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This map represents the change between 1971-2000 and 2071-2100 in the annual peak fraction of total live vegetation carbon held in herbaceous plants, as simulated by the model MC1 under the CSIRO Mk3 future climate projection and A2 anthropogenic emissions scenario. The range of data values is from -0.741 to +0.999. The mean value is +0.107. Data values are calculated as GFRAC(2071-2100) minus GFRAC(1971-2000). GFRAC data is from MC1 version B60. The dynamic global vegetation model MC1 (e.g. Bachelet et al. 2001) was used to simulate vegetation dynamics, associated carbon and nitrogen cycle, water budget, and wild fire impacts at two study sites in eastern Oregon (Deschutes and Fremont-Winema National Forests)...
Shifts in plant community structure in shrub and grass-dominated ecosystems are occurring over large land areas in the western US. It is not clear what effect this vegetative change will have on rates of carbon and nitrogen cycling, and thus long-term ecosystem productivity. To study the effect of different plant species on the decomposability of soil organic substrates and rates of C- and N-cycling, we conducted laboratory incubations of soils from a 15-yr-old experimental plot where big sagebrush (Artemisia tridentata Nutt.) and crested wheatgrass (Agropyron desertorum [Fisch.] Schult.) plants had been planted in a grid pattern. Soil samples collected from beneath crested wheatgrass had significantly greater total...
Abstract The importance of snow and related cryospheric processes as an ecological factor has been recognized since at least the beginning of the twentieth century. Even today, however, many observations remain anecdotal. The research to date on cold-lands ecosystems results in scientists being unable to evaluate to what extent changes in the cryosphere will be characterized by abrupt changes in local and global biogeochemical cycles, and how these changes in seasonality may affect the rates and timing of key ecological processes. Studies of gas exchanges through snow have revealed that snow plays an important role in modulating wintertime soil biogeochemical processes, and that these can be the driving processes...
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To assess the distribution, frequency, and global extent of riverine hypoxia, we compiled 118 million paired dissolved oxygen (DO) and water temperature measurements from 125,158 unique locations in rivers in 93 countries and territories across the globe. The dataset also includes site characteristics derived from StreamCat, the National Hydrography and HydroAtlas datasets and proximal land cover derived from MODIS-based IGBP land cover types compiled using Google Earth Engine (GEE).
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Predicted changes in climate may affect key soil processes such as respiration and net nitrogen (N) mineralization and thus key ecosystem functions such as carbon (C) storage and nutrient availability. To identify the sensitivity of shrubland soils to predicted climate changes, we have carried out experimental manipulations involving ecosystem warming and prolonged summer drought in ericaceous shrublands across a European climate gradient. We used retractable covers to create artificial nighttime warming and prolonged summer drought to 20-m 2 experimental plots. Combining the data from across the environmental gradient with the results from the manipulation experiments provides evidence for strong climate controls...
In semiarid ecosystems, physiography (landscape setting) may interact with woody-plant and soil microbe communities to constrain seasonal exchanges of material and energy at the ecosystem scale. In an upland and riparian shrubland, we examined the seasonally dynamic linkage between ecosystem CO2 exchange, woody-plant water status and photosynthesis, and soil respiration responses to summer rainfall. At each site, we compared tower-based measurements of net ecosystem CO2 exchange (NEE) with ecophysiological measurements among velvet mesquite (Prosopis velutina Woot.) in three size classes and soil respiration in sub-canopy and inter-canopy micro-sites. Monsoonal rainfall influenced a greater shift in the magnitude...
In the arid and semiarid regions of North America, discrete precipitation pulses are important triggers for biological activity. The timing and magnitude of these pulses may differentially affect the activity of plants and microbes, combining to influence the C balance of desert ecosystems. Here, we evaluate how a "pulse" of water influences physiological activity in plants, soils and ecosystems, and how characteristics, such as precipitation pulse size and frequency are important controllers of biological and physical processes in arid land ecosystems. We show that pulse size regulates C balance by determining the temporal duration of activity for different components of the biota. Microbial respiration responds...
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This map represents the mean for the 30 year period 1971-2000 of the annual peak value of the fraction of live vegetation carbon which is in herbaceous (as opposed to woody) vegetation. The data is from output variable GFRAC in MC1 version B60. The data values are unitless fractions and range from 0 to 1. The mean value is 0.101.
