Back to the Future (BTF): Resampling Vegetation Plots to Assess 45 Years of Change in Arctic Plant Communities in Baffin Island, Canada

Arctic ecosystems are undergoing significant changes due to anthropogenically-induced climate warming. To determine the consequences of a changing climate, there is a need to better understand biotic responses that are occurring at various scales in the Arctic. In particular, plant communities are responding to these environmental changes with shifts in species abundance and diversity. Vegetation plays a key role in primary productivity, nutrient cycling, surface energy budget, and trophic interactions at all levels in the Arctic. This study focuses on documenting changes in arctic plant communities by re-sampling vegetation plots established in 1964 as part of a vegetation gradient analysis covering 200m2 of tundra in North-Central Baffin Island, Canada. Recently deglaciated, the landscape of Baffin is barren, with vegetation communities being discontinuous and concentrated in moist areas. Here we describe patterns of change within these communities. Seventy-nine plots were relocated and re-sampled in the summer of 2009. Sampling plots consist of a 1m x 10m belt, and vegetation cover for vascular and non-vascular species was assessed by visual estimation within a 1m x 10cm strip inside the belt. Hierarchical clustering using Sorensen distance measures and flexible beta linkage method (beta= -.25) of 1964 data revealed 10 different vegetation communities. A preliminary non-metric multidimensional scaling ordination using 1964 and 2009 data showed all vegetation communities shifting towards the same direction in theoretical space, except for one. Movement along axis one (net change = 3.9) suggests communities are becoming drier, while movement along axis 2 (net change = 2.5) may infer biomass has increased. Future work will involve assessing changes in species richness and diversity, as well as identifying key drivers and mechanisms of vegetation community change in the tundra. By evaluating these changes over decadal time scales, we can further understand how plant communities will behave in the future. This has important implications on how arctic terrestrial landscapes can alter the earth systems through biotic or abiotic feedback.