To understand the importance of topographically determined soil moisture and controlled burning for tree species and forest communities, we resampled plots in the Edge of Appalachia Preserve, southern Ohio, in 2008. The site is part of a continuous forest in a region where soil moisture is determined largely by topography. Our intent was to examine the long term effects of burning and to examine how community structure and species importance might vary among topographic soil moisture regimes and over time.

Eighteen plots (25 m x 50 m)were constructed in 1996 before burning. Nine plots lay within the burn, nine outside it. Plots are stratified across integrated soil moisture index classes as xeric, intermediate, and mesic. Each burn and soil moisture class combination has three replicates. Sampling occurred in 1997, and 2001. We resampled in 2008. For overstory stems (>10 cm dbh) species and dbh were recorded. For saplings (< 10 cm dbh) species and diameter class were recorded. We calculated relative number, relative basal area and importance value for each species within each plot. We executed Anovas for total plot values and for each species (relative number, basal area, and importance values) across burn, moisture and burn*moisture classes.

Results/Conclusions

We did not find statistically significant variation (P=0.05 was chosen) in total basal area or total number across burned and unburned treatments or across moisture classes. However certain species did exhibit significant variation. In the overstory Acer saccharum (2008, relative number), Fagus grandifolia (2008 relative number), Liriodendron tulipifera (relative number and importance value 1997, 2001, 2008), and Quercus prinus (relative number and importance value 1997, 2001, 2008) vary significantly across moisture classes. Fagus grandifolia (relative number 1997, 2008) and Quercus coccinea (relative number 1997) vary significantly with burn treatment and unburned. Fagus grandifolia (relative number 2008) varies significantly in the interaction between treatment and moisture class. The relative number of saplings for Acer rubrum (all years), Carya (1997), Populus gradidentata (2001) and Sassafras albidum (all years) vary significantly across moisture classes. Carya (1997) and Populus grandidentata (2001) vary significantly with burn treatment and unburned control. Carpinus caroliniana varies in all years across all classes. Our results suggest that controlled burning to a small degree and stratification of soil moisture to a larger degree result in differences in tree species assemblages in southern Ohio.