Abstract Detail

Ecological Section

Beauregard, Frieda [1], deBlois, Sylvie [2].

Decreases in habitat availability at cold edge help explain range limits of temperate forest plants.

Overview: Climate has such a pervasive influence on various physical and biological processes in a landscape that it is often hard to identify its unique contribution to range limits. Climate affects plant distribution not only directly, but also indirectly through its influence on other factors that make a site more or less suitable for colonization. Here we compare patterns of site occupancy along a climate gradient including cold range limits to test for patterns consistent with hypotheses of indirect and direct cold limitation, dispersal limitation, and differing levels of negative biotic interactions. Study organisms: understory flowering plants, ferns and shrubs of the temperate and boreal forest biomes. Methods: We characterize species’ growing season niche shape using extended Huisman, Olff, Fresco models to define zones at the margin and toward the centre of this niche. We then construct generalized linear models within a Bayesian model averaging framework to determine non-climate habitat suitability, the frequency of these conditions in these two zones, and species occupancy patterns. Wilcoxon tests were also used independently to test for these occupancy and availability patterns. Results: We find that species are strongly influenced by indirect climatic variables (e.g. broadleaf cover, humus characteristics) through the changes in their availability across these distribution zones. We also find that 28 of our 37 study species have shifted to occupy sites with better drainage at their short growing season-range edges, which could be linked to earlier spring warming; as well for a few species, there was a shift to southern aspect slopes and lower elevations, also indicative of warm microclimates. Moreover, we find support for greater negative biotic interactions away from the short-growing season range edge via lower rates of suitable-site occupancy away from this edge. Synthesis: This study supports hypotheses of decreased habitat patch availability toward cold-range edges, of cold temperatures/short growing seasons on placing an absolute limit on range edge location, and of lower levels of biotic stress toward cold range-edges.

1 - McGill University, Plant Science, 21111 Lakeshore Road, Ste. Anne-de-Bellevue, QC, H9X 3V9, Canada
2 - McGill University, Plant Science and McGill School of Environment, 21111 Lakeshore Road, Ste. Anne-de-Bellevue, QC, H9X 3V9, Canada

Keywords:
Species distribution
Soil
microclimate
asymetric abiotic stress hypothesis
range limits
deciduous forest
native
native species
boreal forest.

Presentation Type: Oral Paper:Papers for Sections
Session: 68
Location: Salon 8/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 1:45 PM
Number: 68002
Abstract ID:310
Candidate for Awards:None