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Sample records for california grassland experiment

  1. 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.

  2. 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.

  3. Selenium contamination of the Grasslands, a major California waterfowl area

    Science.gov (United States)

    Ohlendorf, H.M.; Hothem, R.L.; Aldrich, T.W.; Krynitsky, A.J.

    1987-01-01

    In a recent study at Kesterson Reservoir in California, selenium was shown to cause mortality and deformities in embryos of aquatic birds. The present study was conducted to determine if selenium or other contaminants in agricultural drainwater used for marsh management were likely to cause similar adverse effects in the nearby Grasslands area. Selenium concentrations were elevated (greater than 15 ppm, dry-weight) in livers of some birds of all species collected from the Grasslands. Mean selenium concentrations in all species sampled in the South Grasslands were significantly higher (P less than 0.05) than those from the 'control site', the Volta Wildlife Area. Mean selenium levels in black-necked stilts (Himantopus mexicanus) from the South Grasslands (35.6 ppm) were similar (P greater than 0.05) to levels in stilts from Kesterson (46.4 ppm), but means for American avocets (Recurvirostra americana) from the South Grasslands (67.3 ppm) were higher (P less than 0.05) than those from Kesterson (28.4 ppm). Bird eggs and fish from the Grasslands also contained elevated levels of selenium. Concentrations of eight heavy metals in fish generally reflected those patterns previously found in water entering the study areas. Of the organochlorines detected in fish, only DDE occurred at concentrations potentially harmful to birds (6.1 and 3.0 ppm, wet weight, at two South Grassland sites). The effect on avian health or reproduction of the other contaminants, singly or in combination, could not be determined. However, selenium levels were apparently sufficiently elevated in 1984 to have caused adverse effects on avian reproduction in the South Grasslands.

  4. Fire And Dynamics Of Granivory On A California Grasslands Forb

    Energy Technology Data Exchange (ETDEWEB)

    Espeland, E; Carlsen, T; Macqueen, D

    2003-10-02

    This study examines the effects of burning and granivory on the reproductive success of the rare plant Amsinckia grandiflora (Boraginaceae). Fire is often used in California grasslands as a means of exotic species control, but the indirect effects of these controls on the reproductive ecology of a native plants are rarely assessed. The interaction of fire with granivory of A. grandiflora seeds was examined in California grasslands over five years (1998-2002). In 1998 and 1999, both burned and unburned plots had bird-exclusion (netted) and no-exclusion (open) treatments. Predation rates were high (51-99%) and final predation rates did not differ among treatments. In 2000, granivory rates in the unburned, open plots were lower than in previous years (14%), and rodent trapping yielded only a single animal. Low granivory rates were observed in 2001 for unburned, open plots (47%). In 2001, burned/open plots experienced significantly more granivory (87%) than either burned/netted plots (37%) or unburned/open plots (47%). In 2002, every seed was taken from burned, open plots. Granivory was highly variable, ranging from 4% to 100% per plot over a three-week period. Nearly all plots were discovered (>10% predation) by granivores in all trials in all years. When data from all treatments were combined, significant differences in granivory rates occurred among years, indicating stronger inter-year effects than within-year effects due to burning or bird exclusion. Fire affects granivory when overall predation rates are low, but when predation levels are high (as they were in 1998 and 1999), fire may not affect granivory occurring within the same year. Models extending seed survivorship through the dry summer indicate that most seeds are eaten, even when granivory rates are low.

  5. 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.

  6. Drought Experiment of a Mongolian Grassland Ecosystem

    Science.gov (United States)

    Shinoda, M.; Tsunekawa, A.; Nemoto, M.; Nachinshonhor, G. U.; Nakano, T.; Tamura, K.; Asano, M.; Erdenetsetseg, D.

    2006-12-01

    Recent large-scale climate change including global warming has likely been manifested as frequent and/or intensive drought occurrences in inland, arid Asia such as Mongolia. In order to investigate the response of a Mongolian grassland ecosystem to such a drought, an artificial drought experiment was conducted at Bayan Unjuul (105.95E, 47.04N) in the Mongolian typical steppe region during the growing season of 2005. The climatological (1995-2004) annul precipitation is 172.9mm, concentrated on the summer months of May- August, while the annual mean temperature is 0.1degC, with soil freezing during the winter. This study site is codominated by perennial grasses such as Stipa krylovii, Agropyron cristatum, and Cleistogenes squarrosa and annual forbs such as Artemisia adamsii and Chenopodium album. An area of 300m w300m in size was surrounded by a fence for protecting this area from grazing. The plots inside and outside of the area are referred to as no-grazing (NG) and grazing (G) plots, respectively. In the NG plot, two plots of 30m w30m with drought (D plot) and mowing (M plot) manipulations are allocated in the southwest part of the NG plot. The drought manipulation was conducted using a rainout shelter with a transparent polyethylene roof, open on all sides during the major growing season from late May to early August 2005. The total precipitation of 60.3mm in the annual total of 96.9mm (that is, a severe drought year) was excluded from the D plot. Thus, natural severe drought and artificial very severe drought conditions were produced in this year. To study the vegetation impact on thermal and moisture conditions at the ground surface, the mowing has been carried out on a monthly basis during the growing season. The initial conditions for each plot were examined during the late growing seasons of 2003 and 2004, showing no significant difference in terms of vegetation (above-/below-ground biomass and species diversity) and physical and chemical soil properties

  7. Conversion of chaparral areas to grassland techniques used in California

    Science.gov (United States)

    Jay R. Bentley

    1967-01-01

    Chaparral-as the term is used in California-refers to dense stands of evergreen, shrubby vegetation. The information in this handbook applies to the chaparral within the brushland zone that lies below the State's commercial timber belt (fig. 1). This zone includes about 11 million acres of chaparral and associated types and 9 million acres of woodland types.

  8. Contaminants in eggs of aquatic birds from the grasslands of central California

    Science.gov (United States)

    Hothem, R.L.; Welsh, D.

    1994-01-01

    Eggs were collected from the Grasslands of western Merced County, California, during 1986 and 1987, and at the Mendota Wildlife Area in Fresno County in 1987, as part of a reproductive study of nesting ducks and shorebirds. The eggs were analyzed to evaluate the effects of contaminants in agricultural drainwater on avian reproduction. Agricultural drainwater was the major source of water for irrigation and fall flooding in the Grasslands until the fall of 1985 when drainwater was mostly replaced by uncontaminated water. Drainwater had not been used at Mendota. Concentrations of arsenic and boron in eggs from all sites were lower than those known to harm avian reproduction. However, mean concentrations of selenium, a trace element known to impair avian reproduction at high dietary levels, were higher in eggs from the Grasslands than in eggs from the uncontaminated site. Although some selenium concentrations were as high as those found to have caused death or deformities at other sites, reproductive impairment was not observed in any ducks or shorebirds nesting in the Grasslands in 1986 or 1987.

  9. 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

  10. 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

  11. 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.

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

    Directory of Open Access Journals (Sweden)

    Claudia Stein

    Full Text Available 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.

  13. Ecosystem impacts of compost and manure applications to California grazed grassland soils

    Science.gov (United States)

    DeLonge, M. S.; Silver, W. L.

    2012-12-01

    Organic matter amendments, such as compost and manure, are often applied to grasslands to improve soil conditions and enhance net primary productivity. It has been proposed that this land management strategy can sequester carbon (C) in soils and may therefore contribute to climate change mitigation. However, the net mitigation potential of organic amendments depends in part on the ecosystem response following land-application, which is likely to vary with the amendment chemical quality (C, N, C:N). To investigate the differences in ecosystem response to soil amendments of various qualities, we established research plots on three grazed annual grasslands in northern California. The study sites were sampled for soil chemical and physical properties (bulk density, temperature, and moisture), plant community composition, and peak season net primary productivity prior to and following treatment applications. In October 2011, before the rainy season, we applied a thin layer of organic amendments to the study plots. At each site, three replicate plots were treated with fresh manure (1.2 % N, 15.8 % C, C:N = 13.5), three plots were treated with a commercial plant-waste compost (2.4 % N, 26.6 % C, C:N = 11.1), and three plots were left untreated as controls. At one site, 3 additional plots received a thin layer of compost with a lower N concentration and a higher C:N ratio (1.9 % N, 27.4 % C, C:N = 14.5). All plots were sampled for greenhouse gas emissions (N2O, CH4, and CO2, n=3 per plot) using vented chambers shortly after the organic matter was applied, and then intensively following three rain events throughout the rainy season. Results showed that dry amendments were associated with negligible trace gas fluxes, but that these fluxes increased after rain events. Nitrous oxide emissions increased slightly after the first rain event and reached peak levels (approximately 20 ng N cm-1 h-1 for the manure and high N compost only) after three days, following second rain event

  14. Soil Organic Carbon Redistribution by Geomorphic Processes in an Undisturbed Zero Order Annual Grassland Watershed, California

    Science.gov (United States)

    Yoo, K.; Amundson, R.; Heimsath, A. M.; Dietrich, W. E.

    2001-12-01

    Despite the crucial role of soils in global carbon cycle, the sizes of soil organic carbon (SOC) pools and relevant fluxes are still in debate. We studied the extent which topography regulates SOC pools and fluxes through geomorphic processes (erosion, deposition, and episodic hollow evacuation) in an undisturbed zero order annual grassland watershed of Tennessee Valley California (site area: 100mx70m, MAP:760mm, MAT:16° C). We systematically measured soil thickness, bulk density, texture, carbon and nitrogen content to the depth of bedrock contact for 69 soil pits (and plant C inputs at 44 aboveground 25x25 cm quadrats) along diverging slopes (average slope: 28%) and in the adjacent hollow. We performed a high resolution (map and calculate the 2 dimensional slope curvature using Kriging method. Over the diverging slope, in general, soil thickness (5 to 92cm) and SOC storage (3.8 to 17.0 kgC/m2) tend to increase downslope despite their significant variations with local topographic curvature. Hollow soils are thicker (71 to 270cm) and have higher SOC storage (17.5 to 28.6 kgC/m2). However aboveground plant C inputs in the upper hollow (75 to 187 gC/m2/yr) were not higher than those of diverging slope (42 to 336 gC/m2/yr), suggesting the importance of the burial and reduced decomposition rate of SOC eroded from adjacent slopes. By combining a diffusion soil transport law (which is a function of topographic curvature and soil thickness) and a carbon decomposition model, we determined the rate of SOC erosion losses from divergent slopes and reconstructed SOC storage in the hollow over time scale of 10k years. This empirically constrained model provides the mechanistic explanation of the observed topographic pattern of SOC storage.

  15. Methane-Oxidizing Bacteria in a California Upland Grassland Soil: Diversity and Response to Simulated Global Change

    OpenAIRE

    Horz, Hans-Peter; Rich, Virginia; Avrahami, Sharon; Bohannan, Brendan J. M.

    2005-01-01

    We investigated the diversity of methane-oxidizing bacteria (i.e., methanotrophs) in an annual upland grassland in northern California, using comparative sequence analysis of the pmoA gene. In addition to identifying type II methanotrophs commonly found in soils, we discovered three novel pmoA lineages for which no cultivated members have been previously reported. These novel pmoA clades clustered together either with clone sequences related to “RA 14” or “WB5FH-A,” which both represent clust...

  16. Influences of the vegetation mosaic on riparian and stream environments in a mixed forest-grassland landscape in "Mediterranean" northwestern California

    Science.gov (United States)

    Hartwell H Welsh Jr; Garth R. Hodgson; Nancy E. Karraker

    2005-01-01

    We examined differences in riparian and aquatic environments within the three dominant vegetation patch types of the Mattole River watershed, a 789-km2 mixed conifer-deciduous (hardwood) forest and grassland-dominated landscape in northwestern California, USA. Riparian and aquatic environments, and particularly microclimates therein, influence...

  17. 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

  18. Response of soil carbon dioxide efflux to fire disturbance in a long-term grassland global change experiment

    Science.gov (United States)

    Strong, A. L.; Chiariello, N.; Tobeck, T.; Field, C. B.

    2012-12-01

    How terrestrial biosphere-atmosphere carbon dioxide exchange responds to global change is an important component to understanding global feedbacks of the carbon cycle. Soils represent a global store of organic carbon on the order of 3000 Pg C. Increased carbon dioxide release from increased respiration of soil C in response to climate warming and other direct and indirect anthropogenic factors could create a positive carbon cycle feedback to climate change. Numerous studies have demonstrated that soil respiration increases under experimental warming and elevated CO2, although the long-term, multi-year dynamics of this feedback remain poorly constrained. Punctuated disturbances, such as fire, are also likely to affect soil C responses, and understanding how fire and other global change factors interact in their influence on soil respiration is important in order to fully characterize climate-carbon cycle feedbacks. Previous studies have found that fire disturbance in semi-arid grasslands reduces soil CO2. The Jasper Ridge Global Change Experiment is a thirteen-year continuous full-factorial global change manipulation (elevated carbon dioxide, temperature, precipitation, and nitrogen deposition) located in a clay-loam soil grassland in central coastal California. In summer 2011, an additional treatment condition -- a controlled burn -- was applied to half the experimental plots to provide a fire treatment, and in the following growing season, soil carbon dioxide effluxes were measured at peak aboveground plant biomass (April 2012) and after summer senescence (June 2012) using a LiCOR-6400 soil respiration chamber and infrared gas analyzer. Across all plots and other treatments, CO2 fluxes were greater in burned grassland soils than in non-burned grassland soils (p 0.10). Neither soil temperature, nor soil moisture appeared to be correlated with soil CO2 efflux (p > 0.10). By June 2012, after senescence and dry-out, all soil CO2 effluxes were lower than in April, and

  19. Usefulness of LANDSAT data for monitoring plant development and range conditions in California's annual grassland

    Science.gov (United States)

    Carneggie, D. M.; Degloria, S. D.; Colwell, R. N.

    1977-01-01

    A network of sampling sites throughout the annual grassland region was established to correlate plant growth in stages and forage production to climatic and other environmental factors. Plant growth and range conditions were further related to geographic location and seasonal variations. A sequence of LANDSAT data was obtained covering critical periods in the growth cycle. Data were analyzed by both photointerpretation and computer aided techniques. Image characteristics and spectral reflectance data were then related to forage production, range condition, range site, and changing growth conditions.

  20. 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.

  1. 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.

  2. Composition of soil seed banks in southern California coastal sage scrub and adjacent exotic grassland

    Science.gov (United States)

    Robert D. Cox; Edith B. Allen

    2008-01-01

    Soil seed banks are important to many plant communities and are recognized as an important component of management plans. Understanding seed bank composition and density is especially important when communities have been invaded by exotic species and must be managed to promote desirable species. We examined germinable soil seed banks in southern California coastal sage...

  3. Methane-oxidizing bacteria in a California upland grassland soil: diversity and response to simulated global change.

    Science.gov (United States)

    Horz, Hans-Peter; Rich, Virginia; Avrahami, Sharon; Bohannan, Brendan J M

    2005-05-01

    We investigated the diversity of methane-oxidizing bacteria (i.e., methanotrophs) in an annual upland grassland in northern California, using comparative sequence analysis of the pmoA gene. In addition to identifying type II methanotrophs commonly found in soils, we discovered three novel pmoA lineages for which no cultivated members have been previously reported. These novel pmoA clades clustered together either with clone sequences related to "RA 14" or "WB5FH-A," which both represent clusters of environmentally retrieved sequences of putative atmospheric methane oxidizers. Conservation of amino acid residues and rates of nonsynonymous versus synonymous nucleotide substitution in these novel lineages suggests that the pmoA genes in these clades code for functionally active methane monooxygenases. The novel clades responded to simulated global changes differently than the type II methanotrophs. We observed that the relative abundance of type II methanotrophs declined in response to increased precipitation and increased atmospheric temperature, with a significant antagonistic interaction between these factors such that the effect of both together was less than that expected from their individual effects. Two of the novel clades were not observed to respond significantly to these environmental changes, while one of the novel clades had an opposite response, increasing in relative abundance in response to increased precipitation and atmospheric temperature, with a significant antagonistic interaction between these factors.

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

    Science.gov (United States)

    Ward, David; Kirkman, Kevin; Tsvuura, Zivanai

    2017-01-01

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

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

    Science.gov (United States)

    Kirkman, Kevin; Tsvuura, Zivanai

    2017-01-01

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

  6. 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

  7. Spatial heterogeneity confounded ozone-exposure experiment in semi-natural grassland.

    Science.gov (United States)

    Stampfli, Andreas; Fuhrer, Jürg

    2010-02-01

    Interpretation of observations from manipulative experiments is often complicated by a multitude of uncontrolled processes operating at various spatial and temporal scales. As such processes may differ among experimental plots there is a risk that effects of experimental treatments are confounded. Here we report on a free-air ozone-exposure experiment in permanent semi-natural grassland that suggested strong ozone effects on community productivity after 5 years. We tested ozone effects and investigated the potential of confounding due to changes in nutrient management. Repeated-measure ANOVA revealed mainly negative temporal trends for frequency of abundant productive plant species. Constrained ordination additionally showed converging trajectories of species compositions for ozone and control treatments with time. Yields sampled prior to the start of the experiment and soil nitrogen concentrations revealed that spatial heterogeneity in the soil nutrient status was not accounted for by the random allocation of treatments to plots with a bias towards less productive patches in the elevated-ozone plots. Re-analysis of yield data using repeated-measure ANOVA with a covariable to account for productivity prior to the start of fumigation revealed effects on the temporal changes in total yield and yield of legumes that cannot be separated between ozone and pre-treatment nutrient status. Changes in species composition favour an ecological interpretation with spatial heterogeneity as the major cause of different yield declines. Although elevated ozone may cause subtle physiological changes with longer term implications, our new results suggest that species-rich mature grassland such as the one studied at Le Mouret may be less sensitive to elevated ozone than previously assumed. In this experiment a confounded design was hidden at the start by transitory effects of a prior change in nutrient treatments.

  8. 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

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

    Science.gov (United States)

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

    2013-01-01

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

  10. Testing the link between functional diversity and ecosystem functioning in a Minnesota grassland experiment.

    Science.gov (United States)

    Clark, Christopher M; Flynn, Dan F B; Butterfield, Bradley J; Reich, Peter B

    2012-01-01

    The functional diversity of a community can influence ecosystem functioning and reflects assembly processes. The large number of disparate metrics used to quantify functional diversity reflects the range of attributes underlying this concept, generally summarized as functional richness, functional evenness, and functional divergence. However, in practice, we know very little about which attributes drive which ecosystem functions, due to a lack of field-based tests. Here we test the association between eight leading functional diversity metrics (Rao's Q, FD, FDis, FEve, FDiv, convex hull volume, and species and functional group richness) that emphasize different attributes of functional diversity, plus 11 extensions of these existing metrics that incorporate heterogeneous species abundances and trait variation. We assess the relationships among these metrics and compare their performances for predicting three key ecosystem functions (above- and belowground biomass and light capture) within a long-term grassland biodiversity experiment. Many metrics were highly correlated, although unique information was captured in FEve, FDiv, and dendrogram-based measures (FD) that were adjusted by abundance. FD adjusted by abundance outperformed all other metrics in predicting both above- and belowground biomass, although several others also performed well (e.g. Rao's Q, FDis, FDiv). More generally, trait-based richness metrics and hybrid metrics incorporating multiple diversity attributes outperformed evenness metrics and single-attribute metrics, results that were not changed when combinations of metrics were explored. For light capture, species richness alone was the best predictor, suggesting that traits for canopy architecture would be necessary to improve predictions. Our study provides a comprehensive test linking different attributes of functional diversity with ecosystem function for a grassland system.

  11. Testing the Link between Functional Diversity and Ecosystem Functioning in a Minnesota Grassland Experiment

    Science.gov (United States)

    Butterfield, Bradley J.; Reich, Peter B.

    2012-01-01

    The functional diversity of a community can influence ecosystem functioning and reflects assembly processes. The large number of disparate metrics used to quantify functional diversity reflects the range of attributes underlying this concept, generally summarized as functional richness, functional evenness, and functional divergence. However, in practice, we know very little about which attributes drive which ecosystem functions, due to a lack of field-based tests. Here we test the association between eight leading functional diversity metrics (Rao’s Q, FD, FDis, FEve, FDiv, convex hull volume, and species and functional group richness) that emphasize different attributes of functional diversity, plus 11 extensions of these existing metrics that incorporate heterogeneous species abundances and trait variation. We assess the relationships among these metrics and compare their performances for predicting three key ecosystem functions (above- and belowground biomass and light capture) within a long-term grassland biodiversity experiment. Many metrics were highly correlated, although unique information was captured in FEve, FDiv, and dendrogram-based measures (FD) that were adjusted by abundance. FD adjusted by abundance outperformed all other metrics in predicting both above- and belowground biomass, although several others also performed well (e.g. Rao’s Q, FDis, FDiv). More generally, trait-based richness metrics and hybrid metrics incorporating multiple diversity attributes outperformed evenness metrics and single-attribute metrics, results that were not changed when combinations of metrics were explored. For light capture, species richness alone was the best predictor, suggesting that traits for canopy architecture would be necessary to improve predictions. Our study provides a comprehensive test linking different attributes of functional diversity with ecosystem function for a grassland system. PMID:23300787

  12. Testing the link between functional diversity and ecosystem functioning in a Minnesota grassland experiment.

    Directory of Open Access Journals (Sweden)

    Christopher M Clark

    Full Text Available The functional diversity of a community can influence ecosystem functioning and reflects assembly processes. The large number of disparate metrics used to quantify functional diversity reflects the range of attributes underlying this concept, generally summarized as functional richness, functional evenness, and functional divergence. However, in practice, we know very little about which attributes drive which ecosystem functions, due to a lack of field-based tests. Here we test the association between eight leading functional diversity metrics (Rao's Q, FD, FDis, FEve, FDiv, convex hull volume, and species and functional group richness that emphasize different attributes of functional diversity, plus 11 extensions of these existing metrics that incorporate heterogeneous species abundances and trait variation. We assess the relationships among these metrics and compare their performances for predicting three key ecosystem functions (above- and belowground biomass and light capture within a long-term grassland biodiversity experiment. Many metrics were highly correlated, although unique information was captured in FEve, FDiv, and dendrogram-based measures (FD that were adjusted by abundance. FD adjusted by abundance outperformed all other metrics in predicting both above- and belowground biomass, although several others also performed well (e.g. Rao's Q, FDis, FDiv. More generally, trait-based richness metrics and hybrid metrics incorporating multiple diversity attributes outperformed evenness metrics and single-attribute metrics, results that were not changed when combinations of metrics were explored. For light capture, species richness alone was the best predictor, suggesting that traits for canopy architecture would be necessary to improve predictions. Our study provides a comprehensive test linking different attributes of functional diversity with ecosystem function for a grassland system.

  13. BUGS in the analysis of biodiversity experiments: species richness and composition are of similar importance for grassland productivity.

    Directory of Open Access Journals (Sweden)

    Andy Hector

    Full Text Available The idea that species diversity can influence ecosystem functioning has been controversial and its importance relative to compositional effects hotly debated. Unfortunately, assessing the relative importance of different explanatory variables in complex linear models is not simple. In this paper we assess the relative importance of species richness and species composition in a multilevel model analysis of net aboveground biomass production in grassland biodiversity experiments by estimating variance components for all explanatory variables. We compare the variance components using a recently introduced graphical Bayesian ANOVA. We show that while the use of test statistics and the R² gives contradictory assessments, the variance components analysis reveals that species richness and composition are of roughly similar importance for primary productivity in grassland biodiversity experiments.

  14. Separating drought effects from roof artifacts on ecosystem processes in a grassland drought experiment.

    Science.gov (United States)

    Vogel, Anja; Fester, Thomas; Eisenhauer, Nico; Scherer-Lorenzen, Michael; Schmid, Bernhard; Weisser, Wolfgang W; Weigelt, Alexandra

    2013-01-01

    1: Given the predictions of increased drought probabilities under various climate change scenarios, there have been numerous experimental field studies simulating drought using transparent roofs in different ecosystems and regions. Such roofs may, however, have unknown side effects, called artifacts, on the measured variables potentially confounding the experimental results. A roofed control allows the quantification of potential artifacts, which is lacking in most experiments. 2: We conducted a drought experiment in experimental grasslands to study artifacts of transparent roofs and the resulting effects of artifacts on ecosystems relative to drought on three response variables (aboveground biomass, litter decomposition and plant metabolite profiles). We established three drought treatments, using (1) transparent roofs to exclude rainfall, (2) an unroofed control treatment receiving natural rainfall and (3) a roofed control, nested in the drought treatment but with rain water reapplied according to ambient conditions. 3: Roofs had a slight impact on air (+0.14°C during night) and soil temperatures (-0.45°C on warm days, +0.25°C on cold nights), while photosynthetically active radiation was decreased significantly (-16%). Aboveground plant community biomass was reduced in the drought treatment (-41%), but there was no significant difference between the roofed and unroofed control, i.e., there were no measurable roof artifact effects. 4: Compared to the unroofed control, litter decomposition was decreased significantly both in the drought treatment (-26%) and in the roofed control treatment (-18%), suggesting artifact effects of the transparent roofs. Moreover, aboveground metabolite profiles in the model plant species Medicago x varia were different from the unroofed control in both the drought and roofed control treatments, and roof artifact effects were of comparable magnitude as drought effects. 5: Our results stress the need for roofed control treatments

  15. 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

  16. Separating drought effects from roof artefacts on ecosystem processes in a grassland drought experiment

    Science.gov (United States)

    Vogel, Anja; Fester, Thomas; Eisenhauer, Nico; Scherer-Lorenzen, Michael; Schmid, Bernhard; Weisser, Wolfgang W.; Weigelt, Alexandra

    2013-04-01

    Given the predictions of increasing risk of long drought periods under various climate change scenarios, there have been numerous experimental field studies simulating drought using transparent roofs in different ecosystems and regions. Such roofs may, however, have unknown side effects, here called artefacts, on the response variables potentially confounding experimental results and misleading conclusions. Knowing the ecosystem response to such roof artefacts is therefore indispensible to correctly predict the effects of drought on the composition and functioning of ecosystems. We therefore aimed at filling this gap by studying the relevance of roof artefacts in a temperate grassland ecosystem. We compared pure drought effects to roof artefacts by measuring the response of three ecosystem properties (aboveground biomass, litter decomposition and plant metabolite profiles). We realized three treatments: a drought treatment simulated by means of transparent roofs, an unroofed control treatment receiving natural rainfall and a roofed control, with rain water applied according to ambient conditions. The roof constructions in our experiment caused a slight change in air (+0.14 °C during night) and soil (-0.45°C on warm days, +0.25 °C on cold nights) temperatures while photosynthetically active radiation was decreased (-16%) on bright days. Aboveground plant community biomass was reduced in the drought treatment (-41%), but there was no significant difference between the roofed and unroofed control, thus there was no measurable response of aboveground biomass to roof artefacts, but a considerable response to drought. Compared to the unroofed control, litter decomposition was decreased both in the drought treatment (-26%) and in the roofed control treatment (-18%), suggesting a response of litter decomposition to roof artefacts in addition to drought. Similarly, aboveground metabolite profiles in the model plant species Medicago x varia were significantly different

  17. 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...

  18. 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.

  19. Interpretation of results from on-farm experiments: manure-nitrogen recovery on grassland as affected by manure quality and application technique. 2. A sociological analysis

    NARCIS (Netherlands)

    Ploeg, van der J.D.; Groot, J.C.J.; Verhoeven, F.P.M.; Lantinga, E.A.

    2007-01-01

    This article discusses the outcomes of a re-analysis of a grassland experiment, by locating it within the wider institutional context composed of well-established routines used in agronomic research and the dominant epistemological tradition of agricultural sciences. It is argued that both, research

  20. Boston type 1 keratoprosthesis: the university of california davis experience.

    Science.gov (United States)

    Bradley, Jay C; Hernandez, Enrique Graue; Schwab, Ivan R; Mannis, Mark J

    2009-04-01

    To compare the University of California Davis experience using the Boston keratoprosthesis with the Boston Keratoprosthesis Study Group's initial report. Retrospective chart review. We analyzed 30 eyes of 28 patients who previously underwent Boston type 1 keratoprosthesis surgery at our institution between 2004 and 2008. Preoperative, intraoperative, and postoperative parameters were collected and analyzed. Visual acuity and keratoprosthesis stability. Preoperative diagnoses were failed graft (26 eyes, 87%), chemical injury (3 eyes, 10%), and Stevens-Johnson syndrome (1 eye, 3%). Twenty eyes (66%) had preoperative glaucoma. Preoperative best-corrected visual acuity ranged from 20/150 to light perception and was or=20/200 in 77% of eyes. Among eyes at least 1 year after the operation (16 eyes), vision was >or=20/200 in 75% of eyes and >or=20/40 in 25% of eyes. At an average follow-up of 19 months, retention of the initial keratoprosthesis was 83.3%. The Boston type 1 keratoprosthesis is a viable option after multiple keratoplasty failures or in conditions with a poor prognosis for primary keratoplasty. Patients with autoimmune disease are at higher risk for complications. The University of California Davis experience seems equivalent to the initial report of the Boston Keratoprosthesis Study Group. With longer follow-up, additional surgical procedures may be required but good anatomic and functional outcomes can be maintained.

  1. Seasonal Variation in the NDVI–Species Richness Relationship in a Prairie Grassland Experiment (Cedar Creek

    Directory of Open Access Journals (Sweden)

    Ran Wang

    2016-02-01

    Full Text Available Species richness generally promotes ecosystem productivity, although the shape of the relationship varies and remains the subject of debate. One reason for this uncertainty lies in the multitude of methodological approaches to sampling biodiversity and productivity, some of which can be subjective. Remote sensing offers new, objective ways of assessing productivity and biodiversity. In this study, we tested the species richness–productivity relationship using a common remote sensing index, the Normalized Difference Vegetation Index (NDVI, as a measure of productivity in experimental prairie grassland plots (Cedar Creek. Our study spanned a growing season (May to October, 2014 to evaluate dynamic changes in the NDVI–species richness relationship through time and in relation to environmental variables and phenology. We show that NDVI, which is strongly associated with vegetation percent cover and biomass, is related to biodiversity for this prairie site, but it is also strongly influenced by other factors, including canopy growth stage, short-term water stress and shifting flowering patterns. Remarkably, the NDVI-biodiversity correlation peaked at mid-season, a period of warm, dry conditions and anthesis, when NDVI reached a local minimum. These findings confirm a positive, but dynamic, productivity–diversity relationship and highlight the benefit of optical remote sensing as an objective and non-invasive tool for assessing diversity–productivity relationships.

  2. Microbial lipid and amino sugar responses to long-term simulated global environmental changes in a California annual grassland

    Directory of Open Access Journals (Sweden)

    Chao eLIANG

    2015-05-01

    Full Text Available Global environmental change is predicted to have major consequences for carbon cycling and the functioning of soil ecosystems. However, we have limited knowledge about its impacts on the microorganisms, which act as a valve between carbon sequestered in soils versus released into the atmosphere. In this study we examined microbial response to continuous 9-year manipulation of three global change factors (elevated CO2, warming, and nitrogen deposition, singly and in combination using two methods: lipid and amino sugar biomarkers at the Jasper Ridge Global Change Experiment (JRGCE. The two methods yielded important distinctions. There were limited microbial lipid differences, but many significant effects for microbial amino sugars. We found that CO2 was not a direct factor influencing soil carbon and major amino sugar pools, but had a positive impact on bacterial-derived muramic acid. Likewise, warming and nitrogen deposition appeared to enrich residues specific to bacteria despite an overall depletion in total amino sugars. The results indicate that elevated CO2, warming, and nitrogen deposition all appeared to increase bacterial-derived residues, but this accumulation effect was far offset by a corresponding decline in fungal residues. The sensitivity of microbial residue biomarker amino sugars to warming and nitrogen deposition may have implications for our predictions of global change impacts on soil stored carbon.

  3. Blue and Valley Oak Seedling Establishment on California's Hardwood Rangelands

    Science.gov (United States)

    Theodore E. Adams Jr.; Peter B. Sands; William H. Weitkamp; Neil K. McDougald

    1991-01-01

    Factors contributing to poor establishment of blue oak (Quercus douglasii) and valley oak (Q. lobata) in California oak-grassland savannas were studied in a series of acorn seeding experiments initiated in 1985. Exclusion of large herbivores permitted examination of herbaceous interference and small mammal and insect depredation....

  4. Standardized measures of critical thinking. Experience with the California Critical Thinking Tests.

    Science.gov (United States)

    Leppa, C J

    1997-01-01

    Standardized measures of student critical thinking are an attractive option for nursing educators under pressure to demonstrate student higher order thinking skills. One program's experience using the California Critical Thinking Skills Test and the California Critical Thinking Dispositions Inventory illustrates some of the problems of using standardized test and potential solutions.

  5. Biodiversity effects on ecosystem functioning in a 15-year grassland experiment

    NARCIS (Netherlands)

    Weisser, Wolfgang; Roscher, Christiane; Meyer, Sebastian T.; Ebeling, Anne; Luo, Guangjuan; Allan, Eric; Beßler, Holger; Barnard, Romain L.; Buchmann, Nina; Buscot, François; Engels, Christof; Fischer, Christine; Fischer, Markus; Gessler, Arthur; Gleixner, Gerd; Halle, Stefan; Hildebrandt, Anke; Hillebrand, Helmut; Kroon, de Hans; Lange, Markus; Leimer, Sophia; Roux, Le Xavier; Milcu, Alexandru; Mommer, Liesje; Niklaus, Pascal A.; Oelmann, Yvonne; Proulx, Raphael; Roy, Jacques; Scherber, Christoph; Scherer-lorenzen, Michael; Scheu, Stefan; Tscharntke, Teja; Wachendorf, Michael; Wagg, Cameron; Weigelt, Alexandra; Wilcke, Wolfgang; Wirth, Christian; Schulze, Ernst Detlef; Schmid, Bernhard; Eisenhauer, Nico

    2017-01-01

    In the past two decades, a large number of studies have investigated the relationship between biodiversity and ecosystem functioning, most of which focussed on a limited set of ecosystem variables. The Jena Experiment was set up in 2002 to investigate the effects of plant diversity on element

  6. Are observed allocation responses in a grassland FACE experiment consistent with functional balance theory?

    Science.gov (United States)

    Stocker, B. D.; Scheider, M.; Lüscher, A.

    2016-12-01

    Terrestrial carbon and nitrogen cycles are tightly coupled by plant tissue stoichiometry and plant controls on ecosystem N retention and fixation. Their co-evolution under rising CO2 and global environmental change is one of the key uncertainties in future Earth system projections. Free Air CO2 Enrichment experiments provide crucial insights into ecosystem responses to elevated CO2, but due to the paucity of such experiments, upscaling and generalisations are often difficult to make. Here, we investigate observed responses in the SwissFACE experiment using a new ecosystem model for the coupled C and N cycles that embodies functional balance theory. In the model, above versus belowground allocation is balanced under daily light conditions and N availability to achieve C and N acquisition in a ratio corresponding to its requirement for new growth. A model setup with plant control on N fixation, based on the relative efficiencies of mineral N uptake versus symbiotic fixation, is compared with a no-fixation setup, reflecting the SwissFACE field experiment conducted separately with N-fixing and non-fixing monocultures. Model predictions based on functional balance theory are generally consistent with observed responses. The strong observed aboveground growth enhancement in non-fixing grass monocultures under high mineral N addition is caused by the relief of N limitation and reduced requirement for fine roots. Under elevated CO2 and low N fertilisation, resource limitation shifts belowground and therefore leads to smaller leaf growth enhancements but enhanced fine root production. On time scales beyond the experiment, this limitation is predicted to be relieved by re-balancing of net N mineralisation and enhanced N retention. These dynamics are different in N-fixing plant communities where temporally increased N limitation after the CO2 step increase is relieved by higher rates of N fixation. Such a model-data analysis supports the interpretation of empirical results

  7. The "Experimenting Agency": The California Youth Authority Research Division.

    Science.gov (United States)

    Palmer, Ted; Petrosino, Anthony

    2003-01-01

    Describes the randomized field trials conducted by the California Youth Authority in the 1960s and 1970s and discusses why such rigorous tests were used and why they eventually came to be used less often. (SLD)

  8. Plant diversity effects on soil microbial functions and enzymes are stronger than warming in a grassland experiment.

    Science.gov (United States)

    Steinauer, Katja; Tilman, David; Wragg, Peter D; Cesarz, Simone; Cowles, Jane M; Pritsch, Karin; Reich, Peter B; Weisser, Wolfgang W; Eisenhauer, Nico

    2015-01-01

    Anthropogenic changes in biodiversity and atmospheric temperature significantly influence ecosystem processes. However, little is known about potential interactive effects of plant diversity and warming on essential ecosystem properties, such as soil microbial functions and element cycling. We studied the effects of orthogonal manipulations of plant diversity (one, four, and 16 species) and warming (ambient, +1.5 degrees C, and +3 degrees C) on soil microbial biomass, respiration, growth after nutrient additions, and activities of extracellular enzymes in 2011 and 2012 in the BAC (biodiversity and climate) perennial grassland experiment site at Cedar Creek, Minnesota, USA. Focal enzymes are involved in essential biogeochemical processes of the carbon, nitrogen, and phosphorus cycles. Soil microbial biomass and some enzyme activities involved in the C and N cycle increased significantly with increasing plant diversity in both years. In addition, 16-species mixtures buffered warming induced reductions in topsoil water content. We found no interactive effects of plant diversity and warming on soil microbial biomass and growth rates. However, the activity of several enzymes (1,4-beta-glucosidase, 1,4-beta-N-acetylglucosaminidase, phosphatase, peroxidase) depended on interactions between plant diversity and warming with elevated activities of enzymes involved in the C, N, and P cycles at both high plant diversity and high warming levels. Increasing plant diversity consistently decreased microbial biomass-specific enzyme activities and altered soil microbial growth responses to nutrient additions, indicating that plant diversity changed nutrient limitations and/or microbial community composition. In contrast to our expectations, higher plant diversity only buffered temperature effects on soil water content, but not on microbial functions. Temperature effects on some soil enzymes were greatest at high plant diversity. In total, our results suggest that the fundamental

  9. 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.

  10. Biodiversity and ecosystem stability in a decade-long grassland experiment.

    Science.gov (United States)

    Tilman, David; Reich, Peter B; Knops, Johannes M H

    2006-06-01

    Human-driven ecosystem simplification has highlighted questions about how the number of species in an ecosystem influences its functioning. Although biodiversity is now known to affect ecosystem productivity, its effects on stability are debated. Here we present a long-term experimental field test of the diversity-stability hypothesis. During a decade of data collection in an experiment that directly controlled the number of perennial prairie species, growing-season climate varied considerably, causing year-to-year variation in abundances of plant species and in ecosystem productivity. We found that greater numbers of plant species led to greater temporal stability of ecosystem annual aboveground plant production. In particular, the decadal temporal stability of the ecosystem, whether measured with intervals of two, five or ten years, was significantly greater at higher plant diversity and tended to increase as plots matured. Ecosystem stability was also positively dependent on root mass, which is a measure of perenniating biomass. Temporal stability of the ecosystem increased with diversity, despite a lower temporal stability of individual species, because of both portfolio (statistical averaging) and overyielding effects. However, we found no evidence of a covariance effect. Our results indicate that the reliable, efficient and sustainable supply of some foods (for example, livestock fodder), biofuels and ecosystem services can be enhanced by the use of biodiversity.

