Ecology and Paleoecology of American Chestnut in Eastern North American Forests

Recent surveys of surviving American chestnut populations demonstrate that chestnut sprout clones are an important part of the understory in many eastern woodlands, and may be increasing as a percentage of total stand biomass. Studies in southern New England indicate that most chestnut sprouts originated as seedlings and were never associated with former canopy-dominant trees. The distribution of these sprouts probably reflects the pattern of chestnut seedling establishment in New England at a time when agricultural lands were being abandoned, and forest trees were invading old fields surrounding small woodlots. Woodlands with many logs from former large chestnut trees and few surviving sprouts may indicate that chestnut was not reproducing in some former chestnut stands. These results are used to construct a model for chestnut reproduction as a two-step process, namely seedling establishment followed many years later by the release of suppressed stems. Comparative studies of chestnut and chinquapin indicate that both species possess similar growth forms, but that chestnut exhibits sprouting characteristics suited for survival as a canopy tree, while chinquapin exhibits sprouting characteristics suited for multiple cycles of release and reversion to shrub form. Further insight into the chestnut ecology was obtained by studying the frequency of chestnut pollen in bogs, forest hollows and soils at a site near the modern range limit of chestnut in northcentral Massachusetts. Pollen data from bogs indicates that chestnut increased to approximately 15 percent of the total forest about 2000yr ago, but may have been present at much lower frequencies as much as 4500 yr ago. Pollen data from soils indicate that the regionally averaged chestnut frequency inferred from bog sediments represents the average of large cyclic variations in chestnut at specific locations, with local increases in chestnut pollen following disturbances such as windstorm and fire. These results and other data indicate the abrupt increase in chestnut pollen about 2000 yr ago at most sites in southern New England represents a subtle and complex change in disturbance regime, and is not the simple result of climate Change or delayed migration.

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Author(s): Frederick Paillet

Publication: American Chestnut Proceedings - 1992