The effects of observed and experimental climate change and permafrost disturbance on tundra vegetation in the western Canadian High Arctic
Bosquet, L.. 2011. M.Sc. Thesis. Dept. of Geography. Queen's University, Kingston, Ontario
Abstract
The response of vegetation to climate change and permafrost disturbance was
studied at the Cape Bounty Arctic Watershed Observatory (CBAWO) on Melville Island,
Nunavut. Climate change is expected to alter the terrestrial ecosystem of this area and
cause non-linear responses. This study focussed on two predicted outcomes of climate
change in the western Canadian High Arctic: the occurrence of a permafrost disturbance
termed active layer detachments (ALDs), and increased air temperature and precipitation.
To study the effects of ALD formation twenty 1 m
2
plots were established within
two ALDs. One ALD (ALD05) was formed in July 2007 and represented the initial
impact of slope failure caused by an exceptionally warm year. The other (ALD04) was
formed at least sixty years ago and represented the long-term impact of slope failure.
Physical soil measurements and vegetation surveys were completed in both disturbances.
ALD formation creates depressions on the landscape that increase snow
accumulation. Snow accumulation was greater in the more recent ALD than in the older
one and this resulted in greater changes to the physical environment. Vegetation was not
significantly impacted by disturbance, although phenology was delayed due to snowcover
retention.
To study the effects of increased air temperature and precipitation an International
Tundra Experiment (ITEX) site was established at CBAWO in July 2008. Snow fences
and open-top chambers (OTC) were erected to increase snow accumulation and air
temperature. Physical soil measurements and vegetation surveys were completed through
the summer of 2009. Soil temperature and active layer depth were affected by snow and
phenology was delayed in plots with snow enhancement. Experimental warming also had
some effects on the parameters measured but only in conjunction with snow
enhancement. This study found that in the first year of experimentation snow
enhancement has a greater effect than increased air temperature.
These studies represent the beginning of two long-term projects at CBAWO and
the results from this study represent baseline data for future research. Continued
monitoring will show the evolution of vegetation in the ALDs and the potential long-term
effects of temperature and snow manipulation.
