Study shows plants moved downhill, not up, in warming world

January 20, 2011
Data collected during the Wieslander vegetation survey in the 1920s and 1930s were used in the new climate study. (Marian Koshland Library, UC Berkeley archival photo)

( -- In a paper published today in the journal Science, a University of California, Davis, researcher and his co-authors challenge a widely held assumption that plants will move uphill in response to warmer temperatures.

Between 1930 and 2000, instead of colonizing to maintain a constant temperature, many California instead moved downhill an average of 260 feet, said Jonathan Greenberg, an assistant project scientist at the UC Davis Center for Spatial Technologies and Remote Sensing.

"While the climate warmed significantly in this period, there was also more precipitation. These wetter conditions are allowing plants to exist in warmer locations than they were previously capable of," Greenberg said.

Many forecasts say climate change will cause a number of and animals to migrate to new ranges or become extinct. That research has largely been based on the assumption that temperature is the dominant driver of species distributions. However, Greenberg said the new study reveals that other factors, such as precipitation, may be more important than temperature in defining the habitable range of these species.

The findings could have global relevance, because many locations north of 45 degrees latitude (which includes the northernmost United States, virtually all of Canada and Russia, and most of Europe) have had increased precipitation in the past century, and global climate models generally predict that trend will continue, the authors said.

"As we continue to improve our understanding of impacts on species, we will help land managers and policy makers to make more informed decisions on, for instance, conservation efforts for threatened and endangered species," Greenberg said.

He added that the study underlines the importance of an investment in basic science, as the results are based on historical data collected by the U.S. Forest Service in the 1930s, a program that was supported by New Deal spending after the .

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1 / 5 (1) Jan 20, 2011
why would they go higher where it's hotter and dry air?
3.7 / 5 (3) Jan 20, 2011
why would they go higher where it's hotter and dry air

If you look at high mountains, when you go higher in elevation the temperature gets colder. There is a point where the trees change from broad leaf to conifer and then a higher point where the trees thin out and then stop. Above that, there is only ground plants like grass and shrubs. If you go even higher, there is almost no vegitation at all, and even higher you'll find permanent ice caps. It was assumed that if you warm up the air, then those plants will all be able to grow at higher elevations because it's not as cold as it used to be.

This article doesn't really say whether the max elevation of the tree line changed or not. It says that the minimum elevations went lower, but it didn't say if the total area increased or decreased. I wonder which it was?
1 / 5 (1) Jan 21, 2011
I heard a different version of this story on NPR today.

The guy was saying that this study only applies to a part of northern California. He said that plants in other places ARE moving up hill and that this is a special case, which is why they are studying it. He said that the main conclusion for him is that it shows how different areas will respond differently to temperature changes, and that the old assumption that temperature is the biggest factor is wrong in at least this cases.
1 / 5 (1) Jan 21, 2011
I knew it would come to this. Now AGW means that mountains will become deserts, and cause trees to develop mobility. I saw it in my computer model.

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