J.S. Christie | Search USGS

USGS2000

Clearcut stand size and scrub-successional bird assemblages

We investigated the effects of clearcut stand size on species richness, reproductive effort, and relative abundance of scrub-successional birds and the entire bird assemblage at the Savannah River Site in South Carolina. We used standardized mist-net grids to mark and recapture birds in clearcuts replanted with longleaf pine ( Pinus palustris ) in stands of 2 to 57 ha that were two to six years old. Species richness for the entire bird assemblage was not explained by stand size ( P = 0.67), stand age ( P = 0.95), or the interaction of these two variables ( P = 0.90). Similarly, species richness of scrub-successional birds was not explained by stand size ( P = 0.63), stand age ( P = 0.55), or the interaction of stand size and stand age ( P = 0.35). Regressing species richness on clearcut stand size, we found a significant negative relationship between these variables for the entire bird assemblage ( P = 0.01) and for scrub-successional birds ( P = 0.02). The ratio of juveniles to adults in mist-net samples varied by year ( P = 0.04), but neither clearcut size ( P = 0.23) nor the interaction of clearcut size and year ( P = 0.25) was related to the ratio of juveniles to adults in the sample. We found no relationship between the frequency of capture of any category of birds and stand size (scrub-successional, P = 0.52; woodland, P = 0.77; combined sample, P = 0.55). Neither bird-species richness, reproductive effort, nor relative abundance differed across clearcut stand sizes. Clearcut stand size does not appear to be an important management variable if variation in species richness, reproductive effort, or relative abundance are objectives. We suggest that even-aged forestry is a useful tool for managing birds in the southeastern United States.

The Auk↗

USGS1999

Scrub-successional bird community dynamics in young and mature longleaf pine-wiregrass savannahs

Public agencies are required to manage for threatened and endangered species and for biodiversity. However, at times, management for threatened and endangered species precludes consideration of other species. We investigated how managing for red-cockaded woodpeckers (Picoides borealis) and biodiversity at the Savannah River Site (SRS), South Carolina, affected communities of bird species that use early-successional scrub habitat (hereafter, scrub-successional species). Management for red-cockaded woodpeckers at the SRS involved both (1) manipulating mature longleaf pine (Pinus palustris)-wiregrass (Andropogon spp.) stands via canopy thinning, removal of midstory trees, and prescribed burning; and (2) even-aged timber harvesting. The former management practice encouraged red-cockaded woodpeckers to establish new colonies in previously unoccupied stands (hereafter, 'recruitment' stands). The latter management practice is used to remove off-site planted pines and replant with preferred longleaf pines. We conducted a constant-effort mist net study in recruitment and regenerating stands (stands clearcut and planted with longleaf pine) during the breeding seasons of 1995-96. We hypothesized that the scrub-successional bird community in recruitment stands would have greater species richness and higher survival and reproductive rates per species than in regenerating stands. However, recruitment stands always had fewer scrub-successional species (1995:36 species; 1996:31 species) than regenerating stands (1995:54 species; 1996:55 species), and all species that occurred in recruitment stands also occurred in regenerating stands. Species which commonly occurred in both recruitment and regenerating stands had similar adult:juvenile ratios (P > 0.15) and relative proportion of adults in breeding condition (P > 0.05). We detected no difference in survival rates of Bachman's sparrows (Aimophila aestivalis), indigo buntings (Passerina cyanea), and of 'combined' scrub-successional birds between stand types (P > 0.05). We found that even-aged forestry is an important management practice for maintaining and increasing avian biodiversity on public lands, as well as an acceptable management practice for red-cockaded woodpeckers.

Journal of Wildlife Management↗