An analysis by the Environmental Protection Agency found temperatures rising an average of 1 to 4 degrees Fahrenheit in Missouri and Arkansas during the summer and 1 to 7 degrees in winter.

“If conditions become drier, the current range and density of forests could be reduced and replaced by grasslands and pastures,” the EPA report on Missouri noted. “Even a warmer and wetter climate could lead to changes; trees that are better adapted to warmer climates, such as (some) oaks and southern pines, would prevail. Under these conditions, forests could become more dense.”

“These changes could occur during the lifetime of today’s children,” the EPA report on Missouri concluded, noting that fire, pests and disease could accelerate changes.

In Arkansas, not only would southern pine forests advance northward, but scrub timber and noncommercial varieties of oaks would also expand their range, noted the EPA.

A third analysis, this one in 2006 by Jacqueline Mohan, then a scientist with the Marine Biological Laboratory at Woods Hole, Mass., noted that rising carbon dioxide will lead to the proliferation of vines such as poison ivy and Japanese honeysuckle in forests around the country.

Because these plants don’t have to generate the wood structure to support them the way a tree does, they grow much faster. Poison ivy grew twice as fast in an environment simulating projected CO2 levels at mid-century compared to poison ivy exposed to today’s levels of the gas. Not only was it growing faster, but the plant’s oil that causes skin irritation was more potent.

“Increasing abundance of woody vines is causing increased tree mortality and reduced tree regeneration in forests around the globe, potentially resulting in shifts in community composition,” the study concluded.

Rain the issue

Doug Inkley, senior scientist with the National Wildlife Federation, said all of the models for the region under global warming indicate rising temperatures, but less certain is the rainfall forecast. Less rainfall would lead to the drier Ozarks, while more rainfall would lead to the expansion of the range for southern pine species, for example, he said.

But even if rainfall increases, soil moisture could still continue to decline because of warmer temperatures, he noted.

In a wetter future, species of trees now associated with Louisiana, for example might migrate northward, such as southern magnolia and live oak, which is most often seen draped with Spanish moss, said Shannon, with the Arkansas Forestry commission.

“If over the decades climates become warmer, we’d see those trees naturalized in Arkansas,” he said.

Loblolly pine is another species that might march toward Missouri with the change.

“I could see that creeping north,” Shannon added.

Louis Iverson, resource ecologist for the U.S. Forest Service and one of the agency’s leading researchers on climate change, also forecasts an expanding range for loblolly pine.