WorldWideScience

Sample records for california grassland experiment

  1. The California Valley grassland

    Science.gov (United States)

    Keeley, J.E.; Schoenherr, Allan A.

    1990-01-01

    Grasslands are distributed throughout California from Oregon to Baja California Norte and from the coast to the desert (Brown 1982) (Figure 1). This review will focus on the dominant formation in cismontane California, a community referred to as Valley Grassland (Munz 1959). Today, Valley Grassland is dominated by non-native annual grasses in genera such as Avena (wild oat), Bromus (brome grass), and Hordeum (barley), and is often referred to as the California annual grassland. On localized sites, native perennial bunchgrasses such as Stipa pultra (purple needle grass) may dominate and such sites are interpreted to be remnants of the pristine valley grassland. In northwestern California a floristically distinct formation of the Valley Grassland, known as Coast Prairie (Munz 1959) or Northern Coastal Grassland (Holland and Keil 1989) is recognized. The dominant grasses include many native perennial bunchgrasses in genera such as Agrostis, Calamagrostis, Danthonia, Deschampsia, Festuca, Koeleria and Poa (Heady et al. 1977). Non-native annuals do not dominate, but on some sites non-native perennials like Anthoxanthum odoratum may colonize the native grassland (Foin and Hektner 1986). Elevationally, California's grasslands extend from sea level to at leas 1500 m. The upper boundary is vague because montane grassland formations are commonly referred to as meadows; a community which Munz (1959) does not recognize. Holland and Keil (1989) describe the montane meadow as an azonal community; that is, a community restricted not so much to a particular climatic zone but rather controlled by substrate characteristics. They consider poor soil-drainage an over-riding factor in the development of montane meadows and, in contrast to grasslands, meadows often remain green through the summer drought. Floristically, meadows are composed of graminoids; Cyperaceae, Juncaceae, and rhizomatous grasses such as Agropyron (wheat grass). Some bunchgrasses, such as Muhlenbergia rigens, are

  2. Variation in soil moisture and N availability modulates carbon and water exchange in a California grassland experiment

    Energy Technology Data Exchange (ETDEWEB)

    St. Clair, S.B.; Sudderth, E.; Fischer, M.L.; Torn, M.S.; Stuart, S.; Salve, R.; Eggett, D.; Ackerly, D.

    2009-03-15

    Variability in the magnitude and timing of precipitation is predicted to change under future climate scenarios. The primary objective of this study was to understand how variation in precipitation patterns consisting of soil moisture pulses mixed with intermittent dry down events influence ecosystem gas fluxes. We characterized the effects of precipitation amount and timing, N availability, and plant community composition on whole ecosystem and leaf gas exchange in a California annual grassland mesocosm study system that allowed precise control of soil moisture conditions. Ecosystem CO2 and fluxes increased significantly with greater precipitation and were positively correlated with soil moisture. A repeated 10 day dry down period following 11 days of variable precipitation inputs strongly depressed net ecosystem CO2 exchange (NEE) across a range of season precipitation totals, and plant community types. Ecosystem respiration (Re), evapotranspiration (ET) and leaf level photosynthesis (Amax) showed greatest sensitivity to dry down periods in low precipitation plots. Nitrogen additions significantly increased NEE, Re and Amax, particularly as water availability was increased. These results demonstrate that N availability and intermittent periods of soil moisture deficit (across a wide range of cumulative season precipitation totals) strongly modulate ecosystem gas exchange.

  3. Threshold responses to interacting global changes in a California grassland ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Field, Christopher [Carnegie Inst. of Science, Stanford, CA (United States); Mooney, Harold [Stanford Univ., CA (United States); Vitousek, Peter [Stanford Univ., CA (United States)

    2015-02-02

    Building on the history and infrastructure of the Jasper Ridge Global Change Experiment, we conducted experiments to explore the potential for single and combined global changes to stimulate fundamental type changes in ecosystems that start the experiment as California annual grassland. Using a carefully orchestrated set of seedling introductions, followed by careful study and later removal, the grassland was poised to enable two major kinds of transitions that occur in real life and that have major implications for ecosystem structure, function, and services. These are transitions from grassland to shrubland/forest and grassland to thistle patch. The experiment took place in the context of 4 global change factors – warming, elevated CO2, N deposition, and increased precipitation – in a full-factorial array, present as all possible 1, 2, 3, and 4-factor combinations, with each combination replicated 8 times.

  4. Arbuscular mycorrhiza fungi mediate soil respiration response to climate change in California grasslands

    Science.gov (United States)

    Estruch, Carme; Mcfarland, Jack; Haw, Monica P.; Schulz, Marjorie S.; Pugnaire, Francisco I.; Waldrop, Mark P.

    2017-04-01

    California grasslands store ca. 100 Tg of soil organic carbon (SOC) and almost 40% of those ecosystems are prone to land use changes. The fate of these carbon pools will largely depend on how the main components of soil respiration - i.e., roots, mycorrhiza, and 'bulk soil' communities- respond to such changes. In order to determine the sensitivity to environmental drivers we set up an experiment to address the effect of plant community composition, soil age and warming on soil respiration rate during the 2014-2015 winter. We tested differences among microbial, fungal and root respiration using an exclusion technique to assess the effect of plant community (open grasslands vs oak woodland) in two field sites differing in soil properties as nutrient content, related to geologic soil age (92 and 137 kyr). We also used open top chambers (OTC) to simulate global change effects on grasslands. Our results showed that arbuscular mycorrhizal fungi were the main drivers of differences recorded between soils of different age, and that those differences were linked to nutrient availability. Bulk soil respiration was more sensitive to environmental variation than mycorrhizal or root respiration, indicating that the presence of mycorrhizae and roots can regulate the capacity of CO2 emission to the atmosphere. Soil age affected CO2 flux from grasslands but not under oak canopies, likely due to the high concentration of SOM in oak canopies which moderated any affect of soil mineralogy on nutrient availability. Overall our study shows that the ability of grasslands to mitigate CO2 emissions depends on interactions between vegetation and their rhizosphere on soil microbial communities.

  5. Temporal dynamics of soil nematode communities in a grassland plant diversity experiment.

    NARCIS (Netherlands)

    Viketoft, M.; Sohlenius, B.; Bostrom, S.; Palmborg, C.; Bengtsson, J.; Berg, M.P.; Kuss-Danell, K.

    2011-01-01

    We report here on an 8-year study examining links between plant and nematode communities in a grassland plant diversity experiment, located in the north of Sweden on previous agricultural soil. The examined plots contained 1, 4 and 12 common grassland plant species from three functional groups;

  6. Seasonal variation in carbon dioxide exchange over a Mediterranean annual grassland in California

    Energy Technology Data Exchange (ETDEWEB)

    Xu, L; Baldocchi, D

    2004-05-01

    Understanding how environmental variables affect the processes that regulate the carbon flux over grassland is critical for large-scale modeling research, since grasslands comprise almost one-third of the earth's natural vegetation. To address this issue, fluxes of CO{sub 2} (F{sub c}, flux toward the surface is negative) were measured over a Mediterranean, annual grassland in California, USA for 2 years with the eddy covariance method. To interpret the biotic and abiotic factors that modulate F{sub c} over the course of a year we decomposed net ecosystem CO{sub 2} exchange into its constituent components, ecosystem respiration (R{sub eco}) and gross primary production (GPP). Daytime R{sub eco} was extrapolated from the relationship between temperature and nighttime F{sub c} under high turbulent conditions. Then, GPP was estimated by subtracting daytime values of F{sub c} from daytime estimates of R{sub eco}. Results show that most of carbon exchange, both photosynthesis and respiration, was limited to the wet season (typically from October to mid-May). Seasonal variations in GPP followed closely to changes in leaf area index, which in turn was governed by soil moisture, available sunlight and the timing of the last frost. In general, R{sub eco} was an exponential function of soil temperature, but with season-dependent values of Q{sub 10}. The temperature-dependent respiration model failed immediately after rain events, when large pulses of R{sub eco} were observed. Respiration pulses were especially notable during the dry season when the grass was dead and were the consequence of quickly stimulated microbial activity. Integrated values of GPP, R{sub eco}, and net ecosystem exchange (NEE) were 867, 735, and -132g C m{sup -2}, respectively, for the 2000-2001 season, and 729, 758, and 29g C m{sup -2} for the 2001-2002 season. Thus, the grassland was a moderate carbon sink during the first season and a weak carbon source during the second season. In contrast to a

  7. Leaf trait response to nutrients and herbivore exclusion across a globally replicated grassland experiment

    Science.gov (United States)

    Firn, Jennifer

    2017-04-01

    Leaf trait response to nutrients and herbivore exclusion across a globally replicated grassland experiment Jennifer Firn1, James McGree2, Eric Lind3, Elizabeth Borer3, Eric Seabloom3, Lauren Sullivan3, Kimberly Lapierre4 and the Nutrient Network 1Queensland University of Technology (QUT), School of Earth, Environmental and Biological Sciences, Science and Engineering Faculty, Brisbane, QLD, 4001 Australia 2Queensland University of Technology (QUT), School of Mathematical Sciences, Science and Engineering Faculty, Brisbane, QLD, 4001 Australia 3Universtiy of Minnesota, Department of Ecology, Evolution, and Behavior, 1479 Gortner Avenue, 140 Gortner Laboratory, St. Paul, MN 55108 USA 4Department of integrative Biology, University of California, Berkeley, CA 94720 USA Functional trait research has developed with the aim of finding general patterns in how the function of plant assemblages changes with respect to different land-uses. Most studies have compared sites within and across regions with variations in land-use history, but not necessarily with standardized treatments in an experimental framework. The trends that have emerged from this research is that characteristics of leaf traits such as specific leaf area (SLA) correlate with carbon acquisition strategies known to influence ecosystem functioning. SLA has been found to represent a plant's investment in growing light-capturing area per dry mass content. Species with a relatively high SLA tend to have a higher rate of return on the resources invested into making tissue (cheaper leaves in terms of energy and resources needed to produce them) when compared to species with a lower SLA (more expensive leaves to produce). Few studies have examined quantitatively measured traits in an experimental framework. The Nutrient Network experiment, globally distributed experiment, presents a unique opportunity to examine the response of functional traits across grassland ecosystems characterised by a diverse range of

  8. Evaluating ecosystem services provided by non-native species: an experimental test in California grasslands.

    Science.gov (United States)

    Stein, Claudia; Hallett, Lauren M; Harpole, W Stanley; Suding, Katharine N

    2014-01-01

    The concept of ecosystem services--the benefits that nature provides to human's society--has gained increasing attention over the past decade. Increasing global abiotic and biotic change, including species invasions, is threatening the secure delivery of these ecosystem services. Efficient evaluation methods of ecosystem services are urgently needed to improve our ability to determine management strategies and restoration goals in face of these new emerging ecosystems. Considering a range of multiple ecosystem functions may be a useful way to determine such strategies. We tested this framework experimentally in California grasslands, where large shifts in species composition have occurred since the late 1700's. We compared a suite of ecosystem functions within one historic native and two non-native species assemblages under different grazing intensities to address how different species assemblages vary in provisioning, regulatory and supporting ecosystem services. Forage production was reduced in one non-native assemblage (medusahead). Cultural ecosystem services, such as native species diversity, were inherently lower in both non-native assemblages, whereas most other services were maintained across grazing intensities. All systems provided similar ecosystem services under the highest grazing intensity treatment, which simulated unsustainable grazing intensity. We suggest that applying a more comprehensive ecosystem framework that considers multiple ecosystem services to evaluate new emerging ecosystems is a valuable tool to determine management goals and how to intervene in a changing ecosystem.

  9. Distribution modelling of pre-Columbian California grasslands with soil phytoliths: New insights for prehistoric grassland ecology and restoration.

    Science.gov (United States)

    Fick, Stephen E; Evett, Rand R

    2018-01-01

    Historical reconstructions of plant community distributions are useful for biogeographic studies and restoration planning, but the quality of insights gained depends on the depth and reliability of historical information available. For the Central Valley of California, one of the most altered terrestrial ecosystems on the planet, this task is particularly difficult given poor historical documentation and sparse relict assemblages of pre-invasion plant species. Coastal and interior prairies were long assumed to have been dominated by perennial bunchgrasses, but this hypothesis has recently been challenged. We evaluated this hypothesis by creating species distribution models (SDMs) using a novel approach based on the abundance of soil phytoliths (microscopic particles of biogenic silica used as a proxy for long-term grass presence) extracted from soil samples at locations statewide. Modeled historical grass abundance was consistently high along the coast and to a lesser extent in higher elevation foothills surrounding the Central Valley. SDMs found strong associations with mean temperature, temperature variability, and precipitation variability, with higher predicted abundance in regions with cooler, equable temperatures and moderated rainfall, mirroring the pattern for modern perennial grass distribution across the state. The results of this study strongly suggest that the pre-Columbian Central Valley of California was not dominated by grasses. Using soil phytolith data as input for SDMs is a promising new method for predicting the extent of prehistoric grass distributions where alternative historical datasets are lacking.

  10. Stereo photo series for quantifying natural fuels.Volume XIII: grasslands, shrublands, oak-bay woodlands, and eucalyptus forests in the East Bay of California.

    Science.gov (United States)

    Clinton S. Wright; Robert E. Vihnanek

    2014-01-01

    Four series of photographs display a range of natural conditions and fuel loadings for grassland, shrubland, oak-bay woodland, and eucalyptus forest ecosystems on the eastern slopes of the San Francisco Bay area of California. Each group of photos includes inventory information summarizing vegetation composition, structure, and loading; woody material loading and...

  11. Changes in vegetation types and Ellenberg indicator values after 65 years of fertilizer application in the Rengen Grassland Experiment, Germany

    NARCIS (Netherlands)

    Chytry, M.; Hejcman, M.; Hennekens, S.M.; Schellberg, J.

    2009-01-01

    Question: How does semi-natural grassland diversify after 65 years of differential application of Ca, N, P, and K fertilizers? Is fertilizer application adequately reflected by the Ellenberg indicator values (EIVs)? Location: Eifel Mountains, West Germany. Methods: The Rengen Grassland Experiment

  12. Heterogeneity of water flow in grassland soil during irrigation experiment

    Czech Academy of Sciences Publication Activity Database

    Lichner, Ľ.; Dušek, J.; Tesař, Miroslav; Czachor, H.; Mészároš, I.

    2014-01-01

    Roč. 69, č. 11 (2014), s. 1555-1561 ISSN 0006-3088 R&D Projects: GA TA ČR(CZ) TA0201451 Grant - others:ERDF ITMS26240120004 Institutional support: RVO:67985874 Keywords : degree of preferential flow * effective cross section * infiltration experiment * radioactive tracer technique * sandy soil Subject RIV: DA - Hydrology ; Limnology Impact factor: 0.827, year: 2014

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

    Science.gov (United States)

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

    2017-08-01

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

  14. USING CALIBRATED RGB IMAGERY FROM LOW-COST UAVS FOR GRASSLAND MONITORING: CASE STUDY AT THE RENGEN GRASSLAND EXPERIMENT (RGE, GERMANY

    Directory of Open Access Journals (Sweden)

    U. Lussem

    2017-08-01

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

  15. Habitat selection by female northern pintails wintering in the Grassland Ecological Area, California

    Science.gov (United States)

    Fleskes, Joseph P.; Gilmer, David S.; Jarvis, Robert L.

    2004-01-01

    To determine relative importance of habitats available in the Grassland Ecological Area (GEA) to wintering female northern pintails, Anas acuta, we studied habitat use relative to availability (i.e., habitat selection) in the GEA during September through March, 1991-94 for 196 Hatch-Year (HY) and 221 After-Hatch-Year (AHY) female pintails that were radio tagged during August-early October in the GEA (n = 239), other San Joaquin Valley areas (n = 132), or other Central Valley areas (n = 46). Habitat availability and use varied among seasons and years, but pintails always selected shallow and, except on hunting days, open habitats. Swamp timothy, Heleochloa schoenoides, marsh was the most available, used, and selected habitat. Watergrass, Echinochloa crusgalli, marsh in the GEA was used less than available at night in contrast to previous studies in other SJV areas. Preferred late-winter habitats were apparently lacking in the GEA, at least relative to in the Sacramento Valley and Delta where most pintails moved to in December each year. Impacts on pintails of the increasing practice of managing marshes for increased emergent vegetation to attract other species should be monitored. Shallow, open habitats that produce seeds and invertebrates available to pintails in late winter would help maintain pintail abundance in the GEA.

  16. Invasion of non-native grasses causes a drop in soil carbon storage in California grasslands

    Energy Technology Data Exchange (ETDEWEB)

    Koteen, Laura E; Harte, John [Energy and Resources Group, 310 Barrows Hall, University of California, Berkeley, CA 94720 (United States); Baldocchi, Dennis D, E-mail: lkoteen@berkeley.edu [Department of Environmental Science, Policy and Management, 137 Mulford Hall, University of California, Berkeley, CA 94720 (United States)

    2011-10-15

    Vegetation change can affect the magnitude and direction of global climate change via its effect on carbon cycling among plants, the soil and the atmosphere. The invasion of non-native plants is a major cause of land cover change, of biodiversity loss, and of other changes in ecosystem structure and function. In California, annual grasses from Mediterranean Europe have nearly displaced native perennial grasses across the coastal hillsides and terraces of the state. Our study examines the impact of this invasion on carbon cycling and storage at two sites in northern coastal California. The results suggest that annual grass invasion has caused an average drop in soil carbon storage of 40 Mg/ha in the top half meter of soil, although additional mechanisms may also contribute to soil carbon losses. We attribute the reduction in soil carbon storage to low rates of net primary production in non-native annuals relative to perennial grasses, a shift in rooting depth and water use to primarily shallow sources, and soil respiratory losses in non-native grass soils that exceed production rates. These results indicate that even seemingly subtle land cover changes can significantly impact ecosystem functions in general, and carbon storage in particular.

  17. Invasion of non-native grasses causes a drop in soil carbon storage in California grasslands

    Science.gov (United States)

    Koteen, Laura E.; Baldocchi, Dennis D.; Harte, John

    2011-10-01

    Vegetation change can affect the magnitude and direction of global climate change via its effect on carbon cycling among plants, the soil and the atmosphere. The invasion of non-native plants is a major cause of land cover change, of biodiversity loss, and of other changes in ecosystem structure and function. In California, annual grasses from Mediterranean Europe have nearly displaced native perennial grasses across the coastal hillsides and terraces of the state. Our study examines the impact of this invasion on carbon cycling and storage at two sites in northern coastal California. The results suggest that annual grass invasion has caused an average drop in soil carbon storage of 40 Mg/ha in the top half meter of soil, although additional mechanisms may also contribute to soil carbon losses. We attribute the reduction in soil carbon storage to low rates of net primary production in non-native annuals relative to perennial grasses, a shift in rooting depth and water use to primarily shallow sources, and soil respiratory losses in non-native grass soils that exceed production rates. These results indicate that even seemingly subtle land cover changes can significantly impact ecosystem functions in general, and carbon storage in particular.

  18. Invasion of non-native grasses causes a drop in soil carbon storage in California grasslands

    International Nuclear Information System (INIS)

    Koteen, Laura E; Harte, John; Baldocchi, Dennis D

    2011-01-01

    Vegetation change can affect the magnitude and direction of global climate change via its effect on carbon cycling among plants, the soil and the atmosphere. The invasion of non-native plants is a major cause of land cover change, of biodiversity loss, and of other changes in ecosystem structure and function. In California, annual grasses from Mediterranean Europe have nearly displaced native perennial grasses across the coastal hillsides and terraces of the state. Our study examines the impact of this invasion on carbon cycling and storage at two sites in northern coastal California. The results suggest that annual grass invasion has caused an average drop in soil carbon storage of 40 Mg/ha in the top half meter of soil, although additional mechanisms may also contribute to soil carbon losses. We attribute the reduction in soil carbon storage to low rates of net primary production in non-native annuals relative to perennial grasses, a shift in rooting depth and water use to primarily shallow sources, and soil respiratory losses in non-native grass soils that exceed production rates. These results indicate that even seemingly subtle land cover changes can significantly impact ecosystem functions in general, and carbon storage in particular.

  19. Weed suppression greatly increased by plant diversity in intensively managed grasslands: A continental-scale experiment.

    Science.gov (United States)

    Connolly, John; Sebastià, Maria-Teresa; Kirwan, Laura; Finn, John Anthony; Llurba, Rosa; Suter, Matthias; Collins, Rosemary P; Porqueddu, Claudio; Helgadóttir, Áslaug; Baadshaug, Ole H; Bélanger, Gilles; Black, Alistair; Brophy, Caroline; Čop, Jure; Dalmannsdóttir, Sigridur; Delgado, Ignacio; Elgersma, Anjo; Fothergill, Michael; Frankow-Lindberg, Bodil E; Ghesquiere, An; Golinski, Piotr; Grieu, Philippe; Gustavsson, Anne-Maj; Höglind, Mats; Huguenin-Elie, Olivier; Jørgensen, Marit; Kadziuliene, Zydre; Lunnan, Tor; Nykanen-Kurki, Paivi; Ribas, Angela; Taube, Friedhelm; Thumm, Ulrich; De Vliegher, Alex; Lüscher, Andreas

    2018-03-01

    Grassland diversity can support sustainable intensification of grassland production through increased yields, reduced inputs and limited weed invasion. We report the effects of diversity on weed suppression from 3 years of a 31-site continental-scale field experiment.At each site, 15 grassland communities comprising four monocultures and 11 four-species mixtures based on a wide range of species' proportions were sown at two densities and managed by cutting. Forage species were selected according to two crossed functional traits, "method of nitrogen acquisition" and "pattern of temporal development".Across sites, years and sown densities, annual weed biomass in mixtures and monocultures was 0.5 and 2.0 t  DM ha -1 (7% and 33% of total biomass respectively). Over 95% of mixtures had weed biomass lower than the average of monocultures, and in two-thirds of cases, lower than in the most suppressive monoculture (transgressive suppression). Suppression was significantly transgressive for 58% of site-years. Transgressive suppression by mixtures was maintained across years, independent of site productivity.Based on models, average weed biomass in mixture over the whole experiment was 52% less (95% confidence interval: 30%-75%) than in the most suppressive monoculture. Transgressive suppression of weed biomass was significant at each year across all mixtures and for each mixture.Weed biomass was consistently low across all mixtures and years and was in some cases significantly but not largely different from that in the equiproportional mixture. The average variability (standard deviation) of annual weed biomass within a site was much lower for mixtures (0.42) than for monocultures (1.77). Synthesis and applications . Weed invasion can be diminished through a combination of forage species selected for complementarity and persistence traits in systems designed to reduce reliance on fertiliser nitrogen. In this study, effects of diversity on weed suppression were

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

    Directory of Open Access Journals (Sweden)

    David Ward

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

  1. California's experience with alternative fuel vehicles

    International Nuclear Information System (INIS)

    Sullivan, C.

    1993-01-01

    California is often referred to as a nation-state, and in many aspects fits that description. The state represents the seventh largest economy in the world. Most of California does not have to worry about fuel to heat homes in the winter. What we do worry about is fuel for our motor vehicles, approximately 24 million of them. In fact, California accounts for ten percent of new vehicle sales in the United States each year, much of it used in the transportation sector. The state is the third largest consumer of gasoline in the world, only exceeded by the United States as a whole and the former Soviet Union. California is also a leader in air pollution. Of the nine worst ozone areas in the country cited in the 1990 Clean Air Act Amendments, two areas the Los Angeles Basin and San Diego are located in California. Five of California's cities made the top 20 smoggiest cities in the United States. In reality, all of California's major metropolitan areas have air quality problems. This paper will discuss the beginnings of California's investigations of alternative fuels use in vehicles; the results of the state's demonstration programs; and future plans to improve California's air quality and energy security in the mobile sector

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

    Science.gov (United States)

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

    2013-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Kevin S Ellison

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

  4. Research priorities for grassland science: the need of long term integrated experiments networks

    Directory of Open Access Journals (Sweden)

    G. Lemaire

    2007-07-01

    Full Text Available Grasslands have to be considered not only as a mean for providing foods for domestic herbivore but also as an important biome of terrestrial biosphere. This function of grasslands as an active component of our environment requires specific studies on the role and impact of this ecosystem on soil erosion and soil quality, quality and quantity of water resources, atmosphere composition and greenhouse gas emission or sequestration, biodiversity dynamics at different scales from field plot to landscape. All these functions have to be evaluated in conjunction with the function of providing animal products for increasing human population. So multifunctionality of grasslands become a new paradigm for grassland science. Environmental and biodiversity outputs require long term studies, being the long term retro-active processes within soil, vegetation and micro-organism communities in relation to changes in management programme. So grassland science needs to carry on long term integrated experimentation for studying all the environmental outputs and ecological services associated to grassland management systems.

  5. Dynamics of a grassland ecosystem: botanical equilibrium in the Park Grass Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Silvertown, J

    1980-01-01

    The published results of the Park Grass Experiment (PGE), begun in 1856, provide up to 30 yr of annual data which may be used to determine whether the botanical composition of these grasslands was at equilibrium. Data covering a period exceeding 80 yr are available to test for relationships between hay yield (biomass), species diversity, species number and time. Species diversity and species number show negative relationships with plot biomass and with pH. These relationships were constant over time. The effects of biomass and pH on species number and species diversity were additive. Analysis of the flora of nine plots, each divided into grasses, legumes and a miscellaneous component showed that these components were at equilibrium. The effect of various endogenous factors on this botanical equilibrium was examined. No regular or irregular cycles of component biomass operating between years were detected and it is inferred that populations were regulated by processes operating within individual years. The biomasses of all three components were positively correlated within an unfertilized plot but the floristic components of plots receiving a fertilizer treatment showed few within-plot correlations. By contrast between-plot correlations of components were common for all plots with the exception of those receiving nitrogen fertilizer. The mechanisms of population regulation which maintained the park grass ecosystem at equilibrium are discussed and tests for these are proposed.

  6. Pioneering in wind energy: the California experience

    International Nuclear Information System (INIS)

    Righter, R.W.

    1996-01-01

    In California today nearly 16,000 wind generators are spinning, providing for the electrical needs of roughly one million residents. Yet in 1980, just sixteen years ago, the state was without wind generators, save for a few experimental models. It is time to reflect on this remarkable growth. What caused it? What transformed a ''soft energy path'' dream into reality? This paper will focus on four central factors: (1) political climate, (2) tax incentives, (3) the PURPA Act of 1978, and (4) a sympathetic public utility commission. (author)

  7. Grassland Sustainability

    Science.gov (United States)

    Deborah U. Potter; Paulette L. Ford

    2004-01-01

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

  8. Asymmetric responses of primary productivity to precipitation extremes: A synthesis of grassland precipitation manipulation experiments.

    Science.gov (United States)

    Wilcox, Kevin R; Shi, Zheng; Gherardi, Laureano A; Lemoine, Nathan P; Koerner, Sally E; Hoover, David L; Bork, Edward; Byrne, Kerry M; Cahill, James; Collins, Scott L; Evans, Sarah; Gilgen, Anna K; Holub, Petr; Jiang, Lifen; Knapp, Alan K; LeCain, Daniel; Liang, Junyi; Garcia-Palacios, Pablo; Peñuelas, Josep; Pockman, William T; Smith, Melinda D; Sun, Shanghua; White, Shannon R; Yahdjian, Laura; Zhu, Kai; Luo, Yiqi

    2017-10-01

    Climatic changes are altering Earth's hydrological cycle, resulting in altered precipitation amounts, increased interannual variability of precipitation, and more frequent extreme precipitation events. These trends will likely continue into the future, having substantial impacts on net primary productivity (NPP) and associated ecosystem services such as food production and carbon sequestration. Frequently, experimental manipulations of precipitation have linked altered precipitation regimes to changes in NPP. Yet, findings have been diverse and substantial uncertainty still surrounds generalities describing patterns of ecosystem sensitivity to altered precipitation. Additionally, we do not know whether previously observed correlations between NPP and precipitation remain accurate when precipitation changes become extreme. We synthesized results from 83 case studies of experimental precipitation manipulations in grasslands worldwide. We used meta-analytical techniques to search for generalities and asymmetries of aboveground NPP (ANPP) and belowground NPP (BNPP) responses to both the direction and magnitude of precipitation change. Sensitivity (i.e., productivity response standardized by the amount of precipitation change) of BNPP was similar under precipitation additions and reductions, but ANPP was more sensitive to precipitation additions than reductions; this was especially evident in drier ecosystems. Additionally, overall relationships between the magnitude of productivity responses and the magnitude of precipitation change were saturating in form. The saturating form of this relationship was likely driven by ANPP responses to very extreme precipitation increases, although there were limited studies imposing extreme precipitation change, and there was considerable variation among experiments. This highlights the importance of incorporating gradients of manipulations, ranging from extreme drought to extreme precipitation increases into future climate change

  9. Asymmetric responses of primary productivity to precipitation extremes: A synthesis of grassland precipitation manipulation experiments

    Czech Academy of Sciences Publication Activity Database

    Wilcox, K. R.; Shi, Z.; Gherardi, L. A.; Lemoine, N. P.; Koerner, S. E.; Hoover, D. L.; Bork, E.; Byrne, K. M.; Cahill, J.; Collins, S. L.; Evans, S.M.; Gilgen, Anna K.; Holub, Petr; Jiang, L.; Knapp, A. K.; LeCain, D.; Liang, J.; Garcia-Palacios, P.; Penuelas, J.; Pockman, W. T.; Smith, M. D.; Sun, S.; White, S. R.; Yahdjian, L.; Zhu, K.; Luo, Y.

    2017-01-01

    Roč. 23, č. 10 (2017), s. 4376-4385 ISSN 1354-1013 Institutional support: RVO:86652079 Keywords : net primary productivity * terrestrial ecosystems * temperate grassland * biomass allocation * plant-communities * tallgrass prairie * climate extremes * use efficiency * united-states * global-change * aboveground net primary productivity * belowground net primary productivity * biomass allocation * climate change * grasslands * meta-analysis * root biomass Subject RIV: EH - Ecology, Behaviour OBOR OECD: Environmental sciences (social aspects to be 5.7) Impact factor: 8.502, year: 2016

  10. The Rengen Grassland experiment: bryophytes biomass and element concentrations after 65 years of fertilizer application.

    Science.gov (United States)

    Hejcman, Michal; Száková, Jirina; Schellberg, Jürgen; Srek, Petr; Tlustos, Pavel; Balík, Jirí

    2010-07-01

    The Rengen Grassland Experiment in Germany, established in 1941, consists of the following fertilizer treatments applied under a two cut management: control, Ca, CaN, CaNP, CaNP-KCl, and CaNP-K(2)SO(4). The aim of this study was (1) to identify effects of fertilizer application on biomass and species composition of bryophytes and (2) to investigate the impact of fertilizer application on macro- (N, P, K, Ca, Mg), micro- (Cu, Fe, Mn, Zn), and toxic (As, Cd, Cr, Pb, Ni) element concentrations in bryophyte biomass. In June 2006, Rhytidiadelphus squarrosus was the only bryophyte species recorded in the control. In treatment Ca, R. squarrosus was the dominant bryophyte species whereas Brachythecium rutabulum occurred sporadically only in a single plot of that treatment. The latter was the only bryophyte species collected in CaN, CaNP, CaNP-KCl, and CaNP-K(2)SO(4) treatments. Dry matter accumulation of bryophytes was highest in the control (180 g m(-2)) followed by Ca (46 g m(-2)), CaNP (25 g m(-2)), CaNP-KCl (15 g m(-2)), CaNP-K(2)SO(4) (9 g m(-2)), and CaN (2 g m(-2)) treatments. A negative correlation between biomass production of bryophytes and dry matter production of vascular plants was revealed up to a threshold value of 400 g m(-2). Above this limit, biomass production of bryophytes remained obviously unaffected by further increase in biomass production of vascular plants. A significant effect of treatment on As, Cd, Cr, Fe, Mn, Ni, Pb, P, Ca, Mg, K, and N concentrations was revealed. Concentrations of these elements were a function of amount of elements supplied with fertilizers. Bryophytes seem to be promising bio-indicators not only for airborne deposition of toxic element but also for fertilizer introduced as well.

  11. Vegetation recovery in slash-pile scars following conifer removal in a grassland-restoration experiment

    Science.gov (United States)

    Charles B. Halpern; Joseph A. Antos; Liam M. Beckman

    2014-01-01

    A principal challenge to restoring tree-invaded grasslands is the removal of woody biomass. Burning of slash piles to reduce woody residues from forest restoration practices generates intense, prolonged heating, with adverse effects on soils and vegetation. In this study, we examined vegetation responses to pile burning following tree removal from conifer-invaded...

  12. Biogenic and pedogenic controls on Si distributions and cycling in grasslands of the Santa Cruz soil chronosequence, California

    Science.gov (United States)

    White, Art F.; Vivit, Davison V.; Schulz, Marjorie S.; Bullen, Tom D.; Evett, Rand R.; Aagarwal, Jugdeep

    2012-10-01

    Biogenic and pedogenic processes control silica cycling in grasslands growing on a soil chronosequence and dominated by strong seasonal variabilities of a Mediterranean climate. Shallow pore water Si, in spite of significant annual uptake and release by plant growth and dieback, exhibits only moderate seasonal fluctuations reflecting strong buffering from labile biogenic Si, dominated by phytoliths and by secondary pedogenic silicates. Long phytolith residence times (340-900 yrs) reflect the seasonally dry climate and high solute Si concentrations. Water-extractable Si is closely associated with Al, indicating seasonal precipitation and dissolution of a highly labile 1:1 hydroxyaluminosilicate (HAS), probably allophane, which transforms in deeper soil into fine grained, poorly crystalline kaolinite. Shallow plant roots extract greater proportions of biogenic Si and deeper plant roots larger amounts pedogenic Si. High pore water Ge/Si in late winter and spring reflects the reinforcing effects of plant fractionation and concurrent dissolution of Ge-enriched HAS. The same processes produce pore waters with depleted 30Si/28Si. In the summer and fall, Ge/Si declines and 30Si/28Si increases, reflecting the cessation of plant uptake, continued dissolution of soil phytoliths and re-precipitation of less soluble HAS. Si inputs from weathering (2-90 mmol m-2 yr-1) and losses from pore water discharge (18-68 mM m-2 yr-1) are comparable for individual soils, decline with soil age and are significantly less than amounts of Si annual cycled through the vegetation (42-171 mM m-2 yr-1). Mobile Si is generally balanced in the soils with upward bio-pumping by the shallow-rooted grasses efficiently competing against downward leaching and pore water discharge. Small net annual increases in Si in the present day soils could not have been maintained over the time scale represented by the chronosequence (65-225 yrs), implying past changes in environmental conditions.

  13. USING CALIBRATED RGB IMAGERY FROM LOW-COST UAVS FOR GRASSLAND MONITORING: CASE STUDY AT THE RENGEN GRASSLAND EXPERIMENT (RGE), GERMANY

    OpenAIRE

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

    2017-01-01

    Monitoring the spectral response of intensively managed grassland throughout the growing season allows optimizing fertilizer inputs by monitoring plant growth. For example, site-specific fertilizer application as part of precision agriculture (PA) management requires information within short time. But, this requires field-based measurements with hyper- or multispectral sensors, which may not be feasible on a day to day farming practice. Exploiting the information of RGB images from consumer g...

  14. Terrestrial activity and conservation of adult California red-legged frogs Rana aurora draytonii in coastal forests and grasslands

    Science.gov (United States)

    Bulger, J.B.; Scott, N.J.; Seymour, R.B.

    2003-01-01

    The federally threatened California red-legged frog Rana aurora draytonii occupies both aquatic and terrestrial habitats in its adult life stage. The terrestrial activities of this species are not well known and require documentation to assist in the development of appropriate levels of protection under the US Endangered Species Act. We studied the terrestrial activities of radio-tagged red-legged frogs (n = 8-26) inhabiting a coastal watershed in Santa Cruz County, California, during 1997-1998. In particular, we investigated (1) the use of terrestrial habitats by non-migrating adults in relation to season, breeding chronology, and precipitation, and (2) adult migration behavior, including seasonal timing, duration, distances traveled, and the use of corridors. Non-migrating red-legged frogs occupied terrestrial habitats briefly (median = 4-6 days) following infrequent summer rains, but resided nearly continuously on land (median = 20-30 days) from the onset of the winter wet-season until breeding activities commenced 1-2 months later. All of the non-migrating frogs remained within 130 m of their aquatic site of residence (median days), despite frequent and copious rainfall. Adult migration to and from breeding sites occurred from late October through mid-May (wet season). We monitored 25 migration events between aquatic sites that were 200-2800 m apart. Short distance movements ( days, longer movements required up to 2 months. Most migrating frogs moved overland in approximately straight lines to target sites without apparent regard to vegetation type or topography. Riparian corridors were neither essential nor preferred as migration routes. Frogs traveling overland occurred in upland habitats as far as 500 m from water. Approximately 11-22% of the adult population was estimated to migrate to and from breeding sites annually, whereas the bulk of the adult population was resident at these sites. Adequate protection of red-legged frog populations inhabiting

  15. Turnover and storage of C and N in five density fractions from California annual grassland surface soils

    Science.gov (United States)

    Baisden, W. T.; Amundson, R.; Cook, A. C.; Brenner, D. L.

    2002-12-01

    We measured 14C/12C in density fractions from soils collected before and after atmospheric thermonuclear weapons testing to examine soil organic matter (SOM) dynamics along a 3 million year California soil chronosequence. The mineral-free particulate organic matter (FPOM; 2.2 g cm-3) consists of relatively OM-free sand and OM-rich clays. Three indicators of decomposition (C:N, δ13C, and δ15N) all suggest increasing SOM decomposition with increasing fraction density. The Δ14C-derived SOM turnover rates suggest that ≥90% of FPOM turns over in millenial) SOM. Within each soil, the four mineral-associated fractions display approximately the same residence time (34-42 years in 200 kyr soil, 29-37 years in 600 kyr soil, and 18-26 years in 1-3 Myr soils), indicating that a single stabilized SOM "pool" exists in these soils and may turn over primarily as a result of soil disruption.

  16. The California experience : lessons learned and prospects for the future

    Energy Technology Data Exchange (ETDEWEB)

    Levin, J. [AC Transit, Oakland, CA (United States)

    2007-07-01

    AC Transit operates 650 hydrogen-powered mass transit buses that serve 1.5 million people in 13 cities in California. This presentation discussed the impact of the buses on public health, quality of life and cost savings. Hydrogen has been touted as a diversified and renewable energy supply that can provide energy independence and reduction in global warming. Mass transit systems have proven to be well suited for testing the limits of hydrogen-powered vehicles primarily because of the centralized fueling and maintenance structure. AC Transit began ZEbus testing in November 1999 and became involved in the California Fuel Cell Partnership in 2000. The NeBus test was performed in 2000, followed by the ISE/UTC Thor Bus in 2003/2004. The governor's inauguration of the zero emission buses was in January 2007. The lessons learned from the California experience were: (1) motivation must be for the right reason, (2) a champion is required, (3) community and political support is required, (4) capital investment is required, (5) a strong management team is required, (6) partners must be chosen wisely, (7) the end user or customer must be allowed to drive the design, (8) inform the public about plans, (9) evaluation is essential to industry-wide application, (10) all resources must be considered for outreach and education, (11) optimism is required to surpass challenges, (12) the technology should be promoted for future generations. The presentation concluded with comments on market value of hydrogen and fuel cell vehicles, their fuel efficiency, reliability and durability. tabs., figs.

  17. WATCHING GRASS GROW- A PILOT STUDY ON THE SUITABILITY OF PHOTOGRAMMETRIC TECHNIQUES FOR QUANTIFYING CHANGE IN ABOVEGROUND BIOMASS IN GRASSLAND EXPERIMENTS

    Directory of Open Access Journals (Sweden)

    M. Kröhnert

    2018-05-01

    Full Text Available Grassland ecology experiments in remote locations requiring quantitative analysis of the biomass in defined plots are becoming increasingly widespread, but are still limited by manual sampling methodologies. To provide a cost-effective automated solution for biomass determination, several photogrammetric techniques are examined to generate 3D point cloud representations of plots as a basis, to estimate aboveground biomass on grassland plots, which is a key ecosystem variable used in many experiments. Methods investigated include Structure from Motion (SfM techniques for camera pose estimation with posterior dense matching as well as the usage of a Time of Flight (TOF 3D camera, a laser light sheet triangulation system and a coded light projection system. In this context, plants of small scales (herbage and medium scales are observed. In the first pilot study presented here, the best results are obtained by applying dense matching after SfM, ideal for integration into distributed experiment networks.

  18. Successive sheep grazing reduces population density of Brandt's voles in steppe grassland by altering food resources: a large manipulative experiment.

    Science.gov (United States)

    Li, Guoliang; Yin, Baofa; Wan, Xinrong; Wei, Wanhong; Wang, Guiming; Krebs, Charles J; Zhang, Zhibin

    2016-01-01

    Livestock grazing has shaped grassland ecosystems around the world. Previous studies indicated grazing showed various impacts on small rodents; however, most studies were conducted over 1-2 years without controlling for confounding factors such as immigration/emigration and predation in rodents. Brandt's voles (Lasiopodomys brandtii) are generally recognized as pests because of food overlap with domestic herbivores, but are also important for biodiversity conservation because they provide nests or food to many birds. Fully understanding the ecological relationship between domestic herbivores and small mammals is essential to making ecosystem management decisions. To address these needs, we carried out a field experiment during the period 2010-2013 to assess the effects of sheep grazing on vegetation and the population density of Brandt's voles along a gradient of three grazing intensities by using 12 large-scale enclosures. Responses of Brandt's voles to livestock grazing varied with grazing intensity and year. As compared to the control group, sheep grazing had no effect on vole abundance in the first year but an overall negative effect on vole abundance in the following 3 years. Successive grazing caused decreases in survival and male body mass of voles, but had no significant effect on fecundity. Negative effects of grazing were associated with a grazing-induced deterioration in both food quantity (reflected by biomass and cover of less-preferred plants), and food quality (measured by tannin and total phenol content). Our findings highlight the urgent need for more flexible management of yearly rotational grazing to optimize livestock production while maintaining species diversity and ecosystem health.

  19. Dynamics of ammonia exchange with cut grassland: synthesis of results and conclusions of the GRAMINAE Integrated Experiment

    Directory of Open Access Journals (Sweden)

    M. A. Sutton

    2009-12-01

    Full Text Available Improved data on biosphere-atmosphere exchange are fundamental to understanding the production and fate of ammonia (NH3 in the atmosphere. The GRAMINAE Integrated Experiment combined novel measurement and modelling approaches to provide the most comprehensive analysis of the interactions to date. Major inter-comparisons of micrometeorological parameters and NH3 flux measurements using the aerodynamic gradient method and relaxed eddy accumulation (REA were conducted. These showed close agreement, though the REA systems proved insufficiently precise to investigate vertical flux divergence. Grassland management had a large effect on fluxes: emissions increased after grass cutting (−50 to 700 ng m−2 s−1 NH3 and after N-fertilization (0 to 3800 ng m−2 s−1 compared with before the cut (−60 to 40 ng m−2 s−1.

    Effects of advection and air chemistry were investigated using horizontal NH3 profiles, acid gas and particle flux measurements. Inverse modelling of NH3 emission from an experimental farm agreed closely with inventory estimates, while advection errors were used to correct measured grassland fluxes. Advection effects were caused both by the farm and by emissions from the field, with an inverse dispersion-deposition model providing a reliable new approach to estimate net NH3 fluxes. Effects of aerosol chemistry on net NH3 fluxes were small, while the measurements allowed NH3-induced particle growth rates to be calculated and aerosol fluxes to be corrected.

    Bioassays estimated the emission potential Γ = [NH4+]/[H+] for different plant pools, with the apoplast having the smallest values (30–1000. The main within-canopy sources of NH3 emission appeared to be leaf litter and the soil surface, with Γ up to 3 million and

  20. Past tree influence and prescribed fire mediate biotic interactions and community reassembly in a grassland-restoration experiment

    Science.gov (United States)

    Charles B. Halpern; Joseph A. Antos; Donald McKenzie; Annette M. Olson; Lara Souza

    2016-01-01

    1. Woody plant encroachment of grasslands is occurring globally, with profound ecological consequences. Attempts to restore herbaceous dominance may fail if the woody state is resilient or if intervention leads to an alternate, undesirable state. Restoration outcomes often hinge on biotic interactions – particularly on priority effects that inhibit or promote community...

  1. Using wildfires as a natural experiment to evaluate the effect of fire on southern California vernal pool plant communities

    Directory of Open Access Journals (Sweden)

    Charles H. Black

    2016-07-01

    Full Text Available Fires in Mediterranean-type ecosystems (MTEs have been studied widely with emphasis on shrub and grassland vegetation types. Although vernal pools comprise a very small fraction of MTEs, they are important to regional biodiversity due to high local endemism. Fire frequency has been increasing in MTEs and while altered fire regimes have been shown to threaten native shrub communities, their effect on vernal pools is uncertain. Due to the number of at-risk species in this habitat, experiments with potentially harmful effects are problematic. Therefore, we initiated this study to take advantage of two anthropogenic but unplanned fire events. The analysis uses data collected from 2001 to 2009 on a site burned in 2000 and 2003. We analyzed the data in an exploratory framework and applied unadjusted and adjusted models using different parameterizations of the exposure variables. The results did not provide evidence that fire reduced the abundance of native vernal pool species in southern California. There is provisional evidence of a positive but temporary effect of fire on native vernal pool species. Our analysis demonstrates an exploratory analytical approach for use with problematic data sets that can arise when conservation objectives constrain opportunities for experimental studies.

  2. Grazing damage to plants and gastropod and grasshopper densities in a CO 2-enrichment experiment on calcareous grassland

    Science.gov (United States)

    Ledergerber, Stephan; Thommen, G. Heinrich; Baur, Bruno

    Plant-herbivore interactions may change as atmospheric CO 2 concentrations continue to rise. We examined the effects of elevated atmospheric CO 2 and CO 2-exposure chambers on the grazing damage to plants, and on the abundances of potential herbivores (terrestrial gastropods and grasshoppers) in a calcareous grassland in the Jura mountains of Switzerland (village of Nenzlingen). Individuals of most plant species examined showed slight grazing damage. However, plots with CO 2 enrichment and plots with ambient atmosphere did not differ in the extent of grazing damage. Similarly, plots with CO 2 enrichment and plots with ambient atmosphere did not differ in either gastropod or grasshopper density. Experimental plots with and without chambers did not differ in the number of gastropods. However, the densities of gastropods and grasshoppers and extent of grazing damage to plants were generally lower in the experimental area than in the grassland outside the experimental field.

  3. Imprint of oaks on nitrogen availability and δ15N in California grassland-savanna: A case of enhanced N inputs?

    Science.gov (United States)

    Perakis, S.S.; Kellogg, C.H.

    2007-01-01

    Woody vegetation is distributed patchily in many arid and semi-arid ecosystems, where it is often associated with elevated nitrogen (N) pools and availability in islands of fertility. We measured N availability and δ15N in paired blue-oak versus annual grass dominated patches to characterize the causes and consequences of spatial variation in N dynamics of grassland-savanna in Sequoia-Kings Canyon National Park. We found significantly greater surface soil N pools (0–20 cm) in oak patches compared to adjacent grass areas across a 700 m elevation gradient from foothills to the savanna-forest boundary. N accumulation under oaks was associated with a 0.6‰ depletion in soil δ15N relative to grass patches. Results from a simple δ15N mass balance simulation model, constrained by surface soil N and δ15N measured in the field, suggest that the development of islands of N fertility under oaks can be traced primarily to enhanced N inputs. Net N mineralization and percent nitrification in laboratory incubations were consistently higher under oaks across a range of experimental soil moisture regimes, suggesting a scenario whereby greater N inputs to oak patches result in net N accumulation and enhanced N cycling, with a potential for greater nitrate loss as well. N concentrations of three common herbaceous annual plants were nearly 50% greater under oak than in adjacent grass patches, with community composition shifted towards more N-demanding species under oaks. We find that oaks imprint distinct N-rich islands of fertility that foster local feedback between soil N cycling, plant N uptake, and herbaceous community composition. Such patch-scale differences in N inputs and plant–soil interactions increase biogeochemical heterogeneity in grassland-savanna ecosystems and may shape watershed-level responses to chronic N deposition.

  4. The Lived Experiences of Asian Americans Who Became Chief Executive Officers (CEOs) of California Community Colleges

    Science.gov (United States)

    Ramones, Eric

    2017-01-01

    The purpose of this phenomenological study was to explore the lived experiences of Asian Americans who became chief executive officers (CEOs) of a California Community College District. This study discussed the experiences, the influence of Asian culture, the perception of Asian Americans, and the challenges encountered by Asian American CEOs. To…

  5. Protecting Student Press Freedom by State Law: The Experience in California.

    Science.gov (United States)

    Overbeck, Wayne

    Following "Tinker vs. Des Moines Community School District," the United States Supreme Court decision that assured First Amendment rights to secondary school students and teachers, California began experimenting with statutory guarantees of free expression for students at the high school and community college levels. Decisions issued by…

  6. Managing electrical demand through difficult periods: California's experience with demand response

    International Nuclear Information System (INIS)

    Wikler, G.; Ghosh, D.Ph.D.

    2010-01-01

    This paper provides a brief overview of California's electricity situation and the relevance of Demand Response (DR) in addressing some of the challenges faced by the State's electricity system. It then discusses California's experience with DR, market rules that influence what role DR plays and attempts to integrate wholesale-retail level program offerings in the State, and some of the key drivers that are likely to enhance the role of DR. Lastly, the paper identifies some of the key challenges facing implementers of DR programs and discusses how many of those challenges could potentially be overcome. (authors)

  7. Management experiences and trends for water reuse implementation in Northern California.

    Science.gov (United States)

    Bischel, Heather N; Simon, Gregory L; Frisby, Tammy M; Luthy, Richard G

    2012-01-03

    In 2010, California fell nearly 300,000 acre-ft per year (AFY) short of its goal to recycle 1,000,000 AFY of municipal wastewater. Growth of recycled water in the 48 Northern California counties represented only 20% of the statewide increase in reuse between 2001 and 2009. To evaluate these trends and experiences, major drivers and challenges that influenced the implementation of recycled water programs in Northern California are presented based on a survey of 71 program managers conducted in 2010. Regulatory requirements limiting discharge, cited by 65% of respondents as a driver for program implementation, historically played an important role in motivating many water reuse programs in the region. More recently, pressures from limited water supplies and needs for system reliability are prevalent drivers. Almost half of respondents (49%) cited ecological protection or enhancement goals as drivers for implementation. However, water reuse for direct benefit of natural systems and wildlife habitat represents just 6-7% of total recycling in Northern California and few financial incentives exist for such projects. Economic challenges are the greatest barrier to successful project implementation. In particular, high costs of distribution systems (pipelines) are especially challenging, with $1 to 3 million/mile costs experienced. Negative perceptions of water reuse were cited by only 26% of respondents as major hindrances to implementation of surveyed programs.

  8. Voluntary intake and in vivo digestibility of forages from semi-natural grasslands in dairy cows

    NARCIS (Netherlands)

    Bruinenberg, M.H.; Valk, H.; Struik, P.C.

    2003-01-01

    To study in vivo digestibility of forages from semi-natural grasslands two experiments were carried out. In the first experiment lactating dairy cows were offered three different silage-based diets. Silage originated from intensively managed grassland (IM), extensively managed species-poor grassland

  9. Soil fertilization leads to a decline in between-samples variability of microbial community δ13C profiles in a grassland fertilization experiment.

    Directory of Open Access Journals (Sweden)

    Stavros D Veresoglou

    Full Text Available Gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS was used to measure the (13C/(12C ratios of PLFAs at natural abundance levels from a temperate grassland nitrogen (N and phosphorus (P factorial fertilization experiment in northern Greece. In each plot two rhizosphere samples were derived centred around individual Agrostis capillaris and Prunella vulgaris plants. It was hypothesized that the isotopic signal of microbes that preferentially feed on recalcitrant litter such as fungi would be modified by fertilization more strongly than that of opportunistic microbes using labile C. Microbial community δ(13C was affected by both P and N fertilization regime and plant species identity. However, we have been unable to detect significant nutrient effects on individual groups of microbes when analyzed separately in contrast to our original hypothesis. Intra-treatment variability, as evaluated from Hartley's F(max tests in the five first PCA components axes as well as the size of the convex hulls in PCA scoreplots and Mahalanobis distances, was considerably higher in the non-fertilized controls. Moreover, a significant relationship was established between the change in PLFA abundances and their respective changes in δ(13C for the aggregate of samples and those simultaneously fertilized with N and P. We conclude that use of compound specific isotope analysis in the absence of labelling represents a valuable and overlooked tool in obtaining an insight of microbial community functioning.

  10. Effects of plant diversity, N fertilization, and elevated carbon dioxide on grassland soil N cycling in a long-term experiment.

    Science.gov (United States)

    Mueller, Kevin E; Hobbie, Sarah E; Tilman, David; Reich, Peter B

    2013-04-01

    The effects of global environmental changes on soil nitrogen (N) pools and fluxes have consequences for ecosystem functions such as plant productivity and N retention. In a 13-year grassland experiment, we evaluated how elevated atmospheric carbon dioxide (CO2 ), N fertilization, and plant species richness alter soil N cycling. We focused on soil inorganic N pools, including ammonium and nitrate, and two N fluxes, net N mineralization and net nitrification. In contrast with existing hypotheses, such as progressive N limitation, and with observations from other, often shorter, studies, elevated CO2 had relatively static and small, or insignificant, effects on soil inorganic N pools and fluxes. Nitrogen fertilization had inconsistent effects on soil N transformations, but increased soil nitrate and ammonium concentrations. Plant species richness had increasingly positive effects on soil N transformations over time, likely because in diverse subplots the concentrations of N in roots increased over time. Species richness also had increasingly positive effects on concentrations of ammonium in soil, perhaps because more carbon accumulated in soils of diverse subplots, providing exchange sites for ammonium. By contrast, subplots planted with 16 species had lower soil nitrate concentrations than less diverse subplots, especially when fertilized, probably due to greater N uptake capacity of subplots with 16 species. Monocultures of different plant functional types had distinct effects on N transformations and nitrate concentrations, such that not all monocultures differed from diverse subplots in the same manner. The first few years of data would not have adequately forecast the effects of N fertilization and diversity on soil N cycling in later years; therefore, the dearth of long-term manipulations of plant species richness and N inputs is a hindrance to forecasting the state of the soil N cycle and ecosystem functions in extant plant communities. © 2012 Blackwell

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

    NARCIS (Netherlands)

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

    2004-01-01

    Chronic effects of ozone on wet grassland species early in the growing season might be altered by interspecific competition. Individual plants of Holcus lanatus, Lychnis flos-cuculi, Molinia caerulea and Plantago lanceolata were grown in monocultures and in mixed cultures with Agrostis capillaris.

  12. Distinguishing Intensity Levels of Grassland Fertilization Using Vegetation Indices

    Directory of Open Access Journals (Sweden)

    Jens L. Hollberg

    2017-01-01

    Full Text Available Monitoring the reaction of grassland canopies on fertilizer application is of major importance to enable a well-adjusted management supporting a sustainable production of the grass crop. Up to date, grassland managers estimate the nutrient status and growth dynamics of grasslands by costly and time-consuming field surveys, which only provide low temporal and spatial data density. Grassland mapping using remotely-sensed Vegetation Indices (VIs has the potential to contribute to solving these problems. In this study, we explored the potential of VIs for distinguishing five differently-fertilized grassland communities. Therefore, we collected spectral signatures of these communities in a long-term fertilization experiment (since 1941 in Germany throughout the growing seasons 2012–2014. Fifteen VIs were calculated and their seasonal developments investigated. Welch tests revealed that the accuracy of VIs for distinguishing these grassland communities varies throughout the growing season. Thus, the selection of the most promising single VI for grassland mapping was dependent on the date of the spectra acquisition. A random forests classification using all calculated VIs reduced variations in classification accuracy within the growing season and provided a higher overall precision of classification. Thus, we recommend a careful selection of VIs for grassland mapping or the utilization of temporally-stable methods, i.e., including a set of VIs in the random forests algorithm.

  13. The community ecology of barley/cereal yellow dwarf viruses in Western US grasslands.

    Science.gov (United States)

    Power, Alison G; Borer, Elizabeth T; Hosseini, Parviez; Mitchell, Charles E; Seabloom, Eric W

    2011-08-01

    Research on plant viruses in natural ecosystems has been increasing rapidly over the past decade. This paper reviews recent research on the barley and cereal yellow dwarf viruses (B/CYDVs) in grasslands of the western US, beginning with the evidence that the disease caused by these viruses facilitated the invasion of western US grasslands by European annual grasses. Observational and experimental studies of B/CYDVs were carried out along a latitudinal gradient (33.8-48.8°N) from southern California to southern Canada. The prevalence and community composition of B/CYDVs were assessed over a variety of scales and under a range of biotic and abiotic conditions. The findings indicate that both biotic and abiotic factors are important influences on virus ecology and epidemiology. Introduced annual grasses are high-quality hosts that amplify both virus and vector populations in this system, but our research suggests that endemic perennial grasses are critically important for sustaining virus populations in contemporary grasslands largely composed of introduced species. Experiments indicated that increased phosphorus supply to hosts resulted in greater host biomass and higher virus prevalence. Using experimental exclosures, it was found that the presence of grazing vertebrate herbivores increased the abundance of annual grasses, resulting in increased virus prevalence. The results of these studies suggest that patterns of B/CYDV prevalence and coinfection in western US grasslands are strongly shaped by the interactions of host plants, vectors, vertebrate herbivores, and abiotic drivers including nutrients. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. Public Outreach and Educational Experiences in Mexico and Latin American communities in California

    Science.gov (United States)

    Andres De Leo-Winkler, Mario; Canalizo, Gabriela; Pichardo, Barbara; Arias, Brenda

    2015-08-01

    I have created and applied diverse methods in public outreach at National Autonomous Univerisity of Mexico (UNAM) since 2001.A student-led volunteer astronomical club has been created, the biggest in Mexico. We serve over 10,000 people per year. We have created public outreach activities for the general audience: archeo-astronomical outings, scientific movie debates, conferences, courses, public telescope viewings. We have also worked with juvenile delinquents to offer them scientific opportunities when released from jail.I've also created and worked the social media for the Institute of Astronomy UNAM, which is currently the biggest social media site on astronomy in Spanish in the world. I've created and organized a mass photo exhibition (over 1 million people served) for the Institute of Astronomy, UNAM which was citizen-funded through an online platform, the first of its kind in the country. Together with my colleages, we created workshops on astronomy for children with the Mexican's government funding.I've participated in several radio and television programs/capsules designed to bring astronomy to the general audience, one in particular ("Astrophysics for Dummies") was very successful in nation-wide Mexican radio.I am currently applying all experiences to develop a new public outreach project on astronomy for the University of California - Riverside and its on-campus and surrounding Latin American communities. We are offering new workshops for blind and deaf children. We want to integrate the Latino community to our outreach activities and offer science in their language in a simple and entertaining fashion. We have also successfully applied astrophotography as a course which brings social-science and arts undergraduate students into natural sciences.Sharing experiences, success and failure stories will help new and experienced educators and public outreach professionals learn and better from past experiences.

