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Sample records for net community production

  1. Ultraviolet radiation enhances Arctic net plankton community production

    NASA Astrophysics Data System (ADS)

    Garcia-Corral, Lara S.; Agustí, Susana; Regaudie-de-Gioux, Aurore; Iuculano, Francesca; Carrillo-de-Albornoz, Paloma; Wassmann, Paul; Duarte, Carlos M.

    2014-08-01

    In this study we report the response of net community production (NCP) of plankton communities in the Arctic surface waters exposure to natural ultraviolet radiation (UVR) conditions. A possible bias in previous measurements performed using borosilicate glass bottles (opaque to most UVR) can underestimate NCP. Here we show that 77% of the sampled communities suffer, on average, 38.5% of net increase in NCP when exposed to natural UV-B condition, relative to values when UV-B radiation is excluded. UV-B tends to shift communities toward autotrophy, with the most autotrophic communities responding the strongest. This is likely explained by the inhibition of bacterial respiration during the continuous day period of the Arctic summer, corroborated by experiments where bacterial production influenced by UV-B directly affect NCP. Whereas Arctic warming is expected to lead to lower NCP, our results show that increased UV-B radiation may partially compensate this negative effect in surface waters.

  2. Assessing net community production in a glaciated Alaskan fjord

    NASA Astrophysics Data System (ADS)

    Reisdorph, S. C.; Mathis, J. T.

    2015-09-01

    The impact of deglaciation in Glacier Bay has been observed to seasonally influence the biogeochemistry of this marine system. The influence from surrounding glaciers, particularly tidewater glaciers, has the potential to affect the efficiency and structure of the marine food web within Glacier Bay. To assess the magnitude and the spatial and temporal variability in net community production in a glaciated fjord, we measured dissolved inorganic carbon, inorganic macronutrients, dissolved oxygen, and particulate organic carbon between July 2011 and July 2012 in Glacier Bay, Alaska. High net community production rates were observed across the bay (~ 54 to ~ 81 mmol C m-2 d-1) between the summer and fall of 2011. However, between the fall and winter, as well as between the winter and spring of 2012, air-sea fluxes of carbon dioxide and organic matter respiration made net community production rates negative across most of the bay as inorganic carbon and macronutrient concentrations returned to pre-bloom levels. The highest organic carbon production occurred within the west arm between the summer and fall of 2011 with ~ 4.5 × 105 kg C d-1. Bay-wide, there was carbon production of ~ 9.2 × 105 g C d-1 between the summer and fall. Respiration and air-sea gas exchange were the dominant drivers of carbon chemistry between the fall and winter of 2012. The substantial spatial and temporal variability in our net community production estimates may reflect glacial influences within the bay, as meltwater is depleted in macronutrients relative to marine waters entering from the Gulf of Alaska in the middle and lower parts of the bay. Further glacial retreat will likely lead to additional modifications in the carbon biogeochemistry of Glacier Bay, with unknown consequences for the local marine food web, which includes many species of marine mammals.

  3. Predicting plankton net community production in the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Serret, Pablo; Robinson, Carol; Fernández, Emilio; Teira, Eva; Tilstone, Gavin; Pérez, Valesca

    2009-07-01

    We present, test and implement two contrasting models to predict euphotic zone net community production (NCP), which are based on 14C primary production (PO 14CP) to NCP relationships over two latitudinal (ca. 30°S-45°N) transects traversing highly productive and oligotrophic provinces of the Atlantic Ocean (NADR, CNRY, BENG, NAST-E, ETRA and SATL, Longhurst et al., 1995 [An estimation of global primary production in the ocean from satellite radiometer data. Journal of Plankton Research 17, 1245-1271]). The two models include similar ranges of PO 14CP and community structure, but differ in the relative influence of allochthonous organic matter in the oligotrophic provinces. Both models were used to predict NCP from PO 14CP measurements obtained during 11 local and three seasonal studies in the Atlantic, Pacific and Indian Oceans, and from satellite-derived estimates of PO 14CP. Comparison of these NCP predictions with concurrent in situ measurements and geochemical estimates of NCP showed that geographic and annual patterns of NCP can only be predicted when the relative trophic importance of local vs. distant processes is similar in both modeled and predicted ecosystems. The system-dependent ability of our models to predict NCP seasonality suggests that trophic-level dynamics are stronger than differences in hydrodynamic regime, taxonomic composition and phytoplankton growth. The regional differences in the predictive power of both models confirm the existence of biogeographic differences in the scale of trophic dynamics, which impede the use of a single generalized equation to estimate global marine plankton NCP. This paper shows the potential of a systematic empirical approach to predict plankton NCP from local and satellite-derived P estimates.

  4. Global net community production and the putative net heterotrophy of the oligotrophic oceans

    NASA Astrophysics Data System (ADS)

    Westberry, Toby K.; Williams, Peter J. Le B.; Behrenfeld, Michael J.

    2012-12-01

    Reconciling rates of organic carbon export from the euphotic zone with the consumption of organic material in the dark ocean remains one of the major quantitative uncertainties of the ocean carbon cycle. Euphotic zone net community production (NCP) provides one broad constraint on export flux and potential carbon drawdown. However, in vitro measurements of NCP consistently suggest that oligotrophic oceans are net heterotrophic, which is inconsistent with evidence of their carbon export to depth. Further, we have been unable to identify organic inputs on a scale to supplement the purported net heterotrophy. Here, we calculate global NCP rates using empirical relationships between in vitro photosynthesis (P) and respiration (R) and a satellite-based productivity model. A low value for global NCP (˜139 ± 325 Tmol C a-1) is found when a single P versus R (PvR) relation is derived from all in vitro data, with areas of net heterotrophy occupying 52% of the surface ocean. If a set of PvR relationships are instead derived by segregating the in vitro data into broad latitudinal zones associated with differing nutrient dynamics, we find a global NCP distribution in better agreement with independent model estimates of particulate carbon export, except in the 10°-40° latitudinal band where negative NCP values remain. Consistency between NCP and particulate export across all latitudes is achieved by applying a single PvR relationship derived using all in vitro data collected outside the 10°-40° latitudinal band. With this model, global NCP is estimated at ˜781 ± 393 Tmol C a-1 and modeled values at well-characterized field sites are in good agreement with non-incubation based in situ measurements. We infer from our results that in vitro NCP data from oligotrophic sites are too low, and suggest that this error is more likely the result of underestimated photosynthesis than overestimated respiration, although the precise physiological nature of the problem remains to be

  5. Assessing net community production in a glaciated Alaska fjord

    NASA Astrophysics Data System (ADS)

    Reisdorph, S. C.; Mathis, J. T.

    2014-09-01

    The impact of deglaciation in Glacier Bay (GLBA) has been observed to seasonally impact the biogeochemistry of this marine system. The influence from surrounding glaciers, particularly tidewater glaciers, has the potential to greatly impact the efficiency and structure of the marine food web within GLBA. To assess the magnitude, spatial and temporal variability of net community production (NCP) in a glaciated fjord, we measured dissolved inorganic carbon (DIC), inorganic macronutrients, dissolved oxygen (DO) and particulate organic carbon (POC) between July 2011 and July 2012 in Glacier Bay, AK. Seasonally-averaged data were analyzed on a regional basis to account for distinct biogeochemical differences within the Bay due to spatial variation in rates of primary production and the influence of glacial-fed stratification, particularly in the northern regions. High NCP rates were observed across the Bay (~ 54 to ~ 81 mmol C m-2 d-1) between the summer and fall of 2011. However, between the fall and winter, as well as between the winter and spring of 2012, air-sea fluxes of CO2 and organic matter respiration made NCP rates negative across most of the Bay as inorganic carbon and macronutrient concentrations returned to pre-bloom levels. The highest carbon production occurred within the lower bay between the summer and fall of 2011 with ~ 1.3 × 1010 g C season-1. Bay-wide, there was carbon production of ~ 2.6 × 1010 g C season-1 between the summer and fall. Respiration and air-sea gas exchange were the dominant drivers of carbon biogeochemistry between the fall and winter of 2012. The substantial spatial and temporal variability in our NCP estimates largely reflect glacial influences within the Bay, as melt-water is depleted in macronutrients relative to marine waters entering from the Gulf of Alaska in the middle and lower parts of the Bay. Further glacial retreat will likely lead to additional modifications in the carbon biogeochemistry of GLBA with unknown

  6. Effects of elevated turbidity and nutrients on the net production of a tropical seagrass community

    SciTech Connect

    Caldwell, J.W.

    1985-01-01

    Dredging effects on seagrass communities in the Florida Keys were examined by (1) comparing impacts on net production resulting from dredging and natural weather events, (2) determining changes in community photosynthetic efficiency, (3) evaluating shading and nutrient effects on net production, and (4) developing a systems dynamics model. Net community production was estimated during numerous meteorological and dredging events using the Odum-Hoskins oxygen technique in flow-through field microcosms. In other experiments, shading and nutrients (phosphorus, nitrate, and ammonia) were manipulated to simulate dredge plume conditions. The greatest depression in net community production resulted from severe thunderstorms and dredging events, respectively. In field microcosm experiments, significant interaction occurred between shading and nutrient concentration. The model of seagrass production was most sensitive to changes in nutrient-seagrass relationships, seagrass production estimates, and seagrass-light interactions. Recovery of seagrass biomass following numerous dredging events (3.5 years) was longer than that from the estimated total annual thunderstorms encountered (1 year) but shorter than recovery from hurricane events (4.1 years).

  7. Uncertainty and sensitivity in optode-based shelf-sea net community production estimates

    NASA Astrophysics Data System (ADS)

    Hull, Tom; Greenwood, Naomi; Kaiser, Jan; Johnson, Martin

    2016-02-01

    Coastal seas represent one of the most valuable and vulnerable habitats on Earth. Understanding biological productivity in these dynamic regions is vital to understanding how they may influence and be affected by climate change. A key metric to this end is net community production (NCP), the net effect of autotrophy and heterotrophy; however accurate estimation of NCP has proved to be a difficult task. Presented here is a thorough exploration and sensitivity analysis of an oxygen mass-balance-based NCP estimation technique applied to the Warp Anchorage monitoring station, which is a permanently well-mixed shallow area within the River Thames plume. We have developed an open-source software package for calculating NCP estimates and air-sea gas flux. Our study site is identified as a region of net heterotrophy with strong seasonal variability. The annual cumulative net community oxygen production is calculated as (-5 ± 2.5) mol m-2 a-1. Short-term daily variability in oxygen is demonstrated to make accurate individual daily estimates challenging. The effects of bubble-induced supersaturation is shown to have a large influence on cumulative annual estimates and is the source of much uncertainty.

  8. Uncertainty and sensitivity in optode-based shelf-sea net community production estimates

    NASA Astrophysics Data System (ADS)

    Hull, T.; Greenwood, N.; Kaiser, J.; Johnson, M.

    2015-09-01

    Coastal seas represent one of the most valuable and vulnerable habitats on Earth. Understanding biological productivity in these dynamic regions is vital to understanding how they may influence and be affected by climate change. A key metric to this end is net community production (NCP), the net effect of autotrophy and hetrotrophy, however accurate estimation of NCP has proved to be a difficult task. Presented here is a thorough exploration and sensitivity analysis of an oxygen mass-balance based NCP estimation technique applied to the Warp Anchorage monitoring station which is a permanently well mixed shallow area within the Thames river plume. We have developed an open source software package for calculating NCP estimates and air-sea gas flux. Our study site is identified as a region of net heteotrophy with strong seasonal variability. The annual cumulative net community oxygen production is calculated as (-5 ± 2.5) mol m-2 a-1. Short term daily variability in oxygen is demonstrated to make accurate individual daily estimates challenging. The effects of bubble induced supersaturation is shown to have a large influence on cumulative annual estimates, and is the source of much uncertainty.

  9. Net community production and dark community respiration in a Karenia brevis (Davis) bloom in West Florida coastal waters, USA.

    PubMed

    Hitchcock, Gary L; Kirkpatrick, Gary; Minnett, Peter; Palubok, Valeriy

    2010-05-01

    Oxygen-based productivity and respiration rates were determined in West Florida coastal waters to evaluate the proportion of community respiration demands met by autotrophic production within a harmful algal bloom dominated by Karenia brevis. The field program was adaptive in that sampling during the 2006 bloom occurred where surveys by the Florida Wildlife Research Institute indicated locations with high cell abundances. Net community production (NCP) rates from light-dark bottle incubations during the bloom ranged from 10 to 42 µmole O2 L(-1) day(-1) with highest rates in bloom waters where abundances exceeded 10(5) cells L(-1). Community dark respiration (R) rates in dark bottles ranged from <10 to 70 µmole O2 L(-1) day(-1) over 24 h. Gross primary production derived from the sum of NCP and R varied from ca. 20 to 120 µmole O2 L(-1) day(-1). The proportion of GPP attributed to NCP varied with the magnitude of R during day and night periods. Most surface communities exhibited net autotrophic production (NCP > R) over 24 h, although heterotrophy (NCP < R) characterized the densest sample where K. brevis cell densities exceed 10(6) cells L(-1). PMID:24179460

  10. The relation of mixed-layer net community production to phytoplankton community composition in the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Cassar, Nicolas; Wright, Simon W.; Thomson, Paul G.; Trull, Thomas W.; Westwood, Karen J.; Salas, Miguel; Davidson, Andrew; Pearce, Imojen; Davies, Diana M.; Matear, Richard J.

    2015-04-01

    Surface ocean productivity mediates the transfer of carbon to the deep ocean and in the process regulates atmospheric CO2 levels. A common axiom in oceanography is that large phytoplankton contribute disproportionally to the transfer of carbon to the deep ocean because of their greater ability to escape grazing pressure, build biomass, and sink. In the present study, we assessed the relationship of net community production to phytoplankton assemblages and plankton size distribution in the Sub-Antarctic Zone and northern reaches of the Polar Frontal Zone in the Australian sector of the Southern Ocean. We reanalyzed and synthesized previously published estimates of O2/Ar net community oxygen production (NCP) and triple-O2 isotopes gross primary oxygen production (GPP) along with microscopic and pigment analyses of the microbial community. Overall, we found that the axiom that large phytoplankton drive carbon export was not supported in this region. Mixed-layer-depth-integrated NCP was correlated to particulate organic carbon (POC) concentration in the mixed layer. While lower NCP/GPP and NCP/POC values were generally associated with communities dominated by smaller plankton size (as would be expected), these communities did not preclude high values for both properties. Vigorous NCP in some regions occurred in the virtual absence of large phytoplankton (and specifically diatoms) and in communities dominated by nanoplankton and picoplankton. We also observed a positive correlation between NCP and the proportion of the phytoplankton community grazed by microheterotrophs, supporting the mediating role of grazers in carbon export. The novel combination of techniques allowed us to determine how NCP relates to upper ocean ecosystem characteristics and may lead to improved models of carbon export.

  11. Ocean carbon cycling in the Indian Ocean: 2. Estimates of net community production

    NASA Astrophysics Data System (ADS)

    Bates, Nicholas R.; Pequignet, A. Christine; Sabine, Christopher L.

    2006-09-01

    The spatiotemporal variability of ocean carbon cycling and air-sea CO2 exchange in the Indian Ocean was examined using inorganic carbon data collected as part of the World Ocean Circulation Experiment (WOCE) cruises in 1995. Several carbon mass balance approaches were used to estimate rates of net community production (NCP) in the Indian Ocean. Carbon transports into and out of the Indian Ocean were derived using mass transport estimates of Robbins and Toole (1997) and Schmitz (1996), and transoceanic hydrographic and TCO2 sections at 32°S and across the Indonesian Throughflow. The derived NCP rates of 749 ± 227 to 1572 ± 180 Tg C yr-1 (0.75-1.57 Pg C yr-1) estimated by carbon mass balance were similar to new production rates (1100-1800 Tg C yr-1) determined for the Indian Ocean by a variety of other methods (Louanchi and Najjar, 2000; Gnanadesikan et al., 2002). Changes in carbon inventories of the surface layer were also used to evaluate the spatiotemporal patterns of NCP. Significant NCP occurred in all regions during the Northeast Monsoon and Spring Intermonsoon periods. During the Southwest Monsoon and Fall Intermonsoon periods, the trophic status appears to shift from net autotrophy to net heterotrophy, particularly in the Arabian Sea, Bay of Bengal, and 10°N to 10°S zones.

  12. Annual net community production and the biological carbon flux in the ocean

    NASA Astrophysics Data System (ADS)

    Emerson, Steven

    2014-01-01

    The flux of biologically produced organic matter from the surface ocean (the biological pump), over an annual cycle, is equal to the annual net community production (ANCP). Experimental determinations of ANCP at ocean time series sites using a variety of different metabolite mass balances have made it possible to evaluate the accuracy of sediment trap fluxes and satellite-determined ocean carbon export. ANCP values at the Hawaii Ocean Time-series (HOT), the Bermuda Atlantic Time-series Study (BATS), Ocean Station Papa (OSP) are 3 ± 1 mol C m-2 yr-1—much less variable than presently suggested by satellite remote sensing measurements and global circulation models. ANCP determined from mass balances at these locations are 3-4 times particulate organic carbon fluxes measured in sediment traps. When the roles of dissolved organic carbon (DOC) flux, zooplankton migration, and depth-dependent respiration are considered these differences are reconciled at HOT and OSP but not at BATS, where measured particulate fluxes are about 3 times lower than expected. Even in the cases where sediment trap fluxes are accurate, it is not possible to "scale up" these measurements to determine ANCP without independent determinations of geographically variable DOC flux and zooplankton migration. Estimates of ANCP from satellite remote sensing using net primary production determined by the carbon-based productivity model suggests less geographic variability than its predecessor (the vertically generalized productivity model) and brings predictions at HOT and OSP closer to measurements; however, satellite-predicted ANCP at BATS is still 3 times too low.

  13. Decoupling of net community and export production on submesoscales in the Sargasso Sea

    NASA Astrophysics Data System (ADS)

    Estapa, M. L.; Siegel, D. A.; Buesseler, K. O.; Stanley, R. H. R.; Lomas, M. W.; Nelson, N. B.

    2015-08-01

    Determinations of the net community production (NCP) in the upper ocean and the particle export production (EP) should balance over long time and large spatial scales. However, recent modeling studies suggest that a horizontal decoupling of flux-regulating processes on submesoscales (≤10 km) could lead to imbalances between individual determinations of NCP and EP. Here we sampled mixed-layer biogeochemical parameters and proxies for NCP and EP during 10, high-spatial resolution (~2 km) surface transects across strong physical gradients in the Sargasso Sea. We observed strong biogeochemical and carbon flux variability in nearly all transects. Spatial coherence among measured biogeochemical parameters within transects was common but rarely did the same parameters covary consistently across transects. Spatial variability was greater in parameters associated with higher trophic levels, such as chlorophyll in >5.0 µm particles, and variability in EP exceeded that of NCP in nearly all cases. Within sampling transects, coincident EP and NCP determinations were uncorrelated. However, when averaged over each transect (30 to 40 km in length), we found NCP and EP to be significantly and positively correlated (R = 0.72, p = 0.04). Transect-averaged EP determinations were slightly smaller than similar NCP values (Type-II regression slope of 0.93, standard deviation = 0.32) but not significantly different from a 1:1 relationship. The results show the importance of appropriate sampling scales when deriving carbon flux budgets from upper ocean observations.

  14. Net community production and calcification from 7 years of NOAA Station Papa Mooring measurements

    NASA Astrophysics Data System (ADS)

    Fassbender, Andrea J.; Sabine, Christopher L.; Cronin, Meghan F.

    2016-02-01

    Seven years of near-continuous observations from the Ocean Station Papa (OSP) surface mooring were used to evaluate drivers of marine carbon cycling in the eastern subarctic Pacific. Processes contributing to mixed layer carbon inventory changes throughout each deployment year were quantitatively assessed using a time-dependent mass balance approach in which total alkalinity and dissolved inorganic carbon were used as tracers. By using two mixed layer carbon tracers, it was possible to isolate the influences of net community production (NCP) and calcification. Our results indicate that the annual NCP at OSP is 2 ± 1 mol C m-2 yr-1 and the annual calcification is 0.3 ± 0.3 mol C m-2 yr-1. Piecing together evidence for potentially significant dissolved organic carbon cycling in this region, we estimate a particulate inorganic carbon to particulate organic carbon ratio between 0.15 and 0.25. This is at least double the global average, adding to the growing evidence that calcifying organisms play an important role in carbon export at this location. These results, coupled with significant seasonality in the NCP, suggest that carbon cycling near OSP may be more complex than previously thought and highlight the importance of continuous observations for robust assessments of biogeochemical cycling.

  15. Net community production at Ocean Station Papa observed with nitrate and oxygen sensors on profiling floats

    NASA Astrophysics Data System (ADS)

    Plant, Joshua N.; Johnson, Kenneth S.; Sakamoto, Carole M.; Jannasch, Hans W.; Coletti, Luke J.; Riser, Stephen C.; Swift, Dana D.

    2016-06-01

    Six profiling floats equipped with nitrate and oxygen sensors were deployed at Ocean Station P in the Gulf of Alaska. The resulting six calendar years and 10 float years of nitrate and oxygen data were used to determine an average annual cycle for net community production (NCP) in the top 35 m of the water column. NCP became positive in February as soon as the mixing activity in the surface layer began to weaken, but nearly 3 months before the traditionally defined mixed layer began to shoal from its winter time maximum. NCP displayed two maxima, one toward the end of May and another in August with a summertime minimum in June corresponding to the historical peak in mesozooplankton biomass. The average annual NCP was determined to be 1.5 ± 0.6 mol C m-2 yr-1 using nitrate and 1.5 ± 0.7 mol C m-2 yr-1 using oxygen. The results from oxygen data proved to be quite sensitive to the gas exchange model used as well as the accuracy of the oxygen measurement. Gas exchange models optimized for carbon dioxide flux generally ignore transport due to gas exchange through the injection of bubbles, and these models yield NCP values that are two to three time higher than the nitrate-based estimates. If nitrate and oxygen NCP rates are assumed to be related by the Redfield model, we show that the oxygen gas exchange model can be optimized by tuning the exchange terms to reproduce the nitrate NCP annual cycle.

  16. The annual cycle of gross primary production, net community production, and export efficiency across the North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Palevsky, Hilary I.; Quay, Paul D.; Lockwood, Deirdre E.; Nicholson, David P.

    2016-02-01

    We measured triple oxygen isotopes and oxygen/argon dissolved gas ratios as nonincubation-based geochemical tracers of gross oxygen production (GOP) and net community production (NCP) on 16 container ship transects across the North Pacific from 2008 to 2012. We estimate rates and efficiency of biological carbon export throughout the full annual cycle across the North Pacific basin (35°N-50°N, 142°E-125°W) by constructing mixed layer budgets that account for physical and biological influences on these tracers. During the productive season from spring to fall, GOP and NCP are highest in the Kuroshio region west of 170°E and decrease eastward across the basin. However, deep winter mixed layers (>200 m) west of 160°W ventilate ~40-90% of this seasonally exported carbon, while only ~10% of seasonally exported carbon east of 160°W is ventilated in winter where mixed layers are <120 m. As a result, despite higher annual GOP in the west than the east, the annual carbon export (sequestration) rate and efficiency decrease westward across the basin from export of 2.3 ± 0.3 mol C m-2 yr-1 east of 160°W to 0.5 ± 0.7 mol C m-2 yr-1 west of 170°E. Existing productivity rate estimates from time series stations are consistent with our regional productivity rate estimates in the eastern but not western North Pacific. These results highlight the need to estimate productivity rates over broad spatial areas and throughout the full annual cycle including during winter ventilation in order to accurately estimate the rate and efficiency of carbon sequestration via the ocean's biological pump.

  17. Temperature effects on net greenhouse gas production and bacterial communities in arctic thaw ponds.

    PubMed

    Negandhi, Karita; Laurion, Isabelle; Lovejoy, Connie

    2016-08-01

    One consequence of High Arctic permafrost thawing is the formation of small ponds, which release greenhouse gases (GHG) from stored carbon through microbial activity. Under a climate with higher summer air temperatures and longer ice-free seasons, sediments of shallow ponds are likely to become warmer, which could influence enzyme kinetics or select for less cryophilic microbes. There is little data on the direct temperature effects on GHG production and consumption or on microbial communities' composition in Arctic ponds. We investigated GHG production over 16 days at 4°C and 9°C in sediments collected from four thaw ponds. Consistent with an enzymatic response, production rates of CO2 and CH4 were significantly greater at higher temperatures, with Q10 varying from 1.2 to 2.5. The bacterial community composition from one pond was followed through the incubation by targeting the V6-V8 variable regions of the 16S rRNA gene and 16S rRNA. Several rare taxa detected from rRNA accounted for significant community compositional changes. At the higher temperature, the relative community contribution from Bacteroidetes decreased by 15% with compensating increases in Betaproteobacteria, Alphaproteobacteria, Firmicutes, Acidobacteria, Verrucomicrobia and Actinobacteria. The increase in experimental GHG production accompanied by changes in community indicates an additional factor to consider in sediment environments when evaluating future climate scenarios. PMID:27288196

  18. Satellite estimates of net community production based on O2/Ar observations and comparison to other estimates

    NASA Astrophysics Data System (ADS)

    Li, Zuchuan; Cassar, Nicolas

    2016-05-01

    We present two statistical algorithms for predicting global oceanic net community production (NCP) from satellite observations. To calibrate these two algorithms, we compiled a large data set of in situ O2/Ar-NCP and remotely sensed observations, including sea surface temperature (SST), net primary production (NPP), phytoplankton size composition, and inherent optical properties. The first algorithm is based on genetic programming (GP) which simultaneously searches for the optimal form and coefficients of NCP equations. We find that several GP solutions are consistent with NPP and SST being strong predictors of NCP. The second algorithm uses support vector regression (SVR) to optimize a numerical relationship between O2/Ar-NCP measurements and satellite observations. Both statistical algorithms can predict NCP relatively well, with a coefficient of determination (R2) of 0.68 for GP and 0.72 for SVR, which is comparable to other algorithms in the literature. However, our new algorithms predict more spatially uniform annual NCP distribution for the world's oceans and higher annual NCP values in the Southern Ocean and the five oligotrophic gyres.

  19. Biomass production and net ecosystem exchange following defoliation in a wet sedge community

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Riparian ecosystems provide a multitude of ecosystem services, maintenance of which is tied to sustainable management of stream-side plant communities that provide important forage resources for livestock grazing operations. The objectives of this study were to evaluate above- and below-ground grow...

  20. Shifting grassland plant community structure drives positive interactive effects of warming and diversity on aboveground net primary productivity.

    PubMed

    Cowles, Jane M; Wragg, Peter D; Wright, Alexandra J; Powers, Jennifer S; Tilman, David

    2016-02-01

    Ecosystems worldwide are increasingly impacted by multiple drivers of environmental change, including climate warming and loss of biodiversity. We show, using a long-term factorial experiment, that plant diversity loss alters the effects of warming on productivity. Aboveground primary productivity was increased by both high plant diversity and warming, and, in concert, warming (≈1.5 °C average above and belowground warming over the growing season) and diversity caused a greater than additive increase in aboveground productivity. The aboveground warming effects increased over time, particularly at higher levels of diversity, perhaps because of warming-induced increases in legume and C4 bunch grass abundances, and facilitative feedbacks of these species on productivity. Moreover, higher plant diversity was associated with the amelioration of warming-induced environmental conditions. This led to cooler temperatures, decreased vapor pressure deficit, and increased surface soil moisture in higher diversity communities. Root biomass (0-30 cm) was likewise consistently greater at higher plant diversity and was greater with warming in monocultures and at intermediate diversity, but at high diversity warming had no detectable effect. This may be because warming increased the abundance of legumes, which have lower root : shoot ratios than the other types of plants. In addition, legumes increase soil nitrogen (N) supply, which could make N less limiting to other species and potentially decrease their investment in roots. The negative warming × diversity interaction on root mass led to an overall negative interactive effect of these two global change factors on the sum of above and belowground biomass, and thus likely on total plant carbon stores. In total, plant diversity increased the effect of warming on aboveground net productivity and moderated the effect on root mass. These divergent effects suggest that warming and changes in plant diversity are likely to have both

  1. Estimation of austral summer net community production in the Amundsen Sea: Self-organizing map analysis approach

    NASA Astrophysics Data System (ADS)

    Park, K.; Hahm, D.; Lee, D. G.; Rhee, T. S.; Kim, H. C.

    2014-12-01

    The Amundsen Sea, Antarctica, has been known for one of the most susceptible region to the current climate change such as sea ice melting and sea surface temperature change. In the Southern Ocean, a predominant amount of primary production is occurring in the continental shelf region. Phytoplankton blooms take place during the austral summer due to the limited sunlit and sea ice cover. Thus, quantifying the variation of summer season net community production (NCP) in the Amundsen Sea is essential to analyze the influence of climate change to the variation of biogeochemical cycle in the Southern Ocean. During the past three years of 2011, 2012 and 2014 in austral summer, we have conducted underway observations of ΔO2/Ar and derived NCP of the Amundsen Sea. Despite the importance of NCP for understanding biological carbon cycle of the ocean, the observations are rather limited to see the spatio-temporal variation in the Amundsen Sea. Therefore, we applied self-organizing map (SOM) analysis to expand our observed data sets and estimate the NCP during the summer season. SOM analysis, a type of artificial neural network, has been proved to be a useful method for extracting and classifying features in geoscience. In oceanography, SOM has applied for the analysis of various properties of the seawater such as sea surface temperature, chlorophyll concentration, pCO2, and NCP. Especially it is useful to expand a spatial coverage of direct measurements or to estimate properties whose satellite observations are technically or spatially limited. In this study, we estimate summer season NCP and find a variables set which optimally delineates the NCP variation in the Amundsen Sea as well. Moreover, we attempt to analyze the interannual variation of the Amundsen Sea NCP by taking climatological factors into account for the SOM analysis.

  2. Drivers of variation in aboveground net primary productivity and plant community composition differe across a broad precipitation gradient

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It has long been a goal of ecology to determine what factors drive variation in aboveground net primary production (ANPP). Total annual precipitation has been shown to be a strong predictor of ANPP across broad spatial scales, but a poor predictor at local scales. Here we aim to determine the amount...

  3. Climate change impacts on net primary production (NPP) and export production (EP) regulated by increasing stratification and phytoplankton community structure in CMIP5 models

    NASA Astrophysics Data System (ADS)

    Fu, W.; Randerson, J.; Moore, J. K.

    2015-08-01

    We examine climate change impacts on net primary production (NPP) and export production (sinking particulate flux; EP) with simulations from nine Earth System Models (ESMs) performed in the framework of the fifth Coupled Model Inter-comparison Project (CMIP5). Global NPP and EP are reduced considerably by the end of the century for the intense warming scenario of Representative Concentration Pathway (RCP) 8.5. Relative to the 1990s, global NPP in the 2090s is reduced by 2.3-16 % and EP by 7-18 %. The models with the largest increases in stratification (and largest relative reductions in NPP and EP) also show the largest positive biases in stratification for the contemporary period, suggesting some potential overestimation of climate impacts on NPP and EP. All of the CMIP5 models show an increase in stratification in response to surface ocean warming and freshening that is accompanied by decreases in NPP, EP, and surface macronutrient concentrations. There is considerable variability across models in the absolute magnitude of these fluxes, surface nutrient concentrations, and their perturbations by climate change, indicating large model uncertainties. The negative response of NPP and EP to stratification increases reflects a bottom-up control, as nutrient flux to the euphotic zone declines. Models with dynamic phytoplankton community structure show larger declines in EP than in NPP. This is driven by phytoplankton community composition shifts, with a reduced percentage of NPP by large phytoplankton under RCP 8.5, as smaller phytoplankton are favored under the increasing nutrient stress. Thus, projections of the NPP response to climate change in the CMIP5 models are critically dependent on the simulated phytoplankton community structure, the efficiency of the biological pump, and the resulting (highly variable) levels of regenerated production. Community composition is represented relatively simply in the CMIP5 models, and should be expanded to better capture the

  4. Investigating the spring bloom initiation and net community production in the Subantarctic Southern Ocean using high-resolution in situ glider data

    NASA Astrophysics Data System (ADS)

    thomalla, sandy; Racault, Marie-Fanny; Swart, Sebastiaan; Monteiro, Pedro

    2014-05-01

    Phytoplankton bloom phenology has important consequences for marine ecosystems, fisheries and carbon export to the ocean interior. As such, it is important to examine the drivers of phytoplankton bloom initiation and their sensitivity to inter-annual climate variability and change. In this study we use ~6 months of in-situ high-resolution glider data to investigate the spring bloom initiation in the subantarctic zone (SAZ) of the Southern Ocean by implementing three different methods; a rate of change method, a threshold method and a cumulative sum method. The bloom initiation dates are critically compared to one another and the drivers of discrepancies assessed to inform on the sensitivities of different methods to processes driving the seasonal evolution of phytoplankton biomass in the subantarctic. The bloom initiation dates combined with in situ glider data of chlorophyll, light, and mixed layer depth allow us to resolve both Sverdrup's Critical Depth and Behrenfeld's Disturbance Recovery models through the water column and thus determine the seasonal evolution of net community production and respiration rates and the potential for carbon export. The outputs of the two different models are compared to one another in the context of their sensitivities to water column processes thereby refining their ability to address specific system scale questions. The novelty of this study is that gliders provide an unprecedented dataset to assess the seasonal cycle of phytoplankton biomass throughout the water column at high resolution, thus enhancing our understanding of net community production and export processes at submeso-space and sub-seasonal time scales.

  5. Net production of oxygen in the subtropical ocean.

    PubMed

    Riser, Stephen C; Johnson, Kenneth S

    2008-01-17

    The question of whether the plankton communities in low-nutrient regions of the ocean, comprising 80% of the global ocean surface area, are net producers or consumers of oxygen and fixed carbon is a key uncertainty in the global carbon cycle. Direct measurements in bottle experiments indicate net oxygen consumption in the sunlit zone, whereas geochemical evidence suggests that the upper ocean is a net source of oxygen. One possible resolution to this conflict is that primary production in the gyres is episodic and thus difficult to observe: in this model, oligotrophic regions would be net consumers of oxygen during most of the year, but strong, brief events with high primary production rates might produce enough fixed carbon and dissolved oxygen to yield net production as an average over the annual cycle. Here we examine the balance of oxygen production over three years at sites in the North and South Pacific subtropical gyres using the new technique of oxygen sensors deployed on profiling floats. We find that mixing events during early winter homogenize the upper water column and cause low oxygen concentrations. Oxygen then increases below the mixed layer at a nearly constant rate that is similar to independent measures of net community production. This continuous oxygen increase is consistent with an ecosystem that is a net producer of fixed carbon (net autotrophic) throughout the year, with episodic events not required to sustain positive oxygen production. PMID:18202655

  6. Neural network-based estimates of Southern Ocean net community production from in-situ and satellite observation: A methodological study

    NASA Astrophysics Data System (ADS)

    Chang, C.; Johnson, N. C.; Cassar, N.

    2012-12-01

    Although the Southern Ocean (SO) net community production (NCP), which is the difference between gross primary production and the community respiration rate, plays an important role in the global carbon cycle, limited in situ measurements prohibit a thorough understanding of the climatology and variability NCP in this region. In order to achieve a more comprehensive characterization of temporal and spatial variability of Southern Ocean NCP, we use a neural network approach based on the self-organizing map (SOM) to reconstruct weekly gridded (1o x 1o) SO NCP maps for the period of 1998-2009. This approach combines in situ measurements of NCP from over 40 research cruises with satellite-derived NCP predictor data, which includes chlorophyll (Chl), particulate organic carbon (POC), photosynthetically available radiation (PAR), sea surface height (SSH), and sea surface temperature (SST), as well as the mixed layer depth (MLD) from a high-resolution ocean general circulation model forced with satellite observed wind. The resulting NCP reconstructions reveal a number of salient features, including low NCP in the subtropics except near land masses, elevated NCP along the subtropical front (STF) around 40oS and especially off the Atlantic coast of the South America between the Río de la Plata and the Falkland Island, and moderate NCP values near Kerguelen Islands and along the Antarctic coast. Peak SO NCP occurs during November - January, as expected, and the climatological NCP field during the growing season closely resembles the climatological POC field. This neural network approach, which reveals complex nonlinear relationships and readily handles missing predictor data, provides a comprehensive view of SO NCP and an opportunity to investigate variability over a period of more than ten years. Convergence of various approaches;

  7. Hourly oxygen and total gas tension measurements at the Southern Ocean Time Series site reveal winter ventilation and spring net community production

    NASA Astrophysics Data System (ADS)

    Weeding, Ben; Trull, Thomas W.

    2014-01-01

    Using a moored instrument package at 35 m depth at the Southern Ocean Time Series (SOTS) site near 46°56'S 142°15'E from September 2010 to April 2011 (219 days), we obtained the first Southern Ocean Time Series of dissolved oxygen (from an optode sensor) and nitrogen (from a total gas tension sensor). Nitrogen was consistently supersaturated (100.8%-102.9%), while oxygen was highly subsaturated in early spring (as low as 93.5%) and reached supersaturation (maximum 104.9%) during only 37 days in early summer. The low oxygen levels in spring illustrate the importance of deep mixing in the Subantarctic Zone in ventilating the upper limb of the global overturning circulation. Using nitrogen as a proxy for physical processes, we isolated biological contributions to the oxygen time series to obtain net community production (NCP). Almost all NCP occurred in spring in the presence of deep mixed layers, with only small additional contributions in summer after water column stratification. The temperature and salinity time series also revealed distinct parcels of water. Rapid changes at their interfaces generated unrealistic NCP events in the standard calculation model, which were removed, while still retaining NCP contributions from each parcel. NCP totaled 2.2 ± 1.2 mol O2 m-2 over the deployment, within the range of previous estimates from low temporal resolution techniques. Examination of errors revealed particular sensitivity to entrainment, suggesting more rigorous understanding of this process is required, e.g., via profiling instruments.

  8. Net community production and stoichiometry of nutrient consumption in a pelagic ecosystem of a northern high latitude fjord: mesocosm CO2 perturbation study

    NASA Astrophysics Data System (ADS)

    Silyakova, A.; Bellerby, R. G. J.; Czerny, J.; Schulz, K. G.; Nondal, G.; Tanaka, T.; Engel, A.; De Lange, T.; Riebesell, U.

    2012-08-01

    Net community production (NCP) and ratios of carbon to nutrient consumption were studied during a large-scale mesocosm experiment on ocean acidification in Kongsfjorden, West Spitsbergen, during June-July 2010. Nutrient-deplete fjord water with natural phyto- and bacteriaplankton assemblages, enclosed in nine mesocosms of ~ 50 m3 volume, was exposed to pCO2 levels ranging from 185 to 1420 μatm on initial state. Mean values of pCO2 levels during experiment ranged from 175 to 1085 μatm in different mesocosms. Phytoplankton growth was stimulated by nutrient addition. In this study NCP is estimated as a cumulative change in dissolved inorganic carbon concentrations. Stoichiometric couping between inorganic carbon and nutrient is shown as a ratio of a cumulative NCP to a cumulative change in inorganic nutrients. Three peaks of chlorophyll a concentration occurred during the experiment. Accordingly the experiment was divided in three phases. Overall cumulative NCP was similar in all mesocosms by the final day of experiment. However, NCP varied among phases, showing variable response to CO2 perturbation. Carbon to nitrogen (C : N) and carbon to phosphorus (C : P) uptake ratios were estimated only for the period after nutrient addition (post-nutrient period). For the total post-nutrient period ratios were close to Redfield proportions, however varied from it in different phases. The response of C : N and C : P uptake ratios to CO2 perturbation was different for three phases of the experiment, reflecting variable NCP and dependence on changing microbial community. Through the variable NCP, C : N and C : P uptake ratios for 31 days of the experiment we show a flexibility of biogeochemical response establishing a strong microbial loop in Kongsfjorden under different CO2 scenarios.

  9. Impact of Drought and Precipitation Seasonality on Net Primary Production and Plant Community Composition Across a Grassland Ecotone in New Mexico

    NASA Astrophysics Data System (ADS)

    Collins, S. L.; Thomey, M. L.; Brown, R. F.; Gehres, N.; Petrie, M. D.; Vanderbilt, K.; Pockman, W.

