The Effects of Intensive Eradication Efforts for Asian Longhorned Beetle on Understory Plant Communities, Tree Regeneration, and Forest Structure in Southern New England Hardwood Forests

Asian longhorned beetle (ALB) is an invasive forest pest that attacks hardwood species, particularly maple. The pest was found in Worcester (MA) in 2008, and the area subsequently experienced one of the largest ALB invasions in the USA. In response, forest managers enacted a quarantine around the infected area and implemented a variety of treatments to contain and eliminate the pest. Their strategies included full host treatments–removal of all host species from saplings to pole size–and additional herbicide applications as well as stump grinding to minimize stump sprouting. 

A study conducted by a team of researchers including NE CASC Principal Investigator Anthony D’Amato examines the impacts of these treatments five to eight years after management interventions in the area. Their findings are presentied in a new article, “The effects of intensive eradication efforts for Asian longhorned beetle on understory plant communities, tree regeneration, and forest structure in southern New England hardwood forests,” published in Forest Ecology and Management. 

The study focuses on three key issues: the presence of host species in the regeneration layer and the overstory; the presence of invasive species in the herbaceous layer; and the impact of treatments on forest composition and structure. Using standardized forest sampling protocol, the team sampled across forest type and treatments. Ultimately, it found that treatments did not significantly impact forest recovery. Rather, the legacy of land use in the area and existing forest composition dynamics played the largest role in shaping the forest as it is today. The team also found that regeneration was likely influenced by the species present in the overstory, and conditions favored species that grow well in disturbed soils, such as red maple and white pine. Invasive species represented a small portion of the herbaceous layer and were not significantly related to the treatments; the seedbank likely influenced the composition more than treatments. Forests appeared to be moving towards oak-hickory composition, a type that is abundant in this area and likely to continue to be so under future climate conditions. 

Treatments for ALB are considered highly effective in eliminating the pest, and this study indicates that these interventions do not greatly impact forest recovery compared to other factors.