The Alaska Arctic Vegetation Archive (AVA-AK, GIVD-ID: NA-US-014) is a free, publically available database archive of vegetation-plot data from the Arctic tundra region of northern Alaska.The archive currently contains 24 datasets with 3,026 non-overlapping plots.Of these, 74% have geolocation data with 25-m or better precision.Species cover data and header data are stored in a Turboveg database.A standardized Pan Arctic Species List provides a consistent nomenclature for vascular plants, bryophytes, and lichens in the archive.A web-based online Alaska Arctic Geoecological Atlas (AGA-AK) allows viewing and downloading the species data in a variety of formats, and provides access to a wide variety of ancillary data.We conducted a preliminary cluster analysis of the first 16 datasets (1,613 plots) to examine how the spectrum of derived clusters is related to the suite of datasets, habitat types, and environmental gradients.We present the contents of the archive, assess its strengths and weaknesses, and provide three supplementary files that include the data dictionary, a list of habitat types, an overview of the datasets, and details of the cluster analysis.
In this NASA ABoVE-funded project, we combine geospatial data products derived from airborne and spaceborne remote sensing (RS) data with targeted field observations and modeling in order to quantify ecosystem responses to Arctic and boreal environmental change. Specifically, we quantify methane (CH4) ebullition (bubbling) emissions associated with 60 years of permafrost thaw in thousands of Alaskan and NW Canadian lakes by direct observation with RS systems.
To achieve our goals, we have developed statistically-significant models that are using SAR, optical and infrared RS data in order to detect and quantify CH4 ebullition emissions at intra-, whole- and regional-lake scales. We also established a relationship between observed CH4 ebullition and average annual soil organic carbon (SOC) inputs to a handful of Alaskan lakes via thermokarst-margin expansion during recent decades using field data, radiocarbon dating and modeling.
Our paper we will provide an overview of the goals, datasets, and methods used for the various components of this project. We will present on (1) the collection of new and synthesis of existing field data on CH4 ebullition, thaw-bulbs and SOC; (2) the analysis of existing data from aerial surveys, SAR and optical RS of CH4 in lake ice; (3) the orthorectification of historic aerial photos for comparison to high-resolution satellite imagery to produce fine-scale regional maps of lake area change, (4) the modelling of permafrost SOC quantities eroded into lakes; (5) the radiocarbon dating of CH4 and SOC, (6) GIS modeling to produce multi-temporal regional maps of historic lake area change, associated CH4 emissions, and permafrost SOC stocks; and (7) outreach to stakeholders at Alaska village and rural community field sites. To demonstrate the scientific relevance of our work we will also showcase a set of research results that we have been able to achieve so far. These will include (1) first regional-scale RS-based estimates of lake-borne CH4 ebullition emissions; (2) regional scale estimates of lake area change from an analysis of 50 years of remote sensing data; and (3) regression models linking lake area change to CH4 emissions.
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