3 grasses in grasslands where they were dominant were influenced primarily by longer periods of climate, while C3 grasses in grasslands where they were co-dominant with C4 grasses were influenced little by climate anomalies at either short or long periods of time. Our results suggest that future changes in spring and summer climate and water balance are likely to affect cover of both C3 and C4 grasses, but cover of C4 grasses may be affected more strongly, and the degree of change will depend on soils and topography where they are growing and the timing of the growing season.

Informing agricultural management - The challenge of modelling grassland phenology

NASA Astrophysics Data System (ADS)

Calanca, Pierluigi

2017-04-01

Grasslands represent roughly 70% of the agricultural land worldwide, are the backbone of animal husbandry and contribute substantially to agricultural income. At the farm scale a proper management of meadows and pastures is necessary to attain a balance between forage production and consumption. A good hold on grassland phenology is of paramount importance in this context, because forage quantity and quality critically depend on the developmental stage of the sward. Traditionally, empirical rules have been used to advise farmers in this respect. Yet the provision of supporting information for decision making would clearly benefit from dedicated tools that integrate reliable models of grassland phenology. As with annual crops, in process-based models grassland phenology is usually described as a linear function of so-called growing degree days, whereby data from field trials and monitoring networks are used to calibrate the relevant parameters. It is shown in this contribution that while the approach can provide reasonable estimates of key developmental stages in an average sense, it fails to account for the variability observed in managed grasslands across sites and years, in particular concerning the start of the growing season. The analysis rests on recent data from western Switzerland, which serve as a benchmark for simulations carried out with grassland models of increasing complexity. Reasons for an unsatisfactory model performance and possibilities to improve current models are discussed, including the necessity to better account for species composition, late season management decisions, as well as plant physiological processes taking place during the winter season. The need to compile existing, and collect new data doe managed grasslands is also stressed.

Quantifying the pedo-ecohydrological structure and function of degraded, grassland ecosystems

NASA Astrophysics Data System (ADS)

Brazier, Richard E.

2015-04-01

Grassland ecosystems cover significant areas of the terrestrial land mass, across a range of geoclimates, from arctic tundra, through temperate and semi-arid landscapes. In very few locations, such grasslands may be termed 'pristine' in that they remain undamaged by human activities and resilient to changing climates. In far more cases, grasslands are being degraded, often irreversibly so, with significant implications for a number of ecosystem services related to water resources, soil quality, nutrient cycles, and therefore both global food and water security. This paper draws upon empirical research that has been undertaken over the last decade to characterise a range of different grasslands in terms of soil properties, vegetation structure and geomorphology and to understand how these structures or patterns might interact or control how the grassland ecosystems function. Particular emphasis is placed upon quantifying fluxes of water, within and from grasslands, but also fluxes of sediment, via the processes of soil erosion and finally fluxes of the macronutrients Nitrogen, Phosphorus and Carbon from the landscape to surface waters. Data are presented from semi-arid grasslands, which are subject to severe encroachment by woody species, temperate upland grasslands that have been 'improved' via drainage to support grazing, temperate lowland grasslands, that are unimproved (Culm or Rhôs pastures) and finally intensively managed grasslands in temperate regions, that have been significantly modified via land management practices to improve productivity. It is hypothesised that, once degraded, the structure and function of these very diverse grassland ecosystems follows the same negative trajectory, resulting in depleted soil depths, nutrient storage capacities and therefore reduced plant growth and long-term carbon sequestration. Results demonstrate that similar, but highly complex and non-linear responses to perturbation of the ecosystem are observed, regardless of

Quantifying the pedo-ecohydrological structure and function of degraded, grassland ecosystems

NASA Astrophysics Data System (ADS)

Brazier, Richard E.

2015-04-01

Grassland ecosystems cover significant areas of the terrestrial land mass, across a range of geoclimates, from arctic tundra, through temperate and semi-arid landscapes. In very few locations, such grasslands may be termed 'pristine' in that they remain undamaged by human activities and resilient to changing climates. In far more cases, grasslands are being degraded, often irreversibly so, with significant implications for a number of ecosystem services related to water resources, soil quality, nutrient cycles, and therefore both global food and water security. This paper draws upon empirical research that has been undertaken over the last decade to characterise a range of different grasslands in terms of soil properties, vegetation structure and geomorphology and to understand how these structures or patterns might interact or control how the grassland ecosystems function. Particular emphasis is placed upon quantifying fluxes of water, within and from grasslands, but also fluxes of sediment, via the processes of soil erosion and finally fluxes of the macronutrients Nitrogen, Phosphorus and Carbon from the landscape to surface waters. Data are presented from semi-arid grasslands, which are subject to severe encroachment by woody species, temperate upland grasslands that have been 'improved' via drainage to support grazing, temperate lowland grasslands, that are unimproved (Culm or Rhôs pastures) and finally intensively managed grasslands in temperate regions, that have been significantly modified via land management practices to improve productivity. It is hypothesised that, once degraded, the structure and function of these very diverse grassland ecosystems follows the same negative trajectory, resulting in depleted soil depths, nutrient storage capacities and therefore reduced plant growth and long-term carbon sequestration. Results demonstrate that similar, but highly complex and non-linear responses to perturbation of the ecosystem are observed, regardless of

Effects of long-term grassland management on the carbon and nitrogen pools of different soil aggregate fractions.

PubMed

Egan, Gary; Crawley, Michael J; Fornara, Dario A

2018-02-01

Common grassland management practices include animal grazing and the repeated addition of lime and nutrient fertilizers to soils. These practices can greatly influence the size and distribution of different soil aggregate fractions, thus altering the cycling and storage of carbon (C) and nitrogen (N) in grassland soils. So far, very few studies have simultaneously addressed the potential long-term effect that multiple management practices might have on soil physical aggregation. Here we specifically ask whether and how grazing, liming and nutrient fertilization might influence C and N content (%) as well as C and N pools of different soil aggregate fractions in a long-term grassland experiment established in 1991 at Silwood Park, Berkshire, UK. We found that repeated liming applications over 23years significantly decreased the C pool (i.e. gCKg -1 soil) of Large Macro Aggregate (LMA>2mm) fractions and increased C pools within three smaller soil aggregate fractions: Small Macro Aggregate (SMA, 250μm-2mm), Micro Aggregate (MiA, 53-250μm), and Silt Clay Aggregate (SCA<53μm). Soil C (and N) accrual in smaller fractions was mainly caused by positive liming effects on aggregate fraction mass rather than on changes in soil C (and N) content (%). Liming effects could be explained by increases in soil pH, as this factor was significantly positively related to greater soil C and N pools of smaller aggregate fractions. Long-term grazing and inorganic nutrient fertilization had much weaker effects on both soil aggregate-fraction mass and on soil C and N concentrations, however, our evidence is that these practices could also contribute to greater C and N pools of smaller soil fractions. Overall our study demonstrates how agricultural liming can contribute to increase C pools of small (more stable) soil fractions with potential significant benefits for the long-term C balance of human-managed grassland soils. Copyright © 2017 Elsevier B.V. All rights reserved.

Methane Emissions from Semi-natural, Drained and Re-wetted Peatlands in Germany

NASA Astrophysics Data System (ADS)

Tiemeyer, B.; Bechtold, M.; Albiac Borraz, E.; Augustin, J.; Drösler, M.; Beetz, S.; Beyer, C.; Eickenscheidt, T.; Fiedler, S.; Förster, C.; Giebels, M.; Glatzel, S.; Heinichen, J.; Höper, H.; Leiber-Sauheitl, K.; Peichl-Brak, M.; Rosskopf, N.; Sommer, M.; Zeitz, J.; Freibauer, A.

2014-12-01

Drained peatlands contribute around 5% to the total German greenhouse gas emissions. While these areas are hotspots for carbon dioxide (CO2) and nitrous oxide (N2O) emissions, some re-wetted peatlands may emit large amounts of methane (CH4). To quantify the GHG emission reductions achieved by the re-wetting of peatlands, the reduced CO2 emissions and the potential CH4fluxes need to be balanced. We synthesized methane flux data from 14 peatlands with 122 sites. At each site, methane fluxes were measured for one to three years with static chambers. The sites comprise arable land, intensive and extensive grassland, forest and peat mining areas as well as semi-natural and re-wetted peatlands on both bog peat, fen peat and other soils rich in organic carbon. Besides the groundwater table we consider further potential drivers for the CH4fluxes such as soil properties (carbon, nitrogen, pH, and physical properties), climatic parameters, land use, and vegetation composition. Annual methane fluxes ranged from low uptake rates (around -1 g CH4-C m² a-1) to very high emissions (> 200 g CH4-C m² a-1). Intensively drained sites showed very low emissions, while for annual mean water levels higher than 5-10 cm below ground, elevated emissions of more than 20 g CH4-C may occur. At some re-wetted sites CH4 emissions of more than 100 g CH4-C m² a-1 were measured, which roughly equal the Global Warming Potential of the CO2-emissions from intensively drained agricultural sites. These high fluxes were probably caused by a combination of nutrient-rich conditions, the dieback of poorly adapted plants and a fast accumulation of organic sediments. However, this was the exception and not the rule even for very wet re-wetted sites. Achieving a model efficiency of 0.72 during cross-validation, a boosted regression tree (BRT) model was well able to describe logarithmic CH4-fluxes. Groundwater level, biotope type, soil nitrogen content, and ponding duration during summer were the most

Influence of Agropastoral System Components on Mountain Grassland Vulnerability Estimated by Connectivity Loss.

PubMed

Gartzia, Maite; Fillat, Federico; Pérez-Cabello, Fernando; Alados, Concepción L

2016-01-01

Over the last decades, global changes have altered the structure and properties of natural and semi-natural mountain grasslands. Those changes have contributed to grassland loss mainly through colonization by woody species at low elevations, and increases in biomass and greenness at high elevations. Nevertheless, the interactions between agropastoral components; i.e., ecological (grassland, environmental, and geolocation properties), social, and economic components, and their effects on the grasslands are still poorly understood. We estimated the vulnerability of dense grasslands in the Central Pyrenees, Spain, based on the connectivity loss (CL) among grassland patches that has occurred between the 1980s and the 2000s, as a result of i) an increase in biomass and greenness (CL-IBG), ii) woody encroachment (CL-WE), or iii) a decrease in biomass and greenness (CL-DBG). The environmental and grassland components of the agropastoral system were associated with the three processes, especially CL-IBG and CL-WE, in relation with the succession of vegetation toward climax communities, fostered by land abandonment and exacerbated by climate warming. CL-IBG occurred in pasture units that had a high proportion of dense grasslands and low current livestock pressure. CL-WE was most strongly associated with pasture units that had a high proportion of woody habitat and a large reduction in sheep and goat pressure between the 1930s and the 2000s. The economic component was correlated with the CL-WE and the CL-DBG; specifically, expensive pastures were the most productive and could maintain the highest rates of livestock grazing, which slowed down woody encroachment, but caused grassland degradation and DBG. In addition, CL-DBG was associated with geolocation of grasslands, mainly because livestock tend to graze closer to passable roads and buildings, where they cause grassland degradation. To properly manage the grasslands, an integrated management plan must be developed that

Lesser prairie-chicken avoidance of trees in a grassland landscape

USGS Publications Warehouse

Lautenbach, Joseph M.; Plumb, Reid T.; Robinson, Samantha G.; Hagen, Christian A.; Haukos, David A.; Pitman, James C.

2016-01-01

Grasslands are among the most imperiled ecosystems in North America. Reasons that grasslands are threatened include conversion to row-crop agriculture, fragmentation, and changes in fire regimes. The reduction of fire processes in remaining prairies has resulted in tree encroachment and establishment in grasslands, further reducing grassland quantity and quality. Grassland birds have been experiencing precipitous population declines in recent decades, commensurate with landscape changes to grasslands. The lesser prairie-chicken (Tympanuchus pallidicinctus Ridgway) is a declining species of prairie grouse of conservation concern. We used second- and third-order habitat selection metrics to test if female lesser prairie-chickens avoid grasslands where trees were present. Our results indicated that female lesser prairie-chickens selected habitats avoiding the nearest trees by 283 m on average, nearly twice as far as would be expected at random. Lesser prairie-chickens were 40 times more likely to use habitats with tree densities of 0 trees ∙ ha− 1 than habitats with 5 trees ∙ ha− 1. Probability of use indicated that lesser prairie-chickens were 19 times more likely to use habitats 1000 m from the nearest tree when compared with using habitats 0 m from the nearest tree. Nest survival was not affected at densities < 2 trees ∙ ha− 1; however, we could not test if nest survival was affected at greater tree densities as no nests were detected at densities > 2 trees ∙ ha− 1. Avoidance of trees could be due to perceived increased predation risk, reduced habitat quality, or a combination of these potentially confounding factors. Preventing further establishment and expansion of trees in landscapes occupied by lesser prairie-chickens could contribute to the continued persistence of the species. Additionally, restoring grasslands through tree removal may facilitate conservation efforts for grassland species such as the lesser prairie-chicken by improving

Comparative water relations of adjacent california shrub and grassland communities.

PubMed

Davis, S D; Mooney, H A

1985-07-01

Much of the coastal mountains and foothills of central and southern California are covered by a mosaic of grassland, coastal sage scrub, and evergreen sclerophyllous shrubs (chaparral). In many cases, the borders between adjacent plant communities are stable. The cause of this stability is unknown. The purpose of our study was to examine the water use patterns of representative grasses, herbs, and shrubs across a grassland/chaparrel ecotone and determine the extent to which patterns of water use contribute to ecotone stability. In addition, we examined the effects of seed dispersal and animal herbivory. We found during spring months, when water was not limited, grassland species had a much higher leaf conductance to water vapor diffusion than chaparral plants. As the summer drought progressed, grassland species depleted available soil moisture first, bare zone plants second, and chaparral third, with one chaparral species (Quercus durata) showing no evidence of water stress. Soil moisture depletion patterns with depth and time corresponded to plant water status and root depth. Rabbit herbivory was highest in the chaparral and bare zone as indicated by high densities of rabbit pellets. Dispersal of grassland seeds into the chaparral and bare zone was low. Our results support the hypothesis that grassland species deplete soil moisture in the upper soil horizon early in the drought, preventing the establishment of chaparral seedlings or bare zone herbs. Also, grassland plants are prevented from invading the chaparral because of low seed dispersability and high animal herbivory in these regions.

Regime shifts in desert grasslands: patterns, mechanisms, and management

USDA-ARS?s Scientific Manuscript database

Transitions from semiarid grassland to shrubland states are among the most widely recognized examples of regime shifts in terrestrial ecosystems. Nonetheless, the processes causing grassland-shrubland transitions, and their consequences, are incompletely understood. We challenge several misconceptio...

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.

Exotic grasslands on reclaimed midwestern coal mines: An ornithological perspective

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

Scott, P.E.; Lima, S.L.

The largest grasslands in Indiana and Illinois are on reclaimed surface coal mines, which are numerous in the Illinois Coal Basin. The reclamation goal of establishing a vegetation cover with inexpensive, hardy exotic grass species (e.g., tall fescue, smooth brome) inadvertently created persistent, large grassland bird refuges. We review research documenting the importance of these sites for native prairie birds. On mines, grassland specialist birds (restricted to grassland throughout their range) prefer sites dominated by exotic grasses to those rich in forbs, whereas nonspecialist bird species show no significant preference. Midwestern mine grasslands potentially could be converted into landscapes thatmore » include native warm-season grasses and forbs adapted to the relatively dry, poor soil conditions, in addition to the present successful exotic grass stands. A key question is whether native mixtures will resist conversion to forb-rich or woody growth over the long term, as the exotic grasses have done.« less

Ecological transition in Arizona's subalpine and montane grasslands

Treesearch

Michael R. White

2000-01-01

Important components of Southwest forest ecosystem are subalpine and montane grassland communities, Grassland communities provide habitat diversity for wildlife, forage for domestic livestock and wildlife, and contribute to the visual quality of an area. The objectives of this research were to determine if: 1) vegetation attributes and soil-surface cover variables of...

[Vegetation index estimation by chlorophyll content of grassland based on spectral analysis].

PubMed

Xiao, Han; Chen, Xiu-Wan; Yang, Zhen-Yu; Li, Huai-Yu; Zhu, Han

2014-11-01

Comparing the methods of existing remote sensing research on the estimation of chlorophyll content, the present paper confirms that the vegetation index is one of the most practical and popular research methods. In recent years, the increasingly serious problem of grassland degradation. This paper, firstly, analyzes the measured reflectance spectral curve and its first derivative curve in the grasslands of Songpan, Sichuan and Gongger, Inner Mongolia, conducts correlation analysis between these two spectral curves and chlorophyll content, and finds out the regulation between REP (red edge position) and grassland chlorophyll content, that is, the higher the chlorophyll content is, the higher the REIP (red-edge inflection point) value would be. Then, this paper constructs GCI (grassland chlorophyll index) and selects the most suitable band for retrieval. Finally, this paper calculates the GCI by the use of satellite hyperspectral image, conducts the verification and accuracy analysis of the calculation results compared with chlorophyll content data collected from field of twice experiments. The result shows that for grassland chlorophyll content, GCI has stronger sensitivity than other indices of chlorophyll, and has higher estimation accuracy. GCI is the first proposed to estimate the grassland chlorophyll content, and has wide application potential for the remote sensing retrieval of grassland chlorophyll content. In addition, the grassland chlorophyll content estimation method based on remote sensing retrieval in this paper provides new research ideas for other vegetation biochemical parameters' estimation, vegetation growth status' evaluation and grassland ecological environment change's monitoring.

Long-term grazing effects on vegetation characteristics and soil properties in a semiarid grassland, northern China.

PubMed

Zhang, Jing; Zuo, Xiaoan; Zhou, Xin; Lv, Peng; Lian, Jie; Yue, Xiyuan

2017-05-01

Understanding the responses of vegetation characteristics and soil properties to grazing disturbance is useful for grassland ecosystem restoration and management in semiarid areas. Here, we examined the effects of long-term grazing on vegetation characteristics, soil properties, and their relationships across four grassland types (meadow, Stipa steppe, scattered tree grassland, and sandy grassland) in the Horqin grassland, northern China. Our results showed that grazing greatly decreased vegetation cover, aboveground plant biomass, and root biomass in all four grassland types. Plant cover and aboveground biomass of perennials were decreased by grazing in all four grasslands, whereas grazing increased the cover and biomass of shrubs in Stipa steppe and of annuals in scattered tree grassland. Grazing decreased soil carbon and nitrogen content in Stipa steppe and scattered tree grassland, whereas soil bulk density showed the opposite trend. Long-term grazing significantly decreased soil pH and electrical conductivity (EC) in annual-dominated sandy grassland. Soil moisture in fenced and grazed grasslands decreased in the following order of meadow, Stipa steppe, scattered tree grassland, and sandy grassland. Correlation analyses showed that aboveground plant biomass was significantly positively associated with the soil carbon and nitrogen content in grazed and fenced grasslands. Species richness was significantly positively correlated with soil bulk density, moisture, EC, and pH in fenced grasslands, but no relationship was detected in grazed grasslands. These results suggest that the soil carbon and nitrogen content significantly maintains ecosystem function in both fenced and grazed grasslands. However, grazing may eliminate the association of species richness with soil properties in semiarid grasslands.

Impacts of tree rows on grassland birds & potential nest predators: A removal experiment

USGS Publications Warehouse

Ellison, Kevin S.; Ribic, Christine; Sample, David W.; Fawcett, Megan J.; Dadisman, John D.

2013-01-01

Globally, grasslands and the wildlife that inhabit them are widely imperiled. Encroachment by shrubs and trees has widely impacted grasslands in the past 150 years. In North America, most grassland birds avoid nesting near woody vegetation. Because woody vegetation fragments grasslands and potential nest predator diversity and abundance is often greater along wooded edge and grassland transitions, we measured the impacts of removing rows of trees and shrubs that intersected grasslands on potential nest predators and the three most abundant grassland bird species (Henslow’s sparrow [Ammodramus henslowii], Eastern meadowlark [Sturnella magna], and bobolink [Dolichonyx oryzivorus]) at sites in Wisconsin, U.S.A. We monitored 3 control and 3 treatment sites, for 1 yr prior to and 3 yr after tree row removal at the treatment sites. Grassland bird densities increased (2–4 times for bobolink and Henslow’s sparrow) and nesting densities increased (all 3 species) in the removal areas compared to control areas. After removals, Henslow’s sparrows nested within ≤50 m of the treatment area, where they did not occur when tree rows were present. Most dramatically, activity by woodland-associated predators nearly ceased (nine-fold decrease for raccoon [Procyon lotor]) at the removals and grassland predators increased (up to 27 times activity for thirteen-lined ground squirrel [Ictidomys tridecemlineatus]). Nest success did not increase, likely reflecting the increase in grassland predators. However, more nests were attempted by all 3 species (175 versus 116) and the number of successful nests for bobolinks and Henslow’s sparrows increased. Because of gains in habitat, increased use by birds, greater production of young, and the effective removal of woodland-associated predators, tree row removal, where appropriate based on the predator community, can be a beneficial management action for conserving grassland birds and improving fragmented and degraded grassland

Occupancy patterns of regionally declining grassland sparrow populations in a forested Pennsylvania landscape

USGS Publications Warehouse

Hill, Jason M.; Diefenbach, Duane R.

2014-01-01

Organisms can be affected by processes in the surrounding landscape outside the boundary of habitat areas and by local vegetation characteristics. There is substantial interest in understanding how these processes affect populations of grassland birds, which have experienced substantial population declines. Much of our knowledge regarding patterns of occupancy and density stem from prairie systems, whereas relatively little is known regarding how occurrence and abundance of grassland birds vary in reclaimed surface mine grasslands. Using distance sampling and single-season occupancy models, we investigated how the occupancy probability of Grasshopper (Ammodramus savannarum) and Henslow's Sparrows (A. henslowii) on 61 surface mine grasslands (1591 ha) in Pennsylvania changed from 2002 through 2011 in response to landscape, grassland, and local vegetation characteristics . A subset (n = 23; 784 ha) of those grasslands were surveyed in 2002, and we estimated changes in sparrow density and vegetation across 10 years. Grasshopper and Henslow's Sparrow populations declined 72% and 49%, respectively from 2002 to 2011, whereas overall woody vegetation density increased 2.6 fold. Henslow's Sparrows avoided grasslands with perimeter–area ratios ≥0.141 km/ha and woody shrub densities ≥0.04 shrubs/m2. Both species occupied grasslands ≤13 ha, but occupancy probability declined with increasing grassland perimeter–area ratio and woody shrub density. Grassland size, proximity to nearest neighboring grassland ( = 0.2 km), and surrounding landscape composition at 0.5, 1.5, and 3.0 km were not parsimonious predictors of occupancy probability for either species. Our results suggest that reclaimed surface mine grasslands, without management intervention, are ephemeral habitats for Grasshopper and Henslow's Sparrows. Given the forecasted decline in surface coal production for Pennsylvania, it is likely that both species will continue to decline in our study region for the

Occupancy patterns of regionally declining grassland sparrow populations in a forested Pennsylvania landscape.

PubMed

Hill, Jason M; Diefenbach, Duane R

2014-06-01

Organisms can be affected by processes in the surrounding landscape outside the boundary of habitat areas and by local vegetation characteristics. There is substantial interest in understanding how these processes affect populations of grassland birds, which have experienced substantial population declines. Much of our knowledge regarding patterns of occupancy and density stem from prairie systems, whereas relatively little is known regarding how occurrence and abundance of grassland birds vary in reclaimed surface mine grasslands. Using distance sampling and single-season occupancy models, we investigated how the occupancy probability of Grasshopper (Ammodramus savannarum) and Henslow's Sparrows (A. henslowii) on 61 surface mine grasslands (1591 ha) in Pennsylvania changed from 2002 through 2011 in response to landscape, grassland, and local vegetation characteristics . A subset (n = 23; 784 ha) of those grasslands were surveyed in 2002, and we estimated changes in sparrow density and vegetation across 10 years. Grasshopper and Henslow's Sparrow populations declined 72% and 49%, respectively from 2002 to 2011, whereas overall woody vegetation density increased 2.6 fold. Henslow's Sparrows avoided grasslands with perimeter-area ratios ≥0.141 km/ha and woody shrub densities ≥0.04 shrubs/m(2). Both species occupied grasslands ≤13 ha, but occupancy probability declined with increasing grassland perimeter-area ratio and woody shrub density. Grassland size, proximity to nearest neighboring grassland (x = 0.2 km), and surrounding landscape composition at 0.5, 1.5, and 3.0 km were not parsimonious predictors of occupancy probability for either species. Our results suggest that reclaimed surface mine grasslands, without management intervention, are ephemeral habitats for Grasshopper and Henslow's Sparrows. Given the forecasted decline in surface coal production for Pennsylvania, it is likely that both species will continue to decline in our study region for the

Managed grassland alters soil N dynamics and N2O emissions in temperate steppe.

PubMed

Xu, Lijun; Xu, Xingliang; Tang, Xuejuan; Xin, Xiaoping; Ye, Liming; Yang, Guixia; Tang, Huajun; Lv, Shijie; Xu, Dawei; Zhang, Zhao

2018-04-01

Reclamation of degraded grasslands as managed grasslands has been increasingly accelerated in recent years in China. Land use change affects soil nitrogen (N) dynamics and nitrous oxide (N 2 O) emissions. However, it remains unclear how large-scale grassland reclamation will impact the grassland ecosystem as a whole. Here, we investigated the effects of the conversion from native to managed grasslands on soil N dynamics and N2O emissions by field experiments in Hulunber in northern China. Soil (0-10cm), nitrate (NO 3 - ), ammonium (NH 4 + ), and microbial N were measured in plots in a temperate steppe (Leymus chinensis grassland) and two managed grasslands (Medicago sativa and Bromus inermis grasslands) in 2011 and 2012. The results showed conversion of L. chinensis grassland to M. sativa or B. inermis grasslands decreased concentrations of NO 3 - -N, but did not change NH 4 + -N. Soil microbial N was slightly decreased by the conversion of L. chinensis grassland to M. sativa, but increased by the conversion to B. inermis. The conversion of L. chinensis grassland to M. sativa (i.e., a legume grass) increased N 2 O emissions by 26.2%, while the conversion to the B. inermis (i.e., a non-legume grass) reduced N 2 O emissions by 33.1%. The conversion from native to managed grasslands caused large created variations in soil NO 3 - -N and NH 4 + -N concentrations. Net N mineralization rates did not change significantly in growing season or vegetation type, but to net nitrification rate. These results provide evidence on how reclamation may impact the grassland ecosystem in terms of N dynamics and N 2 O emissions. Copyright © 2017. Published by Elsevier B.V.

Bird productivity and nest predation in agricultural grasslands

USGS Publications Warehouse

Ribic, Christine; Guzy, Michael J.; Anderson, Travis J.; Sample, David W.; Nack, Jamie L.

2012-01-01

Effective conservation strategies for grassland birds in agricultural landscapes require understanding how nesting success varies among different grassland habitats. A key component to this is identifying nest predators and how these predators vary by habitat. We quantified nesting activity of obligate grassland birds in three habitats [remnant prairie, cool-season grass Conservation Reserve Program (CRP) fields, and pastures) in southwest Wisconsin, 2002-2004. We determined nest predators using video cameras and examined predator activity using track stations. Bobolink (Dolichonyx oryzivorus) and Henslow's Sparrow (Ammodramus henslowii) nested primarily in CRP fields, and Grasshopper Sparrow (A. savannarum) in remnant prairies. Eastern Meadowlark (Sturnella magna) nested evenly across all three habitats. Daily nest survival rate for Eastern Meadowlark varied by nesting stage alone. Daily nest survival rate for Grasshopper Sparrow varied by nest vegetation and distance to the nearest woody edge; nest survival was higher near woody edges. In CRP fields, most predators were grassland-associated, primarily thirteen-lined ground squirrels (Ictidomys tridecemlineatus). In pastures, one-third of the nest predators were grassland-associated (primarily thirteen-lined ground squirrels) and 56% were associated with woody habitats (primarily raccoons, Procyon lotor). Raccoon activity was greatest around pastures and lowest around prairies; regardless of habitat, raccoon activity along woody edges was twice that along non-woody edges. Thirteen-lined ground squirrel activity was greater along prairie edges than pastures and was greater along nonwoody edges compared to woody edges. In CRP fields, raccoon activity was greater along edges compared to the interiors; for ground squirrels these relationships were reversed. Using video camera technology to identify nest predators was indispensable in furthering our understanding of the grassland system. The challenge is to use that

Considering Forest and Grassland Carbon in Land Management

Treesearch

M. Janowiak; W.J. Connelly; K. Dante-Wood; G.M. Domke; C. Giardina; Z. Kayler; K. Marcinkowski; T. Ontl; C. Rodriguez-Franco; C. Swanston; C.W. Woodall; M. Buford

2017-01-01

Forest and grassland ecosystems in the United States play a critical role in the global carbon cycle, and land management activities influence their ability to absorb and sequester carbon. These ecosystems provide a critical regulating function, offsetting about 12 to 19 percent of the Nation's annual greenhouse gas emissions. Forests and grasslands are managed...

Influence of Agropastoral System Components on Mountain Grassland Vulnerability Estimated by Connectivity Loss

PubMed Central

Fillat, Federico; Pérez-Cabello, Fernando; Alados, Concepción L.

2016-01-01

Over the last decades, global changes have altered the structure and properties of natural and semi-natural mountain grasslands. Those changes have contributed to grassland loss mainly through colonization by woody species at low elevations, and increases in biomass and greenness at high elevations. Nevertheless, the interactions between agropastoral components; i.e., ecological (grassland, environmental, and geolocation properties), social, and economic components, and their effects on the grasslands are still poorly understood. We estimated the vulnerability of dense grasslands in the Central Pyrenees, Spain, based on the connectivity loss (CL) among grassland patches that has occurred between the 1980s and the 2000s, as a result of i) an increase in biomass and greenness (CL-IBG), ii) woody encroachment (CL-WE), or iii) a decrease in biomass and greenness (CL-DBG). The environmental and grassland components of the agropastoral system were associated with the three processes, especially CL-IBG and CL-WE, in relation with the succession of vegetation toward climax communities, fostered by land abandonment and exacerbated by climate warming. CL-IBG occurred in pasture units that had a high proportion of dense grasslands and low current livestock pressure. CL-WE was most strongly associated with pasture units that had a high proportion of woody habitat and a large reduction in sheep and goat pressure between the 1930s and the 2000s. The economic component was correlated with the CL-WE and the CL-DBG; specifically, expensive pastures were the most productive and could maintain the highest rates of livestock grazing, which slowed down woody encroachment, but caused grassland degradation and DBG. In addition, CL-DBG was associated with geolocation of grasslands, mainly because livestock tend to graze closer to passable roads and buildings, where they cause grassland degradation. To properly manage the grasslands, an integrated management plan must be developed that

Ecosystem Carbon Storage in Alpine Grassland on the Qinghai Plateau

PubMed Central

Liu, Shuli; Zhang, Fawei; Du, Yangong; Guo, Xiaowei; Lin, Li; Li, Yikang; Li, Qian; Cao, Guangmin

2016-01-01

The alpine grassland ecosystem can sequester a large quantity of carbon, yet its significance remains controversial owing to large uncertainties in the relative contributions of climate factors and grazing intensity. In this study we surveyed 115 sites to measure ecosystem carbon storage (both biomass and soil) in alpine grassland over the Qinghai Plateau during the peak growing season in 2011 and 2012. Our results revealed three key findings. (1) Total biomass carbon density ranged from 0.04 for alpine steppe to 2.80 kg C m-2 for alpine meadow. Median soil organic carbon (SOC) density was estimated to be 16.43 kg C m-2 in alpine grassland. Total ecosystem carbon density varied across sites and grassland types, from 1.95 to 28.56 kg C m-2. (2) Based on the median estimate, the total carbon storage of alpine grassland on the Qinghai Plateau was 5.14 Pg, of which 94% (4.85 Pg) was soil organic carbon. (3) Overall, we found that ecosystem carbon density was affected by both climate and grazing, but to different extents. Temperature and precipitation interaction significantly affected AGB carbon density in winter pasture, BGB carbon density in alpine meadow, and SOC density in alpine steppe. On the other hand, grazing intensity affected AGB carbon density in summer pasture, SOC density in alpine meadow and ecosystem carbon density in alpine grassland. Our results indicate that grazing intensity was the primary contributing factor controlling carbon storage at the sites tested and should be the primary consideration when accurately estimating the carbon storage in alpine grassland. PMID:27494253

Ecosystem Carbon Storage in Alpine Grassland on the Qinghai Plateau.

PubMed

Liu, Shuli; Zhang, Fawei; Du, Yangong; Guo, Xiaowei; Lin, Li; Li, Yikang; Li, Qian; Cao, Guangmin

2016-01-01

The alpine grassland ecosystem can sequester a large quantity of carbon, yet its significance remains controversial owing to large uncertainties in the relative contributions of climate factors and grazing intensity. In this study we surveyed 115 sites to measure ecosystem carbon storage (both biomass and soil) in alpine grassland over the Qinghai Plateau during the peak growing season in 2011 and 2012. Our results revealed three key findings. (1) Total biomass carbon density ranged from 0.04 for alpine steppe to 2.80 kg C m-2 for alpine meadow. Median soil organic carbon (SOC) density was estimated to be 16.43 kg C m-2 in alpine grassland. Total ecosystem carbon density varied across sites and grassland types, from 1.95 to 28.56 kg C m-2. (2) Based on the median estimate, the total carbon storage of alpine grassland on the Qinghai Plateau was 5.14 Pg, of which 94% (4.85 Pg) was soil organic carbon. (3) Overall, we found that ecosystem carbon density was affected by both climate and grazing, but to different extents. Temperature and precipitation interaction significantly affected AGB carbon density in winter pasture, BGB carbon density in alpine meadow, and SOC density in alpine steppe. On the other hand, grazing intensity affected AGB carbon density in summer pasture, SOC density in alpine meadow and ecosystem carbon density in alpine grassland. Our results indicate that grazing intensity was the primary contributing factor controlling carbon storage at the sites tested and should be the primary consideration when accurately estimating the carbon storage in alpine grassland.

Tools for Management for Grassland Ecosystem Sustainability: Thinking "Outside the Box"

Treesearch

Gerald J. Gottfried

2004-01-01

Grassland ecosystem management is dynamic and has adapted to the development of new tools and ideas. Our ancestors were indirectly managing grasslands when they learned to move livestock to take advantage of better water and greener forage. One could argue that even their hunting of grassland wildlife, especially the use of fire to drive animals to waiting hunters, had...

Net ecosystem productivity of temperate grasslands in northern China: An upscaling study

USGS Publications Warehouse

Zhang, Li; Guo, Huadong; Jia, Gensuo; Wylie, Bruce; Gilmanov, Tagir; Howard, Daniel M.; Ji, Lei; Xiao, Jingfeng; Li, Jing; Yuan, Wenping; Zhao, Tianbao; Chen, Shiping; Zhou, Guangsheng; Kato, Tomomichi

2014-01-01

Grassland is one of the widespread biome types globally, and plays an important role in the terrestrial carbon cycle. We examined net ecosystem production (NEP) for the temperate grasslands in northern China from 2000 to 2010. We combined flux observations, satellite data, and climate data to develop a piecewise regression model for NEP, and then used the model to map NEP for grasslands in northern China. Over the growing season, the northern China's grassland had a net carbon uptake of 158 ± 25 g C m−2 during 2000–2010 with the mean regional NEP estimate of 126 Tg C. Our results showed generally higher grassland NEP at high latitudes (northeast) than at low latitudes (central and west) because of different grassland types and environmental conditions. In the northeast, which is dominated by meadow steppes, the growing season NEP generally reached 200–300 g C m−2. In the southwest corner of the region, which is partially occupied by alpine meadow systems, the growing season NEP also reached 200–300 g C m−2. In the central part, which is dominated by typical steppe systems, the growing season NEP generally varied in the range of 100–200 g C m−2. The NEP of the northern China's grasslands was highly variable through years, ranging from 129 (2001) to 217 g C m−2 growing season−1 (2010). The large interannual variations of NEP could be attributed to the sensitivity of temperate grasslands to climate changes and extreme climatic events. The droughts in 2000, 2001, and 2006 reduced the carbon uptake over the growing season by 11%, 29%, and 16% relative to the long-term (2000–2010) mean. Over the study period (2000–2010), precipitation was significantly correlated with NEP for the growing season (R2 = 0.35, p-value < 0.1), indicating that water availability is an important stressor for the productivity of the temperate grasslands in semi-arid and arid regions in northern China. We conclude that northern temperate grasslands have the potential to

Effects of haying on breeding birds in CRP grasslands

USGS Publications Warehouse

Igl, Lawrence D.; Johnson, Douglas H.

2016-01-01

The Conservation Reserve Program (CRP) is a voluntary program that is available to agricultural producers to help protect environmentally sensitive or highly erodible land. Management disturbances of CRP grasslands generally are not allowed unless authorized to provide relief to livestock producers during severe drought or a similar natural disaster (i.e., emergency haying and grazing) or to improve the quality and performance of the CRP cover (i.e., managed haying and grazing). Although CRP grasslands may not be hayed or grazed during the primary bird-nesting season, these disturbances may have short-term (1 yr after disturbance) and long-term (≥2 yr after disturbance) effects on grassland bird populations. We assessed the effects of haying on 20 grassland bird species in 483 CRP grasslands in 9 counties of 4 states in the northern Great Plains, USA between 1993 and 2008. We compared breeding bird densities (as determined by total-area counts) in idle and hayed fields to evaluate changes 1, 2, 3, and 4 years after haying. Haying of CRP grasslands had either positive or negative effects on grassland birds, depending on the species, the county, and the number of years after the initial disturbance. Some species (e.g., horned lark [Eremophila alpestris], bobolink [Dolichonyx oryzivorus]) responded positively after haying, and others (e.g., song sparrow [Melospiza melodia]) responded negatively. The responses of some species changed direction as the fields recovered from haying. For example, densities for common yellowthroat (Geothlypis trichas), sedge wren (Cistothorus platensis), and clay-colored sparrow (Spizella pallida) declined the first year after haying but increased in the subsequent 3 years. Ten species showed treatment × county interactions, indicating that the effects of haying varied geographically. This long-term evaluation on the effects of haying on breeding birds provides important information on the strength and direction of changes in

Green fescue grassland: 40 years of secondary succession.

Treesearch

Elbert H. Reid; Gerald S. Strickler; Wade B. Hall

1980-01-01

The 40-year succession of a depleted green fescue (Festuca viridula) sub-alpine grassland in the Wallowa Mountains, Oregon, was influenced by historic soil erosion. Range conditions of the grassland annually grazed by domestic sheep improved greatly between 1938 and 1978; most of the improvement occurred between the 30th and 40th years. Photographs illustrate the...

Establishment gaps as an innovative tool to restore landscape-scale grassland biodiversity

NASA Astrophysics Data System (ADS)

Tóthmérész, Béla; Deák, Balázs; Török, Péter; Tischew, Sabine; Kirmer, Anita; Kelemen, András; Miglécz, Tamás; Tóth, Katalin; Radócz, Szilvia; Sonkoly, Judit; Valkó, Orsolya

2017-04-01

The large-scale abandonment of croplands resulted in landscape-scale changes in biodiversity, ecosystem services and agricultural production in Central Europe. Grasslands are vital landscape elements, and sustaining their biodiversity is crucial for biodiversity conservation. Thus, grassland restoration on former croplands offers a vital opportunity to restore grassland biodiversity. We studied vegetation changes in former croplands sown by grass seed mixtures in Hungary. We evaluated the usefulness of sowing grass seed mixtures, a frequently used restoration technique. We also developed a novel method (so-called establishment gaps) to increase the diversity of species-poor sown grasslands. We compiled a multi-species seed mixture containing 35 species. We established altogether 32 establishment gaps (size: 1×1-m, 2×2-m and 4×4-m) in 8-year-old restored grasslands. We evaluated the success and cost-effectiveness of spontaneous grassland recovery and active grassland restoration by seed sowing. We focused on the restoration of ecosystem services, like weed control, biomass production, and recovery of biodiversity. Using establishment gaps we could successfully introduce target species to the species-poor recovered grasslands. All sown species established in the establishment gaps and many of them maintained or even increased their first-year cover to the second year. Larger establishment gaps were characterised by higher cover of sown species and more homogeneous species composition compared to the smaller ones. Thus, we recommend using large establishment gaps in restoration practice. Our findings suggest that grassland restoration on croplands offer a viable solution for restoring biodiversity and ecosystem services. We found that both spontaneous grassland recovery and seed sowing can be cost-effective methods, and can be successful even during a relatively short period of a nature conservation project.

Prescribed fire as an alternative measure in European grassland conservation

NASA Astrophysics Data System (ADS)

Valkó, Orsolya; Deák, Balázs; Török, Péter; Tóthmérész, Béla

2015-04-01

There are contrasting opinions on the perspectives of prescribed burning management in European grasslands. One hand, prescribed burning can be effectively used with relatively low implementation costs for the management of open landscapes, the reduction of accumulated litter or for decreasing the chance of wildfires. On the other hand burning can also have serious detrimental impacts on grassland ecosystems by promoting the dominance of some problem species (e.g. some competitors or invasive species) and by threatening endangered plant and animal species, especially invertebrates, thus, inappropriate burning can result in a loss of biodiversity in the long run. Our goal was to review the publications on the application of prescribed burning in European grasslands considering general (e.g. timing, frequency and duration) and specific (e.g. types of grasslands, effects on endangered species) circumstances. Even prescribed burning forms an integral part of the North-American grassland management practice, it is rarely applied in Europe, despite the fact that uncontrolled burning occurs frequently in some regions. According to the North-American experiences prescribed burning can be a viable solution for biodiversity conservation and can be a feasible solution for several nature conservation problems. We reviewed prescribed burning studies from Europe and North-America to identify findings which might be adapted to the European grassland conservation strategy. We found that not only the application of fire management is scarce in Europe but there is also a lack of published studies on this topic. European studies - contrary to the North-American practice - usually used yearly dormant-season burning, and concluded that this burning type solely is not feasible to preserve and maintain species-rich grasslands. In North-American grasslands, application of burning has a stronger historical, practical and scientific background; it is fine-tuned in terms of timing, frequency

Potential soil carbon sequestration in overgrazed grassland ecosystems

NASA Astrophysics Data System (ADS)

Conant, Richard T.; Paustian, Keith

2002-12-01

Excessive grazing pressure is detrimental to plant productivity and may lead to declines in soil organic matter. Soil organic matter is an important source of plant nutrients and can enhance soil aggregation, limit soil erosion, and can also increase cation exchange and water holding capacities, and is, therefore, a key regulator of grassland ecosystem processes. Changes in grassland management which reverse the process of declining productivity can potentially lead to increased soil C. Thus, rehabilitation of areas degraded by overgrazing can potentially sequester atmospheric C. We compiled data from the literature to evaluate the influence of grazing intensity on soil C. Based on data contained within these studies, we ascertained a positive linear relationship between potential C sequestration and mean annual precipitation which we extrapolated to estimate global C sequestration potential with rehabilitation of overgrazed grassland. The GLASOD and IGBP DISCover data sets were integrated to generate a map of overgrazed grassland area for each of four severity classes on each continent. Our regression model predicted losses of soil C with decreased grazing intensity in drier areas (precipitation less than 333 mm yr-1), but substantial sequestration in wetter areas. Most (93%) C sequestration potential occurred in areas with MAP less than 1800 mm. Universal rehabilitation of overgrazed grasslands can sequester approximately 45 Tg C yr-1, most of which can be achieved simply by cessation of overgrazing and implementation of moderate grazing intensity. Institutional level investments by governments may be required to sequester additional C.

Modeling effects of conservation grassland losses on amphibian habitat

USGS Publications Warehouse

Mushet, David M.; Neau, Jordan L.; Euliss, Ned H.

2014-01-01

Amphibians provide many ecosystem services valued by society. However, populations have declined globally with most declines linked to habitat change. Wetlands and surrounding terrestrial grasslands form habitat for amphibians in the North American Prairie Pothole Region (PPR). Wetland drainage and grassland conversion have destroyed or degraded much amphibian habitat in the PPR. However, conservation grasslands can provide alternate habitat. In the United States, the Conservation Reserve Program (CRP) is the largest program maintaining grasslands on agricultural lands. We used an ecosystem services model (InVEST) parameterized for the PPR to quantify amphibian habitat over a six-year period (2007–2012). We then quantified changes in availability of amphibian habitat under various land-cover scenarios representing incremental losses (10%, 25%, 50%, 75%, and 100%) of CRP grasslands from 2012 levels. The area of optimal amphibian habitat in the four PPR ecoregions modeled (i.e., Northern Glaciated Plains, Northwestern Glaciated Plains, Lake Agassiz Plain, Des Moines Lobe) declined by approximately 22%, from 3.8 million ha in 2007 to 2.9 million ha in 2012. These losses were driven by the conversion of CRP grasslands to croplands, primarily for corn and soybean production. Our modeling identified an additional 0.8 million ha (26%) of optimal amphibian habitat that would be lost if remaining CRP lands are returned to crop production. An economic climate favoring commodity production over conservation has resulted in substantial losses of amphibian habitat across the PPR that will likely continue into the future. Other regions of the world face similar challenges to maintaining amphibian habitats.

Using Calibrated RGB Imagery from Low-Cost Uavs for Grassland Monitoring: Case Study at the Rengen Grassland Experiment (rge), Germany

NASA Astrophysics Data System (ADS)

Lussem, U.; Hollberg, J.; Menne, J.; Schellberg, J.; Bareth, G.

2017-08-01

Monitoring the spectral response of intensively managed grassland throughout the growing season allows optimizing fertilizer inputs by monitoring plant growth. For example, site-specific fertilizer application as part of precision agriculture (PA) management requires information within short time. But, this requires field-based measurements with hyper- or multispectral sensors, which may not be feasible on a day to day farming practice. Exploiting the information of RGB images from consumer grade cameras mounted on unmanned aerial vehicles (UAV) can offer cost-efficient as well as near-real time analysis of grasslands with high temporal and spatial resolution. The potential of RGB imagery-based vegetation indices (VI) from consumer grade cameras mounted on UAVs has been explored recently in several. However, for multitemporal analyses it is desirable to calibrate the digital numbers (DN) of RGB-images to physical units. In this study, we explored the comparability of the RGBVI from a consumer grade camera mounted on a low-cost UAV to well established vegetation indices from hyperspectral field measurements for applications in grassland. The study was conducted in 2014 on the Rengen Grassland Experiment (RGE) in Germany. Image DN values were calibrated into reflectance by using the Empirical Line Method (Smith & Milton 1999). Depending on sampling date and VI the correlation between the UAV-based RGBVI and VIs such as the NDVI resulted in varying R2 values from no correlation to up to 0.9. These results indicate, that calibrated RGB-based VIs have the potential to support or substitute hyperspectral field measurements to facilitate management decisions on grasslands.

Cowbird parasitism in grassland and cropland in the northern Great Plains: Chapter 27

USGS Publications Warehouse

Koford, Rolf R.; Bowen, B.S.; Lokemoen, John T.; Kruse, Arnold D.; Smith, James N.M.; Cook, T.L.; Rothstein, S. IU.; Robinson, S.K.; Sealy, S.G.

2000-01-01

The landscape of the Great Plains has been greatly altered by human activities in the past century, and several grassland passerines have experienced significant population declines in recent decades. We explore here whether brood parasitism by Brown-headed Cowbirds, which are abundant in the Great Plains, has contributed to these declines. We measured the frequency of cowbird parasitism of passerine species in seeded grassland, natural grassland, and cropland in studies conducted in North Dakota during 1981-1993. The proportions of parasitized nests were 25%, 34%, and 39% in seeded grassland, natural grassland, and cropland, respectively. We speculate that much of the variation in parasitism rate among these habitats is related to the local abundance of cowbirds, to nest visibility, and to the presence of suitable perches for female cowbirds. Local abundance of cowbirds may be high in areas with cattle pastures. Nests and nesting behavior are probably more visible to female cowbirds in cropland than in grassland. Female cowbirds may use shrubs as perches while searching for host nests, and shrubs are more common in natural grasslands than in the other habitats we examined. Experimental work on the determinants of cowbird abundance in grasslands is needed.

PREFACE: Dynamics of wetting Dynamics of wetting

NASA Astrophysics Data System (ADS)

Grest, Gary S.; Oshanin, Gleb; Webb, Edmund B., III

2009-11-01

Capillary phenomena associated with fluids wetting other condensed matter phases have drawn great scientific interest for hundreds of years; consider the recent bicentennial celebration of Thomas Young's paper on equilibrium contact angles, describing the geometric shape assumed near a three phase contact line in terms of the relevant surface energies of the constituent phases [1]. Indeed, nearly a century has passed since the seminal papers of Lucas and Washburn, describing dynamics of capillary imbibition [2, 3]. While it is generally appreciated that dynamics of fluid wetting processes are determined by the degree to which a system is out of capillary equilibrium, myriad complications exist that challenge the fundamental understanding of dynamic capillary phenomena. The topic has gathered much interest from recent Nobel laureate Pierre-Gilles de Gennes, who provided a seminal review of relevant dissipation mechanisms for fluid droplets spreading on solid surfaces [4] Although much about the dynamics of wetting has been revealed, much remains to be learned and intrinsic technological and fundamental interest in the topic drives continuing high levels of research activity. This is enabled partly by improved experimental capabilities for resolving wetting processes at increasingly finer temporal, spatial, and chemical resolution. Additionally, dynamic wetting research advances via higher fidelity computational modeling capabilities, which drive more highly refined theory development. The significance of this topic both fundamentally and technologically has resulted in a number of reviews of research activity in wetting dynamics. One recent example addresses the evaluation of existing wetting dynamics theories from an experimentalist's perspective [5]. A Current Opinion issue was recently dedicated to high temperature capillarity, including dynamics of high temperature spreading [6]. New educational tools have recently emerged for providing instruction in wetting

Trichoderma Biofertilizer Links to Altered Soil Chemistry, Altered Microbial Communities, and Improved Grassland Biomass.

PubMed

Zhang, Fengge; Huo, Yunqian; Cobb, Adam B; Luo, Gongwen; Zhou, Jiqiong; Yang, Gaowen; Wilson, Gail W T; Zhang, Yingjun

2018-01-01

In grasslands, forage and livestock production results in soil nutrient deficits as grasslands typically receive no nutrient inputs, leading to a loss of grassland biomass. The application of mature compost has been shown to effectively increase grassland nutrient availability. However, research on fertilization regime influence and potential microbial ecological regulation mechanisms are rarely conducted in grassland soil. We conducted a two-year experiment in meadow steppe grasslands, focusing on above- and belowground consequences of organic or Trichoderma biofertilizer applications and potential soil microbial ecological mechanisms underlying soil chemistry and microbial community responses. Grassland biomass significantly ( p = 0.019) increased following amendment with 9,000 kg ha -1 of Trichoderma biofertilizer (composted cattle manure + inoculum) compared with other assessed organic or biofertilizer rates, except for BOF3000 (fertilized with 3,000 kg ha -1 biofertilizer). This rate of Trichoderma biofertilizer treatment increased soil antifungal compounds that may suppress pathogenic fungi, potentially partially responsible for improved grassland biomass. Nonmetric multidimensional scaling (NMDS) revealed soil chemistry and fungal communities were all separated by different fertilization regime. Trichoderma biofertilizer (9,000 kg ha -1 ) increased relative abundances of Archaeorhizomyces and Trichoderma while decreasing Ophiosphaerella . Trichoderma can improve grassland biomass, while Ophiosphaerella has the opposite effect as it may secrete metabolites causing grass necrosis. Correlations between soil properties and microbial genera showed plant-available phosphorus may influence grassland biomass by increasing Archaeorhizomyces and Trichoderma while reducing Ophiosphaerella . According to our structural equation modeling (SEM), Trichoderma abundance was the primary contributor to aboveground grassland biomass. Our results suggest Trichoderma

Trichoderma Biofertilizer Links to Altered Soil Chemistry, Altered Microbial Communities, and Improved Grassland Biomass

PubMed Central

Zhang, Fengge; Huo, Yunqian; Cobb, Adam B.; Luo, Gongwen; Zhou, Jiqiong; Yang, Gaowen; Wilson, Gail W. T.; Zhang, Yingjun

2018-01-01

In grasslands, forage and livestock production results in soil nutrient deficits as grasslands typically receive no nutrient inputs, leading to a loss of grassland biomass. The application of mature compost has been shown to effectively increase grassland nutrient availability. However, research on fertilization regime influence and potential microbial ecological regulation mechanisms are rarely conducted in grassland soil. We conducted a two-year experiment in meadow steppe grasslands, focusing on above- and belowground consequences of organic or Trichoderma biofertilizer applications and potential soil microbial ecological mechanisms underlying soil chemistry and microbial community responses. Grassland biomass significantly (p = 0.019) increased following amendment with 9,000 kg ha−1 of Trichoderma biofertilizer (composted cattle manure + inoculum) compared with other assessed organic or biofertilizer rates, except for BOF3000 (fertilized with 3,000 kg ha−1 biofertilizer). This rate of Trichoderma biofertilizer treatment increased soil antifungal compounds that may suppress pathogenic fungi, potentially partially responsible for improved grassland biomass. Nonmetric multidimensional scaling (NMDS) revealed soil chemistry and fungal communities were all separated by different fertilization regime. Trichoderma biofertilizer (9,000 kg ha−1) increased relative abundances of Archaeorhizomyces and Trichoderma while decreasing Ophiosphaerella. Trichoderma can improve grassland biomass, while Ophiosphaerella has the opposite effect as it may secrete metabolites causing grass necrosis. Correlations between soil properties and microbial genera showed plant-available phosphorus may influence grassland biomass by increasing Archaeorhizomyces and Trichoderma while reducing Ophiosphaerella. According to our structural equation modeling (SEM), Trichoderma abundance was the primary contributor to aboveground grassland biomass. Our results suggest Trichoderma biofertilizer

Modification of Susceptible and Toxic Herbs on Grassland Disease.