    2014-12-01

    In the southwestern US, climate change will impact the amount, timing and variability of rainfall during the summer monsoon. Changes in amount and seasonality of precipitation are likely to affect plant community dynamics and ecosystem processes, especially along ecotones. In 2012, we established a rainfall manipulation experiment (EDGE-Extreme Drought in Grasslands Experiment) in Chihuahuan Desert grassland (CDG) dominated by black grama and shortgrass steppe (SGS) dominated by blue grama across a grassland ecotone in central New Mexico. EDGE includes two rainfall treatments, chronic drought (~66% reduction in monsoon rainfall) and altered timing of the summer monsoon. Chronic drought is imposed from July through September by rainout shelters with roof panels that cover 66% of the surface area. To alter precipitation seasonality complete rainout shelters are erected in July and August, and all rainfall that occurred during this period is captured, stored, and then reapplied in several large rain events during September and October. Thus, this treatment receives the same amount of precipitation as ambient but differs in seasonality and frequency of rain events. We measured soil moisture, aboveground net primary production (ANPP), and plant species composition in each replicate (n=10) of each treatment at CDG and SGS sites. There were no significant pre-treatment differences in ANPP or plant species richness at either site. In 2013 following an above average monsoon, ambient ANPP was 99.4 g m-2 at CDG and 44.3 g m-2 at SGS. Event size reduction resulted in a 75% reduction in ANPP at CDG but only a 33% reduction in ANPP at SGS. Shifting the monsoon to later in the growing season resulted in a 50% and 43% reduction in ANPP at CDG and SGS, respectively. Thus, ANPP at CDG partially recovered from the mid-summer drought with late season precipitation but SGS did not. Event size reduction also resulted in a decrease in species richness at CDG, but not at SGS. These short

  10. Impact of drought and precipitation seasonality on net primary production and plant community composition across a grassland ecotone in New Mexico

    NASA Astrophysics Data System (ADS)

    Collins, Scott; Thomey, Michell; Brown, Renee; Gehres, Nate; Petrie, Matthew; Vanderbilt, Kristin; Pockman, William

    2015-04-01

    In the southwestern US, climate change will impact the amount, timing and variability of rainfall during the summer monsoon. Changes in amount and seasonality of precipitation are likely to affect plant community dynamics and ecosystem processes, especially along ecotones. In 2012, we established a rainfall manipulation experiment (EDGE-Extreme Drought in Grasslands Experiment) in Chihuahuan Desert grassland (CDG) dominated by black grama and shortgrass steppe (SGS) dominated by blue grama across a grassland ecotone in central New Mexico. EDGE includes two rainfall treatments, chronic drought (~66% reduction in monsoon rainfall) and altered timing of the summer monsoon. Chronic drought is imposed from July through September by rainout shelters with roof panels that cover 66% of the surface area. To alter precipitation seasonality complete rainout shelters are erected in July and August, and all rainfall that occurred during this period is captured, stored, and then reapplied in several large rain events during September and October. Thus, this treatment receives the same amount of precipitation as ambient but differs in seasonality and frequency of rain events. We measured soil moisture, aboveground net primary production (ANPP), and plant species composition in each replicate (n=10) of each treatment at CDG and SGS sites. There were no significant pre-treatment differences in ANPP or plant species richness at either site. In 2013 following an above average monsoon, ambient ANPP was 99.4 g m-2 at CDG and 44.3 g m-2 at SGS. Event size reduction resulted in a 75% reduction in ANPP at CDG but only a 33% reduction in ANPP at SGS. Shifting the monsoon to later in the growing season resulted in a 50% and 43% reduction in ANPP at CDG and SGS, respectively. Thus, ANPP at CDG partially recovered from the mid-summer drought with late season precipitation but SGS did not. Event size reduction also resulted in a decrease in species richness at CDG, but not at SGS. These short

  11. Switchgrass: Production, Economics, and Net Energy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The critical questions for a biomass bioenergy production system are: • What are the economics? • Is energy from biomass net energy positive? • Is production system information available and verified? • Is the system sustainable? To address these questions, ten farmers in the mid-continental USA w...

  12. Patterns of net primary production across sites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Net primary production (NPP) is a fundamentally important and commonly measured ecosystem process that provides an integrative estimate of energy capture and flow into systems, and consequently the energy available for use by other trophic levels. A wide range of productivity levels occurs globally ...

  13. QUANTIFYING UNCERTAINTY IN NET PRIMARY PRODUCTION MEASUREMENTS

    EPA Science Inventory

    Net primary production (NPP, e.g., g m-2 yr-1), a key ecosystem attribute, is estimated from a combination of other variables, e.g. standing crop biomass at several points in time, each of which is subject to errors in their measurement. These errors propagate as the variables a...

  14. Net ecosystem production in a subarctic peatland

    SciTech Connect

    Luken, J.O.

    1984-01-01

    A mass balance approach was used to determine the rates of carbon storage in three areas of a subarctic bog near Fairbanks, Alaska (latitude 64/sup 0/52'N). Aboveground net primary production was 20.3, 74.2, and 77.4 gm/sup -2/yr/sup -1/ for nonvascular plants, the shrub and herb layer, and the tree layer of the bog forest, respectively. Aboveground net primary production was 83.7 and 58.2 g m/sup -2/yr/sup -1/ for nonvascular plants and the shrub and herb layer of the Andromeda bog, respectively, in the Carex lawns, aboveground net primary production was 194.9 and 111.7 g m/sup -2/yr/sup -1/ for nonvascular and vascular plants, respectively. Sphagnum mosses are important components of this peatbog ecosystem due to their high rates of net primary production and slow rates of decomposition. Experimental manipulations of light level, water table level, and nutrient availability indicated that terminal extension rates and volumetric density of the Sphagnum stands are controlled primarily by light and water table levels. An explanation of Sphagnum zonation in hummock-hollow complexes is presented which incorporates aspects of growth rate, stand morphology, and reproductive mode. Soil carbon dioxide efflux rates were measured in a number of different hummock-hollow microhabitats. Approximately 75% of the variance associated with soil respiration could be explained by regression equations with soil moisture and soil temperature as independent variables. Carbohydrate limitation of soil microbial populations was demonstrated in both laboratory and field experiments.

  15. Advancing netCDF-CF for the Geoscience Community

    NASA Astrophysics Data System (ADS)

    Davis, Ethan; Zender, Charlie; Arctur, David; Jelenak, Aleksandar; Santek, Dave; O'Brien, Kevin; Dixon, Mike

    2016-04-01

    The Climate and Forecast (CF) metadata conventions for netCDF (netCDF-CF) are used widely by weather forecasters, climate scientists, and remote-sensing researchers to include auxiliary information along with scientific data. This auxiliary information, or metadata, describes where and how the data were collected, the units of measurement used, and other similar details. Numerous open source and commercial software tools are able to explore and analyze data sets that include netCDF-CF metadata. This presentation will introduce work to extend the existing netCDF-CF metadata conventions in ways that will broaden the range of earth science domains whose data can be represented. It will include discussion of the enhancements to netCDF-CF that are envisioned and information on how to participate in the community-based standards development process.

  16. A model of global net ecosystem production

    SciTech Connect

    Potter, C.S.; Matson, P.A. ); Field, C.B.; Randerson, J. ); Vitousek, P.M.; Mooney, H.A. )

    1993-06-01

    We present an ecosystem modeling approach to resolve global climate and edaphic controls on seasonal NEP patterns. Global remote sensing, climate and land surface data sets are used as inputs to drive a terrestrial carbon cycle model at 1[degrees]lat/lon resolution. monthly net primary productivity (NPP) is calculated using surface radiation and NDVI to determine photosynthesis, which is subsequently adjusted by temperature, water and nitrogen stress factors. Total nitrogen availability is coupled to net mineralization rates from litter soil carbon pools. Soil respiration and NPP balance one another globally at around 60 Gt C yr[sup [minus]1]. The seasonal amplitude of global NEP is 1.2 Gt C. Although substantial month-to-month variation is observed for tropical forest areas, seasonal amplitude is driven globally by boreal and temperate forest ecosystems between 650 and 30[degrees] N latitude.

  17. LabNet: Toward a community of practice

    NASA Astrophysics Data System (ADS)

    Ruopp, Richard

    1993-03-01

    It is common currency that science education in America isn't working well enough. We are failing to excite the curiosity of young minds in the great questions of the physical universe. LabNet—a prototype teacher-support project developed by TERC, and funded by the National Science Foundation, is dedicated to addressing this issue. The first three year phase of LabNet began in January 1989 and ended in mid-1992. During that time, some 562 high school teachers of physics in 37 states were involved. Three interconnected threads are woven through the fabric of LabNet. The first, and most vivid, is the use of projects to enhance students' science learning. LabNet's second thread is building a community of practice among LabNet teachers. The third thread woven into LabNet is promoting the use of new technologies in science teaching and learning. The most notable use of new technology in the LabNet project is telecommunications—computer-to-computer communication via telephone lines. A dedicated network has been created and made available to all participants. As the first national network designed for high school teachers of physical science, the LabNetwork is a dynamic medium for building and sustaining a community of practice for physics teachers separated by many thousands of miles. In recommendations directed at teachers, scientists, and particularly the National Science Foundation, steps are outlined that can be taken to strengthen the community and the teaching of science in both the secondary and elementary grades.

  18. Community Net Energy Metering: How Novel Policies Expand Benefits of Net Metering to Non-Generators

    SciTech Connect

    Rose, James; Varnado, Laurel

    2009-04-01

    As interest in community solutions to renewable energy grows, more states are beginning to develop policies that encourage properties with more than one meter to install shared renewable energy systems. State net metering policies are evolving to allow the aggregation of multiple meters on a customer’s property and to dissolve conventional geographical boundaries. This trend means net metering is expanding out of its traditional function as an enabling incentive to offset onsite customer load at a single facility. This paper analyzes community net energy metering (CNEM) as an emerging vehicle by which farmers, neighborhoods, and municipalities may more easily finance and reap the benefits of renewable energy. Specifically, it aims to compare and contrast the definition of geographical boundaries among different CNEM models and examine the benefits and limitations of each approach. As state policies begin to stretch the geographic boundaries of net metering, they allow inventive solutions to encourage renewable energy investment. This paper attempts to initiate the conversation on this emerging policy mechanism and offers recommendations for further development of these policies.

  19. Global Patterns in Human Consumption of Net Primary Production

    NASA Technical Reports Server (NTRS)

    Imhoff, Marc L.; Bounoua, Lahouari; Ricketts, Taylor; Loucks, Colby; Harriss, Robert; Lawrence William T.

    2004-01-01

    The human population and its consumption profoundly affect the Earth's ecosystems. A particularly compelling measure of humanity's cumulative impact is the fraction of the planet's net primary production that we appropriate for our Net primary production-the net amount of solar energy converted to plant organic matter through photosynthesis-can be measured in units of elemental carbon and represents the primary food energy source for the world's ecosystems. Human appropriation of net primary production, apart from leaving less for other species to use, alters the composition of the atmosphere, levels of biodiversity, flows within food webs and the provision of important primary production required by humans and compare it to the total amount generated on the landscape. We then derive a spatial ba!mce sheet of net primary production supply and demand for the world. We show that human appropriation of net primary production varies spatially from almost zero to many times the local primary production. These analyses reveal the uneven footprint of human consumption and related environmental impacts, indicate the degree to which human populations depend on net primary production "imports" and suggest policy options for slowing future growth of human appropriation of net primary production.

  20. Net Community and Gross Photosynthetic Production Rates in the Eastern Tropical South Pacific, as Determined from O2/AR Ratios and Triple Oxygen Isotopic Composition of Dissolved O2

    NASA Astrophysics Data System (ADS)

    Prokopenko, M. G.; Yeung, L. Y.; Berelson, W.; Fleming, J.; Rollins, N.; Young, E. D.; Haskell, W. Z.; Hammond, D. E.; Capone, D. G.

    2010-12-01

    This study assesses the rates of ocean carbon production and its fate with respect to recycling or export in the Eastern Tropical South Pacific (ETSP). ETSP has been previously identified as a region where N2 fixation and denitrification may be spatially coupled; this is also a region of localized CO2 outgassing. Using an Equilibrated Inlet Mass Spectrometer (EIMS) system, we obtained continuous measurements of the biological O2 supersaturation in the mixed layer along the ship track encompassing a region bounded by 10-20° S and 80-100° W in January - March, 2010. Vertical profiles were also taken at selected stations and analyzed for dissolved O2/Ar ratios on EIMS and triple oxygen isotope composition (17O excess) on a multi-collector IRMS (Isotope Ratio Mass Spectrometer) at UCLA. Gas exchange rates were estimated using two approaches: the Rn-222 deficit method and the wind parameterization method, which utilized wind speeds extracted from ASCAT satellite database. Oxygen Net Community Production (O-NCP) rates calculated based on biological O2 supersaturation ranged from slightly negative to ~ 0.3 - 15 mmol/m2d, with higher rates along the northern part of the transect. Oxygen Gross Community Production (O-GPP) rates calculated from 17O excess were between 50 ± 20 and 200 ± 40 mmol/m2d, with higher rates observed along the northern cruise transect as well. Notably, the NCP/GPP ratios along the northern transect were higher by the factor of 2 to 3 than their southern counterparts. The O2/Ar-based NCP rates were comparable to POC flux measured with floating traps deployed at the southern stations, but exceeded by a factor of 5-10 the trap POC fluxes obtained at the northern stations. A one-dimensional box model has been constructed to quantify the magnitude of oxygen primary production below the mixed layer. The results of this work will be integrated with measurements of 15-N2 uptake that are in progress, to constrain the potential contribution of N2 fixation

  1. Estimating Net Primary Productivity Using Satellite and Ancillary Data

    NASA Technical Reports Server (NTRS)

    Choudhury, Bhaskar J.

    2002-01-01

    The net primary productivity (C) or the annual rate of carbon accumulation per unit ground area by terrestrial plant communities is the difference of gross photosynthesis (A(sub g)) and respiration (R) per unit ground area. Available field observations show that R is a large and variable fraction of A(sub g), although it is generally recognized that there are considerable difficulties in determining these fluxes, and thus pose challenge in assessing the accuracy. Further uncertainties arise in extrapolating field measurements (which are acquired over a hectare or so area) to regional scale. Here, an approach is presented for determining these fluxes using satellite and ancillary data to be representative of regional scale and allow assessment of interannual variation. A, has been expressed as the product of radiation use efficiency for gross photosynthesis by an unstressed canopy and intercepted photosynthetically active radiation, which is then adjusted for stresses due to soil water shortage and temperature away from optimum. R has been calculated as the sum of growth and maintenance components (respectively, R(sub g) and R(sub m)).The R(sub m) has been determined from nitrogen content of plant tissue per unit ground area, while R(sub g) has been obtained as a fraction of the difference of A(sub g) and R(sub m). Results for five consecutive years (1986-1990) are presented for the Amazon-Tocontins, Mississippi, and Ob River basins.

  2. Environmental controls on daytime net community calcification on a Red Sea reef flat

    NASA Astrophysics Data System (ADS)

    Bernstein, W. N.; Hughen, K. A.; Langdon, C.; McCorkle, D. C.; Lentz, S. J.

    2016-06-01

    Coral growth and carbonate accumulation form the foundation of the coral reef ecosystem. Changes in environmental conditions due to coastal development, climate change, and ocean acidification may pose a threat to net carbonate production in the near future. Controlled laboratory studies demonstrate that calcification by corals and coralline algae is sensitive to changes in aragonite saturation state (Ωa), as well as temperature, light, and nutrition. Studies also show that the dissolution rate of carbonate substrates is impacted by changes in carbonate chemistry. The sensitivity of coral reefs to these parameters must be confirmed and quantified in the natural environment in order to predict how coral reefs will respond to local and global changes, particularly ocean acidification. We estimated the daytime hourly net community metabolic rates, both net community calcification (NCC) and net community productivity (NCP), at Sheltered Reef, an offshore platform reef in the central Red Sea. Average NCC was 8 ± 3 mmol m-2 h-1 in December 2010 and 11 ± 1 mmol m-2 h-1 in May 2011, and NCP was 21 ± 7 mmol m-2 h-1 in December 2010 and 44 ± 4 mmol m-2 h-1 in May 2011. We also monitored a suite of physical and chemical properties to help relate the rates at Sheltered Reef to published rates from other sites. While previous research shows that short-term field studies investigating the NCC-Ωa relationship have differing results due to confounding factors, it is important to continue estimating NCC in different places, seasons, and years, in order to monitor changes in NCC versus Ω in space and time, and to ultimately resolve a broader understanding of this relationship.

  3. BreadNet: An On-Line Community.

    ERIC Educational Resources Information Center

    Walker, Susan

    1987-01-01

    Describes BreadNet, a computer network linking Middlebury College English teachers, their associates, and students. Network extends to rural English teachers and their K-8 students. BreadNet used for student pen pal program, teacher teleconferencing, information access. Also describes BreadNet's problems and future possibilities. (TES)

  4. Net ecosystem production: A comprehensive measure of net carbon accumulation by ecosystems

    USGS Publications Warehouse

    Randerson, J.T.; Chapin, F. S., III; Harden, J.W.; Neff, J.C.; Harmon, M.E.

    2002-01-01

    The conceptual framework used by ecologists and biogeochemists must allow for accurate and clearly defined comparisons of carbon fluxes made with disparate techniques across a spectrum of temporal and spatial scales. Consistent with usage over the past four decades, we define "net ecosystem production" (NEP) as the net carbon accumulation by ecosystems. Past use of this term has been ambiguous, because it has been used conceptually as a measure of carbon accumulation by ecosystems, but it has often been calculated considering only the balance between gross primary production (GPP) and ecosystem respiration. This calculation ignores other carbon fluxes from ecosystems (e.g., leaching of dissolved carbon and losses associated with disturbance). To avoid conceptual ambiguities, we argue that NEP be defined, as in the past, as the net carbon accumulation by ecosystems and that it explicitly incorporate all the carbon fluxes from an ecosystem, including autotrophic respiration, heterotrophic respiration, losses associated with disturbance, dissolved and particulate carbon losses, volatile organic compound emissions, and lateral transfers among ecosystems. Net biome productivity (NBP), which has been proposed to account for carbon loss during episodic disturbance, is equivalent to NEP at regional or global scales. The multi-scale conceptual framework we describe provides continuity between flux measurements made at the scale of soil profiles and chambers, forest inventories, eddy covariance towers, aircraft, and inversions of remote atmospheric flask samples, allowing a direct comparison of NEP estimates made at all temporal and spatial scales.

  5. Global climate change and terrestrial net primary production

    NASA Technical Reports Server (NTRS)

    Melillo, Jerry M.; Mcguire, A. D.; Kicklighter, David W.; Moore, Berrien, III; Vorosmarty, Charles J.; Schloss, Annette L.

    1993-01-01

    A process-based model was used to estimate global patterns of net primary production and soil nitrogen cycling for contemporary climate conditions and current atmospheric CO2 concentration. Over half of the global annual net primary production was estimated to occur in the tropics, with most of the production attributable to tropical evergreen forest. The effects of CO2 doubling and associated climate changes were also explored. The responses in tropical and dry temperate ecosystems were dominated by CO2, but those in northern and moist temperate ecosystems reflected the effects of temperature on nitrogen availability.

  6. Human Appropriation of Net Primary Production - Can Earth Keep Up?

    NASA Technical Reports Server (NTRS)

    Imhoff, Marc L.

    2006-01-01

    The amount of Earth's vegetation or net primary production required to support human activities is powerful measure of aggregate human impacts on the biosphere. Biophysical models applied to consumption statistics were used to estimate the annual amount of net primary production in the form of elemental carbon required for food, fibre, and fuel-wood by the global population. The calculations were then compared to satellite-based estimates of Earth's average net primary production to produce a geographically explicit balance sheet of net primary production "supply" and "demand". Humans consume 20% of Earth's net primary production (11.5 petagrams carbon) annually and this percentage varies regionally from 6% (South America) to over 70% (Europe and Asia), and locally from near 0% (central Australia) to over 30,000% (New York City, USA). The uneven footprint of human consumption and related environmental impacts, indicate the degree to which human populations are vulnerable to climate change and suggest policy options for slowing future growth of NPP demand.

  7. An Evaluation of California's Community College Based Economic Development Programs (ED>Net).

    ERIC Educational Resources Information Center

    Bowman (James) Associates, San Francisco, CA.

    This study describes economic outcomes of California's ED>Net (California Community College Economic Network) program, an alliance between community colleges and California businesses. ED>Net's purpose is to advance the state's economic growth by providing job-related education and services to businesses and organizations. This report develops…

  8. Community of Practice Applications from WaterNet: The NASA Water Cycle Solutions Network

    NASA Astrophysics Data System (ADS)

    Matthews, D.; Brilly, M.; Gregoric, G.; Polajnar, J.; Houser, P.; Rodell, M.; Lehning, M.

    2009-04-01

    WaterNet is a new international network of researchers, stakeholders, and end-users of remote sensing tools that will benefit the water resources management community. It addresses a means for enhancing the social and economic developments of nations by increased use of practical research products from the terrestrial water cycle for making informed decisions. This paper provides a summary of the Water Cycle Community of Practice (CoP) plans and examples of Land Surface Model (LSM) applications for extreme events - floods, droughts, and heavy snowstorms in Europe. It discusses the concept of NASA's solutions networks focusing on the WaterNet. It invites EGU teams to join our WaterNet network. The NASA Water cycle Solutions Network's goal is to improve and optimize the sustained ability of water cycle researchers, stakeholders, organizations and networks to interact, identify, harness, and extend NASA research results to augment decision support tools and meet national needs. Our team is developing WaterNet by engaging relevant NASA water cycle research and community-of-practice organizations, to develop what we term an "actionable database" that can be used to communicate and connect NASA Water cycle research Results (NWRs) towards the improvement of water-related Decision Support Tools (DSTs). Recognizing that the European Commission and European Space Agency have also developed many related research products (EWRs), we seek to learn about these and network with the EU teams to include their information in the WaterNet actionable data base. Recognizing the many existing highly valuable water-related science and application networks in the US and EU, we focus the balance of our efforts on enabling their interoperability - facilitating access and communications among decision-makers and scientists. We present results of our initial focus on identification, collection, and analysis of the two end points, these being the NWRs and EWRs and water related DSTs. We

  9. Net loss of CaCO3 from coral reef communities due to human induced seawater acidification

    NASA Astrophysics Data System (ADS)

    Andersson, A. J.; Kuffner, I. B.; MacKenzie, F. T.; Jokiel, P. L.; Rodgers, K. S.; Tan, A.

    2009-02-01

    Acidification of seawater owing to oceanic uptake of atmospheric CO2 originating from human activities such as burning of fossil fuels and land-use changes has raised serious concerns for its adverse effects on corals, coral reefs and carbonate communities in general. Here we demonstrate a transition from net accumulation towards net loss of calcium carbonate (CaCO3) material owing to decreased calcification and increased carbonate dissolution from replicated subtropical coral reef communities (n=3) incubated in continuous-flow mesocosms subject to present and future seawater conditions. The calcifying community was dominated by the coral Montipora capitata. Daily average community calcification or Net Ecosystem Calcification (NEC = CaCO3 production - dissolution) was positive at 4.5 mmol CaCO3 m-2 h-1 under ambient seawater pCO2 conditions as opposed to negative at -0.1 mmol CaCO3 m-2 h-1 under seawater conditions of double the ambient pCO2. These experimental results provide support for the conclusion that some net calcifying communities could become subject to net dissolution in response to anthropogenic ocean acidification within this century.

  10. NETS

    NASA Technical Reports Server (NTRS)

    Baffes, Paul T.

    1993-01-01

    NETS development tool provides environment for simulation and development of neural networks - computer programs that "learn" from experience. Written in ANSI standard C, program allows user to generate C code for implementation of neural network.

  11. Summary of the first network-centric sensing community workshop, 'netted sensors: a government, industry, and academia dialogue'

    NASA Astrophysics Data System (ADS)

    Tromp, Laurens D.; Jacyna, Garry M.; Allen, David P.

    2006-05-01

    The MITRE Corporation recently hosted the first Netted Sensors Community Workshop in McLean, Virginia, on 24 October - 26 October 2005. The Workshop was sponsored by the Defense Advanced Research Projects Agency (DARPA), Office of the Secretary of Defense (OSD) Director of Defense Research and Engineering (DDR&E), and the National Science Foundation (NSF). The goal was to establish and sustain an annual Netted Sensors workshop that brings together Government, Industry and Academia to accelerate the development and transition of appropriate Netted Sensor technologies to solve real world problems. The workshop provided a forum focused on the application of netted sensing research and development (R&D) activities to solve existing and future Department of Defense (DoD), Intelligence Community (IC), Department of Homeland Security (DHS), and Environmental sensing problems. The Netted Sensors workshop brought together the Science and Technology (S&T) community, Industry, and Government / Military organizations to (1) share, discuss and disseminate new R&D results, (2) highlight new commercial products and technologies, and (3) identify and discuss nationally important sensing problems suitable for Netted Sensing solutions. This paper provides a summary of the presentations that were made at the workshop as well as recommendations for future workshops.

  12. Forecasting annual aboveground net primary production in the intermountain west

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For many land manager’s annual aboveground net primary production, or plant growth, is a key factor affecting business success, profitability and each land manager's ability to successfully meet land management objectives. The strategy often utilized for forecasting plant growth is to assume every y...

  13. Chapter 12. Net primary production in the shortgrass steppe

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Net primary production (NPP), the amount of carbon or energy fixed by green plants in excess of their respiratory needs, is the fundamental quantity upon which all heterotrophs and the ecosystem processes they are associated with depend. Understanding NPP is therefore a prerequisite to understanding...

  14. CLIMATE CHANGE IMPACTS OF NET PRIMARY PRODUCTION IN CHINA

    EPA Science Inventory

    Several studies have estimated the potential effects of greenhouse gas-induced climate change on various systems using outputs of general circulation models (GCMs). he purpose of this study was to generate comparable estimates of potential impacts on net primary production using ...

  15. Quantifying Annual Aboveground Net Primary Production in the Intermountain West

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As part of a larger project, methods were developed to quantify current year growth on grasses, forbs, and shrubs. Annual aboveground net primary production (ANPP) data are needed for this project to calibrate results from computer simulation models and remote-sensing data. Measuring annual ANPP of ...

  16. Net energy analysis of alcohol production from sugarcane

    SciTech Connect

    Hopkinson, C.S. Jr.; Day, J.W. Jr.

    1980-01-18

    Energy requirements were calculated for the agricultural and the industrial phase of ethyl alcohol production from sugarcane grown in Louisiana. Agricultural energy requirements comprised 54% of all energy inputs, with machinery, fuel, and nitrogen fertilizer representing most of the energy subsidies. Overall net energy benefits (output:input) for alcohol production ranged from 1.8:1 to 0.9:1 depending on whether crop residues or fossil fuels were used for industrial processes.

  17. Community of Practice Applications from WaterNet: The NASA Water Cycle Solutions Network

    NASA Astrophysics Data System (ADS)

    Matthews, D.; Brilly, M.; Gregoric, G.; Polajnar, J.; Houser, P.; Rodell, M.; Lehning, M.

    2009-04-01

    WaterNet is a new international network of researchers, stakeholders, and end-users of remote sensing tools that will benefit the water resources management community. It addresses a means for enhancing the social and economic developments of nations by increased use of practical research products from the terrestrial water cycle for making informed decisions. This paper provides a summary of the Water Cycle Community of Practice (CoP) plans and examples of Land Surface Model (LSM) applications for extreme events - floods, droughts, and heavy snowstorms in Europe. It discusses the concept of NASA's solutions networks focusing on the WaterNet. It invites EGU teams to join our WaterNet network. The NASA Water cycle Solutions Network's goal is to improve and optimize the sustained ability of water cycle researchers, stakeholders, organizations and networks to interact, identify, harness, and extend NASA research results to augment decision support tools and meet national needs. Our team is developing WaterNet by engaging relevant NASA water cycle research and community-of-practice organizations, to develop what we term an "actionable database" that can be used to communicate and connect NASA Water cycle research Results (NWRs) towards the improvement of water-related Decision Support Tools (DSTs). Recognizing that the European Commission and European Space Agency have also developed many related research products (EWRs), we seek to learn about these and network with the EU teams to include their information in the WaterNet actionable data base. Recognizing the many existing highly valuable water-related science and application networks in the US and EU, we focus the balance of our efforts on enabling their interoperability - facilitating access and communications among decision-makers and scientists. We present results of our initial focus on identification, collection, and analysis of the two end points, these being the NWRs and EWRs and water related DSTs. We

  18. Net loss of CaCO3 from coral reef communities due to human induced seawater acidification

    USGS Publications Warehouse

    Andersson, A.J.; Kuffner, I.B.; MacKenzie, F.T.; Jokiel, P.L.; Rodgers, K.S.; Tan, A.

    2009-01-01

    Acidification of seawater owing to oceanic uptake of atmospheric CO2 originating from human activities such as burning of fossil fuels and land-use changes has raised serious concerns regarding its adverse effects on corals and calcifying communities. Here we demonstrate a net loss of calcium carbonate (CaCO3) material as a result of decreased calcification and increased carbonate dissolution from replicated subtropical coral reef communities (n=3) incubated in continuous-flow mesocosms subject to future seawater conditions. The calcifying community was dominated by the coral Montipora capitata. Daily average community calcification or Net Ecosystem Calcification (NEC=CaCO3 production – dissolution) was positive at 3.3 mmol CaCO3 m−2 h−1 under ambient seawater pCO2 conditions as opposed to negative at −0.04 mmol CaCO3 m−2h−1 under seawater conditions of double the ambient pCO2. These experimental results provide support for the conclusion that some net calcifying communities could become subject to net dissolution in response to anthropogenic ocean acidification within this century. Nevertheless, individual corals remained healthy, actively calcified (albeit slower than at present rates), and deposited significant amounts of CaCO3 under the prevailing experimental seawater conditions of elevated pCO2.

  19. Designing Interoperable Data Products with Community Conventions

    NASA Astrophysics Data System (ADS)

    Habermann, T.; Jelenak, A.; Lee, H.

    2015-12-01

    The HDF Product Designer (HPD) is a cloud-based client-server collaboration tool that can bring existing netCDF-3/4/CF, HDF4/5, and HDF-EOS2/5 products together to create new interoperable data products that serve the needs of the Earth Science community. The tool is designed to reduce the burden of creating and storing data in standards-compliant, interoperable HDF5 files and lower the technical and programming skill threshold needed to design such products by providing a user interface that combines the netCDF-4/HDF5 interoperable feature set with applicable metadata conventions. Users can collaborate quickly to devise new HDF5 products while at the same time seamlessly incorporating the latest best practices and conventions in their community by importing existing data products. The tool also incorporates some expert system features through CLIPS, allowing custom approaches in the file design, as well as easy transfer of preferred conventions as they are being developed. The current state of the tool and the plans for future development will be presented. Constructive input from any interested parties is always welcome.

  20. Sea-ice melt CO2-carbonate chemistry in the western Arctic Ocean: meltwater contributions to air-sea CO2 gas exchange, mixed layer properties and rates of net community production under sea ice

    NASA Astrophysics Data System (ADS)

    Bates, N. R.; Garley, R.; Frey, K. E.; Shake, K. L.; Mathis, J. T.

    2014-01-01

    The carbon dioxide (CO2)-carbonate chemistry of sea-ice melt and co-located, contemporaneous seawater has rarely been studied in sea ice covered oceans. Here, we describe the CO2-carbonate chemistry of sea-ice melt (both above sea ice as "melt ponds" and below sea ice as "interface waters") and mixed layer properties in the western Arctic Ocean in the early summer of 2010 and 2011. At nineteen stations, the salinity (~ 0.5 to < 6.5), dissolved inorganic carbon (DIC; ~ 20 to < 550 μmol kg-1) and total alkalinity (TA; ~ 30 to < 500 μmol kg-1) of above-ice melt pond water was low compared to water in the underlying mixed layer. The partial pressure of CO2 (pCO2) in these melt ponds was highly variable (~ < 10 to > 1500 μatm) with the majority of melt ponds acting as potentially strong sources of CO2 to the atmosphere. The pH of melt pond waters was also highly variable ranging from mildly acidic (6.1 to 7) to slightly more alkaline than underlying seawater (8 to 10.7). All of observed melt ponds had very low (< 0.1) saturation states (Ω) for calcium carbonate (CaCO3) minerals such as aragonite (Ωaragonite). Our data suggests that sea ice generated "alkaline" or "acidic" melt pond water. This melt-water chemistry dictates whether the ponds are sources of CO2 to the atmosphere or CO2 sinks. Below-ice interface water CO2-carbonate chemistry data also indicated substantial generation of alkalinity, presumably owing to dissolution of calcium CaCO3 in sea ice. The interface waters generally had lower pCO2 and higher pH/Ωaragonite than the co-located mixed layer beneath. Sea-ice melt thus contributed to the suppression of mixed layer pCO2 enhancing the surface ocean's capacity to uptake CO2 from the atmosphere. Meltwater contributions to changes in mixed-layer DIC were also used to estimate net community production rates (mean of 46.9 ±29.8 g C m-2 for the early-season period) under sea-ice cover. Although sea-ice melt is a transient seasonal feature, above-ice melt

  1. Local Area Network: Community Involvement, Social Capital, and Glocalization at NetU

    ERIC Educational Resources Information Center

    Trevett-Smith, Matthew D.

    2010-01-01

    Ethnographic and interview data from a long-term study of "NetU," a wired community and college, are used to investigate the effects of computer-mediated communication on social relationships. During the course of this research "LAN" residents of NetU are compared with a similar group of non-LAN residents who lived in the same neighborhood, but…

  2. Economic Investigation of Community-Scale Versus Building Scale Net-Zero Energy

    SciTech Connect

    Fernandez, Nicholas; Katipamula, Srinivas; Brambley, Michael R.; Reddy, T. A.

    2009-12-31

    The study presented in this report examines issues concerning whether achieving net-zero energy performance at the community scale provides economic and potentially overall efficiency advantages over strategies focused on individual buildings.

  3. Estimating Net Primary Productivity Using Satellite and Ancillary Data

    NASA Technical Reports Server (NTRS)

    Choudhury, B. J.; Houser, Paul (Technical Monitor)

    2001-01-01

    The net primary productivity (C) or annual rate of carbon accumulation per unit ground area by terrestrial plant communities is the difference of the rate of gross photosynthesis (A(sub g)) and autotrophic respiration (R) per unit ground area. Although available observations show that R is a large and variable fraction of A(sub g), viz., 0.3 to 0.7, it is generally recognized that much uncertainties exist in this fraction due to difficulties associated with the needed measurements. Additional uncertainties arise when these measurements are extrapolated to regional or global land surface using empirical equations, for example, using regression equations relating C to mean annual precipitation and air temperature. Here, a process-based approach has been taken to calculate A(sub g) and R using satellite and ancillary data. A(sub g) has been expressed as a product of radiation use efficiency, magnitude of intercepted photosynthetically active radiation (PAR), and normalized by stresses due to soil water shortage and air temperature away from the optimum range. A biophysical model has been used to determine the radiation use efficiency from the maximum rate of carbon assimilation by a leaf, foliage temperature, and the fraction of diffuse PAR incident on a canopy. All meteorological data (PAR, air temperature, precipitation, etc.) needed for the calculation are derived from satellite observations, while a land use, land cover data (based on satellite and ground measurements) have been used to assess the maximum rate of carbon assimilation by a leaf of varied cover type based on field measurements. R has been calculated as the sum of maintenance and growth components. The maintenance respiration of foliage and live fine roots at a standard temperature of different land cover has been determined from their nitrogen content using field and satellite measurements, while that of living fraction of woody stem (viz., sapwood) from the seasonal maximum leaf area index as

  4. EcoVillage: A Net Zero Energy Ready Community

    SciTech Connect

    Arena, L.; Faakye, O.

    2015-02-01

    CARB is working with the EcoVillage co-housing community in Ithaca, New York, on their third neighborhood called the Third Residential EcoVillage Experience (TREE). This community scale project consists of 40 housing units --15 apartments and 25 single family residences. The community is pursuing certifications for DOE Zero Energy Ready Home, U.S. Green Building Council Leadership in Energy and Environmental Design Gold, and ENERGY STAR for the entire project. Additionally, seven of the 25 homes, along with the four-story apartment building and community center, are being constructed to the Passive House (PH) design standard.

  5. Global net primary production and heterotrophic respiration for 1987

    SciTech Connect

    Hunt, R.E. Jr.; Piper, S.C.; Nemani, R. |

    1995-06-01

    An ecosystem process model, BIOME-BGC, was parameterized and used to simulate the actual net primary production and heterotrophic respiration using daily climatic data, land cover type, leaf area index gridded to 1{degree} latitude by 1{degree} longitude grid cells for the year 1987. Global net primary production was 52 Pg C. These estimates were validated directly by two different methods. First, the grid cells were aggregated and used as inputs to a 3D atmospheric transport model, to compare CO{sub 2} station data with predictions. We simulated the intra-annual variation of atmospheric CO{sub 2} well for the northern hemisphere, but not for the southern hemisphere. Second, we calculated the net {sup 13}C uptake of vegetation, which is a function of water use efficiency. The {sup 13}C/{sup 12}C ratios agreed with measured data, indicating a strong limitation of global primary processes by the hydrologic cycle, especially precipitation. These are different from other global carbon models as we can simulate the year-to-year variation of climate, including El Nino, on the global carbon cycle.

  6. Shadow netWorkspace: An Open Source Intranet for Learning Communities

    ERIC Educational Resources Information Center

    Laffey, James M.; Musser, Dale

    2006-01-01

    Shadow netWorkspace (SNS) is a web application system that allows a school or any type of community to establish an intranet with network workspaces for all members and groups. The goal of SNS has been to make it easy for schools and other educational organizations to provide network services in support of implementing a learning community. SNS is…

  7. Net carbon flux in organic and conventional olive production systems

    NASA Astrophysics Data System (ADS)

    Saeid Mohamad, Ramez; Verrastro, Vincenzo; Bitar, Lina Al; Roma, Rocco; Moretti, Michele; Chami, Ziad Al

    2014-05-01

    Agricultural systems are considered as one of the most relevant sources of atmospheric carbon. However, agriculture has the potentiality to mitigate carbon dioxide mainly through soil carbon sequestration. Some agricultural practices, particularly fertilization and soil management, can play a dual role in the agricultural systems regarding the carbon cycle contributing to the emissions and to the sequestration process in the soil. Good soil and input managements affect positively Soil Organic Carbon (SOC) changes and consequently the carbon cycle. The present study aimed at comparing the carbon footprint of organic and conventional olive systems and to link it to the efficiency of both systems on carbon sequestration by calculating the net carbon flux. Data were collected at farm level through a specific and detailed questionnaire based on one hectare as a functional unit and a system boundary limited to olive production. Using LCA databases particularly ecoinvent one, IPCC GWP 100a impact assessment method was used to calculate carbon emissions from agricultural practices of both systems. Soil organic carbon has been measured, at 0-30 cm depth, based on soil analyses done at the IAMB laboratory and based on reference value of SOC, the annual change of SOC has been calculated. Substracting sequestrated carbon in the soil from the emitted on resulted in net carbon flux calculation. Results showed higher environmental impact of the organic system on Global Warming Potential (1.07 t CO2 eq. yr-1) comparing to 0.76 t CO2 eq. yr-1 in the conventional system due to the higher GHG emissions caused by manure fertilizers compared to the use of synthetic foliar fertilizers in the conventional system. However, manure was the main reason behind the higher SOC content and sequestration in the organic system. As a resultant, the organic system showed higher net carbon flux (-1.7 t C ha-1 yr-1 than -0.52 t C ha-1 yr-1 in the conventional system reflecting higher efficiency as a

  8. Evaluating North American net primary productivity with satellite observations

    NASA Technical Reports Server (NTRS)

    Goward, Samuel N.; Dye, Dennis G.

    1987-01-01

    An ecological model is developed to estimate annual net primary productivity (NPP) in 12 North American biomes. The model combines existing models which address canopy photosynthesis in response to light, temperature, and moisture availability, and account for respiration. Climate data, solar radiation data, and spectral vegetation index data are utilized. Estimates of NPP from the model compare well with data in the literature, but a systematic error is suspected. Difficulties encountered in specifying certain model parameters are discussed as possible sources of this error. The results of this study suggest the promise of remotely sensed measurements for macroscale evaluation and modeling of NPP.

