Thinning and burning in oak woodlands

July 2013.A Thesis presented to the Faculty of the Graduate School University of Missouri--Columbia In Partial Fulfillment of the Requirements for the Degree Master of Science.Thesis supervisor: Dr. John M. Kabrick.The legacy of fire suppression in savanna, woodland, and forest ecosystems since the early 20th century has allowed heavy encroachment of fire-intolerant species throughout open-oak communities of Midwestern North America. Shifts in resource gradients and the development of novel environmental-species relationships in many of today's second-growth stands has challenged conventional management techniques for objectives such as regenerating oak and pine, reducing fuel loads, and controlling invasive species. This study evaluates controlled burning and mechanical thinning treatments as methods for achieving these objectives while reversing the departure from natural or historic conditions in fire-suppressed woodland communities. We investigated each of these silvicultural practices, including the combination, for over a decade to address changes in stand structure, species composition, tree growth, and bole damage. We found that overstory stocking was significantly reduced after two prescribed burns and lowest in harvest-burn plots, which also contained the greatest percent coverage of forbs, graminoids, shrubs, and vines. Woodland indicator species responded almost equally to harvest-only and burn-only treatments, while the combination led to significantly greater coverage's than in control. Species diversity, richness, and evenness were also greatest on sites where two prescribed fires were conducted following harvests, although there was no significant difference between other treatments. Fire-induced mortality was significant after two prescribed burns, especially where harvested, but had minimal impact on trees >25 cm. Basal re-sprout in harvested stands was marginally reduced by two prescribed fires, but the density of small diameter stems (