Issue 6

Research Makes Afforestation Work

by Kim MacQueen

Let’s say you have inherited a few hundred acres of farmland in the Lower Mississippi Alluvial Valley (LMAV), the vast, 25-million-acre complex of forested wetlands running from Illinois to the Gulf of Mexico. You’re standing outside taking it all in, fertile farmland rented out for soybean production, dotted with isolated stands of elm, ash, sugarberry, and oak.

Back in the early 1900s, that land looked a lot different. Rather than a few trees here and there, your acreage was filled with bottomland hardwoods so thick the canopy darkened the understory. The trees provided habitat for wildlife and kept the surrounding air and water clean. Over the next 100 years, it was drained and deforested for agricultural use, damaging the ecosystem and contributing to erosion, decreased water quality, and greenhouse gasses.

The land’s previous use as soybean fields has driven away the wildlife that depend on large forest expanses, as well as the birds that formerly passed through here every autumn on their way south. With more and more of their habitat lost to deforestation, these mostly neotropical bird species have been squeezed into ever smaller migration corridors. In fact, fully 80 percent of the bottomland forest that used to stand in the area surrounding the Mississippi River Basin has been given over to agriculture, so vast numbers of certain species who used to live here are gone.

Remember, too, that agricultural profits are down, so keeping your land in soybeans might not make much sense. Since it’s located in the flood plain, not much beyond soybeans will grow there anyway. It’s a good idea to remove your land from agricultural use altogether— but unless it derives some economic benefit, you may not be able to keep your land at all.

It’s enough to make you want to turn around and go back inside. Before you do, though, remember—good help is available. This is what the researchers at the SRS Southern Hardwoods Laboratory in Stoneville, MS, do every day.

Help Where You Need It

Stoneville scientists focus on the regeneration of bottomland hardwood forest in the LMAV, helping landowners sort out the details of returning farm land to forest—a process called afforestation. Research forester Emile Gardiner has worked primarily on this issue since 1994. His work centers on providing upto- date research aimed at helping private landowners make the best decisions for individual pieces of land.

“I work on the biological end of afforestation, researching problems like the best way to establish a forest stand on a site that has been in agricultural use for several decades,” Gardiner says. “This might include identifying morphological or physiological traits of seedlings that improve survival and growth on adverse sites, gaining an understanding of environmental factors that hinder stand establishment, or promoting alternative afforestation practices that address multiple landowner objectives.”

But afforestation is really an ecological imperative. The area’s now profound lack of forest contributes to erosion. Agricultural runoff containing nitrogen and phosphorous flows into the Gulf of Mexico, contributing to the lack of dissolved oxygen that leads to marine dead zones.

“To encourage and sustain additional forestry land use in the LMAV, we will have to strengthen the prominence of forestry in the regional economy,” notes Gardiner. Farming will also continue to be important. This means the area will never be returned entirely to the bottomland hardwoods that characterized the Big Woods of former times, but will continue to be a mixture of farm and forest.

A major aid to Stoneville’s afforestation efforts comes in the form of two innovative resources from the USDA Natural Resources Conservation Service (NRCS): the Conservation Reserve Program and the Wetlands Reserve Program. Both were established by Congress to provide landowner incentives to remove economically marginal or otherwise sensitive land from agricultural use.

“Landowners can enroll in the program that suits their desires. If the program involves afforestation, they are assisted by a forester who develops a management prescription for establishing trees on their property,” Gardiner explains. “The landowner may receive cost-share payments for afforestation practices including site preparation, seedling planting, weed control, etc. Our research focuses on developing practices that increase the success of forest establishment.”

Under these programs, owners can receive rental payments as an incentive for returning previously farmed land to forest and wetlands. Depending on the program, the payments compare favorably with land rental rates for farming—if you can rent your land to someone growing agricultural crops for $50 an acre, you’d get a similar payment through this program.