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

    Science.gov (United States)

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

    2018-04-01

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

  16. Grassland biodiversity can pay.

    Science.gov (United States)

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

    2018-04-10

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

  17. How will land use affect air temperature in the surface boundary layer? Lessons learned from a comparative study on the energy balance of an oak savanna and annual grassland in California, USA

    Directory of Open Access Journals (Sweden)

    Dennis Baldocchi

    2013-06-01

    Full Text Available We investigated the effect of land use on differences in air temperature. We based our analysis on a decade of weather and energy flux measurements, collected over two contrasting landscapes, an oak savanna and an annual grassland, growing under the same climate conditions. Over the decade, the daily-averaged, potential air temperature above the aerodynamically rougher and optically darker oak savanna was 0.5°C warmer than that above the aerodynamically smoother and optically brighter annual grassland. However, air temperature differences were seasonal. Smallest differences in potential air temperature occurred towards the end of spring, when much of the soil moisture reservoir was depleted. Largest differences in potential air temperature occurred during the winter rain season when the grass was green and transpiring and when the trees were senescent or deciduous. To understand the effect of land use on the local climate, we examined the concomitant changes in net radiation, sensible and latent heat exchange, the aerodynamic roughness (R a, the surface resistance to water transfer (R s, aerodynamic surface temperature and the growth of the planetary boundary layer, with measurements and model computations. Overall, these biophysical variables provide us with mechanistic information to diagnose and predict how changes in air temperature will follow changes in land use or management. In conclusion, land use change is responsible for having a marked impact on the local climate of a region. At the local level, the change in the surface energy balance, towards a darker and rougher surface, will produce an additive increment to climate warming induced by a greater greenhouse gas burden in the atmosphere.

  18. Particle size reduction in debris flows: Laboratory experiments compared with field data from Inyo Creek, California

    Science.gov (United States)

    Arabnia, O.; Sklar, L. S.; Mclaughlin, M. K.

    2014-12-01

    Rock particles in debris flows are reduced in size through abrasion and fracture. Wear of coarse sediments results in production of finer particles, which alter the bulk material rheology and influence flow dynamics and runout distance. Particle wear also affects the size distribution of coarse particles, transforming the initial sediment size distribution produced on hillslopes into that delivered to the fluvial channel network. A better understanding of the controls on particle wear in debris flows would aid in the inferring flow conditions from debris flow deposits, in estimating the initial size of sediments entrained in the flow, and in modeling debris flow dynamics and mapping hazards. The rate of particle size reduction with distance traveled should depend on the intensity of particle interactions with other particles and the flow boundary, and on rock resistance to wear. We seek a geomorphic transport law to predict rate of particle wear with debris flow travel distance as a function of particle size distribution, flow depth, channel slope, fluid composition and rock strength. Here we use four rotating drums to create laboratory debris flows across a range of scales. Drum diameters range from 0.2 to 4.0 m, with the largest drum able to accommodate up to 2 Mg of material, including boulders. Each drum has vanes along the boundary to prevent sliding. Initial experiments use angular clasts of durable granodiorite; later experiments will use less resistant rock types. Shear rate is varied by changing drum rotational velocity. We begin experiments with well-sorted coarse particle size distributions, which are allowed to evolve through particle wear. The fluid is initially clear water, which rapidly acquires fine-grained wear products. After each travel increment all coarse particles (mass > 0.4 g) are weighed individually. We quantify particle wear rates using statistics of size and mass distributions, and by fitting various comminution functions to the data

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

    Science.gov (United States)

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

    2004-09-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-09-01

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

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

    International Nuclear Information System (INIS)

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

    2004-01-01

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

  2. Deregulation and natural gas trade relationships: lessons from the Alberta-California experience

    International Nuclear Information System (INIS)

    Wilson, Patrick Impero

    1997-01-01

    In 1978 the US government moved to deregulate the American natural gas industry. The market changes that resulted from this initial step took time to ripple their way out to regional and subnational gas trading relationships. This ripple effect required subnational governments (state and provincial regulators) to rethink their gas regulatory policies. This article examines the restructuring of the Alberta-California gas trade. It explores how changes in US policy forced California and Alberta regulators to recast their policies. It concludes with several lessons that can be drawn from this case about the complex challenge of restructuring international gas trading relationships. (author)

  3. Tests were inconclusive: California's experiment with ACOs raises questions about whether they'll save money.

    Science.gov (United States)

    Vesely, Rebecca

    2010-11-01

    In California, many providers have been working in accountable care organizations for decades, and they say they can work well. "It's not the type of organization that defines the success of an ACO, it's the leadership," said Tom Williams, executive director of the Oakland, Calif.-based Integrated Healthcare Association. "For success, there needs to be alignment between hospitals and physicians."

  4. Root biomass and carbon storage in differently managed multispecies temporary grasslands

    DEFF Research Database (Denmark)

    Eriksen, Jørgen; Mortensen, Tine Bloch; Søegaard, Karen

    2012-01-01

    Species-rich grasslands may potentially increase carbon (C) storage in soil, and an experiment was established to investigate C storage in highly productive temporary multi-species grasslands. Plots were established with three mixtures: (1) a herb mixture containing salad burnet (Sanguisorba minor...

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

    Directory of Open Access Journals (Sweden)

    Fengge Zhang

    2018-04-01

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

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

    Science.gov (United States)

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

    2018-01-01

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

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

    Science.gov (United States)

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

    2014-11-01

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

  8. Species interactions reverse grassland responses to changing climate.

    Science.gov (United States)

    Suttle, K B; Thomsen, Meredith A; Power, Mary E

    2007-02-02

    Predictions of ecological response to climate change are based largely on direct climatic effects on species. We show that, in a California grassland, species interactions strongly influence responses to changing climate, overturning direct climatic effects within 5 years. We manipulated the seasonality and intensity of rainfall over large, replicate plots in accordance with projections of leading climate models and examined responses across several trophic levels. Changes in seasonal water availability had pronounced effects on individual species, but as precipitation regimes were sustained across years, feedbacks and species interactions overrode autecological responses to water and reversed community trajectories. Conditions that sharply increased production and diversity through 2 years caused simplification of the food web and deep reductions in consumer abundance after 5 years. Changes in these natural grassland communities suggest a prominent role for species interactions in ecosystem response to climate change.

  9. Does Evapotranspiration Increase When Forests are converted to Grasslands?

    Science.gov (United States)

    Varcoe, Robert; Sterling, Shannon

    2017-04-01

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

  10. Quitline utilization rates of African-American and white smokers: the California experience.

    Science.gov (United States)

    Zhu, Shu-Hong; Gardiner, Phillip; Cummins, Sharon; Anderson, Christopher; Wong, Shiushing; Cowling, David; Gamst, Anthony

    2011-01-01

    To compare the utilization rate of a statewide tobacco quitline by African-American smokers to that of white smokers. Observational study of 18 years of state quitline operation in California. Subjects were 61,096 African-American and 279,042 white smokers who called the quitline from August 1992 to December 2009. Data from six California Tobacco Surveys, 1993, 1996, 1999, 2002, 2005, and 2008 were also used. Callers' answers to the question how they heard about the quitline were grouped into four categories: media, health care providers, friends/family, and others. The averaged annual quitline call volume for each ethnic group was divided by the total number of smokers in that group, based on California Tobacco Surveys, to produce the annual quitline utilization rate. In five out of six periods of comparison, African-American smokers had a higher annual utilization rate than white smokers. The odds ratios [ORs] ranged from 1.44 to 2.40 (all p smokers were significantly more likely to call the state quitline than white smokers were. Promoting the quitline as part of antismoking media campaigns can help reduce disparity in cessation service utilization.

  11. Protecting Mongolia's grassland steppes | CRDI - Centre de ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    ... windy grassland region is severely damaged, desertification can quickly set in. ... to marketing to the sound use of (grassland) resources," explains Ykhanbai, who ... is going to require improvement in the skills of researchers, adds Ykhanbai.

  12. Challenges with controlling varicella in prison settings: Experience of California, 2010–2011

    OpenAIRE

    Leung, Jessica; Lopez, Adriana S.; Tootell, Elena; Baumrind, Nikki; Mohle-Boetani, Janet; Leistikow, Bruce; Harriman, Kathleen H.; Preas, Christopher P.; Cosentino, Giorgio; Bialek, Stephanie R.; Marin, Mona

    2014-01-01

    We describe the epidemiology of varicella in one state prison in California during 2010–2011, control measures implemented, and associated costs. Eleven varicella cases were reported, 9 associated with 2 outbreaks. One outbreak consisted of 3 cases and the second consisted of 6 cases with 2 generations of spread. Among exposed inmates serologically tested, 98% (643/656) were VZV sero-positive. The outbreaks resulted in >1,000 inmates exposed, 444 staff exposures, and >$160,000 in costs. We do...

  13. Appreciation of grassland functions by European stakeholders

    NARCIS (Netherlands)

    Pol, van den A.; Golinski, P.; Hennessy, D.; Huyghe, C.; Parente, G.; Peyraud, J.L.

    2014-01-01

    In order to promote sustainable and competitive ruminant production systems, the European Multisward project was aimed at improving farmer trust in grassland and grassland mixtures. A questionnaire on grassland functions was submitted in eight languages, in order to better understand the importance

  14. Incorporating grassland management in a global vegetation model

    Science.gov (United States)

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

    2013-04-01

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

  15. Environmental Assessment for the proposed Induction Linac System Experiments in Building 51B at Lawrence Berkeley National Laboratory, Berkeley, California

    International Nuclear Information System (INIS)

    1995-08-01

    The US Department of Energy (DOE) has prepared an Environmental Assessment (EA), (DOE/EA-1087) evaluating the proposed action to modify existing Building 51B at Lawrence Berkeley National Laboratory (LBNL) to install and conduct experiments on a new Induction Linear Accelerator System. LBNL is located in Berkeley, California and operated by the University of California (UC). The project consists of placing a pre-fabricated building inside Building 51B to house a new 10 MeV heavy ion linear accelerator. A control room and other support areas would be provided within and directly adjacent to Building 51B. The accelerator system would be used to conduct tests, at reduced scale and cost, many features of a heavy-ion accelerator driver for the Department of Energy's inertial fusion energy program. Based upon information and analyses in the EA, the DOE has determined that the proposed action is not a major Federal action significantly affecting the quality of the human environment within the meaning of the National Environmental Policy Act of 1969. Therefore, an Environmental Impact Statement is not required. This report contains the Environmental Assessment, as well as the Finding of No Significant Impact (FONSI)

  16. The California ISO experience with price spikes and search for remedies

    Energy Technology Data Exchange (ETDEWEB)

    Barkovich, B. R. [Barkovich and Yap, Inc., San Francisco, CA (United States)

    2000-07-01

    An overview of the conditions under which price spikes have occurred in California, and the attempts to eliminate those conditions are discussed. Several periods of price spikes have occurred since the competitive electricity market became a reality in California, usually at times of high system load.. Price spikes in the ancillary services (A/S) (one of the two markets run by the California Independent System Operator (CAISO), the other being balancing or real-time energy), occurred when the supply of competitive bids has been restricted either by bid insufficiency or gaming. Bid insufficiency is the failure of the market to produce enough bids for a particular product. Gaming is defined as taking advantage of an occasion when there is likely to be short supply due to transmission constraints or geographical distribution of generation and using the occasion to maximize prices. The key tool used by the CAISO to reduce price spikes has been to reduce and adjust procurement of A/S by instituting additional enforcement of market participants' ability to meet their requirements to provide A/S on command. If they fail to do so, they do not receive payment for capacity that has been bid, with the bids accepted, but not provided. Changes in the scheduling system to facilitate inter-Scheduling Coordinator trades of A/S obligations, designed to reduce procurement through the CAISO markets and thus potentially lower market clearing prices for A/S in those markets, has been another technique used. The institution of 'Rational Buyer' has been yet another, and more substantial, means used to reduce price spikes. This mechanism, involving demand substitution across the markets for A/S, has the effect of defeating attempts by a generator to place a high-priced bid in a generally lower value market in the expectation of a smaller number of bids in that market. Significant decline in the amount of A/S procured, and a significant decline in the ratio of the total cost

  17. The California ISO experience with price spikes and search for remedies

    International Nuclear Information System (INIS)

    Barkovich, B. R.

    2000-01-01

    An overview of the conditions under which price spikes have occurred in California, and the attempts to eliminate those conditions are discussed. Several periods of price spikes have occurred since the competitive electricity market became a reality in California, usually at times of high system load.. Price spikes in the ancillary services (A/S) (one of the two markets run by the California Independent System Operator (CAISO), the other being balancing or real-time energy), occurred when the supply of competitive bids has been restricted either by bid insufficiency or gaming. Bid insufficiency is the failure of the market to produce enough bids for a particular product. Gaming is defined as taking advantage of an occasion when there is likely to be short supply due to transmission constraints or geographical distribution of generation and using the occasion to maximize prices. The key tool used by the CAISO to reduce price spikes has been to reduce and adjust procurement of A/S by instituting additional enforcement of market participants' ability to meet their requirements to provide A/S on command. If they fail to do so, they do not receive payment for capacity that has been bid, with the bids accepted, but not provided. Changes in the scheduling system to facilitate inter-Scheduling Coordinator trades of A/S obligations, designed to reduce procurement through the CAISO markets and thus potentially lower market clearing prices for A/S in those markets, has been another technique used. The institution of 'Rational Buyer' has been yet another, and more substantial, means used to reduce price spikes. This mechanism, involving demand substitution across the markets for A/S, has the effect of defeating attempts by a generator to place a high-priced bid in a generally lower value market in the expectation of a smaller number of bids in that market. Significant decline in the amount of A/S procured, and a significant decline in the ratio of the total cost of A

  18. Challenges with controlling varicella in prison settings: experience of California, 2010 to 2011.

    Science.gov (United States)

    Leung, Jessica; Lopez, Adriana S; Tootell, Elena; Baumrind, Nikki; Mohle-Boetani, Janet; Leistikow, Bruce; Harriman, Kathleen H; Preas, Christopher P; Cosentino, Giorgio; Bialek, Stephanie R; Marin, Mona

    2014-10-01

    This article describes the epidemiology of varicella in one state prison in California during 2010 and 2011, control measures implemented, and associated costs. Eleven varicella cases were reported, of which nine were associated with two outbreaks. One outbreak consisted of three cases and the second consisted of six cases with two generations of spread. Among exposed inmates serologically tested, 98% (643/656) were varicella-zoster virus seropositive. The outbreaks resulted in > 1,000 inmates exposed, 444 staff exposures, and > $160,000 in costs. The authors documented the challenges and costs associated with controlling and managing varicella in a prison setting. A screening policy for evidence of varicella immunity for incoming inmates and staff and vaccination of susceptible persons has the potential to mitigate the impact of future outbreaks and reduce resources necessary to manage cases and outbreaks. © The Author(s) 2014.

  19. Challenges with controlling varicella in prison settings: Experience of California, 2010–2011

    Science.gov (United States)

    Leung, Jessica; Lopez, Adriana S.; Tootell, Elena; Baumrind, Nikki; Mohle-Boetani, Janet; Leistikow, Bruce; Harriman, Kathleen H.; Preas, Christopher P.; Cosentino, Giorgio; Bialek, Stephanie R.; Marin, Mona

    2015-01-01

    We describe the epidemiology of varicella in one state prison in California during 2010–2011, control measures implemented, and associated costs. Eleven varicella cases were reported, 9 associated with 2 outbreaks. One outbreak consisted of 3 cases and the second consisted of 6 cases with 2 generations of spread. Among exposed inmates serologically tested, 98% (643/656) were VZV sero-positive. The outbreaks resulted in >1,000 inmates exposed, 444 staff exposures, and >$160,000 in costs. We documented the challenges and costs associated with controlling and managing varicella in a prison setting. A screening policy for evidence of varicella immunity for incoming inmates and staff and vaccination of susceptible persons has the potential to mitigate the impact of future outbreaks and reduce resources necessary for managing cases and outbreaks. PMID:25201912

  20. Monitoring in South African grasslands

    CSIR Research Space (South Africa)

    Mentis, MT

    1984-12-01

    Full Text Available The main purpose of this document is to propose how ecological monitoring might be developed in the Grassland Biome of South Africa. Monitoring is defined as the maintenance of regular surveillance to test the null hypothesis of no change...

  1. The fluorescent tracer experiment on Holiday Beach near Mugu Canyon, Southern California

    Science.gov (United States)

    Kinsman, Nicole; Xu, J. P.

    2012-01-01

    After revisiting sand tracer techniques originally developed in the 1960s, a range of fluorescent coating formulations were tested in the laboratory. Explicit steps are presented for the preparation of the formulation evaluated to have superior attributes, a thermoplastic pigment/dye in a colloidal mixture with a vinyl chloride/vinyl acetate copolymer. In September 2010, 0.59 cubic meters of fluorescent tracer material was injected into the littoral zone about 4 kilometers upcoast of Mugu submarine canyon in California. The movement of tracer was monitored in three dimensions over the course of 4 days using manual and automated techniques. Detailed observations of the tracer's behavior in the coastal zone indicate that this tracer successfully mimicked the native beach sand and similar methods could be used to validate models of tracer movement in this type of environment. Recommendations including how to time successful tracer studies and how to scale the field of view of automated camera systems are presented along with the advantages and disadvantages of the described tracer methodology.

  2. Proficiency testing materials for pH and blood gases. The California Thoracic Society experience.

    Science.gov (United States)

    Hansen, J E; Clausen, J L; Levy, S E; Mohler, J G; Van Kessel, A L

    1986-02-01

    The California Thoracic Society Blood Gas Proficiency Testing Program distributed ampules from three separate lots of quality control products every three months as unknowns to participating clinical (survey) laboratories and ten selected reference laboratories. For eight quarters, aqueous buffers were distributed. For each lot, PCO2 and pH measurements varied within narrow ranges between laboratories. Concurrently, the PO2 measurements varied widely between reference laboratories as well as survey laboratories, but varied minimally when repeatedly assessed on each reference laboratory machine. Change to a fluorocarbon-containing emulsion as a testing medium resulted in a significant reduction in within model and overall variability for PO2. We attribute this reduction in variability to the higher O2 content and decreased temperature sensitivity for PO2 of the fluorocarbon-containing emulsion. Because we have no evidence that the magnitude of the interinstrument differences in PO2 found with these materials would be found with fresh human blood we recommend that regulatory agencies use the results of proficiency testing for PO2 cautiously.

  3. Research on the Mechanism of Cross Regional Grassland Ecological Compensation

    Science.gov (United States)

    Yang, Ran; Ma, Jun

    2018-01-01

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

  4. Baking soda misuse as a home remedy: case experience of the California Poison Control System.

    Science.gov (United States)

    Al-Abri, S A; Kearney, T

    2014-02-01

    Baking soda is a common household product promoted by the manufacturer as an antacid. It contains sodium bicarbonate and has the potential for significant toxicity when ingested in excessive amounts. Characterizing the patterns and outcomes from the misuse of baking soda as a home remedy can guide the clinical assessment and preventative counselling of patients at risk for use of this product. We conducted a retrospective review of all symptomatic cases involving ingestion and misuse of a baking soda powder product that were reported to the California Poison Control System between the years 2000 and 2012. Of the 192 cases we identified, 55·8% were female, ages ranged 2 months to 79 years, and the most common reasons for misuse included antacid (60·4%), 'beat a urine drug test' (11·5%) and treat a UTI (4·7%). Most cases (55·2%) had significant symptoms warranting a medical evaluation, whereas 12 patients required hospital admission developed either electrolyte imbalances, metabolic alkalosis or respiratory depression. Misuse of baking soda can result in serious electrolyte and acid/base imbalances. Patients at highest risk of toxicity may include those who chronically use an antacid, those who use the method to 'beat' urine drug screens, pregnant women and young children. Self-treatment with baking soda as a home remedy may also mask or delay medical care thereby complicating or exacerbating an existing medical problem. We suggest that healthcare providers counsel high-risk patients about the potential complications of misuse of baking soda as a home remedy. © 2013 John Wiley & Sons Ltd.

  5. Effect of phosphorus availability on the selection of species with different ploidy levels and genome sizes in a long-term grassland fertilization experiment.

    Science.gov (United States)

    Šmarda, Petr; Hejcman, Michal; Březinová, Alexandra; Horová, Lucie; Steigerová, Helena; Zedek, František; Bureš, Petr; Hejcmanová, Pavla; Schellberg, Jürgen

    2013-11-01

    Polyploidy and increased genome size are hypothesized to increase organismal nutrient demands, namely of phosphorus (P), which is an essential and abundant component of nucleic acids. Therefore, polyploids and plants with larger genomes are expected to be selectively disadvantaged in P-limited environments. However, this hypothesis has yet to be experimentally tested. We measured the somatic DNA content and ploidy level in 74 vascular plant species in a long-term fertilization experiment. The differences between the fertilizer treatments regarding the DNA content and ploidy level of the established species were tested using phylogeny-based statistics. The percentage and biomass of polyploid species clearly increased with soil P in particular fertilizer treatments, and a similar but weaker trend was observed for the DNA content. These increases were associated with the dominance of competitive life strategy (particularly advantageous in the P-treated plots) in polyploids and the enhanced competitive ability of dominant polyploid grasses at high soil P concentrations, indicating their increased P limitation. Our results verify the hypothesized effect of P availability on the selection of polyploids and plants with increased genome sizes, although the relative contribution of increased P demands vs increased competitiveness as causes of the observed pattern requires further evaluation. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  6. Resurvey of site stability quadrilaterals, Otay Mountain and Quincy, California. [San Andreas fault experiment

    Science.gov (United States)

    Scholz, C. H.

    1977-01-01

    Trilateration quadrilaterals established across two faults near the San Andreas Fault Experiment laser/satellite ranging sites were resurveyed after four years. No evidence of significant tectonic motion was found.

  7. California Bioregions

    Data.gov (United States)

    California Natural Resource Agency — California regions developed by the Inter-agency Natural Areas Coordinating Committee (INACC) were digitized from a 1:1,200,000 California Department of Fish and...

  8. Operation and maintenance experience at the General Atomic Company's TRIGA reactor facility at San Diego, California

    International Nuclear Information System (INIS)

    Whittemore, W.L.; Stout, W.A.; Shoptaugh, J.R.; Chesworth, R.H.

    1982-01-01

    Since the startup of the original 250 kW TRIGA Mark I reactor in 1958, General Atomic Company has accumulated nearly 24 years of operation and maintenance experience with this type of reactor. In addition to the nearly 24 years of experience gained on the Mark I, GA has operated the 1.5 MW Advanced Prototype Test Reactor (Mark F) for 22 years and operated a 2 MW below-ground TRIGA Mark III for five years. Information obtained from normal and abnormal operation are presented. (author)

  9. Parenting their adolescents: the experiences of Jordanian immigrant women in California.

    Science.gov (United States)

    Hattar-Pollara, M; Meleis, A I

    1995-01-01

    Having their children enter adolescence presents new demands on the role functions of Jordanian immigrant women in the United States. Such demands require modifications in traditional parenting approaches. The authors attempted to uncover and describe the experiences of Jordanian immigrant mothers (N = 30) in parenting their adolescents in the United States. Content and narrative analysis revealed the dynamic processes that the mothers used in raising their children. They continuously attempted to balance the need for their teens to maintain a Jordanian ethnic identity and the need for them to become integrated into the new community. Their parenting was driven by an attempt to avoid loss of honor and bad reputation. Four aspects of the maternal role emerged from the analysis: mothering through nurturing the adolescents and promoting cultural identity, disciplining for cultural adherence, advocacy and mediation, and vigilant parenting. The findings support a dynamic interplay between cultural and structural conditions in shaping the experiences of Jordanian immigrant women.

  10. Effects of Government Grassland Conservation Policy on Household Livelihoods and Dependence on Local Grasslands: Evidence from Inner Mongolia, China

    NARCIS (Netherlands)

    Du, Bingzhen; Zhen, Lin; Yan, Huimin; Groot, de Dolf

    2016-01-01

    Grassland degradation intensifies human-environment conflicts and adversely affects local residents’ livelihoods. To reduce grassland degradation in Inner Mongolia, China, the government has enforced (since 1998) a series of grassland conservation and management policies that restrict the use of

  11. A Gravity data along LARSE (Los Angeles Regional Seismic Experiment) Line II, Southern California

    Science.gov (United States)

    Wooley, R.J.; Langenheim, V.E.

    2001-01-01

    The U.S. Geological Survey conducted a detailed gravity study along part of the Los Angeles Regional Seismic Experiment (LARSE) transect across the San Fernando Basin and Transverse Ranges to help characterize the structure underlying this area. 249 gravity measurements were collected along the transect and to augment regional coverage near the profile. An isostatic gravity low of 50-60 mGal reflects the San Fernando-East Ventura basin. Another prominent isostatic gravity with an amplitude of 30 mGal marks the Antelope Valley basin. Gravity highs occur over the Santa Monica Mountains and the Transverse Ranges. The highest isostatic gravity values coincide with outcrops of Pelona schist.

  12. Laparoscopic management of peripelvic renal cysts: University of California, San Francisco, experience and review of literature.

    Science.gov (United States)

    Camargo, Affonso H L A; Cooperberg, Matthew R; Ershoff, Brent D; Rubenstein, Jonathan N; Meng, Maxwell V; Stoller, Marshall L

    2005-05-01

    To report our experience and review published reports on the laparoscopic management of peripelvic renal cysts. Peripelvic renal cysts represent a unique subset of renal cysts, as they are rare, commonly symptomatic, and more difficult to treat than simple peripheral renal cysts. Minimally invasive methods for the treatment of peripelvic renal cysts, including laparoscopic decortication, have recently become more common. Four patients who presented with symptomatic peripelvic cysts underwent laparoscopic decortication at our institution. All four were men aged 47 to 65 years. One patient had undergone an unsuccessful prior cyst aspiration. All patients underwent preoperative computed tomography and retrograde pyelography. The mean number of peripelvic cysts per patient was 3.0, and the mean cyst size was 7.1 cm. The mean operative time was 259 minutes (range 240 to 293), and the mean estimated blood loss was 30 mL (range 10 to 50). No evidence of cystic renal cell carcinoma was found on aspiration cytology or cyst wall pathologic examination. The mean hospital stay was 1.3 days. No inadvertent collecting system injuries and no intraoperative or postoperative complications occurred. All 4 patients achieved symptomatic relief and were determined to have radiologic success as determined by the 6-month postoperative computed tomography findings. Laparoscopic ablation of peripelvic renal cysts is more difficult than that of simple peripheral renal cysts and demands a heightened awareness of potential complications and, therefore, more advanced surgical skills. In addition to our experience, a thorough review of published reports found this procedure to be safe and effective with appropriate patient selection.

  13. Changes in productivity of grassland with ageing

    NARCIS (Netherlands)

    Hoogerkamp, M.

    1984-01-01

    The productivity of grassland may change greatly with ageing. Frequently, a productive ley period, occurring in the first time after (re)seeding, is followed by a period in which productivity decreases. Under conditions favourable to grassland this may be temporary. A production level

  14. Airborne In-Situ Measurements of Formaldehyde Over California: First Results from the Compact Formaldehyde Fluorescence Experiment (COFFEE) Instrument

    Science.gov (United States)

    Marrero, Josette Elizabeth; Saint Clair, Jason; Yates, Emma L.; Gore, Warren; Swanson, Andrew K.; Iraci, Laura T.; Hanisco, Thomas F.

    2016-01-01

    Formaldehyde (HCHO) is one of the most abundant oxygenated volatile organic compounds (VOCs) in the atmosphere, playing a role multiple atmospheric processes. Measurements of HCHO can be used to help quantify convective transport, the abundance of VOCs, and ozone production in urban environments. The Compact Formaldehyde FluorescencE Experiment (COFFEE) instrument uses Non-Resonant Laser Induced Fluorescence (NR-LIF) to detect trace concentrations of HCHO as part of the Alpha Jet Atmospheric eXperiment (AJAX) payload. Developed at NASA GSFC, COFFEE is a small, low maintenance instrument with a sensitivity of 100 pptv and a quick response time (1 sec). The COFFEE instrument has been customized to fit in an external wing pod on the Alpha Jet aircraft based at NASA ARC. The instrument can operate over a broad range of altitudes, from boundary layer to lower stratosphere, making it well suited for the Alpha Jet, which can access altitudes from the surface up to 40,000 ft. Results of the first COFFEE science flights preformed over the California's Central Valley will be presented. Boundary layer measurements and vertical profiles in the tropospheric column will both be included. This region is of particular interest, due to its elevated levels of HCHO, revealed in satellite images, as well as its high ozone concentrations. In addition to HCHO, the AJAX payload includes measurements of atmospheric ozone, methane, and carbon dioxide. Formaldehyde is one of the few urban pollutants that can be measured from space. Plans to compare in-situ COFFEE data with satellite-based HCHO observations such as those from OMI (Aura) and OMPS (SuomiNPP) will also be presented.

  15. Effects of forest expansion on mountain grassland

    DEFF Research Database (Denmark)

    Guidi, Claudia; Magid, Jakob; Rodeghiero, Mirco

    2014-01-01

    Background and aims. Grassland abandonment followed by forest succession is the dominant land-use change in the European Alps. We studied the impact of current forest expansion on mountain grassland on changes in physical soil organic carbon (SOC) fractions along a land-use and management gradient......, focusing on changes in aggregate stability and particulate organic matter (POM). Methods. Four successional stages were investigated: managed grassland, two transitional phases in which grassland abandonment led to colonization by Picea abies (L.) Karst., and old mixed forest dominated by Fagus sylvatica L....... Results. The dimension of aggregates assessed by aggregate size fractionation tended to increase, whereas SOC allocation to stable aggregates assessed by sizedensity fractionation decreased following conversion of grassland to forest (e.g. from 81 to 59 % in the 0–5 cm layer). The amount of SOC stored...

  16. Extensive Management Promotes Plant and Microbial Nitrogen Retention in Temperate Grassland

    Science.gov (United States)

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

    2012-01-01

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

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

    Science.gov (United States)

    Brazier, Richard E.

    2015-04-01

    the environmental setting or wider climatic conditions that the grasslands experience. Furthermore, it is demonstrated that the relatively stable ecosystem state that has prevailed in the 'pristine' grasslands studied, is in fact very fragile and may be easily altered, either by anthropogenic forcing, due to land management or by 'semi-natural' processes, related to climate change or changes in the incidence of wildfires (for example). Once structurally altered, it is also shown that positive feedbacks will occur to accelerate the loss of critical resources (topsoil and nutrients) from the ecosystem, in particular in drylands, resulting in widespread land degradation that cannot be reversed. In the temperate grasslands studied, it is shown that anthropogenic intervention may halt or even to some degree reverse the degradation of the soil-vegetation-water continuum. However, such 'landscape restoration' approaches are costly and require long-term management commitment if they are to succeed. degrade these critical ecosystems further. Finally, analysis of water, sediment and nutrient fluxes from this range of grasslands also demonstrates how critical ecosystem services that grasslands can provide; including soil water storage to buffer downstream flooding, soil carbon storage and enhanced biodiversity are reduced, often to the point where restoration of the original (pristine) landscape function is impossible. To conclude, discussion is made of how we can learn across grass landscapes globally, to ensure that those ecosystems that might be restored to build resilient landscapes under future climates are well understood and that future efforts to manage grasslands for increased food production do not degrade these critical ecosystems further.

  18. Herbivores and nutrients control grassland plant diversity via light limitation

    Science.gov (United States)

    Borer, Elizabeth T.; Seabloom, Eric W.; Gruner, Daniel S.; Harpole, W. Stanley; Hillebrand, Helmut; Lind, Eric M.; Alder, Peter B.; Alberti, Juan; Anderson, T. Michael; Bakker, Jonathan D.; Biederman, Lori; Blumenthal, Dana; Brown, Cynthia S.; Brudvig, Lars A.; Buckley, Yvonne M.; Cadotte, Marc; Chu, Cheng-Jin; Cleland, Elsa E.; Crawley, Michael J.; Daleo, Pedro; Damschen, Ellen Ingman; Davies, Kendi F.; DeCrappeo, Nicole M.; Du, Guozhen; Firn, Jennifer; Hautier, Yann; Heckman, Robert W.; Hector, Andy; HilleRisLambers, Janneke; Iribarne, Oscar; Klein, Julia A.; Knops, Johannes M.H.; La Pierre, Kimberly J.; Leakey, Andrew D.B.; Li, Wei; MacDougall, Andrew S.; McCulley, Rebecca L.; Melbourne, Brett A.; Mitchell, Charles E.; Moore, Joslin L.; Mortensen, Brent; O'Halloran, Lydia R.; Orrock, John L.; Pascual, Jesús; Prober, Suzanne M.; Pyke, David A.; Risch, Anita C.; Schuetz, Martin; Smith, Melinda D.; Stevens, Carly J.; Sullivan, Lauren L.; Williams, Ryan J.; Wragg, Peter D.; Wright, Justin P.; Yang, Louie H.

    2014-01-01

    Human alterations to nutrient cycles and herbivore communities are affecting global biodiversity dramatically. Ecological theory predicts these changes should be strongly counteractive: nutrient addition drives plant species loss through intensified competition for light, whereas herbivores prevent competitive exclusion by increasing ground-level light, particularly in productive systems. Here we use experimental data spanning a globally relevant range of conditions to test the hypothesis that herbaceous plant species losses caused by eutrophication may be offset by increased light availability due to herbivory. This experiment, replicated in 40 grasslands on 6 continents, demonstrates that nutrients and herbivores can serve as counteracting forces to control local plant diversity through light limitation, independent of site productivity, soil nitrogen, herbivore type and climate. Nutrient addition consistently reduced local diversity through light limitation, and herbivory rescued diversity at sites where it alleviated light limitation. Thus, species loss from anthropogenic eutrophication can be ameliorated in grasslands where herbivory increases ground-level light.

  19. Competition under high and low nutrient levels among three grassland species occupying different positions in a successional sequence

    NARCIS (Netherlands)

    Schippers, P.; Snoeijing, I.; Kropff, M.J.

    1999-01-01

    To clarify the role of seasonal change, competitive response and nutrient availability in the competitive asymmetry of grassland species a competition experiment was conducted on Holcus lanatus, Anthoxanthum odoratum and Festuca ovina, which represent a successional sequence of decreasing nutrient

  20. Variability of annual CO2 exchange from Dutch grasslands

    NARCIS (Netherlands)

    Jacobs, C.M.J.; Jacobs, A.F.G.; Bosveld, F.C.; Hendriks, D.M.D.; Hensen, A.; Kroon, P.; Moors, E.J.; Nol, L.; Schrier-Uijl, A.P.; Veenendaal, E.M.

    2007-01-01

    An intercomparison is made of the Net Ecosystem Exchange of CO2, NEE, for eight Dutch grassland sites: four natural grasslands, two production grasslands and two meteorological stations within a rotational grassland region. At all sites the NEE was determined during at least 10 months per site,

  1. Herbage intake regulation and growth of rabbits raised on grasslands: back to basics and looking forward.

    Science.gov (United States)

    Martin, G; Duprat, A; Goby, J-P; Theau, J-P; Roinsard, A; Descombes, M; Legendre, H; Gidenne, T

    2016-10-01

    Organic agriculture is developing worldwide, and organic rabbit production has developed within this context. It entails raising rabbits in moving cages or paddocks, which enables them to graze grasslands. As organic farmers currently lack basic technical information, the objective of this article is to characterize herbage intake, feed intake and the growth rate of rabbits raised on grasslands in different environmental and management contexts (weather conditions, grassland type and complete feed supplementation). Three experiments were performed with moving cages at an experimental station. From weaning, rabbits grazed a natural grassland, a tall fescue grassland and a sainfoin grassland in experiments 1, 2 and 3, respectively. Rabbit diets were supplemented with a complete pelleted feed limited to 69 g dry matter (DM)/rabbit per day in experiment 1 and 52 g DM/rabbit per day in experiments 2 and 3. Herbage allowance and fiber, DM and protein contents, as well as rabbit intake and live weight, were measured weekly. Mean herbage DM intake per rabbit per day differed significantly (P<0.001) between experiments. It was highest in experiment 1 (78.5 g DM/day) and was 43.9 and 51.2 g DM/day in experiments 2 and 3, respectively. Herbage allowance was the most significant determinant of herbage DM intake during grazing, followed by rabbit metabolic weight (live weight0.75) and herbage protein and fiber contents. Across experiments, a 10 g DM increase in herbage allowance and a 100 g increase in rabbit metabolic weight corresponded to a mean increase of 6.8 and 9.6 g of herbage DM intake, respectively. When including complete feed, daily mean DM intakes differed significantly among experiments (P<0.001), ranging from 96.1 g DM/rabbit per day in experiment 2 to 163.6 g DM/rabbit per day in experiment 1. Metabolic weight of rabbits raised on grasslands increased linearly over time in all three experiments, yielding daily mean growth rates of 26.2, 19.2 and 28.5 g/day in

  2. Satellite-based assessment of grassland yields

    Science.gov (United States)

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

    2015-04-01

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

  3. Drought and Carbon Cycling of Grassland Ecosystems under Global Change: A Review

    Directory of Open Access Journals (Sweden)

    Tianjie Lei

    2016-10-01

    Full Text Available In recent years, the increased intensity and duration of droughts have dramatically altered the structure and function of grassland ecosystems, which have been forced to adapt to this change in climate. Combinations of global change drivers such as elevated atmospheric CO2 concentration, warming, nitrogen (N deposition, grazing, and land-use change have influenced the impact that droughts have on grassland C cycling. This influence, to some extent, can modify the relationship between droughts and grassland carbon (C cycling in the multi-factor world. Unfortunately, prior reviews have been primarily anecdotal from the 1930s to the 2010s. We investigated the current state of the study on the interactive impacts of multiple factors under drought scenarios in grassland C cycling and provided scientific advice for dealing with droughts and managing grassland C cycling in a multi-factor world. Currently, adequate information is not available on the interaction between droughts and global change drivers, which would advance our understanding of grassland C cycling responses. It was determined that future experiments and models should specifically test how droughts regulate grassland C cycling under global changes. Previous multi-factor experiments of current and future global change conditions have studied various drought scenarios poorly, including changes in precipitation frequency and amplitude, timing, and interactions with other global change drivers. Multi-factor experiments have contributed to quantifying these potential changes and have provided important information on how water affects ecosystem processes under global change. There is an urgent need to establish a systematic framework that can assess ecosystem dynamic responses to droughts under current and future global change and human activity, with a focus on the combined effects of droughts, global change drivers, and the corresponding hierarchical responses of an ecosystem.

  4. Description of the Grassland Biome Project

    CSIR Research Space (South Africa)

    Mentis, MT

    1982-10-01

    Full Text Available The objectives, organization and research programme of the Grassland Biome Project are described against a background of the biome's ecological characteristics and environmental problems. Four principal research topics wil 1 be focused upon: (i...

  5. The Immigrant's University: A Study of Academic Performance and the Experiences of Recent Immigrant Groups at the University of California

    Science.gov (United States)

    Douglass, John Aubrey; Thomson, Gregg

    2010-01-01

    One of the major characteristics of globalization is the large influx of immigrant groups moving largely from underdeveloped regions to developed economies. California offers one of the most robust examples of a large-scale, postmodern demographic transition that includes a great racial, ethnic, and cultural diversity of immigrant groups, many of…

  6. Comparative Effectiveness of Houghton Mifflin Harcourt Fuse: Algebra 1--A Report of Randomized Experiments in Four California Districts

    Science.gov (United States)

    Toby, Megan; Ma, Boya; Lai, Garrett; Lin, Li; Jaciw, Andrew

    2012-01-01

    In spring 2010, Houghton Mifflin Harcourt (HMH) began planning a pilot of an application for the Apple iPad, "HMH Fuse: Algebra 1," which was then in development. The application was to be piloted in four California school districts during the 2010-2011 school year. HMH contracted with Empirical Education Inc. to conduct a one-year…

  7. Comparative Effectiveness of Houghton Mifflin Harcourt Fuse: Algebra 1--A Report of Randomized Experiments in Four California Districts. Research Summary

    Science.gov (United States)

    Empirical Education Inc., 2012

    2012-01-01

    In spring 2010, Houghton Mifflin Harcourt (HMH) began planning a pilot of an application for the Apple iPad, "HMH Fuse: Algebra 1," which was then in development. The application was to be piloted in four California school districts during the 2010-2011 school year. HMH contracted with Empirical Education Inc. to conduct a one-year…

  8. Soil disturbance as a grassland restoration measure

    DEFF Research Database (Denmark)

    Schnoor, Tim; Bruun, Hans Henrik; Olsson, Pål Axel

    2015-01-01

    Soil disturbance is recognized as an important driver of biodiversity in dry grasslands, and can therefore be implemented as a restoration measure. However, because community re-assembly following disturbance includes stochastic processes, a focus only on species richness or establishment success...... to experimental disturbance treatments (ploughing or rotavation), and the vegetation was surveyed during four subsequent years of succession. Treated plots were compared with control plots representing untreated grassland, as well as nearby plots characterized by plant communities representing the restoration...

  9. The Effects of Timing of Grazing on Plant and Arthropod Communities in High-Elevation Grasslands

    Science.gov (United States)

    Davis, Stacy C.; Burkle, Laura A.; Cross, Wyatt F.; Cutting, Kyle A.

    2014-01-01

    Livestock grazing can be used as a key management tool for maintaining healthy ecosystems. However, the effectiveness of using grazing to modify habitat for species of conservation concern depends on how the grazing regime is implemented. Timing of grazing is one grazing regime component that is less understood than grazing intensity and grazer identity, but is predicted to have important implications for plant and higher trophic level responses. We experimentally assessed how timing of cattle grazing affected plant and arthropod communities in high-elevation grasslands of southwest Montana to better evaluate its use as a tool for multi-trophic level management. We manipulated timing of grazing, with one grazing treatment beginning in mid-June and the other in mid-July, in two experiments conducted in different grassland habitat types (i.e., wet meadow and upland) in 2011 and 2012. In the upland grassland experiment, we found that both early and late grazing treatments reduced forb biomass, whereas graminoid biomass was only reduced with late grazing. Grazing earlier in the growing season versus later did not result in greater recovery of graminoid or forb biomass as expected. In addition, the density of the most ubiquitous grassland arthropod order (Hemiptera) was reduced by both grazing treatments in upland grasslands. A comparison of end-of-season plant responses to grazing in upland versus wet meadow grasslands revealed that grazing reduced graminoid biomass in the wet meadow and forb biomass in the upland, irrespective of timing of grazing. Both grazing treatments also reduced end-of-season total arthropod and Hemiptera densities and Hemiptera biomass in both grassland habitat types. Our results indicate that both early and late season herbivory affect many plant and arthropod characteristics in a similar manner, but grazing earlier may negatively impact species of conservation concern requiring forage earlier in the growing season. PMID:25338008

  10. Factors affecting the ozone sensitivity of temperate European grasslands: An overview

    Energy Technology Data Exchange (ETDEWEB)

    Bassin, S. [Agroscope FAL Reckenholz, Swiss Federal Research Station for Agroecology and Agriculture, Air Pollution/Climate Group, Reckenholzstrasse 191, CH-8046 Zurich (Switzerland)]. E-mail: seraina.bassin@fal.admin.ch; Volk, M. [Agroscope FAL Reckenholz, Swiss Federal Research Station for Agroecology and Agriculture, Air Pollution/Climate Group, Reckenholzstrasse 191, CH-8046 Zurich (Switzerland); Fuhrer, J. [Agroscope FAL Reckenholz, Swiss Federal Research Station for Agroecology and Agriculture, Air Pollution/Climate Group, Reckenholzstrasse 191, CH-8046 Zurich (Switzerland)

    2007-04-15

    This overview of experimentally induced effects of ozone aims to identify physiological and ecological principles, which can be used to classify the sensitivity to ozone of temperate grassland communities in Europe. The analysis of data from experiments with single plants, binary mixtures and multi-species communities illustrates the difficulties to relate individual responses to communities, and thus to identify grassland communities most at risk. Although there is increasing evidence that communities can be separated into broad classes of ozone sensitivity, the database from experiments under realistic conditions with representative systems is too small to draw firm conclusions. But it appears that risk assessments, based on results from individuals or immature mixtures exposed in chambers, are only applicable to intensively managed, productive grasslands, and that the risk of ozone damage for most of perennial grasslands with lower productivity tends to be less than previously expected. - An overview of experimentally induced ozone effects suggests that temperate grasslands could be separated into broad classes of ozone sensitivity based on physiological and ecological principles.

  11. Factors affecting the ozone sensitivity of temperate European grasslands: An overview

    International Nuclear Information System (INIS)

    Bassin, S.; Volk, M.; Fuhrer, J.

    2007-01-01

    This overview of experimentally induced effects of ozone aims to identify physiological and ecological principles, which can be used to classify the sensitivity to ozone of temperate grassland communities in Europe. The analysis of data from experiments with single plants, binary mixtures and multi-species communities illustrates the difficulties to relate individual responses to communities, and thus to identify grassland communities most at risk. Although there is increasing evidence that communities can be separated into broad classes of ozone sensitivity, the database from experiments under realistic conditions with representative systems is too small to draw firm conclusions. But it appears that risk assessments, based on results from individuals or immature mixtures exposed in chambers, are only applicable to intensively managed, productive grasslands, and that the risk of ozone damage for most of perennial grasslands with lower productivity tends to be less than previously expected. - An overview of experimentally induced ozone effects suggests that temperate grasslands could be separated into broad classes of ozone sensitivity based on physiological and ecological principles

  12. Grassland Arthropods Are Controlled by Direct and Indirect Interactions with Cattle but Are Largely Unaffected by Plant Provenance.

    Science.gov (United States)

    Farrell, Kelly Anne; Harpole, W Stanley; Stein, Claudia; Suding, Katharine N; Borer, Elizabeth T

    2015-01-01

    Cattle grazing and invasion by non-native plant species are globally-ubiquitous changes occurring to plant communities that are likely to reverberate through whole food webs. We used a manipulative field experiment to quantify how arthropod community structure differed in native and non-native California grassland communities in the presence and absence of grazing. The arthropod community was strongly affected by cattle grazing: the biovolume of herbivorous arthropods was 79% higher in grazed than ungrazed plots, whereas the biovolume of predatory arthropods was 13% higher in ungrazed plots. In plots where non-native grasses were grazed, arthropod biovolume increased, possibly in response to increased plant productivity or increased nutritional quality of rapidly-growing annual plants. Grazing may thus affect plant biomass both through the direct removal of biomass, and through arthropod-mediated impacts. We also expected the arthropod community to differ between native and non-native plant communities; surprisingly, arthropod richness and diversity did not vary consistently between these grass community types, although arthropod abundance was slightly higher in plots with native and ungrazed grasses. These results suggest that whereas cattle grazing affects the arthropod community via direct and indirect pathways, arthropod community changes commonly associated with non-native plant invasions may not be due to the identity or dominance of the invasive species in those systems, but to accompanying changes in plant traits or functional group composition, not seen in this experiment because of the similarity of the plant communities.

  13. Grassland Arthropods Are Controlled by Direct and Indirect Interactions with Cattle but Are Largely Unaffected by Plant Provenance.

    Directory of Open Access Journals (Sweden)

    Kelly Anne Farrell

    Full Text Available Cattle grazing and invasion by non-native plant species are globally-ubiquitous changes occurring to plant communities that are likely to reverberate through whole food webs. We used a manipulative field experiment to quantify how arthropod community structure differed in native and non-native California grassland communities in the presence and absence of grazing. The arthropod community was strongly affected by cattle grazing: the biovolume of herbivorous arthropods was 79% higher in grazed than ungrazed plots, whereas the biovolume of predatory arthropods was 13% higher in ungrazed plots. In plots where non-native grasses were grazed, arthropod biovolume increased, possibly in response to increased plant productivity or increased nutritional quality of rapidly-growing annual plants. Grazing may thus affect plant biomass both through the direct removal of biomass, and through arthropod-mediated impacts. We also expected the arthropod community to differ between native and non-native plant communities; surprisingly, arthropod richness and diversity did not vary consistently between these grass community types, although arthropod abundance was slightly higher in plots with native and ungrazed grasses. These results suggest that whereas cattle grazing affects the arthropod community via direct and indirect pathways, arthropod community changes commonly associated with non-native plant invasions may not be due to the identity or dominance of the invasive species in those systems, but to accompanying changes in plant traits or functional group composition, not seen in this experiment because of the similarity of the plant communities.

  14. Bundled payment fails to gain a foothold In California: the experience of the IHA bundled payment demonstration.

    Science.gov (United States)

    Ridgely, M Susan; de Vries, David; Bozic, Kevin J; Hussey, Peter S

    2014-08-01

    To determine whether bundled payment could be an effective payment model for California, the Integrated Healthcare Association convened a group of stakeholders (health plans, hospitals, ambulatory surgery centers, physician organizations, and vendors) to develop, through a consensus process, the methods and means of implementing bundled payment. In spite of a high level of enthusiasm and effort, the pilot did not succeed in its goal to implement bundled payment for orthopedic procedures across multiple payers and hospital-physician partners. An evaluation of the pilot documented a number of barriers, such as administrative burden, state regulatory uncertainty, and disagreements about bundle definition and assumption of risk. Ultimately, few contracts were signed, which resulted in insufficient volume to test hypotheses about the impact of bundled payment on quality and costs. Although bundled payment failed to gain a foothold in California, the evaluation provides lessons for future bundled payment initiatives. Project HOPE—The People-to-People Health Foundation, Inc.

  15. Effects of grassland management on the emission of methane from grassland on peat soils

    Energy Technology Data Exchange (ETDEWEB)

    Van Dasselaar, A. [Dept. of Soil Science and Plant Nutrition, Wageningen Agricultural Univ. (Netherlands); Oenema, O. [NMI, Wageningen (Netherlands)

    1995-11-01

    Net methane (CH{sub 4}) emissions from managed grassland on peat soils in the Netherlands have been monitored with vented closed flux chambers in the period January - June 1994. Net CH{sub 4} emissions from two intensively managed grasslands were low, in general less than 0.1 mg CH{sub 4} m{sup -2} d{sup -l}. On these sites, the effect of management was negligibly small. CH{sub 4} emission from three extensively managed grasslands in a nature preserve ranged from 0 to 185 mg CH{sub 4} m{sup -2} d{sup -l}. The results presented here indicate that CH{sub 4} emissions are 2-3 orders of magnitude higher on extensively managed grasslands than on intensively managed grasslands. 2 figs., 6 refs.

  16. Fate of leaf-litter N in forest and grassland along a pedo-climatic gradient in south-western Siberia: an in situ 15N-labelling experiment

    Science.gov (United States)

    Brédoire, Félix; Zeller, Bernd; Nikitich, Polina; Barsukov, Pavel A.; Rusalimova, Olga; Bakker, Mark R.; Legout, Arnaud; Bashuk, Alexander; Kayler, Zachary E.; Derrien, Delphine

    2017-04-01

    The suitability of Siberia for agriculture is expected to increase in the next decades due to strong and rapid climatic changes, but little is known on the environmental drivers of soil fertility there, especially nitrogen (N). Plant-available N is mainly derived from litter decomposition. South-western (SW) Siberia is located on the transition between several bioclimatic zones that are predicted to shift and extend along with climate change (steppe, forest-steppe, sub-taiga). The soils of this region are formed on a common loess deposit but they are submitted to different climatic conditions and vegetation cover. In the south of the region, typically in steppe/forest-steppe, soil freezes over winter because of a relatively shallow snow-pack, and water shortages are frequent in summer. In the north, typically in sub-taiga, the soil is barely frozen in winter due to a thick snow-pack and sufficient soil moisture in summer. In this study, we characterized the dynamics of leaf litter decomposition and the transfer of N from leaf litter to the soil and back to plants. Four sites were chosen along a climate gradient (temperature, precipitation and snow depth). At each site, we applied 15N-labelled leaf litter on the soil surface in experimental plots in an aspen (Populus tremula L.) forest and in a grassland. Twice a year during three years, we tracked the 15N derived from the decomposing labelled-litter in the organic layers, in the first 15 cm of the soil, and in above-ground vegetation. Soil temperature and moisture were monitored at a daily timestep over three years and soil water budgets were simulated (BILJOU model, Granier et al. 1999). We observed contrasting patterns in the fate of litter-derived 15N between bioclimatic zones. Over three years, along with faster decay rates, the release of leaf litter-N was faster in sub-taiga than in forest-steppe. As such, higher quantities of 15N were transferred into the soil in sub-taiga. The transfer was also deeper there

  17. Plutonium in a grassland ecosystem

    International Nuclear Information System (INIS)

    Little, C.A.

    1976-08-01

    A study was made of plutonium contamination of grassland at the Rocky Flats plant northwest of Denver, Colorado. Of interest were: the definition of major plutonium-containing ecosystem compartments; the relative amounts in those compartments; how those values related to studies done in other geographical areas; whether or not the predominant isotopes, 238 Pu and 239 Pu, behaved differently; and what mechanisms might have allowed for the observed patterns of contamination. Samples of soil, litter, vegetation, arthropods, and small mammals were collected for Pu analysis and mass determination from each of two macroplots. Small aliquots (5 g or less) were analyzed by a rapid liquid scintillation technique and by alpha spectrometry. Of the compartments sampled, greater than 99 percent of the total plutonium was contained in the soil and the concentrations were significantly inversely correlated with distance from the contamination source, depth of the sample, and particle size of the sieved soil samples. The soil data suggested that the distribution of contamination largely resulted from physical transport processes

  18. Preliminary Research on Grassland Fine-classification Based on MODIS

    International Nuclear Information System (INIS)

    Hu, Z W; Zhang, S; Yu, X Y; Wang, X S

    2014-01-01

    Grassland ecosystem is important for climatic regulation, maintaining the soil and water. Research on the grassland monitoring method could provide effective reference for grassland resource investigation. In this study, we used the vegetation index method for grassland classification. There are several types of climate in China. Therefore, we need to use China's Main Climate Zone Maps and divide the study region into four climate zones. Based on grassland classification system of the first nation-wide grass resource survey in China, we established a new grassland classification system which is only suitable for this research. We used MODIS images as the basic data resources, and use the expert classifier method to perform grassland classification. Based on the 1:1,000,000 Grassland Resource Map of China, we obtained the basic distribution of all the grassland types and selected 20 samples evenly distributed in each type, then used NDVI/EVI product to summarize different spectral features of different grassland types. Finally, we introduced other classification auxiliary data, such as elevation, accumulate temperature (AT), humidity index (HI) and rainfall. China's nation-wide grassland classification map is resulted by merging the grassland in different climate zone. The overall classification accuracy is 60.4%. The result indicated that expert classifier is proper for national wide grassland classification, but the classification accuracy need to be improved

  19. Some Insights on Grassland Health Assessment Based on Remote Sensing

    Directory of Open Access Journals (Sweden)

    Dandan Xu

    2015-01-01

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

  20. Some insights on grassland health assessment based on remote sensing.

    Science.gov (United States)

    Xu, Dandan; Guo, Xulin

    2015-01-29

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

  1. Importance and functions of European grasslands.

    Science.gov (United States)

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

    2005-01-01

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

  2. [Research progress and trend on grassland agroecology].

    Science.gov (United States)

    Ren, Jizhou; Li, Xianglin; Hou, Fujiang

    2002-08-01

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

  3. Plutonium in a grassland ecosystem

    International Nuclear Information System (INIS)

    Little, C.A.

    1976-01-01

    This study was concerned with plutonium contamination of grassland at the U.S. Energy Research and Development Administration Rocky Flats plant northwest of Denver, Colorado. Of interest were: the definition of major plutonium-containing ecosystem compartments; the relative amounts in those compartments; how those values related to studies done in other geogrphical areas; whether or not the predominant isotopes, 238 Pu and 239 Pu, behaved differently; and what mechanisms might have allowed for the observed patterns of contamination. Samples of soil, litter, vegetation, arthropods, and small mammals were collected for plutonium analysis and mass determination from each of two macroplots. Small aliquots (5 g or less) were analyzed by a rapid liquid scintillation technique and by alpha spectrometry. Of the compartments sampled, greater than 99% of the total plutonium was contained in the soil. The concentrations of plutonium in soil were significantly inversely correlated with distance from the contamination source, depth of the sample, and particle size of the sieved soil samples. The soil data suggested that the distribution of contamination largely resulted from physical transport processes. A mechanism of agglomerated submicron plutonium oxide particles and larger (1-500 μm) host soil particles was proposed. Concentrations of Pu in litter and vegetation were inversely correlated to distance from the source and directly correlated to soil concentrations at the same location. Comparatively high concentration ratios of vegetation to soil suggested wind resuspension of contamination as an important transport mechanism. Arthropod and small mammal samples were highly skewed, kurtotic, and quite variable, having coefficients of variation (standard deviation/mean) as high as 600%. Bone Pu concentrations were lower than other tissues. Hide, GI, and lung were generally not higher in Pu than kidney, liver and muscle

  4. Black-tailed prairie dogs, cattle, and the conservation of North America's arid grasslands.

    Directory of Open Access Journals (Sweden)

    Rodrigo Sierra-Corona

    Full Text Available Prairie dogs (Cynomys spp. have been eliminated from over 95% of their historic range in large part from direct eradication campaigns to reduce their purported competition with cattle for forage. Despite the longstanding importance of this issue to grassland management and conservation, the ecological interactions between cattle and prairie dogs have not been well examined. We address this issue through two complementary experiments to determine if cattle and prairie dogs form a mutualistic grazing association similar to that between prairie dogs and American bison. Our experimental results show that cattle preferentially graze along prairie dog colony edges and use their colony centers for resting, resembling the mutualistic relationship prairie dogs have with American bison. Our results also show that prairie dog colonies are not only an important component of the grassland mosaic for maintaining biodiversity, but also provide benefits to cattle, thereby challenging the long-standing view of prairie dogs as an undesirable pest species in grasslands.

  5. Distinguishing Intensity Levels of Grassland Fertilization Using Vegetation Indices

    OpenAIRE

    Jens L. Hollberg; Jürgen Schellberg

    2017-01-01

    Monitoring the reaction of grassland canopies on fertilizer application is of major importance to enable a well-adjusted management supporting a sustainable production of the grass crop. Up to date, grassland managers estimate the nutrient status and growth dynamics of grasslands by costly and time-consuming field surveys, which only provide low temporal and spatial data density. Grassland mapping using remotely-sensed Vegetation Indices (VIs) has the potential to contribute to solving these ...

  6. Bird communities and biomass yields in potential bioenergy grasslands.

    Directory of Open Access Journals (Sweden)

    Peter J Blank

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

  7. Using a Regional Cluster of AmeriFlux Sites in Central California to Advance Our Knowledge on Decadal-Scale Ecosystem-Atmosphere Carbon Dioxide Exchange

    Energy Technology Data Exchange (ETDEWEB)

    Baldocchi, Dennis [Univ. of California, Berkeley, CA (United States)

    2015-03-24

    Continuous eddy convariance measurements of carbon dioxide, water vapor and heat were measured continuously between an oak savanna and an annual grassland in California over a 4 year period. These systems serve as representative sites for biomes in Mediterranean climates and experience much seasonal and inter-annual variability in temperature and precipitation. These sites hence serve as natural laboratories for how whole ecosystem will respond to warmer and drier conditions. The savanna proved to be a moderate sink of carbon, taking up about 150 gC m-2y-1 compared to the annual grassland, which tended to be carbon neutral and often a source during drier years. But this carbon sink by the savanna came at a cost. This ecosystem used about 100 mm more water per year than the grassland. And because the savanna was darker and rougher its air temperature was about 0.5 C warmer. In addition to our flux measurements, we collected vast amounts of ancillary data to interpret the site and fluxes, making this site a key site for model validation and parameterization. Datasets consist of terrestrial and airborne lidar for determining canopy structure, ground penetrating radar data on root distribution, phenology cameras monitoring leaf area index and its seasonality, predawn water potential, soil moisture, stem diameter and physiological capacity of photosynthesis.