  9. Evaluating North American net primary productivity with satellite observations

    NASA Astrophysics Data System (ADS)

    Goward, Samuel N.; Dye, Dennis G.

    An ecological model is developed to estimate annual net primary productivity in twelve North American biomes. Existing models were combined which together address canopy photosynthesis in response to light, temperature, and moisture availability, and account for respiration. Normalized Difference Vegetation Index (NDVI) data from the NOAA-7 Advanced Very High Resolution Radiometer (AVHRR) sensor provided estimates of canopy-intercepted photosynthetically active radiation for the twelve-month study period. Estimates of NPP generated from the model compare favorably with figures reported in the literature. However the model estimates are, in general, less than reported figures, suggesting the possibility of systematic error in the model. Difficulties confronted in specifying certain model parameters are discussed as possible sources of error. The results of this study suggest the promise of remotely sensed measurements for macroscale evaluation and modeling of primary productivity.

  10. Sweeping beauty: is grassland arthropod community composition effectively estimated by sweep netting?

    PubMed Central

    Spafford, Ryan D; Lortie, Christopher J

    2013-01-01

    Arthropods are critical ecosystem components due to their high diversity and sensitivity to perturbation. Furthermore, due to their ease of capture they are often the focus of environmental health surveys. There is much debate regarding the best sampling method to use in these surveys. Sweep netting and pan trapping are two sampling methods commonly used in agricultural arthropod surveys, but have not been contrasted in natural grassland systems at the community level. The purpose of this study was to determine whether sweep netting was effective at estimating arthropod diversity at the community level in grasslands or if supplemental pan trapping was needed. Arthropods were collected from grassland sites in Montana, USA, in the summer of 2011. The following three standardized evaluation criteria (consistency, reliability, and precision) were developed to assess the efficacy of sweep netting and pan trapping, based on analyses of variations in arthropod abundances, species richness, evenness, capture frequency, and community composition. Neither sampling method was sufficient in any criteria to be used alone for community-level arthropod surveys. On a taxa-specific basis, however, sweep netting was consistent, reliable, and precise for Thysanoptera, infrequently collected (i.e., rare) insects, and Arachnida, whereas pan trapping was consistent, reliable, and precise for Collembola and bees, which is especially significant given current threats to the latter's populations worldwide. Species-level identifications increase the detected dissimilarity between sweep netting and pan trapping. We recommend that community-level arthropod surveys use both sampling methods concurrently, at least in grasslands, but likely in most nonagricultural systems. Target surveys, such as monitoring bee communities in fragmented grassland habitat or where detailed information on behavior of the target arthropod groups is available can in some instances employ singular methods. As a

  11. BiomeNet: A Bayesian Model for Inference of Metabolic Divergence among Microbial Communities

    PubMed Central

    Chipman, Hugh; Gu, Hong; Bielawski, Joseph P.

    2014-01-01

    Metagenomics yields enormous numbers of microbial sequences that can be assigned a metabolic function. Using such data to infer community-level metabolic divergence is hindered by the lack of a suitable statistical framework. Here, we describe a novel hierarchical Bayesian model, called BiomeNet (Bayesian inference of metabolic networks), for inferring differential prevalence of metabolic subnetworks among microbial communities. To infer the structure of community-level metabolic interactions, BiomeNet applies a mixed-membership modelling framework to enzyme abundance information. The basic idea is that the mixture components of the model (metabolic reactions, subnetworks, and networks) are shared across all groups (microbiome samples), but the mixture proportions vary from group to group. Through this framework, the model can capture nested structures within the data. BiomeNet is unique in modeling each metagenome sample as a mixture of complex metabolic systems (metabosystems). The metabosystems are composed of mixtures of tightly connected metabolic subnetworks. BiomeNet differs from other unsupervised methods by allowing researchers to discriminate groups of samples through the metabolic patterns it discovers in the data, and by providing a framework for interpreting them. We describe a collapsed Gibbs sampler for inference of the mixture weights under BiomeNet, and we use simulation to validate the inference algorithm. Application of BiomeNet to human gut metagenomes revealed a metabosystem with greater prevalence among inflammatory bowel disease (IBD) patients. Based on the discriminatory subnetworks for this metabosystem, we inferred that the community is likely to be closely associated with the human gut epithelium, resistant to dietary interventions, and interfere with human uptake of an antioxidant connected to IBD. Because this metabosystem has a greater capacity to exploit host-associated glycans, we speculate that IBD-associated communities might arise

  12. Uncertainty analysis of terrestrial net primary productivity and net biome productivity in China during 1901-2005

    NASA Astrophysics Data System (ADS)

    Shao, Junjiong; Zhou, Xuhui; Luo, Yiqi; Zhang, Guodong; Yan, Wei; Li, Jiaxuan; Li, Bo; Dan, Li; Fisher, Joshua B.; Gao, Zhiqiang; He, Yong; Huntzinger, Deborah; Jain, Atul K.; Mao, Jiafu; Meng, Jihua; Michalak, Anna M.; Parazoo, Nicholas C.; Peng, Changhui; Poulter, Benjamin; Schwalm, Christopher R.; Shi, Xiaoying; Sun, Rui; Tao, Fulu; Tian, Hanqin; Wei, Yaxing; Zeng, Ning; Zhu, Qiuan; Zhu, Wenquan

    2016-05-01

    Despite the importance of net primary productivity (NPP) and net biome productivity (NBP), estimates of NPP and NBP for China are highly uncertain. To investigate the main sources of uncertainty, we synthesized model estimates of NPP and NBP for China from published literature and the Multi-scale Synthesis and Terrestrial Model Intercomparison Project (MsTMIP). The literature-based results showed that total NPP and NBP in China were 3.35 ± 1.25 and 0.14 ± 0.094 Pg C yr-1, respectively. Classification and regression tree analysis based on literature data showed that model type was the primary source of the uncertainty, explaining 36% and 64% of the variance in NPP and NBP, respectively. Spatiotemporal scales, land cover conditions, inclusion of the N cycle, and effects of N addition also contributed to the overall uncertainty. Results based on the MsTMIP data suggested that model structures were overwhelmingly important (>90%) for the overall uncertainty compared to simulations with different combinations of time-varying global change factors. The interannual pattern of NPP was similar among diverse studies and increased by 0.012 Pg C yr-1 during 1981-2000. In addition, high uncertainty in China's NPP occurred in areas with high productivity, whereas NBP showed the opposite pattern. Our results suggest that to significantly reduce uncertainty in estimated NPP and NBP, model structures should be substantially tested on the basis of empirical results. To this end, coordinated distributed experiments with multiple global change factors might be a practical approach that can validate specific structures of different models.

  13. Building Capacity through Sustainable Engagement: Lessons for the Learning Community from the "GraniteNet" Project

    ERIC Educational Resources Information Center

    Arden, Catherine; McLachlan, Kathryn; Cooper, Trevor

    2009-01-01

    This paper reports an exploration into critical success factors for the sustainability of the partnership between the University of Southern Queensland and the Stanthorpe community during the GraniteNet Phoenix Project--the first phase of a three-phase participatory action research project conducted during 2007-2008. The concepts of learning…

  14. From social network to safety net: Dementia-friendly communities in rural northern Ontario.

    PubMed

    Wiersma, Elaine C; Denton, Alison

    2016-01-01

    Dementia-friendly communities, as communities that enable people with dementia to remain involved and active and have control over their lives for as long as possible, centrally involve social support and social networks for people living with dementia. The purpose of this research was to explore and understand the context of dementia in rural northern communities in Ontario with an emphasis on understanding how dementia friendly the communities were. Using qualitative methods, interviews were conducted with a total of 71 participants, including 37 health service providers, 15 care partners, 2 people living with dementia and 17 other community members such as local business owners, volunteers, local leaders, friends and neighbours. The strong social networks and informal social support that were available to people living with dementia, and the strong commitment by community members, families and health care providers to support people with dementia, were considered a significant asset to the community. A culture of care and looking out for each other contributed to the social support provided. In particular, the familiarity with others provided a supportive community environment. People with dementia were looked out for by community members, and continued to remain connected in their communities. The social support provided in these communities demonstrated that although fragile, this type of support offered somewhat of a safety net for individuals living with dementia. This work provides important insights into the landscape of dementia in rural northern Ontario communities, and the strong social supports that sustain people with dementia remaining in the communities. PMID:24381217

  15. Transcriptomic evidence for net methane oxidation and net methane production in putative ANaerobic MEthanotrophic (ANME) archaea

    NASA Astrophysics Data System (ADS)

    Lloyd, K. G.; Alperin, M. J.; Teske, A.

    2010-12-01

    Anaerobic methane oxidation regulates methane emissions in marine sediments and is thought to be mediated by uncultured methanogen-like archaea collectively labeled ANME (for ANaerobic MEthanotrophs). ANME archaea are often assumed to be obligate methanotrophs that are incapable of net methanogenesis, and are therefore used as proxies for anaerobic methane oxidation in many environments in spite of uncertainty regarding their metabolic capabilities. We tested this assumption by detecting and quantifying methanogenic gene transcription of ANME archaea across clearly differentiated zones of methane oxidation vs. methane production in sediments from the White Oak River estuary, NC. ANME-1 archaea (a group of putative obligate methanotrophs) consistently transcribe 16S rRNA and mRNA of methyl coenzyme M reductase (mcrA) the key gene for methanogenesis, up to 45 cm into methanogenic sediments. CARD-FISH shows that ANME-1 archaea exist as single rod-shaped cells or pairs of cells, and in very low numbers. Integrating normalized depth-distributions of 16S rDNA and rRNA (measured with qPCR and RT-qPCR, respectively) shows that 26-77 % of the rDNA proxy for ANME-1 cell numbers, and 18-74 % of the rRNA proxy for ANME-1 activity occurs within methane-producing sediments. mRNA transcripts of dissimilatory sulfite reductase (dsrAB) from sulfate reducing bacteria, the putative syntrophic partners of sulfate-dependent methane oxidation, were amplified consistently from methane-oxidizing sediments, and inconsistently from methane-producing sediments. These results change the perspective from ANME-1 archaea as obligate methane oxidizers to methanogens that are also capable of methane oxidation.

  16. Efficacy of mosquito netting for sustainable small holders' cabbage production in Africa.

    PubMed

    Martin, T; Assogba-Komlan, F; Houndete, T; Hougard, J M; Chandre, F

    2006-04-01

    The efficacy of a mosquito netting to protect cabbages, Brassica oleracea L., against pests was investigated in field trials in Benin, West Africa. A polyester net covered the plants at night by using a wood armature. The net was removed during the day to prevent overheating and excessive shade, both problems of insect-proof screens used under tropical conditions. The number of all lepidopteran larvae with netting protection and foliar insecticide sprays was significantly lower than the unprotected control. The number of diamondback moth, Plutella xylostella (L.), was significantly lower with netting protection compared with foliar insecticide sprays and control. Netting treated with deltamethrin gave total protection of young plants against the aphid Lipaphis erysimi (Kaltenbach). At harvest, the number of marketable cabbages protected with untreated netting was significantly higher compared with the production with foliar insecticide sprays. The protection of cabbages with netting can be an economically viable method. Considering the price of cabbages on local markets (US dollars 1/unit), the net returns per 100 m2 were US dollars 247 by using netting, US dollars 149 by using insecticides, and US dollars 117 for controls. The net returns for using netting are based on replacing the netting each crop cycle. But netting can be reused several times, depending upon conditions, increasing the profit margin. The netting protection may be an alternative to the growing unsustainable practices of vegetable cropping in peri-urban areas of tropical countries. PMID:16686146

  17. Changes in Net Primary Production over Korea and Climate Factors

    NASA Astrophysics Data System (ADS)

    Shim, C.; Hong, J.; Lee, M.; Baek, G.

    2011-12-01

    Spatial and temporal variabilities of NPP(Net Primary Production) retrieved from two satellite instruments, AVHRR(Advanced Very High Resolution Radiometer, 1981-2000) and MODIS(MODerate-resolution Imaging Spectroradiometer, 2000-2006), were investigated. The range of mean NPP from AVHRR and MODIS were estimated to be 894-1068 g C/m2/yr and 610-694.90 g C/m2/yr, respectively. The discrepancy of NPP between the two instruments is about 325 g C/m2/yr, and MODIS product is generally closer to the ground measurement than AVHRR despite the limitation in direct comparison such as spatial resolution and vegetation classification. The higher NPP values over South Korea are related to the regions with higher biomass (e.g., mountains) and higher annual temperature. The interannual NPP trends from the two satellite products were computed, and both mean annual trends show continuous NPP increase; 41 g C/m2/yr from AVHRR (1981-2000) and 36 g C/m2/yr from MODIS (2000-2006) over South Korea. Specifically, the higher increasing trends over the Southwestern region are likely due to the increasing productivity of crop fields from sufficient irrigation and fertilizer use. The retrieved NPP shows a closer relationship between monthly temperature and precipitation, which results in maximum correlation during summer monsoons. The difference in the detection wavelength and model schemes during the retrieval can make a significant difference in the satellite products, and a better accuracy in the meterological and land use data and modeling applications will be necessary to improve the satellite-based NPP data.

  18. Validation and Spatiotemporal Analysis of CERES Surface Net Radiation Product

    DOE PAGESBeta

    Jia, Aolin; Jiang, Bo; Liang, Shunlin; Zhang, Xiaotong; Ma, Han

    2016-01-23

    The Clouds and the Earth’s Radiant Energy System (CERES) generates one of the few global satellite radiation products. The CERES ARM Validation Experiment (CAVE) has been providing long-term in situ observations for the validation of the CERES products. However, the number of these sites is low and their distribution is globally sparse, and particularly the surface net radiation product has not been rigorously validated yet. Therefore, additional validation efforts are highly required to determine the accuracy of the CERES radiation products. In this study, global land surface measurements were comprehensively collected for use in the validation of the CERES netmore » radiation (Rn) product on a daily (340 sites) and a monthly (260 sites) basis, respectively. The validation results demonstrated that the CERES Rn product was, overall, highly accurate. The daily validations had a Mean Bias Error (MBE) of 3.43 W·m−2, Root Mean Square Error (RMSE) of 33.56 W·m−2, and R2 of 0.79, and the monthly validations had an MBE of 3.40 W·m−2, RMSE of 25.57 W·m−2, and R2 of 0.84. The accuracy was slightly lower for the high latitudes. Following the validation, the monthly CERES Rn product, from March 2000 to July 2014, was used for a further analysis. We analysed the global spatiotemporal variation of the Rn, which occurred during the measurement period. In addition, two hot spot regions, the southern Great Plains and south-central Africa, were then selected for use in determining the driving factors or attribution of the Rn variation. We determined that Rn over the southern Great Plains decreased by −0.33 W·m−2 per year, which was mainly driven by changes in surface green vegetation and precipitation. In south-central Africa, Rn decreased at a rate of −0.63 W·m−2 per year, the major driving factor of which was surface green vegetation.« less

  19. Relative contributions of mercury bioavailability and microbial growth rate on net methylmercury production by anaerobic mixed cultures†

    PubMed Central

    Kucharzyk, Katarzyna H.; Deshusses, Marc A.; Porter, Kaitlyn A.; Hsu-Kim, Heileen

    2016-01-01

    Monomethylmercury (MeHg) is produced in many aquatic environments by anaerobic microorganisms that take up and methylate inorganic forms of Hg(II). Net methylation of Hg(II) appears to be correlated with factors that affect the activity of the anaerobic microbial community and factors that increase the bioavailability of Hg(II) to these organisms. However, the relative importance of one versus the other is difficult to elucidate even though this information can greatly assist remediation efforts and risk assessments. Here, we investigated the effects of Hg speciation (dissolved Hg and nanoparticulate HgS) and microbial activity on the net production of MeHg using two mixed microbial cultures that were enriched from marine sediments under sulfate reducing conditions. The cultures were amended with dissolved Hg (added as a dissolved nitrate salt) and nanoparticulate HgS, and grown under different carbon substrate concentrations. The results indicated that net mercury methylation was the highest for cultures incubated in the greatest carbon substrate concentration (60 mM) compared to incubations with less carbon (0.6 and 6 mM), regardless of the form of mercury amended. Net MeHg production in cultures exposed to HgS nanoparticles was significantly slower than in cultures exposed to dissolved Hg; however, the difference diminished with slower growing cultures with low carbon addition (0.6 mM). The net Hg methylation rate was found to correlate with sulfate reduction rate in cultures exposed to dissolved Hg, while methylation rate was roughly constant for cultures exposed to nanoparticulate HgS. These results indicated a potential threshold of microbial productivity: below this point net MeHg production was limited by microbial activity, regardless of Hg bioavailability. Above this threshold of productivity, Hg speciation became a contributing factor towards net MeHg production. PMID:26211614

  20. Scaling net ecosystem production and net biome production over a heterogeneous region in the western United States

    NASA Astrophysics Data System (ADS)

    Turner, D. P.; Ritts, W. D.; Law, B. E.; Cohen, W. B.; Yang, Z.; Hudiburg, T.; Campbell, J. L.; Duane, M.

    2007-08-01

    Bottom-up scaling of net ecosystem production (NEP) and net biome production (NBP) was used to generate a carbon budget for a large heterogeneous region (the state of Oregon, 2.5×105 km2) in the western United States. Landsat resolution (30 m) remote sensing provided the basis for mapping land cover and disturbance history, thus allowing us to account for all major fire and logging events over the last 30 years. For NEP, a 23-year record (1980-2002) of distributed meteorology (1 km resolution) at the daily time step was used to drive a process-based carbon cycle model (Biome-BGC). For NBP, fire emissions were computed from remote sensing based estimates of area burned and our mapped biomass estimates. Our estimates for the contribution of logging and crop harvest removals to NBP were from the model simulations and were checked against public records of forest and crop harvesting. The predominately forested ecoregions within our study region had the highest NEP sinks, with ecoregion averages up to 197 gC m-2 yr-1. Agricultural ecoregions were also NEP sinks, reflecting the imbalance of NPP and decomposition of crop residues. For the period 1996-2000, mean NEP for the study area was 17.0 TgC yr-1, with strong interannual variation (SD of 10.6). The sum of forest harvest removals, crop removals, and direct fire emissions amounted to 63% of NEP, leaving a mean NBP of 6.1 TgC yr-1. Carbon sequestration was predominantly on public forestland, where the harvest rate has fallen dramatically in the recent years. Comparison of simulation results with estimates of carbon stocks, and changes in carbon stocks, based on forest inventory data showed generally good agreement. The carbon sequestered as NBP, plus accumulation of forest products in slow turnover pools, offset 51% of the annual emissions of fossil fuel CO2 for the state. State-level NBP dropped below zero in 2002 because of the combination of a dry climate year and a large (200 000 ha) fire. These results highlight

  1. Scaling net ecosystem production and net biome production over a heterogeneous region in the western United States

    NASA Astrophysics Data System (ADS)

    Turner, D. P.; Ritts, W. D.; Law, B. E.; Cohen, W. B.; Yang, Z.; Hudiburg, T.; Campbell, J. L.; Duane, M.

    2007-04-01

    Bottom-up scaling of net ecosystem production (NEP) and net biome production (NBP) was used to generate a carbon budget for a large heterogeneous region (the state of Oregon, 2.5×105 km2) in the western United States. Landsat resolution (30 m) remote sensing provided the basis for mapping land cover and disturbance history, thus allowing us to account for all major fire and logging events over the last 30 years. For NEP, a 23-year record (1980-2002) of distributed meteorology (1 km resolution) at the daily time step was used to drive a process-based carbon cycle model (Biome-BGC). For NBP, fire emissions were computed from remote sensing based estimates of area burned and our mapped biomass estimates. Our estimates for the contribution of logging and crop harvest removals to NBP were from the model simulations and were checked against public records of forest and crop harvesting. The predominately forested ecoregions within our study region had the highest NEP sinks, with ecoregion averages up to 197 gC m-2 yr-1. Agricultural ecoregions were also NEP sinks, reflecting the imbalance of NPP and decomposition of crop residues. For the period 1996-2000, mean NEP for the study area was 17.0 TgC yr-1, with strong interannual variation (SD of 10.6). The sum of forest harvest removals, crop removals, and direct fire emissions amounted to 63% of NEP, leaving a mean NBP of 6.1 TgC yr-1. Carbon sequestration was predominantly on public forestland, where the harvest rate has fallen dramatically in the recent years. Comparison of simulation results with estimates of carbon stocks, and changes in carbon stocks, based on forest inventory data showed generally good agreement. The carbon sequestered as NBP, plus accumulation of forest products in slow turnover pools, offset 51% of the annual emissions of fossil fuel CO2 for the state. State-level NBP dropped below zero in 2002 because of the combination of a dry climate year and a large (200 000 ha) fire. These results highlight

  2. Development of a Mapped Diabetes Community Program Guide for a Safety Net Population

    PubMed Central

    Zallman, Leah; Ibekwe, Lynn; Thompson, Jennifer W.; Ross-Degnan, Dennis; Oken, Emily

    2014-01-01

    Purpose Enhancing linkages between patients and community programs is increasingly recognized as a method for improving physical activity, nutrition and weight management. Although interactive mapped community program guides may be beneficial, there remains a dearth of articles that describe the processes and practicalities of creating such guides. This article describes the development of an interactive, web-based mapped community program guide at a safety net institution and the lessons learned from that process. Conclusions This project demonstrated the feasibility of creating two maps – a program guide and a population health map. It also revealed some key challenges and lessons for future work in this area, particularly within safety-net institutions. Our work underscores the need for developing partnerships outside of the health care system and the importance of employing community-based participatory methods. In addition to facilitating improvements in individual wellness, mapping community programs also has the potential to improve population health management by healthcare delivery systems such as hospitals, health centers, or public health systems, including city and state departments of health. PMID:24752180

  3. 19 CFR 151.47 - Optional entry of net quantity of petroleum or petroleum products.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 19 Customs Duties 2 2012-04-01 2012-04-01 false Optional entry of net quantity of petroleum or petroleum products. 151.47 Section 151.47 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF... Petroleum and Petroleum Products § 151.47 Optional entry of net quantity of petroleum or petroleum...

  4. 19 CFR 151.47 - Optional entry of net quantity of petroleum or petroleum products.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 2 2013-04-01 2013-04-01 false Optional entry of net quantity of petroleum or petroleum products. 151.47 Section 151.47 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF... Petroleum and Petroleum Products § 151.47 Optional entry of net quantity of petroleum or petroleum...

  5. 19 CFR 151.47 - Optional entry of net quantity of petroleum or petroleum products.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 2 2011-04-01 2011-04-01 false Optional entry of net quantity of petroleum or petroleum products. 151.47 Section 151.47 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF... Petroleum and Petroleum Products § 151.47 Optional entry of net quantity of petroleum or petroleum...

  6. 19 CFR 151.47 - Optional entry of net quantity of petroleum or petroleum products.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Optional entry of net quantity of petroleum or petroleum products. 151.47 Section 151.47 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF... Petroleum and Petroleum Products § 151.47 Optional entry of net quantity of petroleum or petroleum...

  7. 19 CFR 151.47 - Optional entry of net quantity of petroleum or petroleum products.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 2 2014-04-01 2014-04-01 false Optional entry of net quantity of petroleum or petroleum products. 151.47 Section 151.47 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF... Petroleum and Petroleum Products § 151.47 Optional entry of net quantity of petroleum or petroleum...

  8. Net ecosystem production in a Little Ice Age moraine: the role of plant functional traits

    NASA Astrophysics Data System (ADS)

    Varolo, E.; Zanotelli, D.; Tagliavini, M.; Zerbe, S.; Montagnani, L.

    2015-07-01

    Current glacier retreat allows vast mountain ranges available for vegetation establishment and growth. Little is known about the effective carbon (C) budget of these new ecosystems and how the presence of different vegetation communities, characterized by their specific physiology and life forms influences C fluxes. In this study, using a comparative analysis of the C fluxes of two contrasting vegetation types, we intend to evaluate if the different physiologies of the main species have an effect on Ecosystem Respiration (Reco), Gross Primary Production (GPP), annual cumulated Net Ecosystem Exchange (NEE), and long-term carbon accumulation in soil. The NEE of two plant communities present on a Little Ice Age moraine in the Matsch glacier forefield (Alps, Italy) was measured over two growing seasons. They are a typical C3 grassland, dominated by Festuca halleri All. and a community dominated by CAM rosettes Sempervivum montanum L. on rocky soils. Using transparent and opaque chambers, we extrapolated the ecophysiological responses to the main environmental drivers and performed the partition of NEE into Reco and GPP. Soil samples were collected from the same site to measure long-term C accumulation in the ecosystem. The two communities showed contrasting GPP but similar Reco patterns and as a result significantly different in NEE. The grassland acted mainly as a carbon sink with a total cumulated value of -46.4 ± 35.5 g C m-2 NEE while the plots dominated by the CAM rosettes acted as a source with 31.9 ± 22.4 g C m-2. In spite of the NEE being different in the two plant communities, soil analysis did not reveal significant differences in carbon accumulation. Grasslands showed 1.76 ± 0.12 kg C m-2, while CAM rosettes showed 2.06 ± 0.23 kg C m-2. This study demonstrates that carbon dynamics of two vegetation communities can be distinct even though the growing environment is similar. The physiological traits of the dominant species determine large differences in

  9. Mesozooplankton production, grazing and respiration in the Bay of Bengal: Implications for net heterotrophy

    NASA Astrophysics Data System (ADS)

    Fernandes, Veronica; Ramaiah, N.

    2016-03-01

    Mesozooplankton samples were collected from the mixed layer along a central (along 88°E) and a western transect in the Bay of Bengal during four seasons covered between 2001 and 2006 in order to investigate spatio-temporal variability in their biomass. At these stations, grazing and respiration rates were measured from live zooplankton hauled in from the surface during December 2005. Akin to the mesozooplankton "paradox" in the central and eastern Arabian Sea, biomass in the mixed layer was more or less invariant in the central and western Bay of Bengal, even as the chl a showed marginal temporal variation. By empirical equation, the mesozooplankton production rate calculated to be 70-246 mg C m- 2 d- 1 is on par with the Arabian Sea. Contrary to the conventional belief, mesozooplankton grazing impact was up to 83% on primary production (PP). Low PP coupled with very high zooplankton production (70% of PP) along with abundant bacterial production (50% of the PP; Ramaiah et al., 2009) is likely to render the Bay of Bengal net heterotrophic, especially during the spring intermonsoon. Greater estimates of fecal pellet-carbon egestion by mesozooplankton compared to the average particulate organic carbon flux in sediment traps, implies that much of the matter is recycled by heterotrophic communities in the mixed layer facilitating nutrient regeneration for phytoplankton growth. We also calculated that over a third of the primary production is channelized for basin-wide zooplankton respiration that accounts for ~ 52 Mt C annually. In the current scenario of global warming, if low (primary) productive warm pools like the Bay of Bengal continue to be net heterotrophic, negative implications like enhanced emission of CO2 to the atmosphere, increased particulate flux to the deeper waters and greater utilization of dissolved oxygen resulting in expansion of the existing oxygen minimum zone are imminent.

  10. Exact evaluation of gross photosynthetic production from the oxygen triple-isotope composition of O2: Implications for the net-to-gross primary production ratios

    NASA Astrophysics Data System (ADS)

    Prokopenko, Maria G.; Pauluis, Olivier M.; Granger, Julie; Yeung, Laurence Y.

    2011-07-01

    The oxygen triple-isotope composition of dissolved O2 provides an integrative method to estimate the rates of Gross Photosynthetic Production (GPP) in the upper ocean, and combined with estimates of Net Community Production (NCP) yields an estimate of the net-to-gross (NCP/GPP) production ratios. However, derivations of GPP from oxygen triple-isotope measurements have involved some mathematical approximations. We derive an exact expression for calculating GPP, and show that small errors associated with approximations result in a relative error of up to ˜38% in GPP, and up to ˜50% in N/G. In open ocean regimes with low primary production, the observed magnitude of the error is comparable to the combined methodological uncertainties. In highly productive ecosystems, the error arising from approximations becomes significant. Using data collected on the Bering Sea shelf, we illustrate the differences in GPP estimates in both high and low productivity regimes that arise from exact and approximated formulations.

  11. Net Loss of CaCO3 from a subtropical calcifying community due to seawater acidification: mesocosm-scale experimental evidence

    NASA Astrophysics Data System (ADS)

    Andersson, A. J.; Kuffner, I. B.; MacKenzie, F. T.; Jokiel, P. L.; Rodgers, K. S.; Tan, A.

    2009-08-01

    Acidification of seawater owing to oceanic uptake of atmospheric CO2 originating from human activities such as burning of fossil fuels and land-use changes has raised serious concerns regarding its adverse effects on corals and calcifying communities. Here we demonstrate a net loss of calcium carbonate (CaCO3) material as a result of decreased calcification and increased carbonate dissolution from replicated subtropical coral reef communities (n=3) incubated in continuous-flow mesocosms subject to future seawater conditions. The calcifying community was dominated by the coral Montipora capitata. Daily average community calcification or Net Ecosystem Calcification (NEC=CaCO3 production - dissolution) was positive at 3.3 mmol CaCO3 m-2 h-1 under ambient seawater pCO2 conditions as opposed to negative at -0.04 mmol CaCO3 m-2 h-1 under seawater conditions of double the ambient pCO2. These experimental results provide support for the conclusion that some net calcifying communities could become subject to net dissolution in response to anthropogenic ocean acidification within this century. Nevertheless, individual corals remained healthy, actively calcified (albeit slower than at present rates), and deposited significant amounts of CaCO3 under the prevailing experimental seawater conditions of elevated pCO2.

  12. Net Loss of CaCO3 from a subtropical calcifying community due to seawater acidification: Mesocosm-scale experimental evidence

    USGS Publications Warehouse

    Andersson, A.J.; Kuffner, I.B.; MacKenzie, F.T.; Jokiel, P.L.; Rodgers, K.S.; Tan, A.

    2009-01-01

    Acidification of seawater owing to oceanic uptake of atmospheric CO 2 originating from human activities such as burning of fossil fuels and land-use changes has raised serious concerns regarding its adverse effects on corals and calcifying communities. Here we demonstrate a net loss of calcium carbonate (CaCO3) material as a result of decreased calcification and increased carbonate dissolution from replicated subtropical coral reef communities (N=3) incubated in continuous-flow mesocosms subject to future seawater conditions. The calcifying community was dominated by the coral Montipora capitata. Daily average community calcification or Net Ecosystem Calcification (NECC=CaCO3 production - dissolution) was positive at 3.3 mmol CaCO3 m-2 h-1 under ambient seawater pCO2 conditions as opposed to negative at -0.04 mmol CaCO3 m-2 h-1 under seawater conditions of double the ambient pCO2. These experimental results provide support for the conclusion that some net calcifying communities could become subject to net dissolution in response to anthropogenic ocean acidification within this century. Nevertheless, individual corals remained healthy, actively calcified (albeit slower than at present rates), and deposited significant amounts of CaCO3 under the prevailing experimental seawater conditions of elevated pCO2.

  13. Effectiveness of bowl trapping and netting for inventory of a bee community

    USGS Publications Warehouse

    Grundel, R.; Frohnapple, K.J.; Jean, R.P.; Pavlovic, N.B.

    2011-01-01

    Concern over the status of bees has increased the need to inventory bee communities and, consequently, has increased the need to understand effectiveness of different bee sampling methods. We sampled bees using bowl traps and netting at 25 northwest Indiana sites ranging from open grasslands to forests. Assemblages of bees captured in bowl traps and by netting were very similar, but this similarity was driven by similar relative abundances of commonly captured species. Less common species were often not shared between collection methods (bowls, netting) and only about half of the species were shared between methods. About one-quarter of species were more often captured by one of the two collection methods. Rapid accumulation of species was aided by sampling at temporal and habitat extremes. In particular, collecting samples early and late in the adult flight season and in open and forest habitats was effective in capturing the most species with the fewest samples. The number of samples estimated necessary to achieve a complete inventory using bowls and netting together was high. For example, ≈72% of species estimated capturable in bowls were captured among the 3,159 bees collected in bowls in this study, but ≈30,000–35,000 additional bees would need to be collected to achieve a 100% complete inventory. For bowl trapping, increasing the number of sampling dates or sampling sites was more effective than adding more bowls per sampling date in completing the inventory with the fewest specimens collected.

  14. In silico substrate dependence increases community productivity but threatens biodiversity

    NASA Astrophysics Data System (ADS)

    Daly, Aisling J.; Baetens, Jan M.; De Baets, Bernard

    2016-04-01

    The critical role that biodiversity plays in ecosystem functioning has motivated many studies of the mechanisms that sustain biodiversity, a notable example being cyclic competition. We extend existing models of communities with cyclic competition by incorporating variable community evenness and resource dependence in demographic processes, two features that have generally been neglected. In this way, we align previous approaches more closely with real-world microbial ecosystems. We demonstrate the existence of a trade-off between increasing biomass production and maintaining biodiversity. This supports experimental observations of a net negative biodiversity effect on biomass productivity, due to competition effects suffered by highly productive species in diverse communities. Our results also support the important role assigned by microbial ecologists to evenness in maintaining ecosystem stability, thus far largely overlooked in in silico approaches.

  15. Residence time control on hot moments of net nitrate production and uptake in the hyporheic zone

    USGS Publications Warehouse

    Briggs, Martin A.; Lautz, Laura K.; Hare, Danielle K.

    2014-01-01

    moments of net production and uptake, enhancing NO3- production as residence times approach the anaerobic threshold, and changing zones of net NO3- production to uptake as residence times increase past the net sink threshold. The anaerobic and net sink thresholds for beaver-influenced streambed morphology occur at much shorter residence times (1.3 h and 2.3 h, respectively) compared to other documented hyporheic systems, and the net sink threshold compares favorably to the lower boundary of the anaerobic threshold determined for this system with the new oxygen Damkohler number. The consistency of the residence time threshold values of NO3- cycling in this study, despite environmental variability and disparate morphology, indicates that NO3- hot moment dynamics are primarily driven by changes in physical hydrology and associated residence times.

  16. Capsular polysaccharides from Cryptococcus neoformans modulate production of neutrophil extracellular traps (NETs) by human neutrophils.

    PubMed

    Rocha, Juliana D B; Nascimento, Michelle T C; Decote-Ricardo, Debora; Côrte-Real, Suzana; Morrot, Alexandre; Heise, Norton; Nunes, Marise P; Previato, José Osvaldo; Mendonça-Previato, Lucia; DosReis, George A; Saraiva, Elvira M; Freire-de-Lima, Célio G

    2015-01-01

    In the present study, we characterized the in vitro modulation of NETs (neutrophil extracellular traps) induced in human neutrophils by the opportunistic fungus Cryptococcus neoformans, evaluating the participation of capsular polysaccharides glucuronoxylomanan (GXM) and glucuronoxylomannogalactan (GXMGal) in this phenomenon. The mutant acapsular strain CAP67 and the capsular polysaccharide GXMGal induced NET production. In contrast, the wild-type strain and the major polysaccharide GXM did not induce NET release. In addition, C. neoformans and the capsular polysaccharide GXM inhibited PMA-induced NET release. Additionally, we observed that the NET-enriched supernatants induced through CAP67 yeasts showed fungicidal activity on the capsular strain, and neutrophil elastase, myeloperoxidase, collagenase and histones were the key components for the induction of NET fungicidal activity. The signaling pathways associated with NET induction through the CAP67 strain were dependent on reactive oxygen species (ROS) and peptidylarginine deiminase-4 (PAD-4). Neither polysaccharide induced ROS production however both molecules blocked the production of ROS through PMA-activated neutrophils. Taken together, the results demonstrate that C. neoformans and the capsular component GXM inhibit the production of NETs in human neutrophils. This mechanism indicates a potentially new and important modulation factor for this fungal pathogen. PMID:25620354

  17. Near Net Shape production of metal components using LENS

    SciTech Connect

    Schlienger, E.; Dimos, D.; Griffith, M.; Michael, J.; Oliver, M.; Romero, T.; Smugeresky, J.

    1998-03-01

    Rapid Prototyping and Near Net Shape manufacturing technologies are the subject of considerable attention and development efforts. At Sandia National Laboratories, one such effort is LENS (Laser Engineered Net Shaping). The LENS process utilizes a stream of powder and a focused Nd YAG laser to build near net shape fully dense metal parts. In this process, a 3-D solid model is sliced, then an X-Y table is rastered under the beam to build each slice. The laser 1 powder head is incremented upward with each slice and the deposition process is controlled via shuttering of the laser. At present, this process is capable of producing fully dense metal parts of iron, nickel and titanium alloys including tool steels and aluminides. Tungsten components have also been produced. A unique aspect of this process is the ability to produce components wherein the composition varies at differing locations in the part. Such compositional variations may be accomplished in either a stepped or graded fashion. In this paper, the details of the process will be described. The deposition mechanism will be characterized and microstructures and their associated properties will be discussed. Examples of parts which have been produced will be shown and issues regarding dimensional control and surface finish will be addressed.

  18. Initial net CO2 uptake responses and root growth for a CAM community placed in a closed environment.

    PubMed

    Nobel, Park S; Bobich, Edward G

    2002-11-01

    To help understand carbon balance between shoots and developing roots, 41 bare-root crassulacean acid metabolism (CAM) plants native to the Sonoran Desert were studied in a glass-panelled sealable room at day/night air temperatures of 25/15 degrees C. Net CO(2) uptake by the community of Agave schottii, Carnegia gigantea, Cylindropuntia versicolor, Ferocactus wislizenii and Opuntia engelmannii occurred 3 weeks after watering. At 4 weeks, the net CO(2) uptake rate measured for south-east-facing younger parts of the shoots averaged 1.94 micro mol m(-2) s(-1) at night, considerably higher than the community-level nocturnal net CO(2) uptake averaged over the total shoot surface, primarily reflecting the influences of surface orientation on radiation interception (predicted net CO(2) uptake is twice as high for south-east-facing surfaces compared with all compass directions). Estimated growth plus maintenance respiration of the roots averaged 0.10 micro mol m(-2) s(-1) over the 13-week period, when the community had a net carbon gain from the atmosphere of 4 mol C while the structural C incorporated into the roots was 23 mol. Thus, these five CAM species diverted all net C uptake over the 13-week period plus some existing shoot C to newly developing roots. Only after sufficient roots develop to support shoot water and nutrient requirements will the plant community have net above-ground biomass gains. PMID:12466099

  19. Creating Community-Based Video Productions.

    ERIC Educational Resources Information Center

    Spangler, Lynn C.

    In the interest of offering universities new avenues for teaching students methods of video production, this paper presents a number of ideas for allowing students to practice their production skills out in the community. Following an introduction, the paper lists six types of community based productions suitable for students: (1) performance…

  20. Social Capacity Assessment for communities and organisations in the CapHaz-Net context

    NASA Astrophysics Data System (ADS)

    Begg, C.; Kuhlicke, C.; Steinführer, A.; Luther, J.

    2012-04-01

    Instead of focusing on physical conditions of a hazard, CapHaz-Net regards the occurrence of a disaster as a result of people, communities and organisations lacking capacities to anticipate, cope with and recover from the impact of a natural hazard. Therefore, the CapHaz-Net project has pooled together knowledge surrounding six topics relating to the social side of natural hazards. These theoretical topics, which include social capacity building, risk governance, social vulnerability, risk perception, risk communication and risk education have been reviewed in terms of how they relate to and how we can improve actions relating to natural hazards. One of the results of this work has been the development of capacities typology that relates to the abilities and resources available to organisations and communities in regards to a future hazard event. It is from this typology we have developed two social capacity audits; one for communities and one for organisations. These assessments aim to identify appropriate measures and strategies regarding how to enhance, develop and build different kinds of capacities. The final outcome of the project is to develop recommendations. By using these assessments participants will be able to identify strong capacities and can refer to the recommendations for tips on how to improve capacities identified as weak. Most importantly, the assessment process is designed to be a self-assessment, completed by members of the community/organisation with the help of a facilitator. That way deficits and outcomes are defined by those who are most likely to be affected by a future hazard event and most likely to be implementing improvements towards resilience.

  1. Production of aluminum-lithium near net shape extruded cylinders

    NASA Technical Reports Server (NTRS)

    Hartley, Paula J.