PubMed

Yao, Xiang; Fan, Yubing; Chai, Qing; Johnson, Richard D; Nan, Zhibiao; Li, Chunjie

2016-09-16

Recent research shows that continuous overgrazing not only causes grassland biodiversity to decline, but also causes light fungal disease. Achnatherum inebrians is susceptible to fungal diseases and increases in prevalence during over grazing due its toxicity to livestock. This study aimed to examine the effects of A. inebrians on biological control organisms and levels of plant diseases in overgrazed grasslands in northwestern China. The results showed that A. inebrians plants were seriously infected by fungal diseases and that this led to a high incidence of the mycoparasitic species Ampelomyces quisqualis and Sphaerellopsis filum. In addition, the fungivore, Aleocharinae, was found only in the soil growing A. inebrians rather than in the overgrazed area without A. inebrians. Overall, in an overgrazed grassland fenced for one year, disease levels in blocks without A. inebrians were significantly higher than those in blocks with A. inebrians. Our findings indicated that the disease susceptible, toxic A. inebrians can help control plant disease levels in overgrazed grasslands.

Modification of Susceptible and Toxic Herbs on Grassland Disease

PubMed Central

Yao, Xiang; Fan, Yubing; Chai, Qing; Johnson, Richard D.; Nan, Zhibiao; Li, Chunjie

2016-01-01

Recent research shows that continuous overgrazing not only causes grassland biodiversity to decline, but also causes light fungal disease. Achnatherum inebrians is susceptible to fungal diseases and increases in prevalence during over grazing due its toxicity to livestock. This study aimed to examine the effects of A. inebrians on biological control organisms and levels of plant diseases in overgrazed grasslands in northwestern China. The results showed that A. inebrians plants were seriously infected by fungal diseases and that this led to a high incidence of the mycoparasitic species Ampelomyces quisqualis and Sphaerellopsis filum. In addition, the fungivore, Aleocharinae, was found only in the soil growing A. inebrians rather than in the overgrazed area without A. inebrians. Overall, in an overgrazed grassland fenced for one year, disease levels in blocks without A. inebrians were significantly higher than those in blocks with A. inebrians. Our findings indicated that the disease susceptible, toxic A. inebrians can help control plant disease levels in overgrazed grasslands. PMID:27633060

Estimated historical distribution of grassland communities of the Southern Great Plains

USGS Publications Warehouse

Reese, Gordon C.; Manier, Daniel J.; Carr, Natasha B.; Callan, Ramana; Leinwand, Ian I.F.; Assal, Timothy J.; Burris, Lucy; Ignizio, Drew A.

2016-12-07

The purpose of this project was to map the estimated distribution of grassland communities of the Southern Great Plains prior to Euro-American settlement. The Southern Great Plains Rapid Ecoregional Assessment (REA), under the direction of the Bureau of Land Management and the Great Plains Landscape Conservation Cooperative, includes four ecoregions: the High Plains, Central Great Plains, Southwestern Tablelands, and the Nebraska Sand Hills. The REA advisors and stakeholders determined that the mapping accuracy of available national land-cover maps was insufficient in many areas to adequately address management questions for the REA. Based on the recommendation of the REA stakeholders, we estimated the potential historical distribution of 10 grassland communities within the Southern Great Plains project area using data on soils, climate, and vegetation from the Natural Resources Conservation Service (NRCS) including the Soil Survey Geographic Database (SSURGO) and Ecological Site Information System (ESIS). The dominant grassland communities of the Southern Great Plains addressed as conservation elements for the REA area are shortgrass, mixed-grass, and sand prairies. We also mapped tall-grass, mid-grass, northwest mixed-grass, and cool season bunchgrass prairies, saline and foothill grasslands, and semi-desert grassland and steppe. Grassland communities were primarily defined using the annual productivity of dominant species in the ESIS data. The historical grassland community classification was linked to the SSURGO data using vegetation types associated with the predominant component of mapped soil units as defined in the ESIS data. We augmented NRCS data with Landscape Fire and Resource Management Planning Tools (LANDFIRE) Biophysical Settings classifications 1) where NRCS data were unavailable and 2) where fifth-level watersheds intersected the boundary of the High Plains ecoregion in Wyoming. Spatial data representing the estimated historical distribution of

Grassland biodiversity can pay.

PubMed

Binder, Seth; Isbell, Forest; Polasky, Stephen; Catford, Jane A; Tilman, David

2018-04-10

The biodiversity-ecosystem functioning (BEF) literature provides strong evidence of the biophysical basis for the potential profitability of greater diversity but does not address questions of optimal management. BEF studies typically focus on the ecosystem outputs produced by randomly assembled communities that only differ in their biodiversity levels, measured by indices such as species richness. Landholders, however, do not randomly select species to plant; they choose particular species that collectively maximize profits. As such, their interest is not in comparing the average performance of randomly assembled communities at each level of biodiversity but rather comparing the best-performing communities at each diversity level. Assessing the best-performing mixture requires detailed accounting of species' identities and relative abundances. It also requires accounting for the financial cost of individual species' seeds, and the economic value of changes in the quality, quantity, and variability of the species' collective output-something that existing multifunctionality indices fail to do. This study presents an assessment approach that integrates the relevant factors into a single, coherent framework. It uses ecological production functions to inform an economic model consistent with the utility-maximizing decisions of a potentially risk-averse private landowner. We demonstrate the salience and applicability of the framework using data from an experimental grassland to estimate production relationships for hay and carbon storage. For that case, our results suggest that even a risk-neutral, profit-maximizing landowner would favor a highly diverse mix of species, with optimal species richness falling between the low levels currently found in commercial grasslands and the high levels found in natural grasslands.

Wet meadows

Treesearch

Jonathan W. Long; Karen Pope

2014-01-01

Wet meadows help to sustain favorable water flows, biological diversity, and other values; consequently, restoration of degraded wet meadows is an important part of a strategy for promoting socioecological resilience. This chapter focuses on high-elevation wet meadows that are associated with streams; thus restoration of such meadows may be considered a subset of...

[Wet work].

PubMed

Kieć-Swierczyńska, Marta; Chomiczewska, Dorota; Krecisz, Beata

2010-01-01

Wet work is one of the most important risk factors of occupational skin diseases. Exposure of hands to the wet environment for more than 2 hours daily, wearing moisture-proof protective gloves for a corresponding period of time or necessity to wash hands frequently lead to the disruption of epidermal stratum corneum, damage to skin barrier function and induction of irritant contact dermatitis. It may also promote penetration of allergens into the skin and increase the risk of sensitization to occupational allergens. Exposure to wet work plays a significant role in occupations, such as hairdressers and barbers, nurses and other health care workers, cleaning staff, food handlers and metalworkers. It is more common among women because many occupations involving wet work are female-dominated. The incidence of wet-work-induced occupational skin diseases can be reduced by taking appropriate preventive measures. These include identification of high-risk groups, education of workers, organization of work enabling to minimize the exposure to wet work, use of personal protective equipment and skin care after work.

Soil moisture and soil temperature variability among three plant communities in a High Arctic Lake Basin

NASA Astrophysics Data System (ADS)

Davis, M. L.; Konkel, J.; Welker, J. M.; Schaeffer, S. M.

2017-12-01

Soil moisture and soil temperature are critical to plant community distribution and soil carbon cycle processes in High Arctic tundra. As environmental drivers of soil biochemical processes, the predictability of soil moisture and soil temperature by vegetation zone in High Arctic landscapes has significant implications for the use of satellite imagery and vegetation distribution maps to estimate of soil gas flux rates. During the 2017 growing season, we monitored soil moisture and soil temperature weekly at 48 sites in dry tundra, moist tundra, and wet grassland vegetation zones in a High Arctic lake basin. Soil temperature in all three communities reflected fluctuations in air temperature throughout the season. Mean soil temperature was highest in the dry tundra community at 10.5±0.6ºC, however, did not differ between moist tundra and wet grassland communities (2.7±0.6 and 3.1±0.5ºC, respectively). Mean volumetric soil moisture differed significantly among all three plant communities with the lowest and highest soil moisture measured in the dry tundra and wet grassland (30±1.2 and 65±2.7%), respectively. For all three communities, soil moisture was highest during the early season snow melt. Soil moisture in wet grassland remained high with no significant change throughout the season, while significant drying occurred in dry tundra. The most significant change in soil moisture was measured in moist tundra, ranging from 61 to 35%. Our results show different gradients in soil moisture variability within each plant community where: 1) soil moisture was lowest in dry tundra with little change, 2) highest in wet grassland with negligible change, and 3) variable in moist tundra which slowly dried but remained moist. Consistently high soil moisture in wet grassland restricts this plant community to areas with no significant drying during summer. The moist tundra occupies the intermediary areas between wet grassland and dry tundra and experiences the widest range

Effects of temperature and precipitation on grassland bird nesting success as mediated by patch size.

PubMed

Zuckerberg, Benjamin; Ribic, Christine A; McCauley, Lisa A

2018-02-06

Grassland birds are declining faster than any other bird guild across North America. Shrinking ranges and population declines are attributed to widespread habitat loss and increasingly fragmented landscapes of agriculture and other land uses that are misaligned with grassland bird conservation. Concurrent with habitat loss and degradation, temperate grasslands have been disproportionally affected by climate change relative to most other terrestrial biomes. Distributions of grassland birds often correlate with gradients in climate, but few researchers have explored the consequences of weather on the demography of grassland birds inhabiting a range of grassland fragments. To do so, we modeled the effects of temperature and precipitation on nesting success rates of 12 grassland bird species inhabiting a range of grassland patches across North America (21,000 nests from 81 individual studies). Higher amounts of precipitation in the preceding year were associated with higher nesting success, but wetter conditions during the active breeding season reduced nesting success. Extremely cold or hot conditions during the early breeding season were associated with lower rates of nesting success. The direct and indirect influence of temperature and precipitation on nesting success was moderated by grassland patch size. The positive effects of precipitation in the preceding year on nesting success were strongest in relatively small grassland patches and had little effect in large patches. Conversely, warm temperatures reduced nesting success in small grassland patches but increased nesting success in large patches. Mechanisms underlying these differences may be patch-size-induced variation in microclimates and predator activity. Although the exact cause is unclear, large grassland patches, the most common metric of grassland conservation, appears to moderate the effects of weather on grassland-bird demography and could be an effective component of climate-change adaptation. �

Convergence of potential net ecosystem production among contrasting C3 grasslands

PubMed Central

Peichl, Matthias; Sonnentag, Oliver; Wohlfahrt, Georg; Flanagan, Lawrence B.; Baldocchi, Dennis D.; Kiely, Gerard; Galvagno, Marta; Gianelle, Damiano; Marcolla, Barbara; Pio, Casimiro; Migliavacca, Mirco; Jones, Michael B.; Saunders, Matthew

2013-01-01

Metabolic theory and body size dependent constraints on biomass production and decomposition suggest that differences in the intrinsic potential net ecosystem production (NEPPOT) should be small among contrasting C3 grasslands and therefore unable to explain the wide range in the annual apparent net ecosystem production (NEPAPP) reported by previous studies. We estimated NEPPOT for nine C3 grasslands under contrasting climate and management regimes using multi-year eddy covariance data. NEPPOT converged within a narrow range suggesting little difference in the net carbon dioxide uptake capacity across C3 grasslands. Our results indicate a unique feature of C3 grasslands compared to other terrestrial ecosystems and suggest a state of stability in NEPPOT due to tightly coupled production and respiration processes. Consequently, the annual NEPAPP of C3 grasslands is primarily a function of seasonal and short-term environmental and management constraints, and therefore especially susceptible to changes in future climate patterns and associated adaptation of management practices. PMID:23346985

Impacts of Tree Rows on Grassland Birds and Potential Nest Predators: A Removal Experiment

PubMed Central

Ellison, Kevin S.; Ribic, Christine A.; Sample, David W.; Fawcett, Megan J.; Dadisman, John D.

2013-01-01

Globally, grasslands and the wildlife that inhabit them are widely imperiled. Encroachment by shrubs and trees has widely impacted grasslands in the past 150 years. In North America, most grassland birds avoid nesting near woody vegetation. Because woody vegetation fragments grasslands and potential nest predator diversity and abundance is often greater along wooded edge and grassland transitions, we measured the impacts of removing rows of trees and shrubs that intersected grasslands on potential nest predators and the three most abundant grassland bird species (Henslow’s sparrow [Ammodramus henslowii], Eastern meadowlark [Sturnella magna], and bobolink [Dolichonyx oryzivorus]) at sites in Wisconsin, U.S.A. We monitored 3 control and 3 treatment sites, for 1 yr prior to and 3 yr after tree row removal at the treatment sites. Grassland bird densities increased (2–4 times for bobolink and Henslow’s sparrow) and nesting densities increased (all 3 species) in the removal areas compared to control areas. After removals, Henslow’s sparrows nested within ≤50 m of the treatment area, where they did not occur when tree rows were present. Most dramatically, activity by woodland-associated predators nearly ceased (nine-fold decrease for raccoon [Procyon lotor]) at the removals and grassland predators increased (up to 27 times activity for thirteen-lined ground squirrel [Ictidomys tridecemlineatus]). Nest success did not increase, likely reflecting the increase in grassland predators. However, more nests were attempted by all 3 species (175 versus 116) and the number of successful nests for bobolinks and Henslow’s sparrows increased. Because of gains in habitat, increased use by birds, greater production of young, and the effective removal of woodland-associated predators, tree row removal, where appropriate based on the predator community, can be a beneficial management action for conserving grassland birds and improving fragmented and degraded grassland

Impacts of tree rows on grassland birds and potential nest predators: a removal experiment.

PubMed

Ellison, Kevin S; Ribic, Christine A; Sample, David W; Fawcett, Megan J; Dadisman, John D

2013-01-01

Globally, grasslands and the wildlife that inhabit them are widely imperiled. Encroachment by shrubs and trees has widely impacted grasslands in the past 150 years. In North America, most grassland birds avoid nesting near woody vegetation. Because woody vegetation fragments grasslands and potential nest predator diversity and abundance is often greater along wooded edge and grassland transitions, we measured the impacts of removing rows of trees and shrubs that intersected grasslands on potential nest predators and the three most abundant grassland bird species (Henslow's sparrow [Ammodramus henslowii], Eastern meadowlark [Sturnella magna], and bobolink [Dolichonyx oryzivorus]) at sites in Wisconsin, U.S.A. We monitored 3 control and 3 treatment sites, for 1 yr prior to and 3 yr after tree row removal at the treatment sites. Grassland bird densities increased (2-4 times for bobolink and Henslow's sparrow) and nesting densities increased (all 3 species) in the removal areas compared to control areas. After removals, Henslow's sparrows nested within ≤50 m of the treatment area, where they did not occur when tree rows were present. Most dramatically, activity by woodland-associated predators nearly ceased (nine-fold decrease for raccoon [Procyon lotor]) at the removals and grassland predators increased (up to 27 times activity for thirteen-lined ground squirrel [Ictidomys tridecemlineatus]). Nest success did not increase, likely reflecting the increase in grassland predators. However, more nests were attempted by all 3 species (175 versus 116) and the number of successful nests for bobolinks and Henslow's sparrows increased. Because of gains in habitat, increased use by birds, greater production of young, and the effective removal of woodland-associated predators, tree row removal, where appropriate based on the predator community, can be a beneficial management action for conserving grassland birds and improving fragmented and degraded grassland ecosystems.

Key challenges and priorities for modelling European grasslands under climate change.

PubMed

Kipling, Richard P; Virkajärvi, Perttu; Breitsameter, Laura; Curnel, Yannick; De Swaef, Tom; Gustavsson, Anne-Maj; Hennart, Sylvain; Höglind, Mats; Järvenranta, Kirsi; Minet, Julien; Nendel, Claas; Persson, Tomas; Picon-Cochard, Catherine; Rolinski, Susanne; Sandars, Daniel L; Scollan, Nigel D; Sebek, Leon; Seddaiu, Giovanna; Topp, Cairistiona F E; Twardy, Stanislaw; Van Middelkoop, Jantine; Wu, Lianhai; Bellocchi, Gianni

2016-10-01

Grassland-based ruminant production systems are integral to sustainable food production in Europe, converting plant materials indigestible to humans into nutritious food, while providing a range of environmental and cultural benefits. Climate change poses significant challenges for such systems, their productivity and the wider benefits they supply. In this context, grassland models have an important role in predicting and understanding the impacts of climate change on grassland systems, and assessing the efficacy of potential adaptation and mitigation strategies. In order to identify the key challenges for European grassland modelling under climate change, modellers and researchers from across Europe were consulted via workshop and questionnaire. Participants identified fifteen challenges and considered the current state of modelling and priorities for future research in relation to each. A review of literature was undertaken to corroborate and enrich the information provided during the horizon scanning activities. Challenges were in four categories relating to: 1) the direct and indirect effects of climate change on the sward 2) climate change effects on grassland systems outputs 3) mediation of climate change impacts by site, system and management and 4) cross-cutting methodological issues. While research priorities differed between challenges, an underlying theme was the need for accessible, shared inventories of models, approaches and data, as a resource for stakeholders and to stimulate new research. Developing grassland models to effectively support efforts to tackle climate change impacts, while increasing productivity and enhancing ecosystem services, will require engagement with stakeholders and policy-makers, as well as modellers and experimental researchers across many disciplines. The challenges and priorities identified are intended to be a resource 1) for grassland modellers and experimental researchers, to stimulate the development of new research

Extensive Management Promotes Plant and Microbial Nitrogen Retention in Temperate Grassland

PubMed Central

de Vries, Franciska T.; Bloem, Jaap; Quirk, Helen; Stevens, Carly J.; Bol, Roland; Bardgett, Richard D.

2012-01-01

Leaching losses of nitrogen (N) from soil and atmospheric N deposition have led to widespread changes in plant community and microbial community composition, but our knowledge of the factors that determine ecosystem N retention is limited. A common feature of extensively managed, species-rich grasslands is that they have fungal-dominated microbial communities, which might reduce soil N losses and increase ecosystem N retention, which is pivotal for pollution mitigation and sustainable food production. However, the mechanisms that underpin improved N retention in extensively managed, species-rich grasslands are unclear. We combined a landscape-scale field study and glasshouse experiment to test how grassland management affects plant and soil N retention. Specifically, we hypothesised that extensively managed, species-rich grasslands of high conservation value would have lower N loss and greater N retention than intensively managed, species-poor grasslands, and that this would be due to a greater immobilisation of N by a more fungal-dominated microbial community. In the field study, we found that extensively managed, species-rich grasslands had lower N leaching losses. Soil inorganic N availability decreased with increasing abundance of fungi relative to bacteria, although the best predictor of soil N leaching was the C/N ratio of aboveground plant biomass. In the associated glasshouse experiment we found that retention of added 15N was greater in extensively than in intensively managed grasslands, which was attributed to a combination of greater root uptake and microbial immobilisation of 15N in the former, and that microbial immobilisation increased with increasing biomass and abundance of fungi. These findings show that grassland management affects mechanisms of N retention in soil through changes in root and microbial uptake of N. Moreover, they support the notion that microbial communities might be the key to improved N retention through tightening linkages

The future of arid grasslands: identifying issues, seeking solutions

Treesearch

Barbara Tallman; Deborah M. Finch; Carl Edminster; Robert Hamre

1998-01-01

This conference was designed to provide a non-confrontational setting for a variety of people from differing viewpoints to discuss the threats facing arid grasslands of the Southwest. Participants included ranchers and other private economists, scientists, and students. The sessions were organized around the major themes of understanding grasslands, identifying...

Chicken Farming in Grassland Increases Environmental Sustainability and Economic Efficiency

PubMed Central

Liu, Meizhen; Wang, Bingxue; Osborne, Colin P.; Jiang, Gaoming

2013-01-01

Background Grassland degradation caused by overgrazing poses a threat to both animal husbandry and environmental sustainability in most semi-arid areas especially north China. Although the Chinese Government has made huge efforts to restore degraded grasslands, a considerable attempt has unfortunately failed due to an inadequate consideration of economic benefits to local communities. Methodology/Principal Findings A controlled field experiment was conducted to test our hypothesis that utilizing natural grasslands as both habitat and feed resources for chickens and replacing the traditional husbandry system with chicken farming would increase environmental sustainability and raise income. Aboveground plant biomass elevated from 25 g m−2 for grazing sheep to 84 g m−2 for chicken farming. In contrast to the fenced (unstocked) grassland, chicken farming did not significantly decrease aboveground plant biomass, but did increase the root biomass by 60% (p<0.01). Compared with traditional sheep grazing, chicken farming significantly improved soil surface water content (0–10 cm), from 5% to 15%. Chicken farming did not affect the soil bulk density, while the traditional sheep grazing increased the soil bulk density in the 0–10 cm soil layer by 35% of the control (p<0.05). Most importantly, the economic income of local herdsmen has been raised about six times compared with the traditional practice of raising sheep. Ecologically, such an innovative solution allowed large degraded grasslands to naturally regenerate. Grasslands also provided a high quality organic poultry product which could be marketed in big cities. Conclusion/Significance Chicken farming is an innovative alternative strategy for increasing environmental sustainability and economic income, rather than a challenge to the traditional nomadic pastoral system. Our approach might be technically applicable to other large degraded grasslands of the world, especially in China. PMID:23372678

Chicken farming in grassland increases environmental sustainability and economic efficiency.

PubMed

Liu, Meizhen; Wang, Bingxue; Osborne, Colin P; Jiang, Gaoming

2013-01-01

Grassland degradation caused by overgrazing poses a threat to both animal husbandry and environmental sustainability in most semi-arid areas especially north China. Although the Chinese Government has made huge efforts to restore degraded grasslands, a considerable attempt has unfortunately failed due to an inadequate consideration of economic benefits to local communities. A controlled field experiment was conducted to test our hypothesis that utilizing natural grasslands as both habitat and feed resources for chickens and replacing the traditional husbandry system with chicken farming would increase environmental sustainability and raise income. Aboveground plant biomass elevated from 25 g m(-2) for grazing sheep to 84 g m(-2) for chicken farming. In contrast to the fenced (unstocked) grassland, chicken farming did not significantly decrease aboveground plant biomass, but did increase the root biomass by 60% (p<0.01). Compared with traditional sheep grazing, chicken farming significantly improved soil surface water content (0-10 cm), from 5% to 15%. Chicken farming did not affect the soil bulk density, while the traditional sheep grazing increased the soil bulk density in the 0-10 cm soil layer by 35% of the control (p<0.05). Most importantly, the economic income of local herdsmen has been raised about six times compared with the traditional practice of raising sheep. Ecologically, such an innovative solution allowed large degraded grasslands to naturally regenerate. Grasslands also provided a high quality organic poultry product which could be marketed in big cities. Chicken farming is an innovative alternative strategy for increasing environmental sustainability and economic income, rather than a challenge to the traditional nomadic pastoral system. Our approach might be technically applicable to other large degraded grasslands of the world, especially in China.

[Impacts of Ochotona pallasi disturbance on alpine grassland community characteristics].

PubMed

Zhao, Guo-qin; Li, Guang-yong; Ma, Wen-hu; Zhao, Dian-zhi; Li, Xiao-yan

2013-08-01

Plateau pika is the main fossorial mammal in the alpine grassland in Qinghai Lake Watershed of Northwest China. Based on the field investigation data from 18 alpine grassland quadrats in the Watershed, and by using redundancy analysis (RDA) and the surface fitting offered by 'R-Vegan' , the disturbance intensity of plateau pika (Ochotona pallasi) was classified as four levels. In order to explore the impacts of plateau pika disturbance on the alpine grassland ecosystem and its grazing quality, the community characteristics under different disturbance intensities by plateau pika were analyzed, and a conceptual model about the alpine grassland community succession was proposed. The results showed that with the increase of the disturbance intensity, the dominant species changed from Juncus roemerianus to Poa pratensis and Laux maritima. When the disturbance was small, the community had high quantitative values of coverage, aboveground biomass, biodiversity, and species richness, but the proportion of weeds was also high. When the disturbance was large, the quantitative values were the lowest, while the proportion of weeds was the highest. When the disturbance was moderate, the community had relatively high quantitative values, and the proportion of grasses and sedges was the highest. It was concluded that the community' s characteristic values under low plateau pika disturbance intensity were high but the grazing quality was low, while high disturbance intensity resulted in the grassland degradation. Therefore, the disturbance intensity in the threshold could maintain the stability of alpine grassland ecosystem and improve its grazing quality.

Area sensitivity in North American grassland birds: Patterns and processes

USGS Publications Warehouse

Ribic, C.A.; Koford, Rolf R.; Herkert, J.R.; Johnson, D.H.; Niemuth, N.D.; Naugle, D.E.; Bakker, K.K.; Sample, D.W.; Renfrew, R.B.

2009-01-01

Grassland birds have declined more than other bird groups in North America in the past 35-40 years (Vickery and Herkert 2001, Sauer et al. 2008), prompting a wide variety of research aimed at understanding these declines, as well as conservation programs trying to reverse the declines (Askins et al. 2007). Area sensitivity, whereby the pattern of a species’ occurrence and density increases with patch area (Robbins et al. 1989), has been invoked as an important issue in grassland-bird conservation, and understanding the processes that drive area sensitivity in grassland birds is a major conservation need (Vickery and Herkert 2001). Here, we review the literature on North American grassland bird species that is relevant to the following questions: (1) What is the evidence for area sensitivity in grassland birds? (2) What are the historical explanations for area sensitivity? (3) What ecological processes could produce area sensitivity? And (5) what are the conservation implications of knowing the processes behind area sensitivity? Because of space limitations, we could not cite every paper we reviewed; the cited papers are given as examples of the literature in this field

Balancing forest-regeneration probabilities and maintenance costs in dry grasslands of high conservation priority

USGS Publications Warehouse

Bolliger, Janine; Edwards, Thomas C.; Eggenberg, Stefan; Ismail, Sascha; Seidl, Irmi; Kienast, Felix

2011-01-01

Abandonment of agricultural land has resulted in forest regeneration in species-rich dry grasslands across European mountain regions and threatens conservation efforts in this vegetation type. To support national conservation strategies, we used a site-selection algorithm (MARXAN) to find optimum sets of floristic regions (reporting units) that contain grasslands of high conservation priority. We sought optimum sets that would accommodate 136 important dry-grassland species and that would minimize forest regeneration and costs of management needed to forestall predicted forest regeneration. We did not consider other conservation elements of dry grasslands, such as animal species richness, cultural heritage, and changes due to climate change. Optimal sets that included 95–100% of the dry grassland species encompassed an average of 56–59 floristic regions (standard deviation, SD 5). This is about 15% of approximately 400 floristic regions that contain dry-grassland sites and translates to 4800–5300 ha of dry grassland out of a total of approximately 23,000 ha for the entire study area. Projected costs to manage the grasslands in these optimum sets ranged from CHF (Swiss francs) 5.2 to 6.0 million/year. This is only 15–20% of the current total estimated cost of approximately CHF30–45 million/year required if all dry grasslands were to be protected. The grasslands of the optimal sets may be viewed as core sites in a national conservation strategy.

Grassland productivity limited by multiple nutrients.

PubMed

Fay, Philip A; Prober, Suzanne M; Harpole, W Stanley; Knops, Johannes M H; Bakker, Jonathan D; Borer, Elizabeth T; Lind, Eric M; MacDougall, Andrew S; Seabloom, Eric W; Wragg, Peter D; Adler, Peter B; Blumenthal, Dana M; Buckley, Yvonne M; Chu, Chengjin; Cleland, Elsa E; Collins, Scott L; Davies, Kendi F; Du, Guozhen; Feng, Xiaohui; Firn, Jennifer; Gruner, Daniel S; Hagenah, Nicole; Hautier, Yann; Heckman, Robert W; Jin, Virginia L; Kirkman, Kevin P; Klein, Julia; Ladwig, Laura M; Li, Qi; McCulley, Rebecca L; Melbourne, Brett A; Mitchell, Charles E; Moore, Joslin L; Morgan, John W; Risch, Anita C; Schütz, Martin; Stevens, Carly J; Wedin, David A; Yang, Louie H

2015-07-06

Terrestrial ecosystem productivity is widely accepted to be nutrient limited(1). Although nitrogen (N) is deemed a key determinant of aboveground net primary production (ANPP)(2,3), the prevalence of co-limitation by N and phosphorus (P) is increasingly recognized(4-8). However, the extent to which terrestrial productivity is co-limited by nutrients other than N and P has remained unclear. Here, we report results from a standardized factorial nutrient addition experiment, in which we added N, P and potassium (K) combined with a selection of micronutrients (K+μ), alone or in concert, to 42 grassland sites spanning five continents, and monitored ANPP. Nutrient availability limited productivity at 31 of the 42 grassland sites. And pairwise combinations of N, P, and K+μ co-limited ANPP at 29 of the sites. Nitrogen limitation peaked in cool, high latitude sites. Our findings highlight the importance of less studied nutrients, such as K and micronutrients, for grassland productivity, and point to significant variations in the type and degree of nutrient limitation. We suggest that multiple-nutrient constraints must be considered when assessing the ecosystem-scale consequences of nutrient enrichment.

Rapid Decline of a Grassland System and Its Ecological and Conservation Implications

PubMed Central

Ceballos, Gerardo; Davidson, Ana; List, Rurik; Pacheco, Jesús; Manzano-Fischer, Patricia; Santos-Barrera, Georgina; Cruzado, Juan

2010-01-01

One of the most important conservation issues in ecology is the imperiled state of grassland ecosystems worldwide due to land conversion, desertification, and the loss of native populations and species. The Janos region of northwestern Mexico maintains one of the largest remaining black-tailed prairie dog (Cynomys ludovicianus) colony complexes in North America and supports a high diversity of threatened and endangered species. Yet, cattle grazing, agriculture, and drought have greatly impacted the region. We evaluated the impact of human activities on the Janos grasslands, comparing changes in the vertebrate community over the last two decades. Our results reveal profound, rapid changes in the Janos grassland community, demonstrating large declines in vertebrate abundance across all taxonomic groups. We also found that the 55,000 ha prairie dog colony complex has declined by 73% since 1988. The prairie dog complex has become increasingly fragmented, and their densities have shown a precipitous decline over the years, from an average density of 25 per ha in 1988 to 2 per ha in 2004. We demonstrated that prairie dogs strongly suppressed woody plant encroachment as well as created open grassland habitat by clearing woody vegetation, and found rapid invasion of shrubland once the prairie dogs disappeared from the grasslands. Comparison of grasslands and shrublands showed markedly different species compositions, with species richness being greatest when both habitats were considered together. Our data demonstrate the rapid decline of a grassland ecosystem, and documents the dramatic loss in biodiversity over a very short time period concomitant with anthropogenic grassland degradation and the decline of a keystone species. PMID:20066035

Effects of wind turbines on upland nesting birds in Conservation Reserve Program grasslands

USGS Publications Warehouse

Leddy, K.L.; Higgins, K.F.; Naugle, D.E.

1999-01-01

Grassland passerines were surveyed during summer 1995 on the Buffalo Ridge Wind Resource Area in southwestern Minnesota to determine the relative influence of wind turbines on overall densities of upland nesting birds in Conservation Reserve Program (CRP) grasslands. Birds were surveyed along 40 m fixed width transects that were placed along wind turbine strings within three CRP fields and in three CRP fields without turbines. Conservation Reserve Program grasslands without turbines and areas located 180 m from turbines supported higher densities (261.0-312.5 males/100 ha) of grassland birds than areas within 80 m of turbines (58.2-128.0 males/100 ha). Human disturbance, turbine noise, and physical movements of turbines during operation may have disturbed nesting birds. We recommend that wind turbines be placed within cropland habitats that support lower densities of grassland passerines than those found in CRP grasslands.

How Spatial Heterogeneity of Cover Affects Patterns of Shrub Encroachment into Mesic Grasslands

PubMed Central

Montané, Francesc; Casals, Pere; Dale, Mark R. T.

2011-01-01

We used a multi-method approach to analyze the spatial patterns of shrubs and cover types (plant species, litter or bare soil) in grassland-shrubland ecotones. This approach allows us to assess how fine-scale spatial heterogeneity of cover types affects the patterns of Cytisus balansae shrub encroachment into mesic mountain grasslands (Catalan Pyrenees, Spain). Spatial patterns and the spatial associations between juvenile shrubs and different cover types were assessed in mesic grasslands dominated by species with different palatabilities (palatable grass Festuca nigrescens and unpalatable grass Festuca eskia). A new index, called RISES (“Relative Index of Shrub Encroachment Susceptibility”), was proposed to calculate the chances of shrub encroachment into a given grassland, combining the magnitude of the spatial associations and the surface area for each cover type. Overall, juveniles showed positive associations with palatable F. nigrescens and negative associations with unpalatable F. eskia, although these associations shifted with shrub development stage. In F. eskia grasslands, bare soil showed a low scale of pattern and positive associations with juveniles. Although the highest RISES values were found in F. nigrescens plots, the number of juvenile Cytisus was similar in both types of grasslands. However, F. nigrescens grasslands showed the greatest number of juveniles in early development stage (i.e. height<10 cm) whereas F. eskia grasslands showed the greatest number of juveniles in late development stages (i.e. height>30 cm). We concluded that in F. eskia grasslands, where establishment may be constrained by the dominant cover type, the low scale of pattern on bare soil may result in higher chances of shrub establishment and survival. In contrast, although grasslands dominated by the palatable F. nigrescens may be more susceptible to shrub establishment; current grazing rates may reduce juvenile survival. PMID:22174858

Landscape composition and habitat area affects butterfly species richness in semi-natural grasslands.

PubMed

Ockinger, Erik; Smith, Henrik G

2006-09-01

During the last 50 years, the distribution and abundance of many European butterfly species associated with semi-natural grasslands have declined. This may be the result of deteriorating habitat quality, but habitat loss, resulting in decreasing area and increasing isolation of remaining habitat, is also predicted to result in reduced species richness. To investigate the effects of habitat loss on species richness, we surveyed butterflies in semi-natural grasslands of similar quality and structure, but situated in landscapes of different habitat composition. Using spatially explicit habitat data, we selected one large (6-10 ha) and one small (0.5-2 ha) grassland site (pasture) in each of 24 non-overlapping 28.2 km(2) landscapes belonging to three categories differing in the proportion of the area that consisted of semi-natural grasslands. After controlling for local habitat quality, species richness was higher in grassland sites situated in landscapes consisting of a high proportion of grasslands. Species richness was also higher in larger grassland sites, and this effect was more pronounced for sedentary than for mobile species. However, the number of species for a given area did not differ between large and small grasslands. There was also a significant relationship between butterfly species richness and habitat quality in the form of vegetation height and abundance of flowers. In contrast, butterfly density was not related to landscape composition or grassland size. When species respond differently to habitat area or landscape composition this leads to effects on community structure, and nestedness analysis showed that depauperate communities were subsets of richer ones. Both grassland area and landscape composition may have contributed to this pattern, implying that small habitat fragments and landscapes with low proportions of habitat are both likely to mainly contain common generalist species. Based on these results, conservation efforts should aim at

Effects of precipitation on grassland ecosystem restoration under grazing exclusion in Inner Mongolia, China

Treesearch

Lu Hao; Ge Sun; Yongqiang Liu; Zhiqiu Gao; Junjie He; Tingting Shi; Bingjuan Wu

2014-01-01

China launched the ‘‘Returning Grazing Lands to Grasslands’’ project about a decade ago to restore severely degraded grasslands. Grassland grazing exclusion was one of the experimental approaches for achieving the grand goal. Here, we evaluate the long-term regional ecological effects of grassland grazing exclusion in the Xilingol region of Inner Mongolia, China. The...

Conceptual ecological model for management of breeding grassland birds in the Mid-Atlantic Region

USGS Publications Warehouse

Peterjohn, Bruce G.

2006-01-01

The status of grassland birds has become an increasingly important conservation issue. These species exhibit the most consistent population declines of any group of North American birds during the past 40 years. Anecdotal evidence suggests these declines have been occurring for nearly a century (Peterjohn and Sauer 1999). While the widespread conversion of grasslands into other habitats contributed to these declining populations, other factors such as habitat fragmentation and mowing regimes are also implicated (Vickery et al. 1999a). This plight of grassland birds has heightened awareness of the need for concerted conservation actions to reverse these seriously declining population trends. The National Park Service (NPS) is positioned to potentially contribute to grassland bird conservation in the Mid-Atlantic Region. The NPS maintains a number of historic sites and former battlefields that are managed for their cultural significance but also support wildlife populations. Many of these “cultural parks” maintain open landscapes to recreate land use patterns that existed at the times of the historical events. These open landscapes are primarily managed grasslands which could be maintained to benefit grassland birds. In 2005, the NPS initiated a project exploring the potential of “cultural parks” to support significant breeding grassland bird communities. This project involved parks within three NPS Inventory and Monitoring Program (I&M) networks, Mid-Atlantic, National Capital, and Eastern Rivers and Mountains. Five parks were selected for the initial focus of this study, all of which maintain open landscapes for interpretation of historic events. Most parks were selected because they represent the most extensive grassland habitats within their networks, with the rationale that if these parks cannot support significant breeding grassland bird communities, then parks with smaller acreages cannot support these communities either. The five parks included in

Seasonal and Spatial Variations of Bulk Nitrogen Deposition and the Impacts on the Carbon Cycle in the Arid/Semiarid Grassland of Inner Mongolia, China.

PubMed

Li, Xianglan; Shi, Huiqiu; Xu, Wenfang; Liu, Wei; Wang, Xiujun; Hou, Longyu; Feng, Fei; Yuan, Wenping; Li, Linghao; Xu, Hua

2015-01-01

Atmospheric nitrogen (N) deposition is an important component that affects the structure and function of different terrestrial ecosystem worldwide. However, much uncertainty still remains concerning the magnitude of N deposition on grassland ecosystem in China. To study the spatial and temporal patterns of bulk N deposition, the levels of N (NH4+-N and NO3--N) concentration in rainfall were measured at 12 sites across a 1200 km grassland transect in Inner Mongolia, China, and the respective N deposition rates were estimated. The inorganic N deposition rates ranged from 4.53 kg N ha-1 to 12.21 kg N ha-1 with a mean value of 8.07 kg N ha-1 during the entire growing season, decreasing steadily from the eastern to the western regions. Inorganic N deposition occurred mainly in July and August across meadow steppe, typical steppe, and desert steppe, which corresponded to the seasonal distribution of mean annual precipitation. A positive relationship was found between inorganic N deposition and mean annual precipitation (R2 = 0.54 ~ 0.72, P < 0.0001) across the grassland transect. Annual estimation of inorganic N deposition was 0.67 Pg yr-1 in Inner Mongolia, China based on the correlation between N deposition rates and precipitation. N deposition was an important factor controlling aboveground biomass and ecosystem respiration, but has no effect on root biomass and soil respiration. We must clarify that we used the bulk deposition samplers during the entire sampling process and estimated the dissolved NH4+-N and NO3--N deposition rates during the entire growing season. Long-term N deposition monitoring networks should be constructed to study the patterns of N deposition and its potential effect on grassland ecosystem, considering various N species, i.e., gaseous N, particle N, and wet N deposition.

Responses of microbial respiration in grazed and ungrazed grasslands to glucose addition

NASA Astrophysics Data System (ADS)

Xu, Xingliang; Liu, Qianyuan; Pang, Rui

2017-04-01

Grazing can change species composition, alter soil properties, and thus modify microbial activities, affecting biogeochemical processes in grasslands. However, it remains unclear how microbial respiration in grazed and ungrazed grasslands responds to glucose addition. Here we hypothesize that microbial respiration in grazed grasslands will respond more strongly to glucose addition than in ungrazed grasslands because moderate grazing can enhance microbial activity. To examine the hypothesis above, we collected the upper 10 cm soil from grazed and ungrazed grasslands at five sites of China. Three sites (Hulunbuir 1, Hulunbuir 2 and Xielingele) were located in Inner Mongolia and two in the Tibet Plateau) Soils were incubated with low glucose input (50% MBC), high glucose input (150% MBC), and water for 60 days in 21oC. CO2 released from soil was trapped with 1 M NaOH. The results showed that the effect of grazing on microbial respiration has two distinct patterns, depending on soil types and addition amount. After glucose addition, cumulative CO2 efflux from grazed soils was significantly higher than from ungrazed soils in two temperate grasslands (Hulunbuir 1 and Xielingele). This may be ascribed to that moderate grazing promoted microbial activity. On the contrary, microbial respirations from grazed soils were lower than ungrazed soils in two alpine meadows of Haibei and Dangxiong and in Hulunbuir 2. This effect of grazing was not obvious in Hulunbeier 2 soils at low carbon addition level. Grazing may decrease soil organic carbon, nitrogen availability and thus microbial activity in alpine grasslands. These findings indicate that soil microorganisms could have different adaptation mechanisms to grazing in temperate and alpine grasslands.

Response of grassland biomass production to simulated climate change and clipping along an elevation gradient.

PubMed

Carlyle, Cameron N; Fraser, Lauchlan H; Turkington, Roy

2014-03-01

Changes in rainfall and temperature regimes are altering plant productivity in grasslands worldwide, and these climate change factors are likely to interact with grassland disturbances, particularly grazing. Understanding how plant production responds to both climate change and defoliation, and how this response varies among grassland types, is important for the long-term sustainability of grasslands. For 4 years, we manipulated temperature [ambient and increased using open-top chambers (OTC)], water (ambient, reduced using rainout shelters and increased using hand watering) and defoliation (clipped, and unclipped) in three grassland types along an elevation gradient. We monitored plant cover and biomass and found that OTC reduced biomass by 15%, but clipping and water treatments interacted with each other and their effects varied in different grassland types. For example, total biomass did not decline in the higher elevation grasslands due to clipping, and water addition mitigated the effects of clipping on subordinate grasses in the lower grasslands. The response of total biomass was driven by dominant plant species while subordinate grasses and forbs showed more variable responses. Overall, our results demonstrate that biomass in the highest elevation grassland was least effected by the treatments and the response of biomass tended to be dependent on interactions between climate change treatments and defoliation. Together, the results suggest that ecosystem function of these grasslands under altered climate patterns will be dependent on site-specific management.

Carbon storage in Chinese grassland ecosystems: Influence of different integrative methods.

PubMed

Ma, Anna; He, Nianpeng; Yu, Guirui; Wen, Ding; Peng, Shunlei

2016-02-17

The accurate estimate of grassland carbon (C) is affected by many factors at the large scale. Here, we used six methods (three spatial interpolation methods and three grassland classification methods) to estimate C storage of Chinese grasslands based on published data from 2004 to 2014, and assessed the uncertainty resulting from different integrative methods. The uncertainty (coefficient of variation, CV, %) of grassland C storage was approximately 4.8% for the six methods tested, which was mainly determined by soil C storage. C density and C storage to the soil layer depth of 100 cm were estimated to be 8.46 ± 0.41 kg C m(-2) and 30.98 ± 1.25 Pg C, respectively. Ecosystem C storage was composed of 0.23 ± 0.01 (0.7%) above-ground biomass, 1.38 ± 0.14 (4.5%) below-ground biomass, and 29.37 ± 1.2 (94.8%) Pg C in the 0-100 cm soil layer. Carbon storage calculated by the grassland classification methods (18 grassland types) was closer to the mean value than those calculated by the spatial interpolation methods. Differences in integrative methods may partially explain the high uncertainty in C storage estimates in different studies. This first evaluation demonstrates the importance of multi-methodological approaches to accurately estimate C storage in large-scale terrestrial ecosystems.

Analysis of predator movement in prairie landscapes with contrasting grassland composition

USGS Publications Warehouse

Phillips, M.L.; Clark, W.R.; Nusser, S.M.; Sovada, M.A.; Greenwood, R.J.

2004-01-01

Mammalian predation influences waterfowl breeding success in the U.S. northern Great Plains, yet little is known about the influence of the landscape on the ability of predators to find waterfowl nests. We used radiotelemetry to record nightly movements of red foxes (Vulpes vulpes) and striped skunks (Mephitis mephitis) in two 41.4-km2 study areas in North Dakota. Study areas contained either 15-20% grassland (low grassland composition) or 45-55% grassland (high grassland composition). Grasslands included planted cover, pastureland, and hayland. We predicted that the type and composition of cover types in the landscape would influence both predator movement across the landscape (as measured by the fractal dimension and displacement ratio) as well as localized movement (as measured by the rate of movement and turning angle between locations) within patches of different cover types. Red fox movements were straighter (lower fractal dimensions and higher displacements) across landscapes with a low grassland composition, indicating directed movement between the more isolated patches of planted cover. Striped skunk movements did not differ between landscape types, illustrating their movement along wetland edges, which had similar compositions in both landscape types. The high variability in turning angles by red fox in planted cover and pastureland in both landscape types is consistent with restricted-area foraging. The high rate of movement by red foxes in planted cover and by striped skunks in wetland edges suggests that spatial memory may influence movement patterns. Understanding the behavior of predators in fragmented prairie landscape is essential for managing breeding habitat for grassland birds and for predicting the spatial and temporal dynamics of predators and their prey.

Establishment of seeded grasslands for wildlife habitat in the prairie pothole region

USGS Publications Warehouse

Duebbert, Harold F.; Jacobson, Erling T.; Higgins, Kenneth F.; Podoll, Erling B.

1981-01-01

Techniques are described for establishment of seeded grasslands on cultivated soils to provide wildlife habitat within the glaciated prairie pothole region in the north-central United States. Management of grassland habitats on a sound ecological basis is an important wildlife management activity in the region. The primary purpose of the guidelines in this publication is to help managers establish and maintain good stands of seeded cover for waterfowl nesting and use by other prairie wildlife. Several options are available for selecting a type of cover to be established. The following seeded grassland types are described: (1) introduced cool-season grasses and legumes; (2) tall, warm-season native grasses; and (3) mixed-grass prairie grasses. Major vegetative species recommended for (1) are tall wheatgrass (Agropyron elongatum), intermediate wheatgrass (A. intermedium), alfalfa (Medicago sativa), and sweetclover (Melilotus spp.); for (2) are big bluestem (Andropogon gerardi), indiangrass (Sorghastrum nutans), and switchgrass (Panicum virgatum); for (3) are green needlegrass (Stipa viridula), little bluestem (Andropogon scoparius), western wheatgrass (Agropyron smithii), and sideoats grama (Bouteloua curtipendula). Important factors that affect the success of establishment of seeded grasslands include site adaptability, site preparation, seedbed preparation, planting equipment and methods, rates and dates of seeding, and seed sources. A management goal for seeded grasslands intended to provide optimum habitat for dabbling duck nesting should be to maintain vigorous stands of vegetation with the tallest, most dense cover form that is possible under prevailing soil and climatic conditions. Grassland management is a never-ending job and seeded grasslands require periodic rejuvenation to maintain them in an optimum condition. Prescribed burning and planned grazing systems are acceptable methods for periodically rejuvenating seeded native grasses. Stands of introduced

Reconstructing grassland fire history using sedimentary charcoal: Considering count, size and shape.

PubMed

Leys, Berangere A; Commerford, Julie L; McLauchlan, Kendra K

2017-01-01

Fire is a key Earth system process, with 80% of annual fire activity taking place in grassland areas. However, past fire regimes in grassland systems have been difficult to quantify due to challenges in interpreting the charcoal signal in depositional environments. To improve reconstructions of grassland fire regimes, it is essential to assess two key traits: (1) charcoal count, and (2) charcoal shape. In this study, we quantified the number of charcoal pieces in 51 sediment samples of ponds in the Great Plains and tested its relevance as a proxy for the fire regime by examining 13 potential factors influencing charcoal count, including various fire regime components (e.g. the fire frequency, the area burned, and the fire season), vegetation cover and pollen assemblages, and climate variables. We also quantified the width to length (W:L) ratio of charcoal particles, to assess its utility as a proxy of fuel types in grassland environments by direct comparison with vegetation cover and pollen assemblages. Our first conclusion is that charcoal particles produced by grassland fires are smaller than those produced by forest fires. Thus, a mesh size of 120μm as used in forested environments is too large for grassland ecosystems. We recommend counting all charcoal particles over 60μm in grasslands and mixed grass-forest environments to increase the number of samples with useful data. Second, a W:L ratio of 0.5 or smaller appears to be an indicator for fuel types, when vegetation surrounding the site is before composed of at least 40% grassland vegetation. Third, the area burned within 1060m of the depositional environments explained both the count and the area of charcoal particles. Therefore, changes in charcoal count or charcoal area through time indicate a change in area burned. The fire regimes of grassland systems, including both human and climatic influences on fire behavior, can be characterized by long-term charcoal records.

Reconstructing grassland fire history using sedimentary charcoal: Considering count, size and shape

PubMed Central

Leys, Berangere A.; Commerford, Julie L.; McLauchlan, Kendra K.

2017-01-01

Fire is a key Earth system process, with 80% of annual fire activity taking place in grassland areas. However, past fire regimes in grassland systems have been difficult to quantify due to challenges in interpreting the charcoal signal in depositional environments. To improve reconstructions of grassland fire regimes, it is essential to assess two key traits: (1) charcoal count, and (2) charcoal shape. In this study, we quantified the number of charcoal pieces in 51 sediment samples of ponds in the Great Plains and tested its relevance as a proxy for the fire regime by examining 13 potential factors influencing charcoal count, including various fire regime components (e.g. the fire frequency, the area burned, and the fire season), vegetation cover and pollen assemblages, and climate variables. We also quantified the width to length (W:L) ratio of charcoal particles, to assess its utility as a proxy of fuel types in grassland environments by direct comparison with vegetation cover and pollen assemblages. Our first conclusion is that charcoal particles produced by grassland fires are smaller than those produced by forest fires. Thus, a mesh size of 120μm as used in forested environments is too large for grassland ecosystems. We recommend counting all charcoal particles over 60μm in grasslands and mixed grass-forest environments to increase the number of samples with useful data. Second, a W:L ratio of 0.5 or smaller appears to be an indicator for fuel types, when vegetation surrounding the site is before composed of at least 40% grassland vegetation. Third, the area burned within 1060m of the depositional environments explained both the count and the area of charcoal particles. Therefore, changes in charcoal count or charcoal area through time indicate a change in area burned. The fire regimes of grassland systems, including both human and climatic influences on fire behavior, can be characterized by long-term charcoal records. PMID:28448597

Climate-driven diversity change in annual grasslands: Drought plus deluge does not equal normal.

PubMed

Harrison, Susan P; LaForgia, Marina L; Latimer, Andrew M

2018-04-01

Climate forecasts agree that increased variability and extremes will tend to reduce the availability of water in many terrestrial ecosystems. Increasingly severe droughts may be exacerbated both by warmer temperatures and by the relative unavailability of water that arrives in more sporadic and intense rainfall events. Using long-term data and an experimental water manipulation, we examined the resilience of a heterogeneous annual grassland community to a prolonged series of dry winters that led to a decline in plant species richness (2000-2014), followed by a near-record wet winter (2016-2017), a climatic sequence that broadly resembles the predicted future in its high variability. In our 80, 5-m 2 observational plots, species richness did not recover in response to the wet winter, and the positive relationship of richness to annual winter rainfall thus showed a significant weakening trend over the 18-year time period. In experiments on 100, 1-m 2 plots, wintertime water supplementation increased and drought shelters decreased the seedling survival and final individual biomass of native annual forbs, the main functional group contributing to the observed long-term decline in richness. Water supplementation also increased the total cover of native annual forbs, but only increased richness within nested subplots to which seeds were also added. We conclude that prolonged dry winters, by increasing seedling mortality and reducing growth of native forbs, may have diminished the seedbank and thus the recovery potential of diversity in this community. However, the wet winter and the watering treatment did cause recovery of the community mean values of a key functional trait (specific leaf area, an indicator of drought intolerance), suggesting that some aggregate community properties may be stabilized by functional redundancy among species. © 2017 John Wiley & Sons Ltd.

Is grazing exclusion effective in restoring vegetation in degraded alpine grasslands in Tibet, China?