  8. Constraints on tree seedling establishment in montane grasslands of the Valles Caldera, New Mexico

    Science.gov (United States)

    Jonathan D. Coop; Thomas J. Givnish

    2008-01-01

    Montane and subalpine grasslands are prominent, but poorly understood, features of the Rocky Mountains. These communities frequently occur below reversed tree lines on valley floors, where nightly cold air accumulation is spatially coupled with fine soil texture. We used field experiments to assess the roles of minimum temperature, soil texture, grass competition, and...

  9. Nitrogen Fertilizer Replacement Value of Concentrated Liquid Fraction of Separated Pig Slurry Applied to Grassland

    NARCIS (Netherlands)

    Middelkoop, Van J.C.; Holshof, G.

    2017-01-01

    Seven grassland experiments on sandy and clay soils were performed during a period of 4 years to estimate the nitrogen (N) fertilizer replacement value (NFRV) of concentrated liquid fractions of separated pig slurry (mineral concentrate: MC). The risk of nitrate leaching when applying MC was

  10. Dissimilar response of plant and soil biota communities to long-term nutrient adition in grasslands

    NARCIS (Netherlands)

    Wal, van der A.; Geerts, R.H.E.M.; Korevaar, H.; Schouten, A.J.; Jagers op Akkerhuis, G.A.J.M.; Rutgers, M.; Mulder, C.

    2009-01-01

    The long-term effect of fertilizers on plant diversity and productivity is well known, but long-term effects on soil biota communities have received relatively little attention. Here, we used an exceptional long-lasting (>40 years) grassland fertilization experiment to investigate the long-term

  11. Mechanical soil disturbance as a determinant of arbuscular mycorrhizal fungal communities in semi-natural grassland

    DEFF Research Database (Denmark)

    Schnoor, Tim Krone; Lekberg, Ylva; Rosendahl, Søren

    2011-01-01

    an ongoing grassland restoration experiment that contained replicated plowed and control plots. The AM fungal community in roots was determined using nested PCR and LSU rDNA primers. We identified 38 phylotypes within the Glomeromycota, of which 29 belonged to Glomus A, six to Glomus B, and three...

  12. Soil acidification and liming in grassland production and grassland soil fertility in Slovenia

    Directory of Open Access Journals (Sweden)

    Jure ČOP

    2015-12-01

    Full Text Available This paper reviews the evidences on grassland soil acidity and liming in relation to soil processes and herbage production. There is also an outline of the present state of soil acidity and acidity-related traits – contents of organic matter (OM, phosphorus (P and potassium (K in Slovene grassland. In grassland, soil acidification is an ongoing process under humid climate conditions. It is mainly driven by leaching of nutrients, net loss of cations due to retention in livestock products, use of physiologically acid fertilizers, acid rain and N2 fixation. This process is reduced by strong pH buffering capacity of the soil and by physiologically basic fertilizers. Acid grassland soils in Slovenia are widely distributed in spite of the fact that 44% of the total land has developed from a carbonate parent material. Of the 1713 grassland soil samples analysed during 2005-2007 45% were regarded as acid ones (pH < 5.5; in KCl, 57% as soils with very low P status (˂ 6 mg P2O5/100 g soil and 22% as soils with very low K status (˂ 10 mg K2O/100 soil. Increased content of soil organic matter was identified for alpine pastures (˃ 10 % OM in 44% of samples, mainly as a result of low decomposition rate. Liming of acid grassland soils did not always reflect in a higher herbage yield. The cause for this inefficiency is plant composition of grassland. Thus, many grassland plants with relatively high production potential have adapted to acid soil conditions. To illustrate the inconsistent liming effect three researches are reviewed. In the first two researches liming along with fertilizer application did not increase the yield comparing to the fertilized control while in the third research the increase amounted 26 %. Liming improves considerably botanical composition of the acid grassland (e.g. sward where Common Bent – Agrostis tenuis Sibth. – prevails and thus indirectly affects palatability and nutritive value of herbage. Grassland liming has a weak

  13. Grassland ecology and diversity (Ecologia y diversidad de pastizales)

    Science.gov (United States)

    Laurie B. Abbott

    2006-01-01

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

  14. Appreciation of the functions of grasslands by Irish stakeholders

    NARCIS (Netherlands)

    Hennessy, D.; Pol-van Dasselaar, van den A.

    2014-01-01

    The European project MultiSward studied the appreciation of different functions of grasslands by European stakeholders. This paper describes the importance of grasslands for stakeholders in Ireland. Ireland currently has approximately 4.6 million ha of grassland, which is 90% of the total utilized

  15. Predation drives nesting success in moist highland grasslands: the ...

    African Journals Online (AJOL)

    By focusing on process-oriented data rather than inventory-type data, this study provides a robust understanding of the effects of agricultural management on grassland bird reproductive output in the moist highland grasslands (MHGs) of South Africa. Four-hundred and four nests of 12 grassland-breeding bird species were ...

  16. Forging successful academic-community partnerships with community health centers: the California statewide Area Health Education Center (AHEC) experience.

    Science.gov (United States)

    Fowkes, Virginia; Blossom, H John; Mitchell, Brenda; Herrera-Mata, Lydia

    2014-01-01

    Increased access to insurance under the Affordable Care Act will increase demands for clinical services in community health centers (CHCs). CHCs also have an increasingly important educational role to train clinicians who will remain to practice in community clinics. CHCs and Area Health Education Centers (AHECs) are logical partners to prepare the health workforce for the future. Both are sponsored by the Health Resources and Services Administration, and they share a mission to improve quality of care in medically underserved communities. AHECs emphasize the educational side of the mission, and CHCs the service side. Building stronger partnerships between them can facilitate a balance between education and service needs.From 2004 to 2011, the California Statewide AHEC program and its 12 community AHECs (centers) reorganized to align training with CHC workforce priorities. Eight centers merged into CHC consortia; others established close partnerships with CHCs in their respective regions. The authors discuss issues considered and approaches taken to make these changes. Collaborative innovative processes with program leadership, staff, and center directors revised the program mission, developed common training objectives with an evaluation plan, and defined organizational, functional, and impact characteristics for successful AHECs in California. During this planning, centers gained confidence as educational arms for the safety net and began collaborations with statewide programs as well as among themselves. The AHEC reorganization and the processes used to develop, strengthen, and identify standards for centers forged the development of new partnerships and established academic-community trust in planning and implementing programs with CHCs.

  17. Hydrogen energy system in California

    International Nuclear Information System (INIS)

    Zweig, R.M.

    1995-01-01

    Results of experiences on the use of hydrogen as a clean burning fuel in California and results of the South Coast Air Quality Management district tests using hydrogen as a clean burning environmentally safe fuel are given. The results of Solar Hydrogen Projects in California and recent medical data documentation of human lung damage of patients living in air polluted urban areas are summarized

  18. COENOLOGICAL SHIFT FOLLOWING FERTILIZATION IN MEDITERRANEAN GRASSLAND

    Directory of Open Access Journals (Sweden)

    ALESSANDRO SERAFINI SAULI

    2006-05-01

    Full Text Available In Rome both meadows of CentraI-European affinity and Mediterranean dry grasslands are presento We studied a site (Parco Regionale Urbano de] Pineto in Rome with very diverse vegetation, where species belonging to both coenologica] groups oceur. Wc fertilized a grassland with a combination of phosphorus (P and nitrogen (N. After fertilization diagDostie species of Helianthemetea guttati (Thcrophytes dccrease while species of MolinioArrhenatheretea (Hemicriptophytes increase. In a climate as that of Rome, transition between Mediterranean (with summer drought and Central European (without summer drought, nutrients availability modulates the distribution of vegetation Classes with respectively Mediterranean or Central-Europe affinities.

  19. Carbon fluxes from an urban tropical grassland

    International Nuclear Information System (INIS)

    Ng, B.J.L.; Hutyra, L.R.; Nguyen, H.; Cobb, A.R.; Kai, F.M.; Harvey, C.; Gandois, L.

    2015-01-01

    Turfgrass covers a large fraction of the urbanized landscape, but the carbon exchange of urban lawns is poorly understood. We used eddy covariance and flux chambers in a grassland field manipulative experiment to quantify the carbon mass balance in a Singapore tropical turfgrass. We also assessed how management and variations in environmental factors influenced CO 2 respiration. Standing aboveground turfgrass biomass was 80 gC m −2 , with a mean ecosystem respiration of 7.9 ± 1.1 μmol m −2  s −1 . The contribution of autotrophic respiration was 49–76% of total ecosystem respiration. Both chamber and eddy covariance measurements suggest the system was in approximate carbon balance. While we did not observe a significant relationship between the respiration rates and soil temperature or moisture, daytime fluxes increased during the rainy interval, indicating strong overall moisture sensitivity. Turfgrass biomass is small, but given its abundance across the urban landscape, it significantly influences diurnal CO 2 concentrations. - Highlights: • We measured urban turfgrass CO 2 respiration rates and soil characteristics. • Mean observed ecosystem respiration was 7.9 ± 1.1 μmol m −2  s −1 . • Soil temperature and moisture were largely insignificant drivers of observed flux. - We found a Singapore urban turfgrass to be approximately carbon neutral, with a mean ecosystem respiration of 7.9 ± 1.1 μmol m −2  s −1

  20. Radioecological sensitivity of permanent grasslands

    International Nuclear Information System (INIS)

    Besson, Benoit

    2009-01-01

    The project 'SENSIB' of the Institute for Radiological Protection and Nuclear Safety (IRSN) aims at characterizing and classifying parameters with significant impact on the transfer of radioactive contaminants in the environment. This thesis is focused on permanent grassland areas. Its objectives are the analysis of the activity variations of two artificial radionuclides ( 137 Cs and 90 Sr) in the chain from soil to dairy products as well as the categorization of ecological and anthropogenic parameters, which determine the sensitivity of the studied area. For this study, in situ sampling is carried out in 15 farms in 3 different French regions (Charente, Puy-de-Dome and Jura). The sampling sites are chosen according to their natural variations (geology, altitude and climate) and the soil types. Additionally to the radiologic measurements, geographic, soil and vegetation data as well as data concerning cattle-rearing and cheese manufacturing processes are gathered. From the soil to the grass vegetation, 137 Cs transfer factors vary between 3 x 10-3 and 148 x 10-3 Bq kg-1 (dry weight) per Bq kg-1 (dry weight) (N = 73). Theses transfer factors are significantly higher in the Puy-de-Dome region than in the Jura region. The 137 Cs transfer factor from cattle feed to milk varies from 5.9 x 10-3 to 258 x 10-3 Bq kg-1 (fresh weight) per Bq kg-1 (dry weight) (N = 28). Statistically, it is higher in the Charente region. Finally, the 90 Sr transfer factor from milk to cheese ranges from 3.9 to 12.1. The studied site with the highest factor is the Jura (N = 25). The link between milk and dairy products is the stage with the most 137 Cs and 90 Sr transfers. A nonlinear approach based on a discretization method of the transfer factor with multiple comparison tests admits a classification of the sensitivity factors from soil to grass vegetation. We can determine 20 factors interfering in the 137 Cs transfer into the vegetation, for instance, the clay rate of the soils or a marker

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

    Science.gov (United States)

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

    2013-01-01

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

  2. Building capacity for HIV/AIDS prevention among Asian Pacific Islander organizations: the experience of a culturally appropriate capacity-building program in Southern California.

    Science.gov (United States)

    Takahashi, Lois M; Candelario, Jury; Young, Tim; Mediano, Elizabeth

    2007-01-01

    This article has two goals: (1) to outline a conceptual model for culturally appropriate HIV prevention capacity building; (2) to present the experiences from a 3-year program provided by Asian Pacific AIDS Intervention Team to Asian Pacific Islander (API) organizations in southern California. The participating organizations were of two types: lesbian, gay, bisexual, transgender, and questioning (LGBTQ) social organizations and social service agencies not targeting LGBTQ. These organizations were selected for participation because of their commitment to HIV/AIDS issues in API communities. An organizational survey and staff observations were used to explore changes in capacity. The organizations were mostly small, targeted diverse populations, served a large geographic area (southern California as a region), and were knowledgeable about HIV. Organizations became more viable (more capacity in human resources, financial, external relations, and strategic management), but also more unstable (large growth in paid staff and board members), and showed more capacity in HIV knowledge environments (especially less stigma and more sensitivity to diverse populations). The results suggest that capacity can expand over a short period of time, but as capacity increases, organizational viability/stability and HIV knowledge environments change, meaning that different types of technical assistance would be needed for sustainability.

  3. Precipitation and soil impacts on partitioning of subsurface moisture in Avena barbata: Observations from a greenhouse experiment

    Energy Technology Data Exchange (ETDEWEB)

    Salve, R.; Torn, M.S.

    2011-03-01

    The primary objective of this study was to assess the impact of two grassland soils and precipitation regimes on soil-moisture dynamics. We set up an experiment in a greenhouse, and monitored soil moisture dynamics in mesocosms planted with Avena barbata, an annual species found in California grasslands. By repeating the precipitation input at regular intervals, we were able to observe plant manipulation of soil moisture during well-defined periods during the growing season. We found that the amount of water partitioned to evapotranspiration, seepage, and soil storage varied among different growth stages. Further, both soil type and precipitation regimes had a significant impact on redistributing soil moisture. Whereas in the low-precipitation treatments most water was released to the atmosphere as evapotranspiration, major losses from the high-precipitation treatment occurred as gravity drainage. Observations from this study emphasize the importance of understanding intra-seasonal relationships between vegetation, soil, and water.

  4. Grasslands feeling the heat: The effects of elevated temperatures on a subtropical grassland

    Directory of Open Access Journals (Sweden)

    Rowan D. Buhrmann

    2016-12-01

    Conclusions: OTCs can simulate realistic increases of air temperature in subtropical grasslands. Graminoids and shrubs appear to benefit from elevated temperatures whilst forbs decrease in abundance, possibly through competition and/or direct physiological effects.

  5. Building leadership among laboratory-based and clinical and translational researchers: the University of California, San Francisco experience.

    Science.gov (United States)

    Wides, Cynthia; Mertz, Elizabeth; Lindstaedt, Bill; Brown, Jeanette

    2014-02-01

    In 2005 the University of California, San Francisco (UCSF) implemented the Scientific Leadership and Management (SLM) course, a 2-day leadership training program to assist laboratory-based postdoctoral scholars in their transition to independent researchers managing their own research programs. In 2011, the course was expanded to clinical and translational junior faculty and fellows. The course enrollment was increased from approximate 100 to 123 participants at the same time. Based on course evaluations, the number and percent of women participants appears to have increased over time from 40% (n = 33) in 2007 to 53% (n = 58) in 2011. Course evaluations also indicated that participants found the course to be relevant and valuable in their transition to academic leadership. This paper describes the background, structure, and content of the SLM and reports on participant evaluations of the course offerings from 2007 through 2011. © 2014 Wiley Periodicals, Inc.

  6. On the stability of mixed grasslands

    NARCIS (Netherlands)

    Schulte, R.P.O.

    2001-01-01

    Recent years have seen a renewed interest in the use of white clover (Trifolium repens) in grasslands, as a more sustainable alternative to fertiliser nitrogen inputs. However, mixtures of grasses and white clover have frequently been associated with unstable and hence unreliable herbage

  7. Purpose and Need for a Grassland Assessment

    Science.gov (United States)

    Deborah M. Finch; Cathy W. Dahms

    2004-01-01

    This report is volume 1 of an ecological assessment of grassland ecosystems in the Southwestern United States, and it is one of a series of planned publications addressing major ecosystems of the Southwest. The first assessment, General Technical Report RM-GTR- 295, An Assessment of Forest Ecosystem Health in the Southwest (by Dahms and Geils, technical editors,...

  8. [Spatiotemporal characteristics of MODIS NDVI in Hulunber Grassland].

    Science.gov (United States)

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

    2009-11-01

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

  9. Post-remedial-action survey report for Kinetic Experiment Water Boiler Reactor Facility, Santa Susana Field Laboratories, Rockwell International, Ventura County, California

    International Nuclear Information System (INIS)

    Wynveen, R.A.; Smith, W.H.; Sholeen, C.M.; Flynn, K.F.; Justus, A.L.

    1981-10-01

    Rockwell International's Santa Susana Laboratories in Ventura County, California, have been the site of numerous federally-funded contracted projects involving the use of radioactive materials. Among these was the Kinetics Experiment Water Boiler (KEWB) Reactor which was operated under the auspices of the US Atomic Energy Commission (AEC). The KEWB Reactor was last operated in 1966. The facility was subsequently declared excess and decontamination and decommissioning operations were conducted during the first half of calendar year 1975. The facility was completely dismantled and the site graded to blend with the surrounding terrain. During October 1981, a post-remedial-action (certification) survey of the KEWB site was conducted on the behalf of the US Department of Energy by the Radiological Survey Group (RSG) of the Occupational Health and Safety Division's Health Physics Section (OHS/HP) of Argonne National Laboratory (ANL). The survey confirmed that the site was free from contamination and could be released for unrestricted use

  10. Airborne In-Situ Measurements of Formaldehyde over California: One Year of Results from the Compact Formaldehyde Fluorescence Experiment (COFFEE) Instrument

    Science.gov (United States)

    Marrero, J. E.; St Clair, J. M.; Yates, E. L.; Ryoo, J. M.; Gore, W.; Swanson, A. K.; Iraci, L. T.; Hanisco, T. F.

    2016-12-01

    Formaldehyde (HCHO) is one of the most abundant oxygenated volatile organic compounds (VOCs) in the atmosphere, playing a role in multiple atmospheric processes, such as ozone (O3) production in polluted environments. Due to its short lifetime of only a few hours in daytime, HCHO also serves as tracer of recent photochemical activity. While photochemical oxidation of non-methane hydrocarbons is the dominant source, HCHO can also be emitted directly from fuel combustion, vegetation, and biomass burning. The Compact Formaldehyde FluorescencE Experiment (COFFEE) instrument was built for integration onto the Alpha Jet Atmospheric eXperiment (AJAX) payload, based out of NASA's Ames Research Center (Moffett Field, CA). Using Non-Resonant Laser Induced Fluorescence (NR-LIF), trace concentrations of HCHO can be detected with a sensitivity of 200 parts per trillion. Since its first research flight in December 2015, COFFEE has successfully flown on more than 20 science missions throughout California and Nevada. Presented here are results from these flights, including boundary layer measurements and vertical profiles throughout the tropospheric column. California's San Joaquin Valley is a primary focus, as this region is known for its elevated levels of HCHO as well as O3. Measurements collected in wildfire plumes, urban centers, agricultural lands, and on and off shore comparisons will be presented. In addition, the correlation of HCHO to other trace gases also measured by AJAX, including O3, methane, carbon dioxide, and water vapor will also be shown. Lastly, the implications of these HCHO measurements on calibration and validation of remote sensing data collected by NASA's OMI (Aura) and OMPS (SuomiNPP) satellites will be addressed.

  11. Nitrogen acquisition by plants and microorganisms in a temperate grassland.

    Science.gov (United States)

    Liu, Qianyuan; Qiao, Na; Xu, Xingliang; Xin, Xiaoping; Han, Jessie Yc; Tian, Yuqiang; Ouyang, Hua; Kuzyakov, Yakov

    2016-03-10

    Nitrogen (N) limitation is common in most terrestrial ecosystems, often leading to strong competition between microorganisms and plants. The mechanisms of niche differentiation to reduce this competition remain unclear. Short-term (15)N experiments with NH4(+), NO3(-), and glycine were conducted in July, August and September in a temperate grassland to evaluate the chemical, spatial and temporal niche differentiation by competition between plants and microorganisms for N. Microorganisms preferred NH4(+) and NO3(-), while plants preferred NO3(-). Both plants and microorganisms acquired more N in August and September than in July. The soil depth had no significant effects on microbial uptake, but significantly affected plant N uptake. Plants acquired 67% of their N from the 0-5 cm soil layer and 33% from the 5-15 cm layer. The amount of N taken up by microorganisms was at least seven times than plants. Although microorganisms efficiently compete for N with plants, the competition is alleviated through chemical partitioning mainly in deeper soil layer. In the upper soil layer, neither chemical nor temporal niche separation is realized leading to strong competition between plants and microorganisms that modifies N dynamics in grasslands.

  12. Transient behavior of cadmium in a grassland arthropod food chain

    International Nuclear Information System (INIS)

    Van Hook, R.I.; Yates, A.J.

    1975-01-01

    Biological assimilation and transport of cadmium were determined for an arthropod food chain in an east Tennessee grassland community. Laboratory experiments demonstrated that there were no significant differences (P greater than 0.05) in assimilation rates (17 percent assimilation per day) or biological half-lives (7 days) of 109 Cd either as soluble nitrate or insoluble oxide in crickets under identical conditions. Field experiments demonstrated that primary consumers (crickets) accumulated 109 Cd much more rapidly (uptake rate = 0.55 day -1 ) than did the spider predators (uptake rate = 0.08 day -1 ). Equilibrium concentrations in crickets were obtained in 9 days (0.04 ppM cadmium), while equilibrium was not reached in spiders during the 30-day study. Food-chain concentration of cadmium did not occur as crickets accumulated levels of cadmium 60 percent of that in their vegetation food sources and spiders accumulated only 70 percent of the cadmium present in the cricket tissues

  13. A Phenomenological Study: The Lived Experience of Former Foster Youth Attending a Four-Year College in Southern California

    Science.gov (United States)

    Lee, Dora Yiu Lam

    2010-01-01

    This qualitative study examined the lived experience of eight individuals attending a four-year college who were all part of a campus support program for former foster youth. The purpose of this phenomenological study was to understand and explore the lived experiences of these unique college students that have gone through the foster care system.…

  14. Greenhouse Gas Emission from Beef Cattle Grazing Systems on Temperate Grasslands

    Science.gov (United States)

    Rice, C. W.; Rivera-Zayas, J.

    2017-12-01

    At a global scale, cattle production is responsible for 65% of GHG emissions. During 2014 cattle management was the largest emitters of methane (CH4) representing a 23.2% of the total CH4 from anthropogenic activities. Since 2014, gas samples have been gathered and analyzed for carbon dioxide (CO2), CH4 and nitrous oxide (N2O) from three grazing areas under three different burning regimes at the temperate grassland of Konza Prairie Biological Station in Kansas. Burning regimes included one site in annually burned, and two sites with patch burned every three years on offset years. Burning regimes showed no effect in N2O emissions (pconsumed on grazed grassland soils; with an increase in consumption with patch burning. Results quantify the role of temperate grasslands as a sink of CH4, and a possible sink of N2O. This experiment evidence CO2, CH4 and N2O emissions behavior as a consequence of burning regimes, and quantify the role of temperate grasslands as a sink of CH4 and N2O in order to understand best practice for resilience of beef cattle management.

  15. Feasibility Study on: Reforestation of Degraded Grasslands in Indonesia as a Climate Change Mitigation Option

    Energy Technology Data Exchange (ETDEWEB)

    Dalfelt, A; Naess, L O; Sutamihardja, R T.M.; Gintings, N

    1997-12-31

    The report deals with a cooperation project between Norway and Indonesia dealing with a feasibility study on sustainable reforestation of degraded grasslands in Indonesia. Poor forest management and uncontrolled land use changes contribute a significant share anthropogenic emissions of greenhouse gases, especially CO{sub 2}, and one of many ways to reduce the CO{sub 2} emission is to encourage reforestation and better forest management. The report contains a brief overview of the issue of Imperata (alang-alang) grasslands, an outline of the present status, a discussion of potential costs and benefits associated with reforestation, and suggestions of strategies which could be applied to reach the desired goals. Case studies are presented from three locations where field work has been undertaken. The case studies provide baseline data about the sites and the imperata grasslands, experiences from earlier efforts to rehabilitate the grasslands, the common attitude to reforestation among the local communities, a discussion of the feasibility of reforestation, and finally, recommendations for the future. 142 refs., 11 figs., 15 tabs.

  16. Grassland/atmosphere response to changing climate: Coupling regional and local scales

    International Nuclear Information System (INIS)

    Coughenour, M.B.; Kittel, T.G.F.; Pielke, R.A.; Eastman, J.

    1993-10-01

    The objectives of the study were: to evaluate the response of grassland ecosystems to atmospheric change at regional and site scales, and to develop multiscaled modeling systems to relate ecological and atmospheric models with different spatial and temporal resolutions. A menu-driven shell was developed to facilitate use of models at different temporal scales and to facilitate exchange information between models at different temporal scales. A detailed ecosystem model predicted that C 3 temperate grasslands wig respond more strongly to elevated CO 2 than temperate C 4 grasslands in the short-term while a large positive N-PP response was predicted for a C 4 Kenyan grassland. Long-term climate change scenarios produced either decreases or increases in Colorado plant productivity (NPP) depending on rainfall, but uniform increases in N-PP were predicted in Kenya. Elevated CO 2 is likely to have little effect on ecosystem carbon storage in Colorado while it will increase carbon storage in Kenya. A synoptic climate classification processor (SCP) was developed to evaluate results of GCM climate sensitivity experiments. Roughly 80% agreement was achieved with manual classifications. Comparison of lx and 2xCO 2 GCM Simulations revealed relatively small differences

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

    Directory of Open Access Journals (Sweden)

    Fernando C. Scottá

    2015-07-01

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

  18. Feasibility Study on: Reforestation of Degraded Grasslands in Indonesia as a Climate Change Mitigation Option

    Energy Technology Data Exchange (ETDEWEB)

    Dalfelt, A.; Naess, L.O.; Sutamihardja, R.T.M.; Gintings, N.

    1996-12-31

    The report deals with a cooperation project between Norway and Indonesia dealing with a feasibility study on sustainable reforestation of degraded grasslands in Indonesia. Poor forest management and uncontrolled land use changes contribute a significant share anthropogenic emissions of greenhouse gases, especially CO{sub 2}, and one of many ways to reduce the CO{sub 2} emission is to encourage reforestation and better forest management. The report contains a brief overview of the issue of Imperata (alang-alang) grasslands, an outline of the present status, a discussion of potential costs and benefits associated with reforestation, and suggestions of strategies which could be applied to reach the desired goals. Case studies are presented from three locations where field work has been undertaken. The case studies provide baseline data about the sites and the imperata grasslands, experiences from earlier efforts to rehabilitate the grasslands, the common attitude to reforestation among the local communities, a discussion of the feasibility of reforestation, and finally, recommendations for the future. 142 refs., 11 figs., 15 tabs.

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

    Science.gov (United States)

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

    2010-05-01

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

  20. Energy analysis of various grassland utilisation systems

    Directory of Open Access Journals (Sweden)

    Jozef Ržonca

    2005-01-01

    Full Text Available In 2003 and 2004 was carried out the energy analysis of the different types of permanent grassland utilization on the Hrubý Jeseník locality. There were estimated values of the particular entrances of additional energy. Energy entrances moved according to the pratotechnologies from 2.17 GJ. ha–1 to 22.70 GJ.ha–1. The biggest share on energy entrances had fertilizers. It was 84.93% by the nitrogen fertilisation. The most energy benefit of brutto and nettoenergy was marked by the low intensive utilisation (33.40 GJ.ha–1 NEL and 32.40 GJ.ha–1 NEV on average. The highest value of energy efficiency (13.23% was marked by the low intensive utilization of permanent grassland. By using of higher doses of industrial fertilizers has energy efficiency decreased. From view of energy benefit and intensiveness on energy entrances it appears the most available utilisation of permanent grassland with three cuts per year (first cut on May 31st at the latest, every next after 60 days or two cuts per year (first cut on July 15th, next cuts after 90 days.

  1. SOWING GRASSLANDS – EFFICIENT SOLUTION FOR ZOOTEHNICAL PRODUCTION

    Directory of Open Access Journals (Sweden)

    VALENTINA OFELIA ROBESCU

    2008-05-01

    Full Text Available Recruitment is critical for the maintenance of plant populations and community diversity, but sexual regeneration is considered to be infrequent in climatically harsh habitats such as sub alpine grasslands. For this reasons it is very important to improve the grassland. In this paper we study the interaction among milk production, fertilizations and flower composition in sub alpine grasslands. The agrochemical indicators are important because they influence the pasture value and at the final the milk production.

  2. Effects of grassland management on the emission of methane from grassland on peat soils

    Energy Technology Data Exchange (ETDEWEB)

    Oenema, O. [Department of Soil Science and Plant Nutrition, Wageningen Agricultural University, Wageningen (Netherlands)

    1995-12-31

    The aim of the project on the title subject is to provide insight into the major controlling factors that contribute to the net exchange rates of methane (CH4) between grassland and atmosphere, and to provide quantitative net CH4 emission rates. Net CH4 emissions have been monitored with vented closed flux chambers on both intensively managed grasslands and grasslands in a nature preserve on peat soil in the Netherlands. Net CH4 emissions from intensively managed grasslands (Zegveld, Netherlands) were low in the period January-December 1994, in general in the range of -0.2 to 0.2 mg CH4 m{sup -2} d{sup -1}. Only in the relatively warm summer of 1994, consumption of atmospheric CH4 of about 0.4 mg m{sup -2} d{sup -1} was measured. Effects of ground water level in the range of 30-60 cm below surface were very small. There were also no clear effects of nitrogen fertilization and grazing versus mowing on CH4 emission from the soil. Net CH4 emissions from three extensively managed grasslands in a nature preserve (Nieuwkoopse Plassen area in the Netherlands) ranged from 0-215 mg CH4 m{sup -2} d{sup -1} in the period January 1994-June 1995. Differences between the three sites were quite large, as were the spatial variations at each of the sites. The results presented here indicate that a shift of intensively managed peat grasslands into more natural ecosystems will significantly increase the contribution of Dutch peat soils to the total CH4 emission. refs.

  3. Regional Variation in the Temperature Sensitivity of Soil Organic Matter Decomposition in China's Forests and Grasslands

    Science.gov (United States)

    Liu, Y.; He, N.; Zhu, J.; Yu, G.; Xu, L.; Niu, S.; Sun, X.; Wen, X.

    2017-12-01

    How to assess the temperature sensitivity (Q10) of soil organic matter (SOM) decomposition and its regional variation with high accuracy is one of the largest uncertainties in determining the intensity and direction of the global carbon (C) cycle in response to climate change. In this study, we collected a series of soils from 22 forest sites and 30 grassland sites across China to explore regional variation in Q10 and its underlying mechanisms. We conducted a novel incubation experiment with periodically changing temperature (5-30 °C), while continuously measuring soil microbial respiration rates. The results showed that Q10 varied significantly across different ecosystems, ranging from 1.16 to 3.19 (mean 1.63). Q10 was ordered as follows: alpine grasslands (2.01) > temperate grasslands (1.81) > tropical forests (1.59) > temperate forests (1.55) > subtropical forests (1.52). The Q10 of grasslands (1.90) was significantly higher than that of forests (1.54). Furthermore, Q10 significantly increased with increasing altitude and decreased with increasing longitude. Environmental variables and substrate properties together explained 52% of total variation in Q10 across all sites. Overall, pH and soil electrical conductivity primarily explained spatial variation in Q10. The general negative relationships between Q10 and substrate quality among all ecosystem types supported the C quality temperature (CQT) hypothesis at a large scale, which indicated that soils with low quality should have higher temperature sensitivity. Furthermore, alpine grasslands, which had the highest Q10, were predicted to be more sensitive to climate change under the scenario of global warming.

  4. Effects of water and nitrogen addition on species turnover in temperate grasslands in northern China.

    Directory of Open Access Journals (Sweden)

    Zhuwen Xu

    Full Text Available Global nitrogen (N deposition and climate change have been identified as two of the most important causes of current plant diversity loss. However, temporal patterns of species turnover underlying diversity changes in response to changing precipitation regimes and atmospheric N deposition have received inadequate attention. We carried out a manipulation experiment in a steppe and an old-field in North China from 2005 to 2009, to test the hypothesis that water addition enhances plant species richness through increase in the rate of species gain and decrease in the rate of species loss, while N addition has opposite effects on species changes. Our results showed that water addition increased the rate of species gain in both the steppe and the old field but decreased the rates of species loss and turnover in the old field. In contrast, N addition increased the rates of species loss and turnover in the steppe but decreased the rate of species gain in the old field. The rate of species change was greater in the old field than in the steppe. Water interacted with N to affect species richness and species turnover, indicating that the impacts of N on semi-arid grasslands were largely mediated by water availability. The temporal stability of communities was negatively correlated with rates of species loss and turnover, suggesting that water addition might enhance, but N addition would reduce the compositional stability of grasslands. Experimental results support our initial hypothesis and demonstrate that water and N availabilities differed in the effects on rate of species change in the temperate grasslands, and these effects also depend on grassland types and/or land-use history. Species gain and loss together contribute to the dynamic change of species richness in semi-arid grasslands under future climate change.

  5. Student Experiences of "Soul Healing" in Music and Dance Performance Courses at The University of California, Los Angeles

    OpenAIRE

    Rann, Lara Diane

    2015-01-01

    This dissertation illuminates students’ experiences of “soul healing” through the cultivation of spirituality, self-love/ self-knowledge, mentorship, and community in the context of two UCLA courses: the Music and Dance of Ghana World Music Performance Ensemble, taught by master drummer Kobla Ladzekpo of the Anlo-Ewe ethnic group in Ghana, West Africa, and “Advanced Hip Hop,” taught by “street dance” pioneer and choreographer Rennie Harris, of Philadelphia, PA. My definition of soul healing ...

  6. Impact of Grassland Reseeding, Herbicide spraying and Ploughing on Diversity and Abundance of Soil Arthropods.

    OpenAIRE

    Wei Liu; Wei Liu; Wei Liu; Junling Zhang; Stuart L Norris; Phil Murray

    2016-01-01

    In order to determine the interactive effect of reseeding, herbicide spraying and ploughing on soil fauna communities, we conducted a grassland reseeding experiment combined with pre-reseed management to examine how with the whole reseeding process affects soil faunal composition. Sampling occasions and exact treatments were as follows: 1) before chemical herbicide spray; 2) after spray but before ploughing; 3) after ploughing but before reseeding; and 4) after one year of recovery. Our resul...

  7. Greenhouse gas balance of an establishing Sphagnum culture on a former bog grassland in Germany

    OpenAIRE

    A. Günther; G. Jurasinski; K. Albrecht; G. Gaudig; M. Krebs; S. Glatzel

    2017-01-01

    The cultivation of Sphagnum mosses on re-wetted peat bogs for use in horticulture is a new land use strategy. We provide the first greenhouse gas balances for a field-scale Sphagnum farming experiment on former bog grassland, in its establishment phase. Over two years we used closed chambers to make measurements of GHG exchange on production strips of Sphagnum palustre L. and Sphagnum papillosum Lindb. and on irrigation ditches. Methane fluxes of both Sphagnum species showed a significant dec...

  8. More than a century of Grain for Green Program is expected to restore soil carbon stock on alpine grassland revealed by field {sup 13}C pulse labeling

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qi; Chen, Dongdong; Zhao, Liang [Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, Qinghai (China); Yang, Xue [Department of Education of Qinghai Province, Xining 810008, Qinghai (China); Xu, Shixiao [Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, Qinghai (China); Zhao, Xinquan, E-mail: xqzhao@nwipb.cas.cn [Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, Qinghai (China); Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 10041, Sichuan (China)

    2016-04-15

    Anthropogenic changes in land use/cover have altered the vegetation, soil, and carbon (C) cycling on the Qinghai–Tibetan Plateau (QTP) over the last ~ 50 years. As a result, the Grain for Green Program (GfGP) has been widely implemented over the last 10 years to mitigate the impacts of cultivation. To quantify the effects of the GfGP on C partitioning and turnover rates at the ecosystem scale, an in situ {sup 13}C pulse labeling experiment was conducted on natural and GfGP grasslands in an agro-pastoral ecotone in the Lake Qinghai region on the QTP. We found that there were significant differences in the C stocks of all the considered pools in both the natural and GfGP grasslands, with higher CO{sub 2} uptake rates in the GfGP grassland than that in the natural grassland. Partitioning of photoassimilate (% of recovered {sup 13}C) in C pools of both grasslands was similar 25 days after labeling, except in the roots of the 0–15 and 5–15 cm soil layer. Soil organic C (SOC) sequestration rate in the GfGP grassland was 11.59 ± 1.89 g C m{sup −2} yr{sup −1} significantly greater than that in the natural grassland. The results confirmed that the GfGP is an efficient approach for grassland restoration and C sequestration. However, it will take more than a century (119.19 ± 20.26 yr) to restore the SOC stock from the current cropland baseline level to the approximate level of natural grassland. We suggest that additional measures are needed in the selection of suitable plant species for vegetation restoration, and in reasonable grazing management. - Highlights: • Grain for Green Project initiated in 1999 converts cropland to grassland/shrubland. • Impact of Grain for Green on carbon cycling on Qinghai–Tibetan Plateau is unknown. • Effects on carbon partitioning and turnover were accessed by {sup 13}CO{sub 2} pulse labeling. • Different mass of {sup 13}C in excess, similar {sup 13}C partitioning are shown in grasslands. • Soil organic carbon of

  9. More than a century of Grain for Green Program is expected to restore soil carbon stock on alpine grassland revealed by field "1"3C pulse labeling

    International Nuclear Information System (INIS)

    Li, Qi; Chen, Dongdong; Zhao, Liang; Yang, Xue; Xu, Shixiao; Zhao, Xinquan

    2016-01-01

    Anthropogenic changes in land use/cover have altered the vegetation, soil, and carbon (C) cycling on the Qinghai–Tibetan Plateau (QTP) over the last ~ 50 years. As a result, the Grain for Green Program (GfGP) has been widely implemented over the last 10 years to mitigate the impacts of cultivation. To quantify the effects of the GfGP on C partitioning and turnover rates at the ecosystem scale, an in situ "1"3C pulse labeling experiment was conducted on natural and GfGP grasslands in an agro-pastoral ecotone in the Lake Qinghai region on the QTP. We found that there were significant differences in the C stocks of all the considered pools in both the natural and GfGP grasslands, with higher CO_2 uptake rates in the GfGP grassland than that in the natural grassland. Partitioning of photoassimilate (% of recovered "1"3C) in C pools of both grasslands was similar 25 days after labeling, except in the roots of the 0–15 and 5–15 cm soil layer. Soil organic C (SOC) sequestration rate in the GfGP grassland was 11.59 ± 1.89 g C m"−"2 yr"−"1 significantly greater than that in the natural grassland. The results confirmed that the GfGP is an efficient approach for grassland restoration and C sequestration. However, it will take more than a century (119.19 ± 20.26 yr) to restore the SOC stock from the current cropland baseline level to the approximate level of natural grassland. We suggest that additional measures are needed in the selection of suitable plant species for vegetation restoration, and in reasonable grazing management. - Highlights: • Grain for Green Project initiated in 1999 converts cropland to grassland/shrubland. • Impact of Grain for Green on carbon cycling on Qinghai–Tibetan Plateau is unknown. • Effects on carbon partitioning and turnover were accessed by "1"3CO_2 pulse labeling. • Different mass of "1"3C in excess, similar "1"3C partitioning are shown in grasslands. • Soil organic carbon of cropland will be restored to natural

  10. Interference between perennial grassland and Lavandula stoechas subsp. pedunculata seedlings: a case of spatial segregation cause by competition

    Science.gov (United States)

    Sánchez, Ana M.; Peco, Begoña

    2004-07-01

    This paper analyses the relationship between Lavandula stoechas subsp. pedunculata, a common Mediterranean scrub species in central Iberia, and perennial grasslands. While Lavandula gives rise to almost monospecific formations in intermediate and upper hill zones, perennial grasses occupy the low areas. The proposed explanatory hypothesis for this spatial distribution is that the scrub is unable to establish itself in grasslands with heavy spatial occupation. We designed two experiments to test this hypothesis, one which analysed the effect of perennial grass cover on Lavandula establishment, and another which focused on its influence on previously implanted seedling survival and growth, distinguishing the effect of shoot and root interference. The results show negative interference during establishment and later in the use of light and nutrients. This results in a very low overall survival probability, with only 1.4% of seedlings surviving the first growth period. This low success rate explains the existence of a clear spatial segregation between scrub patches and perennial-dominated grasslands.

  11. The California-Arizona Minority Partnership for Astronomy Research and Education (CAMPARE): an Educational Experience for Undergraduates at the University of Arizona Alumni Association's Astronomy Camp.

    Science.gov (United States)

    Lemon, Courtney; McCarthy, D.; Rudolph, A.

    2011-01-01

    The California-Arizona Minority Partnership for Astronomy Research and Education (CAMPARE) is an NSF-funded partnership between the Astronomy Program at Cal Poly Pomona (CPP) and the University of Arizona Steward Observatory designed to promote participation of underrepresented minorities (including women) in astronomy research and education. As part of the education component of the program, CPP undergraduate physics majors and minors are eligible to work as a counselor at the University of Arizona's Astronomy Camp, one of the premier astronomy outreach opportunities in the world. CAMPARE students have the opportunity to work in this learn-by-doing environment with a wide range of students to gain first hand experience of teaching astronomy to students of a wide variety of ages in highly structured educational setting. Cal Poly Pomona students who are interested in education, both formal and informal, work in a variety of camps, from Girl Scout camps to camps for advanced high school students, to further their understanding of what it means to be a professional in the field of education. The CAMPARE student who participated in this program during summer 2010 had the opportunity to work under Dr. Don McCarthy, camp director of University of Arizona's Astronomy Camps for 20 years, and observe the interpersonal relations between campers and staff that is so vital to the learning the students receive. Through these observations, the CAMPARE student was able to learn to gauge students' interest in the material, and experience real life teaching and learning scenarios in the informal education realm.

  12. Cattle slurry on grassland - application methods and nitrogen use efficiency

    NARCIS (Netherlands)

    Lalor, S.T.J.

    2014-01-01

    Cattle slurry represents a significant resource on grassland-based farming systems. The objective of this thesis was to investigate and devise cattle slurry application methods and strategies that can be implemented on grassland farms to improve the efficiency with which nitrogen (N) in

  13. Ecological transition in Arizona's subalpine and montane grasslands

    Science.gov (United States)

    Michael R. White

    2000-01-01

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

  14. Influence of density on the seasonal utilization of broad grassland ...

    African Journals Online (AJOL)

    We monitored seasonal use of grassland types by white rhinos at two sites within the Hluhluwe iMfolozi Park (HiP). Thirty-two rhinos were removed from one site to reduce rhino density. Seasonal use of grassland types was similar at both sites, but differed to what a previous study reported. This was likely due to higher food ...

  15. Prescribed burning supports grassland biodiversity - A multi-species study

    Science.gov (United States)

    Valkó, Orsolya; Deák, Balázs; Magura, Tibor; Török, Péter; Kelemen, András; Tóth, Katalin; Horváth, Roland; Nagy, Dávid; Debnár, Zsuzsanna; Zsigrai, György; Kapocsi, István; Tóthmérész, Béla

    2017-04-01

    During ancient times, fire was an important factor shaping European landscapes. Nowadays, prescribed burning can be one of the most effective conservation tools for the management of open landscapes, controlling dominant species, reducing accumulated litter or decreasing wildfire risk. In a prescribed burning experiment, we studied the effects of fire on dry alkaline grasslands. We tested whether autumn prescribed burning can be an alternative conservation measure in these grasslands. We selected six sites in Hungary: in three sites, prescribed burning was applied in November 2011, while three sites remained unburnt. We studied the effects of fire on soil characteristics, plant biomass and on the vegetation and arthropod assemblages (isopods, spiders, ground beetles and rove beetles). Soluble salt content increased significantly in the burnt sites, but soil pH, organic matter, potassium and phosphorous did not change. We found that prescribed fire had several positive effects from the nature conservation viewpoint. Diversity and the number of flowering shoots were higher, and the cover of the dominant grass was lower in the burnt sites. Graminoid biomass was lower, while total, green and forb biomass were higher in the burnt plots compared to the control ones. Our findings suggest that prescribed burning fire did not harm arthropods; species-level analyses showed that out of the most abundant invertebrate species, the abundance of ten was not affected, one decreased and one increased after burning. Our findings highlight that mosaic prescribed fire is a viable management tool in open landscapes, because it supports plant diversity and does not threaten arthropods.

  16. A Teacher Training Experience Based on Work with Communities in California Una experiencia de formación de profesores a partir del trabajo con comunidades en California Uma experiência de formação de professores que trabalham em comunidades de California

    Directory of Open Access Journals (Sweden)

    Fernando Rodriguez-Valls

    2011-04-01

    Full Text Available This article describes the results of a teacher training model that involves contact with local communities and action-research practices. The study included students enrolled in the education program at a university in southern California during the 2007-08 school year. They were interviewed during the course of their 16-week projects in which they analyzed the global culture of students and parents from various ethnic groups as subsequent input for classroom work and, ultimately, the design of lessons and the development of educational plans pursuant to the requirements of the California Commission on Teacher Credentialing (CCTC. Among other conclusions, it was found that transforming teachers acquire a variety of useful skills for their work as educators in the global village by learning about the community from the inside out.El artículo presenta los resultados de un modelo de formación de profesores en contacto con comunidades locales, según el esquema de investigación-acción. En el estudio participaron los estudiantes del programa de educación en una universidad ubicada en el sur de California, durante el año escolar 2007-08, a quienes se entrevistó durante el desarrollo de sus proyectos, de 16 semanas, en los que analizaron la cultura global desde los estudiantes y padres procedentes de varios grupos étnicos, mediante lo cual se aportó luego al trabajo de aula y, posteriormente, al diseño de lecciones y al desarrollo de planes educativos, siguiendo las normas establecidas por la Comisión de Maestros de California (CCTC. Entre las conclusiones se encontró que al aprender acerca de la comunidad desde adentro hacia afuera, los educadores de la transformación adquirieron diversas competencias, útiles para su trabajo como educadores en la aldea global.O artigo apresenta os resultados de um modelo de formação de professores que trabalham em comunidades locais, de acordo com o esquema de pesquisa-ação. Foram incluidos os

  17. Precipitation alters interactions in a grassland ecological community.

    Science.gov (United States)

    Deguines, Nicolas; Brashares, Justin S; Prugh, Laura R

    2017-03-01

    Climate change is transforming precipitation regimes world-wide. Changes in precipitation regimes are known to have powerful effects on plant productivity, but the consequences of these shifts for the dynamics of ecological communities are poorly understood. This knowledge gap hinders our ability to anticipate and mitigate the impacts of climate change on biodiversity. Precipitation may affect fauna through direct effects on physiology, behaviour or demography, through plant-mediated indirect effects, or by modifying interactions among species. In this paper, we examined the response of a semi-arid ecological community to a fivefold change in precipitation over 7 years. We examined the effects of precipitation on the dynamics of a grassland ecosystem in central California from 2007 to 2013. We conducted vegetation surveys, pitfall trapping of invertebrates, visual surveys of lizards and capture-mark-recapture surveys of rodents on 30 plots each year. We used structural equation modelling to evaluate the direct, indirect and modifying effects of precipitation on plants, ants, beetles, orthopterans, kangaroo rats, ground squirrels and lizards. We found pervasive effects of precipitation on the ecological community. Although precipitation increased plant biomass, direct effects on fauna were often stronger than plant-mediated effects. In addition, precipitation altered the sign or strength of consumer-resource and facilitative interactions among the faunal community such that negative or neutral interactions became positive or vice versa with increasing precipitation. These findings indicate that precipitation influences ecological communities in multiple ways beyond its recognized effects on primary productivity. Stochastic variation in precipitation may weaken the average strength of biotic interactions over time, thereby increasing ecosystem stability and resilience to climate change. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological

  18. Report on data from the Nearshore Sediment Transport Study experiment at Leadbetter Beach, Santa Barbara, California, January-February 1980 (NODC Accession 8200080)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — THIS DATA SET CONSISTS OF THE RESULTS OF THE NEARSHORE SEDIMENT Nearshore Sediment Transport Study at Leadbetter Beach, Santa Barbara, California. These data from 28...

  19. Isolated Transverse Process Fractures and Markers of Associated Injuries: The Experience at University of California, Los Angeles.

    Science.gov (United States)

    Bui, Timothy T; Nagasawa, Daniel T; Lagman, Carlito; Jacky Chen, Cheng Hao; Chung, Lawrance K; Voth, Brittany L; Beckett, Joel S; Tucker, Alexander M; Niu, Tianyi; Gaonkar, Bilwaj; Yang, Isaac; Macyszyn, Luke

    2017-08-01

    To report a single-institution experience with isolated transverse process fractures (ITPFs) and provide increasing support for the development of evidence-based guidelines. The authors also evaluated the presence of concerning symptoms or red flags that may indicate additional, underlying injuries in the setting of ITPFs. The Ronald Reagan UCLA Medical Center patient database was queried (years 2005-2016) using International Classification of Diseases, Ninth Revision, code 805: fracture of the vertebral column without mention of spinal cord injury. A total of 129 patients with ITPFs were identified. Mean age was 38.1 years (range 15-92 years). Women were more likely to present with abdominal pain and associated kidney injury (P = 0.018 and P = 0.012, respectively). Motor vehicle accident (MVA) was the most common mechanism of injury (n = 81, 62.8%) and was associated with thoracic (P = 0.032) and lower extremity pain/injury (P = 0.005). Back pain was the most common presenting symptom (n = 71, 64.6%) and was associated with intraabdominal and lower extremity injuries (P = 0.032 and P = 0.016, respectively). Chest and neck pain were associated with vascular injuries (P < 0.001 and P = 0.001, respectively). Spine consult (neurosurgery or orthopedic surgery) was frequent (n = 94, 72.9%) and was more common after MVA versus fall (P = 0.018). Several factors were identified as significant markers of associated injuries, including female sex, MVA, and presenting symptoms. Neck and chest pain were significantly associated with vascular injuries. Clinicians should maintain high indices of suspicion for associated injuries in patients with ITPFs, especially after high-velocity mechanisms. Copyright © 2017. Published by Elsevier Inc.

  20. Effects of Government Grassland Conservation Policy on Household Livelihoods and Dependence on Local Grasslands: Evidence from Inner Mongolia, China

    Directory of Open Access Journals (Sweden)

    Bingzhen Du

    2016-12-01

    Full Text Available Grassland degradation intensifies human-environment conflicts and adversely affects local residents’ livelihoods. To reduce grassland degradation in Inner Mongolia, China, the government has enforced (since 1998 a series of grassland conservation and management policies that restrict the use of grasslands. To ease the impact on the residents’ livelihoods, the national and regional governments have offered a series of top-down arrangements to stimulate sustainable use of the grasslands. Simultaneously, local households spontaneously developed bottom-up countermeasures. To determine the effects of these processes, we interviewed members of 135 households using a mix of qualitative and quantitative methods. We analyzed the effects on household dependence on local grasslands and on perceptions of the future of grassland use. Our findings show that the implementation of the grassland conservation policies significantly affected household livelihoods, which in turn affected household use of natural assets (primarily the land, their agricultural assets (farming and grazing activities and their financial assets (income and consumption, resulting in fundamental transformation of their lifestyles. The households developed adaptation measures to account for the dependence of their livelihood on local ecosystems by initializing strategies, such as seeking off-farm work, leasing pasture land, increasing purchases of fodder for stall-fed animals and altering their diet and fuel consumption to compensate for their changing livelihoods.

  1. Monitoring soil greenhouse gas emissions from managed grasslands

    Science.gov (United States)

    Díaz-Pinés, Eugenio; Lu, Haiyan; Butterbach-Bahl, Klaus; Kiese, Ralf

    2014-05-01

    Grasslands in Central Europe are of enormous social, ecological and economical importance. They are intensively managed, but the influence of different common practices (i.e. fertilization, harvesting) on the total greenhouse gas budget of grasslands is not fully understood, yet. In addition, it is unknown how these ecosystems will react due to climate change. Increasing temperatures and changing precipitation will likely have an effect on productivity of grasslands and on bio-geo-chemical processes responsible for emissions of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). In the frame of the TERENO Project (www.tereno.net), a long-term observatory has been implemented in the Ammer catchment, southern Germany. Acting as an in situ global change experiment, 36 big lysimeters (1 m2 section, 150 cm height) have been translocated along an altitudinal gradient, including three sites ranging from 600 to 860 meters above sea level. In addition, two treatments have been considered, corresponding to different management intensities. The overall aim of the pre-alpine TERENO observatory is improving our understanding of the consequences of climate change and management on productivity, greenhouse gas balance, soil nutritional status, nutrient leaching and hydrology of grasslands. Two of the sites are equipped with a fully automated measurement system in order to continuously and accurately monitor the soil-atmosphere greenhouse gas exchange. Thus, a stainless steel chamber (1 m2 section, 80 cm height) is controlled by a robotized system. The chamber is hanging on a metal structure which can move both vertically and horizontally, so that the chamber is able to be set onto each of the lysimeters placed on the field. Furthermore, the headspace of the chamber is connected with a gas tube to a Quantum Cascade Laser, which continuously measures CO2, CH4, N2O and H2O mixing ratios. The chamber acts as a static chamber and sets for 15 minutes onto each lysimeter

  2. The response of sward-dwelling arthropod communities to reduced grassland management intensity in pastures

    Directory of Open Access Journals (Sweden)

    Helden Alvin J.

    2015-12-01

    Full Text Available We compared arthropod taxon richness, diversity and community structure of two replicated grassland husbandry experiments to investigate effects of reduced management intensity, as measured by nutrient input levels (390, 224 and 0 kg/ha per year N in one experiment, and 225 and 88 kg/ha per year N in another. Suction sampling was used to collect Araneae, Coleoptera, Hemiptera and Hymenoptera, with Araneae and Coleoptera also sampled with pitfall trapping. Univariate analyses found no significant differences in abundance and species density between treatments. However, with multivariate analysis, there were significant differences in arthropod community structure between treatments in both experiments.

  3. Effects of Erosion from Mounds of Different Termite Genera on Distinct Functional Grassland Types in an African Savannah.

    Science.gov (United States)

    Gosling, Cleo M; Cromsigt, Joris P G M; Mpanza, Nokukhanya; Olff, Han

    A key aspect of savannah vegetation heterogeneity is mosaics formed by two functional grassland types, bunch grasslands, and grazing lawns. We investigated the role of termites, important ecosystem engineers, in creating high-nutrient patches in the form of grazing lawns. Some of the ways termites can contribute to grazing lawn development is through erosion of soil from aboveground mounds to the surrounding soil surface. This may alter the nutrient status of the surrounding soils. We hypothesize that the importance of this erosion varies with termite genera, depending on feeding strategy and mound type. To test this, we simulated erosion by applying mound soil from three termite genera ( Macrotermes , Odontotermes , and Trinervitermes ) in both a field experiment and a greenhouse experiment. In the greenhouse experiment, we found soils with the highest macro nutrient levels (formed by Trinervitermes ) promoted the quality and biomass of both a lawn ( Digitaria longiflora ) and a bunch ( Sporobolus pyramidalis ) grass species. In the field we found that soils with the highest micro nutrient levels (formed by Macrotermes ) showed the largest increase in cover of grazing lawn species. By linking the different nutrient availability of the mounds to the development of different grassland states, we conclude that the presence of termite mounds influences grassland mosaics, but that the type of mound plays a crucial role in determining the nature of the effects.

  4. Data on the solute concentration within the subsurface flows of Little Lost Man Creek in response to a transport experiment, Redwood National Park, northwest California

    Science.gov (United States)

    Zellweger, Gary W.; Kennedy, V.C.; Bencala, K.E.; Avanzino, R.J.; Jackman, A.P.; Triska, F.J.

    1986-01-01

    A solute transport experiment was conducted on a 327-m reach of Little Lost Man Creek, a small stream in Humboldt County, California. Solutes were injected for 20 days. Chloride was used as a conservative tracer; lithium, potassium, and strontium were used as reactive tracers. In addition, nitrate and phosphate were added as biological reactants. Eighteen shallow wells were dug along the length of the study reach, 1-10 m laterally from the edge of the stream. The wells and sites in the stream were monitored for the injected solutes during and after the injection. Solute concentrations in the wells and stream are indicative of transport properties of stream and subsurface channel flow. This report presents the results of the analyses of the well samples and chemical data relevant to the interpretation of hydrological and chemical interaction between the stream and adjacent channel subsurface flows in the streambed. Calculations of the percentage of streamwater in the wellwater were made from conservative tracer measurements. The composition of wellwater ranged from 47% to 100% streamwater with most values above 90%. The time for water to travel from the beginning of the study reach to the wells was approximately three times as great as the travel time in the stream at the same distance down the reach. The three conclusions that can be drawn are (1) water in the stream exchanges extensively with water in the rest of the channel; (2) the interstitial water in the channel gravels achieves almost the same composition as the stream; and (3) under low flow conditions the stream gravels contain a significant portion of the stream volume. Plots of normalized chloride, lithium, and strontium concentrations at three stream sites are included. (Author 's abstract)

  5. California Political Districts

    Data.gov (United States)

    California Natural Resource Agency — This is a series of district layers pertaining to California'spolitical districts, that are derived from the California State Senateand State Assembly information....

  6. Staged invasions across disparate grasslands: effects of seed provenance, consumers and disturbance on productivity and species richness.

    Science.gov (United States)

    Maron, John L; Auge, Harald; Pearson, Dean E; Korell, Lotte; Hensen, Isabell; Suding, Katharine N; Stein, Claudia

    2014-04-01

    Exotic plant invasions are thought to alter productivity and species richness, yet these patterns are typically correlative. Few studies have experimentally invaded sites and asked how addition of novel species influences ecosystem function and community structure and examined the role of competitors and/or consumers in mediating these patterns. We invaded disturbed and undisturbed subplots in and out of rodent exclosures with seeds of native or exotic species in grasslands in Montana, California and Germany. Seed addition enhanced aboveground biomass and species richness compared with no-seeds-added controls, with exotics having disproportionate effects on productivity compared with natives. Disturbance enhanced the effects of seed addition on productivity and species richness, whereas rodents reduced productivity, but only in Germany and California. Our results demonstrate that experimental introduction of novel species can alter ecosystem function and community structure, but that local filters such as competition and herbivory influence the magnitude of these impacts. © 2014 John Wiley & Sons Ltd/CNRS.