    1995-01-01

    In the late 1980's, under funding from the Advanced Launch System Program, numerous near net shape technologies were investigated as a means for producing high quality, low cost Aluminum-Lithium (Al-Li) hardware. Once such option was to extrude near net shape barrel panels instead of producing panels by machining thick plate into a final tee-stiffened configuration (which produced up to 90% scrap). This method offers a reduction in the volume of scrap and consequently reduces the buy-to-fly cost. Investigation into this technology continued under Shuttle-C funding where four Al alloys 2219, 2195, 2096, and RX 818 were extruded. Presented herein are the results of that program. Each alloy was successfully extruded at Wyman Gordon, opened and flattened at Ticorm, and solution heat treated and stretched at Reynolds Metals Company. The first two processes were quite successful while the stretching process did offer some challenges. Due to the configuration of the panels and the stretch press set-up, it was difficult to induce a consistent percentage of cold work throughout the length and width of each panel. The effects of this variation will be assessed in the test program to be conducted at a future date.

  2. The utility of estimating net primary productivity over Alaska using baseline AVHRR data

    USGS Publications Warehouse

    Markon, C.J.; Peterson, K.M.

    2002-01-01

    Net primary productivity (NPP) is a fundamental ecological variable that provides information about the health and status of vegetation communities. The Normalized Difference Vegetation Index, or NDVI, derived from the Advanced Very High Resolution Radiometer (AVHRR) is increasingly being used to model or predict NPP, especially over large remote areas. In this article, seven seasonally based metrics calculated from a seven-year baseline NDVI dataset were used to model NPP over Alaska, USA. For each growing season, they included maximum, mean and summed NDVI, total days, product of total days and maximum NDVI, an integral estimate of NDVI and a summed product of NDVI and solar radiation. Field (plot) derived NPP estimates were assigned to 18 land cover classes from an Alaskan statewide land cover database. Linear relationships between NPP and each NDVI metric were analysed at four scales: plot, 1-km, 10-km and 20-km pixels. Results show moderate to poor relationship between any of the metrics and NPP estimates for all data sets and scales. Use of NDVI for estimating NPP may be possible, but caution is required due to data seasonality, the scaling process used and land surface heterogeneity.

  3. Kaupuni Village: A Closer Look at the First Net-Zero Energy Affordable Housing Community in Hawai'i (Brochure)

    SciTech Connect

    Not Available

    2012-05-01

    This is the first of four Hawaii Clean Energy Initiative community brochures focused on HCEI success stories. This brochure focuses on the first LEED Platinum net-zero energy affordable housing community in Hawaii. Our lead NREL contact for HCEI is Ken Kelly.

  4. The SeaDataNet data products: regional temperature and salinity historical data collections

    NASA Astrophysics Data System (ADS)

    Simoncelli, Simona; Coatanoan, Christine; Bäck, Orjan; Sagen, Helge; Scoy, Serge; Myroshnychenko, Volodymyr; Schaap, Dick; Schlitzer, Reiner; Iona, Sissy; Fichaut, Michele

    2016-04-01

    Temperature and Salinity (TS) historical data collections covering the time period 1900-2013 were created for each European marginal sea (Arctic Sea, Baltic Sea, Black Sea, North Sea, North Atlantic Ocean and Mediterranean Sea) within the framework of SeaDataNet2 (SDN) EU-Project and they are now available as ODV collections through the SeaDataNet web catalog at http://sextant.ifremer.fr/en/web/seadatanet/. Two versions have been published and they represent a snapshot of the SDN database content at two different times: V1.1 (January 2014) and V2 (March 2015). A Quality Control Strategy (QCS) has been developped and continuously refined in order to improve the quality of the SDN database content and to create the best product deriving from SDN data. The QCS was originally implemented in collaboration with MyOcean2 and MyOcean Follow On projects in order to develop a true synergy at regional level to serve operational oceanography and climate change communities. The QCS involved the Regional Coordinators, responsible of the scientific assessment, the National Oceanographic Data Centers (NODC) and the data providers that, on the base of the data quality assessment outcome, checked and eventually corrected anomalies in the original data. The QCS consists of four main phases: 1) data harvesting from the central CDI; 2) file and parameter aggregation; 3) quality check analysis at regional level; 4) analysis and correction of data anomalies. The approach is iterative to facilitate the upgrade of SDN database content and it allows also the versioning of data products with the release of new regional data collections at the end of each QCS loop. SDN data collections and the QCS will be presented and the results summarized.

  5. Productivity, Social Networks and Net Communities in the Workplace

    ERIC Educational Resources Information Center

    Asunda, Paul

    2010-01-01

    The 21st century workplace is being shaped by ever-changing technological innovations, shifting demographic patterns, globalization and power shifts, in addition to different economic players such as policymakers, employers, education and training institutions that shape the quality of the future workforce. In today's work environment,…

  6. Altruistic willingness to pay in community-based sales of insecticide-treated nets exists in Nigeria.

    PubMed

    Onwujekwe, Obinna; Chima, Reginald; Shu, Elvis; Nwagbo, Douglas; Akpala, Cyril; Okonkwo, Paul

    2002-02-01

    The objective of this study was to determine whether households who are willing to pay for insecticide-treated nets (ITNs) for themselves are prepared to contribute for the ITNs to be purchased for the indigent community members who cannot afford the nets. This was in the framework of community-based and directed sales for ITNs. The study was conducted in four malaria holoendemic communities in south-eastern Nigeria. Contingent valuation method was used to determine the altruistic willingness to pay (WTP) from randomly selected household heads or their representatives, which was elicited using an open-ended question. Theoretical validity was assessed using the Tobit model. Median altruistic WTP ranged from $0.11 to $0.21 across the four communities (95 Naira = $1). However, using a pooled data from the four communities, the mean was $0.34. In Tobit estimation, altruistic WTP varied significantly with two of the communities; the respondents were resident in, sex, marital status and the amount of savings of the respondent. It also varied significantly with the respondents' WTP for their own ITNs and average monthly household expenditures to treat malaria (p<0.05). Altruistic WTP will exist in community-based and directed sales of ITNs. Thus there can be intra-community subsidisation by the rich for the poor who may not be able to pay for the nets. Community mobilisation and sensitisation should be used to encourage able households to actually pay at least the amounts they have stated. PMID:11848272

  7. Shuttle Net, Tuna Net

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Rockwell International, NASA's prime contractor for the Space Shuttle, asked West Coast Netting (WCN) to develop a safety net for personnel working on the Shuttle Orbiter. This could not be an ordinary net, it had to be relatively small, yet have extraordinary tensile strength. It also had to be fire resistant and resistant to ultraviolet (UV) light. After six months, WCN found the requisite fiber, a polyester-like material called NOMEX. The company was forced to invent a more sophisticated twisting process since conventional methods did not approach specified breaking strength. The resulting product, the Hyperester net, sinks faster and fishes deeper, making it attractive to fishing fleets. A patented treatment for UV protection and greater abrasion resistance make Hyperester nets last longer, and the no-shrink feature is an economic bonus.

  8. Bacterial Community Affects Toxin Production by Gymnodinium catenatum

    PubMed Central

    Albinsson, Maria E.; Negri, Andrew P.; Blackburn, Susan I.; Bolch, Christopher J. S.

    2014-01-01

    The paralytic shellfish toxin (PST)-producing dinoflagellate Gymnodinium catenatum grows in association with a complex marine bacterial community that is both essential for growth and can alter culture growth dynamics. Using a bacterial community replacement approach, we examined the intracellular PST content, production rate, and profile of G. catenatum cultures grown with bacterial communities of differing complexity and composition. Clonal offspring were established from surface-sterilized resting cysts (produced by sexual crosses of strain GCDE06 and strain GCLV01) and grown with: 1) complex bacterial communities derived from each of the two parent cultures; 2) simplified bacterial communities composed of the G. catenatum-associated bacteria Marinobacter sp. strain DG879 or Alcanivorax sp. strain DG881; 3) a complex bacterial community associated with an untreated, unsterilized sexual cross of the parents. Toxin content (STX-equivalent per cell) of clonal offspring (134–197 fmol STX cell−1) was similar to the parent cultures (169–206 fmol STX cell−1), however cultures grown with single bacterial types contained less toxin (134–146 fmol STX cell−1) than offspring or parent cultures grown with more complex mixed bacterial communities (152–176 fmol STX cell−1). Specific toxin production rate (fmol STX day−1) was strongly correlated with culture growth rate. Net toxin production rate (fmol STX cell−1 day−1) did not differ among treatments, however, mean net toxin production rate of offspring was 8-fold lower than the parent cultures, suggesting that completion of the sexual lifecycle in laboratory cultures leads to reduced toxin production. The PST profiles of offspring cultures were most similar to parent GCDE06 with the exception of cultures grown with Marinobacter sp. DG879 which produced higher proportions of dcGTX2+3 and GC1+2, and lower proportions of C1+2 and C3+4. Our data demonstrate that the bacterial community can alter

  9. Water balance calculations and net production of perennial vegetation in the northern Mojave Desert

    SciTech Connect

    Lane, L.J.; Romney, E.M.; Hakonson, T.E.

    1984-01-01

    Measurements obtained between 1968 and 1976 indicate the influence of climatic factors and soil characteristics upon soil moisture and production of perennial vegetation in the northern Mojave Desert. Seasonal distribution patterns of precipitation are shown to have a strong effect on plant-available soil moisture, and these patterns are, in turn, reflected in net production of perennial vegetation. Available climatic data and soil characteristics were used as input to a continuous simulation model to calculate the water balance for a unit area watershed. Computed and measured soil moisture agreed quite well over a rangeof values from close to the wilting point to near field capacity. The authors used computed evapo-transpiration rates to estimate water use by perennial vegetation. Computed water use was multiplied by a water use efficiency factor to estimate net production of perennial vegetation. Estimated net production exhibited year-to-year variability comparable with measured values, and agreed quite closely with available observations. This paper briefly describes soil-water-plant relationships in the northern Mojave Desert and illustrates an application of a continuous simulation model to predict soil moisture and net production of perennial vegetation. Based on the authors analysis, the simulation model would appear to have potential for estimating the water balance and above ground net primary production on arid and semiarid rangelands. 21 references, 5 figures, 5 tables.

  10. Net energy analysis of methanol and ethanol production

    NASA Astrophysics Data System (ADS)

    Perez-Blanco, H.; Hannon, B.

    1982-03-01

    Methanol (MeOH) and ethanol (EtOH) are industrial alcohols that can be used as liquid fuels. They may be obtained from renewable or non-renewable feedstocks. The production processes and end uses are analyzed in order to assess the potential energy savings introduced by alcohol production from renewable instead of nonrenewable feedstock. Whereas MeOH production from wood brings about energy savings, EtOH production from corn may or may not save energy depending on the end use of the alcohol. If the alcohol is used as a motor fuel, no overall energy savings are found. The economics and total labor requirements of each process are also considered.

  11. 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

  12. MODIS EVI as a Proxy for Net Primary Production across Precipitation Regimes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Above ground net primary production (ANPP) is a measure of the rate of photosynthesis in an ecosystem, and is indicative of its biomass productivity. Prior studies have reported a relationship between ANPP and annual precipitation which converged across biomes in dry years. This deserves further s...

  13. Edaphic and climatic effects on forest stand development, net primary production, and net ecosystem productivity simulated for Coastal Plain loblolly pine in Virginia

    NASA Astrophysics Data System (ADS)

    Sampson, D. A.; Wynne, R. H.; Seiler, J. R.

    2008-03-01

    We used SECRETS-3PG to simulate net primary production (NPP) and net ecosystem productivity (NEP) of loblolly pine (Pinus taeda L.) growing on the Virginia Coastal Plain, focusing on the effects of soils and climate, and stand age over a 30-year rotation. Soil type was influential, with heavier soils having greater NEP earlier in the rotation than lighter, sandier soils, although these differences disappeared by the rotation end. Climate had only a small effect. Stand age had the largest effect, with simulated annual NEP strongly negative during the first 5 to 8 years of development but peaking at +600 g C m-2 a-1 by age 13. Modest declines in NEP after 13 years were associated with declines in LAI as stands aged. The 30-year mean annual NEP was positive over most of the study area but in a few cases was indistinguishable from zero for northwestern portions of the study. Simulated annual NPP rose from zero to over 2300 g biomass m-2 a-1 by age 12, after which it declined to ˜1700 g biomass m-2 a-1 by rotation end. These results suggest that loblolly pine plantations on the Coastal Plain of Virginia may become net annual C sinks 5 to 9 years after planting but that when averaged over a whole rotation the net carbon accumulation during the baseline rotation simulated here is indistinguishable from zero. Our results also suggest, however, that this finding is sensitive to the length of the rotation, soil type (and thus fertility), and climate, implying that changes in management practices could significantly influence the carbon balance in managed loblolly pine plantations.

  14. Mapping net primary production and related biophysical variables with remote sensing: Application to the BOREAS region

    NASA Astrophysics Data System (ADS)

    Goetz, Scott J.; Prince, Stephen D.; Goward, Samuel N.; Thawley, Michelle M.; Small, Jennifer; Johnston, Andrew

    1999-11-01

    Maps of net and gross primary production, autotrophic respiration, biomass, and other biophysical variables were generated for 106 km2 of boreal forest in central Canada (the Boreal Ecosystem-Atmosphere (BOREAS) region) using a production efficiency model (PEM) driven with remotely sensed observations at 1 km2 spatial resolution. The PEM was based on carbon yields of absorbed photosynthetically active radiation for both gross and net primary production (GPP and NPP), accounting for environmental stress and autotrophic respiration (Ra). Physiological control was modeled using remotely sensed maps of air temperature, vapor pressure deficit, and soil moisture. The accuracy of the inferred variables was generally within 10-30% of point measurements at the surface and independent model results (both at the stand level). Biomass maps were derived from visible reflectance measurements and were also compared to independently derived maps. Area-averaged GPP was 604 g C m-2 yr-1 compared with average canopy respiration of 428 g C m-2 yr-1 and NPP of 235 g C m-2 yr-1. Net annual carbon uptake in net primary production for the region totaled 175 teragrams. Canopy carbon exchange (GPP and Ra) differed widely between land cover types even though the model does not use land cover information. Extensive areas of the least productive cover types (e.g., lowland needleleaf species) accounted for the greatest amount of NPP.

  15. The potential of centrifugal casting for the production of near net shape uranium parts

    SciTech Connect

    Robertson, E.

    1993-09-01

    This report was written to provide a detailed summary of a literature survey on the near net shape casting process of centrifugal casting. Centrifugal casting is one potential casting method which could satisfy the requirements of the LANL program titled Near Net Shape Casting of Uranium for Reduced Environmental, Safety and Health Impact. In this report, centrifugal casting techniques are reviewed and an assessment of the ability to achieve the near net shape and waste minimization goals of the LANL program by using these techniques is made. Based upon the literature reviewed, it is concluded that if properly modified for operation within a vacuum, vertical or horizontal centrifugation could be used to safely cast uranium for the production of hollow, cylindrical parts. However, for the production of components of geometries other than hollow tubes, vertical centrifugation could be combined with other casting methods such as semi-permanent mold or investment casting.

  16. Evaluation of mist-net sampling as an index to productivity in Kirtland's Warblers

    USGS Publications Warehouse

    Bart, J.; Kepler, C.; Sykes, P.; Bocetti, C.I.

    1999-01-01

    In summary, in our study (1) capture rates (number of HY birds/number of AHY birds) were not useful as a direct measure of productivity in Kirtland's Warblers because HY birds were about 1.7 times more likely than AHY birds to be captured in mist nets; (2) capture rates varied substantially among sites, presumably because of changes in habitat that affected movements during late summer (thus, capture rates at a single site did not provide a useful index to population-wide productivity); and (3) population-wide capture rates provided useful indices to population-wide productivity. As noted previously, the first two conclusions are already accepted by specialists in the use of mist netting to index productivity. Our study presents the first evidence that annual variation in relative capture rates is sufficiently small that mist netting at multiple sites in a region can provide a useful index to region-wide productivity. The region must be large relative to late-summer movements by the study species, which means that obtaining habitat-specific productivity rates will be possible only within large patches of habitat. It should also be recognized that many species will move much farther than Kirtland's Warblers (owing to their limited breeding distribution). Our results suggest that mist-netting programs like MAPS and the Constant Effort Sites used in Britain can provide useful measures of temporal patterns, large-scale spatial patterns, and year-specific patterns in avian productivity. Furthermore, unlike most nest-monitoring studies, mist netting in late summer measures season-long productivity, the quantity of greatest use in most demographic analyses. Late-summer mist netting thus appears to be a useful method for studying avian productivity provided that investigators realize that results from at least six to eight sites that are well distributed across a large region must be combined to obtain a valid index, and that results obtained in this manner describe

  17. Estimating Green Net National Product for Puerto Rico: An Economic Measure of Sustainability (Journal article)

    EPA Science Inventory

    This paper presents the data sources and methodology used to estimate Green Net National Product (GNNP), an economic metric of sustainability, for Puerto Rico. Using the change in GNNP as a one-sided test of weak sustainability (i.e., positive growth in GNNP is not enough to show...

  18. Green Net Regional Product for the San Luis Basin, Colorado: An Economic Measure of Regional Sustainability

    EPA Science Inventory

    This paper presents the data sources and methodology used to estimate Green Net Regional Product (GNRP), a green accounting approach, for the San Luis Basin (SLB). GNRP is equal to aggregate consumption minus the depreciation of man-made and natural capital. We measure the move...

  19. Aboveground net primary production responses to water availability in the Chihuhuan Desert: importance of legacy effects

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In arid ecosystems, current year precipitation explains a small proportion of annual aboveground net primary production (ANPP). Precipitation that occurred in previous years may be responsible for the observed difference between actual and expected ANPP, a concept that we called legacy. Thus, previo...

  20. Global Net Primary Production Predicted from Vegetation Class, Precipitation, and Temperature.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Net Primary Production (NPP), the difference between CO2 fixed by photosynthesis and CO2 lost to autotrophic respiration, is one of the most important components of the carbon cycle. Our goal was to develop a simple regression model to estimate global NPP using climate and land cover data. Approxima...

  1. Global Potential Net Prmary Production Predicted from Vegetation Class, Precipitation, and Temperature

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Net Primary Production (NPP), the difference between CO2 fixed by photosynthesis and CO2 lost to autotrophic respiration, is one of the most important components of the carbon cycle. Our goal was to develop a simple regression model to estimate global NPP using climate and land cover data. Approxima...

  2. A new net primary production estimating model using NOAA-AVHRR applied to the Haihe Basin, China

    NASA Astrophysics Data System (ADS)

    Xu, Xingang; Wu, Bingfang; Li, Qiangzi; Meng, Jihua; Zhang, Fengli

    2006-10-01

    Terrestrial net primary production (NPP), as an important component of carbon cycle on land, not only indicates directly the production level of vegetation community on land, but also shows the status of terrestrial ecosystem. What's more, NPP is also a determinant of carbon sinks on land and a key regulator of ecological processes, including interactions among tropic levels. In the study, three existing models are combined with each other to assess net primary production in Haihe Basin, China. The photosynthetically active radiation (PAR) model of Monteith is used for the calculation of absorbed photosynthetically active radiation (APAR), the light utilization efficiency model of Potter et al. is used for determining the light utilization efficiency, and the surface energy balance system (SEBS) of Su is used into Potter's model to describe water stress in land wetness conditions. To assess NPP, We use NOAA-AVHRR data from November 2003 to September 2004 and the corresponding daily data of temperature and hours of sunshine obtained from meteorological stations in Haihe Basin, China. After atmospheric, geometrical and radiant corrections, every ten days NOAA data are processed to become an image of NDVI by means of the maximal value composition method (MVC) in order to eliminate some noises. Using these data, we compute NPP in spring season and spring season of 2004 in Haihe Basin, China. The result shows, in Haihe Basin, NPP for spring season is averaged to 336.10gC•m -2, and 709.16 gC•m -2 for autumn season. In spatial distribution, NPP is greater in both ends than in middle for spring season, and decrease increasingly from north to south for autumn season. Future work should rely on the integration of high and low resolution images to assess net primary production, which will probably have more accurately estimation.

  3. Geospatial analysis of change in net primary productivity, 1998-2013, Inner Mongolian Desert steppe region, China

    NASA Astrophysics Data System (ADS)

    Wuliangha, B.; Han, W.; Sun, G. F.; Chen, J. B.

    2016-04-01

    Net primary productivity (NPP) is a quantitative measure of the carbon absorption by plants per unit time and space. The NPP is a key indicator to evaluate the productivity of vegetation communities in the natural environment. Consistent data on terrestrial NPP are urgently needed to constrain model estimates of carbon fluxes and hence to refine our understanding of ecosystem responses to climate change. It could also be an indicator to represent certain land cover characteristics. This study analyzed NPP changes from 1998 to 2013 in the Inner Mongolian Desert Steppe region of China through estimation of annual NPP using multiyear 10-day SPOT VEGETATION NDVI data and meteorological observation data from 1998 to 2013 by using a modified Carnegie-Ames-Stanford Approach (CASA) model. ArcGIS and ENVI software was used for spatial data processing; NPP inversion was performed and an integrated program was used for the modified CASA model. We also used related spatial information technologies, such as geographic information system, global navigation satellite system and remote sensing technology, to determine some 1 km2 random sampling pixels and regularly selected four 1m2 quadrats in each pixel, and we measured aboveground net primary productivity (ANPP) for accuracy assessment of modelled NPP. The final results show that the NPP had many obvious geospatial changes during the period from 1998 to 2013 in the Inner Mongolian Desert Steppe region.

  4. Disturbance severity and net primary production resilience of a Great Lakes forest ecosystem

    NASA Astrophysics Data System (ADS)

    Goodrich-Stuart, E. J.; Fahey, R.; De La Cruz, A.; Gough, C. M.

    2013-12-01

    As many Eastern deciduous forests of North America transition from early to mid-succession, the future of regional terrestrial carbon (C) storage is uncertain. The gradual, patchy senescence of early-successional trees accompanying this transition is comparable in severity to moderate disturbances such as silvicultural thinnings or insect outbreaks. While stand-replacing disturbance causes forests to temporarily become C sources, more moderate disturbances may inflict little to no decline in C sequestration. Identifying the disturbance severity at which net primary production (NPP) declines and the underlying mechanisms that drive forest C storage resistance to disturbance is increasingly important as moderate disturbances increase in frequency and extent across the region. The Forest Accelerated Succession ExperimenT (FASET) at the University of Michigan Biological Station subjected 39 ha of forest to moderate disturbance in 2008 by advancing age-related tree mortality through the stem girdling of early successional aspen and birch. Stand-scale disturbance severity, expressed as relative basal area of girdled aspen and birch, was 39% but plot-scale severity varied substantially within the experimental area (9 to 66% in 0.1 ha plots) because of the heterogeneous distribution of aspen and birch. We used this disturbance severity gradient to examine: 1) the relationship between NPP resilience and disturbance severity; 2) the disturbance severity at which NPP resilience prompts a shift in dominance from canopy to subcanopy vegetation; 3) how NPP resilience relates to disturbance-driven changes in resource-use efficiency, and 4) how disturbance severity shapes emerging forest communities We found that NPP is highly resilient to low to moderate levels of disturbance, but that production declines once a higher disturbance threshold is exceeded. Several complementary mechanisms, including canopy structural reorganization and the reallocation of growth-limiting light and

  5. Net energy production associated with pathogen inactivation during mesophilic and thermophilic anaerobic digestion of sewage sludge.

    PubMed

    Ziemba, Christopher; Peccia, Jordan

    2011-10-15

    The potential for anaerobic digester energy production must be balanced with the sustainability of reusing the resultant biosolids for land application. Mesophilic, thermophilic, temperature-phased, and high temperature (60 or 70 °C) batch pre-treatment digester configurations have been systematically evaluated for net energy production and pathogen inactivation potential. Energy input requirements and net energy production were modeled for each digester scheme. First-order inactivation rate coefficients for Escherichia coli, Enterococcus faecalis and bacteriophage MS-2 were measured at each digester temperature and full-scale pathogen inactivation performance was estimated for each indicator organism and each digester configuration. Inactivation rates were found to increase dramatically at temperatures above 55 °C. Modeling full-scale performance using retention times based on U.S. EPA time and temperature constraints predicts a 1-2 log inactivation in mesophilic treatment, and a 2-5 log inactivation in 50-55 °C thermophilic and temperature-phased treatments. Incorporating a 60 or 70 °C batch pre-treatment phase resulted in dramatically higher potency, achieving MS-2 inactivation of 14 and 16 logs respectively, and complete inactivation (over 100 log reduction) of E. coli and E. faecalis. For temperatures less than 70 °C, viability staining of thermally-treated E. coli showed significantly reduced inactivation relative to standard culture enumeration. Due to shorter residence times in thermophilic reactors, the net energy production for all digesters was similar (less than 20% difference) with the 60 or 70 °C batch treatment configurations producing the most net energy and the mesophilic treatment producing the least. Incorporating a 60 or 70 °C pre-treatment phase can dramatically increase pathogen inactivation performance without decreasing net energy capture from anaerobic digestion. Energy consumption is not a significant barrier against

  6. Community-level net spillover of natural enemies from managed to natural forest.

    PubMed

    Frost, Carol M; Didham, Raphael K; Rand, Tatyana A; Peralta, Guadalupe; Tylianakis, Jason M

    2015-01-01

    Edge effects in fragmented natural habitats may De exaceroateci by intensive land use in the surrounding landscape. Given that most managed systems have higher primary productivity than adjacent natural systems, theory suggests that bottom-up subsidized consumers are likely to spill over from managed to natural habitats. Furthermore, the magnitude of spillover is likely to differ between generalist and specialist consumers, because of differences in their ability to use the full spectrum of resources. However, it is unknown whether there is indeed asymmetrical spillover of consumers between managed and natural habitats, and whether this is related to resource abundance or the trophic specialization of the consumer. We used flight intercept traps to measure spillover of generalist predators (Vespula wasps, Vespidae) and more specialist predators (106 species of parasitoids, Ichneumonidae and Braconidae) across habitat edges between native New Zealand forest and exotic plantation forest over a summer season. We found net spillover of both generalist and specialist predators from plantation to native forest, and that this was greater for generalists. To test whether natural enemy spillover from managed habitats was related to prey (caterpillar) abundance (i.e., whether it was bottom-up productivity driven, due to increased primary productivity), we conducted a large-scale herbivore reduction experiment at half of our plantation sites, by helicopter spraying caterpillar-specific insecticide over 2.5 ha per site. We monitored bidirectional natural enemy spillover and found that herbivore reduction reduced generalist but not specialist predator spillover. Trophic generalists may benefit disproportionately from high resource productivity in a habitat, and their cross-habitat spillover effects on natural food webs may be an important source of consumer pressure in mosaic landscapes. PMID:26236904

  7. Seasonal distribution of net primary production by functional groups in Chihuahuan Desert, and the role of seasonal precipitation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In hot deserts, precipitation is the principal driver for net primary production.  This study tested two hypotheses regarding aboveground net primary production (ANPP) and the effects of precipitation on ANPP in the Chihuahuan Desert, with emphasis on differences among seasons and among functional g...

  8. GLASS daytime all-wave net radiation product: Algorithm development and preliminary validation

    DOE PAGESBeta

    Jiang, Bo; Liang, Shunlin; Ma, Han; Zhang, Xiaotong; Xiao, Zhiqiang; Zhao, Xiang; Jia, Kun; Yao, Yunjun; Jia, Aolin

    2016-03-09

    Mapping surface all-wave net radiation (Rn) is critically needed for various applications. Several existing Rn products from numerical models and satellite observations have coarse spatial resolutions and their accuracies may not meet the requirements of land applications. In this study, we develop the Global LAnd Surface Satellite (GLASS) daytime Rn product at a 5 km spatial resolution. Its algorithm for converting shortwave radiation to all-wave net radiation using the Multivariate Adaptive Regression Splines (MARS) model is determined after comparison with three other algorithms. The validation of the GLASS Rn product based on high-quality in situ measurements in the United Statesmore » shows a coefficient of determination value of 0.879, an average root mean square error value of 31.61 Wm-2, and an average bias of 17.59 Wm-2. Furthermore, we also compare our product/algorithm with another satellite product (CERES-SYN) and two reanalysis products (MERRA and JRA55), and find that the accuracy of the much higher spatial resolution GLASS Rn product is satisfactory. The GLASS Rn product from 2000 to the present is operational and freely available to the public.« less

  9. Remote sensing of biomass and annual net aerial primary productivity of a salt marsh

    NASA Technical Reports Server (NTRS)

    Hardisky, M. A.; Klemas, V.; Daiber, F. C.; Roman, C. T.

    1984-01-01

    Net aerial primary productivity is the rate of storage of organic matter in above-ground plant issues exceeding the respiratory use by the plants during the period of measurement. It is pointed out that this plant tissue represents the fixed carbon available for transfer to and consumption by the heterotrophic organisms in a salt marsh or the estuary. One method of estimating annual net aerial primary productivity (NAPP) required multiple harvesting of the marsh vegetation. A rapid nondestructive remote sensing technique for estimating biomass and NAPP would, therefore, be a significant asset. The present investigation was designed to employ simple regression models, equating spectral radiance indices with Spartina alterniflora biomass to nondestructively estimate salt marsh biomass. The results of the study showed that the considered approach can be successfully used to estimate salt marsh biomass.

  10. Simulating net particle production and chiral magnetic current in a C P -odd domain

    NASA Astrophysics Data System (ADS)

    Fukushima, Kenji

    2015-09-01

    To address a question of whether the chiral magnetic current is a static polarization or a genuine flow of charged particles, we elucidate the numerical formulation to simulate the net production of right-handed particles and anomalous currents with C P -breaking background fields which cause an imbalance between particles and antiparticles. For a concrete demonstration we numerically impose pulsed electric and magnetic fields to confirm our answer to the question that the produced net particles flow in the dynamical chiral magnetic effect. The rate for the particle production and the chiral magnetic current generation is quantitatively consistent with the axial anomaly, while they appear with a finite response time. We emphasize the importance to quantify the response time that would suppress observable effects of the anomalous current.

  11. A comparison of shoreline seines with fyke nets for sampling littoral fish communities in floodplain lakes

    USGS Publications Warehouse

    Clark, S.J.; Jackson, J.R.; Lochmann, S.E.

    2007-01-01

    We compared shoreline seines with fyke nets in terms of their ability to sample fish species in the littoral zone of 22 floodplain lakes of the White River, Arkansas. Lakes ranged in size from less than 0.5 to 51.0 ha. Most contained large amounts of coarse woody debris within the littoral zone, thus making seining in shallow areas difficult. We sampled large lakes (>2 ha) using three fyke nets; small lakes (<2 ha) were sampled using two fyke nets. Fyke nets were set for 24 h. Large lakes were sampled with an average of 11 seine hauls/ lake and small lakes were sampled with an average of 3 seine hauls/lake, but exact shoreline seining effort varied among lakes depending on the amount of open shoreline. Fyke nets collected more fish and produced greater species richness and diversity measures than did seining. Species evenness was similar for the two gear types. Two species were unique to seine samples, whereas 13 species and 3 families were unique to fyke-net samples. Although fyke nets collected more fish and more species than did shoreline seines, neither gear collected all the species present in the littoral zone of floodplain lakes. These results confirm the need for a multiple-gear approach to fully characterize the littoral fish assemblages in floodplain lakes. ?? Copyright by the American Fisheries Society 2007.

  12. Incorporating benthic community changes into hydrochemical-based projections of coral reef calcium carbonate production under ocean acidification

    NASA Astrophysics Data System (ADS)

    Shaw, Emily C.; Hamylton, Sarah M.; Phinn, Stuart R.

    2016-06-01

    The existence of coral reefs is dependent on the production and maintenance of calcium carbonate (CaCO3) framework that is produced through calcification. The net production of CaCO3 will likely decline in the future, from both declining net calcification rates (decreasing calcification and increasing dissolution) and shifts in benthic community composition from calcifying organisms to non-calcifying organisms. Here, we present a framework for hydrochemical studies that allows both declining net calcification rates and changes in benthic community composition to be incorporated into projections of coral reef CaCO3 production. The framework involves upscaling net calcification rates for each benthic community type using mapped proportional cover of the benthic communities. This upscaling process was applied to the reef flats at One Tree and Lady Elliot reefs (Great Barrier Reef) and Shiraho Reef (Okinawa), and compared to existing data. Future CaCO3 budgets were projected for Lady Elliot Reef, predicting a decline of 53 % from the present value by end-century (800 ppm CO2) without any changes to benthic community composition. A further 5.7 % decline in net CaCO3 production is expected for each 10 % decline in calcifier cover, and net dissolution is predicted by end-century if calcifier cover drops below 18 % of the present extent. These results show the combined negative effect of both declining net calcification rates and changing benthic community composition on reefs and the importance of considering both processes for determining future reef CaCO3 production.

  13. Gross nitrous oxide production drives net nitrous oxide fluxes across a salt marsh landscape.

    PubMed

    Yang, Wendy H; Silver, Whendee L

    2016-06-01

    Sea level rise will change inundation regimes in salt marshes, altering redox dynamics that control nitrification - a potential source of the potent greenhouse gas, nitrous oxide (N2 O) - and denitrification, a major nitrogen (N) loss pathway in coastal ecosystems and both a source and sink of N2 O. Measurements of net N2 O fluxes alone yield little insight into the different effects of redox conditions on N2 O production and consumption. We used in situ measurements of gross N2 O fluxes across a salt marsh elevation gradient to determine how soil N2 O emissions in coastal ecosystems may respond to future sea level rise. Soil redox declined as marsh elevation decreased, with lower soil nitrate and higher ferrous iron in the low marsh compared to the mid and high marshes (P < 0.001 for both). In addition, soil oxygen concentrations were lower in the low and mid-marshes relative to the high marsh (P < 0.001). Net N2 O fluxes differed significantly among marsh zones (P = 0.009), averaging 9.8 ± 5.4 μg N m(-2)  h(-1) , -2.2 ± 0.9 μg N m(-2)  h(-1) , and 0.67 ± 0.57 μg N m(-2)  h(-1) in the low, mid, and high marshes, respectively. Both net N2 O release and uptake were observed in the low and high marshes, but the mid-marsh was consistently a net N2 O sink. Gross N2 O production was highest in the low marsh and lowest in the mid-marsh (P = 0.02), whereas gross N2 O consumption did not differ among marsh zones. Thus, variability in gross N2 O production rates drove the differences in net N2 O flux among marsh zones. Our results suggest that future studies should focus on elucidating controls on the processes producing, rather than consuming, N2 O in salt marshes to improve our predictions of changes in net N2 O fluxes caused by future sea level rise. PMID:26718748

  14. Investigating a Non-Mesh Mosquito Net among Outdoor Sleeping Nomadic Communities in Kenya

    PubMed Central

    Gore-Langton, Georgia R.; Mungai, James; Alenwi, Nfornuh; Abagira, Abdullahi; Bicknell, Owen M.; Harrison, Rebecca E.; Hassan, Farah Amin; Munga, Stephen; Eves, Katie; Juma, Elizabeth; Allan, Richard

    2015-01-01

    Rising reports of exophagic malaria vectors make even more pressing the need for alternatives to traditional, mesh, long-lasting insecticidal nets (LLINs) designed for indoor sleeping and often inadequate in the protection of outdoor-sleeping populations. This study tests and evaluates the retention, utilization, and durability of novel, non-mesh nets designed for outdoor use. Longitudinal, cross-sectional surveys were conducted, the physical condition of nets was assessed, and bio-efficacy and insecticide content were tested. At 22 months, retention was 98.0%; 97.1% of nets fell within the World Health Organization (WHO) category of being in “good” condition; none were in the “torn” category. At 18 months post-distribution, 100% of nets had at least WHO Pesticide Evaluation Scheme (WHOPES)-acceptable levels of insecticide, this proportion was 66.7% at 22 months. This novel mosquito net has the potential to provide a durable and context-specific tool to prevent malaria among traditionally hard-to-protect and highly vulnerable populations. PMID:26416107

  15. Building America Top Innovations 2012: Zero Net-Energy Homes Production Builder Business Case: California/Florida Production Builders

    SciTech Connect

    none,

    2013-01-01

    This Building America Top Innovations profile describes Grupe Homes of Sacramento’s work with Building America to design California’s first production-scale community of solar homes. The homes outsold neighboring developments two to one.

  16. Net methylmercury production in 2 contrasting stream sediments and associated accumulation and toxicity to periphyton.

    PubMed

    Klaus, Jaclyn E; Hammerschmidt, Chad R; Costello, David M; Burton, G Allen

    2016-07-01

    Periphyton uptake of bioaccumulative methylmercury (MeHg) may be an important entryway into the food web of many stream ecosystems where periphyton can be dominant primary producers. The net production of MeHg in stream sediment, its bioaccumulation in periphyton, and the potential toxicity of divalent Hg (Hg[II]) and MeHg in sediment to periphyton were investigated with a 67-d in situ incubation experiment using chemical exposure substrates containing either a fine-grained, organic-rich or a sandy, low-organic sediment, each amended with varying concentrations of mercuric chloride. Methylmercury was produced in sediment, and concentrations increased with greater amounts of added Hg(II); however, the net production of MeHg was inhibited in the highest Hg(II) treatments of both sediments. The range of total Hg concentrations that inhibited MeHg production was between approximately 80 000 ng Hg and 350 000 ng Hg per gram of organic matter for both sediments. Periphyton colonizing substrates accumulated MeHg in proportion to the concentration in sediment, but periphyton exposed to the sandy sediment accumulated approximately 20-fold more than those exposed to the organic-rich sediment relative to sediment MeHg concentrations. Toxicity of either Hg(II) or MeHg to periphyton was not observed with either periphyton organic content, net primary production, or respiration as endpoints. These results suggest that in situ production and bioaccumulation of MeHg in stream ecosystems can vary as a function of sediment characteristics and Hg(II) loadings to the sediment. Environ Toxicol Chem 2016;35:1759-1765. © 2015 SETAC. PMID:26636557

  17. NET-Works: Linking families, communities and primary care to prevent obesity in preschool-age children☆,☆☆

    PubMed Central

    Sherwood, Nancy E.; French, Simone A.; Veblen-Mortenson, Sara; Crain, A. Lauren; Berge, Jerica; Kunin-Batson, Alicia; Mitchell, Nathan; Senso, Meghan

    2014-01-01

    Obesity prevention in children offers a unique window of opportunity to establish healthful eating and physical activity behaviors to maintain a healthful body weight and avoid the adverse proximal and distal long-term health consequences of obesity. Given that obesity is the result of a complex interaction between biological, behavioral, family-based, and community environmental factors, intervention at multiple levels and across multiple settings is critical for both short- and long-term effectiveness. The Minnesota NET-Works (Now Everybody Together for Amazing and Healthful Kids) study is one of four obesity prevention and/or treatment trials that are part of the Childhood Obesity Prevention and Treatment (COPTR) Consortium. The goal of the NET-Works study is to evaluate an intervention that integrates home, community, primary care and neighborhood strategies to promote healthful eating, activity patterns, and body weight among low income, racially/ethnically diverse preschool-age children. Critical to the success of this intervention is the creation of linkages among the settings to support parents in making home environment and parenting behavior changes to foster healthful child growth. Five hundred racially/ethnically diverse, two–four year old children and their parent or primary caregiver will be randomized to the multi-component intervention or to a usual care comparison group for a three-year period. This paper describes the study design, measurement and intervention protocols, and statistical analysis plan for the NET-Works trial. PMID:24120933

  18. Effects of organic matter amendments on net primary productivity and greenhouse gas emissions in annual grasslands.

    PubMed

    Ryals, Rebecca; Silver, Whendee L

    2013-01-01

    Most of the world's grasslands are managed for livestock production. A critical component of the long-term sustainability and profitability of rangelands (e.g., grazed grassland ecosystems) is the maintenance of plant production. Amending grassland soils with organic waste has been proposed as a means to increase net primary productivity (NPP) and ecosystem carbon (C) storage, while mitigating greenhouse gas emissions from waste management. Few studies have evaluated the effects of amendments on the C balance and greenhouse gas dynamics of grasslands. We used field manipulations replicated within and across two rangelands (a valley grassland and a coastal grassland) to determine the effects of a single application of composted green waste amendments on NPP and greenhouse gas emissions over three years. Amendments elevated total soil respiration by 18% +/- 4% at both sites but had no effect on nitrous oxide or methane emissions. Carbon losses were significantly offset by greater and sustained plant production. Amendments stimulated both above- and belowground NPP by 2.1 +/- 0.8 Mg C/ha to 4.7 +/- 0.7 Mg C/ha (mean +/- SE) over the three-year study period. Net ecosystem C storage increased by 25-70% without including the direct addition of compost C. The estimated magnitude of net ecosystem C storage was sensitive to estimates of heterotrophic soil respiration but was greater than controls in five out of six fields that received amendments. The sixth plot was the only one that exhibited lower soil moisture than the control, suggesting an important role of water limitation in these seasonally dry ecosystems. Treatment effects persisted over the course of the study, which were likely derived from increased water-holding capacity in most plots, and slow-release fertilization from compost decomposition. We conclude that a single application of composted organic matter can significantly increase grassland C storage, and that effects of a single application are likely to

  19. Mobile health and patient engagement in the safety net: a survey of community health centers and clinics.

    PubMed

    Broderick, Andrew; Haque, Farshid

    2015-05-01

    Patient-centered technologies have emerged as a way to actively engage patients in care. The reach and potential of cell phones to engage diverse patient populations is great. Evidence of their effectiveness in improving health-related outcomes is limited. Researchers conducted an online survey of community health centers and clinics to assess if and how health care providers in the safety net use cell phones to support patient engagement. The findings indicate that the use of cell phones in patient care is at an early stage of deployment across the safety net. Organizations identify chronic disease management as an area where cell phones offer considerable potential to effectively engage patients. To promote widespread adoption and use, technical assistance to support the implementation and management of interventions, evidence-based or best practice models that highlight successful implementation strategies in care delivery, and the introduction of new payment or reimbursement policies will be essential. PMID:26040018

  20. Assessment of the Impact of Urban Sprawl on Net Primary Productivity

    NASA Astrophysics Data System (ADS)

    Milesi, C.; Elvidge, C. D.; Nemani, R. R.; Running, S. W.