PubMed Central

Yan, Yan

2015-01-01

Overgrazing is considered one of the key disturbance factors that results in alpine grassland degradation in Tibet. Grazing exclusion by fencing has been widely used as an approach to restore degraded grasslands in Tibet since 2004. Is the grazing exclusion management strategy effective for the vegetation restoration of degraded alpine grasslands? Three alpine grassland types were selected in Tibet to investigate the effect of grazing exclusion on plant community structure and biomass. Our results showed that species biodiversity indicators, including the Pielou evenness index, the Shannon–Wiener diversity index, and the Simpson dominance index, did not significantly change under grazing exclusion conditions. In contrast, the total vegetation cover, the mean vegetation height of the community, and the aboveground biomass were significantly higher in the grazing exclusion grasslands than in the free grazed grasslands. These results indicated that grazing exclusion is an effective measure for maintaining community stability and improving aboveground vegetation growth in alpine grasslands. However, the statistical analysis showed that the growing season precipitation (GSP) plays a more important role than grazing exclusion in which influence on vegetation in alpine grasslands. In addition, because the results of the present study come from short term (6–8 years) grazing exclusion, it is still uncertain whether these improvements will be continuable if grazing exclusion is continuously implemented. Therefore, the assessments of the ecological effects of the grazing exclusion management strategy on degraded alpine grasslands in Tibet still need long term continued research. PMID:26157607

Is grazing exclusion effective in restoring vegetation in degraded alpine grasslands in Tibet, China?

PubMed

Yan, Yan; Lu, Xuyang

2015-01-01

Overgrazing is considered one of the key disturbance factors that results in alpine grassland degradation in Tibet. Grazing exclusion by fencing has been widely used as an approach to restore degraded grasslands in Tibet since 2004. Is the grazing exclusion management strategy effective for the vegetation restoration of degraded alpine grasslands? Three alpine grassland types were selected in Tibet to investigate the effect of grazing exclusion on plant community structure and biomass. Our results showed that species biodiversity indicators, including the Pielou evenness index, the Shannon-Wiener diversity index, and the Simpson dominance index, did not significantly change under grazing exclusion conditions. In contrast, the total vegetation cover, the mean vegetation height of the community, and the aboveground biomass were significantly higher in the grazing exclusion grasslands than in the free grazed grasslands. These results indicated that grazing exclusion is an effective measure for maintaining community stability and improving aboveground vegetation growth in alpine grasslands. However, the statistical analysis showed that the growing season precipitation (GSP) plays a more important role than grazing exclusion in which influence on vegetation in alpine grasslands. In addition, because the results of the present study come from short term (6-8 years) grazing exclusion, it is still uncertain whether these improvements will be continuable if grazing exclusion is continuously implemented. Therefore, the assessments of the ecological effects of the grazing exclusion management strategy on degraded alpine grasslands in Tibet still need long term continued research.

Legacy effects of grassland management on soil carbon to depth.

PubMed

Ward, Susan E; Smart, Simon M; Quirk, Helen; Tallowin, Jerry R B; Mortimer, Simon R; Shiel, Robert S; Wilby, Andrew; Bardgett, Richard D

2016-08-01

The importance of managing land to optimize carbon sequestration for climate change mitigation is widely recognized, with grasslands being identified as having the potential to sequester additional carbon. However, most soil carbon inventories only consider surface soils, and most large-scale surveys group ecosystems into broad habitats without considering management intensity. Consequently, little is known about the quantity of deep soil carbon and its sensitivity to management. From a nationwide survey of grassland soils to 1 m depth, we show that carbon in grassland soils is vulnerable to management and that these management effects can be detected to considerable depth down the soil profile, albeit at decreasing significance with depth. Carbon concentrations in soil decreased as management intensity increased, but greatest soil carbon stocks (accounting for bulk density differences), were at intermediate levels of management. Our study also highlights the considerable amounts of carbon in subsurface soil below 30 cm, which is missed by standard carbon inventories. We estimate grassland soil carbon in Great Britain to be 2097 Tg C to a depth of 1 m, with ~60% of this carbon being below 30 cm. Total stocks of soil carbon (t ha(-1) ) to 1 m depth were 10.7% greater at intermediate relative to intensive management, which equates to 10.1 t ha(-1) in surface soils (0-30 cm), and 13.7 t ha(-1) in soils from 30 to 100 cm depth. Our findings highlight the existence of substantial carbon stocks at depth in grassland soils that are sensitive to management. This is of high relevance globally, given the extent of land cover and large stocks of carbon held in temperate managed grasslands. Our findings have implications for the future management of grasslands for carbon storage and climate mitigation, and for global carbon models which do not currently account for changes in soil carbon to depth with management. © 2016 John Wiley & Sons Ltd.

Spillover from adjacent crop and forest habitats shapes carabid beetle assemblages in fragmented semi-natural grasslands.

PubMed

Schneider, Gudrun; Krauss, Jochen; Boetzl, Fabian A; Fritze, Michael-Andreas; Steffan-Dewenter, Ingolf

2016-12-01

Semi-natural grasslands in Europe are insect biodiversity hotspots and important source habitats delivering ecosystem services to adjacent agricultural land by species spillover. However, this spillover might also occur in the opposite direction, affecting the diversity of semi-natural grasslands. This opposite spillover has got little attention in scientific literature even though generalist species penetrating into the grasslands can affect local biotic interactions, community composition and the conservation value of grassland habitats. In this study, we examined spillover effects from two different adjacent habitat types on carabid beetle assemblages in 20 semi-natural calcareous grasslands. The grasslands were either adjacent to a cereal crop field or to a coniferous forest. We found distinct differences in carabid beetle assemblages in calcareous grasslands depending on adjacent habitat type. Species richness and activity density were higher, but the evenness was lower in calcareous grasslands adjacent to crop fields compared with calcareous grasslands adjacent to coniferous forests. Further, we found a strong spillover of carabid beetles from adjacent crop fields after crop harvest, which may result in transiently increased predation pressure and resource competition in calcareous grasslands. Our results highlight that species composition, diversity and presumably ecosystem functions within semi-natural habitats are affected by the type and management of surrounding habitats. This needs to be considered by nature conservation measures, which aim to protect the unique insect communities of semi-natural European grasslands.

Factors Limiting the Establishment of a Chaparral Oak, Quercus durata Jeps., in Grassland

Treesearch

Kimberlyn Williams; Stephen D. Davis; Barbara L. Gartner; Staffan Karlsson

1991-01-01

We studied factors that restrict colonization of grassland by Quercus durata Jeps., an oak commonly found in chaparral on serpentine soils. The study site contained a chaparral/ grassland border that had been stable for at least 50 years. Monitoring of acorns planted in the chaparral understory and grassland revealed that, although initial seedling...

Microbial decomposition of dead grassland roots and its influence on the carbon cycle under changing precipitation patterns

NASA Astrophysics Data System (ADS)

Becerra, C.; Schimel, J.

2013-12-01

Soil is the largest reservoir of organic carbon in terrestrial ecosystems and as such, represents a potential sink for carbon dioxide.The decomposition products of dead roots buried in the soil is a contributor to soil organic carbon. However, changing precipitation patterns may affect its fate by influencing the microbial community responsible for decomposing dead roots. To assess the impact of changing precipitation patterns, we constructed microcosms with grassland soil collected from the UCSB Sedgwick Reserve, an active and long-term research site, and dead roots from greenhouse-grown grass, Bromus diandrus. Microcosms were wetted continuously, every seven days, or every twenty days. Sets of microcosms were periodically deconstructed to assess the soil versus the roots-associated microbial community and its function. Differences in respiration rates of microcosms continuously wetted or wetted every 7 days versus microcosms wetted every 20 days existed for the first 70 days. After which, no differences in respiration rates were seen with microcosms containing roots and the no roots control. Relatedly, after a 70% roots mass loss by day 50, there was no difference in the respiration rate of microcosms containing roots and the no roots control. More than half of the roots mass loss had occurred by 30 days. By the end of the incubation period, the roots mass loss in continuously wet and 7-day wetted microcosms were over 80% compared to 67% for the microcosms wetted every 20 days. Microbial biomass in the soil were constant over time and showed no difference in treatment except with the no roots control during the first half of the incubation period. Hydrolytic enzyme activities (β-1,4-glucosidase; α-1,4-glucosidase; β-1,4-xylosidase; β-1,4-cellobiosidase) on the roots versus the soil attached to the roots were over an order greater and decreased faster with the exception of N-acetyl-glucosaminidase and acid phosphatase. Oxidative enzyme activities (phenol

Indigenous 14C-phenanthrene biodegradation in "pristine" woodland and grassland soils from Norway and the United Kingdom.

PubMed

Okere, Uchechukwu V; Schuster, Jasmin K; Ogbonnaya, Uchenna O; Jones, Kevin C; Semple, Kirk T

2017-11-15

In this study, the indigenous microbial mineralisation of 14 C-phenanthrene in seven background soils (four from Norwegian woodland and three from the UK (two grasslands and one woodland)) was investigated. ∑PAHs ranged from 16.39 to 285.54 ng g -1 dw soil. Lag phases (time before 14 C-phenanthrene mineralisation reached 5%) were longer in all of the Norwegian soils and correlated positively with TOC, but negatively with ∑PAHs and phenanthrene degraders for all soils. 14 C-phenanthrene mineralisation in the soils varied due to physicochemical properties. The results show that indigenous microorganisms can adapt to 14 C-phenanthrene mineralisation following diffuse PAH contamination. Considering the potential of soil as a secondary PAH source, these findings highlight the important role of indigenous microflora in the processing of PAHs in the environment.

Variability in vegetation effects on density and nesting success of grassland birds

USGS Publications Warehouse

Winter, Maiken; Johnson, Douglas H.; Shaffer, Jill A.

2005-01-01

The structure of vegetation in grassland systems, unlike that in forest systems, varies dramatically among years on the same sites, and among regions with similar vegetation. The role of this variation in vegetation structure on bird density and nesting success of grassland birds is poorly understood, primarily because few studies have included sufficiently large temporal and spatial scales to capture the variation in vegetation structure, bird density, or nesting success. To date, no large-scale study on grassland birds has been conducted to investigate whether grassland bird density and nesting success respond similarly to changes in vegetation structure. However, reliable management recommendations require investigations into the distribution and nesting success of grassland birds over larger temporal and spatial scales. In addition, studies need to examine whether bird density and nesting success respond similarly to changing environmental conditions. We investigated the effect of vegetation structure on the density and nesting success of 3 grassland-nesting birds: clay-colored sparrow (Spizella pallida), Savannah sparrow (Passerculus sandwichensis), and bobolink (Dolichonyx oryzivorus) in 3 regions of the northern tallgrass prairie in 1998-2001. Few vegetation features influenced the densities of our study species, and each species responded differently to those vegetation variables. We could identify only 1 variable that clearly influenced nesting success of 1 species: clay-colored sparrow nesting success increased with increasing percentage of nest cover from the surrounding vegetation. Because responses of avian density and nesting success to vegetation measures varied among regions, years, and species, land managers at all times need to provide grasslands with different types of vegetation structure. Management guidelines developed from small-scale, short-term studies may lead to misrepresentations of the needs of grassland-nesting birds.

Grassland bird responses to land management in the largest remaining tallgrass prairie.

PubMed

Rahmig, Corina J; Jensen, William E; With, Kimberly A

2009-04-01

Extensive habitat loss and changing agricultural practices have caused widespread declines in grassland birds throughout North America. The Flint Hills of Kansas and Oklahoma--the largest remaining tallgrass prairie--is important for grassland bird conservation despite supporting a major cattle industry. In 2004 and 2005, we assessed the community, population, and demographic responses of grassland birds to the predominant management practices (grazing, burning, and haying) of the region, including grasslands restored under the Conservation Reserve Program (CRP). We targeted 3 species at the core of this avian community: the Dickcissel (Spiza americana), Grasshopper Sparrow (Ammodramus savannarum), and Eastern Meadowlark (Sturnella magna). Bird diversity was higher in native prairie hayfields and grazed pastures than CRP fields, which were dominated by Dickcissels. Although Dickcissel density was highest in CRP, their nest success was highest and nest parasitism by Brown-headed Cowbirds (Moluthrus ater) lowest in unburned hayfields (in 2004). Conversely, Grasshopper Sparrow density was highest in grazed pastures, but their nest success was lowest in these pastures and highest in burned hayfields, where cowbird parasitism was also lowest (in 2004). Management did not influence density and nest survival of Eastern Meadowlarks, which were uniformly low across the region. Nest success was extremely low (5-12%) for all 3 species in 2005, perhaps because of a record spring drought. Although the CRP has benefited grassland birds in agricultural landscapes, these areas may have lower habitat value in the context of native prairie. Hayfields may provide beneficial habitat for some grassland birds in the Flint Hills because they are mowed later in the breeding season than elsewhere in the Midwest. Widespread grazing and annual burning have homogenized habitat-and thus grassland-bird responses-across the Flint Hills. Diversification of management practices could increase

Ecosystem carbon loss with woody plant invasion of grasslands.

PubMed

Jackson, Robert B; Banner, Jay L; Jobbágy, Esteban G; Pockman, William T; Wall, Diana H

2002-08-08

The invasion of woody vegetation into deserts, grasslands and savannas is generally thought to lead to an increase in the amount of carbon stored in those ecosystems. For this reason, shrub and forest expansion (for example, into grasslands) is also suggested to be a substantial, if uncertain, component of the terrestrial carbon sink. Here we investigate woody plant invasion along a precipitation gradient (200 to 1,100 mm yr(-1)) by comparing carbon and nitrogen budgets and soil delta(13)C profiles between six pairs of adjacent grasslands, in which one of each pair was invaded by woody species 30 to 100 years ago. We found a clear negative relationship between precipitation and changes in soil organic carbon and nitrogen content when grasslands were invaded by woody vegetation, with drier sites gaining, and wetter sites losing, soil organic carbon. Losses of soil organic carbon at the wetter sites were substantial enough to offset increases in plant biomass carbon, suggesting that current land-based assessments may overestimate carbon sinks. Assessments relying on carbon stored from woody plant invasions to balance emissions may therefore be incorrect.

78 FR 65609 - Medicine Bow-Routt National Forests and Thunder Basin National Grassland; Wyoming; Thunder Basin...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-01

... National Grassland; Wyoming; Thunder Basin National Grassland Prairie Dog Amendment Environmental Impact... alternatives will be analyzed in the Thunder Basin National Grassland Prairie Dog Amendment EIS. The EIS will... Basin National Grassland Prairie Dog Amendment. The Open House/ Presentation meetings will be held on...

Area requirements of grassland birds: A regional perspective

USGS Publications Warehouse

Johnson, Douglas H.; Igl, Lawrence D.

2001-01-01

Area requirements of grassland birds have not been studied except in tallgrass prairie. We studied the relation between both species-occurrence and density and patch size by conducting 699 fixed-radius point counts of 15 bird species on 303 restored grassland areas in nine counties in four northern Great Plains states. Northern Harrier (Circus cyaneus), Sedge Wren (Cistothorus platensis), Clay-colored Sparrow (Spizella pallida), Grasshopper Sparrow (Ammodramus savannarum), Baird's Sparrow (Ammodramus bairdii), Le Conte's Sparrow (Ammodramus leconteii), and Bobolink (Dolichonyx oryzivorus) were shown to favor larger grassland patches in one or more counties. Evidence of area sensitivity was weak or ambivalent for Eastern Kingbird (Tyrannus tyrannus), Common Yellowthroat (Geothlypis trichas), Savannah Sparrow (Passerculus sandwichensis), and Western Meadowlark (Sturnella neglecta). Red-winged Blackbirds (Agelaius phoeniceus) preferred larger patches in some counties, and smaller patches in others. Mourning Doves (Zenaida macroura) and Brown- headed Cowbirds (Molothrus ater) tended to favor smaller grassland patches. Three species showed greater area sensitivity in counties where each species was more common. Five species demonstrated some spatial pattern of area sensitivity, either north to south or east to west. This study demonstrates the importance of replication in space; results from one area may not apply to others because of differences in study design, analytical methods, location relative to range of the species, and surrounding landscapes.

Grassland bird response to harvesting switchgrass as a biomass energy crop

USGS Publications Warehouse

Roth, A.M.; Sample, D.W.; Ribic, C.A.; Paine, L.; Undersander, D.J.; Bartelt, G.A.

2005-01-01

The combustion of perennial grass biomass to generate electricity may be a promising renewable energy option. Switchgrass (Panicum virgatum) grown as a biofuel has the potential to provide a cash crop for farmers and quality nesting cover for grassland birds. In southwestern Wisconsin (near lat. 42??52???, long. 90??08???), we investigated the impact of an August harvest of switchgrass for bioenergy on community composition and abundance of Wisconsin grassland bird species of management concern. Harvesting the switchgrass in August resulted in changes in vegetation structure and bird species composition the following nesting season. In harvested transects, residual vegetation was shorter and the litter layer was reduced in the year following harvest. Grassland bird species that preferred vegetation of short to moderate height and low to moderate density were found in harvested areas. Unharvested areas provided tall, dense vegetation structure that was especially attractive to tall-grass bird species, such as sedge wren (Cistothorus platensis) and Henslow's sparrow (Ammodramus henslowii). When considering wildlife habitat value in harvest management of switchgrass for biofuel, leaving some fields unharvested each year would be a good compromise, providing some habitat for a larger number of grassland bird species of management concern than if all fields were harvested annually. In areas where most idle grassland habitat present on the landscape is tallgrass, harvest of switchgrass for biofuel has the potential to increase the local diversity of grassland birds.

The microbe-mediated mechanisms affecting topsoil carbon stock in Tibetan grasslands

DOE PAGES

Yue, Haowei; Wang, Mengmeng; Wang, Shiping; ...

2015-02-17

Warming has been shown to cause soil carbon (C) loss in northern grasslands owing to accelerated microbial decomposition that offsets increased grass productivity. Yet, a multi-decadal survey indicated that the surface soil C stock in Tibetan alpine grasslands remained relatively stable. To investigate this inconsistency, we analyzed the feedback responses of soil microbial communities to simulated warming by soil transplant in Tibetan grasslands. Microbial functional diversity decreased in response to warming, whereas microbial community structure did not correlate with changes in temperature. The relative abundance of catabolic genes associated with nitrogen (N) and C cycling decreased with warming, most notablymore » in genes encoding enzymes associated with more recalcitrant C substrates. By contrast, genes associated with C fixation increased in relative abundance. The relative abundance of genes associated with urease, glutamate dehydrogenase and ammonia monoxygenase ( ureC, gdh and amoA) were significantly correlated with N 2O efflux. These results suggest that unlike arid/semiarid grasslands, Tibetan grasslands maintain negative feedback mechanisms that preserve terrestrial C and N pools. To examine whether these trends were applicable to the whole plateau, we included these measurements in a model and verified that topsoil C stocks remained relatively stable. Thus, by establishing linkages between microbial metabolic potential and soil biogeochemical processes, we conclude that long-term C loss in Tibetan grasslands is ameliorated by a reduction in microbial decomposition of recalcitrant C substrates.« less

MODIS NDVI and vegetation phenology dynamics in the Inner Mongolia grassland

NASA Astrophysics Data System (ADS)

Gong, Z.; Kawamura, K.; Ishikawa, N.; Goto, M.; Wulan, T.; Alateng, D.; Yin, T.; Ito, Y.

2015-08-01

The Inner Mongolia grassland, one of the most important grazing regions in China, has long been threatened by land degradation and desertification, mainly due to overgrazing. To understand vegetation responses over the last decade, this study evaluated trends in vegetation cover and phenology dynamics in the Inner Mongolia grassland by applying a normalized difference vegetation index (NDVI) time series obtained by the Terra Moderate Resolution Imaging Spectroradiometer (MODIS) during 2002-2014. The results showed that the cumulative annual NDVI increased to over 77.10 % in the permanent grassland region (2002-2014). The mean value of the total change showed that the start of season (SOS) date and the peak vegetation productivity date of the season (POS) had advanced by 5.79 and 2.43 days respectively. The end of season (EOS) was delayed by 5.07 days. These changes lengthened the season by 10.86 days. Our results also confirmed that grassland changes are closely related to spring precipitation (February-May) and increasing temperature during the growing period because of the global warming. Overall, productivity in the Inner Mongolia Autonomous Region tends to increase, but in some grassland areas with grazing, land degradation is ongoing.

Forest and grassland carbon in North America: A short course for land managers

Treesearch

Chris Swanston; Michael J. Furniss; Kristen Schmitt; Jeffrey Guntle; Maria Janowiak; Sarah Hines

2012-01-01

This multimedia short-course presents a range of information on the science, management and policy of forest and grassland carbon. Forests and grasslands worldwide play a critical role in storing carbon and sequestering greenhouse gases from the atmosphere. The U.S. Forest Service, which manages 193 million acres of forests and grasslands, emphasizes the need for...

Atmospheric nitrogen deposition in south-east Scotland: Quantification of the organic nitrogen fraction in wet, dry and bulk deposition

NASA Astrophysics Data System (ADS)

González Benítez, Juan M.; Cape, J. Neil; Heal, Mathew R.; van Dijk, Netty; Díez, Alberto Vidal

Water soluble organic nitrogen (WSON) compounds are ubiquitous in precipitation and in the planetary boundary layer, and therefore are a potential source of bioavailable reactive nitrogen. This paper examines weekly rain data over a period of 22 months from June 2005 to March 2007 collected in 2 types of rain collector (bulk deposition and "dry + wet" deposition) located in a semi-rural area 15 km southwest of Edinburgh, UK (N55°51'44″, W3°12'19″). Bulk deposition collectors are denoted in this paper as "standard rain gauges", and they are the design used in the UK national network for monitoring precipitation composition. "Dry + wet" deposition collectors are flushing rain gauges and they are equipped with a rain detector (conductivity array), a spray nozzle, a 2-way valve and two independent bottles to collect funnel washings (dry deposition) and true wet deposition. On average, for the 27 weekly samples with 3 valid replicates for the 2 types of collectors, dissolved organic nitrogen (DON) represented 23% of the total dissolved nitrogen (TDN) in bulk deposition. Dry deposition of particles and gas on the funnel surface, rather than rain, contributed over half of all N-containing species (inorganic and organic). Some discrepancies were found between bulk rain gauges and flushing rain gauges, for deposition of both TDN and DON, suggesting biological conversion and loss of inorganic N in the flushing samplers.

Evapotranspiration and soil moisture dynamics in a temperate grassland ecosystem in Inner Mongolia China

Treesearch

L. Hao; Ge Sun; Yongqiang Liu; G. S. Zhou; J. H.   Wan;  L. B. Zhang; J. L. Niu; Y. H. Sang;  J. J He

2015-01-01

Precipitation, evapotranspiration (ET), and soil moisture are the key controls for the productivity and functioning of temperate grassland ecosystems in Inner Mongolia, northern China. Quantifying the soil moisture dynamics and water balances in the grasslands is essential to sustainable grassland management under global climate change. We...

Patch size and landscape effects on density and nesting success of grassland birds

USGS Publications Warehouse

Winter, Maiken; Johnson, Douglas H.; Shaffer, Jill A.; Donovan, Therese M.; Svedarsky, W. Daniel

2006-01-01

Current management recommendations for grassland birds in North America emphasize providing large patches of grassland habitat within landscapes that have few forest or shrubland areas. These Bird Conservation Areas are being proposed under the assumption that large patches of habitat in treeless landscapes will maintain viable populations of grassland birds. This assumption requires that patch size and landscape features affect density and nesting success of grassland birds, and that these effects are consistent among years and regions and across focal species. However, these assumptions have not yet been validated for grassland birds, and the relative importance of local vegetation structure, patch size, and landscape composition on grassland bird populations is not well known. In addition, factors influencing grassland bird nesting success have been investigated mostly in small-scale and short-duration studies. To develop management guidelines for grassland birds, we tested the spatial and temporal repeatability of the influence of patch size and landscape composition on density and nesting success of 3 grassland passerines, after controlling for local-scale vegetation structure, climate, and—when analyzing nest success—bird density. We conducted our study during 4 years (1998–2001) in 44 study plots that were set up in 3 regions of the northern tallgrass prairie in Minnesota and North Dakota, USA. In these study plots we measured density and nesting success of clay-colored sparrows (Spizella pallida), Savannah sparrows (Passerculus sandwichensis), and bobolinks (Dolichonyx oryzivorus). Statistical models indicated that density was influenced by patch size, landscape, region, and local vegetation structure more so than by local vegetation structure alone. Both magnitude and direction of the response of density to patch size varied among regions, years, and species. In contrast, the direction of landscape effects was consistent among regions, years, and

Energy Potential of Biomass from Conservation Grasslands in Minnesota, USA

PubMed Central

Jungers, Jacob M.; Fargione, Joseph E.; Sheaffer, Craig C.; Wyse, Donald L.; Lehman, Clarence

2013-01-01

Perennial biomass from grasslands managed for conservation of soil and biodiversity can be harvested for bioenergy. Until now, the quantity and quality of harvestable biomass from conservation grasslands in Minnesota, USA, was not known, and the factors that affect bioenergy potential from these systems have not been identified. We measured biomass yield, theoretical ethanol conversion efficiency, and plant tissue nitrogen (N) as metrics of bioenergy potential from mixed-species conservation grasslands harvested with commercial-scale equipment. With three years of data, we used mixed-effects models to determine factors that influence bioenergy potential. Sixty conservation grassland plots, each about 8 ha in size, were distributed among three locations in Minnesota. Harvest treatments were applied annually in autumn as a completely randomized block design. Biomass yield ranged from 0.5 to 5.7 Mg ha−1. May precipitation increased biomass yield while precipitation in all other growing season months showed no affect. Averaged across all locations and years, theoretical ethanol conversion efficiency was 450 l Mg−1 and the concentration of plant N was 7.1 g kg−1, both similar to dedicated herbaceous bioenergy crops such as switchgrass. Biomass yield did not decline in the second or third year of harvest. Across years, biomass yields fluctuated 23% around the average. Surprisingly, forb cover was a better predictor of biomass yield than warm-season grass with a positive correlation with biomass yield in the south and a negative correlation at other locations. Variation in land ethanol yield was almost exclusively due to variation in biomass yield rather than biomass quality; therefore, efforts to increase biomass yield might be more economical than altering biomass composition when managing conservation grasslands for ethanol production. Our measurements of bioenergy potential, and the factors that control it, can serve as parameters for assessing the economic

Effect of degradation intensity on grassland ecosystem services in the alpine region of Qinghai-Tibetan Plateau, China.

PubMed

Wen, Lu; Dong, Shikui; Li, Yuanyuan; Li, Xiaoyan; Shi, Jianjun; Wang, Yanlong; Liu, Demei; Ma, Yushou

2013-01-01

The deterioration of alpine grassland has great impact on ecosystem services in the alpine region of Qinghai-Tibetan Plateau. However, the effect of grassland degradation on ecosystem services and the consequence of grassland deterioration on economic loss still remains a mystery. So, in this study, we assessed four types of ecosystem services following the Millennium Ecosystem Assessment classification, along a degradation gradient. Five sites of alpine grassland at different levels of degradation were investigated in Guoluo Prefecture of Qinghai Province, China. The species composition, aboveground biomass, soil total organic carbon (TOC), and soil total nitrogen (TN) were tested to evaluate major ecological services of the alpine grassland. We estimated the value of primary production, carbon storage, nitrogen recycling, and plant diversity. The results show the ecosystem services of alpine grassland varied along the degradation gradient. The ecosystem services of degraded grassland (moderate, heavy and severe) were all significantly lower than non-degraded grassland. Interestingly, the lightly degraded grassland provided more economic benefit from carbon maintenance and nutrient sequestration compared to non-degraded. Due to the destruction of the alpine grassland, the economic loss associated with decrease of biomass in 2008 was $198/ha. Until 2008, the economic loss caused by carbon emissions and nitrogen loss on severely degraded grassland was up to $8 033/ha and $13 315/ha, respectively. Urgent actions are required to maintain or promote the ecosystem services of alpine grassland in the Qinghai-Tibetan Plateau.

Effect of Degradation Intensity on Grassland Ecosystem Services in the Alpine Region of Qinghai-Tibetan Plateau, China

PubMed Central

Wen, Lu; Dong, Shikui; Li, Yuanyuan; Li, Xiaoyan; Shi, Jianjun; Wang, Yanlong; Liu, Demei; Ma, Yushou

2013-01-01

The deterioration of alpine grassland has great impact on ecosystem services in the alpine region of Qinghai-Tibetan Plateau. However, the effect of grassland degradation on ecosystem services and the consequence of grassland deterioration on economic loss still remains a mystery. So, in this study, we assessed four types of ecosystem services following the Millennium Ecosystem Assessment classification, along a degradation gradient. Five sites of alpine grassland at different levels of degradation were investigated in Guoluo Prefecture of Qinghai Province, China. The species composition, aboveground biomass, soil total organic carbon (TOC), and soil total nitrogen (TN) were tested to evaluate major ecological services of the alpine grassland. We estimated the value of primary production, carbon storage, nitrogen recycling, and plant diversity. The results show the ecosystem services of alpine grassland varied along the degradation gradient. The ecosystem services of degraded grassland (moderate, heavy and severe) were all significantly lower than non-degraded grassland. Interestingly, the lightly degraded grassland provided more economic benefit from carbon maintenance and nutrient sequestration compared to non-degraded. Due to the destruction of the alpine grassland, the economic loss associated with decrease of biomass in 2008 was $198/ha. Until 2008, the economic loss caused by carbon emissions and nitrogen loss on severely degraded grassland was up to $8 033/ha and $13 315/ha, respectively. Urgent actions are required to maintain or promote the ecosystem services of alpine grassland in the Qinghai-Tibetan Plateau. PMID:23469278

Habitat acquisition strategies for grassland birds in an urbanizing landscape

Treesearch

Stephanie A. Snyder; James R. Miller; Adam M. Skibbe; Robert G. Haight

2007-01-01

Habitat protection for grassland birds is an important component of open space land acquisition in suburban Chicago. We use optimization decision models to develop recommendations for land protection and analyze tradeoffs between alternative goals. One goal is to acquire (and restore if necessary) as much grassland habitat as possible for a given budget. Because a...

Accounting for habitat when considering climate: has the niche of the Adonis blue butterfly changed in the UK?

PubMed

O'Connor, Rory S; Hails, Rosemary S; Thomas, Jeremy A

2014-04-01

The dramatic recovery of three species of grassland specialist butterfly threatened with extinction at their high latitude range limits in the 1980s has been attributed to two factors: increased grazing on calcareous grassland sites and warmer air temperatures. Both result in the warming of soil surface temperatures, favourable to the larvae of these species. We address the influence of both of these factors on the habitat usage of the butterfly Polyommatus bellargus, undergoing recovery at its northern range edge. We test the hypothesis that the larval niche of P. bellargus has become less constrained in the past three decades, whilst controlling for changes in habitat structure. Once habitat change has been accounted for we find no evidence for a broadening of the larval niche of P. bellargus. Further, we show that coincident with the recovery of P. bellargus there have been drastic reductions in average turf height across UK chalk grasslands, but changes in air temperature have been highly variable. We conclude that changes to soil surface temperatures caused by reducing turf heights will have been a more consistent influence than air temperature increases, and so habitat improvements through increased grazing will have been the major driver of recovery in P. bellargus. We consider the need to account for changes in habitat when exploring the impacts of recent climate change on local habitats in thermophilous species, and emphasise the continued importance of habitat management to support such species under variable local climates.

Regional dynamics of grassland change in the western Great Plains

USGS Publications Warehouse

Drummond, M.A.

2007-01-01

This paper examines the contemporary land-cover changes in two western Great Plains ecoregions between 1973 and 2000. Agriculture and other land uses can have a substantial effect on grassland cover that varies regionally depending on the primary driving forces of change. In order to better understand change, the rates, types, and causes of land conversion were examined for 1973, 1980, 1986, 1992, and 2000 using Landsat satellite data and a statistical sampling strategy. The overall estimated rate of land-cover change between 1973 and 2000 was 7.4% in the Northwestern Great Plains and 11.5% in the Western High Plains. Trends in both ecoregions have similarities, although the dynamics of change differ temporally depending on driving forces. Between 1973 and 1986, grassland cover declined when economic opportunity drove an expansion of agriculture. Between 1986 and 2000, grassland expanded as public policy and a combination of socioeconomic factors drove a conversion from agriculture to grassland. ?? 2007 Copyright by the Center for Great Plains Studies, University of Nebraska-Lincoln.

Threshold responses to interacting global changes in a California grassland ecosystem

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

Field, Christopher; Mooney, Harold; Vitousek, Peter

2015-02-02

Building on the history and infrastructure of the Jasper Ridge Global Change Experiment, we conducted experiments to explore the potential for single and combined global changes to stimulate fundamental type changes in ecosystems that start the experiment as California annual grassland. Using a carefully orchestrated set of seedling introductions, followed by careful study and later removal, the grassland was poised to enable two major kinds of transitions that occur in real life and that have major implications for ecosystem structure, function, and services. These are transitions from grassland to shrubland/forest and grassland to thistle patch. The experiment took place inmore » the context of 4 global change factors – warming, elevated CO 2, N deposition, and increased precipitation – in a full-factorial array, present as all possible 1, 2, 3, and 4-factor combinations, with each combination replicated 8 times.« less

The greenhouse gas balance of European grasslands.

PubMed

Chang, Jinfeng; Ciais, Philippe; Viovy, Nicolas; Vuichard, Nicolas; Sultan, Benjamin; Soussana, Jean-François

2015-10-01

The greenhouse gas (GHG) balance of European grasslands (EU-28 plus Norway and Switzerland), including CO2 , CH4 and N2 O, is estimated using the new process-based biogeochemical model ORCHIDEE-GM over the period 1961-2010. The model includes the following: (1) a mechanistic representation of the spatial distribution of management practice; (2) management intensity, going from intensively to extensively managed; (3) gridded simulation of the carbon balance at ecosystem and farm scale; and (4) gridded simulation of N2 O and CH4 emissions by fertilized grassland soils and livestock. The external drivers of the model are changing animal numbers, nitrogen fertilization and deposition, land-use change, and variable CO2 and climate. The carbon balance of European grassland (NBP) is estimated to be a net sink of 15 ± 7 g C m(-2 ) year(-1) during 1961-2010, equivalent to a 50-year continental cumulative soil carbon sequestration of 1.0 ± 0.4 Pg C. At the farm scale, which includes both ecosystem CO2 fluxes and CO2 emissions from the digestion of harvested forage, the net C balance is roughly halved, down to a small sink, or nearly neutral flux of 8 g C m(-2 ) year(-1) . Adding CH4 and N2 O emissions to net ecosystem exchange to define the ecosystem-scale GHG balance, we found that grasslands remain a net GHG sink of 19 ± 10 g C-CO2 equiv. m(-2 ) year(-1) , because the CO2 sink offsets N2 O and grazing animal CH4 emissions. However, when considering the farm scale, the GHG balance (NGB) becomes a net GHG source of -50 g C-CO2 equiv. m(-2 ) year(-1) . ORCHIDEE-GM simulated an increase in European grassland NBP during the last five decades. This enhanced NBP reflects the combination of a positive trend of net primary production due to CO2 , climate and nitrogen fertilization and the diminishing requirement for grass forage due to the Europe-wide reduction in livestock numbers. © 2015 John Wiley & Sons Ltd.

Upscaling carbon fluxes over the Great Plains grasslands: Sinks and sources

USGS Publications Warehouse

Zhang, Li; Wylie, Bruce K.; Ji, Lei; Gilmanov, Tagir G.; Tieszen, Larry L.; Howar, Daniel M.

2011-01-01

Previous studies suggested that the grasslands may be carbon sinks or near equilibrium, and they often shift between carbon sources in drought years and carbon sinks in other years. It is important to understand the responses of net ecosystem production (NEP) to various climatic conditions across the U.S. Great Plains grasslands. Based on 15 grassland flux towers, we developed a piecewise regression model and mapped the grassland NEP at 250 m spatial resolution over the Great Plains from 2000 to 2008. The results showed that the Great Plains was a net sink with an averaged annual NEP of 24 ± 14 g C m−2 yr−1, ranging from a low value of 0.3 g C m−2 yr−1 in 2002 to a high value of 47.7 g C m−2 yr−1 in 2005. The regional averaged NEP for the entire Great Plains grasslands was estimated to be 336 Tg C yr−1 from 2000 to 2008. In the 9 year period including 4 dry years, the annual NEP was very variable in both space and time. It appeared that the carbon gains for the Great Plains were more sensitive to droughts in the west than the east. The droughts in 2000, 2002, 2006, and 2008 resulted in increased carbon losses over drought-affected areas, and the Great Plains grasslands turned into a relatively low sink with NEP values of 15.8, 0.3, 20.1, and 10.2 g C m−2 yr−1 for the 4 years, respectively.

Hydrologic impacts of converting grassland to managed forestland in Uruguay

Treesearch

G.M. Chescheira; R.W. Skaggsa; D.M. Amatyab

2008-01-01

Over 500,000 hectares of grassland have been converted to managed forestland in Uruguay since 1990. This study was initiated to determine the hydrologic and water quality impacts of changing land use from grassland (pasture) to pine plantation in Uruguay. Two adjacent watersheds located on the El Cerro ranch in the Tacuarembo River basin were selected for a paired...

Assessing the biophysical naturalness of grassland in eastern North Dakota with hyperspectral imagery

NASA Astrophysics Data System (ADS)

Zhou, Qiang

Over the past two decades, non-native species within grassland communities have quickly developed due to human migration and commerce. Invasive species like Smooth Brome grass (Bromus inermis) and Kentucky Blue Grass (Poa pratensis), seriously threaten conservation of native grasslands. This study aims to discriminate between native grasslands and planted hayfields and conservation areas dominated by introduced grasses using hyperspectral imagery. Hyperspectral imageries from the Hyperion sensor on EO-1 were acquired in late spring and late summer on 2009 and 2010. Field spectra for widely distributed species as well as smooth brome grass and Kentucky blue grass were collected from the study sites throughout the growing season. Imagery was processed with an unmixing algorithm to estimate fractional cover of green and dry vegetation and bare soil. As the spectrum is significantly different through growing season, spectral libraries for the most common species are then built for both the early growing season and late growing season. After testing multiple methods, the Adaptive Coherence Estimator (ACE) was used for spectral matching analysis between the imagery and spectral libraries. Due in part to spectral similarity among key species, the results of spectral matching analysis were not definitive. Additional indexes, "Level of Dominance" and "Band variance", were calculated to measure the predominance of spectral signatures in any area. A Texture co-occurrence analysis was also performed on both "Level of Dominance" and "Band variance" indexes to extract spatial characteristics. The results suggest that compared with disturbed area, native prairie tend to have generally lower "Level of Dominance" and "Band variance" as well as lower spatial dissimilarity. A final decision tree model was created to predict presence of native or introduced grassland. The model was more effective for identification of Mixed Native Grassland than for grassland dominated by a single

An African grassland responds similarly to long-term fertilization to the Park Grass experiment.

PubMed

Ward, David; Kirkman, Kevin; Tsvuura, Zivanai

2017-01-01

We compared the results of a long-term (65 years) experiment in a South African grassland with the world's longest-running ecological experiment, the Park Grass study at Rothamsted, U.K. The climate is warm and humid in South Africa and cool and temperate in England. The African grassland has been fertilized with two forms of nitrogen applied at four levels, phosphorus and lime in a crossed design in 96 plots. In 1951, about 84% of plant cover consisted of Themeda triandra, Tristachya leucothrix and Setaria nigrirostris. Currently, the dominant species are Panicum maximum, Setaria sphacelata and Eragrostis curvula, making up 71% of total biomass. As in the Park Grass experiment, we found a significant (additive) interaction effect on ANPP of nitrogen and phosphorus, and a (marginally significant) negative correlation between ANPP and species richness. Unlike the Park Grass experiment, there was no correlation between ANPP and species richness when pH was included as a covariate. There was also a significant negative effect of nitrogen amount and nitrogen form and a positive effect of lime on species richness and species diversity. Soil pH had an important effect on species richness. Liming was insufficient to balance the negative effects on species richness of nitrogen fertilization. There was a significant effect of pH on biomass of three abundant species. There were also significant effects of light on the biomass of four species, with only Panicum maximum having a negative response to light. In all of the abundant species, adding total species richness and ANPP to the model increased the amount of variance explained. The biomass of Eragrostis curvula and P. maximum were negatively correlated with species richness while three other abundant species increased with species richness, suggesting that competition and facilitation were active. Consistent with the results from the Park Grass and other long-term fertilization experiments of grasslands, we found a

Local-scale habitat associations of grassland birds in southwestern Minnesota

USGS Publications Warehouse

Elliott, Lisa H.; Johnson, Douglas H.

2017-01-01

Conservation of obligate grassland species requires not only the protection of a sufficiently large area of habitat but also the availability of necessary vegetation characteristics for particular species. As a result land managers must understand which habitat characteristics are important for their target species. To identify the habitat associations of eight species of grassland birds, we conducted bird and vegetation surveys on 66 grassland habitat patches in southwestern Minnesota in 2013 and 2014. Species of interest included sedge wren (Cistothorus platensis), Savannah sparrow (Passerculus sandwichensis), grasshopper sparrow (Ammodramus savannarum), Henslow's sparrow (Ammodramus henslowii), dickcissel (Spiza americana), bobolink (Dolichonyx oryzivorus), and western meadowlark (Sturnella neglecta). We calculated correlation coefficients between vegetation variables and species density as measures of linear association. We assessed curvilinear relationships with loess plots. We found grassland birds on 95.5% of surveyed sites, indicating remnant prairie in southwestern Minnesota is used by grassland birds. In general individual species showed different patterns of association and most species were tolerant of a wide variety of habitat conditions. The most consistent pattern was a negative association with both the quantity and proximity of trees. Our findings that individual species have different habitat preferences suggest that prairie resource managers may need to coordinate management efforts in order to create a mosaic of habitat types to support multiple species, though tree control will be an important and ongoing management activity at the individual site level.

Towards place-based borderlands grassland conservation (Hacia la conservacion de pastizales en tierras fronterizas)

Treesearch

Diana Hadley; Xavier Basurto

2006-01-01

When European explorers first observed the vast grasslands of the American continent, they viewed a series of interconnected, intact grassland ecosystems flourishing with an enormous diversity of flora and an abundance of wildlife. The term "sea of grass" appears frequently in descriptions of the vast prairie grasslands that extended from Canada to central...

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...

Assessment of soil water use by grassland by frequency domain reflectometry in the humid area of Spain

NASA Astrophysics Data System (ADS)

Mestas Valero, R. M.; Báez Bernal, D.; García Pomar, M. I.; Paz González, A.

2009-04-01

Frequency domain reflectometry (FDR) is becoming increasingly used for indirect water content determination in soils. In Galica, located in NW Spain, the humid region of this country, annual precipitation exceeds evapotranspiration. However, the yearly distribution of rainfall is irregular, so that supplementary irrigation during the dry warm summer is required often. This study aims to evaluate soil water use by grasslands and soil water regime patterns during the warm season from soil moisture measured at successive depths using FDR. The study sity is located at the experimental field of the Centre for Agricultural Research (CIAM) in Mabegondo, latitude 43°14' N and longitude 08°15' W. Soil moisture was monitored at six experimental plots from July to October 2008 two times per week using a portable FDR sensor. Measurements were made from 10 to 160 cm depth at 10 cm intervals. Moreover one of the plots was equipped with a continuous recording FDR-EnviroSCAN probe. Crop potential evapotranspiration (ETc) was estimated according to the of FAO version of the Penman-Monteith equation and the meteorological information required to apply this method was provided by a station located in the place experimental field. Cumulative rainfall along the study period was 195 mm, which is above the long-term mean and cumulative potential evapotranspiration was 264.7 mm. Using the water balance method the total value of actual evapotranspiration was estimated at 205.2 mm. Analysis of soil moisture content profiles allowed a description of soil water regime and main soil water withdrawal patterns under grassland. In general, grassland roots extracted most soil water from the 0-40 cm depth. In contrast, moisture content at the bottom of the profile was close to saturation, even the driest weeks of the study period. Continuous monitoring of soil water content allowed a more detailed characterization of dry and wet periods during the study season. The study data set may be useful

Proximate and landscape factors influence grassland bird distributions

USGS Publications Warehouse

Cunningham, M.A.; Johnson, D.H.

2006-01-01

Ecologists increasingly recognize that birds can respond to features well beyond their normal areas of activity, but little is known about the relative importance of landscapes and proximate factors or about the scales of landscapes that influence bird distributions. We examined the influences of tree cover at both proximate and landscape scales on grassland birds, a group of birds of high conservation concern, in the Sheyenne National Grassland in North Dakota, USA. The Grassland contains a diverse array of grassland and woodland habitats. We surveyed breeding birds on 2015 100 m long transect segments during 2002 and 2003. We modeled the occurrence of 19 species in relation to habitat features (percentages of grassland, woodland, shrubland, and wetland) within each 100-m segment and to tree cover within 200-1600 m of the segment. We used information-theoretic statistical methods to compare models and variables. At the proximate scales, tree cover was the most important variable, having negative influences on 13 species and positive influences on two species. In a comparison of multiple scales, models with only proximate variables were adequate for some species, but models combining proximate with landscape information were best for 17 of 19 species. Landscape-only models were rarely competitive. Combined models at the largest scales (800-1600 m) were best for 12 of 19 species. Seven species had best models including 1600-m landscapes plus proximate factors in at least one year. These were Wilson's Phalarope (Phalaropus tricolor), Sedge Wren (Cistothorus platensis), Field Sparrow (Spizella pusilla), Grasshopper Sparrow (Ammodramus savannarum), Bobolink (Dolychonix oryzivorus), Red-winged Blackbird (Agelaius phoeniceus), and Brown-headed Cowbird (Molothrus ater). These seven are small-bodied species; thus larger-bodied species do not necessarily respond most to the largest landscapes. Our findings suggest that birds respond to habitat features at a variety of

Studying the effects of land use on sediment loads, Little Missouri National Grasslands, North Dakota

USGS Publications Warehouse

Macek-Rowland, Kathleen M.

2002-01-01

The Little Missouri National Grasslands in North Dakota were established in 1960 and are publicly owned lands administered by the U.S. Department of Agriculture (USDA) Forest Service. The grasslands are not solid blocks of National Forest Systems lands but are lands intermingled with other Federal, State, and privately-owned lands. The mixed-ownership pattern creates a unique environmental management arrangement within each grasslands area.The USDA Forest Service needs to determine how changes in land use affect loss of sediment from the grasslands, especially during periods of high runoff or after a grassland fire. Excessive sediment loss has the potential to destabilize hillslopes and channels by increasing runoff potential, by prohibiting natural revegetation, by changing animal habitation patterns, and by impacting areas farther downslope and downstream of affected areas.On October 31, 1999, two major grass-land fires occurred in the Little Missouri National Grasslands area. The Squaw Gap Fire affected 51,627 acres and the Rough Creek Fire affected 7,979 acres. Runoff caused substantial erosion when many road ditches and culverts were filled with sediment and some roads were washed out. In order to implement the best management practices within the Little Missouri National Grasslands, the USDA Forest Service will need sediment information related to land-use changes such as burned and unburned areas and grazed and ungrazed areas.The Little Missouri National Grasslands are located along the Little Missouri River in western North Dakota. The Grasslands are comprised of 1,028,000 acres predominantly in an area of rolling hills, sparsely covered buttes, coulees, woody draws, and badlands. Most of the area is used as rangeland; but, some of the area is cultivated or used for oil and gas development. The Grasslands have semiarid climate with short, warm summers and long, cold winters. The Grasslands receive an average annual precipitation of about 13 to 15 inches

Simulating Spatiotemporal Dynamics of Sichuan Grassland Net Primary Productivity Using the CASA Model and In Situ Observations

PubMed Central

Tang, Chuanjiang; Fu, Xinyu; Jiang, Dong; Zhang, Xinyue; Zhou, Su

2014-01-01

Net primary productivity (NPP) is an important indicator for grassland resource management and sustainable development. In this paper, the NPP of Sichuan grasslands was estimated by the Carnegie-Ames-Stanford Approach (CASA) model. The results were validated with in situ data. The overall precision reached 70%; alpine meadow had the highest precision at greater than 75%, among the three types of grasslands validated. The spatial and temporal variations of Sichuan grasslands were analyzed. The absorbed photosynthetic active radiation (APAR), light use efficiency (ε), and NPP of Sichuan grasslands peaked in August, which was a vigorous growth period during 2011. High values of APAR existed in the southwest regions in altitudes from 2000 m to 4000 m. Light use efficiency (ε) varied in the different types of grasslands. The Sichuan grassland NPP was mainly distributed in the region of 3000–5000 m altitude. The NPP of alpine meadow accounted for 50% of the total NPP of Sichuan grasslands. PMID:25250396

Vaginitis test - wet mount

MedlinePlus

... prep - vaginitis; Vaginosis - wet mount; Trichomoniasis - wet mount; Vaginal candida - wet mount ... provider gently inserts an instrument (speculum) into the vagina to hold it open and view inside. A ...

Monitoring as a Means to Focus Research and Conservation - The Grassland Bird Monitoring Example

Treesearch

Brenda Dale; Michael Norton; Constance Downes; Brian Collins

2005-01-01

One recommendation of the Canadian Landbird Monitoring Strategy of Partners in Flight-Canada is to improve monitoring capability for rapidly declining grassland birds. In Canada, we lack statistical power for many grassland species because they are detected in small numbers, on a low number of routes, or show high year-to-year variability. In developing a Grassland...

Phosphorus translocation by red deer on a subalpine grassland in the central European Alps

Treesearch

Martin Schutz; Anita C. Risch; Gerald Achermann; Conny Thiel-Egenter; Deborah Page-Dumroese; Martin F. Jurgensen; Peter J. Edward

2006-01-01

We examined the role of red deer (Cervus elaphus L.) in translocating phosphorus (P) from their preferred grazing sites (short-grass vegetation on subalpine grasslands) to their wider home range in a subalpine grassland ecosystem in the Central European Alps. Phosphorus was used because it is the limiting nutrient in these grasslands. When we compared P removal of...

How will the semi-natural vegetation of the UK have changed by 2030 given likely changes in nitrogen deposition?

PubMed

Stevens, Carly J; Payne, Richard J; Kimberley, Adam; Smart, Simon M

2016-01-01

Nitrogen deposition is known to have major impacts on contemporary ecosystems but few studies have addressed how these impacts will develop over coming decades. We consider likely changes to British semi-natural vegetation up to the year 2030 both qualitatively, based on knowledge of species responses from experimental and gradient studies, and quantitatively, based on modelling of species relationships in national monitoring data. We used historical N deposition trends and national predictions of changing deposition to calculate cumulative deposition from 1900 to 2030. Data from the Countryside Survey (1978, 1990 and 1998) was used to parameterise models relating cumulative N deposition to Ellenberg N which were then applied to expected future deposition trends. Changes to habitat suitability for key species of grassland, heathland and bog, and broadleaved woodland to 2030 were predicted using the MultiMOVE model. In UK woodlands by 2030 there is likely to be reduced occurrence of lichens, increased grass cover and a shift towards more nitrophilic vascular plant species. In grasslands we expect changing species composition with reduced occurrence of terricolous lichens and, at least in acid grasslands, reduced species richness. In heaths and bogs we project overall reductions in species richness with decreased occurrence of terricolous lichens and some bryophytes, reduced cover of dwarf shrubs and small increases in grasses. Our study clearly suggests that changes in vegetation due to nitrogen deposition are likely to continue through coming decades. Copyright © 2015 Elsevier Ltd. All rights reserved.

Long Term Positive Effect of Grassland Restoration on Plant Diversity - Success or Not?

PubMed Central

Lindborg, Regina

2016-01-01

Restoration is important for biodiversity conservation worldwide, but surprisingly little is known about its efficiency in a long-term perspective. In this study, we re-examined Swedish semi-natural grasslands 12–20 years after the restoration, by comparing field inventories of vascular plant species diversity made in 2001 with follow-up inventories in 2012. We also analysed restoration effect in relation to six environmental factors and used continuously managed semi-natural grasslands as references of desired state after restoration. We found that total species richness increased over time but not to reference levels, while there were no significant changes in species density or number of grassland specialists. However, the overall species composition in the restored sites, as well as grassland specialist composition, now largely resembled reference conditions. Fertilisation and time between abandonment and restoration were the only environmental variables that affected total species composition change, while site area affected change in grassland specialist composition. Our results show that restoration of semi-natural grasslands can contribute to conservation of semi-natural habitats and their associated biodiversity. Yet, due to the vague restoration goals for these sites, it is difficult to evaluate the restoration success, which emphasise the general need for clear and measurable goals. PMID:27196748

Long Term Positive Effect of Grassland Restoration on Plant Diversity - Success or Not?

