Songbird Community Variation Among Five Levels of Overstory Retention in Northern AlabamaThis article is part of a larger document. View the larger document here.
We compared songbird communities among varying degrees of overstory tree retention in the oak-hickory forest of the southern Mid-Cumberland Plateau region. Three 20-ha complete block replicates of 5 experimental treatments (15 treatment units, 4 ha per unit) were used. The five treatments were operational shelterwood stands with target overstory retention levels of approximately 0, 25, 50, 75, and 100 percent. The residual basal area and resultant canopy cover of these overstory retentions were compared among treatments and both showed three distinct conditions, closed canopy, open forest, and clearcut. Territory spot-mapping was used to quantify bird species richness and density during the first post-treatment year, between mid-April and July 2002. Sixty bird species were detected with 34 of those defending territories on the sites. Clearcuts (0 percent retention) had significantly lower values than the other four treatment types for overall bird territory density, species richness, and Shannon diversity index. Territorial density of breeding songbirds was highest in the 50 percent retention treatments, while species richness and Shannon diversity peaked in the units with 25 percent basal area retention.