Document: ELI-3-69-18

The interactions of multiple disturbances: Effects on northern hardwood forest community structure.

HANE, E.N.*

Brown University, Providence, RI 02912, USA ¹

Abstract:
The northern hardwood forest has seen a recent explosion of understory beech saplings (Fagus grandifolia) due to the presence of an exotic disease, beech bark disease. Removal experiments of beech saplings have shown that 40% of the mortality of sugar maple (Acer saccharum) seedlings is due to the presence of beech. Shading experiments show that while a large proportion of the negative effect of beech on sugar maple is from shading, allelopathy provides an alternative explanation. Greenhouse allelopathy experiments show that sugar maple seedlings exposed to beech leaf leachate have significantly lower biomass and leaf area than those which get the same nutrients, but without the secondary compounds that exist in the beech leaf leachate. The shift in understory community structure is particularly important after the ice storm of January 1998, which created many new canopy gaps. The severity and density of beech bark disease, and thus beech thicket sprouting, depends largely on land-use history, with areas that were previously logged having the highest density of beech saplings, and areas which were managed for sugar maple syrup production having the lowest. The severity of the ice damage is correlated with the density of beech, and also with the degree of beech bark disease damage. The interactions of all these disturbances (land-use, beech bark disease and ice storm) indicate that beech will be increasingly important in the future, and at the expense of sugar maple.

Keywords: disturbance, northern hardwood forest, land-use

This abstract is being presented at: 8:30 AM in session:
Oral Session #42: Disturbance Ecology: Effects of Storms.