Forests not keeping pace with climate change: study

More than half of eastern U.S. tree species examined in a massive new Duke University-led study aren't adapting to climate change as quickly or consistently as predicted.

"Many models have suggested that trees will migrate rapidly to and elevations in response to warming temperatures, but evidence for a consistent, climate-driven northward is essentially absent in this large analysis," says James S. Clark, H.L. Blomquist Professor of Environment at Duke's Nicholas School of the Environment.

Nearly 59 percent of the species examined by Clark and his colleagues showed signs that their geographic ranges are contracting from both the north and south.

Fewer species -- only about 21 percent -- appeared to be shifting northward as predicted. About 16 percent seemed to be advancing southward, and around 4 percent appeared to be expanding in both directions.

The scientists analyzed data on 92 species in more than 43,000 forest plots in 31 states. They published their findings this month in the journal .

The study found no consistent evidence that population spread is greatest in areas where climate has changed the most; nor do the species' response patterns appear to be related to seed size or dispersal characteristics.

"Warm zones have shifted northward by up to 100 kilometers in some parts of the eastern United States, but our results do not inspire confidence that tree populations are tracking those changes," says Clark, who also holds appointments at Duke as a professor of biology and statistics. "This increases the risk of serious lags in tree migrations."

The concept of climate-driven migration is based on the assumption that as temperatures warm, the southern edge of some tree species' ranges could begin to erode as adult trees die and the seeds they leave behind in the soil can no longer sprout. At the same time, the species could spread to higher latitudes as seedlings dispersed on their northern boundaries are able to take root in newly favorable climates there.

To test whether this predicted response was occurring in real life, Clark and his colleagues pored through decades of data compiled by the U.S. Forest Service's Forest Inventory and Analysis Program. They compared the relative distributions of seedlings, saplings and adult trees of 92 widely distributed eastern U.S. species at 43,334 plots in 30 different longitudinal bands, and factored in things like seed characteristics, and changes in climate and precipitation.

"The patterns of tree responses we were able to document using this seedling-versus-tree analysis are more consistent with range contraction than with northward migration, although there are signs some species are shifting to higher elevations," Clark says.

The fact that the majority of the northernmost latitudes documented for was lower than those for adult trees of the same indicates "a lack of evidence for climate-mediated migration, and should increase concern for the risks posed by ," he says.

Explore further

Climate change predicted to drive trees northward

More information: "Failure to migrate: lack of tree range expansion in response to climate change," Kai Zhu, Christopher W. Woodall, James S. Clark. Global Change Biology, accepted article online. DOI: 10.1111/j.1365-2486.2011.02571.x
Provided by Duke University
Citation: Forests not keeping pace with climate change: study (2011, October 31) retrieved 19 August 2019 from
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Oct 31, 2011
Sad to hear that biodiversity survival rates is worse than we suspected.

Oct 31, 2011
Trees aren't moving to where climate alarmist say they should so the logical conclusion is that there is something wrong with the trees.

Nov 01, 2011
This may be due to the level of sarcasm employed, not the apparent decision to "lie".
I thought the "climate alarmist" comment would have given this away.

Nov 01, 2011

What motivates Sean W to tell such lies?

Most likely he is a member of the Tea Party Cult, as it seems most of the newer members are republican morons who belive Sarah Painintheass is some scientific mental Titan and probably the Messiah.

Nov 01, 2011
There have bee a couple of major tree migrations in my part of the country over the past 50 years. Dutch elm disease and the box elder bug have killed off major quantities of trees, which in turn have made room for resistant species. Neither had anything to do with climate or Tea parties.

Nov 01, 2011
Talking with some people I know in the Sierra Nevada mountains, they have noticed that the tree lines seem to at least be going up in elevation - if not in latitude.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more