Since they were established in 1985, the NRCS programs have enrolled more than 34 million acres across the United States, according to USDA Farm Service reports. “Both of these Federal programs are widely accepted among private landowners across the South,” notes Steve Meadows, research forester at Stoneville. “As a result, many thousands of acres of marginal cropland in our area have been restored to bottomland hardwood forests.”

What Works and Why

What’s the key to regenerating forest in the LMAV? The answer is . . . it depends. On what you plant and where, on whether you use seed or seedlings, on whether and how well you care for the fledgling site once you’ve planted—and on your own personal objectives as a landowner.

“It’s very site-specific,” Gardiner says. “You have to ask the landowner to define the outcomes they wish to achieve through afforestation. Soil types, hydrologic regimes, and other variables— including the amount the landowner is willing to invest—are considered when designing an afforestation plan to meet the defined management objectives. Getting the landowner to articulate what they want of their forest 10, 20, or 100 years in the future is often very difficult.”

That’s where Meadows comes in. While Gardiner helps landowners through the planting stage, Meadows looks at the long term, studying intermediate stand management—the silvicultural practices prescribed after the stand has developed through the sapling stage. If you’re deciding whether to plant, say, all oak or a mix of species, and you want to know what your stand will look like after it’s been there for 20 years, Meadows is your man.

“It is extremely important for hardwood forest managers to understand the patterns of stand development, particularly in mixed-species forests,” Meadows notes. “Knowledge of stand development patterns and processes allows hardwood silviculturists to make more effective stand prescriptions and to more accurately predict the treeand stand-level responses to those prescriptions.”

A No-Win Boxing Match Among Trees

Since the 1980s, Meadows has helped to conduct workshops for landowners through Mississippi State University, outlining the best practices for stand management. One of the first decisions, when you’re looking at how and what to plant, is whether your forest will be a pure stand (all one species) or mixed, and how that stand will fare after 15 or 20 years. Because of the various developmental patterns of bottomland hardwood species, there’s a lot to consider when trying to predict future stand structure.

“One of the most serious problems associated with establishing a pure oak plantation is that the individual oak trees don’t compete very well with each other,” Meadows says. “By the time they are about 30 to 40 years old, individual oak trees in a pure oak plantation are like evenly matched heavyweight boxers in a championship fight. Neither boxer can gain an advantage over the other and, by the 15th round, they’ve both pretty much had it, but neither one goes down. Both of them are exhausted, but neither one is willing to give up. Oaks in a pure oak plantation behave much the same way. They’ve all experienced the effects of severe competition for a number of years, but generally are not able to out compete their neighbors. As a result, the plantation usually stagnates quickly and the majority of the trees suffer reduced growth and vitality.”

Does that mean mixed-species stands are inherently healthier? Again, that depends. Most of the existing research is on mixed-species natural stands, and it remains to be seen whether individual trees in pure stands would likely play out their years together under the same boxing-match scenario. Stoneville scientists are researching stand management of both pure and mixedspecies stands now, in small locations ranging from Alabama to Texas. Stoneville scientists have also set up studies at the Sharkey Restoration Research and Demonstration Site, a 3,000-acre holding of the U.S. Fish and Wildlife Service in Sharkey County, MS. Once a managed farm, the land has been offered up as a study site to researchers interested in forest restoration and afforestation.

One 240-acre afforestation study on the Sharkey site is carved into 20-acre plots, with different treatments assigned to each plot. This lets researchers monitor variables such as wildlife use and changes to soil chemistry. So if you’re interested in knowing the difference between the ongoing development of a pure stand of oak and that of a mixed stand of several species, you can visit and take notes about what each one looks like. Each year, hundreds of people—from landowners to student groups to Federal policymakers—visit the Sharkey site.

So—the challenge is a big one. Landowners in the Lower Mississippi Alluvial Valley who want to return their land to forest have a lot to do, but a wealth of assistance and information is right at hand.

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For more information:

Emile Gardiner at 662–686–3184 or egardiner@fs.fed.us
Steve Meadows at 662–686–3168 or smeadows01@fs.fed.us

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Kim MacQueen is a freelance science writer based in Brevard, NC.