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Full-Text Articles in Botany
Shrub Encroachment Alters Sensitivity Of Soil Respiration To Temperature And Moisture, J. M. Cable, G. A. Barron-Gafford, K. Ogle, M. Pavao-Zuckerman, R. L. Scott, David G. Williams, T. E. Huxman
Shrub Encroachment Alters Sensitivity Of Soil Respiration To Temperature And Moisture, J. M. Cable, G. A. Barron-Gafford, K. Ogle, M. Pavao-Zuckerman, R. L. Scott, David G. Williams, T. E. Huxman
David G Williams
A greater abundance of shrubs in semiarid grasslands affects the spatial patterns of soil temperature, moisture, and litter, resulting in fertile islands with potentially enhanced soil metabolic activity. The goal of this study was to quantify the microsite specificity of soil respiration in a semiarid riparian ecosystem experiencing shrub encroachment. We quantified the response of soil respiration to different microsite conditions created by big mesquite shrubs (near the trunk and the canopy edge), medium-sized mesquite, sacaton bunchgrasses, and open spaces. We hypothesized that soil respiration would be more temperature sensitive and less moisture sensitive and have a greater magnitude in …
Carbon And Oxygen Isotope Analysis Of Leaf Biomass Reveals Contrasting Photosynthetic Responses To Elevated Co(2) Near Geologic Vents In Yellowstone National Park, S. Sharma, David G. Williams
Carbon And Oxygen Isotope Analysis Of Leaf Biomass Reveals Contrasting Photosynthetic Responses To Elevated Co(2) Near Geologic Vents In Yellowstone National Park, S. Sharma, David G. Williams
David G Williams
In this study we explore the use of natural CO2 emissions in Yellowstone National Park (YNP) in Wyoming, USA to study responses of natural vegetation to elevated CO2 levels. Radiocarbon (14C) analysis of leaf biomass from a conifer (Pinus contortus; lodgepole pine) and an invasive, non-native herb (Linaria dalmatica; Dalmation toadflax) was used to trace the inputs of vent CO2 and quantify assimilation-weighted CO2 concentrations experienced by individual plants near vents and in comparable locations with no geologic CO2 exposure. The carbon and oxygen isotopic composition and nitrogen percent of leaf biomass from the same plants was used to investigate …
Daily To Decadal Patterns Of Precipitation, Humidity, And Photosynthetic Physiology Recorded In The Spines Of The Columnar Cactus, Carnegiea Gigantea, N. B. English, D. L. Dettman, D. R. Sandquist, David G. Williams
Daily To Decadal Patterns Of Precipitation, Humidity, And Photosynthetic Physiology Recorded In The Spines Of The Columnar Cactus, Carnegiea Gigantea, N. B. English, D. L. Dettman, D. R. Sandquist, David G. Williams
David G Williams
Isotopic analyses of cactus spines grown serially from the apex of long-lived columnar cactuses may be useful for climatological and ecological studies if time series can be reliably determined from spines. To characterize the timescales over which spines may record this information, we measured spine growth in saguaro cactus over days, months, and years with time-lapse photography, periodic marking, and postbomb radiocarbon dating and then analyzed isotopic variability over these same timescales and compared these measurements to local climate. We used daily increments of growth, visible as transverse bands of light and dark tissue in spines, as chronometers to develop …