  11. 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

  12. 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...

  13. Effects of herbivores on grassland plant diversity.

    NARCIS (Netherlands)

    Olff, H.; Ritchie, M.E.

    1998-01-01

    The role of herbivores in controlling plant species richness is a critical issue in the conservation and management of grassland biodiversity. Numerous field experiments in grassland plant communities show that herbivores often, but not always, increase plant diversity. Recent work suggests that the

  14. Work Experience Education: A Handbook for California Secondary Schools.

    Science.gov (United States)

    Jastram, Virginia Clapp; And Others

    Prepared by a statewide work experience advisory committee, this handbook is designed to supply administrators of work experience education programs with current, useful information needed to conduct effective work experience programs. Included in the handbook are: (1) a discussion of the nature, purpose, and history of work experience, (2)…

  15. Response of aboveground biomass and diversity to nitrogen addition - a five-year experiment in semi-arid grassland of Inner Mongolia, China

    Science.gov (United States)

    He, Kejian; Qi, Yu; Huang, Yongmei; Chen, Huiying; Sheng, Zhilu; Xu, Xia; Duan, Lei

    2016-08-01

    Understanding the response of the plant community to increasing nitrogen (N) deposition is helpful for improving pasture management in semi-arid areas. We implemented a 5-year N addition experiment in a Stipa krylovii steppe of Inner Mongolia, northern China. The aboveground biomass (AGB) and species richness were measured annually. Along with the N addition levels, the species richness declined significantly, and the species composition changed noticeably. However, the total AGB did not exhibit a noticeable increase. We found that compensatory effects of the AGB occurred not only between the grasses and the forbs but also among Gramineae species. The plant responses to N addition, from the community to species level, lessened in dry years compared to wet or normal years. The N addition intensified the reduction of community productivity in dry years. Our study indicated that the compensatory effects of the AGB among the species sustained the stability of grassland productivity. However, biodiversity loss resulting from increasing N deposition might lead the semi-arid grassland ecosystem to be unsustainable, especially in dry years.

  16. Response of aboveground biomass and diversity to nitrogen addition - a five-year experiment in semi-arid grassland of Inner Mongolia, China.

    Science.gov (United States)

    He, Kejian; Qi, Yu; Huang, Yongmei; Chen, Huiying; Sheng, Zhilu; Xu, Xia; Duan, Lei

    2016-08-30

    Understanding the response of the plant community to increasing nitrogen (N) deposition is helpful for improving pasture management in semi-arid areas. We implemented a 5-year N addition experiment in a Stipa krylovii steppe of Inner Mongolia, northern China. The aboveground biomass (AGB) and species richness were measured annually. Along with the N addition levels, the species richness declined significantly, and the species composition changed noticeably. However, the total AGB did not exhibit a noticeable increase. We found that compensatory effects of the AGB occurred not only between the grasses and the forbs but also among Gramineae species. The plant responses to N addition, from the community to species level, lessened in dry years compared to wet or normal years. The N addition intensified the reduction of community productivity in dry years. Our study indicated that the compensatory effects of the AGB among the species sustained the stability of grassland productivity. However, biodiversity loss resulting from increasing N deposition might lead the semi-arid grassland ecosystem to be unsustainable, especially in dry years.

  17. Non-native plants and soil microbes: potential contributors to the consistent reduction in soil aggregate stability caused by the disturbance of North American grasslands.

    Science.gov (United States)

    Duchicela, Jessica; Vogelsang, Keith M; Schultz, Peggy A; Kaonongbua, Wittaya; Middleton, Elizabeth L; Bever, James D

    2012-10-01

    • Soil aggregate stability is an important ecosystem property that is altered by anthropogenic disturbance. Yet, the generalization of these alterations and the identification of the main contributors are limited by the absence of cross-site comparisons and the application of inconsistent methodologies across regions. • We assessed aggregate stability in paired remnant and post-disturbance grasslands across California, shortgrass and tallgrass prairies, and in manipulative experiments of plant composition and soil microbial inoculation. • Grasslands recovering from anthropogenic disturbance consistently had lower aggregate stability than remnants. Across all grasslands, non-native plant diversity was significantly associated with reduced soil aggregate stability. A negative effect of non-native plants on aggregate stability was also observed in a mesocosm experiment comparing native and non-native plants from California grasslands. Moreover, an inoculation study demonstrated that the degradation of the microbial community also contributes to the decline in soil aggregate stability in disturbed grasslands. • Anthropogenic disturbance consistently reduced water-stable aggregates. The stability of aggregates was reduced by non-native plants and the degradation of the native soil microbial community. This latter effect might contribute to the sustained decline in aggregate stability following anthropogenic disturbance. Further exploration is advocated to understand the generality of these potential mechanisms. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

  18. California Student Counselors Reflect on a Study Abroad Experience in New Zealand

    Science.gov (United States)

    Winslade, John; Douglass, Amy; Echeverria, Korina; Garcia, Joanna; Howard, Krystal; Lillard, Dorry; Stephens, Samantha; Zacarias, Stefany

    2015-01-01

    Seven counseling and guidance students from California participated in a study abroad program in which they were placed in a high school in Auckland, New Zealand, for one month. Their comments on the experience in response to researchers' questions form the basis of this paper. They suggest that the participants benefited from being immersed in a…

  19. Abiotic processes are insufficient for fertile island development: A 10-year artificial shrub experiment in a desert grassland

    Science.gov (United States)

    Li, Junran; Gilhooly, William P.; Okin, Gregory S.; Blackwell, John

    2017-03-01

    The relative importance of biotic and abiotic processes in the development of "fertile islands" in dryland systems has rarely been investigated. Here we approached this question by using artificial shrubs, which exclude plant litter production and soil nutrient uptake, but retain the functions of trapping windblown material, funneling of stemflow, and differential rain splash. We conducted a vegetation manipulation study more than a decade ago in the desert grassland of southern New Mexico and subsequently revisited the site in 2012 and 2015. The results show that no notable soil mounds were observed under the artificial shrubs; however, soil texture under the artificial shrubs has gradually changed to resemble the patterns of soil particle-size distribution under natural shrubs. Our results highlight that with the exclusion of direct biotic additions, soils captured by shrub canopies are not necessarily fertile and thus do not themselves contribute to the development of fertile islands.

  20. 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.

  1. An interdisciplinary tillage erosion experiment: establishing a new field in grassland with reconstructed ard plough of the Bronze Age - Iron Age

    Science.gov (United States)

    Pavelka, Jan; Smetanová, Anna; Rejman, Jerzy; Kováčik, Peter

    2017-04-01

    Despite recognising the role of tillage erosion in landforms evolution, little research has documented its effects in prehistoric times. Herein, an interdisciplinary archaeological-geomorphological experiment with reconstructed tillage tools and management was conducted in order to measure tillage erosion when a new field in grasslands was established in the Bronze Age-Iron Age. Three wooden ards were reconstructed based on archaeological findings. They were tested in a cross-tillage experiment, consisting of a tillage pass perpendicular to the primary slope (6.5-9.7%), and a second tillage pass parallel to the primary slope of a convex-convex ridge with mowed grass (0.2 m high, vegetation cover >90%). The standard sole ard proved to be the most effective, with a mean tillage depth of 0.12 m, a mean tillage speed of 3.8 km h-1, and a mean distance between furrows of 0.20-0.25 m. Only 13% of the 264 tracers placed on 6 transects were displaced, and the mean tracers displacement parallel to the primary slope was 0.04 ± 0.17 m. Contour tillage perpendicular to primary slope created V or U shaped furrows with a mean depth of 0.1-0.12 m, a mean width of 0.05-0.1 m, and incision under the main root zone. Only soil in direct contact with the ard was displaced, with a mean translocation distance of 0.06 ± 0.2 m parallel and 0.06 ± 0.3 m perpendicular to the primary slope. During tillage parallel to slope, soil clods of 0.20 x 0.25 x 0.10 m were created and slightly disturbed or turned over one another. The tracers moved within the furrows and with the soil clods. Loose soil, resembling a seedbed, was not covered by soil clods. Mean displacement during the second pass was 0.03 ± 0.19 m parallel and 0.00 ± 0.15 m perpendicular to primary slope. The displacement from cross-tillage with a wooden ard in permanent grasslands was lower than many previously measured values of traditional animal-powered metal ploughs in permanent fields. No relationship between mean soil

  2. Southwestern Grassland Ecology

    Science.gov (United States)

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

    2004-01-01

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

  3. 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.

  4. Women's childhood and adult adverse experiences, mental health, and binge drinking: The California Women's Health Survey

    Directory of Open Access Journals (Sweden)

    Pavao Joanne

    2008-06-01

    Full Text Available Abstract Background This study examined sociodemographic, physical and mental health, and adult and childhood adverse experiences associated with binge drinking in a representative sample of women in the State of California. Materials and methods Data were from the 2003 to 2004 (response rates of 72% and 74%, respectively California Women's Health Survey (CWHS, a population-based, random-digit-dial annual probability survey sponsored by the California Department of Health Services. The sample was 6,942 women aged 18 years or older. Results The prevalence of binge drinking was 9.3%. Poor physical health, and poorer mental health (i.e., symptoms of PTSD, anxiety, and depression, feeling overwhelmed by stress, were associated with binge drinking when demographics were controlled, as were adverse experiences in adulthood (intimate partner violence, having been physically or sexually assaulted, or having experienced the death of someone close and in childhood (living with someone abusing substances or mentally ill, or with a mother vicimized by violence, or having been physically or sexually assaulted. When adult mental health and adverse experiences were also controlled, having lived as a child with someone who abused substances or was mentally ill was associated with binge drinking. Associations between childhood adverse experiences and binge drinking could not be explained by women's poorer mental health status in adulthood. Conclusion Identifying characteristics of women who engage in binge drinking is a key step in prevention and intervention efforts. Binge drinking programs should consider comprehensive approaches that address women's mental health symptoms as well as circumstances in the childhood home.

  5. Land tenure reform and grassland degradation in Inner Mongolia, China

    Science.gov (United States)

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

    2017-04-01

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

  6. Farm-gate budget of energy crops: an experiment to assess changes in GHGs balance due to a land use change from grassland to short rotation coppice of poplar

    Science.gov (United States)

    Sabbatini, S.; Arriga, N.; Baiocco, A.; Boschi, A.; Castaldi, S.; Consalvo, C.; Gioli, B.; Matteucci, G.; Tomassucci, M.; Zaldei, A.; Papale, D.

    2012-04-01

    Over the last decades the rising in the prices of oil pushed many farmers all over the Europe to exploit part of their fields to produce biomass for energy. Government funding promoted this trend in order to contrast global warming and Green-House Gases (GHG) emissions. Nevertheless energy crops entail, in addition to a land use change, a sum of treatments that leads again to emissions of GHG. In the context of the GHG-Europe FP7 project we set-up an experiment to study a case of land use change from grassland to Short Rotation Coppice (SRC) of poplar clones in central Italy. Through the Eddy Covariance (EC) technique, we measure carbon and energy fluxes over two different poplar SRC with different ages, and over a reference site (grassland) representing the original land use. Furthermore, we measured additional fluxes such as soil respiration, CH4 and N2O fluxes using chambers. To compute the Farm-Gate Budget (FGB) of both the grassland and the poplar plantations, we collect also additional data that contribute to GHG budget such as management (tillage, fertilizations, irrigations, harvesting) and disturbances. In this poster we present the experiment set-up and the first results resulting from the measurements.

  7. Grassland Management Plan [Draft

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This grassland management plan is for Bear River Migratory Bird Refuge in Utah. It includes a summary of the refuge, special considerations for endangered species,...

  8. 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.

  9. Experiences in Care According to Parental Citizenship and Language Use Among Latino Children in California.

    Science.gov (United States)

    Ortega, Alexander N; McKenna, Ryan M; Langellier, Brent A; Alcalá, Héctor E; Roby, Dylan H

    2017-01-05

    To assess differences in health care access, utilization, and experiences among Latino children in California according to parental citizenship status and language use. Data are from the 2011 and 2012 California Health Interview Survey public use child files. A total of 2841 interviews of parents of Latino children younger than the age of 12 years were conducted. Analyses were conducted to determine the associations between access (usual of source of care, delay in receiving needed care, health insurance), utilization (physician visits in past year, emergency department visits), and experiences (doctor listens, doctor explains instructions clearly, communication via telephone or e-mail) according to parental citizenship status and household language use after adjusting for confounders. In multivariate analyses, there were no significant differences in access to care according to parental citizenship status. Children with 2 noncitizen parents had fewer doctor visits and were less likely to go to the emergency department in the past year than those with 2 citizen parents. Among children with 1 or 2 noncitizen parents, their parents reported worse experiences in care than those with 2 citizen parents. Similar results were observed for language use. Parents of children in bilingual and Spanish-only households were less likely to report that their children's doctors explained things clearly, and parents in Spanish-only households were less likely to communicate via telephone or e-mail than those in English-only households. Health policy should focus on provider-parent communication to ensure health care equity for Latino children whose parents are not citizens or do not speak English. Copyright © 2017 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

  10. [Effect of grazing on grassland under protective plantation in the ecotone between agriculture and animal husbandry or Songnen plain].

    Science.gov (United States)

    He, Nianpeng; Wu, Ling; Zhou, Daowei

    2004-05-01

    Based on the current special position that grassland under protective plantation is one of the most important grazing spaces of the ecotone between agriculture and animal husbandry in Songnen plain, an experiment was conducted to investigate the effect of grazing on grassland under protective plantation. The results showed that no-grazing grassland in the grassland under protective plantation was seriously degenerated, but light and moderate grazing could stimulate the growth of grass and the product and quality of grassland. The index of grassland quality (IGQ) of no-grazing grassland was the lowest (15.51), attributing to serious degradation, while that of light grazing grassland was the highest (86.41), and the IGQ was decreased with increasing grazing intensity. Therefore, in order to stimulate the grass growth of the grassland, fully utilize the leaves of poplar, and increase the available forage resources, light and moderate grazing intensity should be advocated, but no-grazing and extreme grazing should be avoided.

  11. [Experiences of undocumented Mexican migrant women when accessing sexual and reproductive health services in California, USA: a case study].

    Science.gov (United States)

    Deeb-Sossa, Natalia; Díaz Olavarrieta, Claudia; Juárez-Ramírez, Clara; García, Sandra G; Villalobos, Aremis

    2013-05-01

    This study focuses on the experience of Mexican women migrants in California, USA, with the use of formal health services for sexual and reproductive health issues. The authors used a qualitative interpretative approach with life histories, interviewing eight female users of healthcare services in California and seven key informants in Mexico and California. There were three main types of barriers to healthcare: immigration status, language, and gender. Participants reported long waiting times, discriminatory attitudes, and high cost of services. A combination of formal and informal healthcare services was common. The assessment of quality of care was closely related to undocumented immigration status. Social support networks are crucial to help solve healthcare issues. Quality of care should take intercultural health issues into account.

  12. Grassland: a global resource

    National Research Council Canada - National Science Library

    McGilloway, D. A

    2005-01-01

    ... and discussions on more specialised topics of worldwide significance. Grasslands: a Global Resource draws together contributions from leading researchers, educators, policy makers and farmers from around the world, to espouse current knowledge and understanding of this complex ecosystem, the ways in which it can be enhanced and utilised an...

  13. 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.

  14. 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....... There was a tendency towards increased biomass in the large root fraction with increasing herb content. The experiment indicated increased CO2 evolution following cultivation of multispecies grasslands...

  15. Kaiser Permanente Northern California: current experiences with internet, mobile, and video technologies.

    Science.gov (United States)

    Pearl, Robert

    2014-02-01

    The US health care system has been slow to adopt Internet, mobile, and video technologies, which have the capability to engage patients in their own care, increase patients' access to providers, and possibly improve the quality of care while reducing costs. Nevertheless, there are some pockets of progress, including Kaiser Permanente Northern California (KPNC). In 2008 KPNC implemented an inpatient and ambulatory care electronic health record system for its 3.4 million members and developed a suite of patient-friendly Internet, mobile, and video tools. KPNC has achieved many successes. For example, the number of virtual "visits" grew from 4.1 million in 2008 to an estimated 10.5 million in 2013. This article describes KPNC's experience with Internet, mobile, and video technologies and the obstacles faced by other health care providers interested in embracing them. The obstacles include the predominant fee-for-service payment model, which does not reimburse for virtual visits; the considerable investment needed to deploy these technologies; and physician buy-in.

  16. Prevention of natural grassland invasion by Eragrostis plana Nees using ecological management practices

    Directory of Open Access Journals (Sweden)

    Telmo Focht

    2012-08-01

    Full Text Available The objective of this research was to evaluate the effects of different types of disturbance on the ability of the natural grassland to avoid the invasion of Eragrostis plana Nees (South African lovegrass. The experiment was carried out in Dom Pedrito, Rio Grande do Sul, Brazil, in an area free of South African lovegrass, from Feb. 2004 to Apr. 2007. The treatments were: 1 grassland management regimes: exclusion; low grazing intensity (rotational grazing, ±10 cm; and high grazing intensity (continuous grazing, ±5 cm; 2 initial levels of soil disturbance: high grassland, ±10 cm; low grassland, ±5 cm height; and low grassland with scarified soil; 3 fertilization regimes: without fertilization; phosphorus; and nitrogen. The experimental design was a split-split-plot type in complete blocks, with three replicates. Three winter cultivated species - Trefoil repens L., Lotus corniculatus L., Lolium multiflorum Lam. and South African lovegrass -were sown in 54 split-splitplots (split-plots: low grassland, and low grassland with scarified soil. The other 27 split-split-plots (split-plots: high grassland were sown only with South African lovegrass. The grassland height, plant number of South African lovegrass, grassland dry mass and photosynthetic active radiation intercepted (FARint at the soil level were recorded. The fertilization regimes did not influence the South African lovegrass plant number. The initial levels of soil disturbance and grassland management regimes influenced the invasion of South African lovegrass. The invasion was favored by the lower grassland height and lower forage mass, higher intensity of the soil disturbance, and higher FARint due to the continuous grazing. On the contrary, higher grassland height, higher forage mass, lower soil disturbance and lower FARint, associated with rotational grazing or exclusion, showed higher potential to control the invasion of South African lovegrass in the natural grassland.

  17. North American Grasslands & Biogeographic Regions

    Science.gov (United States)

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

  18. Enhancing Price Response Programs through Auto-DR: California's 2007 Implementation Experience

    Energy Technology Data Exchange (ETDEWEB)

    Kiliccote, Sila; Wikler, Greg; Chiu, Albert; Piette, Mary Ann; Kiliccote, Sila; Hennage, Dan; Thomas, Chuck

    2007-12-18

    This paper describes automated demand response (Auto-DR) activities, an innovative effort in California to ensure that DR programs produce effective and sustainable impacts. Through the application of automation and communication technologies coupled with well-designed incentives and DR programs such as Critical Peak Pricing (CPP) and Demand Bidding (DBP), Auto-DR is opening up the opportunity for many different types of buildings to effectively participate in DR programs. We present the results of Auto-DR implementation efforts by the three California investor-owned utilities for the Summer of 2007. The presentation emphasizes Pacific Gas and Electric Company's (PG&E) Auto-DR efforts, which represents the largest in the state. PG&E's goal was to recruit, install, test and operate 15 megawatts of Auto-DR system capability. We describe the unique delivery approaches, including optimizing the utility incentive structures designed to foster an Auto-DR service provider community. We also show how PG&E's Critical Peak Pricing (CPP) and Demand Bidding (DBP) options were called and executed under the automation platform. Finally, we show the results of the Auto-DR systems installed and operational during 2007, which surpassed PG&E's Auto-DR goals. Auto-DR is being implemented by a multi-disciplinary team including the California Investor Owned Utilities (IOUs), energy consultants, energy management control system vendors, the Lawrence Berkeley National Laboratory (LBNL), and the California Energy Commission (CEC).

  19. Geothermal Gases--Community Experiences, Perceptions, and Exposures in Northern California.

    Science.gov (United States)

    Chiu, Cindy H; Lozier, Matthew J; Bayleyegn, Tesfaye; Tait, Karen; Barreau, Tracy; Copan, Lori; Roisman, Rachel; Jackson, Rebecca; Smorodinsky, Svetlana; Kreutzer, Richard A; Yip, Fuyuen; Wolkin, Amy

    2015-12-01

    Lake County, California, is in a high geothermal-activity area. Over the past 30 years, the city of Clearlake has reported health effects and building evacuations related to geothermal venting. Previous investigations in Clearlake revealed hydrogen sulfide at levels known to cause health effects and methane at levels that can cause explosion risks. The authors conducted an investigation in multiple cities and towns in Lake County to understand better the risk of geothermal venting to the community. They conducted household surveys and outdoor air sampling of hydrogen sulfide and methane and found community members were aware of geothermal venting and some expressed concerns. The authors did not, however, find hydrogen sulfide above the California Environmental Protection Agency air quality standard of 30 parts per billion over one hour or methane above explosive thresholds. The authors recommend improving risk communication, continuing to monitor geothermal gas effects on the community, and using community reports and complaints to monitor and document geothermal venting incidents.

  20. 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

  1. How to Promote the Badamu Industry in Shache County Xinjiang with Experiences Drawn from American California

    Directory of Open Access Journals (Sweden)

    Xuefeng Xiao

    2014-04-01

    Full Text Available Xinjiang Amygdalus Communis L. (Badamu is a kind of precious nut in the world, which has a long growing history in southern Xinjiang along the Yeerqing and kashigeer rivers. Shache county is the main producing area. Owing to a big lag in growing technique, process and marketing behind those of the advanced countries, economic gains are low and insufficient. This thesis makes a contrast between the growing the marketing models of Shache and of California, points out the problems in Shache, and presents some suggestions on the healthy development of the Badanmu industry in Xinjiang.

  2. Chicken farming in grassland increases environmental sustainability and economic efficiency.

    Science.gov (United States)

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

    2013-01-01

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

  3. Birds of Southwestern grasslands: Status, conservation, and management

    Science.gov (United States)

    Michele Merola-Zwartjes

    2005-01-01

    In the Southwestern United States, the grassland avifauna is collectively composed of a mixture of species found primarily in desert grasslands, shortgrass steppe, wet meadows, and alpine tundra (as used here, desert grasslands incorporate both arid grasslands and desert shrub grasslands). Of these habitats, desert grasslands and shortgrass steppe are the most...

  4. NPP Grassland: Charleville, Australia, 1973-1974

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: Above and below ground productivity of a native C3 grassland and an introduced C4 grassland were studied from 1973-1974 near Charleville in Southern...

  5. Prescribed fire as an alternative measure in European grassland conservation

    Science.gov (United States)

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

    2015-04-01

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

  6. Environmental Assessment Military Housing Privatization Initiative at Beale Air Force Base, California

    Science.gov (United States)

    2005-06-01

    the key management personnel, investigators and technical 5 personnel that contributed to document preparation. 6 Name Degree Professional...conducted Marysville California kangaroo rat ( Dipodomys californicus eximus) SC/SSC Sutter Buttes in Sutter County Occurs in grassland and

  7. 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

  8. UCI Alumni and Their Careers. A Survey of the Graduate Training and Work Experience of the First Decade of the University of California, Irvine Alumni.

    Science.gov (United States)

    California Univ., Irvine. Student Affairs Office of Studies and Research.

    The career and educational experiences of the baccalaureate degree recipients of the University of California at Irvine (UCI) during the first decade of its existence, 1965-74, were studied. A response from 2,479 alumni, or 51 percent, provided information concerning: (1) educational attainment; (2) initial employment after graduation; and (3)…

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

    Directory of Open Access Journals (Sweden)

    Rowan D. Buhrmann

    2016-11-01

    Full Text Available Background: Tropical and subtropical Africa is predicted to experience a rise in temperature. The effects of rising temperatures on temperate grasslands have been studied using open-top chambers (OTCs but reports for tropical/subtropical grasslands are scarce. This study used OTCs to investigate the effects of elevated temperatures on a threatened subtropical grassland type, namely KwaZulu-Natal Sandstone Sourveld (KZNSS.Objectives: To assess the effects of OTCs on selected abiotic parameters and plant productivity within KZNSS.Methods: Five OTC and control plots were randomly distributed at the same altitude within a patch of KZNSS. Air and soil temperature, relative humidity (RH, soil moisture content and light intensity were monitored in all plots in spring, summer, autumn and winter. Biomass production and plant density were measured in each season, for each life form (graminoid, forb and shrub, separately and combined.Results: The OTCs resulted in a rise in average, maximum and minimum day and night, air and soil temperatures. This increase, the degree of which differed across seasons, was accompanied by a decline in RH and soil moisture content. Elevated temperatures led to a significant increase in combined, graminoid and shrub above-ground productivity (AGP and a decrease in forb density, but in certain seasons only. Below-ground biomass production was unaffected by elevated temperatures.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.

  10. A major state tobacco tax increase, the master settlement agreement, and cigarette consumption: the California experience.

    Science.gov (United States)

    Sung, Hai-Yen; Hu, Teh-wei; Ong, Michael; Keeler, Theodore E; Sheu, Mei-ling

    2005-06-01

    We evaluated the combined effects on California cigarette consumption of an additional 50 cent per pack state tax imposed by Proposition 10 of January 1999 and a 45 cent per pack increase in cigarette prices stemming from the Master Settlement Agreement (MSA) of November 1998. We used quarterly cigarette sales data for the period 1984-2002 to estimate a time-series intervention model adjusting for seasonal variations and time trend. Over the period 1999 through 2002, the combined effect was to reduce cigarette consumption by 2.4 packs per capita per quarter (1.3 billion packs total over the 4-year period) and to raise state tax revenues by $2.1 billion. These effects were similar to the effects of a 25 cent per pack tax increase enacted by Proposition 99 a decade earlier, although with decreased relative effectiveness as measured by percentage of reduction in cigarette consumption divided by percentage of increase in taxation (-0.44 vs -0.60). A major increase in price through taxation and the MSA provided a strong economic disincentive for smokers in a state with a low smoking prevalence. This effect could be reinforced if part of the MSA payments were devoted to tobacco control programs.

  11. 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.

  12. Childhood Experiences and Psychosocial Influences on HIV Risk among Adolescent Latinas in Southern California.

    Science.gov (United States)

    Newcomb, Michael D.; Locke, Thomas F.; Goodyear, Rodney K.

    2003-01-01

    This study determined how adverse childhood experiences influenced risky sexual behavior in a community sample of Latina adolescents in Los Angeles. Psychosocial, sociocultural, and environmental mediators of the relations between childhood experiences and risky sexual behavior were tested. Childhood maltreatment was associated with risky sexual…

  13. Adverse childhood experiences and substance use among Hispanic emerging adults in Southern California.

    Science.gov (United States)

    Allem, Jon-Patrick; Soto, Daniel W; Baezconde-Garbanati, Lourdes; Unger, Jennifer B

    2015-11-01

    Emerging adults who experienced stressful childhoods may engage in substance use as a maladaptive coping strategy. Given the collectivistic values Hispanics encounter growing up, adverse childhood experiences may play a prominent role in substance use decisions as these events violate the assumptions of group oriented cultural paradigms. Alternatively, adverse childhood events might not increase the risk of substance use because strong family ties could mitigate the potential maladaptive behaviors associated with these adverse experiences. This study examined whether adverse childhood experiences were associated with substance use among Hispanic emerging adults. Participants (n = 1420, mean age = 22, 41% male) completed surveys indicating whether they experienced any of 8 specific adverse experiences within their first 18 years of life, and past-month cigarette use, marijuana use, hard drug use, and binge drinking. Logistic regression models examined the associations between adverse childhood experiences and each category of substance use, controlling for age, gender, and depressive symptoms. The number of adverse childhood experiences was significantly associated with each category of substance use. A difference in the number of adverse childhood experiences, from 0 to 8, was associated with a 22% higher probability of cigarette smoking, a 24% higher probability of binge drinking, a 31% higher probability of marijuana use, and a 12% higher probability of hard drug use respectively. These findings should be integrated into prevention/intervention programs in hopes of quelling the duration and severity of substance use behaviors among Hispanic emerging adults. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. 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.

  15. Grassland rehabilitation (Rehabilitacion de Pastizales)

    Science.gov (United States)

    Mario Royo

    2006-01-01

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

  16. 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...

  17. Nonlinear, interacting responses to climate limit grassland production under global change.

    Science.gov (United States)

    Zhu, Kai; Chiariello, Nona R; Tobeck, Todd; Fukami, Tadashi; Field, Christopher B

    2016-09-20

    Global changes in climate, atmospheric composition, and pollutants are altering ecosystems and the goods and services they provide. Among approaches for predicting ecosystem responses, long-term observations and manipulative experiments can be powerful approaches for resolving single-factor and interactive effects of global changes on key metrics such as net primary production (NPP). Here we combine both approaches, developing multidimensional response surfaces for NPP based on the longest-running, best-replicated, most-multifactor global-change experiment at the ecosystem scale-a 17-y study of California grassland exposed to full-factorial warming, added precipitation, elevated CO2, and nitrogen deposition. Single-factor and interactive effects were not time-dependent, enabling us to analyze each year as a separate realization of the experiment and extract NPP as a continuous function of global-change factors. We found a ridge-shaped response surface in which NPP is humped (unimodal) in response to temperature and precipitation when CO2 and nitrogen are ambient, with peak NPP rising under elevated CO2 or nitrogen but also shifting to lower temperatures. Our results suggest that future climate change will push this ecosystem away from conditions that maximize NPP, but with large year-to-year variability.

  18. Interracial dating: attitudes and experience among American college students in California.

    Science.gov (United States)

    Fiebert, M S; Karamol, H; Kasdan, M

    2000-12-01

    Dating and marriage crossing ethnic, racial, and cultural lines have become increasingly common in the United States. This study examined two aspects, interracial dating behavior and attitudes toward romantic involvement, in four ethnic groups of college students: Euro-American, Latino, Asian-American, and African-American. Subjects (196 men, 367 women) were surveyed with regard to their willingness to be romantically involved interracially or interculturally along with their actual interracial dating experience. Analysis indicated a high willingness in all ethnic groups to be romantically involved as well as an absence of sex difference with regard to both attitude and experience. However, there were differences in both attitude and experience among ethnic groups.

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

    Science.gov (United States)

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

    2017-02-23

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

  20. Cross-Jurisdictional Sharing for Emergency Management-Related Public Health: Exploring the Experiences of Tribes and Counties in California

    Directory of Open Access Journals (Sweden)

    Maureen A. Wimsatt

    2017-09-01

    Full Text Available Each American Indian tribe is unique in several ways, including in its relationships with local governments and risk for emergencies. Cross-jurisdictional sharing (CJS arrangements are encouraged between tribes and counties for emergency management-related population health, but researchers have not yet explored CJS experiences of tribes and counties for emergency management. This investigation used collaboration theory and a CJS spectrum framework to assess the scope and prevalence of tribe–county CJS arrangements for emergency management in California as well as preconditions to CJS. Mixed-methods survey results indicate that tribes and counties have varied CJS arrangements, but many are informal or customary. Preconditions to CJS include tribe–county agreement about having CJS, views of the CJS relationship, barriers to CJS, and jurisdictional strengths and weaknesses in developing CJS arrangements. Areas for public health intervention include funding programs that build tribal capacity in emergency management, reduce cross-jurisdictional disagreement, and promote ongoing tribe–county relationships as a precursor to formal CJS arrangements. Study strengths, limitations, and future directions are also discussed.

  1. Cross-Jurisdictional Sharing for Emergency Management-Related Public Health: Exploring the Experiences of Tribes and Counties in California.

    Science.gov (United States)

    Wimsatt, Maureen A

    2017-01-01

    Each American Indian tribe is unique in several ways, including in its relationships with local governments and risk for emergencies. Cross-jurisdictional sharing (CJS) arrangements are encouraged between tribes and counties for emergency management-related population health, but researchers have not yet explored CJS experiences of tribes and counties for emergency management. This investigation used collaboration theory and a CJS spectrum framework to assess the scope and prevalence of tribe-county CJS arrangements for emergency management in California as well as preconditions to CJS. Mixed-methods survey results indicate that tribes and counties have varied CJS arrangements, but many are informal or customary. Preconditions to CJS include tribe-county agreement about having CJS, views of the CJS relationship, barriers to CJS, and jurisdictional strengths and weaknesses in developing CJS arrangements. Areas for public health intervention include funding programs that build tribal capacity in emergency management, reduce cross-jurisdictional disagreement, and promote ongoing tribe-county relationships as a precursor to formal CJS arrangements. Study strengths, limitations, and future directions are also discussed.

  2. Effectiveness of "On Our Way to English" for Development of Reading and Oral Proficiency by Elementary English Learners: A Report of Randomized Experiments in a California and a Texas School District. Research Summary

    Science.gov (United States)

    Empirical Education Inc., 2006

    2006-01-01

    The authors conducted an experiment during the 2003-2004 school year to determine whether "On Our Way to English" ("OWE"), a product to help elementary students learn to read and speak English, was more effective in a California and a Texas school district than materials already in place. In the California study, 384 English…

  3. California Bioregions

    Data.gov (United States)

    California Department of Resources — 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...

  4. A FLORISTIC INVENTORY OF THE CIMARRON NATIONAL GRASSLAND (KANSAS) AND THE COMANCHE NATIONAL GRASSLAND (COLORADO)

    National Research Council Canada - National Science Library

    Bernadette Kuhn; B.E. Nelson; Ronald L. Hartman

    2011-01-01

    ... Cimarrón National Grassland, Comanche National Grassland, and adjacent private lands. Our study area, spread over Baca, Las Animas, and Otero counties in Colorado and Morton County in Kansas, encompasses 567,300 acres...

  5. 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.

  6. Surging wildfire activity in a grassland biome

    Science.gov (United States)

    Donovan, Victoria M.; Wonkka, Carissa L.; Twidwell, Dirac

    2017-06-01

    Rapid changes in wildfire patterns are documented globally, increasing pressure to identify regions that may experience increases in wildfire in future decades. Temperate grassland and savanna biomes were some of the most frequently burned regions on Earth; however, large wildfires have been largely absent from the Great Plains of North America over the last century. In this paper, we conduct an in-depth analysis of changes in large wildfire (>400 ha) regime characteristics over a 30 year period across the Great Plains. For the entire biome, (i) the average number of large wildfires increased from 33.4 ± 5.6 per year from 1985 to 1994 to 116.8 ± 28.8 wildfires per year from 2005 to 2014, (ii) total area burned by large wildfires increased 400%, (iii) over half the ecoregions had greater than a 70% probability of a large wildfire occurring in the last decade, and (iv) seasonality of large wildfires remained relatively similar.

  7. Spatial distribution of grassland productivity and land use in Europe

    NARCIS (Netherlands)

    Smit, H.J.; Metzger, M.J.; Ewert, F.

    2008-01-01

    Grasslands are an important land use in Europe with essential functions for feed and ecosystem service supply. Impact assessment modelling of European agriculture and the environment needs to consider grasslands and requires spatially explicit information on grassland distribution and productivity,

  8. Rocky 7 prototype Mars rover field geology experiments 1. Lavic Lake and sunshine volcanic field, California

    Science.gov (United States)

    Arvidson, R. E.; Acton, C.; Blaney, D.; Bowman, J.; Kim, S.; Klingelhofer, G.; Marshall, J.; Niebur, C.; Plescia, J.; Saunders, R.S.; Ulmer, C.T.

    1998-01-01

    Experiments with the Rocky 7 rover were performed in the Mojave Desert to better understand how to conduct rover-based, long-distance (kilometers) geological traverses on Mars. The rover was equipped with stereo imaging systems for remote sensing science and hazard avoidance and 57Fe Mo??ssbauer and nuclear magnetic resonance spectrometers for in situ determination of mineralogy of unprepared rock and soil surfaces. Laboratory data were also obtained using the spectrometers and an X ray diffraction (XRD)/XRF instrument for unprepared samples collected from the rover sites. Simulated orbital and descent image data assembled for the test sites were found to be critical for assessing the geologic setting, formulating hypotheses to be tested with rover observations, planning traverses, locating the rover, and providing a regional context for interpretation of rover-based observations. Analyses of remote sensing and in situ observations acquired by the rover confirmed inferences made from orbital and simulated descent images that the Sunshine Volcanic Field is composed of basalt flows. Rover data confirmed the idea that Lavic Lake is a recharge playa and that an alluvial fan composed of sediments with felsic compositions has prograded onto the playa. Rover-based discoveries include the inference that the basalt flows are mantled with aeolian sediment and covered with a dense pavement of varnished basalt cobbles. Results demonstrate that the combination of rover remote sensing and in situ analytical observations will significantly increase our understanding of Mars and provide key connecting links between orbital and descent data and analyses of returned samples. Copyright 1998 by the American Geophysical Union.

  9. Fourteen years of forage monitoring on the California Central Coast shows tremendous variation

    Science.gov (United States)

    Royce Larsen; Karl Striby; Marc Horney

    2015-01-01

    To better understand forage production (above ground biomass) and precipitation patterns in the Central Coast region of California, the first in a growing network of primary production monitoring sites were established in 2001. The California Central Coast has a Mediterranean climate with cool, moist winters and hot, dry summers, and is dominated by annual grasslands...

  10. Interactive effects of grazing, drought, and fire on grassland plant communities in North America and South Africa.

    Science.gov (United States)

    Koerner, Sally E; Collins, Scott L

    2014-01-01

    Grazing, fire, and climate shape mesic grassland communities. With global change altering all three factors, understanding how grasslands respond to changes in these combined drivers may aid in projecting future changes in grassland ecosystems. We manipulated rainfall and simulated grazing (clipping) in two long-term fire experiments in mesic grasslands in North America (NA) and South Africa (SA). Despite their common drivers, grasslands in NA and SA differ in evolutionary history. Therefore, we expected community structure and production in NA and SA to respond differently to fire, grazing, and drought. Specifically, we hypothesized that NA plant community composition and production would be more responsive than the SA plant communities to changes in the drivers and their interactions, and that despite this expected stability of SA grasslands, drought would be the dominant factor controlling production, but grazing would play the primary role in determining community composition at both sites. Contrary to our hypothesis, NA and SA grasslands generally responded similarly to grazing, drought, and fire. Grazing increased diversity, decreased grass cover and production, and decreased belowground biomass at both sites. Drought alone minimally impacted plant community structure, and we saw similar treatment interactions at the two sites. Drought was not the primary driver of grassland productivity, but instead drought effects were similar to or less than grazing and fire. Even though these grasslands differed in evolutionary history, they responded similarly to our fire, grazing, and climate manipulations. Overall, we found community and ecosystem convergence in NA and SA grasslands. Grazing and fire are as important as climate in controlling mesic grassland ecosystems on both continents.