PubMed

Waldén, Emelie; Lindborg, Regina

2016-01-01

Restoration is important for biodiversity conservation worldwide, but surprisingly little is known about its efficiency in a long-term perspective. In this study, we re-examined Swedish semi-natural grasslands 12-20 years after the restoration, by comparing field inventories of vascular plant species diversity made in 2001 with follow-up inventories in 2012. We also analysed restoration effect in relation to six environmental factors and used continuously managed semi-natural grasslands as references of desired state after restoration. We found that total species richness increased over time but not to reference levels, while there were no significant changes in species density or number of grassland specialists. However, the overall species composition in the restored sites, as well as grassland specialist composition, now largely resembled reference conditions. Fertilisation and time between abandonment and restoration were the only environmental variables that affected total species composition change, while site area affected change in grassland specialist composition. Our results show that restoration of semi-natural grasslands can contribute to conservation of semi-natural habitats and their associated biodiversity. Yet, due to the vague restoration goals for these sites, it is difficult to evaluate the restoration success, which emphasise the general need for clear and measurable goals.

Remote sensing for grassland management in the arid Southwest

USGS Publications Warehouse

Marsett, R.C.; Qi, J.; Heilman, P.; Biedenbender, S.H.; Watson, M.C.; Amer, S.; Weltz, M.; Goodrich, D.; Marsett, R.

2006-01-01

We surveyed a group of rangeland managers in the Southwest about vegetation monitoring needs on grassland. Based on their responses, the objective of the RANGES (Rangeland Analysis Utilizing Geospatial Information Science) project was defined to be the accurate conversion of remotely sensed data (satellite imagery) to quantitative estimates of total (green and senescent) standing cover and biomass on grasslands and semidesert grasslands. Although remote sensing has been used to estimate green vegetation cover, in arid grasslands herbaceous vegetation is senescent much of the year and is not detected by current remote sensing techniques. We developed a ground truth protocol compatible with both range management requirements and Landsat's 30 m resolution imagery. The resulting ground-truth data were then used to develop image processing algorithms that quantified total herbaceous vegetation cover, height, and biomass. Cover was calculated based on a newly developed Soil Adjusted Total Vegetation Index (SATVI), and height and biomass were estimated based on reflectance in the near infrared (NIR) band. Comparison of the remotely sensed estimates with independent ground measurements produced r2 values of 0.80, 0.85, and 0.77 and Nash Sutcliffe values of 0.78, 0.70, and 0.77 for the cover, plant height, and biomass, respectively. The approach for estimating plant height and biomass did not work for sites where forbs comprised more than 30% of total vegetative cover. The ground reconnaissance protocol and image processing techniques together offer land managers accurate and timely methods for monitoring extensive grasslands. The time-consuming requirement to collect concurrent data in the field for each image implies a need to share the high fixed costs of processing an image across multiple users to reduce the costs for individual rangeland managers.

Strategic Grassland Bird Conservation throughout the Annual Cycle: Linking Policy Alternatives, Landowner Decisions, and Biological Population Outcomes.

PubMed

Drum, Ryan G; Ribic, Christine A; Koch, Katie; Lonsdorf, Eric; Grant, Evan; Ahlering, Marissa; Barnhill, Laurel; Dailey, Thomas; Lor, Socheata; Mueller, Connie; Pavlacky, David C; Rideout, Catherine; Sample, David

2015-01-01

Grassland bird habitat has declined substantially in the United States. Remaining grasslands are increasingly fragmented, mostly privately owned, and vary greatly in terms of habitat quality and protection status. A coordinated strategic response for grassland bird conservation is difficult, largely due to the scope and complexity of the problem, further compounded by biological, sociological, and economic uncertainties. We describe the results from a collaborative Structured Decision Making (SDM) workshop focused on linking social and economic drivers of landscape change to grassland bird population outcomes. We identified and evaluated alternative strategies for grassland bird conservation using a series of rapid prototype models. We modeled change in grassland and agriculture cover in hypothetical landscapes resulting from different landowner decisions in response to alternative socio-economic conservation policy decisions. Resulting changes in land cover at all three stages of the annual cycle (breeding, wintering, and migration) were used to estimate changes in grassland bird populations. Our results suggest that successful grassland bird conservation may depend upon linkages with ecosystem services on working agricultural lands and grassland-based marketing campaigns to engage the public. With further development, spatial models that link landowner decisions with biological outcomes can be essential tools for making conservation policy decisions. A coordinated non-traditional partnership will likely be necessary to clearly understand and systematically respond to the many conservation challenges facing grassland birds.

Strategic Grassland Bird Conservation throughout the Annual Cycle: Linking Policy Alternatives, Landowner Decisions, and Biological Population Outcomes

PubMed Central

Drum, Ryan G.; Ribic, Christine A.; Koch, Katie; Lonsdorf, Eric; Grant, Evan; Ahlering, Marissa; Barnhill, Laurel; Dailey, Thomas; Lor, Socheata; Mueller, Connie; Pavlacky, David C.; Rideout, Catherine; Sample, David

2015-01-01

Grassland bird habitat has declined substantially in the United States. Remaining grasslands are increasingly fragmented, mostly privately owned, and vary greatly in terms of habitat quality and protection status. A coordinated strategic response for grassland bird conservation is difficult, largely due to the scope and complexity of the problem, further compounded by biological, sociological, and economic uncertainties. We describe the results from a collaborative Structured Decision Making (SDM) workshop focused on linking social and economic drivers of landscape change to grassland bird population outcomes. We identified and evaluated alternative strategies for grassland bird conservation using a series of rapid prototype models. We modeled change in grassland and agriculture cover in hypothetical landscapes resulting from different landowner decisions in response to alternative socio-economic conservation policy decisions. Resulting changes in land cover at all three stages of the annual cycle (breeding, wintering, and migration) were used to estimate changes in grassland bird populations. Our results suggest that successful grassland bird conservation may depend upon linkages with ecosystem services on working agricultural lands and grassland-based marketing campaigns to engage the public. With further development, spatial models that link landowner decisions with biological outcomes can be essential tools for making conservation policy decisions. A coordinated non-traditional partnership will likely be necessary to clearly understand and systematically respond to the many conservation challenges facing grassland birds. PMID:26569108

Strategic Grassland Bird Conservation throughout the annual cycle: Linking policy alternatives, landowner decisions, and biological population outcomes

USGS Publications Warehouse

Drum, Ryan G.; Ribic, Christine; Koch, Katie; Lonsdorf, Eric V.; Grant, Edward C.; Ahlering, Marissa; Barnhill, Laurel; Dailey, Thomas; Lor, Socheata; Mueller, Connie; Pavlacky, D.C.; Rideout, Catherine; Sample, David W.

2015-01-01

Grassland bird habitat has declined substantially in the United States. Remaining grasslands are increasingly fragmented, mostly privately owned, and vary greatly in terms of habitat quality and protection status. A coordinated strategic response for grassland bird conservation is difficult, largely due to the scope and complexity of the problem, further compounded by biological, sociological, and economic uncertainties. We describe the results from a collaborative Structured Decision Making (SDM) workshop focused on linking social and economic drivers of landscape change to grassland bird population outcomes. We identified and evaluated alternative strategies for grassland bird conservation using a series of rapid prototype models. We modeled change in grassland and agriculture cover in hypothetical landscapes resulting from different landowner decisions in response to alternative socio-economic conservation policy decisions. Resulting changes in land cover at all three stages of the annual cycle (breeding, wintering, and migration) were used to estimate changes in grassland bird populations. Our results suggest that successful grassland bird conservation may depend upon linkages with ecosystem services on working agricultural lands and grassland-based marketing campaigns to engage the public. With further development, spatial models that link landowner decisions with biological outcomes can be essential tools for making conservation policy decisions. A coordinated non-traditional partnership will likely be necessary to clearly understand and systematically respond to the many conservation challenges facing grassland birds.

Changing Summer Precipitation Pattern Alters Microbial Community Response to Fall Wet-up in a Mediterranean Soil

NASA Astrophysics Data System (ADS)

Barnard, R. L.; Osborne, C. A.; Firestone, M. K.

2014-12-01

The large soil CO2 efflux associated with rewetting dry soils after the dry summer period significantly contributes to the annual carbon budget of Mediterranean grasslands. Rapid reactivation of soil heterotrophic activity and a pulse of available carbon are both required to fuel the CO2 pulse. Better understanding of the effects of altered summer precipitation on the metabolic state of indigenous microorganisms may be important in predicting future changes in carbon cycling. Here, we investigated the effects of a controlled rewetting event on the soil CO2 efflux pulse and on the present (DNA-based) and potentially active (rRNA-based) soil bacterial and fungal communities in intact soil cores previously subjected to three different precipitation patterns over four months (full summer dry season, extended wet season, and absent dry season). Phylogenetic marker genes for bacteria (16S) and fungi (28S) were sequenced before and after rewetting, and the abundance of these genes and transcripts was measured. Even after having experienced markedly different antecedent water conditions, the potentially active bacterial communities showed a consistent wet-up response. Moreover, we found a significant positive relation between the extent of change in the structure of the potentially active bacterial community and the magnitude of the CO2 pulse upon rewetting dry soils. We suggest that the duration of severe dry conditions (predicted to change under future climate) is important in conditioning the response potential of the soil bacterial community to wet-up as well as in framing the magnitude of the associated CO2 pulse.

[Influences of land using patterns on the anti-wind erosion of meadow grassland].

PubMed

Zhou, Yao-Zhi; Wang-Xu; Yang, Gui-Xia; Xin, Xiao-Ping

2008-05-01

In order to analyse the effects of the human disturbances to the ability of anti-wind erosion of the Hulunbuir meadow grassland, the methods of vegetation investigation and the wind tunnel experiment were made to research the changes of vegetation and the abilities of anti-wind erosion of meadow grassland under different using patterns of meadow grassland. The results indicate that, under different grazing intensities of meadow grassland, the critical wind velocity of soil erosion (v) changes with the vegetation cover according to the relation of second power function. Along with the grazing intensities increasing and the vegetation cover reducing, the velocity of soil erosion rapidly increased on the condition of similar wind velocity which is speedier than the critical wind velocity of soil erosion. When the meadow grassland is mildly grazed which the vegetation cover maintains 63%, the velocity of soil erosion is small even there is gale that the wind velocity reach 25 m/s. When the vegetation cover of meadow grassland reduced to less than 35%, the velocity of soil erosion rapidly increased with the vegetation cover's reducing on the condition of the wind velocity is among 20-25 m/s. And owing to the no-tillage cropland of meadow grassland is completely far from the protection of the vegetation, the soil wind erosion quantity achieves 682.1 kg/hm2 in a minute when the wind velocity is 25 m/s, which approaches the average formation quantity of soil (1 000 kg/hm2) in a year.

Species diversity of remnant calcareous grasslands in south eastern Germany depends on litter cover and landscape structure

NASA Astrophysics Data System (ADS)

Huber, Stephanie; Huber, Birgit; Stahl, Silvia; Schmid, Christoph; Reisch, Christoph

2017-08-01

Species diversity depends on, often interfering, multiple ecological drivers. Comprehensive approaches are hence needed to understand the mechanisms determining species diversity. In this study, we analysed the impact of vegetation structure, soil properties and fragmentation on the plant species diversity of remnant calcareous grasslands, therefore, in a comparative approach. We determined plant species diversity of 18 calcareous grasslands in south eastern Germany including all species and grassland specialists separately. Furthermore, we analysed the spatial structure of the grasslands as a result of fragmentation during the last 150 years (habitat area, distance to the nearest calcareous grassland and connectivity in 1830 and 2013). We also collected data concerning the vegetation structure (height of the vegetation, cover of bare soil, grass and litter) and the soil properties (content of phosphorous and potassium, ratio of carbon and nitrogen) of the grassland patches. Data were analysed using Bayesian multiple regressions. We observed a habitat loss of nearly 80% and increasing isolation between grasslands since 1830. In the Bayesian multiple regressions the species diversity of the studied grasslands depended negatively on cover of litter and to a lower degree on the distance to the nearest calcareous grassland in 2013, whereas soil properties had no significant impact. Our study supports the observation that vegetation structure, which strongly depends on land use, is often more important for the species richness of calcareous grasslands than fragmentation or soil properties. Even small and isolated grasslands may, therefore, contribute significantly to the conservation of species diversity, when they are still grazed.

Grassland rehabilitation (Rehabilitacion de Pastizales)

Treesearch

Mario Royo

2006-01-01

The main goal of grassland rehabilitation is to reestablish vegetation, with the objectives of reducing soil erosion, incorporating more rainwater into the soil and aquifer, maintaining biodiversity, restoring scenic beauty, and attaining a site's forage potential, as well as maintaining and reproducing the native fauna. Pastures can be rehabilitated naturally by...

Assessment of Tibetan grassland degeneration via landscape analysis

NASA Astrophysics Data System (ADS)

Sun, Jian; Hou, Ge; Ma, Baibing; Zang, Wenqian

2017-04-01

Desertification as one of the most severity social-economic-environmental issues has been extensive researched, and the assessments of desertification can be implemented accurately and efficiently based on the landscape indicators of vegetation coverage. Consequently, we explored the relationships of the degeneration index of the grassland with climate factors (temperature and precipitation), and human disturbance factors (livestock quantity and animal husbandry output value) via a landscape assessment approach across Tibet. The results showed that the vegetation coverage presented an increase tendency in the central region of Tibet, but the adverse phenomenon was observed in the northwest region. Meanwhile, the correlation of vegetation coverage with precipitation presented as positive effect in most region of Tibet except some regions of the alpine steppe, and the positive correlation of vegetation coverage with temperature also was observed in the less northwest region of Tibet. In addition, we found that the livestock quantity play a key roles in regulating vegetation coverage of the central region. Furthermore, the landscape indexes [number of patches (NP), patch density (PD), contagion index (CONTAG), landscape shape index (LSI), aggregation index (AI)] of grasslands were analyzed, the results exposed that vegetation coverage (1%-20%) has the positive influences on CONTAG and AI, but negative affects LSI, PD and NP. Morreover, there are opposite correlations among vegetation coverage and landscape indexes when vegetation coverage is 21%-40%. We concluded that overgrazing is the main reason of grassland degradation in Tibet, especially the number of livestock aggravates the landscape fragmentation. The results highlighted the alpine grassland management in future.

Plant assemblage composition and soil P concentration differentially affect communities of AM and total fungi in a semi-arid grassland.

PubMed

Klabi, Rim; Bell, Terrence H; Hamel, Chantal; Iwaasa, Alan; Schellenberg, Mike; Raies, Aly; St-Arnaud, Marc

2015-01-01

Adding inorganic P- and N-fixing legumes to semi-arid grasslands can increase forage yield, but soil nutrient concentrations and plant cover may also interact to modify soil fungal populations, impacting short- and long-term forage production. We tested the effect of plant assemblage (seven native grasses, seven native grasses + the domesticated N-fixing legume Medicago sativa, seven native grasses + the native N-fixing legume Dalea purpurea or the introduced grass Bromus biebersteinii + M. sativa) and soil P concentration (addition of 0 or 200 P2O5 kg ha(-1) at sowing) on the diversity and community structure of arbuscular mycorrhizal (AM) fungi and total fungi over two consecutive years, using 454-pyrosequencing of 18S rDNA and ITS amplicons. Treatment effects were stronger in the wet year (2008) than the dry year (2009). The presence of an N-fixing legume with native grasses generally increased AM fungal diversity, while the interaction between soil P concentration and plant assemblage modified total fungal community structure in 2008. Excluding interannual variations, which are likely driven by moisture and plant productivity, AM fungal communities in semi-arid grasslands appear to be primarily affected by plant assemblage composition, while the composition of other fungi is more closely linked to soil P. © FEMS 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Interannual variation in land-use intensity enhances grassland multidiversity

PubMed Central

Allan, Eric; Bossdorf, Oliver; Dormann, Carsten F.; Prati, Daniel; Gossner, Martin M.; Tscharntke, Teja; Blüthgen, Nico; Bellach, Michaela; Birkhofer, Klaus; Boch, Steffen; Böhm, Stefan; Börschig, Carmen; Chatzinotas, Antonis; Christ, Sabina; Daniel, Rolf; Diekötter, Tim; Fischer, Christiane; Friedl, Thomas; Glaser, Karin; Hallmann, Christine; Hodac, Ladislav; Hölzel, Norbert; Jung, Kirsten; Klein, Alexandra Maria; Klaus, Valentin H.; Kleinebecker, Till; Krauss, Jochen; Lange, Markus; Morris, E. Kathryn; Müller, Jörg; Nacke, Heiko; Pašalić, Esther; Rillig, Matthias C.; Rothenwöhrer, Christoph; Schall, Peter; Scherber, Christoph; Schulze, Waltraud; Socher, Stephanie A.; Steckel, Juliane; Steffan-Dewenter, Ingolf; Türke, Manfred; Weiner, Christiane N.; Werner, Michael; Westphal, Catrin; Wolters, Volkmar; Wubet, Tesfaye; Gockel, Sonja; Gorke, Martin; Hemp, Andreas; Renner, Swen C.; Schöning, Ingo; Pfeiffer, Simone; König-Ries, Birgitta; Buscot, François; Linsenmair, Karl Eduard; Schulze, Ernst-Detlef; Weisser, Wolfgang W.; Fischer, Markus

2014-01-01

Although temporal heterogeneity is a well-accepted driver of biodiversity, effects of interannual variation in land-use intensity (LUI) have not been addressed yet. Additionally, responses to land use can differ greatly among different organisms; therefore, overall effects of land-use on total local biodiversity are hardly known. To test for effects of LUI (quantified as the combined intensity of fertilization, grazing, and mowing) and interannual variation in LUI (SD in LUI across time), we introduce a unique measure of whole-ecosystem biodiversity, multidiversity. This synthesizes individual diversity measures across up to 49 taxonomic groups of plants, animals, fungi, and bacteria from 150 grasslands. Multidiversity declined with increasing LUI among grasslands, particularly for rarer species and aboveground organisms, whereas common species and belowground groups were less sensitive. However, a high level of interannual variation in LUI increased overall multidiversity at low LUI and was even more beneficial for rarer species because it slowed the rate at which the multidiversity of rare species declined with increasing LUI. In more intensively managed grasslands, the diversity of rarer species was, on average, 18% of the maximum diversity across all grasslands when LUI was static over time but increased to 31% of the maximum when LUI changed maximally over time. In addition to decreasing overall LUI, we suggest varying LUI across years as a complementary strategy to promote biodiversity conservation. PMID:24368852

Estimating N2O processes during grassland renewal and grassland conversion to maize cropping using N2O isotopocules

NASA Astrophysics Data System (ADS)

Buchen, Caroline; Well, Reinhard; Flessa, Heinz; Fuß, Roland; Helfrich, Mirjam; Lewicka-Szczebak, Dominika

2017-04-01

Grassland break-up due to grassland renewal and grassland conversion to cropland can lead to a flush of mineral nitrogen from decomposition of the old grass sward and the decomposition of soil organic matter. Moreover, increased carbon and nitrogen mineralisation can result in enhanced nitrous oxide (N2O) emissions. As N2O is known to be an important greenhouse gas and a major precursor for ozone depletion, its emissions need to be mitigated by adjusting agricultural management practices. Therefore, it is necessary to understand the N2O processes involved, as well as the contribution of N2O reduction to N2. Apart from the widely used 15N gas flux method, natural abundance isotopic analysis of the four most abundant isotopocules of N2O species is a promising alternative to assess N2O production pathways. We used stable isotope analyses of soil-emitted N2O (δ18ON2O, δ15NN2Obulk and δ15NN2OSP= intramolecular distribution of 15N within the linear N2O molecule) with an isotopocule mapping approach to simultaneously estimate the magnitude of N2O reduction to N2 and the fraction of N2O originating from the bacterial denitrification pathway or fungal denitrification and/or nitrification. This approach is based on endmember areas of isotopic values for the N2O produced from different sources reported in the literature. For this purpose, we calculated two main scenarios with different assumptions for N2O produced: N2O is reduced to N2 before residual N2O is mixed with N2O of various sources (Scenario a) and vice versa (Scenario b). Based on this, we applied seven different scenario variations, where we evaluated the range of possible values for the potential N2O production pathways (heterotrophic bacterial denitrification and/or nitrifier denitrification and fungal denitrification and/or nitrification). This was done by using a range of isotopic endmember values and assuming different fractionation factors of N2O reduction in order to find the most reliable scenario

Contrasting impacts of reindeer grazing in two tundra grasslands

NASA Astrophysics Data System (ADS)

Vowles, Tage; Lovehav, Cajsa; Molau, Ulf; Björk, Robert G.

2017-03-01

Plant communities in Arctic and alpine areas are changing due to higher temperatures and longer vegetation periods and it is uncertain how this will affect plant-herbivore dynamics. For instance, relatively fast-growing, deciduous shrub species that are the most responsive to warming may also be the most targeted by herbivores such as reindeer, giving less palatable evergreen shrubs the chance to expand. Using herbivore exclosures, we have studied how two grasslands with contrasting nutrient and moisture regimes, a dry, nutrient-poor alpine grass heath and a wet, productive low herb meadow, changed between 1995 and 2012, in grazed and ungrazed conditions. At the grass heath, evergreen low shrub abundance had more than doubled, regardless of grazer treatment, whereas at the low herb meadow, evergreen shrubs had increased only outside exclosures while deciduous tall shrubs and forbs were significantly more abundant inside exclosures. Deciduous tall shrubs were also significantly taller in exclosures. These contrasting findings suggest that the impact of herbivores is to a great deal determined by their influence on competitive interactions between plant species, and therefore depends on the underlying composition of the plant community. Consequently, as the balance in these competitive interactions is shifting due to climate warming, we conclude that the potential of herbivory to influence this balance is considerable yet highly site dependent.

Changes in SOC stocks and fractions after natural afforestation of alpine grasslands

NASA Astrophysics Data System (ADS)

Guidi, Claudia; Rodeghiero, Mirco; Vesterdal, Lars; Gianelle, Damiano

2013-04-01

Land use changes are considered one of the major driving forces of global carbon fluxes and can induce significant alterations of soil organic carbon stocks. In the European Alps, the dominant form of land use change is represented by the abandonment of marginal mountain grasslands and their invasion by tree species, i.e. a transition from grassland to forest. While an increase in live and dead aboveground biomass is commonly reported, the impact on soil organic carbon (SOC) is still unclear. The main objective of the current study was to quantify the effect of abandonment and forest regrowth of mountain grassland on SOC, considering both SOC stocks and its physically separated fractions. The study area is located in a pre-alpine area of the Trentino region (Italy), with an elevation of about 1150 m. We compared four land uses representing a transition from grassland to forest: I) managed grassland; II) grassland abandoned 10 years ago; III) natural afforested grassland abandoned after 1973; IV) reference forest, already present in 1861. The afforested area and the reference forest are both dominated by Norway spruce (Picea abies) and beech (Fagus sylvatica). For each land use intensity three sampling areas were selected. In each area we collected eight soil cores to a depth of 30 cm, dividing the soil core in 4 depth increments. To assess changes in SOC stocks, we measured bulk density, stoniness, root biomass and organic carbon content. Mineral SOC stocks were calculated using both an equivalent depth and an equivalent mass approach. Changes in SOC fractions were assessed using aggregate size fractionation (Cambardella and Elliott, 1993) and size-density fractionation procedures. Preliminary results show higher soil C concentrations in forest sites compared to grassland. This can be attributed to higher C inputs and lower mineralization rates due to a higher degree of soil aggregation and protection of soil organic matter, but also to the higher stoniness

Spatiotemporal variations in litter mass and their relationships with climate in temperate grassland: A case study from Xilingol grassland, Inner Mongolia (China)

NASA Astrophysics Data System (ADS)

Ren, Hongrui; Zhang, Bei

2018-02-01

Clarifying spatiotemporal variations of litter mass and their relationships with climate factors will advance our understanding of ecosystem structure and functioning in grasslands. Our objective is to investigate the spatiotemporal variations of litter mass in the growing season and their relationships with precipitation and temperature in the Xilingol grassland using MOD09A1 data. With widely used STI (simple tillage index), we firstly estimated the litter mass of Xilingol grassland in the growing season from 2000 to 2014. Then we investigated the variations of litter mass in the growing season at regional and site scales. We further explored the spatiotemporal relationships between litter mass and precipitation and temperature at both scales. The litter mass increased with increasing mean annual precipitation and decreasing mean annual temperature at regional scale. The variations of litter mass at given sites followed quadratic function curves in the growing season, and litter mass generally attained maximums between August 1 and September 1. Positive spatial relationship was observed between litter mass variations and precipitation, and negative spatial relationship was found between litter mass variations and temperature in the growing season. There was no significant relationship between inter-annual variations of litter mass and precipitation and temperature at given sites. Results illustrate that precipitation and temperature are important drivers in shaping ecosystem functioning as reflected in litter mass at regional scale in the Xilingol grassland. Our findings also suggest the action of distinct mechanism in controlling litter mass variations at regional and sites scales.

An assessment of the spatial extent and condition of grasslands in the Apache Highlands ecoregion

Treesearch

Carolyn A. F. Enquist; David F. Gori

2005-01-01

Grasslands in the Apache Highlands ecoregion have experienced dramatic changes. To assess and identify remaining native grasslands for conservation planning and management, we used a combination of expert consultation and field verification. Over two-thirds of native grasslands have experienced shrub encroachment. More than 30% of these may be restorable with...

The impacts of climate change and human activities on grassland productivity in Qinghai Province, China

NASA Astrophysics Data System (ADS)

Yin, Fang; Deng, Xiangzheng; Jin, Qin; Yuan, Yongwei; Zhao, Chunhong

2014-03-01

Qinghai Province, which is the source of three major rivers (i.e., Yangtze River, Yellow River and Lancang River) in East Asia, has experienced severe grassland degradation in past decades. The aim of this work was to analyze the impacts of climate change and human activities on grassland ecosystem at different spatial and temporal scales. For this purpose, the regression and residual analysis were used based on the data from remote sensing data and meteorological stations. The results show that the effect of climate change was much greater in the areas exhibiting vigorous vegetation growth. The grassland degradation was strongly correlated with the climate factors in the study area except Haixi Prefecture. Temporal and spatial heterogeneity in the quality of grassland were also detected, which was probably mainly because of the effects of human activities. In the 1980s, human activities and grassland vegetation growth were in equilibrium, which means the influence of human activities was in balance with that of climate change. However, in the 1990s, significant grassland degradation linked to human activities was observed, primarily in the Three-River Headwaters Region. Since the 21st century, this adverse trend continued in the Qinghai Lake area and near the northern provincial boundaries, opposite to what were observed in the eastern part of study. These results are consistent with the currently status of grassland degradation in Qinghai Province, which could serve as a basis for the local grassland management and restoration programs.

Differentiating climate- and human-induced drivers of grassland degradation in the Liao River Basin, China.

PubMed

He, Chunyang; Tian, Jie; Gao, Bin; Zhao, Yuanyuan

2015-01-01

Quantitatively distinguishing grassland degradation due to climatic variations from that due to human activities is of great significance to effectively governing degraded grassland and realizing sustainable utilization. The objective of this study was to differentiate these two types of drivers in the Liao River Basin during 1999-2009 using the residual trend (RESTREND) method and to evaluate the applicability of the method in semiarid and semihumid regions. The relationship between the normalized difference vegetation index (NDVI) and each climatic factor was first determined. Then, the primary driver of grassland degradation was identified by calculating the change trend of the normalized residuals between the observed and the predicted NDVI assuming that climate change was the only driver. We found that the RESTREND method can be used to quantitatively and effectively differentiate climate and human drivers of grassland degradation. We also found that the grassland degradation in the Liao River Basin was driven by both natural processes and human activities. The driving factors of grassland degradation varied greatly across the study area, which included regions having different precipitation and altitude. The degradation in the Horqin Sandy Land, with lower altitude, was driven mainly by human activities, whereas that in the Kungl Prairie, with higher altitude and lower precipitation, was caused primarily by climate change. Therefore, the drivers of degradation and local conditions should be considered in an appropriate strategy for grassland management to promote the sustainability of grasslands in the Liao River Basin.

Mixed artificial grasslands with more roots improved mine soil infiltration capacity

NASA Astrophysics Data System (ADS)

Wu, Gao-Lin; Yang, Zheng; Cui, Zeng; Liu, Yu; Fang, Nu-Fang; Shi, Zhi-Hua

2016-04-01

Soil water is one of the critical limiting factors in achieving sustainable revegetation. Soil infiltration capacity plays a vital role in determining the inputs from precipitation and enhancing water storage, which are important for the maintenance and survival of vegetation patches in arid and semi-arid areas. Our study investigated the effects of different artificial grasslands on soil physical properties and soil infiltration capacity. The artificial grasslands were Medicago sativa, Astragalus adsurgens, Agropyron mongolicum, Lespedeza davurica, Bromus inermis, Hedysarum scoparium, A. mongolicum + Artemisia desertorum, A. adsurgens + A. desertorum and M. sativa + B. inermis. The soil infiltration capacity index (SICI), which was based on the average infiltration rate of stage I (AIRSI) and the average infiltration rate of stage III (AIRS III), was higher (indicating that the infiltration capacity was greater) under the artificial grasslands than that of the bare soil. The SICI of the A. adsurgens + A. desertorum grassland had the highest value (1.48) and bare soil (-0.59) had the lowest value. It was evident that artificial grassland could improve soil infiltration capacity. We also used principal component analysis (PCA) to determine that the main factors that affected SICI were the soil water content at a depth of 20 cm (SWC20), the below-ground root biomasses at depths of 10 and 30 cm (BGB10, BGB30), the capillary porosity at a depth of 10 cm (CP10) and the non-capillary porosity at a depth of 20 cm (NCP20). Our study suggests that the use of Legume-poaceae mixtures and Legume-shrub mixtures to create grasslands provided an effective ecological restoration approach to improve soil infiltration properties due to their greater root biomasses. Furthermore, soil water content, below-ground root biomass, soil capillary porosity and soil non-capillary porosity were the main factors that affect the soil infiltration capacity.

Identifying priority areas for ecosystem service management in South African grasslands.

PubMed

Egoh, Benis N; Reyers, Belinda; Rouget, Mathieu; Richardson, David M

2011-06-01

Grasslands provide many ecosystem services required to support human well-being and are home to a diverse fauna and flora. Degradation of grasslands due to agriculture and other forms of land use threaten biodiversity and ecosystem services. Various efforts are underway around the world to stem these declines. The Grassland Programme in South Africa is one such initiative and is aimed at safeguarding both biodiversity and ecosystem services. As part of this developing programme, we identified spatial priority areas for ecosystem services, tested the effect of different target levels of ecosystem services used to identify priority areas, and evaluated whether biodiversity priority areas can be aligned with those for ecosystem services. We mapped five ecosystem services (below ground carbon storage, surface water supply, water flow regulation, soil accumulation and soil retention) and identified priority areas for individual ecosystem services and for all five services at the scale of quaternary catchments. Planning for individual ecosystem services showed that, depending on the ecosystem service of interest, between 4% and 13% of the grassland biome was required to conserve at least 40% of the soil and water services. Thirty-four percent of the biome was needed to conserve 40% of the carbon service in the grassland. Priority areas identified for five ecosystem services under three target levels (20%, 40%, 60% of the total amount) showed that between 17% and 56% of the grassland biome was needed to conserve these ecosystem services. There was moderate to high overlap between priority areas selected for ecosystem services and already-identified terrestrial and freshwater biodiversity priority areas. This level of overlap coupled with low irreplaceability values obtained when planning for individual ecosystem services makes it possible to combine biodiversity and ecosystem services in one plan using systematic conservation planning. Copyright © 2011 Elsevier Ltd. All

Genetic diversity of calcareous grassland plant species depends on historical landscape configuration.

PubMed

Reisch, Christoph; Schmidkonz, Sonja; Meier, Katrin; Schöpplein, Quirin; Meyer, Carina; Hums, Christian; Putz, Christina; Schmid, Christoph

2017-04-24

Habitat fragmentation is considered to be a main reason for decreasing genetic diversity of plant species. However, the results of many fragmentation studies are inconsistent. This may be due to the influence of habitat conditions, having an indirect effect on genetic variation via reproduction. Consequently we took a comparative approach to analyse the impact of habitat fragmentation and habitat conditions on the genetic diversity of calcareous grassland species in this study. We selected five typical grassland species (Primula veris, Dianthus carthusianorum, Medicago falcata, Polygala comosa and Salvia pratensis) occurring in 18 fragments of calcareous grasslands in south eastern Germany. We sampled 1286 individuals in 87 populations and analysed genetic diversity using amplified fragment length polymorphisms. Additionally, we collected data concerning habitat fragmentation (historical and present landscape structure) and habitat conditions (vegetation structure, soil conditions) of the selected study sites. The whole data set was analysed using Bayesian multiple regressions. Our investigation indicated a habitat loss of nearly 80% and increasing isolation between grasslands since 1830. Bayesian analysis revealed a significant impact of the historical landscape structure, whereas habitat conditions played no important role for the present-day genetic variation of the studied plant species. Our study indicates that the historical landscape structure may be more important for genetic diversity than present habitat conditions. Populations persisting in abandoned grassland fragments may contribute significantly to the species' variability even under deteriorating habitat conditions. Therefore, these populations should be included in approaches to preserve the genetic variation of calcareous grassland species.

Are Agrofuels a conservation threat or opportunity for grassland birds in the United States?

USGS Publications Warehouse

Robertson, Bruce A.; Rice, Robert A.; Ribic, Christine; Babcock, Bruce A.; Landis, Douglas A.; Herkert, James R.; Fletcher, Robert J.; Fontaine, Joseph J; Doran, Patrick J.; Schemske, Douglas W.

2012-01-01

In the United States, government-mandated growth in the production of crops dedicated to biofuel (agrofuels) is predicted to increase the demands on existing agricultural lands, potentially threatening the persistence of populations of grassland birds they support. We review recently published literature and datasets to (1) examine the ability of alternative agrofuel crops and their management regimes to provide habitat for grassland birds, (2) determine how crop placement in agricultural landscapes and agrofuel-related land-use change will affect grassland birds, and (3) identify critical research and policy-development needs associated with agrofuel production. We find that native perennial plants proposed as feedstock for agrofuel (switchgrass, Panicum virgatum, and mixed grass—forb prairie) have considerable potential to provide new habitat to a wide range of grassland birds, including rare and threatened species. However, industrialization of agrofuel production that maximizes biomass, homogenizes vegetation structure, and results in the cultivation of small fields within largely forested landscapes is likely to reduce species richness and/or abundance of grassland-dependent birds. Realizing the potential benefits of agrofuel production for grassland birds' conservation will require the development of new policies that encourage agricultural practices specifically targeting the needs of grassland specialists. The broad array of grower-incentive programs in existence may deliver new agrofuel policies effectively but will require coordination at a spatial scale broader than currently practiced, preferably within an adaptive-management framework.

Conservation Reserve Program mitigates grassland loss in the lesser prairie-chicken range of Kansas

USGS Publications Warehouse

Haukos, David A.; Spencer, David; Hagen, Christian A.; Daniels, Melinda D.; Goodin, Doug

2017-01-01

Since the beginning of the 20th century, the overall occupied range of the lesser prairie-chicken (Tympanuchus pallidicinctus) has declined by 84% commensurate with population trends. Much of this decline has been attributed to the loss and fragmentation of native grasslands throughout the lesser prairie-chicken range. However, quantification of changes in land cover in the distribution of the lesser prairie-chicken is lacking. Our objectives were to (1) document changes in the areal extent and connectivity of grasslands in the identified lesser prairie-chicken range in Kansas, USA, (>60% of extant lesser prairie-chicken population) from the 1950s to 2013 using remotely sensed data and (2) assess the potential of the Conservation Reserve Program (U.S. Department of Agriculture Program converting cropland to permanent cover; CRP) to mitigate grassland loss. Digital land cover maps were generated on a decadal time step through spectral classification of LANDSAT images and visual analysis of aerial photographs (1950s and 1960s). Landscape composition and configuration were assessed using FRAGSTATS to compute a variety of landscape metrics measuring changes in the amount of grassland present as well as changes in the size and configuration of grassland patches. With the exception of a single regional portion of the range, nearly all of the grassland converted to cropland in the lesser prairie-chicken range of Kansas occurred prior to the 1950s. Prior to the implementation of CRP, the amount of grassland decreased 3.6% between the 1950s and 1985 from 18,455 km2 to 17,788 km2. Since 1985, the overall amount of grassland in the lesser prairie-chicken range has increased 11.9% to 19,898 km2 due to implementation of CRP, although the area of grassland decreased between 1994 and 2013 as CRP contracts were not renewed by landowners. Since 1986 grassland in Kansas became more connected and less fragmented in response to the CRP. While the CRP has been successful in

Woody plant encroachment of grasslands: a comparison of terrestrial and wetland settings.

PubMed

Saintilan, Neil; Rogers, Kerrylee

2015-02-01

A global trend of woody plant encroachment of terrestrial grasslands is co-incident with woody plant encroachment of wetland in freshwater and saline intertidal settings. There are several arguments for considering tree encroachment of wetlands in the context of woody shrub encroachment of grassland biomes. In both cases, delimitation of woody shrubs at regional scales is set by temperature thresholds for poleward extent, and by aridity within temperature limits. Latitudinal expansion has been observed for terrestrial woody shrubs and mangroves, following recent warming, but most expansion and thickening has been due to the occupation of previously water-limited grassland/saltmarsh environments. Increases in atmospheric CO₂, may facilitate the recruitment of trees in terrestrial and wetland settings. Improved water relations, a mechanism that would predict higher soil moisture in grasslands and saltmarshes, and also an enhanced capacity to survive arid conditions, reinforces local mechanisms of change. The expansion of woody shrubs and mangroves provides a negative feedback on elevated atmospheric CO₂ by increasing carbon sequestration in grassland and saltmarsh, and is a significant carbon sink globally. These broad-scale vegetation shifts may represent a new stable state, reinforced by positive feedbacks between global change drivers and endogenic mechanisms of persistence in the landscape.

Effects of 10-Year Management Regimes on the Soil Seed Bank in Saline-Alkaline Grassland

PubMed Central

Ma, Hongyuan; Yang, Haoyu; Liang, Zhengwei; Ooi, Mark K. J.

2015-01-01

Background Management regimes for vegetation restoration of degraded grasslands can significantly affect the process of ecological succession. However, few studies have focused on variation in the soil seed bank during vegetation restoration under different management regimes, especially in saline-alkaline grassland habitats. Our aim was to provide insights into the ecological effects of grassland management regimes on soil seed bank composition and vegetation establishment in mown, fenced, transplanted and natural grassland sites, all dominated by the perennial rhizomatous grass Leymus chinensis. Methodology We studied species composition and diversity in both the soil seed bank and aboveground vegetation in differently managed grasslands in Northeast China. An NMDS (nonmetric multidimensional scaling) was used to evaluate the relationship between species composition, soil seed banks, aboveground vegetation and soil properties. Principal Findings Fenced and mown grassland sites had high density and species richness in both the soil seed bank and aboveground vegetation. The Transplanted treatment exhibited the highest vegetation growth and seed production of the target species L. chinensis. Seeds of L. chinensis in the soil occurred only in transplanted and natural grassland. Based on the NMDS analysis, the number of species in both the soil seed bank and aboveground vegetation were significantly related to soil Na+, Cl-, RSC (residual sodium carbonate), alkalinity, ESP (exchangeable sodium percentage) and AP (available phosphorus). Conclusions Soil seed bank composition and diversity in the saline-alkaline grassland were significantly affected by the management regimes implemented, and were also significantly related to the aboveground vegetation and several soil properties. Based on vegetative growth, reproductive output and maintenance of soil seed bank, the transplanting was identified as the most effective method for relatively rapid restoration of the target

Effects of 10-year management regimes on the soil seed bank in saline-alkaline grassland.

PubMed

Ma, Hongyuan; Yang, Haoyu; Liang, Zhengwei; Ooi, Mark K J

2015-01-01

Management regimes for vegetation restoration of degraded grasslands can significantly affect the process of ecological succession. However, few studies have focused on variation in the soil seed bank during vegetation restoration under different management regimes, especially in saline-alkaline grassland habitats. Our aim was to provide insights into the ecological effects of grassland management regimes on soil seed bank composition and vegetation establishment in mown, fenced, transplanted and natural grassland sites, all dominated by the perennial rhizomatous grass Leymus chinensis. We studied species composition and diversity in both the soil seed bank and aboveground vegetation in differently managed grasslands in Northeast China. An NMDS (nonmetric multidimensional scaling) was used to evaluate the relationship between species composition, soil seed banks, aboveground vegetation and soil properties. Fenced and mown grassland sites had high density and species richness in both the soil seed bank and aboveground vegetation. The Transplanted treatment exhibited the highest vegetation growth and seed production of the target species L. chinensis. Seeds of L. chinensis in the soil occurred only in transplanted and natural grassland. Based on the NMDS analysis, the number of species in both the soil seed bank and aboveground vegetation were significantly related to soil Na+, Cl-, RSC (residual sodium carbonate), alkalinity, ESP (exchangeable sodium percentage) and AP (available phosphorus). Soil seed bank composition and diversity in the saline-alkaline grassland were significantly affected by the management regimes implemented, and were also significantly related to the aboveground vegetation and several soil properties. Based on vegetative growth, reproductive output and maintenance of soil seed bank, the transplanting was identified as the most effective method for relatively rapid restoration of the target species L. chinensis. This approach could be

Impact of land use change on soil organic matter dynamics in subalpine grassland

NASA Astrophysics Data System (ADS)

Meyer, Stefanie; Leifeld, Jens; Bahn, Michael; Fuhrer, Jürg

2010-05-01

Information regarding the response of soil organic matter (SOM) in soils to past and expected future land use changes in the European Alps is scarce. Understanding this response requires knowledge of size and residence times of SOM fractions with distinct stabilities. In order to quantify differences between types of land use in the amount, distribution and turnover rates of soil organic carbon (SOC) in subalpine grassland soils, we used soil aggregate and SOM density fractionation in combination with 14C dating. Samples were taken along gradients of different types of land use from meadow (M) to pasture (P) and to abandoned grassland (A) in the Stubai Valley and in the Matsch Valley. Sampling sites in both areas were located at equal altitude (1880 m and 1820 m, respectively) with the same parent material and soil type, but the Matsch Valley receives 400-500 mm less annual rainfall. SOC stocks in the top 10 cm were 2.47 ± 0.32 (M), 2.75 ± 0.32 (P), and 2.50 ± 0.31 kg C/m2 (A) in the Stubai Valley and 2.25 ± 0.14 (M), 3.45 ± 0.22 (P), 3.16 ± 0.27 kg C/m2(A) in the Matsch Valley. Three aggregate size classes were separated by wet sieving: 2 mm. The light floating fraction (wPOM, ρ >1 g/cm3) was included in the analysis. Free (f-) and occluded particulate organic matter (oPOM) were isolated from each aggregate size class (ρ >1.6 g/cm3). At both locations, more than 80% of SOC was stored in small (0.25-2 mm) and large (>2 mm) macroaggregates, but no trend in relation to the different types of land use could be detected. The fraction of C in fPOM and in oPOM in all aggregate size classes was highest for soil from abandoned grasslands. The bulk soil of the abandoned site in the Stubai Valley showed a significantly higher share of fPOM-C and oPOM-C and a higher amount of wPOM-C as compared to the soil from managed grassland, whereas in the Matsch Valley pasture soil had a significantly higher wPOM-C content. At both sites, 13C natural abundance analyses revealed

Oldest Evidence of Toolmaking Hominins in a Grassland-Dominated Ecosystem

PubMed Central

Plummer, Thomas W.; Ditchfield, Peter W.; Bishop, Laura C.; Kingston, John D.; Ferraro, Joseph V.; Braun, David R.; Hertel, Fritz; Potts, Richard

2009-01-01

Background Major biological and cultural innovations in late Pliocene hominin evolution are frequently linked to the spread or fluctuating presence of C4 grass in African ecosystems. Whereas the deep sea record of global climatic change provides indirect evidence for an increase in C4 vegetation with a shift towards a cooler, drier and more variable global climatic regime beginning approximately 3 million years ago (Ma), evidence for grassland-dominated ecosystems in continental Africa and hominin activities within such ecosystems have been lacking. Methodology/Principal Findings We report stable isotopic analyses of pedogenic carbonates and ungulate enamel, as well as faunal data from ∼2.0 Ma archeological occurrences at Kanjera South, Kenya. These document repeated hominin activities within a grassland-dominated ecosystem. Conclusions/Significance These data demonstrate what hitherto had been speculated based on indirect evidence: that grassland-dominated ecosystems did in fact exist during the Plio-Pleistocene, and that early Homo was active in open settings. Comparison with other Oldowan occurrences indicates that by 2.0 Ma hominins, almost certainly of the genus Homo, used a broad spectrum of habitats in East Africa, from open grassland to riparian forest. This strongly contrasts with the habitat usage of Australopithecus, and may signal an important shift in hominin landscape usage. PMID:19844568

Soil greenhouse gas flux, soil moisture, and soil temperature variability among three plant communities from 2015 to 2017 in a High-Arctic lake basin, Northwest Greenland

NASA Astrophysics Data System (ADS)

Konkel, J. M.; Welker, J. M.; Schaeffer, S. M.

2017-12-01

Soil greenhouse gas flux rates are known to vary with plant community and soil environment. Increases in temperature and precipitation are likely to affect the distribution of vegetation and soil conditions in High Arctic ecosystems. In coastal tundra landscapes in northwest Greenland, vegetation, soil organic matter, and greenhouse gas fluxes are thought to be controlled primarily by water availability. In this study, we measured greenhouse gas flux rates, soil moisture, and soil temperature over three summer seasons along a soil moisture gradient in a High Arctic lake basin represented by dry tundra, moist tundra, and wet grassland plant communities. Preliminary results for trace gas fluxes showed N2O production from all three plant communities ranged from 0.03±0.03 to 0.48±0.12 g N ha-1d-1. While wet grassland was a CH4 source up to 5.2±1.1 g C ha-1d-1, dry tundra and moist tundra were CH4 sinks up to -10.4±1.7 and -2.2±0.9 g C ha-1d-1, respectively. For all three seasons, the highest and lowest mean soil CO2 flux rates were measured in wet grassland and moist tundra (up to 18.3±1.1 and 8.7±0.6 kg C ha-1 d-1, respectively). A lab incubation study showed that, with frequent wetting events, soil CO2 flux remained relatively high in wet grassland, was consistently higher in dry tundra than in moist tundra, and dry tundra CO2 flux significantly increased with wetting events. We show that while soil CO2 flux in all three vegetation zones was influenced by soil moisture variability, soil temperature clearly influenced the timing of flux rate increases and decreases over the course of each season. Colder air and soil temperatures in 2017 corresponded with decreased mean soil CO2 flux rates in dry tundra and wet grassland, yet CO2 flux rates remained consistent in moist tundra among all three seasons. These results suggest that climate-induced warmer and wetter soil environmental conditions may increase rates of soil CO2 flux from wet grassland and dry tundra

Can we use the past as a lens to the future? Using historic events to predict regional grassland and shrubland responses to multi-year drought or wet periods under climate change

USDA-ARS?s Scientific Manuscript database

Background/Question/Methods Ecologists are being challenged to predict ecosystem responses under changing climatic conditions. Water availability is the primary driver of ecosystem processes in temperate grasslands and shrublands, but uncertainty in the magnitude and direction of change in precipita...

Management options to limit nitrate leaching from grassland

NASA Astrophysics Data System (ADS)

Cuttle, S. P.; Scholefield, D.

1995-12-01

Nitrate leaching can be reduced by the adoption of less intensive grassland systems which, though requiring a greater land area to achieve the same agricultural output, result in less nitrate leaching per unit of production than do intensively managed grasslands. The economic penalties associated with reductions in output can be partly offset by greater reliance on symbiotic nitrogen fixation and the use of clover-based swards in place of synthetic N fertilisers. Alternatively, specific measures can be adopted to improve the efficiency of nitrogen use in intensively managed systems in order to maintain high outputs but with reduced losses. Controls should take account of other forms of loss and flows of nitrogen between grassland and other components of the whole-farm system and, in most instances, should result in an overall reduction in nitrogen inputs. Removing stock from the fields earlier in the grazing season will reduce the accumulation of high concentrations of potentially leachable nitrate in the soil of grazed pastures but will increase the quantity of manure produced by housed animals and the need to recycle this effectively. Supplementing grass diets with low-nitrogen forages such as maize silage will reduce the quantity of nitrogen excreted by livestock but may increase the potential for nitrate leaching elsewhere on the farm if changes to cropping patterns involve more frequent cultivation of grassland. Improved utilisation by the sward of nitrogen in animal excreta and manures and released by mineralisation of soil organic matter will permit equivalent reductions to be made in fertiliser inputs, provided that adequate information is available about the supply of nitrogen from these non-fertiliser sources.

Influence of Fire and other anthropogenic practices on grassland and shrubland birds in New England

Treesearch

Peter D. Vickery; Benjamin Zuckerburg; Andrea L. Jones; W. Gregory Shriver; Andrew P. Weik

2005-01-01

Since 1966, many species of grassland and shrubland birds have declined substantially in New England (Askins 2000). The extent of grassland and shrubland habitat in New England has changed dramatically over the past 400 years. Presently, grassland and shrubland habitat in New England are created and maintained primarily as a result of four types of habitat management:...

Grasslands ecosystems, endangered species, and sustainable ranching in the Mexico-U.S. borderlands: Conference proceedings

Treesearch

Xavier Basurto; Diana Hadley

2006-01-01

The semi-arid grasslands in the Mexico-United States border region are relatively intact and provide one of the best opportunities in North America to preserve and nurture an extensive series of grassland ecosystems. The conference was organized to increase appreciation for the importance of the remaining semi-arid grasslands and to create a platform for expanding the...

[Edge influence of soil moisture at farmland-grassland boundary in agriculture-pasturage ecotone of northern China].

PubMed

Liu, Hong-lai; Zhang, Wei-hua; Wang, Kun; Zhao, Na

2009-03-01

In the agriculture-pasturage ecotone of Northern China, a typical zone with linear boundary of cropland and grassland was chosen to investigate its soil moisture regime, and the moving split-window technique was adopted to study the edge influence of soil moisture at the boundary. The results showed that the edge influence was 10 m, from 6 m within grassland and 4 m within cropland, and was categorized as the acute change type boundary. Accordingly, the farmland-grassland landscape boundary could be divided into three functional zones, i.e., grassland zone, farmland zone, and compositional ecotone zone. Soil moisture content varied abruptly in the ecotone zone, but presented linear distribution in both grassland zone and farmland zone. The average soil moisture content in grassland was about 1 g x g(-1) higher than that in farmland, which was mainly caused by the decreased capillary moisture capacity of farmland. Owing to the different vegetation cover, farmland and grassland had different transpiration and evaporation, which led to the diverse soil moisture regime, making soil water potential changed and water movement from one ecosystem to another possible.

Aboveground biomass in Tibetan grasslands

Treesearch

Y.H. Yang; J.Y. Fang; Y.D. Pan; C.J. Ji

2009-01-01

This study investigated spatial patterns and environmental controls of aboveground biomass (AGB) in alpine grasslands on the Tibetan Plateau by integrating AGB data collected from 135 sites during 2001-2004 and concurrent enhanced vegetation index derived from MODIS data sets. The AGB was estimated at 68.8 gm-2, with a larger value (90.8 gm

Negative effects of climate change on upland grassland productivity and carbon fluxes are not attenuated by nitrogen status.

PubMed

Eze, Samuel; Palmer, Sheila M; Chapman, Pippa J

2018-05-09

Effects of climate change on managed grassland carbon (C) fluxes and biomass production are not well understood. In this study, we investigated the individual and interactive effects of experimental warming (+3 °C above ambient summer daily range of 9-12 °C), supplemental precipitation (333 mm +15%) and drought (333 mm -23%) on plant biomass, microbial biomass C (MBC), net ecosystem exchange (NEE) and dissolved organic C (DOC) flux in soil cores from two upland grasslands of different soil nitrogen (N) status (0.54% and 0.37%) in the UK. After one month of acclimation to ambient summer temperature and precipitation, five replicate cores of each treatment were subjected to three months of experimental warming, drought and supplemental precipitation, based on the projected regional summer climate by the end of the 21st Century, in a fully factorial design. NEE and DOC flux were measured throughout the experimental duration, alongside other environmental variables including soil temperature and moisture. Plant biomass and MBC were determined at the end of the experiment. Results showed that warming plus drought resulted in a significant decline in belowground plant biomass (-29 to -37%), aboveground plant biomass (-35 to -77%) and NEE (-13 to -29%), regardless of the N status of the soil. Supplemental precipitation could not reverse the negative effects of warming on the net ecosystem C uptake and plant biomass production. This was attributed to physiological stress imposed by warming which suggests that future summer climate will reduce the C sink capacity of the grasslands. Due to the low moisture retention observed in this study, and to verify our findings, it is recommended that future experiments aimed at measuring soil C dynamics under climate change should be carried out under field conditions. Longer term experiments are recommended to account for seasonal and annual variability, and adaptive changes in biota. Copyright © 2018 Elsevier B.V. All

Deposition Fluxes of Terpenes over Grassland

PubMed Central

Bamberger, I.; Hörtnagl, L.; Ruuskanen, T. M.; Schnitzhofer, R.; Müller, M.; Graus, M.; Karl, T.; Wohlfahrt, G.; Hansel, A.