    2002-12-01

    While urban areas are generally thought to reduce the photosynthetic capacity of the land, little research has been devoted to quantifying the net effect of urbanization on net primary productivity (NPP). The southeastern United States has undergone one of the highest rates of landscape change and urban sprawl in the country, representing an ideal study area in which to develop a remote sensing based methodology for a regional assessment of the impact or urbanization on ecosystem productivity. We used a combination of MODIS and nighttime Defense Meteorological Satellite Program / Operational Linescan System (DMSP/OLS) data to estimate the extent of recent urban sprawl and its impact on regional NPP in the southeastern United States. The analysis based on the nighttime data indicated that in 1992/93 urban areas amount to 4.5 % of the total surface in the region. In the year 2000, the nighttime data revealed an increase in urban developed land by 1.9 %. Estimates derived from the MODIS data indicated that land cover changes due to urban development that took place during the analyzed period reduced annual NPP of the southeastern United States by 0.4 %. Results from this study indicated that the combination of MODIS products such as NPP with nighttime data could provide rapid assessment of urban land cover changes and their impact on ecosystem productivity.

  1. Net ecosystem production, calcification and CO2 fluxes on a reef flat in Northeastern Brazil

    NASA Astrophysics Data System (ADS)

    Longhini, Cybelle M.; Souza, Marcelo F. L.; Silva, Ananda M.

    2015-12-01

    The carbon cycle in coral reefs is usually dominated by the organic carbon metabolism and precipitation-dissolution of CaCO3, processes that control the CO2 partial pressure (pCO2) in seawater and the CO2 fluxes through the air-sea interface. In order to characterize these processes and the carbonate system, four sampling surveys were conducted at the reef flat of Coroa Vermelha during low tide (exposed flat). Net ecosystem production (NEP), net precipitation-dissolution of CaCO3 (G) and CO2 fluxes across the air-water interface were calculated. The reef presented net autotrophy and calcification at daytime low tide. The NEP ranged from -8.7 to 31.6 mmol C m-2 h-1 and calcification from -13.1 to 26.0 mmol C m-2 h-1. The highest calcification rates occurred in August 2007, coinciding with the greater NEP rates. The daytime CO2 fluxes varied from -9.7 to 22.6 μmol CO2 m-2 h-1, but reached up to 13,900 μmol CO2 m-2 h-1 during nighttime. Carbon dioxide influx to seawater was predominant in the reef flat during low tide. The regions adjacent to the reef showed a supersaturation of CO2, acting as a source of CO2 to the atmosphere (from -22.8 to -2.6 mol CO2 m-2 h-1) in the reef flat during ebbing tide. Nighttime gas release to the atmosphere indicates a net CO2 release from the Coroa Vermelha reef flat within 24 h, and that these fluxes can be important to carbon budget in coral reefs.

  2. Southern Ocean Seasonal Net Production from Satellite, Atmosphere, and Ocean Data Sets

    NASA Technical Reports Server (NTRS)

    Keeling, Ralph F.; Campbell, J. (Technical Monitor)

    2002-01-01

    A new climatology of monthly air-sea O2 flux was developed using the net air-sea heat flux as a template for spatial and temporal interpolation of sparse hydrographic data. The climatology improves upon the previous climatology of Najjar and Keeling in the Southern Hemisphere, where the heat-based approach helps to overcome limitations due to sparse data coverage. The climatology is used to make comparisons with productivity derived from CZCS images. The climatology is also used in support of an investigation of the plausible impact of recent global warming an oceanic O2 inventories.

  3. Comparing global models of terrestrial net primary productivity (NPP): Global pattern and differentiation by major biomes

    USGS Publications Warehouse

    Kicklighter, D.W.; Bondeau, A.; Schloss, A.L.; Kaduk, J.; McGuire, A.D.

    1999-01-01

    Annual and seasonal net primary productivity estimates (NPP) of 15 global models across latitudinal zones and biomes are compared. The models simulated NPP for contemporary climate using common, spatially explicit data sets for climate, soil texture, and normalized difference vegetation index (NDVI). Differences among NPP estimates varied over space and time. The largest differences occur during the summer months in boreal forests (50??to 60??N) and during the dry seasons of tropical evergreen forests. Differences in NPP estimates are related to model assumptions about vegetation structure, model parameterizations, and input data sets.

  4. Worldwide estimates and bibliography of net primary productivity derived from pre-1982 publications

    SciTech Connect

    Esser, G.; Lieth, H.F.H.; Scurlock, J.M.O.; Olson, R.J.

    1997-10-01

    An extensive compilation of more than 700 field estimates of net primary productivity of natural and agricultural ecosystems worldwide was synthesized in Germany in the 1970s and early 1980s. Although the Osnabrueck data set has not been updated since the 1980s, it represents a wealth of information for use in model development and validation. This report documents the development of this data set, its contents, and its recent availability on the Internet from the Oak Ridge National Laboratory Distributed Active Archive Center for Biogeochemical Dynamics. Caution is advised in using these data, which necessarily include assumptions and conversions that may not be universally applicable to all sites.

  5. Net primary productivity of forest stands in New Hampshire estimated from Landsat and MODIS satellite data

    PubMed Central

    Potter, Christopher; Gross, Peggy; Genovese, Vanessa; Smith, Marie-Louise

    2007-01-01

    Background A simulation model that relies on satellite observations of vegetation cover from the Landsat 7 sensor and from the Moderate Resolution Imaging Spectroradiometer (MODIS) was used to estimate net primary productivity (NPP) of forest stands at the Bartlett Experiment Forest (BEF) in the White Mountains of New Hampshire. Results Net primary production (NPP) predicted from the NASA-CASA model using 30-meter resolution Landsat inputs showed variations related to both vegetation cover type and elevational effects on mean air temperatures. Overall, the highest predicted NPP from the NASA-CASA model was for deciduous forest cover at low to mid-elevation locations over the landscape. Comparison of the model-predicted annual NPP to the plot-estimated values showed a significant correlation of R2 = 0.5. Stepwise addition of 30-meter resolution elevation data values explained no more than 20% of the residual variation in measured NPP patterns at BEF. Both the Landsat 7 and the 250-meter resolution MODIS derived mean annual NPP predictions for the BEF plot locations were within ± 2.5% of the mean of plot estimates for annual NPP. Conclusion Although MODIS imagery cannot capture the spatial details of NPP across the network of closely spaced plot locations as well as Landsat, the MODIS satellite data as inputs to the NASA-CASA model does accurately predict the average annual productivity of a site like the BEF. PMID:17941989

  6. Ozone Effects on Global Net Primary Production and Carbon Sequestration Using a Biogeochemistry Model

    NASA Astrophysics Data System (ADS)

    Felzer, B. S.; Kicklighter, D. W.; Melillo, J. M.; Wang, C.; Zhuang, Q.; Prinn, R. G.

    2002-12-01

    The effects of air pollution on vegetation may provide another important control on the carbon cycle that has not yet been widely considered. Prolonged exposure to high levels of ozone, in particular, has been observed to inhibit photosynthesis by direct cellular damage within the leaves and through changes in stomatal conductance. We have incorporated simple empirical equations derived for hardwoods, pines, and crops into the Terrestrial Ecosystem Model (TEM, version 4.3) to explore spatial and temporal variations of ozone effects on net primary productivity (NPP) and carbon sequestration across the globe. Although our results show up to a 2% reduction in annual NPP as a result of historical ozone levels during the late 1980s-early 1990s, regionally this reduction is much larger. The largest decreases (up to 39% in some locations) occur in the eastern U.S., Europe, and China, during months with high ozone levels and substantial production. Carbon sequestration during the early 1990s is reduced by as much as 0.43 PgC/yr, or 15%, with the presence of ozone. Thus the effects of ozone on net primary production and carbon sequestration should be factored into future calculations of the global carbon budget.

  7. Global human appropriation of net primary production doubled in the 20th century.

    PubMed

    Krausmann, Fridolin; Erb, Karl-Heinz; Gingrich, Simone; Haberl, Helmut; Bondeau, Alberte; Gaube, Veronika; Lauk, Christian; Plutzar, Christoph; Searchinger, Timothy D

    2013-06-18

    Global increases in population, consumption, and gross domestic product raise concerns about the sustainability of the current and future use of natural resources. The human appropriation of net primary production (HANPP) provides a useful measure of human intervention into the biosphere. The productive capacity of land is appropriated by harvesting or burning biomass and by converting natural ecosystems to managed lands with lower productivity. This work analyzes trends in HANPP from 1910 to 2005 and finds that although human population has grown fourfold and economic output 17-fold, global HANPP has only doubled. Despite this increase in efficiency, HANPP has still risen from 6.9 Gt of carbon per y in 1910 to 14.8 GtC/y in 2005, i.e., from 13% to 25% of the net primary production of potential vegetation. Biomass harvested per capita and year has slightly declined despite growth in consumption because of a decline in reliance on bioenergy and higher conversion efficiencies of primary biomass to products. The rise in efficiency is overwhelmingly due to increased crop yields, albeit frequently associated with substantial ecological costs, such as fossil energy inputs, soil degradation, and biodiversity loss. If humans can maintain the past trend lines in efficiency gains, we estimate that HANPP might only grow to 27-29% by 2050, but providing large amounts of bioenergy could increase global HANPP to 44%. This result calls for caution in refocusing the energy economy on land-based resources and for strategies that foster the continuation of increases in land-use efficiency without excessively increasing ecological costs of intensification. PMID:23733940

  8. Community-randomized trial of lambdacyhalothrin-treated hammock nets for malaria control in Yanomami communities in the Amazon region of Venezuela.

    PubMed

    Magris, M; Rubio-Palis, Y; Alexander, N; Ruiz, B; Galván, N; Frias, D; Blanco, M; Lines, J

    2007-03-01

    We conducted a community-randomized controlled trial in an area of moderate malaria transmission in the Amazon region, southern Venezuela, home of the Yanomami indigenous ethnic group. The aim was to compare the malaria incidence rate in villages with lambdacyhalothrin-treated hammock nets (ITHN) or with placebo-treated hammock nets (PTHN). In both arms of the study, intensive surveillance for early case detection was maintained and prompt malaria treatment was administered. Baseline data were collected before the intervention and a population of around 924 Yanomami was followed for 2 years. Despite the recent introduction of nets in the Yanomami villages and the adverse natural conditions in the area, the nets were accepted enthusiastically by the study population, used conscientiously and looked after carefully. The malaria incidence rate per thousand person-years at risk was 114.6 in the IHTN group and 186.8 in the PTHN group. The adjusted rate ratios indicated that ITHN prevent 56% [IRR: 0.44, 95% confidence interval (CI): 52-59%] of new malaria cases. ITHN reduced the prevalence of parasitaemia by 83% [relative risks (RR): 0.17, 95% CI: 47-100%], according to a cross-sectional survey carried out during the high transmission season. The prevalence of splenomegaly and anaemia was too low to detect any possible reduction as a result of ITHN. The main conclusion of the present study is that ITHN can reduce malaria incidence in the area and it is the most feasible method for malaria control in a forested area where indigenous villages are scattered over a large territory. This is the first community-level epidemiological trial to show that ITHN are highly effective against malaria transmitted by Anopheles darlingi. PMID:17313511

  9. A framework for evaluating safety-net and other community-level factors on access for low-income populations.

    PubMed

    Davidson, Pamela L; Andersen, Ronald M; Wyn, Roberta; Brown, E Richard

    2004-01-01

    The framework presented in this article extends the Andersen behavioral model of health services utilization research to examine the effects of contextual determinants of access. A conceptual framework is suggested for selecting and constructing contextual (or community-level) variables representing the social, economic, structural, and public policy environment that influence low-income people's use of medical care. Contextual variables capture the characteristics of the population that disproportionately relies on the health care safety net, the public policy support for low-income and safety-net populations, and the structure of the health care market and safety-net services within that market. Until recently, the literature in this area has been largely qualitative and descriptive and few multivariate studies comprehensively investigated the contextual determinants of access. The comprehensive and systematic approach suggested by the framework will enable researchers to strengthen the external validity of results by accounting for the influence of a consistent set of contextual factors across locations and populations. A subsequent article in this issue of Inquiry applies the framework to examine access to ambulatory care for low-income adults, both insured and uninsured. PMID:15224958

  10. Comparing the Net Ecosystem Exchange of Two Cropping Systems for Dairy Feed Production

    NASA Astrophysics Data System (ADS)

    Sulaiman, M. F.; Wagner-Riddle, C.; Brown, S. E.

    2015-12-01

    A three-year study was conducted from 2012 to 2014 to determine the net CO2 fluxes from corn and hay, the two main feed crops used in dairy production. The aim of this study is to better understand the net ecosystem exchange (NEE) in annual and perennial cropping systems used in dairy production to benefit greenhouse gas emission model developments and the life cycle analysis of dairy production. The study was conducted on two 4-ha plots where one plot was a 5-year old hayfield and the other plot was planted in a continuous cycle corn. All plots were continuously monitored using the flux-gradient method deployed with a tunable diode laser trace gas analyzer and sonic anemometers. All plots received dairy manure as fertilizer applied according to common practice. The cumulative NEE for the three years of the study was -873.15 g C m-2 for corn and -409.36 g C m-2 for hay. Differences in respiration between the two cropping systems was found to be the larger factor compared to differences in gross ecosystem production (GEP) that resulted in the contrasting cumulative NEE where cumulative respiration for the three years for hay was 3094.23 g C m-2 as opposed to 2078.11 g C m-2 for corn. Cumulative GEP for the three years was 3503.60 and 2951.31 g C m-2 for hay and corn respectively. Inter-annual and inter-crop variability of the NEE, GEP and respiration will be discussed in relation to biomass production, climatic conditions and crop physiological characteristics.

  11. Estimating crop net primary production using inventory data and MODIS-derived parameters

    SciTech Connect

    Bandaru, Varaprasad; West, Tristram O.; Ricciuto, Daniel M.; Izaurralde, Roberto C.

    2013-06-03

    National estimates of spatially-resolved cropland net primary production (NPP) are needed for diagnostic and prognostic modeling of carbon sources, sinks, and net carbon flux. Cropland NPP estimates that correspond with existing cropland cover maps are needed to drive biogeochemical models at the local scale and over national and continental extents. Existing satellite-based NPP products tend to underestimate NPP on croplands. A new Agricultural Inventory-based Light Use Efficiency (AgI-LUE) framework was developed to estimate individual crop biophysical parameters for use in estimating crop-specific NPP. The method is documented here and evaluated for corn and soybean crops in Iowa and Illinois in years 2006 and 2007. The method includes a crop-specific enhanced vegetation index (EVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS), shortwave radiation data estimated using Mountain Climate Simulator (MTCLIM) algorithm and crop-specific LUE per county. The combined aforementioned variables were used to generate spatially-resolved, crop-specific NPP that correspond to the Cropland Data Layer (CDL) land cover product. The modeling framework represented well the gradient of NPP across Iowa and Illinois, and also well represented the difference in NPP between years 2006 and 2007. Average corn and soybean NPP from AgI-LUE was 980 g C m-2 yr-1 and 420 g C m-2 yr-1, respectively. This was 2.4 and 1.1 times higher, respectively, for corn and soybean compared to the MOD17A3 NPP product. Estimated gross primary productivity (GPP) derived from AgI-LUE were in close agreement with eddy flux tower estimates. The combination of new inputs and improved datasets enabled the development of spatially explicit and reliable NPP estimates for individual crops over large regional extents.

  12. Establishing and Expanding a Web Community Called NorthStarNet

    ERIC Educational Resources Information Center

    Minarik, Alan; Stoll, Christina

    2005-01-01

    These pioneers set out to set up new communities in the virtual frontier. Now, more than 50 libraries serve as Web hubs for their local settlements. The communities we live in have changed over time. But no matter the size of the tallest building, no matter how advanced the infrastructure, they grew to that size from humble beginnings: a…

  13. Economic Development Program, California Community Colleges: ED>Net 1998-1999 Annual Report.

    ERIC Educational Resources Information Center

    California Community Colleges, Sacramento. Economic Development Coordination Network (EDNet).

    This report describes economic development programs operated by California Community Colleges during fiscal year 1998-1999. Report highlights include: (1) 60 of 107 community colleges (48 of 72 districts) operated an economic development program; (2) eight economic development programs engaged primarily in delivering training and technical…

  14. Use of MODIS Sensor Images Combined with Reanalysis Products to Retrieve Net Radiation in Amazonia

    PubMed Central

    de Oliveira, Gabriel; Brunsell, Nathaniel A.; Moraes, Elisabete C.; Bertani, Gabriel; dos Santos, Thiago V.; Shimabukuro, Yosio E.; Aragão, Luiz E. O. C.

    2016-01-01

    In the Amazon region, the estimation of radiation fluxes through remote sensing techniques is hindered by the lack of ground measurements required as input in the models, as well as the difficulty to obtain cloud-free images. Here, we assess an approach to estimate net radiation (Rn) and its components under all-sky conditions for the Amazon region through the Surface Energy Balance Algorithm for Land (SEBAL) model utilizing only remote sensing and reanalysis data. The study period comprised six years, between January 2001–December 2006, and images from MODIS sensor aboard the Terra satellite and GLDAS reanalysis products were utilized. The estimates were evaluated with flux tower measurements within the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) project. Comparison between estimates obtained by the proposed method and observations from LBA towers showed errors between 12.5% and 16.4% and 11.3% and 15.9% for instantaneous and daily Rn, respectively. Our approach was adequate to minimize the problem related to strong cloudiness over the region and allowed to map consistently the spatial distribution of net radiation components in Amazonia. We conclude that the integration of reanalysis products and satellite data, eliminating the need for surface measurements as input model, was a useful proposition for the spatialization of the radiation fluxes in the Amazon region, which may serve as input information needed by algorithms that aim to determine evapotranspiration, the most important component of the Amazon hydrological balance. PMID:27347957

  15. Use of MODIS Sensor Images Combined with Reanalysis Products to Retrieve Net Radiation in Amazonia.

    PubMed

    de Oliveira, Gabriel; Brunsell, Nathaniel A; Moraes, Elisabete C; Bertani, Gabriel; Dos Santos, Thiago V; Shimabukuro, Yosio E; Aragão, Luiz E O C

    2016-01-01

    In the Amazon region, the estimation of radiation fluxes through remote sensing techniques is hindered by the lack of ground measurements required as input in the models, as well as the difficulty to obtain cloud-free images. Here, we assess an approach to estimate net radiation (Rn) and its components under all-sky conditions for the Amazon region through the Surface Energy Balance Algorithm for Land (SEBAL) model utilizing only remote sensing and reanalysis data. The study period comprised six years, between January 2001-December 2006, and images from MODIS sensor aboard the Terra satellite and GLDAS reanalysis products were utilized. The estimates were evaluated with flux tower measurements within the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) project. Comparison between estimates obtained by the proposed method and observations from LBA towers showed errors between 12.5% and 16.4% and 11.3% and 15.9% for instantaneous and daily Rn, respectively. Our approach was adequate to minimize the problem related to strong cloudiness over the region and allowed to map consistently the spatial distribution of net radiation components in Amazonia. We conclude that the integration of reanalysis products and satellite data, eliminating the need for surface measurements as input model, was a useful proposition for the spatialization of the radiation fluxes in the Amazon region, which may serve as input information needed by algorithms that aim to determine evapotranspiration, the most important component of the Amazon hydrological balance. PMID:27347957

  16. Cultivating a Cycle of Trust With Diverse Communities in Practice-Based Research: A Report From PRIME Net

    PubMed Central

    Getrich, Christina M.; Sussman, Andrew L.; Campbell-Voytal, Kimberly; Tsoh, Janice Y.; Williams, Robert L.; Brown, Anthony E.; Potter, Michael B.; Spears, William; Weller, Nancy; Pascoe, John; Schwartz, Kendra; Neale, Anne Victoria

    2013-01-01

    PURPOSE Practice-based research networks (PBRNs) are increasingly seen as important vehicles to translate research into practice, although less is known about the process of engaging diverse communities in PBRN research. The objective of this study was to identify strategies for successfully recruiting and retaining diverse racial/ethnic communities into PBRN research studies. METHODS This collaborative, multisite study engaged 5 of the 8 networks of the PRImary care MultiEthnic Network (PRIME Net) consortium that conducts research with traditionally underrepresented/underserved populations. We used a sequential, qualitative research design. We first conducted 1 key informant interview with each of 24 researchers experienced in recruiting research participants from 5 racial/ethnic communities (African American, Arab/Chaldean, Chinese, Hispanic, and Native American). Subsequently, we conducted 18 focus groups with 172 persons from these communities. RESULTS Participants’ comments indicated that successful recruitment and retention of underrepresented populations in PBRN studies is linked to the overall research process. This process, which we termed the cycle of trust, entailed developing and sustaining relationships of trust during 4 interrelated stages: before the study, during study recruitment, throughout study conduct, and after study completion. Participants identified a set of flexible strategies within each stage and called for close engagement with clinic and community partners. CONCLUSIONS Our participants suggest that approaches to research that lay a foundation of trust, demonstrate respect for community members, and extend beyond the enrollment and data collection phases are essential to enhance the participation of diverse populations in PBRN research. These findings offer the PBRN community a guide toward achieving this important goal. PMID:24218379

  17. Malaria knowledge and long-lasting insecticidal net use in rural communities of central Côte d'Ivoire

    PubMed Central

    2011-01-01

    Background To improve effectiveness of malaria control interventions, it is essential to deepen the knowledge of contextual factors that govern people's practice for preventive and curative measures. The aim of this study was to determine factors that influence the use of long-lasting insecticidal nets (LLINs) in three rural communities of Côte d'Ivoire, two of which benefited from recent interventions. Methods The study was carried out in 957 households in three villages (Bozi, N'Dakonankro and Yoho) located in central Côte d'Ivoire. Indicators of socioeconomic position (SEP), malaria knowledge and practice, placing special emphasis on LLINs, were investigated during a cross-sectional questionnaire survey. Principal component analysis was used to calculate the SEP of households by means of a list of household assets ownership. The concentration index was used to assess the direction of the association between SEP and a given variable. To compare groups or means, Fisher's exact test, χ2 and Kruskal-Wallis test were used, as appropriate. Results Significant differences were found between SEP and reported malaria symptoms, such as fever or hot body, convulsion, anaemia and jaundice (yellow eyes). Individuals from the least poor group cited more often the use of bed nets and insecticide-treated nets (ITNs) compared to poorer groups. The mean number of individuals reporting the use of bed nets and LLINs was different between groups with different educational level. Moreover, the mean number of LLINs in a household was influenced by the presence of children below five years of age. Conclusion The study not only confirmed that education and SEP play important roles in the prevention and control of malaria and promotion of health in general, but pointed at the basic essential knowledge and the key behavioural elements that should guide education and learning processes among the poorer segments of the population. In turn, such knowledge may change behaviour and lead to

  18. Observation and simulation of net primary productivity in Qilian Mountain, western China.

    PubMed

    Zhou, Y; Zhu, Q; Chen, J M; Wang, Y Q; Liu, J; Sun, R; Tang, S

    2007-11-01

    We modeled net primary productivity (NPP) at high spatial resolution using an advanced spaceborne thermal emission and reflection radiometer (ASTER) image of a Qilian Mountain study area using the boreal ecosystem productivity simulator (BEPS). Two key driving variables of the model, leaf area index (LAI) and land cover type, were derived from ASTER and moderate resolution imaging spectroradiometer (MODIS) data. Other spatially explicit inputs included daily meteorological data (radiation, precipitation, temperature, humidity), available soil water holding capacity (AWC), and forest biomass. NPP was estimated for coniferous forests and other land cover types in the study area. The result showed that NPP of coniferous forests in the study area was about 4.4 tCha(-1)y(-1). The correlation coefficient between the modeled NPP and ground measurements was 0.84, with a mean relative error of about 13.9%. PMID:17129660

  19. Comparing the impact of the 2003 and 2010 heatwaves on Net Primary Production in Europe

    NASA Astrophysics Data System (ADS)

    Bastos, Ana; Gouveia, Célia M.; Trigo, Ricardo M.; Running, Steve W.

    2013-04-01

    Climate variability is known to influence primary productivity on land ecosystems (Nemani et al., 2003). In particular, extreme climatic events such as major droughts and heatwaves are known to have severe impact on primary productivity and, therefore, to affect significantly the carbon dioxide uptake by land ecosystems at regional (Ciais et al., 2005) or even global scale (Zhao and Running, 2010). In the last decade, Europe was struck by two outstanding heatwaves, the 2003 event in Western Europe and the recent 2010 episode over Eastern Europe. Both were characterised by record breaking temperatures at the daily, weekly, monthly and seasonal scales, although the amplitude and spatial extent of the 2010 mega-heatwave surpassed the 2003 event (Barriopedro et al., 2011). This work aims to assess the influence of both mega-heatwaves on yearly Net Primary Production (NPP) and seasonal Net Photosynthesis (NP), which corresponds to the difference between Gross Primary Production and maintenance respiration. The work relies on yearly NPP and monthly NP data derived from satellite imagery obtained from MODIS (Moderate Resolution Imaging Spectroradiometer) sensor at 1km spatial resolution. Data were selected for the period between 2000 and 2011 over a region extending from 34.6N to 73.5N and 12.1W to 46.8E, covering Eurasia. In 2010 very low primary production anomalies are observed over a very large area in Eastern Europe, at the monthly, seasonal and yearly scale. In western Russia, yearly NPP anomalies fall below 50% of average. These widespread negative anomalous values of NP fields over the western Russia region match the patterns of very high temperature values combined with below-average precipitation, at the seasonal (summer) scale. Moreover, the impact of the heatwave is not only evident at the regional level but also at the wider continental (European) scale and is significantly more extensive and intense than the corresponding heatwave of 2003 in Western Europe

  20. Estimating crop net primary production using national inventory data and MODIS-derived parameters

    NASA Astrophysics Data System (ADS)

    Bandaru, Varaprasad; West, Tristram O.; Ricciuto, Daniel M.; César Izaurralde, R.

    2013-06-01

    National estimates of spatially-resolved cropland net primary production (NPP) are needed for diagnostic and prognostic modeling of carbon sources, sinks, and net carbon flux between land and atmosphere. Cropland NPP estimates that correspond with existing cropland cover maps are needed to drive biogeochemical models at the local scale as well as national and continental scales. Existing satellite-based NPP products tend to underestimate NPP on croplands. An Agricultural Inventory-based Light Use Efficiency (AgI-LUE) framework was developed to estimate individual crop biophysical parameters for use in estimating crop-specific NPP over large multi-state regions. The method is documented here and evaluated for corn (Zea mays L.) and soybean (Glycine max L. Merr.) in Iowa and Illinois in 2006 and 2007. The method includes a crop-specific Enhanced Vegetation Index (EVI), shortwave radiation data estimated using the Mountain Climate Simulator (MTCLIM) algorithm, and crop-specific LUE per county. The combined aforementioned variables were used to generate spatially-resolved, crop-specific NPP that corresponds to the Cropland Data Layer (CDL) land cover product. Results from the modeling framework captured the spatial NPP gradient across croplands of Iowa and Illinois, and also represented the difference in NPP between years 2006 and 2007. Average corn and soybean NPP from AgI-LUE was 917 g C m-2 yr-1 and 409 g C m-2 yr-1, respectively. This was 2.4 and 1.1 times higher, respectively, for corn and soybean compared to the MOD17A3 NPP product. Site comparisons with flux tower data show AgI-LUE NPP in close agreement with tower-derived NPP, lower than inventory-based NPP, and higher than MOD17A3 NPP. The combination of new inputs and improved datasets enabled the development of spatially explicit and reliable NPP estimates for individual crops over large regional extents.

  1. The Nitrogen Budget of a Northern Hardwood Forest: Sources and net Primary Productivity Requirements

    NASA Astrophysics Data System (ADS)

    Nave, L. E.; Vogel, C. S.; Gough, C. M.; Curtis, P. S.

    2006-12-01

    Nitrogen (N) limits net primary productivity (NPP) in most forests. Nearly all N required for NPP comes from decomposing organic matter, and is continuously recycled within the forest. However, atmospheric N deposition may augment forest N supply, increasing NPP. To quantify internal N cycling, atmospheric N inputs, and NPP, we developed an ecosystem-scale nitrogen (N) budget for a mixed deciduous forest in northern lower Michigan, USA. Sources of N were net N-mineralization (Nmin), wet (Dw) and bulk (Db) atmospheric N deposition, and canopy retention of bulk N deposition (CRN). We also quantified the N requirement of NPP, which was measured by biometric inventory of annual leaf, above- and belowground wood, and fine root mass production. Nmin supplied 44.3 kg N ha-1 yr-1 (88% of total annual N supply), while inorganic Dw supplied 4.8 kg N ha-1yr-1 (9% of total). Bulk organic N deposition contributed 1.5 kg N ha-1, or 3% of the total annual N supply. The forest canopy retained 2.2 kg N ha-1 of total Db, suggesting that 4% of the annual NPP N requirement could be met through canopy N uptake, if all N retained by the canopy was assimilated. Of the 53.5 kg N ha-1 yr-1 required for NPP, 61% was for fine root production, 32% was for leaf production, and 7% was for wood. Our N supply and forest NPP N requirement estimates were very close, with quantified N sources supplying 94% of the annual NPP N requirement. At our site, where Dw and organic Db provide 12% of the annual NPP N requirement, atmospheric N deposition makes a small but significant contribution to NPP. However, the minor contribution of CRN to the annual NPP N requirement indicates that N retained by the canopy has little effect on forest growth.

  2. Grassland and Cropland Net Ecosystem Production of the U.S. Great Plains

    NASA Astrophysics Data System (ADS)

    Howard, D. M.; Wylie, B. K.; Ji, L.; Gilmanov, T. G.; Zhang, L.

    2014-12-01

    At observation sites throughout the world, carbon dioxide (CO2) levels and other ecosystem resources are measured by instruments known as flux towers. Although flux towers only measure the surrounding vicinity or spatial footprint of their placement ecosystem, the data recorded at these towers can be up-scaled to much greater levels through the use of comprehensive remote sensing data and advanced computer modeling. The purpose of this study was to develop ecological net ecosystem production (NEP) models capable of producing weekly cropland and grassland NEP maps of the U.S. Great Plains at 250 meter resolution for 2000 - 2008. Separate NEP regression tree models were developed for each land cover type (cropland and grassland) with 15 flux towers supporting the grassland model and 13 towers supporting the cropland model. The NEP regression tree models were established through training based on data from the supporting flux towers, remote sensing data, and other biogeophysical inputs. Map results of this study indicate, as anticipated, grassland ecosystems generally perform as net carbon (C) sinks, absorbing and storing C from the atmosphere, and conversely, croplands generally as net C sources (crop yields were not taken into account), releasing C, in the form of CO2, into the atmosphere. The models were evaluated by implementing a leave-one-out cross validation method, which withholds data form one particular year or site for testing a model developed with the remaining data. The cropland model validation analysis received an average Pearson's correlation coefficient (r) of 0.85 for the yearly validation and an average r = 0.73 for the site withholding. The grassland model validation analysis received an average r = 0.86 for the yearly validation and an average r = 0.83 for the site withholding.

  3. Net primary production of a temperate deciduous forest exhibits a threshold response to increasing disturbance severity.

    PubMed

    Stuart-Haëntjens, Ellen J; Curtis, Peter S; Fahey, Robert T; Vogel, Christoph S; Gough, Christopher M

    2015-09-01

    The global carbon (C) balance is vulnerable to disturbances that alter terrestrial C storage. Disturbances to forests occur along a continuum of severity, from low-intensity disturbance causing the mortality or defoliation of only a subset of trees to severe stand- replacing disturbance that kills all trees; yet considerable uncertainty remains in how forest production changes across gradients of disturbance intensity. We used a gradient of tree mortality in an upper Great Lakes forest ecosystem to: (1) quantify how aboveground wood net primary production (ANPP,) responds to a range of disturbance severities; and (2) identify mechanisms supporting ANPPw resistance or resilience following moderate disturbance. We found that ANPPw declined nonlinearly with rising disturbance severity, remaining stable until >60% of the total tree basal area senesced. As upper canopy openness increased from disturbance, greater light availability to the subcanopy enhanced the leaf-level photosynthesis and growth of this formerly light-limited canopy stratum, compensating for upper canopy production losses and a reduction in total leaf area index (LAI). As a result, whole-ecosystem production efficiency (ANPPw/LAI) increased with rising disturbance severity, except in plots beyond the disturbance threshold. These findings provide a mechanistic explanation for a nonlinear relationship between ANPPw, and disturbance severity, in which the physiological and growth enhancement of undisturbed vegetation is proportional to the level of disturbance until a threshold is exceeded. Our results have important ecological and management implications, demonstrating that in some ecosystems moderate levels of disturbance minimally alter forest production. PMID:26594704

  4. PARCS: A Safety Net Community-Based Fitness Center for Low-Income Adults

    PubMed Central

    Keith, NiCole; de Groot, Mary; Mi, Deming; Alexander, Kisha; Kaiser, Stephanie

    2015-01-01

    Background Physical activity (PA) and fitness are critical to maintaining health and avoiding chronic disease. Limited access to fitness facilities in low-income urban areas has been identified as a contributor to low PA participation and poor fitness. Objectives This research describes community-based fitness centers established for adults living in low-income, urban communities and characterizes a sample of its members. Methods The community identified a need for physical fitness opportunities to improve residents’ health. Three community high schools were host sites. Resources were combined to renovate and staff facilities, acquire equipment, and refer patients to exercise. The study sample included 170 members ≥ age 18yr who completed demographic, exercise self-efficacy, and quality of life surveys and a fitness evaluation. Neighborhood-level U.S. Census data were obtained for comparison. Results The community-based fitness centers resulted from university, public school, and hospital partnerships offering safe, accessible, and affordable exercise opportunities. The study sample mean BMI was 35 ± 7.6 (Class II obesity), mean age was 50yr ± 12.5, 66% were black, 72% were female, 66% completed some college or greater, and 71% had an annual household income < $25K and supported 2.2 dependents. Participants had moderate confidence for exercise participation and low fitness levels. When compared to census data, participants were representative of their communities. Conclusion This observational study reveals a need for affordable fitness centers for low-income adults. We demonstrate a model where communities and organizations strategically leverage resources to address disparities in physical fitness and health. PMID:27346764

  5. Specific features of determination of the net production of nitrous oxide by soils

    NASA Astrophysics Data System (ADS)

    Ananyeva, N. D.; Ivashchenko, K. V.; Stolnikova, E. V.; Stepanov, A. L.; Kudeyarov, V. N.

    2015-06-01

    The rate of the net nitrous oxide (N2O) production, the content of microbial biomass carbon (Cmic), and its portion in the total soil organic carbon (Corg) were determined in the samples from podzol, soddy-podzolic soils, gray forest soils, chernozems, burozems, and carbolithozems of natural, arable, and fallow ecosystems in Kostroma, Vladimir, Moscow, Kaluga, Voronezh oblasts, and Krasnodar region. The most sustainable N2O production was found in the soils enriched with glucose or its mixture with ammonium sulfate at 22°C upon the preliminary incubation of the soil samples (7 days, 60% of water holding capacity). In the profiles of forest soils, a direct correlation was found between the N2O production and the Cmic content ( r = 0.74, p ≤ 0.05, n = 18). In the upper mineral layers (0-10 cm) of soddy-podzolic soils of the cropland, fallow, young, secondary and native forests, the inverse relationship between the N2O production and the Cmic content ( r = -0.75, p ≤ 0.05, n = 6) was observed. In a series of the fallowed, cultivated, and forest soils, the net N2O production decreased (239, 69, and 38 ng N2O-N × 10-3/g per h), and the Cmic content and Cmic: Corg ratio increased (181, 569, and 1020 μg C/g; 1.4, 2.6, and 3.0%, respectively) attesting to the increasing N2O flux in the anthropogenically transformed ecosystems. The application of cycloheximide (20-50 mg/g) to the soil lowered the N2O production by 69-99%, which pointed to a significant contribution of fungi to this process. An approach to separate nitrification and denitrification in the soil using low concentrations of acetylene (1.8 Pa) was proposed. The conditions of preparation of the soil samples for sustainable detection of N2O production were specified. It was shown that this process is tightly related to the soil microbial biomass and its fungal component.

  6. Famine Early Warning Systems Network (FEWS NET) Contributions to Strengthening Resilience and Sustainability for the East African Community

    NASA Astrophysics Data System (ADS)

    Budde, M. E.; Galu, G.; Funk, C. C.; Verdin, J. P.; Rowland, J.