  11. Nitrous oxide emission from intensively managed grasslands

    NARCIS (Netherlands)

    Velthof, G.L.

    1997-01-01

    The aims of this thesis are to quantify nitrous oxide (N 2 O) emission from intensively managed grasslands in the Netherlands, to increase the insight in the factors controlling N 2 O emission from intensively managed grasslands and to explore

  12. 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

  13. 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...

  14. Management of water resources for grasslands

    Science.gov (United States)

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

  15. Effect of four plant species on soil 15N-access and herbage yield in temporary agricultural grasslands

    DEFF Research Database (Denmark)

    Pirhofer-Walzl, Karin; Eriksen, J.; Rasmussen, Jesper

    2013-01-01

    Abstract Background and aims We carried out field experiments to investigate if an agricultural grassland mixture comprising shallow- (perennial ryegrass: Lolium perenne L.; white clover: Trifolium repens L.) and deep- (chicory: Cichorium intybus L.; Lucerne: Medicago sativa L.) rooting grassland...... species has greater herbage yields than a shallow-rooting two-species mixture and pure stands, if deep-rooting grassland species are superior in accessing soil 15N from 1.2 m soil depth compared with shallow-rooting plant species and vice versa, if a mixture of deep- and shallow-rooting plant species has......-access of pure stands, two-species and four-species grassland communities. Results Herbage yield and soil 15N-access of the mixture including deep- and shallow-rooting grassland species were generally greater than the pure stands and the two-species mixture, except for herbage yield in pure stand lucerne...

  16. Experience with fermentation of grass and grass silage from extensively used grassland. Feasibility study on monofermentation of grass silage from contaminated sites - biomass from grasslands of the Elbe dyke foreland; Betriebserfahrungen mit der Vergaerung von Gras und Grassilagen von extensiv genutztem Gruenland. Machbarkeitsuntersuchung zur Monovergaerung von Grassilagen schadstoffkontaminierter Standorte am Beispiel der eingesetzten Biomasse von Gruenlandflaechen aus dem Deichvorland der Elbe

    Energy Technology Data Exchange (ETDEWEB)

    Heuer, Hans-Juergen [Landwirtschaftskammer Niedersachsen, Bezirksstelle Uelzen (Germany)

    2011-07-01

    This feasibility study was concluded in 2011; monofermentation of grass silage from contaminated sites of the Elbe dyke foreland was investigated. It was found that a biogas operated in monofermentation of grass silage from extensively used grasslands is technically and economically feasible in batch operation. It was also shown that the fermentation residue can be used as agricultural fertilizer, provided that it is first turned in a compost turning unit and then worked into the soil. In view of the high pollutant concentration of the soils in the Elbe dyke foreland, the results of the project give the agricultural businesses in the Elbe valley grasslands an alternative use of the land. [German] Die Machbarkeitsuntersuchung zur Monovergaerung von Grassilagen schadstoffkontaminierter Standorte am Beispiel der eingesetzten Biomasse von Gruenlandflaechen aus dem Deichvorland der Elbe wurde Anfang Mai 2011 abgeschlossen. Im Ergebnis wurde herausgearbeitet, dass sich eine Biogaslage im Monovergaerungsverfahren mit ausschliesslich nur Grassilagen von extensiv gefuehrten Gruenlandflaechen technisch und wirtschaftlich in einer Batch-Anlage betreiben laesst. Auch wurde der Nachweis gefuehrt, dass die Biomasse aus dem Deichvorland der Elbe als Gaerrest auf das Gruenland im Deichvorland unter Beruecksichtigung von naturschutzfachlichen Vorgaben und nach den Vorgaben der guten fachlichen Praxis beim Duengen zurueckgefuehrt werden kann. Vor einer Aufbringung auf dem Gruenland sollte der feste Gaerrest jedoch mit einem Kompost-Umsetzer aufbereitet werden. Nach dem Ausstreuen auf dem Gruenland ist der Gaerrest mit einer Wiesenschleppe einzureiben. Vor dem Hintergrund der hohen Schadstoffbelastung der Boeden im Deichvorland der Elbe, tragen die im Projekt erarbeiteten Ergebnisse dazu bei, den landwirtschaftlichen Betriebsleitern in der Elbtalaue eine alternative Nutzung zur bisherigen Lebensmittelproduktion unterbreiten zu koennen.

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

    Science.gov (United States)

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

    2017-01-01

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

  18. 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.

  19. Carbon storage of Mediterranean grasslands

    Directory of Open Access Journals (Sweden)

    Corona, Piermaria

    2016-06-01

    Full Text Available Secondary grasslands are one of the most common vegetation types worldwide. In Europe, and in the Mediterranean basin, human activities have transformed many woodlands into secondary grasslands. Despite their recognized role in the global carbon cycle, very few data are available for estimating the biomass of Mediterranean grasslands. We developed linear regression models in order to predict the biomass of two native Mediterranean grasses (Ampelodesmos mauritanicus and Hyparrhenia hirta and an invasive alien grass (Pennisetum setaceum. Ampelodesmos mauritanicus is very common throughout the Mediterranean basin, mostly on north-facing slopes, H. hirta characterizes thermo-xeric grasslands, while P. setaceum is an alien species that is rapidly spreading along coastal areas. The measured morphometric attributes of individual plants as potential predictors were considered. The validation results corroborate the ability of the established models to predict above ground and total biomass of A. mauritanicus and P. setaceum. We also evaluated the total biomass per hectare for each species. The highest biomass per hectare was found for A. mauritanicus, whereas biomass was higher for H. hirta than for P. setaceum. The replacement of H. hirta by P. setaceum may reduce the total carbon storage in the ecosystem; however, P. setaceum allocates more resources to the roots, thus increasing the more stable and durable pool of carbon in grasslands.Los pastizales secundarios son uno de los tipos de vegetación más comunes en todo el mundo. En Europa y en la cuenca mediterránea, las actividades humanas han transformado muchos bosques en pastizales secundarios. A pesar de su reconocido papel en el ciclo global del carbono, hay muy pocos datos disponibles para la estimación de la biomasa de los pastizales mediterráneos. Hemos desarrollado modelos de regresión lineal con el fin de predecir la biomasa de dos gramíneas nativas del Mediterráneo (Ampelodesmos

  20. Seniors' and People with Disabilities' Experiences with Mandatory Medicaid Managed Care in California: Populations to Target for Additional Support during Transitions.

    Science.gov (United States)

    Graham, Carrie L; McDonnell, Diana D

    2016-01-01

    With more states moving people with disabilities and complex care needs into managed care, it is important to target beneficiaries for additional anticipated support before specific needs arise. In a survey of 1,521 seniors and people with disabilities in California who moved into Medicaid managed care six-16 months previously, the majority reported neutral or positive experiences with managed care continuity, access, and quality, compared with fee-for-service. Beneficiaries most likely to have negative experiences included those with poor self-rated health, functional impairment, cognitive impairment, frequent ED visits, and claims for back / osteoarthritis and cancer. Those with no specialty visits and those who had been continuously enrolled in Medicaid longer term before the transition also were more likely to report negative experiences. These populations can be targeted for assistance by health plans and Medicaid agencies. More specialty visits and longer time in Medicaid managed care also seems to improve beneficiaries' experiences.

  1. 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…

  2. 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…

  3. Grasslands, Invertebrates, and Precipitation: A Review of the Effects of Climate Change.

    Science.gov (United States)

    Barnett, Kirk L; Facey, Sarah L

    2016-01-01

    Invertebrates are the main components of faunal diversity in grasslands, playing substantial roles in ecosystem processes including nutrient cycling and pollination. Grassland invertebrate communities are heavily dependent on the plant diversity and production within a given system. Climate change models predict alterations in precipitation patterns, both in terms of the amount of total inputs and the frequency, seasonality and intensity with which these inputs occur, which will impact grassland productivity. Given the ecological, economic and biodiversity value of grasslands, and their importance globally as areas of carbon storage and agricultural development, it is in our interest to understand how predicted alterations in precipitation patterns will affect grasslands and the invertebrate communities they contain. Here, we review the findings from manipulative and observational studies which have examined invertebrate responses to altered rainfall, with a particular focus on large-scale field experiments employing precipitation manipulations. Given the tight associations between invertebrate communities and their underlying plant communities, invertebrate responses to altered precipitation generally mirror those of the plants in the system. However, there is evidence that species responses to future precipitation changes will be idiosyncratic and context dependent across trophic levels, challenging our ability to make reliable predictions about how grassland communities will respond to future climatic changes, without further investigation. Thus, moving forward, we recommend increased consideration of invertebrate communities in current and future rainfall manipulation platforms, as well as the adoption of new technologies to aid such studies.

  4. 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 (Prabbit 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 (Prabbit 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 experiments 1, 2 and 3, respectively. The highest growth rate was obtained on the sainfoin grassland despite lower concentrate supplementation. Thus, it seems possible to reduce complete feed supplementation without reducing animal performance. This possibility requires improving

  5. Evidence for Recent Invasion of Historically Resistant Chaparral Shrublands to Grasslands

    Science.gov (United States)

    Park, I.; Jenerette, D.; Hooper, J.

    2015-12-01

    Although historically resistant to invasion and type-conversion, there are strong indications that native shrublands in southern California are often increasingly degraded, and in many cases have begun transitioning into herbaceous grasslands. Chaparral shrublands in particular, which are characterized by a closed evergreen canopy composed of multiple species, represent a critical habitat for many native fauna and also play a significant role in soil stabilization and water partitioning throughout much of Southern California. However, in response to interactive global changes, these ecosystems may be transitioning into invasive-dominated deciduous grasslands. Through the use of a novel, phenology-driven vegetation classification, we examine the extent of such type-conversions through analysis of increases in seasonal changes (i.e. deciduousness). Estimates of phenological variation in greenness (NDVI) developed through analysis of Landsat 4-8 imagery were calibrated to observed seasonal NDVI variation as developed through high-resolution ground-based imagery platforms to develop estimates in the change of percent cover by evergreen shrubs and drought-deciduous herbs and grasses. This study evaluates long-term changes in invasive cover from 1985 through 2011. These analyses indicate substantial type-conversion of native chaparral over this period, as with differences in local elevation representing the dominant factor in the degree of long-term type-conversion at broad landscape-scales, with high elevation sites being the least susceptible to type conversion from chaparral to invaded grassland.

  6. Plant species richness promotes soil carbon and nitrogen stocks in grasslands without legumes

    NARCIS (Netherlands)

    Cong, W.; Ruijven, van J.; Mommer, L.; Deyn, de G.B.; Berendse, F.; Hoffland, E.

    2014-01-01

    1.The storage of carbon (C) and nitrogen (N) in soil is important ecosystem functions. Grassland biodiversity experiments have shown a positive effect of plant diversity on soil C and N storage. However, these experiments all included legumes, which constitute an important N input through

  7. "Picturing the Past": Farm Women on the Grasslands Frontier, 1850-1900

    Science.gov (United States)

    Sundberg, Sara Brooks

    2010-01-01

    This study analyzes fifty-two accounts by pioneer farm women from a less well known part of the U.S. grasslands, the Minnesota prairie between 1850 and 1900. Using Hamlin Garland's frequently cited description of his mother's experience as a baseline for comparison to Minnesota farm women's experiences, this study finds that pioneer farm women…

  8. The rise of C4 grassland ecosystems, a climate puzzle

    Science.gov (United States)

    Henderson, A.; Fox, D.; Freeman, K. H.

    2011-12-01

    The expansion of grasslands was one of the most profound ecological changes in the Cenozoic. Understanding the history of forest to grassland transitions, and the development of C4 grasslands in particular, is critical for understanding the relationship between land surface climate feedbacks, seasonality, and temperature. Modern distributions and ecological experiments demonstrate a strong correlation between C4 biogeography and high growing season temperatures and precipitation, as well as low pCO2 concentrations. The rise of C4 grasses in North America, as documented by carbonate nodule and mammal teeth δ13C values, began during a warm period with relatively stable pCO2 in the late Miocene. Surprisingly, C4 grasses continued to expand and then rose to dominance in the Great Plains as climates progressively cooled, moisture availability increased, and ice sheets formed further north on the continent. To understand this seemingly paradoxical scenario, we need constraints on the rate and character of increasing abundances of C4 vegetation. To this end, we use molecular and isotopic tools from terrestrial plant leaf wax n-alkanes extracted from carbonate nodules in the Meade Basin, Kansas and sites in Texas for the past 12 Ma. These records offer site-specific reconstructions tied directly to vegetation source. We compare our results to published continental-scale reconstructions of n-alkanes from the Mississippi River drainage basin and to climate records. From the distribution of C27 to C33 n-alkane abundances and patterns in δ13C values, we infer that C4 grasses coexisted with patches of C3 vegetation, including both grasses and trees. C4 grasses increasingly dominated the landscape, reaching modern abundances as ice sheets were reaching their southern limit in North America. Our results confirm that C4 grasslands emerged under cool and wet conditions, something we would not predict based on modern analogues, raising questions about our understanding of the

  9. Modest enhancements to conventional grassland diversity improve the provision of pollination services.

    Science.gov (United States)

    Orford, Katherine A; Murray, Phil J; Vaughan, Ian P; Memmott, Jane

    2016-06-01

    Grassland for livestock production is a major form of land use throughout Europe and its intensive management threatens biodiversity and ecosystem functioning in agricultural landscapes. Modest increases to conventional grassland biodiversity could have considerable positive impacts on the provision of ecosystem services, such as pollination, to surrounding habitats.Using a field-scale experiment in which grassland seed mixes and sward management were manipulated, complemented by surveys on working farms and phytometer experiments, the impact of conventional grassland diversity and management on the functional diversity and ecosystem service provision of pollinator communities were investigated.Increasing plant richness, by the addition of both legumes and forbs, was associated with significant enhancements in the functional diversity of grassland pollinator communities. This was associated with increased temporal stability of flower-visitor interactions at the community level. Visitation networks revealed pasture species Taraxacum sp. (Wigg.) (dandelion) and Cirsium arvense (Scop.) (creeping thistle) to have the highest pollinator visitation frequency and richness. Cichorium intybus (L.) (chichory) was highlighted as an important species having both high pollinator visitation and desirable agronomic properties.Increased sward richness was associated with an increase in the pollination of two phytometer species; Fragaria × ananassa (strawberry) and Silene dioica (red campion), but not Vicia faba (broad bean). Enhanced functional diversity, richness and abundance of the pollinator communities associated with more diverse neighbouring pastures were found to be potential mechanisms for improved pollination. Synthesis and applications. A modest increase in conventional grassland plant diversity with legumes and forbs, achievable with the expertise and resources available to most grassland farmers, could enhance pollinator functional diversity, richness and abundance

  10. NPP Grassland: Hays, USA, 1970, R1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains three ASCII files (.txt format). Two files contain above- and below-ground biomass and productivity data for a mixed prairie grassland, one...

  11. Grassland Management Plan : Necedah National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This plan summarizes grassland management on Necedah NWR. A description, objectives, desired habitat conditions, management plans, and an evaluation are provided for...

  12. 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...

  13. 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

  14. 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.

  15. The Impact of Desertification in the Mongolian and the Inner Mongolian Grassland on the Regional Climate.

    Science.gov (United States)

    Xue, Yongkang

    1996-09-01

    This is an investigation of the impact of and mechanisms for biosphere feedback in the northeast Asian grassland on the regional climate. Desertification in the Inner Mongolian grassland has dramatically increased during the past 40 years. The Center for Ocean-Land-Atmosphere Studies atmospheric general circulation model, which includes a biosphere model, was used to test the impact of this desertification. In the grassland experiment, areas of Mongolia and Inner Mongolia were specified as grassland. In the desertification experiment, these areas were specified as desert. Each experiment consists of six integrations with different atmospheric initial conditions and different specifications of the extent of the desertification area. All integrations were 90 days in length, beginning in early June and continuing through August, coincident with the period of the East Asian summer monsoon.The desertification had a significant impact on the simulated climate. During the past 40 years, the observed rainfall has decreased in northern and southern China but increased in central China, and the Inner Mongolian grassland and northern China have become warmer. The simulated rainfall and surface temperature differences between the desertification integrations and the grassland integrations are consistent with these observed changes.The water balance and surface energy balance were altered by the desertification. The reduction in evaporation in the desertification experiment dominated the changes in the local surface energy budget. The reduction in convective latent beating above the surface layer enhanced sinking motion (or weakened rising motion) over the desertification area and over the adjacent area to the south. Coincidentally, the monsoon circulation was weakened and the rainfall was reduced.

  16. The role of human capital and learning in Mexican microenterprises: The experience of the state of Baja California

    Directory of Open Access Journals (Sweden)

    Martín Ramírez Urquidi

    2014-01-01

    Full Text Available This work aims at understanding the structure of human capital and learning in low value added microenterprises of Baja California and to determine the role of such factors in microenterprise performance, in order to establish a diagnosis on their contribution and get some public policy implications for the sector. The results confirm the importance of human capital on the performance of these businesses, since there is a relationship between human capital and performance as measured in different ways. The results also account for the heterogeneity in the distribution of microenterprise human capital among locations, sectors, types of business and sex.

  17. [Differences in soil respiration between cropland and grassland ecosystems and factors influencing soil respiration on the Loess Plateau].

    Science.gov (United States)

    Zhou, Xiao-Gang; Zhang, Yan-Jun; Nan, Ya-Fang; Liu, Qing-Fang; Guo, Sheng-Li

    2013-03-01

    Understanding the effect of land-use change on soil respiration rates becomes critical in predicting soil carbon cycling under conversion of arable into grassland on the Loess Plateau. From July 2010 to December 2011, CO2 efflux from the soil surface was measured between 08:00 to 10:00 am in clear days by a Licor-8100 closed chamber system (Li-COR, Lincoln, NE, US). Also, soil temperature and soil moisture at the 5-cm depth was measured using a Li-Cor thermocouple and a hand-held frequency-domain reflectometer (ML2x, Delta-T Devices Ltd, UK) at each PVC collar, respectively. We found marked differences (P < 0.05) in soil respiration related to different land-use: the mean cropland soil respiration [1.35 micromol x (m2 x s)(-1)] was 24% (P < 0.05) less than the paired grassland soil respiration [1.67 micromol x (m2 x s)(-1)] (P < 0.05) during the period of experiment and the cumulative CO2-C emissions in grassland (856 g x m(-2)) was 23% (P < 0.05) higher than that in cropland (694 g x m(-2)). Soil moisture from 0-5 cm depth was much drier in cropland and significantly different between cropland and grassland except for winter. However, there were no clear relationships between soil moisture and soil respiration. Soil temperature at 5-cm depth was 2.5 degress C higher in grassland during the period of experiment (P < 0.05). Regression of soil temperature vs. soil respiration indicated significant exponential relationships both in grassland and cropland. Besides, there were intrinsic differences in response of soil respiration to temperature between the cropland and grassland ecosystems: grassland and cropland respiration response was significantly different at the alpha = 0.05 level, also expressed by a higher temperature sensitivity of soil respiration (Q10) in cropland (2.30) relative to grassland (1.74). Soil temperature of cropland and grassland can explain 79% of the variation in the soil respiration in grassland, compared to 82% in cropland. Therefore, land

  18. 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.

  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. 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.

  1. 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.

  2. Madagascar's grasses and grasslands: anthropogenic or natural?

    Science.gov (United States)

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

    2016-01-01

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

  3. Occurrence of spray drift for different crop types: cereal, cereal stubble and grassland.

    Science.gov (United States)

    De Schampheleire, M; Nuyttens, D; Dekeyser, D; Verboven, P; Spanoghe, P

    2008-01-01

    Pesticide spray drift is affected by 4 main factors: weather conditions, spray application technique, physicochemical properties of the spray Liquid and surrounding characteristics. This research studied the importance of crop type being sprayed for drift occurrence. Drift experiments were performed over cereals, cereal stubbles and grassland according to the international standard ISO 22866. From the results it was found that drift occurrence in cereals and cereal stubbles was lower than drift occurrence in grassland. The differences between cereals and cereal stubbles were significant only at low wind speed.

  4. 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.

  5. 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

    While the effect of disturbance on overall abundance and community composition of arbuscular mycorrhizal (AM) fungi has been researched in agricultural fields, less is known about the impact in semi-natural grasslands. We sampled two AM plant species, Festuca brevipila and Plantago lanceolata, from...... 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...... the control or disturbed plots. We found no evidence of host preference in this system, except for one phylotype that preferentially seemed to colonize Festuca. Our results show that disturbance imposed a stronger structuring force for AM fungal communities than did host plants in this semi-natural grassland....

  6. 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.

  7. Grassland habitat monitoring plan [Sand Lake National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Sand Lake National Wildlife Refuge Grassland Habitat Management Plan provides vision and specific guidance on managing grassland habitats for resources of...

  8. 2009 Field Season : Annual Grassland Vegetation Monitoring : Summary

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — An annual grassland monitoring plan was initiated on the grassland units at Bear River Migratory Bird Refuge during the 2009 field season. The annual monitoring plan...

  9. Grassland Management Plan Union Slough National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Northern Tallgrass Prairie is an endangered ecosystem, and in turn, grassland dependent birds and some forbs are in serious peril. The Grassland Management Plan...

  10. Grassland Management Plan : Swan Lake National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Grassland Management Plan for Swan Lake National Wildlife Refuge provides an overview of the Refuge, a list of special considerations affecting grassland...

  11. California Air Basins

    Data.gov (United States)

    California Department of Resources — Air ResourcesCalifornia Air Resources BoardThe following datasets are from the California Air Resources Board: * arb_california_airbasins - California Air BasinsThe...

  12. Biodiversity loss in grasslands : consequences for ecosystem functioning and interactions with above- and belowground organisms

    NARCIS (Netherlands)

    Ruijven, van J.

    2005-01-01

    Considering the current rate of extinctions, it is crucial to understand the consequences of these losses of biodiversity for the functioning of ecosystems. Grasslands proved a very suitable ecosystem for biodiversity-ecosystem functioning research.In earlier experiments,

  13. 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

  14. Contrasting above- and belowground sensitivity of three Great Plains grasslands to altered rainfall regimes

    Science.gov (United States)

    To assess primary productivity responses to increases in precipitation amount and altered rainfall patterns, we conducted an experiment in 2011 and 2012 in shortgrass prairie (SGP; C4 dominated; Central Plains Experimental Grassland), northern mixed grass prairie (NMP; C3 dominated; Fort Keogh Lives...

  15. 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...

  16. Effect of seed mixture composition and management on competitiveness of herbs in temporary grasslands

    DEFF Research Database (Denmark)

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

    2012-01-01

    In multispecies grasslands the proportion of different herb species may vary considerably due to low competitiveness of some herbs. To examine the possibility for increasing the competitiveness, an experiment with three factors was set up: 1) amount of herb seed (5, 50 or 100%) in a mixture...

  17. Identifying and Addressing Genetic Counseling Challenges among Indigenous People of Oaxaca-One Center's Experience with Two Immigrant Farmworker Families in the Central Valley of California.

    Science.gov (United States)

    Shen, Joseph J; Carmichael, Jason; Vásquez Santos, Leoncio

    2018-02-03

    An important aspect of genetic counseling is the recognition of and adaptation to the socio-cultural uniqueness of the different populations that a genetics clinic serves. The Central Valley of California is home to a large population from Mexico, with a significant proportion of indigenous ancestry originating from the state of Oaxaca. We report on our experience with two families of this community-one extended family with an early lethal inborn error of metabolism and the other with a chronic disfiguring form of ichthyosis. We identified multiple important factors that needed to be considered, including the matching of language dialects, adaptation to different social interaction conventions, acknowledgement of traditional medicine beliefs, and effective transmission of genetic terms and concepts, all of which should be incorporated into the interactions with these families when aiming to provide comprehensive genetic counseling.

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

    Science.gov (United States)

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

    2014-01-01

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

  19. 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.

  20. Ungulate vs. landscape control of soil C and N processes in grasslands of Yellowstone National Park

    Energy Technology Data Exchange (ETDEWEB)

    Frank, D.A. [Syracuse Univ., NY (United States). Biological Research Labs.; Groffman, P.M. [Inst. of Ecosystem Studies, Millbrook, NY (United States)

    1998-10-01

    Within large grassland ecosystems, climatic and topographic gradients are considered the primary controls of soil processes. Ungulates also can influence soil dynamics; however the relative contribution of large herbivores to controlling grassland soil processes remains largely unknown. In this study, the authors compared the effects of native migratory ungulates and variable site (landscape) conditions, caused by combined climatic and topographic variability, on grassland of the northern winter range of Yellowstone National Park by determining soil C and N dynamics inside and outside 33--37 yr exclosures at seven diverse sites. Sites included hilltop, slope, and slope bottom positions across a climatic gradient and represented among the driest and wettest grasslands on the northern winter range. The authors performed two experiments: (1) a 12-mo in situ net N mineralization study and (2) a long-term (62-wk) laboratory incubation to measure potential N mineralization and microbial respiration. Results from the in situ experiment indicated that average net N mineralization among grazed plots was double that of fenced, ungrazed plots (1.9 g N{center_dot}m{sup {minus}2}{center_dot}yr{sup {minus}1}). Mean grazer enhancement of net N mineralization across sites (1.9 g N{center_dot}m{sup {minus}2}{center_dot}yr{sup {minus}1}), approached the maximum difference in net N mineralization among fenced plots (2.2 g N{center_dot}m{sup {minus}2}{center_dot}yr{sup {minus}1}), i.e., the greatest landscape effect observed. Furthermore, ungulates substantially increased between-site variation in mineralization; grazed grassland, 1 SD = 2.2 g N{center_dot}m{sup {minus}2}{center_dot}yr{sup {minus}1}, fenced grassland, 1 SD = 0.85 g N{center_dot}m{sup {minus}2}{center_dot}yr{sup {minus}1}.

  1. 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.

  2. 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

  3. Greenhouse gas fluxes over Central European grasslands

    Science.gov (United States)

    Hörtnagl, L. J.; Bahn, M.; Barthel, M.; Eugster, W.; Klumpp, K.; Ladreiter-Knauss, T.; Merbold, L.; Wohlfahrt, G.; Buchmann, N. C.

    2014-12-01

    The uptake of carbon dioxide (CO2) by grassland ecosystems can be offset by the concurrent emission of the greenhouse gases methane (CH4) and nitrous oxide (N2O) in terms of CO2-equivalents. As a consequence, CH4 and N2O emissions can contribute to an increase of the global warming potential (GWP) of the respective study site. For a full assessment of the climatic impact of grassland ecosystems it is therefore necessary to quantify fluxes of these two compounds in combination with CO2 exchange. Since agricultural management practices and land use change at a given site can have a strong impact on annual CH4 and N2O budgets, both compounds are a frequent topic of discussion when planning GHG mitigation strategies.Here we present an overview of the GHG exchange of eight managed Central European grassland sites along a gradient of elevation and land use intensity. Fluxes of the three major GHGs CO2, CH4 and N2O were quantified using the eddy covariance or chamber technique. The grasslands differed with regard to the amount of fertilizer input, frequency of cuts and grazing duration and intensity, ranging from more intensively managed to very lightly managed and abandoned grassland. In this presentation we focus on time periods when measurements of all three compounds were available for all sites. We investigate common features among observed CH4 and N2O exchange patterns at the different grassland sites in relation to management activities and concurrently measured biotic / abiotic parameters. In addition, we evaluate the impact of CH4 and N2O fluxes on the annual GWP of field sites for which long-term measurements are available.

  4. Grassland renovation in the Netherlands; agronomic, environmetal and economic issues

    NARCIS (Netherlands)

    Schils, R.L.M.; Aarts, H.F.M.; Bussink, D.W.; Conijn, J.G.; Corre, V.J.; Dam, van A.M.; Hoving, I.E.; Meer, van der H.G.; Velthof, G.L.

    2007-01-01

    Experimental studies into the effects of grassland renovation on environmental and agronomic parameters are scarce in the Netherlands. The effects of grassland renovation have been estimated for the three cases of permanent grassland on sand, clay and peat soil, and an additional case for a

  5. 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

  6. 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...

  7. 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 ...

  8. Negative global phosphorus budgets challenge sustainable intensification of grasslands

    NARCIS (Netherlands)

    Sattari, S.Z.; Bouwman, A.F.|info:eu-repo/dai/nl/090428048; Rodríquez, R. Martinez; Beusen, A.H.W.|info:eu-repo/dai/nl/109357302; van Ittersum, M.K.

    2016-01-01

    Grasslands provide grass and fodder to sustain the growing need for ruminant meat and milk. Soil nutrients in grasslands are removed through withdrawal in these livestock products and through animal manure that originates from grasslands and is spread in croplands. This leads to loss of soil

  9. Negative global phosphorus budgets challenge sustainable intensification of grasslands

    NARCIS (Netherlands)

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

    2016-01-01

    Grasslands provide grass and fodder to sustain the growing need for ruminant meat and milk. Soil nutrients in grasslands are removed through withdrawal in these livestock products and through animal manure that originates from grasslands and is spread in croplands. This leads to loss of soil

  10. 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...... target. Species richness and functional diversity both increased in response to soil disturbance, and rotavation, but not ploughing, had a persistent positive effect on the occurrence of specialist species of calcareous sandy grassland. However, no type of soil disturbance caused the plant species...

  11. 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.

  12. Nest defense- Grassland bird responses to snakes

    Science.gov (United States)

    Ellison, Kevin S.; Ribic, Christine

    2012-01-01

    Predation is the primary source of nest mortality for most passerines; thus, behaviors to reduce the impacts of predation are frequently quantified to study learning, adaptation, and coevolution among predator and prey species. Video surveillance of nests has made it possible to examine real-time parental nest defense. During 1999-2009, we used video camera systems to monitor 518 nests of grassland birds. We reviewed video of 48 visits by snakes to 34 nests; 37 of these visits resulted in predation of active nests. When adult birds encountered snakes at the nest (n = 33 visits), 76% of the encounters resulted in a form of nest defense (nonaggressive or aggressive); in 47% of the encounters, birds physically struck snakes. When defending nests, most birds pecked at the snakes; Eastern Meadowlarks (Sturnella magna) and Bobolinks (Dolichonyx oryzivorus) pecked most frequently in anyone encounter. Also, two Eastern Meadowlarks ran around snakes, frequently with wings spread, and three Bobolinks struck at snakes from the air. Nest defense rarely appeared to alter snake behavior; the contents of seven nests defended aggressively and two nests defended nonaggressively were partially depredated, whereas the contents of six nests defended each way were consumed completely. One fledgling was produced at each of three nests that had been aggressively defended. During aggressive defense, one snake appeared to be driven away and one was wounded. Our findings should be a useful starting point for further research. For example, future researchers may be able to determine whether the behavioral variation we observed in nest defense reflects species differences, anatomic or phylogenetic constraints, or individual differences related to a bird's prior experience. There appears to be much potential for studying nest defense behavior using video recording of both real and simulated encounters. 

  13. Grassland biodiversity bounces back from long-term nitrogen addition.

    Science.gov (United States)

    Storkey, J; Macdonald, A J; Poulton, P R; Scott, T; Köhler, I H; Schnyder, H; Goulding, K W T; Crawley, M J

    2015-12-17

    The negative effect of increasing atmospheric nitrogen (N) pollution on grassland biodiversity is now incontrovertible. However, the recent introduction of cleaner technologies in the UK has led to reductions in the emissions of nitrogen oxides, with concomitant decreases in N deposition. The degree to which grassland biodiversity can be expected to 'bounce back' in response to these improvements in air quality is uncertain, with a suggestion that long-term chronic N addition may lead to an alternative low biodiversity state. Here we present evidence from the 160-year-old Park Grass Experiment at Rothamsted Research, UK, that shows a positive response of biodiversity to reducing N addition from either atmospheric pollution or fertilizers. The proportion of legumes, species richness and diversity increased across the experiment between 1991 and 2012 as both wet and dry N deposition declined. Plots that stopped receiving inorganic N fertilizer in 1989 recovered much of the diversity that had been lost, especially if limed. There was no evidence that chronic N addition has resulted in an alternative low biodiversity state on the Park Grass plots, except where there has been extreme acidification, although it is likely that the recovery of plant communities has been facilitated by the twice-yearly mowing and removal of biomass. This may also explain why a comparable response of plant communities to reduced N inputs has yet to be observed in the wider landscape.

  14. 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...

  15. Land use affects the resistance and resilience of carbon dynamics of mountain grassland to extreme drought

    Science.gov (United States)

    Ingrisch, Johannes; Karlowsky, Stefan; Hasibeder, Roland; Anadon-Rosell, Alba; Augusti, Angela; Scheld, Sarah; König, Alexander; Gleixner, Gerd; Bahn, Michael

    2015-04-01

    Climatic extremes like droughts are expected to occur more frequently and to be more severe in a future climate and have been shown to strongly affect the carbon (C) cycle. Few studies have so far explored how the management intensity of ecosystems and land-use changes alter C cycle responses to extreme climatic events. In many mountain areas land-use changes have been taking place at a rapid pace and have altered plant species composition and biogeochemical cycles. It is still unknown whether and how abandonment of mountain grasslands affects the resistance and the resilience of carbon dynamics to extreme drought. We carried out an in situ experiment to test the hypothesis that abandonment increases the resistance of grassland C dynamics to extreme drought, but decreases its resilience (i.e. post-drought recovery). In a common garden experiment at a mountain meadow in the Austrian Central Alps we exposed large intact monoliths from the meadow and a nearby abandoned grassland to extreme drought conditions during the main growth period in late spring. We measured above- and belowground productivity and net ecosystem exchange and its components over the course of the drought and during the recovery to assess and quantify their resistance and resilience. Furthermore, we analysed the coupling of the two major ecosystem CO2 fluxes, photosynthesis and soil respiration, as based on 13CO2 pulse labelling campaigns at peak drought and during post-drought recovery using isotope laser spectroscopy. Four weeks of early season drought induced a strong decrease of aboveground biomass at the mountain meadow, whereas no effect was observed for the abandoned grassland. At peak drought gross primary productivity was reduced at both grasslands compared to the respective controls, but with a stronger decrease at the meadow (80%) compared to the abandoned grassland (60%). The same pattern was observed for ecosystem respiration. However, the effect was less pronounced compared to carbon

  16. Water and Productivity of Floodplain Grasslands: Exploring Linkages through Experimentations and Models in the Tana River Delta, Kenya

    Science.gov (United States)

    Leauthaud, C.; Musila, W.; Kergoat, L.; Hiernaux, P.; Manuela, G.; Duvail, S.

    2014-12-01

    Floodplain grasslands have one of the highest productivities of non-cultivated ecosystems on Earth. They procure a wide variety of benefits to human beings. In Eastern Africa, grasslands of Echinochloa stagnina are primordial for pastoralists as highly productive dry-season grazing zones. Regular flooding is a critical property in maintaining their productivity and resulting services. Yet, construction of hydrologic infrastructure modifies the flooding regime of rivers and the consequences on downstream floodplain grasslands need to be assessed. This presentation focuses on quantifying the productivity of the floodplain grasslands in the Tana River Delta, Kenya, in order to assess potential changes under varying flooding regimes. The interactions between growth and floods are explored firstly at an experimental site, then through the construction of a process-based plant growth model adapted to floodplain grasslands. The 15-month experiment consisted in quantifying daily growth rates under various rainfall, irrigation, cutting and flooding regimes . Floods increased growth rates three-folds, and high productivities were maintained after the floods. The cutting regime and contribution of non-flood water also influenced productivity. Modelling allowed exploring the underlying processes explaining such behaviour. In an exploratory endeavour, the productivity of the grassland at the ecosystem scale was assessed with the model for a variety of flood and non-flooded scenarios. Decreasing floods led to a drop in annual productivity that could have serious consequences for the livestock keeping activities of the zone. This research highlights the importance of floods in the maintenance of high productivities for a floodplain grassland typical of East Africa, and maybe of the Sahelian band. The model, once further validated, could be used on other floodplain grasslands, such as those of the Niger delta. Results for the Tana River Delta would need to be discussed with the

  17. Evidence of physiological decoupling from grassland ecosystem drivers by an encroaching woody shrub.

    Directory of Open Access Journals (Sweden)

    Jesse B Nippert

    Full Text Available Shrub encroachment of grasslands is a transformative ecological process by which native woody species increase in cover and frequency and replace the herbaceous community. Mechanisms of encroachment are typically assessed using temporal data or experimental manipulations, with few large spatial assessments of shrub physiology. In a mesic grassland in North America, we measured inter- and intra-annual variability in leaf δ(13C in Cornus drummondii across a grassland landscape with varying fire frequency, presence of large grazers and topographic variability. This assessment of changes in individual shrub physiology is the largest spatial and temporal assessment recorded to date. Despite a doubling of annual rainfall (in 2008 versus 2011, leaf δ(13C was statistically similar among and within years from 2008-11 (range of -28 to -27‰. A topography*grazing interaction was present, with higher leaf δ(13C in locations that typically have more bare soil and higher sensible heat in the growing season (upland topographic positions and grazed grasslands. Leaf δ(13C from slopes varied among grazing contrasts, with upland and slope leaf δ(13C more similar in ungrazed locations, while slopes and lowlands were more similar in grazed locations. In 2011, canopy greenness (normalized difference vegetation index - NDVI was assessed at the centroid of individual shrubs using high-resolution hyperspectral imagery. Canopy greenness was highest mid-summer, likely reflecting temporal periods when C assimilation rates were highest. Similar to patterns seen in leaf δ(13C, NDVI was highest in locations that typically experience lowest sensible heat (lowlands and ungrazed. The ability of Cornus drummondii to decouple leaf physiological responses from climate variability and fire frequency is a likely contributor to the increase in cover and frequency of this shrub species in mesic grassland and may be generalizable to other grasslands undergoing woody encroachment.

  18. 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

  19. Protecting Mongolia's grassland steppes | IDRC - International ...

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

    2011-07-13

    Jul 13, 2011 ... For centuries, Mongolia's herders were nomadic, roaming what is the world's biggest natural grassland in search of pastures for their animals — an approach that was environmentally sustainable. There was common access to land, and the herders lived in harmony with nature in this fragile and dry ...

  20. Structure and Processes in Temperate Grassland Vegetation

    DEFF Research Database (Denmark)

    Ejrnæs, R.

