Fens May Provide Refuge as Climate Changes

When people talk about how global warming will affect the Adirondacks, the discussion often focuses on the mountains. Plants and animals at the top of the topography have no escape route as the temperature rises and warmth-tolerant species move upslope.

But what about the bottom of the topography? Many of the northern, cold-loving plants found on the summits of the High Peaks are also found in Adirondack fens, wetlands that resemble bogs but are fed by groundwater instead of rainwater.

Air temperature fluctuates throughout the day, the season or the year, but groundwater temperature remains stable. Fens may provide a refuge for boreal species as conditions above get hotter.

Patrick Raney, a wetlands planner and doctoral candidate at SUNY College of Environmental Science and Forestry, in Syracuse, is monitoring 300 temperature sensors he recently placed in the saturated soils of fens around New York State, including six sites in the Adirondacks.

“Historically, as the glaciers retreated, species would have had thousands of years to migrate along with the appropriate climate,” Raney says. “But because things are changing so rapidly, if you lose a bunch of boreal or other species at the southern range of their distribution, there are not going to be a ton of species coming behind to replace them on the same pace because climate is changing so quickly. Species just physically can’t migrate that fast.

“Understanding these locations where there are pockets where species are less vulnerable is a pretty important tool for conservation.”

The temperature of groundwater is generally equal to the mean air temperature directly above. It stays within a narrow range year-round.

“There is a whole lot of mass to warm up of saturated and solid materials,” Raney explains. “I think over a long-term period, soils will eventually start to warm up but it’s going to be a much slower process than changes in air temperature.”

Scientists have used climate models to predict that Adirondack air temperatures are currently on pace to warm 6 to 11°F by the end of this century. The models don’t scale down to smaller features in the landscape.

“There’s a lot of detail missing from those models related to wetlands. They’ve been ignored,” Raney says.

“One-third of species on endangered species lists depend on wetlands at least a portion of their life. So, if we are going to develop these big models and try to assess how vulnerable biodiversity is to climate change, if we are not going in and measuring things pertinent to wetlands then we are really missing a lot.”

Raney is currently preparing a paper on the project to submit to a scientific journal.

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