A5050147648- Climate change and permafrost
- Cryospheric studies and observations
- Peatlands and Wetlands Ecology
- Atmospheric and Environmental Gas Dynamics
- Geology and Paleoclimatology Research
- Plant Water Relations and Carbon Dynamics
- Methane Hydrates and Related Phenomena
- Indigenous Studies and Ecology
- Tree-ring climate responses
- Arctic and Antarctic ice dynamics
- Forest ecology and management
- Climate variability and models
- Atmospheric chemistry and aerosols
- Fire effects on ecosystems
- Urban Heat Island Mitigation
- Rangeland and Wildlife Management
- Ecology and Vegetation Dynamics Studies
- Polar Research and Ecology
- Isotope Analysis in Ecology
- Remote Sensing in Agriculture
- Plant Reproductive Biology
- Tree Root and Stability Studies
- Coastal wetland ecosystem dynamics
- Magnetic and Electromagnetic Effects
- Agroforestry and silvopastoral systems
University of Alaska Fairbanks
2016-2025
Princeton University
2016
University of Alaska System
2011
La Trobe University
2006
Pacific Northwest Research Station
2006
University of British Columbia
2006
Grand Valley State University
2006
Abisko Scientific Research Station
2006
Marine Biological Laboratory
1999-2002
University of California, Berkeley
1995-1996
Plant functional traits are the features (morphological, physiological, phenological) that represent ecological strategies and determine how plants respond to environmental factors, affect other trophic levels influence ecosystem properties. Variation in plant traits, trait syndromes, has proven useful for tackling many important questions at a range of scales, giving rise demand standardised ways measure ecologically meaningful traits. This line research been among most fruitful avenues...
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...
The International Tundra Experiment (ITEX) is a collaborative, multisite experiment using common temperature manipulation to examine variability in species response across climatic and geographic gradients of tundra ecosystems. ITEX was designed specifically arctic alpine increased temperature. We compiled from one four years experimental data 13 different sites used meta-analysis analyze responses plant phenology, growth, reproduction warming. Results indicate that key phenological events...
Abstract. The plant functional types (growth forms) traditionally recognized by arctic ecologists provide a useful framework for predicting vegetation responses to, and effects on, ecosystem processes. These are similar to those objectively defined cluster analysis based on traits expected influence Principal components showed that two major suites of (related growth rate woodiness) explain the grouping species into types. because they (1) many ecological processes (e.g. productivity,...
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...
Summary Tropical forests are globally important, but it is not clear whether biodiversity enhances carbon storage and sequestration in them. We tested this relationship focusing on components of functional trait as predictors. Data presented for three rain Bolivia, Brazil Costa Rica. Initial above‐ground biomass increments survivors, recruits survivors + (total) were estimated trees ≥10 cm d.b.h. 62 21 1.0‐ha plots, respectively. determined relationships to initial standing ( AGB i ),...
Abstract We used snow fences and small (1 m 2 ) open‐topped fiberglass chambers (OTCs) to study the effects of changes in winter cover summer air temperatures on arctic tundra. In 1994, two 60 long, 2.8 high fences, one moist other dry tundra, were erected at Toolik Lake, Alaska. OTCs paired with unwarmed plots, placed along each experimental gradient control areas adjacent snowdrifts. After 8 years, vegetation sites, including that had changed significantly. At both shrubs, live vegetation,...
The crucial role of biodiversity in the links between ecosystems and societies has been repeatedly highlighted both as source wellbeing a target human actions, but not all aspects are equally important to different ecosystem services. Similarly, social actors have perceptions access services, therefore, they wants capacities select directly or indirectly for particular characteristics. Their choices feed back onto services provided parties involved turn, affect future decisions. Despite this...
As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release offset by increased production Arctic boreal biomass; however, lack robust estimates net balance increases risk further overshooting international emissions targets. Precise empirical or model-based assessments critical factors driving are unlikely in near future, so address gap, we present from 98...
Abstract The Russian invasion of Ukraine hampers the ability to adequately describe conditions across Arctic, thus biasing view on Arctic change. Here we benchmark pan-Arctic representativeness largest high-latitude research station network, INTERACT, with or without stations. Excluding stations lowers markedly, some biases being same magnitude as expected shifts caused by climate change end century.
