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A Field Study Of Wind Erosion Following A Grass Fire On The Llano Estacado Of North America, J.E. Stout
A Field Study Of Wind Erosion Following A Grass Fire On The Llano Estacado Of North America, J.E. Stout
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Interactions between earth, wind, and fire have always played an important role in the formation and evolution of the level plains of the Llano Estacado of North America. The uppermost sediments of this vast region are aeolian deposits, formed by aeolian deposition into grassland vegetation. Grass cover enhances aeolian deposition by slowing near-surface winds and vegetation secures sediments once they are deposited. The benefits of grass cover, however, are lost when occasional fires remove protective vegetation fromfields. After a fire, the underlying soil surface becomes exposed and susceptible to wind erosion until the vegetative cover is re-established. The purpose of …
Primary Productivity And Water Balance Of Grassland Vegetation On Three Soils In A Continuous Co2 Gradient: Initial Results From The Lysimeter Co2 Gradient Experiment, Philip A. Fay, Alexia M. Kelley, Andrew C. Procter, Dafeng Hui, Virgina L. Jin, Robert B. Jackson, Hyrum B. Johnson, H. Wayne Polley
Primary Productivity And Water Balance Of Grassland Vegetation On Three Soils In A Continuous Co2 Gradient: Initial Results From The Lysimeter Co2 Gradient Experiment, Philip A. Fay, Alexia M. Kelley, Andrew C. Procter, Dafeng Hui, Virgina L. Jin, Robert B. Jackson, Hyrum B. Johnson, H. Wayne Polley
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Field studies of atmospheric CO2 effects on ecosystems usually include few levels of CO2 and a single soil type, making it difficult to ascertain the shape of responses to increasing CO2 or to generalize across soil types. The Lysimeter CO2 Gradient (LYCOG) chambers were constructed to maintain a linear gradient of atmospheric CO2 (~250 to 500 µ 1-1) on grassland vegetation established on intact soil monoliths from three soil series. The chambers maintained a linear daytime CO2 gradient from 263 µ 1-1 at the subambient end of the gradient to 502 …
Physiological And Environmental Regulation Of Interannual Variability In Co2 Exchange On Rangelands In The Western United States, H. Wayne Polley, William Emmerich, James A. Bradford, Phillip L. Sims, Douglas H. Johnson, Nicanor Z. Saliendra, Tony Svejcar, Raymond Angell, Albert B. Frank, Rebecca L. Phillips, Keirith A. Snyder, Jack A. Morgan
Physiological And Environmental Regulation Of Interannual Variability In Co2 Exchange On Rangelands In The Western United States, H. Wayne Polley, William Emmerich, James A. Bradford, Phillip L. Sims, Douglas H. Johnson, Nicanor Z. Saliendra, Tony Svejcar, Raymond Angell, Albert B. Frank, Rebecca L. Phillips, Keirith A. Snyder, Jack A. Morgan
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
For most ecosystems, net ecosystem exchange of CO2 (NEE) varies within and among years in response to environmental change.We analyzed measurements of CO2 exchange from eight native rangeland ecosystems in the western United States (58 site-years of data) in order to determine the contributions of photosynthetic and respiratory (physiological) components of CO2 exchange to environmentally caused variation in NEE. Rangelands included Great Plains grasslands, desert shrubland, desert grasslands, and sagebrush steppe.
Root Responses Along A Subambient To Elevated Co2 Gradient In A C3–C4 Grassland, Laurel J. Anderson, Justin D. Derners, H. Wayne Polley, Wendy S. Gordon, David M. Eissenstat, Robert B. Jackson
Root Responses Along A Subambient To Elevated Co2 Gradient In A C3–C4 Grassland, Laurel J. Anderson, Justin D. Derners, H. Wayne Polley, Wendy S. Gordon, David M. Eissenstat, Robert B. Jackson
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Atmospheric CO2 (Ca) concentration has increased significantly during the last 20 000 years, and is projected to double this century. Despite the importance of belowground processes in the global carbon cycle, community-level and single species root responses to rising Ca are not well understood. We measured net community root biomass over 3 years using ingrowth cores in a natural C3–C4 grassland exposed to a gradient of Ca from preglacial to future levels (230–550 µmol mol-1).
