Tree-ring based reconstructions of disturbance and growth dynamics in several deciduous forest ecosystems

In this dissertation I present four projects that were executed to develop an understanding of disturbance and growth dynamics in deciduous forest ecosystems of eastern North America. In each project, analysis of tree-rings (dendroecology), was used as the primary data source in the analyses. The first project focuses on the growth of American chestnut (Castanea dentata) as a canopy tree in a Wisconsin oak forest. This study revealed that C. dentata growth was vastly greater than other hardwoods growing in the stand. Castanea dentata recruitment into the canopy was apparently facilitated by disturbance; however, it exhibited a range of growth responses suggesting plasticity in ecological response that (1) offers promise for restoration efforts and (2) may have contributed to its dominance prior to the chestnut blight. The second dissertation project addresses anthropogenic disturbance and the formation of oak savanna in central Kentucky. I demonstrated that this oak savanna ecosystem was formed by anthropogenic disturbance in the recent past. Because of the >300 year depth of the chronology in this project, I was able to develop a hypothetical model linking human population dynamics, land use eras, and ecosystem structure.; The third and fourth projects work in tandem. The third project presented a vetting of the commonly employed technique of fire-history reconstruction using fire scars in oak samples. In this project we clarify the assumptions made in such analyses, and show that (1) scarring occurs from sources other than fire in the landscape, and (2) that multiple annual fires may not be recorded in the tree-ring record. Overall, the tree-ring record proved effective in fire history reconstruction. In the final project of the dissertation, I used this technique to develop a fire history of oak communities in the Mesophytic Forest Region of eastern North America. This project included broad geographic coverage, sufficient sample depth to characterize fire at a regional scale. I demonstrated that fire was a frequent and widespread occurrence during the formation of oak communities. I also isolate a variety of features in the historical regime that are appropriate for application in modern stands. For instance, historical fire in these communities was a dormant season event, it exhibited internal temporal variability, and it occurred in all types of climatic conditions, including extreme drought. These features, among others, are summarized to provide reference conditions for fire as a disturbance process. (Abstract shortened by UMI.)...