Permafrost collapse affects peatland ecosystem

Permafrost, the frozen foundation of North America isnt that permanent anymore, a team of scientists from the Michigan State University, Southern Illinois University, Villanova University and the National Renewable Energy Laboratory, have found.

Washington, Aug 19 : Permafrost, the frozen foundation of North America isn't that permanent anymore, a team of scientists from the Michigan State University, Southern Illinois University, Villanova University and the National Renewable Energy Laboratory, have found.

Permafrost serves as a platform underneath vast expanses of northern forests and wetlands in many northern ecosystems. But rising atmospheric temperatures are accelerating rates of permafrost thaw in northern regions.

In their study appearing in last week's online edition of Global Change Biology, MSU researcher Merritt Turetsky and her team explored whether melting permafrost could lead to a viscous feedback of carbon exchange that actually fuels future climate change.

The team found that permafrost degradation has complex impacts on greenhouse gas fluxes from northern wetlands.

"The loss of permafrost usually means the loss of terra firma in an otherwise often boggy landscape. Roads, buildings and whole communities will have to cope with this aspect of climate change. What this means for ecosystems and humans residing in the North remains of the most pressing issues in the climate change arena," said Turetsky, assistant professor of crop and soil sciences and fisheries and wildlife in MSU.

The study focused on peatlands, a common type of wetland in boreal regions that slowly accumulates peat, which is an accumulation of partially decayed vegetation.

Today, peatlands represent a massive reservoir of stockpiled carbon that accumulated from the atmosphere over many thousands of years. Peat blankets the permafrost and protects it like a thick layer of insulation.

"We find permafrost in peatlands further south than in other boreal ecosystems due to the insulating qualities of peat .So we have argued that these ecosystems serve as a very sensitive indicator of climate change," said Prof. Turetsky.

"What will happen to peatlands when climate change disrupts these frozen layers, or perhaps more importantly what will happen to all of that stored carbon in peat, have remained big questions for us," she said.

Findings revealed that Permafrost collapse in peatlands tended to result in the slumping of the soil surface and flooding, followed by a complete change in vegetation, soil structure, and many other important aspects of these ecosystems.

Prof. Turetsky said they were quite surprised by the results, as initially they had expected to find that the melting ice would trigger a release of greenhouse gases to the atmosphere, with previously frozen plant and animal remains becoming susceptible to decay.

"This could serve as a positive feedback to climate change, where typically warming causes changes that release more greenhouse gases, which in turn causes more warming, and more emissions, and so on," said Prof. Turetsky.

"The study showed that vegetation responded to the flooding with a boost in productivity. More vegetation sequesters more carbon away from the atmosphere in plant biomass. This is actually good news from a greenhouse gas perspective," she added.

Prof. Turetsky said it seemed now that permafrost degradation initially causes increased soil carbon sequestration, rather than the large release of carbon to the atmosphere originally predicted, but over time high methane emissions will balance - or outweigh - the reduction of carbon in the atmosphere.

"Not all ecosystems underlain by permafrost will respond the same way. It will depend on the history of the permafrost and the nature of both vegetation and soils. What is clear is that not even northern ecosystems can escape the wide reach of climate change," she added.

ANI