    2014-12-01

    The Planning for Resilience in East Africa through Policy, Adaptation, Research, and Economic Development (PREPARED) is a multi-organizational project aimed at mainstreaming climate-resilient development planning and program implementation into the East African Community (EAC). The Famine Early Warning Systems Network (FEWS NET) has partnered with the PREPARED project to address three key development challenges for the EAC; 1) increasing resiliency to climate change, 2) managing trans-boundary freshwater biodiversity and conservation and 3) improving access to drinking water supply and sanitation services. USGS FEWS NET has been instrumental in the development of gridded climate data sets that are the fundamental building blocks for climate change adaptation studies in the region. Tools such as the Geospatial Climate Tool (GeoCLIM) have been developed to interpolate time-series grids of precipitation and temperature values from station observations and associated satellite imagery, elevation data, and other spatially continuous fields. The GeoCLIM tool also allows the identification of anomalies and assessments of both their frequency of occurrence and directional trends. A major effort has been put forth to build the capacities of local and regional institutions to use GeoCLIM to integrate their station data (which is not typically available to the public) into improved national and regional gridded climate data sets. In addition to the improvements and capacity building activities related to geospatial analysis tools, FEWS NET will assist in two other areas; 1) downscaling of climate change scenarios and 2) vulnerability impact assessments. FEWS NET will provide expertise in statistical downscaling of Global Climate Model output fields and work with regional institutions to assess results of other downscaling methods. Completion of a vulnerability impact assessment (VIA) involves the examination of sectoral consequences in identified climate "hot spots". FEWS NET

  7. Sensitivity of Spruce/Moss Boreal Forest Net Ecosystem Productivity to Seasonal Anomalies in Weather

    NASA Technical Reports Server (NTRS)

    Frolking, Steve

    1997-01-01

    Abstract. A process-oriented, daily time step model of a spruce/moss boreal ecosystem simulated 1994 and 1995 productivity for a Boreal Ecosystem-Atmosphere Study site near Thompson, Manitoba. Simulated black spruce net primary productivity (NPP) was 139 g C m(exp -2) in 1994 and 112 in 1995; feathermoss NPP was 13.0 g C m(exp -2) in 1994 and 9.7 in 1995; decomposition was 126 g C m(exp -2) in 1994 and 130 in 1995; net ecosystem productivity (NEP) was an uptake of 26.3 g C m(exp -2)in 1994 and 2.5 in 1995. A very dry period for the first half of the 1995 summer was the major cause of that year's lower productivity. Sensitivity simulations explored the impact of 2-month long warmer, cooler, wetter, and drier spells on ecosystem productivity. Warmer summers decreased spruce NPP, moss NPP, and NEP; cooler summers had the opposite effect. Earlier snowmelt (due to either warmer spring temperatures or reduced winter precipitation) increased moss and spruce NPP; later snowmelt had the opposite effect. The largest effect on decomposition was a 5% reduction due to a drier summer. One-month droughts (April through October) were also imposed on 1975 base year weather. Early summer droughts reduced moss annual NPP by -30-40%; summer droughts reduced spruce annual NPP by 10%; late summer droughts increased moss NPP by about 20% due to reduced respiration; May to September monthly droughts reduced heterotrophic respiration by about 10%. Variability in NEP was up to roughly +/- 35%. Finally, 1975 growing season precipitation was redistributed into frequent, small rainstorms and infrequent, large rainstorms. These changes had no effect on spruce NPP. Frequent rainstorms increased decomposition by a few percent, moss NPP by 50%, and NEP by 20%. Infrequent rainstorms decreased decomposition by 5%, moss NPP by 50% and NEP by 15%. The impact of anomalous weather patterns on productivity of this ecosystem depended on their timing during the year. Multiyear data sets are necessary to

  8. Net primary productivity of some aquatic macrophytes in sewage-sullage mixture.

    PubMed

    Kanungo, V K; Sinha, S; Naik, M L

    2001-07-01

    Sewage-sullage mixture from Raipur city is spread over a vast area surrounding the city. This mixture has a pH always above neutrality with high turbidity. Transparency was nil with the absence of phenolphthalein alkalinity and dissolved oxygen. Hardness was high with low nitrogen and phosphorus concentration. Human consumable. acquatic macrophytes are cultivated in such waste water. Net primary productivity of three macrophytes: Ipomoea aquatica, Marsilea quadrifolia and Nelumbo nucifera were evaluated while being cultivated in such sewage-sullage mixture. Productivity was determined either with periodic biomass removal (I. aquatica and M. quadrifolia) or through removing the biomass only once at the time of growing season (N. nucifera). Growing season productivity of up to 27.48. 19.81 and 9.49 g m(-2) and day(-1) and extrapolated productivity of up to 100.30, 72.31 and 34.64 mt. ha(-1) yr(-1) was recorded for I. aquatica. M. quadrifolia and N. nucifera respectively. Thus, these macrophytes are yielding a high amount of human consumable biomass from an area which neither be a useless wetland. PMID:12017265

  9. Community solar salt production in Goa, India

    PubMed Central

    2012-01-01

    Traditional salt farming in Goa, India has been practised for the past 1,500 years by a few communities. Goa’s riverine estuaries, easy access to sea water and favourable climatic conditions makes salt production attractive during summer. Salt produced through this natural evaporation process also played an important role in the economy of Goa even during the Portuguese rule as salt was the chief export commodity. In the past there were 36 villages involved in salt production, which is now reduced to 9. Low income, lack of skilled labour, competition from industrially produced salt, losses incurred on the yearly damage of embankments are the major reasons responsible for the reduction in the number of salt pans. Salt pans (Mithagar or Mithache agor) form a part of the reclaimed waterlogged khazan lands, which are also utilised for aquaculture, pisciculture and agriculture. Salt pans in Goa experience three phases namely, the ceased phase during monsoon period of June to October, preparatory phase from December to January, and salt harvesting phase, from February to June. After the monsoons, the salt pans are prepared manually for salt production. During high tide, an influx of sea water occurs, which enters the reservoir pans through sluice gates. The sea water after 1–2 days on attaining a salinity of approximately 5ºBé, is released into the evaporator pans and kept till it attains a salinity of 23 - 25ºBé. The brine is then released to crystallizer pans, where the salt crystallises out 25 - 27ºBé and is then harvested. Salt pans form a unique ecosystem where succession of different organisms with varying environmental conditions occurs. Organisms ranging from bacteria, archaea to fungi, algae, etc., are known to colonise salt pans and may influence the quality of salt produced. The aim of this review is to describe salt farming in Goa’s history, importance of salt production as a community activity, traditional method of salt production and the

  10. Community solar salt production in Goa, India.

    PubMed

    Mani, Kabilan; Salgaonkar, Bhakti B; Das, Deepthi; Bragança, Judith M

    2012-01-01

    Traditional salt farming in Goa, India has been practised for the past 1,500 years by a few communities. Goa's riverine estuaries, easy access to sea water and favourable climatic conditions makes salt production attractive during summer. Salt produced through this natural evaporation process also played an important role in the economy of Goa even during the Portuguese rule as salt was the chief export commodity. In the past there were 36 villages involved in salt production, which is now reduced to 9. Low income, lack of skilled labour, competition from industrially produced salt, losses incurred on the yearly damage of embankments are the major reasons responsible for the reduction in the number of salt pans.Salt pans (Mithagar or Mithache agor) form a part of the reclaimed waterlogged khazan lands, which are also utilised for aquaculture, pisciculture and agriculture. Salt pans in Goa experience three phases namely, the ceased phase during monsoon period of June to October, preparatory phase from December to January, and salt harvesting phase, from February to June. After the monsoons, the salt pans are prepared manually for salt production. During high tide, an influx of sea water occurs, which enters the reservoir pans through sluice gates. The sea water after 1-2 days on attaining a salinity of approximately 5ºBé, is released into the evaporator pans and kept till it attains a salinity of 23 - 25ºBé. The brine is then released to crystallizer pans, where the salt crystallises out 25 - 27ºBé and is then harvested.Salt pans form a unique ecosystem where succession of different organisms with varying environmental conditions occurs. Organisms ranging from bacteria, archaea to fungi, algae, etc., are known to colonise salt pans and may influence the quality of salt produced.The aim of this review is to describe salt farming in Goa's history, importance of salt production as a community activity, traditional method of salt production and the biota

  11. Above- and below-ground net primary productivity across ten Amazonian forests on contrasting soils

    NASA Astrophysics Data System (ADS)

    Aragão, L. E. O. C.; Malhi, Y.; Metcalfe, D. B.; Silva-Espejo, J. E.; Jiménez, E.; Navarrete, D.; Almeida, S.; Costa, A. C. L.; Salinas, N.; Phillips, O. L.; . Anderson, L. O.; Baker, T. R.; Goncalvez, P. H.; Huamán-Ovalle, J.; Mamani-Solórzano, M.; Meir, P.; Monteagudo, A.; Peñuela, M. C.; Prieto, A.; Quesada, C. A.; Rozas-Dávila, A.; Rudas, A.; Silva Junior, J. A.; Vásquez, R.

    2009-02-01

    The net primary productivity (NPP) of tropical forests is one of the most important and least quantified components of the global carbon cycle. Most relevant studies have focused particularly on the quantification of the above-ground coarse wood productivity, and little is known about the carbon fluxes involved in other elements of the NPP, the partitioning of total NPP between its above- and below-ground components and the main environmental drivers of these patterns. In this study we quantify the above- and below-ground NPP of ten Amazonian forests to address two questions: (1) How do Amazonian forests allocate productivity among its above- and below-ground components? (2) How do soil and leaf nutrient status and soil texture affect the productivity of Amazonian forests? Using a standardized methodology to measure the major elements of productivity, we show that NPP varies between 9.3±1.3 Mg C ha-1 yr-1 (mean±standard error), at a white sand plot, and 17.0±1.4 Mg C ha-1 yr-1 at a very fertile Terra Preta site, with an overall average of 12.8±0.9 Mg C ha-1 yr-1. The studied forests allocate on average 64±3% and 36±3% of the total NPP to the above- and below-ground components, respectively. The ratio of above-ground and below-ground NPP is almost invariant with total NPP. Litterfall and fine root production both increase with total NPP, while stem production shows no overall trend. Total NPP tends to increase with soil phosphorus and leaf nitrogen status. However, allocation of NPP to below-ground shows no relationship to soil fertility, but appears to decrease with the increase of soil clay content.

  12. Above- and below-ground net primary productivity across ten Amazonian forests on contrasting soils

    NASA Astrophysics Data System (ADS)

    Aragão, L. E. O. C.; Malhi, Y.; Metcalfe, D. B.; Silva-Espejo, J. E.; Jiménez, E.; Navarrete, D.; Almeida, S.; Costa, A. C. L.; Salinas, N.; Phillips, O. L.; Anderson, L. O.; Alvarez, E.; Baker, T. R.; Goncalvez, P. H.; Huamán-Ovalle, J.; Mamani-Solórzano, M.; Meir, P.; Monteagudo, A.; Patiño, S.; Peñuela, M. C.; Prieto, A.; Quesada, C. A.; Rozas-Dávila, A.; Rudas, A.; Silva, J. A., Jr.; Vásquez, R.

    2009-12-01

    The net primary productivity (NPP) of tropical forests is one of the most important and least quantified components of the global carbon cycle. Most relevant studies have focused particularly on the quantification of the above-ground coarse wood productivity, and little is known about the carbon fluxes involved in other elements of the NPP, the partitioning of total NPP between its above- and below-ground components and the main environmental drivers of these patterns. In this study we quantify the above- and below-ground NPP of ten Amazonian forests to address two questions: (1) How do Amazonian forests allocate productivity among its above- and below-ground components? (2) How do soil and leaf nutrient status and soil texture affect the productivity of Amazonian forests? Using a standardized methodology to measure the major elements of productivity, we show that NPP varies between 9.3±1.3 Mg C ha-1 yr-1 (mean±standard error), at a white sand plot, and 17.0±1.4 Mg C ha-1 yr-1 at a very fertile Terra Preta site, with an overall average of 12.8±0.9 Mg C ha-1 yr-1. The studied forests allocate on average 64±3% and 36±3% of the total NPP to the above- and below-ground components, respectively. The ratio of above-ground and below-ground NPP is almost invariant with total NPP. Litterfall and fine root production both increase with total NPP, while stem production shows no overall trend. Total NPP tends to increase with soil phosphorus and leaf nitrogen status. However, allocation of NPP to below-ground shows no relationship to soil fertility, but appears to decrease with the increase of soil clay content.

  13. Laser Spray Fabrication for Net-Shape Rapid Product Realization LDRD

    SciTech Connect

    Atwood, C.L.; Ensz, M.T.; Greene, D.L.; Griffith, M.L.; Harwell, L.D.; Jeantette, F.P.; Keicher, D.M.; Oliver, M.S.; Reckaway, D.E.; Romero, J.A.; Schlienger, M.E.; Smugeresky, J.D.

    1999-04-01

    The primary purpose of this LDRD project was to characterize the laser deposition process and determine the feasibility of fabricating complex near-net shapes directly from a CAD solid model. Process characterization provided direction in developing a system to fabricate complex shapes directly from a CAD solid model. Our goal for this LDRD was to develop a system that is robust and provides a significant advancement to existing technologies (e.g., polymeric-based rapid prototyping, laser welding). Development of the process will allow design engineers to produce functional models of their designs directly from CAD files. The turnaround time for complex geometrical shaped parts will be hours instead of days and days instead of months. With reduced turnaround time, more time can be spent on the product-design phase to ensure that the best component design is achieved. Maturation of this technology will revolutionize the way the world produces structural components.

  14. Large Uncertainties in Estimating Grassland Carbon Fluxes: Can Net Ecosystem Production Be Inferred?

    NASA Astrophysics Data System (ADS)

    Cahill, K. N.; Foley, J. A.; Kucharik, C. J.

    2003-12-01

    Despite interest in estimating ecosystem carbon budgets based on easily collected field data, no previous study to our knowledge has compared various methods of estimating total above- and belowground net primary production (NPP) and net ecosystem production (NEP, the annual carbon accumulated by an ecosystem) from commonly measured biomass and soil surface CO2 flux data in grasslands. Here we used field data from two grassland restorations and a row-crop agriculture treatment enrolled in the Conservation Reserve Program as a model for an analysis of methodological uncertainty in estimating ecosystem carbon budgets over a short time period. The goal of this study was to investigate how a range of methods for estimating NPP and NEP suggested in the literature might be used to predict ecosystem carbon budgets based on short-term field measurements. We conclude that it is extremely difficult to close the carbon budget of a temperate grassland using flux-based methods that account for plant-derived carbon inputs and soil surface CO2 losses. Current uncertainties in (1) estimating aboveground NPP, (2) determining belowground NPP, and (3) splitting soil respiration into heterotrophic and autotrophic components strongly affect the magnitude, and even the sign, of NEP. A comparison of these estimates, across a treatment of different plant species mixes and land management, cannot reliably distinguish differences in NEP, nor the absolute sign of the overall carbon budget. These uncertainties likely exist in all grassland carbon budget studies using this approach, so conclusions about whether these systems are truly carbon sinks, or how they should be managed to sequester carbon, must be made with extreme care. Longer-term stocks methods, periodically linked to flux-based measurements of individual processes, may be the only way to close the carbon budget in these systems with any reasonable degree of certainty at the present time.

  15. 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

  16. Comparing the impact of the 2003 and 2010 heatwaves on Net Ecosystem Production in Europe

    NASA Astrophysics Data System (ADS)

    Bastos, A. F.; Gouveia, C. M.; Trigo, R. M.

    2012-12-01

    Climate variability is known to influence primary productivity on land ecosystems (Nemani et al., 2003). In particular, extreme climatic events such as major droughts and heatwaves are known to have severe impact on primary productivity and, therefore, to affect significantly the carbon dioxide uptake by land ecosystems at regional (Ciais et al., 2005) or even global scale (Zhao and Running, 2010). In the last decade, Europe was struck by two outstanding heatwaves, the 2003 event in Western Europe and the recent 2010 episode over Eastern Europe. Both were characterised by record breaking temperatures at the daily, weekly, monthly and seasonal scales, although the amplitude and spatial extent of the 2010 mega-heatwave surpassed the 2003 event (Barriopedro et al., 2011). This work aims to assess the influence of both mega-heatwaves on seasonal and yearly Net Ecosystem Production (NEP). The work relies on monthly NEP data derived from satellite imagery obtained from MODIS (Moderate Resolution Imaging Spectroradiometer) sensor at 1km spatial resolution. Data were selected for the period between 2000 and 2011 over a region extending from 34.6 oN to 73.5 oN and 12.1 oW to 46.8 oE, covering Eurasia. In 2010 very low NEP anomalies are observed over a very large area in Eastern Europe, at the monthly, seasonal and yearly scale. In western Russia, yearly NEP anomalies fall below 50% of average cumulative NEP. These widespread negative anomalous values of NEP fields over the western Russia region match the patterns of very high temperature values combined with below-average precipitation, at the seasonal (summer) scale. Moreover, the impact of the heatwave is not only evident at the regional level but also at the wider continental (European) scale and is significantly more extensive and intense than the corresponding heatwave of 2003 in Western Europe (Ciais et al., 2005). References: Barriopedro, D., E. M. Fischer, J. Luterbacher, R. M. Trigo, and R. Garcia-Herrera (2011

  17. The effects of urbanization on net primary productivity in southeastern China.

    PubMed

    Lu, Dengsheng; Xu, Xiaofeng; Tian, Hanqin; Moran, Emilio; Zhao, Maosheng; Running, Steven

    2010-09-01

    Net primary productivity (NPP) is one of the major ecosystem products on which human societies rely heavily. However, rapid urban sprawl and its associated dense population and economic conditions have generated great pressure on natural resources, food security, and environments. It is valuable to understand how urban expansion and associated demographic and economic conditions affect ecosystem functions. This research conducted a case study in Southeastern China to examine the impacts of urban expansion and demographic and economic conditions on NPP. The data sources used in research include human settlement developed through a combination of MODIS, DMSP-OLS and Landsat ETM+ images, the annual NPP from MODIS, and the population and gross domestic product (GDP) from the 2000 census data. Multiple regression analysis and nonlinear regression analysis were used to examine the relationships of NPP with settlement, population and GDP. This research indicates that settlement, population and GDP have strongly negative correlation with NPP in Southeastern China, but the outcomes were nonlinear when population or GDP reached certain thresholds. PMID:20703877

  18. The Effects of Urbanization on Net Primary Productivity in Southeastern China

    NASA Astrophysics Data System (ADS)

    Lu, Dengsheng; Xu, Xiaofeng; Tian, Hanqin; Moran, Emilio; Zhao, Maosheng; Running, Steven

    2010-09-01

    Net primary productivity (NPP) is one of the major ecosystem products on which human societies rely heavily. However, rapid urban sprawl and its associated dense population and economic conditions have generated great pressure on natural resources, food security, and environments. It is valuable to understand how urban expansion and associated demographic and economic conditions affect ecosystem functions. This research conducted a case study in Southeastern China to examine the impacts of urban expansion and demographic and economic conditions on NPP. The data sources used in research include human settlement developed through a combination of MODIS, DMSP-OLS and Landsat ETM+ images, the annual NPP from MODIS, and the population and gross domestic product (GDP) from the 2000 census data. Multiple regression analysis and nonlinear regression analysis were used to examine the relationships of NPP with settlement, population and GDP. This research indicates that settlement, population and GDP have strongly negative correlation with NPP in Southeastern China, but the outcomes were nonlinear when population or GDP reached certain thresholds.

  19. Accountability and Productivity: Report for the Illinois Community College System.

    ERIC Educational Resources Information Center

    Illinois Community Coll. Board, Springfield.

    Within the Illinois Community College System (ICCS), each of the 50 member colleges reports to the Illinois Community College Board (ICCB) on their productivity improvements. This report summarizes the productivity reports of the ICCS colleges, examines the results of a series of analyses of productivity conducted by the ICCB from a statewide…

  20. Transformations, Inc. Net Zero Energy Communities, Devens, Easthampton, Townsend, Massachusetts (Fact Sheet)

    SciTech Connect

    Not Available

    2013-11-01

    In 2009, Transformations, Inc. partnered with U.S. Department of Energy (DOE) Building America team Building Science Corporation (BSC) to build new net zero energy houses in three developments in Massachusetts. The company has been developing strategies for cost-effective super-insulated homes in the New England market since 2006. After years of using various construction techniques, it has developed a specific set of assemblies and specifications that achieve a 44.9% reduction in energy use compared with a home built to the 2009 International Residential Code, qualifying the houses for the DOE's Challenge Home. The super-insulated houses provide data for several research topics in a cold climate. BSC studied the moisture risks in double stud walls insulated with open cell spray foam and cellulose. The mini-split air source heat pump (ASHP) research focused on the range of temperatures experienced in bedrooms as well as the homeowners' perceptions of equipment performance. BSC also examined the developer's financing options for the photovoltaic (PV) systems, which take advantage of Solar Renewable Energy Certificates, local incentives, and state and federal tax credits.

  1. New Whole-House Case Study: Transformations, Inc. Net Zero Energy Communities, Devens, Easthampton, Townsend, Massachusetts

    SciTech Connect

    2013-11-01

    In 2009, Transformations, Inc. partnered with Building America team Building Science Corporation (BSC) to build new net zero energy houses in three developments in Massachusetts. The company has been developing strategies for cost-effective super-insulated homes in the New England market since 2006. After years of using various construction techniques, it has developed a specific set of assemblies and specifications that achieve a 44.9% reduction in energy use compared with a home built to the 2009 International Residential Code, qualifying the houses for the DOE’s Challenge Home. The super-insulated houses provide data for several research topics in a cold climate. BSC studied the moisture risks in double stud walls insulated with open cell spray foam and cellulose. The mini-split air source heat pump (ASHP) research focused on the range of temperatures experienced in bedrooms as well as the homeowners’ perceptions of equipment performance. BSC also examined the developer’s financing options for the photovoltaic (PV) systems, which take advantage of Solar Renewable Energy Certificates, local incentives, and state and federal tax credits.

  2. The Central Logic Board for the KM3NeT detector: Design and production

    NASA Astrophysics Data System (ADS)

    Musico, P.

    2016-07-01

    The KM3NeT deep sea neutrino observatory will include a very large number of multi-Photomultiplier (PMT) optical modules (DOM) to detect the Cherenkov light generated by secondary particles produced in neutrino interactions. The Central Logic Board (CLB) has been developed to acquire timing and amplitude information from the PMT signals, implementing time-to-digital conversion (TDC) with time over threshold (TOT) technique. The board is also used to configure all the DOM subsystems, to assist in the DOM position and orientation, calibration and to monitor temperature and humidity in the DOM itself. All the collected data are transmitted to shore using a wide-bandwidth optical network. Moreover, through the optical network, all the DOMs are kept synchronized in time within 1 ns precision using the White Rabbit (WR) Precision Time Protocol (PTP) over an Ethernet connection. A large Field Programmable Gate Array (FPGA) has been adopted to implement all the specifications witht the requested performances. The CLB will be also used in the base container of the detection unit (DU) to set-up and monitor all the requested functionalities: in this scenario a dedicated firmware and software will be deployed on board. The design has been started in early 2013 and several prototypes have been developed. After deep test carried on in different EU laboratories, the final mass production batch of 600 boards has been ordered and built: all the CLB are now ready for integration in the DOMs and base containers. The first two KM3NeT DU will be deployed in summer 2015 and all other units are in advanced stage of integration.

  3. Flood effects on efflux and net production of nitrous oxide in river floodplain soils

    NASA Astrophysics Data System (ADS)

    Riaz, Muhammad; Bruderer, Christian; Niklaus, Pascal A.; Luster, Jörg

    2016-04-01

    Floodplain soils are often rich in nutrients and exhibit high spatial heterogeneity in terms of geomorphology, soil environmental conditions and substrate availability for processes involved in carbon and nutrient cycling. In addition, fluctuating water tables lead to temporally changing redox conditions. In such systems, there are ideal conditions for the occurrence of hot spots and moments of nitrous oxide emissions, a potent greenhouse gas. The factors that govern the spatial heterogeneity and dynamics of N2O formation in floodplain soils and the surface efflux of this gas are not fully understood. A particular issue is the contribution of N2O formation in the subsoil to surface efflux. We studied this question in the floodplain of a restored section of the Thur river (NE Switzerland) which is characterized by a flashy flow regime. As a consequence, the floodplain soils are unsaturated most of the time. We showed earlier that saturation during flood pulses leads to short phases of generally anoxic conditions followed by a drying phase with anoxic conditions within aggregates and oxic conditions in larger soil pores. The latter conditions are conducive for spatially closely-coupled nitrification-denitrification and related hot moments of nitrous oxide formation. In a floodplain zone characterized by about one meter of young, sandy sediments, that are mostly covered by the tall grass Phalaris arundinacea, we measured at several time points before and after a small flood event N2O surface efflux with the closed-chamber method, and assessed N2O concentrations in the soil air at four different depths using gas-permeable tubings. In addition, we calculated the N2O diffusivity in the soil from Radon diffusivity. The latter was estimated in-situ from the recovery of Radon concentration in the gas-permeable tubings after purging with ambient air. All these data were then used to calculate net N2O production rates at different soil depths with the gradient method. In

  4. Petri Net Modeling and Decomposition Method for Solving Production Scheduling Problems

    NASA Astrophysics Data System (ADS)

    Nishi, Tatsushi; Maeno, Ryota

    Considering the need to develop general scheduling problem solver, the recent integration of Petri Nets as modeling tools into effective optimization methods for scheduling problems is very promising. The paper addresses a Petri Net modeling and decomposition method for solving a wide variety of scheduling problems. The scheduling problems are represented as the optimal transition firing sequence problems for timed Petri Nets. The Petri Net is decomposed into several subnets in which each subproblem can be easily solved by Dijkstra' algorithm. The approach is applied to a flowshop scheduling problem. The performance of the proposed algorithm is compared with that of a simulated annealing method.

  5. Climatic controls on aboveground net primary production of tropical lowland rainforests

    NASA Astrophysics Data System (ADS)

    Hofhansl, F.; Drage, S.; Poelz, E.; Richter, A.; Wanek, W.

    2012-12-01

    Aboveground net primary production (ANPP) of tropical forests is driven by soil fertility and climate, the latter receiving special attention as recent projections of global circulation models predict Mesoamerican tropics to become drier and warmer. Given the scarcity of manipulative experiments, interannual climate variations caused by El Nino Southern Oscillation have been used to assess the potential responses of tropical ANPP to projected climate change. The focus of this study was (1) to investigate how seasonal and interannual climate variations affect ANPP and the partitioning between litterfall and stem increment on three forest sites differing in soil fertility and disturbance regime in SW Costa Rica, and (2) to identify major drivers of tropical forest ANPP by integrating our results into a dataset provided by the National Center for Ecological Analysis and Synthesis (NCEAS). While forest productivity was reported to decline in areas with high precipitation and temperature, we measured among the highest stem increments and litterfall rates published to date at a site with >6000 mm mean annual precipitation (MAP) and a mean annual temperature (MAT) of 28 °C. Based on the full dataset MAP was inversely correlated with litterfall, while MAT and soil fertility promoted stem increment. Therefore the percentage of litterfall and stem increment to ANPP shifted from 80:20 in low productive tropical forests to 40:60 at forest sites with high biomass production. Our results suggest that there is a shift in the allocation of biomass towards greater nutrient conservation (i.e. production of wood biomass) in more productive tropical forests while litterfall is sustaining nutrient recycling processes in less productive forests and that this relationship is driven by climate. We finally demonstrate that both ANPP components are sensitive to seasonal and interannual climate variation at the three forest sites studied, but that the controls differ for litterfall and stem

  6. Coherence between woody carbon uptake and net ecosystem productivity at five eddy-covariance sites

    NASA Astrophysics Data System (ADS)

    Babst, F.; Bouriaud, O.; Papale, D.; Gielen, B.; Janssens, I.; Nikinmaa, E.; Ibrom, A.; Wu, J.; Bernhofer, C.; Koestner, B.; Gruenwald, T.; Seufert, G.; Ciais, P.; Frank, D. C.

    2013-12-01

    Forest growth ranks amongst the most important processes that determine the carbon balance of terrestrial ecosystems. Quantifications of forest carbon cycling can be made e.g. using biometric and eddy-covariance (EC) techniques. Both offer different perspectives on carbon uptake and attempts to combine them have been inconsistent and variably successful in the past. This contributes to persistent uncertainties regarding carbon allocation in forest ecosystems and complicates precise vegetation model parameterization. Aiming to reconcile assessments of carbon cycling from biometric and EC techniques, we measured radial tree growth and wood density at five long-term EC stations across Europe. The resulting records were used to calculate annual carbon uptake during above-ground wood formation and compared to monthly and seasonal CO2-flux measurements. Efforts were made to identify i) the time periods when EC and tree-ring data correspond best in different parts of Europe and ii) the fraction of eddy-fluxes which is associated with changes in above-ground woody carbon stocks. Biometric measurements and net ecosystem productivity (NEP) proved largely compatible at seasonal time scales while relationships with gross primary productivity (GPP) were often weaker. Results suggest a partitioning of sequestered carbon mainly used for volume increase (January-June) and a combination of cell-wall thickening and storage (July-September). The inter-annual variability in above-ground woody carbon uptake was significantly linked with absolute productivity ranging between 69-366 g C m-2 y-1 at boreal and temperate sites, thereby accounting for 10-25% of GPP, 15-32% of TER, and 25-80% of NEP. These findings from sites representing the major European climate zones and tree species contribute to improved quantification of above-ground carbon allocation in forests. Furthermore, they refine knowledge on processes driving ecosystem productivity important for e.g. vegetation models and

  7. Aboveground Net Primary Productivity in a Riparian Wetland Following Restoration of Hydrology

    PubMed Central

    Koontz, Melissa; Lundberg, Christopher; Lane, Robert; Day, John; Pezeshki, Reza

    2016-01-01

    This research presents the initial results of the effects of hydrological restoration on forested wetlands in the Mississippi alluvial plain near Memphis, Tennessee. Measurements were carried out in a secondary channel, the Loosahatchie Chute, in which rock dikes were constructed in the 1960s to keep most flow in the main navigation channel. In 2008–2009, the dikes were notched to allow more flow into the secondary channel. Study sites were established based on relative distance downstream of the notched dikes. Additionally, a reference site was established north of the Loosahatchie Chute where the dikes remained unnotched. We compared various components of vegetation composition and productivity at sites in the riparian wetlands for two years. Salix nigra had the highest Importance Value at every site. Species with minor Importance Values were Celtis laevigata, Acer rubrum, and Plantanus occidentalis. Productivity increased more following the introduction of river water in affected sites compared to the reference. Aboveground net primary productivity was highest at the reference site (2926 ± 458.1 g·m−2·year−1), the intact site; however, there were greater increase at the sites in the Loosahatchie Chute, where measurements ranged from 1197.7 ± 160.0 g m−2·year−1·to 2874.2 ± 794.0 g·m−2·year−1. The site furthest from the notching was the most affected. Pulsed inputs into these wetlands may enhance forested wetland productivity. Continued monitoring will quantify impacts of restored channel hydrology along the Mississippi River. PMID:26861409

  8. Aboveground Net Primary Productivity in a Riparian Wetland Following Restoration of Hydrology.

    PubMed

    Koontz, Melissa; Lundberg, Christopher; Lane, Robert; Day, John; Pezeshki, Reza

    2016-01-01

    This research presents the initial results of the effects of hydrological restoration on forested wetlands in the Mississippi alluvial plain near Memphis, Tennessee. Measurements were carried out in a secondary channel, the Loosahatchie Chute, in which rock dikes were constructed in the 1960s to keep most flow in the main navigation channel. In 2008-2009, the dikes were notched to allow more flow into the secondary channel. Study sites were established based on relative distance downstream of the notched dikes. Additionally, a reference site was established north of the Loosahatchie Chute where the dikes remained unnotched. We compared various components of vegetation composition and productivity at sites in the riparian wetlands for two years. Salix nigra had the highest Importance Value at every site. Species with minor Importance Values were Celtis laevigata, Acer rubrum, and Plantanus occidentalis. Productivity increased more following the introduction of river water in affected sites compared to the reference. Aboveground net primary productivity was highest at the reference site (2926 ± 458.1 g·m(-2)·year(-1)), the intact site; however, there were greater increase at the sites in the Loosahatchie Chute, where measurements ranged from 1197.7 ± 160.0 g m(-2)·year(-1)·to 2874.2 ± 794.0 g·m(-2)·year(-1). The site furthest from the notching was the most affected. Pulsed inputs into these wetlands may enhance forested wetland productivity. Continued monitoring will quantify impacts of restored channel hydrology along the Mississippi River. PMID:26861409

  9. Climatic and oceanic forcing of new, net, and diatom production in the North Water

    NASA Astrophysics Data System (ADS)

    Tremblay, Jean-Eric; Gratton, Yves; Fauchot, Juliette; Price, Neil M.

    New, net, and diatom production in the North Water were estimated during May to July 1998 from in vitro measurements of nitrate uptake and mesoscale temporal changes in the inventories of nitrate, silicate, oxygen, and inorganic carbon (DIC). Sampling stations were divided into two domains according to the position of the dominant water types: the silicate-rich Arctic water (SRAW) and Baffin Bay Water (BBW). BBW dominated in the southeast and was associated with relatively shallow upper mixed layers (UMLs) and weak horizontal advection. A phytoplankton bloom started in late April in BBW and grew slowly over 7 weeks, during which time the build-up of particulate organic nitrogen and carbon accounted for ca. 80% of the nitrate and DIC deficit, respectively. Over half of the new production (1.37 g C m -2 d -1) during this period was attributed to wind-driven replenishment of nitrate in the euphotic zone. The bloom culminated when seasonally declining winds and rising temperatures severed the UML from the deep nutrient reservoir. The same change in weather induced ice melt, stratification, and bloom development in northern SRAW, which had previously been characterized by deep UMLs. Collectively, the results imply that the timing and magnitude of blooms in the North Water are controlled by a succession of oceanic and climatic forcings. New C production in the North Water during April to July (1.11 g C m -2 d -1) was an order of magnitude higher than in adjacent waters and up to 8 times higher than in the Northeast Water polynya. As much as 80% of this production was mediated by diatoms >5 μm, suggesting potentially high and efficient C transfer to the herbivorous food web and deep waters.

  10. Spatio-temporal distribution of net-collected phytoplankton community and its response to marine exploitation in Xiangshan Bay

    NASA Astrophysics Data System (ADS)

    Jiang, Zhibing; Zhu, Xuyu; Gao, Yu; Chen, Quanzhen; Zeng, Jiangning; Zhu, Genhai

    2013-07-01

    To explore the spatial-temporal distribution of the phytoplankton community and evaluate the combined effects of marine resource exploitation, net-collected phytoplankton and physical-chemical parameters were investigated in the Xiangshan Bay during the four seasons of 2010. A total of eight phyla, 97 genera, and 310 species were found, including 232 diatom species, 45 dinoflagellate species and 33 other taxa. The phytoplankton abundances presented a significant ( P<0.001) seasonal difference with the average of 60.66×104 cells/m3. Diatoms (mainly consisting of Coscinodiscus jonesianus, Cerataulina pelagica, Skeleto n ema costatum, and genus Chaetoceros) dominated the phytoplankton assemblage in all seasons. We found great spatio-temporal variation in community composition based on the multidimensional scaling and similarity analysis. Canonical correspondence analysis show that temperature, nutrition, illumination, and salinity were the main variables associated with microalgal assemblage. Compared with the previous studies, an increase in phytoplankton abundance and change in the dominant species coincided with increased exploitation activities in this bay (e.g. operation of coastal power plants, intensive mariculture, tidal flat reclamation, and industrial and agricultural development). The present findings suggest that the government should exercise caution when deciding upon developmental patterns in the sea-related economy.

  11. Importance of Past Human and Natural Disturbance in Present-Day Net Ecosystem Productivity

    NASA Astrophysics Data System (ADS)

    Felzer, B. S.; Phelps, P.

    2014-12-01

    Gridded datasets of Net Ecosystem Exchange derived from eddy covariance and remote sensing measurements provide a means of validating Net Ecosystem Productivity (NEP, opposite of NEE) from terrestrial ecosystem models. While most forested regions in the U.S. are observed to be moderate to strong carbon sinks, models not including human or natural disturbances will tend to be more carbon neutral, which is expected of mature ecosystems. We have developed the Terrestrial Ecosystems Model Hydro version (TEM-Hydro) to include both human and natural disturbances to compare against gridded NEP datasets. Human disturbances are based on the Hurtt et al. (2006) land use transition dataset and include transient agricultural (crops and pasture) conversion and abandonment and timber harvest. We include natural disturbances of storms and fires based on stochastic return intervals. Tropical storms and hurricane return intervals are based on Zheng et al. (2009) and occur only along the U.S. Atlantic and Gulf coasts. Fire return intervals are based on LANDFIRE Rapid Assessment Vegetation Models and vegetation types from the Hurtt dataset. We are running three experiments with TEM-Hydro from 1700-2011 for the conterminous U.S.: potential vegetation (POT), human disturbance only (agriculture and timber harvest, LULC), and human plus natural disturbance (agriculture, timber harvest, storms, and fire, DISTURB). The goal is to compare our NEP values to those obtained by FLUXNET-MTE (Jung et al. 2009) from 1982-2008 and ECMOD (Xiao et al., 2008) from 2000-2006 for different plant functional types (PFTs) within the conterminous U.S. Preliminary results show that, for the entire U.S., potential vegetation yields an NEP of 10.8 gCm-2yr-1 vs 128.1 gCm-2yr-1 for LULC and 89.8 gCm-2yr-1 for DISTURB from 1982-2008. The effect of regrowth following agricultural and timber harvest disturbance therefore contributes substantially to the present-day carbon sink, while stochastic storms and fires

  12. Community-level net spillover of natural enemies from managed to natural forest

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Edge effects in fragmented natural habitats may be exacerbated by intensive land-use in the surrounding landscape. Given that most managed systems have higher productivity than adjacent natural systems, theory suggests that subsidised consumers are likely to spill over from managed to natural habita...

  13. Spatial heterogeneity in aboveground net primary production and species richness at multiple scales in the Chihuahuan Desert

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We analyzed patterns in spatial heterogeneity and the processes driving these patterns in two ecosystem properties, aboveground net primary production (ANPP) and species richness, at multiple scales in the Chihuahuan Desert. We used long-term data (1990-2009) to examine the importance of a suite of...

  14. Scepticism towards insecticide treated mosquito nets for malaria control in rural community in north-western Tanzania.

    PubMed

    Nnko, Soori E; Whyte, Susan R; Geissler, Wenzel P; Aagaard-Hansen, Jens

    2012-04-01

    Despite existence of effective tools for malaria control, malaria continues to be one of the leading killer diseases especially among under-five year children and pregnant women in poor rural populations of Sub Saharan Africa. In Tanzania Mainland the disease contributes to 39.4% of the total OPD attendances. In terms of mortality, malaria is known to be responsible for more than one third of deaths among children of age below 5 years and also contributes for up to one fifth of deaths among pregnant women. This paper is based on a study conducted in a rural community along the shores of Lake Victoria in Mwanza region, North-Western Tanzania. The study explores reasons for scepticism and low uptake of insecticide treated mosquito nets (ITNs) that were promoted through social marketing strategy for malaria control prior to the introduction of long lasting nets (LLN). The paper breaks from traditional approach that tend to study low uptake of health interventions in terms of structural practical constraints--cost, accessibility, everyday priorities--or in terms of cognition--insufficient knowledge of benefits e.g. ignorance of public health messages. This paper has shown that, the majority of people who could afford the prices of ITNs and who knew where to obtain the insecticides did not necessarily buy them. This suggests that, although people tend to report cost-related factors as a barrier against the use of ITNs, there are other critical concerns at work. Without underestimating the practical factors, our study have recommended to consider critical examinations of those other concerns that hinder optimal utilization of ITN for malaria control, and the basis for those concerns. PMID:26591730

  15. Linking aboveground net primary productivity to soil carbon and dissolved organic carbon in complex terrain

    NASA Astrophysics Data System (ADS)

    Peterson, Fox S.; Lajtha, Kate J.

    2013-07-01

    Factors influencing soil organic matter (SOM) stabilization and dissolved organic carbon (DOC) content in complex terrain, where vegetation, climate, and topography vary over the scale of a few meters, are not well understood. We examined the spatial correlations of lidar and geographic information system-derived landscape topography, empirically measured soil characteristics, and current and historical vegetation composition and structure versus SOM fractions and DOC pools and leaching on a small catchment (WS1) in the H.J. Andrews Experimental Forest, located in the western Cascades Range of Oregon, USA. We predicted that aboveground net primary productivity (ANPP), litter fall, and nitrogen mineralization would be positively correlated with SOM, DOC, and carbon (C) content of the soil based on the principle that increased C inputs cause C stores in and losses from in the soil. We expected that in tandem, certain microtopographical and microclimatic characteristics might be associated with elevated C inputs and correspondingly, soil C stores and losses. We confirmed that on this site, positive relationships exist between ANPP, C inputs (litter fall), and losses (exportable DOC), but we did not find that these relationships between ANPP, inputs, and exports were translated to SOM stores (mg C/g soil), C content of the soil (% C/g soil), or DOC pools (determined with salt and water extractions). We suggest that the biogeochemical processes controlling C storage and lability in soil may relate to longer-term variability in aboveground inputs that result from a heterogeneous and evolving forest stand.

  16. Estimating Green Net National Product for Puerto Rico: An Economic Measure of Sustainability

    NASA Astrophysics Data System (ADS)

    Wu, Shanshan; Heberling, Matthew T.