2013-01-01

Eddy covariance flux measurements were carried out for two subsequent vegetation periods above a temperate mountain grassland in an alpine valley using a proton-transfer-reaction – mass spectrometer (PTR-MS) and a PTR-time of flight – mass spectrometer (PTR-TOF). In 2008 and during the first half of the vegetation period 2009 the volume mixing ratios (VMRs) for the sum of monoterpenes (MTs) were typically well below 1 ppbv and neither MT emission nor deposition was observed. After a hailstorm in July 2009 an order of magnitude higher amount of terpenes was transported to the site from nearby coniferous forests causing elevated VMRs. As a consequence, deposition fluxes of terpenes to the grassland, which continued over a time period of several weeks without significant re-emission, were observed. For days without precipitation the deposition occurred at velocities close to the aerodynamic limit. In addition to monoterpene uptake, deposition fluxes of the sum of sesquiterpenes (SQTs) and the sum of oxygenated terpenes (OTs) were detected. Considering an entire growing season for the grassland (i.e., 1st of April to 1st of November), the cumulative carbon deposition of monoterpenes reached 276 mg C m−2. This is comparable to the net carbon emission of methanol (329 mg C m−2), which is the dominant non methane volatile organic compound (VOC) emitted from this site, during the same time period. It is suggested that deposition of monoterpenes to terrestrial ecosystems could play a more significant role in the reactive carbon budget than previously assumed. PMID:24383048

Grassland and shrubland birds of Gettysburg National Military Park and Eisenhower National Historic Site: Current status and management recommendations

USGS Publications Warehouse

Peterjohn, Bruce G.

2007-01-01

Gettysburg National Military Park (NMP) and Eisenhower National Historic Site (NHS) were surveyed for grassland birds during the 2005 breeding season. These parks currently maintain a total of approximately 1,220 ha (3,015 ac) of grassland habitats within a mosaic of cultivated fields and woodlands. The grasslands are hayfields managed through agricultural leases and fields maintained by the National Park Service (NPS). Most grasslands are composed of introduced cool-season grasses, but Gettysburg NMP maintains a few fields dominated by switchgrass (Panicum virgatum) and is creating additional warm-season grasslands. Hayfields managed through agricultural leases support few grassland birds. The most numerous grassland bird communities are found between Seminary and Cemetery ridges in fields managed by the NPS. The parks discourage hay harvesting before July in all fields in an effort to improve the reproductive success of grassland birds.Shrub-dominated habitats were scarce in both parks. A few areas that were harvested recently for timber supported early successional communities in Gettysburg NMP. Other shrublands were limited to narrow corridors (<10 m [32 ft]) bordering fields and drainages. No shrublands were present on Eisenhower NHS, but an abandoned pasture along Willoughby Run was reverting into a mesic shrubland.Four species of obligate grassland birds were recorded during the 2005 surveys. A population of approximately 130 bobolinks (Dolichonyx oryzivorus) was primarily restricted to grasslands between Seminary and Cemetery ridges maintained by the NPS and a hayfield on Eisenhower NHS. This population is large for southeastern Pennsylvania and the surrounding region. Eastern meadowlarks (Sturnella magna) were most numerous in the same fields occupied by bobolinks but smaller numbers were scattered in other grasslands. Grasshopper sparrows (Ammodramus savannarum) were locally distributed in Conservation Reserve Program fields and other grasslands with more

Grassland restoration with and without fire: evidence from a tree-removal experiment

Treesearch

C.B. Halpern; R.D. Haugo; J.A. Antos; S.S. Kaas; A.L. Kilanowski

2012-01-01

Forest encroachment threatens the biological diversity of grasslands globally. Positive feedbacks can reinforce the process, affecting soils and ground vegetation, ultimately leading to replacement of grassland by forest species. We tested whether restoration treatments (tree removal, with or without fire) reversed effects of nearly two centuries of encroachment by...

Habitat availability is a more plausible explanation than insecticide acute toxicity for U.S. grassland bird species declines

USGS Publications Warehouse

Hill, Jason M.; Egan, J. Franklin; Stauffer, Glenn E.; Diefenbach, Duane R.

2014-01-01

Grassland bird species have experienced substantial declines in North America. These declines have been largely attributed to habitat loss and degradation, especially from agricultural practices and intensification (the habitat-availability hypothesis). A recent analysis of North American Breeding Bird Survey (BBS) “grassland breeding” bird trends reported the surprising conclusion that insecticide acute toxicity was a better correlate of grassland bird declines in North America from 1980–2003 (the insecticide-acute-toxicity hypothesis) than was habitat loss through agricultural intensification. In this paper we reached the opposite conclusion. We used an alternative statistical approach with additional habitat covariates to analyze the same grassland bird trends over the same time frame. Grassland bird trends were positively associated with increases in area of Conservation Reserve Program (CRP) lands and cropland used as pasture, whereas the effect of insecticide acute toxicity on bird trends was uncertain. Our models suggested that acute insecticide risk potentially has a detrimental effect on grassland bird trends, but models representing the habitat-availability hypothesis were 1.3–21.0 times better supported than models representing the insecticide-acute-toxicity hypothesis. Based on point estimates of effect sizes, CRP area and agricultural intensification had approximately 3.6 and 1.6 times more effect on grassland bird trends than lethal insecticide risk, respectively. Our findings suggest that preserving remaining grasslands is crucial to conserving grassland bird populations. The amount of grassland that has been lost in North America since 1980 is well documented, continuing, and staggering whereas insecticide use greatly declined prior to the 1990s. Grassland birds will likely benefit from the de-intensification of agricultural practices and the interspersion of pastures, Conservation Reserve Program lands, rangelands and other grassland

Habitat availability is a more plausible explanation than insecticide acute toxicity for U.S. grassland bird species declines.

PubMed

Hill, Jason M; Egan, J Franklin; Stauffer, Glenn E; Diefenbach, Duane R

2014-01-01

Grassland bird species have experienced substantial declines in North America. These declines have been largely attributed to habitat loss and degradation, especially from agricultural practices and intensification (the habitat-availability hypothesis). A recent analysis of North American Breeding Bird Survey (BBS) "grassland breeding" bird trends reported the surprising conclusion that insecticide acute toxicity was a better correlate of grassland bird declines in North America from 1980-2003 (the insecticide-acute-toxicity hypothesis) than was habitat loss through agricultural intensification. In this paper we reached the opposite conclusion. We used an alternative statistical approach with additional habitat covariates to analyze the same grassland bird trends over the same time frame. Grassland bird trends were positively associated with increases in area of Conservation Reserve Program (CRP) lands and cropland used as pasture, whereas the effect of insecticide acute toxicity on bird trends was uncertain. Our models suggested that acute insecticide risk potentially has a detrimental effect on grassland bird trends, but models representing the habitat-availability hypothesis were 1.3-21.0 times better supported than models representing the insecticide-acute-toxicity hypothesis. Based on point estimates of effect sizes, CRP area and agricultural intensification had approximately 3.6 and 1.6 times more effect on grassland bird trends than lethal insecticide risk, respectively. Our findings suggest that preserving remaining grasslands is crucial to conserving grassland bird populations. The amount of grassland that has been lost in North America since 1980 is well documented, continuing, and staggering whereas insecticide use greatly declined prior to the 1990s. Grassland birds will likely benefit from the de-intensification of agricultural practices and the interspersion of pastures, Conservation Reserve Program lands, rangelands and other grassland habitats into

Habitat Availability Is a More Plausible Explanation than Insecticide Acute Toxicity for U.S. Grassland Bird Species Declines

PubMed Central

Hill, Jason M.; Egan, J. Franklin; Stauffer, Glenn E.; Diefenbach, Duane R.

2014-01-01

Grassland bird species have experienced substantial declines in North America. These declines have been largely attributed to habitat loss and degradation, especially from agricultural practices and intensification (the habitat-availability hypothesis). A recent analysis of North American Breeding Bird Survey (BBS) “grassland breeding” bird trends reported the surprising conclusion that insecticide acute toxicity was a better correlate of grassland bird declines in North America from 1980–2003 (the insecticide-acute-toxicity hypothesis) than was habitat loss through agricultural intensification. In this paper we reached the opposite conclusion. We used an alternative statistical approach with additional habitat covariates to analyze the same grassland bird trends over the same time frame. Grassland bird trends were positively associated with increases in area of Conservation Reserve Program (CRP) lands and cropland used as pasture, whereas the effect of insecticide acute toxicity on bird trends was uncertain. Our models suggested that acute insecticide risk potentially has a detrimental effect on grassland bird trends, but models representing the habitat-availability hypothesis were 1.3–21.0 times better supported than models representing the insecticide-acute-toxicity hypothesis. Based on point estimates of effect sizes, CRP area and agricultural intensification had approximately 3.6 and 1.6 times more effect on grassland bird trends than lethal insecticide risk, respectively. Our findings suggest that preserving remaining grasslands is crucial to conserving grassland bird populations. The amount of grassland that has been lost in North America since 1980 is well documented, continuing, and staggering whereas insecticide use greatly declined prior to the 1990s. Grassland birds will likely benefit from the de-intensification of agricultural practices and the interspersion of pastures, Conservation Reserve Program lands, rangelands and other grassland

Shift in soil microbial communities with shrub encroachment in Inner Mongolia grasslands, China

NASA Astrophysics Data System (ADS)

Shen, H.; Li, H.; Zhang, J.; Hu, H.; Chen, L.; Zhu, Y.; Fang, J.

2017-12-01

The ongoing expansion of shrub encroachment into grasslands represents a unique form of land cover change. How this process affects soil microbial communities is poorly understood. In this study, we aim to assess the effects of shrub encroachment on soil microbial biomass, abundance and composition by comparing data between shrub patches and neighboring herb patches in shrub-encroached grasslands (SEGs) in Inner Mongolia, China. Fourteen SEG sites from two ecosystem types (typical and desert grasslands) were investigated. The phospholipid fatty acid (PLFA) method was used to analyze the composition and biomass of the soil microbial community. Our results showed that the top-soil microbial biomass and abundances of gram-negative bacteria, arbuscular mycorrhizal fungi, and actinomycetes were significantly higher in shrub patches than in herb patches in both typical and desert grasslands (P < 0.05). The fungi to bacteria ratio was significantly higher in shrub patches than in herb patches in desert grassland (P < 0.05). The microbial biomass was positively associated with mean annual precipitation, total nitrogen and available phosphorus, and negatively associated with mean annual temperature. Our results also indicated that the variation in microbial composition was largely explained by edaphic factors, followed by climate factors. In conclusion, shrub encroachment in Inner Mongolia grasslands has significantly influenced the structure and abundance of soil microbial communities, which makes the microbial communities toward a fresh organic carbon-based structure. This study highlights the importance of edaphic and climate factors in microbial community shifts in SEGs.

Soil seed-bank composition reveals the land-use history of calcareous grasslands

NASA Astrophysics Data System (ADS)

Karlík, Petr; Poschlod, Peter

2014-07-01

We compared soil seed banks and vegetation of recent (established on abandoned arable fields) and ancient (continuously managed as pastures at least since 1830) calcareous grasslands if there is any impact of former arable field use. The study was carried out in two regions of Southern Germany with well-preserved dry grassland vegetation: the western Jurassic mountains (Kaltes Feld) and the climatically drier eastern part of Southern Germany (Kallmünz). Total number of species in the seed bank was similar in both regions, but species composition partly differed, reflecting phytogeographical differences between the regions. The total number of emerged seedlings showed a large disparity (5457 compared to 2523 seedlings/m2 in Kaltes Feld and Kallmünz, respectively). Though there were differences in seed bank composition and size, we found a uniform pattern of plant traits (affiliation to phytosociological groups, Raunkiaer plant life-forms and seed longevity), which depended on the age of the grassland. The main conclusion is that seed banks in contemporary calcareous grasslands still reflect the history of former land use - in this case arable cultivation, even though it occurred a long time ago (up to 150 years). Indicators of former arable fields are germinable seeds of weeds which have persisted in the soil to the present. By contrast, weedy species are completely absent from the seed banks of ancient grasslands. Soil seed banks of recent grasslands may be of substantial conservation importance because they may store seeds of rare and endangered weed species such as Kickxia spuria, Silene noctiflora and Stachys annua, the majority of which have already gone extinct from the current vegetation of the study sites.

Cellulolytic potential under environmental changes in microbial communities from grassland litter

DOE PAGES

Berlemont, Renaud; Allison, Steven D.; Weihe, Claudia; ...

2014-11-25

We report that in many ecosystems, global changes are likely to profoundly affect microorganisms. In Southern California, changes in precipitation and nitrogen deposition may influence the composition and functional potential of microbial communities and their resulting ability to degrade plant material. To test whether such environmental changes impact the distribution of functional groups involved in leaf litter degradation, we determined how the genomic diversity of microbial communities in a semi-arid grassland ecosystem changed under reduced precipitation or increased N deposition. We monitored communities seasonally over a period of 2 years to place environmental change responses into the context of naturalmore » variation. Fungal and bacterial communities displayed strong seasonal patterns, Fungi being mostly detected during the dry season whereas Bacteria were common during wet periods. Most putative cellulose degraders were associated with 33 bacterial genera and predicted to constitute 18% of the microbial community. Precipitation reduction reduced bacterial abundance and cellulolytic potential whereas nitrogen addition did not affect the cellulolytic potential of the microbial community. Finally, we detected a strong correlation between the frequencies of genera of putative cellulose degraders and cellulase genes. Thus, microbial taxonomic composition was predictive of cellulolytic potential. This work provides a framework for how environmental changes affect microorganisms responsible for plant litter deconstruction.« less

Understanding variation in ecosystem pulse responses to wetting: Benefits of data-model coupling

NASA Astrophysics Data System (ADS)

Jenerette, D.

2011-12-01

Metabolic pulses of activity are a common ecological response to intermittently available resources and in water-limited ecosystems these pulses often occur in response to wetting. Net ecosystem CO2 exchange (NEE) in response to episodic wetting events is hypothesized to have a complex trajectory reflecting the distinct responses, or "pulses", of respiration and photosynthesis. To help direct research activities a physiological-based model of whole ecosystem metabolic activity up- and down-regulation was developed to investigate ecosystem energy balance and gas exchange pulse responses following precipitation events. This model was to investigate pulse dynamics from a local network of sites in southern Arizona, a global network of eddy-covariance ecosystem monitoring sites, laboratory incubation studies, and field manipulations. Pulse responses were found to be ubiquitous across ecosystem types. These pulses had a highly variable influence on NEE following wetting, ranging from large net sinks to sources of CO2 to the atmosphere. Much of the variability in pulse responses of NEE could be described through a coupled up- and down-regulation pulse response model. Respiration pulses were hypothesized to occur through a reduction in whole ecosystem activation energy; this model was both useful and corroborated through laboratory incubation studies of soil respiration. Using the Fluxnet eddy-covariance measurement database event specific responses were combined with the pulse model into an event specific twenty-five day net flux calculation. Across all events observed a general net accumulation of CO2 following a precipitation event, with the largest net uptake within deciduous broadleaf forests and smallest within grasslands. NEE pulses favored greater uptake when pre-event ecosystem respiration rates and total precipitation were higher. While the latter was expected, the former adds to previous theory by suggesting a larger net uptake of CO2 when pre-event metabolic

Winter bird population studies and project prairie birds for surveying grassland birds

Treesearch

Daniel J. Twedt; Paul B. Hamel; Mark S. Woodrey

2008-01-01

We compared 2 survey methods for assessing winter bird communities in temperate grasslands: Winter Bird Population Study surveys are area-searches that have long been used in a variety of habitats whereas Project Prairie Bird surveys employ active-flushing techniques on strip-transects and are intended for use in grasslands.

Effects of plant species richness on 13C assimilate partitioning in artificial grasslands of different established ages

PubMed Central

Xu, Longhua; Yao, Buqing; Wang, Wenying; Wang, Fangping; Zhou, Huakun; Shi, Jianjun; Zhao, Xinquan

2017-01-01

Artificial grasslands play a role in carbon storage on the Qinghai–Tibetan Plateau. The artificial grasslands exhibit decreased proportions of graminate and increased species richness with age. However, the effect of the graminate proportions and species richness on ecosystem C stocks in artificial grasslands have not been elucidated. We conducted an in situ13C pulse-labeling experiment in August 2012 using artificial grasslands that had been established for two years (2Y), five years (5Y), and twelve years (12Y). Each region was plowed fallow from severely degraded alpine meadow in the Qinghai-Tibetan Plateau. The 12Y grassland had moderate proportions of graminate and the highest species richness. This region showed more recovered 13C in soil and a longer mean residence time, which suggests species richness controls the ecosystem C stock. The loss rate of leaf-assimilated C of the graminate-dominant plant species Elymus nutans in artificial grasslands of different ages was lowest in the 12Y grassland, which also had the highest species richness. Thus the lower loss rate of leaf-assimilated C can be partially responsible for the larger ecosystem carbon stocks in the 12Y grassland. This finding is a novel mechanism for the effects of species richness on the increase in ecosystem functioning. PMID:28067300

Wet-Bulb-Globe Temperature Data Report

DTIC Science & Technology

2015-03-01

Hour Min Pressure Dry Nat Wet Globe Dry Nat Wet Globe Dry Nat Wet Globe Wind Cld amt Cld type Obscuration Quest RH Kestrel RH VPSc RH S1 WBGT Q WBGT...Wet Globe Dry Nat Wet Globe Dry Nat Wet Globe Wind Cld amt Cld type Obscuration Quest RH Kestrel RH VPSc RH S1 WBGT Q WBGT K2 WBGT GMT millibars deg F...Dry Nat Wet Globe Dry Nat Wet Globe Wind Cld amt Cld type Obscuration Quest RH Kestrel RH VPSc RH S1 WBGT Q WBGT K2 WBGT GMT millibars deg F deg F deg

Prescribed burning to affect a state transition in a shrub-encroached desert grassland

USDA-ARS?s Scientific Manuscript database

Prescribed burning is a commonly advocated and historical practice for control of woody species encroachment into grasslands on all continents. However, desert grasslands of the southwestern United States often lack needed herbaceous fuel loads for effective prescriptions, dominant perennial gramin...

Association of wintering raptors with Conservation Reserve Enhancement Program grasslands in Pennsylvania

USGS Publications Warehouse

Wilson, A.; Brittingham, M.; Grove, G.

2010-01-01

Conservation grasslands can provide valuable habitat resource for breeding songbirds, but their value for wintering raptors has received little attention. We hypothesized that increased availability of grassland habitat through the Conservation Reserve Enhancement Program (CREP) has resulted in an increase or redistribution in numbers of four species of raptors in Pennsylvania since 2001. We tested this by analyzing winter raptor counts from volunteer surveys, conducted from 2001 to 2008, for Red-tailed Hawks (Buteo jamaicensis), Rough-legged Hawks (Buteo lagopus), Northern Harriers (Circus cyaneus), and American Kestrels (Falco sparverius). During that period, numbers of wintering Northern Harriers increased by more than 20% per year. Log-linear Poisson regression models show that all four species increased in the region of Pennsylvania that had the most and longest-established conservation grasslands. At the county scale (N= 67), Bayesian spatial models showed that spatial and temporal population trends of all four species were positively correlated with the amount of conservation grassland. This relationship was particularly strong for Northern Harriers, with numbers predicted to increase by 35.7% per year for each additional 1% of farmland enrolled in CREP. Our results suggest that conservation grasslands are likely the primary cause of the increase in numbers of wintering Northern Harriers in Pennsylvania since 2001. ?? 2010 The Authors. Journal of Field Ornithology ?? 2010 Association of Field Ornithologists.

Breeding biology and nest-site selection of red-tailed hawks in an altered desert grassland

USGS Publications Warehouse

Hobbs, R.J.; DeStefano, S.; Halvorson, W.L.

2006-01-01

Red-tailed Hawks (Buteo jamaicensis) have expanded their range as trees have invaded formerly-open grasslands. Desert grasslands of southern Arizona have been invaded by mesquite trees (Prosopis velutina) since Anglo-American settlement and now support a large population of Red-tailed Hawks. We studied a population of Red-tailed Hawks in an altered desert grassland in southern Arizona. Our objectives were to determine what environmental characteristics influence Red-tailed Hawk habitat selection in mesquite-invaded desert grasslands and to evaluate the habitat quality of these grasslands for Red-tailed Hawks based on nesting density, nest success, and productivity. Red-tailed Hawks had 86% (95% C.I. = 73-99) nest success and 1.82 young per breeding pair (95% C.I. = 1.41-2.23). Nesting density was 0.15 (95% CI = 0.08-0.21) breeding pairs/km2 and the mean nearest-neighbor distance was 1.95 km (95% C.I. = 1.74-2.16). Red-tailed Hawks selected nest-sites with taller nest-trees and greater tree height and cover than were available at random. Mesquite trees in desert grasslands provide abundant potential nesting structures for Red-tailed Hawks. ?? 2006 The Raptor Research Foundation, Inc.

The effects of climatic and CO[sub 2] changes on grassland storage of soil carbon

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

Ojima, D.S.; Parton, W.J.; Schimel, D.S.

1993-06-01

We present results from analysis of the sensitivity of global grassland ecosystems to modified climate. We assess over 30 grassland sites from around the world under two different GCM double CO[sub 2] climates. The results indicate that soil C losses occur in Ar grassland regions (losses range from 1.6 to 8.8% of current soil C levels for the surface 20 cm). The Eurasian grasslands lost the greatest amount of soil C ([approximately]700 g C/m[sub 2]) and the other temperate grasslands lost approximately half this amount. The tropical grasslands and savannas lost the least amount of soil C per unit areamore » (ranging from no change to 130 g C/m[sub 2] losses). Plant production varies according to modifications in rainfall amounts under the altered climate and to altered nitrogen mineralization rates. The two GCM's differed in predictions of rainfall with a doubling of CO[sub 2], and this difference is reflected in plant production. Soil decomposition rates responded most predictably to changes in temperature. CO[sub 2] fertilization effects on soil C loss and plant production tended to reduce the net impact of climate alterations.« less

Grassland bird use of oak barrens and dry prairies in Wisconsin

USGS Publications Warehouse

Vos, Susan M.; Ribic, Christine A.

2011-01-01

Grassland bird populations have declined more than any other group of birds in North America and are of conservation concern to state and federal agencies. We determined relative abundances of grassland birds in oak barrens and dry sand prairies—native habitat types rare in the state of Wisconsin. We also investigated the association of relative abundance, patch size, and patch vegetation. Our study was conducted May–July 2000–2002 on Fort McCoy Military Installation in Monroe County, Wisconsin. Fourteen grassland bird species were found in native habitat patches. Vesper sparrow (Pooecetes gramineus), grasshopper sparrow (Ammodramus savannarum), and field sparrow (Spizella pusilla) were the most abundant grassland bird species; all are species of management concern in Wisconsin. Of the most abundant species, only grasshopper sparrow relative abundance increased as patch size increased; vesper sparrow and field sparrow relative abundances decreased as patch size increased. Though found at lower relative abundances, horned larks (Erephila alpestris), savannah sparrows (Passerculus sandwichensis), and upland sandpipers (Bartramia longicauda) were found at higher relative abundances as patch size increased. Patch vegetation was important for some species. Vesper sparrows were found at higher abundances in patches with shorter, less dense vegetation and higher woody cover, eastern meadowlark (Sturnella magna) relative abundances were higher in patches with higher proportions of grass, and dickcissel (Spiza americana) relative abundances were higher in patches with taller, denser vegetation and lower proportions of litter. Native habitats are important for grassland bird species of management concern and large patches are particularly important for some of them.

Grazing effects on grassland ecosystems

Treesearch

Linda L. Wallace; Mel I. Dyer

1996-01-01

In this study, we used a modified version of a meta-analysis (compilation and analysis of the literature in which an individual area is subjected to the disturbance and its response is noted) to analyze grazing effects on grassland ecosystems. Prior efforts have focused on one aspect of ecosystem behavior such as productivity or species diversity. In this analysis, we...

Using Remotely Sensed Fluorescence and Soil Moisture to Better Understand the Seasonal Cycle of Tropical Grasslands

NASA Astrophysics Data System (ADS)

Smith, Dakota Carlysle

Seasonal grasslands account for a large area of Earth's land cover. Annual and seasonal changes in these grasslands have profound impacts on Earth's carbon, energy, and water cycles. In tropical grasslands, growth is commonly water-limited and the landscape oscillates between highly productive and unproductive. As the monsoon begins, soils moisten providing dry grasses the water necessary to photosynthesize. However, along with the rain come clouds that obscure satellite products that are commonly used to study productivity in these areas. To navigate this issue, we used solar induced fluorescence (SIF) products from OCO-2 along with soil moisture products from the Soil Moisture Active Passive satellite (SMAP) to "see through" the clouds to monitor grassland productivity. To get a broader understanding of the vegetation dynamics, we used the Simple Biosphere Model (SiB4) to simulate the seasonal cycles of vegetation. In conjunction with SiB4, the remotely sensed SIF and soil moisture observations were utilized to paint a clearer picture of seasonal productivity in tropical grasslands. The remotely sensed data is not available for every place at one time or at every time for one place. Thus, the study was focused on a large area from 15° E to 35° W and from 8°S to 20°N in the African Sahel. Instead of studying productivity relative to time, we studied it relative to soil moisture. Through this investigation we found soil moisture thresholds for the emergence of grassland growth, near linear grassland growth, and maturity of grassland growth. We also found that SiB4 overestimates SIF by about a factor of two for nearly every value of soil moisture. On the whole, SiB4 does a surprisingly good job of predicting the response of seasonal growth in tropical grasslands to soil moisture. Future work will continue to integrate remotely sensed SIF & soil moisture with SiB4 to add to our growing knowledge of carbon, water, and energy cycling in tropical grasslands.

Differential Sensitivity to Drought in Six Central U.S. Grasslands

NASA Astrophysics Data System (ADS)

Knapp, A.; Carroll, C. J. W.; Denton, E. M.; La Pierre, K. J.; Wilcox, K. R.; Collins, S. L.; Smith, M.

2014-12-01

Terrestrial ecosystems often vary dramatically in their responses to drought, but the reasons why are unclear. With climate change forecasts for more frequent and extensive drought in the future, a more complete understanding of the mechanisms that determine differential ecosystem sensitivity to drought is needed. In 2012, the Central U.S. experienced the 4th largest drought in a century, with a regional-scale 40% reduction in growing season precipitation affecting ecosystems ranging from desert grassland to mesic tallgrass prairie. This provided an opportunity to assess ecosystem sensitivity to a drought of common magnitude in six native grasslands. We tested the prediction that drought sensitivity is inversely related to mean annual precipitation (MAP) by quantifying reductions in aboveground net primary production (ANPP). Long-term ANPP data available for each site (mean length = 16 yrs) were used as a baseline for calculating reductions in ANPP, and drought sensitivity was estimated as the reduction in ANPP per mm reduction in precipitation. Arid grasslands were the most sensitive to drought, but drought responses and sensitivity varied by more than 2-fold among the six grasslands, despite all sites experiencing 40% reductions in growing season precipitation. Although drought sensitivity generally decreased with increasing MAP as predicted, there was evidence that the identity and traits of the dominant species, as well as plant functional diversity, influenced sensitivity.

Evaluation of SPOT imagery for the estimation of grassland biomass

NASA Astrophysics Data System (ADS)

Dusseux, P.; Hubert-Moy, L.; Corpetti, T.; Vertès, F.

2015-06-01

In many regions, a decrease in grasslands and change in their management, which are associated with agricultural intensification, have been observed in the last half-century. Such changes in agricultural practices have caused negative environmental effects that include water pollution, soil degradation and biodiversity loss. Moreover, climate-driven changes in grassland productivity could have serious consequences for the profitability of agriculture. The aim of this study was to assess the ability of remotely sensed data with high spatial resolution to estimate grassland biomass in agricultural areas. A vegetation index, namely the Normalized Difference Vegetation Index (NDVI), and two biophysical variables, the Leaf Area Index (LAI) and the fraction of Vegetation Cover (fCOVER) were computed using five SPOT images acquired during the growing season. In parallel, ground-based information on grassland growth was collected to calculate biomass values. The analysis of the relationship between the variables derived from the remotely sensed data and the biomass observed in the field shows that LAI outperforms NDVI and fCOVER to estimate biomass (R2 values of 0.68 against 0.30 and 0.50, respectively). The squared Pearson correlation coefficient between observed and estimated biomass using LAI derived from SPOT images reached 0.73. Biomass maps generated from remotely sensed data were then used to estimate grass reserves at the farm scale in the perspective of operational monitoring and forecasting.

Emissions from miombo woodland and dambo grassland savanna fires

NASA Astrophysics Data System (ADS)

Sinha, Parikhit; Hobbs, Peter V.; Yokelson, Robert J.; Blake, Donald R.; Gao, Song; Kirchstetter, Thomas W.

2004-06-01

Airborne measurements of trace gases and particles over and downwind of two prescribed savanna fires in Zambia are described. The measurements include profiles through the smoke plumes of condensation nucleus concentrations and normalized excess mixing ratios of particles and gases, emission factors for 42 trace gases and seven particulate species, and vertical profiles of ambient conditions. The fires were ignited in plots of miombo woodland savanna, the most prevalent savanna type in southern Africa, and dambo grassland savanna, an important enclave of miombo woodland ecosystems. Emission factors for the two fires are combined with measurements of fuel loading, combustion factors, and burned area (derived from satellite burn scar retrievals) to estimate the emissions of trace gases and particles from woodland and grassland savanna fires in Zambia and southern Africa during the dry season (May-October) of 2000. It is estimated that the emissions of CO2, CO, total hydrocarbons, nitrogen oxides (NOx as NO), sulfur dioxide (SO2), formaldehyde, methyl bromide, total particulate matter, and black carbon from woodland and grassland savanna fires during the dry season of 2000 in southern Africa contributed 12.3%, 12.6%, 5.9%, 10.3%, 7.5%, 24.2%, 2.8%, 17.5%, and 11.1%, respectively, of the average annual emissions from all types of savanna fires worldwide. In 2000 the average annual emissions of methane, ethane, ethene, acetylene, propene, formaldehyde, methanol, and acetic acid from the use of biofuels in Zambia were comparable to or exceeded dry season emissions of these species from woodland and grassland savanna fires in Zambia.

Emissions from Miombo Woodland and Dambo Grassland Savanna Fires

NASA Technical Reports Server (NTRS)

Sinha, Parikhit; Hobbs, Peter V.; Yokelson, Robert J.; Blake, Donald R.; Gao, Song; Kirchstetter, Thomas W.

2004-01-01

Airborne measurements of trace gases and particles over and downwind of two prescribed savanna fires in Zambia are described. The measurements include profiles through the smoke plumes of condensation nucleus concentrations and normalized excess mixing ratios of particles and gases, emission factors for 42 trace gases and seven particulate species, and vertical profiles of ambient conditions. The fires were ignited in plots of miombo woodland savanna, the most prevalent savanna type in southern Africa, and dambo grassland savanna, an important enclave of miombo woodland ecosystems. Emission factors for the two fires are combined with measurements of fuel loading, combustion factors, and burned area (derived from satellite burn scar retrievals) to estimate the emissions of trace gases and particles from woodland and grassland savanna fires in Zambia and southern Africa during the dry season (May-October) of 2000. It is estimated that the emissions of CO2, CO, total hydrocarbons, nitrogen oxides (NOx as NO), sulfur dioxide (SO2), formaldehyde, methyl bromide, total particulate matter, and black carbon from woodland and grassland savanna fires during the dry season of 2000 in southern Africa contributed 12.3%, 12.6%, 5.9%, 10.3%, 7.5%, 24.2%, 2.8%, 17.5%, and 11.1%, respectively, of the average annual emissions from all types of savanna fires worldwide. In 2000 the average annual emissions of methane, ethane, ethene, acetylene, propene, formaldehyde, methanol, and acetic acid from the use of biofuels in Zambia were comparable to or exceeded dry season emissions of these species from woodland and grassland savanna fires in Zambia.

Financial appraisal of wet mesophilic AD technology as a renewable energy and waste management technology.

PubMed

Dolan, T; Cook, M B; Angus, A J

2011-06-01

Anaerobic digestion (AD) has the potential to support diversion of organic waste from landfill and increase renewable energy production. However, diffusion of this technology has been uneven, with countries such as Germany and Sweden taking the lead, but limited diffusion in other countries such as the UK. In this context, this study explores the financial viability of AD in the UK to offer reasons why it has not been more widely used. This paper presents a model that calculates the Internal Rate of Return (IRR) on a twenty year investment in a 30,000 tonnes per annum wet mesophilic AD plant in the UK for the treatment of source separated organic waste, which is judged to be a suitable technology for the UK climate. The model evaluates the financial significance of the different alternative energy outputs from this AD plant and the resulting economic subsidies paid for renewable energy. Results show that renewable electricity and renewable heat sales supported by renewable electricity and renewable heat tariffs generates the greatest IRR (31.26%). All other uses of biogas generate an IRR in excess of 15%, and are judged to be a financially viable investment. Sensitivity analysis highlights the financial significance of: economic incentive payments and a waste management gate fee; and demonstrates that the fate of the digestate by-product is a source of financial uncertainty for AD investors. Copyright © 2011 Elsevier B.V. All rights reserved.

Livestock grazing supports native plants and songbirds in a California annual grassland.

PubMed

Gennet, Sasha; Spotswood, Erica; Hammond, Michele; Bartolome, James W

2017-01-01

Over eight years we measured the effects of plant community composition, vegetation structure, and livestock grazing on occurrence of three grassland bird species-Western Meadowlark (Sturnella neglecta), Horned Lark (Eremophila alpestris), and Grasshopper Sparrow (Ammodramus savannarum)-at sites in central California during breeding season. In California's Mediterranean-type climatic region, coastal and inland grassland vegetation is dominated by exotic annual grasses with occasional patches of native bunchgrass and forbs. Livestock grazing, primarily with beef cattle, is the most widely used management tool. Compared with ungrazed plots, grazed plots had higher bare ground, native plant cover, and vertically heterogeneous vegetation. Grazed plots also had less plant litter and shorter vegetation. Higher native plant cover, which is predominantly composed of bunchgrasses in our study area, was associated with livestock grazing and north-facing aspects. Using an information theoretic approach, we found that all three bird species had positive associations with native plant abundance and neutral (Western Meadowlark, Grasshopper Sparrow) or positive (Horned Lark) association with livestock grazing. All species favored flatter areas. Horned Larks and Western Meadowlark occurred more often where there were patches of bare ground. Western Meadowlarks and Grasshopper Sparrows were most common on north-facing slopes, suggesting that these species may be at risk from projected climate change. These findings demonstrate that livestock grazing is compatible with or supports grassland bird conservation in Mediterranean-type grasslands, including areas with high levels of exotic annual grass invasion, in part because grazing supports the persistence of native plants and heterogeneity in vegetation structure. However, conservation of low-lying grasslands with high native species presence, and active management to increase the abundance of native plant species are also likely to

The Influence of Land Use on the Grassland Fire Occurrence in the Northeastern Inner Mongolia Autonomous Region, China.

PubMed

Li, Yiping; Zhao, Jianjun; Guo, Xiaoyi; Zhang, Zhengxiang; Tan, Gang; Yang, Jihong

2017-02-23

Grassland, as one of the most important ecosystems on Earth, experiences fires that affect the local ecology, economy and society. Notably, grassland fires occur frequently each year in northeastern China. Fire occurrence is a complex problem with multiple causes, such as natural factors, human activities and land use. This paper investigates the disruptive effects of grassland fire in the northeastern Inner Mongolia Autonomous Region of China. In this study, we relied on thermal anomaly detection from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor to identify fire occurrences, and land use data were acquired by Landsat Thematic Mapper/Enhanced Thematic Mapper (TM/ETM). We discussed the relationship between land use and the spatial distribution of grassland fires. The results showed that the impact of land use on grassland fires was significant. Spatially, approximately 80% of grassland fires were clustered within 10 km of cultivated land, and grassland fires generally occurred in areas of intense human activity. The correlation between the spatial distribution of grassland fires and the land use degree in 2000, 2005 and 2010 was high, with R² values of 0.686, 0.716, 0.633, respectively ( p < 0.01). These results highlight the importance of the relationship between land use and grassland fire occurrence in the northeastern Inner Mongolia Autonomous Region. This study provides significance for local fire management and prevention.

The Influence of Land Use on the Grassland Fire Occurrence in the Northeastern Inner Mongolia Autonomous Region, China

PubMed Central

Li, Yiping; Zhao, Jianjun; Guo, Xiaoyi; Zhang, Zhengxiang; Tan, Gang; Yang, Jihong

2017-01-01

Grassland, as one of the most important ecosystems on Earth, experiences fires that affect the local ecology, economy and society. Notably, grassland fires occur frequently each year in northeastern China. Fire occurrence is a complex problem with multiple causes, such as natural factors, human activities and land use. This paper investigates the disruptive effects of grassland fire in the northeastern Inner Mongolia Autonomous Region of China. In this study, we relied on thermal anomaly detection from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor to identify fire occurrences, and land use data were acquired by Landsat Thematic Mapper/Enhanced Thematic Mapper (TM/ETM). We discussed the relationship between land use and the spatial distribution of grassland fires. The results showed that the impact of land use on grassland fires was significant. Spatially, approximately 80% of grassland fires were clustered within 10 km of cultivated land, and grassland fires generally occurred in areas of intense human activity. The correlation between the spatial distribution of grassland fires and the land use degree in 2000, 2005 and 2010 was high, with R2 values of 0.686, 0.716, 0.633, respectively (p < 0.01). These results highlight the importance of the relationship between land use and grassland fire occurrence in the northeastern Inner Mongolia Autonomous Region. This study provides significance for local fire management and prevention. PMID:28241476

Evaluating the Impacts of Grassland Conversions to Experimental Forest on Groundwater Recharge in the Nebraska Sand Hills

NASA Astrophysics Data System (ADS)

Adane, Zablon A.

The Nebraska Sand Hills grasslands provide the greatest groundwater recharge rates in the High Plains Aquifer. However, the grasslands and their ecological services have become vulnerable to land use change and degradation. This study used a series of field data to investigate the effects of grassland conversions to forest on recharge rates in a century-old experimental forest in the Sand Hills. The results show that the impact of grassland conversion on recharge was dependent on the species and plantation density. Estimated recharge rates beneath the dense plantations represent reductions of 86-94% relative to the native grassland. Results of 1H Nuclear Magnetic Resonance spectral analysis suggested that the surface soil organic carbon beneath pine plantations also contain up to 3 times the ratio of hydrophobic components than the native grasslands and may alter the soil hydraulic properties. This investigation further uncovered a previously overlooked feedback between the effect of soil organic carbon chemical shift generated by the ponderosa pine needle litter decomposition; namely that the alteration may have a link to reduced groundwater recharge rates. Thus, a global optimizer algorithm was used to estimate the effective soil hydraulic parameters from monthly soil moisture contents and recharge rates were then estimated through HYDRUS 1-D numerical modeling for grassland and pine forest soils. The impact of grassland conversion to pine was an overall reduction of groundwater recharge by nearly 100%. These outcomes highlight the significance of the grasslands for recharge, in the Sand Hills and the sustainability of the High Plains Aquifer.

The effects of mesquite invasion on a southeastern Arizona grassland bird community

USGS Publications Warehouse

Lloyd, J.; Mannan, R.W.; DeStefano, S.; Kirkpatrick, C.

1998-01-01

We determined which vegetal features influenced the distribution and abundance of grassland birds at the Buenos Aires National Wildlife Refuge, Arizona. The density and distribution of mesquite (Prosopis velutina) exerted the strongest influence on the grassland bird community. Abundances of Pyrrhuloxia (Cardinalis sinuatus; r2 = 0.363, P = 0.025) and Lucy's Warbler (Vermivora luciae; r2 = 0.348, P = 0.04), and total abundance of birds (r2 = 0.358, P = 0.04) were positively correlated with increasing density of mesquite (Prosopis velutina), whereas abundance of Cactus Wren (Campylorhynchus brunneicapillus; r2 = 0.452, P = 0.02) was negatively correlated with increasing mesquite density. Abundance of Loggerhead Shrike (Lanius ludovicianus; r2 = 0.693, P < 0.001) was positively correlated with an increasing patchiness of mesquite. Shrub-dependent bird species dominated the community, accounting for 12 of the 18 species and 557 of the 815 individuals detected. Species relying on extensive areas of open grassland were largely absent from the study area, perhaps a result of the recent invasion of mesquite into this semi-desert grassland.

Challenges Associated with Estimating Utility in Wet Age-Related Macular Degeneration: A Novel Regression Analysis to Capture the Bilateral Nature of the Disease.

PubMed

Hodgson, Robert; Reason, Timothy; Trueman, David; Wickstead, Rose; Kusel, Jeanette; Jasilek, Adam; Claxton, Lindsay; Taylor, Matthew; Pulikottil-Jacob, Ruth

2017-10-01

The estimation of utility values for the economic evaluation of therapies for wet age-related macular degeneration (AMD) is a particular challenge. Previous economic models in wet AMD have been criticized for failing to capture the bilateral nature of wet AMD by modelling visual acuity (VA) and utility values associated with the better-seeing eye only. Here we present a de novo regression analysis using generalized estimating equations (GEE) applied to a previous dataset of time trade-off (TTO)-derived utility values from a sample of the UK population that wore contact lenses to simulate visual deterioration in wet AMD. This analysis allows utility values to be estimated as a function of VA in both the better-seeing eye (BSE) and worse-seeing eye (WSE). VAs in both the BSE and WSE were found to be statistically significant (p < 0.05) when regressed separately. When included without an interaction term, only the coefficient for VA in the BSE was significant (p = 0.04), but when an interaction term between VA in the BSE and WSE was included, only the constant term (mean TTO utility value) was significant, potentially a result of the collinearity between the VA of the two eyes. The lack of both formal model fit statistics from the GEE approach and theoretical knowledge to support the superiority of one model over another make it difficult to select the best model. Limitations of this analysis arise from the potential influence of collinearity between the VA of both eyes, and the use of contact lenses to reflect VA states to obtain the original dataset. Whilst further research is required to elicit more accurate utility values for wet AMD, this novel regression analysis provides a possible source of utility values to allow future economic models to capture the quality of life impact of changes in VA in both eyes. Novartis Pharmaceuticals UK Limited.

Spatial probability models of fire in the desert grasslands of the southwestern USA

USDA-ARS?s Scientific Manuscript database

Fire is an important driver of ecological processes in semiarid environments; however, the role of fire in desert grasslands of the Southwestern US is controversial and the regional fire distribution is largely unknown. We characterized the spatial distribution of fire in the desert grassland region...

Evaluating effects of habitat loss and land-use continuity on ant species richness in seminatural grassland remnants.

PubMed

Dauber, Jens; Bengtsson, Jan; Lenoir, Lisette

2006-08-01

Seminatural grasslands in Europe are susceptible to habitat destruction and fragmentation that result in negative effects on biodiversity because of increased isolation and area effects on extinction rate. However even small habitatpatches of seminatural grasslands might be of value for conservation and restoration of species richness in a landscape with a long history of management, which has been argued to lead to high species richness. We tested whether ant communities have been negatively affected by habitat loss and increased isolation of seminatural grasslands during the twentieth century. We examined species richness and community composition in seminatural grasslands of different size in a mosaic landscape in Central Sweden. Grasslands managed continuously over centuries harbored species-rich and ecologically diverse ant communities. Grassland remnant size had no effect on ant species richness. Small grassland remnants did not harbor a nested subset of the ant species of larger habitats. Community composition of ants was mainly affected by habitat conditions. Our results suggest that the abandonment of traditional land use and the encroachment of trees, rather than the effects of fragmentation, are important for species composition in seminatural grasslands. Our results highlight the importance of considering land-use continuity and dispersal ability of thefocal organisms when examining the effects of habitat loss and fragmentation on biodiversity. Landscape history should be considered in conservation programs focusing on effects of land-use change.

The paradox of the individual household responsibility system in the grasslands of the Tibetan Plateau, China

Treesearch

Camille Richard; Yan Zhaoli; Du Guozhen

2006-01-01

Grasslands of the Tibetan plateau are commonly believed to be degrading as a result of unsustainable grazing practices. In response, the Grassland Law attempts to allocate grasslands based on the Individual Household Responsibility System model that has worked in the agricultural areas of China. However, the actual tenure scenario in the rangelands of Tibet is not as...

[Projected changes in vegetation net primary productivity of grassland in Inner Mongolia, China during 2011-2050.

PubMed

Guo, Ling Hui; Hao, Cheng Yuan; Wu, Shao Hong; Gao, Jiang Bo; Zhao, Dong Sheng

2016-03-01

In this paper, the CENTURY-based modeling system (complying CENTURY model from a site-based model into spatial model) after being systematically calibrated was used to investigate future climate change under Representative Concentration Pathways Scenario (RCP, 4.5 and 8.5) driven spatio-temporal changes in vegetation net primary productivity (NPP) of Inner Mongolia grassland during 2011-2050. The simulation showed that Inner Mongolia grassland NPP would greatly decrease with a rate of 0.57 g C·m -2 ·a -1 (RCP4.5) and 0.89 g C·m -2 ·a -1 (RCP8.5). NPP of Inner Mongolia grassland appeared to decrease by approximately 11.6% (2020s), 12.0% (2030s) and 18.0% (2040s) under the RCP4.5 in relation to baseline period, while its reduction could be exacerbated as 23.8% (2020s), 21.2% (2030s) and 30.1% (2040s) in the RCP8.5 at the regional scale. In addition, grassland NPP induced by future climate changes varied between different grassland types and times, strongly correlating with climate scenario. Even for the RCP4.5, however, a great majority (89.7%) of the grassland exhibited a decreasing trend in annual NPP, with 15.6% of the area decreasing by more than 20% compared with the baseline term. Therefore, although future precipitation rising could benefit vegetation growth, it might be still not enough to compensate for the negative effect of warming on the NPP of Inner Mongolia grassland, and the sustainable development of grassland resources might face a greater challenge.

The effects of fire events on soil geochemistry in semi-arid grasslands

Treesearch

Thomas H. Biggs; Lisa N. Florkowski; Philip A. Pearthree; Pei-Jen L. Shaner

2005-01-01

Throughout the southwestern United States, vegetation in what historically was grassland has changed to a mixture of trees and shrubs; exotic grass species and undesirable shrubs have also invaded the grasslands at the expense of native grasses. The availability and amount of soil nutrients influence the relative success of plants, but few studies have examined fire...

Prairie chickens on the Sheyenne National Grasslands: September 18, 1987; Crookston, Minnesota

Treesearch

Ardell J. Bjugstad

1988-01-01

Prairie chickens (Tympanuchus cupido pinnatus) were first censused on the Sheyenne Grasslands in 1961. The population was extremely low in the 1960's, gradually increased in the 1970's, and reached a peak of 410 in 1980. Sufficient evidence exists to link the increase in numbers of prairie chickens on the grasslands from 1961 through 1987...

Trajectories of grassland ecosystem change in response to experimental manipulations of precipitation

NASA Astrophysics Data System (ADS)

Knapp, Alan; Smith, Melinda; Collins, Scott; Blair, John; Briggs, John

2010-05-01

Understanding and predicting the dynamics of ecological systems has always been central to Ecology. Today, ecologists recognize that in addition to natural and human-caused disturbances, a fundamentally different type of ecosystem change is being driven by the combined and cumulative effects of anthropogenic activities affecting earth's climate and biogeochemical cycles. This type of change is historically unprecedented in magnitude, and as a consequence, such alterations are leading to trajectories of change in ecological responses that differ radically from those observed in the past. Through both short- and long-term experiments, we have been trying to better understand the mechanisms and consequences of ecological change in grassland ecosystems likely to result from changes in precipitation regimes. We have manipulated a key resource for most grasslands (water) and modulators of water availability (temperature) in field experiments that vary from 1-17 years in duration, and used even longer-term monitoring data from the Konza Prairie LTER program to assess how grassland communities and ecosystems will respond to changes in water availability. Trajectories of change in aboveground net primary production (ANPP) in sites subjected to 17 years of soil water augmentation were strongly non-linear with a marked increase in the stimulation of ANPP after year 8 (from 25% to 65%). Lags in alterations in grassland community composition are posited to be responsible for the form of this trajectory of change. In contrast, responses in ANPP to chronic increases in soil moisture variability appear to have decreased over a 10-yr period of manipulation, although the net effects of more variable precipitation inputs were to reduce ANPP, alter the genetic structure of the dominant grass species, increase soil nitrogen availability and reduce soil respiration. The loss of sensitivity to increased resource variability was not reflected in adjacent plots where precipitation was

Increasing temperature reduces the coupling between available nitrogen and phosphorus in soils of Chinese grasslands

NASA Astrophysics Data System (ADS)

Geng, Yan; Baumann, Frank; Song, Chao; Zhang, Mi; Shi, Yue; Kühn, Peter; Scholten, Thomas; He, Jin-Sheng

2017-03-01

Changes in climatic conditions along geographical gradients greatly affect soil nutrient cycling processes. Yet how climate regimes such as changes in temperature influence soil nitrogen (N) and phosphorus (P) concentrations and their stoichiometry is not well understood. This study investigated the spatial pattern and variability of soil N and P availability as well as their coupling relationships at two soil layers (0-10 and 10-20 cm) along a 4000-km climate transect in two grassland biomes of China, the Inner Mongolian temperate grasslands and the Tibetan alpine grasslands. Our results found that in both grasslands, from cold to warm sites the amounts of soil total N, total P and available P all decreased. By contrast, the amount of available N was positively related to mean annual temperature in the Tibetan grasslands. Meanwhile, with increasing temperature ratio of available N to P significantly increased but the linear relationship between them was considerably reduced. Thus, increasing temperature may not only induce a stoichiometric shift but also loose the coupling between available N and P. This N-P decoupling under warmer conditions was more evident in the Tibetan alpine grasslands where P limitation might become more widespread relative to N as temperatures continue to rise.

PRAIRIEMAP: A GIS database for prairie grassland management in western North America

USGS Publications Warehouse

,

2003-01-01

The USGS Forest and Rangeland Ecosystem Science Center, Snake River Field Station (SRFS) maintains a database of spatial information, called PRAIRIEMAP, which is needed to address the management of prairie grasslands in western North America. We identify and collect spatial data for the region encompassing the historical extent of prairie grasslands (Figure 1). State and federal agencies, the primary entities responsible for management of prairie grasslands, need this information to develop proactive management strategies to prevent prairie-grassland wildlife species from being listed as Endangered Species, or to develop appropriate responses if listing does occur. Spatial data are an important component in documenting current habitat and other environmental conditions, which can be used to identify areas that have undergone significant changes in land cover and to identify underlying causes. Spatial data will also be a critical component guiding the decision processes for restoration of habitat in the Great Plains. As such, the PRAIRIEMAP database will facilitate analyses of large-scale and range-wide factors that may be causing declines in grassland habitat and populations of species that depend on it for their survival. Therefore, development of a reliable spatial database carries multiple benefits for land and wildlife management. The project consists of 3 phases: (1) identify relevant spatial data, (2) assemble, document, and archive spatial data on a computer server, and (3) develop and maintain the web site (http://prairiemap.wr.usgs.gov) for query and transfer of GIS data to managers and researchers.

Comparative research on soil magnetic susceptibility and Chroma and grain of grassland soil and farmland soil in alpine region

NASA Astrophysics Data System (ADS)

Jie, Yuan; Guangchao, Cao; Chongyi, E.; Gang, Jiang; Youjing, Yuan; Cheng, Xiang

2017-03-01

This thesis aims at researching unchanged perennial farmland and grassland soil on the northern of Qinghai Lake basin and differences between soil magnetic susceptibility, chroma and soil particle size composition of grassland and farmland in lengthways profile(0-60cm). The result shows that the distinction of Xlf between grassland and farmland is smaller above 15cm, and farmland Xlf is finer than grassland below 15cm. The Xfd of grassland is finer than farmland above 30cm, which has a little difference below 30cm. Farmland chroma value is finer than the grassland generally. The lightness of grassland has increased trend and farmland has the decrease trend above 30cm, the lightness of grassland and farmland has no other changes below 30cm, the change of redness and yellowness in lengthways profile has a decrease trend from 0 to 60cm; the clay and silt content of grassland are finer than farmland except sand content; the sand maximum content of farmland in 0-10cm segment; 20 to 35 cm segment sand content decrease and began to increase from 35-60cm segment; the soil particle size composition has a big difference, in particular, when it is above 30cm, it has a little difference below 30cm.

7 CFR 51.897 - Wet.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Definitions § 51.897 Wet. Wet means that the grapes are wet from moisture from crushed, leaking, or decayed berries or from rain. Grapes which are moist from dew or other moisture condensation such as that...

