The oak forest type is one of the largest endangered ecosystems. Central hardwoods ecosystems dominated by an oak overstory are seldom replaced with oak regeneration, regardless of harvesting method. This failure in oak development is the result of changed disturbance regimes, in particular, the suppression of human-caused fire since the 1930s. Studies of prescribed fires have established that fire alone will not remove the larger midstory trees that inhibit oak regeneration. As part of the national Fire and Fire Surrogate (FFS) study, four treatments have been implemented: control, fire only, thinning only, and fire plus thinning. In addition to the integrated ecosystem studies required by the FFS study protocols, collateral investigations include the effects of the treatments on: acorn production and predation by weevils and deer, bats, and flying squirrels; mycorrhizae; fire intensity; and soil moisture.