A5027458310- Climate change and permafrost
- Peatlands and Wetlands Ecology
- Cryospheric studies and observations
- Geology and Paleoclimatology Research
- Soil Carbon and Nitrogen Dynamics
- Atmospheric and Environmental Gas Dynamics
- Plant Water Relations and Carbon Dynamics
- Botany and Plant Ecology Studies
- Turfgrass Adaptation and Management
- Lichen and fungal ecology
- Indigenous Studies and Ecology
- Ecology and Vegetation Dynamics Studies
- Methane Hydrates and Related Phenomena
- Fire effects on ecosystems
- Rangeland and Wildlife Management
- Polar Research and Ecology
- Climate variability and models
- Geological Studies and Exploration
- Coastal wetland ecosystem dynamics
- Tree-ring climate responses
- Soil and Water Nutrient Dynamics
- Smart Materials for Construction
- Plant responses to elevated CO2
- Plant Taxonomy and Phylogenetics
- Species Distribution and Climate Change
Marine Biological Laboratory
2015-2024
University of Alaska Fairbanks
2002-2016
University of Edinburgh
2006-2007
La Trobe University
2006
Pacific Northwest Research Station
2006
University of British Columbia
2006
Grand Valley State University
2006
University of Minnesota
2005
University of Copenhagen
1999
U.S. National Science Foundation
1998
We manipulated light, temperature, and nutrients in moist tussock tundra near Toolik Lake, Alaska to determine how global changes these parameters might affect community ecosystem processes. Some of manipulations altered nutrient availability, growth—form composition, net primary production, species richness less than a decade, indicating that arctic vegetation at this site is sensitive climatic change. In general, short—term (3—yr) responses were poor predictors longer term (9—yr)...
Recent observations of changes in some tundra ecosystems appear to be responses a warming climate. Several experimental studies have shown that plants and can respond strongly environmental change, including warming; however, most were limited single location short duration based on variety designs. In addition, comparisons among are difficult because techniques been used achieve different measurements assess responses. We metaanalysis plant community from standardized experiments at 11...
Ecology Letters (2011) Abstract Understanding the sensitivity of tundra vegetation to climate warming is critical forecasting future biodiversity and feedbacks climate. In situ experiments accelerate change on a small scale forecast responses local plant communities. Limitations this approach include apparent site‐specificity results uncertainty about power short‐term studies anticipate longer term change. We address these issues with synthesis 61 experimental studies, up 20 years duration,...
raise global mean temperature over the next century by 1.0–3.5 °C (Houghton et al. 1995, 1996). Ecologists from around world have begun experiments to investigate effects of warming on terrestrial ecosystems, aspect climate change that attracts most public attention (Woodwell and McKenzie Walker Steffen 1999). The effort understand response builds a history investigations elevated CO 2 plants ecosystems (Koch Mooney 1996, Schulze There are important differences, however, between increases in...
In undisturbed arctic tussock and wet meadow tundras we increased air temperature with a plastic greenhouse, nutrient availability by NPK fertilization, decreased light intensity shade cloth to determine the factors limiting growth of tundra plants. After 2 yr these manipulations measured each major vascular species one moss species. Each showed different pattern response alteration light, temperature, regimes, indicating that no single factor limits all in communities. Growth canopy (Betula...
We compared the effects of temperature on rates microbial respiration, N mineralization, nitrification, and P mineralization in soils from six arctic ecosystems located along a toposequence Alaska's North Slope. Soils these were incubated aerobically laboratory for 13 wk at temperatures representative field values during typical growing season. Rates C insensitive to between 3° 9°C but increased by factors 2 or more 9° 15°. For both N, differences among greater than due incubation within...
Abstract Shrub encroachment into grass‐dominated biomes is occurring globally due to a variety of anthropogenic activities, but the consequences for carbon (C) inputs, storage and cycling remain unclear. We studied eight North American graminoid‐dominated ecosystems invaded by shrubs, from arctic tundra Atlantic coastal dunes, quantify patterns controls C inputs via aboveground net primary production (ANPP). Across fourfold range in mean annual precipitation (MAP), key regulator ecosystem...
The fertilization responses of six tundra species belonging to three plant growth forms were compared test the hypothesis that same form are more similar one another than other in their response a controlled perturbation. perturbation was complete factorial NPK experiment tussock at Eagle Creek, Alaska, USA. We deciduous shrubs, evergreen and functionally graminoids terms mineral total nonstructural carbohydrate (TNC) concentrations, annual production per stem or tiller. Species differed...
