A preliminary analysis of the response of an avian community to silvicultural treatments in the southern Cumberland Plateau, Alabama, USA.

We simulated a shelterwood forest regeneration treatment by reducing basal area, and monitored the response of an avian community in oak-hickory forest on the southern Cumberland Plateau, northern Alabama, USA. We used five treatments: control (no removal), clear-cut (100% removal), and 25, 50, and 75% removal of basal area. Territory mapping was used to quantify bird community between mid-April and July of both 2002 and 2003. Microclimate variables were recorded at each plot. The residual basal area and canopy cover showed three distinct conditions after treatment: closed canopy, open forest, and clear-cut. The microclimate varied among treatments: air temperature was highest in clear-cut plots and lowest in control plots, whereas soil moisture had the opposite pattern. A total of 71 bird species were detected, with 36 of them defending territories. Territory density, species richness, and Shannon diversity index differed among the treatments; the relationship between these bird community indices and the level of basal area removal was quadratic, lowest in the clear-cut plots and highest in the intermediate levels. Although species richness was similar among the control, 25, 50, and 75% removal treatments, species composition varied. The richness difference among treatments became smaller in the second year post-treatment (2003) with an increase in bird density and richness occurring in the clear-cut plots.