    2016-04-01

    This paper presents the data sources and methodology used to estimate Green Net National Product (GNNP), an economic metric of sustainability, for Puerto Rico. Using the change in GNNP as a one-sided test of weak sustainability (i.e., positive growth in GNNP is not enough to show the economy is sustainable), we measure the movement away from sustainability by examining the change in GNNP from 1993 to 2009. In order to calculate GNNP, we require both economic and natural capital data, but limited data for Puerto Rico require a number of simplifying assumptions. Based on the environmental challenges faced by Puerto Rico, we include damages from air emissions and solid waste, the storm protection value of mangroves and the value of extracting crushed stone as components in the depreciation of natural capital. Our estimate of GNNP also includes the value of time, which captures the effects of technological progress. The results show that GNNP had an increasing trend over the 17 years studied with two periods of negative growth (2004-2006 and 2007-2008). Our additional analysis suggests that the negative growth in 2004-2006 was possibly due to a temporary economic downturn. However, the negative growth in 2007-2008 was likely from the decline in the value of time, suggesting the island of Puerto Rico was moving away from sustainability during this time.

  17. Responses of Terrestrial Ecosystems’ Net Primary Productivity to Future Regional Climate Change in China

    PubMed Central

    Zhao, Dongsheng; Wu, Shaohong; Yin, Yunhe

    2013-01-01

    The impact of regional climate change on net primary productivity (NPP) is an important aspect in the study of ecosystems’ response to global climate change. China’s ecosystems are very sensitive to climate change owing to the influence of the East Asian monsoon. The Lund–Potsdam–Jena Dynamic Global Vegetation Model for China (LPJ-CN), a global dynamical vegetation model developed for China’s terrestrial ecosystems, was applied in this study to simulate the NPP changes affected by future climate change. As the LPJ-CN model is based on natural vegetation, the simulation in this study did not consider the influence of anthropogenic activities. Results suggest that future climate change would have adverse effects on natural ecosystems, with NPP tending to decrease in eastern China, particularly in the temperate and warm temperate regions. NPP would increase in western China, with a concentration in the Tibetan Plateau and the northwest arid regions. The increasing trend in NPP in western China and the decreasing trend in eastern China would be further enhanced by the warming climate. The spatial distribution of NPP, which declines from the southeast coast to the northwest inland, would have minimal variation under scenarios of climate change. PMID:23593325

  18. [Sensitivity of parameters in net primary productivity model of broadleaf-Korean pine mixed forest].

    PubMed

    Zhou, Chun-Hua; Hao, Zhan-Qing; He, Hong-Shi; Zhou, Dan-Hui

    2008-05-01

    PnET-II (photosynthesis and evapotranspiration) model is an ecosystem process model, which requires extensive input parameters, including vegetation parameters, soil parameters and climate parameters, to simulate net primary productivity (NPP). This study estimated the total and wood (stem and branch) NPPs of Korean pine and broadleaf species in Fenglin Natural Reserve, and examined the responses of the NPPs to the variations of the input parameters in PnET-II model. The simulation results indicated that among the vegetation parameters in PnET-II model, the variation of canopy parameters, had greater effects on the simulated NPPs of Korean pine and broadleaf species, and the response of Korean pine's total NPP to vegetation parameters was larger than that of broadleaf species'. The variation of soil water holding capacity (WHC) had smaller effects on the NPPs of Korean pine and broadleaf species, and the response of Korean pine's NPP to the WHC was somewhat smaller than that of broadleaf trees'. In climate scenarios, the variation of air temperature had the greatest effects on the simulated NPP of Korean pine and broadleaf trees, followed by precipitation and radiation. Different climate scenarios had different effects on the predicted results. The total and wood NPPs of Korean pine and broadleaf trees had different responses to the input parameters. PMID:18655573

  19. Forecasting global urban expansion and its effect on terrestrial net primary productivity

    NASA Astrophysics Data System (ADS)

    Li, Xuecao; Yu, Le; Liu, Xiaoping; Gong, Peng

    2016-04-01

    Net primary productivity (NPP) is of great importance to global terrestrial carbon cycle and global climate change. Although many relevant studies have been carried out, attempts on its consequence caused by urban expansion are still limited. In this study, we quantified the NPP loss after urbanization by 2100, through linking a global land use/cover dynamic (GLCD) model and a neighborhood proxy method. Finer resolution (30m) global land cover map as well as detailed land demand dataset (half degree) were adopted for urban growth modeling and NPP quantification. Our results indicate that (1) by 2100, the global urban area will reach 125.15×104 km2, with a growth rate of 2,892 km2/year; (2) the NPP loss due to urbanization during period of 2010-2100 is 9×10^(-3) PgC, which accounts more than 3% of the total urban NPP in 2010. In addition, by the end of this century, most urbanized land is estimated to happen in developing countries, e.g. China and India. Overall, global urban expansion results a neglect impact to NPP. Therefore, more attentions should be paid to cope with urban development in future, such as urban planning or managements.

  20. Dynamic changes in terrestrial net primary production and their effects on evapotranspiration

    NASA Astrophysics Data System (ADS)

    Li, Zhi; Chen, Yaning; Wang, Yang; Fang, Gonghuan

    2016-06-01

    The dramatic increase of global temperature since the year 2000 has a considerable impact on the global water cycle and vegetation dynamics. Little has been done about recent feedback of vegetation to climate in different parts of the world, and land evapotranspiration (ET) is the means of this feedback. Here we used the global 1 km MODIS net primary production (NPP) and ET data sets (2000-2014) to investigate their temporospatial changes under the context of global warming. The results showed that global NPP slightly increased in 2000-2014 at a rate of 0.06 PgC yr-2. More than 64 % of vegetated land in the Northern Hemisphere (NH) showed increased NPP (at a rate of 0.13 PgC yr-2), while 60.3 % of vegetated land in the Southern Hemisphere (SH) showed a decreasing trend (at a rate of -0.18 PgC yr-2). Vegetation greening and climate change promote rises of global ET. Specially, the increased rate of land ET in the NH (0.61 mm yr-2) is faster than that in the SH (0.41 mm yr-2). Over the same period, global warming and vegetation greening accelerate evaporation in soil moisture, thus reducing the amount of soil water storage. Continuation of these trends will likely exacerbate regional drought-induced disturbances and point to an increased risk of ecological drought, especially during regional dry climate phases.

  1. Nitrogen limitation of net primary productivity in terrestrial ecosystems is globally distributed.

    PubMed

    LeBauer, David S; Treseder, Kathleen K

    2008-02-01

    Our meta-analysis of 126 nitrogen addition experiments evaluated nitrogen (N) limitation of net primary production (NPP) in terrestrial ecosystems. We tested the hypothesis that N limitation is widespread among biomes and influenced by geography and climate. We used the response ratio (R approximately equal ANPP(N)/ANPP(ctrl)) of aboveground plant growth in fertilized to control plots and found that most ecosystems are nitrogen limited with an average 29% growth response to nitrogen (i.e., R = 1.29). The response ratio was significant within temperate forests (R = 1.19), tropical forests (R = 1.60), temperate grasslands (R = 1.53), tropical grasslands (R = 1.26), wetlands (R = 1.16), and tundra (R = 1.35), but not deserts. Eight tropical forest studies had been conducted on very young volcanic soils in Hawaii, and this subgroup was strongly N limited (R = 2.13), which resulted in a negative correlation between forest R and latitude. The degree of N limitation in the remainder of the tropical forest studies (R = 1.20) was comparable to that of temperate forests, and when the young Hawaiian subgroup was excluded, forest R did not vary with latitude. Grassland response increased with latitude, but was independent of temperature and precipitation. These results suggest that the global N and C cycles interact strongly and that geography can mediate ecosystem response to N within certain biome types. PMID:18409427

  2. Remote sensing of aboveground biomass and annual net aerial primary productivity in tidal wetlands

    SciTech Connect

    Hardisky, M.A.

    1983-01-01

    A technique was investigated for estimating biomass and net aerial primary productivity (NAPP) in Delaware tidal marshes from spectral data, describing marsh vegetation canopies. Spectral radiance data were collected with hand-held radiometers from the ground and from low altitude aircraft. Spectral wavebands corresponding to Landsat 4 thematic mapper bands 3, 4 and 5 and multispectral scanner bands 5 and 7 were employed. Spectral data, expressed as index values, were substituted into simple regression models to nondestructively compute total aboveground biomass. Dead biomass, salt crystals on plant leaves and soil background reflectance, all attenuated the spectral radiance index values. A large spectral contribution from any one of these canopy components caused an underestimate of live biomass. Biomass and annual NAPP of a S. alterniflora dominated salt marsh was estimated by traditional harvesting techniques and from ground-gathered spectral radiance data. The live and dead standing crop biomass estimates computed from spectral data were usually not significantly different from harvest biomass estimates. Spectral estimates of NAPP were usually within 10% of NAPP estimates calculated from harvest data. August live standing crop biomass estimates computed from ground-gathered spectral data for a tidal brackish marsh were generally within 10% of harvest estimates. Live biomass estimates computed from spectral data gathered from a low altitude aircraft were equally similar to harvest biomass estimates. The remote sensing technique holds much promise for rapid and accurate estimates of biomass and NAPP in tidal marshes.

  3. Estimating Green Net National Product for Puerto Rico: An Economic Measure of Sustainability.

    PubMed

    Wu, Shanshan; Heberling, Matthew T

    2016-04-01

    This paper presents the data sources and methodology used to estimate Green Net National Product (GNNP), an economic metric of sustainability, for Puerto Rico. Using the change in GNNP as a one-sided test of weak sustainability (i.e., positive growth in GNNP is not enough to show the economy is sustainable), we measure the movement away from sustainability by examining the change in GNNP from 1993 to 2009. In order to calculate GNNP, we require both economic and natural capital data, but limited data for Puerto Rico require a number of simplifying assumptions. Based on the environmental challenges faced by Puerto Rico, we include damages from air emissions and solid waste, the storm protection value of mangroves and the value of extracting crushed stone as components in the depreciation of natural capital. Our estimate of GNNP also includes the value of time, which captures the effects of technological progress. The results show that GNNP had an increasing trend over the 17 years studied with two periods of negative growth (2004-2006 and 2007-2008). Our additional analysis suggests that the negative growth in 2004-2006 was possibly due to a temporary economic downturn. However, the negative growth in 2007-2008 was likely from the decline in the value of time, suggesting the island of Puerto Rico was moving away from sustainability during this time. PMID:26721472

  4. [Variation trends of natural vegetation net primary productivity in China under climate change scenario].

    PubMed

    Zhao, Dong-sheng; Wu, Shao-hong; Yin, Yun-he

    2011-04-01

    Based on the widely used Lund-Potsdam-Jena Dynamic Global Vegetation Model (LPJ) for climate change study, and according to the features of natural environment in China, the operation mechanism of the model was adjusted, and the parameters were modified. With the modified LPJ model and taking 1961-1990 as baseline period, the responses of natural vegetation net primary productivity (NPP) in China to climate change in 1991-2080 were simulated under the Special Report on Emissions Scenarios (SRES) B2 scenario. In 1961-1990, the total NPP of natural vegetation in China was about 3.06 Pg C a(-1); in 1961-2080, the total NPP showed a fluctuant decreasing trend, with an accelerated decreasing rate. Under the condition of slight precipitation change, the increase of mean air temperature would have definite adverse impact on the NPP. Spatially, the NPP decreased from southeast coast to northwest inland, and this pattern would have less variation under climate change. In eastern China with higher NPP, especially in Northeast China, east of North China, and Loess Plateau, the NPP would mainly have a decreasing trend; while in western China with lower NPP, especially in the Tibetan Plateau and Tarim Basin, the NPP would be increased. With the intensive climate change, such a variation trend of NPP would be more obvious. PMID:21774310

  5. Interannual variation in climate-potential net primary productivity relationships in differing ecosystems of California

    SciTech Connect

    Koch, G.W.; Randerson, J.T. )

    1994-06-01

    The seasonality and interannual variation in potential net primary production (NPP) were examined in differing vegetation types in California over three years of contrasting precipitation using co-registered maps of climate, vegetation, and 1km biweekly NDVI derived from high resolution satellite AVHRR data. Differences in seasonality of the vegetation types (annual grassland, chamise chaparral, deciduous oak woodland, and evergreen oak) were clearly evident and corresponded well to patterns observed in field studies. In years and locations having high precipitation the annual peak in NDVI occurred later in all vegetation classes. The annual sum of biweekly NDVI was correlated with annual precipitation in all vegetation types, although the slopes and intercepts of the regressions differed among types. Annual grassland showed the largest increase in sumNDVI per unit increase in total precipitation and most of the variation in grassland sumNDVI was explained by variation in autumn precipitation. In general the ratio of sumNDVI to annual precipitation was dependent on the temporal distribution of precipitation with respect to the long-term average pattern. Published relationships between precipitation and NPP were used to develop equations relating annual NDVI sum to NPP.

  6. Energy intensity ratios as net energy measures of United States energy production and expenditures

    NASA Astrophysics Data System (ADS)

    King, C. W.

    2010-10-01

    In this letter I compare two measures of energy quality, energy return on energy invested (EROI) and energy intensity ratio (EIR) for the fossil fuel consumption and production of the United States. All other characteristics being equal, a fuel or energy system with a higher EROI or EIR is of better quality because more energy is provided to society. I define and calculate the EIR for oil, natural gas, coal, and electricity as measures of the energy intensity (units of energy divided by money) of the energy resource relative to the energy intensity of the overall economy. EIR measures based upon various unit prices for energy (e.g. /Btu of a barrel of oil) as well as total expenditures on energy supplies (e.g. total dollars spent on petroleum) indicate net energy at different points in the supply chain of the overall energy system. The results indicate that EIR is an easily calculated and effective proxy for EROI for US oil, gas, coal, and electricity. The EIR correlates well with previous EROI calculations, but adds additional information on energy resource quality within the supply chain. Furthermore, the EIR and EROI of oil and gas as well as coal were all in decline for two time periods within the last 40 years, and both time periods preceded economic recessions.

  7. A direct test of nitrogen and phosphorus limitation to net primary productivity in a lowland tropical wet forest.

    PubMed

    Alvarez-Clare, S; Mack, M C; Brooks, M

    2013-07-01

    Experimental evidence for limitation of net primary productivity (NPP) by nitrogen (N) or phosphorus (P) in lowland tropical forests is rare, and the results from the few existing studies have been inconclusive. To directly test if N or P limit NPP in a lowland tropical wet forest in Costa Rica, we conducted a full factorial fertilization experiment (4 treatments x 6 replicates in 30 x 30 m plots). We focused on the influence of tree size and taxa on nutrient limitation, because in these forests a wide variety of tree functional traits related to nutrient acquisition and use are likely to regulate biogeochemical processes. After 2.7 years, a higher percentage of trees per plot increased basal area (BA) with P additions (66.45% +/- 3.28% without P vs. 76.88% +/- 3.28% with P), but there were no other community-level responses to N or P additions on BA increase, litterfall productivity, or root growth. Phosphorus additions resulted in doubled stem growth rates in small trees (5-10 cm diameter at breast height (dbh); [P < or = 0.01]) but had no effect on intermediate (10-30 cm dbh) or large trees (> 30 cm dbh). Phosphorus additions also increased the percentage of seedling survival from 59% to 78% (P < 0.01), as well as the percentage of seedlings that grew (P = 0.03), and increased leaf number (P = 0.02). Trees from Pentaclethra macroloba, the most abundant species, did not increase growth rates with fertilization (P = 0.40). In contrast, the most abundant palms (Socratea exorrhiza) had more than two times higher stem growth rates with P additions (P = 0.01). Our experiment reiterates that P availability is a significant driver of plant processes in these systems, but highlights the importance of considering different aspects of the plant community when making predictions concerning nutrient limitation. We postulate that in diverse, lowland tropical forests "heterogeneous nutrient limitation" occurs, not only driven by variability in nutrient responses among taxa

  8. Net energy production and emissions mitigation of domestic wastewater treatment system: a comparison of different biogas-sludge use alternatives.

    PubMed

    Chen, Shaoqing; Chen, Bin

    2013-09-01

    Wastewater treatment systems are increasingly designed for the recovery of valuable chemicals and energy in addition to waste stream disposal. Herein, the life-cycle energy production and emissions mitigation of a typical domestic wastewater treatment system were assessed, in which different combinations of biogas use and sludge processing lines for industrial or household applications were considered. The results suggested that the reuse of biogas and sludge was so important in the system's overall energy balance and environmental performance that it may offset the cost in the plant's installation and operation. Combined heat and power and household utilization were two prior options for net energy production, provided an ideal power conversion efficiency and biogas production. The joint application of household biogas use and sludge nutrient processing achieved both high net energy production and significant environmental remediation across all impact categories, representing the optimal tradeoff for domestic wastewater treatment. PMID:23880131

  9. Modeling and spatially distributing forest net primary production at the regional scale.

    PubMed

    Mickler, Robert A; Earnhardt, Todd S; Moore, Jennifer A

    2002-04-01

    Forest, agricultural, rangeland, wetland, and urban landscapes have different rates of carbon sequestration and total carbon sequestration potential under alternative management options. Changes in the proportion and spatial distribution of land use could enhance or degrade that area's ability to sequester carbon in terrestrial ecosystems. As the ecosystems within a landscape change due to natural or anthropogenic processes, they may go from being a carbon sink to a carbon source or vice versa. Satellite image analysis has been tested for timely and accurate measurement of spatially explicit land use change and is well suited for use in inventory and monitoring of terrestrial carbon. The coupling of Landsat Thematic Mapper (TM) data with a physiologically based forest productivity model (PnET-II) and historic climatic data provides an opportunity to enhance field plot-based forest inventory and monitoring methodologies. We use periodic forest inventory data from the U.S. Department of Agriculture (USDA) Forest Service's Forest Inventory and Analysis (FIA) Program to obtain estimates of forest area and type and to generate estimates of carbon storage for evergreen, deciduous, and mixed-forest classes. The area information is used in an accuracy assessment of remotely sensed forest cover at the regional scale. The map display of modeled net primary production (NPP) shows a range of forest carbon storage potentials and their spatial relationship to other landscape features across the southern United States. This methodology addresses the potential for measuring and projecting forest carbon sequestration in the terrestrial biosphere of the southern United States. PMID:12002186

  10. Green Net Regional Product for the San Luis Basin, Colorado: an economic measure of regional sustainability.

    PubMed

    Heberling, Matthew T; Templeton, Joshua J; Wu, Shanshan

    2012-11-30

    This paper presents the data sources and methodology used to estimate Green Net Regional Product (GNRP), a green accounting approach, for the San Luis Basin (SLB). We measured the movement away from sustainability by examining the change in GNRP over time. Any attempt at green accounting requires both economic and natural capital data. However, limited data for the Basin requires a number of simplifying assumptions and requires transforming economic data at the national, state, and county levels to the level of the SLB. Given the contribution of agribusiness to the SLB, we included the depletion of both groundwater and soil as components in the depreciation of natural capital. We also captured the effect of the consumption of energy on climate change for future generations through carbon dioxide (CO(2)) emissions. In order to estimate the depreciation of natural capital, the shadow price of water for agriculture, the economic damages from soil erosion due to wind, and the social cost of carbon emissions were obtained from the literature and applied to the SLB using benefit transfer. We used Colorado's total factor productivity for agriculture to estimate the value of time (i.e., to include the effects of exogenous technological progress). We aggregated the economic data and the depreciation of natural capital for the SLB from 1980 to 2005. The results suggest that GNRP had a slight upward trend through most of this time period, despite temporary negative trends, the longest of which occurred during the period 1985-86 to 1987-88. However, given the upward trend in GNRP and the possibility of business cycles causing the temporary declines, there is no definitive evidence of moving away from sustainability. PMID:22483369

  11. Simulation of the effects of bottom topography on net primary production induced by riverine input

    NASA Astrophysics Data System (ADS)

    Hoshiba, Yasuhiro; Yamanaka, Yasuhiro

    2016-04-01

    Riverine input often leads to high biological productivity in coastal areas. In coastal areas termed as region of freshwater influence (ROFI), horizontal anticyclonic gyres and vertical circulation form by density differences between buoyant river water and sea water. Previous physical oceanography studies have shown that the horizontal pattern of anticyclonic gyres and the strength of vertical circulation are dependent on the bottom topography of ROFI. However, the dependencies of biogeochemical cycles such as the net primary production (NPP) on the bottom topography have not been verified. In order to clarify how the bottom topography affects the NPP in phytoplankton blooms caused by riverine input through the physical processes in ROFI, we used an ocean general circulation model (OGCM) including a simple ecosystem model and conducted several case studies varying the bottom slope angle in the ideal settings. We estimated NPP categorized into three nutrients supplied from the river, the sea-subsurface layer and via regeneration: RI-NPP, S-NPP and RE-NPP. S-NPP and RE-NPP are larger and smaller with a steeper slope, respectively, while RI-NPP is not affected by the slope angle. As a result, total NPP is weakly dependent on the slope angle, i.e., because S- and RE-NPPs cancel each other out through two physical processes, (1) S-NPP is controlled by the strength of the vertical circulation and (2) RE-NPP is controlled by the shape of the horizontal gyre, which both vary with the bottom slope angle. We also conducted realistic simulations for Ishikari Bay, Japan and confirmed a similar dependency to that in the above ideal settings. That is, the simulation results are consistent with the regime of ideal settings and show that RI- and RE-NPPs are important variables for Ishikari Bay which has a gentle slope.

  12. Estimation of net primary productivity using a process-based model in Gansu Province, Northwest China

    SciTech Connect

    Wang, Peijuan; Xie, Donghui; Zhou, Yuyu; E, Youhao; Zhu, Qijiang

    2014-01-16

    The ecological structure in the arid and semi-arid region of Northwest China with forest, grassland, agriculture, Gobi, and desert, is complex, vulnerable, and unstable. It is a challenging and sustaining job to keep the ecological structure and improve its ecological function. Net primary productivity (NPP) modeling can help to improve the understanding of the ecosystem, and therefore, improve ecological efficiency. The boreal ecosystem productivity simulator (BEPS) model provides the possibility of NPP modeling in terrestrial ecosystem, but it has some limitations for application in arid and semi-arid regions. In this paper we improve the BEPS model, in terms of its water cycle by adding the processes of infiltration and surface runoff, to be applicable in arid and semi-arid regions. We model the NPP of forest, grass, and crop in Gansu Province as an experimental area in Northwest China in 2003 using the improved BEPS model, parameterized with moderate resolution remote sensing imageries and meteorological data. The modeled NPP using improved BEPS agrees better with the ground measurements in Qilian Mountain than that with original BEPS, with a higher R2 of 0.746 and lower root mean square error (RMSE) of 46.53 gC/m2 compared to R2 of 0.662 and RMSE of 60.19 gC/m2 from original BEPS. The modeled NPP of three vegetation types using improved BEPS show evident differences compared to that using original BEPS, with the highest difference ratio of 9.21% in forest and the lowest value of 4.29% in crop. The difference ratios between different vegetation types lie on the dependence on natural water sources. The modeled NPP in five geographic zones using improved BEPS are higher than those with original BEPS, with higher difference ratio in dry zones and lower value in wet zones.

  13. Global evidence on nitrogen saturation of terrestrial ecosystem net primary productivity

    NASA Astrophysics Data System (ADS)

    Tian, Dashuan; Wang, Hong; Sun, Jian; Niu, Shuli

    2016-02-01

    The continually increasing nitrogen (N) deposition is expected to increase ecosystem aboveground net primary production (ANPP) until it exceeds plant N demand, causing a nonlinear response and N saturation for ANPP. However, the nonlinear response of ANPP to N addition gradient and the N saturation threshold have not been comprehensively quantified yet for terrestrial ecosystems. In this study, we compiled a global dataset of 44 experimental studies with at least three levels of N treatment. Nitrogen response efficiency (NRE, ANPP response per unit N addition) and the difference in NRE between N levels (ΔNRE) were quantified to test the nonlinearity in ANPP response. We found a universal response pattern of N saturation for ANPP with N addition gradient across all the studies and in different ecosystems. An averaged N saturation threshold for ANPP nonlinearity was found at the N addition rates of 5-6 g m-2 yr-1. The extent to which ANPP approaches N saturation varied with ecosystem type, N addition rate and environmental factors. ANPP in grasslands had lower NRE than those in forests and wetlands. Plant NRE decreased with reduced soil C:N ratio, and was the highest at intermediate levels of rainfall and temperature. These findings suggest that ANPP in grassland or the ecosystems with low soil C:N ratio (or low and high rainfall or temperature) is easier to be saturated with N enrichment. Overall, these results indicate that the beneficial effect of N deposition on plant productivity likely diminishes with continuous N enrichment when N loading surpasses the N saturation threshold for ANPP nonlinearity.

  14. Estimating net primary production of natural grassland and its spatio-temporal distribution in China.

    PubMed

    Zhang, Meiling; Lal, Rattan; Zhao, Youyi; Jiang, Wenlan; Chen, Quangong

    2016-05-15

    The net primary production (NPP) of grassland largely determines terrestrial carbon (C) sinks, and thus plays an important role in the global C cycle. Comprehensive and sequential classification system of grasslands (CSCS) is a unique vegetation classification system (mainly for grassland) that is dependent on quantitative measurement indices [>0°C annual cumulative temperature (Σθ) and moisture index (K-value)]. Based on the relationship of the quantitative classification of CSCS and grassland NPP, a modified model of Carnegie-Ames-Stanford Approach (CASA) was used to predict the grassland NPP and its temporal and spatial distribution in China from 2004 to 2008. The scatter plot of the estimated NPP and the observed NPP showed that the estimated data can be accepted with correlation coefficient of 0.896 (P<0.05). The average annual NPP of grassland from 2004 to 2008 in China ranged from 443.23 to 554.40 g Cm(-2)yr.(-)(1). The NPP also showed spatial-temporal variations. There existed an increasing trend of NPP from the northwest to southeast due to the zonal distribution of vegetation. From the trend of monthly variations, it can be drawn that the NPP accumulation primarily occurred between April and October. The average NPP over seven months from April to October was 482.19 g Cm(-2), or about 88.78% of the annual total. The spatial-temporal trend suggests the importance of water and thermal regimes in determining the grassland NPP (i.e. water and thermal are key limited factors for the grassland production), which is also confirmed by a cluster analysis. The mean annual NPP and the total annual NPP differed significantly among grassland classes corresponding with different Σθ and K-value. The results demonstrate that the grassland NPP and the classes/super-classes in CSCS achieve the optimum coupling. PMID:26925730

  15. From Miami to Madison: Investigating the Relationship Between Climate and Terrestrial Net Primary Production

    NASA Astrophysics Data System (ADS)

    Zaks, D.; Foley, J.; Ramankutty, N.; Barford, C.

    2005-12-01

    The ``Miami Model'' (Lieth, 1975) was the first global scale empirical model of terrestrial net primary productivity (NPP). This model used sparse observations to calibrate NPP based on the minimum of temperature and precipitation functions. The simplicity and relative accuracy of this model has led to its continued use. The development of improved techniques to measure NPP in the field (Gower et al. 1999, 2001; Malhi et al. 2002, Clark et al., 2001), and the expanded spatial and temporal range of observations have prompted this study, which reexamines the relationship of ecophysiological variables to NPP. A large reference dataset (n = 2268) of NPP field observations, including many from the Global Primary Production Data Initiative (Olson et al., 2001), were compiled for calibration and parameter optimization. We developed a rigorous statistical test for several paired climatic variables in order to investigate their relationship to terrestrial NPP. In addition to temperature and precipitation, we chose more robust pairs of independent climatic variables based on their ability to represent plant stressors such as heat and water stress. These variables included growing degree-days base 0, a water stress index, and average incident photosynthetic active radiation (PAR) for each day the average temperature is greater then 0°C. The water stress and PAR indices used in the study were calculated using a simple surface energy and water balance model (Prentice et al., 1993; Foley, 1994; Haxeltine and Prentice, 1996) using climate data from New (2002). Both linear and sigmoidal functional forms were chosen to relate the climatic variables to NPP. The model coefficients were determined by minimizing the least squared error between the observations and simulations. Calculated annual global NPP ranged from 50 - 60 Pg, well within the estimates of previous studies (i.e. Cramer et al. 1999). Spatial patterns of NPP were compared using biome averages as well as latitudinal

  16. Controls of vegetation structure and net primary production in restored grasslands

    USGS Publications Warehouse

    Munson, Seth M.; Lauenroth, William K.

    2014-01-01

    1. Vegetation structure and net primary production (NPP) are fundamental properties of ecosystems. Understanding how restoration practices following disturbance interact with environmental factors to control these properties can provide insight on how ecosystems recover and guide management efforts. 2. We assessed the relative contribution of environmental and restoration factors in controlling vegetation structure, above- and below-ground investment in production across a chronosequence of semiarid Conservation Reserve Program (CRP) fields recovering from dryland wheat cropping relative to undisturbed grassland. Importantly, we determined the role of plant diversity and how seeding either native or introduced perennial grasses influenced the recovery of vegetation properties. 3. Plant basal cover increased with field age and was highest in CRP fields seeded with native perennial grasses. In contrast, fields seeded with introduced perennial grasses had tall-growing plants with relatively low basal cover. These vegetation structural characteristics interacted with precipitation, but not soil characteristics, to influence above-ground NPP (ANPP). Fields enrolled in the CRP program for >7 years supported twice as much ANPP as undisturbed shortgrass steppe in the first wet year of the study, but all CRP fields converged on a common low amount of ANPP in the following dry year and invested less than half as much as the shortgrass steppe in below-ground biomass. 4. ANPP in CRP fields seeded with native perennial grasses for more than 7 years was positively related to species richness, whereas ANPP in CRP fields seeded with introduced perennial grasses were controlled more by dominant species. 5. Synthesis and applications. Seeding with introduced, instead of native, perennial grasses had a strong direct influence on vegetation structure, including species richness, which indirectly affected NPP through time. However, the effects of restoring either native or introduced

  17. CO2 and CH4 Net Carbon Flux from a high-carbon peatland in Northern Minnesota: Plot scale observations of the Shrub, forb, Sphagnum and microbial community

    NASA Astrophysics Data System (ADS)

    Phillips, J. R.; Hanson, P. J.; Riggs, J.

    2013-12-01

    Significant uncertainty exists regarding the fate of stored peatland carbon under future climate warming scenarios. Methods have been developed to track net flux of CO2 and CH4 from experimental warming plots at a scale appropriate to the in situ biological community. Surface flux measurements of CO2 and CH4 were made using and open-path analyzers over and area of 1.13 m2 within each of our 16 plots. A custom-designed chamber encloses the hummock-hollow topography and allows point in time measurements of the shrub, forb, Sphagnum and the complex microbial community complex. These observations are made with ambient light and imposed dark conditions to allow estimates of net community daytime and night respiratory processes. Sphagnum hollow temperatures, water table levels, hummock moisture levels, and recent PAR as a potential surrogate for labile C are all being evaluated as drivers of net CO2-C and CH4-C flux. Periodic observations from August 2011 through July 2013 show obvious seasonal trends with temperature being the obvious driving variable. During this ';wet' time period surface drying and lower water table depths have not been seen to be key drivers of net C flux. Midwinter conditions with a frozen peat surface produce zero CO2 and CH4 flux. Maximum net CO2 flux in mid summer shows daytime surface uptake values near -6 to -7 μmol m-2 s-1 and night loss rates of 6 to 7 μmol m-2 s-1. Maximum midsummer observed CH4 flux for this bog range from 0.4 to 0.5 μmol m-2 s-1. Integrating temperature dependent models of net flux across annual periods showed next CO2-C and net CH4-C flux to be 850 and 20 g C m-2 y-1, respectively. Sequential clipping of vegetation layers showed that the shrub (LAI = ~0.5 m2 m-2) and the forb/sedge layer (LAI = ~1 m2 m-2) dominated net carbon uptake during daytime periods while shading the Sphagnum layer (LAI >1 m2 m-2), but had limited impact on dark community respiration likely dominated by the subsurface microbial community. A

  18. Automation of Presentation Record Production Based on Rich-Media Technology Using SNT Petri Nets Theory

    PubMed Central

    Martiník, Ivo

    2015-01-01

    Rich-media describes a broad range of digital interactive media that is increasingly used in the Internet and also in the support of education. Last year, a special pilot audiovisual lecture room was built as a part of the MERLINGO (MEdia-rich Repository of LearnING Objects) project solution. It contains all the elements of the modern lecture room determined for the implementation of presentation recordings based on the rich-media technologies and their publication online or on-demand featuring the access of all its elements in the automated mode including automatic editing. Property-preserving Petri net process algebras (PPPA) were designed for the specification and verification of the Petri net processes. PPPA does not need to verify the composition of the Petri net processes because all their algebraic operators preserve the specified set of the properties. These original PPPA are significantly generalized for the newly introduced class of the SNT Petri process and agent nets in this paper. The PLACE-SUBST and ASYNC-PROC algebraic operators are defined for this class of Petri nets and their chosen properties are proved. The SNT Petri process and agent nets theory were significantly applied at the design, verification, and implementation of the programming system ensuring the pilot audiovisual lecture room functionality. PMID:26258164

  19. Relationships between net primary productivity and forest stand age in U.S. forests

    NASA Astrophysics Data System (ADS)

    He, Liming; Chen, Jing M.; Pan, Yude; Birdsey, Richard; Kattge, Jens

    2012-09-01

    Net primary productivity (NPP) is a key flux in the terrestrial ecosystem carbon balance, as it summarizes the autotrophic input into the system. Forest NPP varies predictably with stand age, and quantitative information on the NPP-age relationship for different regions and forest types is therefore fundamentally important for forest carbon cycle modeling. We used four terms to calculate NPP: annual accumulation of live biomass, annual mortality of aboveground and belowground biomass, foliage turnover to soil, and fine root turnover in soil. For U.S. forests the first two terms can be reliably estimated from the Forest Inventory and Analysis (FIA) data. Although the last two terms make up more than 50% of total NPP, direct estimates of these fluxes are highly uncertain due to limited availability of empirical relationships between aboveground biomass and foliage or fine root biomass. To resolve this problem, we developed a new approach using maps of leaf area index (LAI) and forest age at 1 km resolution to derive LAI-age relationships for 18 major forest type groups in the USA. These relationships were then used to derive foliage turnover estimates using species-specific trait data for leaf specific area and longevity. These turnover estimates were also used to derive the fine root turnover based on reliable relationships between fine root and foliage turnover. This combination of FIA data, remote sensing, and plant trait information allows for the first empirical and reliable NPP-age relationships for different forest types in the USA. The relationships show a general temporal pattern of rapid increase in NPP in the young ages of forest type groups, peak growth in the middle ages, and slow decline in the mature ages. The predicted patterns are influenced by climate conditions and can be affected by forest management. These relationships were further generalized to three major forest biomes for use by continental-scale carbon cycle models in conjunction with

  20. Uncertainty analysis of gross primary production partitioned from net ecosystem exchange measurements

    NASA Astrophysics Data System (ADS)

    Raj, R.; Hamm, N. A. S.; van der Tol, C.; Stein, A.

    2015-08-01

    Gross primary production (GPP), separated from flux tower measurements of net ecosystem exchange (NEE) of CO2, is used increasingly to validate process-based simulators and remote sensing-derived estimates of simulated GPP at various time steps. Proper validation should include the uncertainty associated with this separation at different time steps. This can be achieved by using a Bayesian framework. In this study, we estimated the uncertainty in GPP at half hourly time steps. We used a non-rectangular hyperbola (NRH) model to separate GPP from flux tower measurements of NEE at the Speulderbos forest site, The Netherlands. The NRH model included the variables that influence GPP, in particular radiation, and temperature. In addition, the NRH model provided a robust empirical relationship between radiation and GPP by including the degree of curvature of the light response curve. Parameters of the NRH model were fitted to the measured NEE data for every 10-day period during the growing season (April to October) in 2009. Adopting a Bayesian approach, we defined the prior distribution of each NRH parameter. Markov chain Monte Carlo (MCMC) simulation was used to update the prior distribution of each NRH parameter. This allowed us to estimate the uncertainty in the separated GPP at half-hourly time steps. This yielded the posterior distribution of GPP at each half hour and allowed the quantification of uncertainty. The time series of posterior distributions thus obtained allowed us to estimate the uncertainty at daily time steps. We compared the informative with non-informative prior distributions of the NRH parameters. The results showed that both choices of prior produced similar posterior distributions GPP. This will provide relevant and important information for the validation of process-based simulators in the future. Furthermore, the obtained posterior distributions of NEE and the NRH parameters are of interest for a range of applications.

  1. Increasing precipitation event size increases aboveground net primary productivity in a semi-arid grassland.

    PubMed

    Heisler-White, Jana L; Knapp, Alan K; Kelly, Eugene F

    2008-11-01

    Water availability is the primary constraint to aboveground net primary productivity (ANPP) in many terrestrial biomes, and it is an ecosystem driver that will be strongly altered by future climate change. Global circulation models predict a shift in precipitation patterns to growing season rainfall events that are larger in size but fewer in number. This "repackaging" of rainfall into large events with long intervening dry intervals could be particularly important in semi-arid grasslands because it is in marked contrast to the frequent but small events that have historically defined this ecosystem. We investigated the effect of more extreme rainfall patterns on ANPP via the use of rainout shelters and paired this experimental manipulation with an investigation of long-term data for ANPP and precipitation. Experimental plots (n = 15) received the long-term (30-year) mean growing season precipitation quantity; however, this amount was distributed as 12, six, or four events applied manually according to seasonal patterns for May-September. The long-term mean (1940-2005) number of rain events in this shortgrass steppe was 14 events, with a minimum of nine events in years of average precipitation. Thus, our experimental treatments pushed this system beyond its recent historical range of variability. Plots receiving fewer, but larger rain events had the highest rates of ANPP (184 +/- 38 g m(-2)), compared to plots receiving more frequent rainfall (105 +/- 24 g m(-2)). ANPP in all experimental plots was greater than long-term mean ANPP for this system (97 g m(-2)), which may be explained in part by the more even distribution of applied rain events. Soil moisture data indicated that larger events led to greater soil water content and likely permitted moisture penetration to deeper in the soil profile. These results indicate that semi-arid grasslands are capable of responding immediately and substantially to forecast shifts to more extreme precipitation patterns. PMID

  2. Uncertainty analysis of gross primary production partitioned from net ecosystem exchange measurements

    NASA Astrophysics Data System (ADS)

    Raj, Rahul; Hamm, Nicholas Alexander Samuel; van der Tol, Christiaan; Stein, Alfred

    2016-03-01

    Gross primary production (GPP) can be separated from flux tower measurements of net ecosystem exchange (NEE) of CO2. This is used increasingly to validate process-based simulators and remote-sensing-derived estimates of simulated GPP at various time steps. Proper validation includes the uncertainty associated with this separation. In this study, uncertainty assessment was done in a Bayesian framework. It was applied to data from the Speulderbos forest site, The Netherlands. We estimated the uncertainty in GPP at half-hourly time steps, using a non-rectangular hyperbola (NRH) model for its separation from the flux tower measurements. The NRH model provides a robust empirical relationship between radiation and GPP. It includes the degree of curvature of the light response curve, radiation and temperature. Parameters of the NRH model were fitted to the measured NEE data for every 10-day period during the growing season (April to October) in 2009. We defined the prior distribution of each NRH parameter and used Markov chain Monte Carlo (MCMC) simulation to estimate the uncertainty in the separated GPP from the posterior distribution at half-hourly time steps. This time series also allowed us to estimate the uncertainty at daily time steps. We compared the informative with the non-informative prior distributions of the NRH parameters and found that both choices produced similar posterior distributions of GPP. This will provide relevant and important information for the validation of process-based simulators in the future. Furthermore, the obtained posterior distributions of NEE and the NRH parameters are of interest for a range of applications.