Spatiotemporal Dynamics Of Black-Tailed Prairie Dog Colonies Affected By Plague, David J. Augustine, Marc R. Matchett, Theodore P. Toombs, Jack F. Cully, Tommy L. Johnson, J. G. Sidle
Spatiotemporal Dynamics Of Black-Tailed Prairie Dog Colonies Affected By Plague, David J. Augustine, Marc R. Matchett, Theodore P. Toombs, Jack F. Cully, Tommy L. Johnson, J. G. Sidle
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Black-tailed prairie dogs (Cynomys ludovicianus) are a key component of the disturbance regime in semi-arid grasslands of central North America. Many studies have compared community and ecosystem characteristics on prairie dog colonies to grasslands without prairie dogs, but little is known about landscape-scale patterns of disturbance that prairie dog colony complexes may impose on grasslands over long time periods. We examined spatiotemporal dynamics in two prairie dog colony complexes in southeastern Colorado (Comanche) and northcentral Montana (Phillips County) that have been strongly influenced by plague, and compared them to a complex unaffected by plague in northwestern Nebraska (Oglala). …
Increasing Co2 From Subambient To Superambient Concentrations Alters Species Composition And Increases Above-Ground Biomass In A C3/C4 Grassland, H. W. Polley, Hyrum B. Johnson, Justin D. Derner
Increasing Co2 From Subambient To Superambient Concentrations Alters Species Composition And Increases Above-Ground Biomass In A C3/C4 Grassland, H. W. Polley, Hyrum B. Johnson, Justin D. Derner
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
The glacial-to-present increase in atmospheric CO2 concentration is likely to have stimulated plant production, but experimental tests in natural ecosystems are lacking.
Net Grassland Carbon Flux Over A Subambient To Superambient Co2 Gradient, P. C. Mielnick, W. A. Dugas, H. B. Johnson, H. W. Polley, J. Sanabria
Net Grassland Carbon Flux Over A Subambient To Superambient Co2 Gradient, P. C. Mielnick, W. A. Dugas, H. B. Johnson, H. W. Polley, J. Sanabria
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Increasing atmospheric CO2 concentrations may have a profound effect on the structure and function of plant communities. A previously grazed, central Texas grassland was exposed to a 200-µmol mol-1 to 550 µmol mol-1 CO2 gradient from March to mid-December in 1998 and 1999 using two, 60-m long, polyethylene-covered chambers built directly onto the site. One chamber was operated at subambient CO2 concentrations (200-360 µmol mol-1 daytime) and the other was regulated at superambient concentrations (360-550 µmol mol-1). Continuous CO2 gradients were maintained in each chamber by photosynthesis during the day and …
Gas Exchange And Photosynthetic Acclimation Over Subambient To Elevated Co2 In A C3-C4 Grassland, Laurel J. Anderson, Hafiz Maherali, Hyrum B. Johnson, H. Wayne Polley, Robert B. Jackson
Gas Exchange And Photosynthetic Acclimation Over Subambient To Elevated Co2 In A C3-C4 Grassland, Laurel J. Anderson, Hafiz Maherali, Hyrum B. Johnson, H. Wayne Polley, Robert B. Jackson
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Atmospheric CO2 (Ca) has risen dramatically since preglacial times and is projected to double in the next century. As part of a 4-year study, we examined leaf gas exchange and photosynthetic acclimation in C3 and C4 plants using unique chambers that maintained a continuous Ca gradient from 200 to 550 µmol mol-1 in a natural grassland. Our goals were to characterize linear, nonlinear and threshold responses to increasing Ca from past to future Ca levels. Photosynthesis (A), stomatal conductance (gs), leaf water-use efficiency (A/gs …