Composition and spatial structure of plant communities on southeastern Victoria Island, arctic Canada

Abstract

We used multivariate methods to investigate the composition and spatial organisation of tundra plant communities in the Wellington Bay region of southeastern Victoria Island (69°N, 106°W). Ordination and classification of sites at an intermediate scale (≈ 1 ha) were conducted using principal components analysis and sums of squares agglomerative clustering on a matrix of standardized chord distances. The findings suggested eight vegetation classes. These communities are described floristically. At this spatial scale, the vegetation showed correspondence to elevation, slope, and thickness of soil, but not to aspect. The spatial patterns of multiple plant species and physical variables (i.e., slope of terrain and thickness of soil) were examined using multiscale ordination and double logarithmic regressions of variance on distance, respectively. Multiscale ordination revealed ever-increasing plant heterogeneity with distance (0.25 – 1600 m) and suggested only weak general patterns at scales ≤ 200 m. Similarly, variance in the physical factors tended to increase continually with distance. Both the vegetation and physical environment thus appeared to be organised on gradients. Key words: Arctic, classification, ordination, spatial scale, tundra.