Microhabitat pattern and the structure of forest bird communities

A forest-simulation model was used to generate a data set comprising tree size classes measured on a 9 ha area of contiguous forest over 750 yr, which was then used to examine the role of microhabitat pattern in structuring random assemblages of bird species defined by niche ellipses in principal-component space. An increasing variation in microhabitat structure through successional time accounted for realistic trends in species richness, dominance, equitability and turnover in forest bird communities. The statistical distribution of microhabitat availability in mature forest provided for an inverse relationship between niche position (species preferring unusual microhabitats have high niche position) and abundance; this same distribution within potentially usable niche space predicted the occurrence of more rare than common species. The spatial distribution of microhabitat variety in mature forests generated an increase in species richness with increasing sample area. At the stand level, among-quadrat variation in microhabitats accounts for the variety and abundance of bird species supported by the stand. Within landscapes, among-stand variation in microhabitat availability represents another source of variation contributing to the distribution of bird species. Results help to explain why habitat area is such a useful predictor of species abundance and suggest the conditions under which estimates of the stand-level distribution of microhabitats might be useful predictors of species-abundance patterns at the landscape scale. -from Authors

Duke Scholars

Author Dean L. Urban Environmental Sciences and Policy