7 CFR 51.897 - Wet.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Definitions § 51.897 Wet. Wet means that the grapes are wet from moisture from crushed, leaking, or decayed berries or from rain. Grapes which are moist from dew or other moisture condensation such as that...

Paludiculture on marginal lands - sustainable use of wet peatlands

NASA Astrophysics Data System (ADS)

Oehmke, Claudia; Dahms, Tobias; Wichmann, Sabine; Wichtmann, Wendelin

2017-04-01

Peatlands are marginal lands. If they are drained, they show a short initial productive period. Soil degradation due to peat oxidation leads to numerous problems which increasingly restrict agricultural use and cause significant environmental impacts such as greenhouse gas emissions and eutrophication and thereby produce high external costs. Worldwide greenhouse gas emissions from drained peatlands have a significant share ( 10%) in the emissions from agriculture, forestry and other land use (AFOLU) sectors (Smith et al. 2014). In Germany they contribute more than 35% to the total emissions from agriculture (agricultural sector and cropland and grassland management) (UBA 2016). Rewetting drained peatlands can significantly reduce environmental problems caused by peatland drainage. Continuation of agricultural use with adapted crops and machinery, so called paludiculture (Latin ‚palus' = swamp) stops further degradation, maintains the peat body, reduces climate change mitigation and produces renewable fuels and raw materials. Fen and bog soils are suitable for various different paludicultures. The biomass of Sphagnum (sphagnum farming) cultivated on cut-over bogs or degraded bog grasslands can be used as raw material for horticultural growing media. Flood-tolerant and productive plant species like Common Reed, Reed Canary Grass, Cattail, Black Alder and different Sedge species are suitable for paludiculture on fen soils. Biomass utilization ranges from traditional forms, like fodder production or the use of Common Reed as roof thatch, to new utilization options, that includes biomass use for heat generation, co-subtrates for biorefineries or construction and insulation products. The above-ground biomass of one hectare Common Reed (winter yield=8 t DM) equates to an energy content of 3,000 litre heating oil. A district heating plant (800 kW) in NE Germany demonstrates the feasibility of using biomass from wet fen meadows for local heat generation. Moreover, tests

Vegetation and soil condition changes on a subalpine grassland in eastern Oregon.

Treesearch

Gerald S. Strickler

1961-01-01

In the late 193O's, a subalpine grassland in the green fescue type in the Wallowa Mountains of northeastern Oregon was known to be in very poor condition. This grassland, located in the headwaters of the Imnaha River and locally known as Tenderfoot Basin, had been subjected to mismanaged sheep grazing for many years. Both quality and quantity of forage had...

Responses of soil fungal community to the sandy grassland restoration in Horqin Sandy Land, northern China.

PubMed

Wang, Shao-Kun; Zuo, Xiao-An; Zhao, Xue-Yong; Li, Yu-Qiang; Zhou, Xin; Lv, Peng; Luo, Yong-Qing; Yun, Jian-Ying

2016-01-01

Sandy grassland restoration is a vital process including re-structure of soils, restoration of vegetation, and soil functioning in arid and semi-arid regions. Soil fungal community is a complex and critical component of soil functioning and ecological balance due to its roles in organic matter decomposition and nutrient cycling following sandy grassland restoration. In this study, soil fungal community and its relationship with environmental factors were examined along a habitat gradient of sandy grassland restoration: mobile dunes (MD), semi-fixed dunes (SFD), fixed dunes (FD), and grassland (G). It was found that species abundance, richness, and diversity of fungal community increased along with the sandy grassland restoration. The sequences analysis suggested that most of the fungal species (68.4 %) belonged to the phylum of Ascomycota. The three predominant fungal species were Pleospora herbarum, Wickerhamomyces anomalus, and Deconica Montana, accounting for more than one fourth of all the 38 species. Geranomyces variabilis was the subdominant species in MD, Pseudogymnoascus destructans and Mortierella alpine were the subdominant species in SFD, and P. destructans and Fungi incertae sedis were the dominant species in FD and G. The result from redundancy analysis (RDA) and stepwise regression analysis indicated that the vegetation characteristics and soil properties explain a significant proportion of the variation in the fungal community, and aboveground biomass and C:N ratio are the key factors to determine soil fungal community composition during sandy grassland restoration. It was suggested that the restoration of sandy grassland combined with vegetation and soil properties improved the soil fungal diversity. Also, the dominant species was found to be alternative following the restoration of sandy grassland ecosystems.

Dairy farming on permanent grassland: can it keep up?

PubMed

Kellermann, M; Salhofer, K

2014-10-01

Based on an extensive data set for southern Germany, we compared the productive performance of dairy farms that operate solely on permanent grassland and dairy farms using fodder crops from arable land. We allowed for heterogeneous production technologies and identified more intensive and extensive production systems for both types of farms, whereby we based our notion of intensive versus extensive dairy production on differences in stocking density and milk yield per cow and year. To be able to compare the productivity levels and productivity developments of the various groups of farms, we developed a group- and chain-linked multilateral productivity index. We also analyzed how technical change, technical efficiency change, and a scale change effect contribute to productivity growth between the years 2000 and 2008. Our results revealed that permanent grassland farms can generally keep up with fodder-crop farms, even in an intensive production setting. However, extensively operating farms, especially those on permanent grassland, significantly lag behind in productivity and productivity change and run the risk of losing ground. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Eutrophication weakens stabilizing effects of diversity in natural grasslands.

PubMed

Hautier, Yann; Seabloom, Eric W; Borer, Elizabeth T; Adler, Peter B; Harpole, W Stanley; Hillebrand, Helmut; Lind, Eric M; MacDougall, Andrew S; Stevens, Carly J; Bakker, Jonathan D; Buckley, Yvonne M; Chu, Chengjin; Collins, Scott L; Daleo, Pedro; Damschen, Ellen I; Davies, Kendi F; Fay, Philip A; Firn, Jennifer; Gruner, Daniel S; Jin, Virginia L; Klein, Julia A; Knops, Johannes M H; La Pierre, Kimberly J; Li, Wei; McCulley, Rebecca L; Melbourne, Brett A; Moore, Joslin L; O'Halloran, Lydia R; Prober, Suzanne M; Risch, Anita C; Sankaran, Mahesh; Schuetz, Martin; Hector, Andy

2014-04-24

Studies of experimental grassland communities have demonstrated that plant diversity can stabilize productivity through species asynchrony, in which decreases in the biomass of some species are compensated for by increases in others. However, it remains unknown whether these findings are relevant to natural ecosystems, especially those for which species diversity is threatened by anthropogenic global change. Here we analyse diversity-stability relationships from 41 grasslands on five continents and examine how these relationships are affected by chronic fertilization, one of the strongest drivers of species loss globally. Unmanipulated communities with more species had greater species asynchrony, resulting in more stable biomass production, generalizing a result from biodiversity experiments to real-world grasslands. However, fertilization weakened the positive effect of diversity on stability. Contrary to expectations, this was not due to species loss after eutrophication but rather to an increase in the temporal variation of productivity in combination with a decrease in species asynchrony in diverse communities. Our results demonstrate separate and synergistic effects of diversity and eutrophication on stability, emphasizing the need to understand how drivers of global change interactively affect the reliable provisioning of ecosystem services in real-world systems.

Patch-burn grazing management, vegetation heterogeneity and avian responses in a semi-arid grassland

USDA-ARS?s Scientific Manuscript database

Anthropogenic changes to disturbance regimes in grasslands, and associated homogenization of vegetation structure, have been implicated as factors contributing to declines in populations of grassland birds in North America. We examined the influence of patch-burn grazing management, which employs sp...

Grassland ecosystem responses to climate change and human activities within the Three-River Headwaters region of China.

PubMed

Han, Ze; Song, Wei; Deng, Xiangzheng; Xu, Xinliang

2018-06-13

The Three-River Headwaters region (TRHR) of China is an important part of the Qinghai-Tibetan Plateau. Although the TRHR is rich in grassland resources, the ecosystem of this area is extremely fragile. Natural and artificial interference have been key to the development of grassland ecosystem spatiotemporal heterogeneity, although the intensity and mode of their influence on ecological processes varies depending on scale; analyses in this area are therefore also scale-dependent. We use multi-scale nested data to analyze the mechanisms underlying the influence of climate change and human activities on grassland net primary productivity (NPP) by applying a multi-level modeling approach. The results of this study show that: (1) The annual grassland NPP of the TRHR has risen in a wavelike pattern over time, increasing by 39.88% overall; (2) Differences of 54.9% and 41.1% in temporal grassland NPP can be attributed to variations between these watersheds as well as county characteristics, and; (3) Although the 'warm and moist' climate trend seen over the course of this study has proved beneficial in enhancing grassland NPP, the rate of increase has tended to be faster in relatively dry and warm regions. Economic development and population growth have both exerted negative impacts on grassland NPP.

Combining social policy and scientific knowledge with stakeholder participation can benefit on salted grassland production in Northeast China

NASA Astrophysics Data System (ADS)

Wang, Deli; Yang, Zhiming; Wang, Ling; Sun, Wei

2015-04-01

Soil salinization is a serious environmental problem across the Eurasian steppes, where millions people have been living for at least five thousand years and will still depend on it in the near future. During the last several decades, ecologists and grassland scientists have done much research on rational grassland utilization avoiding land degradation and reduction in ecological services. Meanwhile, the central and local governments took some attempts of agricultural policy and ecological subsidy to mitigate large scale land salinization in Northeast China. Fortunately, more and more farmers and stakeholders begin to adopt rational grassland management with the guidance of scientists and the help of local governments. However, up to date, there is still a gap between farmers, scientists and governments, which often negatively affect grassland production and remission of soil salinization in these areas. We conducted a case study on sustainable grassland production adapted to steppe salinization funded by EC project from 2011 to 2013. Our goal is trying to establish a mode of adaptive grassland management integrating previous scientific knowledge (grazing and seeding), current agricultural policies (ecological subsidy) and stakeholders' participation or performance. The study showed that: A. Despite of some grassland utilization techniques available for stakeholders (regulating stocking rate and seeding in pastures, or planting high quality forages), they tended to take the simplest action to enhance animal production and prevent grassland salinization; B. Compared to educating or training stakeholders, demonstration of grazing management is the most effective mean for knowledge dissemination or technology transfer; C. Ecological subsidy is absolutely welcome to the local people, and technology transfer became easier when combined with ecological subsidy; D. There was a contrasting effect in grassland production and land degradation mitigation for experimental farm

Combining Livestock Production Information in a Process-Based Vegetation Model to Reconstruct the History of Grassland Management

NASA Technical Reports Server (NTRS)

Chang, Jinfeng; Ciais, Philippe; Herrero, Mario; Havlik, Petr; Campioli, Matteo; Zhang, Xianzhou; Bai, Yongfei; Viovy, Nicolas; Joiner, Joanna; Wang, Xuhui;

Quantification of wet-work exposure in nurses using a newly developed wet-work exposure monitor.

PubMed

Visser, Maaike J; Behroozy, Ali; Verberk, Maarten M; Semple, Sean; Kezic, Sanja

2011-08-01

Occupational contact dermatitis (OCD) is an important work-related disease. A major cause of OCD is 'wet work': frequent contact of the skin with water, soap, detergents, or occlusive gloves. The German guidance TRGS 401 recommends that the duration of wet work (including use of occlusive gloves) should not exceed 2 h day(-1) and also the frequency of hand washing or hand disinfection should be taken into account. This highlights the need for a reliable method to assess duration and frequency of wet work. Recently, a wet-work sampler has been developed by the University of Aberdeen. The sampler uses the temperature difference (ΔT) generated by evaporative cooling between two sensors: one sensor on the skin and a second one placed 2 mm above the skin. We have evaluated the use of this sampler in a healthcare setting, using direct observation as reference. Twenty-six nurses wore the sampler on the volar side of the middle finger for ∼2 h during their regular daily tasks, while being observed by a researcher. Sampler results were evaluated using various threshold values for ΔT to identify wet events of the hands. The optimal ΔT to discern wet and dry skin differed considerably between individual nurses. Individual results yielded a median sensitivity of 78 and 62% and a median specificity of 79 and 68% for indicating wet skin and glove use, respectively. Overall, the sampler was moderately accurate for identifying wetness of the skin and less accurate for discerning glove use. In conclusion, agreement between observed wet work and device-reported wet events in healthcare settings was not high and further adaptations and developments may be required.

Topographic and Bioclimatic Determinants of the Occurrence of Forest and Grassland in Tropical Montane Forest-Grassland Mosaics of the Western Ghats, India

PubMed Central

Das, Arundhati; Nagendra, Harini; Anand, Madhur; Bunyan, Milind

2015-01-01

The objective of this analysis was to identify topographic and bioclimatic factors that predict occurrence of forest and grassland patches within tropical montane forest-grassland mosaics. We further investigated whether interactions between topography and bioclimate are important in determining vegetation pattern, and assessed the role of spatial scale in determining the relative importance of specific topographic features. Finally, we assessed the role of elevation in determining the relative importance of diverse explanatory factors. The study area consists of the central and southern regions of the Western Ghats of Southern India, a global biodiversity hotspot. Random forests were used to assess prediction accuracy and predictor importance. Conditional inference classification trees were used to interpret predictor effects and examine potential interactions between predictors. GLMs were used to confirm predictor importance and assess the strength of interaction terms. Overall, topographic and bioclimatic predictors classified vegetation pattern with approximately 70% accuracy. Prediction accuracy was higher for grassland than forest, and for mosaics at higher elevations. Elevation was the most important predictor, with mosaics above 2000m dominated largely by grassland. Relative topographic position measured at a local scale (within a 300m neighbourhood) was another important predictor of vegetation pattern. In high elevation mosaics, northness and concave land surface curvature were important predictors of forest occurrence. Important bioclimatic predictors were: dry quarter precipitation, annual temperature range and the interaction between the two. The results indicate complex interactions between topography and bioclimate and among topographic variables. Elevation and topography have a strong influence on vegetation pattern in these mosaics. There were marked regional differences in the roles of various topographic and bioclimatic predictors across the

Topographic and Bioclimatic Determinants of the Occurrence of Forest and Grassland in Tropical Montane Forest-Grassland Mosaics of the Western Ghats, India.

PubMed

Das, Arundhati; Nagendra, Harini; Anand, Madhur; Bunyan, Milind

2015-01-01

The objective of this analysis was to identify topographic and bioclimatic factors that predict occurrence of forest and grassland patches within tropical montane forest-grassland mosaics. We further investigated whether interactions between topography and bioclimate are important in determining vegetation pattern, and assessed the role of spatial scale in determining the relative importance of specific topographic features. Finally, we assessed the role of elevation in determining the relative importance of diverse explanatory factors. The study area consists of the central and southern regions of the Western Ghats of Southern India, a global biodiversity hotspot. Random forests were used to assess prediction accuracy and predictor importance. Conditional inference classification trees were used to interpret predictor effects and examine potential interactions between predictors. GLMs were used to confirm predictor importance and assess the strength of interaction terms. Overall, topographic and bioclimatic predictors classified vegetation pattern with approximately 70% accuracy. Prediction accuracy was higher for grassland than forest, and for mosaics at higher elevations. Elevation was the most important predictor, with mosaics above 2000 m dominated largely by grassland. Relative topographic position measured at a local scale (within a 300 m neighbourhood) was another important predictor of vegetation pattern. In high elevation mosaics, northness and concave land surface curvature were important predictors of forest occurrence. Important bioclimatic predictors were: dry quarter precipitation, annual temperature range and the interaction between the two. The results indicate complex interactions between topography and bioclimate and among topographic variables. Elevation and topography have a strong influence on vegetation pattern in these mosaics. There were marked regional differences in the roles of various topographic and bioclimatic predictors across the

Changes in grassland management and plant diversity in a marginal region of the Carpathian Mts. in 1999-2015.

PubMed

Halada, Ľuboš; David, Stanislav; Hreško, Juraj; Klimantová, Alexandra; Bača, Andrej; Rusňák, Tomáš; Buraľ, Miroslav; Vadel, Ľuboš

2017-12-31

The political change from socialism to democracy in countries of Central and Eastern Europe at the end of the 20th century induced broad changes in agriculture mostly due to land ownership changes and strong reduction of subsidies to agriculture. This resulted in agricultural decline, including grassland abandonment, which influenced grassland biodiversity and conservation. Between 1999 and 2015 we studied the grasslands in the area depopulated in the early 1980's in the Poloniny National Park (NE Slovakia, Carpathian Mts.). The aim of the study was to examine influence of environmental factors and grassland management driven by the Common Agricultural Policy (CAP) to plant community structure and taxonomical diversity. We identified altitude and soil properties as the main environmental factors: altitude determines climate gradient and probably also management intensity gradient and soil properties express soil fertility via A-horizon depth. We identified remarkable increase of proportion of managed grasslands from only 8% in 1999 to 40% in 2012-2015; other 7% of sampled grasslands were recently restored and prepared for future management. The average species richness in grasslands managed in 2012-2015 increased from 47.5 species per record in 1999 to 54.2 species in 2012-2015, the increase was found statistically significant. In 2012-2015, we observed statistically significant difference in the average species richness between managed (54.2) and abandoned grasslands (46.3). The agricultural subsidies of the CAP drive the grassland management in the study area. Therefore, we conclude that CAP enabled grassland biodiversity maintenance in significant part of the Poloniny National Park following start of its application in 2004 and above provided figures can be considered as indicators of the CAP effectiveness in our study area. However, the conservation of mountain meadows remains a challenge because of their poor accessibility. Copyright © 2017 Elsevier B.V. All

Monitoring aeolian desertification process in Hulunbir grassland during 1975-2006, Northern China.

PubMed

Guo, Jian; Wang, Tao; Xue, Xian; Ma, Shaoxiu; Peng, Fei

2010-07-01

The Hulunbir grassland experienced aeolian desertification expansion during 1975-2000, but local rehabilitation during 2000-2006. Northern China suffered severe aeolian desertification during the past 50 years. Hulunbir grassland, the best stockbreeding base in Northern China, was also affected by aeolian desertification. To evaluate the evolution and status of aeolian desertification, as well as its causes, satellite images (acquired in 1975, 1984, 2000, and 2006) and meteorological and socioeconomic data were interpreted and analyzed. The results show there was 2,345.7, 2,899.8, 4,053.9, and 3,859.6 km(2) of aeolian desertified land in 1975, 1984, 2000, and 2006, respectively. The spatial pattern dynamic had three stages: stability during 1975-1984, fast expansion during 1984-2000, and spatial transfer during 2000-2006. The dynamic degree of aeolian desertification is negatively related to its severity. Comprehensive analysis shows that the human factor is the primary cause of aeolian desertification in Hulunbir grassland. Although aeolian desertified land got partly rehabilitated, constant increase of extremely severe aeolian desertified land implied that current measures were not effective enough on aeolian desertification control. Alleviation of grassland pressure may be an effective method.

Should heterogeneity be the basis for conservation? Grassland bird response to fire and grazing

USGS Publications Warehouse

Fuhlendorf, S.D.; Harrell, W.C.; Engle, David M.; Hamilton, R.G.; Davis, C.A.; Leslie, David M.

2006-01-01

In tallgrass prairie, disturbances such as grazing and fire can generate patchiness across the landscape, contributing to a shifting mosaic that presumably enhances biodiversity. Grassland birds evolved within the context of this shifting mosaic, with some species restricted to one or two patch types created under spatially and temporally distinct disturbance regimes. Thus, management-driven reductions in heterogeneity may be partly responsible for declines in numbers of grassland birds. We experimentally altered spatial heterogeneity of vegetation structure within a tallgrass prairie by varying the spatial and temporal extent of fire and by allowing grazing animals to move freely among burned and unburned patches (patch treatment). We contrasted this disturbance regime with traditional agricultural management of the region that promotes homogeneity (traditional treatment). We monitored grassland bird abundance during the breeding seasons of 2001-2003 to determine the influence of altered spatial heterogeneity on the grassland bird community. Focal disturbances of patch burning and grazing that shifted through the landscape over several years resulted in a more heterogeneous pattern of vegetation than uniform application of fire and grazing. Greater spatial heterogeneity in vegetation provided greater variability in the grassland bird community. Some bird species occurred in greatest abundance within focally disturbed patches, while others occurred in relatively undisturbed patches in our patch treatment. Henslow's Sparrow, a declining species, occurred only within the patch treatment. Upland Sandpiper and some other species were more abundant on recently disturbed patches within the same treatment. The patch burn treatment created the entire gradient of vegetation structure required to maintain a suite of grassland bird species that differ in habitat preferences. Our study demonstrated that increasing spatial and temporal heterogeneity of disturbance in grasslands

Molt and aging criteria for four North American grassland passerines

USGS Publications Warehouse

Pyle, Peter; Jones, Stephanie L.; Ruth, Janet M.

2008-01-01

Prairie and grassland habitats in central and western North America have declined substantially since settlement by Europeans (Knopf 1994) and many of the birds and other organisms that inhabit North American grasslands have experienced steep declines (Peterjohn and Sauer 1999; Johnson and Igl 1997; Sauer, Hines, and Fallon 2007). The species addressed here, Sprague’s Pipit (Anthus spragueii), Grasshopper (Ammodramus savannarum) and Baird’s (A. bairdii) sparrows, and Chestnut-collared Longspurs (Calcarius ornatus), are grassland birds that are of special conservation concern throughout their ranges due to declining populations and the loss of the specific grassland habitats required on both their breeding and wintering ranges (Knopf 1994, Davis and Sealy 1998, Davis 2003, Davis 2004, Jones and Dieni 2007). Population-trend data on grassland birds, while clearly showing declines, provides no information on the causes of population declines. Without demographic information (i.e., productivity and survivorship), there are no means to determine when in their life cycle the problems that are creating these declines are occurring, or to determine to what extent population trends are driven by factors that affect birth rates, death rates, or both (DeSante 1995). For migratory birds, population declines may be driven by factors on breeding grounds, during migration, and/or on wintering grounds. Lack of data on productivity and survivorship thus impedes the formulation of effective management and conservation strategies to reverse population declines (DeSante 1992). Furthermore, if deficiencies in survivorship are revealed, management strategies may need to address habitats on both breeding and non-breeding grounds, as well as along migratory pathways. One technique that helps inform management strategies is the biochemical analysis of isotopes and genetic markers, from the sampling of individual feathers from live birds (Smith et al. 2003, Pérez and Hobson 2006

Changes in Temperature Sensitivity and Activation Energy of Soil Organic Matter Decomposition in Different Qinghai-Tibet Plateau Grasslands.

PubMed

Li, Jie; He, Nianpeng; Wei, Xuehong; Gao, Yang; Zuo, Yao

2015-01-01

Qinghai-Tibet Plateau grasslands are unique geographical regions and store substantial soil organic matter (SOM) in the soil surface, which make them very sensitive to global climate change. Here, we focused on three main grassland types (alpine meadow, steppe, and desert) and conducted a soil incubation experiment at five different temperatures (5, 10, 15, 20, and 25°C) to investigate SOM decomposition rates (R), temperature sensitivity (Q10), and activation energy (Ea). The results showed that grassland type and incubation temperature had significant impact on R (P < 0.001), and the values of R were exponential correlated with incubation temperature in three alpine grasslands. At the same temperature, R was in the following order: alpine meadow > alpinesteppe > alpine desert. The Q10 values differed significantly among different grasslands, and the overall trends were as follows: alpine meadow (1.56 ± 0.09) < alpine steppe (1.88 ± 0.23) < alpine desert (2.39 ± 0.32). Moreover, the Ea values differed significantly across different grassland types (P < 0.001) and increased with increasing incubation time. The exponential negative correlations between Ea and R at 20°C across all grassland types (all Ps < 0.001) indicated that the substrate-quality temperature hypothesis is applicable to the alpine grasslands. Our findings provide new insights for understanding the responses of SOM decomposition and storage to warming scenarios in this Plateau.

Exotic-Dominated Grasslands Show Signs of Recovery with Cattle Grazing and Fire.

PubMed

Delaney, John T; Moranz, Raymond A; Debinski, Diane M; Engle, David M; Miller, James R

2016-01-01

In grasslands, overgrazing by domestic livestock, fertilization, and introduction of exotic forage species leads to plant communities consisting of a mixture of native and exotic species. These degraded grasslands present a problem for land managers, farmers, and restoration ecologists concerned with improving biodiversity while continuing to use the land for livestock production. Here we assessed the response of butterfly and plant community composition to the use of fire and moderate grazing by domestic cattle on degraded grasslands dominated by exotic plants. We evaluated change by comparing experimental pastures to two reference sites that were grasslands dominated by native plants. We used two burning and grazing treatments: 1) patch-burn graze, a heterogeneously managed treatment, where one third of the pasture is burned each year and cattle have free access to the entire pasture, and 2) graze-and-burn, a homogenously managed treatment, where the entire pasture is grazed each year and burned in its entirety every three years. We tested for change in the butterfly and plant community composition over seven years using Bray-Curtis dissimilarity measures. Over the course of seven years, degraded pastures in both treatments became more similar to reference sites with respect to the butterfly and plant communities. Only two butterfly species and two plant functional guilds exhibited significant linear trends over time, with varying responses. Compositional changes in both the butterfly and plant communities indicate that the use of moderate grazing and fire may shift butterfly and plant communities of exotic-dominated grasslands to be more similar to reference tallgrass prairies over time.

Grassland bird use of Conservation Reserve Program fields in the Great Plains

USGS Publications Warehouse

Johnson, Douglas H.; Haufler, Jonathan B.

2005-01-01

An enormous area in the Great Plains is currently enrolled in the Conservation Reserve Program (CRP): 19.5 million acres (nearly 8 million ha) in Montana, North Dakota, South Dakota, Wyoming, Nebraska, Colorado, Kansas, Oklahoma, and Texas. This change in land use from cropland to grassland since 1985 has markedly influenced grassland bird populations. Many, but certainly not all, grassland species do well in CRP fields. The responses by birds to the program differ not only by species but also by region, year, the vegetation composition in a field, and whether or not a field has been hayed or grazed. The large scale and extent of the program has allowed researchers to address important conservation questions, such as the effect of the size of habitat patch and the influence of landscape features on bird use. However, most studies on nongame bird use of CRP in or near the Great Plains have been short-lived; 83% lasted only 1-3 years. Further, attention to the topic seems to have waned in recent years; the number of active studies peaked in the early 1990s and dramatically declined after 1995. Because breeding-bird use of CRP fields varies dramatically in response both to vegetational succession and to climatic variation, long-term studies are important. What was learned about CRP in its early stages may no longer be applicable. Finally, although the CRP provisions of the Farm Bill have been beneficial to many grassland birds, it is critical that gains in grassland habitat produced by the program not be off set by losses of native prairie.

Using simple environmental variables to estimate below-ground productivity in grasslands

USGS Publications Warehouse

Gill, R.A.; Kelly, R.H.; Parton, W.J.; Day, K.A.; Jackson, R.B.; Morgan, J.A.; Scurlock, J.M.O.; Tieszen, L.L.; Castle, J.V.; Ojima, D.S.; Zhang, X.S.

2002-01-01

In many temperate and annual grasslands, above-ground net primary productivity (NPP) can be estimated by measuring peak above-ground biomass. Estimates of below-ground net primary productivity and, consequently, total net primary productivity, are more difficult. We addressed one of the three main objectives of the Global Primary Productivity Data Initiative for grassland systems to develop simple models or algorithms to estimate missing components of total system NPP. Any estimate of below-ground NPP (BNPP) requires an accounting of total root biomass, the percentage of living biomass and annual turnover of live roots. We derived a relationship using above-ground peak biomass and mean annual temperature as predictors of below-ground biomass (r2 = 0.54; P = 0.01). The percentage of live material was 0.6, based on published values. We used three different functions to describe root turnover: constant, a direct function of above-ground biomass, or as a positive exponential relationship with mean annual temperature. We tested the various models against a large database of global grassland NPP and the constant turnover and direct function models were approximately equally descriptive (r2 = 0.31 and 0.37), while the exponential function had a stronger correlation with the measured values (r2 = 0.40) and had a better fit than the other two models at the productive end of the BNPP gradient. When applied to extensive data we assembled from two grassland sites with reliable estimates of total NPP, the direct function was most effective, especially at lower productivity sites. We provide some caveats for its use in systems that lie at the extremes of the grassland gradient and stress that there are large uncertainties associated with measured and modelled estimates of BNPP.

[Effects of desertification on C and N storages in grassland ecosystem on Horqin sandy land].

PubMed

Zhao, Ha-lin; Li, Yu-qiang; Zhou, Rui-lian

2007-11-01

Sandy grassland is widespread in northern China, where desertification is very common because of overgrazing and estrepement. However, little is known about the effects of desertification on grassland C and N storages in this region. A field survey was conducted on Horqin sandy grassland, and desertification gradients were established to evaluate the effects of desertification on C and N storages in soil, plant, and litter. The results showed that desertification had deep effects on the contents and storages of grassland C and N. The C and N contents and storages in the grassland decreased significantly with increasing desertification degree. Comparing with those in un-desertified grassland, the C and N contents in lightly, moderately, heavily, and severely desertified grasslands decreased by 56.06% and 48.72%, 78.43% and 74.36%, 88.95% and 84.62%, and 91.64% and 84.62% in 0-100 cm soil layer, and by 8.61% and 6.43%, 0.05% and 25.71%, 2.58% and 27.14%, and 8. 61% and 27. 86% in plant components, respectively. Relevantly, the C and N storages decreased by 50.95% and 43.38%, 75.19% and 71.04%, 86.76% and 81.48%, and 91.17% and 83.17% in plant underground components in 0-100 cm soil layer, and by 25.08% and 27.62%, 30.90% and 46.55%, 73.84% and 80.62%, and 90.89% and 87.31% in plant aboveground components, respectively. In 2000, the total area of desertified grassland in Horqin sandy land was 30152. 7 km2, and the C and N loss via desertification reached up to 107.53 and 9.97 Mt, respectively. Correlation analysis indicated that the decrease of soil C and N contents was mainly come from the decreased soil fine particles caused by wind erosion in the process of desertification, and the degradation of soil texture- and nutrient status led finally to the rapid decrease of C and N storages in plant biomass and litter.

A collaborative characterization of North American grasslands and rangelands: climate, ecohydrology and carbon sink-source dynamics

NASA Astrophysics Data System (ADS)

Petrie, M. D.; Brunsell, N. A.; Vargas, R.; Collins, S. L.

2013-12-01

Grassland and rangeland ecoregions extend across the North American continent and exhibit diversity in climate, ecosystem services, and biophysical processes. In many grasslands and rangelands, the potential for reductions in ecosystem services and for large-scale ecosystem state change may increase under future climate scenarios. Climate change projections for North America vary, however, and the way changing climate will influence specific ecoregions is largely unknown. To better understand the regional effects of climate change on grasslands and rangelands, it is important to better understand the biophysical characteristics of these systems locally, and to identify the sensitivity of these characteristics to observed climate variation. In our study, we propose to use eddy covariance, soil moisture and precipitation data to identify how the grasslands and rangelands of North America differ in their responses to climate variability through time, with specific focus on the active growing season. Our primary goal is to determine the sensitivity of ecosystem Net Primary Productivity [NPP] to variation in temperature and precipitation patterns, and classify North American grasslands and rangelands by these sensitivities in addition to more standard climate and productivity variables. Our preliminary analyses in mesic, semiarid and arid grasslands in Kansas, Colorado and New Mexico show significant (P < 0.05) differences in climate, carbon sink strength and growing season length, and suggest that patterns of seasonal productivity and precipitation sensitivity may elucidate important grassland and rangeland responses to changing climate. Using change in Gross Primary Productivity (GPP) as an indicator of the onset of photosynthesis in spring and of senescense in the fall, grassland and rangeland ecosystems in Kansas (top and bottom left panels) and New Mexico (bottom right panel) display differing patterns of activity throughout the year.

Evidence of Physiological Decoupling from Grassland Ecosystem Drivers by an Encroaching Woody Shrub

PubMed Central

Nippert, Jesse B.; Ocheltree, Troy W.; Orozco, Graciela L.; Ratajczak, Zak; Ling, Bohua; Skibbe, Adam M.

2013-01-01

Shrub encroachment of grasslands is a transformative ecological process by which native woody species increase in cover and frequency and replace the herbaceous community. Mechanisms of encroachment are typically assessed using temporal data or experimental manipulations, with few large spatial assessments of shrub physiology. In a mesic grassland in North America, we measured inter- and intra-annual variability in leaf δ13C in Cornus drummondii across a grassland landscape with varying fire frequency, presence of large grazers and topographic variability. This assessment of changes in individual shrub physiology is the largest spatial and temporal assessment recorded to date. Despite a doubling of annual rainfall (in 2008 versus 2011), leaf δ13C was statistically similar among and within years from 2008-11 (range of −28 to −27‰). A topography*grazing interaction was present, with higher leaf δ13C in locations that typically have more bare soil and higher sensible heat in the growing season (upland topographic positions and grazed grasslands). Leaf δ13C from slopes varied among grazing contrasts, with upland and slope leaf δ13C more similar in ungrazed locations, while slopes and lowlands were more similar in grazed locations. In 2011, canopy greenness (normalized difference vegetation index – NDVI) was assessed at the centroid of individual shrubs using high-resolution hyperspectral imagery. Canopy greenness was highest mid-summer, likely reflecting temporal periods when C assimilation rates were highest. Similar to patterns seen in leaf δ13C, NDVI was highest in locations that typically experience lowest sensible heat (lowlands and ungrazed). The ability of Cornus drummondii to decouple leaf physiological responses from climate variability and fire frequency is a likely contributor to the increase in cover and frequency of this shrub species in mesic grassland and may be generalizable to other grasslands undergoing woody encroachment. PMID:24339950

The effects of management on ammonia fluxes over a cut grassland as measured by use of dynamic chambers

NASA Astrophysics Data System (ADS)

David, M.; Roche, R.; Mattsson, M.; Sutton, M. A.; Dämmgen, U.; Schjoerring, J. K.; Cellier, P.

2009-01-01

Grassland management may lead to strong modification of the canopy structure and hence fluxes of carbon and nitrogen in the soil-plant-atmosphere system. Mowing or grazing removes green leaves, which are often a sink for ammonia. Consequently, the ratio between actively growing leaves and senescing/dead parts of the plants is strongly changed in favour of the latter, which may constitute a large source of ammonia. Moreover, fertilisers are a known source of ammonia through direct volatilisation. The effects of grassland management, e.g. growing, cutting and fertilisation, on ammonia emission were investigated using a dynamic chamber. This technique made it possible to monitor ammonia emissions in the field at the plant level. With ammonia-free air at the inlet, the ammonia emissions from mature sward did not exceed 4 ng NH3 m-2 s-1. They were approximately 20 times larger above a sward re-growing after cutting and 200 times larger after fertilisation, where 0.5-1.0% of the applied inorganic nitrogen fertiliser was lost by volatilisation. Cutting implied three main changes in ammonia sources and sinks within the canopy: (i) physiological changes with nitrogen remobilisation to the growing leaves and increase in senescence, (ii) changes in compartment proportions with only 5% of green leaves remaining after cutting as opposed to equal proportions of dead leaves as green leaves before cutting, (iii) microclimate changes within the canopy especially for litter with higher turbulence, temperature, and alternation of dry (day) and wet (night) conditions after cutting. These changes promoted ammonia volatilisation from the litter, which could account for the increased ammonia loss following cutting. Another potential source was the wounded surfaces of the stubble which may have emitted ammonia during bleeding and evaporation of sap containing significant levels of ammonium. These results showed that the contribution of litter and drying cut sward on the ammonia balance of

77 FR 75119 - Dakota Prairie Grasslands, North Dakota; Oil and Gas Development Supplemental Environmental...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-19

... DEPARTMENT OF AGRICULTURE Forest Service Dakota Prairie Grasslands, North Dakota; Oil and Gas... Prairie Grasslands Record of Decision for Oil and Gas Leasing on the Little Missouri and Cedar River... Management Plans Revision FEIS which included a Reasonably Foreseeable Development Scenario (RFDS) for Oil...

Grassland vegetation and bird communities in the southern Great Plains of North America

USGS Publications Warehouse

Chapman, R.N.; Engle, David M.; Masters, R.E.; Leslie, David M.

2004-01-01

Structure and composition of vegetation and abundance of breeding birds in grasslands seeded to Old World bluestem (Bothriochloa ischmaeum) were compared to native mixed prairie in the southern Great Plains of North America. Abundance of birds was determined using fixed-radius point counts. Detrended correspondence analysis was used to compare plant community composition and canonical correspondence analysis was used to examine the relationships between plant species composition and vegetation structure with the bird community. Plant species composition differed distinctly between seeded grassland and native mixed prairie, but the differences were not reflected in habitat structure, bird community composition, or abundance of bird species. Seeded grassland was inferior to native mixed prairie in terms of diversity of plant species, but that difference did not translate into meaningful differences in structure that drove habitat selection by breeding birds. Conservation programs that promote establishment of seeded grassland and do not allow for suitable disturbance regimes will selectively benefit a narrow suite of birds regardless of plant species composition. ?? 2004 Elsevier B.V. All rights reserved.

Multiscale Trend Analysis for Pampa Grasslands Using Ground Data and Vegetation Sensor Imagery

PubMed Central

Scottá, Fernando C.; da Fonseca, Eliana L.

2015-01-01

This study aimed to evaluate changes in the aboveground net primary productivity (ANPP) of grasslands in the Pampa biome by using experimental plots and changes in the spectral responses of similar vegetation communities obtained by remote sensing and to compare both datasets with meteorological variations to validate the transition scales of the datasets. Two different geographic scales were considered in this study. At the local scale, an analysis of the climate and its direct influences on grassland ANPP was performed using data from a long-term experiment. At the regional scale, the influences of climate on the grassland reflectance patterns were determined using vegetation sensor imagery data. Overall, the monthly variations of vegetation canopy growth analysed using environmental changes (air temperature, total rainfall and total evapotranspiration) were similar. The results from the ANPP data and the NDVI data showed the that variations in grassland growth were similar and independent of the analysis scale, which indicated that local data and the relationships of local data with climate can be considered at the regional scale in the Pampa biome by using remote sensing. PMID:26197320

Air quality and human health impacts of grasslands and shrublands in the United States

NASA Astrophysics Data System (ADS)

Gopalakrishnan, Varsha; Hirabayashi, Satoshi; Ziv, Guy; Bakshi, Bhavik R.

2018-06-01

Vegetation including canopy, grasslands, and shrublands can directly sequester pollutants onto the plant surface, resulting in an improvement in air quality. Until now, several studies have estimated the pollution removal capacity of canopy cover at the level of a county, but no such work exists for grasslands and shrublands. This work quantifies the air pollution removal capacity of grasslands and shrublands at the county-level in the United States and estimates the human health benefits associated with pollution removal using the i-Tree Eco model. Sequestration of pollutants is estimated based on the Leaf Area Index (LAI) obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) derived dataset estimates of LAI and the percentage land cover obtained from the National Land Cover Database (NLCD) for the year 2010. Calculation of pollution removal capacity using local environmental data indicates that grasslands and shrublands remove a total of 6.42 million tonnes of air pollutants in the United States and the associated monetary benefits total 268 million. Human health impacts and associated monetary value due to pollution removal was observed to be significantly high in urban areas indicating that grasslands and shrublands are equally critical as canopy in improving air quality and human health in urban regions.

Assessment of Grassland Health Based on Spatial Information Technology in Changji Autonomous Prefecture, Xinjiang

NASA Astrophysics Data System (ADS)

Du, M. J.; Zheng, J. H.; Mu, C.

2018-04-01

Based on the "pressure-state-response" (PSR) model, comprehensively applied GIS and RS techniques, 20 evaluation indicators were selected based on pressure, state and response, the entropy weight method was used to determine the weight of each index and build a grassland health evaluation system in Changji Prefecture, Xinjiang. Based on this, evaluation and dynamic analysis of grassland health in Changji Prefecture from 2000 to 2016, using GIS/RS technology, the trend of grassland health status in Changji is analyzed and studied. The results show that: 1) Grassland with low health leveld, lower health level, sub-health level, health level and high health level accounts for 1.46 %,27.67 %,38.35 %,29.21 % and 3.31 % of the total area of Changji. Qitai County, Hutubi County, and Manas County are lower health levels, Jimsar County, Changji City, and Mulei County are at a relatively high level, and Fukang City has a healthy level of health. 2) The level of grassland health in Changji County decreased slightly during the 17 years, accounting for 38.42 % of the total area. The area of 23,87 % showed a stable trend, and the improved area accounted for 37.31 % of the vertical surface area.

Faunal isotope records reveal trophic and nutrient dynamics in twentieth century Yellowstone grasslands.

PubMed

Fox-Dobbs, Kena; Nelson, Abigail A; Koch, Paul L; Leonard, Jennifer A

2012-10-23

Population sizes and movement patterns of ungulate grazers and their predators have fluctuated dramatically over the past few centuries, largely owing to overharvesting, land-use change and historic management. We used δ(13)C and δ(15)N values measured from bone collagen of historic and recent gray wolves and their potential primary prey from Yellowstone National Park to gain insight into the trophic dynamics and nutrient conditions of historic and modern grasslands. The diet of reintroduced wolves closely parallels that of the historic population. We suggest that a significant shift in faunal δ(15)N values over the past century reflects impacts of anthropogenic environmental changes on grassland ecosystems, including grazer-mediated shifts in grassland nitrogen cycle processes.

WET AND DRY SCRUBBERS FOR EMISSION CONTROL

EPA Science Inventory

Generally speaking, absorption equipment includes two major categories: Wet adsorption scrubbers (or wet scrubbers); Dry absorption scrubbers (or dry scrubbers).
Wet scrubbers: As the name implies, wet scrubbers (also known as wet collectors) are devices which use a liquid fo...

Spatiotemporal dynamics of grassland aboveground biomass on the Qinghai-Tibet Plateau based on validated MODIS NDVI.

PubMed

Liu, Shiliang; Cheng, Fangyan; Dong, Shikui; Zhao, Haidi; Hou, Xiaoyun; Wu, Xue

2017-06-23

Spatiotemporal dynamics of aboveground biomass (AGB) is a fundamental problem for grassland environmental management on the Qinghai-Tibet Plateau (QTP). Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) data can feasibly be used to estimate AGB at large scales, and their precise validation is necessary to utilize them effectively. In our study, the clip-harvest method was used at 64 plots in QTP grasslands to obtain actual AGB values, and a handheld hyperspectral spectrometer was used to calculate field-measured NDVI to validate MODIS NDVI. Based on the models between NDVI and AGB, AGB dynamics trends during 2000-2012 were analyzed. The results showed that the AGB in QTP grasslands increased during the study period, with 70% of the grasslands undergoing increases mainly in the Qinghai Province. Also, the meadow showed a larger increasing trend than steppe. Future AGB dynamic trends were also investigated using a combined analysis of the slope values and the Hurst exponent. The results showed high sustainability of AGB dynamics trends after the study period. Predictions indicate 60% of the steppe and meadow grasslands would continue to increase in AGB, while 25% of the grasslands would remain in degradation, with most of them distributing in Tibet.

Temporal and spatial changes of land use and landscape in a coal mining area in Xilingol grassland

NASA Astrophysics Data System (ADS)

Guan, Chunzhu; Zhang, Baolin; Li, Jiannan; Zhao, Junling

2017-01-01

Coal mining, particularly surface mining, inevitably disturbs land. According to Landsat images acquired over Xilingol grassland in 2005, 2009 and 2015, land uses were divided into seven classes, i. e., open stope, stripping area, waste-dump area, mine industrial area, farmland, urban area and the original landscape (grassland), using supervised classification and human-computer interactive interpretation. The overall classification accuracies were 97.72 %, 98.43 % and 96.73 %, respectively; the Kappa coefficients were 0.95, 0.97 and 0.95, respectively. Analysis on LUCC (Land Use and Cover Change) showed that surface coal mining disturbed grassland ecosystem: grassland decreased by 8661.15 hm2 in 2005-2015. The area and proportion of mining operation areas (open stope, stripping area, waste-dump area, mine industrial field) increased, but those of grassland decreased continuously. Transfer matrix of land use changes showed that waste-dump had the largest impacts in mining disturbance, and that effective reclamation of waste-dump areas would mitigate eco-environment destruction, as would be of great significance to protect fragile grassland eco-system. Six landscape index showed that landscape fragmentation increased, and the influences of human activity on landscape was mainly reflected in the expansion of mining area and urban area. Remote sensing monitoring of coal surface mining in grassland would accurately demonstrate the dynamics and trend of LUCC, providing scientific supports for ecological reconstruction in surface mining area.

Effects of woody species encroachment and fire on the soil seed bank of Transylvanian dry basiphilous grasslands - perspectives for their restoration

NASA Astrophysics Data System (ADS)

Görzen, Eugen; Borisova, Karina; Ruprecht, Eszter; Fenesi, Annamária; Lukács, Katalin; Bertram, Anna; Donath, Tobias W.

2017-04-01

Background: Semi-natural dry basiphilous grasslands in the Transylvanian Basin of Romania are among the most species-rich grasslands worldwide and protected according to the Habitats Directive of the European Union. They evolved in response to human impact over millennia (grazing and cutting) and to prevailing environmental conditions. Currently, they are under threat due to land use changes: abandonment and intensification of sheep farming. As soon as the management of the grassland ceases, litter accumulation begins, followed by the invasion and establishment of native and non-native shrubs and trees. In order to halt secondary succession, the deliberate burning of shrub-encroached grasslands has progressively been applied. Questions: The establishment of woody species in grassland as well as the application of fire management to prevent the further spread of shrubs has recently increased in Transylvania. Still, little is known about the underlying mechanisms and the specific effects of encroachment by native and non-native woody species as well as fire on plant species and functional diversity of these grasslands. Likewise, there is a lack in efficient measures in Transylvania to restore grassland already invaded by woody plants. Consequently, we ask: (i) In which ways does woody species encroachment affect plant species and functional diversity, (ii) do native and non-native woody species differ with respect to their impact on grassland species composition and structure, (iii) is controlled burning a useful management tool to control shrub encroachment and to preserve biodiversity of these grasslands, and (iv) can soil seed banks contribute to the restoration of dry basiphilous grasslands in Transylvania? Methods: We collected data on plant species richness, composition and structure, topsoil conditions and soil seed bank composition in 16 shrub encroached grassland sites in the Transylvanian Basin, Romania, from June to August 2016. We compared uninvaded

Predicting parameters of degradation succession processes of Tibetan Kobresia grasslands

NASA Astrophysics Data System (ADS)

Lin, L.; Li, Y. K.; Xu, X. L.; Zhang, F. W.; Du, Y. G.; Liu, S. L.; Guo, X. W.; Cao, G. M.

2015-08-01

In the past two decades, increasing human activity (i.e., overgrazing) in the Tibetan Plateau has strongly influenced plant succession processes, resulting in the degradation of alpine grasslands. Therefore, it is necessary to diagnose the degree of degradation to enable implementation of appropriate management for sustainable exploitation and protection of alpine grasslands. Here, we investigated environmental factors and plant functional group quantity factors (PFGs) during the alpine grassland succession processes. Principal component analysis (PCA) was used to identify the parameters indicative of degradation. We divided the entire degradation process into six stages. PFG types shifted from rhizome bunch grasses to rhizome plexus and dense plexus grasses during the degradation process. Leguminosae and Gramineae plants were replaced by Sedges during the advanced stages of degradation. The PFGs were classified into two reaction groups: the grazing-sensitive group, containing Kobresia humilis Mey, and Gramineae and Leguminosae plants, and the grazing-insensitive group, containing Kobresia pygmaea Clarke. The first group was correlated with live root biomass in the surface soil (0-10 cm), whereas the second group was strongly correlated with mattic epipedon thickness and K. pygmaea characteristics. The degree of degradation of alpine meadows may be delineated by development of mattic epipedon and PFG composition. Thus, meadows could be easily graded and their use adjusted based on our scaling system, which would help prevent irreversible degradation of important grasslands. Because relatively few environmental factors are investigated, this approach can save time and labor to formulate a conservation management plan for degraded alpine meadows.

Predicting parameters of degradation succession processes of Tibetan Kobresia grasslands

NASA Astrophysics Data System (ADS)

Lin, L.; Li, Y. K.; Xu, X. L.; Zhang, F. W.; Du, Y. G.; Liu, S. L.; Guo, X. W.; Cao, G. M.

2015-11-01

In the past two decades, increasing human activity (i.e., overgrazing) in the Tibetan Plateau has strongly influenced plant succession processes, resulting in the degradation of alpine grasslands. Therefore, it is necessary to diagnose the degree of degradation to enable implementation of appropriate management for sustainable exploitation and protection of alpine grasslands. Here, we investigated environmental factors and plant functional group (PFG) quantity factors during the alpine grassland succession processes. Principal component analysis (PCA) was used to identify the parameters indicative of degradation. We divided the entire degradation process into six stages. PFG types shifted from rhizome bunchgrasses to rhizome plexus and dense-plexus grasses during the degradation process. Leguminosae and Gramineae plants were replaced by sedges during the advanced stages of degradation. The PFGs were classified into two reaction groups: the grazing-sensitive group, containing Kobresia humilis Mey, and Gramineae and Leguminosae plants, and the grazing-insensitive group, containing Kobresia pygmaea Clarke. The first group was correlated with live root biomass in the surface soil (0-10 cm), whereas the second group was strongly correlated with mattic epipedon thickness and K. pygmaea characteristics. The degree of degradation of alpine meadows may be delineated by development of mattic epipedon and PFG composition. Thus, meadows could be easily graded and their use adjusted based on our scaling system, which would help prevent irreversible degradation of important grasslands. Because relatively few environmental factors are investigated, this approach can save time and labor to formulate a conservation management plan for degraded alpine meadows.

Grassland Bird Conservation Efforts in Missouri and Iowa: How Will We Measure Success?

Treesearch

Brad Jacobs; Rolf R. Koford; Frank R. Thompson III; Hope Woodward; Mike Hubbard; Jane A. Fitzgerald; James R. Herkert

2005-01-01

Missouri and Iowa have adopted the Bird Conservation Area (BCA) model of Partners in Flight and applied the BCA model to ten areas managed to benefit grassland birds. These ten BCAs have large core areas of continuous grassland centered on active lek sites of Greater Prairie-Chickens (Tympanuchus cupido). Management is focused on expanding the number...

National forests on the edge: development pressures on America's national forests and grasslands.

Treesearch

Ralph J. Alig; Eric M. White; Sara J. Comas; Mary Carr; Mike Eley; Kelly Elverum; Mike O' Donnell; David M. Theobald; Ken Cordell; Jonathan Haber; Theodore W. Beauvais

2007-01-01

Many of America’s national forests and grasslands—collectively called the National Forest System—face increased risks and alterations from escalating housing development on private rural lands along their boundaries. National forests and grasslands provide critical social, ecological, and economic benefits to the American public. This study projects future housing...

Impact of two different types of grassland-to-cropland-conversion on dynamics of soil organic matter mineralization and N2O emission

NASA Astrophysics Data System (ADS)

Roth, G.; Flessa, H.; Helfrich, M.; Well, R.

2012-04-01

Conversion of grassland to arable land often causes a decrease of soil organic matter stocks and it increases nitrate leaching and the emission of the greenhouse gases CO2 and N2O. Conversion methods which minimize the mechanical impact on the surface soil may reduce mineralization rates and greenhouse gas emissions. We determined the effect of two different types of grassland to maize conversion (a) plowing of the sward followed by seeding of maize and (b) chemical killing of the sward by glyphosate followed by direct seed of maize) on the mineralization of grassland derived organic matter, the release of nitrate and the emission of N2O. The field experiment was carried out at the research station Kleve which is located in North Rhine-Westphalia, Germany. A four times replicated plot experiment with the following treatments was set up in April 2010: (i) mechanical conversion of grassland to maize (ii) chemical conversion grassland to maize and (iii) continuous grassland as reference. Nitrogen fertilization was 137 kg N ha-1 for maize and 250 kg N ha-1 for grassland. Soil respiration and emission of N2O were measured weekly for one year using manual closed chambers and gas chromatography. Emission of CO2 from mineralization of grassland-derived organic matter was determined from the δ13C signature of soil respiration. Soil respiration was mainly fueled by mineralization of grassland-derived organic carbon. There was no effect of the type of grassland conversion on total mineralization of organic matter originating from grassland. Both grassland to maize conversion treatments exhibited very high soil nitrate concentrations one year after grassland conversion (about 250 kg NO3-N in 0 - 90 cm). Total N2O emission decreased in the order chemical conversion of grassland (25.5) > mechanical conversion of grassland (20.1) > permanent grassland (10.8). Emissions were highest after harvest of maize when soil moisture increased. The results show that both types of grassland

The impact of human-environment interactions on the stability of forest-grassland mosaic ecosystems

PubMed Central

Innes, Clinton; Anand, Madhur; Bauch, Chris T.

