Assessment of Climate Change Impacts on a Wildlife Habitat Economically Important for Northerners

Activity Rationale

For thousands of years, wildlife has played a critical role in the economy and culture of northern communities. Balancing wildlife habitat conservation and industrial development under a changing climate is therefore one of the main issues in northern land use planning and governance. This activity provides earth observation information on changes to caribou and polar bear habitats to assist stakeholders and decision-makers in identifying climate change adaptation options.

Leader: Wenjun Chen

The Topic

Observational evidence shows that northern landscapes and habitats are changing. Several model simulations have suggested that, in this century, climate change could initiate substantial increases in the depth of soil that melts in the summer.  Such changes would have substantial impacts on the wildlife species and landscapes that the traditional economy, emerging eco-tourism sector, and infrastructure critical to northern development depend on.

This activity will enable stakeholders in the Canadian Wildlife Service, Parks Canada, the Government of the Northwest Territories, and other groups to assess the urgency of the issues and to identify adaptation options. Studies address climate change impacts on a critical habitat for caribou (the primary terrestrial wildlife source for local economy) and a key wildlife tourist site, Wapusk National Park (the “polar bear capital of the world").

Caribou heard near Wapusk National Park, July 2007 (photo courtesy of Wenjun Chen)

Climate change impacts on critical habitat for caribou

Two caribou habitats were selected as initial study areas from 2006 to 2011: the Porcupine caribou habitat in northern Yukon and Alaska, and the Bathurst caribou habitat located mainly in NWT with a portion of its calving ground in Nunavut and winter range in Manitoba.  The key research questions for the two caribou habitats are:

• Which areas of the two caribou habitats are most important for the caribou population?
• What changes have occurred and might occur under future climate change scenarios in the two caribou habitats?

The map above shows the locations of field measurement sites and the two caribou habitat study areas. Field measurements (including land cover type, aboveground biomass, foliage biomass, leaf area index, vegetation percent cover, wetland type, and permafrost active layer depth) were used to develop baseline maps. These maps were then used as a basis for detecting changes in habitat conditions using satellite remote sensing data.

Climate change impacts on polar bear habitat

A partnership between Natural Resources Canada and Parks Canada facilitates the monitoring of the ecological integrity of national parks. The Wapusk National Park, an important polar bear summer habitat, was selected as an initial study area. The key research questions for this polar bear habitat are:

• What is the present distribution of peat plateau and permafrost that is available for polar bear den sites in Wapusk National Park?
• What changes have occurred in the recent past and what might occur under future climate change scenarios in the polar bear habitat?

Baseline maps of the current status of caribou and polar bear habitats were developed using optical and radar satellite imagery (e.g. Landsat, SPOT, and RADARSAT) and permafrost process models. The models were calibrated and verified using field measurements.   Seasonal and long-term changes of caribou and polar bear habitats were assessed using time series of optical and radar satellite imagery, as well as ecosystem process models.

Results

Caribou habitat study

Lichens and mosses are the main winter diet of caribou and are common in mature woodland but largely absent from recently burned areas. Therefore, woodland area was used as a measure of caribou winter forage availability. In order to determine the extent of land cover types such as woodland, a baseline map was created from Landsat imagery. The baseline land cover map for the Bathurst caribou habitat is shown below.

Baseline map of land cover classification for the year 2000 over the Bathurst caribou habitat (derived from Landsat imagery).

Comparisons of land cover between 1990 and 2000 found a 35% reduction in woodland area within the winter range of the Bathurst caribou herd (right). Burned areas, which do not provide adequate habitat for caribou, covered 24085 km2 from 1990 to 2000. Statistical analyses revealed a correlation between burned areas and average June-September air temperatures within the winter range of the Bathurst caribou herd. This suggests that fires are more likely to occur when air temperatures are warmer.

For the summer range of the Bathurst caribou herd, relationships were found between average leaf nitrogen (N) concentration at peak growing times and the average growing season length. Leaf nitrogen concentration is commonly used as a measure of forage quality. The relationship between nitrogen concentration and growing season length for the summer range of the Bathurst caribou heard indicates that forage quality decreases as climate warms.

Polar bear habitat study

Frozen peat plateaus in Wapusk National Park host important habitat for polar bear summer den sites. Permafrost is sensitive to changes in climate, which poses a potential threat to polar bear habitat in the region. To assess the impacts of a changing climate on permafrost-bearing peat plateaus, maps of wetland types were developed to provide a baseline for observation (right).

The “active layer” of permafrost is the top portion of soil that thaws in the summer and freezes in the autumn. Terrain with a shallow active layer is more suitable for polar bear summer habitat because a greater profile of frozen ground is available for den sites. Measurements of the ground’s active layer were performed for different land cover types in Wapusk National Park.

