Biodiversity and Land Productivity

http://www.motherearthnews.com/nature-and-environment/biodiversity-land-production-bioenergy.aspx

Cows in Tallgrass
   PHOTO BY BRYAN WELCH

Most North American farms of the 21st century are, comparatively speaking, biological wastelands. Plowed, fertilized and cultivated from property-line to property-line, much of the Great Plains has been stripped of its wildlife. Walk through a soybean field anywhere in the Midwest, then take the same sort of stroll through a native prairie in the same region (if you can find one). The contrast is shocking. The prairie, especially the dominant “tallgrass” prairie, is among the world’s most fecund environments. Dozens of species thrive in a thick carpet of plants growing unbelievably fast. In three months I have watched an acre of my undisturbed pasture grow six tons of grass. One acre, three months, six tons.

Ecologist David Tilman has been studying the productivity of the prairie at Minnesota’s Cedar Creek Natural History Area for more than a decade. He has compared the productivity of the land planted in a natural mixture of several species with the same land planted with only one highly useful species. In the December 2006 issue of Scientific American he reported that the diverse natural prairie produced 238 percent more “bioenergy” than the same land planted in one species. Furthermore, the diverse, natural prairie stores two-thirds of its productivity underground, making a native grassland naturally carbon-negative, no matter what the tops of the plants are used for. The soybean field produces a lot of food, but it produces comparatively little life, for what that’s worth.