Unearthing insights for a Sustainable Future in a
Rural South Carolina Forest
Dan Richter’s Team Investigates Environmental Effects of Wood Energy p.4
by Tim Lucas
“Dan’s groundbreaking work on soils at Calhoun Forest is of global importance. It is fitting that he is now examining the environmental impacts of wood fuel use at this well-studied site. I look forward to seeing the outcomes from Dan’s research to make sure that we proceed sustainably,” Smith says.
To simulate conditions in a forest that has been harvested for wood products, including wood for energy, Richter had half of his 16 research plots at the Calhoun forest “operationally logged” in May 2007. Pulp wood and solid wood products were removed, leaving behind only tree tops and other debris.
As soon as the logging dust settled, he and his team of three PhD students, Jason Jackson, Meg Mobley and Jian Wei Li, and research associate Paul Heine, began the monumental job of estimating how much wood biomass had been left behind.
“Harvesting for wood energy means that managers need to become more and more efficient in removing biomass from forests,” Richter explains. “Conventional harvests of timber take products from the forest every 15 to 30 years and they typically leave low-value wood behind. This material helps resupply forest nutrition. But under intensive management for wood energy, more frequent harvests may be needed, with less material left to resupply forest nutrition.”
Armed with high-tech GPS units and old-fashioned tape measures, Richter’s team canvassed the clear-cut plots, recording the length and diameter of every sizeable branch and stump, as well as measuring and re-measuring the overall area of land cleared. Branches, twigs and debris too small to measure individually were collected from sampling sites throughout the cleared area and sawed up so their biomass could be measured collectively, by volume and weight. Hundreds of samples were taken back to the lab in Durham and ground up, to measure their carbon and nutrient content.
“It’s a lot of work just to get to a number,” says Jackson, “but it’s absolutely critical. We need to know the amount of woody debris left behind because that’s what will impact soil nutrition, feed the decomposers, and affect forest health and recovery in coming years.”
Although they work collaboratively, each has his or her own area of related expertise.
Richter and Li study nutrient cycling in the forest’s O-horizon—the topmost layer of soil, composed of decaying leaves, twigs, pine needles and other organic matter on the forest floor. Their studies, published in Ecology and other peer-reviewed journals, have revealed new insights into how forest re-growth affects the soil’s nutrient balance over time, specifically the availability of micronutrients and iron oxides critical to the biological functioning of the soil.
photo captions: Richter at the Calhoun Forest; panorama of the Calhoun Forest; Richter, Jason Jackson, Meg Mobley and Jian Wei Li surveying the Calhoun site.