ABSTRACT Our objective is to describe a multi‐layer model of C 3 ‐canopy processes that effectively simulates hourly CO 2 and latent energy ( LE ) fluxes in mixed deciduous Quercus‐Acer (oak–maple) stand central Massachusetts, USA. The key hypothesis governing the biological component stomatal conductance g s varied so daily carbon uptake per unit foliar nitrogen maximized within limitations canopy water availability. hydraulic system modelled as an analogue simple electrical circuits...
Primary production, plant biomass, element content, and various measures of turnover cycling were compared among four contrasting tundra vegetation types near Toolik Lake, Alaska. The study sites selected to represent extreme examples the wide variation in growth form composition that is typical northern ecosystems. aim research was determine whether differ their dominant also production: biomass relationships overall patterns use. included tussock tundra, a deciduous shrub—dominated...
Ecosystem responses to increased CO2 are often constrained by nutrient limitation. We present a model of multiple-element limitation (MEL) and use it analyze constraints imposed N on the an instantaneous doubling concentration in 350-yr-old eastern deciduous forest. examine effects different exchange rates inorganic with sources sinks external ecosystem (e.g., through deposition leaching) initial ratios net:gross mineralization. Both these factors influence availability vegetation and,...
Journal Article Global Change and the Carbon Balance of Arctic Ecosystems: Carbon/nutrient interactions should act as major constraints on changes in global terrestrial carbon cycling Get access Gaius R. Shaver, Shaver Search for other works by this author on: Oxford Academic Google Scholar W. D. Billings, Billings F. Stuart Chapin, III, III Anne E. Giblin, Giblin Knute J. Nadelhoffer, Nadelhoffer C. Oechel, Oechel B. Rastetter BioScience, Volume 42, Issue 6, June 1992, Pages 433–441,...
F.S. Chapin III, R.L. Jefferies, J.F. Reynolds, G.R. Shaver, and J. Svoboda, Arctic Plant Physiological Ecology: A Challenge for the Future. The System: B. Maxwell, Climate: Potential Change under Global Warming. D.L. Kane, L.D. Hinzman, M. Woo, K.R. Everett, Hydrology Climate Change. L.C. Bliss N.V. Matveyeva, Circumpolar Vegetation. W.D. Billings, Phytogeographic Evolutionary Flora Vegetation in a Changing Climate. K.M. Peterson, Succession, Competition, Constraints of Species Arctic....
Significance One of the greatest challenges in projecting future shifts global climate is understanding how soil respiration rates will change with warming. Multiple experimental warming studies have explored this response, but no consensus has been reached. Based on a synthesis 27 spanning nine biomes, we find that although increases rates, there limited evidence for shifting response We also note universal decline temperature sensitivity at temperatures >25 °C. Together, our data...
Abstract Global environmental change, related to climate change and the deposition of airborne N‐containing contaminants, has already resulted in shifts plant community composition among functional types Arctic temperate alpine regions. In this paper, we review how key ecosystem processes will be altered by these transformations, complex biological cascades feedbacks that might result, some potential broader consequences for earth system. Firstly, consider patterns growth allocation,...
Nitrogen and phosphorus pool sizes, distribution, cycling rates were described compared for six different ecosystem types occurring along a single toposequence in northern Alaska. The was located on series of old floodplains the Sagavanirktok River, foothills Brooks Range. From tussock tundra uplands, passed through relatively dry hilltop heath zone, hillslope shrub/lupine/Cassiope footslope Equisetum wet sedge tundra, riparian shrub zone. A late—melting snowbank covered site early June each...
Field manipulations of light, temperature, nutrients, and length growing season in directions simulating global environmental change altered biomass the four most abundant vascular plant species tussock tundra northern Alaska. These are Betula nana, Ledum palustre, Vaccinium vitis—idaea, Eriophorum vaginatum. Biomass response to our treatments reflected changes both growth mortality, with being stimulated by that enhanced biomass, mortality all (except Vaccinium). Those highest leaf stem...
Abstract Long‐term ecosystem‐level experiments, in which the environment is manipulated a controlled manner, are important tools to predict responses of ecosystem functioning and composition future global change. We present results meta‐analysis performed on long‐term experiments near Toolik Lake, Alaska, Abisko, Sweden. quantified aboveground biomass different arctic subarctic ecosystems experimental fertilization, warming shading. not only analysed general patterns but also differences...