As many national parks in the Northeast pursue their missions of re-creating open landscapes where important historical events took place, managers are using native grasses to replace forests that grew up on these sites in the 20th century and to restore open spaces now occupied by nonnative, cool-season grasses. This initiative reflects National Park Service (NPS) policy to restore native species and has ramifications for wildlife, particularly grassland birds.
By the mid-1800s, the once-dominant forests that covered much of the eastern United States had been converted to agriculture. Farming practices, particularly in the southern states, quickly depleted the land of nutrients. These worn-out fields were left fallow or used as pasture as new land was opened for farming. By the 1860s in the eastern United States, the landscape was typically a mosaic of crops, pasture, orchards, woodlots, and abandoned fields. The abandoned fields began the slow succession to forest, often being first colonized by native, warm-season grasses such as broomsedge (Andropogon virginicus), purpletop (Tridens flavus var. flavus), Indiangrass (Sorghastrum nutans), little bluestem (Schizachyrium scoparium var. scoparium), and big bluestem (Andropogon gerardii). These types of grasses grow in clumps or bunches, never forming a blanket of turf, and put down long taproots, penetrating at least 6 feet (1.8 m) into the subsoil. The long roots reach needed nutrients and water, making the grasses drought tolerant and helping rebuild the soil. Many species of grassland birds thrived in this landscape of small farming fields and abundant fallow ground.
Changes in agriculture following World War II, such as the introduction of large-scale crop production, and use of turf-producing, nonnative, cool-season grasses, particularly cultivars of fescue such as Kentucky-31, began altering the agricultural landscape. Habitat conversion and intensification of agricultural practices probably led to the decline of many grassland birds (Trocki and Paton 2005). Use of fescue for hay and pastures also greatly reduced wildlife habitat. These changes also took place in many historical park units where agriculture has been used as a land management tool. In many parks, the agricultural lands no longer reflected the mosaic landscape of the 1800s.
Peterjohn, B., B. Eick, and B. Blumberg. 2007. Native grasses: Contributors to historical landscapes and grassland-bird habitat in the Northeast. Park Science 24(2):62–66.
Available at http://www.nature.nps.gov/ParkScience/archive/PDF/Article_PDFs/ParkScience24(2)Winter2006-2007_62-66_Peterjohn_et_al_2552.pdf.