    In Denmark, the grass greens in late March. Perhaps that is the reason why early spring is so well suited to classify grasslands according to conservation value by their colour. When there is no interference by summer drought and autumn litter, a marked difference can be observed between the unif......In Denmark, the grass greens in late March. Perhaps that is the reason why early spring is so well suited to classify grasslands according to conservation value by their colour. When there is no interference by summer drought and autumn litter, a marked difference can be observed between...... the uniform bluish green colour of a monotonous rye grass sward with white clover and scattered weeds and the yellowish green colour of seminatural grasslands covered in pleurocarpic mosses and harbouring a diverse array of plant, fungi and insect species. Later, you will maybe also discover how to find...... the rare species belonging to the fungal genera of Hygrocybe, Entoloma and Clavaria. These occur almost exclusively in the yellowish green, unimproved grasslands, but not everywhere so. In the summer, it is often possible to see that the grass is greener in some parts of a slope or in a hollow...

  1. Environmental modifications for improved grassland production ...

    African Journals Online (AJOL)

    The most important environmental limitations to grassland production are set by the moisture regime, the physiography, soil conditions, temperature, vegetation present, entomological and microbiological factors of the environment. The significant features of these factors are discussed. Modification which can be applied to ...

  2. [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.

  3. Carbon sink activity of managed grasslands

    Science.gov (United States)

    Klumpp, Katja; Chabbi, Abad; Gastal, Francois; Senapati, Nimai; Charrier, Xavier; Darsonville, Olivier; Creme, Alexandra

    2017-04-01

    In agriculture, a large proportion of GHG emission saving potential may be achieved by means of soil C sequestration. Recent demonstrations of carbon sink activities however, often questioned the existence of C storing grasslands, as uncertainty surrounding estimates are often larger than the sink itself. Besides climate, key components of the carbon sink activity in grasslands are type and intensity of management practices. Here, we analysed long term data on C flux and soil organic carbon stocks for two long term (>13yrs) national observation sites in France (SOERE-ACBB). These sites comprise a number of grassland fields and managements options (i.e. permanent, sowing, grazing, mowing, and fertilization) offering an opportunity to study carbon offsets (i.e. compensation of CH4 and N2O emissions), climatic-management interactions and trade-offs concerning ecosystem services (e.g. production). Furthermore, for some grassland fields, the carbon sink activity was compared using two methods; repeated soil inventory and estimation of the ecosystem C budget by continuous measurement of CO2 exchange (i.e. eddy covariance) in combination with quantification of other C imports and exports, necessary to estimate net C storage. In general grasslands, were a potential sink of C (i.e. net ecosystem exchange, NEE), where grazed sites had lower NEE compared the cut site. However, when it comes to net C storage (NCS), mowing reduced markedly potential sink leading to very low NCS compared to grazed sites. Including non-CO2 fluxes (CH4 and N2O emission) in the budget, revealed that GHG emissions were offset by C sink activity.

  4. Mineral Fertilization with UAN on Natural Grassland Festuca rubra L. with Agrostis capillaries L.

    Directory of Open Access Journals (Sweden)

    Ioan Rotar

    2016-11-01

    Full Text Available An important part of efficient livestock production is ensuring the sufficient grass for hay and pasture. However, low soil nutrient levels often limit forage production. With good fertilizer management and soil fertility, the productivity of many hay and pasture fields can be greatly improved. Through good fertilizer management, the productivity of many hay and pasture fields can be significantly improved by Ross H. McKenzie (2005. The aim of this paper was the effect of fertilization with liquid fertilizer (UAN the harvest of dry and floristic composition changing on natural grassland. The experiment whose results we present was placed in 2014 in the place in Baisoara Mountain village, Cluj County. Experience has been placed on the Festuca rubra and Agrostis capillaries - of grassland type. The natural grassland of Festuca rubra with Agrostis capillaries responded very well to mineral fertilizers with liquid fertilizer UAN. The floristic composition of natural grassland fertilized with liquid fertilizers based on nitrogen, it can be seen an increase the Gramineae families and an evidence downward trend from Fabaceae families.

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

    Energy Technology Data Exchange (ETDEWEB)

    Borer, Elizabeth T. [Department of Ecology, Evolution, and Behavior, University of Minnesota; et al, et al

    2014-01-01

    Human alterations to nutrient cycles1,2 and herbivore communities3–7 are affecting global biodiversity dramatically2. 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 systems8,9. 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.

  6. Drought resistance across California ecosystems: Evaluating changes in carbon dynamics using satellite imagery

    Science.gov (United States)

    Sparkle L. Malone; Mirela G. Tulbure; Antonio J. Perez-Luque; Timothy J. Assal; Leah L. Bremer; Debora P. Drucker; Vicken Hillis; Sara Varela; Michael L. Goulden

    2016-01-01

    Drought is a global issue that is exacerbated by climate change and increasing anthropogenic water demands. The recent occurrence of drought in California provides an important opportunity to examine drought response across ecosystem classes (forests, shrublands, grasslands, and wetlands), which is essential to understand how climate influences ecosystem structure and...

  7. Effects of management of ecosystem carbon pools and fluxes in grassland ecosystems

    Science.gov (United States)

    Ryals, R.; Silver, W. L.

    2010-12-01

    Grasslands represent a large land-use footprint and have considerable potential to sequester carbon (C) in soil. Climate policies and C markets may provide incentives for land managers to pursue strategies that optimize soil C storage, yet we lack robust understanding of C sequestration in grasslands. Previous research has shown that management approaches such as organic amendments or vertical subsoiling can lead to larger soil C pools. These management approaches can both directly and indirectly affect soil C pools. We used well-replicated field experiments to explore the effects of these management strategies on ecosystem C pools and fluxes in two bioclimatic regions of California (Sierra Foothills Research and Extension Center (SFREC) and Nicasio Ranch). Our treatments included an untreated control, compost amendments, plowed (vertical subsoil), and compost + plow. The experiment was conducted over two years allowing us to compare dry (360 mm) and average (632 mm) rainfall conditions. Carbon dioxide (CO2) fluxes were measured weekly using a LI-8100 infrared gas analyzer. Methane (CH4) and nitrous oxide (N2O) fluxes were measured monthly using static flux chambers. Aboveground and belowground biomass were measured at the end of the growing season as an index of net primary productivity (NPP) in the annual plant dominated system. Soil moisture and temperature were measured continuously and averaged on hourly and daily timescales. Soil organic C and N concentrations were measured prior to the application of management treatments and at the ends of each growing season. Soils were collected to a 10 cm depth in year one and at four depth increments (0-10, 10-30, 30-50, and 50-100 cm) in year two. Soil C and N concentrations were converted to content using bulk density values for each plot. During both growing seasons, soil respiration rates were higher in the composted plots and lower in the plowed plots relative to controls at both sites. The effects on C loss via

  8. Grassland/atmosphere response to changing climate: Coupling regional and local scales. Final report

    Energy Technology Data Exchange (ETDEWEB)

    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{sub 3} temperate grasslands wig respond more strongly to elevated CO{sub 2} than temperate C{sub 4} grasslands in the short-term while a large positive N-PP response was predicted for a C{sub 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{sub 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{sub 2} GCM Simulations revealed relatively small differences.

  9. Differential sensitivity to regional-scale drought in six central US grasslands.

    Science.gov (United States)

    Knapp, Alan K; Carroll, Charles J W; Denton, Elsie M; La Pierre, Kimberly J; Collins, Scott L; Smith, Melinda D

    2015-04-01

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

  10. 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.

  11. Persistence of biological nitrogen fixation in high latitude grass-clover grasslands under different management practices

    Science.gov (United States)

    Tzanakakis, Vasileios; Sturite, Ievina; Dörsch, Peter

    2016-04-01

    Biological nitrogen fixation (BNF) can substantially contribute to N supply in permanent grasslands, improving N yield and forage quality, while reducing inorganic N inputs. Among the factors critical to the performance of BNF in grass-legume mixtures are selected grass and legume species, proportion of legumes, the soil-climatic conditions, in particular winter conditions, and management practices (e.g. fertilization and compaction). In high latitude grasslands, low temperatures can reduce the performance of BNF by hampering the legumés growth and by suppressing N2 fixation. Estimation of BNF in field experiments is not straightforward. Different methods have been developed providing different results. In the present study, we evaluated the performance of BNF, in a newly established field experiment in North Norway over four years. The grassland consisted of white clover (Trifolium repens L.) and red clover (Trifolium pretense L.) sawn in three proportions (0, 15 and 30% in total) together with timothy (Pheum pretense L.) and meadow fescue (Festuca pratensis L.). Three levels of compaction were applied each year (no tractor, light tractor, heavy tractor) together with two different N rates (110 kg N/ha as cattle slurry or 170 kg N/ha as cattle slurry and inorganic N fertilizer). We applied two different methods, the 15N natural abundance and the difference method, to estimate BNF in the first harvest of each year. Overall, the difference method overestimated BNF relative to the 15N natural abundance method. BNF in the first harvest was compared to winter survival of red and white clover plants, which decreased with increasing age of the grassland. However, winter conditions did not seem to affect the grassland's ability to fix N in spring. The fraction of N derived from the atmosphere (NdfA) in white and red clover was close to 100% in each spring, indicating no suppression of BNF. BNF increased the total N yield of the grasslands by up to 75%, mainly due to high

  12. Acidification of sandy grasslands - consequences for plant diversity

    DEFF Research Database (Denmark)

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

    2009-01-01

    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...... in south-eastern Sweden covered by xeric sand calcareous grasslands (EU habitat directive 6120). Methods: Soil and vegetation were investigated in most of the xeric sand calcareous grasslands in the Scania region (136 sample plots distributed over four or five major areas and about 25 different sites...... of soil P, placing a major constraint on primary productivity in sandy soils. Conclusions: Acidification of sandy grasslands leads to reduced abundance of desirable species, although the overall effect is rather weak between pH 5 and pH 9. Slopes are important for high diversity in sandy grasslands...

  13. 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.

  14. The economic value of grassland species for carbon storage.

    Science.gov (United States)

    Hungate, Bruce A; Barbier, Edward B; Ando, Amy W; Marks, Samuel P; Reich, Peter B; van Gestel, Natasja; Tilman, David; Knops, Johannes M H; Hooper, David U; Butterfield, Bradley J; Cardinale, Bradley J

    2017-04-01

    Carbon storage by ecosystems is valuable for climate protection. Biodiversity conservation may help increase carbon storage, but the value of this influence has been difficult to assess. We use plant, soil, and ecosystem carbon storage data from two grassland biodiversity experiments to show that greater species richness increases economic value: Increasing species richness from 1 to 10 had twice the economic value of increasing species richness from 1 to 2. The marginal value of each additional species declined as species accumulated, reflecting the nonlinear relationship between species richness and plant biomass production. Our demonstration of the economic value of biodiversity for enhancing carbon storage provides a foundation for assessing the value of biodiversity for decisions about land management. Combining carbon storage with other ecosystem services affected by biodiversity may well enhance the economic arguments for conservation even further.

  15. Forage herbs improve mineral composition of grassland herbage

    DEFF Research Database (Denmark)

    Pirhofer-Walzl, Karin; Søegaard, Karen; Jensen, Henning Høgh

    2011-01-01

    Provision of an adequate mineral supply in the diets of ruminants fed mainly on grassland herbage can present a challenge if mineral concentrations are suboptimal for animal nutrition. Forage herbs may be included in grassland seed mixtures to improve herbage mineral content, although there is li......Provision of an adequate mineral supply in the diets of ruminants fed mainly on grassland herbage can present a challenge if mineral concentrations are suboptimal for animal nutrition. Forage herbs may be included in grassland seed mixtures to improve herbage mineral content, although...

  16. Effects of leafy spurge infestation on grassland birds

    Science.gov (United States)

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

    2003-01-01

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

  17. 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

  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. Can selection on a male mating character result in evolutionary change? A selection experiment on California wild radish, Raphanus sativus.

    Science.gov (United States)

    Marshall, Diane L; Evans, Ann S

    2016-03-01

    Whenever more pollen grains arrive on stigmas than necessary to fertilize ovules, sexual selection is possible. However, the role of sexual selection remains controversial, in part because of lack of evidence on genetic bases of traits and the response of relevant characters to selection. In an experiment with Raphanus sativus, we selected on tendency to sire seeds in the stylar or basal regions of fruits. This character is likely related to pollen tube growth rate, and seed position affects rates of abortion and seed predation. We measured differences among families in seed siring and related characters and evaluated responses to selection. All replicates showed strong effects of pollen donor family on proportion of seeds sired per fruit in mixed pollinations. Most also showed effects of pollen donor family on number of pollen grains per flower and pollen diameter. Two of four replicates showed a response to selection on position of seeds sired. In responding replicates, we found trade-offs in pollen grain size and number; plants with larger pollen grains sired more seeds in the basal region. Our data suggest a genetic basis for pollen donor ability to sire seeds in competition. The significant response to selection in two replicates shows that position of seeds sired can respond to selection. Thus, all components for sexual selection to occur and affect traits are present. Variation in results among replicates might be due to changes in greenhouse conditions. Environmental effects may contribute to the maintenance of variation in these fitness-related characters. © 2016 Botanical Society of America.

  20. Regional variation in the temperature sensitivity of soil organic matter decomposition in China's forests and grasslands

    Science.gov (United States)

    Liu, Yuan; He, Nianpeng

    2017-04-01

    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.

  1. 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.

  2. Black-Tailed Prairie Dogs, Cattle, and the Conservation of North America?s Arid Grasslands

    OpenAIRE

    Sierra?Corona, Rodrigo; Davidson, Ana; Fredrickson, Ed L.; Luna-Soria, Hugo; Suzan-Azpiri, Humberto; Ponce-Guevara, Eduardo; Ceballos, Gerardo

    2015-01-01

    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 ...

  3. Leaf dry matter content predicts herbivore productivity, but its functional diversity is positively related to resilience in grasslands.

    Science.gov (United States)

    Pakeman, Robin J

    2014-01-01

    This paper addresses whether the ecosystem service of animal production from grasslands depends upon plant functional identity, plant functional diversity or if the resilience of production is a function of this diversity. Using the results of nine grazing experiments the paper shows that productivity is highly dependent on one leaf trait, leaf dry matter content, as well as rainfall. Animal (secondary) productivity is not dependent on plant functional diversity, but the variability in productivity of grasslands is related to the functional diversity of leaf dry matter content. This and a range of independent studies have shown that functional diversity is reduced at high levels of grassland productivity, so it appears that there is a trade-off between productivity and the resilience of productivity in the face of environmental variation.

  4. Leaf dry matter content predicts herbivore productivity, but its functional diversity is positively related to resilience in grasslands.

    Directory of Open Access Journals (Sweden)

    Robin J Pakeman

    Full Text Available This paper addresses whether the ecosystem service of animal production from grasslands depends upon plant functional identity, plant functional diversity or if the resilience of production is a function of this diversity. Using the results of nine grazing experiments the paper shows that productivity is highly dependent on one leaf trait, leaf dry matter content, as well as rainfall. Animal (secondary productivity is not dependent on plant functional diversity, but the variability in productivity of grasslands is related to the functional diversity of leaf dry matter content. This and a range of independent studies have shown that functional diversity is reduced at high levels of grassland productivity, so it appears that there is a trade-off between productivity and the resilience of productivity in the face of environmental variation.

  5. Using Elemental Budgets to Determine Effects of Simulated Climate Change on Phosphorus Cycling in a Grassland Ecosystem

    Science.gov (United States)

    Yoo, S.; Paytan, A.; Mellett, T.

    2013-12-01

    The purpose of the Jasper Ridge Global Change Experiment is to find out the effects of climate change on a terrestrial grassland ecosystem. The different treatments include increased carbon dioxide, nitrogen deposition, temperature, and precipitation. A portion of the above ground biomass of each plot was harvested, and an abundant species chosen to analyze. The goal of this project was to investigate the effects of climate change on phosphorus cycling in the grassland vegetation. Total phosphorus content of each sample was determined by combustion and acid digestion along with optical emission spectrometry. Total nitrogen and carbon was determined via flash combustion in an isotope ratio mass spectrometer. This information was combined to evaluate the limitation of phosphorus in each treatment and better understand how climate change may affect phosphorus cycling in terrestrial grasslands.

  6. 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

  7. Effects of grassland management on the emission of methane from intensively managed grasslands on peat soil.

    NARCIS (Netherlands)

    Pol-van Dasselaar, van den A.; Beusichem, van M.L.; Oenema, O.

    1997-01-01

    Methane (CH4) is the most important greenhouse gas next to CO2 and as such it contributes to the enhanced greenhouse effect. Peat soils are often considered as sources of CH4. Grasslands on the other hand are generally considered to be a net sink for atmospheric CH4. The aim of this study was

  8. Long-Term Dynamics of Standing Crop and Species Composition after the Cessation of Fertilizer Application to Mown Grassland

    NARCIS (Netherlands)

    Olff, H.; Bakker, J.P.

    1991-01-01

    (1) Current agricultural overproduction in Western Europe has led to an increase in the area of unfertilized grassland. This paper reports an experiment where fertilizer application was stopped to try to restore former species-rich vegetation. (2) Standing crop and species composition of three

  9. 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.

  10. Difficulties of biomass estimation over natural grassland

    Science.gov (United States)

    Kertész, Péter; Gecse, Bernadett; Pintér, Krisztina; Fóti, Szilvia; Nagy, Zoltán

    2017-04-01

    Estimation of biomass amount in grasslands using remote sensing is a challenge due to the high diversity and different phenologies of the constituting plant species. The aim of this study was to estimate the biomass amount (dry weight per area) during the vegetation period of a diverse semi-natural grassland with remote sensing. A multispectral camera (Tetracam Mini-MCA 6) was used with 3 cm ground resolution. The pre-processing method includes noise reduction, the correction for the vignetting effect and the calculation of the reflectance using an Incident Light Sensor (ILS). Calibration was made with ASD spectrophotometer as reference. To estimate biomass Partial Least Squares Regression (PLSR) statistical method was used with 5 bands and NDVI as input variables. Above ground biomass was cut in 15 quadrats (50×50 cm) as reference. The best prediction was attained in spring (r2=0.94, RMSE: 26.37 g m-2). The average biomass amount was 167 g m-2. The variability of the biomass is mainly determined by the relief, which causes the high and low biomass patches to be stable. The reliability of biomass estimation was negatively affected by the appearance of flowers and by the senescent plant parts during the summer. To determine the effects of flower's presence on the biomass estimation, 20 dominant species with visually dominant flowers in the area were selected and cover of flowers (%) were estimated in permanent plots during measurement campaigns. If the cover of flowers was low (0,9), while at higher cover of flowers (>30%), the estimation failed (r2 effect restricts the usage of the remote sensing method to the spring - early summer period in diverse grasslands.

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

    African Journals Online (AJOL)

    Rainfall and temperature are the direct driving factors that affect grassland ecosystem evolution. The study constructed the assessment model of the driving factors, temperature and rainfall, that exerted influence on the primary productivities of the grassland ecosystems in headwater areas, and used the model to ...

  12. 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 ...

  13. 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

  14. Wooded grasslands as part of the European agricultural heritage

    NARCIS (Netherlands)

    Centeri, C.; Renes, J.; Roth, M.; Kruse, A.; Eiter, S.; Kapfer, J.; Santoro, A.; Agnoletti, M.; Emanueli, , F.; Sigura, M.; Dobrovodska, M.; Štefunková, D.; Kučera, Zdeněk; Saláta, D.; Varga, Anna; Villacreces, S.; Dreer, J.; Slámová, M.

    2016-01-01

    Wooded grasslands have always played an important role in rural life with changing issues: They are of high importance for questions of biodiversity, soil, and water resources and in preserving agricultural heritage, but their maintenance is labor intensive. Abandoned wooded grasslands undergo

  15. Considering Forest and Grassland Carbon in Land Management

    Science.gov (United States)

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

    2017-01-01

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

  16. Estimating grassland biomass using SVM band shaving of hyperspectral data

    NARCIS (Netherlands)

    Clevers, J.G.P.W.; Heijden, van der G.W.A.M.; Verzakov, S.; Schaepman, M.E.

    2007-01-01

    In this paper, the potential of a band shaving algorithm based on support vector machines (SVM) applied to hyperspectral data for estimating biomass within grasslands is studied. Field spectrometer data and biomass measurements were collected from a homogeneously managed grassland field. The SVM

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

    African Journals Online (AJOL)

    DR. NJ TONUKARI

    2012-03-22

    Mar 22, 2012 ... the impact mechanism model of climatic changes on the primary production potentials of grassland ecosystems in the headwater areas, and thus using the model to quantitatively examine how the temperature and rainfall variations affected the grassland ecosystem evolutions in the headwater areas.

  18. Andean grasslands are as productive as tropical cloud forests

    NARCIS (Netherlands)

    Oliveras Menor, I.; Girardin, C.; Doughty, C.E.; Cahuana, N.; Arenas, C.E.; Oliver, V.; Huaraca Huasco, W.; Malhi, Y.

    2014-01-01

    We aim to assess net primary productivity (NPP) and carbon cycling in Andean tropical alpine grasslands (puna) and compare it with NPP of tropical montane cloud forests. We ask the following questions: (1) how do NPP and soil respiration of grasslands vary over the seasonal cycle? (2) how do burning

  19. Organic manures and grasslands | AW | African Journal of Range ...

    African Journals Online (AJOL)

    On the basis of the nitrogen balance in fertile, highly stocked grassland, the author discusses the improvement of less productive grasslands in lower rainfall areas. Suggested measures for improvement include subsoiling, surface treatment for better water penetration and seedbed preparation. The introduction of legumes ...

  20. Composition, pattern and diversity of some Transkeian grasslands ...

    African Journals Online (AJOL)

    Species composition, pattern and diversity of selected grassland communities were determined by using point samples, transects and quadrats. The continuously grazed grasslands of Dohne Sourveld generally had the richer species composition, the highest diversity and the most variable intra-community pattern.

  1. Porosity variabilities along a forest – grassland mosaic in Ibeku ...

    African Journals Online (AJOL)

    Variation existed in the porosity characteristics of pedons located on forestland and grassland. Percent coefficient of variation (CV) was greater in forest soils for both bulk density and porosity (% CV = 29.99 and 13.2) than as found in grassland soils (% CV = 2.6 and. 4.1). These results were explained by wide variations in ...

  2. Opening Address: Grassland research and extension: present and ...

    African Journals Online (AJOL)

    It is indeed a great honour to be invited to give the opening address at this Twenty-third Congress of the Grassland Society. It seems pertinent to review briefly grassland research, its impact on the farmer, and consider where we should be going in the future. Veld management research in Southern Africa has a proud history ...

  3. Grazing depletes forb species diversity in the mesic grasslands of ...

    African Journals Online (AJOL)

    Forbs constitute over 80% of the species richness of mesic grassland but their response to grazing is largely unknown. The influence of grazing on the forb composition, richness and diversity of two species-rich grasslands in the coastal hinterland and midlands of KwaZulu-Natal, South Africa was examined in plots subject ...

  4. 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...

  5. 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

  6. To what extent does urbanisation affect fragmented grassland functioning?

    Science.gov (United States)

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

    2015-03-15

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

  7. Effects of Holocene vegetation change on soils across the forest-grassland transition, northern Minnesota, and implications for erosion processes

    Science.gov (United States)

    Mason, Joseph; Kasmerchak, Chase; Keita, Hawa; Liang, Mengyu; Gruley, Kristine

    2016-04-01

    Boundaries between forest and grassland in the midlatitudes and their shifts in response to Holocene climatic change, provide opportunities to detect effects of life on landscapes. In northern Minnesota, USA, paleoecological research has documented that grassland and/or savanna expanded eastward in the dry early to middle Holocene. In the late Holocene, forest cover expanded westward at the expense of savanna and grassland. We studied soils at 20 sites spanning the forest-grassland transition. A dramatic change in soil morphology coincides approximately, though not exactly, with that transition as recorded in 1870s-1880s land surveys, suggesting that soils change rapidly in response to forest expansion (we are attempting to constrain the timescale of response through radiocarbon dating of deep soil organic matter in which stable C isotopes record past presence of grassland). The key changes from grassland to forest are loss of organic matter below a thin surface A horizon and greatly enhanced mobility and downward translocation of clay - particularly smectite - in forest soils. This results in upper soil horizons that have relatively low smectite content and low microaggregate stability (as detected through laser diffraction analysis of aggregate disintegration in laboratory experiments), especially below the thin A horizon. The best explanation for this change appears to involve differences in how OM is added to and accumulated in the soil under forest and grassland; soil acidity and base saturation change more gradually eastward along a gradient more likely to reflect climate than vegetation. Evidence of bioturbation (especially gopher burrowing) is much more common at former grassland sites. In addition to mixing OM downward in the soil, burrowing moves detrital carbonates upward, probably enhancing OM accumulation and aggregate stability. Research on geomorphic response to Holocene climatic change in the Midwestern US has often emphasized higher potential

  8. 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

  9. Using fire risk and species loss to set critical loads for nitrogen deposition in southern California shrublands

    Science.gov (United States)

    E.B. Allen; L.E. Rao; G. Tonnesen; R.F. Johnson; M.E. Fenn; A. Bytnerowicz

    2014-01-01

    Southern California deserts and coastal sage scrub (CSS) are undergoing vegetation-type conversion to exotic annual grassland, especially in regions downwind of urban areas that receive high nitrogen (N), primarily as dry deposition. To determine critical loads (CLs) of N that cause negative impacts, we measured plant and soil responses along N deposition gradients,...

  10. 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.

  11. Exacerbated degradation and desertification of grassland in Central Asia

    Science.gov (United States)

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

    2016-12-01

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

  12. Some environmental aspects of grassland cultivation; the effects of ploughing depth, grassland age, and nitrogen demand of subsequent crops

    NARCIS (Netherlands)

    Velthof, G.L.; Meer, van der H.G.; Aarts, H.F.M.

    2002-01-01

    The Netherlands has submitted a derogation under the Nitrate Directives to the European Union (EU) in 2000. In the final opinion by a group of experts about the Dutch derogation, recommendations on ploughing of grasslands were included dealing with the depth of ploughing of permanent grassland, the

  13. Method and timing of grassland renovation affects herbage yield, nitrate leaching, and nitrous oxide emission in intensively managed grasslands

    NARCIS (Netherlands)

    Velthof, G.L.; Hoving, I.E.; Dolfing, J.; Smit, A.; Kuikman, P.J.; Oenema, O.

    2010-01-01

    Managed grasslands are occasionally ploughed up and reseeded in order to maintain or increase the sward productivity. It has been reported that this renovation of grassland is associated with a flush of soil organic nitrogen (N) mineralization and with a temporary increase in soil mineral N

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

    Science.gov (United States)

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

    2006-01-01

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

  15. 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.

  16. Plant diversity effects on root decomposition in grasslands

    Science.gov (United States)

    Chen, Hongmei; Mommer, Liesje; van Ruijven, Jasper; de Kroon, Hans; Gessler, Arthur; Scherer-Lorenzen, Michael; Wirth, Christian; Weigelt, Alexandra

    2016-04-01

    Loss of plant diversity impairs ecosystem functioning. Compared to other well-studied processes, we know little about whether and how plant diversity affects root decomposition, which is limiting our knowledge on biodiversity-carbon cycling relationships in the soil. Plant diversity potentially affects root decomposition via two non-exclusive mechanisms: by providing roots of different substrate quality and/or by altering the soil decomposition environment. To disentangle these two mechanisms, three decomposition experiments using a litter-bag approach were conducted on experimental grassland plots differing in plant species richness, functional group richness and functional group composition (e.g. presence/absence of grasses, legumes, small herbs and tall herbs, the Jena Experiment). We studied: 1) root substrate quality effects by decomposing roots collected from the different experimental plant communities in one common plot; 2) soil decomposition environment effects by decomposing standard roots in all experimental plots; and 3) the overall plant diversity effects by decomposing community roots in their 'home' plots. Litter bags were installed in April 2014 and retrieved after 1, 2 and 4 months to determine the mass loss. We found that mass loss decreased with increasing plant species richness, but not with functional group richness in the three experiments. However, functional group presence significantly affected mass loss with primarily negative effects of the presence of grasses and positive effects of the presence of legumes and small herbs. Our results thus provide clear evidence that species richness has a strong negative effect on root decomposition via effects on both root substrate quality and soil decomposition environment. This negative plant diversity-root decomposition relationship may partly account for the positive effect of plant diversity on soil C stocks by reducing C loss in addition to increasing primary root productivity. However, to fully

  17. California Political Districts

    Data.gov (United States)

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

  18. Diversity promotes temporal stability across levels of ecosystem organization in experimental grasslands.

    Science.gov (United States)

    Proulx, Raphaël; Wirth, Christian; Voigt, Winfried; Weigelt, Alexandra; Roscher, Christiane; Attinger, Sabine; Baade, Jussi; Barnard, Romain L; Buchmann, Nina; Buscot, François; Eisenhauer, Nico; Fischer, Markus; Gleixner, Gerd; Halle, Stefan; Hildebrandt, Anke; Kowalski, Esther; Kuu, Annely; Lange, Markus; Milcu, Alex; Niklaus, Pascal A; Oelmann, Yvonne; Rosenkranz, Stephan; Sabais, Alexander; Scherber, Christoph; Scherer-Lorenzen, Michael; Scheu, Stefan; Schulze, Ernst-Detlef; Schumacher, Jens; Schwichtenberg, Guido; Soussana, Jean-François; Temperton, Vicky M; Weisser, Wolfgang W; Wilcke, Wolfgang; Schmid, Bernhard

    2010-10-13

    The diversity-stability hypothesis states that current losses of biodiversity can impair the ability of an ecosystem to dampen the effect of environmental perturbations on its functioning. Using data from a long-term and comprehensive biodiversity experiment, we quantified the temporal stability of 42 variables characterizing twelve ecological functions in managed grassland plots varying in plant species richness. We demonstrate that diversity increases stability i) across trophic levels (producer, consumer), ii) at both the system (community, ecosystem) and the component levels (population, functional group, phylogenetic clade), and iii) primarily for aboveground rather than belowground processes. Temporal synchronization across studied variables was mostly unaffected with increasing species richness. This study provides the strongest empirical support so far that diversity promotes stability across different ecological functions and levels of ecosystem organization in grasslands.

  19. Soil phosphorus constrains biodiversity across European grasslands.

    Science.gov (United States)

    Ceulemans, Tobias; Stevens, Carly J; Duchateau, Luc; Jacquemyn, Hans; Gowing, David J G; Merckx, Roel; Wallace, Hilary; van Rooijen, Nils; Goethem, Thomas; Bobbink, Roland; Dorland, Edu; Gaudnik, Cassandre; Alard, Didier; Corcket, Emmanuel; Muller, Serge; Dise, Nancy B; Dupré, Cecilia; Diekmann, Martin; Honnay, Olivier

    2014-12-01

    Nutrient pollution presents a serious threat to biodiversity conservation. In terrestrial ecosystems, the deleterious effects of nitrogen pollution are increasingly understood and several mitigating environmental policies have been developed. Compared to nitrogen, the effects of increased phosphorus have received far less attention, although some studies have indicated that phosphorus pollution may be detrimental for biodiversity as well. On the basis of a dataset covering 501 grassland plots throughout Europe, we demonstrate that, independent of the level of atmospheric nitrogen deposition and soil acidity, plant species richness was consistently negatively related to soil phosphorus. We also identified thresholds in soil phosphorus above which biodiversity appears to remain at a constant low level. Our results indicate that nutrient management policies biased toward reducing nitrogen pollution will fail to preserve biodiversity. As soil phosphorus is known to be extremely persistent and we found no evidence for a critical threshold below which no environmental harm is expected, we suggest that agro-environmental schemes should include grasslands that are permanently free from phosphorus fertilization. © 2014 John Wiley & Sons Ltd.

  20. 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

  1. 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

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

    Directory of Open Access Journals (Sweden)

    Valentin H Klaus

    Full Text Available 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(15N and δ(13C isotopic composition of soil and hay samples of 21 organic and 34 conventional grasslands in two German regions. We also used Δδ(15N (δ(15N plant - δ(15N 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(13C in hay and δ(15N in both soil and hay between management types, but showed that δ(13C abundances were significantly lower in soil of organic compared to conventional grasslands. Δδ(15N values implied that management types did not substantially differ in nitrogen cycling. Only δ(13C 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

  3. GHGs balance in a land use change process from grassland to short rotation coppice of poplar

    Science.gov (United States)

    Sabbatini, Simone; Arriga, Nicola; Baiocco, Andrea; Boschi, Alessio; Castaldi, Simona; Consalvo, Claudia; Gioli, Beniamino; Matteucci, Giorgio; Tomassucci, Michele; Zaldei, Alessandro; Papale, Dario

    2013-04-01

    At present one of the fastest spreading renewable energy sources are bioenergy cultivations. Millions of hectares of traditional crops all over the Europe are expected to be converted in energy crops in the near future, in order to produce green energy and contrast global warming. Last year, in the context of the GHG-Europe FP7 project we set up an experiment to verify the effects on the green-house gases balance of a land use change from traditional agriculture to short rotation coppice of poplar clones in central Italy. CO2 fluxes measured during the last growing season through three Eddy Covariance masts - two on poplar plantations of different ages and one over a reference site (grassland) - have been analysed. We also monitored CO2, CH4 and N2O fluxes from soil measured using chambers in order to better understand the contribution of other GHGs. The two poplar plantations showed a similar uptake of Carbon, 368 g C m-2 year-1 and 358 g C m-2 year-1, while the grassland absorbed 220 g C m-2 year-1 during the same period. Soil respiration in average was higher for the youngest plantation of poplar and for the grassland, lower for the oldest one, where soil is undisturbed from more time. In all the sites we measured low emissions during the winter (between 80 and 150 mg CO2 m-2 h-1), progressively higher in the spring and early summer with growing temperatures (up to 650 mg CO2 m-2 h-1), quite low during the summer because of a strong drought, while the highest values were recorded in September (ca. 1100 mg CO2 m-2 h-1 in the grassland and youngest poplar) after important rain events. Fluxes of N2O and CH4 from soil are very low: little absorption of CH4 in the grassland (values between 0 and -18.75 μg m-2 h-1), with peak after fertilization; in the SRC little absorption or emission with no clear seasonal pattern. Insignificant fluxes of N2O in all crops (even in the grassland after fertilization). The carbon fluxes measured are strongly related to the particular

  4. Environmental Controls and Management Effects on Ecosystem Carbon Exchange in Two Grazed Temperate Grasslands

    Science.gov (United States)

    Ni Choncubhair, O.; Humphreys, J.; Lanigan, G.

    2013-12-01

    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. Accumulation of carbon (C) in grassland systems predominantly takes place in below-ground repositories, enhanced by the presence of a stable soil environment with low carbon turnover rates, active rhizodeposition and high levels of residue and organic inputs. However, this C sequestration is strongly influenced by soil characteristics and climatic variables. Furthermore, in managed pasture systems, carbon exchange across the soil-atmosphere boundary is additionally affected by management activities, such as biomass removal, grazing events and the deposition or application of organic amendments. These biotic and abiotic factors contribute greatly towards the large uncertainty associated with the carbon balance of grassland ecosystems and demand further analysis. In the present study, the controls and drivers of carbon dynamics in two rotationally-grazed grasslands in Ireland were examined. The sites experience similar temperate climatic regimes but differ in soil texture classification and stocking rate. Eddy covariance measurements of net ecosystem exchange of carbon were complemented by regular assessment of standing biomass, leaf cover, harvest exports and organic amendment inputs. Our study showed that mild weather conditions and an extended growing season sustained net C accumulation at both sites for at least ten months of the year. Despite differing soil drainage characteristics, winter fluxes of net carbon exchange and its component fluxes, gross photosynthesis and ecosystem respiration, were highly comparable between the two sites. Management practices during the active growing season exerted a strong influence on both the direction and the rate of C exchange in the grassland systems, with a strong dependence, however, on the timing and

  5. 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…

  6. Pleistocene water cycle and eastern boundary current processes along the California continental margin

    Science.gov (United States)

    Lyle, Mitchell; Heusser, Linda; Ravelo, Christina; Andreasen, Dyke; Olivarez Lyle, Annette; Diffenbaugh, Noah

    2010-11-01

    Coastal marine sediments contain mixtures of terrestrial and marine paleoclimate proxies that record how the coastal water cycle has behaved over long time frames. We explore a 600 kyr marine record from ODP Site 1018, located due west of Santa Cruz, California, to identify coastal wet and dry periods and to associate them with oceanographic processes. Wet periods in central California, identified by increased tree pollen relative to pollen from grasslands and scrublands, are found on every major deglaciation in the last 600 kyr. Sea surface temperature (SST) data were collected for the last two deglaciations. Wet periods are associated with a rapid rise in SST off central California. SST gradients along the California margin and changes in biogenic deposition show that wet periods in central California are associated with a weakening of the California Current and weakened coastal upwelling. High carbonate production suggests that there was significant curl-of-wind stress upwelling offshore. We propose that wet periods in central California are associated with a meteorological connection to the tropical Pacific and weakened southward flow in the California Current that shunted temperate Pacific water northward into the Alaska gyre. We do not observe evidence for a south-shifted westerly storm track at the last glacial maximum but find that wet periods are diachronous along the California margin. The wettest period around the Santa Barbara Basin peaked at 16 ka, preceding the wet peak in central and northern California by 4 kyr.

  7. 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

  8. Response of subalpine grasslands communities to clear-cut and prescribed burnt to control shrub encroachment in Pyrenees

    Science.gov (United States)

    Alados, Concepción L.; Gartzia, Maite; Nuche, Paloma; Saiz, Hugo; Pueyo, Yolanda

    2017-04-01

    Anthropogenic activities have modified vegetation in subalpine belts for long time, lowering treeline ecotone and influencing landscape mainly through grazing and fire. During the last decades the abandonment of traditional land use practices and global warming are contributing largely to the colonization of woody species in subalpine grasslands causing irreversible changes in ecosystem functioning. To prevent those changes a variety of management strategies are carried out to stop the expansion of the highly encroaching shrubs, which require the use of fire and/or clear-cutting, particularly for the conservation of grasslands in subhumid high productive ecosystems. However, it is still poorly understood how different management strategies affect the recovery of subalpine grasslands. Using a field experiment we tested the impact of management treatments on soil properties and vegetation characteristics, including species richness, community structure, interspecies interaction, and complexity of network association. Vegetation was monitored during four years in eight stands (two stands per treatment) where the vegetation was removed by prescribed fire (Burnt treatment), or by mechanical removal (Clear-cut treatment). Two undisturbed E. horridum stands were used as a control (C-Erizón) and two grassland communities regularly grazed (C-Grass) were used as a control for subalpine grassland. Soils nutrients declined in Burnt treatment 3 years after fire, but not differences between Clear-cut and C-Erizón were observed. Species richness and diversity were larger in C-Grass and lower in C-Erizón. Burnt and Clear-cut treatments increased species diversity and richness gradually after 4 year treatment. The proportion of legume forbs, grasses and non-legume forbs did not reach the levels of C-Grass after 4 years of Clear-cut or Burnt treatments. Shrubs and sub-shrubs increased faster after 4 years of burning than after 4 years of clearing, although they did not reach the

  9. Increased soil nutrition and decreased light intensity drive species loss after eight years grassland enclosures.

    Science.gov (United States)

    Li, Jingpeng; Zheng, Zhirong; Xie, Hongtao; Zhao, Nianxi; Gao, Yubao

    2017-03-27

    Enclosures (fenced, grazing or clipping) within a certain period of years are the most common tools for restoration of degraded grasslands in temperate regions. Short-term enclosures can improve biodiversity and productivity by effectively relieving grazing pressure, while long-term enclosures can reduce species diversity. We therefore carried out a field experiment to investigate the specific causes of the reduced species diversity in Hulunbeier grassland of northern China. After eight years of enclosure, the significantly increased soil available nitrogen (AN) and available phosphorus (AvP) in enclosure community reduced nitrogen (N) limitation but most vegetation was still N limited. Many environmental factors led to decreased species richness, but increased soil AN and decreased light intensity at the community bottom were the most significant ones. Community density decreased independently of soil nutrition but significantly related to decreased species richness. Density of dominant canopy species increased, while dominant understory species decreased during assemblage-level thinning; therefore, the random-loss hypothesis was not supported. The dominant understory species responded to lower light availability by increasing their height, leaf area, and chlorophyll content. Moreover, our results were expected to provide some specific guidance for the restoration mode selection of degraded grasslands in northern China.