? The influences of prior monsoon-season drought (PMSD) and the seasonal timing of episodic rainfall (?pulses?) on carbon and water exchange in water-limited ecosystems are poorly quantified. ? In the present study, we estimated net ecosystem exchange of CO2 (NEE) and evapotranspiration (ET) before, and for 15 d following, experimental irrigation in a semi-arid grassland during June and August 2003. Rainout shelters near Tucson, Arizona, USA, were positioned on contrasting soils (clay and sand) and planted with native (Heteropogon contortus) or non-native invasive (Eragrostis lehmanniana) C4 bunchgrasses. Plots received increased (?wet?) or decreased (?dry?) monsoon-season (July?September) rainfall during 2002 and...
Shifts in plant community structure in shrub and grass-dominated ecosystems are occurring over large land areas in the western US. It is not clear what effect this vegetative change will have on rates of carbon and nitrogen cycling, and thus long-term ecosystem productivity. To study the effect of different plant species on the decomposability of soil organic substrates and rates of C- and N-cycling, we conducted laboratory incubations of soils from a 15-yr-old experimental plot where big sagebrush (Artemisia tridentata Nutt.) and crested wheatgrass (Agropyron desertorum [Fisch.] Schult.) plants had been planted in a grid pattern. Soil samples collected from beneath crested wheatgrass had significantly greater total...
Carbon gain depends on efficient photosynthesis and adequate respiration. The effect of temperature on photosynthetic efficiency is well understood. In contrast, the temperature response of respiration is based almost entirely on short-term (hours) measurements in mature organisms to develop Q(10) values for maintenance and whole-plant respiration. These Q(10) values are then used to extrapolate across whole life cycles to predict the influence of temperature on plant growth. Published in Annals of Botany, volume 94, issue 1, on pages 155 - 66, in 2004.
This study is part of an assessment of potential effects of climate change on the St. Lawrence Great Lakes. Its purpose is to investigate potential future lake mixing patterns and primary production. Nested physical and biological models were applied to seasonal mixed layer depth, heat content, primary productivity, and to algal biomass measured as particulate chlorophyll. Two independent second generation General Circulation Models provided scenarios for future conditions of cloud cover, air temperature, humidity, and winds. The climate variables were used to force heat balance and surface mixed layer models for Lakes Superior, Michigan, Huron, Erie, and Ontario. Physical models of heat balance and mixed layer...
Coleogyne ramosissima Torr. (blackbrush) and Atriplex confertifolia [Torr. & Frem.] Wats. (shadscale) are cold desert shrubs from different families. Despite very different life histories they often grow in close geographic proximity in the Great Basin and the Colorado Plateau between 800 and 2000 m elevation. The purpose of this study is to compare the ecophysiology of slow growing and reproducing blackbrush with the ecophysiology of faster growing and reproducing shadscale. Metabolic heat and carbon dioxide production rates were measured on leaf tissue from wild plants and on lab-grown seedlings at temperatures from 10 to 35 °C at 5 °C intervals. Heat of combustion, ash content, and carbon and nitrogen contents...
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This map represents the mean annual fraction of the gridcell affected by wildfire, simulated by the model MC1 for the 30-year period 1971-2000. The data is from output variable PART_BURN in MC1 version B60. The data is a unitless fraction; values range from 0 to 0.110. The mean value is 0.008.
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This map represents the modal vegetation type in each gridcell, as simulated by the model MC1 for the 30-year period 2071-2100, using the CSIRO Mk3 future climate projection under the A2 anthropogenic emission scenario. The data is from output variable VTYPE in MC1 version B60. The vegetation model MC1 (e.g. Bachelet et al. 2001) was used to simulate vegetation dynamics, associated carbon and nitrogen cycle, water budget, and wild fire impacts at two study sites in eastern Oregon (Deschutes ...) and in Arizona (Apache Sitgreaves National Forest area) in the context of a project funded by the USDA Forest Service (PNW 09-JV-11261900-003). Historical climate input data used to run the model were provided by the...
