Alpine plant responses to natural temperature variation and experimental warming treatments in southern Yukon
Year: 2009
Type: dissertation
Abstract: Global climate models predict that the current trend of warming in the Arctic will continue over the next century.The productivity of arctic plants is often limited by short growing seasons with relatively low temperatures such that a warmer climate could have large impacts on plants and plant communities.This study characterised alpine plant responses to changes in temperature at an alpine tundra site near Whitehorse, Yukon, Canada.I examined relationships between plant productivity and natural temperature variations and assessed responses of plants exposed to an experimental warming treatment.Non-destructive measurements of reproductive and growth characteristics of four target species (Dryas octopetala, Lupinus arcticus, Polygonum viviparum, and Salix arctica) were taken annually from 1999 to 2008.There was no significant effect of the warming treatment (OTCs) on average daily mean temperatures as midday warming of up to 1.4 °C was largely offset by night time cooling in the OTCs.Vegetative measurements of target species showed no significant responses to OTC treatments.However, peduncles of D. octopetala and sections of P. viviparum inflorescences that produced bulbils were an average of 34.6 % and 64.7 % longer in OTCs than in controls, respectively.These treatment responses were likely due to plants responding to a factor other than temperature that was modified by the chamber.One vegetative and five reproductive characteristics were significantly related to annual variation in temperature.The summer of 2004 was exceptionally hot, and some species that did not respond to smaller fluctuations in temperature showed large changes in growth or reproduction in this year, perhaps indicating a non-linear response to temperature.Among the larger responses to the warm summer of 2004 was a shift in P. viviparum allocation from predominantly asexual to sexual means of reproduction.Measurements of plant community composition assessed at five-year intervals showed no differences in community composition between experimental plots and controls, and changes in composition over the study period were iii not uni-directional.In general, both individual plants and community composition were highly resilient to observed variation in summer temperatures.Other factors, such as nutrient availability, may be more important in determining plant responses to environmental change at this site than the direct effects of summer temperature variation.scientist.I have learned more in these past few years than I would have thought possible and I primarily have her to thank for it.Jill gave me enough rope to try things out on my own and develop my own ideas while still making sure I was not going to stray too far.This project was initiated in 1998 by researchers from the Yukon Territorial Government Department of Environment and Environment Canada in Whitehorse.I would like to thank Val Loewen, Mike Gill, Jennifer Staniforth, and Michael Svoboda for their on-going work on this project, help in the field, and for kindly answering my persistent questions.I would further like to thank Val for putting me up in Whitehorse on more than one occasion.I would also like to acknowledge the many people from the Yukon
Author: Sara J. Pieper
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2160318838