INFLUENCE OF WITHIN-PLANTATION HETEROGENEITY AND SURROUNDING LANDSCAPE COMPOSITION ON AVIAN COMMUNITIES IN HYBRID POPLAR PLANTATIONS

We conducted breeding bird surveys in Minnesota, Wisconsin, and South Dakota in 12 hybrid popular plantations and surrounding landscapes fro m 1992 to 1994. Plantations varied in age, shape, composition of surro unding landscape, and internal vegetative heterogeneity. Numbers of br eeding bird individuals and species in plantations were lower than in surrounding forest/shrub habitat, but higher than in row crops. Number s of individuals observed within several bird groups based on migrator y status and habitat preference also differed among plantations and su rrounding land-use types. Most differences were between numbers in pla ntations and row crops. Year-to-year changes in bird species compositi on in plantations were more likely in plantations between ages 2 and 4 years than in younger or older plantations. Correlative evidence from canonical correspondence analysis illustrated that plantation bird co mmunities were related to habitat in surround landscapes, plantation a ge, size, latitude, and longitude. Additionally, more heterogeneous pl antations had more species, individuals, and numbers of long-distance migrants. Plantations will likely not support bird communities that ar e comparable to natural forests in either species composition or speci es diversity. A goal would be to position them in the landscape to min imize impacts on regional biodiversity. This could be accomplished by maintaining structural diversity of plantations by creating a broad ra nge of successional stages (ages) throughout plantations within a regi on. Size and connectivity of existing forest fragments may be increase d by plantations, but fragmentation of natural open areas should be av oided.