Long-term soil-ecosystem experiments (LTSEs) document how soils function on decadal time scales. See the LTSE website for a few of the many stories about how humans change soils over decades time: http://ltse.env.duke.edu

The Calhoun LTSE in the Southern Piedmont USA, was initiated in 1957 by US Forest Service scientists, Drs. L.J. Metz and C.G. Wells. Metz laid out the sixteen 0.1-ha plots in old cotton fields and planted them with loblolly pine seedlings; Wells proceeded to sample soils and trees in these plots for nearly thirty years, archiving all samples. Today the ecosystems have been resampled on ten occasions: 1962, 1968, 1972, 1977, 1982, 1990, 1997, 2005, 2007, & 2010. The Calhoun study chronicles the significant and often surprising 50-year changes in soil and ecosystem biogeochemistry. The experiment has contributed to understanding effects of acid precipitation, carbon sequestration, and the cycling of nitrogen, phosphorus, base cations, and trace elements.

The research documents how change rather than equilibrium governs the biogeochemistry of human-managed soil and the wider ecosystem, changes affected at Calhoun by the millennial evolution of the natural ecosystem, the substantial legacy of cotton cultivation, and the 50-year development and management of reforestation.

In May 2007, eight of the 16 permanent plots were logged by clear-cutting and are now being regenerated with pine seedlings, all to further study human interactions with soils, ecosystems, and soil and ecosystem services.

Calhoun researchers invite collaborations with other scientists, land managers and users, teachers, writers, students, even poets.

Dan Richter, Mac Callaham
Duke University & USDA Forest Service