  10. 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.

  11. Does drought legacy alter the recovery of grassland carbon dynamics from drought?

    Science.gov (United States)

    Bahn, Michael; Hasibeder, Roland; Fuchslueger, Lucia; Ingrisch, Johannes; Ladreiter-Knauss, Thomas; Lair, Georg; Reinthaler, David; Richter, Andreas; Kaufmann, Rüdiger

    2017-04-01

    Climate projections suggest an increase in the frequency and the severity of extreme climatic events, such as droughts, with consequences for the carbon cycle and its feedbacks to the climate system. An important implication of increasing drought frequency is that possible legacies of previous droughts may increasingly affect ecosystem responses to new drought events, though this has been rarely tested. Based on a series of severe experimental droughts performed during nine subsequent years on a mountain grassland in the Austrian Alps, we present evidence of effects of drought legacies on the recovery of grassland carbon dynamics from drought and analyse the underlying mechanisms. Both single and recurrent droughts led to increased aboveground productivity during drought recovery relative to control plots, favoring the biomass production and leaf area of grass species more strongly than of forbs. Belowground productivity was significantly increased during recovery. This led to higher total root length, even though specific root length was strongly reduced during recovery, particularly after recurrent drought events. Following rewetting, the temperature dependence of soil respiration was increasingly diminished and the Birch effect declined with progressive recurrence of droughts. This was paralleled by a change in soil aggregate stability and soil porosity in plots repeatedly exposed to drought. Isotopic pulse-labelling experiments revealed effects of drought legacy on plant carbon uptake and belowground allocation and altered microbial turnover of recent plant-derived carbon during and after a subsequent drought. Shifts in tissue nitrogen concentration indicate that drought effects on soil nitrogen turnover and availability could play an important role in the recovery of grassland carbon dynamics following both single and recurrent droughts. In conclusion, drought legacies can alter the recovery of grassland carbon dynamics from drought, the effects increasing

  12. 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.

  13. Effects of drought on nitrogen turnover and abundances of ammonia-oxidizers in mountain grassland

    Science.gov (United States)

    Fuchslueger, L.; Kastl, E.-M.; Bauer, F.; Kienzl, S.; Hasibeder, R.; Ladreiter-Knauss, T.; Schmitt, M.; Bahn, M.; Schloter, M.; Richter, A.; Szukics, U.

    2014-11-01

    Future climate scenarios suggest an increased frequency of summer drought periods in the European Alpine Region. Drought can affect soil nitrogen (N) cycling, by altering N transformation rates, as well as the abundances of ammonia-oxidizing bacteria and archaea. However, the extent to which drought affects N cycling under in situ conditions is still controversial. The goal of this study was to analyse effects of drought on soil N turnover and ammonia-oxidizer abundances in soil without drought history. To this end we conducted rain-exclusion experiments at two differently managed mountain grassland sites, an annually mown and occasionally fertilized meadow and an abandoned grassland. Soils were sampled before, during and after drought and were analysed for potential gross rates of N mineralization, microbial uptake of inorganic N, nitrification, and the abundances of bacterial and archaeal ammonia-oxidizers based on gene copy numbers of the amoA gene (AOB and AOA, respectively). Drought induced different responses at the two studied sites. At the managed meadow drought increased NH4+ immobilization rates and NH4+ concentrations in the soil water solution, but led to a reduction of AOA abundance compared to controls. At the abandoned site gross nitrification and NO3- immobilization rates decreased during drought, while AOB and AOA abundances remained stable. Rewetting had only minor, short-term effects on the parameters that had been affected by drought. Seven weeks after the end of drought no differences to control plots could be detected. Thus, our findings demonstrated that in mountain grasslands drought had distinct transient effects on soil nitrogen cycling and ammonia-oxidizers, which could have been related to a niche differentiation of AOB and AOA with increasing NH4+ levels. However, the effect strength of drought was modulated by grassland management.

  14. 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.

  15. Ammonia volatilization following dairy slurry application to a permanent grassland on a volcanic soil

    Science.gov (United States)

    Martínez-Lagos, J.; Salazar, F.; Alfaro, M.; Misselbrook, T.

    2013-12-01

    Agriculture is the largest source of ammonia (NH3) emission to the atmosphere. Within the agricultural sector, the application of slurry to grasslands as fertilizer is one of the main emission sources. This is a common practice in southern Chile, where most dairy production systems are grazing-based. In Chile, there are few published data of gaseous emissions following slurry application to grassland. The aim of this study was to evaluate NH3 volatilization following dairy slurry application to a permanent grassland on an Andosol soil. Ammonia volatilization was measured in four field experiments (winters of 2009 and 2011 and early and late springs of 2011) using a micrometeorological mass balance method with passive flux samplers following dairy slurry application at a target rate of 100 kg total N ha-1. The accumulated N loss was equivalent to 7, 8, 16 and 21% of the total N applied and 22, 34, 88 and 74% of total ammoniacal nitrogen (TAN) applied for winters 2009 and 2011, and early and late spring 2011, respectively. Ammonia emission rates were high immediately after application and declined rapidly with time, with more than 50% of the total emissions within the first 24 h. Losses were highly influenced by environmental conditions, increasing with temperature and lack of rainfall. Taking into consideration the low N losses via leaching and nitrous oxide emissions reported for the study area, results indicate that NH3 volatilization is the main pathway of N loss in fertilized grasslands of southern Chile. However, dairy slurry application could be an important source of nutrients, if applied at a suitable time, rate and using an appropriate technique, and if soil and climate conditions are taken into consideration. This could improve N use efficiency and reduce N losses to the wider environment.

  16. NPP Grassland: Jornada, USA, 1970-1972, R1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains three ASCII files (.txt format). Two files contain above- and below-ground biomass and productivity data for a desert grassland in the Jornada...

  17. Grassland Management Plan Wertheim National Wildlife Refuge 1989

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This grassland management plan for Wertheim National Wildlife Refuge is presented as an interim document to provide refuge staff in 1989 with management guidelines...

  18. Shawangunk Grasslands National Wildlife Refuge: Comprehensive Conservation Plan

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Comprehensive Conservation Plan (CCP) was written to guide management on Shawangunk Grasslands NWR for the next 15 years. This plan outlines the Refuge vision...

  19. Effects of Habitat Manipulation on Grassland Bird Populations

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Because of continuing concern over the decline of grassland bird populations in the Northeast, and the fact that many management activities designed to increase...

  20. Grasslands Wildlife Management Area : Annual narrative report : Calendar year 1991

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Grasslands WMA outlines Refuge accomplishments during the 1991 calendar year. The report begins with a summary of the year's...

  1. Effects of fire on belowground biomass in Chihuahuan desert grassland

    National Research Council Canada - National Science Library

    Burnett, Shayla A; Hattey, Jeffory A; Johnson, Jennifer E; Swann, Amaris L; Moore, Douglas I; Collins, Scott L

    2012-01-01

    .... eriopoda -dominated grassland in Central New Mexico, USA. At one site, we quantified belowground standing crop and net primary production in burned and unburned areas during the first full growing season following wildfire the previous summer...

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

    DEFF Research Database (Denmark)

    Guidi, Claudia

    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....... 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...... involved into long-term stability are largely unknown. The aim of this PhD thesis was to explore changes in: (i) SOC stocks; (ii) physical SOC fractions; and (iii) labile soil carbon components following forest expansion on mountain grasslands. A land-use gradient located in the Southern Alps (Italy...

  3. New taxa of Entoloma from grasslands in Drenthe, The Netherlands

    NARCIS (Netherlands)

    Arnolds, E.J.M.; Noordeloos, M.E.

    1979-01-01

    Fourteen new species and three new variaties of Entoloma from grassland vegetations in the province of Drenthe, The Netherlands, are described: E. acidophilum, E. argenteostriatum, E. calthionis, E. chlorinosum, E. cryptocystidiatum, E. cuniculorum. E. defibulatum, E. farinogustus, E.

  4. NPP Grassland: Bridger, USA, 1970-1973, R1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains three ASCII text files for the Bridger grassland study site in the Rocky Mountains (45.78 N, -110.78 W, Elevation 2,340 m). Two files contain...

  5. Grassland Management Plan Erie National Wildlife Refuge 1981

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This management plan provides well defined guidelines to accomplish the following goals at Erie National Wildlife Refuge : 1) to manage existing grasslands, 2)...

  6. Grassland bird survey protocol : Kulm Wetland Management District

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Initial Survey Instructions for the grassland bird survey at Kulm Wetland Management District. This survey occurs between May 15th and July 15th annually. All...

  7. Spatiotemporal variability of increasing temperature impacts on grassland vegetation along an elevation transect in the Alps

    Science.gov (United States)

    Niedrist, Georg; Obojes, Nikolaus; Bertoldi, Giacomo; Della Chiesa, Stefano; Tasser, Erich; Tappeiner, Ulrike

    2013-04-01

    Different manipulative approaches have been developed to study and quantify impacts of temperature increase on grassland ecosystems. Many of them share the problem of unwanted effects on the surrounding microclimatic conditions. Transplantation of grassland mesocosms along elevation gradients can be a realistic alternative, although with some restrictions. Here we present 3 years of data from a double-transplant-experiment, were 70*70*20cm grassland turves were transplanted at two elevations from 2000m to 1500m a.s.l. and from 1500m to 1000m a.s.l. respectively, along an inner-alpine elevation gradient in the Vinschgau Valley (South Tyrol, I). All donor and receiving sites are comparable regarding land use (meadows), soil conditions or exposition and are located within a few km's distance ensuring comparable weather conditions apart from the intended air temperature (0.54°K/100m) and annual precipitation (20mm/100m) lapse rate. Phytodiversity and above ground net primary production (ANPP) of the transplanted mesocosms were assessed and compared with locally transplanted monoliths of the respective donor site. Furthermore, growth dynamics was continuously observed throughout the vegetation season with a non-destructive method based on measurement of light (photosynthetic active radiation) extinction within the canopy. After 3 years no significant changes in absolute species numbers has been detected at all, whereas slight variations have been observed regarding species composition. Those shifts could be differentiated both to transplantation artifacts and effects of the elevated temperature. Total aboveground phytomass, unsurprisingly, showed higher values on transplanted (lower) mesocosms, however: data from single cuts and growth rate analysis reveal differing effects between the two transplantation steps as well as over the course of the vegetation period. Transplanted plots from 2000m to 1500m showed continuously higher productivity from spring to autumn

  8. Estimating grassland biomass using SVM band shaving of hyperspectral data

    OpenAIRE

    Clevers, J G P W; van Der Heijden, G.W.A.M.; Verzakov, S; Schaepman, M. E.

    2007-01-01

    In this paper, the potential of a band shaving algorithm based on support vector machines (SVM) applied to hyperspectral data for estimating biomass within grasslands is studied. Field spectrometer data and biomass measurements were collected from a homogeneously managed grassland field. The SVM band shaving technique was compared with a partial least squares (PLS) and a stepwise forward selection analysis. Using their results, a range of vegetation indices was used as predictors for grasslan...

  9. 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...... of aerenchymous plants should be considered before dismissing grasslands on peat as CH4 sources....

  10. 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

  11. 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

  12. Disentangling the response of forest and grassland energy exchange to heatwaves under idealized land-atmosphere coupling

    Science.gov (United States)

    van Heerwaarden, C. C.; Teuling, A. J.

    2014-11-01

    This study investigates the difference in land-atmosphere interactions between grassland and forest during typical heatwave conditions in order to understand the controversial results of Teuling et al. (2010) (hereafter T10), who found the systematic occurrence of higher sensible heat fluxes over forest than over grassland during heatwaves. With a simple but accurate coupled land-atmosphere model, we show that existing parametrizations are able to reproduce the findings of T10 for normal summer and heatwave conditions. Furthermore, we demonstrate the sensitivity of the coupled system to changes in incoming radiation and early-morning temperature typical for European heatwaves. Our results suggest that the fast atmospheric control of stomatal resistance can explain the observed differences between grassland and forest. The atmospheric boundary layer has a buffering function therein: increases in stomatal resistance are largely compensated for by increases in the potential evaporation due to atmospheric warming and drying. In order to disentangle the contributions of differences in several static and dynamic properties between forest and grassland, we have performed a virtual experiment with artificial land-use types that are equal to grassland, but with one of its properties replaced by that of forest. From these, we confirm the important role of the fast physiological processes that lead to the closure of stomata. Nonetheless, for a full explanation of T10's results, the other properties (albedo, roughness and the ratio of minimum stomatal resistance to leaf-area index) play an important but indirect role; their influences mainly consist of strengthening the feedback that leads to the closure of the stomata by providing more energy that can be converted into sensible heat. The model experiment also confirms that, in line with the larger sensible heat flux, higher atmospheric temperatures occur over forest. As our parametrization for stomatal resistance is empirical

  13. 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.

  14. 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.

  15. 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 BACKGROUND: 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. METHODOLOGY/PRINCIPAL FINDINGS: 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. CONCLUSIONS/SIGNIFICANCE: 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.

  16. Recommendations on the use of prescribed burning practices in grassland conservation - An evidence-based study from Hungary

    Science.gov (United States)

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

    2015-04-01

    Fire as a natural disturbance has been present in most European grasslands. In parallel controlled use of burning was an important part of the traditional landscape management for millennia. It was used to reduce litter and suppress woody vegetation as well as to maintain open landscapes suitable for farming. Recently, human activities have a considerable impact on natural fire regimes through habitat fragmentation, cessation of traditional grassland management and climate change. Nowadays the majority of human-ignited fires are uncontrolled burnings and arson, which have serious negative impacts on human life, property and can be detrimental also from the nature conservation point of view. Despite fire was widely applied in the past and the considerable extension and frequency of current grassland fires, the impact of fire on the grassland biodiversity is still scarcely documented in Europe. The aim of our study was to gather practical knowledge and experiences from Hungary concerning the effects of fire on grasslands. To fulfil this aim we sent questionnaires to experts from Hungarian national park directorates to gather unpublished data and field observations concerning the effects of burning on grasslands. Based on the answers for the questionnaires fire regularly occur in almost every grassland types in Hungary. We found that effects of fire are habitat-specific. One hand uncontrolled burning and arson have serious detrimental impacts on many endangered species (ground-dwelling birds, such as Asio flammeus, Tringa totanus and Vanellus vanellus; or lizards, such as Ablepharus kitaibelii). On the other hand in several cases fire has a positive effect on the habitat structure and favours species of high nature conservation interest (plant species, such as Adonis volgensis, Chamaecytisus supinus and Pulsatilla grandis; butterflies, such as Euphydryas aurinia; bird species such as Circus aeruginosus and Larus cachinnans). Our results suggest that even uncontrolled

  17. Grassland breeding bird use of managed grasslands on National Wildlife Refuges in Region 5 of the Fish and Wildlife Service

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The overall purpose of this project is to understand the likely capacity of Fish and Wildlife Service land managers to affect grassland bird populations in Region 5....

  18. Impact of Reduced Diurnal Temperature Range (DTR) on Grassland Mesocosms

    Science.gov (United States)

    Gregg, J. W.; Phillips, C.; Wilson, J.

    2010-12-01

    treatments compared to AMB. Lupinus albicaulus, the lone N-fixing perennial forb, exhibited low (48%) survival for the ambient treatment in the N-rich grassland soils after one year, but even lower survival (8% and 11%) for the SYM and ASYM treatments. There were no differences in soil N availability between treatments, so reduced survival for this and other late spring emerging species appeared to be due to substantially reduced growing season due to the earlier senescence for the warmer treatments. These results suggest that species that take advantage of enhanced fall growth conditions are likely to have a competitive advantage as grasslands become warmer. Overall, our results show no differences in assimilation, respiration, NEP, phenology, or species composition/diversity for ASYM compared to SYM warming treatments. Future research should determine if these lack of treatment effects persist for reverse-ASYM treatments that experience an increase in DTR where greatest temperature increase occurs at the hottest time of day. It will also be important to determine the robustness of these results for woody species or higher latitudes where winter dormancy would play an important role for altering season length.

  19. 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.

  20. 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.

  1. Projected Changes of Grassland Productivity along the Representative Concentration Pathways during 2010–2050 in China

    Directory of Open Access Journals (Sweden)

    Feng Wu

    2013-01-01

    Full Text Available The grassland is an important land use type that plays an important role in the ecosystem services supply in China. It is of great significance to the grassland management to determine the changing trend of grassland productivity and its response to climate change. Firstly, the relationship between grassland productivity and climate change, geographical conditions, and human activities was analyzed with the panel data of the whole China during 1980–2010 in this study. The result indicated that the temperature and precipitation were very important to grassland productivity at the national scale. Secondly, the grassland in China was divided into 7 grassland ecological-economic zones according to the ecosystem service function and climate characteristics. The relationship between grassland productivity and climate change was further analyzed at the regional scale. The result indicated that the temperature is more beneficial to the increase of the grassland productivity in the Qinghai-Tibet Plateau and the Southwest Karst shrubland region. Thirdly, the increase of the temperature and precipitation can increase the grassland productivity and consequently relieve the pressure according to the climate factors of simulation with the community climate system model v4.0 (CCSM. However, the simulation result indicates that the human pressure on grasslands is still severe under the four RCPs scenarios and the grassland area would reduce sharply due to the conversion from the grassland to the cultivated land. What is more, there is still a great challenge to the increase of total grassland productivity in China.

  2. Response of grassland ecosystems to prolonged soil moisture deficit

    Science.gov (United States)

    Ross, Morgan A.; Ponce-Campos, Guillermo E.; Barnes, Mallory L.; Hottenstein, John D.; Moran, M. Susan

    2014-05-01

    Soil moisture is commonly used for predictions of plant response and productivity. Climate change is predicted to cause an increase in the frequency and duration of droughts over the next century, which will result in prolonged periods of below-normal soil moisture. This, in turn, is expected to impact regional plant production, erosion and air quality. In fact, the number of consecutive months of soil moisture content below the drought-period mean has recently been linked to regional tree and shrub mortality in the southwest United States. This study investigated the effects of extended periods of below average soil moisture on the response of grassland ANPP to precipitation. Grassland ecosystems were selected for this study because of their ecological sensitivity to precipitation patterns. It has been postulated that the quick ecological response of grasslands to droughts can provide insight to large scale functional responses of regions to predicted climate change. The study sites included 21 grassland biomes throughout arid-to-humid climates in the United States with continuous surface soil moisture records for 2-13 years during the drought period from 2000-2013. Annual net primary production (ANPP) was estimated from the 13-year record of NASA MODIS Enhanced Vegetation Index extracted for each site. Prolonged soil moisture deficit was defined as a period of at least 10 consecutive months during which soil moisture was below the drought-period mean. ANPP was monitored before, during and after prolonged soil moisture deficit to quantify shifts in the functional response of grasslands to precipitation, and in some cases, new species assemblages that included invasive species. Preliminary results indicated that when altered climatic conditions on grasslands led to an increase in the duration of soil water deficit, then the precipitation-to-ANPP relation became non-linear. Non-linearity was associated with extreme grassland dieback and changes in the historic

  3. Effects of warming and nitrogen deposition on CH4, CO2 and N2O emissions in alpine grassland ecosystems of the Qinghai-Tibetan Plateau.

    Science.gov (United States)

    Zhao, Zhenzhen; Dong, Shikui; Jiang, Xiaoman; Liu, Shiliang; Ji, Hanzhong; Li, Yu; Han, Yuhui; Sha, Wei

    2017-08-15

    Increases in nitrogen (N) deposition along with climate warming can change the dynamics of carbon and nitrogen in the soil, and alter greenhouse gases (GHGs) fluxes. To examine how N deposition and warming affect GHGs (CH4, CO2 and N2O) fluxes in alpine grasslands, we conducted experiments in an alpine meadow (AM), alpine-steppe (AS), and alpine cultivated grassland (CG) on the Qinghai-Tibetan Plateau (QTP). We simulated N deposition by treating soil with ammonium nitrate (NH4NO3) (8kgNha(-1)year(-1)), a warming treatment using an open top chamber (OTC) was carried out, and a combined treatment of warming and N deposition (8kgNha(-1)year(-1)) was conducted. The GHGs were collected during early, peak, and late plant growing seasons, i.e., May, August, and October of 2015, respectively, using a static chamber. We found, in general, neither N deposition nor warming solely altered CH4 and N2O fluxes in the alpine grasslands. The N deposition under warming conditions reduced CO2 emission significantly. The reduction of CO2 emission was most significant in the alpine steppe. The effects of climatic warming and N deposition on the GHGs varied greatly across the grassland types and the growing seasons. The cultivated grasslands were much more unstable than the native grasslands in CH4 uptake. In can be concluded the N deposition associated with human activities may buffer the CO2 emission in the alpine grassland ecosystems in terms of climate changes on the QTP. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. 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

  5. Plant water use affects competition for nitrogen: why drought favors invasive species in California.

    Science.gov (United States)

    Everard, Katherine; Seabloom, Eric W; Harpole, W Stanley; de Mazancourt, Claire

    2010-01-01

    Abstract: Classic resource competition theory typically treats resource supply rates as independent; however, nutrient supplies can be affected by plants indirectly, with important consequences for model predictions. We demonstrate this general phenomenon by using a model in which competition for nitrogen is mediated by soil moisture, with competitive outcomes including coexistence and multiple stable states as well as competitive exclusion. In the model, soil moisture regulates nitrogen availability through soil moisture dependence of microbial processes, leaching, and plant uptake. By affecting water availability, plants also indirectly affect nitrogen availability and may therefore alter the competitive outcome. Exotic annual species from the Mediterranean have displaced much of the native perennial grasses in California. Nitrogen and water have been shown to be potentially limiting in this system. We parameterize the model for a Californian grassland and show that soil moisture-mediated competition for nitrogen can explain the annual species' dominance in drier areas, with coexistence expected in wetter regions. These results are concordant with larger biogeographic patterns of grassland invasion in the Pacific states of the United States, in which annual grasses have invaded most of the hot, dry grasslands in California but perennial grasses dominate the moister prairies of northern California, Oregon, and Washington.

  6. Informing agricultural management - The challenge of modelling grassland phenology

    Science.gov (United States)

    Calanca, Pierluigi

    2017-04-01

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

  7. Grazing-induced BVOC fluxes from a managed grassland

    Science.gov (United States)

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

    2017-04-01

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

  8. Effects of Yak grazing on plant community characteristics of meadow grasslands in the Qinghai-Tibetan Plateau, China

    Science.gov (United States)

    Chai, Linrong; Hou, Fujiang; Bowatte, Saman; Cheng, Yunxiang

    2017-04-01

    The Qinghai-Tibetan Plateau (QTP) is an important part of the global terrestrial ecosystem that provides many ecological roles such as biodiversity protection, upper watersheds for large rivers, circulation of materials, energy balance and provision of forage and habitat for livestock and wildlife. Approximately 40% of the QTP is alpine meadow grasslands and yak farming is one of the dominant land use activities. In recent years, the rapid increase in the number of yaks grazing on meadow grasslands has raised concerns about grassland degradation. In this study we examined the effects of yak grazing on the grassland community characteristics to evaluate the degradation potential of alpine meadow in the QTP. The experiment was carried out on three farms, in close proximity to each other, that were operating at different grazing intensities in Maqu county (N35°58', E101°53', altitude 3650m) of the QTP in the Gansu province in China. We tested 4 levels of yak grazing intensities; control (no grazing), light (2.6yak/ha), moderate (3.5yak/ha) and high (6.5yak/ha ). We hypothesized that greater intensity of grazing would significantly impact the plant community characteristics through trampling effects above and below ground. We found grazing significantly (Pplant community density and the proportion of edible grass biomass were not significantly affected by the grazing treatments. The species richness was significantly reduced (pplant community characteristics in alpine meadow in the QTP, indicating a potential for grassland degradation to occur in future. Therefore, further comprehensive research is warranted. Key words: Qinghai-Tibetan Plateau; Yak grazing; Alpine meadow; Maqu county

  9. 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.

  10. 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

  11. Teale California shoreline

    Data.gov (United States)

    California Department of Resources — 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...

  12. Mediterranean California, Chapter 13

    Science.gov (United States)

    M.E. Fenn; E.B. Allen; L.H. Geiser

    2011-01-01

    The Mediterranean California ecoregion (CEC 1997; Fig 2.2) encompasses the greater Central Valley, Sierra foothills, and central coast ranges of California south to Mexico and is bounded by the Pacific Ocean, Sierra Nevada Mountains and Mojave Desert.

  13. California Condor Critical Habitat

    Data.gov (United States)

    California Department of Resources — 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...

  14. 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.

  15. 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.

  16. 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.

  17. Area sensitivity in North American grassland birds: Patterns and processes

    Science.gov (United States)

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

    2009-01-01

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

  18. 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.

  19. Novel fine-scale aerial mapping approach quantifies grassland weed cover dynamics and response to management.

    Science.gov (United States)

    Malmstrom, Carolyn M; Butterfield, H Scott; Planck, Laura; Long, Christopher W; Eviner, Valerie T

    2017-01-01

    Invasive weeds threaten the biodiversity and forage productivity of grasslands worldwide. However, management of these weeds is constrained by the practical difficulty of detecting small-scale infestations across large landscapes and by limits in understanding of landscape-scale invasion dynamics, including mechanisms that enable patches to expand, contract, or remain stable. While high-end hyperspectral remote sensing systems can effectively map vegetation cover, these systems are currently too costly and limited in availability for most land managers. We demonstrate application of a more accessible and cost-effective remote sensing approach, based on simple aerial imagery, for quantifying weed cover dynamics over time. In California annual grasslands, the target communities of interest include invasive weedy grasses (Aegilops triuncialis and Elymus caput-medusae) and desirable forage grass species (primarily Avena spp. and Bromus spp.). Detecting invasion of annual grasses into an annual-dominated community is particularly challenging, but we were able to consistently characterize these two communities based on their phenological differences in peak growth and senescence using maximum likelihood supervised classification of imagery acquired twice per year (in mid- and end-of season). This approach permitted us to map weed-dominated cover at a 1-m scale (correctly detecting 93% of weed patches across the landscape) and to evaluate weed cover change over time. We found that weed cover was more pervasive and persistent in management units that had no significant grazing for several years than in those that were grazed, whereas forage cover was more abundant and stable in the grazed units. This application demonstrates the power of this method for assessing fine-scale vegetation transitions across heterogeneous landscapes. It thus provides means for small-scale early detection of invasive species and for testing fundamental questions about landscape dynamics.

  20. Estimation and Prediction of Grassland Cover in Western Mongolia Using MODIS-Derived Vegetation Indices

    National Research Council Canada - National Science Library

    Mikhail Yu Paltsyn; James P Gibbs; Liza V Iegorova; Giorgos Mountrakis

    2017-01-01

    ...) sensor, for estimating grassland cover measured at ground level on ninety-two 1 x 1 km blocks distributed from semidesert to high montane grasslands in the Sailugem Range of western Mongolia, where...

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

    Directory of Open Access Journals (Sweden)

    Jinfeng Chang

    2017-05-01

    Full Text Available Abstract 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 livestock production in Europe. However, there has been little work done to quantify the European-wide response of grassland to future climate change. Here we applied ORCHIDEE-GM v2.2, a grid-based model for managed grassland, over European grassland to estimate the impacts of future global change. Results Increases in grassland productivity are simulated in response to future global change, which are mainly attributed to the simulated fertilization effect of rising CO2. The results show significant phenology shifts, in particular an earlier winter-spring onset of grass growth over Europe. A longer growing season is projected over southern and southeastern Europe. In other regions, summer drought causes an earlier end to the growing season, overall reducing growing season length. Future global change allows an increase of management intensity with higher than current potential annual grass forage yield, grazing capacity and livestock density, and a shift in seasonal grazing capacity. We found a continual grassland soil carbon sink in Mediterranean, Alpine, North eastern, South eastern and Eastern regions under specific warming level (SWL of 1.5 and 2 °C relative to pre-industrial climate. However, this carbon sink is found to saturate, and gradually turn to a carbon source at warming level reaching 3.5 °C. Conclusions This study provides a European-wide assessment of the future changes in productivity and phenology of grassland, and their

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

    Science.gov (United States)

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

    2017-12-01

    Europe has warmed more than the global average (land and ocean) since pre-industrial times, and is also projected to continue to warm faster than the global average in the twenty-first century. According to the climate models ensemble projections for various climate scenarios, annual mean temperature of Europe for 2071-2100 is predicted to be 1-5.5 °C higher than that for 1971-2000. Climate change and elevated CO2 concentration are anticipated to affect grassland management and livestock production in Europe. However, there has been little work done to quantify the European-wide response of grassland to future climate change. Here we applied ORCHIDEE-GM v2.2, a grid-based model for managed grassland, over European grassland to estimate the impacts of future global change. Increases in grassland productivity are simulated in response to future global change, which are mainly attributed to the simulated fertilization effect of rising CO2. The results show significant phenology shifts, in particular an earlier winter-spring onset of grass growth over Europe. A longer growing season is projected over southern and southeastern Europe. In other regions, summer drought causes an earlier end to the growing season, overall reducing growing season length. Future global change allows an increase of management intensity with higher than current potential annual grass forage yield, grazing capacity and livestock density, and a shift in seasonal grazing capacity. We found a continual grassland soil carbon sink in Mediterranean, Alpine, North eastern, South eastern and Eastern regions under specific warming level (SWL) of 1.5 and 2 °C relative to pre-industrial climate. However, this carbon sink is found to saturate, and gradually turn to a carbon source at warming level reaching 3.5 °C. This study provides a European-wide assessment of the future changes in productivity and phenology of grassland, and their consequences for the management intensity and the carbon balance

  3. Nitrogen deposition threatens species richness of grasslands across Europe

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, C.J. [Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ (United Kingdom); Gowing, D.J.G. [Department of Life Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Dupre, C.; Diekmann, M. [Institute of Ecology, FB 2, University of Bremen, Leobener Str., DE-28359 Bremen (Germany); Dorland, E. [Section of Landscape Ecology, Department of Geobiology, Utrecht University, P.O. Box 80084, 3508 TB Utrecht (Netherlands); Gaudnik, C.; Alard, D.; Corcket, E. [University of Bordeaux 1. UMR INRA 1202 Biodiversity, Genes and Communities, Equipe Ecologie des Communautes, Batiment B8 - Avenue des Facultes, F-33405 Talence (France); Bleeker, A. [Department of Air Quality and Climate Change, Energy Research Centre of the Netherlands, P.O. Box 1, 1755 ZG Petten (Netherlands); Bobbink, R. [B-WARE Research Centre, Radboud University, P.O. Box 9010, 6525 ED Nijmegen (Netherlands); Fowler, D. [NERC Centre for Ecology and Hydrology, Bush Estate, Penicuik, Midlothian EH26 0QB (United Kingdom); Mountford, J.O. [NERC Centre for Ecology and Hydrology, MacLean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxfordshire OX10 8BB (United Kingdom); Vandvik, V. [Department of Biology, University of Bergen, Box 7800, N-5020 Bergen (Norway); Aarrestad, P.A. [Norwegian Institute for Nature Research, NO-7485 Trondheim (Norway); Muller, S. [Laboratoire des Interactions Ecotoxicologie, Biodiversite et Ecosystemes LIEBE, UMR CNRS 7146, U.F.R. Sci. F.A., Campus Bridoux, Universite Paul Verlaine, Avenue du General Delestraint, F-57070 Metz (France); Dise, N.B. [Department of Environmental and Geographical Science, Manchester Metropolitan University, Manchester M1 5GD (United Kingdom)

    2010-09-15

    Evidence from an international survey in the Atlantic biogeographic region of Europe indicates that chronic nitrogen deposition is reducing plant species richness in acid grasslands. Across the deposition gradient in this region (2-44 kg N ha{sup -1} yr{sup -1}) species richness showed a curvilinear response, with greatest reductions in species richness when deposition increased from low levels. This has important implications for conservation policies, suggesting that to protect the most sensitive grasslands resources should be focussed where deposition is currently low. Soil pH is also an important driver of species richness indicating that the acidifying effect of nitrogen deposition may be contributing to species richness reductions. The results of this survey suggest that the impacts of nitrogen deposition can be observed over a large geographical range. Atmospheric nitrogen deposition is reducing biodiversity in grasslands across Europe.

  4. 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.

  5. 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.

  6. 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.

  7. Grassland management impacts on soil carbon stocks: a new synthesis.

    Science.gov (United States)

    Conant, Richard T; Cerri, Carlos E P; Osborne, Brooke B; Paustian, Keith

    2017-03-01

    Grassland ecosystems cover a large portion of Earths' surface and contain substantial amounts of soil organic carbon. Previous work has established that these soil carbon stocks are sensitive to management and land use changes: grazing, species composition, and mineral nutrient availability can lead to losses or gains of soil carbon. Because of the large annual carbon fluxes into and out of grassland systems, there has been growing interest in how changes in management might shift the net balance of these flows, stemming losses from degrading grasslands or managing systems to increase soil carbon stocks (i.e., carbon sequestration). A synthesis published in 2001 assembled data from hundreds of studies to document soil carbon responses to changes in management. Here we present a new synthesis that has integrated data from the hundreds of studies published after our previous work. These new data largely confirm our earlier conclusions: improved grazing management, fertilization, sowing legumes and improved grass species, irrigation, and conversion from cultivation all tend to lead to increased soil C, at rates ranging from 0.105 to more than 1 Mg C·ha(-1) ·yr(-1) . The new data include assessment of three new management practices: fire, silvopastoralism, and reclamation, although these studies are limited in number. The main area in which the new data are contrary to our previous synthesis is in conversion from native vegetation to grassland, where we find that across the studies the average rate of soil carbon stock change is low and not significant. The data in this synthesis confirm that improving grassland management practices and conversion from cropland to grassland improve soil carbon stocks. © 2016 by the Ecological Society of America.

  8. Bird productivity and nest predation in agricultural grasslands

    Science.gov (United States)

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

    2012-01-01

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

  9. Contribution of radar images for grassland management identification

    Science.gov (United States)

    Dusseux, P.; Gong, X.; Corpetti, T.; Hubert-Moy, L.; Corgne, S.

    2012-09-01

    This paper is concerned with the identification of grassland management using both optical and radar data. In that context, grazing, mowing and a mix of these two managements are commonly used by the farmers on grassland fields. These practices and their intensity of use have different environmental impact. Thus, the objectives of this study are, firstly, to identify grassland management practices using a time series of optical and radar imagery at high spatial resolution and, secondly, to evaluate the contribution of radar data to improve identification of farming practices on grasslands. Because of cloud coverage and revisit frequency of satellite, the number of available optical data is limited during the vegetation period. Thus, radar data can be considered as an ideal complement. The present study is based on the use of SPOT, Landsat and RADARSAT-2 data, acquired in 2010 during the growing period. After a pre-processing step, several vegetation indices, biophysical variables, backscattering coefficients and polarimetric discriminators were computed on the data set. Then, with the help of some statistics, the most discriminating variables have been identified and used to classify grassland fields. In addition, to take into account the temporal variation of variables, dedicated indexes as first and second order derivatives were used. Classification process was based on training samples resulting from field campaigns and computed according six methods: Decision Trees, K-Nearest Neighbor, Neural Networks, Support Vector Machines, the Naive Bayes Classifier and Linear Discriminant Analysis. Results show that combined use of optical and radar remote sensing data is not more efficient for grassland management identification.

  10. Energy potential of biomass from conservation grasslands in Minnesota, USA.

    Science.gov (United States)

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

    2013-01-01

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

  11. 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...

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

    Science.gov (United States)

    Camille Richard; Yan Zhaoli; Du Guozhen

    2006-01-01

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

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

    Science.gov (United States)

    Diana Hadley; Xavier Basurto

    2006-01-01

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

  14. 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 ...

  15. Impacts of climate change on net primary productivity of grasslands in Inner Mongolia

    NARCIS (Netherlands)

    Li, Q.; Tuo Debao,; Zhang, L.; Wei, X.; Wei, Y.; Yang, N.; Xu, Y.; Anten, N.P.R.; Pan, X.

    2014-01-01

    Net primary productivity (NPP) of grasslands is a key variable for characterising carbon cycles in grassland ecosystems. The prediction of NPP in Inner Mongolia is important for adaptation to future climate change, food security and sustainable use of the grassland resources. The output from two

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

    Science.gov (United States)

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

    2005-01-01

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

  17. Productivity of North American grasslands is increased under future climate scenarios despite rising aridity

    Science.gov (United States)

    Grassland productivity is regulated by both temperature and the amount and timing of precipitation. Future climate change is therefore expected to influence grassland phenology and growth, with consequences for ecosystems and economies. However, the potential response of grasslands to climate change...

  18. The effect of grassland shifts on the avifauna of a South African ...

    African Journals Online (AJOL)

    Two distinct grassland types occur within Hluhluwe-iMfolozi Park (HiP): short stoloniferous grazing lawns and tall, tussocklike 'bunch' grasslands. Grazing lawns are maintained by grazing mammals, among which White Rhinoceros Ceratotherium simum is of major importance. By contrast, tall bunch grasslands are ...

  19. 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......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...

