Long-term vegetation recovery on reclaimed coal surface mines in the eastern USA.
Abstract
While reclamation of degraded landscapes is becoming increasingly common, few studies have investigated the long-term effects of reclamation efforts on plant conservation. The goals of this study were to determine whether vegetation communities on reclaimed mines approximate those of the surrounding forest, and to evaluate how intensive reclamation practices used to address short-term erosion and water quality concerns affect long-term recovery. In 1992-93 and 1999 the vegetation on 15 coal surface mines reclaimed between the years 1967-1987, and five periodically logged hardwood forest reference sites in south-western Virginia, USA, were surveyed. Herbaceous species richness was similar on all sites, whereas woody species richness was higher in reference sites than in reclaimed sites. Vegetation community composition on reclaimed sites continued to progress towards reference forest sites between the two sampling periods, but vegetation community composition even on the oldest sites (reclaimed >35 years prior) still differed substantially from reference sites. Herbaceous cover was higher and tree basal area was lower in reclaimed sites compared with reference sites at the first sampling period, but these differences were much less pronounced by the second sampling period. The overall composition of the older reclaimed sites was similar to the reference forest sites, suggesting a high level of resilience in the forests studied. But, as with a number of previous studies of long-term recovery on highly disturbed sites, a number of less common forest species still had not colonized reclaimed sites, raising the question of their value for conservation. These results concur with a common theme that goals for short-term and long-term recovery of highly disturbed sites may conflict. Planting with aggressive non-native ground cover species to minimize short-term erosion may have slowed long-term recovery on the sites studied. Widespread planting of Pinus strobus has not reduced species richness thus far, but may as the canopy closes. More emphasis should be given to long-term recovery potential in developing mine reclamation plans, and strategies to further this goal should be tested.