Proglacial succession of biological soil crusts and vascular plants: Biotic interactions in the High Arctic

Breen K. & Lévesque E.
Canadian Journal of Botany
84 :1714-1731
To evaluate the hypothesis that biological soil crusts facilitate the establishment and maintenance of vascular plants during succession, we studied the distribution patterns of crusts and vascular plants along a High Arctic glacier fore- land and compared the success of plants growing in and out of crusted substrate. Multivariate analyses determined that dis- tance from the glacier and crust cover were the most important variables, explaining 11% and 9% of the variance in the vegetation data, respectively. Surfaces colonized by biological soil crusts generally supported higher plant densities and showed positive associations with the most dominant, long-lived plant species such as Saxifraga oppositifolia L., Salix arc- tica Pall., and Dryas integrifolia Vahl. Crusts facilitate plant establishment and growth in early and midsuccession but may compete for available resources further along the chronosequence. This study recognizes subtle direct influences of crust on vegetation density but also draws attention to a much larger overall positive effect on community structure. Suc- cession on this foreland proceeds via a ‘‘directional-replacement’’ model and supports a well-developed community of bio- logical soil crusts and vascular plants with greater species richness, cover, and density compared with other glacier foreland vegetation communities previously investigated on Ellesmere Island, Nunavut. Arctic, biological soil crusts, plants, succession, facilitation, glacier retreat.
Thursday, 23 February 2023 10:20