Plant responses to natural and experimental variations in temperature in alpine tundra, southern Yukon, Canada

摘要

Substantial climate warming is predicted for high latitude regions and may have large impacts on tundra communities. As part of the International Tundra Experiment, this study characterized plant responses to natural and experimental variations in temperature at a subarctic, alpine tundra site. Non-destructive measures of plant reproduction and growth were monitored annually for four target species (Dryas octopetala, Lupinus arcticus, Polygonum viviparum, and Salix arctica) from 1999 to 2008. Plants were exposed to 8 years of an experimental warming treatment using open-topped chambers (OTCs). Temperatures in OTCs tended to be warmer at midday but cooler at night, with little net daily warming. OTCs had relatively little effect on plant responses, except for positive effects on reproductive characteristics of D. octopetala and P. viviparum. All target species except L. arcticus showed significant annual variations in vegetative and reproductive characteristics. Nondestructive measures used to monitor plant performance were significantly related to actual growth and reproductive output in most cases. Plant community composition did not show experimental effects nor were there consistent trends in composition over the 10 years of the study. Results of the study highlight individualistic species responses and the resilience of the plant community to observed temperature variations at this site.