A5022244166- Soil Carbon and Nitrogen Dynamics
- Ecology and Vegetation Dynamics Studies
- Peatlands and Wetlands Ecology
- Plant Water Relations and Carbon Dynamics
- Soil and Water Nutrient Dynamics
- Plant and animal studies
- Plant responses to elevated CO2
- Climate change and permafrost
- Species Distribution and Climate Change
- Botany and Plant Ecology Studies
- Geology and Paleoclimatology Research
- Historical Geopolitical and Social Dynamics
- Central European national history
- European history and politics
- Cryospheric studies and observations
- Isotope Analysis in Ecology
- Microbial Community Ecology and Physiology
- Mycorrhizal Fungi and Plant Interactions
- Lichen and fungal ecology
- Coastal wetland ecosystem dynamics
- Atmospheric chemistry and aerosols
- Botany, Ecology, and Taxonomy Studies
- Animal Ecology and Behavior Studies
- Plant Stress Responses and Tolerance
- Plant responses to water stress
University of Colorado Boulder
2014-2024
University of Colorado System
1968-2023
Institute of Arctic and Alpine Research
2010-2019
Ecological Society of America
2018
John Wiley & Sons (United States)
2018
Eastern Oregon University
2014
Gettysburg College
1999-2011
Stanford University
2008
Cooperative Institute for Research in Environmental Sciences
1989-2005
Rocky Mountain Research (United States)
2004
Convergence in interspecific leaf trait relationships across diverse taxonomic groups and biomes would have important evolutionary ecological implications. Such convergence has been hypothesized to result from trade-offs that limit the combination of plant traits for any species. Here we address this issue by testing biome differences slope intercept among traits: longevity, net photosynthetic capacity (Amax), diffusive conductance (Gs), specific area (SLA), nitrogen (N) status, more than...
In the western United States vast acreages of land are exposed to low levels atmospheric nitrogen (N) deposition, with interspersed hotspots elevated N deposition downwind large, expanding metropolitan centers or large agricultural operations. Biological response studies in North America demonstrate that some aquatic and terrestrial plant microbial communities significantly altered by deposition. Greater productivity is counterbalanced biotic community changes deleterious effects on...
Significance Human activities have elevated nitrogen (N) deposition and there is evidence that impacts species diversity, but spatially extensive context-specific estimates of N loads at which losses begin remain elusive. Across a wide range climates, soil conditions, vegetation types in the United States, we found 24% >15,000 sites were susceptible to deposition-induced loss. Grasslands, shrublands, woodlands lower than forests, susceptibility increased acidic soils. These findings are...
Niche complementarity, in which coexisting species use different forms of a resource, has been widely invoked to explain some the most debated patterns ecology, including maintenance diversity and relationships between ecosystem function. However, classical models assume resource specialization form distinct niches, does not obviously apply broadly overlapping plant communities. Here we utilize an experimental framework based on competition theory test whether plants partition resources via...
Decomposition is a critical source of plant nutrients, and drives the largest flux terrestrial C to atmosphere. Decomposing soil organic matter typically contains litter from multiple species, yet we lack mechanistic understanding how species diversity influences decomposition processes. Here, show that N cycling during are controlled by composition chemical compounds within mixtures, rather than simple metrics diversity. We amended native soils with mixtures containing up 4 alpine used 9...
Many studies have shown that changes in nitrogen (N) availability affect primary productivity a variety of terrestrial systems, but less is known about the effects changing N cycle on soil organic matter (SOM) decomposition. We used techniques to examine chronic amendments SOM chemistry and microbial community structure function an alpine tundra soil. collected surface (0-5 cm) samples from five control long-term N-amended plots established maintained at Niwot Ridge Long-term Ecological...
Significance Accurate prediction of community responses to global change drivers (GCDs) is critical given the effects biodiversity on ecosystem services. There consensus that human activities are driving species extinctions at scale, but debate remains over whether GCDs systematically altering local communities worldwide. Across 105 experiments included 400 experimental manipulations, we found evidence for a lagged response herbaceous plant caused by shifts in identities and relative...
A nutrient amendment experiment was conducted for two growing seasons in alpine tundra communities to test the hypotheses that: (1) primary production is limited by availability, and (2) physiological developmental constraints act limit responses of plants from a nutrient—poor community more than nutrient—rich increases availability. Experimental treatments consisted N, P, N + P amendments applied plots physiognomically similar communities, dry wet meadows. Extractable soils nonfertilized...
Increases in the deposition of anthropogenic nitrogen (N) have been linked to several terrestrial ecological changes, including soil biogeochemistry, plant stress susceptibility, and community diversity. Recognizing need identify sensitive indicators biotic response N deposition, we empirically estimated critical load for changes alpine composition compared this with change. We also measured degree which vegetation may serve as a sink how much sequestration is related species composition....
The importance of interspecific competition as a cause resource partitioning among species has been widely assumed but rarely tested. Using neighbor removals in combination with 15N tracer additions the field, we examined variation three alpine uptake 15N-NH4+, 15N-NO3-, and 15N-13C-[2]-glycine intact neighborhoods, when paired specific neighbor, all neighbors were removed. Species varied capacity to take up 15N-labeled NH4+, NO3-, glycine neighborhoods pairs. When pairs compared no...
Biodiversity has been described as the diversity of life on earth within species, among and ecosystems. The rate biodiversity loss due to human activity in last 50 years more rapid than at any other time history, many drivers are increasing, including habitat loss, overexploitation, invasive climate change, pollution, pollution from reactive nitrogen (Nr). Of these stressors, change Nr anthropogenic activities causing some most changes. Climate is warming trends that result poleward...
The long-term (5-yr) responses of plant absolute abundance and species diversity to N, P, N+P fertilization were investigated in two sedge-dominated alpine communities that differed soil resource availability but not macroclimate: a resource-poor dry meadow more resource-rich wet meadow. Prior analysis, grouped into functional groups based on growth form, potential developmental constraints, presence or absence mutualisms. Absolute changes pronounced the dry-meadow community than wet-meadow...
Inorganic nitrogen concentrations in winter snow were measured on Niwot Ridge, Colorado, to estimate the potential inputs of this nutrient into an alpine ecosystem for support early season growt...
Abstract Interactions between climate and ecosystems with complex topographic gradients generate unique source sink habitats for water nutrients as a result of precipitation, energy, chemical redistribution. We examined these phenomena high-elevation site in the Colorado Front Range. Current changes atmospheric deposition nitrogen to systems are causing rapid some portions this system but not others. Using conceptual model that links terrestrial each other aquatic ecosystems, we report how...
One significant unanswered question about biotic responses to climate change is how plant communities within topographically complex landscapes will respond change. Alpine are strongly influenced by topographic microclimates which can either buffer or compound the effects of more regional climatic changes. Here, we analyzed species changes over 20+ years in a alpine landscape with pronounced gradients microtopography and consequently large variation temperatures, snow depths, nitrogen...