Ottawa — Lakes and wetlands in the Kenai Peninsula of south-central Alaska are drying at a significant rate. The shift seems to be driven by climate change, and could endanger waterfowl habitats and hasten the spread of wildfires.
In a paper published in the August 2005 issue of the NRC Research Press’ Canadian Journal of Forest Research, Eric Klein and his colleagues document a significant landscape shift from wetlands to woodland and forest in the Kenai Peninsula Lowlands.
The trend fits within a global picture of drying wetlands in northern latitudes, with similar changes already appearing in lower latitudes. Klein, a biologist who did his graduate research with Alaska Pacific University, says the transformation of Alaska’s landscape corresponds with an increase in temperatures over the past 100 years. “When you look at the climatologic data, it shows a warming trend. This is just one of the physical manifestations of that trend that is hard to refute.”
The researchers compared aerial photos of the Kenai Peninsula taken in 1950 and 1996. Combined with extensive field study and analysis of vegetation, the research confirms that the Kenai Peninsula is becoming woodier and dryer. In the areas studied, wooded areas increased from 57 percent to 73 percent from 1950 to 1996, while wetland areas decreased from 5 percent to 1 percent.
The results confirm what the researchers could see for themselves. “It’s very clear when you fly over closed basin lakes, many of which are the kettle ponds left after the glaciers receded,” says Klein. “They have a kind of apron, or area between the water and mature forest, and you can see it getting larger as the water goes down.”
Global temperatures have increased by about 0.6°C over the past 100 years. The rate of temperature increase from 1976 to the present has been double that from 1910 to 1945 — greater than at any other time during the last 1,000 years.
Over the past 30 years, temperatures in the Kenai Peninsula have increased 0.7°C. In the last 15 to 25 years, species such as dwarf birch, blueberries and black spruce have grown up in areas where wetlands had existed for 8,000 to 12,000 years. “These areas used to be soggy bogs with sphagnum peat moss, and no shrubs or trees,” says Dr. Ed Berg, an ecologist with the U.S. Fish and Wildlife Service. “The evidence for this is that when you dig down into the peat, you don’t see any stems or shrubs. Had they grown there in the past, they would have been preserved because peat preserves things very well.”
Wetlands are hotspots for biodiversity. The shift to woodland and forest means loss of many types of wetland vegetation and fewer habitats for migratory birds. The greater forest cover also creates a continuous swath of vegetation that helps wildfires to spread more quickly.
Similar drying is happening outside the Kenai Peninsula. “It’s certainly happening in Alaska on a very broad scale,” says Dr. Berg. “Much of the interior is showing the same kind of drying pattern.”
If the warming trend continues, Alaska’s lakes and wetlands will continue to disappear, creating a dryer landscape in the long term.
Klein says that Alaska’s transformation is another piece of evidence in the climate change puzzle. “The bottom line is that a change is happening,” he says. “There is an overall environment shift occurring in Alaska, and especially in the northern hemisphere. I think it’s a bioindicator of climate change and what is happening to the planet as awhole.”