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SUMMARY Model-data comparisons of plant physiological processes provide an understanding of mechanisms underlying vegetation responses to climate. We simulated the physiology of a piñon pine-juniper woodland (Pinus edulis-Juniperus monosperma) that experienced mortality during a 5 yr precipitation-reduction experiment, allowing a framework with which to(More)
Accurate predictions of sediment yield from distributed models of runoff and sediment yield depends in part of how well matched the model structure is to input data spatial representation. This study investigated how model structure and input data representation affect sediment predictions made using the Soil and Water Assessment Tool (SWAT). The study(More)
This paper presents a new method for extracting flow directions, contributing (upslope) areas, and nested catchments from digital elevation models in lake-dominated areas. Existing tools for acquiring descriptive variables of the topography, such as surface flow directions and contributing areas, were developed for moderate to steep topography. These tools(More)
To quantify the relationship between temporal and spatial variation in tree transpiration, we measured sap flow in 129 trees with constant-heat sap flow sensors in a subalpine forest in southern Wyoming, USA. The forest stand was located along a soil water gradient from a stream side to near the top of a ridge. The stand was dominated by Pinus contorta(More)
Many modern hydrological models require data inputs provided by automated digital terrain analysis functions incorporated into GIS. These inputs include elds representing surface ow directions, up-slope contributing areas, and sub-catchment partitions. Existing raster-based terrain analysis tools, including both those in oOE-the-shelf GIS packages and those(More)
Global information systems have the potential of providing decision makers with timely spatial information about earth systems. This information will come from diverse sources, including field monitoring, remotely sensed imagery, and environmental models. Of the three the latter has the greatest potential of providing regional and global scale information(More)
Spatial models of ecological and hydrological processes are widely used tools for studying natural systems over large areas. However, these models lack speciÿc mechanisms for reporting output uncertainty contributed by model structure, and so testing their suitability for studying a large range of problems is diicult. This paper describes a method of(More)
A Jarvis based [Philos. Trans. R. Soc. London, Ser. B 273 (1976) 593] model of canopy stomatal conductance was evaluated in context of its application to simulating transpiration in a conifer forest covered watershed in the Central Sierra Nevada of California, USA. Parameters influencing stomatal conductance were assigned values using Monte Carlo sampling.(More)
Hydraulic systems of plants have evolved in the context of carbon allocation and fitness trade-offs of maximizing carbon gain and water transport in the face of short and long-term fluctuations in environmental conditions. The resulting diversity of traits include a continuum of isohydry-anisohydry or high to low relative stomatal closure during drought,(More)