A5011496401- Climate change and permafrost
- Cryospheric studies and observations
- Peatlands and Wetlands Ecology
- Geology and Paleoclimatology Research
- Plant Water Relations and Carbon Dynamics
- Atmospheric and Environmental Gas Dynamics
- Soil and Water Nutrient Dynamics
- Fire effects on ecosystems
- Structural Health Monitoring Techniques
- Plant responses to elevated CO2
- Indigenous Studies and Ecology
- Soil Carbon and Nitrogen Dynamics
- Marine and coastal ecosystems
- Ecology and Vegetation Dynamics Studies
- Soil and Unsaturated Flow
- Climate variability and models
- Non-Destructive Testing Techniques
- Isotope Analysis in Ecology
- Hydrology and Watershed Management Studies
- Advanced Control Systems Optimization
- Methane Hydrates and Related Phenomena
- Water Quality and Pollution Assessment
- Hydrocarbon exploration and reservoir analysis
- Nuclear and radioactivity studies
- Nuclear reactor physics and engineering
Marine Biological Laboratory
2009-2023
Nitrogen (N) and phosphorus (P) are tightly cycled in most terrestrial ecosystems, with plant uptake more than 10 times higher the rate of supply from deposition weathering. This near‐total dependence on recycled nutrients stoichiometric constraints resource use by plants microbes mean that two cycles have to be synchronized such ratio N:P uptake, litterfall, net mineralization nearly same. Disturbance can disrupt this synchronization if there is a disproportionate loss one nutrient relative...
We are developing a process-based modelling approach to investigate how carbon (C) storage of tundra across the entire Arctic will respond projected climate change. To implement approach, processes that least understood, and thus have most uncertainty, need be identified studied. In this paper, we key uncertainty by comparing responses C in tussock at one site between simulations two models - global-scale ecosystem model (Terrestrial Ecosystem Model, TEM) plot-scale (General GEM). The...
We describe a scaling protocol that combines two hierarchically linked models with field surveys, spatially distributed weather data, and remotely sensed images to generate daily predictions of gross primary production (GPP) for 9200-km2 arctic watershed. A detailed process-based model vegetation–atmosphere interactions, which has been tested in variety ecosystems against independent hourly gas exchange forms the base hierarchy. This was used construct second simpler, "big-leaf" model,...
Fire frequency has dramatically increased in the tundra of northern Alaska, USA, which major implications for carbon budget region and functioning these ecosystems, support important wildlife species. We investigated postfire succession plant soil (C), nitrogen (N), phosphorus (P) fluxes stocks along a burn severity gradient 2007 Anaktuvuk River fire scar Alaska. Modeling results indicated that early regrowth vegetation was limited primarily by its canopy photosynthetic potential, rather...
Abstract We use the Multiple Element Limitation (MEL) model to examine responses of 12 ecosystems elevated carbon dioxide (CO 2 ), warming, and 20% decreases or increases in precipitation. Ecosystems respond synergistically CO , decreased precipitation combined because higher water‐use efficiency with fertility warming compensate for drought. Response increased is additive. analyze changes ecosystem (C) based on four nitrogen (N) phosphorus (P) attribution factors: (1) total N P, (2) P...
We calibrated the Multiple Element Limitation (MEL) model to Alaskan arctic tundra simulate recovery of thermal erosion features (TEFs) caused by permafrost thaw and mass wasting. TEFs could significantly alter regional carbon (C) nutrient budgets because soils contain large stocks soil organic matter (SOM) are expected become more frequent as climate warms. simulated following TEF stabilization did not address initial, short‐term losses C nutrients during formation. To capture variability...
To investigate the underlying mechanisms that control long-term recovery of tundra carbon (C) and nutrients after fire, we employed Multiple Element Limitation (MEL) model to simulate 200-yr post-fire changes in biogeochemistry three sites along a burn severity gradient response increases air temperature, CO2 concentration, nitrogen (N) deposition, phosphorus (P) weathering rates. The simulations were conducted for severely burned, moderately unburned arctic tundra. Our indicated C balance...
Continuous time‐series estimates of net ecosystem carbon exchange (NEE) are routinely made using eddy covariance techniques. Identifying and compensating for errors in the NEE time series can be automated a signal processing filter like ensemble Kalman (EnKF). The EnKF compares each measurement to model prediction updates estimate by weighting relative specified error an model‐prediction that is continuously updated based on predictions earlier measurements series. Because among variables,...
The Marine Biological Laboratory General Ecosystem Model was calibrated for an arctic tussock tundra system using data from long‐term observations and experiments at Toolik Lake, Alaska. These include the effects of changes in temperature, light, CO 2 , nutrients, so model could be applied to five regions comprising entire Kuparuk River basin. Net primary production, averaged basin, 92 g C m −2 yr −1 . A 150 year simulation carbon storage under a doubling (slow ramp‐up) temperature increase...
Requirements for biomass carbon (C), nitrogen (N), and phosphorus (P) constrain organism growth are important agents structuring ecosystems. Arctic tundra habitats strongly nutrient limited as decomposition recycling of nutrients slowed by low temperature. Modeling interactions among these elemental cycles affords an opportunity to explore how disturbances such climate change might differentially affect cycles. Here we introduce a C–N–P-coupled version the Stoichiometrically Coupled...
We used a process‐based ecosystem model (Marine Biological Laboratory General Ecosystem Model (MBL‐GEM III)) to predict and analyze biogeochemical responses of Arctic tundra ecosystems past (1921–2000) future (2001–2100) changes in climate atmospheric CO 2 the Kuparuk River Basin, Alaska. first calibrated by deriving single parameter set that closely simulated response moist tussock decade‐long experimental manipulations nutrients, temperature, light, at Toolik Lake on North Slope then...
We develop a hierarchical approach to modeling organism acclimation changing availability of and requirements for substitutable interdependent resources. Substitutable resources are that fill the same metabolic or stoichiometric need organism. Interdependent whose acquisition expenditure tightly linked (e.g., light, CO2, water in photosynthesis associated transpiration). illustrate by simulating development vegetation with four sources N differ only cost their uptake assimilation. As...
Whole-ecosystem interactions and feedbacks constrain ecosystem responses to environmental change. The effects of these constraints on climate trends extreme weather events have been well studied. Here we examine how respond changes in day-to-day variability without changing the long-term mean weather. Although is recognized as a critical factor affecting ecological function, change resultant impacts function are still poorly understood. Changes can alter rates individual processes because...
Continuous time-series estimates of net ecosystem carbon exchange (NEE) are routinely made using eddy covariance techniques.Identifying and compensating for errors in the NEE time series can be automated a signal processing filter like ensemble Kalman (EnKF).The EnKF compares each measurement to model prediction updates estimate by weighting relative specified error an model-prediction that is continuously updated based on predictions earlier measurements series.Because among variables, also...