Local topography is more important than climate as a determinant of regional alpine plant diversity in southwestern British Columbia
Date
2012-09-04
Authors
Baldwin-Corriveau, Katharine
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Abstract
Mountain ecosystems are considered highly sensitive to the impacts of climate change,
and are experiencing a magnitude of change that far exceeds global averages, particularly
with respect to increases in average temperature and precipitation. As such, scientists are
predicting a rapid habitat reduction or even the loss of the coolest climatic alpine zones,
thus threatening the continued survival of high elevation specialists. However, many of
these ‘doomsday’ predictions are based primarily on models with coarse-resolution
changes to atmospheric climate parameters, and do not take into account the potential
buffering effects of other environmental gradients known to structure alpine plant
communities, related to topography and soils. To assess the accuracy of predictions
regarding the state of vulnerability of alpine plant communities to climate change, this
thesis examined the relative importance of climate, topography and soils as determinants
of regional alpine plant diversity for all species, as well as for forbs, graminoids and
woody species separately, in alpine meadows of southwestern British Columbia. Through
redundancy analyses and variation partitioning, results show that topography and soils are
more important than climate as determinants of regional alpine plant diversity. Within
these groups, elevation, slope, soil moisture and mean summer temperature were most
significant. Interestingly, precipitation played only a small role, even though the study
area spanned a precipitation gradient of over 1200 mm/year. The stronger influence of
temperature, especially for woody species beta diversity, supports findings of shrub
expansion in arctic-alpine systems. The lower importance of climate as a determinant of
regional alpine plant diversity, especially for forbs, the dominant life form in alpine
meadow ecosystems, suggests that these productive environments may be more resilient
to on-going changes in atmospheric climate conditions than previously believed.
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Keywords
community ecology, plant ecology, species diversity, determinants of diversity, climate change