Authors: Raelene M. Crandall; Ronald E. MastersLow intensity fires were historically recurrent in mixed-pine hardwood habitats in North America. In the absence of fire, open savannas and prairies were converted to closed-canopy forests with low understory plant diversity. We examined the effectiveness of restoration using fire (1-4-year return interval) and timber harvesting on plant diversity and stand structure 20 years after restoration was initiated. We found that one- and two-year burn intervals prevented establishment of woody species in the canopy and resulted in prairie habitat with the greatest plant diversity. Three-year burn intervals created savanna habitat with patchy and clumped establishment of woody species. In the four-year burn intervals, open woodlands appear to be forming at a higher density. We conclude that restoration of species richness in fire-suppressed, mixed-pine hardwood forests is possible with prescribed fire alone after extended periods of time. However, restoration of structure and function in the short term for species of special concern (i.e., woodland-grassland obligate songbirds) will require alteration of stand structure through thinning to open the canopy and restore these habitats to their historical state. Although a three-year burn interval appears to be a threshold, shifting community structure from herbaceous to woody dominated, we recommend a variable, frequent fire regime.