Abstract The Arctic–Boreal Zone is rapidly warming, impacting its large soil carbon stocks. Here we use a new compilation of terrestrial ecosystem CO 2 fluxes, geospatial datasets and random forest models to show that although the was overall an increasing sink from 2001 2020 (mean ± standard deviation in net exchange, −548 140 Tg C yr −1 ; trend, −14 P < 0.001), more than 30% region source. Tundra regions may have already started function on average as sources, demonstrating shift...
Fifteen years of N and P fertilizer addition to an Alaskan moist tundra increased aboveground biomass primary production by 2.5 times. Species composition the fertilized vegetation also changed dramatically, from a mix graminoid, evergreen, deciduous, moss species strong dominance single, deciduous shrub species, Betula nana. Analysis these simultaneous changes allows insights into interactions between in resource availability regulating biomass, production, element use. By 15th year (1995),...
We investigated how three co-dominant arctic shrubs (Betula nana, Salix pulchra, and Ledum palustre ssp. decumbens) responded to long-term treatment with N+P fertilizers greenhouses in a factorial field experiment at Toolik Lake, Alaska. Our goal was understand the relationship between growth of individuals species abundance community, mechanism by which one achieves dominance under changed environmental conditions. compared aboveground allocation patterns individual ramets 15 yr age...
Understanding the carbon dioxide and water fluxes in Arctic is essential for accurate assessment prediction of responses these ecosystems to climate change. In Arctic, there have been relatively few studies net CO 2 , water, energy exchange using micrometeorological methods due difficulty performing measurements cold, remote regions. When are performed, they usually collected only during short summer growing season. We established eddy covariance flux towers three representative Alaska...
The rapidly warming temperatures in high-latitude and alpine regions have the potential to alter phenology of Arctic plants, affecting processes ranging from food webs ecosystem trace gas fluxes. International Tundra Experiment (ITEX) was initiated 1990 evaluate effects expected rapid changes temperature on tundra plant phenology, growth community using experimental warming. Here, we used ITEX control data test phenological responses background variation across sites spanning latitudinal...
Fire causes dramatic short-term changes in vegetation and ecosystem function, may promote rapid change by creating recruitment opportunities. Climate warming likely will increase the frequency of wildfire Arctic, where it is not common now. In 2007, unusually severe Anaktuvuk River fire burned 1039 km(2) tundra on Alaska's North Slope. Four years later, we harvested plant biomass soils across a gradient burn severity, to assess recovery. areas, above-ground net primary productivity vascular...
Bidirectional Reflectance Distribution Function (BRDF) model parameters, Albedo quantities, and Nadir BRDF Adjusted (NBAR) products derived from the Visible Infrared Imaging Radiometer Suite (VIIRS), on Suomi-NPP (National Polar-orbiting Partnership) satellite are evaluated with spatially representative in situ tower albedometer measurements through comparison MODerate Resolution Spectroradiometer (MODIS) long term record. White Sky (WSA), Black (BSA), NBAR, Quality Assurance (QA) results...
Abstract The lack of a standardized database eddy covariance observations has been an obstacle for data‐driven estimation terrestrial CO 2 fluxes in Asia. In this study, we developed such using 54 sites from various databases by applying consistent postprocessing gross primary productivity (GPP) and net ecosystem exchange (NEE). Data‐driven was conducted machine learning algorithm: support vector regression (SVR), with remote sensing data 2000 to 2015 period. Site‐level evaluation the...
Climate warming in arctic tundra may shift dominant vegetation from graminoids to deciduous shrubs, whose functional traits could, turn, alter biotic and abiotic controls over biogeochemical cycling of carbon (C) nitrogen (N). We investigated whether shrub-induced changes microclimate have stronger effects on litter decomposition nutrient release than quality quantity. In near Toolik Lake, Alaska, USA, we incubated a common substrate snow-addition experiment test snow accumulation around...
Abstract. Past efforts to synthesize and quantify the magnitude change in carbon dioxide (CO2) fluxes terrestrial ecosystems across rapidly warming Arctic–boreal zone (ABZ) have provided valuable information but were limited their geographical temporal coverage. Furthermore, these been based on data aggregated over varying time periods, often with only minimal site ancillary data, thus limiting potential be used large-scale budget assessments. To bridge gaps, we developed a standardized...