Scattered nature of Wisconsin's woodlands could complicate forests' response to climate change

Jul 14, 2008

If a warmer Wisconsin climate causes some northern tree species to disappear in the future, it's easy to imagine that southern species will just expand their range northward as soon as the conditions suit them.

The reality, though, may not be nearly so simple. A model developed by UW-Madison forest ecologists Robert Scheller and David Mladenoff suggests that while certain northern species, such as balsam fir, spruce and jack pine, are likely to decline as the state's climate warms, oaks, hickories and other southern Wisconsin trees will be slow to replace them.

Why? Not only is warming expected to outpace the speed at which southern trees can migrate northward, but barriers to dispersal — particularly agricultural lands — will also likely delay their progress, says Mladenoff.

"The result is that northern forest biomass in the future — that is, the standing amount of forest — could decrease, because the trees that are there now will be experiencing less than optimal conditions," he says. "And the southern species aren't going to fill in as quickly as we'd like." He and Scheller report their findings in the current issue of Climate Research.

Mladenoff explains that trees "move" into new areas by producing seeds, which are then carried over short distances by wind, birds or mammals. Under the right conditions, dispersed seeds then grow into seedlings and eventually mature trees, which produce their own seeds to start the process all over again.

Already a slow process, dispersal becomes even slower when forests are broken up by farmland and urban areas — or fragmented — like they are in Wisconsin. Not only is less suitable habitat available overall, but patches of it can also be widely scattered, making it tough for seeds to cross the gaps. In particular, Mladenoff points to the wide band of agricultural land that runs across the middle of the state as a major obstacle to the northward migration of southern trees.

To arrive at their conclusions, Scheller and Mladenoff fed current satellite classification and forest inventory data for a 1.5 million-hectare area of northwestern Wisconsin into a model, LANDIS-II, that's designed to predict how landscapes will respond to climate shifts. Using two well-established sets of future climate predictions, they then examined changes in parameters such as forest succession, seed dispersal and tree growth during the next 200 years.

In the face of the scientists' predictions, is there anything woodland managers can do now? Mladenoff cautions people not to make any drastic management changes. But one thing managers might begin to try is assisted migration: testing how certain southern Wisconsin species — or even different genetic stocks of the same species — do when planted up north on a trial basis. A prime candidate for experiments like this might be sugar maple, says Mladenoff, which is already widely distributed across Wisconsin and is projected to "do OK" on moist soils in the north when the climate warms.

The state might even consider bringing back the field trials that used to go on routinely in the 1950s and '60s, he says, in which researchers would collect genetic variants of individual tree species all over the state and then plant them in many locations to see where they did best. Although time-consuming, an approach like this could help ease some of the uncertainty we're facing now.

"A lot of this is about our incomplete knowledge of how genetically diverse some species are," Mladenoff says, "and how adaptable they may be in different climates."

Source: UW-Madison

Explore further: New research on Earth's carbon budget

add to favorites email to friend print save as pdf

Related Stories

Warming climate has consequences for Michigan's forests

Apr 11, 2014

In the last 100 years, Michigan has become warmer, with more rain coming through heavy downpours. Climate models suggest that the state will continue to warm and variability in precipitation patterns will ...

Recommended for you

New research on Earth's carbon budget

13 hours ago

(Phys.org) —Results from a research project involving scientists from the Desert Research Institute have generated new findings surrounding some of the unknowns of changes in climate and the degree to which ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

mikiwud
2.3 / 5 (3) Jul 15, 2008
Why not use the grant funds to explore the effects of the expected cooling on woodlands?
OH,I forgot,you would loose the grants if it is not related to warming!

More news stories

Magnitude-7.2 earthquake shakes Mexican capital

A powerful magnitude-7.2 earthquake shook central and southern Mexico on Friday, sending panicked people into the streets. Some walls cracked and fell, but there were no reports of major damage or casualties.

Impact glass stores biodata for millions of years

(Phys.org) —Bits of plant life encapsulated in molten glass by asteroid and comet impacts millions of years ago give geologists information about climate and life forms on the ancient Earth. Scientists ...

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...