Document: ROB-3-69-55

Sugar maple mortality on the Allegheny National Forest from 1990-1999 in relation to management and defoliation.

LONG, R.P.* ¹, J.OMER ² and R.WHITE ³

USDA Forest Service, Northeastern Research Station, Delaware, OH USA ¹
USDA Forest Service, Northeastern Area State and Private Forestry, Morgantown, WV USA ²
USDA Forest Service, Allegheny National Forest, Warren, PA USA ³

Abstract:
Sugar maple, Acer saccharum Marsh. has been declining across the unglaciated Allegheny Plateau in northwestern Pennsylvania since the mid-1980s. In 1990, the Allegheny National Forest (ANF), in cooperation with Northeastern Area State and Private Forestry, installed a long-term sugar maple health monitoring network in 30 stands across the ANF, using protocols similar to those used by the North American Maple Project (NAMP). Ten of the stands had no cutting in the last 30-40 years, 12 stands were thinned within the last 10 years, and eight stands were located in recently harvested areas where only a few trees per acre, usually sugar maples, were left as residuals. In this latter group of stands, plots were not feasible; instead about 15-20 of the residual sugar maples were measured across the harvested area. In uncut and thinned stands, all standing trees = 10 cm dbh were tallied within three 20 m by 20 m plots and tree health status and defoliation incidence and severity were determined annually by two observers. Initial sugar maple mortality (number of dead sugar maple as a percent of all sugar maple in a three plot cluster) in 1990 averaged 2.3% (range 0 to 13.3%) for all 30 stands. Average sugar maple mortality from 1990-1999 in all crown classes was 3.2%/yr for uncut stands, 2.3%/yr for thinned stands, and 4.3%/yr for sugar maple residual stands. These mortality rates exceed those reported by the NAMP for a similar period in which average mortality was 0.9%/yr (range 0.2 to 1.9%/yr) for 9 states and 4 provinces. Mortality rates in most stands were highest from 1991 to 1995, coincident with drought (1991) and with outbreaks of defoliating insects including elm spanworm, Ennomos subsignaria, forest tent caterpillar, Malacosoma disstria, and fall cankerworm, alsophila pometaria .

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This abstract is being presented at: 1:15 PM in session:
Oral Session #51: Disturbance Ecology: Harvesting, Grazing and Roads.