Field measurements conducted in the summer of 2007 indicated that lichen bogs and burned bogs have the shallowest active layer thickness at roughly 40 cm, followed by sedge fens at about 85 cm, and shrub/treed fens at roughly 130 cm. Beach ridges have a very deep active layer. The graph below illustrates the measured differences in active layer thickness between the terrain types.

Bogs have a shallow active layer due to the insulating properties of peat, which is usually dry in the summer. Fens are wet, which enhance the depth of the summer thaw. Shrub fens and treed fens capture snow, which effectively prevents heat loss in the winter. Due to the sandy composition of the beach ridge, the ground can be quite warm in the summer with a deep active layer.

To test and validate the permafrost model, three sets of permafrost wells were installed in 2007/2008 to measure ground temperature. The wells are installed in a variety of wetland environments, notably fen and peat plateau. The orientation of the transect was designed to capture the climatic influence of Hudson’s Bay (see map, right). The figure below shows some initial results of these detail ground temperature measurements. With these measurements, we expect to further calibrate and improve the permafrost model as well as obtain better estimates of future conditions. The annual ground temperature record for monitoring sites closer to the Hudson Bay coast will be available in the fall of 2009.

Publications

Please note that subscriptions may be required to access some articles. To request a copy of publications, or for any more information, please contact Wenjun Chen.

• Check for more recent publications in GEOSCAN, the publications database of the Geological Survey of Canada and the Canada Centre for Remote Sensing.

Chen, W., Blain, D., Li, J., Fraser, R., Zhang, Y., Leblanc, S., Koehler, K., Olthof, I., Wang, J., and McGovern, M. 2008. Estimating carbon release caused by land use changes over Canada’s north during 1985-90 and 1990-2000 using satellite earth observation. Journal of Geophysical Research - Biogeosciences (in press).

Chen, W., Blain, D., Li, J., Fraser, R., Zhang, Y., Leblanc, S., Koehler, K., Olthof, I., Wang, J., and McGovern, M. 2008. Biomass measurements and relationships with Landsat-7/ETM+ and JERS-1/SAR data over Canada’s western sub-arctic and low arctic. International Journal of Remote Sensing (in press).

Chen, W., Li, J., Zhang, Y., Zhou, F., Koehler, K., Marriner, B.A., Leblanc, S., Fraser, R., Olthof, I., Zhang, Y., and Wang, J. 2008. Relating Biomass and Leaf Area Index to Non-destructive Measurements for Monitoring Changes in Arctic Vegetation. Arctic (submitted).

Chen, W., Zhang, Y., Cihlar, J., Smith, S.L., and Riseborough, D.W. 2003. Changes in soil temperature and active-layer thickness during the 20th century in a region in western Canada. Journal of Geophysical Research 108(D22), 4696, doi:10.1029/2002JD003355.

Li, J. and Chen W. 2005. A rule-based method for mapping Canada’s wetlands using optical, radar, and DEM data. International Journal of Remote Sensing 26(22): 5051 - 5069.

Li, J., Chen W., and Touzi, R. 2007. Optimum Radarsat-1 configurations for wetlands discrimination: a case study of the Mer Bleue peat bog, Canadian Journal of Remote Sensing 33 (S1): 46-55.

Olthof, I., and Fraser, R.H. 2007. Mapping northern land cover fractions using Landsat ETM+. Remote Sensing of Environment 107: 496-509.

Olthof, I., Pouliot, D., Latifovic, R., and Chen, W. 2007. Long-term northern vegetation changes from satellite data. Arctic (in press). 

Zhang, Y., Chen, W., and Riseborough, D.W. 2006. Temporal and spatial changes of permafrost in Canada since the end of the Little Ice Age. Journal of Geophysical Research 111, D22103, doi:10.1029/2006JD007284.

Zhang, Y., Chen, W., and Riseborough, D.W. 2008. Disequilibrium Response of Permafrost Thaw to Climate Warming in Canada over 1850-2100, Geophysical Research Letters 35, L02502, doi:10.1029/2007GL032117.

Zhang, Y., Chen, W., and Riseborough, D.W. 2008. Transient projections of permafrost distribution in Canada during the 21st century under scenarios of climate change. Global and Planetary Change 60: 443-456, doi:10.1016/j.gloplacha.2007.05.003.

Zhang, Y., Chen, W., and Riseborough, D.W. 2008. Modeling the long-term dynamics of snow and its impacts on permafrost in Canada. Proceedings of the 9th international conference on permafrost, Alaska (in press).

Zhang, Y., Chen, W., and Cihlar, J. 2003. A process-based model for quantifying the impact of climate change on permafrost thermal regimes. Journal of Geophysical Research 108(D22): 4695, doi:10.1029/2002JD003354.

Zhang, Y., Chen, W., Smith, S.L., Riseborough, D.W., and Cihlar, J. 2005. Soil temperature in Canada during the 20th century: complex responses to atmospheric climate change. Journal of Geophysical Research 110: D03112, doi:10.1029/2004JD004910.