Date of Award

2021

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Natural Resources

First Advisor

Anthony W. D'Amato

Abstract

Over the past several decades, the United States has been experiencing an influx of nonnative pests due to increased globalization, and many of these pests have the potential to permanently alter the composition, structure, and function of forests. Asian longhorned beetle (ALB) is an invasive pest that came into Worcester county, MA in 2008, where the first instance of this species invading both urban and natural forested areas was documented. Within the quarantine area for this novel invasion, 30,000 trees were removed over the course of 10 years as part of management efforts focused on harvesting all host species, primarily Acer spp., to prevent ALB spread. While there is great confidence in the effectiveness of these eradication measures, little is known how these natural forests will recover over time. To address this knowledge gap, we examined forest compositional and structural development following three different eradication treatments (full host removals, herbicide, and stump grinding) and patterns with adjacent unimpacted areas. Overall, the results of our observational study found that forests were recovering following similar pathways documented after other disturbances in southern New England forests. There was little difference between eradication treatments in terms of forest composition and structure. Overall, forest types shifted to primarily oak-hickory or pine dominance following the removal of all Acer spp. Most notably, maple species were returning in high numbers in the regeneration layer across all treatments followed by other early colonizing species, including white pine, and black birch. Red maple was the most abundant species for saplings and seedlings and accounted for 43.4% of the sapling layer and 37.1% of the seedling layer across treatments. The density and composition of the regeneration layer did not vary by forest or treatment type. Red maple stump sprouting was documented at 60% of sites but was not found in the control plots. Additionally, invasive plant species represented a small portion of the herbaceous layer constituting 14% of the unique species recorded. Shannon’s diversity of the herbaceous layer differed by forest type, but there was no difference between proportions across treatments. The results of this study suggest that ALB management does not drastically alter forest compositional dynamics in the short term.The second portion of this project examines the long-term effects of ALB management on forests in Worcester county and Cheshire county, New Hampshire using LANDIS-II, a spatially explicit forest vegetation model that incorporates forest inventory data and climate scenarios. We modeled the effects of ALB management on these forests under three low to high emission climate scenarios. Management scenarios included business-as-usual (BAU), partial host (Acer removed), and full host removals (Acer and Betula spp. removed.) We found that climate had a more pronounced effect on final year aboveground biomass than management type. At the final year of simulation across all simulations, white pine, white oak, and red oak were in high abundance. Under BAU management, sugar maple and black birch were in high proportions as well. Overall, the results of these simulations show that under ALB management, forest recovery is dictated by climate more so than host removals. In combination, these studies contribute to our understanding of the short and long-term impacts of Asian longhorned beetle and climate change on forests in southern New England. Practitioners can employ ALB management and confidently expect forests to recover.

Language

en

Number of Pages

114 p.

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