A5070975541- Plant Water Relations and Carbon Dynamics
- Tree-ring climate responses
- Forest ecology and management
- Ecology and Vegetation Dynamics Studies
- Climate variability and models
- Rangeland and Wildlife Management
- Plant responses to water stress
- Tree Root and Stability Studies
- Fire effects on ecosystems
- Hydrology and Watershed Management Studies
- Soil Carbon and Nitrogen Dynamics
- Plant responses to elevated CO2
- Species Distribution and Climate Change
- Atmospheric and Environmental Gas Dynamics
- Plant nutrient uptake and metabolism
- Geology and Paleoclimatology Research
- Plant Ecology and Soil Science
- Plant and animal studies
- Water Quality and Resources Studies
- Peatlands and Wetlands Ecology
- Archaeology and Natural History
- Soil and Unsaturated Flow
- Forest Management and Policy
- Irrigation Practices and Water Management
- Cryospheric studies and observations
University of New Mexico
2015-2024
Sevilleta Long Term Ecological Research
2023
University of Minnesota
2020
Texas A&M University
2020
Minnesota Department of Natural Resources
2020
Duke University
1999-2004
University of Utah
1993-2002
Max Planck Institute for Biogeochemistry
2002
Smithsonian Environmental Research Center
1993
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...
Despite decades of research on plant drought tolerance, the physiological mechanisms by which trees succumb to are still under debate. We report results from an experiment designed separate and test current leading hypotheses tree mortality. show that piñon pine (Pinus edulis) can die both hydraulic failure carbon starvation, during drought, loss conductivity carbohydrate reserves also co-occur. Hydraulic constraints use determined survival time: turgor in phloem limited access reserves, but...
Increases in the abundance or density of woody plants historically semiarid and arid grassland ecosystems have important ecological, hydrological, socioeconomic implications. Using a simplified water-balance model, we propose framework for conceptualizing how plant encroachment is likely to affect components water cycle within these ecosystems. We focus particular on streamflow partitioning evapotranspiration into evaporation transpiration. On basis this framework, suggest that processes are...
The ability of plants to supply water their leaves is intimately associated with survival. Water depends on maintaining an intact column in the xylem from roots shoots. Because this hydraulic pathway under tension, it vulnerable breakage through induction air emboli (cavitation). Although physiological benefit resistance water-stress-induced cavitation for desiccation tolerance clear, there considerable interspecific variation within and across climates. To understand adaptive significance...
We studied 15 riparian and upland Sonoran desert species to evaluate how the limitation of xylem pressure (Ψ(x)) by cavitation corresponded with plant distribution along a moisture gradient. Riparian were obligate trees (Fraxinus velutina, Populus fremontii, Salix gooddingii), native shrubs (Baccharis spp.), an exotic shrub (Tamarix ramosissima). Upland evergreen (Juniperus monosperma, Larrea tridentata), drought-deciduous (Ambrosia dumosa, Encelia farinosa, Fouquieria splendens, Cercidium...
The effects of short-term drought on soil microbial communities remain largely unexplored, particularly at large scales and under field conditions. We used seven experimental sites from two continents (North America Australia) to evaluate the impacts imposed extreme abundance, community composition, richness, function bacterial fungal communities. encompassed different grassland ecosystems spanning a wide range climatic properties. Drought significantly altered composition bacteria and,...
Summary To test the hypothesis that drought predisposes trees to insect attacks, we quantified effects of water availability on tree resistance mechanisms, and mortality mature piñon pine ( Pinus edulis ) one‐seed juniper Juniperus monosperma using an experimental study in New Mexico, USA. The had four replicated treatments (40 × 40 m plot/replicate): removal 45% ambient annual precipitation (H 2 O−); irrigation produce 125% O+); a control (C) quantify impact infrastructure; (A). Piñon began...
Climatic changes are altering Earth's hydrological cycle, resulting in altered precipitation amounts, increased interannual variability of precipitation, and more frequent extreme events. These trends will likely continue into the future, having substantial impacts on net primary productivity (NPP) associated ecosystem services such as food production carbon sequestration. Frequently, experimental manipulations have linked regimes to NPP. Yet, findings been diverse uncertainty still...
Ecosystem models have difficulty predicting plant drought responses, partially from uncertainty in the stomatal response to water deficits soil and atmosphere. We evaluate a 'supply-demand' theory for water-limited behavior that avoids typical scaffold of empirical functions. The premise is canopy demand regulated proportion threat supply posed by xylem cavitation drying. was implemented trait-based soil-plant-atmosphere model. model predicted transpiration (E), diffusive conductance (G),...
Microbial communities regulate many belowground carbon cycling processes; thus, the impact of climate change on structure and function soil microbial could, in turn, release or storage soils. Here we used a large-scale precipitation manipulation (+18%, -50%, ambient) piñon-juniper woodland (Pinus edulis-Juniperus monosperma) to investigate how changes amounts altered as well what role seasonal variation rainfall plant composition played community response. Seasonal variability had larger...
Ecological processes in arid lands are often described by the pulse-reserve paradigm, which rain events drive biological activity until moisture is depleted, leaving a reserve. This paradigm frequently applied to stimulated one or few precipitation within growing season. Here we expand original framework time and space include other pulses that interact with rainfall. new hierarchical pulse-dynamics integrates through pulse-driven exchanges, interactions, transitions, transfers occur across...
ABSTRACT The extent to which stomatal conductance ( g s ) was capable of responding reduced hydraulic k )and preventing cavitation‐inducing xylem pressures evaluated in the small riparian tree, Betula occidentalis Hook. We decreased by inducing cavitation shoots using an air‐injection technique. From 1 18 d after shoot injection we measured midday transpiration rate (E), , and pressure (Ψ p‐xylem on individual leaves crown. then harvested made direct measurements from trunk (2–3 cm diameter)...
Two methods were evaluated for using centrifugal force to measure the occurrence of cavitation as a function negative pressures in xylem. The general protocol was hydraulic conductivity xylem segments (stem or root pieces) before and after centring them on centrifuge rotor spinning about their long axis generate pressure. percentage decrease from initial final measurement used quantify embolism resulting during spinning. In one approach, spun with ends exposed air. This method could only be...
Belowground vertical community composition and maximum rooting depth of the Edwards Plateau central Texas were determined by using DNA sequence variation to identify roots from caves 5–65 m deep. Roots identified comparing their sequences for internal transcribed spacer (ITS) region 18S–26S ribosomal repeat against a reference ITS database developed woody plants region. Sequencing provides, our knowledge, first universal method identifying plant roots. At least six tree species in system...