  7. Organic vs. conventional grassland management: do (15)N and (13)C isotopic signatures of hay and soil samples differ?

    Science.gov (United States)

    Klaus, Valentin H; Hölzel, Norbert; Prati, Daniel; Schmitt, Barbara; Schöning, Ingo; Schrumpf, Marion; Fischer, Markus; Kleinebecker, Till

    2013-01-01

    Distinguishing organic and conventional products is a major issue of food security and authenticity. Previous studies successfully used stable isotopes to separate organic and conventional products, but up to now, this approach was not tested for organic grassland hay and soil. Moreover, isotopic abundances could be a powerful tool to elucidate differences in ecosystem functioning and driving mechanisms of element cycling in organic and conventional management systems. Here, we studied the δ(15)N and δ(13)C isotopic composition of soil and hay samples of 21 organic and 34 conventional grasslands in two German regions. We also used Δδ(15)N (δ(15)N plant - δ(15)N soil) to characterize nitrogen dynamics. In order to detect temporal trends, isotopic abundances in organic grasslands were related to the time since certification. Furthermore, discriminant analysis was used to test whether the respective management type can be deduced from observed isotopic abundances. Isotopic analyses revealed no significant differences in δ(13)C in hay and δ(15)N in both soil and hay between management types, but showed that δ(13)C abundances were significantly lower in soil of organic compared to conventional grasslands. Δδ(15)N values implied that management types did not substantially differ in nitrogen cycling. Only δ(13)C in soil and hay showed significant negative relationships with the time since certification. Thus, our result suggest that organic grasslands suffered less from drought stress compared to conventional grasslands most likely due to a benefit of higher plant species richness, as previously shown by manipulative biodiversity experiments. Finally, it was possible to correctly classify about two third of the samples according to their management using isotopic abundances in soil and hay. However, as more than half of the organic samples were incorrectly classified, we infer that more research is needed to improve this approach before it can be efficiently

  8. Organic vs. Conventional Grassland Management: Do 15N and 13C Isotopic Signatures of Hay and Soil Samples Differ?

    Science.gov (United States)

    Klaus, Valentin H.; Hölzel, Norbert; Prati, Daniel; Schmitt, Barbara; Schöning, Ingo; Schrumpf, Marion; Fischer, Markus; Kleinebecker, Till

    2013-01-01

    Distinguishing organic and conventional products is a major issue of food security and authenticity. Previous studies successfully used stable isotopes to separate organic and conventional products, but up to now, this approach was not tested for organic grassland hay and soil. Moreover, isotopic abundances could be a powerful tool to elucidate differences in ecosystem functioning and driving mechanisms of element cycling in organic and conventional management systems. Here, we studied the δ15N and δ13C isotopic composition of soil and hay samples of 21 organic and 34 conventional grasslands in two German regions. We also used Δδ15N (δ15N plant - δ15N soil) to characterize nitrogen dynamics. In order to detect temporal trends, isotopic abundances in organic grasslands were related to the time since certification. Furthermore, discriminant analysis was used to test whether the respective management type can be deduced from observed isotopic abundances. Isotopic analyses revealed no significant differences in δ13C in hay and δ15N in both soil and hay between management types, but showed that δ13C abundances were significantly lower in soil of organic compared to conventional grasslands. Δδ15N values implied that management types did not substantially differ in nitrogen cycling. Only δ13C in soil and hay showed significant negative relationships with the time since certification. Thus, our result suggest that organic grasslands suffered less from drought stress compared to conventional grasslands most likely due to a benefit of higher plant species richness, as previously shown by manipulative biodiversity experiments. Finally, it was possible to correctly classify about two third of the samples according to their management using isotopic abundances in soil and hay. However, as more than half of the organic samples were incorrectly classified, we infer that more research is needed to improve this approach before it can be efficiently used in practice

  9. Enhancing the diversity of breeding invertebrates within field margins of intensively managed grassland: Effects of alternative management practices.

    Science.gov (United States)

    Fritch, Rochelle A; Sheridan, Helen; Finn, John A; McCormack, Stephen; Ó hUallacháin, Daire

    2017-11-01

    Severe declines in biodiversity have been well documented for many taxonomic groups due to intensification of agricultural practices. Establishment and appropriate management of arable field margins can improve the diversity and abundance of invertebrate groups; however, there is much less research on field margins within grassland systems. Three grassland field margin treatments (fencing off the existing vegetation "fenced"; fencing with rotavation and natural regeneration "rotavated" and; fencing with rotavation and seeding "seeded") were compared to a grazed control in the adjacent intensively managed pasture. Invertebrates were sampled using emergence traps to investigate species breeding and overwintering within the margins. Using a manipulation experiment, we tested whether the removal of grazing pressure and nutrient inputs would increase the abundance and richness of breeding invertebrates within grassland field margins. We also tested whether field margin establishment treatments, with their different vegetation communities, would change the abundance and richness of breeding invertebrates in the field margins. Exclusion of grazing and nutrient inputs led to increased abundance and richness in nearly all invertebrate groups that we sampled. However, there were more complex effects of field margin establishment treatment on the abundance and richness of invertebrate taxa. Each of the three establishment treatments supported a distinct invertebrate community. The removal of grazing from grassland field margins provided a greater range of overwintering/breeding habitat for invertebrates. We demonstrate the capacity of field margin establishment to increase the abundance and richness in nearly all invertebrate groups in study plots that were located on previously more depauperate areas of intensively managed grassland. These results from grassland field margins provide evidence to support practical actions that can inform Greening (Pillar 1) and agri

  10. Indirect Effects of Energy Development in Grasslands

    Science.gov (United States)

    Duquette, Cameron Albert

    Grassland landscapes in North America are undergoing rapid industrialization due to energy development facilitated by the growing popularity of fracking and horizontal drilling technology. Each year over 3 million hectares are lost from grassland and shrubland habitats to well infrastructure. Direct footprints from energy infrastructure cause impacts to vegetation cover, available cattle forage, carbon sequestration potential, and usable space for wildlife. However, legacy effects from well construction and noise pollution, light pollution, and altered viewsheds have the potential to impact areas beyond this direct footprint, causing additive and persistent changes to nearby grassland function. While these additional areas may be small on a well pad basis, they may have substantial cumulative impacts over time. To investigate these effects via a diversity of mechanisms, we studied the seasonal habitat selection of northern bobwhite (Colinus virginianus, hereafter bobwhite) in an energy-producing landscape to evaluate space use patterns relative to energy infrastructure. Habitat selection was modeled in the breeding and nonbreeding season using resource Utilization functions (RUFs). We then investigated patterns of vegetation, arthropod, and soil characteristics surrounding well pads to assess small scale environmental gradients extending away from drilling pads via a combination of multivariate and univariate techniques (i.e., Nonmetric dimensional scaling and ANOVA). We found minimal avoidance of energy structures by quail, suggesting a tolerance of moderate development levels. All small-scale effects studied except for soil moisture were impacted at the pad itself (P < 0.01). Off-pad impacts to arthropod abundance and biomass were spatially limited to areas close to pads, while vegetation cover was typically lower than the surrounding habitat beyond 10 m of pads. Soil surface temperature was higher at distances close to well pads, and soil moisture was not

  11. Three-dimensional imaging, change detection, and stability assessment during the centerline trench levee seepage experiment using terrestrial light detection and ranging technology, Twitchell Island, California, 2012

    Science.gov (United States)

    Bawden, Gerald W.; Howle, James; Bond, Sandra; Shriro, Michelle; Buck, Peter

    2014-01-01

    A full scale field seepage test was conducted on a north-south trending levee segment of a now bypassed old meander belt on Twitchell Island, California, to understand the effects of live and decaying root systems on levee seepage and slope stability. The field test in May 2012 was centered on a north-south trench with two segments: a shorter control segment and a longer seepage test segment. The complete length of the trench area measured 40.4 meters (m) near the levee centerline with mature trees located on the waterside and landside of the levee flanks. The levee was instrumented with piezometers and tensiometers to measure positive and negative porewater pressures across the levee after the trench was flooded with water and held at a constant hydraulic head during the seepage test—the results from this component of the experiment are not discussed in this report. We collected more than one billion three-dimensional light detection and ranging (lidar) data points before, during, and after the centerline seepage test to assess centimeter-scale stability of the two trees and the levee crown. During the seepage test, the waterside tree toppled (rotated 20.7 degrees) into the water. The landside tree rotated away from the levee by 5 centimeters (cm) at a height of 2 m on the tree. The paved surface of the levee crown had three regions that showed subsidence on the waterside of the trench—discussed as the northern, central, and southern features. The northern feature is an elongate region that subsided 2.1 cm over an area with an average width of 1.35 m that extends 15.8 m parallel to the trench from the northern end of the trench to just north of the trench midpoint, and is associated with a crack 1 cm in height that formed during the seepage test on the trench wall. The central subsidence feature is a semicircular region on the waterside of the trench that subsided by as much as 6.2 cm over an area 3.4 m wide and 11.2 m long. The southern feature is an elongate

  12. The role of grasslands in food security and climate change.

    Science.gov (United States)

    O'Mara, F P

    2012-11-01

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

  13. Optimising stocking rate and grazing management to enhance environmental and production outcomes for native temperate grasslands

    Science.gov (United States)

    Badgery, Warwick; Zhang, Yingjun; Huang, Ding; Broadfoot, Kim; Kemp, David; Mitchell, David

    2015-04-01

    Stocking rate and grazing management can be altered to enhance the sustainable production of grasslands but the relative influence of each has not often been determined for native temperate grasslands. Grazing management can range from seasonal rests through to intensive rotational grazing involving >30 paddocks. In large scale grazing, it can be difficult to segregate the influence of grazing pressure from the timing of utilisation. Moreover, relative grazing pressure can change between years as seasonal conditions influence grassland production compared to the relative constant requirements of animals. This paper reports on two studies in temperate native grasslands of northern China and south eastern Australia that examined stocking rate and regionally relevant grazing management strategies. In China, the grazing experiment involved combinations of a rest, moderate or heavy grazing pressure of sheep in spring, then moderate or heavy grazing in summer and autumn. Moderate grazing pressure at 50% of the current district average, resulted in the better balance between maintaining productive and diverse grasslands, a profitable livestock system, and mitigation of greenhouse gases through increased soil carbon, methane uptake by the soil, and efficient methane emissions per unit of weight gain. Spring rests best maintained a desirable grassland composition, but had few other benefits and reduced livestock productivity due to lower feed quality from grazing later in the season. In Australia, the grazing experiment compared continuous grazing to flexible 4- and 20-paddock rotational grazing systems with sheep. Stocking rates were adjusted between systems biannually based on the average herbage mass of the grassland. No treatment degraded the perennial pasture composition, but ground cover was maintained at higher levels in the 20-paddock system even though this treatment had a higher stocking rate. Overall there was little difference in livestock production (e.g. kg

  14. Grazing reduces soil greenhouse gas fluxes in global grasslands: a meta-analysis

    Science.gov (United States)

    Tang, Shiming; Tian, Dashuan; Niu, Shuli

    2017-04-01

    Grazing causes a worldwide degradation in grassland and likely alters soil greenhouse gas fluxes (GHGs). However, the general patterns of grazing-induced changes in grassland soil GHGs and the underlying mechanisms remain unclear. Thus, we synthesized 63 independent experiments in global grasslands that examined grazing impacts on soil GHGs (CO2, CH4 and N2O). We found that grazing with light or moderate intensity did not significantly influence soil GHGs, but consistently depressed them under heavy grazing, reducing CO2 emission by 10.55%, CH4 uptake by 19.24% and N2O emission by 28.04%. The reduction in soil CO2 was mainly due to decreased activity in roots and microbes (soil respiration per unit root and microbial biomass), which was suppressed by less water availability due to higher soil temperature induced by lower community cover under heavy grazing. N2O emission decreased with grazing-caused decline in soil total N. The inhibitory effect on methanotroph activities by water stress is responsible for the decreased CH4 uptake. Furthermore, grazing duration and precipitation also influenced the direction and magnitude of responses in GHGs fluxes. Overall, our results indicate that the reduction in soil CO2 and N2O emission under heavy grazing is partially compensated by the decrease in CH4 uptake, which is mainly regulated by variations in soil moisture.

  15. NDVI and meteorological data as indicators of the Pampa biome natural grasslands growth

    Directory of Open Access Journals (Sweden)

    Denise Cybis Fontana

    2018-04-01

    Full Text Available ABSTRACT The present study aimed to characterize the dynamics of NDVI and meteorological conditions, relating both to the annual dynamics of biomass accumulation in natural pastures of the Pampa biome as a way of subsidizing growth modeling. Forage accumulation rate data from a long-term experiment, NDVI data from the MODIS images, and meteorological data measured at the surface were used. We verify that the agrometeorological element associated to the accumulation of forage in the natural grasslands is different according to the season, which is typical of the subtropical climate. Winter is the critical season for livestock production due to the lower forage accumulation rate and lower values of NDVI, conditioned by the decrease of solar radiation and air temperature. In the summer, the limiting factor to forage accumulation is the hydric condition. It was also verified that the variability in the growth of grasslands can be associated with the ENSO phenomenon, being the El Niño favorable and the La Niña unfavorable, especially in the spring-summer period. Considering the verified associations, spectral indices combined with agrometeorological elements are recommended to the adjustment of models of forage accumulation in the Pampa biome natural grasslands.

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

    Science.gov (United States)

    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. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. BVOCs emission in a semi-arid grassland under climate warming and nitrogen deposition

    Directory of Open Access Journals (Sweden)

    H. J. Wang

    2012-04-01

    Full Text Available Biogenic volatile organic compounds (BVOCs profoundly affect atmospheric chemistry and ecosystem functioning. BVOCs emission and their responses to global change are still unclear in grasslands, which cover one quarter of the Earth's land surface and are currently undergoing the largest changes. Over two growing seasons, we conducted a field experiment in a semi-arid grassland (Inner Mongolia, China to examine the emission and the responses of BVOCs emissions to warming and nitrogen deposition. The natural emission rate (NER of monoterpene (dominant BVOCs here is 107 ± 16 μg m−2 h−1 in drought 2007, and 266 ± 53 μg m−2 h−1 in wet 2008, respectively. Warming decreased the standard emission factor (SEF by 24% in 2007, while it increased by 43% in 2008. The exacerbated soil moisture loss caused by warming in dry season might be responsible for the decrease of SEF in 2007. A possible threshold of soil moisture (8.2% (v/v, which controls the direction of warming effects on monoterpene emission, existed in the semiarid grassland. Nitrogen deposition decreased the coverage of Artemisia frigida and hence reduced the NER by 24% across the two growing seasons. These results suggest that the grasslands dominated by the extended Artemisia frigida are an important source for BVOCs, while the responses of their emissions to global changes are more uncertain since they depend on multifactorial in-situ conditions.

  18. Seedling responses to water pulses in shrubs with contrasting histories of grassland encroachment.

    Directory of Open Access Journals (Sweden)

    Steven R Woods

    Full Text Available Woody plant encroachment into grasslands has occurred worldwide, but it is unclear why some tree and shrub species have been markedly more successful than others. For example, Prosopis velutina has proliferated in many grasslands of the Sonoran Desert in North America over the past century, while other shrub species with similar growth form and life history, such as Acacia greggii, have not. We conducted a glasshouse experiment to assess whether differences in early seedling development could help explain why one species and not the other came to dominate many Sonoran Desert grasslands. We established eight watering treatments mimicking a range of natural precipitation patterns and harvested seedlings 16 or 17 days after germination. A. greggii had nearly 7 times more seed mass than P. velutina, but P. velutina emerged earlier (by 3.0±0.3 d and grew faster (by 8.7±0.5 mg d⁻¹. Shoot mass at harvest was higher in A. greggii (99±6 mg seedling⁻¹ than in P. velutina (74±2 mg seedling⁻¹, but there was no significant difference in root mass (54±3 and 49±2 mg seedling⁻¹, respectively. Taproot elongation was differentially sensitive to water supply: under the highest initial watering pulse, taproots were 52±19 mm longer in P. velutina than in A. greggii. Enhanced taproot elongation under favorable rainfall conditions could give nascent P. velutina seedlings growth and survivorship advantages by helping reduce competition with grasses and maintain contact with soil water during drought. Conversely, A. greggii's greater investment in mass per seed appeared to provide little return in early seedling growth. We suggest that such differences in recruitment traits and their sensitivities to environmental conditions may help explain ecological differences between species that are highly similar as adults and help identify pivotal drivers of shrub encroachment into grasslands.

  19. Measurement of grassland evaporation using a surface-layer ...

    African Journals Online (AJOL)

    Measurement of grassland evaporation using a surface-layer scintillometer. ... Water SA. Journal Home · ABOUT THIS JOURNAL · Advanced Search ... of soil heat flux and net irradiance, evaporation rates were calculated as a residual of the ...

  20. Ecological mechanisms underlying arthropod species diversity in grasslands.

    Science.gov (United States)

    Joern, Anthony; Laws, Angela N

    2013-01-01

    Arthropods are an important component of grassland systems, contributing significantly to biodiversity and ecosystem structure and function. Climate, fire, and grazing by large herbivores are important drivers in grasslands worldwide. Arthropod responses to these drivers are highly variable and clear patterns are difficult to find, but responses are largely indirect with respect to changes in resources, species interactions, habitat structure, and habitat heterogeneity resulting from interactions among fire, grazing, and climate. Here, we review these ecological mechanisms influencing grassland arthropod diversity. We summarize hypotheses describing species diversity at local and regional scales and then discuss specific factors that may affect arthropod diversity in grassland systems. These factors include direct and indirect effects of grazing, fire, and climate, species interactions, above- and belowground interactions, and landscape-level effects.

  1. Soil Organic Carbon Responses to Forest Expansion on Mountain Grasslands

    DEFF Research Database (Denmark)

    Guidi, Claudia

    . Changes in labile soil C were assessed by carbohydrate and thermal analyses of soil samples and fractions. Forest expansion on mountain grasslands caused a decrease in SOC stocks within the mineral soil. The SOC accumulation within the organic layers following forest establishment could not fully...... and thermally labile to resistant components decreased from grassland to forest successional stages, and corresponded to decreased SOC protection within stable aggregates. This PhD thesis showed that mineral SOC stocks and physically protected SOC fractions decreased following forest expansion on mountain......Grassland abandonment followed by progressive forest expansion is the dominant land-use change in the European Alps. Contrasting trends in soil organic carbon (SOC) stocks have been reported for mountainous regions following forest expansion on grasslands. Moreover, its effects on SOC properties...

  2. Impact intensities of climatic changes on grassland ecosystems in ...

    African Journals Online (AJOL)

    DR. NJ TONUKARI

    2012-03-22

    Mar 22, 2012 ... Construction of the impact intensity model of climatic changes on grassland ecosystem ... the temperature and rainfall (Sun and Mu, 2011). Thus, the study ... of the equation, the study transformed the measurement unit Mu of.

  3. The Experiences of Low-Income Latino/a Students in the California Community College System at a Time of Education Budget Cuts

    Science.gov (United States)

    Chacon, Justin Akers

    2013-01-01

    Budget cuts have reduced courses and student services within California community colleges. This coincides with the growth of low-income Latino male (Latinos) and Latina female (Latinas) student enrollment. Budget cuts have been implemented throughout the system, including in the Extended Opportunity Programs and Services (EOPS), which…

  4. Biodiversity in temperate European grasslands: origin and conservation.

    OpenAIRE

    Pärtel, Meelis; Bruun, Hans Henrik; Sammul, Marek

    2005-01-01

    Northern Europe is in the forest zone, but wild megaherbivores have maintained grass-dominated vegetation here for the last 1.8 million years. Continuity of the grassland biome through glacialinterglacial cycles and connection to steppe vegetation has resulted in the evolution, immigration, and survival of a large number of grassland species. During the last millennia the effect of wild ungulates has been replaced by domestic grazers and hay making, and the persistence of grasslan...

  5. Methods for evaluation of the invasibility of grasslands

    DEFF Research Database (Denmark)

    Strandberg, M. T.; Strandberg, B.; Erneberg, M.

    The number of non-native plant species in Danish dry acidic grasslands was positively correlated with the cover of disturbance in the form of molehills, anthills, mouseholes and erosion due trampling or digging by large herbivores/livestock. Natural disturbance in acidic grassland ecosystems...... not grazed by livestock therefore is important for the occurrence of non-native species, and probably also for the occurrence of a high native floristic diversity....

  6. PV water pumping systems for grassland and farmland conservation

    OpenAIRE

    Campana, Pietro Elia

    2013-01-01

    Grassland degradation is considered as one of the worst environmental and economic problems in China because of the negative impacts on water and food security. The application of the photovoltaic water pumping (PVWP) technology for irrigation is an innovative and sustainable solution to curb the progress of grassland desertification and to promote the conservation of farmland in remote areas. The combination of PVWP with water saving irrigation techniques and the sustainable management of th...

  7. The Eurasian Dry Grassland Group (EDGG in 2016–2017

    Directory of Open Access Journals (Sweden)

    Venn Stephen

    2018-06-01

    Full Text Available This report summarizes the activities and achievements of the Eurasian Dry Grassland Group (EDGG from mid-2016 through to the end of 2017. During this period, the 13th Eurasian Grassland Conference took place in Sighişoara, Romania, and the 14th conference was held in Riga, Latvia. The 10th EDGG Field Workshop on Biodiversity patterns across a precipitation gradient in the Central Apennine mountains was conducted in the Central Apennines, Italy, this time in addition to multi-scale sampling of vascular plants, bryophytes and lichens, also including one animal group (leaf hoppers. Apart from the quarterly issues of its own electronic journal (Bulletin of the Eurasian Dry Grassland Group, EDGG also finalised five grassland-related Special Features/Issues during the past 1.5 years in the following international journals: Applied Vegetation Science, Biodiversity and Conservation, Phytocoenologia, Tuexenia and Hacquetia. Beyond that, EDGG facilitated various national and supra-national vegetationplot databases of grasslands and established its own specialised database for standardised multi-scale plot data of Palaearctic grasslands (GrassPlot.

  8. Impacts of Future Grassland Changes on Surface Climate in Mongolia

    Directory of Open Access Journals (Sweden)

    Fan Zhang

    2013-01-01

    Full Text Available Climate change caused by land use/cover change (LUCC is becoming a hot topic in current global change, especially the changes caused by the grassland degradation. In this paper, based on the baseline underlying surface data of 1993, the predicted underlying surface data which can be derived through overlaying the grassland degradation information to the map of baseline underlying surface, and the atmospheric forcing data of RCP 6.0 from CMIP5, climatological changes caused by future grassland changes for the years 2010–2020 and 2040–2050 with the Weather Research Forecast model (WRF are simulated. The model-based analysis shows that future grassland degradation will significantly result in regional climate change. The grassland degradation in future could lead to an increasing trend of temperature in most areas and corresponding change range of the annual average temperature of −0.1°C–0.4°C, and it will cause a decreasing trend of precipitation and corresponding change range of the annual average precipitation of 10 mm–50 mm. This study identifies lines of evidence for effects of future grassland degradation on regional climate in Mongolia which provides meaningful decision-making information for the development and strategy plan making in Mongolia.

  9. Belowground Carbon Allocation and Plant-Microbial Interactions Drive Resistance and Resilience of Mountain Grassland Communities to Drought

    Science.gov (United States)

    Karlowsky, S.; Augusti, A.; Ingrisch, J.; Hasibeder, R.; Lavorel, S.; Bahn, M.; Gleixner, G.

    2016-12-01

    Belowground carbon allocation (BCA) and plant-microbial interactions are crucial for the functioning of terrestrial ecosystems. Recent research suggests that extreme events can have severe effects on these processes but it is unknown how land use intensity potentially modifies their responses. We studied the resistance and resilience of mountain grassland communities to prolonged drought and investigated the role of plant C allocation and soil microbial communities in mediating drought resistance and immediate recovery. In a common garden experiment we exposed monoliths from an abandoned grassland and a hay meadow to an early summer drought. Two independent 13C pulse labeling experiments were conducted, the first during peak drought and the second during the recovery phase. The 13C incorporation was analyzed in above- and belowground plant parts and in phospho- and neutral lipid fatty acids of soil microorganisms. In addition, a 15N label was added at the rewetting to determine plant N uptake. We found that C uptake, BCA and C transfer to soil microorganisms were less strongly reduced by drought in the abandoned grassland than in the meadow. Moreover, drought induced an increase of arbuscular mycorrhiza fungi (AMF) marker in the abandoned grassland. Nevertheless, C uptake and related parameters were quickly recovered and N uptake increased in the meadow during recovery. Unexpectedly, AMF and their C uptake were generally reduced during recovery, while bacteria increased and quickly recovered C uptake, particularly in the meadow. Our results showed a negative relation between high resistance and fast recovery. The more resistant abandoned grassland plant communities seemed to invest more C below ground and into interactions with AMF during drought, likely to access water through their hyphal network. Conversely, meadow communities invested more C from recent photosynthesis into bacterial communities during recovery, obviously to gain more nutrients for regrowth

  10. Habitat associations of migrating and overwintering grassland birds in Southern Texas

    Science.gov (United States)

    Igl, Lawrence D.; Ballard, Bart M.

    1999-01-01

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

  11. The Effects of Land-Use Change from Grassland to Miscanthus x giganteus on Soil N2O Emissions

    Directory of Open Access Journals (Sweden)

    Michael Williams

    2013-09-01

    Full Text Available A one year field trial was carried out on three adjacent unfertilised plots; an 18 year old grassland, a 14 year old established Miscanthus crop, and a 7 month old newly planted Miscanthus crop. Measurements of N2O, soil temperature, water filled pore space (WFPS, and inorganic nitrogen concentrations, were made every one to two weeks. Soil temperature, WFPS and NO3− and NH4+ concentrations were all found to be significantly affected by land use. Temporal crop effects were also observed in soil inorganic nitrogen dynamics, due in part to C4 litter incorporation into the soil under Miscanthus. Nonetheless, soil N2O fluxes were not significantly affected by land use. Cumulative yearly N2O fluxes were relatively low, 216 ± 163, 613 ± 294, and 377 ± 132 g·N·ha−1·yr−1 from the grassland, newly planted Miscanthus, and established Miscanthus plots respectively, and fell within the range commonly observed for unfertilised grasslands dominated by perennial ryegrass (Lolium perenne. Higher mean cumulative fluxes were measured in the newly planted Miscanthus, which may be linked to a possible unobserved increase immediately after establishment. However, these differences were not statistically significant. Based on the results of this experiment, land-use change from grassland to Miscanthus will have a neutral impact on medium to long-term N2O emissions.

  12. The effects of warming and nitrogen addition on soil nitrogen cycling in a temperate grassland, northeastern China.

    Directory of Open Access Journals (Sweden)

    Lin-Na Ma

    Full Text Available Both climate warming and atmospheric nitrogen (N deposition are predicted to affect soil N cycling in terrestrial biomes over the next century. However, the interactive effects of warming and N deposition on soil N mineralization in temperate grasslands are poorly understood.A field manipulation experiment was conducted to examine the effects of warming and N addition on soil N cycling in a temperate grassland of northeastern China from 2007 to 2009. Soil samples were incubated at a constant temperature and moisture, from samples collected in the field. The results showed that both warming and N addition significantly stimulated soil net N mineralization rate and net nitrification rate. Combined warming and N addition caused an interactive effect on N mineralization, which could be explained by the relative shift of soil microbial community structure because of fungal biomass increase and strong plant uptake of added N due to warming. Irrespective of strong intra- and inter-annual variations in soil N mineralization, the responses of N mineralization to warming and N addition did not change during the three growing seasons, suggesting independence of warming and N responses of N mineralization from precipitation variations in the temperate grassland.Interactions between climate warming and N deposition on soil N cycling were significant. These findings will improve our understanding on the response of soil N cycling to the simultaneous climate change drivers in temperate grassland ecosystem.

  13. Improvement of native grassland by legumes introduction and tillage techniques

    Directory of Open Access Journals (Sweden)

    Syamsu Bahar

    1999-10-01

    Full Text Available A factorial design using three species of legumes (Siratro, Centro and Stylo and three different of tillage techniques (no-tillage, minimum tillage and total tillage was applied in this experiment. The results showed that there was no interaction between species and tillage techniques. There was significant reductions on bulk density from 1.23±0.03 g/cm3 (no-tillage to 1.07±0.02 g/cm3 (minimum tillage and 1.05±0.03 g/cm3 (total tillage. Also reductions on penetration resistance from 17.47±3.84 kg/cm2 (no-tillage to 3.31±0.43 kg/cm2 (minimum tillage and 3.19±0.45 kg/cm2 (total tillage. Otherwise significant increasing on aeration porosity from 12.80±0.80% vol. (no-tillage to 21.70±0.95% vol. (minimum tillage and 20.70±0.35% vol. (total tillage. Total tillage gives increased dry matter yield. Also both total tillage and minimum tillage give yields with a higher percentage of legumes compared with no-tillage. It was concluded that total tillage and minimum tillage could be used for improving native grassland.

  14. Priming of soil carbon decomposition in two inner Mongolia grassland soils following sheep dung addition: A study using13C natural abundance approach

    DEFF Research Database (Denmark)

    Ma, Xiuzhi; Ambus, Per; Wang, Shiping

    2013-01-01

    To investigate the effect of sheep dung on soil carbon (C) sequestration, a 152 days incubation experiment was conducted with soils from two different Inner Mongolian grasslands, i.e. a Leymus chinensis dominated grassland representing the climax community (2.1% organic matter content) and a heav......To investigate the effect of sheep dung on soil carbon (C) sequestration, a 152 days incubation experiment was conducted with soils from two different Inner Mongolian grasslands, i.e. a Leymus chinensis dominated grassland representing the climax community (2.1% organic matter content......) and a heavily degraded Artemisia frigida dominated community (1.3% organic matter content). Dung was collected from sheep either fed on L. chinensis (C3 plant with δ13C = -26.8‰; dung δ13C = -26.2‰) or Cleistogenes squarrosa (C4 plant with δ13C = -14.6‰; dung δ13C = -15.7‰). Fresh C3 and C4 sheep dung was mixed......-amended controls. In both grassland soils, ca. 60% of the evolved CO2 originated from the decomposing sheep dung and 40% from the native soil C. Priming effects of soil C decomposition were observed in both soils, i.e. 1.4 g and 1.6 g additional soil C kg-1 dry soil had been emitted as CO2 for the L. chinensis...

  15. Social and Ecological Factors Influencing Attitudes Toward the Application of High-Intensity Prescribed Burns to Restore Fire Adapted Grassland Ecosystems

    Directory of Open Access Journals (Sweden)

    David Toledo

    2013-12-01

    Full Text Available Fire suppression in grassland systems that are adapted to episodic fire has contributed to the recruitment of woody species in grasslands worldwide. Even though the ecology of restoring these fire prone systems back to grassland states is becoming clearer, a major hurdle to the reintroduction of historic fires at a landscape scale is its social acceptability. Despite the growing body of literature on the social aspects of fire, an understanding of the human dimensions of applying high-intensity prescribed burns in grassland and savanna systems is lacking. We used structural equation modeling to examine how landowners' attitudes toward high-intensity prescribed burns are affected by previous experience with burning, perceptions of brush encroachment, land condition, proximity constraints, risk orientation, fire management knowledge and skill, access to fire management equipment, and subjective norms. Our results suggest that experience, risk taking orientation, and especially social norms, i.e., perceived support from others, when implementing prescribed burns play an important role in determining the attitudes of landowners toward the use of high-intensity prescribed burns. Concern over lack of skill, knowledge, and insufficient resources have a moderately negative effect on these attitudes. Our results highlight the importance of targeted engagement strategies to address risk perceptions, subjective norms, and landowner's concerns. With these concerns allayed, it is possible to increase the adoption of high-intensity prescribed burns that lead to landscape-scale grassland restoration and conservation.

  16. Supplemental Environmental Assessment Anti-Terrorism/Force Protection Upgrades at Beale Air Force Base, California

    Science.gov (United States)

    2010-05-01

    anatum) • California black rail (Laterallus jamaicensis coturniculus) • Greater sandhill crane (Grus canadensis tabida) • Bank swallow ( Riparia ... riparia ) The Swainson’s hawk prefers to nest in riparian areas with isolated trees bordered by open foraging habitat (grasslands, agricultural lands...Fault Zones . The projects will not be located on soils that are unstable or expansive, and will not cause seismic activities or landslides. The

  17. Field experiences in the prevention of toxic effects for cyanide and mercury in the Mining District of Vetas-California, Santander

    International Nuclear Information System (INIS)

    Chaparro Garnica, Helkin Claudio Martin

    2004-01-01

    human body for inhalation, ingestion, and for contact; in the area in mention, it is particularly possible the intoxication for vapors of mercury or quicksilver due to the absolute familiarity with the toxic on the part of the almost the population's entirety, from very early age, and for ancestral practical it is inadequate as they are by hand the manipulation of the amalgams clean and it burns it of the fluffs (amalgamates of gold and mercury) in the own vent of the homelike kitchen, or in fathoms inside of or outside of the house but in any event with direct exhibition of the whole family nucleus to the vapors of the quicksilver, situation that is increased by the fact that, contrary to the cyanide that produces the death almost immediately, the mercury in general causes an insidious square of chronic intoxication that those directly affected, attribute to all less ones to the toxic, although the sharp and chronic squares are grateful as professional illness for the Work ministry and of the social protection. It is calculated that around 2500 people of the Mining District Vetas-California has direct relationship or insinuation with the indexed pollutants and therefore it became necessary to approach the problem like part of the technological re-conversion promoted by the Project Surata that is developed by the auspice of the German BGR and in agreement with the aqueduct enterprise of Bucaramanga, the CDMB and the government of the department. The experiences related this report, pick up the activities developed by a compound team by 2 doctors, a driver and 3 field coordinators, including a sociologist, by means of which was looked for to inform to the most representative focal groups in the district, that is, the own miners, students, housewives, community mothers and municipal authorities on the risks of sharp intoxication and chronicle for the inadequate manipulation of mercury and cyanide, by means of technical of high impact as the presentation of clinical cases

  18. Different responses of ecosystem carbon exchange to warming in three types of alpine grassland on the central Qinghai-Tibetan Plateau.

    Science.gov (United States)

    Ganjurjav, Hasbagan; Hu, Guozheng; Wan, Yunfan; Li, Yue; Danjiu, Luobu; Gao, Qingzhu

    2018-02-01

    Climate is a driver of terrestrial ecosystem carbon exchange, which is an important product of ecosystem function. The Qinghai-Tibetan Plateau has recently been subjected to a marked increase in temperature as a consequence of global warming. To explore the effects of warming on carbon exchange in grassland ecosystems, we conducted a whole-year warming experiment between 2012 and 2014 using open-top chambers placed in an alpine meadow, an alpine steppe, and a cultivated grassland on the central Qinghai-Tibetan Plateau. We measured the gross primary productivity, net ecosystem CO 2 exchange (NEE), ecosystem respiration, and soil respiration using a chamber-based method during the growing season. The results show that after 3 years of warming, there was significant stimulation of carbon assimilation and emission in the alpine meadow, but both these processes declined in the alpine steppe and the cultivated grassland. Under warming conditions, the soil water content was more important in stimulating ecosystem carbon exchange in the meadow and cultivated grassland than was soil temperature. In the steppe, the soil temperature was negatively correlated with ecosystem carbon exchange. We found that the ambient soil water content was significantly correlated with the magnitude of warming-induced change in NEE. Under high soil moisture condition, warming has a significant positive effect on NEE, while it has a negative effect under low soil moisture condition. Our results highlight that the NEE in steppe and cultivated grassland have negative responses to warming; after reclamation, the natural meadow would subject to loose more C in warmer condition. Therefore, under future warmer condition, the overextension of cultivated grassland should be avoided and scientific planning of cultivated grassland should be achieved.

  19. Responses of nocturnal rodents to shrub encroachment in Banni grasslands, Gujarat, India

    Science.gov (United States)

    Jayadevan, A.

    2016-12-01

    Shrub encroachment is one of the greatest threats to grasslands globally. These woodlands can strongly influence the behaviour of small mammals adapted to more open habitats, which rely on high visibility for early detection of predators. In semi-arid grasslands, rodents are considered keystone species. Although shrub encroachment is known to negatively affect rodent assemblages, its impact on the foraging behaviour of rodents, which is known to vary in response to risky situations, is unknown. Understanding whether shrub encroachment alters such antipredator behaviour is important as antipredator behaviour can alter the distribution, abundance and ultimately, survival of prey species. In this study, I explored the effects of shrub encroachment on the foraging behaviour of nocturnal rodent communities in the Banni grasslands, India. I examined foraging behaviour, quantified using the giving-up density (GUD) framework and the number of rodent crossings around food patches, in two habitats that differed in the extent of shrub encroachment. Under the GUD framework, the amount of food left behind by a forager in a food patch reflects the costs of feeding at the patch. Higher GUDs imply higher foraging costs. I also investigated how removal of an invasive woody plant, Prosopis juliflora would affect foraging behaviour of nocturnal rodents. High shrub encroachment was associated with higher foraging costs (higher GUDs) and lower activity than the sparsely wooded habitat, likely due to low visibility in the densely wooded habitat. The dense habitat also supported a higher richness and relative abundance of generalist rodents than the sparse habitat, likely due to the increased heterogeneity of the habitat. The tree removal experiment revealed that rodents had lower GUDs (i.e., low foraging costs) after the event of tree cutting. This may be due to the reduction of cover in the habitat, leading to higher visibility and lower predation risk. My results suggest that shrub

  20. Effects of smectite on the oil-expulsion efficiency of the Kreyenhagen Shale, San Joaquin Basin, California, based on hydrous-pyrolysis experiments

    Science.gov (United States)

    Lewan, Michael D.; Dolan, Michael P.; Curtis, John B.

    2014-01-01

    The amount of oil that maturing source rocks expel is expressed as their expulsion efficiency, which is usually stated in milligrams of expelled oil per gram of original total organic carbon (TOCO). Oil-expulsion efficiency can be determined by heating thermally immature source rocks in the presence of liquid water (i.e., hydrous pyrolysis) at temperatures between 350°C and 365°C for 72 hr. This pyrolysis method generates oil that is compositionally similar to natural crude oil and expels it by processes operative in the subsurface. Consequently, hydrous pyrolysis provides a means to determine oil-expulsion efficiencies and the rock properties that influence them. Smectite in source rocks has previously been considered to promote oil generation and expulsion and is the focus of this hydrous-pyrolysis study involving a representative sample of smectite-rich source rock from the Eocene Kreyenhagen Shale in the San Joaquin Basin of California. Smectite is the major clay mineral (31 wt. %) in this thermally immature sample, which contains 9.4 wt. % total organic carbon (TOC) comprised of type II kerogen. Compared to other immature source rocks that lack smectite as their major clay mineral, the expulsion efficiency of the Kreyenhagen Shale was significantly lower. The expulsion efficiency of the Kreyenhagen whole rock was reduced 88% compared to that of its isolated kerogen. This significant reduction is attributed to bitumen impregnating the smectite interlayers in addition to the rock matrix. Within the interlayers, much of the bitumen is converted to pyrobitumen through crosslinking instead of oil through thermal cracking. As a result, smectite does not promote oil generation but inhibits it. Bitumen impregnation of the rock matrix and smectite interlayers results in the rock pore system changing from water wet to bitumen wet. This change prevents potassium ion (K+) transfer and dissolution and precipitation reactions needed for the conversion of smectite to

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

    Science.gov (United States)

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

    2018-04-01

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

  2. Establishing Sphagnum cultures on bog grassland, cut-over bogs, and floating mats: procedures, costs and area potential in Germany

    Directory of Open Access Journals (Sweden)

    S. Wichmann

    2017-04-01

    Full Text Available Sphagnum biomass is valued as a high-quality constituent of horticultural growing media. The cultivation of Sphagnum (peatmoss was tested successfully on peat soil and on artificial mats floating on acidic water bodies. But whether Sphagnum farming is economically feasible is unclear. Drawing on experience gained during four research projects in Germany we compared the procedures, costs and area potential for establishing large-scale Sphagnum cultures. Establishment costs were clearly lower for soil-based cultivation (€8.35 m-2 to €12.80 m 2 than for water-based cultivation (€17.34 m-2 to €21.43 m-2. Relating costs to the predicted dry mass yield over the total cultivation time resulted in values of €1,723 t-1 on cut-over bog, €2,646 t-1 on former bog grassland, €9,625 t -1 on floating mats without pre-cultivation and €11,833 t-1 on pre-cultivated Sphagnum mats. The high production costs of the mats (without pre-cultivation 54 % and with pre-cultivation 63 % of total costs resulted in the highest overall costs. In the case of soil-based Sphagnum cultures, the costs of purchasing Sphagnum diaspores were most influential (on bog grassland 46 % and on cut-over bog 71 % of total costs. The lowest costs relate to cut-over bog because of the smaller effort required for site preparation compared to taking off the topsoil of former bog grassland and the limited costs for the assumed irrigation system. In the case of former bog grassland, the high investment costs for the project-specific automatic water management boosted the establishment costs. Taking into account potential savings on the irrigation system and the high area potential, bog grassland emerges as the most promising land category for Sphagnum farming in Germany.

  3. Ecology and Conservation of Steppes and Semi-Natural Grasslands

    Directory of Open Access Journals (Sweden)

    Valkó Orsolya

    2016-12-01

    Full Text Available Palaearctic grasslands encompass a diverse variety of habitats, many of high nature value and vulnerability. The main challenges are climate-change, land-use change, agricultural intensification and abandonment. Many measures are in place to address these challenges, through restoration and appropriate management, though more work is necessary. We present eight studies from China/Germany, Greece, Kazakhstan, Russia and Ukraine. The papers cover a wide range of grassland and steppe habitats and cover vegetation ecology, syntaxonomy and zoology. We also conducted a systematic search on steppe and grassland diversity. The greatest number of studies was from China, followed by Germany and England. We conclude that the amount of research being carried out on Eurasian grasslands is inadequate considering their high levels of biodiversity and vulnerability. We hope to encourage readers to address current major challenges, such as how to manage grasslands for the benefit of diverse taxa, to ensure that conservation initiatives concentrate on sites where there is good potential for success and for the generation of realistic and viable conservation strategies.

  4. Classification of Grassland Successional Stages Using Airborne Hyperspectral Imagery

    Directory of Open Access Journals (Sweden)

    Thomas Möckel

    2014-08-01

    Full Text Available Plant communities differ in their species composition, and, thus, also in their functional trait composition, at different stages in the succession from arable fields to grazed grassland. We examine whether aerial hyperspectral (414–2501 nm remote sensing can be used to discriminate between grazed vegetation belonging to different grassland successional stages. Vascular plant species were recorded in 104.1 m2 plots on the island of Öland (Sweden and the functional properties of the plant species recorded in the plots were characterized in terms of the ground-cover of grasses, specific leaf area and Ellenberg indicator values. Plots were assigned to three different grassland age-classes, representing 5–15, 16–50 and >50 years of grazing management. Partial least squares discriminant analysis models were used to compare classifications based on aerial hyperspectral data with the age-class classification. The remote sensing data successfully classified the plots into age-classes: the overall classification accuracy was higher for a model based on a pre-selected set of wavebands (85%, Kappa statistic value = 0.77 than one using the full set of wavebands (77%, Kappa statistic value = 0.65. Our results show that nutrient availability and grass cover differences between grassland age-classes are detectable by spectral imaging. These techniques may potentially be used for mapping the spatial distribution of grassland habitats at different successional stages.

  5. Grassland ecology and population growth: striking a balance.

    Science.gov (United States)

    Hou, D; Duan, C; Zhang, D

    2000-06-01

    Degradation of forest and grasslands in western China attributes to the soil erosion and desertification in the country. Researchers have established that the primary reason for the degradation of grasslands is overgrazing, which in turn is caused by a number of factors, including over-population and over-reliance on animal husbandry. In addition, the existing administrative system has also proved ineffective in ensuring sustainable development. On contrary, many local governments even encourage exploitative development of grassland; thus, localities opened up grassland for growing crops in an effort to increase income. According to estimates, degraded grassland accounts for more than one-third of utilizable acreage and another one-third suffers from a profusion of rats and pests. To redress the situation, central government should implement strategies in achieving sustainable development, such as providing banking and tax incentives for the development of the secondary and tertiary industries, and supporting education and training of youths from herding areas. Moreover, government should increase spending on infrastructural construction and ecological preservation. Finally, the family planning program needs to be enforced to control population growth and improve the quality of peoples¿ lives.

  6. Are land use and short time climate change effective on soil carbon compositions and their relationships with soil properties in alpine grassland ecosystems on Qinghai-Tibetan Plateau?

    Science.gov (United States)

    Zhao, Zhenzhen; Dong, Shikui; Jiang, Xiaoman; Zhao, Jinbo; Liu, Shiliang; Yang, Mingyue; Han, Yuhui; Sha, Wei

    2018-06-01

    Fencing and grass plantation are two key interventions to preserve the degraded grassland on the Qinghai-Tibetan Plateau (QTP). Climate warming and N deposition have substantially affected the alpine grassland ecosystems. However, molecular composition of soil organic carbon (SOC), the indicator of degradation of SOC, and its responses to climate change are still largely unclear. In this study, we conducted the experiments in three types of land use on the QTP: alpine meadow (AM), alpine steppe (AS), and cultivated grassland (CG) under 2°C climatic warming, 5 levels of nitrogen deposition rates at 8, 24, 40, 56, and 72kg N ha -1 year -1 , as well as a combination of climatic warming and N deposition (8kg N ha -1 year -1 ). Our findings indicate that all three types of land use were dominated by O-alkyl carbon. The alkyl/O-alkyl ratio, aromaticity and hydrophobicity index of the CG were larger than those of the AM and AS, and this difference was generally stable under different treatments. Most of the SOC in the alpine grasslands was derived from fresh plants, and the carbon in the CG was more stable than that in the AM and AS. The compositions of all the alpine ecosystems were stable under short-term climatic changes, suggesting the short-term climate warming and nitrogen deposition likely did not affect the molecular composition of the SOC in the restored grasslands. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

  8. California Condor Critical Habitat

    Data.gov (United States)

    California Natural Resource Agency — These Data identify (in general) the areas where critical habitat for the California Condor occur. Critical habitat for the species consists of the following 10...

  9. Teale California shoreline

    Data.gov (United States)

    California Natural Resource Agency — California Spatial Information System (CaSIL) is a project designed to improve access to geo-spatial and geo-spatial related data information throughout the state of...

  10. California Workforce: California Faces a Skills Gap

    Science.gov (United States)

    Public Policy Institute of California, 2011

    2011-01-01

    California's education system is not keeping up with the changing demands of the state's economy--soon, California will face a shortage of skilled workers. Projections to 2025 suggest that the economy will continue to need more and more highly educated workers, but that the state will not be able to meet that demand. If current trends persist,…

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

    Science.gov (United States)

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

    2015-11-01

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

  12. Sacramento Metropolitan Area, California

    Science.gov (United States)

    1992-02-01

    addition, several Federal candidate species, the California Hibiscus , California tiger salamander, Sacramento Anthicid Beetle, Sacramento Valley tiger...Board, California Waste Management Board, and Department of Health Services contribute to this list. The Yolo County Health Services Agency maintains and...operation and maintenance of the completed recreational facility. Recreation development is limited to project lands unless health and safety

  13. Effects of different diets on utilization of nitrogen from cattle slurry applied to grassland on a sandy soil in the Netherlands

    NARCIS (Netherlands)

    Reijs, J.W.; Sonneveld, M.P.W.; Sorensen, P.; Schils, R.L.M.; Groot, J.C.J.; Lantinga, E.A.

    2007-01-01

    Dietary adjustments have been suggested as a means to reduce N losses from dairy systems. Differences in fertilizing value of dairy slurry as a result of dietary adjustments were evaluated in a 1-year grassland experiment and by long-term modelling. Slurry composition of non-lactating dairy cows was

  14. Modeling effects of conservation grassland losses on amphibian habitat

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

    Gerald J. Gottfried

    2004-01-01

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

  16. Resilience and stability of the grasslands of the Transkei | B | African ...

    African Journals Online (AJOL)

    In spite of very high stocking rates the grasslands of Transkei still have in many areas a high cover and many climax species. The concepts of resilience and stability are used in an attempt to explain dynamics of the grasslands. Keywords: resiliences|stabilities|grasslands|Transkei|stocking rates|basal covers|grass ...

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2012-01-01

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

  19. Effects of haying on breeding birds in CRP grasslands

    Science.gov (United States)

    Igl, Lawrence D.; Johnson, Douglas H.

    2016-01-01

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

  20. Experiencias de mujeres mexicanas migrantes indocumentadas en California, Estados Unidos, en su acceso a los servicios de salud sexual y reproductiva: estudio de caso Experiências de mulheres mexicanas migrantes sem documentação na Califórnia, Estados Unidos, no acesso aos serviços de saúde sexual e reprodutiva: estudo de caso Experiences of undocumented Mexican migrant women when accessing sexual and reproductive health services in California, USA: a case study

    Directory of Open Access Journals (Sweden)

    Sandra G. García

    2013-05-01

    Full Text Available El objetivo de este estudio fue conocer la experiencia de mujeres mexicanas migrantes en California, Estados Unidos, en torno a la utilización de los servicios formales de salud para resolver problemas relacionados con su salud sexual y reproductiva. El diseño fue cualitativo, con enfoque teórico metodológico de antropología interpretativa. Las técnicas utilizadas fueron historias de vida con mujeres usuarias de los servicios de salud en California y entrevistas breves con informantes clave. Se encontraron tres tipos de barreras principales para el acceso al sistema de salud: condición migratoria, idioma y género. Los tiempos de espera, actitudes discriminatorias y costo del servicio se expresaron como características que más incomodaron a las migrantes. La percepción de calidad de atención estuvo relacionada con la condición de ilegalidad migratoria. La red de apoyo tanto en México, como en California, colabora en la resolución de enfermedades. Se debe incorporar la perspectiva intercultural en los servicios.O objetivo deste estudo foi conhecer a experiência de mulheres imigrantes mexicanas na Califórnia, Estados Unidos, sobre a utilização de serviços formais de saúde para resolver problemas relacionados com a saúde sexual e reprodutiva. O desenho foi qualitativo, com enfoque teórico-metodológico da Antropologia Interpretativa. As técnicas utilizadas foram relatos de histórias de vida de mulheres usuárias dos serviços de saúde na Califórnia e entrevistas breves com informantes-chave. Encontraram-se três tipos de barreiras principais para o acesso ao serviço de saúde: condições de imigração, idioma e gênero. Tempo de espera, atitudes discriminatórias e custo do serviço foram as características que mais incomodaram as imigrantes. A percepção de qualidade da atenção esteve relacionada com a condição de ilegalidade migratória. A rede de apoio, tanto no México quanto na Califórnia, colabora na resolu

  1. Controls upon microbial accessibility to soil organic matter following woody plant encroachment into grasslands

    Science.gov (United States)

    Creamer, C. A.; Boutton, T. W.; Filley, T. R.

    2009-12-01

    Woody plant encroachment (WPE) into savannas and grasslands is a global phenomenon that alters soil organic matter (SOM) dynamics through changes in litter quality and quantity, soil structure, microbial ecology, and soil hydrology. To elucidate the controls upon microbial accessibility to SOM, bulk soils from a chronosequence of progressive WPE into native grasslands at the Texas A&M Agricultural Experimental Station La Copita Research Area were incubated for one year. The quantity and stable carbon isotope composition of respired CO2, plant biopolymer chemistry in SOM, and microbial community structure were tracked. Respiration rates declined steadily over the course of the experiment with 15-25% of the total CO2 respired released in the first month of incubation. Between 8 and 18% of the total carbon was mineralized to CO2 throughout the incubation. After day 84 a significantly (p evidence of enhanced carbon stabilization in these respiration experiments. In fact, a greater proportion of total carbon was lost from the soil of mature woody stands than from young stands, suggesting carbon accumulation observed with WPE may be due to greater input rates or microbial dynamics not captured in the laboratory incubation. A cluster approximately 34 years in age represents a transition point in WPE where respiration dynamics become distinct between grassland and wooded elements. By day 84 of the incubation CO2 respired from all soils was depleted with respect to bulk SOM (1.5 to 5‰) and this pattern remained for the rest of the incubation. As the depletion of CO2 relative to bulk SOM was observed in grassland and cluster soils, we hypothesized the depleted signature resulted from the utilization of depleted biopolymers, specifically lignin, cutin and suberin, as hypothesized by others. Quantitative and isotopic comparisons of these monomers prior to and following the incubation will determine if selective compound utilization is a reason for this depletion. The results

  2. Sudden changes in environmental conditions do not increase invasion risk in grassland

    Science.gov (United States)

    Ruprecht, Eszter; Fenesi, Annamária; Nijs, Ivan

    2013-02-01

    After direct habitat transformation, biological invasions are considered to be the second most important threat to biodiversity. A better understanding of the factors affecting invasion success in new areas is crucial, and may provide insight into potential control actions. We hypothesized that invasion risk increases in habitats undergoing a sudden change in the disturbance regime or environmental conditions. For testing this assumption we initiated a seed sowing experiment while introducing two novel treatments, mowing twice and fertilizer application, in two grassland sites (one dryer and one mesic) in Romania. The seeds of two invasive species, Solidago canadensis and Rudbeckia laciniata, and two resident natives of similar seed sizes, life-forms and strategies were sowed in treated and control plots, and seed germination, seedling establishment and growth were followed during four months. Contrary to our expectations, there was no difference in the treatment effects on seed germination and seedling establishment between species, while there was on seedling vigour of the larger seeded species in the dryer grassland site, where the native had a higher performance especially in increased nutrient conditions. Indifferently from applied treatments, invasive species had greater cumulative germination in the mesic site, while natives were far more successful in seedling establishment in the drier site. At the same time, seed size was found to be a very important factor explaining germination and establishment success, with large seeded species outperforming small seeded species in any circumstances. Our results call the attention upon management interventions in mesic, productive grassland sites opening colonization windows for the recruitment of those invasive species of which ecological requirements correspond to local environmental conditions.

  3. Effects of hay management and native species sowing on grassland community structure, biomass, and restoration.

    Science.gov (United States)

    Foster, Bryan L; Kindscher, Kelly; Houseman, Greg R; Murphy, Cheryl A

    2009-10-01

    Prairie hay meadows are important reservoirs of grassland biodiversity in the tallgrass prairie regions of the central United States and are the object of increasing attention for conservation and restoration. In addition, there is growing interest in the potential use of such low-input, high-diversity (LIHD) native grasslands for biofuel production. The uplands of eastern Kansas, USA, which prior to European settlement were dominated by tallgrass prairie, are currently utilized for intensive agriculture or exist in a state of abandonment from agriculture. The dominant grasslands in the region are currently high-input, low-diversity (HILD) hay fields seeded to introduced C3 hay grasses. We present results from a long-term experiment conducted in a recently abandoned HILD hay field in eastern Kansas to evaluate effects of fertilization, haying, and native species sowing on community dynamics, biomass, and potential for restoration to native LIHD hay meadow. Fertilized plots maintained dominance by introduced grasses, maintained low diversity, and were largely resistant to colonization throughout the study. Non-fertilized plots exhibited rapid successional turnover, increased diversity, and increased abundance of C4 grasses over time. Haying led to modest changes in species composition and lessened the negative impact of fertilization on diversity. In non-fertilized plots, sowing increased representation by native species and increased diversity, successional turnover, and biomass production. Our results support the shifting limitations hypothesis of community organization and highlight the importance of species pools and seed limitations in constraining successional turnover, community structure, and ecosystem productivity under conditions of low fertility. Our findings also indicate that several biological and functional aspects of LIHD hay meadows can be restored from abandoned HILD hay fields by ceasing fertilization and reintroducing native species through

  4. Biomass production in experimental grasslands of different species richness during three years of climate warming

    Science.gov (United States)

    de Boeck, H. J.; Lemmens, C. M. H. M.; Zavalloni, C.; Gielen, B.; Malchair, S.; Carnol, M.; Merckx, R.; van den Berge, J.; Ceulemans, R.; Nijs, I.

    2008-04-01

    Here we report on the single and combined impacts of climate warming and species richness on the biomass production in experimental grassland communities. Projections of a future warmer climate have stimulated studies on the response of terrestrial ecosystems to this global change. Experiments have likewise addressed the importance of species numbers for ecosystem functioning. There is, however, little knowledge on the interplay between warming and species richness. During three years, we grew experimental plant communities containing one, three or nine grassland species in 12 sunlit, climate-controlled chambers in Wilrijk, Belgium. Half of these chambers were exposed to ambient air temperatures (unheated), while the other half were warmed by 3°C (heated). Equal amounts of water were added to heated and unheated communities, so that warming would imply drier soils if evapotranspiration was higher. Biomass production was decreased due to warming, both aboveground (-29%) and belowground (-25%), as negative impacts of increased heat and drought stress in summer prevailed. Complementarity effects, likely mostly through both increased aboveground spatial complementarity and facilitative effects of legumes, led to higher shoot and root biomass in multi-species communities, regardless of the induced warming. Surprisingly, warming suppressed productivity the most in 9-species communities, which may be attributed to negative impacts of intense interspecific competition for resources under conditions of high abiotic stress. Our results suggest that warming and the associated soil drying could reduce primary production in many temperate grasslands, and that this will not necessarily be mitigated by efforts to maintain or increase species richness.

  5. Elevated CO2 and water addition enhance nitrogen turnover in grassland plants with implications for temporal stability.

    Science.gov (United States)

    Dijkstra, Feike A; Carrillo, Yolima; Blumenthal, Dana M; Mueller, Kevin E; LeCain, Dan R; Morgan, Jack A; Zelikova, Tamara J; Williams, David G; Follett, Ronald F; Pendall, Elise

    2018-05-01

    Temporal variation in soil nitrogen (N) availability affects growth of grassland communities that differ in their use and reuse of N. In a 7-year-long climate change experiment in a semi-arid grassland, the temporal stability of plant biomass production varied with plant N turnover (reliance on externally acquired N relative to internally recycled N). Species with high N turnover were less stable in time compared to species with low N turnover. In contrast, N turnover at the community level was positively associated with asynchrony in biomass production, which in turn increased community temporal stability. Elevated CO 2 and summer irrigation, but not warming, enhanced community N turnover and stability, possibly because treatments promoted greater abundance of species with high N turnover. Our study highlights the importance of plant N turnover for determining the temporal stability of individual species and plant communities affected by climate change. © 2018 John Wiley & Sons Ltd/CNRS.

  6. Initial Soil Organic Matter Content Influences the Storage and Turnover of Litter-, Root- and Soil Carbon in Grasslands

    Science.gov (United States)

    Liu, L.; Xu, S.; Li, P.; Sayer, E. J.

    2017-12-01

    Grassland degradation is a worldwide problem that often leads to substantial loss of soil organic matter (SOM). Understanding how SOM content influences the stabilization of plant carbon (C) to form soil C is important to evaluate the potential of degraded grasslands to sequester additional C. We conducted a greenhouse experiment using C3 soils with six levels of SOM content and planted the C4 grass Cleistogenes squarrosa and/or added its litter to investigate how SOM content regulates the storage of new soil C derived from litter and roots, the decomposition of extant soil C, and the formation of soil aggregates. We found that microbial biomass carbon (MBC) increased with SOM content, and increased the mineralization of litter C. Both litter addition and planted treatments increased the amount of new C inputs to soil. However, litter addition had no significant impacts on the mineralization of extant soil C, but the presence of living roots significantly accelerated it. Thus, by the end of the experiment, soil C content was significantly higher in the litter addition treatments, but was not affected by planted treatments. The soil macroaggregate fraction increased with SOM content and was positively related to MBC. Overall, our study suggests that as SOM content increases, plant growth and soil microbes become more active, which allows microbes to process more plant-derived C and increases new soil C formation. The interactions between SOM content and plant C inputs should be considered when evaluating soil C turnover in degraded grasslands.

  7. Using plant functional traits to guide restoration: A case study in California coastal grassland

    DEFF Research Database (Denmark)

    Sandel, Brody Steven; Corbin, Jeffrey; Krupa, Monica

    2011-01-01

    Restoration ecology can benefit greatly from developments in trait-based ecology that enable improved predictions of how the composition of plant communities will respond to changes in environmental conditions. Plant functional traits can be used to guide the restoration of degraded habitats...... generally from the treatments. Carbon addition led to large intraspecific trait shifts, with individuals in C addition plots having smaller, denser leaves and shorter stature. Species' trait plasticity, however, was not related to the community composition response to C addition.   Our study indicates...

