Strategies for forest resilience in the face of environmental change

Forestry-related businesses in the Northeast support 1.5 million jobs and generate more than $12 billion per year. Regional forests are highly valued for income and for many other ecosystem services, including beauty, nature, privacy, and as an inter-generational resource.  However, Northeastern forests are threatened by climate change, which is bringing higher temperatures, greater diversity and survival of pests and diseases over winter, and introduction of harmful invasive species. 

The primary focus of this research was understanding the influence of retaining treetops and branches in forests after a partial harvest. We investigated the impact of such retention on tree seedling establishment and subsequent growth, on woodland insect pollinators and on soil invertebrate communities. We identified and measured more than 500 tree seedlings and saplings of many species in Cornell University forests in the vicinity of Ithaca, NY. All trees selected had germinated after a prior forest thinning and were either surrounded by piles of woody material from treetops and branches, or were in nearby plots devoid of wood on the forest floor. In subsequent years, we re-measured 175 of those tagged trees to compare size, survival, and growth rates. We also observed and collected insects in a forest site that was moderately thinned 12 years previously and a forest site that was heavily thinned seven years before. In addition, we collected and analyzed soil cores at five forested stands and compared the species diversity and abundance of soil-dwelling invertebrates in large treatment plots where all treetop material was removed, and plots where moderate-sized and large-sized treetop material was retained.