A Retrospective Dendroecology of American Chestnut in the Southern Appalachian Forest

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9509307 Stahle The catastrophic chestnut blight destroyed one of the most important species of the eastern deciduous forest and initiated dynamic forest responses that may last for centuries. The scarcity of quantitative data on pre-blight forests has complicated efforts to understand the environmental impact of the blight. Fortunately, an exact and detailed record of chestnut growth can still be recovered from blight-killed logs in a few selected forests that are otherwise largely undisturbed. This project will develop 200- to 300-year long tree-ring chronologies of American Chestnut from blight killed logs at six ancient forest locations in the southern Appalachian region. Tree-ring chronologies will also be developed at the same locations for three age categories of hemlock, and oak. These three categories will be ancient, young pre-blight, and young post-blight trees. At least 24 chronologies will be developed, including 3 chestnut and nine oak from xeric sites. The chestnut chronologies will be extended when possible with ancient chestnut timbers recovered from early historic buildings. All chronologies will be compared with monthly climate data which begin as early as 1871 in order to define the climate response of chestnut in pre-blight forests, and two of its important former associates in pre- and post-blight forests. The chronologies will be used to test hypotheses concerning possible changes in the climate forcing of southern Appalachian forest ecosystems following the blight. The PIs will test the hypothesis that the mature growth rates of chestnut were limited by specific climate variables unique to chestnut. If true, this unique climate influence on an important fraction of presettlement forests has been greatly diminished by the selective removal of chestnut. They will also test the hypothesis that the microclimate changes initiated by the blight have altered the specific seasonal climate variables most limiting to the growth of chestnut associates such as hemlock and oak. The p roposed tree-ring chronologies will salvage a priceless record of chestnut growth that has been ignored for over 50 years and may soon decay beyond recovery.