  8. Drying/rewetting cycles mobilize old C from deep soils from a California annual grassland

    OpenAIRE

    Schimel, JP; Wetterstedt, JAM; Holden, PA; Trumbore, SE

    2011-01-01

    We measured the 14 C and 13 C signatures of CO 2 respired from surface and deep soils released through multiple dry/rewetting cycles in laboratory incubations. The C respired from surface soils included components fixed before and after the 1960s. However, that respired from deep soils was derived from organic matter with a mean turnover time estimated in the range of 650-850 years. This reinforces previous research suggesting that a substantial amount of deep soil C is chemically labile b...

  9. DYNAMICS OF CARBON SEQUESTRATION IN ABANDONED GRASSLANDS OF NORTHEASTERN MEXICO

    Directory of Open Access Journals (Sweden)

    José Israel Yerena Yamallel

    2014-04-01

    Full Text Available Livestock activities due to the improper handling of the load capacity, suffer from low productivity in their grasslands, which are abandoned giving rise to the appearance of species considered invasive and undesirable for producers, without knowing the qualities of these as mitigating of climate change. The objective of the present study was to estimate the carbon content in tamaulipan thornscrub and three abandoned grasslands with a time of abandonment of 10, 20 and 30 years. For the estimation of the carbon content was used a systematic sampling design, in each area were established four sampling sites of 1,600 m2. The primary scrub is the system that resulted in the largest value of carbon content of 14.25 Mg ha-1, followed by the grasslands of 30, 20 and 10 years with 8.03, 7.33 and 4.13 Mg ha-1 respectively. It was concluded that recovering the initial state of the primary scrub take many years, as can be seen in the grasslands system 30 years reaching only 56% of what it had in reserves of primary scrub.

  10. Quantitative ecological relationships in the alpine grassland of ...

    African Journals Online (AJOL)

    A survey, based on 56 000 points at 102 sampling sites in the Tsehlanyane valley of the Oxbow (Madibamatso) Dam catchment in the alpine grassland of Lesotho, indicates that the area is generally in good condition. Physiographic and floristic criteria were measured and the association between pairs of criteria statistically ...

  11. Crude protein changes on grassland along a degradation gradient ...

    African Journals Online (AJOL)

    Evapotranspiration was determined by quantifying the soil-water balance equation with the aid of runoff plots and soil-water content measurements. Crude protein ... The study shows that it is important to keep grassland in optimal condition to utilize limited soil water for sustainable plant and therefore animal production.

  12. Intensification of grassland and forage use: driving forces and constraints

    NARCIS (Netherlands)

    Oenema, O.; Klein, de C.; Alfaro, M.

    2014-01-01

    The increasing demand for safe and nutritional dairy and beef products in a globalising world, together with the needs to increase resource use efficiency and to protect biodiversity, provide strong incentives for intensification of grassland and forage use. This paper addresses the question: 'Does

  13. Achieving grassland production and quality that matches animal needs

    NARCIS (Netherlands)

    Pol, van den A.; Busqué, Juan; Golinski, P.; Noorkõiv, Katrin; O'Donovan, Michael; Peratoner, Giovanni; Reheul, D.

    2016-01-01

    Permanent grasslands are exploited by grazing animals or as meadows depending on different
    constraints. Grazing is the most common use in large parts of Europe, especially in the northwest of
    Europe. However, certain areas are less suitable for grazing. In the Alps e.g. meadows are the

  14. Achieving grassland production and quality that matching animal needs

    NARCIS (Netherlands)

    Pol, van den A.; Busqué, Juan; Golinski, P.; Noorkõiv, Katrin; O'Donovan, Michael; Peratoner, Giovanni; Reheul, D.

    2016-01-01

    Permanent grasslands are exploited by grazing animals or as meadows depending on different constraints. Grazing is the most common use in large parts of Europe, especially in the northwest of Europe. However, certain areas are less suitable for grazing. In the Alps e.g. meadows are the most relevant

  15. Avian diversity in the Naliya Grassland, Abdasa Taluka, Kachchh, India

    Directory of Open Access Journals (Sweden)

    Sandeep B Munjpara

    2012-03-01

    Full Text Available Naliya Grassland is one of the significant grasslands of Gujarat. In this study the importance of the Naliya Grassland has been explored with special reference to avian diversity. Field work for the study was carried out throughout the year of 2007 on a monthly basis covering three distinct seasons to explore avian diversity. A total of 177 species belonging to 54 families were recorded wherein most species belonged to the family Accipitridae (20 species followed by Alaudidae (11 species. Of the total families, five were represented by more than seven species, 18 families by 3-7 species and 31 families by one or two species respectively. Among the species observed, 16 species ware globally threatened (three Critically Endangered, four Endangered and nine Near Threatened. Most of the species were chiefly terrestrial (68.2%, about 23.9% species were freshwater dependant and 7.9% utilized mixed habitats. Maximum species richness was recorded in the monsoons and minimum in summer. Constant turnover and fluctuation in species richness occurred because of seasonal immigration and emigration. Maximum emigration took place during February and March and maximum immigration occurred during June and July. Many water dependant birds attracted to the flooded grassland during the monsoons explained the high species richness during this season. In winter, the area was inhabited by resident species as well as many migratory species.

  16. Evaluation of SPOT imagery for the estimation of grassland biomass

    Science.gov (United States)

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

    2015-06-01

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

  17. Homogenization of the soil surface following fire in semiarid grasslands

    Science.gov (United States)

    Carleton S. White

    2011-01-01

    Semiarid grasslands accumulate soil beneath plant "islands" that are raised above bare interspaces. This fine-scale variation in microtopographic relief is plant-induced and is increased with shrub establishment. Research found that fire-induced water repellency enhanced local-scale soil erosion that reduced variation in microtopographic relief, suggesting...

  18. Relationship between soil chemical factors and grassland diversity

    NARCIS (Netherlands)

    Janssens, F; Peeters, A; Tallowin, JRB; Bakker, JP; Bekker, RM; Fillat, F; Oomes, MJM

    Many studies carried out during these last few years have focused on the factors influencing plant diversity in species-rich grasslands. This is due to the fact that these ecosystems, among the most diversified in temperate climates, are extremely threatened; in some areas, they have almost

  19. Transformation of a savanna grassland by drought and grazing | O ...

    African Journals Online (AJOL)

    The relative effects of drought and heavy grazing on the floristic composition, population size and and structure, and basal cover of an African savanna grassland were differentiated by comparing changes over eight years over eight years, which included a severe drought year, across a gradient of grazing history. Drought ...

  20. Controlling nitrous oxide emissions from grassland livestock production systems

    NARCIS (Netherlands)

    Oenema, O.; Gebauer, G.; Rodriguez, M.; Sapek, A.; Jarvis, S.C.; Corré, W.J.; Yamulki, S.

    1998-01-01

    There is growing awareness that grassland livestock production systems are major sources of nitrous oxide (N2O). Controlling these emissions requires a thorough understanding of all sources and controlling factors at the farm level. This paper examines the various controlling factors and proposes

  1. Effects of large herbivores on grassland arthropod diversity

    NARCIS (Netherlands)

    van Klink, R.; van der Plas, F.; van Noordwijk, C. G. E. (Toos); WallisDeVries, M. F.; Olff, H.

    Both arthropods and large grazing herbivores are important components and drivers of biodiversity in grassland ecosystems, but a synthesis of how arthropod diversity is affected by large herbivores has been largely missing. To fill this gap, we conducted a literature search, which yielded 141

  2. Potassium cycling and losses in grassland systems : a review

    NARCIS (Netherlands)

    Kayser, M; Isselstein, J

    Cycling of potassium in grassland systems has received relatively little attention in research and practice in recent years. Balanced nutrient systems require consideration of nutrients other than nitrogen (N). Potassium (K) is needed in large amounts and is closely related to N nutrition. In

  3. The effect of grassland management on enchytraeids (Oligochaeta) communities

    DEFF Research Database (Denmark)

    Maraldo, Kristine; Schmelz, Rüdiger; Christensen, Bent Tolstrup

    2012-01-01

    Enchytraeids (small white earthworms between 3 to 35 mm) are important regulators of nitrogen turnover in grasslands, as their activities accelerate the decomposition and nutrient recycling processes. In this study, the effect of management on species composition, abundance and biomass of the enc...... biomass and density of the grazed plots are due to compaction by grazing animals....

  4. Effect of burn area on invertebrate recolonization in grasslands in ...

    African Journals Online (AJOL)

    Our study examined the short-term response of grassland invertebrate communities to fire in the South African Drakensberg, in relation to distance from the edge of a burn. We aimed to establish which species survive fire and the dynamics of the post-fire recolonization process, and thereby contribute to establishing the ...

  5. Organic matter dynamics and N mineralization in grassland soils

    NARCIS (Netherlands)

    Hassink, J.

    1995-01-01


    The aims of this study are i) to improve our understanding of the interactions between soil texturelsoil structure, soil organic matter, soil biota and mineralization in grassland soils, ii) to develop a procedure that yields soil organic matter fractions that can be determined directly

  6. Vegetation diversity of salt-rich grasslands in Southeast Europe

    Czech Academy of Sciences Publication Activity Database

    Eliáš, P. Jr.; Sopotlieva, D.; Dítě, D.; Hájková, Petra; Apostolova, I.; Senko, D.; Melečková, Z.; Hájek, Michal

    2013-01-01

    Roč. 16, č. 3 (2013), s. 521-537 ISSN 1402-2001 R&D Projects: GA ČR GA206/09/0329 Institutional research plan: CEZ:AV0Z60050516 Institutional support: RVO:67985939 Keywords : salt marshes * vegetation survey * grasslands Subject RIV: EF - Botanics Impact factor: 2.416, year: 2013

  7. Long-term nutrient fertilization and the carbon balance of permanent grassland: any evidence for sustainable intensification?

    Science.gov (United States)

    Fornara, Dario A.; Wasson, Elizabeth-Anne; Christie, Peter; Watson, Catherine J.

    2016-09-01

    Sustainable grassland intensification aims to increase plant yields while maintaining the ability of soil to act as a sink rather than sources of atmospheric CO2. High biomass yields from managed grasslands, however, can be only maintained through long-term nutrient fertilization, which can significantly affect soil carbon (C) storage and cycling. Key questions remain about (1) how long-term inorganic vs. organic fertilization influences soil C stocks, and (2) how soil C gains (or losses) contribute to the long-term C balance of managed grasslands. Using 43 years of data from a permanent grassland experiment, we show that soils not only act as significant C sinks but have not yet reached C saturation. Even unfertilized control soils showed C sequestration rates of 0.35 Mg C ha-1 yr-1 (i.e. 35 g C m-2 yr-1; 0-15 cm depth) between 1970 and 2013. High application rates of liquid manure (i.e. cattle slurry) further increased soil C sequestration to 0.86 Mg C ha-1 yr-1 (i.e. 86 g C m-2 yr-1) and a key cause of this C accrual was greater C inputs from cattle slurry. However, average coefficients of slurry-C retention in soils suggest that 85 % of C added yearly through liquid manure is lost possibly via CO2 fluxes and organic C leaching. Inorganically fertilized soils (i.e. NPK) had the lowest C-gain efficiency (i.e. unit of C gained per unit of N added) and lowest C sequestration (similar to control soils). Soils receiving cattle slurry showed higher C-gain and N-retention efficiencies compared to soils receiving NPK or pig slurry. We estimate that net rates of CO2-sequestration in the top 15 cm of the soil can offset 9-25 % of GHG (greenhouse gas) emissions from intensive management. However, because of multiple GHG sources associated with livestock farming, the net C balance of these grasslands remains positive (9-12 Mg CO2-equivalent ha-1 yr-1), thus contributing to climate change. Further C-gain efficiencies (e.g. reduced enteric fermentation and use of feed

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

    Science.gov (United States)

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

    2018-02-06

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

  9. Families in the making: gestational surrogate mothers in California

    OpenAIRE

    Bjørn, Henriette Hårseide

    2014-01-01

    This thesis is based on a field work I conducted in California from January to June 2012, where I explore how gestational surrogate mothers experience the process of surrogacy and how California law has dealt with ART-cases. Through exploring surrogacy from different view point, and in particular from the view of surrogate mothers, this has given an insightful view into surrogacy in California. I have identified two court cases which are important for the establishment of parental rights in s...

  10. FIFE data analysis: Testing BIOME-BGC predictions for grasslands

    Science.gov (United States)

    Hunt, E. Raymond, Jr.

    1994-01-01

    The First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE) was conducted in a 15 km by 15 km research area located 8 km south of Manhattan, Kansas. The site consists primarily of native tallgrass prairie mixed with gallery oak forests and croplands. The objectives of FIFE are to better understand the role of biology in controlling the interactions between the land and the atmosphere, and to determine the value of remotely sensed data for estimating climatological parameters. The goals of FIFE are twofold: the upscale integration of models, and algorithm development for satellite remote sensing. The specific objectives of the field campaigns carried out in 1987 and 1989 were the simultaneous acquisition of satellite, atmospheric, and surface data; and the understanding of the processes controlling surface energy and mass exchange. Collected data were used to study the dynamics of various ecosystem processes (photosynthesis, evaporation and transpiration, autotrophic and heterotrophic respiration, etc.). Modelling terrestrial ecosystems at scales larger than that of a homogeneous plot led to the development of simple, generalized models of biogeochemical cycles that can be accurately applied to different biomes through the use of remotely sensed data. A model was developed called BIOME-BGC (for BioGeochemical Cycles) from a coniferous forest ecosystem model, FOREST-BGC, where a biome is considered a combination of a life forms in a specified climate. A predominately C4-photosynthetic grassland is probably the most different from a coniferous forest possible, hence the FIFE site was an excellent study area for testing BIOME-BGC. The transition from an essentially one-dimensional calculation to three-dimensional, landscape scale simulations requires the introduction of such factors as meteorology, climatology, and geomorphology. By using remotely sensed geographic information data for important model inputs, process

  11. The roles of precipitation regimes on juniper forest encroachment on grasslands in Oklahoma

    Science.gov (United States)

    Wang, J.; Xiao, X.; Qin, Y.

    2017-12-01

    Woody plant encroachment into grasslands has been dominantly explained by fire suppression, grazing and CO2 concentrations in the atmosphere. As different root depths of grasses and trees in soils, increased precipitation intensity was expected to facilitate the woody plant abundance, which was demonstrated by the field precipitation test in a sub-tropical savanna ecosystem. However, it is lacking to compressively examine the roles of precipitation regimes on woody plant encroachment at regional scales based on long-term observation data. This study examined the relationships between changes of precipitation regimes (amounts, frequency and intensity) and dynamics of juniper forest coverage using site-based rainfall data and remote sensing-based juniper forest maps in 1994-2010 over Oklahoma State. Our results showed that precipitation amount and intensity played larger roles than frequency on the juniper forest encroachment into the grassland in Oklahoma, and increased precipitation amount and intensity could facilitate the juniper woody encroachment. This practice based on observation data at the regional scale could be used to support precipitation experiments and model simulations and predicting the juniper forest encroachment.

  12. Shifts of growing-season precipitation peaks decrease soil respiration in a semiarid grassland.

    Science.gov (United States)

    Ru, Jingyi; Zhou, Yaqiong; Hui, Dafeng; Zheng, Mengmei; Wan, Shiqiang

    2018-03-01

    Changing precipitation regimes could have profound influences on carbon (C) cycle in the biosphere. However, how soil C release from terrestrial ecosystems responds to changing seasonal distribution of precipitation remains unclear. A field experiment was conducted for 4 years (2013-2016) to examine the effects of altered precipitation distributions in the growing season on soil respiration in a temperate steppe in the Mongolian Plateau. Over the 4 years, both advanced and delayed precipitation peaks suppressed soil respiration, and the reductions mainly occurred in August. The decreased soil respiration could be primarily attributable to water stress and subsequently limited plant growth (community cover and belowground net primary productivity) and soil microbial activities in the middle growing season, suggesting that precipitation amount in the middle growing season is more important than that in the early, late, or whole growing seasons in regulating soil C release in grasslands. The observations of the additive effects of advanced and delayed precipitation peaks indicate semiarid grasslands will release less C through soil respiratory processes under the projected seasonal redistribution of precipitation in the future. Our findings highlight the potential role of intra-annual redistribution of precipitation in regulating ecosystem C cycling in arid and semiarid regions. © 2017 John Wiley & Sons Ltd.

  13. Cellulolytic potential under environmental changes in microbial communities from grassland litter

    Directory of Open Access Journals (Sweden)

    Renaud eBerlemont

    2014-11-01

    Full Text Available In many ecosystems, global changes are likely to profoundly affect microorganisms. In Southern California, changes in precipitation and nitrogen deposition may influence the composition and functional potential of microbial communities and their resulting ability to degrade plant material. To test whether environmental changes impact the distribution of functional groups involved in leaf litter degradation, we determined how the genomic diversity of microbial communities in a semi-arid grassland ecosystem changed under reduced precipitation or increased N deposition. We monitored communities seasonally over a period of two years to place environmental change responses into the context of natural variation. Fungal and bacterial communities displayed strong seasonal patterns, Fungi being mostly detected during the dry season whereas Bacteria were common during wet periods. Most putative cellulose degraders were associated with 33 bacterial genera and constituted ~18.2% of the microbial community. Precipitation reduction reduced bacterial abundance and cellulolytic potential whereas nitrogen addition did not affect the cellulolytic potential of the microbial community. Finally, we detected a strong correlation between the frequencies of genera putative cellulose degraders and cellulase genes. Thus, microbial taxonomic composition was predictive of cellulolytic potential. This work provides a framework for how environmental changes affect microorganisms responsible for plant litter deconstruction.

  14. Differential Responses of Soil Microbial Community to Four-Decade Long Grazing and Cultivation in a Semi-Arid Grassland

    Directory of Open Access Journals (Sweden)

    Yating He

    2017-01-01

    Full Text Available Grazing and cultivation are two important management practices worldwide that can cause significant soil organic carbon (SOC losses. However, it remains elusive how soil microbes have responded to soil carbon changes under these two practices. Based on a four-decade long field experiment, this study investigated the effects of grazing and cultivation on SOC stocks and microbial properties in the semi-arid grasslands of China. We hypothesize that grazing and cultivation would deplete SOC and depress microbial activities under both practices. However, our hypotheses were only partially supported. As compared with the adjacent indigenous grasslands, SOC and microbial biomass carbon (MBC were decreased by 20% or more under grazing and cultivation, which is consistent with the reduction of fungi abundance by 40% and 71%, respectively. The abundance of bacteria and actinomycetes was decreased under grazing but increased under cultivation, which likely enhanced microbial diversity in cultivation. Invertase activity decreased under the two treatments, while urease activity increased under grazing. These results suggest that nitrogen fertilizer input during cultivation may preferentially favor bacterial growth, in spite of SOC loss, due to rapid decomposition, while overgrazing may deteriorate the nitrogen supply to belowground microbes, thus stimulating the microbial production of nitrogen acquisition enzymes. This decade-long study demonstrated differential soil microbial responses under grazing and cultivation and has important applications for better management practices in the grassland ecosystem.

  15. Comparative seed germination traits in alpine and subalpine grasslands: higher elevations are associated with warmer germination temperatures.

    Science.gov (United States)

    Fernández-Pascual, E; Jiménez-Alfaro, B; Bueno, Á

    2017-01-01

    Seed germination traits in alpine grasslands are poorly understood, despite the sensitivity of these communities to climate change. We hypothesise that germination traits predict species occurrence along the alpine-subalpine elevation gradient. Phylogenetic comparative analyses were performed using fresh seeds of 22 species from alpine and subalpine grasslands (1600-2400 m) of the Cantabrian Mountains, Spain (43° N, 5° W). Laboratory experiments were conducted to characterise germinability, optimum germination temperature and effect of cold and warm stratification on dormancy breaking. Variability in these traits was reduced by phylogenetic principal component analysis (phyl.PCA). Phylogenetic generalised least squares regression (PGLS) was used to fit a model in which species average elevation was predicted from their position on the PCA axes. Most subalpine species germinated in snow-like conditions, whereas most alpine species needed accumulation of warm temperatures. Phylogenetic signal was low. PCA1 ordered species according to overall germinability, whilst PCA2 ordered them according to preference for warm or cold germination. PCA2 significantly predicted species occurrence in the alpine-subalpine gradient, as higher elevation species tended to have warmer germination preferences. Our results show that germination traits in high-mountain grasslands are closely linked to the alpine-subalpine gradient. Alpine species, especially those from stripped and wind-edge communities, prefer warmer germination niches, suggesting that summer emergence prevents frost damage during seedling establishment. In contrast, alpine snowfield and subalpine grassland plants have cold germination niches, indicating that winter emergence may occur under snow to avoid drought stress. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

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

    Science.gov (United States)

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

    2018-02-01

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

  17. The Evaluation of Disturbed Grassland After the Ecological Restoration and Phytoremediation in the Low Tatras National Park

    Directory of Open Access Journals (Sweden)

    Ján Novák

    2016-01-01

    Full Text Available At present the grasslands in the conservation areas are often degraded folowing the abandonment of the pasture and it is necessary to restore them. The aim of this paper was to evaluate the grasslands after the ecological restoration and phytoremediation by different methods. In 2004 the experiment was established on degraded sites at locality Low Tatras National Park (1 126 m a.s.l. with three treatments (U – unmanaged control, C – managed by cutting, CS – managed by seeding and cutting. In 2013 on C treatment we noticed the increase of the number of species (threefold, the increase of the coverage of plants (twofold and also the significant increase of the species diversity in comparison with the year 2004. On CS treatment the species diversity has decreased slightly but the forage value has increased more than twofold since 2004. U treatment has remained without changes. The results show the method of seeding the autochthonous species is highly appropriate to increase the forage value of grassland. Spearman correlations between environmental factors (p ≤ 0.05 prove the effect of treatment on the amount of P-soil, P-fyt, K-soil and K-fyt, which show strong negative correlation with the time. On the other hand number of species and EGQ (The evaluation of the grassland qualitycorrelate with time positively (p ≤ 0.05. The restoration by the mowing is recommended on sites, where the increase of diversity is important. Legumes, C, grasses, K-soil, EGQ, number of species, P-soil, time, dry matter hit the variability of the species significantly (to 96.80% of the total variability. The strongest effect on the overall variability of species had legumes, which is 61% of the total variability. Cutting explain 26% of the variability. The soil in the Low Tatras National Park was recovered to the original state through the reduction of soil nutrient – phytoremediation.

  18. Potential nitrogen critical loads for northern Great Plains grassland vegetation

    Science.gov (United States)

    Symstad, Amy J.; Smith, Anine T.; Newton, Wesley E.; Knapp, Alan K.

    2015-01-01

    nitrogen concentration. To determine critical loads for the NGP plant communities in our experiment, we followed the NPS’s precautionary principle in assuming that it is better to be cautious than to let harm occur to the environment. Thus, the critical loads we derived are the lowest nitrogen level that any of our data suggest has a measureable effect on any of the response variables measured.Badlands sparse vegetation, a low-productivity plant community that is an important part of the scenery at Badlands National Park and provides habitat for rare plant species, was the most sensitive of the three vegetation types. More aspects of this vegetation type responded to nitrogen addition, and at lower levels, than at the other two sites. Our data suggest that nitrogen deposition levels of 4- 6 kg N/ha/yr may increase biomass production, and consequently the amount of dead plant material on the ground in this plant community. Slightly higher critical loads are suggested for the two more productive vegetation types more characteristic of most NGP grasslands: 6-10 kg N/ha/yr for biomass production, grass tissue nitrogen concentration, or non-native species (especially annual brome grasses) cover. Highly variable results among years, as well as inconsistent responses to an increasing dose of nitrogen within sites, complicated the derivation of critical loads in this experiment, however. A less precautionary approach to deriving critical loads yielded higher values of 10-38 kg N/ha/yr.

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

    Science.gov (United States)

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

    2011-01-01

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

  20. Grassland futures in Great Britain - Productivity assessment and scenarios for land use change opportunities.

    Science.gov (United States)

    Qi, Aiming; Holland, Robert A; Taylor, Gail; Richter, Goetz M

    2018-09-01

    To optimise trade-offs provided by future changes in grassland use intensity, spatially and temporally explicit estimates of respective grassland productivities are required at the systems level. Here, we benchmark the potential national availability of grassland biomass, identify optimal strategies for its management, and investigate the relative importance of intensification over reversion (prioritising productivity versus environmental ecosystem services). Process-conservative meta-models for different grasslands were used to calculate the baseline dry matter yields (DMY; 1961-1990) at 1km 2 resolution for the whole UK. The effects of climate change, rising atmospheric [CO 2 ] and technological progress on baseline DMYs were used to estimate future grassland productivities (up to 2050) for low and medium CO 2 emission scenarios of UKCP09. UK benchmark productivities of 12.5, 8.7 and 2.8t/ha on temporary, permanent and rough-grazing grassland, respectively, accounted for productivity gains by 2010. By 2050, productivities under medium emission scenario are predicted to increase to 15.5 and 9.8t/ha on temporary and permanent grassland, respectively, but not on rough grassland. Based on surveyed grassland distributions for Great Britain in 2010 the annual availability of grassland biomass is likely to rise from 64 to 72milliontonnes by 2050. Assuming optimal N application could close existing productivity gaps of ca. 40% a range of management options could deliver additional 21∗10 6 tonnes of biomass available for bioenergy. Scenarios of changes in grassland use intensity demonstrated considerable scope for maintaining or further increasing grassland production and sparing some grassland for the provision of environmental ecosystem services. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  1. Species-rich semi-natural grasslands have a higher resistance but a lower resilience than intensively managed agricultural grasslands in response to climate anomalies

    NARCIS (Netherlands)

    Keersmaecker, De Wanda; Rooijen, van Nils; Lhermitte, Stef; Tits, Laurent; Schaminée, Joop; Coppin, Pol; Honnay, Olivier; Somers, Ben

    2016-01-01

    The stable delivery of ecosystem services provided by grasslands is strongly dependent on the stability of grassland ecosystem functions such as biomass production. Biomass production is in turn strongly affected by the frequency and intensity of climate extremes. The aim of this study is to

  2. Migratory monarchs wintering in California experience low infection risk compared to monarchs breeding year-round on non-native milkweed.

    Science.gov (United States)

    Satterfield, Dara A; Villablanca, Francis X; Maerz, John C; Altizer, Sonia

    2016-08-01

    Long-distance migration can lower infection risk for animal populations by removing infected individuals during strenuous journeys, spatially separating susceptible age classes, or allowing migrants to periodically escape from contaminated habitats. Many seasonal migrations are changing due to human activities including climate change and habitat alteration. Moreover, for some migratory populations, sedentary behaviors are becoming more common as migrants abandon or shorten their journeys in response to supplemental feeding or warming temperatures. Exploring the consequences of reduced movement for host-parasite interactions is needed to predict future responses of animal pathogens to anthropogenic change. Monarch butterflies (Danaus plexippus) and their specialist protozoan parasite Ophryocystis elektroscirrha (OE) provide a model system for examining how long-distance migration affects infectious disease processes in a rapidly changing world. Annual monarch migration from eastern North America to Mexico is known to reduce protozoan infection prevalence, and more recent work suggests that monarchs that forego migration to breed year-round on non-native milkweeds in the southeastern and south central Unites States face extremely high risk of infection. Here, we examined the prevalence of OE infection from 2013 to 2016 in western North America, and compared monarchs exhibiting migratory behavior (overwintering annually along the California coast) with those that exhibit year-round breeding. Data from field collections and a joint citizen science program of Monarch Health and Monarch Alert showed that infection frequency was over nine times higher for monarchs sampled in gardens with year-round milkweed as compared to migratory monarchs sampled at overwintering sites. Results here underscore the importance of animal migrations for lowering infection risk and motivate future studies of pathogen transmission in migratory species affected by environmental change. © The

  3. Spain: Europe's California.

    Science.gov (United States)

    Wilvert, Calvin

    1994-01-01

    Contends that, as Spain integrates into the European Economic Community, it is considered to be Europe's California. Asserts that making regional comparisons between California and Spain can be an effective teaching method. Provides comparisons in such areas as agriculture and tourism. (CFR)

  4. Terrestrial ecology. Comprehensive study of the grassland biome

    International Nuclear Information System (INIS)

    Anon.

    1976-01-01

    Terrestrial ecology and grassland biome studies are designed to characterize the biota of the Hanford Reservation, elucidate seasonal dynamics of plant productivity, decomposition and mineral behavior patterns of important plant communities, and, to study the response of these communities to important natural environmental stresses, such as weather, wildfire and man-induced alterations of communities (influenced by grazing cattle and severe mechanical disturbance of the soil, such as affected by plowing or burial of waste materials or construction activities). A detailed account of the important findings of a 5-yr study is currently being prepared by the terrestrial ecology section staff for publication as a contribution to the International Biological Program Grassland Biome project

  5. Direct effects of cattle on grassland birds in Canada.

    Science.gov (United States)

    Bleho, Barbara I; Koper, Nicola; Machtans, Craig S

    2014-06-01

    Effects of grazing on grassland birds are generally thought to be indirect, through alteration of vegetation structure; however, livestock can also affect nest survival directly through trampling and other disturbances (e.g., livestock-induced abandonment). We extracted data on nest fates from 18 grazing studies conducted in Canada. We used these data to assess rates of nest destruction by cattle among 9 ecoregions and between seasonal and rotational grazing systems. Overall, few nests were destroyed by cattle (average 1.5% of 9132 nests). Nest destruction was positively correlated with grazing pressure (i.e., stocking rate or grazing intensity), but nest survival was higher in more heavily grazed areas for some species. Because rates of destruction of grassland bird nests by cattle are low in Canada, management efforts to reduce such destruction may not be of ecological or economic value in Canada. © 2014 Society for Conservation Biology.

  6. The biological transport of radionuclides in grassland and freshwater ecosystems

    International Nuclear Information System (INIS)

    Rudge, S.A.

    1989-12-01

    This thesis examines the biological transport of radionuclides through terrestrial and aquatic ecosystems, with particular reference to radiocaesium. The semi-natural grassland habitat was located at Drigg, W. Cumbria, contaminated primarily by radioactive fallout, from several sources over the past decade. Advantage was made of the deposition of radionuclides from the Chernobyl reactor incident, which occurred during the early stages of the investigation. The study examined the distribution of radiocaesium for the major components of the grassland ecosystem, within the soil-plant-invertebrate-small mammal food chain. Data concerning temporal fluctuation of radionuclide transfer factors between food chain components are presented. The final section examines the spatial distribution of radiocaesium in sediment and the freshwater eel (Anguilla anguilla) in a small stream contaminated by radioactive effluent. The relationship between activity levels in eels and the sediments in which they rest and forage was investigated. Factors influencing uptake of radiocaesium in freshwater fish were also examined. (author)

  7. Acidification of sandy grasslands - consequences for plant diversity

    DEFF Research Database (Denmark)

    Olsson, Pål Axel; Mårtensson, Linda-Maria; Bruun, Hans Henrik

    2009-01-01

    soil; a number of nationally red-listed species showed a similar pattern. Plant species diversity and number of red-listed species increased with slope. Where the topsoil had been acidified, limestone was rarely present above a depth of 30 cm. The presence of limestone restricts the availability......Questions: (1) Does soil acidification in calcareous sandy grasslands lead to loss of plant diversity? (2) What is the relationship between the soil content of lime and the plant availability of mineral nitrogen (N) and phosphorus (P) in sandy grasslands? Location: Sandy glaciofluvial deposits......). Environmental variables were recorded at each plot, and soil samples were analysed for exchangeable P and N, as well as limestone content and pH. Data were analysed with regression analysis and canonical correspondence analysis. Results: Plant species richness was highest on weakly acid to slightly alkaline...

  8. Anaerobic oxidation of methane in grassland soils used for cattle husbandry

    Directory of Open Access Journals (Sweden)

    A. Bannert

    2012-10-01

    Full Text Available While the importance of anaerobic methane oxidation has been reported for marine ecosystems, the role of this process in soils is still questionable. Grasslands used as pastures for cattle overwintering show an increase in anaerobic soil micro-sites caused by animal treading and excrement deposition. Therefore, anaerobic potential methane oxidation activity of severely impacted soil from a cattle winter pasture was investigated in an incubation experiment under anaerobic conditions using 13C-labelled methane. We were able to detect a high microbial activity utilizing CH4 as nutrient source shown by the respiration of 13CO2. Measurements of possible terminal electron acceptors for anaerobic oxidation of methane were carried out. Soil sulfate concentrations were too low to explain the oxidation of the amount of methane added, but enough nitrate and iron(III were detected. However, only nitrate was consumed during the experiment. 13C-PLFA analyses clearly showed the utilization of CH4 as nutrient source mainly by organisms harbouring 16:1ω7 PLFAs. These lipids were also found as most 13C-enriched fatty acids by Raghoebarsing et al. (2006 after addition of 13CH4 to an enrichment culture coupling denitrification of nitrate to anaerobic oxidation of methane. This might be an indication for anaerobic oxidation of methane by relatives of "Candidatus Methylomirabilis oxyfera" in the investigated grassland soil under the conditions of the incubation experiment.

  9. Composition, phenology and restoration of campo rupestre mountain grasslands - Brazil

    OpenAIRE

    Le Stradic, Soizig

    2012-01-01

    Global environmental changes, especially land-use changes, have profound effects on both ecosystem functioning and biodiversity, having already altered many ecosystem services. These losses emphasize the need to preserve what remains; however when conservation programs are not sufficient, restoring areas that have been destroyed or disturbed can improve conservation efforts and mitigate damages. This work focuses on campos rupestres, Neotropical grasslands found at altitudes, which are part o...

  10. Carbon dynamics in an Imperata grassland in Northeast India

    Directory of Open Access Journals (Sweden)

    Amrabati Thokchom

    2016-01-01

    Full Text Available Carbon stocks and soil CO2 flux were assessed in an Imperata cylindrica grassland of Manipur, Northeast India. Carbon stocks in the vegetative components were estimated to be 11.17 t C/ha and soil organic carbon stocks were 55.94 t C/ha to a depth of 30 cm. The rates of carbon accumulation in above-ground and below-ground biomass were estimated to be 11.85 t C/ha/yr and 11.71 t C/ha/yr, respectively. Annual soil CO2 flux was evaluated as 6.95 t C/ha and was highly influenced by soil moisture, soil temperature and soil organic carbon as well as by C stocks in above-ground biomass. Our study on the carbon budget of the grassland ecosystem revealed that annually 23.56 t C/ha was captured by the vegetation through photosynthesis, and 6.95 t C/ha was returned to the atmosphere through roots and microbial respiration, with a net balance of 16.61 t C/ha/yr being retained in the grassland ecosystem. Thus the present Imperata grassland exhibited a high capacity to remove atmospheric CO2 and to induce high C stocks in the soil provided it is protected from burning and overgrazing.Keywords: Above-ground biomass, below-ground biomass, carbon stocks, carbon storage, net primary productivity, soil CO2 flux.DOI: 10.17138/TGFT(419-28  

  11. Carbon balance of renovated grasslands: input- or output-driven?

    Science.gov (United States)

    Choncubhair, Órlaith Ní; Osborne, Bruce; Lanigan, Gary

    2015-04-01

    Temperate grasslands constitute over 30% of the Earth's naturally-occurring biomes and make an important contribution towards the partial mitigation of anthropogenic greenhouse gas emissions by terrestrial ecosystems. In permanent temperate grasslands, biomass production and sward quality can deteriorate over time and periodic renovation activities, involving soil tillage and reseeding, are commonly carried out to halt this decline. Long-term cultivation of agricultural land has been associated with soil aggregate degradation and reduced soil carbon storage. However, the impact of these single tillage disturbances on C cycling in grasslands is less clear. This study evaluated gaseous and dissolved organic carbon (DOC) losses following a single tillage event by subjecting grassland lysimeters with contrasting soil drainage characteristics to simulated conventional inversion or minimum tillage. Field-scale CO2 emissions after conventional tillage were also quantified and empirically modelled over short- and medium-term timeframes to delineate the ecosystem response to environmental variables. Soil moisture was the limiting determinant of ecosystem carbon release following conventional tillage. Freshly-tilled soils were associated with reduced water retention and increased sensitivity to soil moisture, which was particularly pronounced following rewetting events. Significantly elevated but ephemeral CO2 effluxes were detected in the hours following inversion ploughing, however tillage disturbance did not generate significantly enhanced C emission rates in the medium term. Equally, DOC losses were not significantly amplified by conventional tillage compared with conservative minimum tillage and were predominantly controlled by soil drainage across tillage regimes. Our results suggest that a net ecosystem source of 120 to 210 g C m-2 over an approximately two-month period was most likely a consequence of reduced productivity and C input rather than enhanced soil CO2

  12. Making Grasslands Sustainable in Mongolia: Herders' Livelihoods and Climate Change

    OpenAIRE

    Asian Development Bank (ADB)

    2014-01-01

    The threats posed by climate change have significant impacts on Mongolia’s grassland ecosystems and herders’ livelihoods. This publication discusses the auses of climate change and its impacts on livelihoods and ecosystems for herders and the general public. It explains how good pasture management and livestock roductivity are important for increasing incomes and provides information on adaptation practices. It also identifies sustainable management practices that can increase communities’ re...

  13. Resuspension and redistribution of radionuclides during grassland and forest fires in the Chernobyl exclusion zone: part II. Modeling the transport process

    International Nuclear Information System (INIS)

    Yoschenko, V.I.; Kashparov, V.A.; Levchuk, S.E.; Glukhovskiy, A.S.; Khomutinin, Yu.V.; Protsak, V.P.; Lundin, S.M.; Tschiersch, J.

    2006-01-01

    To predict parameters of radionuclide resuspension, transport and deposition during forest and grassland fires, several model modules were developed and adapted. Experimental data of controlled burning of prepared experimental plots in the Chernobyl exclusion zone have been used to evaluate the prognostic power of the models. The predicted trajectories and elevations of the plume match with those visually observed during the fire experiments in the grassland and forest sites. Experimentally determined parameters could be successfully used for the calculation of the initial plume parameters which provide the tools for the description of various fire scenarios and enable prognostic calculations. In summary, the model predicts a release of some per mille from the radionuclide inventory of the fuel material by the grassland fires. During the forest fire, up to 4% of 137 Cs and 9 Sr and up to 1% of the Pu isotopes can be released from the forest litter according to the model calculations. However, these results depend on the parameters of the fire events. In general, the modeling results are in good accordance with the experimental data. Therefore, the considered models were successfully validated and can be recommended for the assessment of the resuspension and redistribution of radionuclides during grassland and forest fires in contaminated territories

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

    Science.gov (United States)

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

    1999-01-01

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

  15. Hierarchical traits distances explain grassland Fabaceae species' ecological niches distances

    Science.gov (United States)

    Fort, Florian; Jouany, Claire; Cruz, Pablo

    2015-01-01

    Fabaceae species play a key role in ecosystem functioning through their capacity to fix atmospheric nitrogen via their symbiosis with Rhizobium bacteria. To increase benefits of using Fabaceae in agricultural systems, it is necessary to find ways to evaluate species or genotypes having potential adaptations to sub-optimal growth conditions. We evaluated the relevance of phylogenetic distance, absolute trait distance and hierarchical trait distance for comparing the adaptation of 13 grassland Fabaceae species to different habitats, i.e., ecological niches. We measured a wide range of functional traits (root traits, leaf traits, and whole plant traits) in these species. Species phylogenetic and ecological distances were assessed from a species-level phylogenetic tree and species' ecological indicator values, respectively. We demonstrated that differences in ecological niches between grassland Fabaceae species were related more to their hierarchical trait distances than to their phylogenetic distances. We showed that grassland Fabaceae functional traits tend to converge among species with the same ecological requirements. Species with acquisitive root strategies (thin roots, shallow root systems) are competitive species adapted to non-stressful meadows, while conservative ones (coarse roots, deep root systems) are able to tolerate stressful continental climates. In contrast, acquisitive species appeared to be able to tolerate low soil-P availability, while conservative ones need high P availability. Finally we highlight that traits converge along the ecological gradient, providing the assumption that species with similar root-trait values are better able to coexist, regardless of their phylogenetic distance. PMID:25741353

  16. Soil Respiration in Semiarid Temperate Grasslands under Various Land Management.

    Directory of Open Access Journals (Sweden)

    Zhen Wang

    Full Text Available Soil respiration, a major component of the global carbon cycle, is significantly influenced by land management practices. Grasslands are potentially a major sink for carbon, but can also be a source. Here, we investigated the potential effect of land management (grazing, clipping, and ungrazed enclosures on soil respiration in the semiarid grassland of northern China. Our results showed the mean soil respiration was significantly higher under enclosures (2.17 μmol.m(-2.s(-1 and clipping (2.06 μmol.m(-2.s(-1 than under grazing (1.65 μmol.m-(2.s(-1 over the three growing seasons. The high rates of soil respiration under enclosure and clipping were associated with the higher belowground net primary productivity (BNPP. Our analyses indicated that soil respiration was primarily related to BNPP under grazing, to soil water content under clipping. Using structural equation models, we found that soil water content, aboveground net primary productivity (ANPP and BNPP regulated soil respiration, with soil water content as the predominant factor. Our findings highlight that management-induced changes in abiotic (soil temperature and soil water content and biotic (ANPP and BNPP factors regulate soil respiration in the semiarid temperate grassland of northern China.

  17. Soil Respiration in Semiarid Temperate Grasslands under Various Land Management.

    Science.gov (United States)

    Wang, Zhen; Ji, Lei; Hou, Xiangyang; Schellenberg, Michael P

    2016-01-01

    Soil respiration, a major component of the global carbon cycle, is significantly influenced by land management practices. Grasslands are potentially a major sink for carbon, but can also be a source. Here, we investigated the potential effect of land management (grazing, clipping, and ungrazed enclosures) on soil respiration in the semiarid grassland of northern China. Our results showed the mean soil respiration was significantly higher under enclosures (2.17 μmol.m(-2).s(-1)) and clipping (2.06 μmol.m(-2).s(-1)) than under grazing (1.65 μmol.m-(2).s(-1)) over the three growing seasons. The high rates of soil respiration under enclosure and clipping were associated with the higher belowground net primary productivity (BNPP). Our analyses indicated that soil respiration was primarily related to BNPP under grazing, to soil water content under clipping. Using structural equation models, we found that soil water content, aboveground net primary productivity (ANPP) and BNPP regulated soil respiration, with soil water content as the predominant factor. Our findings highlight that management-induced changes in abiotic (soil temperature and soil water content) and biotic (ANPP and BNPP) factors regulate soil respiration in the semiarid temperate grassland of northern China.

  18. Hierarchical traits distances explain grassland Fabaceae species’ ecological niches distances

    Directory of Open Access Journals (Sweden)

    Florian eFort

    2015-02-01

    Full Text Available Fabaceae species play a key role in ecosystem functioning through their capacity to fix atmospheric nitrogen via their symbiosis with Rhizobium bacteria. To increase benefits of using Fabaceae in agricultural systems, it is necessary to find ways to evaluate species or genotypes having potential adaptations to sub-optimal growth conditions. We evaluated the relevance of phylogenetic distance, absolute trait distance and hierarchical trait distance for comparing the adaptation of 13 grassland Fabaceae species to different habitats, i.e. ecological niches. We measured a wide range of functional traits (root traits, leaf traits and whole plant traits in these species. Species phylogenetic and ecological distances were assessed from a species-level phylogenetic tree and species’ ecological indicator values, respectively. We demonstrated that differences in ecological niches between grassland Fabaceae species were related more to their hierarchical trait distances than to their phylogenetic distances. We showed that grassland Fabaceae functional traits tend to converge among species with the same ecological requirements. Species with acquisitive root strategies (thin roots, shallow root systems are competitive species adapted to non-stressful meadows, while conservative ones (coarse roots, deep root systems are able to tolerate stressful continental climates. In contrast, acquisitive species appeared to be able to tolerate low soil-P availability, while conservative ones need high P availability. Finally we highlight that traits converge along the ecological gradient, providing the assumption that species with similar root-trait values are better able to coexist, regardless of their phylogenetic distance.

  19. 75 FR 53877 - Proposed Establishment of the Antelope Valley of the California High Desert Viticultural Area

    Science.gov (United States)

    2010-09-02

    ... Viticulture,'' by Albert J. Winkler, University of California Press, 1974, pp. 61-64). As a measurement of..., eighth edition, January 2007, Sunset Publishing Corporation, Menlo Park, California), which is discussed... Service, in cooperation with the University of California Agricultural Experiment Station). Annual...

  20. California Institute for Water Resources - California Institute for Water

    Science.gov (United States)

    Resources Skip to Content Menu California Institute for Water Resources Share Print Site Map Resources Publications Keep in Touch QUICK LINKS Our Blog: The Confluence Drought & Water Information University of California California Institute for Water Resources California Institute for Water Resources

  1. Evaluation of semiarid grassland degradation in North China from multiple perspectives

    Science.gov (United States)

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

    2017-12-01

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

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

    Science.gov (United States)

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

    2018-03-01

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

  3. The influence of boundary features on grassland-edge communities of Alta Murgia

    OpenAIRE

    Cassano, Stefania; Alignier, Audrey; Forte, Luigi; Labadessa, Rocco; Mairota, Paola

    2016-01-01

    Many studies suggest the importance of boundary features on plant community dynamics. Our aim was to investigate the influence of boundary features on edge plant assemblages in semi-natural dry grasslands. For this purpose we selected 16 grassland edges in the central portion of the Natura 2000 site Murgia Alta, in southeastern Italy. These sites were selected according to a combination of boundary features, i.e. the adjoining land use type (road or cereal crop), slope (grassland tilted towar...

  4. Inadequate thermal refuge constrains landscape habitability for a grassland bird species.

    Science.gov (United States)

    Tomecek, John M; Pierce, Brian L; Reyna, Kelly S; Peterson, Markus J

    2017-01-01

    Ecologists have long recognized the influence that environmental conditions have on abundance and range extent of animal species. We used the northern bobwhite ( Colinus virginianus ; hereafter bobwhite) as a model species for studying how microclimates serve as refuge against severe weather conditions. This species serves as an indicator or umbrella species for other sensitive ground-nesting, grassland obligate species. We conducted a mensurative field experiment in the rolling plains of Texas, USA, a semi-arid ecosystem on the southwestern periphery of bobwhite range, to determine whether native bunch grasses, apparently suitable for bobwhite nesting, could reduce ambient temperature below levels harmful for eggs. During the nesting season, we compared temperature and relative humidity readings at daily heat maxima (i.e., the 3 h during each day with highest temperatures) during the nesting season over the course of two years at 63 suitable nest sites paired with 63 random locations ( n = 126) using two sensors at ∼10 and ∼60 cm above ground level. Mean temperature at nest height was 2.3% cooler at nest sites (35.99 °C ± 0.07 SE) compared to random locations (36.81 °C ± 0.07 SE); at ambient height, nest sites were slightly cooler (32.78 °C ± 0.06 SE) than random location (32.99 °C ± 0.06 SE). Mean relative humidity at nest sites was greater at nest height (34.53% ± 0.112 SE) and ambient height (36.22% ± 0.10 SE) compared to random locations at nest (33.35% ± 0.12 SE) and ambient height (35.75% ± 0.10 SE). Based on these results, cover at sites that appear visually suitable for nesting by bobwhites and other ground nesting birds provided adequate thermal refuge in the rolling plains by maintaining cooler, moister microclimates than surrounding non-nesting locations. Post-hoc analyses of data revealed that habitat conditions surrounding suitable nest sites strongly influenced thermal suitability of the substrate. Given that eggs of bobwhites and

  5. Inadequate thermal refuge constrains landscape habitability for a grassland bird species

    Directory of Open Access Journals (Sweden)

    John M. Tomecek

    2017-08-01

    Full Text Available Ecologists have long recognized the influence that environmental conditions have on abundance and range extent of animal species. We used the northern bobwhite (Colinus virginianus; hereafter bobwhite as a model species for studying how microclimates serve as refuge against severe weather conditions. This species serves as an indicator or umbrella species for other sensitive ground-nesting, grassland obligate species. We conducted a mensurative field experiment in the rolling plains of Texas, USA, a semi-arid ecosystem on the southwestern periphery of bobwhite range, to determine whether native bunch grasses, apparently suitable for bobwhite nesting, could reduce ambient temperature below levels harmful for eggs. During the nesting season, we compared temperature and relative humidity readings at daily heat maxima (i.e., the 3 h during each day with highest temperatures during the nesting season over the course of two years at 63 suitable nest sites paired with 63 random locations (n = 126 using two sensors at ∼10 and ∼60 cm above ground level. Mean temperature at nest height was 2.3% cooler at nest sites (35.99 °C ± 0.07 SE compared to random locations (36.81 °C ± 0.07 SE; at ambient height, nest sites were slightly cooler (32.78 °C ± 0.06 SE than random location (32.99 °C ± 0.06 SE. Mean relative humidity at nest sites was greater at nest height (34.53% ± 0.112 SE and ambient height (36.22% ± 0.10 SE compared to random locations at nest (33.35% ± 0.12 SE and ambient height (35.75% ± 0.10 SE. Based on these results, cover at sites that appear visually suitable for nesting by bobwhites and other ground nesting birds provided adequate thermal refuge in the rolling plains by maintaining cooler, moister microclimates than surrounding non-nesting locations. Post-hoc analyses of data revealed that habitat conditions surrounding suitable nest sites strongly influenced thermal suitability of the substrate. Given that eggs of bobwhites

  6. Semi-arid grassland bird responses to patch-burn grazing and drought

    Science.gov (United States)

    Skagen, Susan K.; Augustine, David J.; Derner, Justin D.

    2018-01-01

    As grassland birds of central North America experience steep population declines with changes in land use, management of remaining tracts becomes increasingly important for population viability. The integrated use of fire and grazing may enhance vegetation heterogeneity and diversity in breeding birds, but the subsequent effects on reproduction are unknown. We examined the influence of patch-burn grazing management in shortgrass steppe in eastern Colorado on habitat use and reproductive success of 3 grassland bird species, horned lark (Eremophila alpestris), lark bunting (Calamospiza melanocorys), and McCown’s longspur (Rhynchophanes mccownii), at several spatial scales during 2011 and 2012. Although no simple direct relationship to patch-burn grazing treatment existed, habitat selection depended on precipitation- and management-induced vegetation conditions and spatial scale. All species selected taller-than-expected vegetation at the nest site, whereas at the territory scale, horned larks and McCown’s longspurs selected areas with low vegetation height and sparse cover of tall plants (taller than the dominant shortgrasses). Buntings nested primarily in unburned grassland under average rainfall. Larks and longspurs shifted activity from patch burns during average precipitation (2011) to unburned pastures during drought (2012). Daily survival rate (DSR) of nests varied with time in season, species, weather, and vegetation structure. Daily survival rate of McCown’s longspur nests did not vary with foliar cover of relatively tall vegetation at the nest under average precipitation but declined with increasing cover during drought. At the 200-m scale, increasing cover of shortgrasses, rather than taller plant species, improved DSR of larks and longspurs. These birds experience tradeoffs in the selection of habitat at different spatial scales: tall structure at nests may reduce visual detection by predators and provide protection from sun, wind, and rain, yet

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

    Science.gov (United States)

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

    2010-01-01

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

  8. Grassland Soil Carbon Responses to Nitrogen Additions

    Science.gov (United States)

    Hofmockel, K. S.; Tfailly, M.; Callister, S.; Bramer, L.; Thompson, A.

    2017-12-01

    Using a long-term continental scale experiment, we tested if increases in nitrogen (N) inputs augment the accumulation of plant and microbial residues onto mineral soil surfaces. This research investigates N effects on molecular biogeochemistry across six sites from the Nutrient Network (NutNet) experiment. The coupling between concurrently changing carbon (C) and N cycles remains a key uncertainty in understanding feedbacks between the terrestrial C cycle and climate change. Existing models do not consider the full suite of linked C-N processes, particularly belowground, that could drive future C-climate feedbacks. Soil harbors a wealth of diverse organic molecules, most of which have not been measured in hypothesis driven field research. For the first time we systematically assess the chemical composition of soil organic matter (SOM) and functional characteristics of the soil microbiome, to enhance our understanding of the molecular underpinnings of ecosystem C and N cycling. We have acquired soils from 5 ecosystem experiments across the US that have been subjected to 8 years of N addition treatments. These soils have been analyzed for chemical composition to identify how the soil fertility and stability is altered by N fertilization. We found distinct SOM signatures from our field experiments and shifts in soil chemistry in response to 8 years of N fertilization. Across all sites, we found the molecular composition of SOM varied with clay content, supporting the importance of soil mineralogy in the accumulation of specific chemical classes of SOM. While many molecules were common across sites, we discovered a suite of molecules that were site specific. N fertilization had a significant effect on SOM composition. Differences between control and N amended plots were greater in sites rich in lipids and more complex molecules, compared to sites with SOM rich in amino-sugar and protein like substances. Our results have important implications for how SOM is

  9. Increased competition does not lead to increased phylogenetic overdispersion in a native grassland.

    Science.gov (United States)

    Bennett, Jonathan A; Lamb, Eric G; Hall, Jocelyn C; Cardinal-McTeague, Warren M; Cahill, James F

    2013-09-01

    That competition is stronger among closely related species and leads to phylogenetic overdispersion is a common assumption in community ecology. However, tests of this assumption are rare and field-based experiments lacking. We tested the relationship between competition, the degree of relatedness, and overdispersion among plants experimentally and using a field survey in a native grassland. Relatedness did not affect competition, nor was competition associated with phylogenetic overdispersion. Further, there was only weak evidence for increased overdispersion at spatial scales where plants are likely to compete. These results challenge traditional theory, but are consistent with recent theories regarding the mechanisms of plant competition and its potential effect on phylogenetic structure. We suggest that specific conditions related to the form of competition and trait conservatism must be met for competition to cause phylogenetic overdispersion. Consequently, overdispersion as a result of competition is likely to be rare in natural communities. © 2013 John Wiley & Sons Ltd/CNRS.

  10. Effects of nitrogen and water addition on trace element stoichiometry in five grassland species

    DEFF Research Database (Denmark)

    Cai, Jiangping; Weiner, Jacob; Wang, Ruzhen

    2017-01-01

    A 9-year manipulative experiment with nitrogen (N) and water addition, simulating increasing N deposition and changing precipitation regime, was conducted to investigate the bioavailability of trace elements, iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) in soil, and their uptake by plants...... in the organism and the chemical concentration in the growth substrate) and foliar Fe:Mn ratio in each plant was calculated. Our results showed that soil available Fe, Mn and Cu concentrations increased under N addition and were negatively correlated with both soil pH and cation exchange capacity. Water addition...... under the two environmental change factors in a semi-arid grassland of Inner Mongolia. We measured concentrations of trace elements in soil and in foliage of five common herbaceous species including 3 forbs and 2 grasses. In addition, bioaccumulation factors (BAF, the ratio of the chemical concentration...

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

    Science.gov (United States)

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

    2018-05-09

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

  12. A more holistic understanding of soil organic matter pools of alpine and pre-alpine grassland soils in a changing climate

    Science.gov (United States)

    Garcia Franco, Noelia; Wiesmeier, Martin; Kiese, Ralf; Dannenmann, Michael; Wolf, Benjamin; Brandhuber, Robert; Beck, Robert; Kögel-Knabner, Ingrid

    2016-04-01

    In southern Germany, the alpine and pre-alpine grassland systems (> 1 Mio ha) provide an important economic value via fodder used for milk and meat production and grassland soils support environmental key functions (C and N storage, water retention, erosion control and biodiversity hot spot). In addition, these grassland soils constitute important regions for tourism and recreation. However, the different land use and management practices in this area introduce changes which are likely to accelerate due to climate change. The newly launched SUPSALPS project within the BonaRes Initiative of the German Ministry for Education and Research is focused on the development and evaluation of innovative grassland management strategies under climate change with an emphasis on soil functions, which are on the one hand environmental sustainable and on the other hand economically viable. Several field experiments of the project will be initialized in order to evaluate grassland soil functioning for a range of current and climate adapted management practices. A multi-factorial design combines ongoing and new plant-soil meso-/macrocosm and field studies at a multitude of existing long-term research sites along an elevation gradient in Bavaria. One of the specific objectives of the project is to improve our knowledge on the sensitivity of specific soil organic matter (SOM) fractions to climate change. Moreover, the project aims to determine the processes and mechanisms involved in the build-up and stabilization of C and N pools under different management practices. In order to derive sensitive SOM pools, a promising physical fractionation method was developed that enables the separation of five different SOM fractions by density, ultrasonication and sieving separation: fine particulate organic matter (fPOM), occluded particulate organic matter (oPOM>20μm and oPOM 20 μm; medium + fine silt and clay, management changes.

  13. Ecosystem properties of semi-arid savanna grassland in West Africa and its relationship to environmental variability

    DEFF Research Database (Denmark)

    Tagesson, Torbern; Fensholt, Rasmus; Guiro, Idrissa

    2015-01-01

    he Dahra field site in Senegal, West Africa, was established in 2002 to monitor ecosystem properties of semiarid savanna grassland and their responses to climatic and environmental change. This article describes the environment and the ecosystem properties of the site using a unique set of in situ......), biomass, vegetation water content, and land-atmosphere exchanges of carbon (NEE) and energy. The Dahra field site experiences a typical Sahelian climate and is covered by coexisting trees (~3% canopy cover) and grass species, characterizing large parts of the Sahel. This makes the site suitable...

  14. Native peoples’ relationship to the California chaparral

    Science.gov (United States)

    Anderson, M. Kat; Keeley, Jon E.; Underwood, Emma C.; Safford, Hugh D.; Molinari, Nicole A.; Keeley, Jon E.

    2018-01-01

    Ethnographic interviews and historical literature reviews provide evidence that for many tribes of California, chaparral plant communities were a rich source of food, medicines, and technologies and that they supplemented natural fires with deliberate burning of chaparral to maximize its ability to produce useful products. Many of the most important chaparral plant species used in the food and material culture have strong adaptations to fire. Particularly useful were many annual and perennial herbs, which proliferate after fire from seed and bulb banks, shrub resprouts that made superb cordage and basketry material, as well as animals that were more readily caught in postfire environments. The reasons for burning in chaparral are grouped into seven ecological categories, each relying on a known response to fire of the chaparral community. The authors posit that tribes employed intentional burning to maintain chaparral in different ages and size classes to meet diverse food and material needs, tracking the change in plant and animal abundance and diversity, and shifts in shrub architecture and habitat structure during the recovery of the chaparral community. Areas were burned in ways designed to create a mosaic of open grassland and recently burned, young and mature stands of chaparral with different combinations of species and densities. This management conferred on chaparral plant communities a degree of spatial, structural, successional, and biotic diversity that exceeded what would have been the case in the absence of human intervention. These impacts are still evident on contemporary landscapes.

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

    Science.gov (United States)

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

    2017-04-01

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

  16. Flower resource and land management drives hoverfly communities and bee abundance in seminatural and agricultural grasslands.