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This map represents the modal vegetation type in each gridcell, as simulated by the model MC1 for the 30-year period 2071-2100, using the MIROC 3.2 medres future climate projection under the A2 anthropogenic emission scenario. The data is from output variable VTYPE in MC1 version B60. The vegetation model MC1 (e.g. Bachelet et al. 2001) was used to simulate vegetation dynamics, associated carbon and nitrogen cycle, water budget, and wild fire impacts at two study sites in eastern Oregon (Deschutes ...) and in Arizona (Apache Sitgreaves National Forest area) in the context of a project funded by the USDA Forest Service (PNW 09-JV-11261900-003). Historical climate input data used to run the model were provided...
Cheatgrass (Bromus tectorum L.) is a dominant weed that has increased the frequency of wildfire in the Great Basin since its introduction about 100 yr ago. This study examines characteristics of respiratory metabolism in several different populations. Seeds from 6 populations were germinated and metabolic heat rates (q) and dark respiration rates (Rco2) of all seedlings were measured calorimetrically at 15° and 25° C or (for 3 populations) at 5° intervals from 5° to 35° C. Growth rates, substrate carbon conversion efficiencies, and Arrhenius temperature coefficients were calculated from the data. Results show that cheatgrass metabolism is most efficient at temperatures near 0° C; at temperatures above 20-25°...
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This map represents the modal vegetation type in each gridcell, as simulated by the model MC1 for the 30-year period 1971-2000. The data is from output variable VTYPE in MC1 version B60. The vegetation model MC1 (e.g. Bachelet et al. 2001) was used to simulate vegetation dynamics, associated carbon and nitrogen cycle, water budget, and wild fire impacts at two study sites in eastern Oregon, Deschutes and Fremont-Winema National Forests, in the context of a project funded by the USDA Forest Service (PNW 09-JV-11261900-003). Historical climate input data used to run the model were provided by the PRISM group (Chris Daly, OSU) at a 30arc second (800m) spatial grain. The model was also run using future climate...
map background search result map search result map The Response of Soil Processes to Climate Change: Results from Manipulation Studies of Shrublands Across an Environmental Gradient Average annual value of the peak monthly fraction of live biomass in grass 2071 to 2100 under CSIRO A2 climate scenario for the easern Oregon study area USA Change in the fraction of total live vegetation carbon held in herbaceous plants between 1971-2000 and 2071-2000, as simulated by MC1 under CSIRO Mk3 A2 for the eastern Oregon study area, Oregon, USA Simulated vegetation types (2071-2100) under MIROC medres A2 for the eastern Oregon study area, USA Average annual value of the peak monthly fraction of live biomass in grass 2071 to 2100 under MIROC A2 climate scenario for the easern Oregon study area USA Simulated vegetation types (2071-2100) under CSIRO Mk3 A2 for the eastern Oregon study area, Oregon, USA Average annual fraction of grid cell burned (1971-2000) for the eastern Oregon study area, USA Vegetation types (1971-2000) for the eastern Oregon study area, USA Annual fraction of the total live vegetation carbon held in herbaceous plants (1971-2000) for the Eastern Oregon study area, USA Average annual value of the peak monthly fraction of live biomass in grass 2071 to 2100 under CSIRO A2 climate scenario for the easern Oregon study area USA Change in the fraction of total live vegetation carbon held in herbaceous plants between 1971-2000 and 2071-2000, as simulated by MC1 under CSIRO Mk3 A2 for the eastern Oregon study area, Oregon, USA Simulated vegetation types (2071-2100) under MIROC medres A2 for the eastern Oregon study area, USA Average annual value of the peak monthly fraction of live biomass in grass 2071 to 2100 under MIROC A2 climate scenario for the easern Oregon study area USA Simulated vegetation types (2071-2100) under CSIRO Mk3 A2 for the eastern Oregon study area, Oregon, USA Average annual fraction of grid cell burned (1971-2000) for the eastern Oregon study area, USA Vegetation types (1971-2000) for the eastern Oregon study area, USA Annual fraction of the total live vegetation carbon held in herbaceous plants (1971-2000) for the Eastern Oregon study area, USA The Response of Soil Processes to Climate Change: Results from Manipulation Studies of Shrublands Across an Environmental Gradient