  3. Social protection for all ages? Impacts of Ethiopia's Productive Safety Net Program on child nutrition.

    PubMed

    Porter, Catherine; Goyal, Radhika

    2016-06-01

    We investigate the impact of a large-scale social protection scheme, the Productive Safety Net Program (PSNP) in Ethiopia, on child nutritional outcomes. Children living in households that receive cash transfers should experience improved child nutrition. However, in the case of the PSNP, which for the majority of participants is a public works program, there are several potential threats to finding effects: first, without conditionality on child inputs, increased household income may not be translated into improved child nutrition. Second, the work requirement may impact on parental time, child time use and calories burned. Third, if there is a critical period for child human capital investment that closes before the age of 5 then children above this age may not see any improvement in medium-term nutritional outcomes, measured here as height-for-age. Using a cohort study that collected data both pre-and post-program implementation in 2002, 2006 and 2009, we exploit several novel aspects of the survey design to find estimates that can deal with non-random program placement. We present both matching and difference-in-differences estimates for the index children, as well as sibling-differences. Our estimates show an important positive medium-term nutritional impact of the program for children aged 5-15 that are comparable in size to Conditional Cash Transfer program impacts for much younger children. We show indicative evidence that the program impact on improved nutrition is associated with improved food security and reduced child working hours. Our robustness checks restrict the comparison group, by including only households who were shortlisted, but never received PSNP, and also exclude those who never received aid, thus identifying impact based on timing alone. We cannot rule out that the nutritional impact of the program is the same for younger and older children. PMID:27176466

  4. The supply and demand of net primary production in the Sahel

    NASA Astrophysics Data System (ADS)

    Abdi, A. M.; Seaquist, J.; Tenenbaum, D. E.; Eklundh, L.; Ardö, J.

    2014-09-01

    Net primary production (NPP) is the principal source of energy for ecosystems and, by extension, human populations that depend on them. The relationship between the supply and demand of NPP is important for the assessment of socio-ecological vulnerability. We present an analysis of the supply and demand of NPP in the Sahel using NPP estimates from the MODIS sensor and agri-environmental data from FAOSTAT. This synergistic approach allows for a spatially explicit estimation of human impact on ecosystems. We estimated the annual amount of NPP required to derive food, fuel and feed between 2000 and 2010 for 22 countries in sub-Saharan Africa. When comparing annual estimates of supply and demand of NPP, we found that demand increased from 0.44 PgC to 1.13 PgC, representing 19% and 41%, respectively, of available supply due to a 31% increase in the human population between 2000 and 2010. The demand for NPP has been increasing at an annual rate of 2.2% but NPP supply was near-constant with an inter-annual variability of approximately 1.7%. Overall, there were statistically significant (p < 0.05) increases in the NPP of cropland (+6.0%), woodland (+6.1%) and grassland/savanna (+9.4%), and a decrease in the NPP of forests (-0.7%). On the demand side, the largest increase was for food (20.4%) followed by feed (16.7%) and fuel (5.5%). The supply-demand balance of NPP is a potentially important tool from the standpoint of sustainable development, and as an indicator of stresses on the environment stemming from increased consumption of biomass.

  5. A new framework for evaluating the impacts of drought on net primary productivity of grassland.

    PubMed

    Lei, Tianjie; Wu, Jianjun; Li, Xiaohan; Geng, Guangpo; Shao, Changliang; Zhou, Hongkui; Wang, Qianfeng; Liu, Leizhen

    2015-12-01

    This paper presented a valuable framework for evaluating the impacts of droughts (single factor) on grassland ecosystems. This framework was defined as the quantitative magnitude of drought impact that unacceptable short-term and long-term effects on ecosystems may experience relative to the reference standard. Long-term effects on ecosystems may occur relative to the reference standard. Net primary productivity (NPP) was selected as the response indicator of drought to assess the quantitative impact of drought on Inner Mongolia grassland based on the Standardized Precipitation Index (SPI) and BIOME-BGC model. The framework consists of six main steps: 1) clearly defining drought scenarios, such as moderate, severe and extreme drought; 2) selecting an appropriate indicator of drought impact; 3) selecting an appropriate ecosystem model and verifying its capabilities, calibrating the bias and assessing the uncertainty; 4) assigning a level of unacceptable impact of drought on the indicator; 5) determining the response of the indicator to drought and normal weather state under global-change; and 6) investigating the unacceptable impact of drought at different spatial scales. We found NPP losses assessed using the new framework were more sensitive to drought and had higher precision than the long-term average method. Moreover, the total and average losses of NPP are different in different grassland types during the drought years from 1961-2009. NPP loss was significantly increased along a gradient of increasing drought levels. Meanwhile, NPP loss variation under the same drought level was different in different grassland types. The operational framework was particularly suited for integrative assessing the effects of different drought events and long-term droughts at multiple spatial scales, which provided essential insights for sciences and societies that must develop coping strategies for ecosystems for such events. PMID:26204052

  6. A cluster randomized controlled cross-over bed net acceptability and preference trial in Solomon Islands: community participation in shaping policy for malaria elimination

    PubMed Central

    2009-01-01

    Background A key component of the malaria elimination strategy in Solomon Islands (SI) is widespread coverage of long-lasting insecticidal nets (LLINs). The success of this strategy is dependent on LLIN acceptability and compliance. There has been unresolved debate among policy makers and donors as to which type of LLIN would be most appropriate for large-scale distribution in SI, and anecdotal reports of a lack of acceptability of certain brands of LLINs. A cluster randomized controlled crossover bed net acceptability and preference trial was therefore carried out from July to September, 2008 to inform policy and to facilitate community engagement and participation in the selection of the most appropriate LLIN for use in SI. Method A three-stage sampling method was used to randomly select the study population from Malaita Province, SI. Three brands of LLINs were assessed in this study: Olyset®, PermaNet® and DuraNet®. Bed net acceptability and preference were evaluated through surveys at three defined time points after short and longer-term trial of each LLIN. Results The acceptability of PermaNet® after short-term use (96.5%) was significantly greater than Olyset® (67.3%, p < 0.001) and DuraNet® (69.8%, p < 0.001). The acceptability of DuraNet® and Olyset® after short-term use was not significantly different at the 5% level. LLINs that were perceived not to prevent mosquito bites were significantly less acceptable than LLINs that were perceived to prevent mosquito bites (OR 0.15; 95%CI 0.03 to 0.6). LLINs that allow a pleasant night's sleep (OR 6.3; 95%CI:3.3-12.3) and have a soft texture (OR 5.7; 95%CI:1.9-20.5) were considered more acceptable than those that did not. Olyset®'s acceptability decreased over time and this was due to net wrinkling/shrinkage after washing resulting in reduced efficiency in preventing mosquito bites. The increase in DuraNet® acceptability was a result of a reduction in minor adverse events following longer-term use

  7. Simulating net ecosystem productivity and the sensitivity of a sub-arctic boreal forest ecosystem

    NASA Astrophysics Data System (ADS)

    Ueyama, M.; Harazono, Y.; Kim, Y.; Tanaka, N.

    2005-12-01

    BIOME-BGC was used to examine how air temperature and precipitation affect NEP in a sub-arctic black spruce forest. The model was tuned using data from the eddy correlation measurement site in UAF black spruce forest during 2003 and 2004. The climate dataset of Fairbanks airport between 1949 and 2004 was used for the model spin-up. The model almost reproduced the observed NEE, in which climate in 2003 was normal and that in 2004 was drought in summer. The model, however, failed to simulate the late winter NEE, during which obvious daytime uptake were observed under extreme low temperature. Annual simulation of GPP and ecosystem respiration was 2.2 and 1.8 kg CO2 m-2 yr-1 in 2003 and 2.4 and 1.9 kg CO2 m-2 yr-1 in 2004. While warm growing season temperature enhanced the photosynthesis and respiration in 2004, significant drought in August 2004 were restricted both the photosynthesis and heterotrophic respiration. Simulated annual NEE was 0.2 kg CO2 m-2 yr-1 in 2003 and 0.3 kg CO2 m-2 yr-1 in 2004. The simulation explored the impact of seasonal warmer (+5oC), wetter (120% of precipitation) and drier (80% of precipitation) spells on net ecosystem productivity, comparing the long term Fairbanks weather between 1980 and 2000. Wetter condition in either season did not significantly affect annual NEP. While drought summer decreased annual NEP by 30% mainly due to reduction in GPP by 9%, low snowfall winter also reduced the annual NEP by 19%, in which low snow water brought drought stress in following summer and then suppressed both GPP to 93% and ecosystem respiration to 96%. Warmer summer and autumn decreased annual NEP to 37% and 65%. In this case, GPP did not increase and maintenance and heterotrophic respiration were enhanced to 120% and 126%, respectively, in warmer summer and 103% and 107%, respectively, in warmer autumn. The simulation unambiguously showed productivity of the sub-arctic boreal forest was significantly sensitive to warmer temperature in summer and

  8. Use of Yohkoh SXT in Measuring the Net Current and CME Productivity of Active Regions

    NASA Technical Reports Server (NTRS)

    Falconer, D. A.; Moore, R. L.; Gary, G. A.; Six, N. Frank (Technical Monitor)

    2001-01-01

    In our investigation of the correlation of global nonpotentiality of active regions to their CME productivity (Falconer, D.A. 2001, JGR, in press, and Falconer, Moore, & Gary, 2000, EOS 82, 20 S323), we use Yohkoh SXT images for two purposes. The first use is to help resolve the 180 degree ambiguity in the direction of the observed transverse magnetic field. Resolution of the 180 degree ambiguity is important, since the net current, one of our measures of global nonpotentiality, is derived from integrating the dot product of the transverse field around a contour (I(sub N)=(integral)BT(raised dot)dl). The ambiguity results from the observed transverse field being determined from the linear polarization, which gives the plane of the direction, but leaves a 180 degrees ambiguity. Automated methods to resolve the ambiguity ranging from the simple acute angle rule (Falconer, D.A. 2001) to the more sophisticated annealing method (Metcalf T.R. 1994). For many active regions, especially ones that are nearly potential these methods work well. But for very nonpotential active regions where the shear angle (the angle between the observed and potential transverse field) is near 90 degrees throughout large swaths along the main neutral line, both methods can resolve the ambiguity incorrectly for long segments of the neutral line. By determining from coronal images, such as those from Yohkoh/SXT, the sense of shear along the main neutral line in the active region, these cases can be identified and corrected by a modification of the acute angle rule described here. The second use of Yohkoh/SXT in this study is to check for the cusped coronal arcades of long-duration eruptive flares. This signature is an excellent proxy for CMEs, and was used by Canfield, Hudson, and McKenzie (1999 GRL V26, 6, 627-630). This work is funded by NSF through the Space Weather Program and by NASA through the Solar Physics Supporting Research and Technology Program.

  9. Sea spray geoengineering can reduce ocean net primary productivity and carbon uptake

    NASA Astrophysics Data System (ADS)

    Partanen, Antti-Ilari; Keller, David; Korhonen, Hannele; Matthews, Damon

    2016-04-01

    Sea spray geoengineering or marine cloud brightening is one of the proposed methods to deliberately increase planetary albedo and thus counteract climate change. Previous studies have shown that it has potential to significantly alter the global energy balance and reduce impacts on temperature and precipitation. However, its effects on ecosystems have received considerably less attention. Our goal is to assess the effects of sea spray geoengineering on marine biological productivity and global carbon cycle. We use the University of Victoria Earth System Climate Model (UVic ESCM) to simulate the effects of prescribed aerosol forcing from previous simulations with the aerosol-climate model ECHAM-HAMMOZ. In our baseline simulation (GEO), forcing from geoengineering was applied over three persistent stratocumulus regions off the coasts of North America, South America, and South Africa. The global mean forcing was -1 W m‑2. Other forcings and emissions were set according to the RCP4.5 scenario. The control run (CTRL) was identical to GEO except that no geoengineering was present. As a more extreme case, we simulated a scenario where forcing from geoengineering was applied over all ocean area (GEO-ALL) giving a global mean forcing of -4.9 W m‑2. Geoengineering decreased the global total ocean net primary productivity (NPP) during the first decades, but the effect was insignificant by the end of the 21st century. The decrease was caused by decreased temperature of the ocean and climate system in general, not by the decrease in available sunlight as might have been expected. This was demonstrated by two sensitivity simulations where geoengineering was affecting only either temperature or the light available to marine ecosystems. The simulation GEO-ALL behaves in a different way than GEO: ocean NPP was lower than that in CTRL for the first three decades of geoengineering as in GEO, but then NPP increased over the level in CTRL for the remaining of the simulation. In

  10. Water use efficiency of net primary production in global terrestrial ecosystems

    NASA Astrophysics Data System (ADS)

    Xia, Lei; Wang, Fei; Mu, Xingmin; Jin, Kai; Sun, Wenyi; Gao, Peng; Zhao, Guangju

    2015-07-01

    The carbon and water cycles of terrestrial ecosystems, which are strongly coupled via water use efficiency (WUE), are influenced by global climate change. To explore the relationship between the carbon and water cycles and predict the effect of climate change on terrestrial ecosystems, it is necessary to study the WUE in global terrestrial ecosystems. In this study, the 13-year WUE (i.e., net primary production (NPP)/evapotranspiration (ET)) of global terrestrial ecosystems was calculated based on the Moderate Resolution Imaging Spectro-radiometer (MODIS) NPP (MOD17A3) and ET (MOD16A3) products from 2000 to 2012. The results indicate that the annual average WUE decreased but not significantly, and the 13-year mean value was 868.88 mg C m -2 mm -1. The variation trend of WUE value for each pixel differed greatly across the terrestrial ecosystems. A significant variation ( P<0.05) occurred in about 18.50% of the land surface. WUE was spatially distributed from 0 to 2541 mg C m -2 mm -1, and 58.78% of the WUE values were concentrated in the interval of 600-1200 mg C m -2 mm -1. The WUE increased from north to south in Africa and Oceania and from east to west in Europe and South America. Both latitudinal and longitudinal gradients existed in Asia and North America. The following trends in the WUE of different continents and Köppen-Geiger climates were observed: Europe (1129.71 mg C m -2 mm -1)> Oceania (1084.46 mg C m -2 mm -1)> Africa (893.51 mg C m -2 mm -1)> South America (893.07 mg C m -2 mm -1)> North America (870.79 mg C m -2 mm -1)> Asia (738.98 mg C m -2 mm -1) and warm temperate climates (1094 mg C m -2 mm -1)> snowy climates (862 mg C m -2 mm -1)> arid climates (785 mg C m -2 mm -1)> equatorial climates (732 mg C m -2 mm -1)> polar climates (435 mg C m -2 mm -1). Based on the WUE value and the present or future rainfall, the maximum carbon that fixed in one region may be theoretically calculated. Also, under the background of global climatic change, WUE may

  11. Mesozooplankton community composition, feeding, and export production during SOIREE

    NASA Astrophysics Data System (ADS)

    Zeldis, John

    The community composition and feeding rates of mesozooplankton (>200 μm length) were determined using plankton hauls, bottle incubations and gut pigment determinations during Southern Ocean Iron RElease Experiment (SOIREE) in the Southern Ocean in February 1999. Upper-ocean (0-65 m) mesozooplankton biomass (4.2 and 3.2 g m -2, inside and outside the iron-fertilised patch, respectively) was dominated by large copepodites (>1.5 mm). Salps and euphausiids were absent and very rare, respectively. Incubations using large copepods showed no significant difference in clearance rates of nano- (2-20 μm) and net- (>20 μm) plankton. Mean clearance rates inside and outside the iron-fertilised patch also did not differ and were very low (ca. 50 ml mg DW -1 d -1). Mean ingestion rate, however, was significantly greater in the patch due to higher algal and heterotrophic nanoflagellate (HNAN) biomass there. Gut pigment analysis showed that most ingestion by large, medium and small copepods occurred at night, and that specific ingestion was greatest in small copepods. Daily integrated ingestion rates determined by the incubation and gut pigment methods were similar for comparable large copepods. Phytoplankton and HNAN ingestion met only 14% of the estimated daily respiratory carbon requirements of the large copepods inside the patch, and 4% outside. Little ciliate or detrital carbon was available in the system, which could have further supplemented the food supply. A number of other studies have found a similar disparity between ingestion and nutritional requirements in copepods. Reasons for this include the possibility that fine-scale aggregations of copepods and their food have not been adequately sampled, or that measured metabolic rates have been systematically overestimated. Ingestion of phytoplankton by the total copepod community was low, with <1% of standing stock removed per day (inside and outside the patch) and 4% and 8% of primary production removed (inside and

  12. Impacts of climate change drivers on C4 grassland productivity: scaling driver effects through the plant community.

    PubMed

    Polley, H Wayne; Derner, Justin D; Jackson, Robert B; Wilsey, Brian J; Fay, Philip A

    2014-07-01

    Climate change drivers affect plant community productivity via three pathways: (i) direct effects of drivers on plants; (ii) the response of species abundances to drivers (community response); and (iii) the feedback effect of community change on productivity (community effect). The contribution of each pathway to driver-productivity relationships depends on functional traits of dominant species. We used data from three experiments in Texas, USA, to assess the role of community dynamics in the aboveground net primary productivity (ANPP) response of C4 grasslands to two climate drivers applied singly: atmospheric CO2 enrichment and augmented summer precipitation. The ANPP-driver response differed among experiments because community responses and effects differed. ANPP increased by 80-120g m(-2) per 100 μl l(-1) rise in CO2 in separate experiments with pasture and tallgrass prairie assemblages. Augmenting ambient precipitation by 128mm during one summer month each year increased ANPP more in native than in exotic communities in a third experiment. The community effect accounted for 21-38% of the ANPP CO2 response in the prairie experiment but little of the response in the pasture experiment. The community response to CO2 was linked to species traits associated with greater soil water from reduced transpiration (e.g. greater height). Community effects on the ANPP CO2 response and the greater ANPP response of native than exotic communities to augmented precipitation depended on species differences in transpiration efficiency. These results indicate that feedbacks from community change influenced ANPP-driver responses. However, the species traits that regulated community effects on ANPP differed from the traits that determined how communities responded to drivers. PMID:24501178

  13. Controlling Malaria in Western Pacific with Mosquito Nets Treated with Pyrethroids in Village Communities, 1979-1999.

    PubMed

    Self, Lee

    2016-07-01

    Insecticide-treated mosquito nets were first put to practical use in the Western Pacific Region. Less than a decade after conducting workshops and other promotional activities, millions of people were protected by 1989. This occurred before the availability of commercially produced pretreated nets and before global funding for mass net distribution. This paper describes the sequence of steps leading to regional control success. The beginning stages in 1979 recognized that treating torn mosquito nets was a viable control option. Basic net treatment procedures were established by 1983 and workshops were held the next 2 years in China, Cambodia, Laos, Malaysia, Papua New Guinea, Philippines, Solomon Islands, Vanuatu, and Vietnam. Malaria staff became convinced of net benefits and were motivated to impart their knowledge to others. Village inhabitants soaked the nets in washbasins containing permethrin or deltamethrin solution, then dried them horizontally on mats. By the 1990s, the population protected by nets had appreciably increased, and regional malaria cases confirmed by microscopy were markedly reduced. This coincided with commercial interest to mass-produce pretreated mosquito nets for worldwide use. PMID:26880771

  14. Expansive Learning as Production of Community

    ERIC Educational Resources Information Center

    Morck, Line Lerche

    2010-01-01

    This article contributes a framework for analyzing learning as an expansive process in which persons come to partly transcend marginalization. Expansive learning is a kind of learning that partly transcends marginalization through changed participation and recognition by others of participants in their changed communities. This article draws on…

  15. Increasing Productivity in the Community College. Topical Paper Number 67.

    ERIC Educational Resources Information Center

    Goodwin, Gregory; Young, James C.

    Drawing heavily on the speeches and discussions that took place at a League for Innovation in the Community College conference held late in 1977 in North Carolina, this paper discusses the problem of increasing productivity in community colleges. Although escalating costs and decreasing revenues over the past decade have given the problem of…

  16. Variations of net ecosystem production due to seasonal precipitation differences in a tropical dry forest of northwest Mexico

    NASA Astrophysics Data System (ADS)

    Verduzco, Vivian S.; Garatuza-Payán, Jaime; Yépez, Enrico A.; Watts, Christopher J.; Rodríguez, Julio C.; Robles-Morua, Agustin; Vivoni, Enrique R.

    2015-10-01

    Due to their large extent and high primary productivity, tropical dry forests (TDF) are important contributors to atmospheric carbon exchanges in subtropical and tropical regions. In northwest Mexico, a bimodal precipitation regime that includes winter precipitation derived from Pacific storms and summer precipitation from the North American monsoon (NAM) couples water availability with ecosystem processes. We investigated the net ecosystem production of a TDF ecosystem using a 4.5 year record of water and carbon fluxes obtained from the eddy covariance method complemented with remotely sensed data. We identified a large CO2 efflux at the start of the summer season that is strongly related to the preceding winter precipitation and greenness. Since this CO2 efflux occurs prior to vegetation green-up, we infer that respiration is mainly due to decomposition of soil organic matter accumulated from the prior growing season. Overall, ecosystem respiration has an important effect on the net ecosystem production but can be overwhelmed by the strength of the primary productivity during the NAM. Precipitation characteristics during NAM have significant controls on sustaining carbon fixation in the TDF into the fall season. We identified that a threshold of ~350 to 400 mm of monsoon precipitation leads to a switch in the annual carbon balance in the TDF ecosystem from a net source (+102 g C/m2/yr) to a net sink (-249 g C/m2/yr). This monsoonal precipitation threshold is typically exceeded one out of every 2 years. The close coupling of winter and summer periods with respect to carbon fluxes suggests that the annual carbon balance is dependent on precipitation amounts in both seasons in TDF ecosystems.

  17. Quantifying Human Appropriated Net Primary Productivity (HANPP) in a Ghanaian Cocoa System

    NASA Astrophysics Data System (ADS)

    Morel, A.; Adu-Bredu, S.; Adu Sasu, M.; Ashley Asare, R.; Boyd, E.; Hirons, M. A.; Malhi, Y.; Mason, J.; Norris, K.; Robinson, E. J. Z.; McDermott, C. L.

    2015-12-01

    Ghana is the second largest producer of cocoa (Theobroma cacoa), exporting approximately 18 percent of global volumes. These cocoa farms are predominantly small-scale, ranging in size from 2-4 hectares (ha). Traditionally, the model of cocoa expansion in Ghana relied on clearing new areas of forest and establishing a farm under remnant forest trees. This is increasingly less practical due to few unprotected forest areas remaining and management practices favoring close to full sun cocoa to maximize short-term yields. This study is part of a larger project, ECOLMITS, which is an interdisciplinary, ESPA-funded[1] initiative exploring the ecological limits of ecosystem system services (ESS) for alleviating poverty in small-scale agroforestry systems. The ecological study plots are situated within and around the Kakum National Forest, a well-protected, moist-evergreen forest of the Lower Guinea Forest region. Net primary productivity (NPP) is a measure of the rate at which carbon dioxide (CO2) is incorporated into plant tissues (e.g. canopy, stem and root). For this study, NPP was monitored in situ using methods developed by the Global Environmental Monitoring Network (GEM, http://gem.tropicalforests.ox.ac.uk/). By comparing NPP measured in intact forest and farms, the human appropriated NPP (HANPP) of this system can be estimated. The forest measures provide the "potential" NPP of the region, and then the reduction in NPP for farm plots is calculated for both land-cover change (HANPPLUC) and cocoa harvesting (HANPPHARV). The results presented are of the first year of NPP measurements across the cocoa landscape, including measurements from intact forest, logged forest and cocoa farms across a shade gradient and located at varying distances from the forest edge (e.g. 100 m, 500 m, 1 km and 5 km). These measures will have implications for carbon sequestration potential over the region and long-term sustainability of the Ghanaian cocoa sector. [1] Ecosystem Services for

  18. The uncertainties of the net primary production due to regional and seasonal temperature changes in China

    NASA Astrophysics Data System (ADS)

    Sun, Guodong

    2015-04-01

    A kind of temperature change scenario is supplied by the approach of conditional nonlinear optimal perturbation related to parameter (CNOP-P) to estimate the variation of the net primary production (NPP)in North-South transect of eastern China within a state-of-the-art Lund-Potsdam-Jena dynamical global vegetation model (LPJ DGVM). There are two traits for the kind of temperature change scenario. Firstly, the kind of temperature change scenario considers the regional and seasonal differences in North-South transect of eastern China. The character of the temperature change is similar to the observation data due to the observational constraint. Secondly, the kind of temperature change scenario causes the maximal possible impact on the simulated NPP to discuss the maximal uncertainty in the simulated NPP to the temperature change in North-South transect of eastern China. Other two kinds of temperature change scenarios are also applied to explain the above two traits and to analyze variations due to different kinds of temperature change scenarios. It is shown that the kind of temperature change scenario resulted of the CNOP-P approach, which is called as the CNOP-P-type temperature change scenario, exhibits the regional and seasonal temperature differences in North-South transect of eastern China. The NPP decreases by 1.84% in northern China, and respectively increases by 4.09% and 18.99% in northeastern and southern China as the results of the CNOP-P-type temperature change scenario, though the NPP increases in small part of northern China and decreases in part of northeastern China. The variations in the NPP caused by the CNOP-P-type temperature change scenario are different to those by the other two types of temperature change scenarios in northern, northeastern China and southern China. The impact of the CNOP-P-type temperature change scenario on the NPP is intenser than that of the other two types of temperature change scenarios. The seasonal analyses demonstrate

  19. Efficacy, Outcomes, and Empowerment Evaluation of a School District NET Project, Part II: School and Community Impact. Research Brief.

    ERIC Educational Resources Information Center

    Miller-Whitehead, Marie

    This study addressed assessing the efficacy and outcomes of a U.S. Department of Agriculture Nutrition Education Training (NET) project designed to increase awareness of health risk and wellness factors for grade 9 students. Although this paper reprises results from a survey of 125 ninth graders about the NET curriculum, the focus of this part of…

  20. Established dietary estimates of net acid production do not predict measured net acid excretion in patients with Type 2 diabetes on Paleolithic-Hunter-Gatherer-type diets

    PubMed Central

    Frassetto, Lynda A; Shi, Lijie; Schloetter, Monique; Sebastian, Anthony; Remer, Thomas

    2014-01-01

    Background Formulas developed to estimate diet-dependent net acid excretion (NAE) generally agree with measured values for typical Western diets. Whether they can also appropriately predict NAE for "Paleolithic-type" (Paleo) diets – which contain very high amounts of fruits and vegetables (F&V) and concurrent high amounts of protein is unknown. Here we compare measured NAEs with established NAE-estimates in subjects with Type 2 diabetes (T2D). Methods Thirteen subjects with well controlled T2D were randomized to either a Paleo or American Diabetes Association (ADA) diet for 14 days. 24-hour urine collections were performed at baseline and end of the diet period, and analyzed for titratable acid, bicarbonate, and ammonium to calculate measured NAE. Three formulas for estimating NAE from dietary intake were used; two (NAE_diet R or L) that include dietary mineral intake and sulfate- and organic acid (OA) production, and one that is empirically-derived (NAE_diet F) only considering potassium and protein intake. Results Measured NAE on the Paleo diet was significantly lower than on the ADA diet (+31±22 vs. 112±52 mEq/day, p=0.002). Although all formula estimates showed similar and reasonable correlations (r=0.52–0.76) with measured NAE, each one underestimated measured values. The formula with the best correlation did not contain an estimate of dietary organic acid production. Conclusions Paleo diets are lower in NAE than typical Western diets. However, commonly used formulas clearly underestimate NAE, especially for diets with very high F&V (as the Paleo diet), and in subjects with T2D. This may be due to an inappropriate estimation of proton loads stemming from OAs, underlining the necessity for improved measures of OA-related proton sources. PMID:23859996

  1. Net primary productivity, upwelling and coastal currents in the Gulf of Ulloa, Baja California, México

    NASA Astrophysics Data System (ADS)

    González-Rodríguez, E.; Trasviña-Castro, A.; Gaxiola-Castro, G.; Zamudio, L.; Cervantes-Duarte, R.

    2012-08-01

    The Gulf of Ulloa, a highly productive area off the western coast of the Baja California Peninsula, is examined for five successive years (2003-2007) by using satellite data and seasonal net primary productivity (NPP) estimates obtained from a vertical generalised production model. The results identify that northwestern winds blow parallel to the coast throughout the year. However, highest NPP occurs from March to June. During this period, an equatorward coastal current transports water from neighbouring upwelling areas to the northern Gulf of Ulloa and in combination with local upwelling, which injects nutrients into the euphotic zone, produce the observed increase in NPP. The opposite situation occurs in late summer when a warm poleward current of tropical characteristics arrives and inhibits the productivity in the whole region and generates the yearly lowest NPP levels. Our findings reveal the importance of lateral advection in the modulation of the primary productivity in this subtropical upwelling region.

  2. Soil Carbon Change and Net Energy Associated with Biofuel Production on Marginal Lands: A Regional Modeling Perspective

    SciTech Connect

    Bandaru, Varaprasad; Izaurralde, Roberto C.; Manowitz, David H.; Link, Robert P.; Zhang, Xuesong; Post, W. M.

    2013-12-01

    The use of marginal lands (MLs) for biofuel production has been contemplated as a promising solution for meeting biofuel demands. However, there have been concerns with spatial location of MLs, their inherent biofuel potential, and possible environmental consequences with the cultivation of energy crops. Here, we developed a new quantitative approach that integrates high-resolution land cover and land productivity maps and uses conditional probability density functions for analyzing land use patterns as a function of land productivity to classify the agricultural lands. We subsequently applied this method to determine available productive croplands (P-CLs) and non-crop marginal lands (NC-MLs) in a nine-county Southern Michigan. Furthermore, Spatially Explicit Integrated Modeling Framework (SEIMF) using EPIC (Environmental Policy Integrated Climate) was used to understand the net energy (NE) and soil organic carbon (SOC) implications of cultivating different annual and perennial production systems.

  3. Geographical Factors Affecting Bed Net Ownership, a Tool for the Elimination of Anopheles-Transmitted Lymphatic Filariasis in Hard-to-Reach Communities

    PubMed Central

    Stanton, Michelle C.; Bockarie, Moses J.; Kelly-Hope, Louise A.

    2013-01-01

    Vector control, including the use of bed nets, is recommended as a possible strategy for eliminating lymphatic filariasis (LF) in post-conflict countries such as the Democratic Republic of Congo (DRC). This study examined the geographical factors that influence bed net ownership in DRC in order to identify hard-to-reach communities that need to be better targeted. In particular, urban/rural differences and the influence of population density, proximity to cities and health facilities, plus access to major transport networks were investigated. Demographic and Health Survey geo-referenced cluster level data were used to map bed net coverage (proportion of households with at least one of any type of bed net or at least one insecticide-treated net (ITN)), and ITN density (ITNs per person) for 260 clusters. Bivariate and multiple logistic or Poisson regression analyses were used to determine significant relationships. Overall, bed net (30%) and ITN (9%) coverage were very low with significant differences found between urban and rural clusters. In rural clusters, ITN coverage/density was positively correlated with population density (r = 0.25, 0.27 respectively, p<0.01), and negatively with the distance to the two largest cities, Kinshasa or Lubumbashi (r = −0.28, −0.30 respectively, p<0.0001). Further, ownership was significantly negatively correlated with distance to primary national roads and railways (all three measures), distance to main rivers (any bed net only) and distance to the nearest health facility (ITNs only). Logistic and Poisson regression models fitted to the rural cluster data indicated that, after controlling for measured covariates, ownership levels in the Bas-Congo province close to Kinshasa were much larger than that of other provinces. This was most noticeable when considering ITN coverage (odds ratio: 5.3, 95% CI: 3.67–7.70). This analysis provides key insights into the barriers of bed net ownership, which will help inform both LF

  4. Geographical factors affecting bed net ownership, a tool for the elimination of Anopheles-transmitted lymphatic filariasis in hard-to-reach communities.

    PubMed

    Stanton, Michelle C; Bockarie, Moses J; Kelly-Hope, Louise A

    2013-01-01

    Vector control, including the use of bed nets, is recommended as a possible strategy for eliminating lymphatic filariasis (LF) in post-conflict countries such as the Democratic Republic of Congo (DRC). This study examined the geographical factors that influence bed net ownership in DRC in order to identify hard-to-reach communities that need to be better targeted. In particular, urban/rural differences and the influence of population density, proximity to cities and health facilities, plus access to major transport networks were investigated. Demographic and Health Survey geo-referenced cluster level data were used to map bed net coverage (proportion of households with at least one of any type of bed net or at least one insecticide-treated net (ITN)), and ITN density (ITNs per person) for 260 clusters. Bivariate and multiple logistic or Poisson regression analyses were used to determine significant relationships. Overall, bed net (30%) and ITN (9%) coverage were very low with significant differences found between urban and rural clusters. In rural clusters, ITN coverage/density was positively correlated with population density (r = 0.25, 0.27 respectively, p<0.01), and negatively with the distance to the two largest cities, Kinshasa or Lubumbashi (r = -0.28, -0.30 respectively, p<0.0001). Further, ownership was significantly negatively correlated with distance to primary national roads and railways (all three measures), distance to main rivers (any bed net only) and distance to the nearest health facility (ITNs only). Logistic and Poisson regression models fitted to the rural cluster data indicated that, after controlling for measured covariates, ownership levels in the Bas-Congo province close to Kinshasa were much larger than that of other provinces. This was most noticeable when considering ITN coverage (odds ratio: 5.3, 95% CI: 3.67-7.70). This analysis provides key insights into the barriers of bed net ownership, which will help inform both LF and

  5. Exploring Global Patterns in Human Appropriation of Net Primary Production Using Earth Observation Satellites and Statistical Data

    NASA Astrophysics Data System (ADS)

    Imhoff, M.; Bounoua, L.

    2004-12-01

    A unique combination of satellite and socio-economic data were used to explore the relationship between human consumption and the carbon cycle. Biophysical models were applied to consumption data to estimate the annual amount of Earth's terrestrial net primary production humans require for food, fiber and fuel using the same modeling architecture as satellite-supported NPP measurements. The amount of Earth's NPP required to support human activities is a powerful measure of the aggregate human impacts on the biosphere and indicator of societal vulnerability to climate change. Equations were developed estimating the amount of landscape-level NPP required to generate all the products consumed by 230 countries including; vegetal foods, meat, milk, eggs, wood, fuel-wood, paper and fiber. The amount of NPP required was calculated on a per capita basis and projected onto a global map of population to create a spatially explicit map of NPP-carbon demand in units of elemental carbon. NPP demand was compared to a map of Earth's average annual net primary production or supply created using 17 years (1982-1998) of AVHRR vegetation index to produce a geographically accurate balance sheet of terrestrial NPP-carbon supply and demand. Globally, humans consume 20 percent of Earth's total net primary production on land. Regionally the NPP-carbon balance percentage varies from 6 to over 70 percent and locally from near 0 to over 30,000 percent in major urban areas. The uneven distribution of NPP-carbon supply and demand, indicate the degree to which various human populations rely on NPP imports, are vulnerable to climate change and suggest policy options for slowing future growth in NPP demand.

  6. Estimation of Ecosystem Parameters of the Community Land Model with DREAM: Evaluation of the Potential for Upscaling Net Ecosystem Exchange

    NASA Astrophysics Data System (ADS)

    Hendricks Franssen, H. J.; Post, H.; Vrugt, J. A.; Fox, A. M.; Baatz, R.; Kumbhar, P.; Vereecken, H.

    2015-12-01

    Estimation of net ecosystem exchange (NEE) by land surface models is strongly affected by uncertain ecosystem parameters and initial conditions. A possible approach is the estimation of plant functional type (PFT) specific parameters for sites with measurement data like NEE and application of the parameters at other sites with the same PFT and no measurements. This upscaling strategy was evaluated in this work for sites in Germany and France. Ecosystem parameters and initial conditions were estimated with NEE-time series of one year length, or a time series of only one season. The DREAM(zs) algorithm was used for the estimation of parameters and initial conditions. DREAM(zs) is not limited to Gaussian distributions and can condition to large time series of measurement data simultaneously. DREAM(zs) was used in combination with the Community Land Model (CLM) v4.5. Parameter estimates were evaluated by model predictions at the same site for an independent verification period. In addition, the parameter estimates were evaluated at other, independent sites situated >500km away with the same PFT. The main conclusions are: i) simulations with estimated parameters reproduced better the NEE measurement data in the verification periods, including the annual NEE-sum (23% improvement), annual NEE-cycle and average diurnal NEE course (error reduction by factor 1,6); ii) estimated parameters based on seasonal NEE-data outperformed estimated parameters based on yearly data; iii) in addition, those seasonal parameters were often also significantly different from their yearly equivalents; iv) estimated parameters were significantly different if initial conditions were estimated together with the parameters. We conclude that estimated PFT-specific parameters improve land surface model predictions significantly at independent verification sites and for independent verification periods so that their potential for upscaling is demonstrated. However, simulation results also indicate

  7. Community Television. A Handbook for Production.

    ERIC Educational Resources Information Center

    American Association of Retired Persons, Washington, DC.

    This manual is designed to encourage older people to take an active role in local television program production and to design and produce programs that will enhance the quality of life for other older Americans. It is noted that locally produced television offers older people a voice at the local level, the opportunity for making new friends and…

  8. Forest cockchafer larvae as methane production hotspots in soils and their importance for net soil methane fluxes

    NASA Astrophysics Data System (ADS)

    Görres, Carolyn-Monika; Kammann, Claudia; Murphy, Paul; Müller, Christoph

    2016-04-01

    Certain groups of soil invertebrates, namely scarab beetles and millipedes, are capable of emitting considerable amounts of methane due to methanogens inhabiting their gut system. It was already pointed out in the early 1990's, that these groups of invertebrates may represent a globally important source of methane. However, apart from termites, the importance of invertebrates for the soil methane budget is still unknown. Here, we present preliminary results of a laboratory soil incubation experiment elucidating the influence of forest cockchafer larvae (Melolontha hippocastani FABRICIUS) on soil methane cycling. In January/February 2016, two soils from two different management systems - one from a pine forest (extensive use) and one from a vegetable field (intensive use) - were incubated for 56 days either with or without beetle larvae. Net soil methane fluxes and larvae methane emissions together with their stable carbon isotope signatures were quantified at regular intervals to estimate gross methane production and gross methane oxidation in the soils. The results of this experiment will contribute to testing the hypothesis of whether methane production hotspots can significantly enhance the methane oxidation capacity of soils. Forest cockchafer larvae are only found in well-aerated sandy soils where one would usually not suspect relevant gross methane production. Thus, besides quantifying their contribution to net soil methane fluxes, they are also ideal organisms to study the effect of methane production hotspots on overall soil methane cycling. Funding support: Reintegration grant of the German Academic Exchange Service (DAAD) (#57185798).

  9. Near-Net-Shape Production of Hollow Titanium Alloy Components via Electrochemical Reduction of Metal Oxide Precursors in Molten Salts

    NASA Astrophysics Data System (ADS)

    Hu, Di; Xiao, Wei; Chen, George Z.

    2013-04-01

    Metal oxide precursors (ca. 90 wt pct Ti, 6 wt pct Al, and 4 wt pct V) were prepared with a hollow structure in various shapes such as a sphere, miniature golf club head, and cup using a one-step solid slip-casting process. The precursors were then electro-deoxidized in molten calcium chloride [3.2 V, 1173 K (900 °C)] against a graphite anode. After 24 hours of electrolysis, the near-net-shape Ti-6Al-4V product maintained its original shape with controlled shrinkage. Oxygen contents in the Ti-6Al-4V components were typically below 2000 ppm. The maximum compressive stress and modulus of electrolytic products obtained in this work were approximately 243 MPa and 14 GPa, respectively, matching with the requirement for medical implants. Further research directions are discussed for mechanical improvement of the products via densification during or after electrolysis. This simple, fast, and energy-efficient near-net-shape manufacturing method could allow titanium alloy components with desired geometries to be prepared directly from a mixture of metal oxides, promising an innovative technology for the low-cost production of titanium alloy components.

  10. Warming and Elevated CO2 Interact to Drive Rapid Shifts in Marine Community Production

    PubMed Central

    Sorte, Cascade J. B.; Bracken, Matthew E. S.

    2015-01-01

    Predicting the outcome of future climate change requires an understanding of how alterations in multiple environmental factors manifest in natural communities and affect ecosystem functioning. We conducted an in situ, fully factorial field manipulation of CO2 and temperature on a rocky shoreline in southeastern Alaska, USA. Warming strongly impacted functioning of tide pool systems within one month, with the rate of net community production (NCP) more than doubling in warmed pools under ambient CO2 levels relative to initial NCP values. However, in pools with added CO2, NCP was unaffected by warming. Productivity responses paralleled changes in the carbon-to-nitrogen ratio of a red alga, the most abundant primary producer species in the system, highlighting the direct link between physiology and ecosystem functioning. These observed changes in algal physiology and community productivity in response to our manipulations indicate the potential for natural systems to shift rapidly in response to changing climatic conditions and for multiple environmental factors to act antagonistically. PMID:26714167