    Science.gov (United States)

    Lucas, Andrew; Bull, James C; de Vere, Natasha; Neyland, Penelope J; Forman, Dan W

    2017-10-01

    Pollination is a key ecosystem service, and appropriate management, particularly in agricultural systems, is essential to maintain a diversity of pollinator guilds. However, management recommendations frequently focus on maintaining plant communities, with the assumption that associated invertebrate populations will be sustained. We tested whether plant community, flower resources, and soil moisture would influence hoverfly (Syrphidae) abundance and species richness in floristically-rich seminatural and floristically impoverished agricultural grassland communities in Wales (U.K.) and compared these to two Hymenoptera genera, Bombus, and Lasioglossum . Interactions between environmental variables were tested using generalized linear modeling, and hoverfly community composition examined using canonical correspondence analysis. There was no difference in hoverfly abundance, species richness, or bee abundance, between grassland types. There was a positive association between hoverfly abundance, species richness, and flower abundance in unimproved grasslands. However, this was not evident in agriculturally improved grassland, possibly reflecting intrinsically low flower resource in these habitats, or the presence of plant species with low or relatively inaccessible nectar resources. There was no association between soil moisture content and hoverfly abundance or species richness. Hoverfly community composition was influenced by agricultural improvement and the amount of flower resource. Hoverfly species with semiaquatic larvae were associated with both seminatural and agricultural wet grasslands, possibly because of localized larval habitat. Despite the absence of differences in hoverfly abundance and species richness, distinct hoverfly communities are associated with marshy grasslands, agriculturally improved marshy grasslands, and unimproved dry grasslands, but not with improved dry grasslands. Grassland plant community cannot be used as a proxy for pollinator

  17. University of Southern California

    Data.gov (United States)

    Federal Laboratory Consortium — The focus of the University of Southern California (USC) Children''s Environmental Health Center is to develop a better understanding of how host susceptibility and...

  18. Coastal California Digital Imagery

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital ortho-imagery dataset is a survey of coastal California. The project area consists of approximately 3774 square miles. The project design of the digital...

  19. California Harpoon Fishery

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains vessel logbook and landings data from harpoon vessels that fish within 200 miles of the California coast, from 1974 to present. The harpoon...

  20. Kelp distribution off California

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set delineates kelp beds (Nereocystis leutkeana and Macrocystis spp.) along the Pacific Coast of California. Multiple years of kelp mapping data for the...

  1. California Ocean Uses Atlas

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset is a result of the California Ocean Uses Atlas Project: a collaboration between NOAA's National Marine Protected Areas Center and Marine Conservation...

  2. California Watershed Hydrologic Units

    Data.gov (United States)

    California Natural Resource Agency — This dataset is intended to be used as a tool for water-resource management and planning activities, particularly for site-specific and localized studies requiring a...

  3. California Hydrogen Infrastructure Project

    Energy Technology Data Exchange (ETDEWEB)

    Heydorn, Edward C

    2013-03-12

    Air Products and Chemicals, Inc. has completed a comprehensive, multiyear project to demonstrate a hydrogen infrastructure in California. The specific primary objective of the project was to demonstrate a model of a real-world retail hydrogen infrastructure and acquire sufficient data within the project to assess the feasibility of achieving the nation's hydrogen infrastructure goals. The project helped to advance hydrogen station technology, including the vehicle-to-station fueling interface, through consumer experiences and feedback. By encompassing a variety of fuel cell vehicles, customer profiles and fueling experiences, this project was able to obtain a complete portrait of real market needs. The project also opened its stations to other qualified vehicle providers at the appropriate time to promote widespread use and gain even broader public understanding of a hydrogen infrastructure. The project engaged major energy companies to provide a fueling experience similar to traditional gasoline station sites to foster public acceptance of hydrogen. Work over the course of the project was focused in multiple areas. With respect to the equipment needed, technical design specifications (including both safety and operational considerations) were written, reviewed, and finalized. After finalizing individual equipment designs, complete station designs were started including process flow diagrams and systems safety reviews. Material quotes were obtained, and in some cases, depending on the project status and the lead time, equipment was placed on order and fabrication began. Consideration was given for expected vehicle usage and station capacity, standard features needed, and the ability to upgrade the station at a later date. In parallel with work on the equipment, discussions were started with various vehicle manufacturers to identify vehicle demand (short- and long-term needs). Discussions included identifying potential areas most suited for hydrogen fueling

  4. Effects of nitrogen deposition and cattle grazing on productivity, invasion impact, and soil microbial processes in a serpentine grassland

    Science.gov (United States)

    Pasari, J.; Hernandez, D.; Selmants, P. C.; Keck, D.

    2010-12-01

    In recent decades, human activities have vastly increased the amount of biologically available nitrogen (N) in the biosphere. The resulting increase in N availability has broadly affected ecosystems through increased productivity, changes in species composition, altered nutrient cycles, and increases in invasion by exotic plant species, especially in systems that were historically low in N. California serpentine grasslands are N-limited ecosystems historically dominated by native species including several threatened and endangered plants and animals. Cattle grazing has emerged as the primary tool for controlling the impact of nitrophilic exotic grasses whose increased abundance has paralleled the regional traffic-derived increase in atmospheric N deposition. We examined the interactive effects of cattle grazing and N deposition on plant community composition, productivity, invasion resistance, and microbial processes in the Bay Area's largest serpentine grassland to determine the efficacy of current management strategies as well as the biogeochemical consequences of exotic species invasion. In the first two years of the study, aboveground net primary productivity decreased in response to grazing and increased in response to nitrogen addition. However, contrary to our hypotheses the change in productivity was not due to an increase in exotic species cover as there was little overall effect of grazing or N addition on species composition. Microbial activity was more responsive to grazing and N. Potential net N mineralization rates increased with N addition, but were not affected by grazing. In contrast, soil respiration rates were inhibited by grazing, but were not affected by N addition; suggesting strong carbon-limitation of soil microbial activity, particularly under grazing. Site differences in soil depth and grazing intensity were often more important than treatment effects. We suspect that the unusually dry conditions in the first two growing seasons inhibited

  5. Mutualism and Adaptive Divergence: Co-Invasion of a Heterogeneous Grassland by an Exotic Legume-Rhizobium Symbiosis

    Science.gov (United States)

    Porter, Stephanie S.; Stanton, Maureen L.; Rice, Kevin J.

    2011-01-01

    Species interactions play a critical role in biological invasions. For example, exotic plant and microbe mutualists can facilitate each other's spread as they co-invade novel ranges. Environmental context may influence the effect of mutualisms on invasions in heterogeneous environments, however these effects are poorly understood. We examined the mutualism between the legume, Medicago polymorpha, and the rhizobium, Ensifer medicae, which have both invaded California grasslands. Many of these invaded grasslands are composed of a patchwork of harsh serpentine and relatively benign non-serpentine soils. We grew legume genotypes collected from serpentine or non-serpentine soil in both types of soil in combination with rhizobium genotypes from serpentine or non-serpentine soils and in the absence of rhizobia. Legumes invested more strongly in the mutualism in the home soil type and trends in fitness suggested that this ecotypic divergence was adaptive. Serpentine legumes had greater allocation to symbiotic root nodules in serpentine soil than did non-serpentine legumes and non-serpentine legumes had greater allocation to nodules in non-serpentine soil than did serpentine legumes. Therefore, this invasive legume has undergone the rapid evolution of divergence for soil-specific investment in the mutualism. Contrary to theoretical expectations, the mutualism was less beneficial for legumes grown on the stressful serpentine soil than on the non-serpentine soil, possibly due to the inhibitory effects of serpentine on the benefits derived from the interaction. The soil-specific ability to allocate to a robust microbial mutualism may be a critical, and previously overlooked, adaptation for plants adapting to heterogeneous environments during invasion. PMID:22174755

  6. Mutualism and adaptive divergence: co-invasion of a heterogeneous grassland by an exotic legume-rhizobium symbiosis.

    Directory of Open Access Journals (Sweden)

    Stephanie S Porter

    Full Text Available Species interactions play a critical role in biological invasions. For example, exotic plant and microbe mutualists can facilitate each other's spread as they co-invade novel ranges. Environmental context may influence the effect of mutualisms on invasions in heterogeneous environments, however these effects are poorly understood. We examined the mutualism between the legume, Medicago polymorpha, and the rhizobium, Ensifer medicae, which have both invaded California grasslands. Many of these invaded grasslands are composed of a patchwork of harsh serpentine and relatively benign non-serpentine soils. We grew legume genotypes collected from serpentine or non-serpentine soil in both types of soil in combination with rhizobium genotypes from serpentine or non-serpentine soils and in the absence of rhizobia. Legumes invested more strongly in the mutualism in the home soil type and trends in fitness suggested that this ecotypic divergence was adaptive. Serpentine legumes had greater allocation to symbiotic root nodules in serpentine soil than did non-serpentine legumes and non-serpentine legumes had greater allocation to nodules in non-serpentine soil than did serpentine legumes. Therefore, this invasive legume has undergone the rapid evolution of divergence for soil-specific investment in the mutualism. Contrary to theoretical expectations, the mutualism was less beneficial for legumes grown on the stressful serpentine soil than on the non-serpentine soil, possibly due to the inhibitory effects of serpentine on the benefits derived from the interaction. The soil-specific ability to allocate to a robust microbial mutualism may be a critical, and previously overlooked, adaptation for plants adapting to heterogeneous environments during invasion.

  7. Machine Learning to Assess Grassland Productivity in Southeastern Arizona

    Science.gov (United States)

    Ponce-Campos, G. E.; Heilman, P.; Armendariz, G.; Moser, E.; Archer, V.; Vaughan, R.

    2015-12-01

    We present preliminary results of machine learning (ML) techniques modeling the combined effects of climate, management, and inherent potential on productivity of grazed semi-arid grasslands in southeastern Arizona. Our goal is to support public land managers determine if agency management policies are meeting objectives and where to focus attention. Monitoring in the field is becoming more and more limited in space and time. Remotely sensed data cover the entire allotments and go back in time, but do not consider the key issue of species composition. By estimating expected vegetative production as a function of site potential and climatic inputs, management skill can be assessed through time, across individual allotments, and between allotments. Here we present the use of Random Forest (RF) as the main ML technique, in this case for the purpose of regression. Our response variable is the maximum annual NDVI, a surrogate for grassland productivity, as generated by the Google Earth Engine cloud computing platform based on Landsat 5, 7, and 8 datasets. PRISM 33-year normal precipitation (1980-2013) was resampled to the Landsat scale. In addition, the GRIDMET climate dataset was the source for the calculation of the annual SPEI (Standardized Precipitation Evapotranspiration Index), a drought index. We also included information about landscape position, aspect, streams, ponds, roads and fire disturbances as part of the modeling process. Our results show that in terms of variable importance, the 33-year normal precipitation, along with SPEI, are the most important features affecting grasslands productivity within the study area. The RF approach was compared to a linear regression model with the same variables. The linear model resulted in an r2 = 0.41, whereas RF showed a significant improvement with an r2 = 0.79. We continue refining the model by comparison with aerial photography and to include grazing intensity and infrastructure from units/allotments to assess the

  8. Land-use intensification causes multitrophic homogenization of grassland communities.

    Science.gov (United States)

    Gossner, Martin M; Lewinsohn, Thomas M; Kahl, Tiemo; Grassein, Fabrice; Boch, Steffen; Prati, Daniel; Birkhofer, Klaus; Renner, Swen C; Sikorski, Johannes; Wubet, Tesfaye; Arndt, Hartmut; Baumgartner, Vanessa; Blaser, Stefan; Blüthgen, Nico; Börschig, Carmen; Buscot, Francois; Diekötter, Tim; Jorge, Leonardo Ré; Jung, Kirsten; Keyel, Alexander C; Klein, Alexandra-Maria; Klemmer, Sandra; Krauss, Jochen; Lange, Markus; Müller, Jörg; Overmann, Jörg; Pašalić, Esther; Penone, Caterina; Perović, David J; Purschke, Oliver; Schall, Peter; Socher, Stephanie A; Sonnemann, Ilja; Tschapka, Marco; Tscharntke, Teja; Türke, Manfred; Venter, Paul Christiaan; Weiner, Christiane N; Werner, Michael; Wolters, Volkmar; Wurst, Susanne; Westphal, Catrin; Fischer, Markus; Weisser, Wolfgang W; Allan, Eric

    2016-12-08

    Land-use intensification is a major driver of biodiversity loss. Alongside reductions in local species diversity, biotic homogenization at larger spatial scales is of great concern for conservation. Biotic homogenization means a decrease in β-diversity (the compositional dissimilarity between sites). Most studies have investigated losses in local (α)-diversity and neglected biodiversity loss at larger spatial scales. Studies addressing β-diversity have focused on single or a few organism groups (for example, ref. 4), and it is thus unknown whether land-use intensification homogenizes communities at different trophic levels, above- and belowground. Here we show that even moderate increases in local land-use intensity (LUI) cause biotic homogenization across microbial, plant and animal groups, both above- and belowground, and that this is largely independent of changes in α-diversity. We analysed a unique grassland biodiversity dataset, with abundances of more than 4,000 species belonging to 12 trophic groups. LUI, and, in particular, high mowing intensity, had consistent effects on β-diversity across groups, causing a homogenization of soil microbial, fungal pathogen, plant and arthropod communities. These effects were nonlinear and the strongest declines in β-diversity occurred in the transition from extensively managed to intermediate intensity grassland. LUI tended to reduce local α-diversity in aboveground groups, whereas the α-diversity increased in belowground groups. Correlations between the β-diversity of different groups, particularly between plants and their consumers, became weaker at high LUI. This suggests a loss of specialist species and is further evidence for biotic homogenization. The consistently negative effects of LUI on landscape-scale biodiversity underscore the high value of extensively managed grasslands for conserving multitrophic biodiversity and ecosystem service provision. Indeed, biotic homogenization rather than local diversity

  9. What went wrong in California's electricity market?

    International Nuclear Information System (INIS)

    Chikeung Woo

    2001-01-01

    The California electricity market reform promised to deliver reliable service at low and stable prices. Frequent capacity shortages and the ensuing rolling black-outs, price spikes, and large price volatility since Summer 2000 raise a simple but substantive question: what went wrong? The answer to this question will help countries contemplating electricity market reform not to commit similar mistakes. We find the answer by identifying the major factors that have turned the California dream into a nightmare. Such factors include poor market design, market power, sustained demand growth not matched by new capacity, rising marginal cost, and financial insolvency. Proposed remedies include an alternative market settlement process, long-term contract, fast licensing and siting process for new generation and transmission, conservation and energy-efficiency, distributed resources, rate options, and debt restructuring. The California experience suggests that a reversible regulatory reform is a safe alternative to an irreversible market reform. (Author)

  10. Grassland carbon sequestration and emissions following cultivation in a mixed crop rotation

    DEFF Research Database (Denmark)

    Acharya, Bharat Sharma; Rasmussen, Jim; Eriksen, Jørgen

    2012-01-01

    Grasslands are potential carbon sinks to reduce unprecedented increase in atmospheric CO2. Effect of age (1–4-year-old) and management (slurry, grazing multispecies mixture) of a grass phase mixed crop rotation on carbon sequestration and emissions upon cultivation was compared with 17-year...... biomass was highest in 4-year-old grassland, but all 1–4-year-old grasslands were in between the pea field (0.81 ± 0.094 g kg−1 soil) and the 17-year-old grassland (3.17 ± 0.22 g kg−1 soil). Grazed grasslands had significantly higher root biomass than cut grasslands. There was no significant difference...... in the CO2 emissions within 1–4-year-old grasslands. Only the 17-year-old grassland showed markedly higher CO2 emissions (4.9 ± 1.1 g CO2 kg−1 soil). Differences in aboveground and root biomass did not affect CO2 emissions, and slurry application did not either. The substantial increase in root biomass...

  11. Response of predominant soil bacteria to grassland succession as monitored by ribosomal RNA analyses

    NARCIS (Netherlands)

    Felske, A.

    1999-01-01

    The research described in this thesis was aimed to provide insight into the effects of grassland succession on the composition of the soil bacteria community in the Drentse A agricultural research area. The Drentse A meadows represent grassland succession at different stages. Since 30 years

  12. Modelling the carbon cycle of grassland in the Netherlands under various management strategies and environmental conditions.

    NARCIS (Netherlands)

    Pol-van Dasselaar, van den A.; Lantinga, E.A.

    1995-01-01

    A simulation model of the grassland carbon cycle (CCGRASS) was developed to evaluate the long-term effects of different management strategies and various environmental conditions on carbon sequestration in a loam soil under permanent grassland in the Netherlands. The model predicted that the rate of

  13. The Impact of Ecological Construction Programs on Grassland Conservation in Inner Mongolia, China

    NARCIS (Netherlands)

    Liu, Min; Dries, Liesbeth; Heijman, Wim; Huang, Jikun; Zhu, Xueqin; Hu, Yuanning; Chen, Haibin

    2018-01-01

    A series of Ecological Construction Programs have been initiated to protect the condition of grasslands in China during recent decades. However, grassland degradation is still severe, and conditions have not been restored as intended. This paper aims to empirically examine the effectiveness of these

  14. 78 FR 19444 - Pawnee National Grassland, Colorado; Oil and Gas Leasing Analysis Environmental Impact Statement

    Science.gov (United States)

    2013-04-01

    ... Leasing Analysis on the Pawnee National Grassland (PNG), was signed. That decision determined which Lands... National Grassland. Much of the PNG's federal mineral estate made available per the 1997 ROD has already... [36 CFR 228.102(e)]. Accordingly, the PNG finds it is necessary to disclose the potential effects of...

  15. Long-term after-effects of fertilisation on restoration of calcareous grasslands

    NARCIS (Netherlands)

    Smits, N.A.C.; Bobbink, R.; Willems, J.H.

    2008-01-01

    Question: What are the long-term implications of former fertilisation for the ecological restoration of calcareous grasslands? Location: Gerendal, Limburg, The Netherlands. Methods: In 1970, ten permanent plots were established in just abandoned agricultural calcareous grassland under a regime of

  16. 77 FR 75119 - Dakota Prairie Grasslands, North Dakota; Oil and Gas Development Supplemental Environmental...

    Science.gov (United States)

    2012-12-19

    ... DEPARTMENT OF AGRICULTURE Forest Service Dakota Prairie Grasslands, North Dakota; Oil and Gas... to prepare a supplemental environmental impact statement. SUMMARY: In June of 2003, the Dakota... Dakota Prairie Grasslands Land and Resource Management Plan, based on the 2001 Northern Great Plains...

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

    Science.gov (United States)

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

    2015-01-01

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

  18. Efficacy of exclosures in conserving local shrub biodiversity in xeric sandy grassland, Inner Mongolia, China

    Science.gov (United States)

    Feng-Rui Li; Zhi-Yu Zhou; Li-Ya Zhao; Ai-Sheng Zhang; Ling-Fen Kang

    2007-01-01

    This study investigated the abundance and frequency of occurrence of all shrub species present in the standing vegetation at four sites, including a 5-year exclosure (protected grassland) and three adjacent unprotected grazing sites that had been subjected to different levels of degradation (light, moderate and severe), in xeric sandy grassland of Inner Mongolia for...

  19. Variation in soil organic carbon within highland grasslands of Langtang National Park, Nepal

    Directory of Open Access Journals (Sweden)

    Keshab Shrestha

    2016-09-01

    Full Text Available Grassland also plays important role in food security. The estimated grassland area in Nepal is about 1.75 million ha. Most of the grassland in Nepal is located in higher elevation above, 2000 meter. The aim of this research is to observe difference in SOC of grassland in different altitude. Soil samples were collected from grasslands of altitude: 1500- 2000m, 2001- 2500m, 2501-3000m, 3001- 3500m and 3501- 4000m. The soil samples were collected at successive depths in each grassland i.e. 0 – 10 cm, 10 – 20 cm and 20 – 30 cm. The maximum SOC was found in grassland at altitude 3001 m- 3500m. The lowest was SOC was found in grassland at altitude 3051m – 4000m. Correlation analysis between altitude and SOC shows that SOC is positively correlated with altitude with correlation coefficient 0.850 (significant at P<0.05 level. But SOC decreases sharply in treeline with negative correlation (Significant at P<0.05.International Journal of Environment Vol.5(3 2016, pp.57-65

  20. Grassland simulation with the LPJmL model : version 3.4.018

    NARCIS (Netherlands)

    Boons-Prins, E.R.

    2010-01-01

    One third of the land surface is covered with natural and cultivated grasslands. Most of these grasslands are intensively or extensively exploited by humans to feed animals. With growing wealth, causing an increase of meat consumption, there is a need to better understand the processes that

  1. Effects of nitrogen fertilization and grazing on the emission of nitrous oxide from grassland

    Energy Technology Data Exchange (ETDEWEB)

    Velthof, G.L.; Brader, A.B.; Oenema, O. [NMI, Dept. of Soil Science and Plant Nutrition, Wageningen Agricultural Univ. (Netherlands)

    1995-11-01

    In the Netherlands, managed grasslands are potentially a large source of nitrous oxide (N{sub 2}O), because of the large nitrogen (N) input and the relatively high ground water levels. To provide insight into the major factors that contribute to N{sub 2}O emission from grassland and to provide quantitative N{sub 2}O emission rates, a monitoring study was carried out on four sites, during March 1992 to March 1994. Fluxes of N{sub 2}O increased after N fertilizer application and grazing, especially during wet conditions. Fluxes were higher from peat soils than from sand and clay soils. Fluxes were low during the winter periods. Total N{sub 2}O losses were 2 to 4.5 times higher on grassland fertilized with 160-460 kg N ha{sup -1} yr{sup -1} than on unfertilized grassland. Losses from grazed grasslands were 1.5 to 3.5 times higher than losses from mown grassland. This study shows that management practice of grassland and soil type are major factors controlling N{sub 2}O emission from grasslands. 2 figs., 3 refs.

  2. Balance matters : N:P stoichiometry and plant diversity in grassland ecosystems

    NARCIS (Netherlands)

    Fujita, Y.

    2010-01-01

    Eutrophication of Nitrogen (N) and Phosphorus (P) is threatening the functioning and biodiversity of grassland ecosystems. A well known effect of eutrophication on grasslands is an increase of above-ground productivity, which intensifies light competition and allows only a few competitive species to

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

    Science.gov (United States)

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

  4. Vascular plants and a brief history of the Kiowa and Rita Blanca National Grasslands

    Science.gov (United States)

    Donald L. Hazlett; Michael H. Schiebout; Paulette L. Ford

    2009-01-01

    Administered by the USDA Forest Service, the Kiowa and Rita Blanca National Grasslands occupy 230,000 acres of public land extending from northeastern New Mexico into the panhandles of Oklahoma and Texas. A mosaic of topographic features including canyons, plateaus, rolling grasslands and outcrops supports a diverse flora. Eight hundred twenty six (826) species of...

  5. Spatial patterns of grasses and shrubs in an arid grassland environment

    Science.gov (United States)

    In the Chihuahuan Desert of Mexico and New Mexico, shrub invasion is a common problem, and once-abundant grassland ecosystems are being replaced by shrub-dominated habitat. The spatial arrangement of grasses and shrubs in these arid grasslands can provide better insight into community dynamics and c...

  6. Linear objects impact on grassland degradation in the typical steppe region of China

    NARCIS (Netherlands)

    Li, Suying; Verburg, Peter H.; Lv, Shihai; Gao, Shangyu; Wu, Jingle

    2011-01-01

    Despite growing recognition of the issue of grassland degradation, few regional estimates of linear object impacts on grassland degradation [1]. We presented a methodology for evaluating regional impacts on steppe degradation from linear objects which were two uppermost types, rivers and roads, in

  7. Secondary succession after fire in Imperata grasslands of East Kalimantan Indonesia

    NARCIS (Netherlands)

    Yassir, I.; Kamp, van der J.; Buurman, P.

    2010-01-01

    Regeneration of grassland areas is becoming increasingly important, not only to create new secondary forest and recover the original biodiversity, but also recover for agriculture. We studied an early succession in Imperata grasslands in East Kalimantan, Indonesia, using plots that last burned 3

  8. Potential of endozoochorous seed dispersal by sheep in calcareous grasslands: correlations with seed traits.

    NARCIS (Netherlands)

    Kuiters, A.T.; Huiskes, H.P.J.

    2010-01-01

    Questions: What is the potential of sheep to serve as seed dispersers via ingestion and defecation in calcareous grasslands? Is the presence of viable seeds from dung correlated with specific seed traits? Location: Calcareous grasslands, South Limburg, the Netherlands/Belgium. Methods: Dung samples

  9. Hemiptera community and species responses to grassland sward islets

    OpenAIRE

    Helden, Alvin J.; Dittrich, Alex D. K.

    2016-01-01

    Sward islet is a term that has been used to describe a patch of longer vegetation in a pasture produced by a reduction in cattle grazing around their dung. They are known to affect the abundance and distribution of grassland arthropods. Hemiptera, like other groups, are found in higher densities within islets than the surrounding sward. Does this modify the community composition or is there just a density effect? Evidence from a paired (islets, non-islets) study at an Irish cattle-grazed site...

  10. Organic matter dynamics and N mineralization in grassland soils

    OpenAIRE

    Hassink, J.

    1995-01-01


    The aims of this study are i) to improve our understanding of the interactions between soil texturelsoil structure, soil organic matter, soil biota and mineralization in grassland soils, ii) to develop a procedure that yields soil organic matter fractions that can be determined directly and can be used in soil organic matter models, iii) to develop a model that predicts the long-term dynamics of soil organic matter, iv) to develop a simple model that can be used by farmers and advi...

  11. Aerosol fluxes and particle growth above managed grassland

    Directory of Open Access Journals (Sweden)

    E. Nemitz

    2009-08-01

    Full Text Available Particle deposition velocities (11–3000 nm diameter measured above grassland by eddy covariance during the EU GRAMINAE experiment in June 2000 averaged 0.24 and 0.03 mm s−1 to long (0.75 m and short (0.07 m grass, respectively. After fertilisation with 108 kg N ha−1 as calcium ammonium nitrate, sustained apparent upward fluxes of particles were observed. Analysis of concentrations and fluxes of potential precursor gases, including NH3, HNO3, HCl and selected VOCs, shows that condensation of HNO3 and NH3 on the surface of existing particles is responsible for this effect. A novel approach is developed to derive particle growth rates at the field scale, from a combination of measurements of vertical fluxes and particle size-distributions. For the first 9 days after fertilization, growth rates of 11 nm particles of 7.04 nm hr−1 and 1.68 nm hr−1 were derived for day and night-time conditions, respectively. This implies total NH4NO3 production rates of 1.11 and 0.44 μg m−3 h−1, respectively. The effect translates into a small error in measured ammonia fluxes (0.06% day, 0.56% night and a large error in NH4+ and NO3 aerosol fluxes of 3.6% and 10%, respectively. By converting rapidly exchanged NH3 and HNO3 into slowly depositing NH4NO3, the reaction modifies the total N budget, though this effect is small (<1% for the 10 days following fertilization, as NH3 emission dominates the net flux. It is estimated that 3.8% of the fertilizer N was volatilised as NH3, of which 0.05% re-condensed to form NH4NO3 particles within the lowest 2 m of the surface layer. This surface induced process would at least scale up to a global NH4NO3 formation of ca. 0.21 kt N yr

  12. How Fencing Affects the Soil Quality and Plant Biomass in the Grassland of the Loess Plateau.

    Science.gov (United States)

    Zeng, Quanchao; Liu, Yang; Xiao, Li; Huang, Yimei

    2017-09-25

    Overgrazing is a severe problem in several regions in Northwestern China and has caused serious land degradation. Secondary natural succession plays an important role in the accumulation of soil carbon and nitrogen contents. Estimating the effects of grazing exclusion on soil quality and plant diversity will improve our understanding of the succession process after overgrazing and promote judicious management of degraded pastures. This experiment was designed to measure soil properties and plant diversity following an age chronosequence of grasslands (ages ranged from one year, 12 years, 20 years, and 30 years) in Northwestern China. The results showed that continuous fencing resulted in a considerable increase in plant coverage, plant biomass (above- and below-ground biomass), and plant diversity, which can directly or indirectly improve the accumulation of soil organic carbon and total nitrogen content. The plant coverage and the above- and below-ground biomass linearly increased along the succession time, whereas soil organic C and N contents showed a significant decline in the first 12 years and, subsequently, a significant increase. The increased plant biomass caused an increase in soil organic carbon and soil total nitrogen. These results suggested that soil restoration and plant cover were an incongruous process. Generally, soil restoration is a slow process and falls behind vegetation recovery after grazing exclusion. Although the accumulation of soil C and N stocks needed a long term, vegetation restoration was a considerable option for the degraded grassland due to the significant increase of plant biomass, diversity, and soil C and N stocks. Therefore, fencing with natural succession should be considered in the design of future degraded pastures.

  13. Mineralogical Controls over Carbon Storage and Residence Times in Grassland Soils

    Science.gov (United States)

    Dwivedi, D.; Riley, W. J.; Torn, M. S.; Spycher, N.

    2014-12-01

    Globally, soil organic matter (SOM) contains approximately three times more carbon than the atmosphere and terrestrial vegetation contain combined. However, it is not well understood why some SOM persists for a long time while other SOM decomposes quickly. For future climate predictions, representing soil organic matter (SOM) dynamics accurately in Earth system models is essential. Soil minerals stabilize organic carbon in soil; however, there are gaps in our understanding of how soil mineralogy controls the quantity and turnover of long-residence-time organic carbon. To investigate the impact of soil mineralogy on SOM dynamics, we used a new model (Biotic and Abiotic Model of SOM—BAMS1 [Riley et al., 2014]) integrated with a three-dimensional, multiphase reactive transport solver (TOUGHREACT). The model represents bacterial and fungal activity, archetypal polymer and monomer carbon substrate groups, aqueous chemistry, gaseous diffusion, aqueous advection and diffusion, and adsorption and desorption processes. BAMS1 can predict bulk SOM and radiocarbon signatures without resorting to an arbitrary depth-dependent decline in SOM turnover rates. Results show a reasonable match between observed and simulated depth-resolved SOM and Δ14C in grassland ecosystems (soils formed on terraces south of Eureka, California, and the Central Chernozem Region of Russia) and were consistent with expectations of depth-resolved profiles of lignin content and fungi:aerobic bacteria ratios. Results also suggest that clay-mineral surface area and soil sorption coefficients constitute dominant controls over organic carbon stocks and residence times, respectively. Bibliography: Riley, W.J., F.M. Maggi, M. Kleber, M.S. Torn, J.Y. Tang, D. Dwivedi, and N. Guerry (2014), Long residence times of rapidly decomposable soil organic matter: application of a multi-phase, multi-component, and vertically resolved model (BAMS1) to soil carbon dynamics, Geoscientific Model Development, vol. 7, 1335

  14. SWFSC/MMTD/CCE: Oregon, California, and Washington Line-transect Experiment (ORCAWALE) 1996, 2001, 2008 and CA Current Cetacean and Ecosystem Assessment Survey (CalCurCEAS) 2014

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The California Current Cetacean and Ecosystem Assessment Survey (CalCurCEAS) is a marine mammal assessment survey of the U.S. West Coast waters. Similar research in...

  15. Surplus Facilities Management Program. Post remedial action survey report for the Sodium Reactor Experiment (SRE) facility, Santa Susana Field Laboratories, Rockwell International, Ventura County, California

    International Nuclear Information System (INIS)

    Wynveen, R.A.; Smith, W.H.; Sholeen, C.M.; Flynn, K.F.; Justus, A.L.

    1984-02-01

    Decontamination of the Sodium Reactor Experiment (SRE) began in 1976 and was completed in 1982. In view of the concurrent and post-remedial-action surveys, the following conclusions can be stated. All the buildings and areas included in this decommissioning project have been decontaminated to below the limits specified in the draft ANSI Standard N13.12 and the NRC Guidelines for Decontamination of Facilities and Equipment Prior to Release for Unrestricted Use or Termination of Licenses for By-Product, Source, or Special Nuclear Material, dated July 1982. Radioactive contamination was found in appropriate access points of the sanitary sewer and storm drain systems included within the boundaries of this decommissioning project. One sample indicated a 90 Sr concentration dissolved in the water of approximately half the recommended water concentration for controlled areas and approximately 15 times the recommended water concentration for uncontrolled areas as stated in DOE-5480.1 Chg. 6, Chapter XI. Therefore, the interior inaccessible surfaces of these systems must be considered contaminated in accordance with statements found in the NRC Regulatory Guidelines issued in July 1982. Effluent from the outfall of this drain system must also be considered as being potentially contaminated. 1 reference, 32 figures, 8 tables

  16. Mapping spatio-temporal variation of grassland quantity and quality using MERIS data and the PROSAIL model

    NARCIS (Netherlands)

    Si, Y.; Schlerf, M.; Zurita-Milla, R.; Skidmore, A.K.; Wang, T.

    2012-01-01

    Accurate estimates of the quantity and quality of grasslands, as they vary in space and time and from regional to global scales, furthers our understanding of grassland ecosystems. The Medium Resolution Imaging Spectrometer (MERIS) is a promising sensor for measuring and monitoring grasslands due to

  17. 78 FR 65609 - Medicine Bow-Routt National Forests and Thunder Basin National Grassland; Wyoming; Thunder Basin...

    Science.gov (United States)

    2013-11-01

    ... National Grassland; Wyoming; Thunder Basin National Grassland Prairie Dog Amendment Environmental Impact... Cooperating Agencies. No changes to the Proposed Action or Purpose of and Need for Action have been made... alternatives will be analyzed in the Thunder Basin National Grassland Prairie Dog Amendment EIS. The EIS will...

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

    Directory of Open Access Journals (Sweden)

    Lu Wen

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

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

    Science.gov (United States)

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

    2013-01-01

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

  20. Grasslands of Mexico: A perspective on their conservation (Los pastizales del norte de Mexico: Una perspectiva para su conservacion)

    Science.gov (United States)

    Patricia Manzano; Rurik List

    2006-01-01

    Grasslands are areas dominated by grasses and herbs with few or no trees. Grasslands receive too much rain for a desert environment and too little for a forest. Temperate North American grasslands, especially, have undergone changes on a continental level. Their high productivity and fertility, added to their level topography and lack of trees, make them ideal sites...

  1. Groundwater quality in the Antelope Valley, California

    Science.gov (United States)

    Dawson, Barbara J. Milby; Belitz, Kenneth

    2012-01-01

    Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. Antelope Valley is one of the study areas being evaluated. The Antelope study area is approximately 1,600 square miles (4,144 square kilometers) and includes the Antelope Valley groundwater basin (California Department of Water Resources, 2003). Antelope Valley has an arid climate and is part of the Mojave Desert. Average annual rainfall is about 6 inches (15 centimeters). The study area has internal drainage, with runoff from the surrounding mountains draining towards dry lakebeds in the lower parts of the valley. Land use in the study area is approximately 68 percent (%) natural (mostly shrubland and grassland), 24% agricultural, and 8% urban. The primary crops are pasture and hay. The largest urban areas are the cities of Palmdale and Lancaster (2010 populations of 152,000 and 156,000, respectively). Groundwater in this basin is used for public and domestic water supply and for irrigation. The main water-bearing units are gravel, sand, silt, and clay derived from surrounding mountains. The primary aquifers in Antelope Valley are defined as those parts of the aquifers corresponding to the perforated intervals of wells listed in the California Department of Public Health database. Public-supply wells in Antelope Valley are completed to depths between 360 and 700 feet (110 to 213 meters), consist of solid casing from the land surface to a depth of 180 to 350 feet (55 to 107 meters), and are screened or perforated below the solid casing. Recharge to the groundwater system is primarily runoff from the surrounding mountains, and by direct infiltration of irrigation and sewer and septic

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

    OpenAIRE

    Chang, Jinfeng; Ciais, Philippe; Viovy, Nicolas; Soussana, Jean-Fran?ois; Klumpp, Katja; Sultan, Benjamin

    2017-01-01

    Background Europe has warmed more than the global average (land and ocean) since pre-industrial times, and is also projected to continue to warm faster than the global average in the twenty-first century. According to the climate models ensemble projections for various climate scenarios, annual mean temperature of Europe for 2071?2100 is predicted to be 1?5.5??C higher than that for 1971?2000. Climate change and elevated CO2 concentration are anticipated to affect grassland management and liv...

  3. Private Schools, California, 2009, California Department of Education

    Data.gov (United States)

    U.S. Environmental Protection Agency — California law (California Education Code Section 33190) requires private schools offering or conducting a full-time elementary or secondary level day school for...

  4. The California Hazards Institute

    Science.gov (United States)

    Rundle, J. B.; Kellogg, L. H.; Turcotte, D. L.

    2006-12-01

    California's abundant resources are linked with its natural hazards. Earthquakes, landslides, wildfires, floods, tsunamis, volcanic eruptions, severe storms, fires, and droughts afflict the state regularly. These events have the potential to become great disasters, like the San Francisco earthquake and fire of 1906, that overwhelm the capacity of society to respond. At such times, the fabric of civic life is frayed, political leadership is tested, economic losses can dwarf available resources, and full recovery can take decades. A patchwork of Federal, state and local programs are in place to address individual hazards, but California lacks effective coordination to forecast, prevent, prepare for, mitigate, respond to, and recover from, the harmful effects of natural disasters. Moreover, we do not know enough about the frequency, size, time, or locations where they may strike, nor about how the natural environment and man-made structures would respond. As California's population grows and becomes more interdependent, even moderate events have the potential to trigger catastrophes. Natural hazards need not become natural disasters if they are addressed proactively and effectively, rather than reactively. The University of California, with 10 campuses distributed across the state, has world-class faculty and students engaged in research and education in all fields of direct relevance to hazards. For that reason, the UC can become a world leader in anticipating and managing natural hazards in order to prevent loss of life and property and degradation of environmental quality. The University of California, Office of the President, has therefore established a new system-wide Multicampus Research Project, the California Hazards Institute (CHI), as a mechanism to research innovative, effective solutions for California. The CHI will build on the rich intellectual capital and expertise of the Golden State to provide the best available science, knowledge and tools for

  5. BETA DIVERSITY AND COMMUNITY DIFFERENTIATION IN DRY PERENNIAL SAND GRASSLANDS

    Directory of Open Access Journals (Sweden)

    E. KOVACS-LANG

    2011-01-01

    Full Text Available The spatial variability of species composition was studied in perennial sand grasslands in Hungary at multiple scales. Three sites were compared along an aridity gradient. Existing differences in climate along this ca. 200 km gradient correspond to regional climate changes predicted for the next 20-30 years. Six stands of Festucetum vaginatae grasslands were selected at each site within 400 x 1200 m areas for representing the coarse-scale within-site heterogeneity. Fine-scale compositional heterogeneity of vegetation within stands was sampled by recording the presence of species along 52 m long circular belt transects of 1040 units of 5 cm x 5 cm contiguous microquadrats. This sampling design enabled us to study the patterns of species combinations at a wide range of scales. The highest variability of plant species combinations appeared at very fine scales, between 10 cm and 25 cm. Differences in beta diversity along the gradient were scale-dependent. We found a decreasing trend of beta diversity with increasing aridity at fine scale, and on the contrary, an increasing trend at landscape scale. We conclude that the major trend of the vegetation differentiation due to aridity is the decrease of compositional variability at fine-scale accompanied by a coarse-scale diversification.

  6. Weathering controls on mechanisms of carbon storage in grassland soils

    Science.gov (United States)

    Masiello, C.A.; Chadwick, O.A.; Southon, J.; Torn, M.S.; Harden, J.W.

    2004-01-01

    On a sequence of soils developed under similar vegetation, temperature, and precipitation conditions, but with variations in mineralogical properties, we use organic carbon and 14C inventories to examine mineral protection of soil organic carbon. In these soils, 14C data indicate that the creation of slow-cycling carbon can be modeled as occurring through reaction of organic ligands with Al3+ and Fe3+ cations in the upper horizons, followed by sorption to amorphous inorganic Al compounds at depth. Only one of these processes, the chelation Al3+ and Fe3+ by organic ligands, is linked to large carbon stocks. Organic ligands stabilized by this process traverse the soil column as dissolved organic carbon (both from surface horizons and root exudates). At our moist grassland site, this chelation and transport process is very strongly correlated with the storage and long-term stabilization of soil organic carbon. Our 14C results show that the mechanisms of organic carbon transport and storage at this site follow a classic model previously believed to only be significant in a single soil order (Spodosols), and closely related to the presence of forests. The presence of this process in the grassland Alfisol, Inceptisol, and Mollisol soils of this chronosequence suggests that this process is a more significant control on organic carbon storage than previously thought. Copyright 2004 by the American Geophysical Union.

  7. Does plant diversity affect the water balance of established grassland systems?

    Science.gov (United States)

    Leimer, Sophia; Bischoff, Sebastian; Blaser, Stefan; Boch, Steffen; Busch, Verena; Escher, Peter; Fischer, Markus; Kaupenjohann, Martin; Kerber, Katja; Klaus, Valentin; Michalzik, Beate; Prati, Daniel; Schäfer, Deborah; Schmitt, Barbara; Schöning, Ingo; Schwarz, Martin T.; Siemens, Jan; Thieme, Lisa; Wilcke, Wolfgang

    2017-04-01

    The water cycle drives nutrient cycles and plant productivity. The impact of land use on the water cycle has been extensively studied and there is experimental evidence that biodiversity modifies the water cycle in grasslands. However, the combined influences of land-use and associated biodiversity on the water cycle in established land-use systems are unclear. Therefore, we investigated how evapotranspiration (ETa), downward water flux (DF), and capillary rise (CR) in topsoil and subsoil are related to land-use and plant diversity in established, commercially managed grassland and compared these results to findings from experiments where plant diversity was manipulated. In three Central European regions ("Biodiversity Exploratories"), we studied 29 grassland plots (50 m x 50 m; 9-11 plots per region) from 2010 to 2015. The land-use types cover pasture, mown pasture, and meadow in at least triplicate per region. On each plot, we measured soil water contents, meteorological data (hourly resolution), cumulative precipitation (biweekly), plant species richness, the number of plants in the functional groups of grasses, herbs, and legumes (annually), and root biomass (once). Potential evapotranspiration (ETp) was calculated from meteorological data per plot. Missing data points of ETp and soil water contents were estimated with Bayesian hierarchical models. ETa, DF, and CR were calculated for two soil layers with a soil water balance model. The model is based on changes in soil water storage between subsequent observation dates and ETp, which was partitioned between soil layers according to root distribution. Water fluxes in annual resolution were statistically analyzed for land-use and biodiversity effects using repeated-measures analysis of variance (ANOVA). Land-use type did not affect water fluxes. Species richness did not influence DF and CR. DF from topsoil was higher on plots with more grass species, which is opposite to the results from a manipulative

  8. Sex-related differences in habitat associations of wintering American Kestrels in California's Central Valley

    Science.gov (United States)

    Pandolfino, E.R.; Herzog, M.P.; Smith, Z.

    2011-01-01

    We used roadside survey data collected from 19 routes over three consecutive winters from 200708 to 200910 to compare habitat associations of male and female American Kestrels (Falco sparverius) in the Central Valley of California to determine if segregation by sex was evident across this region. As a species, American Kestrels showed positive associations with alfalfa and other forage crops like hay and winter wheat, as well as grassland, irrigated pasture, and rice. Habitat associations of females were similar, with female densities in all these habitats except rice significantly higher than average. Male American Kestrels showed a positive association only with grassland and were present at densities well below those of females in alfalfa, other forage crops, and grassland. Males were present in higher densities than females in most habitats with negative associations for the species, such as orchards, urbanized areas, and oak savannah. The ratio of females to males for each route was positively correlated with the overall density of American Kestrels on that route. Our findings that females seem to occupy higher quality habitats in winter are consistent with observations from elsewhere in North America. ?? 2011 The Raptor Research Foundation, Inc.

  9. Short-term bioavailability of carbon in soil organic matter fractions of different particle sizes and densities in grassland ecosystems.

    Science.gov (United States)

    Breulmann, Marc; Masyutenko, Nina Petrovna; Kogut, Boris Maratovich; Schroll, Reiner; Dörfler, Ulrike; Buscot, François; Schulz, Elke

    2014-11-01

    The quality, stability and availability of organic carbon (OC) in soil organic matter (SOM) can vary widely between differently managed ecosystems. Several approaches have been developed for isolating SOM fractions to examine their ecological roles, but links between the bioavailability of the OC of size-density fractions and soil microbial communities have not been previously explored. Thus, in the presented laboratory study we investigated the potential bioavailability of OC and the structure of associated microbial communities in different particle-size and density fractions of SOM. For this we used samples from four grassland ecosystems with contrasting management intensity regimes and two soil types: a Haplic Cambisol and a typical Chernozem. A combined size-density fractionation protocol was applied to separate clay-associated SOM fractions (CF1, <1 μm; CF2, 1-2 μm) from light SOM fractions (LF1, <1.8 g cm(-3); LF2, 1.8-2.0 g cm(-3)). These fractions were used as carbon sources in a respiration experiment to determine their potential bioavailability. Measured CO2-release was used as an index of substrate accessibility and linked to the soil microbial community structure, as determined by phospholipid fatty acids (PLFA) analysis. Several key factors controlling decomposition processes, and thus the potential bioavailability of OC, were identified: management intensity and the plant community composition of the grasslands (both of which affect the chemical composition and turnover of OC) and specific properties of individual SOM fractions. The PLFA patterns highlighted differences in the composition of microbial communities associated with the examined grasslands, and SOM fractions, providing the first broad insights into their active microbial communities. From observed interactions between abiotic and biotic factors affecting the decomposition of SOM fractions we demonstrate that increasing management intensity could enhance the potential bioavailability of

  10. Ammonia emission from a permanent grassland on volcanic soil after the treatment with dairy slurry and urea

    Science.gov (United States)

    Salazar, F.; Martínez-Lagos, J.; Alfaro, M.; Misselbrook, T.

    2014-10-01

    Ammonia (NH3) is an air pollutant largely emitted from agricultural activities including the application of livestock manures and fertilizers to grassland. This gas has been linked with important negative impacts on natural ecosystems. In southern Chile, the use of inorganic and organic fertilizers (e.g. slurries) has increased in cattle production systems over recent years, heightening the risk of N losses to the wider environment. The objectives of this study were to evaluate on permanent grasslands on a volcanic ash soil in southern Chile: 1) the N loss due to NH3 volatilization following surface application of dairy slurry and urea fertilizer; and 2) the effect of a urease inhibitor on NH3 emissions from urea fertilizer application. Small plot field experiments were conducted over spring, fall, winter and summer seasons, using a system of wind tunnels to measure ammonia emissions. Ammonia losses ranged from 1.8 (winter) to 26.0% (fall) and 3.1 (winter) to 20.5% (summer) of total N applied for urea and slurry, respectively. Based on the readily available N applied (ammoniacal N for dairy slurry and urea N for urea fertilizer), losses from dairy slurry were much greater, at 16.1 and 82.0%, for winter and summer, respectively. The use of a urease inhibitor proved to be an effective option to minimize the N loss due NH3 volatilization from urea fertilizer, with an average reduction of 71% across all seasons. The results of this and other recent studies regarding N losses suggest that ammonia volatilization is the main pathway of N loss from grassland systems in southern Chile on volcanic ash soils when urea and slurry are used as an N source. The use of good management practices, such as the inclusion of a urease inhibitor with urea fertilizer could have a beneficial impact on reducing N losses due NH3 volatilization and the environmental and economic impact of these emissions.

  11. N management of European grasslands: can the exchange of gaseous N species be influenced at the operational level?

    Science.gov (United States)

    Calanca, P; Neftel, A; Fuhrer, J

    2001-11-30

    Grassland ecosystems can be regarded as biochemical reactors in which large amounts of organic nitrogen (N) are converted into inorganic N, and vice versa. If managed in a sustainable manner, grasslands should operate in a quasi steady state, characterized by an almost perfect balance between total N input and output. As a consequence, the exchange of gaseous N species (NH3, NO, NO2, N2O, and N2) between grasslands and the atmosphere is very small compared to the total N turnover. In this study, the effects of two management options (mowing and fertilization) on production and emission of nitrous oxide (N2O) from a grass/clover crop were examined on the basis of observations and model results referring to an experiment carried out on the Swiss Plateau in late summer of 2000. It was found that production and emission of N2O induced by mowing were of the same order of magnitude as those brought about by fertilization, suggesting a possible transfer of N from clover to the soil after defoliation. Emissions were strongly modulated by precipitation on time scales ranging from 1 day to 1 week. This indicates that effective control of N2O emissions through management on a day-to-day basis requires reliable medium-range weather forecasts. Model calculations were not able to reproduce essential characteristics of the emissions. The model slightly overestimated the background emissions, but severely underestimated the emission peaks following fertilizer application, and largely failed to reproduce emission induced by mowing. Shortfalls in the model used for this study were found in relation to the description of soil-water fluxes, soil organic matter, and the physiology of clover.

  12. N Management of European Grasslands: Can the Exchange of Gaseous N Species Be Influenced at the Operational Level?

    Directory of Open Access Journals (Sweden)

    P. Calanca

    2001-01-01

    Full Text Available Grassland ecosystems can be regarded as biochemical reactors in which large amounts of organic nitrogen (N are converted into inorganic N, and vice versa. If managed in a sustainable manner, grasslands should operate in a quasi steady state, characterized by an almost perfect balance between total N input and output. As a consequence, the exchange of gaseous N species (NH3, NO, NO2, N2O, and N2 between grasslands and the atmosphere is very small compared to the total N turnover. In this study, the effects of two management options (mowing and fertilization on production and emission of nitrous oxide (N2O from a grass/clover crop were examined on the basis of observations and model results referring to an experiment carried out on the Swiss Plateau in late summer of 2000. It was found that production and emission of N2O induced by mowing were of the same order of magnitude as those brought about by fertilization, suggesting a possible transfer of N from clover to the soil after defoliation. Emissions were strongly modulated by precipitation on time scales ranging from 1 day to 1 week. This indicates that effective control of N2O emissions through management on a day-to-day basis requires reliable medium-range weather forecasts. Model calculations were not able to reproduce essential characteristics of the emissions. The model slightly overestimated the background emissions, but severely underestimated the emission peaks following fertilizer application, and largely failed to reproduce emission induced by mowing. Shortfalls in the model used for this study were found in relation to the description of soil-water fluxes, soil organic matter, and the physiology of clover.

  13. The Story of California = La Historia de California.

    Science.gov (United States)

    Bartel, Nick

    "The Story of California" is a history and geography of the state of California, intended for classroom use by limited-English-proficient, native Spanish-speaking students in California's urban middle schools. The book is designed with the left page in English and the right page in Spanish to facilitate student transition into…

  14. LLWPA: Implementation in California

    International Nuclear Information System (INIS)

    Gaynor, R.K.; Romano, S.A.

    1987-01-01

    US Ecology has been designated by the State of California to locate, develop and operate a low-level radioactive waste disposal facility. In early 1986, the firm identified eighteen desert basins in southeastern California for siting considerations. Three candidate sites were selected for detailed field characterization work in February, 1987. A preferred site for licensing purposes will be identified in late 1987. California is currently ahead of the siting milestone schedule mandated by the Low-Level Radioactive Waste Policy Amendments Act. It is likely that a license application will be filed in mid-1988, well before the 1990 milestone date. It is anticipated that the site will be constructed around that milestone date. This paper describes the process undertaken by US Ecology to identify three candidate sites for characterization, and the public involvement program supporting this decision. Future activities leading to a final site development are also described

  15. Transit performance measures in California.

    Science.gov (United States)

    2016-04-01

    This research is the result of a California Department of Transportation (Caltrans) request to assess the most commonly : available transit performance measures in California. Caltrans wanted to understand performance measures and data used by : Metr...

  16. Investing carbon offsets in woody forests - the best solution for California?

    Science.gov (United States)

    Dass, P.; Houlton, B. Z.; Warlind, D.

    2016-12-01

    Increasing atmospheric carbon dioxide (CO2) concentrations from fossil fuel combustion, land conversion and biomass burning are principal to climate change and its manifolds risks on human health, the environment and the global economy. Effective mitigation of climate change thereby involves cutting fossil-fuel emissions at the source or capturing CO2 in engineered or natural ecosystem stocks, or both. The lifetime of CO2 in the atmosphere exceeds 100 years; thus, in the case of CO2 sequestration by natural ecosystems, the residence time of soil and vegetation carbon(C) is a critical component of the efficacy of C offsets in the marketplace, particularly in local to global Cap and Trade frameworks. Here we use a land-surface model to analyze trade-offs in C investment into natural forest vs. grassland sinks and the role of fire in driving the most sustained pathways of CO2 sequestration under Cap and Trade policies. We focus on the California Climate Exchange and AB32 as the model system for examining risks of CO2 offset investments by considering model-based scenarios of (a.) natural woody forests (mixture of trees, shrubs and grasslands) or (b.) pure grasslands (no woody vegetation allowed) under conditions of drought and changes in fire frequency. While forests capture more carbon than grasslands, the latter stores a greater fraction of C in below ground stocks, making it less vulnerable to climate-driven disturbances. Preliminary results for simulations carried out for the last century for the state of California corroborate this hypothesis: while trees capture 100 GgCyr-1 more than grasses, CO2 emissions due to fire is less by 20 GgCyr-1 from grasslands when compared to forest environments. Since policies need to regard potential future scenarios, we present results that investigate how the alternate systems of trees and grasses respond to (i.) the environmental conditions of the no-mitigation scenario (RCP 8.5) through the year 2100, (ii.) periods of extended

  17. Solar: California, not dreaming

    Energy Technology Data Exchange (ETDEWEB)

    Jones, J.

    2006-03-15

    The California Solar Initiative (CSI) was approved by the California Public Utilities Commission (PUC) in January 2006. The CSI is the largest solar programme of this kind ever in the USA and provides for $3.2 billion in incentives for solar projects between 2007 and 2017. The PUC will oversee a $2.5 billion programme to provide funding for solar installations on commercial and existing residential buildings, while the California Energy Commission (CEC) will manage a separate $350 million fund targeted at new residential building. Existing solar programmes operated by the PUC and CEC will be consolidated into the CSI. The CEC programme will use already allocated funding, but the PUC programme will be funded through revenues collected from customers of the main gas and electric utilities in California. Funds will be distributed via rebates to householders or companies that install solar. As well as solar photovoltaics (PV), rebates will also go to solar thermal power (concentrating solar power) and solar heating and cooling. CSI funding can be used in combination with existing federal tax credits. The aim is a gradual increase from installation of 40 MW of PV in 2005 to 100 MW by 2009. The CSI is also expected to create favourable market conditions for PV manufacturers in California and to encourage investment in production of solar-grade silicon in or near California. Objections from the International Brotherhood of Electrical Workers (IBEW) appear to have been overcome but a number of other potential snags remain. CSI is expected to be replicated in other US states.

  18. Priming of soil carbon decomposition in two Inner Mongolia grassland soils following sheep dung addition: a study using ¹³C natural abundance approach.

    Science.gov (United States)

    Ma, Xiuzhi; Ambus, Per; Wang, Shiping; Wang, Yanfen; Wang, Chengjie

    2013-01-01

    To investigate the effect of sheep dung on soil carbon (C) sequestration, a 152 days incubation experiment was conducted with soils from two different Inner Mongolian grasslands, i.e. a Leymus chinensis dominated grassland representing the climax community (2.1% organic matter content) and a heavily degraded Artemisia frigida dominated community (1.3% organic matter content). Dung was collected from sheep either fed on L. chinensis (C3 plant with δ¹³C = -26.8‰; dung δ¹³C = -26.2‰) or Cleistogenes squarrosa (C₄ plant with δ¹³C = -14.6‰; dung δ¹³C = -15.7‰). Fresh C₃ and C₄ sheep dung was mixed with the two grassland soils and incubated under controlled conditions for analysis of ¹³C-CO₂ emissions. Soil samples were taken at days 17, 43, 86, 127 and 152 after sheep dung addition to detect the δ¹³C signal in soil and dung components. Analysis revealed that 16.9% and 16.6% of the sheep dung C had decomposed, of which 3.5% and 2.8% was sequestrated in the soils of L. chinensis and A. frigida grasslands, respectively, while the remaining decomposed sheep dung was emitted as CO₂. The cumulative amounts of C respired from dung treated soils during 152 days were 7-8 times higher than in the un-amended controls. In both grassland soils, ca. 60% of the evolved CO₂ originated from the decomposing sheep dung and 40% from the native soil C. Priming effects of soil C decomposition were observed in both soils, i.e. 1.4 g and 1.6 g additional soil C kg⁻¹ dry soil had been emitted as CO₂ for the L. chinensis and A. frigida soils, respectively. Hence, the net C losses from L. chinensis and A. frigida soils were 0.6 g and 0.9 g C kg⁻¹ soil, which was 2.6% and 7.0% of the total C in L. chinensis and A. frigida grasslands soils, respectively. Our results suggest that grazing of degraded Inner Mongolian pastures may cause a net soil C loss due to the positive priming effect, thereby accelerating soil deterioration.

  19. Understanding of Grassland Ecosystems under Climate Change and Economic Development Pressures in the Mongolia Plateau

    Science.gov (United States)

    Qi, J.; Chen, J.; Shan, P.; Pan, X.; Wei, Y.; Wang, M.; Xin, X.

    2011-12-01

    The land use and land cover change, especially in the form of grassland degradation, in the Mongolian Plateau, exhibited a unique spatio-temporal pattern that is a characteristic of a mixed stress from economic development and climate change of the region. The social dimension of the region played a key role in shaping the landscape and land use change, including the cultural clashes with economic development, conflicts between indigenous people and business ventures, and exogenous international influences. Various research projects have been conducted in the region to focus on physical degradation of grasslands and/or on economic development but there is a lack of understanding how the social and economic dimensions interact with grassland ecosystems and changes. In this talk, a synthesis report was made based on the most recent workshop held in Hohhot, Inner Mongolia, of China, that specifically focused on climate change and grassland ecosystems. The report analyzed the degree of grassland degradation, its climate and social drivers, and coupling nature of economic development and conservation of traditional grassland values. The goal is to fully understand the socio-ecological-economic interactions that together shape the trajectory of the grassland ecosystems in the Mongolia Plateau.

  20. Impact of Climate Change on Temperate and Alpine Grasslands in China during 1982–2006

    Directory of Open Access Journals (Sweden)

    Xiangjin Shen

    2015-01-01

    Full Text Available Based on GIMMS NDVI and climate data from 1982 to 2006, this study analyzed the impact of climate change on grassland in China. During the growing season, there were significant effects of precipitation on the growth of all the grassland types (P<0.05, except for meadow vegetation. For the air temperatures, there existed asymmetrical effects of maximum temperature (Tmax and minimum temperature (Tmin on grassland vegetation, especially for the temperate grasslands and alpine steppe. The growing season NDVI correlated negatively with Tmax but positively with Tmin for temperate grasslands. Seasonally, these opposite effects were only observed in summer. For alpine steppe, the growing season NDVI correlated positively with Tmax but negatively with Tmin, and this pattern of asymmetrical responses was only obvious in spring and autumn. Under the background of global asymmetric warming, more attention should be paid to this asymmetric response of grassland vegetation to daytime and night-time warming, especially when we want to predict the productivity of China’s grasslands in the future.

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

    Science.gov (United States)

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

    2012-01-01

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

  2. Prairie dog decline reduces the supply of ecosystem services and leads to desertification of semiarid grasslands.

    Directory of Open Access Journals (Sweden)

    Lourdes Martínez-Estévez

    Full Text Available Anthropogenic impacts on North American grasslands, a highly endangered ecosystem, have led to declines of prairie dogs, a keystone species, over 98% of their historical range. While impacts of this loss on maintenance of grassland biodiversity have been widely documented, much less is known about the consequences on the supply of ecosystem services. Here we assessed the effect of prairie dogs in the supply of five ecosystem services by comparing grasslands currently occupied by prairie dogs, grasslands devoid of prairie dogs, and areas that used to be occupied by prairie dogs that are currently dominated by mesquite scrub. Groundwater recharge, regulation of soil erosion, regulation of soil productive potential, soil carbon storage and forage availability were consistently quantitatively or qualitatively higher in prairie dog grasslands relative to grasslands or mesquite scrub. Our findings indicate a severe loss of ecosystem services associated to the absence of prairie dogs. These findings suggest that contrary to a much publicize perception, especially in the US, prairie dogs are fundamental in maintaining grasslands and their decline have strong negative impacts in human well - being through the loss of ecosystem services.

