Patterns of northern red oak growth and mortality in western Pennsylvania
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In: Pallardy, Stephen G.; Cecich, Robert A.; Garrett, H. Gene; Johnson, Paul S., eds. Proceedings of the 11th Central Hardwood Forest Conference; Gen. Tech. Rep. NC-188. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station: 386-399
This study evaluates the extent and cause(s) of an observed decline of northern red oak (Quercus rubra L.) on a 50-km portion of a major anticlinal ridge in west central Pennsylvania, and illustrates an approach for evaluating tree declines. Long term annual observations of forest health revealed the onset of crown dieback in 1983, chiefly among red oak, followed by further dieback and mortality. A plot survey in 1994 within 10 stands where increment cores from healthy red oak were obtained in 1986 revealed higher mortality among red oak than other species, higher mortality on ridgetop sites, greater mortality in the northern than southern half of the sample area, and greater mortality among larger diameter red oak. Radial growth and last growth year determined on cores from dead red oak in the 1994 sampling showed highest mortality occurred in 1990-1992. Dead stems displayed spatially-consistent patterns of decreasing growth after 1985. Comparisons with healthy red oak trees revealed a long- term relative growth decline, and relatively lower actual growth after 1969. Radial growth shocks and decreases during 1980-1993 were associated with weather extremes and defoliating insect outbreaks. A persistent, synchronous growth decline began after 1989 in concert with severe gypsy moth defoliation. Greater mortality in certain stands, along with previously discovered disparities in radial growth and tree-ring response to climate, may be related to historic air pollution from Johnstown, a nearby urban/industrial area.
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McClenahen, J. R.; Hutnik, R. J.; Davis, D. D. 1997. Patterns of northern red oak growth and mortality in western Pennsylvania. In: Pallardy, Stephen G.; Cecich, Robert A.; Garrett, H. Gene; Johnson, Paul S., eds. Proceedings of the 11th Central Hardwood Forest Conference; Gen. Tech. Rep. NC-188. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station: 386-399