Do pine trees in aspen stands increase bird diversity?

In the Black Hills of South Dakota, quaking aspen (Populus tremuloides) is being replaced by conifers through fire suppression and successional proces ses. Although the Black Hills National Forest is removing conifers (primari ly ponderosa pine [Pinus ponderosa]) to increase the aspen communities in s ome mixed stands, Forest Plan guidelines allow four conifers per hectare to remain to increase diversity in the remaining aspen stand. We compared bir d species richness in pure ponderosa pine, mixed stands dominated by ponder osa pine with quaking aspen, mixed stands dominated by aspen with ponderosa pine, and pure aspen stands. Stands dominated by ponderosa pine had lower (P < 0.01) bird species richness than stands dominated by aspen. Aspen in p onderosa pine stands or pine in aspen stands did not increase bird species richness (P greater than or equal to 0.68) over the respective pure stands. Thus, leaving ponderosa pine in aspen stands will not have the desired eff ect of increasing bird diversity but may h a ve the negative effect of spee ding successional processes that replace aspen with conifers.