Journal
GLOBAL CHANGE BIOLOGY
Volume 18, Issue 10, Pages 3202-3211Publisher
WILEY
DOI: 10.1111/j.1365-2486.2012.02769.x
Keywords
climate change; climate gradient; establishment; forest-tundra ecotone; Picea glauca; reproduction; seed quality; treeline; white spruce
Funding
- Canadian International Polar Year Program
- Natural Sciences and Engineering Research Council of Canada
- Northern Scientific Training Program (NSTP
- Aboriginal Affairs and Northern Development Canada)
- Research Council of Norway via the IPY [176065/S30]
Ask authors/readers for more resources
The northern boundary of boreal forest and the ranges of tree species are expected to shift northward in response to climate warming, which will result in a decrease in the albedo of areas currently covered by tundra vegetation, an increase in terrestrial carbon sequestration, and an alteration of biodiversity in the current Low Arctic. Central to the prediction of forest expansion is an increase in the reproductive capacity and establishment of individual trees. We assessed cone production, seed viability, and transplanted seedling success of Picea glauca (Moench.) Voss. (white spruce) in the early 1990s and again in the late 2000s at four forest stand sites and eight tree island sites (clonal populations beyond present treeline) in the Mackenzie Delta region of the Northwest Territories, Canada. Over the past 20years, average temperatures in this region have increased by 0.9 degrees C. This area has the northernmost forest-tundra ecotone in North America and is one of the few circumpolar regions where the northern limit of conifer trees reaches the Arctic Ocean. We found that cone production and seed viability did not change between the two periods of examination and that both variables decreased northward across the forest-tundra ecotone. Nevertheless, white spruce individuals at the northern limit of the forest-tundra ecotone produced viable seeds. Furthermore, transplanted seedlings were able to survive in the northernmost sites for 15years, but there were no signs of natural regeneration. These results indicate that if climatic conditions continue to ameliorate, reproductive output will likely increase, but seedling establishment and forest expansion within the forest-tundra of this region is unlikely to occur without the availability of suitable recruitment sites. Processes that affect the availability of recruitment sites are likely to be important elsewhere in the circumpolar ecotone, and should be incorporated into models and predictions of climate change and its effects on the northern forest-tundra ecotone.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available