Dave S. Schimel

Learn More
Ecosystem properties of surficial (0–10 cm) soils in remnant herbaceous patches were compared to those of contrasting woody plant patch types (upland discrete cluster, upland grove, and lowland woodland) where shifting land cover is known to have occurred over the past 50–77 yr. The purpose of this study was to evaluate and quantify the biogeochemical(More)
Recent projections of climatic change have focused a great deal of scientific and public attention on patterns of carbon (C) cycling as well as its controls, particularly the factors that determine whether an ecosystem is a net source or sink of atmospheric carbon dioxide (CO2). Net ecosystem production (NEP), a central concept in C-cycling research, has(More)
Soil organic C content, a major source of system stability in agroecosystems, is controlled by many factors that have complex interactions. The purpose of this study was to evaluate the major controls over soil organic carbon content, and to predict regional patterns of carbon in range and cultivated soils. We obtained pedon and climate data for 500(More)
In many of the world’s drylands, human-induced alteration of grazing and fire regimes over the past century has promoted the replacement of grasses by woody vegetation. Here, we evaluate the magnitude of changes in plant and soil carbon and nitrogen pools in a subtropical landscape undergoing succession from grassland to thorn woodland in southern Texas.(More)
Analysis and simulation of biospheric responses to historical forcing require surface climate data that capture those aspects of climate that control ecological processes, including key spatial gradients and modes of temporal variability. We developed a multivariate, gridded historical climate dataset for the conterminous USA as a common input database for(More)
We integrated soil models with an established ecosystem process model (SIPNET, simplified photosynthesis and evapotranspiration model) to investigate the influence of soil processes on modelled values of soil CO2 fluxes (R Soil). Model parameters were determined from literature values and a data assimilation routine that used a 7-year record of the net(More)
Aims To determine if an experimentally applied anomalous weather year could have effects on species composition and community structure that would carry over into the following year. Methods We conducted a field experiment applying two levels of temperature (ambient and +4 C) and two levels of precipitation (ambient and doubled) and followed cover of plant(More)
Hyperthermia, as measured by increase in rectal temperature, was studied in a group of 22 adult mongrel sled dogs that had been selectively bred for high-speed (up to 33 km/h) races 16-50 km in distance. Under normal working conditions, rectal temperature in the sled dogs increased significantly during initial 15-20 min of run (gathered gallop) after which(More)
  • 1