Abstract
Glaciers are a prominent feature in high mountains and can affect plant distribution along the gradients. However, the possible effect of glaciers on plant community structure at landscape scale has been little studied. We asked: if a glacier tongue crosses a slope laterally and potentially blocks dispersal and migrations, how can this affect vegetation structure and species composition below and above this barrier? A suitable study system is offered by slopes on Mt. Kazbegi, where we established a transect through the subnival and nival belts. We sampled vegetation below and above the glacier tongue and conducted direct gradient analyses to reveal possible effects of the glacier on patterns of species distribution and vegetation structure such as the ratio of solitary plants in vegetation patches. The obtained results indicate that the glacier tongue in our study does not cause a ?vegetation switch? in the usual sense of this phrase. However, it might contribute to an abrupt change in the share of solitary plants, as well as to a very rapid decline of plant abundance and species numbers above the glacier.
Highlights
Throughout the world, glaciers are an important feature of cold landscapes, including high mountains (Pfeffer et al 2014)
As measured by the countable stems, decreased sharply with increasing elevation (Fig. 4). This decrease could be accurately modeled with an exponential equation, on both the north and south slopes, with high values of the determination coefficient (R2 < 0.95)
Came species that entered at middle elevations but dropped out again at higher elevations: Draba siliquosa and Eunomia rotundifolia on both northern and southern expositions, Senecio sosnowskyi on north slopes and Campanula ciliata, Colpodium versicolor, Nardus stricta and Sedum tenellum on south slopes (Tables 2 and 3)
Summary
Throughout the world, glaciers are an important feature of cold landscapes, including high mountains (Pfeffer et al 2014). Because glaciers are retreating owing to the ongoing climate warming, most current research is focused on the revegetation of glacier forelands (see Malanson et al 2020 for the latest contribution). Another line of research is focused on topographic heterogeneity created by existing or retreating glaciers to reveal important drivers of plant distribution at a rather microtopographic scale Glaciers and snow-covered areas often are excluded from
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