Twelve years of herbaceous vegetation change in oak savanna habitat on a Maryland serpentine barren after Virginia pine removal

Herbaceous vegetation monitoring results are reported for serpentine oak savanna (Quercus marilandica and Q. stellata) in Soldiers Delight Natural Environment Area and Wildlands for the period 1992-2003. Monitoring was initiated after unexpectedly finding savanna habitat during a grassland restoration project. Two small areas (each about 0.2 ha) were discovered on the east side of adjacent northwest-facing ridges, by clearing Virginia pine forest (Pinus virginiana) during the winter of 1991/1992. Permanent plot sampling of one of the areas began in 1992, and contiguous grassland vegetation was sampled for comparison. The area was included in a prescribed burn in November 1997 (post-freeze). The herbaceous layer in the savanna was depauperate at the beginning of the study; total herbaceous species cover was only 16.4%, and half of it was produced by only two species, Dichanthelium depauperatum and D. sphaerocarpon. Before the end of the study, total species cover had almost tripled to 46.2%, and little bluestem (Schizachyrium scoparium) had become the dominant species. Species richness in the savanna increased almost 50% during the period due to taxa that also occurred in the grassland with only one exception. But 14 grassland species were not sampled in the savanna, and community indices of similarity were low suggesting important habitat differences.