Oak mast history from dendrochronology: A new technique demonstrated in the southern Appalachian region.

摘要

The main objective of this research was to develop a technique for mast reconstruction using dendrochronology. During this work I collected cores from 845 individual trees from white (Quercus alba), chestnut (Q. prinus), northern red (Q. rubra), black (Q. velutina), and scarlet oaks (Q. coccinea), at 17 sites in the southern Appalachians. I identified five basic steps that are necessary for mast reconstruction. (1) Crossdate the tree-ring series; (2) Standardize the series with a flexible cubic smoothing spline; (3) Use multiple regression to remove climate; (4) Use simple linear regression between the climate residuals and a known mast record to define a regression equation; (5) Use the regression equation to reconstruct mast beyond the scope of the known mast record.; From climate analysis of these five oak species grown under closed-canopy conditions, I determined that four of the five species were adequate recorders of Palmer Drought Severity Index and temperature. I developed five mast reconstructions on the stand level explaining from 20% to 47% of the remaining variance in the chronology after climate was removed. At most, 25% of the site-species chronologies showed a reduction in ring width in known years of heavy mast production, which has implications for the theories of mast fruiting. The evolved strategies hypothesis predicts that a tradeoff should be evident between incremental growth and reproductive effort and the lack of a consistent tradeoff brings this theory into question. I explored the application of mast reconstructions to a problem in wildlife management by comparing two of my reconstructions to a black bear population estimate and black bear harvest records. I found that acorn production from three years prior and the current year correlated significantly with these respective records.; This work demonstrates a new technique for dendrochronology, which I call dendromastecology. It can be applied to other genera and localities around the world to provide information to tree biologists, wildlife ecologists, and mast ecologists. Whether or not future mast reconstructions are successful, they will continue to provide evidence about the tradeoff between incremental growth and reproductive effort.