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Fire in the Arctic Landscape Research and Site Description
The primary focus of this project is on comparative analysis of impacts and recovery along a gradient of burn severity within the AR burn perimeter, from unburned to severely burned plots, hillslopes, and watersheds including the streams and lakes within them. A second focus is on developing methods for evaluating the impacts of this very large burn at the scale of tens to hundreds of km2, i.e., the scale of mesoclimate models and the scale at which impacts on the whole Arctic region become important. Finally, we will evaluate changes in stream and lake chemistry, flow, and community composition as indicators of integrated impacts on large, burned watersheds.
To describe the impacts and early recovery of the AR burn we will concentrate on integrative measures of overall landscape, ecosystem, and community states rather than finely focused process and population studies. We cannot measure everything but will concentrate on the following:
- Standing stocks of organic matter, C, N and other elements:
- How much organic matter and other elements were lost in the burn itself and what is the fate of elements in ash?
- Which parts of the landscape incurred the greatest organic matter and element losses (e.g., uplands vs. lowlands, shrubby vs. graminoid vegetation)?
- How rapidly are organic matter and element stocks being replaced and in which landscape locations?
- Major fluxes of energy, carbon, water, and elements:
- How has the fire changed the surface energy balance of the landscape including heat flux into permafrost, sensible and latent heat exchange with the atmosphere, and seasonal soil thaw?
- What is the daily, seasonal, and annual pattern of Net Ecosystem CO2 Exchange (NEE) and its principal components, Gross primary Production (GPP) and Ecosystem Respiration (ER) in landscapes that differ in burn severity?
- Do landscapes of differing burn severity also differ in summertime stream flow and lake and stream nutrient loading?
- Do changes in lake nutrient and DOC loadings affect lake GPP and ER?
- Thermokarst development and impacts:
- Will thermokarst terrain increase in the burn area, leading to increased erosion, soil slumping, and losses of elements, sediment, and organic matter to streams and lakes?
- Can thermokarst formation be predicted from the interaction between burn severity and landscape characteristics (e.g. slope position, original vegetation community, presence of patterned ground)?
- What is the trajectory of revegetation and recovery of organic matter in areas affected by thermokarst failures?
- Community composition, and productivity:
- As the terrestrial vegetation recovers, how do its interactions with the land surface energy balance and permafrost thaw regime change?
- As the vegetation recovers, can we distinguish effects of species composition on surface energy balance, element cycling and turnover in burned sites?
- Are changes in aquatic productivity and community composition related to burn severity? Will changes in productivity and/or community composition lead to major changes in NEE or trace gas emissions of aquatic systems?
- Upscaling, remote sensing, and large-area measurements:
- Can we use or develop indices based on surface reflectance properties (like the vegetation “greenness” indices NDVI and EVI, and NBR, the normalized burn ratio) to extrapolate our results to larger areas?
- Can we measure the impacts of the burn directly on properties of the atmospheric boundary layer by sampling the atmosphere above the burn?
- Comparison with older (1993 and 1977) burned sites
- Are the changes that we see on the AR burn consistent with longer-term patterns of recovery on older burns on the North Slope?
- Is there any evidence, after 20 or 40+ years, that older burns are recovering to a relatively stable state of C, water, or surface energy exchange? Of vegetation composition and structure?
- Can we distinguish the older, burned tundras from surrounding, unburned tundra?
Where possible with the data to be collected we will take a budget-oriented approach to analyzing our results, comparing stocks, fluxes, and turnover rates at the ecosystem, hillslope, or catchment scale. These system-level measures are also the most directly relatable to coarse-scale properties of the larger Arctic System (climate, hydrology, biogeochemistry, geophysics) and to links between the land and the atmosphere and oceans. In many cases we can use models developed from research based at nearby Toolik Lake to structure these comparisons more formally. By combining new data from the AR fire with results of the extensive past research from Toolik Lake on tundra ecosystem and landscape processes, we can use these models to develop predictions of future change in the burned landscape---and compare those predictions with observations on older burned sites and with results of continued monitoring of the AR burn.