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Harvard Forest REU Symposium Abstract 2018

• Title: An exploration of lichen communities within Harvard Forest in relation to changing tree demographics
• Author: Meghan-Grace P Slocombe (Greenfield Community College)
• Abstract:

  The increased mortality among hemlock populations in concurrence with the spread of the hemlock woolly adelgid, calls for an exploration of how changing tree demographics will affect the ecosystem as a whole. While there have been studies that focus on the effects of losing hemlock populations in Northeastern forests, there has been nearly no research on how a shifting tree demographic will result in altered regional lichen communities. In order to better understand the future lichen communities that might be found in these forests, and their potential impact on nutrient cycling, this study compares the varying species and percent cover of lichen on red maple (Acer rubrum, n=30), red oak (Quercus rubra, n=30), and hemlock (Tsuga canadensis, n=20) tree stems. The average lichen coverage of red oaks was approximately ten percent, red maples approximately nine percent and the coverage on hemlocks was approximately two percent. The average species richness of lichen found on red maples and red oaks was nearly double that found on hemlocks. Lichen community composition was also analyzed using non-metric multidimensional scaling. The data supports the idea that more lichen will be able to colonize tree stems as hemlock populations dwindle and hardwoods take their place. This increase in lichen biomass could increase the rate at which certain nutrients are cycled because of lichens’ ability to absorb and fix nitrogen. This potential increase in useable nitrogen within the ecosystem could also increase an ecosystem’s ability to gain biomass and thus store carbon.

• Research Category: Biodiversity Studies