  20. Grassland management affects belowground carbon allocation in mountain grasslands and its resistance and resilience to drought

    Science.gov (United States)

    Karlowsky, Stefan; Augusti, Angela; Ingrisch, Johannes; Hasibeder, Roland; Bahn, Michael; Gleixner, Gerd

    2015-04-01

    Future climate scenarios do not only forecast increased extreme events during summer, but also more frequent drought events in the early season. In mountain grasslands, different land uses may contribute to the response of the ecosystem to climate changes, like drought in May and June. In this study, we examined the drought response of two differently managed grasslands, 1) a more intensive used meadow and 2) a less intensive used abandoned area. Our aim was to highlight differences in both resistance and resilience of ecosystem functioning, based on carbon (C) belowground allocation as a key function in the plant-rhizosphere continuum. Therefore, we used an isotopic approach and in particular, we used 13C pulse labelling to track the fate of newly assimilated C from leaves, to roots and to soil, up to different microbial communities. We performed two 13C pulse labellings, the first during the acute phase of drought, when the water status of soil was drastically decreased compared to the control; and the second during the recovery phase, when the soil water status was restored to control level. We followed the kinetics of 13C incorporation in above- and below-ground bulk material as well as non-structural sugars, in general soil microbial biomass, in different soil microbial communities and in CO2 respired from roots, up to 5 days from each labelling. Preliminary results from the 13C analyses of bulk phytomass material and soil microbial biomass indicate, as expected, different kinetics of aboveground 13C incorporation and its belowground allocation. During the acute phase of drought, 13C incorporation shows a decrease compared to the control for both land uses, with generally higher reductions in meadow treatments. Root 13C tracer dynamics follow the leaf 13C enrichment with a delay. High label amounts are found in leaves directly after labelling, whereas in roots high 13C incorporation is found first after 24 hours, accompanied by a fast decrease of 13C label in

  1. Plant diversity drives soil microbial biomass carbon in grasslands irrespective of global environmental change factors.

    Science.gov (United States)

    Thakur, Madhav Prakash; Milcu, Alexandru; Manning, Pete; Niklaus, Pascal A; Roscher, Christiane; Power, Sally; Reich, Peter B; Scheu, Stefan; Tilman, David; Ai, Fuxun; Guo, Hongyan; Ji, Rong; Pierce, Sarah; Ramirez, Nathaly Guerrero; Richter, Annabell Nicola; Steinauer, Katja; Strecker, Tanja; Vogel, Anja; Eisenhauer, Nico

    2015-11-01

    Soil microbial biomass is a key determinant of carbon dynamics in the soil. Several studies have shown that soil microbial biomass significantly increases with plant species diversity, but it remains unclear whether plant species diversity can also stabilize soil microbial biomass in a changing environment. This question is particularly relevant as many global environmental change (GEC) factors, such as drought and nutrient enrichment, have been shown to reduce soil microbial biomass. Experiments with orthogonal manipulations of plant diversity and GEC factors can provide insights whether plant diversity can attenuate such detrimental effects on soil microbial biomass. Here, we present the analysis of 12 different studies with 14 unique orthogonal plant diversity × GEC manipulations in grasslands, where plant diversity and at least one GEC factor (elevated CO2 , nutrient enrichment, drought, earthworm presence, or warming) were manipulated. Our results show that higher plant diversity significantly enhances soil microbial biomass with the strongest effects in long-term field experiments. In contrast, GEC factors had inconsistent effects with only drought having a significant negative effect. Importantly, we report consistent non-significant effects for all 14 interactions between plant diversity and GEC factors, which indicates a limited potential of plant diversity to attenuate the effects of GEC factors on soil microbial biomass. We highlight that plant diversity is a major determinant of soil microbial biomass in experimental grasslands that can influence soil carbon dynamics irrespective of GEC. © 2015 John Wiley & Sons Ltd.

  2. Impact of invertebrate herbivory in grasslands depends on plant species diversity.

    Science.gov (United States)

    Stein, Claudia; Unsicker, Sybille B; Kahmen, Ansgar; Wagner, Markus; Audorff, Volker; Auge, Harald; Prati, Daniel; Weisser, Wolfgang W

    2010-06-01

    Invertebrate herbivores are ubiquitous in most terrestrial ecosystems, and theory predicts that their impact on plant community biomass should depend on diversity and productivity of the associated plant communities. To elucidate general patterns in the relationship between invertebrate herbivory, plant diversity, and productivity, we carried out a long-term herbivore exclusion experiment at multiple grassland sites in a mountainous landscape of central Germany. Over a period of five years, we used above- and belowground insecticides as well as a molluscicide to manipulate invertebrate herbivory at 14 grassland sites, covering a wide range of plant species diversity (13-38 species/m2) and aboveground plant productivity (272-1125 g x m(-2) x yr(-1)), where plant species richness and productivity of the sites were not significantly correlated. Herbivore exclusion had significant effects on the plant communities: it decreased plant species richness and evenness, and it altered plant community composition. In particular, exclusion of belowground herbivores promoted grasses at the expense of herbs. In contrast to our expectation, herbivore effects on plant community biomass were not influenced by productivity. However, effect size of invertebrate herbivores was negatively correlated with plant diversity of the grasslands: the effect of herbivory on biomass tended to be negative at sites of high diversity and positive at sites of low diversity. In general, the effects of aboveground herbivores were relatively small as compared to belowground herbivores, which were important drivers of plant community composition. Our study is the first to show that variation in the effects of invertebrate herbivory on plant communities across a landscape is significantly influenced by plant species richness.

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

    Science.gov (United States)

    Cai, Jiangping; Weiner, Jacob; Wang, Ruzhen; Luo, Wentao; Zhang, Yongyong; Liu, Heyong; Xu, Zhuwen; Li, Hui; Zhang, Yuge; Jiang, Yong

    2017-07-01

    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 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 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 partly counteracted the positive effects of N addition on available trace element concentrations in the soil. Foliar Mn, Cu and Zn concentrations increased but Fe concentration decreased with N addition, resulting in foliar elemental imbalances among Fe and other selected trace elements. Water addition alleviated the effect of N addition. Forbs are more likely to suffer from Mn toxicity and Fe deficiency than grass species, indicating more sensitivity to changing elemental bioavailability in soil. Our results suggested that soil acidification due to N deposition may accelerate trace element cycling and lead to elemental imbalance in soil-plant systems of semi-arid grasslands and these impacts of N deposition on semi-arid grasslands were affected by water addition. These findings indicate an important role for soil trace elements in maintaining ecosystem functions associated with atmospheric N deposition and changing precipitation regimes in the future.

  4. Soil Aggregate Dynamics and Plant Community Response after Biosolids Application in a Semiarid Grassland.

    Science.gov (United States)

    Wallace, Brian M; Krzic, Maja; Newman, Reg F; Forge, Tom A; Broersma, Klaas; Neilsen, Gerry

    2016-09-01

    Biosolids may improve the ecological function of degraded semiarid grasslands, but an understanding of the plant community is essential. An experiment was established in 2001 to determine the effects of a single surface application of biosolids on soil aggregate stability and the composition of the plant community in a semiarid grassland in British Columbia, Canada. Four treatments were evaluated: (i) surface biosolids application at 20 (Bio-20) and (ii) 60 Mg ha (Bio-60), (iii) mineral fertilizer, and (iv) a control. All treatments were replicated in four blocks. Soil was sampled during the spring (May), summer (June-July), and fall (October) in 2005, 2006, and 2009; the plant community was assessed in 2009. The greatest increases in size of stable aggregates relative to the control were in the spring and summer, which coincided with a 1.6- to 2.1-fold increase in the spring concentration of N within stable aggregates when biosolids were applied at 20 and 60 Mg ha , respectively. Nitrogen concentrations from the Bio-60 treatment were not different from the control, but the Bio-20 treatment had 42% greater N than all other treatments during summer. Biosolids application in this ecosystem did not increase perennial forage grass species relative to the control, and when biosolids were applied at a rate of 60 Mg ha there was a 75% reduction in the perennial forage plant species. The application of biosolids to native grasslands in semiarid environments should be done cautiously, especially when winter annual plant species (e.g., cheatgrass [ L.]) are present before application. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  5. Effects of changing land use and climate on soil respiration and its components in mountain grassland

    Science.gov (United States)

    Bahn, M.; Gort, M.; Gruber, V.; Ladreiter-Knauss, T.; Schmitt, M.

    2009-04-01

    In mountain areas changes in land use and climate have been more pronounced than in many other parts of Europe. Soil respiration is the largest source of CO2 in terrestrial ecosystems and exhibits particularly high rates in Central European mountain meadows. Based on a multi-annual dataset and a number of ecosystem manipulation experiments we analyse possible effects of land management, land use and climate change on soil respiration and its components (including root, autotrophic and heterotrophic microbial) in mountain grasslands in the Austrian Central Alps. Our results indicate that 1) land management and land use change affect soil CO2 production and diffusion across the soil profile, as well as specific respiratory rates and the relative importance of the source components, 2) in spite of a rapid transfer and respiratory utilisation of fresh photosynthates in the plant-soil system, soil CO2 fluxes in mountain grasslands are well buffered against short-term changes in assimilate supply, as could be induced e.g. by land management practises or weather extremes, and 3) while climate affects soil respiratory fluxes via gross primary productivity at an annual scale, droughts occurring at shorter timescales have only minor effects on soil respiration and cause disproportionately larger reductions of canopy photosynthesis. In case the observed decoupling of soil CO2 fluxes from photosynthesis in response to land management and climate changes is to persist also at longer timescales, it might affect the ecosystem C balance significantly and result in a net C loss from mountain grassland soils.

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

    Science.gov (United States)

    Coop, Jonathan D; Givnish, Thomas J

    2008-04-01

    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 ungulate browsing on the growth, photosynthetic performance, and survival of transplanted ponderosa pine (Pinus ponderosa) seedlings at 32 sites straddling such reversed tree lines in the Valles Caldera National Preserve (VCNP) of the Jemez Mountains, New Mexico (USA). Seedling growth increased most strongly with increasing nighttime minimum temperatures away from the valley bottoms; seedlings experiencing the coldest temperatures on the caldera floor exhibited stunted needles and often no measurable height growth. Based on the chlorophyll fluorescence ratios PhiPSII and Fv/Fm, we found that low minimum temperatures, low soil moisture, and fine soil texture all contributed to photoinhibition. Neighboring herbs had only minor negative effects on seedlings. We found no effect of ungulates, but golden-mantled ground squirrels (Spermophilus lateralis) caused substantial seedling mortality. Second-year seedling survival was highest on sandy soils, and third-year survival was highest at sites with higher minimum temperatures. We conclude that differential tree seedling establishment driven by low minimum temperatures in the valley bottoms is the primary factor maintaining montane grasslands of the VCNP, although this process probably operated historically in combination with frequent surface fire to set the position of the tree line ecotone. As at alpine tree lines, reversed tree lines bordering montane and subalpine grasslands can represent temperature-sensitive boundaries of the tree life form.

  7. Grassland productivity in response to nutrient additions and herbivory is scale-dependent

    Directory of Open Access Journals (Sweden)

    Erica A.H. Smithwick

    2016-12-01

    Full Text Available Vegetation response to nutrient addition can vary across space, yet studies that explicitly incorporate spatial pattern into experimental approaches are rare. To explore whether there are unique spatial scales (grains at which grass response to nutrients and herbivory is best expressed, we imposed a large (∼3.75 ha experiment in a South African coastal grassland ecosystem. In two of six 60 × 60 m grassland plots, we imposed a scaled sampling design in which fertilizer was added in replicated sub-plots (1 × 1 m, 2 × 2 m, and 4 × 4 m. The remaining plots either received no additions or were fertilized evenly across the entire area. Three of the six plots were fenced to exclude herbivory. We calculated empirical semivariograms for all plots one year following nutrient additions to determine whether the scale of grass response (biomass and nutrient concentrations corresponded to the scale of the sub-plot additions and compared these results to reference plots (unfertilized or unscaled and to plots with and without herbivory. We compared empirical semivariogram parameters to parameters from semivariograms derived from a set of simulated landscapes (neutral models. Empirical semivariograms showed spatial structure in plots that received multi-scaled nutrient additions, particularly at the 2 × 2 m grain. The level of biomass response was predicted by foliar P concentration and, to a lesser extent, N, with the treatment effect of herbivory having a minimal influence. Neutral models confirmed the length scale of the biomass response and indicated few differences due to herbivory. Overall, we conclude that interpretation of nutrient limitation in grasslands is dependent on the grain used to measure grass response and that herbivory had a secondary effect.

  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 guild of bird species across North America. Shrinking ranges and population declines have been attributed to widespread habitat loss and increasingly fragmented landscapes of agriculture and other land-use practices that are misaligned with grassland bird conservation. Concurrent with habitat loss and degradation, temperate grasslands have experienced disproportionally faster rates of climate change compared to other terrestrial biomes. Grassland bird distributions and abundances often correlate with gradients in climate, but few studies have explored the consequences of weather on the demography of multiple grassland birds inhabiting a range of grassland fragments. To do so, we modeled the effects of temperature and precipitation on nesting success rates for a dozen grassland bird species comprising 21,000 nests from 81 individual studies across North America. We found that higher amounts of precipitation in the preceding year (bioyear) were associated with higher nesting success, but wetter conditions during the active breeding season reduced nesting success. In terms of temperature, extreme cold and hot springs were associated with lower rates of nesting success. Notably, the direct and indirect influence of temperature and precipitation on nesting success was moderated by grassland patch size. The positive effects of bioyear precipitation on nesting success were strongest for birds occupying smaller grassland patches, with little effect in larger grasslands. Conversely, warmer spring temperatures reduced nesting success in small grassland patches, but increased nesting success in the larger grasslands. Mechanisms underlying these differences may be patch-size induced variation in microclimates and predator activity. While the exact cause is not clear, large grassland patches, the most common metric of grassland conservation, appears to moderate the consequences of weather on grassland bird demography and could

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

    Science.gov (United States)

    Boval, Maryline; Angeon, Valérie; Rudel, Tom

    2017-02-01

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

  10. Remote Sensing Estimates of Grassland Aboveground Biomass Based on MODIS Net Primary Productivity (NPP: A Case Study in the Xilingol Grassland of Northern China

    Directory of Open Access Journals (Sweden)

    Fen Zhao

    2014-06-01

    Full Text Available The precise and rapid estimation of grassland biomass is an important scientific issue in grassland ecosystem research. In this study, based on a field survey of 1205 sites together with biomass data of the Xilingol grassland for the years 2005–2012 and the “accumulated” MODIS productivity starting from the beginning of growing season, we built regression models to estimate the aboveground biomass of the Xilingol grassland during the growing season, then further analyzed the overall condition of the grassland and the spatial and temporal distribution of the aboveground biomass. The results are summarized as follows: (1 The unitary linear model based on the field survey data and “accumulated” MODIS productivity data is the optimum model for estimating the aboveground biomass of the Xilingol grassland during the growing period, with the model accuracy reaching 69%; (2 The average aboveground biomass in the Xilingol grassland for the years 2005–2012 was estimated to be 14.35 Tg, and the average aboveground biomass density was estimated to be 71.32 g∙m−2; (3 The overall variation in the aboveground biomass showed a decreasing trend from the eastern meadow grassland to the western desert grassland; (4 There were obvious fluctuations in the aboveground biomass of the Xilingol grassland for the years 2005–2012, ranging from 10.56–17.54 Tg. Additionally, several differences in the interannual changes in aboveground biomass were observed among the various types of grassland. Large variations occurred in the temperate meadow-steppe and the typical grassland; whereas there was little change in the temperate desert-steppe and temperate steppe-desert.

  11. 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

    ) amendments and (2) disturbance in the form of mowing. We measured height, specific leaf area, leaf thickness and leaf density from individuals of 39 species in the control and C addition plots, and supplemented these trait values with database information on growth form, lifespan, nitrogen-fixing ability...... and seed mass.   Consistent with theoretical predictions, C addition favored short, large-seeded and nitrogen-fixing species, while mowing benefitted short species with high specific leaf area. However, native and exotic species did not differ in any of the measured traits, and neither group benefitted...

  12. 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

  13. Biomass productivity and carrying capacity of the natural grassland ...

    African Journals Online (AJOL)

    The study assessed the biomass productivity and then estimated the carrying capacity of the natural grassland on the Accra Plains of Ghana between January 1990 and February 1992. Eleven sampling sites with varying grass association, soil type and ease of accessibility were sampled. In each sampling site an area of 5.0 ...

  14. 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 ...

  15. 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.

  16. Productivity, biodiversity and nitrate in groundwater of multifunctional grassland

    NARCIS (Netherlands)

    Korevaar, H.; Geerts, R.H.E.M.

    2007-01-01

    Multifunctional land use is an option to increase economic and environmental sustainability and to make a region more attractive for local inhabitants and visitors. Between 2002 and 2004 we studied 76 grasslands on different farms. This paper presents results on production, flora and fauna

  17. Botanical composition, yield and nutritional quality of grassland in ...

    African Journals Online (AJOL)

    Harvesting at 90 d and application of 100 and 150 kg ha-1 N fertiliser had a higher (P < 0.05) total DM yield of the grassland. Crude protein, neutral detergent fibre, acid detergent fibre, cellulose, hemicellulose, phosphorus and IVDMD were significantly (P < 0.05) affected by the stage of harvesting. However, N fertiliser had ...

  18. Response of two semiarid grasslands to a second fire application

    Science.gov (United States)

    Carleton S. White; Rosemary L. Pendleton; Burton K. Pendleton

    2006-01-01

    Prescribed fire was used in two semiarid grasslands to reduce shrub cover, promote grass production, and reduce erosional loss that represents a potential non­point-source of sediment to degrade water quality. This study measured transported soil sediment, dynamics in soil surface microtopography, cover of the woody shrub, grass, and bare ground cover classes, and soil...

  19. Ecological dynamic model of grassland and its practical verification.

    Science.gov (United States)

    Zeng, Xiaodong; Wang, Aihui; Zhao, Gang; Shen, Samuel S P; Zeng, Xubin; Zeng, Qingcun

    2005-02-01

    Based on the physico-biophysical considerations, mathematical analysis and some approximate formulations generally adopted in meteorology and ecology, an ecological dynamic model of grassland is developed. The model consists of three interactive variables, i.e. the biomass of living grass, the biomass of wilted grass, and the soil wetness. The major biophysical processes are represented in parameterization formulas, and the model parameters can be determined inversely by using the observational climatological and ecological data. Some major parameters are adjusted by this method to fit the data (although incomplete) in the Inner Mongolia grassland, and other secondary parameters are estimated through sensitivity studies. The model results are well agreed with reality, e.g., (i) the maintenance of grassland requires a minimum amount of annual precipitation (approximately 300 mm); (ii) there is a significant relationship between the annual precipitation and the biomass of living grass; and (iii) the overgrazing will eventually result in desertification. A specific emphasis is put on the shading effect of the wilted grass accumulated on the soil surface. It effectively reduces the soil surface temperature and the evaporation, hence benefits the maintenance of grassland and the reduction of water loss in the soil.

  20. Bird Use of Grassland Habitat Patches at a Military Airfield

    Science.gov (United States)

    In light of reported declines in grassland bird populations in North America, information about their use of airfield habitats can help inform management decisions in the context of conflicting objectives of minimizing wildlife-aircraft collisions and helping to conserve grasslan...

  1. Collaborative approach passes field test on Mongolian grasslands ...

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

    2010-10-13

    Oct 13, 2010 ... The result was an open-access situation that put mounting pressure on a fragile ecosystem. Grasslands, increasingly affected by drought, became seriously overgrazed. Throughout the 1990s, the number of families engaged in herding more than doubled, and the livestock population increased by 30%.

  2. 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

  3. 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

  4. Speciation of Water-Extractable Organic Nutrients in Grassland Soils

    NARCIS (Netherlands)

    Ros, G.H.; Tschudy, T.C.; Chardon, W.J.; Temminghoff, E.J.M.; Salm, van der C.; Koopmans, G.F.

    2010-01-01

    The release of dissolved organic matter (DOM) from agricultural land can have a large impact on the transport of N and phosphorus (P) to surface waters leading to water quality impairment. The speciation of DOM in agricultural grassland soils has received little attention thus far. Quantification of

  5. Effects of grassland management on soil organic carbon density in ...

    African Journals Online (AJOL)

    The results showed that, by implementing CG, EG and MG practices, the grasslands in agro-pastoral ecotone of Northern China achieved higher SOC storage on decade scales when compared to FG field. CG field had the highest SOC density in 0 to 50 cm soil layer, while the least SOC density was displayed by FG.

  6. Evolution and management of the North American grassland herpetofauna

    Science.gov (United States)

    Norman J. Scott

    1996-01-01

    The modern North American grassland herpetofauna has evolved in situ since the Miocene. Pleistocene glaciation had a minimal effect except in the far North, with only minor displacements of some species. South of the glaciers, winters were warmer and summers cooler than at present. Snakelike reptiles, leaping frogs, and turtle "tanks" are favored adaptive...

  7. 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.

  8. Response of grasslands conversion to croplands on soil organic ...

    African Journals Online (AJOL)

    USER

    2010-03-22

    Mar 22, 2010 ... Frank AB, Tanaka DL, Hofmann L, Follett RF (1995). Soil carbon and nitrogen of Northern Great Plains grasslands as influenced by long-term grazing. J. rangeland manage. 48: 470-474. Guo L, Gifford R (2002). Soil carbon stocks and land use change: a meta analysis. Global Change Biol. (8): 345-360.

  9. Relative Greenness Index for assessing curing of grassland fuel

    NARCIS (Netherlands)

    Newnham, G.J.; Verbesselt, J.; Grant, I.F.; Anderson, S.A.J.

    2011-01-01

    Knowledge of the proportion of live and dead herbaceous fuel in grasslands is important in determining fire danger. This paper examines the Relative Greenness approach for quantifying these live and dead proportions. Relative Greenness places the Normalized Difference Vegetation Index (NDVI) in the

  10. Fine-scale species associations in alvar limestone grasslands

    NARCIS (Netherlands)

    Diekmann, M; Dupre, C; van der Maarel, E

    2004-01-01

    To examine the importance of positive or negative interactions of plant species on a micro-scale, species associations were studied in 38 1 m(2) - plots in alvar limestone grasslands on Oland, Sweden. Each plot was assumed to be homogeneous as to its environmental conditions and spatial distribution

  11. Grasslands: A Source of Secondary Metabolites for Livestock Health.

    Science.gov (United States)

    Poutaraud, Anne; Michelot-Antalik, Alice; Plantureux, Sylvain

    2017-08-09

    The need for environmentally friendly practices in animal husbandry, in conjunction with the reduction of the use of synthetic chemicals, leads us to reconsider our agricultural production systems. In that context, grassland secondary metabolites (GSMs) could offer an alternative way to support to livestock health. In fact, grasslands, especially those with high dicotyledonous plant species, present a large, pharmacologically active reservoir of secondary metabolites (e.g., phenolic compounds, alkaloids, saponins, terpenoids, carotenoids, and quinones). These molecules have activities that could improve or deteriorate health and production. This Review presents the main families of GSMs and uses examples to describe their known impact on animal health in husbandry. Techniques involved for their study are also described. A particular focus is put on anti-oxidant activities of GSMs. In fact, numerous husbandry pathologies, such as inflammation, are linked to oxidative stress and can be managed by a diet rich in anti-oxidants. The different approaches and techniques used to evaluate grassland quality for livestock health highlight the lack of efficient and reliable technics to study the activities of this complex phytococktail. Better knowledge and management of this animal health resource constitute a new multidisciplinary research field and a challenge to maintain and valorize grasslands.

  12. Characteristics of fire behaviour in the montane grasslands of Natal ...

    African Journals Online (AJOL)

    Fire behaviour characteristics were investigated in the montane grasslands of the Natal Drakensberg. The behaviour of experimental fires was measured together with the accompanying biotic and abiotic conditions. Estimates of heat yield, mass of available fuel and forward rate of spread enabled the calculation of intensity ...

  13. Assessment of heavy metal content in soil and grasslands in ...

    African Journals Online (AJOL)

    Investigations were conducted in the N.P. Durmitor area of Montenegro where anthropogenic activities are negatively impacting forests and grasslands. According to meteorological data, this area has been polluted with heavy metals via aero deposition. The aim of this paper was to present an assessment which describes ...

  14. Response of grasslands conversion to croplands on soil organic ...

    African Journals Online (AJOL)

    This study investigated the effects of two types of grasslands conversion to croplands on soil organic carbon (SOC) in Bashang area where it is a typical agro-pastoral ecotone of Northern China using a pare-site method. The results showed that the SOC contents and densities decreased with increasing soil depth. The soil ...

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

    African Journals Online (AJOL)

    A dual-beam surface-layer scintillometer (SLS) was used to estimate sensible heat flux (H) every 2 min for a path length of either 50 or 101 m, for more than 30 months in a mesic grassland in eastern South Africa. The SLS method relies on Monin-Obukhov similarity theory, the correlation between the laser beam signal ...

  16. Water use of grasslands, agroforestry systems and indigenous forests

    CSIR Research Space (South Africa)

    Everson, CS

    2011-12-01

    Full Text Available of introduced tree species exhibit a relatively high annual ETa, when compared to seasonal grasslands and deciduous trees that only maintain their transpiring canopy during summer. Quantification of the annual volumes of water used by these different vegetation...

  17. Salt, history and culture in the western grasslands of Cameroon ...

    African Journals Online (AJOL)

    This paper examines the socio-cultural value of salt among the people of the western grasslands of Cameroon from the precolonial era to contemporary times. Salt was andremains an important condiment used in households, marriages, treatment of the sick, initiation and other cultural ceremonies throughout the western ...

  18. The effects of fire on grassland bird communities of Barberspan ...

    African Journals Online (AJOL)

    Considering the frequent nature of fires and resultant drastic change in habitat following fire, research on the effects of fire on birds in the grasslands of South Africa is surprisingly scarce. For at least five months after burns we followed the changes in bird species composition, species richness and densities of two controlled ...

  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. Multivariate analysis of grassland in the Thee Rivers area, Natal ...

    African Journals Online (AJOL)

    Twenty grassland sites in the Three Rivers area, Natal, were sampled for presence of grass species in 20 8ft square quadrats placed in a restricted random manner at each site. The data were analysed using Wisconsin ordination principal components ordination and normal association analysis. Comparable results were ...

  1. Acacia karroo invasion of grassland: environmental and biotic effects influencing seedling emergence and establishment.

    Science.gov (United States)

    O'Connor, T G

    1995-08-01

    Acacia karroo Hayne is the most important woody invader of grassland in South Africa, and can greatly reduce the productivity of grassland. A field experiment was conducted to test the hypotheses that emergence, growth and the 1st year's survival of Acacia karroo would be enhanced by (1) defoliation of the grass sward, (2) increased irradiance, (3) increased moisture availability and (4) its germination within cattle dung pats. The study was conducted on one site above and one below the natural altitudinal treeline of this species in grassland of the eastern Cape, South Africa. Not one seedling emerged from dung pats. Neither location nor the other treatments affected the density of emerging seedlings, although only 40.4 seedlings m-2 emerged of the 200 seeds m-2 planted. Shading dramatically increased the density of surviving seedlings. In the open, only 3 and 1.5 seedlings m-2 remained respectively at the end of the growing season or the beginning of the next, compared to 23.3 and 19.5 seedlings m-2 under shading for these respective times. This was attributed to the effect of shade on moisture availability in a season which received only 54% of average rainfall. Seedling survival until the end of the growing season was enhanced (30%) by shade at both sites, but also by supplemental water (24%) and defoliation of the sward (7%) at the site above the treeline. Across sites and treatments, seedling survival was related to moisture availability, with no or poor survival for < 500 mm rainfall, indicating this species can only establish in certain rainfall years. Seedling survival over winter was not influenced by treatment, but was greater for larger seedlings. Treatments affected seedling size, in particular seedlings growing under shade and within a dense grass canopy were etiolated. A. karroo seedlings are capable of establishing and surviving within a dense grass sward for at least a year, tolerant of low irradiance and of interference, which, because most seeds

  2. Phosphorus and Nitrogen Co-Limit Global Grassland Productivity

    Science.gov (United States)

    Fay, P. A.; Prober, S. M.; Harpole, W. S.; Knops, J. M. H.; Bakker, J. D.; Borer, E. T.; MacDougall, A. S.; Seabloom, E. W.; Wragg, P. D.; Lind, E. M.

    2014-12-01

    Terrestrial ecosystem primary productivity has been considered to be primarily nitrogen (N) - limited, but may be co-limited by phosphorus (P), and possibly by potassium and micronutrients (K+m). The frequency, magnitude, and global extent of single or multiple nutrient limitations are poorly understood in natural systems, but can influence how anthropogenic nutrient enrichment affects ecosystem productivity and provisioning of ecosystem goods and services. We examined the occurrence and magnitude of nutrient limitation of aboveground net primary productivity (ANPP) by N, P, and K+m at 42 grassland sites on five continents in the Nutrient Network (https://www.nutnet.umn.edu). N, P, and K+m were factorially applied annually in a randomized block design at all sites. ANPP was measured annually for 3 to 5 years by clipping and weighing standing aboveground biomass. We found clear evidence for nutrient limitation of ANPP in these grasslands. Across all sites and years, the combined addition of N and P increased ANPP by 39% over controls, more than occurred if either was added alone (N: 18%; P: 9%), suggesting co-limitation of ANPP by both nutrients. Co-limitation by other nutrient combinations was not detected. At individual sites, ANPP limitation was most often alleviated by adding N and P together, but K+m addition alleviated ANPP limitation at three sites. Also, site-level limitation of ANPP by any one nutrient was positively correlated (R2 0.07 to 0.21) with limitation by other single or multiple nutrients, suggesting generalized multiple nutrient limitation. We found no differences in nutrient limitation of ANPP among continents or management practices, between native and previously cultivated grasslands, or with site soil properties or climate. These novel patterns of nutrient limitation of ANPP in grasslands around the global contradict the long-held idea that N is the primary nutrient limiting productivity in these ecosystems. Grasslands are globally important

  3. Mycorrhizal Productivity Following Woody Plant Invasion of Grassland

    Science.gov (United States)

    Boutton, T. W.; Rowe, H. I.; Ariza, M. C.; Miller, R. M.; Filley, T. R.

    2008-12-01

    Mycorrhizal fungi play an important role in soil carbon storage and dynamics through the production of recalcitrant organic compounds (e.g., glomalin and chitin), and through the production of hyphae which entangle and enmesh soil particles to form aggregates which physically protect organic matter from decomposer organisms. Despite these important functions, little is known regarding rates of mycorrhizal productivity and how these rates might be influenced by changes in plant community composition. We quantified mycorrhizal production in a subtropical savanna parkland in southern Texas where woody plants have invaded areas that were once open grassland. Mycorrhizal ingrowth bags (3 x 10 cm) were made from 50 μm nylon mesh, filled with sterile sand (200-600 μm particle size), and deployed in the field in triplicate in remnant grasslands (n=15), and in woody plant stands (n=13) ranging in age from 15 to 86 yrs. Ingrowth bags were installed in May and harvested in Oct 2007 after 156 days. Hyphae were isolated by flotation/filtration, cleaned thoroughly to remove sand, freeze-dried, and weighed. Microscopic examination indicated that nearly all hyphae recovered from ingrowth bags were from arbuscular mycorrhizal fungi. During the ingrowth period, nearly 4X more hyphal biomass accumulated in wooded areas (9.00 ± 3.84 g m- 2) compared to remnant grasslands (2.35 ± 0.56 g m-2). Hyphal productivity rates increased linearly with woody plant stand age (r = 0.89) from 15 ± 4 mg m-2 day-1 in grasslands (time 0) up to 58-98 mg m-2 day-1 in wooded areas >65 yrs old. When these productivity rates are annualized, we find that hyphal productivity represents approximately 4% of aboveground net primary productivity (ANPP) in wooded areas, and 2% of ANPP in remnant grasslands. These observations are consistent with concurrent studies showing that glomalin concentrations and chitinase enzyme activity both increase in soils with time following woody encroachment into grassland

  4. Grassland Phenology Response to Drought in the Canadian Prairies

    Directory of Open Access Journals (Sweden)

    Tengfei Cui

    2017-12-01

    Full Text Available Drought is a significant climatic disturbance in grasslands, yet the impact drought caused by global warming has on grassland phenology is still unclear. Our research investigates the long-term variability of grassland phenology in relation to drought in the Canadian prairies from 1982 to 2014. Based on the start of growing season (SOG and the end of growing season (EOG derived from Global Inventory Modeling and Mapping Studies (GIMMS NDVI3g datasets, we found that grasslands demonstrated complex phenology trends over our study period. We retrieved the drought conditions of the prairie ecozone at multiple time scales from the 1- to 12-month Standardized Precipitation Evapotranspiration Index (SPEI. We evaluated the correlations between the detrended time series of phenological metrics and SPEIs through Pearson correlation analysis and identified the dominant drought where the maximum correlations were found for each ecozone and each phenological metric. The dominant drought over preceding months account for 14–33% and 26–44% of the year-to-year variability of SOG and EOG, respectively, and fewer water deficits would favor an earlier SOG and delayed EOG. The drought-induced shifts in SOG and EOG were determined based on the correlation between the dominant drought and the year-to-year variability using ordinary least square (OLS method. Our research also quantifies the correlation between precipitation and the evolution of the dominant droughts and the drought-induced shifts in grassland phenology. Every millimeter (mm increase in precipitation accumulated over the dominant periods would cause SOG to occur 0.06–0.21 days earlier, and EOG to occur 0.23–0.45 days later. Our research reveals a complex phenology response in relation to drought in the Canadian prairie grasslands and demonstrates that drought is a significant factor in the timing of both SOG and EOG. Thus, it is necessary to include drought-related climatic variables when

  5. Water use in California

    Science.gov (United States)

    Brandt, Justin; Sneed, Michelle; Rogers, Laurel Lynn; Metzger, Loren F.; Rewis, Diane; House, Sally F.

    2014-01-01

    As part of the USGS National Water Use Compilation, the California Water Science Center works in cooperation with local, State, and Federal agencies as well as academic and private organizations to collect and report total water withdrawals for California. The 2010 California water use data are aggregated here, in this website, for the first time. The California Water Science Center released these data ahead of the online USGS National Water Use Compilation circular report, in response to increased interest associated with current drought conditions. The national report is expected to be released late in 2014. The data on this website represents the most current California water use data available in the USGS National Water Use Compilation. It contains a section on water use in California for 2010. Water-use estimates are compiled by withdrawal source type, use category, and county. Withdrawal source types include groundwater, both fresh and saline,

  6. Effects of compost and manure additions on the greenhouse gas dynamics of managed grasslands

    Science.gov (United States)

    DeLonge, M. S.; Silver, W. L.

    2013-12-01

    Grasslands cover approximately 30% of the terrestrial land surface, and have significant potential to increase soil C storage and thus lower atmospheric CO2 concentrations. Organic matter amendments (e.g., compost, manure) have been shown to be effective at increasing grassland soil C both through direct addition and by increasing net primary productivity. However, organic matter additions can also increase N2O and CH4 fluxes. The effects of organic matter amendments on both soil C and greenhouse gas emissions are dependent on their physical and chemical qualities. To explore the impacts of organic matter amendments of different chemical and physical qualities on soil C and greenhouse gas emissions we established research plots on three managed annual grasslands in California. Three replicate blocks were established at each site and included an untreated control, a manure treatment, and a compost treatment. At one site, an additional compost with a lower nitrogen content was also tested. In October 2011, a 1 cm layer of the designated amendment was added to each plot. All plots were sampled for soil (C and N, bulk density, temperature, moisture) and plant (community, aboveground biomass) properties, prior to and for two years following treatment. Plots were also sampled intensively for N2O, CH4, and CO2 fluxes using static chambers on over 35 days throughout the two rainy seasons, where sampling days were selected to target pulses following rain events. Results show that the amendments differentially affected soil C and greenhouse gases among the treatments. One year after treatment, C concentrations in the top 10 cm of soils had increased at all three sites by a mean of 0.5-1% on plots that received either compost treatment, but not on those that received manure. Lower in the profile (10-30 cm), C concentrations were increased by a smaller amount (<0.3%) and only in two of the sites. The untreated grassland soils were a small source of N2O during the first few

  7. Southern California Particle Center

    Data.gov (United States)

    Federal Laboratory Consortium — At the Southern California Particle Center, center researchers will investigate the underlying mechanisms that produce the health effects associated with exposure to...

  8. Warming reduces carbon losses from grassland exposed to elevated atmospheric carbon dioxide.

    Directory of Open Access Journals (Sweden)

    Elise Pendall

    Full Text Available The flux of carbon dioxide (CO2 between terrestrial ecosystems and the atmosphere may ameliorate or exacerbate climate change, depending on the relative responses of ecosystem photosynthesis and respiration to warming temperatures, rising atmospheric CO2, and altered precipitation. The combined effect of these global change factors is especially uncertain because of their potential for interactions and indirectly mediated conditions such as soil moisture. Here, we present observations of CO2 fluxes from a multi-factor experiment in semi-arid grassland that suggests a potentially strong climate - carbon cycle feedback under combined elevated [CO2] and warming. Elevated [CO2] alone, and in combination with warming, enhanced ecosystem respiration to a greater extent than photosynthesis, resulting in net C loss over four years. The effect of warming was to reduce respiration especially during years of below-average precipitation, by partially offsetting the effect of elevated [CO2] on soil moisture and C cycling. Carbon losses were explained partly by stimulated decomposition of soil organic matter with elevated [CO2]. The climate - carbon cycle feedback observed in this semiarid grassland was mediated by soil water content, which was reduced by warming and increased by elevated [CO2]. Ecosystem models should incorporate direct and indirect effects of climate change on soil water content in order to accurately predict terrestrial feedbacks and long-term storage of C in soil.

  9. Resistance and resilience of soil respiration to recurring summer drought in temperate mountain grassland

    Science.gov (United States)

    Ladreiter-Knauss, Thomas; Walter, Eric; Gruber, Verena; Schmitt, Michael; Ingrisch, Johannes; Hasibeder, Roland; Bahn, Michael

    2013-04-01

    Mountain grasslands are highly sensitive to climatic changes and soil respiration (Rs) is their largest source for CO2 emissions. As a contribution to the EU-project Carbo-Extreme and a national (FWF) project we studied how experimental summer drought and subsequent rewetting affects soil respiration over five subsequent years. The study site was a temperate mountain meadow at 1820m in the Austrian Central Alps. Drought was simulated with rain-out-shelters keeping off precipitation over a period of ca. 2 months of each year, which reduced the soil water content in the main rooting horizon to less than 20%vol (i.e. 20-30% relative extractable water). Rs measurements were performed with automated chambers and were complemented by episodic manual measurements on shallow and deep collars. Rs and its temperature sensitivity decreased at a soil moisture threshold of 20 - 30%vol, with the threshold increasing to higher values from the first to the last year of drought. Soil CO2 efflux was strongly stimulated after rainfall following drought, where Rs exceeded the flux rates of the control plots. Post-rewetting Rs remained enhanced for weeks in the first three years of the experiment. In the fourth and fifth year rewetting caused only a short pulse of soil CO2 emissions, after which Rs decreased below values in control plots for weeks. We conclude that recurring summer drought may alter the resistance and resilience of soil respiration in temperate grassland, with implications for its annual carbon balance.

