Document: MAT-3-40-44

Replacement of eastern Hemlock (Tsuga canadensis) in the Black Rock in the Hudson Highlands of New York.

MATES-MUCHIN, J.T.* ¹, J.D.LEWIS ¹ and W.SCHUSTER ²

Fordham University, Armonk, NY 10504 USA ¹
Black Rock Forest Consortium, Cornwall, NY 12518 USA ²

Abstract:
The eastern hemlock (Tsuga canadensis) is declining in the northeastern United States due to the spread of the hemlock woolly adelgid (HWA), Adelges tsugae, an invasive exotic parasite. To examine potential stand-level changes in species composition associated with this decline, we surveyed nine 0.16 ha plots in one watershed in Black Rock Forest in the Hudson Highlands of New York. The HWA first appeared in this stand approximately 10 years ago, and currently hemlock mortality within the stand ranges from 0% to 17% per plot. In hemlock dominant and co-dominant plots, the most common hardwood species are Quercus prinus (chestnut oak), Quercus rubra (northern red oak) and Acer rubrum (red maple). Chestnut oak and northern red oak abundance varies from 1% to 65% in each plot and are co-dominant with hemlock in the overstory and understory. Red maple accounts for 2% to 30% of the trees and is primarily in the understory. These species will likely replace the hemlock based on their current relative abundance. Although Betula lenta is 15% or less of the trees in each plot, it is likely to increase in abundance based on its colonization ability. The patchy distribution of hemlock mortality within this forest is likely to result in differential reductions in net primary productivity at the sub-stand level. Additionally, the conversion of hemlock-dominated forest to hardwood dominated forest is likely to significantly alter ecosystem processes.

Keywords: birch, community composition, eastern hemlock, herbivory, hemlock woolly adelgid, invasive parasite, oak, red maple, succession

This abstract is being presented at: 3:30 PM in session:
Poster Session #17: Vegetative Analysis.