Continuous Foliar Cover of Vegetation for North American Beringia

Research, conservation, and effective natural resource management often depend on maps that characterize vegetation patterns. Quantitative and ecologically specific representations of vegetation pattern better represent observed vegetation patterns than do traditional categorical vegetation maps. They also avoid a human interpretational bias not necessarily shared by or important to plants or wildlife. We developed quantitative continuous foliar cover maps for 16 plant and lichen species or ecologically narrow aggregates in arctic and boreal Alaska and adjacent Yukon (North American Beringia). To provide context to the performance of our continuous foliar cover maps, we compared our results to the performances of three categorical vegetation maps that cover arctic and boreal Alaska: the National Land Cover Database, the coarse classes of the Alaska Vegetation and Wetland Composite, and the fine classes of the Alaska Vegetation and Wetland Composite. We integrated new and existing ground and aerial vegetation observations for arctic and boreal Alaska from three vegetation plots databases. To map patterns of foliar cover, we statistically associated observations of vegetation foliar cover with environmental, multi-season spectral, and surface texture covariates using a Bayesian statistical learning approach. Our maps predicted 33% to 67% of the observed variation in foliar cover per map class at a 10 × 10 m resolution, although the accuracy of each map varied between the Arctic, Southwest, and Interior subregions. We show that while some maps have high noise at the 10 × 10 m resolution, they generally capture vegetation patterns accurately at local to landscape scales. All continuous foliar cover maps performed substantially better than the categorical vegetation maps both for the entire region and for all subregions. The vegetation database and scripted workflow that we developed to create the continuous foliar cover maps will allow consistent future annual or semi-annual updates to include new observations of vegetation patterns and new covariate data. Our scripted workflow will also allow the application of our methods to different areas. Our continuous foliar cover maps extend knowledge of the functional role of vegetation in communities and wildlife habitat in North American Beringia beyond what has been previously available in categorical vegetation maps or quantitative maps of broadly defined vegetation aggregates.