  10. Effects of soil warming and nitrogen addition on soil respiration in a New Zealand tussock grassland.

    Science.gov (United States)

    Graham, Scott L; Hunt, John E; Millard, Peter; McSeveny, Tony; Tylianakis, Jason M; Whitehead, David

    2014-01-01

    Soil respiration (RS) represents a large terrestrial source of CO2 to the atmosphere. Global change drivers such as climate warming and nitrogen deposition are expected to alter the terrestrial carbon cycle with likely consequences for RS and its components, autotrophic (RA) and heterotrophic respiration (RH). Here we investigate the impacts of a 3°C soil warming treatment and a 50 kg ha(-1) y(-1) nitrogen addition treatment on RS, RH and their respective seasonal temperature responses in an experimental tussock grassland. Average respiration in untreated soils was 0.96±0.09 μmol m(-2) s(-1) over the course of the experiment. Soil warming and nitrogen addition increased RS by 41% and 12% respectively. These treatment effects were additive under combined warming and nitrogen addition. Warming increased RH by 37% while nitrogen addition had no effect. Warming and nitrogen addition affected the seasonal temperature response of RS by increasing the basal rate of respiration (R10) by 14% and 20% respectively. There was no significant interaction between treatments for R10. The treatments had no impact on activation energy (E0). The seasonal temperature response of RH was not affected by either warming or nitrogen addition. These results suggest that the additional CO2 emissions from New Zealand tussock grassland soils as a result of warming-enhanced RS constitute a potential positive feedback to rising atmospheric CO2 concentration.

  11. Contrasting effects of elevated CO2 and warming on nitrogen cycling in a semiarid grassland.

    Science.gov (United States)

    Dijkstra, Feike A; Blumenthal, Dana; Morgan, Jack A; Pendall, Elise; Carrillo, Yolima; Follett, Ronald F

    2010-07-01

    *Simulation models indicate that the nitrogen (N) cycle plays a key role in how other ecosystem processes such as plant productivity and carbon (C) sequestration respond to elevated CO(2) and warming. However, combined effects of elevated CO(2) and warming on N cycling have rarely been tested in the field. *Here, we studied N cycling under ambient and elevated CO(2) concentrations (600 micromol mol(-1)), and ambient and elevated temperature (1.5 : 3.0 degrees C warmer day:night) in a full factorial semiarid grassland field experiment in Wyoming, USA. We measured soil inorganic N, plant and microbial N pool sizes and NO(3)(-) uptake (using a (15)N tracer). *Soil inorganic N significantly decreased under elevated CO(2), probably because of increased microbial N immobilization, while soil inorganic N and plant N pool sizes significantly increased with warming, probably because of increased N supply. We observed no CO(2 )x warming interaction effects on soil inorganic N, N pool sizes or NO(3)(-) uptake in plants and microbes. *Our results indicate a more closed N cycle under elevated CO(2) and a more open N cycle with warming, which could affect long-term N retention, plant productivity, and C sequestration in this semiarid grassland.

  12. Effects of Simulated Climate Conditions on Phosphorus Cycling in an Annual Grassland

    Science.gov (United States)

    Mellett, T.; Defforey, D.; Paytan, A.

    2012-12-01

    The Jasper Ridge Global Change Experiment is a long-term study of the effects of simulated climate change conditions on an annual grassland. The different treatments consist of elevated atmospheric CO2 levels, enhanced nitrate deposition, as well as higher temperatures and precipitation rates. The above ground vegetation from each plot is harvested and separated by species, with the dominant species being selected for analysis. The aim of this study is to investigate the effects of different climate conditions on the phosphorus content and phosphorus cycling in terrestrial plants. Phosphorus content in grass samples is determined using the colorimetric reaction (soluble reactive phosphorus content), as well as combustion and acid digestion (total phosphorus content). Since phosphorus only has one stable isotope, the δ18O signature in phosphate is used as a proxy to investigate phosphorus cycling in this ecosystem. These three tools will be combined and evaluated as indicators for phosphorus limitation in each respective treatment site and provide a better understanding of phosphorus cycling in annual grasslands and the potential effects of climate change on phosphorus cycling.

  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. Mesocarnivore Surveys on Lawrence Livermore National Laboratory Site 300, Alameda and San Joaquin Counties, California

    Energy Technology Data Exchange (ETDEWEB)

    Clark, H O; Smith, D A; Cypher, B L; Kelly, P A; Woollett, J S

    2004-11-16

    Lawrence Livermore National Laboratory (LLNL), operated under cooperative agreement between the University of California and the U. S. Department of Energy, administers and operates an approximately 11 mi{sup 2} (28 km{sup 2}) test site in the remote hills at the northern end of the South Coast Ranges of Central California (Figure 1). Known as Site 300, this expanse of rolling hills and canyons supports a diverse array of grassland communities typical of lowland central California. The facility serves a variety of functions related to testing non-nuclear explosives, lasers, and weapons subsystems. The primary purpose of this project was to determine the presence of any mesocarnivores on Site 300 that use the property for foraging, denning, and other related activities. The surveys occurred from mid-September to mid-October, 2002.

  16. Fertilization and irrigation of Eucalyptus in southern California

    Science.gov (United States)

    Paul W. Moore

    1983-01-01

    An experiment to determine the interaction of three levels of irrigation, three levels of fertility and three densities of planting was started at the University of California Moreno Ranch in 1982. Differential irrigation and fertility treatments will begin in June of 1983. Some current practices of irrigation and fertilization by southern California growers are...

  17. Co-evolving Physical and Biological Organization in Step-pool Channels: Experiments from a Restoration Reach on Wildcat Creek, California

    Science.gov (United States)

    Chin, A.; O'Dowd, A. P.; Mendez, P. K.; Velasco, K. Z.; Leventhal, R. D.; Storesund, R.; Laurencio, L. R.

    2014-12-01

    Step-pools are important features in fluvial systems. Through energy dissipation, step-pools provide stability in high-energy environments that otherwise may erode and degrade. Although research has focused on geomorphological aspects of step-pool channels, the ecological significance of step-pool streams is increasingly recognized. Step-pool streams often contain higher density and diversity of benthic macroinvertebrates and are critical habitats for organisms such as salmonids and tailed frogs. Step-pools are therefore increasingly used to restore eroding channels and improve ecological conditions. This paper addresses a restoration reach of Wildcat Creek in Berkeley, California that featured an installation of step-pools in 2012. The design framework recognized step-pool formation as a self-organizing process that produces a rhythmic morphology. After placing step particles at locations where step-pools are expected to form according to hydraulic theory, the self-organizing approach allowed fluvial processes to refine the rocks into adjusted sequences over time. In addition, a 30-meter "experimental" reach was created to explore the co-evolution of geomorphological and ecological characteristics. After constructing a plane bed channel, boulders and cobbles piled at the upstream end allowed natural flows to mobilize and sort them into step-pool sequences. Ground surveys and LiDAR recorded the development of step-pool sequences over several seasons. Concurrent sampling of benthic macroinvertebrates documented the formation of biological communities in conjunction with habitat. Biological sampling in an upstream reference reach provided a comparison with the restored reach over time. Results to date show an emergent step-pool channel with steps that segment the plane bed into initial step and pool habitats. Biological communities are beginning to form, showing more distinction among habitat types during some seasons, although they do not yet approach reference

  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. 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.

  20. The Development of a Comprehensive First-Year Experience Program for the University of Southern California: Using an Innovation Gap Analysis Model

    Science.gov (United States)

    Studdert, Thomas Patrick

    2013-01-01

    Using an innovation adaptation of the gap analysis approach of Richard Clark and Fred Estes, the collegiate First-Year Experience (FYE) consisting of comprehensive and intentional curricular and co-curricular initiatives was examined. Conceptualization and operationalization of the goal for a FYE program was based on 3 student development theories…

  1. 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.

  2. 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

  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. California-Baja California border master plan - plan maestro fronterizo California-Baja California : executive summary.

    Science.gov (United States)

    2008-09-01

    Crossborder travel at the six land ports of entry (POEs) in the California-Baja California region has grown : significantly over the years. The San Diego County-Tijuana/Tecate region is home to the San Ysidro- : Puerta Mxico, the Otay Mesa-Mesa de ...

  5. California-Baja California border master plan - plan maestro fronterizo California-Baja California.

    Science.gov (United States)

    2008-09-01

    Crossborder travel at the six land ports of entry (POEs) in the California-Baja California region has grown : significantly over the years. The San Diego County-Tijuana/Tecate region is home to the San Ysidro- : Puerta Mxico, the Otay Mesa-Mesa de ...

  6. California's Reference Crisis.

    Science.gov (United States)

    Childers, Thomas A.

    1994-01-01

    Social and economic issues affecting the vitality of public libraries in California are discussed. A 1993 study by the California State Library identified diminishing reference skills and reference collections, reduced funding which impacted staffing, increased demand, technology change, and language/culture issues as contributing factors to…

  7. Multitrophic effects of nutrient addition in upland grassland.

    Science.gov (United States)

    Fountain, M T; Brown, V K; Gange, A C; Symondson, W O C; Murray, P J

    2008-06-01

    Although the effects of nutrient enhancement on aquatic systems are well documented, the consequences of nutritional supplements on soil food webs are poorly understood, and results of past research examining bottom-up effects are often conflicting. In addition, many studies have failed to separate the effects of nutrient enrichment and the physical effects of adding organic matter. In this field study, we hypothesised that the addition of nitrogen to soil would result in a trophic cascade, through detritivores (Collembola) to predators (spiders), increasing invertebrate numbers and diversity. Nitrogen and lime were added to plots in an upland grassland in a randomised block design. Populations of Collembola and spiders were sampled by means of pitfall traps and identified to species. Seventeen species of Collembola were identified from the nitrogen plus lime (N+L) and control plots. Species assemblage, diversity, richness, evenness and total number were not affected by nutrient additions. However, there was an increase in the number of Isotomidae juveniles and Parisotoma anglicana trapped in the N+L plots. Of the 44 spider species identified, over 80% were Linyphiidae. An effect on species assemblage from the addition of N+L to the plots was observed on two of the four sampling dates (July 2002 and June 2003). The linyphiid, Oedothorax retusus, was the only species significantly affected by the treatments and was more likely to be trapped in the control plots.The increased number of juvenile Collembola, and change in community composition of spiders, were consequences of the bottom-up effect caused by nutrient inputs. However, despite efforts to eliminate the indirect effects of nutrient inputs, a reduction in soil moisture in the N+L plots cannot be eliminated as a cause of the invertebrate population changes observed. Even so, this experiment was not confounded by the physical effects of habitat structure reported in most previous studies. It provides evidence

  8. Variability of annual CO2 exchange from Dutch grasslands

    Directory of Open Access Journals (Sweden)

    A. Schrier-Uijl

    2007-10-01

    Full Text Available 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, using the eddy-covariance (EC technique, but in different years. The NEE does not include any import or export other than CO2. The photosynthesis-light response analysis technique is used along with the respiration-temperature response technique to partition NEE into Gross Primary Production (GPP and Ecosystem Respiration (Re and to obtain the eco-physiological characteristics of the sites at the field scale. Annual sums of NEE, GPP and Re are then estimated using the fitted response curves with observed radiation and air temperature from a meteorological site in the centre of The Netherlands as drivers. These calculations are carried out for four years (2002–2005. Land use and management histories are not considered. The estimated annual Re for all individual sites is more or less constant per site and the average for all sites amounts to 1390±30 gC m−2 a−1. The narrow uncertainty band (±2% reflects the small differences in the mean annual air temperature. The mean annual GPP was estimated to be 1325 g C m−2 a−1, and displays a much higher standard deviation, of ±110 gC m−2 a−1 (8%, which reflects the relatively large variation in annual solar radiation. The mean annual NEE amounts to –65±85 gC m−2 a−1. From two sites, four-year records of CO2 flux were available and analyzed (2002–2005. Using the weather record of 2005 with optimizations from the other years, the standard deviation of annual GPP was estimated to be 171–206 gC m−2 a−1 (8–14%, of annual Re 227–247 gC m−2 a−1 (14–16% and of annual NEE 176–276 gC m−2 a−1. The inter-site standard deviation was higher for GPP and Re, 534 gC m−2 a−1 (37

  9. Molt and aging criteria for four North American grassland passerines

    Science.gov (United States)

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

    2008-01-01

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

  10. Forest succession and population viability of grassland plants

    DEFF Research Database (Denmark)

    Lehtilä, Kari; Dahlgren, Johan; Garcia, Maria Begona

    2016-01-01

    Time lags in responses of organisms to deteriorating environmental conditions delay population declines and extinctions. We examined how local processes at the population level contribute to extinction debt, and how cycles of habitat deterioration and recovery may delay extinction. We carried out...... the environmental conditions that enable long-term persistence and to design management for species experiencing extinction debts.......Time lags in responses of organisms to deteriorating environmental conditions delay population declines and extinctions. We examined how local processes at the population level contribute to extinction debt, and how cycles of habitat deterioration and recovery may delay extinction. We carried out...... a demographic analysis of the fate of the grassland perennial Primula veris after the cessation of grassland management, where we used either a unidirectional succession model for forest habitat or a rotation model with a period of forest growth followed by a clear-cut and a new successional cycle...

  11. Patterns of woody plant invasion in an Argentinean coastal grassland

    Science.gov (United States)

    Alberio, Constanza; Comparatore, Viviana

    2014-01-01

    Coastal dune grasslands are fragile ecosystems that have historically been subjected to various types of uses and human activities. In Buenos Aires Province (Argentina), these areas are frequently afforested for urban and touristic development. The introduction and subsequent spread of exotic tree species is one of the main threats to conservation of natural grasslands as invasive trees strongly transform their structure and composition. The aim of this study was to identify patterns of woody plant invasion comparing plant communities and environmental variables between invaded and non-invaded areas surrounding the coastal village of Mar Azul, Argentina. Coastal grasslands in this area are being invaded by Populus alba (white poplar) and Acacia longifolia (coast wattle). The height of the saplings and the richness of the accompanying vegetation were evaluated in relation to the distance from the edge of the mature tree patches. Also, the cover, richness and diversity of all species in the invaded and non-invaded areas were measured, as well as soil pH, temperature and particle size. Negative correlations were found between the height of the saplings and distance to mature tree patches in all areas. The richness of the accompanying vegetation was negatively and positively correlated with the distance from the poplar and acacia area, respectively. The most abundant native species was Cortaderia selloana. Less cover, richness and diversity of native plant species and greater soil particle size were found in invaded areas, where the proportion of bare soil was higher. Also, a higher proportion of leaf litter in the invaded areas was registered. The results emphasize the invasive capacity of P. alba and A. longifolia advancing on the native communities and reducing their richness. Knowledge of the impact of invasive woody plants in coastal grasslands is important to design active management strategies for conservation purposes.

  12. 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  

  13. Regional population viability of grassland songbirds: Effects of agricultural management

    Science.gov (United States)

    Perlut, N.G.; Strong, A.M.; Donovan, T.M.; Buckley, N.J.

    2008-01-01

    Although population declines of grassland songbirds in North America and Europe are well-documented, the effect of local processes on regional population persistence is unclear. To assess population viability of grassland songbirds at a regional scale (???150,000 ha), we quantified Savannah Sparrow Passerculus sandwichensis and Bobolink Dolichonyx oryzivorus annual productivity, adult apparent survival, habitat selection, and density in the four most (regionally) common grassland treatments. We applied these data to a female-based, stochastic, pre-breeding population model to examine whether current grassland management practices can sustain viable populations of breeding songbirds. Additionally, we evaluated six conservation strategies to determine which would most effectively increase population trends. Given baseline conditions, over 10 years, simulations showed a slightly declining or stable Savannah Sparrow population (mean bootstrap ?? = 0.99; 95% CI = 1.00-0.989) and severely declining Bobolink population (mean bootstrap ?? = 0.75; 95% CI = 0.753-0.747). Savannah Sparrow populations were sensitive to increases in all demographic parameters, particularly adult survival. However for Bobolinks, increasing adult apparent survival, juvenile apparent survival, or preference by changing habitat selection cues for late-hayed fields (highest quality) only slightly decreased the rate of decline. For both species, increasing the amount of high-quality habitat (late- and middle-hayed) marginally slowed population declines; increasing the amount of low-quality habitat (early-hayed and grazed) marginally increased population declines. Both species were most sensitive to low productivity and survival on early-hayed fields, despite the fact that this habitat comprised only 18% of the landscape. Management plans for all agricultural regions should increase quality on both low- and high-quality fields by balancing habitat needs, nesting phenology, and species' response to

  14. Spatial heterogeneity increases diversity and stability in grassland bird communities.

    Science.gov (United States)

    Hovick, Torre J; Elmore, R Dwayne; Fuhlendorf, Samuel D; Engle, David M; Hamilton, Robert G

    2015-04-01

    Grasslands are inherently dynamic in space and time, evolving with frequent disturbance from fire and herbivores. As a consequence of human actions, many remaining grasslands have become homogenous, which has led to reduced ecosystem function, biodiversity loss, and decreased ecological services. Previous research has shown that restoring inherent heterogeneity to grasslands can increase avian diversity, but the amount of heterogeneity (i.e., number of patches or fire return interval) and the impact on avian community stability have yet to be investigated. We used a unique landscape-level design to examine avian response to interacting fire and grazing across multiple experimental landscapes that represented a gradient of fire- and grazing-dependent heterogeneity. We used seven landscapes (430-980 ha; x = 627 ha) with varying levels of patchiness ranging from annually burned (one single patch) with spring-only fires to a four-year fire return interval with spring and summer fires (eight patches). This design created a range of heterogeneity as a result of pyric herbivory, an ecological process in which fire and grazing are allowed to interact in space and time. We found that greater heterogeneity across experimental landscapes resulted in increased avian diversity and stability over time. An index of bird community change, quantified as the sum of the range of detrended correspondence analysis axis site scores, was nearly four times greater in the most homogenous experimental landscape when compared to the most heterogeneous experimental landscape. Species responses were consistently positively associated with increased heterogeneity at the landscape scale, and within-experimental-landscape responses were most often related to litter cover, litter accumulation, and vegetation height. We conclude that increased fire- and grazig-dependent heterogeneity can result in high variability in the bird community at finer, transect scales, but increased diversity and

  15. Assessment of Tibetan grassland degeneration via landscape analysis

    Science.gov (United States)

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

    2017-04-01

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

  16. 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.

  17. 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......-old grassland and a pea field as reference. Aboveground and root biomass were determined and soils were incubated to study CO2 emissions after soil disturbance. Aboveground biomass was highest in 1-year-old grassland with slurry application and lowest in 4-year-old grassland without slurry application. Root...... 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...

  18. 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.

  19. 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.

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

    Science.gov (United States)

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

    2017-05-01

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

  1. 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

  2. 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

  3. Effects of Vegetation Type and Management Practice on Soil Respiration of Grassland in Northern Japan

    OpenAIRE

    Minaco Adachi; Satoshi Tsuda

    2013-01-01

    Soil respiration rate in two types of grassland dominated with Zoysia japonica and Miscanthus sinensis, respectively, and under two management practices (undisturbed and intentionally burned) for the M. sinensis grassland was investigated for understanding the effects of grassland vegetation type and management practices on the relationship between soil temperature and soil respiration in northern Japan. Soil temperatures at depth of 1 cm in the Z. japonica (ZJ) and burned M. sinensis (MSb) p...

  4. 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

    2017-12-02

    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 (EVITGS ) 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 EVITGS , 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

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

    Science.gov (United States)

    Hill, Jason M; Diefenbach, Duane R

    2014-06-01

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

  6. Additionality in Conservation Easements Programs: Grassland Easements in the Prairie Pothole Region

    OpenAIRE

    Savage, Jeffrey; Claassen, Roger; Breneman, Vincent E.; Loesch, Chuck; Williams, Ryan

    2014-01-01

    Conversion of native sod (grassland) to cropland in the Prairie Pothole Region (PPR) is threatening important breeding habitats for migratory birds. About 50 percent of North American ducks are produced in the grasslands of the PPR, even though this habitat accounts for only ten percent of duck breeding territory. Once lost, native grassland habitats are difficult to reconstruct. To protect these habitats, the U.S. Fish and Wildlife Service (FWS) holds permanent easements prohibiting grasslan...

  7. California Immigrants Today

    OpenAIRE

    Cornelius, Wayne A.

    1990-01-01

    This paper will focus on the Mexico-origin component of the California immigrant population. Drawing on the results of field studies conducted throughout California and in west-central Mexico during the last ten years,the paper will describe how the profile of Mexican migration to California has changed since the 197Os, suggest explanations for these changes, and discuss their implications for public policy. Effects of the long-running economic crisis in Mexico and of the 1986 U.S. immigra-ti...

  8. NPP Grassland: NPP Estimates from Biomass Dynamics for 31 Sites, 1948-1994, R1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes monthly grassland biomass data, net primary productivity (NPP) estimates, and climate (rainfall amounts and temperature) data for multiple...

  9. DELAYED RESPONSES OF SMALL-MAMMAL ASSEMBLAGES SUBJECT TO AFFORESTATION-INDUCED GRASSLAND FRAGMENTATION

    National Research Council Canada - National Science Library

    R. Johnson; J. W H. Ferguson; A. S. van Jaarsveld; G. N. Bronner; C. T. Chimimba

    2002-01-01

    .... Despite extensive habitat disturbance through afforestation by 1998, assemblage structure and movement distances within the plantation were similar to those recorded in undisturbed grassland assemblages...

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

    Directory of Open Access Journals (Sweden)

    Yan Yan

    2015-06-01

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

  11. 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

  12. 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

  13. Effect of stocking rate and supplementation on performance of dairy cows grazing native grassland in small-scale systems in the highlands of central Mexico.

    Science.gov (United States)

    Sainz-Sánchez, Pedro Alan; López-González, Felipe; Estrada-Flores, Julieta Gertrudis; Martínez-García, Carlos Galdino; Arriaga-Jordán, Carlos Manuel

    2017-01-01

    The use and management of native grassland for dairy production during the rainy season was studied on two small-scale dairy farms in the highlands of central Mexico. Two stocking rates (2 and 4 cows/ha) and two levels of supplementation with commercial concentrate (4 and 6 kg/cow/day) under grazing were given to 12 milking Holstein cows in a 4 × 4 Latin square design replicated three times in a factorial arrangement. Net herbage accumulation (NHA), sward height, chemical composition, and in vitro digestibility of organic matter were recorded for the grassland, as well as vegetation cover and herbage mass 12 weeks post experiment. Animal performance variables were milk yield and composition, live weight, and body condition score. A partial budget analysis of feeding costs, returns, and margins was calculated. There were no differences between periods for NHA and herbage height and between plots for chemical composition (P > 0.05). However, there were highly significant differences among periods (P  0.05) between treatments for milk yield, chemical composition of milk, live weight, or body condition score. Post-experimental vegetation cover was 72 % for both stocking rates, indicating there was no degradation of the grassland. Lower feeding costs were for the low supplementation treatments. It is concluded that a high stocking rate in studied native grasslands of 4 cows/ha with moderate concentrate supplementation supports a mean milk yield of 11.9 kg/cow/day during the rainy season without deleterious effects on the grassland.

  14. 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...

  15. 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...

  16. California Data Exchange Center

    Science.gov (United States)

    ... to make July &28;Water Smart Month.&29; &28;Conserving ... Remote sensors today indicate that statewide, snowpack water content is 54 percent of ... California ranked first, along with Texas, on ...

  17. 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...

  18. 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...

  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. Earthquakes in Southern California

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — There have been many earthquake occurrences in Southern California. This set of slides shows earthquake damage from the following events: Imperial Valley, 1979,...

  1. California Watershed Hydrologic Units

    Data.gov (United States)

    California Department of Resources — 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...

  2. Dinitrogen emissions as an overlooked key component of the N balance of montane grasslands

    Science.gov (United States)

    Zistl-Schlingmann, Marcus; Feng, Jinchao; Kiese, Ralf; Stephan, Ruth; Dannenmann, Michael

    2017-04-01

    Numerous studies have been conducted on the emission dynamics and annual budget of the atmospheric pollutants and primary or secondary greenhouse gases NOx, NH3 and N2O, i.e. gaseous N losses which can play an important role in the N budget of ecosystems. Due to still existing methodical problems in their quantification, considerably less is known on soil dinitrogen (N2) emissions, an inert gas with no hazardous effects on the environment. Understanding of soil N2 emissions however may be important to better understand and manage the N balance of ecosystems and also to mitigate the emissions of the precursor and potent greenhouse gas N2O. Here we quantified soil N2 emissions from montane grasslands used for dairy farming as affected by climate change simulation (reduced annual precipitation, increased temperature). For this purpose, plant-soil-mesocosms were brought from field sites of different elevation to the laboratory for direct simultaneous quantification of soil N2 and N2O emissions by use of the Helium soil core method. Immediately after the measurements, the plant-soil mesocosms were reburied at the sites. Using this approach we found that under current climate conditions, soil N2 emissions exceeded soil N2O emissions by several orders of magnitude and increased from 25 kg N ha-1 year-1 (present climate) to 50 kg N ha-1 year-1 (climate change treatment). Because this approach based on monthly sampling cannot accurately consider N gas emission peaks after manure fertilization, measurements were supplemented by a laboratory incubation approach. In this experiment, the response of all N gas emissions (NH3, NO, N2O, N2) to manure fertilization (50 kg N ha-1) was monitored with subdaily temporal resolution until emissions had diminished. Total N gas losses amounted to roughly half of the supplied N by manure application. Surprisingly, we found that N2 but not NH3 dominated fertilizer-derived gaseous N losses, accounting for 78 to 85 % of total gaseous N losses

  3. Sustainable use of alpine and pre-alpine grassland soils in a changing climate (SUSALPS)

    Science.gov (United States)

    Zistl-Schlingmann, Marcus; Beck, Robert; Brandhuber, Robert; Butterbach-Bahl, Klaus; Garcia Franco, Noelia; von Gillhaußen, Phillip; Jentsch, Anke; Kiese, Ralf; Krämer, Alexander; Kögel-Knabner, Ingrid; Köllner, Thomas; Poppenborg, Patrick; Schloter, Michael; Schulz, Stefanie; Wiesmeier, Martin; Wolf, Benjamin; Dannenmann, Michael

    2016-04-01

    The development of ecologically as well as economically sustainable management options for the carbon- and nitrogen rich alpine and pre-alpine grassland soils in a changing climate poses a grand scientific and socio- economical challenge. The transdisciplinary SUSALPS project starting in 2016 aims to essentially improve the knowledge on the functionality of alpine and pre-alpine grassland soils using both natural-scientific/ technical and socio economical approaches. The project is building on existing infrastructure of German grassland-ecosystem-research like the pre-alpine TERENO (Terrestrial ecosystem observation network observatory) observatory sites, the EVENT and SIGNAL sites as well as long term LfL (Bayerische Landesanstalt für Landwirtschaft) sites, plus a new additional high elevation (1400m a.s.l) site in the Bavarian Alps. The site setup along the elevational gradient on the edge of the Alps (1400 m to 300 m) is used for space-for-time climate change experiments which are combined with extensive and intensive management treatments. A key focus of SUSALPS will be the characterization of combined climate change/management effects on carbon and nitrogen biogeochemistry. Hence, we will evaluate the influence of different management options and current and future climate changes on the soil microbiome and associated biogeochemical processes in the plant-soil-system, on nitrogen use efficiency, on biosphere-atmosphere exchange of greenhouse gases as well as on leaching of environmentally relevant compounds. For this purpose, we simulate the predicted climate change in the region by translocation of large lysimeters (1m2, 1.4m depth; TERENO lysimeters, translocated in 2011) for measurements of biosphere-atmosphere hydrosphere exchange of environmentally relevant C and N compounds as well as by newly transferred smaller plant-soil-mesocosms used for destructive biogeochemical process studies. By closely linking this experimental work with biogeochemical and

  4. 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

  5. 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.

  6. 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

  7. Local parasite lineage sharing in temperate grassland birds provides clues about potential origins of Galapagos avian Plasmodium.

    Science.gov (United States)

    Levin, Iris I; Colborn, Rachel E; Kim, Daniel; Perlut, Noah G; Renfrew, Rosalind B; Parker, Patricia G

    2016-02-01

    Oceanic archipelagos are vulnerable to natural introduction of parasites via migratory birds. Our aim was to characterize the geographic origins of two Plasmodium parasite lineages detected in the Galapagos Islands and in North American breeding bobolinks (Dolichonyx oryzivorus) that regularly stop in Galapagos during migration to their South American overwintering sites. We used samples from a grassland breeding bird assemblage in Nebraska, United States, and parasite DNA sequences from the Galapagos Islands, Ecuador, to compare to global data in a DNA sequence registry. Homologous DNA sequences from parasites detected in bobolinks and more sedentary birds (e.g., brown-headed cowbirds Molothrus ater, and other co-occurring bird species resident on the North American breeding grounds) were compared to those recovered in previous studies from global sites. One parasite lineage that matched between Galapagos birds and the migratory bobolink, Plasmodium lineage B, was the most common lineage detected in the global MalAvi database, matching 49 sequences from unique host/site combinations, 41 of which were of South American origin. We did not detect lineage B in brown-headed cowbirds. The other Galapagos-bobolink match, Plasmodium lineage C, was identical to two other sequences from birds sampled in California. We detected a close variant of lineage C in brown-headed cowbirds. Taken together, this pattern suggests that bobolinks became infected with lineage B on the South American end of their migratory range, and with lineage C on the North American breeding grounds. Overall, we detected more parasite lineages in bobolinks than in cowbirds. Galapagos Plasmodium had similar host breadth compared to the non-Galapagos haemosporidian lineages detected in bobolinks, brown-headed cowbirds, and other grassland species. This study highlights the utility of global haemosporidian data in the context of migratory bird-parasite connectivity. It is possible that migratory bobolinks

  8. Nitrate leaching under grassland as affected by mineral nitrogen fertilization and cattle urine.

    Science.gov (United States)

    Decau, M L; Simon, J C; Jacquet, A

    2004-01-01

    An experiment was performed to better understand to what extent nitrogen fertilization rate and date and amount of urine deposition, when acting in combination, influence nitrate leaching under grassland. Leaching was studied during two successive winters using 2-m2 grassed lysimeters under three levels of N fertilization (0, 150, and 300 kg N ha(-1) yr(-1), referred to as 0N, 150N, and 300N, respectively), two levels of 15N-labeled urine (105 and 165 kg N ha(-1), referred to as A2 and A3, respectively), and three dates of urine application (spring, summer, and fall). During the first winter, total N leaching losses varied between 2 and 50 kg N ha(-1). When tested in combination, N applied as urine to grassland resulted in three times the total N loss by leaching that occurred following N fertilization in the first winter (4.3, 20.8, 34.9, 14.2, 17.1, and 28.7 kg NO3- -N ha(-1) for no urine, A2, A3, ON, 150N, and 300N, respectively). Leaching of 15N urine significantly depended on the date of application: 6.6, 17.3, and 29.1 kg for spring, summer, and fall, respectively. A similar pattern was observed for the contribution of 15N urine to total N leaching with 4.3, 12.9, and 21.4%. However, urine application, both in terms of amount and date, showed very little long-term effect on these N losses in Year 2. In our conditions of low winter rainfall and drainage, grazing management (through season, urinary N amounts, and urine N concentration) resulted in a higher impact on water nitrate quality than moderate N fertilization management.

  9. Anthropogenic dust emissions due to livestock trampling in a Mongolian temperate grassland

    Science.gov (United States)

    Munkhtsetseg, Erdenebayar; Shinoda, Masato; Ishizuka, Masahide; Mikami, Masao; Kimura, Reiji; Nikolich, George

    2017-09-01

    Mongolian grasslands are a natural dust source region and they contribute to anthropogenic dust due to the long tradition of raising livestock there. Past decades of abrupt changes in a nomadic society necessitate a study on the effects of livestock trampling on dust emissions, so that research studies may help maintain a sustainable ecosystem and well-conditioned atmospheric environment. In this study, we conducted a mini wind tunnel experiment (using a PI-SWERL® device) to measure dust emissions fluxes from trampling (at three disturbance levels of livestock density, N) and zero trampling (natural as the background level) at test areas in a Mongolian temperate grassland. Moreover, we scaled anthropogenic dust emissions to natural dust emissions as a relative consequence of livestock trampling. We found a substantial increase in dust emissions due to livestock trampling. This effect of trampling on dust emissions was persistent throughout all wind friction velocities, u* (varying from 0.44 to 0.82 m s-1). Significantly higher dust loading occurs after a certain disturbance level has been reached by the livestock trampling. Our results suggest that both friction velocity (u*) and disturbance level of livestock density (N) have an enormous combinational effect on dust emissions from the trampling test surface. This means that the effect of livestock trampling on dust emissions can be seen or revealed when wind is strong. Our results also emphasize that better management for livestock allocation coupled with strategies to prevent anthropogenic dust loads are needed. However, there are many uncertainties and assumptions to be improved on in this study.

  10. Novel in vitro procedures for rearing a root-feeding pest (Heteronychus arator of grasslands

    Directory of Open Access Journals (Sweden)

    Ivan Hiltpold

    2016-08-01

    Full Text Available Optimising plant protection against insect herbivory relies on testing plant defence mechanisms and how the insect response to these defensive strategies. Such experiments benefit from using insects generated from standardised rearing protocols since this reduces stochastic variation. Such protocols can be challenging to devise, however, especially for root herbivores. These insects generally have complex and long life cycles, which are often only poorly described. Moreover, using field-captured root herbivores is often suboptimal because it involves extensive excavation from sites selected by chance (their location is not obvious and larval stages are frequently indistinguishable beyond the family level. We investigated in vitro procedures to improve the availability of the African Black Beetle (ABB Heteronychus arator, an invasive alien pest in both Australia and New Zealand. Native to Africa, this scarab beetle has established in Australian and New Zealand grasslands, pastures, and crops. Adults feed on the stem of young plants just beneath the soil surface. During the mating season, gravid females lay eggs in the soil, giving rise to larvae feeding on grass roots, causing severe damage, and impairing plant growth. Here, we propose laboratory approaches to collect eggs from field-captured adult beetles, to hatch eggs, and to rear neonate larvae to adults. We propose that these methods will provide plant scientists and entomologists with a better and more controlled supply of ABB larvae for laboratory and field assays. In turn, this will assist with the collection of important information for the management of this insect pest and enhanced protection of plants in crop and grassland ecosystems.

  11. Plant population differentiation and climate change: responses of grassland species along an elevational gradient.

    Science.gov (United States)

    Frei, Esther R; Ghazoul, Jaboury; Matter, Philippe; Heggli, Martin; Pluess, Andrea R

    2014-02-01

    Mountain ecosystems are particularly susceptible to climate change. Characterizing intraspecific variation of alpine plants along elevational gradients is crucial for estimating their vulnerability to predicted changes. Environmental conditions vary with elevation, which might influence plastic responses and affect selection pressures that lead to local adaptation. Thus, local adaptation and phenotypic plasticity among low and high elevation plant populations in response to climate, soil and other factors associated with elevational gradients might underlie different responses of these populations to climate warming. Using a transplant experiment along an elevational gradient, we investigated reproductive phenology, growth and reproduction of the nutrient-poor grassland species Ranunculus bulbosus, Trifolium montanum and Briza media. Seeds were collected from low and high elevation source populations across the Swiss Alps and grown in nine common gardens at three different elevations with two different soil depths. Despite genetic differentiation in some traits, the results revealed no indication of local adaptation to the elevation of population origin. Reproductive phenology was advanced at lower elevation in low and high elevation populations of all three species. Growth and reproduction of T. montanum and B. media were hardly affected by garden elevation and soil depth. In R. bulbosus, however, growth decreased and reproductive investment increased at higher elevation. Furthermore, soil depth influenced growth and reproduction of low elevation R. bulbosus populations. We found no evidence for local adaptation to elevation of origin and hardly any differences in the responses of low and high elevation populations. However, the consistent advanced reproductive phenology observed in all three species shows that they have the potential to plastically respond to environmental variation. We conclude that populations might not be forced to migrate to higher elevations

  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. Anthropogenic dust emissions due to livestock trampling in a Mongolian temperate grassland

    Directory of Open Access Journals (Sweden)

    E. Munkhtsetseg

    2017-09-01

    Full Text Available Mongolian grasslands are a natural dust source region and they contribute to anthropogenic dust due to the long tradition of raising livestock there. Past decades of abrupt changes in a nomadic society necessitate a study on the effects of livestock trampling on dust emissions, so that research studies may help maintain a sustainable ecosystem and well-conditioned atmospheric environment. In this study, we conducted a mini wind tunnel experiment (using a PI-SWERL® device to measure dust emissions fluxes from trampling (at three disturbance levels of livestock density, N and zero trampling (natural as the background level at test areas in a Mongolian temperate grassland. Moreover, we scaled anthropogenic dust emissions to natural dust emissions as a relative consequence of livestock trampling. We found a substantial increase in dust emissions due to livestock trampling. This effect of trampling on dust emissions was persistent throughout all wind friction velocities, u* (varying from 0.44 to 0.82 m s−1. Significantly higher dust loading occurs after a certain disturbance level has been reached by the livestock trampling. Our results suggest that both friction velocity (u* and disturbance level of livestock density (N have an enormous combinational effect on dust emissions from the trampling test surface. This means that the effect of livestock trampling on dust emissions can be seen or revealed when wind is strong. Our results also emphasize that better management for livestock allocation coupled with strategies to prevent anthropogenic dust loads are needed. However, there are many uncertainties and assumptions to be improved on in this study.

  14. GHG Fluxes in semi-natural grasslands in the Pyrenees

    Science.gov (United States)

    Debouk, Haifa; Altimir, Nuria; Ribas, Angela; Ibañez, Mercedes; Sebastià, Teresa

    2015-04-01

    Mountain areas are identified by the IPCC report (2013) as particularly sensitive to climate change. The need to understand mountain grasslands is crucial since these ecosystems can act as both sinks and sources of CO2. Investigating CH4 and N2O fluxes is important because they can offset potential CO2 sequestration. While most studies have been focusing on CO2, the knowledge on the temporal and spatial variability of CH4 and N2O, particularly in semi-natural mountain grasslands, is scarce. This study describes the magnitude and range of variability of the fluxes of CO2, N2O, and CH4 from four semi-natural pastures in the Pyrenees across an altitudinal gradient (1026 to 2436 m a.s.l.) during the growth period in 2012 and 2013. We measured GHG fluxes of the grassland during both light and dark conditions in the study sites using a photoacoustic field gas-monitor (INNOVA 1412, LumaSense Technologies). After completing the GHG measurements, we collected vegetation samples for the estimation of above-ground and below-ground biomass and separated them into functional groups and species. We present here the analysis of the relationship between GHG fluxes and above-ground biomass including the contribution of the relative abundance of plant functional types. Our preliminary results showed a clear seasonal pattern of GHG fluxes. We observed a negative impact of the summer period on the GHG fluxes, which was mostly pronounced in the CO2. We will further elaborate in-depth the effect of the temporal and spatial variability on the fluxes of CO2, N2O and CH4. Also, we will present the relationship between the GHG fluxes and the contribution of the vegetation in terms of the relative abundance of different plant functional types.