2013-01-01

Forest-grassland mosaic ecosystems can exhibit alternative stables states, whereby under the same environmental conditions, the ecosystem could equally well reside either in one state or another, depending on the initial conditions. We develop a mathematical model that couples a simplified forest-grassland mosaic model to a dynamic model of opinions about conservation priorities in a population, based on perceptions of ecosystem rarity. Weak human influence increases the region of parameter space where alternative stable states are possible. However, strong human influence precludes bistability, such that forest and grassland either co-exist at a single, stable equilibrium, or their relative abundance oscillates. Moreover, a perturbation can shift the system from a stable state to an oscillatory state. We conclude that human-environment interactions can qualitatively alter the composition of forest-grassland mosaic ecosystems. The human role in such systems should be viewed as dynamic, responsive element rather than as a fixed, unchanging entity. PMID:24048359

Current challenges in distinguishing climatic and anthropogenic contributions to alpine grassland variation on the Tibetan Plateau.

PubMed

Li, Lanhui; Zhang, Yili; Liu, Linshan; Wu, Jianshuang; Li, Shicheng; Zhang, Haiyan; Zhang, Binghua; Ding, Mingjun; Wang, Zhaofeng; Paudel, Basanta

2018-06-01

Quantifying the impact of climate change and human activities on grassland dynamics is an essential step for developing sustainable grassland ecosystem management strategies. However, the direction and magnitude of climate change and human activities in driving alpine grassland dynamic over the Tibetan Plateau remain under debates. Here, we systematically reviewed the relevant studies on the methods, main conclusions, and causes for the inconsistency in distinguishing the respective contribution of climatic and anthropogenic forces to alpine grassland dynamic. Both manipulative experiments and traditional statistical analysis show that climate warming increase biomass in alpine meadows and decrease in alpine steppes, while both alpine steppes and meadows benefit from an increase in precipitation or soil moisture. Overgrazing is a major factor for the degradation of alpine grassland in local areas with high level of human activity intensity. However, across the entire Tibetan Plateau and its subregions, four views characterize the remaining controversies: alpine grassland changes are primarily due to (1) climatic force, (2) nonclimatic force, (3) combination of anthropogenic and climatic force, or (4) alternation of anthropogenic and climatic force. Furthermore, these views also show spatial inconsistencies. Differences on the source and quality of remote sensing products, the structure and parameter of models, and overlooking the spatiotemporal heterogeneity of human activity intensity contribute to current disagreements. In this review, we highlight the necessity for taking the spatiotemporal heterogeneity of human activity intensity into account in the models of attribution assessment, and the importance for accurate validation of climatic and anthropogenic contribution to alpine grassland variation at multiple scales for future studies.

Changes in the temperature sensitivity of SOM decomposition with grassland succession: implications for soil C sequestration.

PubMed

Nianpeng, He; Ruomeng, Wang; Yang, Gao; Jingzhong, Dai; Xuefa, Wen; Guirui, Yu

2013-12-01

Understanding the temperature sensitivity (Q 10) of soil organic matter (SOM) decomposition is important for predicting soil carbon (C) sequestration in terrestrial ecosystems under warming scenarios. Whether Q 10 varies predictably with ecosystem succession and the ways in which the stoichiometry of input SOM influences Q 10 remain largely unknown. We investigate these issues using a grassland succession series from free-grazing to 31-year grazing-exclusion grasslands in Inner Mongolia, and an incubation experiment performed at six temperatures (0, 5, 10, 15, 20, and 25°C) and with four substrates: control (CK), glucose (GLU), mixed grass leaf (GRA), and Medicago falcata leaf (MED). The results showed that basal soil respiration (20°C) and microbial biomass C (MBC) logarithmically decreased with grassland succession. Q 10 decreased logarithmically from 1.43 in free-grazing grasslands to 1.22 in 31-year grazing-exclusion grasslands. Q 10 increased significantly with the addition of substrates, and the Q 10 levels increased with increase in N:C ratios of substrate. Moreover, accumulated C mineralization was controlled by the N:C ratio of newly input SOM and by incubation temperature. Changes in Q 10 with grassland ecosystem succession are controlled by the stoichiometry of newly input SOM, MBC, and SOM quality, and the combined effects of which could partially explain the mechanisms underlying soil C sequestration in the long-term grazing-exclusion grasslands in Inner Mongolia, China. The findings highlight the effect of substrate stoichiometry on Q 10 which requires further study.

Changes in Temperature Sensitivity and Activation Energy of Soil Organic Matter Decomposition in Different Qinghai-Tibet Plateau Grasslands

PubMed Central

Li, Jie; He, Nianpeng; Wei, Xuehong; Gao, Yang; Zuo, Yao

2015-01-01

Qinghai-Tibet Plateau grasslands are unique geographical regions and store substantial soil organic matter (SOM) in the soil surface, which make them very sensitive to global climate change. Here, we focused on three main grassland types (alpine meadow, steppe, and desert) and conducted a soil incubation experiment at five different temperatures (5, 10, 15, 20, and 25°C) to investigate SOM decomposition rates (R), temperature sensitivity (Q 10), and activation energy (E a). The results showed that grassland type and incubation temperature had significant impact on R (P < 0.001), and the values of R were exponential correlated with incubation temperature in three alpine grasslands. At the same temperature, R was in the following order: alpine meadow > alpinesteppe > alpine desert. The Q 10 values differed significantly among different grasslands, and the overall trends were as follows: alpine meadow (1.56 ± 0.09) < alpine steppe (1.88 ± 0.23) < alpine desert (2.39 ± 0.32). Moreover, the E a values differed significantly across different grassland types (P < 0.001) and increased with increasing incubation time. The exponential negative correlations between E a and R at 20°C across all grassland types (all Ps < 0.001) indicated that the substrate-quality temperature hypothesis is applicable to the alpine grasslands. Our findings provide new insights for understanding the responses of SOM decomposition and storage to warming scenarios in this Plateau. PMID:26176705

The Elum Project: A Network of UK Sites to Understand Land-Use Transitions to Bioenergy and Their Implications for Greenhouse Gas Balance and Carbon Cycling

NASA Astrophysics Data System (ADS)

Harris, Z. M.; Alberti, G.; Bottoms, E.; Rowe, R.; Parmar, K.; Marshall, R.; Elias, D.; Smith, P.; Dondini, M.; Pogson, M.; Richards, M.; Finch, J.; Ineson, P.; Keane, B.; Perks, M.; Wilkinson, M.; Yamulki, S.; Donnison, I.; Farrar, K.; Massey, A.; McCalmont, J.; Drewer, J.; Sohi, S.; McNamara, N.; Taylor, G.

2014-12-01

Rising anthropogenic greenhouse gas (GHG) emissions coupled with an increasing need to address energy security are resulting in the development of cleaner, more sustainable alternatives to traditional fossil fuel sources. Bioenergy crops have been proposed to be able to mitigate the effects of climate change as well as provide increased energy security. The aim of this project is to assess the impact of land conversion to second generation non-food bioenergy crops on GHG balance for several land use transitions, including from arable, grassland and forest. A network of 6 sites was established across the UK to assess the processes underpinning GHG balance and to provide input data to a model being used to assess the sustainability of different land use transitions. Monthly analysis of soil GHGs shows that carbon dioxide contributes most to the global warming potential of these bioenergy crops, irrespective of transition. Nitrous oxide emissions were low for all crops except arable cropping and methane emissions were very low for all sites. Nearly all sites have shown a significant decrease in CO2 flux from the control land use. Eddy flux approaches, coupled with soil assessments show that for the transition from grassland to SRC willow there is a significant reduction in GHG emissions from soil and a negative net ecosystem exchange due to increased GPP and ecosystem respiration. These results suggest for this land use transition to bioenergy in a UK specific context, there may be a net benefit for ecosystem GHG exchange of transition to bioenergy Finally we are developing a meta-modelling tool to allow land use managers to make location-specific, informed decisions about land use change to bioenergy. This work is based on the Ecosystem Land Use Modelling & Soil Carbon GHG Flux Trial (ELUM) project, which was commissioned and funded by the Energy Technologies Institute (ETI). This project is co-ordinated by the Centre for Ecology & Hydrology (www.elum.ac.uk).

Winter climate change effects on soil C and N cycles in urban grasslands.

PubMed

Durán, Jorge; Rodríguez, Alexandra; Morse, Jennifer L; Groffman, Peter M

2013-09-01

Despite growing recognition of the role that cities have in global biogeochemical cycles, urban systems are among the least understood of all ecosystems. Urban grasslands are expanding rapidly along with urbanization, which is expected to increase at unprecedented rates in upcoming decades. The large and increasing area of urban grasslands and their impact on water and air quality justify the need for a better understanding of their biogeochemical cycles. There is also great uncertainty about the effect that climate change, especially changes in winter snow cover, will have on nutrient cycles in urban grasslands. We aimed to evaluate how reduced snow accumulation directly affects winter soil frost dynamics, and indirectly greenhouse gas fluxes and the processing of carbon (C) and nitrogen (N) during the subsequent growing season in northern urban grasslands. Both artificial and natural snow reduction increased winter soil frost, affecting winter microbial C and N processing, accelerating C and N cycles and increasing soil : atmosphere greenhouse gas exchange during the subsequent growing season. With lower snow accumulations that are predicted with climate change, we found decreases in N retention in these ecosystems, and increases in N2 O and CO2 flux to the atmosphere, significantly increasing the global warming potential of urban grasslands. Our results suggest that the environmental impacts of these rapidly expanding ecosystems are likely to increase as climate change brings milder winters and more extensive soil frost. © 2013 John Wiley & Sons Ltd.

Defoliation and arbuscular mycorrhizal fungi shape plant communities in overgrazed semi-arid grasslands.

PubMed

Yang, Xin; Shen, Yue; Liu, Nan; Wilson, Gail W T; Cobb, Adam B; Zhang, Yingjun

2018-05-30

Overgrazing substantially contributes to global grassland degradation by decreasing plant community productivity and diversity through trampling, defoliation, and removal of nutrients. Arbuscular mycorrhizal (AM) fungi also play a critical role in plant community diversity, composition, and primary productivity, maintaining ecosystem functions. However, interactions between grazing disturbances, such as trampling and defoliation, and AM fungi in grassland communities are not well known. We examined influences of trampling, defoliation, and AM fungi on semi-arid grassland plant community composition for three years, by comparing all combinations of these factors. Benomyl fungicide was applied to reduce AM fungal abundance. Overgrazing typically resulted in reduced dominance of Stipa Krylovii, contributing to degradation of typical steppe grasslands. Our results indicated trampling generally had little effect on plant community composition, unless combined with defoliation or AM fungal suppression. Defoliation was the main component of grazing that promoted dominance of Potentilla acaulis over Stipa krylovii and Artemisia frigida, presumably by alleviating light limitation. In non-defoliated plots, AM fungi promoted A. frigida, with a concomitant reduction in S. krylovii growth compared to corresponding AM suppressed plots. Our results indicate AM fungi and defoliation jointly suppress S. krylovii biomass; however, prolonged defoliation weakens mycorrhizal influence on plant community composition. These findings give new insight into dominant plant species shifts in degraded semi-arid grasslands. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Soil microbial communities of three grassland ecosystems in the Bayinbuluke, China.

PubMed

Shao, Keqiang; Gao, Guang

2018-03-01

The microbial community plays an important role in soil nutrient cycles and energy transformations in alpine grassland. In this study, we investigated the composition of the soil microbial community collected from alpine cold swamp meadow (ASM), alpine cold meadow (AM), and alpine cold desert steppe (ADS) within the Bayinbuluke alpine grassland, China, using Illumina amplicon sequencing. Of the 147 271 sequences obtained, 36 microbial phyla or groups were detected. The results showed that the ADS had lower microbial diversity than the ASM and AM, as estimated by the Shannon index. The Verrucomicrobia, Chloroflexi, Planctomycetes, Proteobacteria, and Actinobacteria were the predominant phyla in all 3 ecosystems. Particularly, Thaumarchaeota was only abundant in ASM, Bacteroidetes in AM, and Acidobacteria in ADS. Additionally, the predominant genus also differed with each ecosystem. Candidatus Nitrososphaera was predominant in ADS, the Pir4 lineage in ASM, and Sphingomonas in AM. Our results indicated that the soil microbial community structure was different for each grassland ecosystem in the Bayinbuluke.

Soil organic matter dynamics under different land-use in grasslands in Inner Mongolia (northern China)

NASA Astrophysics Data System (ADS)

Zhao, L.; Wu, W.; Xu, X.; Xu, Y.

2014-04-01

We examined bulk soil properties and molecular biomarker distributions in surface soils from Inner Mongolia grasslands in order to understand the responses of soil organic matter to different land-use. The total of sixteen soils were collected from severely degraded grassland by overgrazing (DG), native grassland without apparent anthropogenic disturbance (NG), groundwater-sustaining grassland (GG) and restored grassland from previous potato cropland (RG). Compared to NG, soil organic carbon content was lower by 50% in DG, but higher by six-fold in GG and one-fold in RG. The δ13C values of soil organic carbon were -24.2 ± 0.6‰ in DG, -24.9 ± 0.6‰ in NG, -25.1 ± 0.1‰ in RG and -26.2 ± 0.6‰ in GG, reflecting different degradation degrees of soil organic matter or different water use efficiencies. The soils in DG contained the lowest abundance of aliphatic lipids (n-alkanes, n-alkanols, n-alkanoic acids, ω-hydroxylalkanoic acids and α-hydroxylalkanoic acids) and lignin-phenols, suggesting selective removal of these biochemically recalcitrant biomarkers with grassland degradation by microbial respiration or wind erosion. Compared to NG, the soils in GG and RG increased ω-hydroxylalkanoic acids by 60-70%, a biomarker for suberin from roots, and increased α-hydroxylalkanoic acids by 10-20%, a biomarker for both cutin and suberin. Our results demonstrate that the groundwater supply and cultivation-restoration practices in Inner Mongolia grasslands not only enhance soil organic carbon sequestration, but also change the proportions of shoot vs. root-derived carbon in soils. This finding has important implications for global carbon cycle since root derived aliphatic carbon has a longer residence time than the aboveground tissue-derived carbon in soils.

Soil organic matter dynamics under different land use in grasslands in Inner Mongolia (northern China)

NASA Astrophysics Data System (ADS)

Zhao, L.; Wu, W.; Xu, X.; Xu, Y.

2014-09-01

We examined bulk soil properties and molecular biomarker distributions in surface soils from Inner Mongolian grasslands in order to understand the responses of soil organic matter to different land use. A total of 16 soils were collected from severely degraded grassland by overgrazing (DG), native grassland without apparent anthropogenic disturbance (NG), groundwater-sustaining grassland (GG) and restored grassland from previous potato cropland (RG). Compared to NG, soil organic carbon content was lower by 50% in DG, but higher by six-fold in GG and one-fold in RG. The δ13C values of soil organic carbon were -24.2 ± 0.6‰ in DG, -24.9 ± 0.6‰ in NG, -25.1 ± 0.1‰ in RG and -26.2 ± 0.6‰ in GG, reflecting different degradation degrees of soil organic matter or different water use efficiencies. The soils in DG contained the lowest abundance of aliphatic lipids (n-alkanes, n-alkanols, n-alkanoic acids, ω-hydroxylalkanoic acids and α-hydroxyalkanoic acids) and lignin-phenols, suggesting selective removal of these biochemically recalcitrant biomarkers with grassland degradation by microbial respiration or wind erosion. Compared to NG, the soils in GG and RG increased ω-hydroxylalkanoic acids by 60-70%, a biomarker for suberin from roots, and increased α-hydroxylalkanoic acids by 10-20%, a biomarker for both cutin and suberin. Our results demonstrate that the groundwater supply and cultivation-restoration practices in Inner Mongolian grasslands not only enhance soil organic carbon sequestration, but also change the proportions of shoot- versus root-derived carbon in soils. This finding has important implications for the global carbon cycle since root-derived aliphatic carbon has a longer residence time than the aboveground tissue-derived carbon in soils.

Mixed-severity fire history at a forest-grassland ecotone in west central British Columbia, Canada.

PubMed

Harvey, Jill E; Smith, Dan J; Veblen, Thomas T

2017-09-01

This study examines spatially variable stand structure and fire-climate relationships at a low elevation forest-grassland ecotone in west central British Columbia, Canada. Fire history reconstructions were based on samples from 92 fire-scarred trees and stand demography from 27 plots collected over an area of about 7 km 2 . We documented historical chronologies of widespread fires and localized grassland fires between AD 1600 and 1900. Relationships between fire events, reconstructed values of the Palmer Drought Severity Index, and annual precipitation were examined using superposed epoch and bivariate event analyses. Widespread fires occurred during warm, dry years and were preceded by multiple anomalously dry, warm years. Localized fires that affected only grassland-proximal forests were more frequent than widespread fires. These localized fires showed a lagged, positive relationship with wetter conditions. The landscape pattern of forest structure provided further evidence of complex fire activity with multiple plots shown to have experienced low-, mixed-, and/or high-severity fires over the last four centuries. We concluded that this forest-grassland ecotone was characterized by fires of mixed severity, dominated by frequent, low-severity fires punctuated by widespread fires of moderate to high severity. This landscape-level variability in fire-climate relationships and patterns in forest structure has important implications for fire and grassland management in west central British Columbia and similar environments elsewhere. Forest restoration techniques such as prescribed fire and thinning are oftentimes applied at the forest-grassland ecotone on the basis that historically high frequency, low-severity fires defined the character of past fire activity. This study provides forest managers and policy makers with important information on mixed-severity fire activity at a low elevation forest-grassland ecotone, a crucial prerequisite for the effective management

Evidence of qualitative differences between soil-occupancy effects of invasive vs. native grassland plant species

USGS Publications Warehouse

Jordan, Nicholas R.; Larson, Diane L.; Huerd, Sheri C.

2011-01-01

Diversified grasslands that contain native plant species are being recognized as important elements of agricultural landscapes and for production of biofuel feedstocks as well as a variety of other ecosystem services. Unfortunately, establishment of such grasslands is often difficult, unpredictable, and highly vulnerable to interference and invasion by weeds. Evidence suggests that soil-microbial "legacies" of invasive perennial species can inhibit growth of native grassland species. However, previous assessments of legacy effects of soil occupancy by invasive species that invade grasslands have focused on single invasive species and on responses to invasive soil occupancy in only a few species. In this study, we tested the hypothesis that legacy effects of invasive species differ qualitatively from those of native grassland species. In a glasshouse, three invasive and three native grassland perennials and a native perennial mixture were grown separately through three cycles of growth and soil conditioning in soils with and without arbuscular mycorrhizal fungi (AMF), after which we assessed seedling growth in these soils. Native species differed categorically from invasives in their response to soil conditioning by native or invasive species, but these differences depended on the presence of AMF. When AMF were present, native species largely had facilitative effects on invasive species, relative to effects of invasives on other invasives. Invasive species did not facilitate native growth; neutral effects were predominant, but strong soil-mediated inhibitory effects on certain native species occurred. Our results support the hypothesis that successful plant invaders create biological legacies in soil that inhibit native growth, but suggest also this mechanism of invasion will have nuanced effects on community dynamics, as some natives may be unaffected by such legacies. Such native species may be valuable as nurse plants that provide cost-effective restoration of

Spatial Pattern and Population Structure of Artemisia ordosica Shrub in a Desert Grassland under Enclosure, Northwest China.

PubMed

Liu, Jiankang; Zhang, Kebin

2018-05-09

Enclosure is an effective practice for restoring and rehabilitating the degraded grassland ecosystem caused by overgrazing. Shrub species, which are dominant in most desert grasslands in arid and semiarid regions, have some beneficial ecological functions for grassland restoration. However, how the population structure and spatial pattern of the Artemisia ordosica shrub changes in a grassland ecosystem under enclosed practice is not well understood. This study, conducted in the Mu Us desert in northwest China, was designed to measure the A. ordosica population according to the chronosequence of enclosure (enclosure periods ranged from 5 years, 10 years, 15 years, and 25 years), contrasting this with an adjacent continuously grazed grassland. The results showed that the enclosed grasslands had a higher number of individuals of different age classes (seedling, adult, aging, and dead group) and greater population coverage, but shrubs had significant lower ( p < 0.05) crown diameter and height in comparison with those in continuously grazed grassland. Further, enclosed grasslands had a significantly higher ( p < 0.05) Shannon-Wiener index (H) and Evenness index (E), but a significantly lower ( p < 0.05) Richness index (R) than continuously grazed grassland. The crown of A. ordosica showed a significant linear positive correlation with height in all plots across succession, indicating that it was feasible to analyze the age structure by crown. The crown-class distribution structure of the A. ordosica population approximated a Gaussian distribution model in all survey plots. Within the population, seedling and adult groups exhibited aggregated spatial distribution at small scales, while aging and dead A. ordosica groups showed random distribution at almost all scales in different plots. The seedling A. ordosica group showed a positive correlation with adults at small scales in all plots except in 10 years of enclosure. However, it showed independent correlation with

Environmental effects on water vapour and carbon dioxide exchange above two alpine grassland ecosystems on the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Wang, L.; Liu, H.

2017-12-01

Alpine grasslands (alpine steppe and alpine meadow) are the main grassland types in China. Based on eddy covariance flux data from July 15, 2014, to December 31, 2015, environmental effects on water vapour and carbon dioxide exchange were analyzed over a semiarid alpine steppe (Bange, Tibet) and a humid alpine meadow (Lijiang, Yunnan) on the Tibetan Plateau. During the wet season, the evaporative fraction (EF) at Bange was strongly and linearly correlated with the soil water content (SWC) because of its sparse green grass cover. In contrast, the correlation between the EF and the SWC at Lijiang was very low because the atmosphere was close to saturation and the EF was relatively constant. Evapotranspiration (ET) at Lijiang could be predicted well by net radiation and air temperature. In the dry season, the EF at both sites decreased with the SWC. The net ecosystem exchange (NEE) at Bange was largely depressed at noon, while this phenomenon did not occur at Lijiang due to good soil water conditions. The saturated NEE at Bange was 24% of that at Lijiang. The temperature sensitivity coefficient of ecosystem respiration at Bange (1.7) was also much lower than that at Lijiang (3.4). Moreover, the annual total NEE at Lijiang from 2012 to 2015 generally decreased with the mean annual air temperature (MAT). An exception occurred in 2014, which had the highest MAT, because the GPP increased with the MAT, but became saturated due to the limit in photosynthetic capacity. The annual total GPP at Lijiang were substantially affected by the seasonal pattern of air temperature, especially in spring and autumn. This is consistent with results obtained using the homogeneity-of-slopes model.

Analysis on the Change of Grassland Coverage in the Source Region of Three Rivers during 2000-2012

NASA Astrophysics Data System (ADS)

Luo, Chengfeng; Wang, Jiao; Liu, Meilin; Liu, Zhengjun

2014-03-01

The Source Region of Three Rivers (SRTR) has very important ecological functions which form an ecological security barrier for China's Qinghai-Tibet plateau. As the biggest nationally occuring nature reserve region in China, the ecological environment here is very fragile. In SRTR the grassland coverage is an effective detector to reflect the ecological environment condition, because it records the changing process of climatic and environmental sensitively. In recent years SRTR has been suffering pressures from both nature and social pressures. With MODIS data the study monitored the grassland coverage continuously in SRTR from 2000 to 2012. The density-model was adapted to estimate grassland coverage degree firstly. Then the degree of change and the change intensity, change type were used to judge the grassland coverage change trend comprehensively. For grassland coverage there was natural change annual or within the year, and the degree of change was used to judge if there was change or not. The grassland has another important characteristic, annual fluctuation, and it can be differed from sustained changes with change type. For grassland coverage, such continuous change, like improvement or degradation, and to what extent, has more guidance sense on specific production practice. On the base of change type and degree of change, change intensity was used to identify the change trend of the grassland coverage. The analysis results from our study show that steady state and fluctuation are two main change trends for the vegetation coverage in SRTR from 2000 to 2012. The conclusion of this paper can provide references in response to environment change research and in the regional ecological environmental protection project in SRTR.

MODIS normalized difference vegetation index (NDVI) and vegetation phenology dynamics in the Inner Mongolia grassland

NASA Astrophysics Data System (ADS)

Gong, Z.; Kawamura, K.; Ishikawa, N.; Goto, M.; Wulan, T.; Alateng, D.; Yin, T.; Ito, Y.

2015-11-01

The Inner Mongolia grassland, one of the most important grazing regions in China, has long been threatened by land degradation and desertification, mainly due to overgrazing. To understand vegetation responses over the last decade, this study evaluated trends in vegetation cover and phenology dynamics in the Inner Mongolia grassland by applying a normalized difference vegetation index (NDVI) time series obtained by the Terra Moderate Resolution Imaging Spectroradiometer (MODIS) during 2002-2014. The results showed that the cumulative annual NDVI increased to over 77.10 % in the permanent grassland region (2002-2014). The mean value of the total change showed that the start of season (SOS) date and the peak vegetation productivity date of the season (POS) had advanced by 5.79 and 2.43 days, respectively. The end of season (EOS) was delayed by 5.07 days. These changes lengthened the season by 10.86 days. Our results also confirmed that grassland changes are closely related to spring precipitation and increasing temperature at the early growing period because of global warming. Overall, productivity in the Inner Mongolia Autonomous Region tends to increase, but in some grassland areas with grazing, land degradation is ongoing.

Wet weather exposure measures

DOT National Transportation Integrated Search

1988-02-01

Accident surveillance programs require a measure of wet-pavement exposure to determine whether the wet-pavement accident rates of particular highway sections are higher or lower than expected. This research program used the results of laboratory and ...

Response of a subalpine grassland to simulated grazing: Aboveground productivity along soil phosphorus gradients

Treesearch

C. Thiel-Egenter; A. C. Risch; M. F. Jurgensen; D. S. Page-Dumroese; B. O. Krusi; M. Schutz

2007-01-01

Interactions between grassland ecosystems and vertebrate herbivores are critical for a better understanding of ecosystem processes, but diverge widely in different ecosystems. In this study, we examined plant responses to simulated red deer (Cervus elaphus L.) grazing using clip-plot experiments in a subalpine grassland ecosystem of the Central...

Effects of temperature and grazing on soil organic carbon storage in grasslands along the Eurasian steppe eastern transect.

PubMed

Zhao, Yanyun; Ding, Yong; Hou, Xiangyang; Li, Frank Yonghong; Han, Wenjun; Yun, Xiangjun

2017-01-01

Soil represents the largest terrestrial organic carbon pool. To address global climate change, it is essential to explore the soil organic carbon storage patterns and their controlling factors. We investigated the soil organic carbon density (SOCD) in 48 grassland sites along the Eurasian steppe eastern transect (ESET) region, which covers the Inner Mongolia grassland subregion and Mongolia grasslands subregion. Specifically, we analyzed the SOCD in the top 30 cm soil layer and its relationships with climatic variables, soil texture, grazing intensity and community biomass productivity. The results showed that the average SOCD of the ESET was 4.74 kg/m2, and the SOCD of the Inner Mongolia grassland subregion (4.11 kg/m2) was significantly lower than that of the Mongolia grassland subregion (5.79 kg/m2). Significant negative relationships were found between the SOCD and the mean annual temperature (MAT), mean annual precipitation (MAP) and grazing intensity in the ESET region. The MAT and grazing intensity were identified as the major factors influencing the SOCD in the ESET region; the MAP and MAT were the major factors influencing the SOCD in the Inner Mongolia grassland subregion; and the MAT and soil pH were the major factors influencing the SOCD in the Mongolia grassland subregion.

Effects of temperature and grazing on soil organic carbon storage in grasslands along the Eurasian steppe eastern transect

PubMed Central

Hou, Xiangyang; Li, Frank Yonghong; Han, Wenjun; Yun, Xiangjun

2017-01-01

Soil represents the largest terrestrial organic carbon pool. To address global climate change, it is essential to explore the soil organic carbon storage patterns and their controlling factors. We investigated the soil organic carbon density (SOCD) in 48 grassland sites along the Eurasian steppe eastern transect (ESET) region, which covers the Inner Mongolia grassland subregion and Mongolia grasslands subregion. Specifically, we analyzed the SOCD in the top 30 cm soil layer and its relationships with climatic variables, soil texture, grazing intensity and community biomass productivity. The results showed that the average SOCD of the ESET was 4.74 kg/m2, and the SOCD of the Inner Mongolia grassland subregion (4.11 kg/m2) was significantly lower than that of the Mongolia grassland subregion (5.79 kg/m2). Significant negative relationships were found between the SOCD and the mean annual temperature (MAT), mean annual precipitation (MAP) and grazing intensity in the ESET region. The MAT and grazing intensity were identified as the major factors influencing the SOCD in the ESET region; the MAP and MAT were the major factors influencing the SOCD in the Inner Mongolia grassland subregion; and the MAT and soil pH were the major factors influencing the SOCD in the Mongolia grassland subregion. PMID:29084243

Relationships between botanical and chemical composition of forages: a multivariate approach to grasslands in the Western Italian Alps.

PubMed

Ravetto Enri, Simone; Renna, Manuela; Probo, Massimiliano; Lussiana, Carola; Battaglini, Luca M; Lonati, Michele; Lombardi, Giampiero

2017-03-01

Plant composition of species-rich mountain grasslands can affect the sensorial and chemical attributes of dairy and meat products, with implications for human health. A multivariate approach was used to analyse the complex relationships between vegetation characteristics (botanical composition and plant community variables) and chemical composition (proximate constituents and fatty acid profile) in mesophilic and dry vegetation ecological groups, comprising six different semi-natural grassland types in the Western Italian Alps. Mesophilic and dry grasslands were comparable in terms of phenology, biodiversity indices and proportion of botanical families. The content of total fatty acids and that of the most abundant fatty acids (alpha-linolenic, linoleic and palmitic acids) were mainly associated to nutrient-rich plant species, belonging to the mesophilic grassland ecological group. Mesophilic grasslands showed also higher values of crude protein, lower values of fibre content and they were related to higher pastoral values of vegetation compared to dry grasslands. The proximate composition and fatty acid profile appeared mainly single species dependent rather than botanical family dependent. These findings highlight that forage from mesophilic grasslands can provide higher nutritive value for ruminants and may be associated to ruminant-derived food products with a healthier fatty acid profile. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Conserving Prairie Pothole Region wetlands and surrounding grasslands: evaluating effects on amphibians

USGS Publications Warehouse

Mushet, David M.; Neau, Jordan L.

2014-01-01

The maintenance of viable and genetically diverse populations of amphibians in the Prairie Pothole Region of the United States depends on upland as well as wetland over-wintering and landscape level habitat features.Prairie pothole wetlands provide important amphibian breeding habitat while grasslands surrounding these wetlands provide foraging habitat for adults, overwintering habitat for some species, and important connectivity among breeding wetlands.Grasslands surrounding wetlands were found to be especially important for wood frogs and northern leopard frogs, while croplands dominated habitat utilized by Great Plains toads and Woodhouse’s toads.Habitat suitability mapping highlighted (1) the influence of deep-water overwintering wetlands on suitable habitat for four of five anuran species encountered; (2) the lack of overlap between areas of core habitat for both the northern leopard frog and wood frog compared to the core habitat for both toad species; and (3) the importance of conservation programs in providing grassland components of northern leopard frog and wood frog habitat.Currently, there are approximately 7.2 million acres (2.9 million hectares, ha) of habitat in the PPR identified as suitable for amphibians. WRP and CRP wetland and grassland habitats accounted for approximately 1.9 million acres (0.75 million ha) or 26 percent of this total area.Continued loss of amphibian habitat resulting from an ongoing trend of returning PPR conservation lands to crop production, will likely have significant negative effects on the region’s ability to maintain amphibian biodiversity. Conversely, increases in conservation wetlands and surrounding grasslands on the PPR landscape have great potential to positively influence the region’s amphibian populations.

No Significant Changes in Topsoil Carbon in the Grasslands of Northern China Between the 1980s and 2000s

NASA Astrophysics Data System (ADS)

Liu, S.; Yang, Y.; Shen, H.; Hu, H.; Zhao, X.; Li, H.; Liu, T.; Fang, J.

2017-12-01

The grasslands of northern China store a large amount of soil organic carbon (SOC), and the small changes in SOC stock could significantly affect the regional C cycle. However, recent estimates of SOC changes in this region are highly controversial. In this study, we examined and mapped the changes in the SOC density (SOCD) in the upper 30 cm of the grasslands of northern China between the 1980s and 2000s, using an improved approach that integrates field-based measurements into machine learning algorithms (artificial neural network and random forest). The random forest-generated SOCD averaged 5.55 kg C m-2 in the 1980s and 5.53 kg C m-2 in the 2000s. The change ranged between -0.17 and 0.22 kg C m-2 at the 95% confidence level, suggesting that the overall SOCD did not change significantly during the study period. However, the change in SOCD exhibited large regional variability. The topsoil of the Inner Mongolian grasslands experienced a significant C loss (4.86 vs. 4.33 kg C m-2), whereas that of the Xinjiang grasslands exhibited an accumulation of C (5.55 vs. 6.46 kg C m-2). In addition, the topsoil C in the Tibetan alpine grasslands remained relatively stable (6.12 vs. 6.06 kg C m-2). A comparison of different grassland types indicated that SOCD exhibited significant decreases in typical steppe, whereas showed increases in mountain meadow, and were stable in the remaining grasslands (alpine meadow, alpine steppe, mountain steppe and desert steppe). Climate variables were shown to be the main determines of the change of SOCD. Increases in precipitation could lead to SOC increase in temperate grasslands and SOC loss in alpine grasslands, while climate warming is likely to cause SOC loss in temperate grasslands. Overall, our study shows that northern grasslands in China remained a neutral SOC sink between the 1980s and 2000s.

Arthropod and oligochaete assemblages from grasslands of the southern Kenai Peninsula, Alaska

PubMed Central

Bowser, Matthew L.; Morton, John M.; Hanson, John Delton; Magness, Dawn R.; Okuly, Mallory

2017-01-01

Abstract Background By the end of this century, the potential climate-biome of the southern Kenai Peninsula is forecasted to change from transitional boreal forest to prairie and grasslands, a scenario that may already be playing out in the Caribou Hills region. Here, spruce (Picea × lutzii Little [glauca × sitchensis]) forests were heavily thinned by an outbreak of the spruce bark beetle (Dendroctonus rufipennis (Kirby, 1837)) and replaced by the native but invasive grass species, Calamagrostis canadensis (Michx.) P. Beauv. As part of a project designed to delimit and characterize potentially expanding grasslands in this region, we sought to characterize the arthropod and earthworm communities of these grasslands. We also used this sampling effort as a trial of applying high-throughput sequencing metabarcoding methods to a real-world inventory of terrestrial arthropods. New information We documented 131 occurrences of 67 native arthropod species at ten sites, characterizing the arthropod fauna of these grasslands as being dominated by Hemiptera (60% of total reads) and Diptera (38% of total reads). We found a single exotic earthworm species, Dendrobaena octaedra (Savigny, 1826), at 30% of sites and one unidentified enchytraeid at a single site. The utility of high-throughput sequencing metabarcoding as a tool for bioassessment of terrestrial arthropod assemblages was confirmed. PMID:28325976

Wetting Transition of Water

NASA Astrophysics Data System (ADS)

Friedman, Serah; Khalil, Matt; Taborek, Peter

2013-03-01

Pure liquid water does not wet most solid surfaces. Liquid water on these surfaces beads up and forms droplets with a finite contact angle. General thermodynamic principles suggest that as the temperature approaches the critical point, the contact angle should go to zero, marking the wetting transition. We have made an optical cell which can operate near the critical point of water (Tc =373C, Pc =217 atm) to study this phenomenon on sapphire, graphite and silicon. We have used two methods to measure the wetting temperature of water on these surfaces. Firstly, we studied a single droplet on a horizontal surface and optically measured the change in contact angle as a function of increasing temperature. Second, we studied the condensation of droplets on a vertical plate as a function of temperature. As the temperature approached the wetting temperature in both cases, the droplets spread and eventually form a smooth film along the surface of the plate. The wetting temperature on sapphire is near 240C and is considerably higher on graphite. Our observed values of Tw are significantly higher than the predictions made by the sharp-kink approximation and recent molecular dynamics simulations.

Preliminary response of primary production and community composition to precipitation variation in a temperate grassland

USDA-ARS?s Scientific Manuscript database

a) Background/Questions/Methods Grassland ecosystems are water-limited and show the highest interannual ANPP variability across biomes. Changes in annual amounts or seasonality of rainfall may interact with soil texture to impact grassland ecosystem functions including net primary productivity (NPP...

Mapping grassland productivity with 250-m eMODIS NDVI and SSURGO database over the Greater Platte River Basin, USA

USGS Publications Warehouse

Gu, Yingxin; Wylie, Bruce K.; Bliss, Norman B.

2013-01-01

This study assessed and described a relationship between satellite-derived growing season averaged Normalized Difference Vegetation Index (NDVI) and annual productivity for grasslands within the Greater Platte River Basin (GPRB) of the United States. We compared growing season averaged NDVI (GSN) with Soil Survey Geographic (SSURGO) database rangeland productivity and flux tower Gross Primary Productivity (GPP) for grassland areas. The GSN was calculated for each of nine years (2000–2008) using the 7-day composite 250-m eMODIS (expedited Moderate Resolution Imaging Spectroradiometer) NDVI data. Strong correlations exist between the nine-year mean GSN (MGSN) and SSURGO annual productivity for grasslands (R2 = 0.74 for approximately 8000 pixels randomly selected from eight homogeneous regions within the GPRB; R2 = 0.96 for the 14 cluster-averaged points). Results also reveal a strong correlation between GSN and flux tower growing season averaged GPP (R2 = 0.71). Finally, we developed an empirical equation to estimate grassland productivity based on the MGSN. Spatially explicit estimates of grassland productivity over the GPRB were generated, which improved the regional consistency of SSURGO grassland productivity data and can help scientists and land managers to better understand the actual biophysical and ecological characteristics of grassland systems in the GPRB. This final estimated grassland production map can also be used as an input for biogeochemical, ecological, and climate change models.

Faunal isotope records reveal trophic and nutrient dynamics in twentieth century Yellowstone grasslands

PubMed Central

Fox-Dobbs, Kena; Nelson, Abigail A.; Koch, Paul L.; Leonard, Jennifer A.

2012-01-01

Population sizes and movement patterns of ungulate grazers and their predators have fluctuated dramatically over the past few centuries, largely owing to overharvesting, land-use change and historic management. We used δ13C and δ15N values measured from bone collagen of historic and recent gray wolves and their potential primary prey from Yellowstone National Park to gain insight into the trophic dynamics and nutrient conditions of historic and modern grasslands. The diet of reintroduced wolves closely parallels that of the historic population. We suggest that a significant shift in faunal δ15N values over the past century reflects impacts of anthropogenic environmental changes on grassland ecosystems, including grazer-mediated shifts in grassland nitrogen cycle processes. PMID:22675135

Numerical studies on groundwater-grassland relations in an inland arid region in China

NASA Astrophysics Data System (ADS)

Wang, J. R.; Hu, L. T.; Sun, K. N.; Liu, X. M.

2017-08-01

In this study, a 2-D numerical model was developed to assess the impacts of groundwater on grassland ecology in the Hulun Lake Basin. An extreme dry climate scenario and water resource management scenario and their interactions in the Hulun Lake Basin were designed, and their influence on groundwater was evaluated. The results show that the grassland ecology is heavily dependent on groundwater, and a distribution of groundwater with a depth of 8 m correlates well with the distribution of grassland. Under the water resource management scenario, the groundwater level will increase to a maximum value of 2.5 m after 15 years around Hulun Lake. The groundwater level will decrease dramatically under the extreme dry climate scenario, thus affecting the environment.

Chihuahuan Desert grassland responds similarly to fall, spring, and summer fires during prolonged drought

Treesearch

Laura M. Ladwig; Scott L. Collins; Paulette L. Ford; Laura B. White

2014-01-01

Land managers frequently use prescribed burning to help maintain grassland communities. Semiarid grassland dynamics following fire are linked to precipitation, with increasing soil moisture accelerating the rate of recovery. Prescribed fires are typically scheduled to follow natural fire regimes, but burning outside the natural fire season could be equally effective...

Canopy reflectance modeling in a tropical wooded grassland

NASA Technical Reports Server (NTRS)

Simonett, David; Franklin, Janet

1986-01-01

Geometric/optical canopy reflectance modeling and spatial/spectral pattern recognition is used to study the form and structure of savanna in West Africa. An invertible plant canopy reflectance model is tested for its ability to estimate the amount of woody vegetation from remotely sensed data in areas of sparsely wooded grassland. Dry woodlands and wooded grasslands, commonly referred to as savannas, are important ecologically and economically in Africa, and cover approximately forty percent of the continent by some estimates. The Sahel and Sudan savannas make up the important and sensitive transition zone between the tropical forests and the arid Sahara region. The depletion of woody cover, used for fodder and fuel in these regions, has become a very severe problem for the people living there. LANDSAT Thematic Mapper (TM) data is used to stratify woodland and wooded grassland into areas of relatively homogeneous canopy cover, and then an invertible forest canopy reflectance model is applied to estimate directly the height and spacing of the trees in the stands. Because height and spacing are proportional to biomass in some cases, a successful application of the segmentation/modeling techniques will allow direct estimation of tree biomass, as well as cover density, over significant areas of these valuable and sensitive ecosystems. The model being tested in sites in two different bioclimatic zones in Mali, West Africa, will be used for testing the canopy model. Sudanian zone crop/woodland test sites were located in the Region of Segou, Mali.

SETAC-U.S. EPA WET INITIATIVES: ALL WET AND NOTHING BUT WET

EPA Science Inventory

To ensure that sould scientific principles and sound science are applied to the challenging issues in t he Whole Effluent Toxicity (WET) process, the Society of Environmental Toxicology and Chemistry (SETAC) Foundation for Environmental Education was awarded a cooperative agreem...

A critical analysis of one standard and five methods to monitor surface wetness and time-of-wetness

NASA Astrophysics Data System (ADS)

Camuffo, Dario; della Valle, Antonio; Becherini, Francesca

2018-05-01

Surface wetness is a synergistic factor to determine atmospheric corrosion, monument weathering, mould growth, sick buildings, etc. However, its detection and monitoring are neither easy nor homogeneous, for a number of factors that may affect readings. Various types of methods and sensors, either commercial or prototypes built in the lab, have been investigated and compared, i.e. the international standard ISO 9223 to evaluate corrosivity after wetness and time-of-wetness; indirect evaluation of wetness, based on the dew point calculated after the output of temperature and relative humidity sensors and direct measurements by means of capacitive wetness sensors, safety sensors, rain sensors (also known as leaf wetness sensors), infrared reflection sensors and fibre optic sensors. A comparison between the different methods is presented, specifying physical principles, forms of wetting to which they are respondent (i.e. condensation, ice melting, splashing drops, percolation and capillary rise), critical factors, use and cost.

Effects of climate on numbers of northern prairie wetlands

USGS Publications Warehouse

Larson, Diane L.

1995-01-01

The amount of water held in individual wetland basins depends not only on local climate patterns but also on groundwater flow regime, soil permeability, and basin size. Most wetland basins in the northern prairies hold water in some years and are dry in others. To assess the potential effect of climate change on the number of wetland basins holding water in a given year, one must first determine how much of the variability in number of wet basins is accounted for by climatic variables. I used multiple linear regression to examine the relationship between climate variables and percentage of wet basins throughout the Prairie Pothole Region of Canada and the United States. The region was divided into three areas: parkland, Canadian grassland, and United States grassland (i.e., North Dakota and South Dakota). The models - which included variables for spring and fall temperature, yearly precipitation, the previous year's count of wet basins, and for grassland areas, the previous fall precipitation - accounted for 63 to 65% of the variation in the number of wet basins. I then explored the sensitivities of the models to changes in temperature and precipitation, as might be associated with increased greenhouse gas concentrations. Parkland wetlands are shown to be much more vulnerable to increased temperatures than are wetlands in either Canadian or United States grasslands. Sensitivity to increased precipitation did not vary geographically. These results have implications for waterfowl and other wildlife populations that depend on availability of wetlands in the parklands for breeding or during periods of drought in the southern grasslands.

Species interactions reverse grassland responses to changing climate.

PubMed

Suttle, K B; Thomsen, Meredith A; Power, Mary E

2007-02-02

Predictions of ecological response to climate change are based largely on direct climatic effects on species. We show that, in a California grassland, species interactions strongly influence responses to changing climate, overturning direct climatic effects within 5 years. We manipulated the seasonality and intensity of rainfall over large, replicate plots in accordance with projections of leading climate models and examined responses across several trophic levels. Changes in seasonal water availability had pronounced effects on individual species, but as precipitation regimes were sustained across years, feedbacks and species interactions overrode autecological responses to water and reversed community trajectories. Conditions that sharply increased production and diversity through 2 years caused simplification of the food web and deep reductions in consumer abundance after 5 years. Changes in these natural grassland communities suggest a prominent role for species interactions in ecosystem response to climate change.

A wet/wet differential pressure sensor for measuring vertical hydraulic gradient.

PubMed

Fritz, Brad G; Mackley, Rob D

2010-01-01

Vertical hydraulic gradient is commonly measured in rivers, lakes, and streams for studies of groundwater-surface water interaction. While a number of methods with subtle differences have been applied, these methods can generally be separated into two categories; measuring surface water elevation and pressure in the subsurface separately or making direct measurements of the head difference with a manometer. Making separate head measurements allows for the use of electronic pressure sensors, providing large datasets that are particularly useful when the vertical hydraulic gradient fluctuates over time. On the other hand, using a manometer-based method provides an easier and more rapid measurement with a simpler computation to calculate the vertical hydraulic gradient. In this study, we evaluated a wet/wet differential pressure sensor for use in measuring vertical hydraulic gradient. This approach combines the advantage of high-temporal frequency measurements obtained with instrumented piezometers with the simplicity and reduced potential for human-induced error obtained with a manometer board method. Our results showed that the wet/wet differential pressure sensor provided results comparable to more traditional methods, making it an acceptable method for future use.

Estimates of grassland biomass and turnover time on the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Xia, Jiangzhou; Ma, Minna; Liang, Tiangang; Wu, Chaoyang; Yang, Yuanhe; Zhang, Li; Zhang, Yangjian; Yuan, Wenping

2018-01-01

The grassland of the Tibetan Plateau forms a globally significant biome, which represents 6% of the world’s grasslands and 44% of China’s grasslands. However, large uncertainties remain concerning the vegetation carbon storage and turnover time in this biome. In this study, we quantified the pool size of both the aboveground and belowground biomass and turnover time of belowground biomass across the Tibetan Plateau by combining systematic measurements taken from a substantial number of surveys (i.e. 1689 sites for aboveground biomass, 174 sites for belowground biomass) with a machine learning technique (i.e. random forest, RF). Our study demonstrated that the RF model is effective tool for upscaling local biomass observations to the regional scale, and for producing continuous biomass estimates of the Tibetan Plateau. On average, the models estimated 46.57 Tg (1 Tg = 1012g) C of aboveground biomass and 363.71 Tg C of belowground biomass in the Tibetan grasslands covering an area of 1.32 × 106 km2. The turnover time of belowground biomass demonstrated large spatial heterogeneity, with a median turnover time of 4.25 years. Our results also demonstrated large differences in the biomass simulations among the major ecosystem models used for the Tibetan Plateau, largely because of inadequate model parameterization and validation. This study provides a spatially continuous measure of vegetation carbon storage and turnover time, and provides useful information for advancing ecosystem models and improving their performance.

Mapping Woody Plant Encroachment in Grassland Using Multiple Source Remote Sensing images: Case Study in Oklahoma

NASA Astrophysics Data System (ADS)

Wang, J.; Xiao, X.; Qin, Y.; Dong, J.; Zhang, G.; Zhang, Y.; Zou, Z.; Zhou, Y.; Wu, X.; Bajgain, R.

2015-12-01

Woody plant encroachment (mainly Juniperus virginiana, a coniferous evergreen tree) in the native grassland has been rapidly increasing in the U.S. Southern Great Plains, largely triggered by overgrazing domestic livestock, fire suppression, and changing rainfall regimes. Increasing dense woody plants have significant implications for local grassland ecosystem dynamics, such as carbon storage, soil nutrient availability, herbaceous forage production, livestock, watershed hydrology and wildlife habitats. However, very limited data are available about the spatio-temporal dynamics of woody plant encroachment to the native grassland at regional scale. Data from remotes sensing could potentially provide relevant information and improve the conversion of native grassland to woody plant encroachment. Previous studies on woody detection in grassland mainly conducted at rangeland scale using airborne or high resolution images, which is sufficient to monitor the dynamics of woody plant encroachment in local grassland. This study examined the potential of medium resolution images to detect the woody encroachment in tallgrass prairie. We selected Cleveland county, Oklahoma, US. as case study area, where eastern area has higher woody coverage than does the western area. A 25-m Phased Array Type L-band Synthetic Aperture Radar (PALSAR, N36W98) image was used to map the trees distributed in the grassland. Then, maximum enhanced vegetation index (EVI) and normalized difference vegetation index (NDVI) in the winter calculated from time-series Landsat images was used to identify the invaded woody species (Juniperus virginiana) through phenology-based algorithm. The resulting woody plant encroachment map was compared with the results extracted from the high resolution images provided by the National Agriculture Imagery Program (NAIP). Field photos were also used to validate the accuracy. These results showed that integrating PALSAR and Landsat had good performance to identify the

Soil organic carbon stock in grasslands: Effects of inorganic fertilizers, liming and grazing in different climate settings.

PubMed

Eze, Samuel; Palmer, Sheila M; Chapman, Pippa J

2018-06-12

Grasslands store about 34% of the global terrestrial carbon (C) and are vital for the provision of various ecosystem services such as forage and climate regulation. About 89% of this grassland C is stored in the soil and is affected by management activities but the effects of these management activities on C storage under different climate settings are not known. In this study, we synthesized the effects of fertilizer (nitrogen and phosphorus) application, liming and grazing regime on the stock of SOC in global grasslands, under different site specific climatic settings using a meta-analysis of 341 datasets. We found an overall significant reduction (-8.5%) in the stock of SOC in global managed grasslands, mainly attributable to grazing (-15.0%), and only partially attenuated by fertilizer addition (+6.7%) and liming (+5.8%), indicating that management to improve biomass production does not contribute sufficient organic matter to replace that lost by direct removal by animals. Management activities had the greatest effect in the tropics (-22.4%) due primarily to heavy grazing, and the least effect in the temperate zone (-4.5%). The negative management effect reduced significantly with increasing mean annual temperature and mean annual precipitation in the temperate zone, suggesting that temperate grassland soils are potential C sinks in the face of climate change. For a sustainable management of grasslands that will provide adequate forage for livestock and mitigate climate change through C sequestration, we recommend that future tropical grassland management policies should focus on reducing the intensity of grazing. Also, to verify our findings for temperate grasslands and to better inform land management policy, future research should focus on the impacts of the projected climate change on net greenhouse gas exchange and potential climate feedbacks. Copyright © 2018 Elsevier Ltd. All rights reserved.

Testing functional trait-based mechanisms underpinning plant responses to grazing and linkages to ecosystem functioning in grasslands

NASA Astrophysics Data System (ADS)

Zheng, S. X.; Li, W. H.; Lan, Z. C.; Ren, H. Y.; Wang, K. B.; Bai, Y. F.

2014-09-01

Abundant evidence has shown that grazing alters plant functional traits, ecological strategies, community structure, and ecosystem functioning of grasslands. Few studies, however, have examined how plant responses to grazing are mediated by resource availability and functional group identity. We test functional trait-based mechanisms underlying the responses of different life forms to grazing and linkages to ecosystem functioning along a soil moisture gradient in the Inner Mongolia grassland. A principal component analysis (PCA) based on 9 traits × 276 species matrix showed that the plant size spectrum (i.e., individual biomass), leaf economics spectrum (leaf N content and leaf density), and light competition spectrum (height and stem-leaf biomass ratio) distinguished plant species responses to grazing. The three life forms exhibited differential strategies as indicated by trait responses to grazing. The annuals and biennials adopted grazing-tolerant strategies associated with high growth rate, reflected by high leaf N content and specific leaf area. The perennial grasses exhibited grazing-tolerant strategies associated with great regrowth capacity and high palatability scores, whereas perennial forbs showed grazing-avoidant strategies with short stature and low palatability scores. In addition, the dominant perennial bunchgrasses exhibited mixed tolerance-resistance strategies to grazing and mixed acquisitive-conservative strategies in resource utilization. Grazing increased the relative abundance of perennial forbs with low palatability in the wet and fertile meadow, but it promoted perennial grasses with high palatability in the dry and infertile typical steppe. Our findings suggest that the effects of grazing on plant functional traits are dependent on both the abiotic (e.g., soil moisture) and biotic (e.g., plant functional group identity and composition) factors. Grazing-induced shifts in functional group composition are largely dependent on resource

Nitrogen fertilizer replacement value of cattle slurry in grassland as affected by method and timing of application.

