Breeding bird assemblages of hurricane-created gaps and adjacent closed canopy forest in the southern Appalachians

Abstract

We studied breeding bird assemblages in forest gaps created in 1995 by Hurricane Opal at the Bent Creek Experimental Forest in Asheville, NC. We hypothesized that forest gaps and adjacent closed-canopy forest would differ in bird density, richness, diversity, and relative abundances of some species. To test this hypothesis we censused breeding bird assemblages for 2 years in 12 gaps (0.1±1.2 ha) and 12 adjacent closed canopy controls using strip transects. Gaps had more coarse woody debris, shrub cover, brushpiles, and pit and mound microtopography than controls. Canopy cover was lower in gaps than controls, but remained high (69:4 AE 2:1% versus 89:6 AE 1:7%). Bird assemblage similarity was high. Total density and species richness of birds were higher in gaps than in controls, but species diversity did not differ between treatments. Shrub (primarily Carolina Wrens) and bark-foragers, and cavity shrub and canopy-nesters were more abundant in gaps than in controls. Densities of gap-associated (Indigo Bunting, Hooded Warbler, Carolina Wren) and edge (Eastern Towhee) species were more abundant in gaps. Abundance of interior species including Red-eyed Vireo and Scarlet Tanager were about equal in gaps and controls. Only Ovenbirds were more abundant in controls than gaps. Species that require larger patches of young second-growth forest, such as Prairie Warbler, and Yellow-breasted Chat, did not occur in gaps; but neither are they abundant in the Asheville basin. No Brown-headed Cowbirds were observed in gaps or controls. Unpublished data indicate that parasitism of arti®cial ground nests did not occur, and predation rates did not differ between gaps and controls. Juvenile birds and other evidence of breeding were observed more often in gaps than in controls, suggesting that gaps attract bird families for foraging and provide microsites that attract breeding pairs. Gap size was positively correlated with bird density, species richness, and diversity. This study suggests that small openings and interior edge habitat created by treefall gaps within a forested matrix do not adversely affect breeding birds as measured by the abundance of individual species or community indices. We suggest that canopy gaps increase avian diversity at a landscape scale by providing habitat patches for some species that require young, second-growth forest, and serve as magnets for recruitment and foraging.

Community composition, relative abundance and habitat association of avian species in Apini and Dikuma forest patches, Awi Administrative Zone, Ethiopia

“…As the number of vegetation layer increases, the number of available niches also increases and so does the diversity of avian species. This is similar to a study by Greenberg and Langham (2001) The insignificant seasonal difference in the diversity of bird species within the same forest type in the present study is in agreement with Symth (1974), Karr (1976), and Karr and Freemark (1993). This might be due to the presence of structurally complex vegetation types that buffer the effect of seasonality.…”

Avian use of early successional habitats: Are regenerating forests, utility right-of-ways and reclaimed surface mines the same?

“…However, our results are consistent with several previous studies that suggest mature forest species occupy early successional areas during the post-fledgling period. For example, Hooded Warblers were found to be more abundant in hurricane caused forest gaps in southern Appalachian forests (Greenberg et al, 2001) and in areas with 60% hemlock (Tsuga canadensis) mortality in the northeastern United States forests (Tingley et al, 2002) compared with undisturbed areas. Likewise, Hunt (1998) found that early successional habitats in Vermont and New Hampshire forests may function as reproductive sources for the American Redstart when compared with mature forests.…”

The effect of contrasting management types on two distinct taxonomic groups in a large-scaled windthrow

“…In both taxonomic groups, one may identify the ''winners'' and ''losers'' of the salvage logging. This highly diversified reaction for different disturbing regimes or silvicultural treatments seems to be a common pattern (Greenberg and Lanham 2001;Venier and Pearce 2007;Kolbin 2008;Grimbacher and Stork 2009;_ Zmihorski 2010). In general, it seems that dead wood and natural structure of the windthrow left for natural regeneration positively affected forest dwelling species and saproxylic organisms (Bässler and Müller 2010;Müller et al 2010), whereas abundance of open-area specialists increased as a result of windthrow management.…”