  15. Greenhouse gas fluxes in mountain grassland differing in land use

    Science.gov (United States)

    Ladreiter-Knauss, Thomas; Schmitt, Michael; Butterbach-Bahl, Klaus; Kienzl, Sandra; Ingrisch, Johannes; Hasibeder, Roland; Bahn, Michael

    2013-04-01

    Mountain grassland covers large areas, thus influences the global greenhouse gas (GHG) balance and is strongly affected by changes in land use. Effects of such changes on the GHG-balance have so far not been well documented. As a contribution to the EU-project GHG Europe we are studying the net ecosystem exchange (NEE) of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) on a mountain meadow, an adjacent and an abandoned pasture at 1820-1970m a.s.l. in the Austrian Central Alps. The GHG balance is estimated from manual and auto-chamber measurements, combined with already published CO2-NEE over almost a decade. Winter CO2-fluxes, primarily soil respiration underneath the snowpack, are estimated with solid state CO2-sensors using a validated diffusion model. We found that abandon the management decreases the NEE of CO2 while its component, soil respiration (Rs), increases. The decrease is explained by differences in leaf area index, biomass and leaf-area-independent changes that were likely related to photosynthetic physiology. The increase in Rs can be explained by higher belowground carbon input due to missing grazing or mowing. The abandoned pasture showed the highest uptake rates of CH4 and a slight uptake of N2O, possibly due to better soil aeration. Spring freeze-thaw events caused slight CH4 emissions in the managed grassland. The meadow and pasture had just low emission rates of N2O even at freeze-thaw cycles and organic fertilization. These results suggest that in mountain grassland the main contributor to the GHG balance are CO2 fluxes that can largely be influenced by land use changes.

  16. Selected indicators of effective fertilization of meadow grasslands

    Directory of Open Access Journals (Sweden)

    Ivan Holúbek

    2015-03-01

    Full Text Available The issues of nutrition and fertilization of meadow phytocenosis with the emphasis on the production effectiveness and economic effectiveness were observed at the low, medium and high intensity of fertilization using artificial fertilizers. The obtained results are based on the research of valley meadows (series A, mountainous meadows (series B and semi-natural and additionally sown and ploughed mountainous meadows (series C. In series A, in the observed period, the production effectiveness reached 14.93–23.76 kg of hay and the economic effectiveness reached 1.07–1.43 €. The higher production effectiveness and economic effectiveness are produced by doses of nutrients in the ratio N : P : K – 1 : 0.35 : 0.5. The highest production effectiveness and economic effectiveness were determined in variants fertilized by lower doses of artificial fertilizers (variants 7 and 12. The influence of PK and NPK nutrients on the production effectiveness and economic effectiveness of fertilization of different grasslands in different altitudes was observed in series B: the higher the altitude (from 350 to 850 meters above the sea level, the lower the indicators of production and economic effectiveness of artificial fertilizers. In series C, the loss of phosphoric and potassic nutrition is represented by higher inputs than outputs. Semi-natural grasslands and ploughed grasslands fertilized by medium and high intensity of NPK fertilizers (var.3–90 N kg*ha-1 + PK a var.4–180 N kg*ha-1 + PK are economically effective.

  17. Aridity modulates N availability in arid and semiarid Mediterranean grasslands.

    Science.gov (United States)

    Delgado-Baquerizo, Manuel; Maestre, Fernando T; Gallardo, Antonio; Quero, José L; Ochoa, Victoria; García-Gómez, Miguel; Escolar, Cristina; García-Palacios, Pablo; Berdugo, Miguel; Valencia, Enrique; Gozalo, Beatriz; Noumi, Zouhaier; Derak, Mchich; Wallenstein, Matthew D

    2013-01-01

    While much is known about the factors that control each component of the terrestrial nitrogen (N) cycle, it is less clear how these factors affect total N availability, the sum of organic and inorganic forms potentially available to microorganisms and plants. This is particularly true for N-poor ecosystems such as drylands, which are highly sensitive to climate change and desertification processes that can lead to the loss of soil nutrients such as N. We evaluated how different climatic, abiotic, plant and nutrient related factors correlate with N availability in semiarid Stipa tenacissima grasslands along a broad aridity gradient from Spain to Tunisia. Aridity had the strongest relationship with N availability, suggesting the importance of abiotic controls on the N cycle in drylands. Aridity appeared to modulate the effects of pH, plant cover and organic C (OC) on N availability. Our results suggest that N transformation rates, which are largely driven by variations in soil moisture, are not the direct drivers of N availability in the studied grasslands. Rather, the strong relationship between aridity and N availability could be driven by indirect effects that operate over long time scales (decades to millennia), including both biotic (e.g. plant cover) and abiotic (e.g. soil OC and pH). If these factors are in fact more important than short-term effects of precipitation on N transformation rates, then we might expect to observe a lagged decrease in N availability in response to increasing aridity. Nevertheless, our results suggest that the increase in aridity predicted with ongoing climate change will reduce N availability in the Mediterranean basin, impacting plant nutrient uptake and net primary production in semiarid grasslands throughout this region.

  18. Aridity modulates N availability in arid and semiarid Mediterranean grasslands.

    Directory of Open Access Journals (Sweden)

    Manuel Delgado-Baquerizo

    Full Text Available While much is known about the factors that control each component of the terrestrial nitrogen (N cycle, it is less clear how these factors affect total N availability, the sum of organic and inorganic forms potentially available to microorganisms and plants. This is particularly true for N-poor ecosystems such as drylands, which are highly sensitive to climate change and desertification processes that can lead to the loss of soil nutrients such as N. We evaluated how different climatic, abiotic, plant and nutrient related factors correlate with N availability in semiarid Stipa tenacissima grasslands along a broad aridity gradient from Spain to Tunisia. Aridity had the strongest relationship with N availability, suggesting the importance of abiotic controls on the N cycle in drylands. Aridity appeared to modulate the effects of pH, plant cover and organic C (OC on N availability. Our results suggest that N transformation rates, which are largely driven by variations in soil moisture, are not the direct drivers of N availability in the studied grasslands. Rather, the strong relationship between aridity and N availability could be driven by indirect effects that operate over long time scales (decades to millennia, including both biotic (e.g. plant cover and abiotic (e.g. soil OC and pH. If these factors are in fact more important than short-term effects of precipitation on N transformation rates, then we might expect to observe a lagged decrease in N availability in response to increasing aridity. Nevertheless, our results suggest that the increase in aridity predicted with ongoing climate change will reduce N availability in the Mediterranean basin, impacting plant nutrient uptake and net primary production in semiarid grasslands throughout this region.

  19. 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

  20. Impacts of 120 years of fertilizer addition on a temperate grassland ecosystem.

    Science.gov (United States)

    Kidd, Jonathan; Manning, Peter; Simkin, Janet; Peacock, Simon; Stockdale, Elizabeth

    2017-01-01

    The widespread application of fertilizers has greatly influenced many processes and properties of agroecosystems, and agricultural fertilization is expected to increase even further in the future. To date, most research on fertilizer impacts has used short-term studies, which may be unrepresentative of long-term responses, thus hindering our capacity to predict long-term impacts. Here, we examined the effects of long-term fertilizer addition on key ecosystem properties in a long-term grassland experiment (Palace Leas Hay Meadow) in which farmyard manure (FYM) and inorganic fertilizer treatments have been applied consistently for 120 years in order to characterize the experimental site more fully and compare ecosystem responses with those observed at other long-term and short-term experiments. FYM inputs increased soil organic carbon (SOC) stocks, hay yield, nutrient availability and acted as a buffer against soil acidification (>pH 5). In contrast, N-containing inorganic fertilizers strongly acidified the soil (Grassland experiments) in that fertilization effects on plant and soil properties appeared to be driven by differences in both nutrient input and changes to soil pH. We also established that the direction of long-term fertilization effects tended to be comparable with short-term experiments, but that their magnitude differed considerably, particularly where ammonium sulphate-induced acidification had occurred. We therefore conclude that short-term studies are unlikely to possess the required timeframe to accurately predict long-term responses, thus necessitating the use of long-term study sites. Such

  1. Estimating the short-term nutritive value of grassland along a ...

    African Journals Online (AJOL)

    UFS

    measurements. Crude protein (CP) content was calculated from measured nitrogen content (Kjeldahl method) of the leaves, stems and seed. Although the monthly CP concentration (g/kg) of grassland in poor condition was generally higher than that of grassland in good condition, CP production decreased significantly with ...

  2. Diversity of soil macro-invertebrates in grasslands under restoration succession

    NARCIS (Netherlands)

    Hemerik, L.; Brussaard, L.

    2002-01-01

    In grasslands under restoration succession, the effect of nutrient impoverishment on the vegetation has been intensively studied. The invertebrate soil animal community has, however, rarely been studied under such conditions. We hypothesised that a plant community in nutrient-poor grasslands

  3. 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

  4. Chihuahuan Desert grassland responds similarly to fall, spring, and summer fires during prolonged drought

    Science.gov (United States)

    Laura M. Ladwig; Scott L. Collins; Paulette L. Ford; Laura B. White

    2014-01-01

    Land managers frequently use prescribed burning to help maintain grassland communities. Semiarid grassland dynamics following fire are linked to precipitation, with increasing soil moisture accelerating the rate of recovery. Prescribed fires are typically scheduled to follow natural fire regimes, but burning outside the natural fire season could be equally effective...

  5. Improving nitrogen management on grassland on commercial pilot dairy farms in the Netherlands

    NARCIS (Netherlands)

    Oenema, J.; Ittersum, van M.K.; Keulen, van H.

    2012-01-01

    Nitrogen (N) use efficiency (NUE), the ratio of N output and N input, is rather low on dairy farms with high stocking densities and high N input on grassland resulting in high N losses to the environment. This study describes and analyses the development and variation in N management on grassland on

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

    Science.gov (United States)

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

    2008-01-01

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

  7. 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...

  8. 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...

  9. Does the aboveground herbivore assemblage influence soil bacterial community composition and richness in subalpine grasslands?

    Science.gov (United States)

    Melanie Hodel; Martin Schütz; Martijn L. Vandegehuchte; Beat Frey; Matthias Albrecht; Matt D. Busse; Anita C. Risch

    2014-01-01

    Grassland ecosystems support large communities of aboveground herbivores that can alter ecosystem processes. Thus, grazing by herbivores can directly and indirectly affect belowground properties such as the microbial community structure and diversity. Even though multiple species of functionally different herbivores coexist in grassland ecosystems, most studies have...

  10. Impact of different-sized herbivores on recruiment opportunities for subordinate herbs in grasslands

    NARCIS (Netherlands)

    Bakker, E.S.; Olff, H.

    2003-01-01

    Potential effects of herbivores on plant species diversity depend on herbivore size, species and density. In this study we examine the effect of different-sized herbivores (cattle and rabbits) on recruitment of subordinate herbs in grasslands. We show that in a grazed floodplain, grassland plant

  11. Impact of different-sized herbivores on recruitment opportunities for subordinate herbs in grasslands

    NARCIS (Netherlands)

    Bakker, Elisabeth S.; Olff, Han

    2003-01-01

    Potential effects of herbivores on plant species diversity depend on herbivore size, species and density. In this study we examine the effect of different-sized herbivores (cattle and rabbits) on recruitment of subordinate herbs in grasslands. We show that in a grazed floodplain, grassland plant

  12. Effects of soil moisture content and temperature on methane uptake by grasslands on sandy soils.

    NARCIS (Netherlands)

    Pol-Van Dasselaar, van den A.; Beusichem, van M.L.; Oenema, O.

    1998-01-01

    Aerobic grasslands may consume significant amounts of atmospheric methane (CH4). We aimed (i) to assess the spatial and temporal variability of net CH4 fluxes from grasslands on aerobic sandy soils, and (ii) to explain the variability in net CH4 fluxes by differences in soil moisture content and

  13. 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

  14. Uncertainty and risk analysis of nutrient management; a model survey for nitrogen fertilization of grassland

    NARCIS (Netherlands)

    Wierda, C.; Oenema, O.

    1996-01-01

    Variations and uncertainties in nitrogen (N) flows in grassland were quantified by using a simple model. The newly developed N risk model calculates dry matter (DM) production and N losses as a function of weather and soil conditions, and grassland m

  15. Estimating plant traits of grasslands from UAV-acquired hyperspectral images

    NARCIS (Netherlands)

    Capolupo, Alessandra; Kooistra, Lammert; Berendonk, Clara; Boccia, Lorenzo; Suomalainen, Juha

    2015-01-01

    Grassland ecosystems cover around 40% of the entire Earth's surface. Therefore, it is necessary to guarantee good grassland management at field scale in order to improve its conservation and to achieve optimal growth. This study identified the most appropriate statistical strategy, between

  16. 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...

  17. Scale-dependent diversity effects of seed dispersal by a wild herbivore in fragmented grasslands.

    Science.gov (United States)

    Auffret, Alistair G; Plue, Jan

    2014-05-01

    Dispersal limitation between habitat fragments is a known driver of landscape-scale biodiversity loss. In Europe, agricultural intensification during the twentieth century resulted in losses of both grassland habitat and traditional grassland seed dispersal vectors such as livestock. During the same period, populations of large wild herbivores have increased in the landscape. Usually studied in woodland ecosystems, these animals are found to disperse seeds from grasslands and other open habitats. We studied endozoochorous seed dispersal by roe deer (Capreolus capreolus) in fragmented grasslands and grassland remnants, comparing dispersed subcommunities of plant species to those in the established vegetation and the seed bank. A total of 652 seedlings of 67 species emerged from 219 samples of roe deer dung. This included many grassland species, and several local grassland specialists. Dispersal had potentially different effects on diversity at different spatial scales. Almost all sites received seeds of species not observed in the vegetation or seed bank at that site, suggesting that local diversity might not be dispersal limited. This pattern was less evident at the landscape scale, where fewer new species were introduced. Nonetheless, long-distance dispersal by large wild herbivores might still provide connectivity between fragmented habitats within a landscape in the areas in which they are active. Finally, as only a subset of the available species were found to disperse in space as well as time, the danger of future biodiversity loss might still exist in many isolated grassland habitats.

  18. 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

  19. 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

  20. 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

  1. Factors affecting digestibility of temperate forages from seminatural grasslands : a review

    NARCIS (Netherlands)

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

    2002-01-01

    To indicate possibilities for the use of forages from seminatural grasslands in ruminant production systems, a literature study to describe the nutritive value of those forages was carried out. In species-rich grasslands, the digestibility of forages is usually lower than the digestibility of

  2. The Distribution and Abundance of Obligate Grassland Birds Breeding in New England and New York

    Science.gov (United States)

    W. Gregory Shriver; Andrea L. Jones; Peter D. Vickery; Andrew Weik; Jeffrey Wells

    2005-01-01

    It is clear that grassland bird populations have declined significantly during the last 30 years. Declines are widespread in North America, making grassland birds a continental conservation priority. In New England and New York steep population declines for many species warranted listing in many states. Habitat loss through farm abandonment and the subsequent...

  3. Thirty years of weather change and effects on a grassland in the Peloncillo Mountains, New Mexico

    Science.gov (United States)

    William H. Moir

    2011-01-01

    In this paper I describe and compare grassland changes since 1977 at the Central Peloncillo Research Natural Area (CPRNA) with temperature and precipitation data from its nearby weather station. The grama grasslands there have thrived through two distinctive climate periods since 1977. The current period began with warm and dry years beginning around 1993 and...

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

    Science.gov (United States)

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

    2005-01-01

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

  5. Guide to the literature on research in the grassland biome of South Africa

    CSIR Research Space (South Africa)

    Tainton, MN

    1984-12-01

    Full Text Available Research into the management of grassland communities in South Africa spans a period of more than 50 years. The work has covered a wide range of topics relating to the form and function of grassland communities, and has had as its main objective...

  6. Production of natural grassland in the central Orange Free State in ...

    African Journals Online (AJOL)

    In order to plan a livestock enterprise it is imperative to know the production potential of the natural grassland. Grassland production is determined mainly by climate and soil, provided reasonably sound management practices are employed. It is thus evident that effective planning must necessarily depend heavily on a ...

  7. Space-based long-term observation of shrinking grassland habitat ...

    Indian Academy of Sciences (India)

    Grassland ecosystem is critical for survival of herbivores and plays an important role in conservation and management of wildlife. These habitats are widely studied for various issues, including biodiversity, biomass assessment, carrying capacity, etc. Woody species ingression in grasslands is one such important aspect that ...

  8. AFLP fingerprinting of Kentucky bluegrass (Poa pratensis L.) from undisturbed Dutch grasslands: implications for conservation

    NARCIS (Netherlands)

    Treuren, van R.

    2008-01-01

    Undisturbed grasslands are considered rich sources of promising genotypes for the development of new varieties of Kentucky bluegrass (Poa pratensis L.). Grasslands that have not been resown with commercial cultivars nor treated with high doses of nitrogen fertilizer have become rare in the

  9. 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...

  10. Effect of rainfall-induced soil geochemistry dynamics on grassland soil microbial communities.

    Science.gov (United States)

    Cruz-Martínez, Karelyn; Rosling, Anna; Zhang, Yang; Song, Mingzhou; Andersen, Gary L; Banfield, Jillian F

    2012-11-01

    In Mediterranean-type grassland ecosystems, the timing of rainfall events controls biogeochemical cycles, as well as the phenology and productivity of plants and animals. Here, we investigate the effect of short-term (days) soil environmental conditions on microbial community structure and composition during a natural wetting and drying cycle. Soil samples were collected from a meadow in Northern California at four time points after the first two rainfall events of the rainy season. We used 16S rRNA microarrays (PhyloChip) to track changes in bacterial and archaeal community composition. Microbial communities at time points 1 and 3 were significantly different than communities at time points 2 and 4. Based on ordination analysis, the available carbon, soil moisture, and temperature explained most of the variation in community structure. For the first time, a complementary and more comprehensive approach using linear regression and generalized logical networks were used to identify linear and nonlinear associations among environmental variables and with the relative abundance of subfamilies. Changes in soil moisture and available carbon were correlated with the relative abundance of many phyla. Only the phylum Actinobacteria showed a lineage-specific relationship to soil moisture but not to carbon or nitrogen. The results indicate that the use of a high taxonomic rank in correlations with nutritional indicators might obscure divergent subfamily-level responses to environmental parameters. An important implication of this research is that there is short-term variation in microbial community composition driven in part by rainfall fluctuation that may not be evident in long-term studies with coarser time resolution.

  11. Introduced predators transform subarctic islands from grassland to tundra

    Science.gov (United States)

    Croll, D.A.; Maron, J.L.; Estes, J.A.; Danner, E.M.; Byrd, G.V.

    2005-01-01

    Top predators often have powerful direct effects on prey populations, but whether these direct effects propagate to the base of terrestrial food webs is debated. There are few examples of trophic cascades strong enough to alter the abundance and composition of entire plant communities. We show that the introduction of arctic foxes (Alopex lagopus) to the Aleutian archipelago induced strong shifts in plant productivity and community structure via a previously unknown pathway. By preying on seabirds, foxes reduced nutrient transport from ocean to land, affecting soil fertility and transforming grasslands to dwarf shrub/forb-dominated ecosystems.

  12. Effects of grassland degradation and precipitation on carbon storage distributions in a semi-arid temperate grassland of Inner Mongolia, China

    Science.gov (United States)

    Li, Xiaobing; Bai, Yunxiao; Wen, Wanyu; Wang, Hong; Li, Ruihua; Li, Guoqing; Wang, Han

    2017-11-01

    Environmental degradation influences carbon (C) cycling and storage in grassland ecosystems by altering vegetation productivity. However, the impacts of different degradation intensities on vegetation-soil C distributions in grasslands have not been well documented. We measured C storage in soil, roots, and plants under light, moderate, and severe degradation levels in a typical steppe region of Xilinhot, Inner Mongolia, China in 2011 and 2012. Grassland C storage was highest in soil, followed by roots, and then aboveground plant biomass. Grassland degradation and precipitation significantly influenced C storage distributions. During the dry year (2011), total C storage in vegetation and soil was highest under light degradation. Carbon storage in aboveground plant biomass and roots increased with degradation intensity. During the wet year (2012), C storage was highest in aboveground plant biomass and roots under light degradation. Root biomass tended to be concentrated in the soil surface during the wet year.

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Maite Gartzia

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

  15. 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...

  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. 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...

  18. Effects of Climate Change and Various Grassland Management Practices on Grasshopper (Orthoptera Assemblages

    Directory of Open Access Journals (Sweden)

    Zoltán Kenyeres

    2014-01-01

    Full Text Available Influence of different grassland management practices on Orthoptera assemblages inhabiting humid grassland areas was studied since 2003 to 2011. The examined sites were within the protected area of Balaton Uplands National Park. The physiognomy and climatic conditions of the studied habitats were similar but their land use types were significantly different. After the preliminary analyses of Nonmetric multidimensional scaling, neighbour joining clustering, and Spearman rank correlation, we examined the possible effects of such independent variables as land use (nonmanagement, mowing, grazing, microclimate (humidity and temperature, regional macroclimate (annual and monthly mean temperatures and rainfall, using General Linear Mixed Models, and canonical correlation analysis. Our results showed that the effect of grassland management practices on the organization of Orthoptera assemblages was at least as important as that of macro- and microclimate. Furthermore, grassland management could intensify the influence of several local and regional parameters. These results can help finding the most suitable type of grassland management to conserve the grasshopper assemblages.

  19. Impacts of Soil Warming and Plant Rhizosphere on Root Litter Decomposition at Different Soil Depths in a Mediterranuan Grassland Lysimeter Facility

    Science.gov (United States)

    Zhu, B.; Hicks Pries, C.; Castanha, C.; Curtis, J. B.; Porras, R. C.; Torn, M. S.

    2014-12-01

    Accurate understanding of soil carbon cycling is critical for predicting climate-ecosystem feedbacks. Decomposition of root litter and its transformation into soil organic matter (SOM) are critical processes of soil carbon cycling. We aim to study the impacts of soil warming and plant rhizosphere on the fate of 13C-labeled roots buried at two soil depths using a field lysimeter facility at Hopland, California. The lysimeters contain soil columns of 38-cm diameter and 48-cm depth (0-15 cm A-horizon, and 15-48 cm B-horizon, Laughlin soil series) sown with annual grasses dominated by Avena barbata. The experiment has three treatments (planted-ambient, planted-warming (+4°C), and unplanted-ambient). In February 2014, 13C-labeled A. fatua roots were added to two depths (8-12 and 38-42 cm). We measured root-derived 13C in respired CO2 collected at the soil surface and in leachate dissolved organic carbon (DOC) collected from the lysimeters during the growing season and in soil harvested in August 2014. We found (1) soil temperature at two depths (10- and 40-cm) have been elevated by 4±0.2°C in the warmed compared to the ambient lysimeters; (2) surface (10-cm) volumetric soil moisture followed this order (unplanted-ambient > planted-ambient > planted-warming), while subsurface (40-cm) soil moisture showed little variation among treatments; (3) ecosystem respiration was enhanced by soil warming during the early growing season (March 15th and April 5th) when soil moisture was not limiting (>20%), while it was suppressed by soil warming during the late growing season (May 7th) when soil moisture was limiting (plant biomass increased 25% with soil warming. More data including 13C values of ecosystem respiration, DOC loss, and harvested soil samples, as well as soil nutrient supply rates, microbial biomass and community structure will be presented during the meeting. Overall, these results suggest that the impact of soil warming and plant rhizosphere on ecosystem carbon

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

    Science.gov (United States)

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

    2017-04-01

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

  1. Archaeal ammonia oxidizers dominate in numbers, but bacteria drive gross nitrification in N-amended grassland soil

    Directory of Open Access Journals (Sweden)

    Anna E Sterngren

    2015-11-01

    Full Text Available Both ammonia-oxidizing archaea (AOA and ammonia-oxidizing bacteria (AOB play an important role in nitrification in terrestrial environments. Most often AOA outnumber AOB, but the relative contribution of AOA and AOB to nitrification rates remains unclear. The aim of this experiment was to test the hypotheses that high nitrogen availability would favor AOB and result in high gross nitrification rates, while high carbon availability would result in low nitrogen concentrations that favor the activity of AOA. The hypotheses were tested in a microcosm experiment where sugars, ammonium or amino acids were added regularly to a grassland soil for a period of 33 days. The abundance of amoA genes from AOB increased markedly in treatments that received nitrogen, suggesting that AOB were the main ammonia oxidizers here. However, AOB could not account for the entire ammonia oxidation activity observed in treatments where the soil was deficient in available nitrogen. The findings suggest that AOA are important drivers of nitrification under nitrogen-poor conditions, but that input of easily available nitrogen results in increased abundance, activity, and relative importance of AOB for gross nitrification in grassland soil.

  2. Archaeal Ammonia Oxidizers Dominate in Numbers, but Bacteria Drive Gross Nitrification in N-amended Grassland Soil

    Science.gov (United States)

    Sterngren, Anna E.; Hallin, Sara; Bengtson, Per

    2015-01-01

    Both ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) play an important role in nitrification in terrestrial environments. Most often AOA outnumber AOB, but the relative contribution of AOA and AOB to nitrification rates remains unclear. The aim of this experiment was to test the hypotheses that high nitrogen availability would favor AOB and result in high gross nitrification rates, while high carbon availability would result in low nitrogen concentrations that favor the activity of AOA. The hypotheses were tested in a microcosm experiment where sugars, ammonium, or amino acids were added regularly to a grassland soil for a period of 33 days. The abundance of amoA genes from AOB increased markedly in treatments that received nitrogen, suggesting that AOB were the main ammonia oxidizers here. However, AOB could not account for the entire ammonia oxidation activity observed in treatments where the soil was deficient in available nitrogen. The findings suggest that AOA are important drivers of nitrification under nitrogen-poor conditions, but that input of easily available nitrogen results in increased abundance, activity, and relative importance of AOB for gross nitrification in grassland soil. PMID:26648926

  3. 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…

  4. 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

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

    OpenAIRE

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

    2017-01-01

    Abstract 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 managemen...

  6. Ecoregion sections of California deserts

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The dataset delineates ecological sections within California deserts. These deserts occupy the southeastern portion of California and include two ecoregional...

  7. 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

  8. 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.

  9. Effect of soil coarseness on soil base cations and available micronutrients in a semi-arid sandy grassland

    Science.gov (United States)

    Lü, Linyou; Wang, Ruzhen; Liu, Heyong; Yin, Jinfei; Xiao, Jiangtao; Wang, Zhengwen; Zhao, Yan; Yu, Guoqing; Han, Xingguo; Jiang, Yong

    2016-04-01

    Soil coarseness is the main process decreasing soil organic matter and threatening the productivity of sandy grasslands. Previous studies demonstrated negative effect of soil coarseness on soil carbon storage, but less is known about how soil base cations (exchangeable Ca, Mg, K, and Na) and available micronutrients (available Fe, Mn, Cu, and Zn) response to soil coarseness. In a semi-arid grassland of Northern China, a field experiment was initiated in 2011 to mimic the effect of soil coarseness on soil base cations and available micronutrients by mixing soil with different mass proportions of sand: 0 % coarse elements (C0), 10 % (C10), 30 % (C30), 50 % (C50), and 70 % (C70). Soil coarseness significantly increased soil pH in three soil depths of 0-10, 10-20 and 20-40 cm with the highest pH values detected in C50 and C70 treatments. Soil fine particles (smaller than 0.25 mm) significantly decreased with the degree of soil coarseness. Exchangeable Ca and Mg concentrations significantly decreased with soil coarseness degree by up to 29.8 % (in C70) and 47.5 % (in C70), respectively, across three soil depths. Soil available Fe, Mn, and Cu significantly decreased with soil coarseness degree by 62.5, 45.4, and 44.4 %, respectively. As affected by soil coarseness, the increase of soil pH, decrease of soil fine particles (including clay), and decline in soil organic matter were the main driving factors for the decrease of exchangeable base cations (except K) and available micronutrients (except Zn) through soil profile. Developed under soil coarseness, the loss and redistribution of base cations and available micronutrients along soil depths might pose a threat to ecosystem productivity of this sandy grassland.

  10. From facilitation to competition: temperature-driven shift in dominant plant interactions affects population dynamics in seminatural grasslands.

    Science.gov (United States)

    Olsen, Siri L; Töpper, Joachim P; Skarpaas, Olav; Vandvik, Vigdis; Klanderud, Kari

    2016-05-01

    Biotic interactions are often ignored in assessments of climate change impacts. However, climate-related changes in species interactions, often mediated through increased dominance of certain species or functional groups, may have important implications for how species respond to climate warming and altered precipitation patterns. We examined how a dominant plant functional group affected the population dynamics of four co-occurring forb species by experimentally removing graminoids in seminatural grasslands. Specifically, we explored how the interaction between dominants and subordinates varied with climate by replicating the removal experiment across a climate grid consisting of 12 field sites spanning broad-scale temperature and precipitation gradients in southern Norway. Biotic interactions affected population growth rates of all study species, and the net outcome of interactions between dominants and subordinates switched from facilitation to competition with increasing temperature along the temperature gradient. The impacts of competitive interactions on subordinates in the warmer sites could primarily be attributed to reduced plant survival. Whereas the response to dominant removal varied with temperature, there was no overall effect of precipitation on the balance between competition and facilitation. Our findings suggest that global warming may increase the relative importance of competitive interactions in seminatural grasslands across a wide range of precipitation levels, thereby favouring highly competitive dominant species over subordinate species. As a result, seminatural grasslands may become increasingly dependent on disturbance (i.e. traditional management such as grazing and mowing) to maintain viable populations of subordinate species and thereby biodiversity under future climates. Our study highlights the importance of population-level studies replicated under different climatic conditions for understanding the underlying mechanisms of climate

  11. 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.

  12. Not all droughts are created equal: the impacts of interannual drought pattern and magnitude on grassland carbon cycling.

    Science.gov (United States)

    Hoover, David L; Rogers, Brendan M

    2016-05-01

    Climate extremes, such as drought, may have immediate and potentially prolonged effects on carbon cycling. Grasslands store approximately one-third of all terrestrial carbon and may become carbon sources during droughts. However, the magnitude and duration of drought-induced disruptions to the carbon cycle, as well as the mechanisms responsible, remain poorly understood. Over the next century, global climate models predict an increase in two types of drought: chronic but subtle 'press-droughts', and shorter term but extreme 'pulse-droughts'. Much of our current understanding of the ecological impacts of drought comes from experimental rainfall manipulations. These studies have been highly valuable, but are often short term and rarely quantify carbon feedbacks. To address this knowledge gap, we used the Community Land Model 4.0 to examine the individual and interactive effects of pulse- and press-droughts on carbon cycling in a mesic grassland of the US Great Plains. A series of modeling experiments were imposed by varying drought magnitude (precipitation amount) and interannual pattern (press- vs. pulse-droughts) to examine the effects on carbon storage and cycling at annual to century timescales. We present three main findings. First, a single-year pulse-drought had immediate and prolonged effects on carbon storage due to differential sensitivities of ecosystem respiration and gross primary production. Second, short-term pulse-droughts caused greater carbon loss than chronic press-droughts when total precipitation reductions over a 20-year period were equivalent. Third, combining pulse- and press-droughts had intermediate effects on carbon loss compared to the independent drought types, except at high drought levels. Overall, these results suggest that interannual drought pattern may be as important for carbon dynamics as drought magnitude and that extreme droughts may have long-lasting carbon feedbacks in grassland ecosystems. Published 2015. This article is a U

  13. Elevated CO2 and warming effects on CH4 uptake in a semiarid grassland below optimum soil moisture

    Science.gov (United States)

    Dijkstra, Feike A.; Morgan, Jack A.; von Fischer, Joseph C.; Follett, Ronald F.

    2011-03-01

    Semiarid rangelands are a significant global sink for methane (CH4), but this sink strength may be altered by climate change. Methane uptake is sensitive to soil moisture showing a hump-shaped relationship with a distinct optimum soil moisture level. Both CO2 and temperature affect soil moisture, but the direction of CH4 uptake response may depend on if the system is below or above the soil moisture optimum. Most climate change studies on CH4 uptake have been conducted in mesic environments with soil moisture levels typically above optimum, but little is known about responses in drier systems with suboptimal soil water. We studied effects of atmospheric CO2 (ambient versus 600 ppm), and temperature (ambient versus 1.5/3.0°C warmer day/night) on CH4 uptake during two growing seasons in a full factorial semiarid grassland field experiment in Wyoming, United States. We observed typical hump-shaped relationships between CH4 uptake and water filled pore space. Averaged over a range of soil moisture conditions, CH4 uptake was not affected by elevated CO2, but significantly decreased with warming in both seasons (25% in the first and 13% in the second season). Warming showed the strongest reduction and elevated CO2 showed the strongest increase in CH4 uptake when soils were below optimum moisture, indicating that these effects are particularly strong when soils are dry. Thus, directional effects of elevated CO2 and warming on CH4 uptake in semiarid grasslands can be opposite to their effects in mesic ecosystems because semiarid grasslands are often below optimum soil moisture for methane uptake.

  14. Not all droughts are created equal: The impacts of interannual drought pattern and magnitude on grassland carbon cycling

    Science.gov (United States)

    Hoover, David L.; Rogers, Brendan M.

    2016-01-01

    Climate extremes, such as drought, may have immediate and potentially prolonged effects on carbon cycling. Grasslands store approximately one-third of all terrestrial carbon and may become carbon sources during droughts. However, the magnitude and duration of drought-induced disruptions to the carbon cycle, as well as the mechanisms responsible, remain poorly understood. Over the next century, global climate models predict an increase in two types of drought: chronic but subtle ‘press-droughts’, and shorter term but extreme ‘pulse-droughts’. Much of our current understanding of the ecological impacts of drought comes from experimental rainfall manipulations. These studies have been highly valuable, but are often short term and rarely quantify carbon feedbacks. To address this knowledge gap, we used the Community Land Model 4.0 to examine the individual and interactive effects of pulse- and press-droughts on carbon cycling in a mesic grassland of the US Great Plains. A series of modeling experiments were imposed by varying drought magnitude (precipitation amount) and interannual pattern (press- vs. pulse-droughts) to examine the effects on carbon storage and cycling at annual to century timescales. We present three main findings. First, a single-year pulse-drought had immediate and prolonged effects on carbon storage due to differential sensitivities of ecosystem respiration and gross primary production. Second, short-term pulse-droughts caused greater carbon loss than chronic press-droughts when total precipitation reductions over a 20-year period were equivalent. Third, combining pulse- and press-droughts had intermediate effects on carbon loss compared to the independent drought types, except at high drought levels. Overall, these results suggest that interannual drought pattern may be as important for carbon dynamics as drought magnitude and that extreme droughts may have long-lasting carbon feedbacks in grassland ecosystems.

  15. Weathering controls on mechanisms of carbon storage in grassland soils

    Energy Technology Data Exchange (ETDEWEB)

    Masiello, C.A.; Chadwick, O.A.; Southon, J.; Torn, M.S.; Harden, J.W.

    2004-09-01

    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 of 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.

  16. High Stocking Density Controls Phillyrea Angustifolia in Mediterranean Grasslands

    Science.gov (United States)

    Mesléard, François; Yavercovski, Nicole; Lefebvre, Gaétan; Willm, Loic; Bonis, Anne

    2017-03-01

    Extensive grazing applied in the form of low instantaneous pressure over a long period is a widespread management practice in protected areas. However this kind of stocking method does not always achieve the expected results, in particular because it fails to limit colonization by woody plants.This is the case in the relict xero-halophytic grasslands of the northern Mediterranean coastal region, subjected to widespread colonization by the shrub Phillyrea angustifolia despite the presence of extensive grazing. In this study, we investigated, for an equal annual stocking rate, the respective impact of high stocking density applied over a short period (mob grazing) and low stocking density applied over a long period on both P. angustifolia and herbaceous cover, using an in situ experimental design run for 7 years. Only mob grazing was effective both in controlling the establishment and increasing the mortality of P. angustifolia individuals. We did not find any difference after the 7 years of experimentation between the two stocking methods with regard to the herbaceous community parameters tested: species richness, diversity, evenness, contribution of annual characteristic species. By contrast, the exclusion of domestic grazing led to a strong reduction of these values.The use of mob grazing may be well suited for meeting conservation goals such as maintaining open habitats in these grasslands.

  17. Permanent grassland history researches in Maramureş

    Directory of Open Access Journals (Sweden)

    Adela Lacrimioara Botis

    2015-05-01

    Full Text Available In the main part of the 20th century, research on plant nutrition was focused on inorganic nutrients, its foundations being laid by the 19th century chemist Justus von Liebing who identified the essential nutrients responsible with plant growth and promoted the use of mineral fertilizers. Although in the middle of the 20th century plant nutrition was focused on mineral fertilizers, organic nutrients still have a long history of use in agriculture and research in this field established fundamental knowledge. Permanent grasslands in Maramureş were the object of study and research from old times because of the vast area and the richness in herbal and wood species – as a result of the influence of the ecological conditions. The research conducted in the area can be divided in three periods - independent on the type of fertilizers used in the process - studies carried out during the 19th century, studies held in the 20th century and the ones in the 21st century which are developed on the concepts of ecology and sustainability to support public policies and provide environmental benefits. Although the first two periods of research in Maramureş are rich in providing information on the flora in Rodna Mountains, ţibleş Mountains, Borşa etc. and on grassland development in the area, in the last century the research scale decreased making this space auspicious for developing new data in the field.

  18. Local adaptation to temperature conserves top-down control in a grassland food web.

    Science.gov (United States)

    Barton, Brandon T

    2011-10-22

    A fundamental limitation in many climate change experiments is that tests represent relatively short-term 'shock' experiments and so do not incorporate the phenotypic plasticity or evolutionary change that may occur during the gradual process of climate change. However, capturing this aspect of climate change effects in an experimental design is a difficult challenge that few studies have accomplished. I examined the effect of temperature and predator climate history in food webs composed of herbaceous plants, generalist grasshopper herbivores and spider predators across a natural 4.8°C temperature gradient spanning 500 km in northeastern USA. In these grasslands, the effects of rising temperatures on the plant community are indirect and arise via altered predator-herbivore interactions. Experimental warming had no direct effect on grasshoppers, but reduced predation risk effects by causing spiders from all study sites to seek thermal refuge lower in the plant canopy. However, spider thermal tolerance corresponded to spider origin such that spiders from warmer study sites tolerated higher temperatures than spiders from cooler study sites. As a consequence, the magnitude of the indirect effect of spiders on plants did not differ along the temperature gradient, although a reciprocal transplant experiment revealed significantly different effects of spider origin on the magnitude of top-down control. These results suggest that variation in predator response to warming may maintain species interactions and associated food web processes when faced with long term, chronic climate warming.

  19. 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.

  20. 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