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

Abstract

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 foreland and compared the success of plants growing in and out of crusted substrate. Multivariate analyses determined that distance 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 arctica 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. Succession on this foreland proceeds via a “directional-replacement” model and supports a well-developed community of biological 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.

Regeneration of Little Ice Age bryophytes emerging from a polar glacier with implications of totipotency in extreme environments

“…[13][14][15]. Since the 1960s, numerous field studies have also reported emergent subglacial vegetation; however, all have concluded that the exhumed material was dead (4,5,(16)(17)(18). Here, we present unique field and experimental evidence for the regeneration of subglacial populations of LIA bryophytes collected from the margin of the retreating Teardrop Glacier, and address the important biological implications for polar environments.…”

“…1B). Within the trimline, the vegetation includes both a chronosequence of recolonizing plants and exhumed, intact assemblages of vascular plants and bryophytes (4)(5)(6). The subfossil bryophyte assemblages are in pristine condition, resulting from prior entombment by a nonerosive, cold-based glacier margin, common at high latitudes (7).…”

“…However, the bryophyte record has not been the focus of a systematic study (4)(5)(6)(19)(20)(21)(22). In high arctic environments the bryophyte flora is comprised of mosses and hepatics, lacking hornworts.…”

Dynamics of bacterial community succession in a salt marsh chronosequence: evidences for temporal niche partitioning

“…In particular, studies on the long-term changes in macro-organismal diversity have been instrumental in helping ecologists to establish a framework to understand and model successional dynamics (Lockwood et al, 1997;Chase, 2003). For such studies, the use of chronosequences, which assume a space-for-time substitution, despite a few criticisms (for a review see Johnson and Miyanishi, 2008), has offered unique opportunities to investigate soil macro-community development across multiple time scales, in some cases spanning over hundreds of years of (ordered) temporal changes (Bormann and Sidle, 1990;Breen and Lévesque, 2006; reviewed in detail by Walker et al, 2010).…”

Nitrogen fixation by associative cyanobacteria in the Canadian Arctic.

“…Few studies have focussed on the functional role of BSCs; however, there is accumulating evidence that BSCs play an important role in both the development and maintenance of vascular plant communities in arctic environments (Breen & Levesque, 2006;Gold et al, 2001). BSCs tend to increase the N content, as well as, the uptake of Cu, K, Mg and Zn of associated seed plants (Belnap & Harper, 1995;Harper & Belnap, 2001).…”