  3. [Community structure and diversity of soil arthropods in naturally restored sandy grasslands after grazing].

    Science.gov (United States)

    Liu, Ren-tao; Zhao, Ha-lin; Zhao, Xue-yong

    2010-11-01

    Taking the Naiman Desertification Research Station under Chinese Academy of Sciences as a base, an investigation was conducted on the community structure of soil arthropods in the naturally restored sandy grasslands after different intensity grazing disturbance, with the effects of vegetation and soil on this community structure approached. In the non-grazing grassland, soil arthropods were rich in species and more in individuals, and had the highest diversity. In the restored grassland after light grazing, soil arthropods had the lowest evenness and diversity. In the restored grassland after moderate grazing, the individuals of soil arthropods were lesser but the major groups were more, and the evenness and diversity were higher. In the restored grassland after heavy grazing, the individuals of soil arthropods were more but the major groups were lesser, and the diversity was higher. Plant individuals' number, vegetation height and coverage, and soil alkalinity were the main factors affecting the soil arthropod community in naturally restored grasslands after different intensity grazing disturbance. It was implied that after 12-year exclosure of grassland, soil arthropod community could be recovered to some degree, while grazing disturbance had long-term negative effects on the arthropod community.

  4. Grasslands and Croplands Have Different Microbial Biomass Carbon Levels per Unit of Soil Organic Carbon

    Directory of Open Access Journals (Sweden)

    Terence P. McGonigle

    2017-07-01

    Full Text Available Primarily using cropped systems, previous studies have reported a positive linear relationship between microbial biomass carbon (MBC and soil organic carbon (SOC. We conducted a meta-analysis to explore this relationship separately for grasslands and croplands using available literature. Studies were limited to those using fumigation–extraction for MBC for field samples. Trials were noted separately where records were distinct in space or time. Grasslands were naturally occurring, restored, or seeded. Cropping systems were typical of the temperate zone. MBC had a positive linear response to increasing SOC that was significant in both grasslands (p < 0.001; r2 = 0.76 and croplands (p < 0.001; r2 = 0.48. However, MBC increased 2.5-fold more steeply per unit of increasing SOC for grassland soils, as compared to the corresponding response in cropland soils. Expressing MBC as a proportion of SOC across the regression overall, slopes corresponded to 2.7% for grasslands and 1.1% for croplands. The slope of the linear relationship for grasslands was significantly (p = 0.0013 steeper than for croplands. The difference between the two systems is possibly caused by a greater proportion of SOC in grasslands being active rather than passive, relative to that in croplands, with that active fraction promoting the formation of MBC.

  5. Wildfires alter rodent community structure across four vegetation types in southern California, USA

    Science.gov (United States)

    Brehme, Cheryl S.; Clark, Denise R.; Rochester, Carlton J.; Fisher, Robert N.

    2011-01-01

    We surveyed burned and unburned plots across four habitat reserves in San Diego County, California, USA, in 2005 and 2006, to assess the effects of the 2003 wildfires on the community structure and relative abundance of rodent species. The reserves each contained multiple vegetation types (coastal sage scrub, chaparral, woodland, and grassland) and spanned from 250 m to 1078 m in elevation. Multivariate analyses revealed a more simplified rodent community structure in all burned habitats in comparison to unburned habitats. Reduction in shrub and tree cover was highly predictive of changes in post-fire rodent community structure in the burned coastal sage scrub and chaparral habitats. Reduction in cover was not predictive for the less substantially burned woodlands and grasslands, for which we hypothesized that interspecific competition played a greater role in post-fire community structure. Across vegetation types, generalists and open habitat specialists typically increased in relative abundance, whereas closed habitat specialists decreased. We documented significant increases in relative abundance of the deer mouse (Peromyscus maniculatus Wagner) and Dulzura kangaroo rat (Dipodomys simulans Merriam). In contrast, we found significant decreases in relative abundance for the California mouse (Peromyscus californicus Gambel), San Diego pocket mouse (Chaetodipus fallax Merriam), desert woodrat (Neotoma lepida Thomas), and brush mouse (Peromyscus boylii Baird). Currently, our research program involves assessment of whether habitat conservation plans (HCPs) in southern California provide long-term protection to HCP covered species, as well as preserve ecosystem function. The scenario of increased wildfires needs to be incorporated into this assessment. We discuss our results in relation to management and conservation planning under a future scenario of larger and more frequent wildfires in southern California.

  6. HCMM: Soil moisture in relation to geologic structure and lithology, northern California. [Sacramento Valley, California

    Science.gov (United States)

    Rich, E. I. (Principal Investigator)

    1980-01-01

    The author has identified the following significant results. Empirical observations on the ground and examination of aerial color IR photographs indicate that in grassland terrain, the vegetation overlying sandstone tends to become less vigorous sooner in the late spring season than does the area overlain by an adjacent shale unit. The reverse relationship obtains in the fall. These relationships are thought to be a reflection of the relative porosity of each of the units and hence of their ability to retain or lose soil moisture. A comparison of the optically enlarged day and nite IR imagery of the Late Mesozoic interbedded sandstone and shale units along the western margin of the Sacramento Valley, California, taken at seasonally critical times of the year (late spring/early summer and late fall/early winter) reveals subtle seasonal variations of graytone which tend to support the empirical observations after consideration of Sun angle and azimuth, and the internal consistency of the data on each set of satellite imagery.

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

    Science.gov (United States)

    Zhou, Qiang

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

  8. Lesser prairie-chicken avoidance of trees in a grassland landscape

    Science.gov (United States)

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

    2016-01-01

    Grasslands are among the most imperiled ecosystems in North America. Reasons that grasslands are threatened include conversion to row-crop agriculture, fragmentation, and changes in fire regimes. The reduction of fire processes in remaining prairies has resulted in tree encroachment and establishment in grasslands, further reducing grassland quantity and quality. Grassland birds have been experiencing precipitous population declines in recent decades, commensurate with landscape changes to grasslands. The lesser prairie-chicken (Tympanuchus pallidicinctus Ridgway) is a declining species of prairie grouse of conservation concern. We used second- and third-order habitat selection metrics to test if female lesser prairie-chickens avoid grasslands where trees were present. Our results indicated that female lesser prairie-chickens selected habitats avoiding the nearest trees by 283 m on average, nearly twice as far as would be expected at random. Lesser prairie-chickens were 40 times more likely to use habitats with tree densities of 0 trees ∙ ha− 1 than habitats with 5 trees ∙ ha− 1. Probability of use indicated that lesser prairie-chickens were 19 times more likely to use habitats 1000 m from the nearest tree when compared with using habitats 0 m from the nearest tree. Nest survival was not affected at densities 2 trees ∙ ha− 1. Avoidance of trees could be due to perceived increased predation risk, reduced habitat quality, or a combination of these potentially confounding factors. Preventing further establishment and expansion of trees in landscapes occupied by lesser prairie-chickens could contribute to the continued persistence of the species. Additionally, restoring grasslands through tree removal may facilitate conservation efforts for grassland species such as the lesser prairie-chicken by improving habitat quality and promoting expansion of occupied range.

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

    Science.gov (United States)

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

    2015-01-01

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

  10. Traditional cattle grazing in a mosaic alkali landscape: effects on grassland biodiversity along a moisture gradient.

    Directory of Open Access Journals (Sweden)

    Péter Török

    Full Text Available Extensively managed pastures are of crucial importance in sustaining biodiversity both in local- and landscape-level. Thus, re-introduction of traditional grazing management is a crucial issue in grassland conservation actions worldwide. Traditional grazing with robust cattle breeds in low stocking rates is considered to be especially useful to mimic natural grazing regimes, but well documented case-studies are surprisingly rare on this topic. Our goal was to evaluate the effectiveness of traditional Hungarian Grey cattle grazing as a conservation action in a mosaic alkali landscape. We asked the following questions: (i How does cattle grazing affect species composition and diversity of the grasslands? (ii What are the effects of grazing on short-lived and perennial noxious species? (iii Are there distinct effects of grazing in dry-, mesophilous- and wet grassland types? Vegetation of fenced and grazed plots in a 200-ha sized habitat complex (secondary dry grasslands and pristine mesophilous- and wet alkali grasslands was sampled from 2006-2009 in East-Hungary. We found higher diversity scores in grazed plots compared to fenced ones in mesophilous- and wet grasslands. Higher cover of noxious species was typical in fenced plots compared to their grazed counterparts in the last year in every studied grassland type. We found an increasing effect of grazing from the dry- towards the wet grassland types. The year-to-year differences also followed similar pattern: the site-dependent effects were the lowest in the dry grassland and an increasing effect was detected along the moisture gradient. We found that extensive Hungarian Grey cattle grazing is an effective tool to suppress noxious species and to create a mosaic vegetation structure, which enables to maintain high species richness in the landscape. Hungarian Grey cattle can feed in open habitats along long moisture gradient, thus in highly mosaic landscapes this breed can be the most suitable

  11. Recent trends, drivers, and projections of carbon cycle processes in forests and grasslands of North America

    Science.gov (United States)

    Domke, G. M.; Williams, C. A.; Birdsey, R.; Pendall, E.

    2017-12-01

    In North America forest and grassland ecosystems play a major role in the carbon cycle. Here we present the latest trends and projections of United States and North American carbon cycle processes, stocks, and flows in the context of interactions with global scale budgets and climate change impacts in managed and unmanaged grassland and forest ecosystems. We describe recent trends in natural and anthropogenic disturbances in these ecosystems as well as the carbon dynamics associated with land use and land cover change. We also highlight carbon management science and tools for informing decisions and opportunities for improving carbon measurements, observations, and projections in forests and grasslands.

  12. Higher Education in California

    Science.gov (United States)

    Public Policy Institute of California, 2016

    2016-01-01

    Higher education enhances Californians' lives and contributes to the state's economic growth. But population and education trends suggest that California is facing a large shortfall of college graduates. Addressing this short­fall will require strong gains for groups that have been historically under­represented in higher education. Substantial…

  13. California Budget Simulation

    Science.gov (United States)

    Mallinson, Daniel J.

    2018-01-01

    The California Budget Challenge produced by Next10 provides a useful and intuitive tool for instructors to introduce students to public budgeting. Students will reason through a series of budgeting decisions using information provided on the fiscal and practical implications of their choices. The Challenge is updated with each budget cycle, so it…

  14. Oak management in California

    Science.gov (United States)

    Plumb. Timothy R.; Philip M. McDonald

    1981-01-01

    Native oak species grow on 15 to 20 million acres (6 to 8 million ha) of California land, and have an estimated net volume of about 3 billion ft3 (85 million m3). This resource, valuable not only for traditional wood products, but also for wildlife habitat, watershed protection, and recreational-esthetic values, is not...

  15. California's Perfect Storm

    Science.gov (United States)

    Bacon, David

    2010-01-01

    The United States today faces an economic crisis worse than any since the Great Depression of the 1930s. Nowhere is it sharper than in the nation's schools. Last year, California saw a perfect storm of protest in virtually every part of its education system. K-12 teachers built coalitions with parents and students to fight for their jobs and their…

  16. FELLOWS ADDRESS California Dreaming

    NARCIS (Netherlands)

    Kooten, van Kees

    2017-01-01

    California was the first jurisdiction to mandate a reduction in greenhouse gas (GHG) emissions by 80% below 1990 levels by 2050. This target was subsequently endorsed by the G8 in 2009 and the European Commission in 2014, and is the guiding principle of the 2015 Paris Agreement. To achieve these

  17. NREL + Southern California Gas

    Energy Technology Data Exchange (ETDEWEB)

    Berdahl, Sonja E [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-10-09

    NREL and Southern California Gas Company are evaluating a new 'power-to-gas' approach - one that produces methane through a biological pathway and uses the expansive natural gas infrastructure to store it. This approach has the potential to change how the power industry approaches renewable generation and energy storage.

  18. California's Future: Higher Education

    Science.gov (United States)

    Johnson, Hans

    2015-01-01

    California's higher education system is not keeping up with the changing economy. Projections suggest that the state's economy will continue to need more highly educated workers. In 2025, if current trends persist, 41 percent of jobs will require at least a bachelor's degree and 36 percent will require some college education short of a bachelor's…

  19. Nutrient fluxes from coastal California catchments with suburban development

    Science.gov (United States)

    Melack, J. M.; Leydecker, A.; Beighley, E.; Robinson, T.; Coombs, S.

    2005-12-01

    Numerous streams originate in the mountains fringing California's coast and transport nutrients into coastal waters. In central California, these streams traverse catchments with land covers including chaparral, grazed grasslands, orchards, industrial agriculture and suburban and urban development. Fluvial nutrient concentrations and fluxes vary as a function of these land covers and as a function of considerable fluctuations in rainfall. As part of a long-term investigation of mobilization and fluvial transport of nutrients in catchments bordering the Santa Barbara Channel we have intensively sampled nutrient concentrations and measured discharge during storm and base flows in multiple catchments and subcatchments. Volume-weighted mean concentrations of nitrate generally ranged from 5 to 25 micromolar in undeveloped areas, increased to about 100 micromolar for suburban and most agricultural catchments, and were in excess of 1000 micromolar in catchments with greenhouse-based agriculture. Phosphate concentrations ranged from 2 to 20 micromolar among the catchments. These data are used to examine the premise that the suburbanized portion of the catchments is the primary source of nutrients to the streams.

  20. Effects of management practices on grassland birds: Grasshopper Sparrow

    Science.gov (United States)

    Dechant, Jill A.; Sondreal, Marriah L.; Johnson, Douglas H.; Igl, Lawrence D.; Goldade, Christopher M.; Nenneman, Melvin P.; Euliss, Betty R.

    1998-01-01

    Information on the habitat requirements and effects of habitat management on grassland birds were summarized from information in more than 5,500 published and unpublished papers. A range map is provided to indicate the relative densities of the species in North America, based on Breeding Bird Survey (BBS) data. Although birds frequently are observed outside the breeding range indicated, the maps are intended to show areas where managers might concentrate their attention. It may be ineffectual to manage habitat at a site for a species that rarely occurs in an area. The species account begins with a brief capsule statement, which provides the fundamental components or keys to management for the species. A section on breeding range outlines the current breeding distribution of the species in North America, including areas that could not be mapped using BBS data. The suitable habitat section describes the breeding habitat and occasionally microhabitat characteristics of the species, especially those habitats that occur in the Great Plains. Details on habitat and microhabitat requirements often provide clues to how a species will respond to a particular management practice. A table near the end of the account complements the section on suitable habitat, and lists the specific habitat characteristics for the species by individual studies. A special section on prey habitat is included for those predatory species that have more specific prey requirements. The area requirements section provides details on territory and home range sizes, minimum area requirements, and the effects of patch size, edges, and other landscape and habitat features on abundance and productivity. It may be futile to manage a small block of suitable habitat for a species that has minimum area requirements that are larger than the area being managed. The Brown-headed Cowbird (Molothrus ater) is an obligate brood parasite of many grassland birds. The section on cowbird brood parasitism summarizes rates

  1. Nocturnal activity of nesting shrubland and grassland passerines: Chapter 9

    Science.gov (United States)

    Slay, Christy M.; Ellison, Kevin S.; Ribic, Christine; Smith, Kimberly G.; Schmitz, Carolyn M.

    2013-01-01

    Nocturnal activity of nesting passerines is largely undocumented in field situations. We used video recordings to quantify sleep patterns of four shrubland and three grassland bird species during the nestling period. All species exhibited “back sleep” (bill tucked under scapular feathers); individuals woke frequently for vigils of their surroundings. Sleep-bout duration varied from 6 minutes (grasshopper sparrow) to 28 minutes (blue-winged warbler, field sparrow). Duration on nest varied from 6.4 hours (field sparrow) to 8.8 hours (indigo bunting). Adults woke 20–30 minutes before sunrise. First morning absence from the nest was short; nestlings were fed within 12 minutes of a parent’s departure. Further research is needed to understand energetic costs of sleep and behavioral adaptations to environmental pressures.

  2. The Changing California Coast: The Effect of a Variable Water Budget on Coastal Vegetation Succession

    Science.gov (United States)

    Hsu, Wei-Chen; Remar, Alex; McClure, Adam; Williams, Emily; Kannan, Soumya; Steers, Robert; Schmidt, Cindy; Skiles, Joseph W.; Hsu, Wei-Chen

    2011-01-01

    The land-ocean interface along the central coast of California is one of the most diverse biogeographic regions of the state. This area is composed of a species-rich mosaic of coastal grassland, shrubland, and forest vegetation types. An acceleration of conifer encroachment into shrublands and shrub encroachment into grasslands along the coast has been recently documented. These vegetation changes are believed to be driven primarily by fire suppression and changing grazing patterns. Climatic variables such as precipitation, fog, cloud cover, temperature, slope, and elevation also play an important role in vegetation succession. Our study area is located along the central California coast, which is characterized by a precipitation gradient from the relatively wetter and cooler north to the drier and warmer south. Some studies indicate changing fog patterns along this coast, which may greatly impact vegetation. A decrease in water availability could slow succession processes. The primary objective of this project is to determine if vegetation succession rates are changing for the study area and to identify climate and ecosystem variables which contribute to succession, specifically the transition among grassland, shrubland, and forest. To identify vegetation types and rates of succession, we classified two Landsat TM 5 scenes from 1985 to 2010 with a resulting overall accuracy of 82.4%. Vegetation succession was correlated to changes in maximum and minimum temperatures, precipitation, and elevation for each sub-region of the study area. Fog frequency was then compared between the northern and southern regions of the study area for determining the spatial relation between fog frequency and the percent of vegetation change.

  3. Rapid top-down regulation of plant C:N:P stoichiometry by grasshoppers in an Inner Mongolia grassland ecosystem.

    Science.gov (United States)

    Zhang, Guangming; Han, Xingguo; Elser, James J

    2011-05-01

    Understanding how food web interactions alter the processing of limiting nutrient elements is an important goal of ecosystem ecology. An experiment manipulating densities of the grasshopper Oedaleus asiaticus was performed to assess top-down effects of grasshoppers on C:N:P stoichiometry of plants and soil in a grassland ecosystem in Inner Mongolia (China). With increased grasshopper feeding, plant biomass declined fourfold, litter abundance increased 30%, and the plant community became dominated by non-host plant taxa. Plant stoichiometric response depended on whether or not the plant was a grasshopper host food species: C:N and C:P ratios increased with increasing grasshopper density (GD) for host plants but decreased in non-host plants. These data suggest either a direct transfer of grasshopper-recycled nutrients from host to non-host plants or a release of non-host plants from nutrient competition with heavily grazed host plants. Litterfall C:N and C:P decreased across moderate levels of grasshopper density but no effects on C:N:P stoichiometry in the surface soil were observed, possibly due to the short experimental period. Our observations of divergent C:N:P stoichiometric response among plant species highlight the important role of grasshopper herbivory in regulating plant community structure and nutrient cycling in grassland ecosystems.

  4. Experimental control of Spanish broom (Spartium junceum invading natural grasslands

    Directory of Open Access Journals (Sweden)

    Cristina Sanhueza

    2012-12-01

    Full Text Available A group of legumes generically known as brooms are among the most successful shrubs invading grasslands in South America and otherregions. These species share a set of biological features that enhance their invasiveness, such as abundant and long-lasting seed banks,aggressive root systems and rapid growth, combined with their ability for re-sprouting after cutting or burning and for avoiding herbivores.They grow in dense stands that exclude native vegetation and are able to change ecological processes, increasing fire frequency and intensity,and fixing atmospheric nitrogen. The Spanish broom (Spartium junceum is a shrub native form the Mediterranean that was introduced intothe Argentine Pampas grasslands where it spreads over remnants of pristine ecosystems, threatening their biodiversity. This paper reports theresults obtained after an adaptive management strategy aimed at controlling this species in a nature reserve, and compares the efficiency ofdifferent mechanical and chemical control techniques in terms of the number of plants killed and the effects on surrounding vegetation andon the recruitment of broom seedlings. Control was implemented in two phases, the first included three treatments: i cut at the base of theplant, ii cut followed by the immediate application of Togar (Picloram 3% + Triclopyr 6%, at a 5% dilution in diesel oil on top of the cut stump, and iii foliar spraying with Togar. The follow-up treatments, implemented one year later, consisted of spraying the re-sprouts with Togar (5% in diesel oil or Glyphosate 36% (2% in water. The best option in terms of controlling Spanish broom was spraying the resprouts with Togar which gave 100% mortality of the treated plants, compared with values of 40% - 100% re-sprouting for the other optionstested. None of the methods was associated with an increase in seedling recruitment, nor with significant changes in the vegetation in the immediate vicinity of the controlled brooms.

  5. Surface temperature retrieval in a temperate grassland with multiresolution sensors

    Science.gov (United States)

    Goetz, S. J.; Halthore, R. N.; Hall, F. G.; Markham, B. L.

    1995-12-01

    Radiometric surface temperatures retrieved at various spatial resolutions from aircraft and satellite measurements at the FIFE site in eastern Kansas were compared with near-surface temperature measurements to determine the accuracy of the retrieval techniques and consistency between the various sensors. Atmospheric characterizations based on local radiosonde profiles of temperature, pressure, and water vapor were used with the LOWTRAN-7 and MODTRAN atmospheric radiance models to correct measured thermal radiances of water and grassland targets for atmospheric attenuation. Comparison of retrieved surface temperatures from a helicopter-mounted modular multispectral radiometer (MMR) (˜5-m "pixel"), C-130 mounted thematic mapper simulator (TMS) (NS001, ˜20-m pixel), and the Landsat 5 thematic mapper (TM) (120-m pixel) was done. Differences between atmospherically corrected radiative temperatures and near-surface measurements ranged from less than 1°C to more than 8°C. Corrected temperatures from helicopter-MMR and NS001-TMS were in general agreement with near-surface infrared radiative thermometer (IRT) measurements collected from automated meteorological stations, with mean differences of 3.2°C and 1.7°C for grassland targets. Much better agreement (within 1°C) was found between the retrieved aircraft surface temperatures and near-surface measurements acquired with a hand-held mast equipped with a MMR and IRT. The NS001-TMS was also in good agreement with near-surface temperatures acquired over water targets. In contrast, the Landsat 5 TM systematically overestimated surface temperature in all cases. This result has been noted previously but not consistently. On the basis of the results reported here, surface measurements were used to provide a calibration of the TM thermal channel. Further evaluation of the in-flight radiometric calibration of the TM thermal channel is recommended.

  6. Modelling nitrous oxide emissions from grazed grassland systems

    International Nuclear Information System (INIS)

    Wang Junye; Cardenas, Laura M.; Misselbrook, Tom H.; Cuttle, Steve; Thorman, Rachel E.; Li Changsheng

    2012-01-01

    Grazed grassland systems are an important component of the global carbon cycle and also influence global climate change through their emissions of nitrous oxide and methane. However, there are huge uncertainties and challenges in the development and parameterisation of process-based models for grazed grassland systems because of the wide diversity of vegetation and impacts of grazing animals. A process-based biogeochemistry model, DeNitrification-DeComposition (DNDC), has been modified to describe N 2 O emissions for the UK from regional conditions. This paper reports a new development of UK-DNDC in which the animal grazing practices were modified to track their contributions to the soil nitrogen (N) biogeochemistry. The new version of UK-DNDC was tested against datasets of N 2 O fluxes measured at three contrasting field sites. The results showed that the responses of the model to changes in grazing parameters were generally in agreement with observations, showing that N 2 O emissions increased as the grazing intensity increased. - Highlights: ► Parameterisation of grazing system using grazing intensity. ► Modification of UK D NDC for the UK soil and weather conditions. ► Validation of the UK D NDC against measured data of N 2 O emissions in three UK sites. ► Estimating influence of animal grazing practises on N 2 O emissions. - Grazing system was parameterised using grazing intensity and UK-DNDC model was modified and validated against measured data of N 2 O emissions in three UK sites.

  7. Grassland communities of traditional orchards in the Western Carpathians (Slovakia

    Directory of Open Access Journals (Sweden)

    Hubert Zarnovican

    2017-06-01

    Full Text Available Traditional orchards are a valuable feature of the rural landscape and they are specific for regions with scattered settlement such as the Myjava hilly land and White Carpathians. Here, the permanent species-rich grasslands beneath trees were regularly managed in the traditional manner until some were replaced in the 1970’s and 80’s by intensively managed orchards, some of which were abandoned in the early 1990’s. Our 2011–2015 phytosociological research followed the standard Braun-Blanquet approach. We classified 178 phytosociological relevés recorded in orchard meadows (156 relevés, former intensively managed orchards (16 relevés, and two relevés from a semi-intensively grazed orchard. Traditionally managed orchard meadows were classified in the following five units: (i Pastinaco sativae-Arrhenatheretum elatioris – thermophilous variant, (ii Pastinaco sativae-Arrhenatheretum elatioris – transitional variant to Alchemillo-Arrhenatheretum elatioris, (iii Ranunculo bulbosi-Arrhenatheretum elatioris, (iv Onobrychido viciifoliae-Brometum erecti, and (v Brachypodio pinnati-Molinietum arundinaceae. Formerly intensively managed large-scale orchards were classified as Pastinaco sativae-Arrhenatheretum elatioris association and the semi-intensively grazed orchard as Lolio perennis-Cynosuretum cristati association. The species composition varies considerably due to tree-shading and different management treatments applied in the orchards, so the relevés of the delimited syntaxonomic units are not typical and have transitional character. Moisture, soil nutrients, and soil reaction were identified as the main environmental gradients influencing species composition. We tested four management treatments in direct gradient analysis and found that abandonment has the strongest effect on species composition. Comparison of grassland vegetation in the studied traditional orchards with that described in Germany reveals differences in species

  8. Grassland invader responses to realistic changes in native species richness.

    Science.gov (United States)

    Rinella, Matthew J; Pokorny, Monica L; Rekaya, Romdhane

    2007-09-01

    The importance of species richness for repelling exotic plant invasions varies from ecosystem to ecosystem. Thus, in order to prioritize conservation objectives, it is critical to identify those ecosystems where decreasing richness will most greatly magnify invasion risks. Our goal was to determine if invasion risks greatly increase in response to common reductions in grassland species richness. We imposed treatments that mimic management-induced reductions in grassland species richness (i.e., removal of shallow- and/or deep-rooted forbs and/or grasses and/or cryptogam layers). Then we introduced and monitored the performance of a notorious invasive species (i.e., Centaurea maculosa). We found that, on a per-gram-of-biomass basis, each resident plant group similarly suppressed invader growth. Hence, with respect to preventing C. maculosa invasions, maintaining overall productivity is probably more important than maintaining the productivity of particular plant groups or species. But at the sites we studied, all plant groups may be needed to maintain overall productivity because removing forbs decreased overall productivity in two of three years. Alternatively, removing forbs increased productivity in another year, and this led us to posit that removing forbs may inflate the temporal productivity variance as opposed to greatly affecting time-averaged productivity. In either case, overall productivity responses to single plant group removals were inconsistent and fairly modest, and only when all plant groups were removed did C. maculosa growth increase substantially over a no-removal treatment. As such, it seems that intense disturbances (e.g., prolonged drought, overgrazing) that deplete multiple plant groups may often be a prerequisite for C. maculosa invasion.

  9. Interspecific neighbor interactions promote the positive diversity-productivity relationship in experimental grassland communities.

    Directory of Open Access Journals (Sweden)

    Yuhua Zhang

    Full Text Available Because the frequency of heterospecific interactions inevitably increases with species richness in a community, biodiversity effects must be expressed by such interactions. However, little is understood how heterospecific interactions affect ecosystem productivity because rarely are biodiversity ecosystem functioning experiments spatially explicitly manipulated. To test the effect of heterospecific interactions on productivity, direct evidence of heterospecific neighborhood interaction is needed. In this study we conducted experiments with a detailed spatial design to investigate whether and how heterospecific neighborhood interactions promote primary productivity in a grassland community. The results showed that increasing the heterospecific: conspecific contact ratio significantly increased productivity. We found there was a significant difference in the variation in plant height between monoculture and mixture communities, suggesting that height-asymmetric competition for light plays a central role in promoting productivity. Heterospecific interactions make tall plants grow taller and short plants become smaller in mixtures compared to monocultures, thereby increasing the efficiency of light interception and utilization. Overyielding in the mixture communities arises from the fact that the loss in the growth of short plants is compensated by the increased growth of tall plants. The positive correlation between species richness and primary production was strengthened by increasing the frequency of heterospecific interactions. We conclude that species richness significantly promotes primary ecosystem production through heterospecific neighborhood interactions.

  10. Interspecific neighbor interactions promote the positive diversity-productivity relationship in experimental grassland communities.

    Science.gov (United States)

    Zhang, Yuhua; Wang, Yongfan; Yu, Shixiao

    2014-01-01

    Because the frequency of heterospecific interactions inevitably increases with species richness in a community, biodiversity effects must be expressed by such interactions. However, little is understood how heterospecific interactions affect ecosystem productivity because rarely are biodiversity ecosystem functioning experiments spatially explicitly manipulated. To test the effect of heterospecific interactions on productivity, direct evidence of heterospecific neighborhood interaction is needed. In this study we conducted experiments with a detailed spatial design to investigate whether and how heterospecific neighborhood interactions promote primary productivity in a grassland community. The results showed that increasing the heterospecific: conspecific contact ratio significantly increased productivity. We found there was a significant difference in the variation in plant height between monoculture and mixture communities, suggesting that height-asymmetric competition for light plays a central role in promoting productivity. Heterospecific interactions make tall plants grow taller and short plants become smaller in mixtures compared to monocultures, thereby increasing the efficiency of light interception and utilization. Overyielding in the mixture communities arises from the fact that the loss in the growth of short plants is compensated by the increased growth of tall plants. The positive correlation between species richness and primary production was strengthened by increasing the frequency of heterospecific interactions. We conclude that species richness significantly promotes primary ecosystem production through heterospecific neighborhood interactions.

  11. Uncertainty analysis of a coupled ecosystem response model simulating greenhouse gas fluxes from a temperate grassland

    Science.gov (United States)

    Liebermann, Ralf; Kraft, Philipp; Houska, Tobias; Breuer, Lutz; Müller, Christoph; Kraus, David; Haas, Edwin; Klatt, Steffen

    2015-04-01

    Among anthropogenic greenhouse gas emissions, CO2 is the dominant driver of global climate change. Next to its direct impact on the radiation budget, it also affects the climate system by triggering feedback mechanisms in terrestrial ecosystems. Such mechanisms - like stimulated photosynthesis, increased root exudations and reduced stomatal transpiration - influence both the input and the turnover of carbon and nitrogen compounds in the soil. The stabilization and decomposition of these compounds determines how increasing CO2 concentrations change the terrestrial trace gas emissions, especially CO2, N2O and CH4. To assess the potential reaction of terrestrial greenhouse gas emissions to rising tropospheric CO2 concentration, we make use of a comprehensive ecosystem model integrating known processes and fluxes of the carbon-nitrogen cycle in soil, vegetation and water. We apply a state-of-the-art ecosystem model with measurements from a long term field experiment of CO2 enrichment. The model - a grassland realization of LandscapeDNDC - simulates soil chemistry coupled with plant physiology, microclimate and hydrology. The data - comprising biomass, greenhouse gas emissions, management practices and soil properties - has been attained from a FACE (Free Air Carbon dioxide Enrichment) experiment running since 1997 on a temperate grassland in Giessen, Germany. Management and soil data, together with weather records, are used to drive the model, while cut biomass as well as CO2 and N2O emissions are used for calibration and validation. Starting with control data from installations without CO2 enhancement, we begin with a GLUE (General Likelihood Uncertainty Estimation) assessment using Latin Hypercube to reduce the range of the model parameters. This is followed by a detailed sensitivity analysis, the application of DREAM-ZS for model calibration, and an estimation of the effect of input uncertainty on the simulation results. Since first results indicate problems with

  12. Stigma Among California's Medical Marijuana Patients

    OpenAIRE

    Satterlund, Travis D.; Lee, Juliet P.; Moore, Roland S.

    2015-01-01

    The enactment of California's Proposition 215 stipulates that patients may use marijuana for medical reasons, provided that it is recommended by a physician. Yet, medical marijuana patients risk being stigmatized for this practice. This paper examines the way in which medical marijuana patients perceive and process stigma, and how it affects their interactions and experiences with others. Eighteen semi-structured interviews of medical marijuana patients were carried out using a semi-structure...

  13. The role of above-ground competition and nitrogen vs. phosphorus enrichment in seedling survival of common European plant species of semi-natural grasslands.

    Directory of Open Access Journals (Sweden)

    Tobias Ceulemans

    Full Text Available Anthropogenic activities have severely altered fluxes of nitrogen and phosphorus in ecosystems worldwide. In grasslands, subsequent negative effects are commonly attributed to competitive exclusion of plant species following increased above-ground biomass production. However, some studies have shown that this does not fully account for nutrient enrichment effects, questioning whether lowering competition by reducing grassland productivity through mowing or herbivory can mitigate the environmental impact of nutrient pollution. Furthermore, few studies so far discriminate between nitrogen and phosphorus pollution. We performed a full factorial experiment in greenhouse mesocosms combining nitrogen and phosphorus addition with two clipping regimes designed to relax above-ground competition. Next, we studied the survival and growth of seedlings of eight common European grassland species and found that five out of eight species showed higher survival under the clipping regime with the lowest above-ground competition. Phosphorus addition negatively affected seven plant species and nitrogen addition negatively affected four plant species. Importantly, the negative effects of nutrient addition and higher above-ground competition were independent of each other for all but one species. Our results suggest that at any given level of soil nutrients, relaxation of above-ground competition allows for higher seedling survival in grasslands. At the same time, even at low levels of above-ground competition, nutrient enrichment negatively affects survival as compared to nutrient-poor conditions. Therefore, although maintaining low above-ground competition appears essential for species' recruitment, for instance through mowing or herbivory, these management efforts are likely to be insufficient and we conclude that environmental policies aimed to reduce both excess nitrogen and particularly phosphorus inputs are also necessary.

  14. Inter-specific competition, but not different soil microbial communities, affects N chemical forms uptake by competing graminoids of upland grasslands.

    Directory of Open Access Journals (Sweden)

    Eduardo Medina-Roldán

    Full Text Available Evidence that plants differ in their ability to take up both organic (ON and inorganic (IN forms of nitrogen (N has increased ecologists' interest on resource-based plant competition. However, whether plant uptake of IN and ON responds to differences in soil microbial community composition and/or functioning has not yet been explored, despite soil microbes playing a key role in N cycling. Here, we report results from a competition experiment testing the hypothesis that soil microbial communities differing in metabolic activity as a result of long-term differences to grazing exposure could modify N uptake of Eriophorum vaginatum L. and Nardus stricta L. These graminoids co-occur on nutrient-poor, mountain grasslands where E. vaginatum decreases and N. stricta increases in response to long-term grazing. We inoculated sterilised soil with soil microbial communities from continuously grazed and ungrazed grasslands and planted soils with both E. vaginatum and N. stricta, and then tracked uptake of isotopically labelled NH(4 (+ (IN and glycine (ON into plant tissues. The metabolically different microbial communities had no effect on N uptake by either of the graminoids, which might suggest functional equivalence of soil microbes in their impacts on plant N uptake. Consistent with its dominance in soils with greater concentrations of ON relative to IN in the soluble N pool, Eriophorum vaginatum took up more glycine than N. stricta. Nardus stricta reduced the glycine proportion taken up by E. vaginatum, thus increasing niche overlap in N usage between these species. Local abundances of these species in mountain grasslands are principally controlled by grazing and soil moisture, although our results suggest that changes in the relative availability of ON to IN can also play a role. Our results also suggest that coexistence of these species in mountain grasslands is likely based on non-equilibrium mechanisms such as disturbance and/or soil heterogeneity.

  15. Evaporation from Pinus caribaea plantations on former grassland soils under maritime tropical conditions.

    NARCIS (Netherlands)

    Waterloo, M.J.; Bruijnzeel, L.A.; Vugts, H.F.; Rawaqa, T.T.

    1999-01-01

    Wet canopy and dry canopy evaporation from young and mature plantations of Pinus caribaea on former grassland soils under maritime tropical conditions in southwestern Viti Levu, Fiji, were determined using micrometeorological and hydrological techniques. Modeled annual evaporation totals (ET) of

  16. Evaporation from Pinus caribaea plantations on former grassland soils under maritime tropical conditions

    NARCIS (Netherlands)

    Waterloo, M.J.; Bruijnzeel, L.A.; Vugts, H.F.; Rawaqa, T.T.

    1999-01-01

    Wet canopy and dry canopy evaporation from young and mature plantations of Pinus caribaea on former grassland soils under maritime tropical conditions in southwestern Viti Levu, Fiji, were determined using micrometeorological and hydrological techniques. Modeled annual evaporation totals (ET) of

  17. NPP Grassland: Beacon Hill, U.K., 1972-1993, R1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains two ASCII text files, one providing productivity measurements for a chalk grassland on Beacon Hill, West Sussex, U.K. (50.92 N, -0.85 W) and...

  18. Soil communities promote temporal stability and species asynchrony in experimental grassland communities

    NARCIS (Netherlands)

    Pellkofer, Sarah; Van Der Heijden, Marcel G A; Schmid, Bernhard; Wagg, Cameron

    2016-01-01

    Background Over the past two decades many studies have demonstrated that plant species diversity promotes primary productivity and stability in grassland ecosystems. Additionally, soil community characteristics have also been shown to influence the productivity and composition of plant communities,

  19. Seasonal dynamics and vertical distribution of plant-feeding nematode communities in grasslands

    NARCIS (Netherlands)

    Verschoor, B.C.; Goede, de R.G.M.; Hoop, de J.W.; Vries, de F.W.

    2001-01-01

    The vertical distribution and seasonal dynamics of plant- and fungal-feeding nematode taxa in permanent grasslands were investigated. Dolichodoridae, Paratylenchus, Pratylenchus, Tylenchidae and Aphelenchoides dominated the upper 10 cm soil and their numbers strongly decreased with depth. The

  20. Monitoring Grassland Tourist Season of Inner Mongolia, China Using Remote Sensing Data

    Directory of Open Access Journals (Sweden)

    Quansheng Ge

    2014-01-01

    Full Text Available Phenology-driven events, such as spring wildflower displays or fall tree colour, are generally appreciated by tourists for centuries around the world. Monitoring when tourist seasons occur using satellite data has been an area of growing research interest in recent decades. In this paper, a valid methodology for detecting the grassland tourist season using remote sensing data was presented. On average, the beginning, the best, and the end of grassland tourist season of Inner Mongolia, China, occur in late June (±30 days, early July (±30 days, and late July (±50 days, respectively. In south region, the grassland tourist season appeared relatively late. The length of the grassland tourist season is about 90 days with strong spatial trend. South areas exhibit longer tourist season.

  1. Plant species occurrence patterns in Eurasian grasslands reflect adaptation to nutrient ratios

    NARCIS (Netherlands)

    Roeling, Ineke S.; Ozinga, Wim A.; van Dijk, Jerry; Eppinga, Maarten B.; Wassen, Martin J.

    2018-01-01

    Previous studies of Eurasian grasslands have suggested that nutrient ratios, rather than absolute nutrient availabilities and associated productivity, may be driving plant species richness patterns. However, the underlying assumption that species occupy distinct niches along nutrient ratio gradients

  2. Spontaneous colonization of restored dry grasslands by target species: restoration proceeds beyond sowing regional seed mixtures

    Czech Academy of Sciences Publication Activity Database

    Johanidesová, E.; Fajmon, K.; Jongepierová, I.; Prach, Karel

    2015-01-01

    Roč. 70, č. 4 (2015), s. 631-638 ISSN 0142-5242 Institutional support: RVO:67985939 Keywords : restoration * grasslands * spontaneous colonization Subject RIV: EH - Ecology, Behaviour Impact factor: 1.617, year: 2015

  3. PCDD/F and Aromatic Emissions from Simulated Forest and Grassland Fires

    Science.gov (United States)

    Emissions of polychlorinated dibenzodioxin and polychlorinated dibenzofuran (PCDD/F) from simulated grassland and forest fires were quantitatively sampled to derive emission factors in support of PCDD/F inventory development. Grasses from Kentucky and Minnesota; forest shrubs fro...

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Ryan G Drum

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

  6. Specialist plant species harbour higher reproductive performances in recently restored calcareous grasslands than in reference habitats

    OpenAIRE

    Harzé, Mélanie; Mahy, Grégory; Bizoux, Jean-Philippe; Piqueray, Julien; Monty, Arnaud

    2015-01-01

    Background and aims_Calcareous grasslands are local biodiversity hotspots in temperate regions that suffered intensive fragmentation. Ecological restoration projects took place all over Europe. Their success has traditionally been assessed using a plant community approach. However, population ecology can also be useful to assess restoration success and to understand underlying mechanisms. Methods_We took advantage of three calcareous grassland sites in Southern Belgium, where reference p...

  7. Energy production from grassland - Assessing the sustainability of different process chains under German conditions

    International Nuclear Information System (INIS)

    Roesch, Christine; Skarka, J.; Raab, K.; Stelzer, V.

    2009-01-01

    In many regions of Europe, grassland shapes the landscape and fulfils important functions in protecting nature, soil, and water. However, the traditional uses of grassland for forage production are vanishing with progress in breeding and structural adaptations in agriculture. On the other hand, the demand for biomass energy is rising due to political sustainability goals and financial measures to support renewable energy. Against this background, the Institute for Technology Assessment and Systems Analysis investigated the applicability, economic efficiency, and sustainability of different techniques for energy production from grassland as well as from grassland converted into maize fields or short-rotation poplars under German conditions. The results show that despite relatively high energy prices and the financial support for bioenergy, the effects of energy production from grassland on employment in agriculture and farmers' income are modest. What is beneficial are savings in non-renewable energy, reductions in greenhouse gas emissions, and local provision of energy carriers. If grassland biomass (grass silage or hay) is used for energy purposes, this brings the further advantages of preserving biodiversity and the cultural landscape and protecting of soil and groundwater. Negative impacts on sustainable development result from an increase in emissions, which leads to acidification, eutrophication, and risks to human health. The overall evaluation indicates that short-rotation poplars are comparatively advantageous from the economic and ecological point of view. Therefore, a development plan for grassland is required to identify areas where grassland could be used as an energy resource or where it would be favourable to install energy plantations with fast-growing perennial plants

  8. Pollination biology in a tropical high-altitude grassland in Brazil: Interactions at the community level

    OpenAIRE

    Freitas, L; Sazima, M

    2006-01-01

    Surveys of local assemblages of plants and their pollinators are among the most useful ways to evaluate specialization in pollination and to discuss the patterns of plant-pollinator interactions among ecosystems. The high-altitude grasslands from southeastern Brazil constitute diminutive island-like formations surrounded by montane rainforests. We registered the floral traits of 124 species from the Serra da Bricaina grasslands (about 60% of the animal-pollinated species of this flora), and d...

  9. Farming for pests? Local and landscape-scale effects of grassland management on rabbit densities

    OpenAIRE

    Petrovan , Silviu O.; Barrio , Isabel C.; Ward , Alastair I.; Wheeler , Philip M.

    2010-01-01

    Abstract In recent decades in the UK, there has been an increasing trend in numbers of the European wild rabbit, a significant agricultural pest typically associated with grassland habitats. However, the relationship between rabbit abundance and grassland management, in particular grazing, has not been sufficiently explained. We studied rabbit densities in seven pasture-dominated sites in north-east England between autumn and spring in two consecutive years, and used generalised li...

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

    Science.gov (United States)

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

    2016-01-01

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

  11. Effect of soil properties and hydrology on Archaeal community composition in three temperate grasslands on peat

    DEFF Research Database (Denmark)

    Görres, Carolyn-Monika; Conrad, Ralf; Petersen, Søren O

    2013-01-01

    Grasslands established on drained peat soils are regarded as negligible methane (CH4) sources; however, they can still exhibit considerable soil CH4 dynamics. We investigated archaeal community composition in two different fen peat soils and one bog peat soil under permanent grassland in Denmark........ Overall, there seemed to be a significant coupling between peat type and archaeal community composition, with local hydrology modifying the strength of this coupling....

  12. Effects of short term and long term soil warming on ecosystem phenology of a sub-arctic grassland: an NDVI-based approach

    Science.gov (United States)

    Leblans, Niki; Sigurdsson, Bjarni D.; Janssens, Ivan A.

    2014-05-01

    Phenology has been defined as the study of the timing of recurring biological events and the causes of their timing with regard to abiotic and biotic factors. Ecosystem phenology, including the onset of the growing season and its senescence in autumn, plays an important role in the carbon, water and energy exchange between biosphere and atmosphere at higher latitudes. Factors that influence ecosystem phenology can therefore induce important climate-controlling feedback mechanisms. Global surface temperatures have been predicted to increase in the coming decades. Hence, a better understanding of the effect of temperature on ecosystem phenology is essential. Natural geothermal soil temperature gradients in Iceland offer a unique opportunity to study the soil temperature (Ts) dependence of ecosystem phenology and distinguish short-term (transient) warming effects (in recently established Ts gradients) from long-term (permanent) effects (in centuries-old Ts gradients). This research was performed in the framework of an international research project (ForHot; www.forhot.is). ForHot includes two natural grassland areas with gradients in Ts, dominated by Festuca sp., Agrostis sp.. The first warmed area was created in 2008, when an earthquake in S-Iceland caused geothermal systems to be shifted to previously cold soils. The second area is located about 3 km away from this newly warmed grassland. For this area, there are proofs that the natural soil warming has been continuous for at least 300 year. In the present study we focus on Ts elevation gradients of +0 to +10°C. The experiment consists of five transects with five temperature levels (+0,+1,+3,+5 and +10°C) in the two aforementioned grassland ecosystems (n=25 in each grassland). From April until November 2013, weekly measurements of the normalized difference vegetation index (NDVI) were taken. In the short-term warmed grassland, the greening of the vegetation was 36 days advanced at +10°C Ts and the date of 50

  13. 78 FR 77447 - California Wind Energy Association, First Solar, Inc. v. California Independent System Operator...

    Science.gov (United States)

    2013-12-23

    ... Energy Association, First Solar, Inc. v. California Independent System Operator Corporation, Southern...), California Wind Energy Association and First Solar, Inc. (collectively, Complainants) filed a formal complaint against the California Independent System Operator Corporation (CAISO) and Southern California...

  14. Biomonitoring in California Firefighters

    Science.gov (United States)

    Israel, Leslie; McNeel, Sandra; Voss, Robert; Wang, Miaomiao; Gajek, Ryszard; Park, June-Soo; Harwani, Suhash; Barley, Frank; She, Jianwen; Das, Rupali

    2015-01-01

    Objective: To assess California firefighters' blood concentrations of selected chemicals and compare with a representative US population. Methods: We report laboratory methods and analytic results for cadmium, lead, mercury, and manganese in whole blood and 12 serum perfluorinated chemicals in a sample of 101 Southern California firefighters. Results: Firefighters' blood metal concentrations were all similar to or lower than the National Health and Nutrition Examination Survey (NHANES) values, except for six participants whose mercury concentrations (range: 9.79 to 13.42 μg/L) were close to or higher than the NHANES reporting threshold of 10 μg/L. Perfluorodecanoic acid concentrations were elevated compared with NHANES and other firefighter studies. Conclusions: Perfluorodecanoic acid concentrations were three times higher in this firefighter group than in NHANES adult males. Firefighters may have unidentified sources of occupational exposure to perfluorinated chemicals. PMID:25563545

  15. Grassland habitat restoration: lessons learnt from long term monitoring of Swanworth Quarry, UK, 1997–2014

    Directory of Open Access Journals (Sweden)

    Barbara Maria Smith

    2017-11-01

    Full Text Available Habitat restoration projects are often conducted when prior use or extraction of natural resources results in land degradation. The success of restoration programmes, however, is variable, and studies that provide evidence of long term outcomes are valuable for evaluation purposes. This study focused on the restoration of vegetation within a limestone quarry in Dorset, UK between 1997 and 2014. Using a randomised block design, the effect of seed mix and seed rate on the development of community assemblage was investigated in comparison to a nearby target calcareous grassland site. We hypothesised that seed mix composition and sowing rate would influence both the trajectory of the grassland assemblage and final community composition. We found that species composition (in relation to both richness and community assemblage was strongly influenced by time and to some extent by seed rate and seed mix. However, no treatments achieved strong resemblance to the calcareous grassland target vegetation; rather they resembled mesotrophic communities. We conclude that (as with previous studies there is no “quick fix” for the establishment of a grassland community; long-term monitoring provides useful information on the trajectory of community development; sowing gets you something (in our case mesotrophic grassland, but, it may not be the target vegetation (e.g., calcicolous grassland you want that is difficult to establish and regenerate; it is important to sow a diverse mix as subsequent recruitment opportunities are probably limited; post-establishment management should be explored further and carefully considered as part of a restoration project.

  16. Striking a balance: socioeconomic development and conservation in grassland through community-based zoning.

    Directory of Open Access Journals (Sweden)

    Craig Leisher

    Full Text Available The goal of preserving nature is often in conflict with economic development and the aspirations of the rural poor. Nowhere is this more striking than in native grasslands, which have been extensively converted until a mere fraction of their original extent remains. This is not surprising; grasslands flourish in places coveted by humans, primed for agriculture, plantations, and settlements that nearly always trump conservation efforts. The Umgano grassland conservation and poverty reduction project in KwaZulu-Natal Province, South Africa uses community-based spatial planning to balance the conversion of its lower-conservation value grasslands to a timber plantation, while conserving higher-value grasslands for heritage purposes and managed livestock grazing. Ten years after project launch, we measured the ecological and socioeconomic impacts of the project using Normalized Differential Vegetation Index remote sensing data and over 500 household interviews, as compared with similar non-conserved areas. Zoned management of the Umgano area had resulted in between 9% and 17% greater average peak production in the grassland areas compared to control sites. There was also a 21% gain in incomes for the roughly one hundred people employed by the forestry efforts, when compared to others in their village. Community-based spatial zoning is an overlooked tool for balancing conservation and development but may require, as we found in Umgano, certain critical factors including strong local leadership, an accountable financial management mechanism to distribute income, outside technical expertise for the zoning design, and community support.

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

    Science.gov (United States)

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

    2017-03-01

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

  18. SUGARLOAF ROADLESS AREA, CALIFORNIA.

    Science.gov (United States)

    Powell, Robert E.; Campbell, Harry W.

    1984-01-01

    On the basis of geologic, geochemical, and geophysical investigations and a survey of mines, quarries, and prospects the Sugarloaf Roadless Area, California, has little promise for the occurrence of metallic mineral or energy resources. Units of carbonate rock and graphitic schist have demonstrated resources of magnesian marble and graphite. Sand, gravel, and construction stone other than carbonate rock are present in the roadless area, but similar or better quality materials are abundant and more accessible outside the area.

  19. Medical marijuana: California update.

    Science.gov (United States)

    James, J S

    1996-08-23

    The Cannabis Buyers' Club in San Francisco remains closed after it was raided by the office of California Attorney General Dan Lungren. Many individuals with serious illnesses such as AIDS and cancer are without safe access to medical marijuana to relieve the symptoms of their diseases. The need for access to medicinal marijuana, the return of the confiscated confidential medical records held at the buyers' club, and the passage of California Proposition 215 in the November election, which allows for the legitimate use of marijuana for medical purposes are of immediate concern. Since the raid, the Cannabis Buyers' Club has denied charges that it sold marijuana to teenagers, saying the drug was sold to a teen's mother, an undercover narcotics officer. However, the club admitted to sales to non-medical individuals who used fraudulent documents in order to obtain the drug and acknowledges the need to tighten procedures. Individuals may be able to obtain marijuana at other buyers' clubs if they have documentation of a medical need. While literature on the medical use of marijuana is lacking, the Federal government continues to block any efforts toward medical research on this issue. A list of other cannabis buyers' clubs in California is included, as well as a list of organizations working for Proposition 215.

  20. The effect of warming on grassland evapotranspiration partitioning using laser-based isotope monitoring techniques

    KAUST Repository

    Wang, Lixin; Niu, Shuli; Good, Stephen P.; Soderberg, Keir; McCabe, Matthew; Sherry, Rebecca A.; Luo, Yiqi; Zhou, Xuhui; Xia, Jianyang; Caylor, Kelly K.

    2013-01-01

    The proportion of transpiration (T) in total evapotranspiration (ET) is an important parameter that provides insight into the degree of biological influence on the hydrological cycles. Studies addressing the effects of climatic warming on the ecosystem total water balance are scarce, and measured warming effects on the T/ET ratio in field experiments have not been seen in the literature. In this study, we quantified T/ET ratios under ambient and warming treatments in a grassland ecosystem using a stable isotope approach. The measurements were made at a long-term grassland warming site in Oklahoma during the May-June peak growing season of 2011. Chamber-based methods were used to estimate the δ2H isotopic composition of evaporation (δE), transpiration (δT) and the aggregated evapotranspiration (δET). A modified commercial conifer leaf chamber was used for δT, a modified commercial soil chamber was used for δE and a custom built chamber was used for δET. The δE, δET and δT were quantified using both the Keeling plot approach and a mass balance method, with the Craig-Gordon model approach also used to calculate δE. Multiple methods demonstrated no significant difference between control and warming plots for both δET and δT. Though the chamber-based estimates and the Craig-Gordon results diverged by about 12‰, all methods showed that δE was more depleted in the warming plots. This decrease in δE indicates that the evaporation flux as a percentage of total water flux necessarily decreased for δET to remain constant, which was confirmed by field observations. The T/ET ratio in the control treatment was 0.65 or 0.77 and the ratio found in the warming treatment was 0.83 or 0.86, based on the chamber method and the Craig-Gordon approach. Sensitivity analysis of the Craig-Gordon model demonstrates that the warming-induced decrease in soil liquid water isotopic composition is the major factor responsible for the observed δE depletion and the temperature

  1. The effect of warming on grassland evapotranspiration partitioning using laser-based isotope monitoring techniques

    KAUST Repository

    Wang, Lixin

    2013-06-01

    The proportion of transpiration (T) in total evapotranspiration (ET) is an important parameter that provides insight into the degree of biological influence on the hydrological cycles. Studies addressing the effects of climatic warming on the ecosystem total water balance are scarce, and measured warming effects on the T/ET ratio in field experiments have not been seen in the literature. In this study, we quantified T/ET ratios under ambient and warming treatments in a grassland ecosystem using a stable isotope approach. The measurements were made at a long-term grassland warming site in Oklahoma during the May-June peak growing season of 2011. Chamber-based methods were used to estimate the δ2H isotopic composition of evaporation (δE), transpiration (δT) and the aggregated evapotranspiration (δET). A modified commercial conifer leaf chamber was used for δT, a modified commercial soil chamber was used for δE and a custom built chamber was used for δET. The δE, δET and δT were quantified using both the Keeling plot approach and a mass balance method, with the Craig-Gordon model approach also used to calculate δE. Multiple methods demonstrated no significant difference between control and warming plots for both δET and δT. Though the chamber-based estimates and the Craig-Gordon results diverged by about 12‰, all methods showed that δE was more depleted in the warming plots. This decrease in δE indicates that the evaporation flux as a percentage of total water flux necessarily decreased for δET to remain constant, which was confirmed by field observations. The T/ET ratio in the control treatment was 0.65 or 0.77 and the ratio found in the warming treatment was 0.83 or 0.86, based on the chamber method and the Craig-Gordon approach. Sensitivity analysis of the Craig-Gordon model demonstrates that the warming-induced decrease in soil liquid water isotopic composition is the major factor responsible for the observed δE depletion and the temperature

  2. Estimating photosynthesis with high resolution field spectroscopy in a Mediterranean grassland under different nutrient availability

    Science.gov (United States)

    Perez-Priego, O.; Guan, J.; Fava, F.; Rossini, M.; Wutzler, T.; Moreno, G.; Carrara, A.; Kolle, O.; Schrumpf, M.; Reichstein, M.; Migliavacca, M.

    2014-12-01

    Recent studies have shown how human induced N:P imbalances are affecting essential processes (e.g. photosynthesis, plant growth rate) that lead to important changes in ecosystem structure and function. In this regard, the accuracy of the approaches based on remotely-sensed data for monitoring and modeling gross primary production (GPP) relies on the ability of vegetation indices (VIs) to track the dynamics of vegetation physiological and biophysical properties/variables. Promising results have been recently obtained when Chlorophyll-sensitive VIs and Chlorophyll fluorescence are combined with structural indices in the framework of the Monteith's light use efficiency (LUE) model. However, further ground-based experiments are required to validate LUE model performances, and their capability to be generalized under different nutrient availability conditions. In this study, the overall objective was to investigate the sensitivity of VIs to track short- and long-term GPP variations in a Mediterranean grassland under different N and P fertilization treatments. Spectral VIs were acquired manually using high resolution spectrometers (HR4000, OceanOptics, USA) along a phenological cycle. The VIs examined included photochemical reflectance index (PRI), MERIS terrestrial-chlorophyll index (MTCI) and normalized difference vegetation index (NDVI). Solar-induced chlorophyll fluorescence calculated at the oxygen absorption band O2-A (F760) using spectral fitting methods was also used. Simultaneously, measurements of GPP and environmental variables were conducted using a transient-state canopy chamber. Overall, GPP, F760 and VIs showed a clear seasonal time-trend in all treatments, which was driven by the phenological development of the grassland. Results showed significant differences (p<0.05) in midday GPP values between N and without N addition plots, in particular at the peak of the growing season during the flowering stage and at the end of the season during senescence. While

  3. Soil emission and uptake of carbonyl sulfide at a temperate mountain grassland

    Science.gov (United States)

    Kitz, Florian; Hammerle, Albin; Laterza, Tamara; Spielmann, Felix M.; Wohlfahrt, Georg

    2016-04-01

    Flux partitioning, i.e. inferring gross primary productivity (GPP) and ecosystem respiration from the measured net ecosystem carbon dioxide (CO2) exchange, is one uncertainty in modelling the carbon cycle and in times where robust models are needed to assess future global changes a persistent problem. A promising new approach is to derive GPP by measuring carbonyl sulfide (COS), the most abundant sulfur-containing trace gas in the atmosphere, with a mean concentration of about 500 pptv in the troposphere. This is possible because COS and CO2 enter the leaf via a similar pathway and are processed by the same enzyme (carbonic anhydrase). A prerequisite to use COS as a proxy for canopy photosynthesis is a robust estimation of COS sources and sinks in an ecosystem. Past studies described soils either as a sink or source, depending on properties like soil temperature and soil water content. The main aim of this study was to quantify the soil COS exchange and its drivers of a temperate mountain grassland in order to aid the use of COS as tracer for canopy CO2 and water vapor exchange. We conducted a field campaign with a Quantum cascade laser at a temperate mountain grassland to estimate the soil COS fluxes under ambient conditions and while simulating a drought. We used self-built fused silica (i.e. light-transparent) soil chambers to avoid COS emissions from built-in materials and to assess the impact of radiation. Vegetation was removed within the chambers, therefor more radiation reached the soil surface compared to natural conditions. This might be the reason for highly positive fluxes during daytime more similar to agricultural study sites. To further investigate this large soil COS source we conducted within canopy concentration measurements near the soil surface and still recorded fluxes confirming the soil as a COS source during daytime. Results from the drought experiment suggested a strong impact of incoming radiation on soil COS fluxes followed by soil

  4. Impact of Altered Precipitation Patterns on Plant Productivity and Soil Respiration in a Northern Great Plains Grassland

    Science.gov (United States)

    Haase, L.; Flanagan, L. B.