PubMed

Lalor, S T J; Schröder, J J; Lantinga, E A; Oenema, O; Kirwan, L; Schulte, R P O

2011-01-01

Slurry application with methods such as trailing shoe (TS) results in reduced emissions of ammonia (NH3) compared with broadcast application using splashplate (SP). Timing the application during cool and wet weather conditions also contributes to low NH3 emissions. From this perspective, we investigated whether reduced NH3 emissions due to improved slurry application method and timing results in an increase in the nitrogen (N) fertilizer replacement value (NFRV). The effects of application timing (June vs. April) and application method (TS vs. SP) on the apparent N recovery (ANR) and NFRV from cattle slurry applied to grassland were examined on three sites over 3 yr in randomized block experiments. The NFRV was calculated using two methods: (i) NFRV(N) based on the ANR of slurry N relative to mineral N fertilizer; and (ii) NFRV(DM) based on DM yield. The TS method increased the ANR, NFRV(N), and NFRV(DM) compared with SP in the 40- to 50-d period following slurry application by 0.09, 0.10, and 0.10 kg kg(-1), respectively. These values were reduced to 0.07, 0.06, and 0.05 kg kg(-1), respectively, when residual harvests during the rest of the year were included. The highest NFRV(DM) for the first harvest period was with application in April using STS (0.30 kg kg(-1)), while application in June with SP had the Slowest (0.12 kg kg(-1)). The highest NFRV(DM) for the cumulative harvest period was with application in April using TS (0.38 kg kg(-1)), while application in June with SP had the lowest (0.17 kg kg(-1)). Improved management of application method, by using TS instead of SP, and timing, by applying slurry in April rather than June, offer potential to increase the NFRV(DM) of cattle slurry applied to grassland.

Grassland Aboveground Biomass in Inner Mongolia: Dynamics (2001-2016) and Driving force

NASA Astrophysics Data System (ADS)

Li, F.; Zeng, Y.; Chen, J.; Wu, B.

2017-12-01

Plant biomass is the most critical measure of carbon stored in an ecosystem, yet it remains imprecisely modeled for many terrestrial biomes. This lack of modeling capacity for biomass and its change through time and space has impeded scientists from making headway concerning issues in the geographic and social sciences. Satellite remote sensing techniques excel at detecting changes in the Earth's surface; however, accurate estimates of biomass for the heterogeneous biome landscapes based on remote sensing techniques are few and far between, which has led to many repetitive studies. Here, we argued that our ability to assess biomass in a heterogeneous landscape using satellite remote sensing techniques would be effectively enhanced through a stratification of landscapes, i.e homogenizing landscapes. Specifically, above-ground biomass (AGB) for an extended heterogeneous grassland biome over the entirety of Inner Mongolia during the past 16 years (2001-2016) was explored using remote sensing time series data from the Moderate Resolution Imaging Spectroradiometer (MODIS). Massive and extensive in-situ measurement AGB data and pure vegetation index (PVI) models, developed from normal remote sensing vegetation indices such as the normalized difference vegetation index (NDVI) and the enhanced vegetation index (EVI), were highlighted in the accomplishment of this study. Taking into full consideration the landscape heterogeneity for the grassland biome over Inner Mongolia, we achieved a series of AGB models with high R2 (>0.85) and low RMSE ( 20.85 g/m2). The total average amount of fresh AGB for the entirety of Inner Mongolia grasslands over the past 16 years was estimated as 87 Tg with an inter-annual standard deviation of 9 Tg. Overall, the grassland AGB for Inner Mongolia increased sporadically. We found that the dynamics of AGB in the grassland biome of Inner Mongolia were substantially dominated by variation in precipitation despite the accommodation of a huge

Assessment of soil water, carbon and nitrogen cycling in reseeded grassland on the North Wyke Farm Platform using a process-based model.

PubMed

Li, Yuefen; Liu, Yi; Harris, Paul; Sint, Hadewij; Murray, Phil J; Lee, Michael R F; Wu, Lianhai

2017-12-15

The North Wyke Farm Platform (NWFP) generates large volumes of temporally-indexed data that provides a valuable test-bed for agricultural mathematical models in temperate grasslands. In our study, we used the primary datasets generated from the NWFP (https://nwfp.rothamsted.ac.uk/) to validate the SPACSYS model in terms of the dynamics of water loss and forage dry matter yield estimated through cutting. The SPACSYS model is capable of simulating soil water, carbon (C) and nitrogen (N) balance in the soil-plant-atmosphere system. The validated model was then used to simulate the responses of soil water, C and N to reseeding grass cultivars with either high sugar (Lolium perenne L. cv. AberMagic) or deep rooting (Festulolium cv. Prior) traits. Simulation results demonstrated that the SPACSYS model could predict reliably soil water, C and N cycling in reseeded grassland. Compared to AberMagic, the Prior grass could fix more C in the second year following reseeding, whereas less C was lost through soil respiration in the first transition year. In comparison to the grass cultivar of the permanent pasture that existed before reseeding, both grasses reduced N losses through runoff and contributed to reducing water loss, especially Prior in relation to the latter. The SPACSYS model could predict these differences as supported by the rich dataset from the NWFP, providing a tool for future predictions on less characterized pasture. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Method of Grassland Information Extraction Based on Multi-Level Segmentation and Cart Model

NASA Astrophysics Data System (ADS)

Qiao, Y.; Chen, T.; He, J.; Wen, Q.; Liu, F.; Wang, Z.

2018-04-01

It is difficult to extract grassland accurately by traditional classification methods, such as supervised method based on pixels or objects. This paper proposed a new method combing the multi-level segmentation with CART (classification and regression tree) model. The multi-level segmentation which combined the multi-resolution segmentation and the spectral difference segmentation could avoid the over and insufficient segmentation seen in the single segmentation mode. The CART model was established based on the spectral characteristics and texture feature which were excavated from training sample data. Xilinhaote City in Inner Mongolia Autonomous Region was chosen as the typical study area and the proposed method was verified by using visual interpretation results as approximate truth value. Meanwhile, the comparison with the nearest neighbor supervised classification method was obtained. The experimental results showed that the total precision of classification and the Kappa coefficient of the proposed method was 95 % and 0.9, respectively. However, the total precision of classification and the Kappa coefficient of the nearest neighbor supervised classification method was 80 % and 0.56, respectively. The result suggested that the accuracy of classification proposed in this paper was higher than the nearest neighbor supervised classification method. The experiment certificated that the proposed method was an effective extraction method of grassland information, which could enhance the boundary of grassland classification and avoid the restriction of grassland distribution scale. This method was also applicable to the extraction of grassland information in other regions with complicated spatial features, which could avoid the interference of woodland, arable land and water body effectively.

Multi-scale models of grassland passerine abundance in a fragmented system in Wisconsin

USGS Publications Warehouse

Renfrew, R.B.; Ribic, C.A.

2008-01-01

Fragmentation of grasslands has been implicated in grassland bird population declines. Multi-scale models are being increasingly used to assess potential factors that influence grassland bird presence, abundance, and productivity. However, studies rarely assess fragmentation metrics, and seldom evaluate more than two scales or interactions among scales. We evaluated the relative importance of characteristics at multiple scales to patterns in relative abundance of Savannah Sparrow (Passerculus sandwichensis), Grasshopper Sparrow (Ammodramus savannarum), Eastern Meadowlark (Sturnella magna), and Bobolink (Dolichonyx oryzivorus). We surveyed birds in 74 southwestern Wisconsin pastures from 1997 to 1999 and compared models with explanatory variables from multiple scales: within-patch vegetation structure (microhabitat), patch (macrohabitat), and three landscape extents. We also examined interactions between macrohabitat and landscape factors. Core area of pastures was an important predictor of relative abundance, and composition of the landscape was more important than configuration. Relative abundance was frequently higher in pastures with more core area and in landscapes with more grassland and less wooded area. The direction and strength of the effect of core pasture size on relative abundance changed depending on amount of wooded area in the landscape. Relative abundance of grassland birds was associated with landscape variables more frequently at the 1200-m scale than at smaller scales. To develop better predictive models, parameters at multiple scales and their interactive effects should be included, and results should be evaluated in the context of microhabitat variability, landscape composition, and fragmentation in the study area. ?? 2007 Springer Science+Business Media B.V.

Wetting of cholesteric liquid crystals.

PubMed

Silvestre, Nuno M; Figueirinhas Pereira, Maria Carolina; Bernardino, Nelson R; Telo da Gama, Margarida M

2016-02-01

We investigate theoretically the wetting properties of cholesteric liquid crystals at a planar substrate. If the properties of substrate and of the interface are such that the cholesteric layers are not distorted, the wetting properties are similar to those of a nematic liquid crystal. If, on the other hand, the anchoring conditions force the distortion of the liquid crystal layers the wetting properties are altered, the free cholesteric-isotropic interface is non-planar and there is a layer of topological defects close to the substrate. These deformations can either promote or hinder the wetting of the substrate by a cholesteric, depending on the properties of the cholesteric liquid crystal.

Influence of management and precipitation on carbon fluxes in greatplains grasslands

USGS Publications Warehouse

Rigge, Matthew B.; Wylie, Bruce K.; Zhang, Li; Boyte, Stephen P.

2013-01-01

Suitable management and sufficient precipitation on grasslands can provide carbon sinks. The net carbon accumulation of a site from the atmosphere, modeled as the Net Ecosystem Productivity (NEP), is a useful means to gauge carbon balance. Previous research has developed methods to integrate flux tower data with satellite biophysical datasets to estimate NEP across large regions. A related method uses the Ecosystem Performance Anomaly (EPA) as a satellite-derived indicator of disturbance intensity (e.g., livestock stocking rate, fire, and insect damage). To better understand the interactions among management, climate, and carbon dynamics, we evaluated the relationship between EPA and NEP data at the 250 m scale for grasslands in the Central Great Plains, USA (ranging from semi-arid to mesic). We also used weekly estimates of NEP to evaluate the phenology of carbon dynamics, classified by EPA (i.e., by level of disturbance impact). Results show that the cumulative carbon balance over these grasslands from 2000 to 2008 was a weak net sink of 13.7 g C m−2 yr−1. Overall, NEP increased with precipitation (R2 = 0.39, P < 0.05) from west to east. Disturbance influenced NEP phenology; however, climate and biophysical conditions were usually more important. The NEP response to disturbance varies by ecoregion, and more generally by grassland type, where the shortgrass prairie NEP is most sensitive to disturbance, the mixed-grass prairie displays a moderate response, and tallgrass prairie is the least impacted by disturbance (as measured by EPA). Sustainable management practices in the tallgrass and mixed-grass prairie may potentially induce a period of average net carbon sink until a new equilibrium soil organic carbon is achieved. In the shortgrass prairie, management should be considered sustainable if carbon stocks are simply maintained. The consideration of site carbon balance adds to the already difficult task of managing grasslands appropriately to site conditions

Grassland bird productivity in warm season grass fields in southwest Wisconsin

USGS Publications Warehouse

Byers, Carolyn M.; Ribic, Christine; Sample, David W.; Dadisman, John D.; Guttery, Michael

2017-01-01

Surrogate grasslands established through federal set-aside programs, such as U.S. Department of Agriculture's Conservation Reserve Program (CRP), provide important habitat for grassland birds. Warm season grass CRP fields as a group have the potential for providing a continuum of habitat structure for breeding birds, depending on how the fields are managed and their floristic composition. We studied the nesting activity of four obligate grassland bird species, Bobolink (Dolichonyx oryzivorus), Eastern Meadowlark (Sturnella magna), Grasshopper Sparrow (Ammodramus savannarum), and Henslow's Sparrow (A. henslowii), in relation to vegetative composition and fire management in warm season CRP fields in southwest Wisconsin during 2009–2011. Intraspecific variation in apparent nest density was related to the number of years since the field was burned. Apparent Grasshopper Sparrow nest density was highest in the breeding season immediately following spring burns, apparent Henslow's Sparrow nest density was highest 1 y post burn, and apparent Bobolink and Eastern Meadowlark nest densities were higher in post fire years one to three. Grasshopper Sparrow nest density was highest on sites with more diverse vegetation, specifically prairie forbs, and on sites with shorter less dense vegetation. Bobolink, Eastern Meadowlark, and Henslow's Sparrow apparent nest densities were higher on sites with deeper litter; litter was the vegetative component that was most affected by spring burns. Overall nest success was 0.487 for Bobolink (22 d nesting period), 0.478 for Eastern Meadowlark (25 d nesting period), 0.507 for Grasshopper Sparrow (22 d nesting period), and 0.151 for Henslow's Sparrow (21 d nesting period). The major nest predators were grassland-associated species: thirteen-lined ground squirrel (Ictidomys tridecemlineatus), striped skunk (Mephitis mephitis), milk snake (Lampropeltis triangulum), American badger (Taxidea taxus), and western fox snake (Elaphe vulpina). Overall

Modeling vegetation and carbon dynamics of managed grasslands at the global scale with LPJmL 3.6

NASA Astrophysics Data System (ADS)

Rolinski, Susanne; Müller, Christoph; Heinke, Jens; Weindl, Isabelle; Biewald, Anne; Bodirsky, Benjamin Leon; Bondeau, Alberte; Boons-Prins, Eltje R.; Bouwman, Alexander F.; Leffelaar, Peter A.; te Roller, Johnny A.; Schaphoff, Sibyll; Thonicke, Kirsten

2018-02-01

Grassland management affects the carbon fluxes of one-third of the global land area and is thus an important factor for the global carbon budget. Nonetheless, this aspect has been largely neglected or underrepresented in global carbon cycle models. We investigate four harvesting schemes for the managed grassland implementation of the dynamic global vegetation model (DGVM) Lund-Potsdam-Jena managed Land (LPJmL) that facilitate a better representation of actual management systems globally. We describe the model implementation and analyze simulation results with respect to harvest, net primary productivity and soil carbon content and by evaluating them against reported grass yields in Europe. We demonstrate the importance of accounting for differences in grassland management by assessing potential livestock grazing densities as well as the impacts of grazing, grazing intensities and mowing systems on soil carbon stocks. Grazing leads to soil carbon losses in polar or arid regions even at moderate livestock densities (< 0.4 livestock units per hectare - LSU ha-1) but not in temperate regions even at much higher densities (0.4 to 1.2 LSU ha-1). Applying LPJmL with the new grassland management options enables assessments of the global grassland production and its impact on the terrestrial biogeochemical cycles but requires a global data set on current grassland management.

Soil Greenhouse Gas Fluxes, Environmental Controls, and the Partitioning of N2O Sources in UK Natural and Seminatural Land Use Types

NASA Astrophysics Data System (ADS)

Sgouridis, Fotis; Ullah, Sami

2017-10-01

Natural and seminatural terrestrial ecosystems (unmanaged peatlands and forests and extensive and intensive grasslands) have been under-represented in the UK greenhouse gas (GHG) inventory. Mechanistic studies of GHG fluxes and their controls can improve the prediction of the currently uncertain GHG annual emission estimates. The source apportionment of N2O emissions can further inform management plans for GHG mitigation. We have measured in situ GHG fluxes monthly in two replicated UK catchments and evaluated their environmental controlling factors. An adapted 15N-gas flux method with low addition of 15N tracer (0.03-0.5 kg 15N ha-1) was used to quantify the relative contribution of denitrification to net N2O production. Total N2O fluxes were 40 times higher in the intensive grasslands than in the peatlands (range: -1.32 to 312.3 μg N m-2 h-1). The contribution of denitrification to net N2O emission varied across the land use types and ranged from 9 to 60%. Soil moisture was the key parameter regulating the partitioning of N2O sources (r2 = 0.46). Total N2O fluxes were explained by a simple model (r2 = 0.83) including parameters such as total dissolved nitrogen, organic carbon, and water content. A parsimonious model with the soil moisture content as a single scalar parameter explained 84% of methane flux variability across land uses. The assumption that 1% of the atmospherically deposited N on natural ecosystems is emitted as N2O could be overestimated or underestimated (0.3-1.6%). The use of land use-specific N2O emission factors and further information on N2O source partitioning should help constrain this uncertainty.

Grazing effects on soil characteristics and vegetation of grassland in northern China

NASA Astrophysics Data System (ADS)

Wang, Z.; Johnson, D. A.; Rong, Y.; Wang, K.

2016-01-01

Large areas of grassland in the agro-pastoral region of northern China were converted into cropland for grain production, and the remaining grasslands are being overgrazed and seriously degraded. The objective of this study was to evaluate how reductions in grazing intensity affect the soil and vegetation characteristics in grasslands of northern China. Soil heterogeneity and vegetation characteristics were evaluated for ungrazed (UG), moderate grazing (MG), and heavy grazing (HG) sites. Grazing increased diversity, but heavy grazing decreased aboveground biomass and increased the non-grass component. The non-grass proportion of total biomass increased with grazing intensity, which was 8, 16 and 48 % for UG, MG and HG sites, respectively. Species richness at the MG and HG sites was significantly higher than at the UG site (P< 0.05) with 3.6, 5.5 and 5.7 for UG, MG and HG sites, respectively. Strong spatial dependence of the examined soil properties at 10 m scale for all grazed sites was revealed by the ratio of nugget to total variation (0-23 %). Overgrazing homogenized soil characteristics at a 10 m scale. The ranges of spatial autocorrelation for soil organic C (SOC) and total N were both > 120 m at the HG site, which was considerably larger than that at the MG and UG sites with corresponding distances of 17.3 and 20.8 m for the MG site and 8.6 and 15.0 m for the UG site, respectively. The sampling density and sampling space for the HG site could be decreased under this scale sampling interval (10 m). Therefore, MG was recommended as the preferred management alternative for grasslands in northern China because of increased plant diversity without negative consequences related to decreased forage quality, forage quantity and soil heterogeneity for the investigated soil properties in northern China's grasslands.

Vascular plants and a brief history of the Kiowa and Rita Blanca National Grasslands

Treesearch

Donald L. Hazlett; Michael H. Schiebout; Paulette L. Ford

2009-01-01

Administered by the USDA Forest Service, the Kiowa and Rita Blanca National Grasslands occupy 230,000 acres of public land extending from northeastern New Mexico into the panhandles of Oklahoma and Texas. A mosaic of topographic features including canyons, plateaus, rolling grasslands and outcrops supports a diverse flora. Eight hundred twenty six (826) species of...

Spatial and temporal patterns of water availability in a grass-shrub ecotone and implications for grassland recovery in arid environments

USDA-ARS?s Scientific Manuscript database

Encroachment of woody shrubs into historic desert grasslands is a major problem throughout the world. Conversion of grasslands to shrub-dominated systems may result in significant alteration of biogeochemical processes and reduced resource availability in shrub interspaces, making grassland recover...

An Introduction to ESERO-UK, the UK Space Education Office

ERIC Educational Resources Information Center

Clements, Allan; Mather, Edward

2012-01-01

This article introduces the UK branch of the European Space Education Resource Office (ESERO-UK), also known as the UK Space Education Office. It is a teaching project designed to use space to enthuse primary and secondary students to study science, technology, engineering and mathematics (STEM) subjects. The office is funded by the European Space…

Impacts of biomass production at civil airports on grassland bird conservation and aviation strike risk.

PubMed

Conkling, Tara J; Belant, Jerrold L; DeVault, Travis L; Martin, James A

2018-03-08

Growing concerns about climate change, foreign oil dependency, and environmental quality have fostered interest in perennial native grasses (e.g., switchgrass [Panicum virgatum]) for bioenergy production while also maintaining biodiversity and ecosystem function. However, biomass cultivation in marginal landscapes such as airport grasslands may have detrimental effects on aviation safety as well as conservation efforts for grassland birds. In 2011-2013, we investigated effects of vegetation composition and harvest frequency on seasonal species richness and habitat use of grassland birds and modeled relative abundance, aviation risk, and conservation value of birds associated with biomass crops. Avian relative abundance was greater in switchgrass monoculture plots during the winter months, whereas Native Warm-Season Grass (NWSG) mixed species plantings were favored by species during the breeding season. Conversely, treatment differences in aviation risk and conservation value were not biologically significant. Only 2.6% of observations included avian species of high hazard to aircraft, providing support for semi-natural grasslands as a feasible landcover option at civil airports. Additionally, varied harvest frequencies across a mosaic of switchgrass monocultures and NWSG plots allows for biomass production with multiple vegetation structure options for grassland birds to increase seasonal avian biodiversity and habitat use. © 2018 by the Ecological Society of America.

Land use in mountain grasslands alters drought response and recovery of carbon allocation and plant-microbial interactions.

PubMed

Karlowsky, Stefan; Augusti, Angela; Ingrisch, Johannes; Hasibeder, Roland; Lange, Markus; Lavorel, Sandra; Bahn, Michael; Gleixner, Gerd

2018-05-01

Mountain grasslands have recently been exposed to substantial changes in land use and climate and in the near future will likely face an increased frequency of extreme droughts. To date, how the drought responses of carbon (C) allocation, a key process in the C cycle, are affected by land-use changes in mountain grassland is not known.We performed an experimental summer drought on an abandoned grassland and a traditionally managed hay meadow and traced the fate of recent assimilates through the plant-soil continuum. We applied two 13 CO 2 pulses, at peak drought and in the recovery phase shortly after rewetting.Drought decreased total C uptake in both grassland types and led to a loss of above-ground carbohydrate storage pools. The below-ground C allocation to root sucrose was enhanced by drought, especially in the meadow, which also held larger root carbohydrate storage pools.The microbial community of the abandoned grassland comprised more saprotrophic fungal and Gram(+) bacterial markers compared to the meadow. Drought increased the newly introduced AM and saprotrophic (A+S) fungi:bacteria ratio in both grassland types. At peak drought, the 13 C transfer into AM and saprotrophic fungi, and Gram(-) bacteria was more strongly reduced in the meadow than in the abandoned grassland, which contrasted the patterns of the root carbohydrate pools.In both grassland types, the C allocation largely recovered after rewetting. Slowest recovery was found for AM fungi and their 13 C uptake. In contrast, all bacterial markers quickly recovered C uptake. In the meadow, where plant nitrate uptake was enhanced after drought, C uptake was even higher than in control plots. Synthesis . Our results suggest that resistance and resilience (i.e. recovery) of plant C dynamics and plant-microbial interactions are negatively related, that is, high resistance is followed by slow recovery and vice versa. The abandoned grassland was more resistant to drought than the meadow and possibly had a

78 FR 56650 - Medicine Bow-Routt National Forests and Thunder Basin National Grassland; Wyoming; Thunder Basin...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-13

... National Grassland; Wyoming; Thunder Basin National Grassland Prairie Dog Amendment AGENCY: Forest Service... 2009 Prairie Dog Management Strategy. The amendment is being proposed to address continuing concerns regarding prairie dog management, raised by the [[Page 56651

Cathode Wetting Studies in Magnesium Electrolysis

NASA Astrophysics Data System (ADS)

McLean, Kevin; Pettingill, James; Davis, Boyd

The effects of cathode materials and electrolyte additives on magnesium wetting were studied with the goal of improving current efficiency in a magnesium electrolysis cell. The study consisted of static wetting and electrolysis tests, both conducted in a visual cell with a molten salt electrolyte of MgCl2-CaCl2-NaCl-KCl-CaF2. The wetting conditions were tested using high resolution photography and contact angle software. The electrolysis tests were completed to qualitatively assess the effect of additives to the melt and were recorded with a digital video camcorder. Results from the static wetting tests showed a significant variation in wetting depending on the material used for the cathode. Mo and a Mo-W alloy, with contact angles of 60° and 52° respectively, demonstrated excellent wetting. The contact angle for steel was 132° and it ranged from 142°-154° for graphite depending on the type. Improvements to the cathode wetting were observed with tungsten and molybdenum oxide additives.

Temporal patterns of vegetation phenology and their responses to climate change in mid-latitude grasslands of the Northern Hemisphere

NASA Astrophysics Data System (ADS)

Ren, S.; Chen, X.; Qin, Q.; Zhang, Y.; Wu, Z.

2017-12-01

Grassland ecosystem is greatly sensitive to regional and global climate changes. In this study, the start (SOS) and end (EOS) date of growing season were extracted from NDVI data (1981 2014) across the mid-latitude (30°N 55°N) grasslands of Northern Hemisphere. We first validated their accuracy by ground observed phenological data and phenological metrics derived from gross primary production (GPP) data. And then, main climatic factors influencing the temporal patterns of SOS/EOS were explored by means of gridded meteorological data and partial correlation analysis. Based on the results of above statistical analysis, the similarities and differences of spring and autumn phenological responses to climate change among North American grasslands, Mid-West Asian grasslands, and Mongolian grasslands were analyzed. The main results and conclusions are as follows. First, a significant positive correlation was found between SOS/EOS and observed green-up/brown-off date (P<0.05) and GPP-based SOS/EOS (P<0.05), which means remote sensed SOS/EOS can reflect temporal dynamics of terrestrial vegetation phenology. Second, SOS in Mid-West Asian grasslands showed a significant advancing trend (0.22 days/year, P<0.01), whereas the trend of SOS in North American grasslands and Mongolian grasslands was not significant. EOS in North American grasslands (0.31 dyas/year, P<0.01) and Mongolian grasslands (0.09 days/year, P<0.05) both presented a significant delaying trend, but the trend of EOS in Mid-West Asian grasslands was not significant. Furthermore, the correlation analysis of SOS/EOS inter-annual fluctuations and hydrothermal factors showed that a significant negative correlation was found between SOS and the pre-season temperature in 41.6% of pixels (P<0.05), while a significant negative/positive correlation was detected between SOS and pre-season rainfall/snowfall in 14.6%/19.0% of pixels (P<0.05). EOS was significantly positively correlated with pre-season rainfall in 34.5% of

Trapping the Pasture Odorscape Using Open-Air Solid-Phase Micro Extraction, a Tool to Assess Grassland Value.

PubMed

Cornu, Agnès; Farruggia, Anne; Leppik, Ene; Pinier, Centina; Fournier, Florence; Genoud, David; Frérot, Brigitte

2015-01-01

Besides supporting cattle feeding, grasslands are home to a diversity of plants and insects that interact with each other by emitting volatile compounds. The aim of this work was to develop a method to determine permanent grassland odorscape and relate it to flower-visiting insects. Two grasslands were chosen for their contrasting levels of botanical diversity, resulting from differing grazing managements. Measurements were made over two periods of three consecutive days at the beginning of grazing, and just after the cows had left the plots. Volatile compounds were trapped using solid-phase microextraction (SPME) fibers exposed eight hours a day in three exclosures per plot, and then analyzed by gas-chromatography-mass spectrometry (GC-MS). Insects were trapped using pan traps and a net, sorted and counted. The open air SPME method yielded volatile compound profiles that were richer than maize field profiles, comprising the common green leaf volatiles (GLV) and more specific ones. Differences between the odorscapes of the two grasslands were found, but they were not as marked as expected from their botanical composition. By contrast, there were sharp differences between the two periods, resulting from the combined effects of changes in weather conditions, plant phenological stage and grazing progress. Several correlations between insect counts and volatile compounds were found. Although their correlation coefficients were low, some of them were confirmed when tested by Spearman rank correlation, and could be logically explained. This method of grassland odorscape deserves to be developed because it can provide information on many aspects of grassland function and on the stresses that grassland plants undergo.

Molecular markers for addressing the genetic consequences of fragmentation on black grama (Bouteloua eriopoda) grasslands

USDA-ARS?s Scientific Manuscript database

Grasses and grasslands are among the most important biological systems on the planet, providing habitat for wildlife, forage for grazers, and grain for animal and human consumption. Bouteloua eriopoda (black grama) is a key species of the grasslands that once covered large parts of the Northern Chi...

Does the aboveground herbivore assemblage influence soil bacterial community composition and richness in subalpine grasslands?

Treesearch

Melanie Hodel; Martin Schütz; Martijn L. Vandegehuchte; Beat Frey; Matthias Albrecht; Matt D. Busse; Anita C. Risch

2014-01-01

Grassland ecosystems support large communities of aboveground herbivores that can alter ecosystem processes. Thus, grazing by herbivores can directly and indirectly affect belowground properties such as the microbial community structure and diversity. Even though multiple species of functionally different herbivores coexist in grassland ecosystems, most studies have...

Spatio-temporal patterns and climate variables controlling of biomass carbon stock of global grassland ecosystems from 1982 to 2006

USGS Publications Warehouse

Xia, Jiangzhou; Liu, Shuguang; Liang, Shunlin; Chen, Yang; Xu, Wenfang; Yuan, Wenping

2014-01-01

Grassland ecosystems play an important role in subsistence agriculture and the global carbon cycle. However, the global spatio-temporal patterns and environmental controls of grassland biomass are not well quantified and understood. The goal of this study was to estimate the spatial and temporal patterns of the global grassland biomass and analyze their driving forces using field measurements, Normalized Difference Vegetation Index (NDVI) time series from satellite data, climate reanalysis data, and a satellite-based statistical model. Results showed that the NDVI-based biomass carbon model developed from this study explained 60% of the variance across 38 sites globally. The global carbon stock in grassland aboveground live biomass was 1.05 Pg·C, averaged from 1982 to 2006, and increased at a rate of 2.43 Tg·C·y−1 during this period. Temporal change of the global biomass was significantly and positively correlated with temperature and precipitation. The distribution of biomass carbon density followed the precipitation gradient. The dynamics of regional grassland biomass showed various trends largely determined by regional climate variability, disturbances, and management practices (such as grazing for meat production). The methods and results from this study can be used to monitor the dynamics of grassland aboveground biomass and evaluate grassland susceptibility to climate variability and change, disturbances, and management.

Nest success of grassland birds in oak barrens and dry prairies in west central Wisconsin

USGS Publications Warehouse

Susan M. Vos,; Ribic, Christine

2013-01-01

We investigated nesting success of grassland birds on dry prairie and oak barrens patches embedded within a forested matrix on Fort McCoy Military Installation. We monitored 280 nests of 9 grassland-bird species from mid-May to late July 2000–2002. Pooecetes gramineus (Vesper Sparrow) andAmmodramus savannarum (Grasshopper Sparrow) were the most abundant nesting species. Vesper Sparrow nest densities were highest on smaller grassland patches, while Grasshopper Sparrow nest densities were highest on the largest patches. Probability of fledging at least one young was 0.20 for Vesper Sparrow. For Grasshopper Sparrow, daily nest survival was higher for nests placed away from trees; probability of fledging at least one young was 0.28 for nests away from trees and 0.05 for nests near trees. Maintaining remnant native habitats is important, and management of woody features may help improve habitat quality for some grassland birds in Wisconsin.

Phenological responses of Icelandic subarctic grasslands to short-term and long-term natural soil warming.

PubMed

Leblans, Niki I W; Sigurdsson, Bjarni D; Vicca, Sara; Fu, Yongshuo; Penuelas, Josep; Janssens, Ivan A

2017-11-01

The phenology of vegetation, particularly the length of the growing season (LOS; i.e., the period from greenup to senescence), is highly sensitive to climate change, which could imply potent feedbacks to the climate system, for example, by altering the ecosystem carbon (C) balance. In recent decades, the largest extensions of LOS have been reported at high northern latitudes, but further warming-induced LOS extensions may be constrained by too short photoperiod or unfulfilled chilling requirements. Here, we studied subarctic grasslands, which cover a vast area and contain large C stocks, but for which LOS changes under further warming are highly uncertain. We measured LOS extensions of Icelandic subarctic grasslands along natural geothermal soil warming gradients of different age (short term, where the measurements started after 5 years of warming and long term, i.e., warmed since ≥50 years) using ground-level measurements of normalized difference vegetation index. We found that LOS linearly extended with on average 2.1 days per °C soil warming up to the highest soil warming levels (ca. +10°C) and that LOS had the potential to extend at least 1 month. This indicates that the warming impact on LOS in these subarctic grasslands will likely not saturate in the near future. A similar response to short- and long-term warming indicated a strong physiological control of the phenological response of the subarctic grasslands to warming and suggested that genetic adaptations and community changes were likely of minor importance. We conclude that the warming-driven extension of the LOSs of these subarctic grasslands did not saturate up to +10°C warming, and hence that growing seasons of high-latitude grasslands are likely to continue lengthening with future warming (unless genetic adaptations or species shifts do occur). This persistence of the warming-induced extension of LOS has important implications for the C-sink potential of subarctic grasslands under climate

Difficulties of biomass estimation over natural grassland

NASA Astrophysics Data System (ADS)

Kertész, Péter; Gecse, Bernadett; Pintér, Krisztina; Fóti, Szilvia; Nagy, Zoltán

2017-04-01

Estimation of biomass amount in grasslands using remote sensing is a challenge due to the high diversity and different phenologies of the constituting plant species. The aim of this study was to estimate the biomass amount (dry weight per area) during the vegetation period of a diverse semi-natural grassland with remote sensing. A multispectral camera (Tetracam Mini-MCA 6) was used with 3 cm ground resolution. The pre-processing method includes noise reduction, the correction for the vignetting effect and the calculation of the reflectance using an Incident Light Sensor (ILS). Calibration was made with ASD spectrophotometer as reference. To estimate biomass Partial Least Squares Regression (PLSR) statistical method was used with 5 bands and NDVI as input variables. Above ground biomass was cut in 15 quadrats (50×50 cm) as reference. The best prediction was attained in spring (r2=0.94, RMSE: 26.37 g m-2). The average biomass amount was 167 g m-2. The variability of the biomass is mainly determined by the relief, which causes the high and low biomass patches to be stable. The reliability of biomass estimation was negatively affected by the appearance of flowers and by the senescent plant parts during the summer. To determine the effects of flower's presence on the biomass estimation, 20 dominant species with visually dominant flowers in the area were selected and cover of flowers (%) were estimated in permanent plots during measurement campaigns. If the cover of flowers was low (<25%), the biomass amount estimation was successful (r2 >0,9), while at higher cover of flowers (>30%), the estimation failed (r2 <0,2). This effect restricts the usage of the remote sensing method to the spring - early summer period in diverse grasslands.

Habitat fragmentation effects on birds in grasslands and wetlands: A critique of our knowledge

USGS Publications Warehouse

Johnson, D.H.

2001-01-01

Habitat fragmentation exacerbates the problem of habitat loss for grassland and wetland birds. Remaining patches of grasslands and wetlands may be too small, too isolated, and too influenced by edge effects to maintain viable populations of some breeding birds. Knowledge of the effects of fragmentation on bird populations is critically important for decisions about reserve design, grassland and wetland management, and implementation of cropland set-aside programs that benefit wildlife. In my review of research that has been conducted on habitat fragmentation, I found at least five common problems in the methodology used. The results of many studies are compromised by these problems: passive sampling (sampling larger areas in larger patches), confounding effects of habitat heterogeneity, consequences of inappropriate pooling of data from different species, artifacts associated with artificial nest data, and definition of actual habitat patches. As expected, some large-bodied birds with large territorial requirements, such as the northern harrier (Circus cyaneus), appear area sensitive. In addition, some small species of grassland birds favor patches of habitat far in excess of their territory size, including the Savannah (Passerculus sandwichensis), grasshopper (Ammodramus savannarum) and Henslow's (A. henslowii) sparrows, and the bobolink (Dolichonyx oryzivorus). Other species may be area sensitive as well, but the data are ambiguous. Area sensitivity among wetland birds remains unknown since virtually no studies have been based on solid methodologies. We need further research on grassland bird response to habitat that distinguishes supportable conclusions from those that may be artifactual.

Greenhouse gas exchange in grasslands: impacts of climate, intensity of management and other factors

NASA Astrophysics Data System (ADS)

Smith, K. A.

2003-04-01

Grasslands occupy some 40% of the terrestrial land surface. They are generally categorised as natural (occurring mainly in those regions where the rainfall is too low to support forest ecosystems), semi-natural (where management, mainly by grazing, has changed the vegetation composition), and artificial (where forests have been cleared to create new pasture land). The soils of the natural and semi-natural grasslands constitute a large reservoir of carbon, and make a substantial contribution to the soil sink for atmospheric CH_4. The conversion of much of the natural temperate grassland to arable agriculture, e.g. in North America and Europe, resulted in a considerable decrease in soil organic carbon, and its release to the atmosphere as CO_2 has made a substantial contribution to the total atmospheric concentration of this gas. The associated increase in cycling of soil N (released from the organic matter) will have contributed to N_2O emissions, and land disturbance and fertilisation has resulted in a depletion of the soil CH_4 sink. Conversion of tropical forests to pastures has also been a major source of CO_2, and these pastures show elevated emissions of N_2O for some years after conversion. Seasonally flooded tropical grasslands are a significant source of CH_4 emissions. Consideration of grassland ecosystems in their entirety, in relation to GHG exchange, necessitates the inclusion of CH_4 production by fauna - domesticated livestock and wild herbivores, as well as some species of termites - in the overall assessment. Stocking rates on pasture land have increased, and the total CH_4 emissions likewise. The relationship between animal production and CH_4 emissions is dependent on the nutritional quality of the vegetation, as well as on animal numbers. In both temperate and tropical regions, increased N inputs as synthetic fertilisers and manures (and increased N deposition) are producing possibly a more-than-linear response in terms of emissions of N_2O. In

Grassland and cropland net ecosystem production of the U.S. Great Plains: Regression tree model development and comparative analysis

USGS Publications Warehouse

Wylie, Bruce K.; Howard, Daniel; Dahal, Devendra; Gilmanov, Tagir; Ji, Lei; Zhang, Li; Smith, Kelcy

2016-01-01

This paper presents the methodology and results of two ecological-based net ecosystem production (NEP) regression tree models capable of up scaling measurements made at various flux tower sites throughout the U.S. Great Plains. Separate grassland and cropland NEP regression tree models were trained using various remote sensing data and other biogeophysical data, along with 15 flux towers contributing to the grassland model and 15 flux towers for the cropland model. The models yielded weekly mean daily grassland and cropland NEP maps of the U.S. Great Plains at 250 m resolution for 2000–2008. The grassland and cropland NEP maps were spatially summarized and statistically compared. The results of this study indicate that grassland and cropland ecosystems generally performed as weak net carbon (C) sinks, absorbing more C from the atmosphere than they released from 2000 to 2008. Grasslands demonstrated higher carbon sink potential (139 g C·m−2·year−1) than non-irrigated croplands. A closer look into the weekly time series reveals the C fluctuation through time and space for each land cover type.

Grassland bird communtiy response to large wildfires

USGS Publications Warehouse

Roberts, Anthony J.; Boal, Clint W.; Wester, David B.; Rideout-Hanzak, Sandra; Whitlaw, Heather A.

2012-01-01

We studied breeding season communities of grassland birds on short-grass and mixed-grass prairie sites during the second and third breeding seasons following two large wildfires in March 2006 in the Texas panhandle, USA. There was an apparent temporary shift in avian community composition following the fires due to species-specific shifts associated with life-history traits and vegetation preferences. Species that prefer sparse vegetation and bare ground on short-grass sites, such as Horned Lark (Eremophila alpestris), benefited from wildfires, while others, such as Western Meadowlark (Sturnella neglecta), that prefer more dense vegetation, were negatively impacted. Mixed-grass sites had species-specific shifts in 2007, two breeding seasons after the fires; grassland bird communities on burned plots were similar by 2008 to those on unburned plots. Avian communities appeared to return to pre-burn levels within 3 years following wildfires. Many of the responses in our study of wildfire were similar to those reported following prescribed fires elsewhere. Prescribed fires appear to have similar effects on the avian community despite differences in intensity and environmental conditions during wildfires.

Differential sensitivity to regional-scale drought in six central US grasslands.

PubMed

Knapp, Alan K; Carroll, Charles J W; Denton, Elsie M; La Pierre, Kimberly J; Collins, Scott L; Smith, Melinda D

2015-04-01

Terrestrial ecosystems often vary dramatically in their responses to drought, but the reasons for this are unclear. With climate change forecasts for more frequent and extensive drought in the future, a more complete understanding of the mechanisms that determine differential ecosystem sensitivity to drought is needed. In 2012, the Central US experienced the fourth largest drought in a century, with a regional-scale 40% reduction in growing season precipitation affecting ecosystems ranging from desert grassland to mesic tallgrass prairie. This provided an opportunity to assess ecosystem sensitivity to a drought of common magnitude in six native grasslands. We tested the prediction that drought sensitivity is inversely related to mean annual precipitation (MAP) by quantifying reductions in aboveground net primary production (ANPP). Long-term ANPP data available for each site (mean length = 16 years) were used as a baseline for calculating reductions in ANPP, and drought sensitivity was estimated as the reduction in ANPP per millimeter reduction in precipitation. Arid grasslands were the most sensitive to drought, but drought responses and sensitivity varied by more than twofold among the six grasslands, despite all sites experiencing 40% reductions in growing season precipitation. Although drought sensitivity generally decreased with increasing MAP as predicted, there was evidence that the identity and traits of the dominant species, as well as plant functional diversity, influenced sensitivity. A more comprehensive understanding of the mechanisms leading to differences in drought sensitivity will require multi-site manipulative experiments designed to assess both biotic and abiotic determinants of ecosystem sensitivity.

Climate change and human activities altered the diversity and composition of soil microbial community in alpine grasslands of the Qinghai-Tibetan Plateau.

PubMed

Zhang, Yong; Dong, Shikui; Gao, Qingzhu; Liu, Shiliang; Zhou, Huakun; Ganjurjav, Hasbagan; Wang, Xuexia

2016-08-15

Alpine ecosystems are known to be sensitive to climate change and human disturbances. However, the knowledge about the changes of their underground microbial communities is inadequate. We explored the diversity and structure of soil bacterial and fungal communities using Ilumina MiSeq sequencing in native alpine grasslands (i.e. the alpine meadow, alpine steppe) and cultivated grassland of the Qinghai-Tibetan Plateau (QTP) under three-year treatments of overgrazing, warming and enhanced rainfall. Enhanced rainfall rather than warming significantly reduced soil microbial diversity in native alpine grasslands. Variable warming significantly reduced it in the cultivated grassland. Over 20% and 40% variations of microbial diversity could be explained by soil nutrients and moisture in the alpine meadow and cultivated grassland, separately. Soil microbial communities could be clustered into different groups according to different treatments in the alpine meadow and cultivated grassland. For the alpine steppe, with the lowest soil nutrients and moistures, <10% variations of microbial diversity was explained by soil properties; and the soil microbial communities among different treatments were similar. The soil microbial community in the cultivated grassland was varied from it in native grasslands. Over 50% variations of soil microbial communities among different treatments were explained by soil nutrients and moisture in each grassland type. Our results suggest that climate change and human activities strongly affected soil microbial communities by changing soil nutrients and moistures in alpine grassland ecosystems. Copyright © 2016 Elsevier B.V. All rights reserved.

13C NMR spectroscopy characterization of particle-size fractionated soil organic carbon in subalpine forest and grassland ecosystems.

PubMed

Shiau, Yo-Jin; Chen, Jenn-Shing; Chung, Tay-Lung; Tian, Guanglong; Chiu, Chih-Yu

2017-12-01

Soil organic carbon (SOC) and carbon (C) functional groups in different particle-size fractions are important indicators of microbial activity and soil decomposition stages under wildfire disturbances. This research investigated a natural Tsuga forest and a nearby fire-induced grassland along a sampling transect in Central Taiwan with the aim to better understand the effect of forest wildfires on the change of SOC in different soil particle scales. Soil samples were separated into six particle sizes and SOC was characterized by solid-state 13 C nuclear magnetic resonance spectroscopy in each fraction. The SOC content was higher in forest than grassland soil in the particle-size fraction samples. The O-alkyl-C content (carbohydrate-derived structures) was higher in the grassland than the forest soils, but the alkyl-C content (recalcitrant substances) was higher in forest than grassland soils, for a higher humification degree (alkyl-C/O-alkyl-C ratio) in forest soils for all the soil particle-size fractions. High humification degree was found in forest soils. The similar aromaticity between forest and grassland soils might be attributed to the fire-induced aromatic-C content in the grassland that offsets the original difference between the forest and grassland. High alkyl-C content and humification degree and low C/N ratios in the fine particle-size fractions implied that undecomposed recalcitrant substances tended to accumulate in the fine fractions of soils.

Patterns of woody plant invasion in an Argentinean coastal grassland

NASA Astrophysics Data System (ADS)

Alberio, Constanza; Comparatore, Viviana

2014-01-01

Coastal dune grasslands are fragile ecosystems that have historically been subjected to various types of uses and human activities. In Buenos Aires Province (Argentina), these areas are frequently afforested for urban and touristic development. The introduction and subsequent spread of exotic tree species is one of the main threats to conservation of natural grasslands as invasive trees strongly transform their structure and composition. The aim of this study was to identify patterns of woody plant invasion comparing plant communities and environmental variables between invaded and non-invaded areas surrounding the coastal village of Mar Azul, Argentina. Coastal grasslands in this area are being invaded by Populus alba (white poplar) and Acacia longifolia (coast wattle). The height of the saplings and the richness of the accompanying vegetation were evaluated in relation to the distance from the edge of the mature tree patches. Also, the cover, richness and diversity of all species in the invaded and non-invaded areas were measured, as well as soil pH, temperature and particle size. Negative correlations were found between the height of the saplings and distance to mature tree patches in all areas. The richness of the accompanying vegetation was negatively and positively correlated with the distance from the poplar and acacia area, respectively. The most abundant native species was Cortaderia selloana. Less cover, richness and diversity of native plant species and greater soil particle size were found in invaded areas, where the proportion of bare soil was higher. Also, a higher proportion of leaf litter in the invaded areas was registered. The results emphasize the invasive capacity of P. alba and A. longifolia advancing on the native communities and reducing their richness. Knowledge of the impact of invasive woody plants in coastal grasslands is important to design active management strategies for conservation purposes.

Export of dissolved organic carbon and nitrate from grassland in winter using high temporal resolution, in situ UV sensing.

PubMed

Sandford, Richard C; Hawkins, Jane M B; Bol, Roland; Worsfold, Paul J

2013-07-01

Co-deployment of two reagentless UV sensors for high temporal resolution (15 min) real time determination of wintertime DOC and nitrate-N export from a grassland lysimeter plot (North Wyke, Devon, UK) is reported. They showed rapid, transient but high impact perturbations of DOC (5.3-23 mg CL(-1)) and nitrate-N export after storm/snow melt which discontinuous sampling would not have observed. During a winter freeze/thaw cycle, DOC export (1.25 kg Cha(-1)d(-1)) was significantly higher than typical UK catchment values (maximum 0.25 kg Chad(-1)) and historical North Wyke data (0.7 kg Cha(-1)d(-1)). DOC concentrations were inversely correlated with the key DOC physico-chemical drivers of pH (January r=-0.65), and conductivity (January r=-0.64). Nitrate-N export (0.8-1.5 mg NL(-1)) was strongly correlated with DOC export (r ≥ 0.8). The DOC:NO3-N molar ratios showed that soil microbial N assimilation was not C limited and therefore high N accrual was not promoted in the River Taw, which is classified as a nitrate vulnerable zone (NVZ). The sensor was shown to be an effective sentinel device for identifying critical periods when rapid ecosystem N accumulation could be triggered by a shift in resource stoichiometry. It is therefore a useful tool to help evaluate land management strategies and impacts from climate change and intensive agriculture. Copyright © 2013 Elsevier B.V. All rights reserved.

Carbon Content of Managed Grasslands Under Mediterranean Climate and Implications for Carbon Sequestration

NASA Astrophysics Data System (ADS)

Owen, J. J.; Silver, W. L.

2012-12-01

Grasslands cover approximately 25% of the terrestrial land surface and typically have considerable carbon (C) storage potential in soils. Human activities have the potential to release or increase C stored in grassland soils. In California, where half the land area is comprised of grasslands, soil C content spans almost an order of magnitude and is not well correlated with climate. The role of management practices in these patterns has not been previously explored. We measured soil C pools and soil physical characteristics at 10 grazed grassland sites in Marin and Sonoma counties in California. At each site, 2 to 3 fields with similar soil units but under different management practices (including manure amendment, tilling, irrigation, and seeding) were sampled at intervals to 50 cm-depth. Soil C varied by a factor of 2 and manure additions tended to increase soil C content by 3 to 15%. Manure additions did not always increase soil C, however. Grazed but otherwise undisturbed conservation land at one site had higher soil C than the adjacent manured fields. This was likely due to the presence of tall grasses and scattered shrubs on the conservation land versus the ryegrass, orchard grass, and clover seeded on the other fields. Variations were greater between sites than between fields at the same site. Soil C percentage decreased with depth but typically more than half of the total soil C content was located below 10-cm-depth, as observed elsewhere in California. We found that California grasslands perform an important ecosystem service by storing C in soil. Management through manure addition can increase that storage, the amount of which primarily depends on climate and soil texture.

Grassland Resistance and Resilience after Drought Depends on Management Intensity and Species Richness

PubMed Central

Vogel, Anja; Scherer-Lorenzen, Michael; Weigelt, Alexandra

2012-01-01

The degree to which biodiversity may promote the stability of grasslands in the light of climatic variability, such as prolonged summer drought, has attracted considerable interest. Studies so far yielded inconsistent results and in addition, the effect of different grassland management practices on their response to drought remains an open question. We experimentally combined the manipulation of prolonged summer drought (sheltered vs. unsheltered sites), plant species loss (6 levels of 60 down to 1 species) and management intensity (4 levels varying in mowing frequency and amount of fertilizer application). Stability was measured as resistance and resilience of aboveground biomass production in grasslands against decreased summer precipitation, where resistance is the difference between drought treatments directly after drought induction and resilience is the difference between drought treatments in spring of the following year. We hypothesized that (i) management intensification amplifies biomass decrease under drought, (ii) resistance decreases with increasing species richness and with management intensification and (iii) resilience increases with increasing species richness and with management intensification. We found that resistance and resilience of grasslands to summer drought are highly dependent on management intensity and partly on species richness. Frequent mowing reduced the resistance of grasslands against drought and increasing species richness decreased resistance in one of our two study years. Resilience was positively related to species richness only under the highest management treatment. We conclude that low mowing frequency is more important for high resistance against drought than species richness. Nevertheless, species richness increased aboveground productivity in all management treatments both under drought and ambient conditions and should therefore be maintained under future climates. PMID:22615865

Habitat effects on condition of doe mule deer in arid mixed woodland-grassland

USGS Publications Warehouse

Bender, L.C.; Lomas, L.A.; Kamienski, T.

2007-01-01

Productivity of mule deer (Odocoileus hemionus Raf.) populations is closely linked to individual nutritional condition. We modeled body fat of individual does as a function of vegetation cover, composition, and water characteristics of their annual, summer, and winter home ranges in north-central New Mexico. We also modeled home range size as a function of the same characteristics. Levels of body fat were most closely and negatively related to the amount of pinyon-juniper in an individual deer's annual home range (F1,21 = 7.6; P = 0.012; r2 = 0.26). Pinyon-juniper types provided little (combined ground cover of preferred forbs and shrubs = 5.7%) mule deer forage but were included in home ranges in excess of their availability on the landscape, likely because of security cover attributes. Proportion of grasslands in home ranges was most strongly related to both annual (F1,23 = 4.9; P = 0.037; r2 = 0.18) and summer (F2,25 = 5.7; P = 0.009; r2 = 0.31) home range sizes, and home ranges increased as the grassland component increased, indicating that this habitat type was providing little value to mule deer. Grassland (0.2% combined cover of preferred forb and shrub) and montane conifer (3.2% ground cover of preferred forb and shrub) habitat types similarly lacked preferred mule deer food, and grasslands also lacked cover. Most immediate gains in mule deer habitat in north-central New Mexico may be attained by management of pinyon-juniper communities to increase forage quantity and quality while maintaining cover attributes. Gains can also be realized in grasslands, but here management must establish both cover and forage.

Arbuscular mycorrhiza fungi mediate soil respiration response to climate change in California grasslands

NASA Astrophysics Data System (ADS)

Estruch, Carme; Mcfarland, Jack; Haw, Monica P.; Schulz, Marjorie S.; Pugnaire, Francisco I.; Waldrop, Mark P.

2017-04-01

California grasslands store ca. 100 Tg of soil organic carbon (SOC) and almost 40% of those ecosystems are prone to land use changes. The fate of these carbon pools will largely depend on how the main components of soil respiration - i.e., roots, mycorrhiza, and 'bulk soil' communities- respond to such changes. In order to determine the sensitivity to environmental drivers we set up an experiment to address the effect of plant community composition, soil age and warming on soil respiration rate during the 2014-2015 winter. We tested differences among microbial, fungal and root respiration using an exclusion technique to assess the effect of plant community (open grasslands vs oak woodland) in two field sites differing in soil properties as nutrient content, related to geologic soil age (92 and 137 kyr). We also used open top chambers (OTC) to simulate global change effects on grasslands. Our results showed that arbuscular mycorrhizal fungi were the main drivers of differences recorded between soils of different age, and that those differences were linked to nutrient availability. Bulk soil respiration was more sensitive to environmental variation than mycorrhizal or root respiration, indicating that the presence of mycorrhizae and roots can regulate the capacity of CO2 emission to the atmosphere. Soil age affected CO2 flux from grasslands but not under oak canopies, likely due to the high concentration of SOM in oak canopies which moderated any affect of soil mineralogy on nutrient availability. Overall our study shows that the ability of grasslands to mitigate CO2 emissions depends on interactions between vegetation and their rhizosphere on soil microbial communities.