A5068455420- Ecology and Vegetation Dynamics Studies
- Plant Water Relations and Carbon Dynamics
- Plant and animal studies
- Rangeland and Wildlife Management
- Plant responses to water stress
- Soil and Unsaturated Flow
- Tree-ring climate responses
- Karst Systems and Hydrogeology
- Hydrology and Watershed Management Studies
- Plant Parasitism and Resistance
- Plant responses to elevated CO2
- Fire effects on ecosystems
- Forest ecology and management
- Soil erosion and sediment transport
- Hydrology and Sediment Transport Processes
- Soil Carbon and Nitrogen Dynamics
- Species Distribution and Climate Change
- Mathematical and Theoretical Epidemiology and Ecology Models
- Plant Ecology and Soil Science
- Soil Moisture and Remote Sensing
- Landslides and related hazards
- Biocrusts and Microbial Ecology
- Geology and Paleoclimatology Research
- Bioenergy crop production and management
- Animal Ecology and Behavior Studies
Texas State University
2013-2022
Oracle (United States)
2003-2005
University of Arizona
1990-2004
University of Utah
1998-2003
Changes in Earth's surface temperatures caused by anthropogenic emissions of greenhouse gases are expected to affect global and regional precipitation regimes. Interactions between changing regimes other aspects change likely natural managed terrestrial ecosystems as well human society. Although much recent research has focused on assessing the responses rising carbon dioxide or temperature, relatively little understanding how respond changes Here we review predicted regimes, outline...
Summary We introduce a hydraulic soil‐plant model with water uptake from two soil layers; one pulse‐dominated shallow layer, the other deeper layer continuous, but generally less than saturated moisture. Water is linked to photosynthetic carbon assimilation through photosynthesis for C 3 plants. A genetic algorithm used identify character suites that maximize gain plants experience particular moisture pattern. The include allocation fraction stem, leaves and root, stem capacitance storage...
Abstract Large portions of the world are characterized by shallow soil underlain weathered bedrock or cemented horizons. The implications this substrate condition for ecohydrological processes have not been systematically explored, but misrepresentation in models could profound consequences climate prediction and global vegetation modelling. An issue particular uncertainty is characterization water storage these regions. A limited number case studies shown that plant uptake restricted to...
1 It is widely assumed that grass-legume associations offer a way to sustainable, low input land use, with reduced environmental impact. However, combination of both ecological and physiological principles may be needed understand the sustainability species balances. 2 To increase understanding dynamics, we developed model extends recently proposed pasture (Thornley, Bergelson & Parsons: Annals Botany 1995, 75, 79-94) by including selective grazing spatial considerations. Population...
The amount and spatial distribution of deep drainage (downward movement water across the bottom root zone) groundwater recharge affect quantity quality increasingly limited in arid semiarid regions. We synthesize research from fields ecology hydrology to address issue start with a recently developed hydrological model that accurately simulates soil potential geochemical profiles measured thick (>50 m), unconsolidated vadose zones. Model results indicate that, since climate change marked...
Abstract Common garden experiments are indoor or outdoor plantings of species populations collected from multiple distinct geographic locations, grown together under shared conditions. These examine a range questions for theory and application using variety methods analysis. The eight papers this special feature comprise cross section contemporary approaches, summarized synthesized here by what they tell us about the relationships between climate‐related trait spectra fitness optima. Four...
1 In a previous paper, we outlined the physiological prerequisites for population oscillations between grass and nitrogen-fixing legume, such as clover. Here, examine field-scale consequences of patch-scale in legume content, using cellular automaton with variable hierarchy two species. 2 We define cell states by species content soil N status. Grasslegume at patch scale are represented an alternation dominance (high N) (low N). To this physiologically based oscillation, add local extinctions...
ABSTRACT Woody plants are encroaching into grasslands and savannas of the karst Edwards Plateau, but their impacts on climate hydrology unclear because high variability in soil depth uncertainties about contribution water fractured limestone to available trees. Water use is controlled by energy ( AE ) its partitioning between latent λE sensible H heat fluxes. We hypothesized that depends depth, with greater leading more less . compared fluxes a deep savanna ~50% woody cover dominated Ashe...
Summary We review plant competition in water‐limited environments with focus on temporal niche dynamics and examine implications for diversity–productivity relationships the response of ecosystem productivity to changes water availability. The main theses under examination are that (i) functional types ( PFT s) have distinct resource pulse use coexist through mechanism complementarity; (ii) species same (functionally redundant species) recruitment niches. In systems, opportunities uptake...
Hot drought is a climate phenomenon that has lately received much attention for its potential to disrupt forest function worldwide. A sharp increase in tree mortality associated with this pattern are often cast as disturbance, which high temperature responsible causing exceptional rates of mortality. The alternative interpretation simply kills trees density-regulating manner and within the bounds normal function. To evaluate evidence disturbance versus regulating dynamics, we conducted...
In desert ecosystems a large proportion of water and nitrogen is supplied in rain-induced pulses. It has been suggested that competitive interactions among plants would be most intense during these pulse periods high resource availability. We tested this hypothesis with three cold shrub species the Colorado Plateau (Gutierrezia sarothrae, Atriplex confertifolia, Chrysothamnus nauseosus), which differ their distribution functional roots. three-year field study we conducted neighbor removal...
Asymmetric competition is a form of resource division among plants, in which large plants greatly suppress the growth smaller neighbors. In annual small size differences between seedlings at onset are magnified into seed-set by asymmetric competition. We formulate novel neighborhood model, reflects this seedling effect as modified type competitive symmetry. represented single, biologically meaningful parameter. implement model population for two species, one low density (the invader), and...
We simulated the habitat selection behavior in a three population predator-prey system with mid-level predator that is also prey. There were two habitats, one of which was relative refuge from predation. Individuals model moved to wherever they could improve their fitness, as if subject rules ideal-free distribution. However, populations generally not achieve simultaneous distributions. Instead, individuals shifted back and forth between habitats. Such oscillations stabilized ways: 1)...
In 1975, Noy-Meir presented a comprehensive, graphical stability analysis for plant–herbivore interactions. Inspired by the of predator–prey interactions Rosenzweig & MacArthur (1963), he cast model in form ordinary differential equations, representing grazing as homogeneous process space and continuous time (Noy-Meir 1975). His demonstrated that continuously grazed ecosystem may have multiple stable states be 'discontinuously stable' (see also reviews May 1977; Tainton, Morris Hardy 1996)....