    2017-12-01

    Precipitation patterns are expected to shift towards larger but fewer rain events, with longer intermittent dry periods, associated with climate change. The larger rain events may compensate for and help to mitigate climate change effects on key ecosystem functions such as plant productivity and soil respiration in semi-arid grasslands. We experimentally manipulated the amount and frequency of simulated precipitation added to trenched, treatment plots that were covered by rain shelters, and measured the response in plant productivity and soil respiration in a native, grassland ecosystem near Lethbridge, Alberta. We compared the observed responses to the predictions of a conceptual ecosystem response model developed by Knapp et al. 2008 (BioScience 58: 811-821). Two experiments were conducted during 14 weeks of the growing season from May-August. The first experiment (normal amount) applied total growing season precipitation of 180 mm (climate normal), and the second experiment (reduced amount) applied total precipitation of 90 mm. In both experiments, precipitation was applied at two frequencies, 1 rain event every week (normal frequency) and 1 rain event every two weeks (reduced frequency). In the normal amount experiment, the average rain event was 12.8 mm for the normal frequency treatment and 25.8 mm for the reduced frequency treatment. In the reduced amount experiment, the average rain event was 6.4 mm for the normal frequency treatment and 12.8 mm for the reduced frequency treatment. We hypothesized that larger but fewer rain events would result in increased plant productivity and soil respiration for both experiments. Plant greenness values calculated from digital photographs were used as a proxy for plant productivity, and showed significantly higher values for the normal vs. reduced amount experiment. Soil respiration rate also showed significantly higher values for the normal vs. reduced amount experiment. No significant treatment effect could be detected

  5. A summary of eight traits of Coleoptera, Hemiptera, Orthoptera and Araneae, occurring in grasslands in Germany

    Science.gov (United States)

    Gossner, Martin M.; Simons, Nadja K.; Achtziger, Roland; Blick, Theo; Dorow, Wolfgang H. O.; Dziock, Frank; Köhler, Frank; Rabitsch, Wolfgang; Weisser, Wolfgang W.

    2015-03-01

    Analyses of species traits have increased our understanding of how environmental drivers such as disturbances affect the composition of arthropod communities and related processes. There are, however, few studies on which traits in the arthropod community are affected by environmental changes and which traits affect ecosystem functioning. The assembly of arthropod traits of several taxa is difficult because of the large number of species, limited availability of trait databases and differences in available traits. We sampled arthropod species data from a total of 150 managed grassland plots in three regions of Germany. These plots represent the spectrum from extensively used pastures to mown pastures to intensively managed and fertilized meadows. In this paper, we summarize information on body size, dispersal ability, feeding guild and specialization (within herbivores), feeding mode, feeding tissue (within herbivorous suckers), plant part (within herbivorous chewers), endophagous lifestyle (within herbivores), and vertical stratum use for 1,230 species of Coleoptera, Hemiptera (Heteroptera, Auchenorrhyncha), Orthoptera (Saltatoria: Ensifera, Caelifera), and Araneae, sampled by sweep-netting between 2008 and 2012. We compiled traits from various literature sources and complemented data from reliable internet sources and the authors’ experience.

  6. Impact of Grassland Reseeding, Herbicide Spraying and Ploughing on Diversity and Abundance of Soil Arthropods

    Science.gov (United States)

    Liu, Wei; Zhang, Junling; Norris, Stuart L.; Murray, Philip J.

    2016-01-01

    In order to determine the interactive effect of reseeding, herbicide spraying and ploughing on soil fauna communities, we conducted a grassland reseeding experiment combined with pre-reseed management to examine how with the whole reseeding process affects soil faunal composition. Sampling occasions and exact treatments were as follows: (1) before chemical herbicide spray; (2) after spray but before ploughing; (3) after ploughing but before reseeding; and (4) after 1 year of recovery. Our results demonstrate that, Acari and Collembola were the two soil fauna taxa with the highest abundance and accounted for around 96% of the relative total abundance among the various managements. Herbicide application tended to increase soil invertebrate abundance. Conversely, subsequent ploughing significantly reduced soil invertebrate abundance and had an obvious negative effect on soil primary and secondary decomposers, which were mainly due to the variations of Acari (especially Oribatida) and Coleoptera group abundance. Moreover, reseeding also reduced the individual number of the groups mentioned above, and favored those predators with a larger body size and individual weight. After 1 year recovery, Collembola abundance recovered to the pre-treatment levels, while with Arthropod and Acari groups were still fluctuating. PMID:27555863

  7. Greenhouse gas balance of an establishing Sphagnum culture on a former bog grassland in Germany

    Directory of Open Access Journals (Sweden)

    A. Günther

    2017-04-01

    Full Text Available The cultivation of Sphagnum mosses on re-wetted peat bogs for use in horticulture is a new land use strategy. We provide the first greenhouse gas balances for a field-scale Sphagnum farming experiment on former bog grassland, in its establishment phase. Over two years we used closed chambers to make measurements of GHG exchange on production strips of Sphagnum palustre L. and Sphagnum papillosum Lindb. and on irrigation ditches. Methane fluxes of both Sphagnum species showed a significant decrease over the study period. This trend was stronger for S. papillosum. In contrast, the estimated CO2 fluxes did not show a significant temporal trend over the study period. The production strips of both Sphagnum species were net GHG sinks of 5–9 t ha 1 a 1 (in CO2-equivalents during the establishment phase of the moss carpets. In comparison, the ditches were a CO2 source instead of a CO2 sink and emitted larger amounts of CH4, resulting in net GHG release of ~11 t ha 1 a 1 CO2-equivalents. We conclude that Sphagnum farming fields should be designed to minimise the area covered by irrigation ditches. Overall, Sphagnum farming on bogs has lower on-field GHG emissions than low-intensity agriculture.

  8. Impact of Grassland Reseeding, Herbicide Spraying and Ploughing on Diversity and Abundance of Soil Arthropods.

    Science.gov (United States)

    Liu, Wei; Zhang, Junling; Norris, Stuart L; Murray, Philip J

    2016-01-01

    In order to determine the interactive effect of reseeding, herbicide spraying and ploughing on soil fauna communities, we conducted a grassland reseeding experiment combined with pre-reseed management to examine how with the whole reseeding process affects soil faunal composition. Sampling occasions and exact treatments were as follows: (1) before chemical herbicide spray; (2) after spray but before ploughing; (3) after ploughing but before reseeding; and (4) after 1 year of recovery. Our results demonstrate that, Acari and Collembola were the two soil fauna taxa with the highest abundance and accounted for around 96% of the relative total abundance among the various managements. Herbicide application tended to increase soil invertebrate abundance. Conversely, subsequent ploughing significantly reduced soil invertebrate abundance and had an obvious negative effect on soil primary and secondary decomposers, which were mainly due to the variations of Acari (especially Oribatida) and Coleoptera group abundance. Moreover, reseeding also reduced the individual number of the groups mentioned above, and favored those predators with a larger body size and individual weight. After 1 year recovery, Collembola abundance recovered to the pre-treatment levels, while with Arthropod and Acari groups were still fluctuating.

  9. Impact of Grassland Reseeding, Herbicide spraying and Ploughing on Diversity and Abundance of Soil Arthropods.

    Directory of Open Access Journals (Sweden)

    Wei Liu

    2016-08-01

    Full Text Available In order to determine the interactive effect of reseeding, herbicide spraying and ploughing on soil fauna communities, we conducted a grassland reseeding experiment combined with pre-reseed management to examine how with the whole reseeding process affects soil faunal composition. Sampling occasions and exact treatments were as follows: 1 before chemical herbicide spray; 2 after spray but before ploughing; 3 after ploughing but before reseeding; and 4 after one year of recovery. Our results demonstrate that, Acari and Collembola were the two soil fauna taxa with the highest abundance and accounted for around 96% of the relative total abundance among the various managements. Herbicide application tended to increase soil invertebrate abundance. Conversely, subsequent ploughing significantly reduced soil invertebrate abundance and had an obvious negative effect on soil primary and secondary decomposers, which were mainly due to the variations of Acari (especially Oribatida and Coleoptera group abundance. Moreover, reseeding also reduced the individual number of the groups mentioned above, and favoured those predators with a larger body size and individual weight. After one year recovery, Collembola abundance recovered to the pre-treatment levels, while with Arthropod and Acari groups were still fluctuating.

  10. Ecoregions of California

    Science.gov (United States)

    Griffith, Glenn E.; Omernik, James M.; Smith, David W.; Cook, Terry D.; Tallyn, Ed; Moseley, Kendra; Johnson, Colleen B.

    2016-02-23

    Ecoregions denote areas of general similarity in ecosystems and in the type, quality, and quantity of environmental resources. They are designed to serve as a spatial framework for the research, assessment, management, and monitoring of ecosystems and ecosystem components. By recognizing the spatial differences in the capacities and potentials of ecosystems, ecoregions stratify the environment by its probable response to disturbance (Bryce and others, 1999). These general purpose regions are critical for structuring and implementing ecosystem management strategies across Federal agencies, State agencies, and nongovernment organizations that are responsible for different types of resources in the same geographical areas (Omernik and others, 2000).The approach used to compile this map is based on the premise that ecological regions are hierarchical and can be identified through the analysis of the spatial patterns and the composition of biotic and abiotic phenomena that affect or reflect differences in ecosystem quality and integrity (Wiken, 1986; Omernik, 1987, 1995). These phenomena include geology, physiography, vegetation, climate, soils, land use, wildlife, and hydrology. The relative importance of each characteristic varies from one ecological region to another regardless of the hierarchical level. A Roman numeral hierarchical scheme has been adopted for different levels of ecological regions. Level I is the coarsest level, dividing North America into 15 ecological regions. Level II divides the continent into 50 regions (Commission for Environmental Cooperation Working Group, 1997, map revised 2006). At level III, the continental United States contains 105 ecoregions and the conterminous United States has 85 ecoregions (U.S. Environmental Protection Agency, 2013). Level IV, depicted here for California, is a further refinement of level III ecoregions. Explanations of the methods used to define these ecoregions are given in Omernik (1995), Omernik and others

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

    Science.gov (United States)

    Smith, Dakota Carlysle

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

  12. Seasonal/Interannual Variations of Carbon Sequestration and Carbon Emission in a Warm-Season Perennial Grassland

    OpenAIRE

    Deepa Dhital; Tomoharu Inoue; Hiroshi Koizumi

    2014-01-01

    Carbon sequestration and carbon emission are processes of ecosystem carbon cycling that can be affected while land area converted to grassland resulting in increased soil carbon storage and below-ground respiration. Discerning the importance of carbon cycle in grassland, we aimed to estimate carbon sequestration in photosynthesis and carbon emission in respiration from soil, root, and microbes, for four consecutive years (2007–2010) in a warm-season perennial grassland, Japan. Soil carbon emi...

  13. The October 1992 Parkfield, California, earthquake prediction

    Science.gov (United States)

    Langbein, J.

    1992-01-01

    A magnitude 4.7 earthquake occurred near Parkfield, California, on October 20, 992, at 05:28 UTC (October 19 at 10:28 p.m. local or Pacific Daylight Time).This moderate shock, interpreted as the potential foreshock of a damaging earthquake on the San Andreas fault, triggered long-standing federal, state and local government plans to issue a public warning of an imminent magnitude 6 earthquake near Parkfield. Although the predicted earthquake did not take place, sophisticated suites of instruments deployed as part of the Parkfield Earthquake Prediction Experiment recorded valuable data associated with an unusual series of events. this article describes the geological aspects of these events, which occurred near Parkfield in October 1992. The accompnaying article, an edited version of a press conference b Richard Andrews, the Director of the California Office of Emergency Service (OES), describes governmental response to the prediction.   

  14. Measuring denitrification after grassland renewal and grassland conversion to cropland by using the 15N gas-flux method

    Science.gov (United States)

    Buchen, Caroline; Eschenbach, Wolfram; Flessa, Heinz; Giesemann, Anette; Lewicka-Szczebak, Dominika; Well, Reinhard

    2015-04-01

    Denitrification, the reduction of oxidized forms of inorganic N to N2O and N2 is an important pathway of gaseous nitrogen losses. Measuring denitrification, especially the reduction of N2O to N2, expressed in the product ratio (N2O/(N2O + N2)), is rather difficult and hence rarely performed under field conditions. But using the 15N gas-flux method allows determining N transformation processes in their natural environment. In order to develop effective climate mitigation strategies understanding the N2O source is essential. We used the 15N gas-flux method to determine N2O and N2 emissions following grassland renewal and conversion techniques. Therefore we selected three different treatments: control (C), mechanical grassland renovation (GR) (autumn 2013) and grassland conversion to maize (GM) (spring 2014) from field plot trials on two different sites (Histic Gleysoil and Plaggic Anthrosol) near Oldenburg, Lower Saxony, Germany. We applied 15N labeled KNO3- (60 atom. % 15N) at a rate equivalent to common farming practices (150 kg N*ha-1) using needle injection of fertilizer solution in three different depths (10 cm, 15 cm, 20 cm) for homogeneous soil labeling up to 30 cm in microplots. During the first 10 days after application (May 2014) gas flux measurements from closed chambers were performed every second day and then weekly following a period of 8 weeks. Gas samples were analyzed for δ15N of N2 and N2O by IRMS according to Lewicka-Szczebak et al. (2013). Concentration and 15N enrichment of NO3- in soil water was determined on weekly samples using the SPIN-MAS technique (Stange et al. 2007). Fluxes of N2 and N2O evolved from the 15N labeled soil nitrogen pool were calculated using the equations of Spott et al. (2006). Peak events of N2 and N2O emissions occurred during the first 10 days of measurement, showing differences in soil types, as well as treatment variations. N2 fluxes up to 178 g*ha-1*day-1 and N2O fluxes up to 280 g*ha-1*day-1 were measured on the

  15. California community water systems inventory dataset, 2010

    Data.gov (United States)

    California Environmental Health Tracking Program — This data set contains information about all Community Water Systems in California. Data are derived from California Office of Drinking Water (ODW) Water Quality...

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

    Science.gov (United States)

    Adane, Zablon A.

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

  17. Effect of soil saturation on denitrification in a grassland soil

    Directory of Open Access Journals (Sweden)

    L. M. Cardenas

    2017-10-01

    Full Text Available Nitrous oxide (N2O is of major importance as a greenhouse gas and precursor of ozone (O3 destruction in the stratosphere mostly produced in soils. The soil-emitted N2O is generally predominantly derived from denitrification and, to a smaller extent, nitrification, both processes controlled by environmental factors and their interactions, and are influenced by agricultural management. Soil water content expressed as water-filled pore space (WFPS is a major controlling factor of emissions and its interaction with compaction, has not been studied at the micropore scale. A laboratory incubation was carried out at different saturation levels for a grassland soil and emissions of N2O and N2 were measured as well as the isotopocules of N2O. We found that flux variability was larger in the less saturated soils probably due to nutrient distribution heterogeneity created from soil cracks and consequently nutrient hot spots. The results agreed with denitrification as the main source of fluxes at the highest saturations, but nitrification could have occurred at the lower saturation, even though moisture was still high (71 % WFSP. The isotopocules data indicated isotopic similarities in the wettest treatments vs. the two drier ones. The results agreed with previous findings where it is clear there are two N pools with different dynamics: added N producing intense denitrification vs. soil N resulting in less isotopic fractionation.

  18. Plutonium in a grassland ecosystem. [Rocky Flats Plant

    Energy Technology Data Exchange (ETDEWEB)

    Little, C.A.

    1976-08-01

    A study was made of plutonium contamination of grassland at the Rocky Flats plant northwest of Denver, Colorado. Of interest were: the definition of major plutonium-containing ecosystem compartments; the relative amounts in those compartments; how those values related to studies done in other geographical areas; whether or not the predominant isotopes, /sup 238/Pu and /sup 239/Pu, behaved differently; and what mechanisms might have allowed for the observed patterns of contamination. Samples of soil, litter, vegetation, arthropods, and small mammals were collected for Pu analysis and mass determination from each of two macroplots. Small aliquots (5 g or less) were analyzed by a rapid liquid scintillation technique and by alpha spectrometry. Of the compartments sampled, greater than 99 percent of the total plutonium was contained in the soil and the concentrations were significantly inversely correlated with distance from the contamination source, depth of the sample, and particle size of the sieved soil samples. The soil data suggested that the distribution of contamination largely resulted from physical transport processes.

  19. Metacommunity analysis of amoeboid protists in grassland soils.

    Science.gov (United States)

    Fiore-Donno, Anna Maria; Weinert, Jan; Wubet, Tesfaye; Bonkowski, Michael

    2016-01-11

    This study reveals the diversity and distribution of two major ubiquitous groups of soil amoebae, the genus Acanthamoeba and the Myxomycetes (plasmodial slime-moulds) that are rarely, if ever, recovered in environmental sampling studies. We analyzed 150 grassland soil samples from three Biodiversity Exploratories study regions in Germany. We developed specific primers targeting the V2 variable region in the first part of the small subunit of the ribosomal RNA gene for high-throughput pyrotag sequencing. From ca. 1 million reads, applying very stringent filtering and clustering parameters to avoid overestimation of the diversity, we obtained 273 acanthamoebal and 338 myxomycete operational taxonomic units (OTUs, 96% similarity threshold). This number is consistent with the genetic diversity known in the two investigated lineages, but unequalled to date by any environmental sampling study. Only very few OTUs were identical to already known sequences. Strikingly different OTUs assemblages were found between the three German regions (PerMANOVA p.value = 0.001) and even between sites of the same region (multiple-site Simpson-based similarity indices <0.4), showing steep biogeographical gradients.

  20. Soil invertebrate fauna enhances grassland succession and diversity.

    Science.gov (United States)

    De Deyn, Gerlinde B; Raaijmakers, Ciska E; Zoomer, H Rik; Berg, Matty P; de Ruiter, Peter C; Verhoef, Herman A; Bezemer, T Martijn; van der Putten, Wim H

    2003-04-17

    One of the most important areas in ecology is to elucidate the factors that drive succession in ecosystems and thus influence the diversity of species in natural vegetation. Significant mechanisms in this process are known to be resource limitation and the effects of aboveground vertebrate herbivores. More recently, symbiotic and pathogenic soil microbes have been shown to exert a profound effect on the composition of vegetation and changes therein. However, the influence of invertebrate soil fauna on succession has so far received little attention. Here we report that invertebrate soil fauna might enhance both secondary succession and local plant species diversity. Soil fauna from a series of secondary grassland succession stages selectively suppress early successional dominant plant species, thereby enhancing the relative abundance of subordinate species and also that of species from later succession stages. Soil fauna from the mid-succession stage had the strongest effect. Our results clearly show that soil fauna strongly affects the composition of natural vegetation and we suggest that this knowledge might improve the restoration and conservation of plant species diversity.

  1. The nutritive value of Valjevac grassland - Zasavica reservation

    Directory of Open Access Journals (Sweden)

    Grdović Svetlana

    2013-01-01

    Full Text Available Valjevac pasture of Zasavica reservation with its area of 300 ha presents a significant area for grazing cattle. In order to evaluate its potential for livestock production, the botanical and chemical composition of hay in three different time periods was observed (spring, summer and autumn. The determined plants species confirmed the richness of Zasavica grasslands, as well as the presence of dry, moist and forest habitat plants. The analyzed plants mostly belong to the Poaceae, Fabaceae, Asteraceae and Plantaginaceae families. Chemical analysis determined that the protein content decreased (P<0.01 from April (17.22±0.40 % to October (10.30±0.16 %, and cellulose content increased (P<0.01 (from 19.07±0.38 % in April to 21.65±0.41 % in October. The calculated energy density of hay samples ranged from 0.425 Starch Units (SU in October, 0.443 SU in April to 0.448 SU in June. The Valjevac pasture with its numerous plant species is of great importance in upkeeping biodiversity and also presents a solid base for livestock production. The determined levels of manganese and copper point out to the need of copper supplementation especially during the late summer and autumn periods. [Projekat Ministarstva nauke Republike Srbije, br. III46002

  2. Microbial Enzyme Activity and Carbon Cycling in Grassland Soil Fractions

    Science.gov (United States)

    Allison, S. D.; Jastrow, J. D.

    2004-12-01

    Extracellular enzymes are necessary to degrade complex organic compounds present in soils. Using physical fractionation procedures, we tested whether old soil carbon is spatially isolated from degradative enzymes across a prairie restoration chronosequence in Illinois, USA. We found that carbon-degrading enzymes were abundant in all soil fractions, including macroaggregates, microaggregates, and the clay fraction, which contains carbon with a mean residence time of ~200 years. The activities of two cellulose-degrading enzymes and a chitin-degrading enzyme were 2-10 times greater in organic matter fractions than in bulk soil, consistent with the rapid turnover of these fractions. Polyphenol oxidase activity was 3 times greater in the clay fraction than in the bulk soil, despite very slow carbon turnover in this fraction. Changes in enzyme activity across the restoration chronosequence were small once adjusted for increases in soil carbon concentration, although polyphenol oxidase activity per unit carbon declined by 50% in native prairie versus cultivated soil. These results are consistent with a `two-pool' model of enzyme and carbon turnover in grassland soils. In light organic matter fractions, enzyme production and carbon turnover both occur rapidly. However, in mineral-dominated fractions, both enzymes and their carbon substrates are immobilized on mineral surfaces, leading to slow turnover. Soil carbon accumulation in the clay fraction and across the prairie restoration chronosequence probably reflects increasing physical isolation of enzymes and substrates on the molecular scale, rather than the micron to millimeter scale.

  3. Seasonal methane dynamics in three temperate grasslands on peat

    DEFF Research Database (Denmark)

    Schäfer, Carolyn; Elsgaard, Lars; Hoffmann, Carl Christian

    2012-01-01

    Background and Aims Drained peatlands are considered to be insignificant CH4 sources, but the effect of drainage on CH4 dynamics has not been extensively studied. We investigated seasonal dynamics of CH4 in two fen peat soils and one bog peat soil under permanent grassland in Denmark. Methods Soil......, even though soil CH4 concentrations of up to 155 and 1000 μmol CH4 dm−3 were measured in one of the fen peats and in the bog peat, respectively. Significant CH4 concentrations were observed above the water table. Methane production assays confirmed the presence of viable methanogens in the upper parts...... of the bog peat soil. The aerenchymous plant Juncus effusus L. liberated CH4 from the peat at rates of up to 3.3 mg CH4 m−2 h−1. No CH4 dynamics were observed in the second fen peat which, in contrast to the other two sites, had high sulfate concentrations. Conclusions Peat type and the distribution...

  4. Analysis of the production stability of mixed grasslands. II. A mathematical framework for the quantification of production stability of grassland ecosystems

    NARCIS (Netherlands)

    Schulte, R.P.O.

    2003-01-01

    The analysis of the intrinsic properties and processes of ecosystems, which regulate the production stability of mixed grasslands, has been complicated by the environmental noise caused by stochastic weather fluctuations. A mathematical framework is presented to deduct the actual, the extrinsic and

  5. Changing patterns of basic household consumption in the Inner Mongolian grasslands: a case study of policy-oriented adoptive changes in the use of grasslands

    NARCIS (Netherlands)

    Du, B.; Zhen, L.; Groot, de R.S.; Goulden, C.E.; Long, X.; Cao, X.; Wu, R.; Sun, C.

    2014-01-01

    Grassland ecosystems, as the basic natural resources in the Inner Mongolia Autonomous Region, are becoming increasingly sensitive to human intervention, leading to deterioration in fragile ecosystems. The goal of this study was to describe the restoration policy-oriented adoptive changes to basic

  6. [Diversity and distribution of grasshoppers (Orthoptera: Acridoidea) in grasslands of the Southern Pampas region, Argentina].

    Science.gov (United States)

    Mariottini, Yanina; De Wysiecki, María Laura; Lange, Carlos Ernesto

    2013-03-01

    In Argentina, the grasslands of Pampas region comprise approximately 15% of the country. As in other grasslands of the world, grasshoppers are among the most important native herbivores. Their economic importance has been recognized in Argentina since the mid to late nineteenth century, since outbreaks of different species have become recurrent phenomena. Therefore, the main objective of this work was to study their diversity and distribution in grasslands of the Southern Pampas region (Laprida county, Buenos Aires province), as one of the most affected areas. The study was conducted during five seasons (2005-10). Sampling sites were represented by the most common plant communities in this area, classified in four categories: native grasslands, disturbed grasslands, implanted pastures and halophilous grasslands. The samplings were conducted from mid-spring to early autumn, with five or six samples per season. We estimated the following population descriptors: species richness (S), eveness (E), dominance (J), and diversity index (H'). In order to evaluate the similitude of the grasshopper communities present in the different plant communities, we used qualitative and quantitative coefficients of similitude. A total of 22 species of grasshoppers were collected, of which 21 belong to the family Acrididae. The subfamily Melanoplinae was the most diverse with eight species. The largest species richness was recorded in native grasslands (18). The different communities of grasshoppers had similar indices of evenness and dominance (p>0.05). Considering all plant communities, the average value of Shannon-Wiener index was 1.58+/-0.075. There was a positive correlation between evenness index and species richness (pgrasshoppers species richness, and diversity of grasshoppers. According to the qualitative indices applied, the similitude between different grasshopper communities was higher than 60%. In general, the species that had a higher frequency of occurrence showed greater

  7. Vegetation in clear-cuts depends on previous land use: a century-old grassland legacy

    Science.gov (United States)

    Jonason, Dennis; Ibbe, Mathias; Milberg, Per; Tunér, Albert; Westerberg, Lars; Bergman, Karl-Olof

    2014-01-01

    Plant species richness in central and northern European seminatural grasslands is often more closely linked to past than present habitat configuration, which is indicative of an extinction debt. In this study, we investigate whether signs of historical grassland management can be found in clear-cuts after at least 80 years as coniferous production forest by comparing floras between clear-cuts with a history as meadow and as forest in the 1870s in Sweden. Study sites were selected using old land-use maps and data on present-day clear-cuts. Species traits reflecting high capacities for dispersal and persistence were used to explain any possible links between the plants and the historical land use. Clear-cuts that were formerly meadow had, on average, 36% higher species richness and 35% higher richness of grassland indicator species, as well as a larger overall seed mass and lower anemochory, compared to clear-cuts with history as forest. We suggest that the plants in former meadows never disappeared after afforestation but survived as remnant populations. Many contemporary forests in Sweden were managed as grasslands in the 1800s. As conservation of remaining grassland fragments will not be enough to reduce the existing extinction debts of the flora, these young forests offer opportunities for grassland restoration at large scales. Our study supports the concept of remnant populations and highlights the importance of considering historical land use for understanding the distribution of grassland plant species in fragmented landscapes, as well as for policy-making and conservation. PMID:25540690

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

    Science.gov (United States)

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

    2015-03-01

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

  9. Community-specific hydraulic conductance potential of soil water decomposed for two Alpine grasslands by small-scale lysimetry

    Science.gov (United States)

    Frenck, Georg; Leitinger, Georg; Obojes, Nikolaus; Hofmann, Magdalena; Newesely, Christian; Deutschmann, Mario; Tappeiner, Ulrike; Tasser, Erich

    2018-02-01

    For central Europe in addition to rising temperatures an increasing variability in precipitation is predicted. This will increase the probability of drought periods in the Alps, where water supply has been sufficient in most areas so far. For Alpine grasslands, community-specific imprints on drought responses are poorly analyzed so far due to the sufficient natural water supply. In a replicated mesocosm experiment we compared evapotranspiration (ET) and biomass productivity of two differently drought-adapted Alpine grassland communities during two artificial drought periods divided by extreme precipitation events using high-precision small lysimeters. The drought-adapted vegetation type showed a high potential to utilize even scarce water resources. This is combined with a low potential to translate atmospheric deficits into higher water conductance and a lower biomass production as those measured for the non-drought-adapted type. The non-drought-adapted type, in contrast, showed high water conductance potential and a strong increase in ET rates when environmental conditions became less constraining. With high rates even at dry conditions, this community appears not to be optimized to save water and might experience drought effects earlier and probably more strongly. As a result, the water use efficiency of the drought-adapted plant community is with 2.6 gDW kg-1 of water much higher than that of the non-drought-adapted plant community (0.16 gDW kg-1). In summary, the vegetation's reaction to two covarying gradients of potential evapotranspiration and soil water content revealed a clear difference in vegetation development and between water-saving and water-spending strategies regarding evapotranspiration.

  10. Reconnaissance Report Yolo Bypass, California

    Science.gov (United States)

    1992-03-01

    fluctuations are common in the palmate-bracted bird’s-beak. These oscillations may be a result of changes in pollination success, rainfall patterns...regulate vegetative growth through feeding activity and assist in pollination of many flowering plant species. Restrictions in geographic movement make...bur clover, storks bill, horseweed, wild lettuce , telegraph weed, and many other less common herbaceous species, Grassland is the common vegetation

  11. Conservation issues: California chaparral

    Science.gov (United States)

    Halsey, Richard W.; Keeley, Jon E.

    2016-01-01

    California chaparral, a sclerophyllous shrub-dominated plant community shaped by a Mediterranean-type climate and infrequent, high-intensity fire, is one of the most biodiverse and threatened habitats on Earth. Distinct forms of chaparral, distinguished by differing species composition, geography, and edaphic characteristics, can cover thousands of hectares with dense vegetation or be restricted to smaller communities identified by the presence of endemic species. To maintain the biodiversity of chaparral, protective land management actions will be required to mitigate the loss due to the impacts of human population growth, development, climate change, and increased fire frequencies.

  12. California quake assessed

    Science.gov (United States)

    Wuethrich, Bernice

    On January 17, at 4:31 A.M., a 6.6 magnitude earthquake hit the Los Angeles area, crippling much of the local infrastructure and claiming 51 lives. Members of the Southern California Earthquake Network, a consortium of scientists at universities and the United States Geological Survey (USGS), entered a controlled crisis mode. Network scientists, including David Wald, Susan Hough, Kerry Sieh, and a half dozen others went into the field to gather information on the earthquake, which apparently ruptured an unmapped fault.

  13. California Tiger Salamander Range - CWHR [ds588

    Data.gov (United States)

    California Natural Resource Agency — Vector datasets of CWHR range maps are one component of California Wildlife Habitat Relationships (CWHR), a comprehensive information system and predictive model for...

  14. Giant Reed Distribution - Northern California [ds333

    Data.gov (United States)

    California Natural Resource Agency — The Arundo Distribution layer is a compilation of Arundo donax observations in northern and central California, obtained from several sources, including Arundo...

  15. Herpetofauna Surveys, Northern California - 2010 [ds694

    Data.gov (United States)

    California Natural Resource Agency — We recorded all incidental herpetofauna encountered during visual encounter and dipnet surveys in northern California. Surveys took place from April 2, 2010 to...

  16. Application of a crop model forced with remote sensing data at high spatio-temporal resolution to estimate evaporation and yields of irrigated grasslands in the South Eastern France

    Science.gov (United States)

    Couralt, D.; Hadria, R.; Ruget, F.; Duchemin, B.; Hagolle, O.

    2009-09-01

    This study focused on the feasibility of using remote sensing data acquired at high spatial and temporal resolution (FORMOSAT-2 images(http://www.spotimage.fr/web/en/977--formosat-2-images.php) for crop monitoring at regional scale. The monitoring of agricultural practices such as grassland mowing and irrigation is essential to simulate accurately all processes related to crop system. This information is needed for example in crop simulation models to estimate production, water and fertilizer consumption and can thus serve to better understand the interactions between agriculture and climate. The analysis of these interactions is especially important in Mediterranean region where the effects of climate changes and crop management modifications are increasingly marked. In this context, an experiment was conducted in 2006 in Crau region in the South-Eastern France. In this area, permanent grassland represents 67 % of the usable agricultural area, and it is often used with irrigation (47 % of the permanent grassland). A time series of 36 FORMOSAT-2 images was acquired with a three days frequency from March to October 2006. Information concerning grassland mowing and irrigation was collected through a survey over 120 fields. The high FORMOSAT-2 revisit frequency allowed replicating the dynamics of Leaf Area index (LAI), and detecting to some extents cultural practices like vegetation cut. Simple automatic algorithms were developed to obtain daily values of LAI for each grasslands field linked with the main agricultural practices performed (cut and irrigation dates). This information was then used in a crop model called STICS (http://147.100.66.194/stics/) to estimate the spatial variability of evapotranspiration and drainage associated with the aerial biomass productions. Comparisons between simulated and observed yields gave satisfactory results. The great spatial variations of evapotranspiration were strongly related to the crop and water management. Such

  17. Experts Question California's Algebra Edict

    Science.gov (United States)

    Cavanagh, Sean

    2008-01-01

    Business leaders from important sectors of the American economy have been urging schools to set higher standards in math and science--and California officials, in mandating that 8th graders be tested in introductory algebra, have responded with one of the highest such standards in the land. Still, many California educators and school…

  18. Quantifying nitrous oxide emissions from Chinese grasslands with a process-based model

    Directory of Open Access Journals (Sweden)

    F. Zhang

    2010-06-01

    Full Text Available As one of the largest land cover types, grassland can potentially play an important role in the ecosystem services of natural resources in China. Nitrous oxide (N2O is a major greenhouse gas emitted from grasslands. Current N2O inventory at a regional or national level in China relies on the emission factor method, which is based on limited measurements. To improve the accuracy of the inventory by capturing the spatial variability of N2O emissions under the diverse climate, soil and management conditions across China, we adopted an approach by utilizing a process-based biogeochemical model, DeNitrification-DeComposition (DNDC, to quantify N2O emissions from Chinese grasslands. In the present study, DNDC was tested against datasets of N2O fluxes measured at eight grassland sites in China with encouraging results. The validated DNDC was then linked to a GIS database holding spatially differentiated information of climate, soil, vegetation and management at county-level for all the grasslands in the country. Daily weather data for 2000–2007 from 670 meteorological stations across the entire domain were employed to serve the simulations. The modelled results on a national scale showed a clear geographic pattern of N2O emissions. A high-emission strip showed up stretching from northeast to central China, which is consistent with the eastern boundary between the temperate grassland region and the major agricultural regions of China. The grasslands in the western mountain regions, however, emitted much less N2O. The regionally averaged rates of N2O emissions were 0.26, 0.14 and 0.38 kg nitrogen (N ha−1 y−1 for the temperate, montane and tropical/subtropical grasslands, respectively. The annual mean N2O emission from the total 337 million ha of grasslands in China was 76.5 ± 12.8 Gg N for the simulated years.

  19. A Satellite-Based Model for Simulating Ecosystem Respiration in the Tibetan and Inner Mongolian Grasslands

    Directory of Open Access Journals (Sweden)

    Rong Ge

    2018-01-01

    Full Text Available It is important to accurately evaluate ecosystem respiration (RE in the alpine grasslands of the Tibetan Plateau and the temperate grasslands of the Inner Mongolian Plateau, as it serves as a sensitivity indicator of regional and global carbon cycles. Here, we combined flux measurements taken between 2003 and 2013 from 16 grassland sites across northern China and the corresponding MODIS land surface temperature (LST, enhanced vegetation index (EVI, and land surface water index (LSWI to build a satellite-based model to estimate RE at a regional scale. First, the dependencies of both spatial and temporal variations of RE on these biotic and climatic factors were examined explicitly. We found that plant productivity and moisture, but not temperature, can best explain the spatial pattern of RE in northern China’s grasslands; while temperature plays a major role in regulating the temporal variability of RE in the alpine grasslands, and moisture is equally as important as temperature in the temperate grasslands. However, the moisture effect on RE and the explicit representation of spatial variation process are often lacking in most of the existing satellite-based RE models. On this basis, we developed a model by comprehensively considering moisture, temperature, and productivity effects on both temporal and spatial processes of RE, and then, we evaluated the model performance. Our results showed that the model well explained the observed RE in both the alpine (R2 = 0.79, RMSE = 0.77 g C m−2 day−1 and temperate grasslands (R2 = 0.75, RMSE = 0.60 g C m−2 day−1. The inclusion of the LSWI as the water-limiting factor substantially improved the model performance in arid and semi-arid ecosystems, and the spatialized basal respiration rate as an indicator for spatial variation largely determined the regional pattern of RE. Finally, the model accurately reproduced the seasonal and inter-annual variations and spatial variability of RE, and it avoided

  20. Changes in plant species richness induce functional shifts in soil nematode communities in experimental grassland.

    Directory of Open Access Journals (Sweden)

    Nico Eisenhauer

    Full Text Available Changes in plant diversity may induce distinct changes in soil food web structure and accompanying soil feedbacks to plants. However, knowledge of the long-term consequences of plant community simplification for soil animal food webs and functioning is scarce. Nematodes, the most abundant and diverse soil Metazoa, represent the complexity of soil food webs as they comprise all major trophic groups and allow calculation of a number of functional indices.We studied the functional composition of nematode communities three and five years after establishment of a grassland plant diversity experiment (Jena Experiment. In response to plant community simplification common nematode species disappeared and pronounced functional shifts in community structure occurred. The relevance of the fungal energy channel was higher in spring 2007 than in autumn 2005, particularly in species-rich plant assemblages. This resulted in a significant positive relationship between plant species richness and the ratio of fungal-to-bacterial feeders. Moreover, the density of predators increased significantly with plant diversity after five years, pointing to increased soil food web complexity in species-rich plant assemblages. Remarkably, in complex plant communities the nematode community shifted in favour of microbivores and predators, thereby reducing the relative abundance of plant feeders after five years.The results suggest that species-poor plant assemblages may suffer from nematode communities detrimental to plants, whereas species-rich plant assemblages support a higher proportion of microbivorous nematodes stimulating nutrient cycling and hence plant performance; i.e. effects of nematodes on plants may switch from negative to positive. Overall, food web complexity is likely to decrease in response to plant community simplification and results of this study suggest that this results mainly from the loss of common species which likely alter plant-nematode interactions.

  1. Subsurface earthworm casts can be important soil microsites specifically influencing the growth of grassland plants.

    Science.gov (United States)

    Zaller, Johann G; Wechselberger, Katharina F; Gorfer, Markus; Hann, Patrick; Frank, Thomas; Wanek, Wolfgang; Drapela, Thomas

    Earthworms (Annelida: Oligochaeta) deposit several tons per hectare of casts enriched in nutrients and/or arbuscular mycorrhizal fungi (AMF) and create a spatial and temporal soil heterogeneity that can play a role in structuring plant communities. However, while we begin to understand the role of surface casts, it is still unclear to what extent plants utilize subsurface casts. We conducted a greenhouse experiment using large mesocosms (volume 45 l) to test whether (1) soil microsites consisting of earthworm casts with or without AMF (four Glomus taxa) affect the biomass production of 11 grassland plant species comprising the three functional groups grasses, forbs, and legumes, (2) different ecological groups of earthworms (soil dwellers- Aporrectodea caliginosa vs. vertical burrowers- Lumbricus terrestris ) alter potential influences of soil microsites (i.e., four earthworms × two subsurface microsites × two AMF treatments). Soil microsites were artificially inserted in a 25-cm depth, and afterwards, plant species were sown in a regular pattern; the experiment ran for 6 months. Our results show that minute amounts of subsurface casts (0.89 g kg -1 soil) decreased the shoot and root production of forbs and legumes, but not that of grasses. The presence of earthworms reduced root biomass of grasses only. Our data also suggest that subsurface casts provide microsites from which root AMF colonization can start. Ecological groups of earthworms did not differ in their effects on plant production or AMF distribution. Taken together, these findings suggest that subsurface earthworm casts might play a role in structuring plant communities by specifically affecting the growth of certain functional groups of plants.

  2. No Significant Changes in Topsoil Carbon in the Grasslands of Northern China Between the 1980s and 2000s

    Science.gov (United States)

    Liu, S.; Yang, Y.; Shen, H.; Hu, H.; Zhao, X.; Li, H.; Liu, T.; Fang, J.

    2017-12-01

    The grasslands of northern China store a large amount of soil organic carbon (SOC), and the small changes in SOC stock could significantly affect the regional C cycle. However, recent estimates of SOC changes in this region are highly controversial. In this study, we examined and mapped the changes in the SOC density (SOCD) in the upper 30 cm of the grasslands of northern China between the 1980s and 2000s, using an improved approach that integrates field-based measurements into machine learning algorithms (artificial neural network and random forest). The random forest-generated SOCD averaged 5.55 kg C m-2 in the 1980s and 5.53 kg C m-2 in the 2000s. The change ranged between -0.17 and 0.22 kg C m-2 at the 95% confidence level, suggesting that the overall SOCD did not change significantly during the study period. However, the change in SOCD exhibited large regional variability. The topsoil of the Inner Mongolian grasslands experienced a significant C loss (4.86 vs. 4.33 kg C m-2), whereas that of the Xinjiang grasslands exhibited an accumulation of C (5.55 vs. 6.46 kg C m-2). In addition, the topsoil C in the Tibetan alpine grasslands remained relatively stable (6.12 vs. 6.06 kg C m-2). A comparison of different grassland types indicated that SOCD exhibited significant decreases in typical steppe, whereas showed increases in mountain meadow, and were stable in the remaining grasslands (alpine meadow, alpine steppe, mountain steppe and desert steppe). Climate variables were shown to be the main determines of the change of SOCD. Increases in precipitation could lead to SOC increase in temperate grasslands and SOC loss in alpine grasslands, while climate warming is likely to cause SOC loss in temperate grasslands. Overall, our study shows that northern grasslands in China remained a neutral SOC sink between the 1980s and 2000s.

  3. Chromium carcinogenicity: California strategies.

    Science.gov (United States)

    Alexeeff, G V; Satin, K; Painter, P; Zeise, L; Popejoy, C; Murchison, G

    1989-10-01

    Hexavalent chromium was identified by California as a toxic air contaminant (TAC) in January 1986. The California Department of Health Services (CDHS) concurred with the findings of the International Agency for Research on Cancer that there is sufficient evidence to demonstrate the carcinogenicity of chromium in both animals and humans. CDHS did not find any compelling evidence demonstrating the existence of a threshold with respect to chromium carcinogenesis. Experimental data was judged inadequate to assess potential human reproductive risks from ambient exposures. Other health effects were not expected to occur at ambient levels. The theoretically increased lifetime carcinogenic risk from a continuous lifetime exposure to hexavalent chromium fell within the range 12-146 cancer cases per nanogram hexavalent chromium per cubic meter of air per million people exposed, depending on the potency estimate used. The primary sources found to contribute significantly to the risk of exposure were chrome platers, chromic acid anodizing facilities and cooling towers utilizing hexavalent chromium as a corrosion inhibitor. Evaluation of genotoxicity data, animal studies and epidemiological studies indicates that further consideration should be given to the potential carcinogenicity of hexavalent chromium via the oral route.

  4. Biomass resources in California

    Energy Technology Data Exchange (ETDEWEB)

    Tiangco, V.M.; Sethi, P.S. [California Energy Commission, Sacramento, CA (United States)

    1993-12-31

    The biomass resources in California which have potential for energy conversion were assessed and characterized through the project funded by the California Energy Commission and the US Department of Energy`s Western Regional Biomass Energy Program (WRBEP). The results indicate that there is an abundance of biomass resources as yet untouched by the industry due to technical, economic, and environmental problems, and other barriers. These biomass resources include residues from field and seed crops, fruit and nut crops, vegetable crops, and nursery crops; food processing wastes; forest slash; energy crops; lumber mill waste; urban wood waste; urban yard waste; livestock manure; and chaparral. The estimated total potential of these biomass resource is approximately 47 million bone dry tons (BDT), which is equivalent to 780 billion MJ (740 trillion Btu). About 7 million BDT (132 billion MJ or 124 trillion Btu) of biomass residue was used for generating electricity by 66 direct combustion facilities with gross capacity of about 800 MW. This tonnage accounts for only about 15% of the total biomass resource potential identified in this study. The barriers interfering with the biomass utilization both in the on-site harvesting, collection, storage, handling, transportation, and conversion to energy are identified. The question whether these barriers present significant impact to biomass {open_quotes}availability{close_quotes} and {open_quotes}sustainability{close_quotes} remains to be answered.

  5. Copulation by California condors

    Science.gov (United States)

    Wilbur, S.R.; Borneman, J.C.

    1972-01-01

    Koford (Res. Rept. No. 3, Natl. Audubon Soc., 1953) observed sexual display among California Condors (Gymnogyps californianus) on more than 30 occasions, yet only once did he see what he thought was copulation. Some of the displays he watched were quite intricate, with considerable posturing and "male" aggression, but no such activity preceded this copulation. The birds sat several feet apart for over 1 hour, then one climbed onto the other's back, staying there 1/2 minute and flapping gently at the apparent moment of coition. Afterward they sat quietly 1/2 hour before flying away. This led Koford to state (p. 79) that "possibly in Gymnogyps copulation is not immediately preceded by display." We have records of 8 California Condor copulations, 5 of which are similar to that described above. The three other occasions began similarly, with the birds sitting quietly, but then the "male" displayed briefly before the "female" with wings half spread and head drooping forward. This elicited no apparent response, but the male immediately walked behind and mounted the female. The apparent moment of coition was accompanied by gentle wing flapping in all instances.

  6. biofuel development in California

    Directory of Open Access Journals (Sweden)

    Varaprasad Bandaru

    2015-07-01

    Full Text Available Biofuels are expected to play a major role in meeting California's long-term energy needs, but many factors influence the commercial viability of the various feedstock and production technology options. We developed a spatially explicit analytic framework that integrates models of plant growth, crop adoption, feedstock location, transportation logistics, economic impact, biorefinery costs and biorefinery energy use and emissions. We used this framework to assess the economic potential of hybrid poplar as a feedstock for jet fuel production in Northern California. Results suggest that the region has sufficient suitable croplands (2.3 million acres and nonarable lands (1.5 million acres for poplar cultivation to produce as much as 2.26 billion gallons of jet fuel annually. However, there are major obstacles to such large-scale production, including, on nonarable lands, low poplar yields and broad spatial distribution and, on croplands, competition with existing crops. We estimated the production cost of jet fuel to be $4.40 to $5.40 per gallon for poplar biomass grown on nonarable lands and $3.60 to $4.50 per gallon for biomass grown on irrigated cropland; the current market price is $2.12 per gallon. Improved poplar yields, use of supplementary feedstocks at the biorefinery and economic supports such as carbon credits could help to overcome these barriers.

  7. Evaporation from Pinus caribaea plantations on former grassland soils under maritime tropical conditions

    Science.gov (United States)

    Waterloo, M. J.; Bruijnzeel, L. A.; Vugts, H. F.; Rawaqa, T. T.

    1999-07-01

    Wet canopy and dry canopy evaporation from young and mature plantations of Pinus caribaea on former grassland soils under maritime tropical conditions in southwestern Viti Levu, Fiji, were determined using micrometeorological and hydrological techniques. Modeled annual evaporation totals (ET) of 1926 and 1717 mm were derived for the 6- and the 15-year-old stands, respectively. Transpiration made up 72% and 70% of annual ET, and modeled rainfall interception by the trees and litter layer was 20-22% and 8-9% in the young and the mature stands respectively. Monthly ET was related to forest leaf area index and was much higher than that for the kind of tall fire-climax Pennisetum polystachyon grassland replaced by the forests. Grassland reforestation resulted in a maximum decrease in annual water yield of 1180 mm on a plot basis, although it is argued that a reduction of (at least) 500-700 mm would be more realistic at the catchment scale. The impact of reforesting grassland on the water resources in southwest Viti Levu is enhanced by its location in a maritime, seasonal climate in the outer tropics, which favors a larger difference between annual forest and grassland evaporation totals than do equatorial regions.

  8. Grassland communities in the USA and expected trends associated with climate change

    Directory of Open Access Journals (Sweden)

    David Paul Belesky

    2016-06-01

    Full Text Available Grasslands, including managed grazinglands, represent one of the largest ecosystems on the planet. Managed grazinglands in particular tend to occupy marginal climatic and edaphic resource zones, thus exacerbating responses in net primary productivity relative to changes in system resources, including anthropogenic factors. Climate dynamism, as evident from the fossil record, appears to be a putative feature of our planet. Recent global trends in temperature and precipitation patterns seem to differ from long-term patterns and have been associated with human activities linked with increased greenhouse gas emissions; specifically CO2. Thus grasslands, with their diverse floristic components, and interaction with and dependence upon herbivores, have a remarkable ability to persist and sustain productivity in response to changing resource conditions. This resistance and resilience to change, including uncertain long-term weather conditions, establishes managed grasslands as an important means of protecting food security. We review responses of grassland communities across regions of the USA and consider the responses in productivity and system function with respect to climatic variation. Research is needed to identify plant resources and management technologies that strengthen our ability to capitalize upon physiological and anatomical features prevalent in grassland communities associated with varying growing conditions.

  9. FLORISTIC CHANGES ALONG THE TOPOGRAPHICAL GRADIENT IN MONTANE GRASSLANDS IN MONTI PICENTINI (CAMPANIA, SW ITALY

    Directory of Open Access Journals (Sweden)

    M. CUTINI

    2010-01-01

    Full Text Available Populations of xerotolerant species (Achnatherum calamagrostis, Stipa crassiculmis subsp. picentina, are scattered along a wide altitudinal gradient on slopes at mid- and high elevation in Monti Picentini, a subcoastal mesozoic limestone ridge in Tyrrhenian Southern Italy. Their stands are widespread in grasslands of mostly secondary origin. At lower altitudes these grasslands replace former deciduous forest communities dominated by oaks or beech, while at higher altitudes they reach the summits, where they apparently merge into the remnants of the still partially grazed, zonal climatogenic, grasslands ranging above the local tree-line. Nevertheless primary stands of these grasslands are to be found around the many clusters of highly dynamic sites of the montane and sub-alpine levels, scattered around screes and rocky outcrops of the prevalently dolomitic morphology of the slopes. This virtual continuity of non arboreal communities across more than 1000 metres of the local topographical gradient, where azonal, relic stands of Pinus nigra s.l. are transitional between the grasslands and the surrounding zonal broadleaved forest vegetation, stresses patterns of the coenological changes between Festuco-Brometea and Elyno-Seslerietea along the catena, which suggest fragmentary persistence of a paleozonation.

  10. FLORISTIC CHANGES ALONG THE TOPOGRAPHICAL GRADIENT IN MONTANE GRASSLANDS IN MONTI PICENTINI (CAMPANIA, SW ITALY

    Directory of Open Access Journals (Sweden)

    F. SPADA

    2010-04-01

    Full Text Available Populations of xerotolerant species (Achnatherum calamagrostis, Stipa crassiculmis subsp. picentina, are scattered along a wide altitudinal gradient on slopes at mid- and high elevation in Monti Picentini, a subcoastal mesozoic limestone ridge in Tyrrhenian Southern Italy. Their stands are widespread in grasslands of mostly secondary origin. At lower altitudes these grasslands replace former deciduous forest communities dominated by oaks or beech, while at higher altitudes they reach the summits, where they apparently merge into the remnants of the still partially grazed, zonal climatogenic, grasslands ranging above the local tree-line. Nevertheless primary stands of these grasslands are to be found around the many clusters of highly dynamic sites of the montane and sub-alpine levels, scattered around screes and rocky outcrops of the prevalently dolomitic morphology of the slopes. This virtual continuity of non arboreal communities across more than 1000 metres of the local topographical gradient, where azonal, relic stands of Pinus nigra s.l. are transitional between the grasslands and the surrounding zonal broadleaved forest vegetation, stresses patterns of the coenological changes between Festuco-Brometea and Elyno-Seslerietea along the catena, which suggest fragmentary persistence of a paleozonation.

  11. Breeding Biology of Grassland Birds in Western New York: Conservation and Management Implications

    Directory of Open Access Journals (Sweden)

    Christopher J. Norment

    2010-12-01

    Full Text Available Declining grassland breeding bird populations have led to increased efforts to assess habitat quality, typically by estimating density or relative abundance. Because some grassland habitats may function as ecological traps, a more appropriate metric for determining quality may be breeding success. Between 1994 and 2003 we gathered data on the nest fates of Eastern Meadowlarks (Sturnella magna, Bobolinks (Dolichonyx oryzivorous, and Savannah Sparrows (Passerculus sandwichensis in a series of fallow fields and pastures/hayfields in western New York State. We calculated daily survival probabilities using the Mayfield method, and used the logistic-exposure method to model effects of predictor variables on nest success. Nest survival probabilities were 0.464 for Eastern Meadowlarks (n = 26, 0.483 for Bobolinks (n = 91, and 0.585 for Savannah Sparrows (n = 152. Fledge dates for first clutches ranged between 14 June and 23 July. Only one obligate grassland bird nest was parasitized by Brown-headed Cowbirds (Molothrus ater, for an overall brood parasitism rate of 0.004. Logistic-exposure models indicated that daily nest survival probabilities were higher in pastures/hayfields than in fallow fields. Our results, and those from other studies in the Northeast, suggest that properly managed cool season grassland habitats in the region may not act as ecological traps, and that obligate grassland birds in the region may have greater nest survival probabilities, and lower rates of Brown-headed Cowbird parasitism, than in many parts of the Midwest.

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

    Science.gov (United States)

    Saintilan, Neil; Rogers, Kerrylee

    2015-02-01

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

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

    Science.gov (United States)

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

    2017-12-01

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

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

    Science.gov (United States)

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

    2018-06-01

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

  15. Floristic composition, environmental variation and species distribution patterns in burned grassland in southern Brazil.

    Science.gov (United States)

    Overbeck, G E; Müller, S C; Pillar, V D; Pfadenhauer, J

    2006-11-01

    In regularly burned grassland on Morro Santana, Porto Alegre, RS, Brazil, we investigated differences in the floristic composition and their relation to soil properties, aspect and distance from the forest border. In 48 plots of 0.75 m2, we identified a total of 201 species from a local species pool of approximately 450 to 500 species. Most species occurred in low frequencies, showing clumpy distribution patterns in the studied area. Multivariate analysis showed that plots close to the forest edge clearly differed from plots in the open grassland concerning composition and structure. Plots exposed to the north differed from plots on the top of the hill both in the composition of species as well as in soil variables, mainly due to shallower soil in the former. No strong relation between soil properties and variation in vegetation composition could be detected at a finer scale. The studied grassland, as all grassland vegetation in southern Brazil, is very rich in species compared to other grassland formations worldwide. However, this high biodiversity and conservational value of Campos vegetation in general has so far not been recognized properly. Disturbance is essential to maintain this open vegetation type and its species richness. Fire should be considered as a management option in the absence of grazing.

  16. Habitat fragmentation effects on birds in grasslands and wetlands: A critique of our knowledge

    Science.gov (United States)

    Johnson, D.H.

    2001-01-01

    Habitat fragmentation exacerbates the problem of habitat loss for grassland and wetland birds. Remaining patches of grasslands and wetlands may be too small, too isolated, and too influenced by edge effects to maintain viable populations of some breeding birds. Knowledge of the effects of fragmentation on bird populations is critically important for decisions about reserve design, grassland and wetland management, and implementation of cropland set-aside programs that benefit wildlife. In my review of research that has been conducted on habitat fragmentation, I found at least five common problems in the methodology used. The results of many studies are compromised by these problems: passive sampling (sampling larger areas in larger patches), confounding effects of habitat heterogeneity, consequences of inappropriate pooling of data from different species, artifacts associated with artificial nest data, and definition of actual habitat patches. As expected, some large-bodied birds with large territorial requirements, such as the northern harrier (Circus cyaneus), appear area sensitive. In addition, some small species of grassland birds favor patches of habitat far in excess of their territory size, including the Savannah (Passerculus sandwichensis), grasshopper (Ammodramus savannarum) and Henslow's (A. henslowii) sparrows, and the bobolink (Dolichonyx oryzivorus). Other species may be area sensitive as well, but the data are ambiguous. Area sensitivity among wetland birds remains unknown since virtually no studies have been based on solid methodologies. We need further research on grassland bird response to habitat that distinguishes supportable conclusions from those that may be artifactual.

  17. DIVERSITY OF PLANT COMMUNITIES IN SECONDARY SUCCESSION OF IMPERATA GRASSLANDS IN SAMBOJA LESTARI, EAST KALIMANTAN, INDONESIA

    Directory of Open Access Journals (Sweden)

    Ishak Yassir

    2016-06-01

    Full Text Available Regeneration of  Imperata grassland areas is becoming increasingly important, both to create new secondary forest and to recover the original biodiversity. The diversity of  plant communities in secondary succession of  Imperata grasslands was studied using 45 subplots of  9 linear transects (10 m x 100 m. Data was collected and all stems over 10 cm dbh were identified, the Importance Values Index (IVI for all trees were calculated, saplings and seedlings were counted  and analysed, and soil samples were taken and analysed. Results showed that  after more than 10 years of  regeneration, 65 families were encountered consisting of  164 species, which were dominated by Vernonia arborea Buch.-Ham, Vitex pinnata L., Macaranga gigantea (Reichb.f. & Zoll. Muell.Arg., Symplocos crassipes C.B. Clarke, Artocarpus odoratissimus Miq., and Bridelia glauca Blume. The effects of  regeneration, from Imperata grassland to secondary forest, on soil were the strongest in the A-horizon where an increase in carbon, N content, and pH were observed. Our result shows that Imperata grasslands appear to be permanent because of  frequent fires and human interferences and so far few efforts have been made to promote sustainable rehabilitation. If  protected from fire and other disturbances, such as shifting cultivation, Imperata grassland will grow and develop into secondary forest.

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

    Science.gov (United States)

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

    2010-01-01

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

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

    Science.gov (United States)

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

    2018-04-01

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

  20. Non-destructive soil amendment application techniques on heavy metal-contaminated grassland: Success and long-term immobilising efficiency.

    Science.gov (United States)

    Friesl-Hanl, Wolfgang; Platzer, Klaus; Riesing, Johann; Horak, Othmar; Waldner, Georg; Watzinger, Andrea; Gerzabek, Martin H

    2017-01-15

    Extensive contamination of grassland with cadmium (Cd), lead (Pb) and zinc (Zn) is a typical problem close to Pb/Zn smelter sites. The entry of Cd or Pb into the food chain is very likely, as are toxicity effects of Zn in plants. Previous promising results from pot and field experiments showed the high potential of using amendments for immobilisation to reduce metal input into the food chain via crops grown on smelter-contaminated soils at Arnoldstein (Austria) (Friesl et al., 2006). The aim of this study was to find a practical solution for large-scale contaminations in hilly regions that avoids erosion. Field application of amendments without destroying the vegetation cover (grassland) involved two approaches: (a) slurrying (Slu) the amendments into cut gaps in the vegetation cover and (b) injecting (Inj) the amendments through the vegetation cover. Here, we investigate the immobilising and long-term efficiency of treatments [gravel sludge (2.5%) + red mud (0.5%) (GS + RM)]. Risk assessment was based on soil, plant and water samples taken over a period of 10 years. Ammonium-nitrate-extractable Cd was reduced up to 50%, Pb up to 90%, and Zn over 90%. Plant uptake into the grass mixture and narrow leaf plantain was significantly reduced for Cd, Pb, and Zn. Harvesting early in vegetation period can further reduce uptake and meet the threshold for fodder crops. The reduction of these elements in the seepage water in 24 samplings within these 10 years reached 40%, 45% and 50%, respectively. Immobilisation increased microbial biomass and decreased human bioaccessibility for Pb. Our investigation of the long-term efficiency of GS + RM in all treatments shows that the Slu and Inj amendment application techniques have promising potential as a realistic and practical method for extensively contaminated hilly land. Slurrying performed best. We conclude that grassland remediation methods involving tillage are counterproductive from the viewpoint of bioaccessibility