EFFECTS OF EVEN-AGED MANAGEMENT ON FOREST BIRDS AT NORTHERN HARDWOOD STAND INTERFACES

Breeding birds were counted along transects across edges of even-aged northern hardwood stands in the White Mountain National Forest, New Hampshire, U.S.A. Two replicate transects across each of 7 edge types representing 3 classes of contrast (abrupt, intermediate, and subtle) were sampled during June 1983-1985 to define species assemblages at stand edges and estimate the width and longevity of functional edges under even-aged management. Of 52 bird species, 28 occurred across all three classes of edges, but no unique species or assemblages were evident at the edges between stands. Across edges between young stands, bird species richness declined linearly from seedling stand interior to pole stand interior, but no differences in cumulative bird species richness by edge contrast type were found. The proportion of edge-detected species was higher in the younger stand in all edge contrast types except the most subtle edge type between mature stands. Only across seedling-sawlog and sapling-large sawlog edges were bird assemblages more different than similar. Edge "avoidance" was pronounced when stands were most different. The distributions of foraging and nesting guilds differed (P < 0.05) only when seedling or sapling stands abutted stands that were pole-sized, or larger. Edges between even-aged northern hardwood stands, even of greatly contrasting age or height, are different from field-forest edges. Northern hardwood clearcuts regenerate rapidly and do not develop a grass stage nor a brushy border. Foliage profiles in stands of widely disparate ages are similar, and effects of boundaries between even-aged stands on breeding birds are ephemeral.