Importance of hardwood competition to American chestnut survival, growth, and blight development in forest clearcuts

Abstract

Ten years after clear-cutting forest stands in Virginia and West Virginia, competing hardwoods around American chestnut trees were either periodically cut (managed) or not cut (control or unmanaged). Blight epidemics occurred in all clear-cut plots prior to their establishment in 1984. For the control plots, the number of chestnut sprout clusters (group of stems sprouting from a single stump) with blighted live stems had decreased by 1989, but between 1985 and 1988 there was a general increase in blighted chestnut stems for the managed clearcut plots. The number of apparent superficial cankers increased in two of three managed plots between 1986 and 1989. Survival of chestnut clusters was high in managed plots between 1985 and 1989, but decreased in one control plot to zero by 1988. Mean diameters at breast height of measurable chestnut stems (> 0.8 cm) declined or remained constant in control plots, but generally increased in managed plots after initial declines. Similar but greater responses were observed in a plantation of American chestnut. Unmanaged clearcuts with a high survival of chestnut clusters had low stand basal areas for competing hardwoods, and vice versa. A mesic site favored American chestnut growth and apparent superficial cankers in the absence of competing hardwoods. Key words: chestnut blight, hypovirulence, biocontrol, forest competition.

The effects of logging and disease on American chestnut

“…This result is supported by a study by Griffin (1992) that found that mesic sites with high canopy basal area also had high chestnut survival. However, Griffin et al (1991) showed that in young forests (13 or 19 year-old clearcuts), chestnut survival was inversely related to canopy basal area. Clearly, canopy density affects chestnut mortality.…”

An analysis of ecophysiological responses to drought in American Chestnut

“…A review of the literature reveals a paucity of data regarding American chestnut drought tolerance and performance under soil water deficits. In fact, with respect to blight tolerance, Griffin et al [15] observed more blight on mesic as opposed to xeric sites, prompting the investigation of the role of xeric conditions in natural hypovirulence biocontrol of the blight fungus [16]. Interestingly, post blight populations of American chestnut exist mostly in the understory of xeric slope hardwood forests [16].…”

Superficial canker instability during winter and virulence ofEndothia parasiticaassociated with managed forest clearcut and plantation American chestnut trees

“…On clearcut sites with high tree-growth potential, no chestnuts may survive due to competition from hardwood tree species, nonsuperficial blight cankers, and browse damage (Griffin 1989, Griffin et al 1991. In contrast, management of forest clearcuts, by removal of competing hardwoods every 2 years over a 6-year period, resulted in high chestnut survival (Griffin et al 1991). More apparent superficial cankers were observed on American chestnut trees in managed clearcut sites than in unmanaged forest clearcut sites after 6 years.…”