Climate change could have role in plant decline

Climate change could have role in plant decline

SELMA — A plant scientist following the footsteps of renowned plant ecologist Robert Whittaker 60 years after he studied the Klamath-Siskiyou region has found sharp population declines in the rare plants he studied.

"Basically, all the things that are most unique to this area have declined more than the things that are widespread," plant ecologist Susan Harrison told fellow scientists and others gathered at the Selma Center for the third Conference on Klamath-Siskiyou Ecology.

Harrison, a professor at the University of California, Davis, in the Department of Environmental Science and Policy, began studying the region in 2007 to try to determine how plants might be responding to changes in climate since Whittaker's time.

"Those species that are restricted to serpentine (soil) have declined more than the species that can be found on and off of serpentine soil," she said during her keynote speech on Thursday, the first day of the conference, which continues through Saturday. "On both soils, species that are close to their biogeographic range limit have declined more than species that aren't on their latitudinal range limits."

From 1949-51, Whittaker studied the plant community in the Klamath-Siskiyou mountains of southwest Oregon and northwest California. He sampled about 400 sites over three seasons.

Beginning in 2006, Harrison and Ellen Damschen, a plant scientist at Washington University in St. Louis, began studying Whittaker's records. They also followed his footsteps on the ground during the past two summers, visiting sites in the same general area, elevation, slope and soil type.

"Overall, we do think that plant communities have shifted in a direction consistent with a warmer climate," Harrison said, noting that plants are in more trouble on serpentine soil.

"We think there is reason to worry about serpentine adapted plants," she said. "If they are just as close to their limits of climatic tolerance as other plants, and they are trapped in these special soils, then they ought to be considered some of the highest priority candidates (for protection).

"If you want to have a big ark to save all the species at risk for climate change, these should be the ones to do something about," she added.

Whittaker, who became one of the most influential ecologists in the nation during the 20th century, was impressed with the rich diversity of plant life in the area.

"The region possesses a greater diversity of forest communities, in a more complex vegetation pattern, than any comparable area of the West," he wrote of the Klamath-Siskiyou range.

Six decades later, Harrison agrees with Whittaker's assessment.

"There are almost 100 species in the Klamath that are only found on serpentine soil," she said. "Even by worldwide standards, this is one of the most spectacular places for really cool, interesting narrowly distributed species."

The rich flora is the result of a combination of geography, geology, the unusual east-west orientation of the mountain range and the fact the region was not covered by glaciers during the ice ages, she said. Several species that thrive there, such as Brewer's spruce and the kalmiopsis, an evergreen flowering shrub, are found nowhere else on earth.

"There has been a significant upward trend in mean annual temperatures," she said, citing data from the National Weather Service office in Medford. Precipitation changes are tougher to analyze, given the region's location in relation to storm flow, but the climate appears to be getting drier, she said.

"From a plant's perspective, it has gotten warmer and it has effectively gotten drier," she said.

In an interview following her presentation, Harrison said the study will continue. It's too early to determine which species will benefit and which will suffer, she said.

"It you look at any one species, you don't really get a pattern," she said. "The only way you get a pattern is by looking at the whole.

"When you look at serpentine outcrops and the vegetation, they look like they haven't changed since the world was created," she added. "It's really kind of shocking to compare them with old data and realize there have been changes in this environment, changes that are just as big as people have found in other places in the world."

Reach reporter Paul Fattig at 776-4496 or e-mail him at

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