Forest insects have significant direct impacts on forest ecosystems; they are also generating new risks, uncertainties, and opportunities for forest landowners.  The objectives of this project were to understand: (1) whether and how invasive insects are shifting land-use regimes in New England by altering human decision-making, and (2) how these changes to human decisions may affect regional forest ecosystems and ecosystem services. 

Our first step was surveying forest landowners in the northeast to ask them how they would respond to a series of hypothetical insect infestation scenarios on their land. Each respondent was presented with four scenarios based on differing insect attributes and asked if they (or someone they hired) would harvest trees targeted by the insect and how certain they were of their response for each scenario. Eighty-four percent of respondents indicated they would consider harvesting for at least one of the four scenarios presented, and 67% of respondents were certain of their intent. Harvest intention increased with greater insect-related tree mortality. Landowners with larger holdings, who had previously harvested forest products, and live on their forestland had greater intentions to harvest in response to insects.

Next, to understand how landowners? response to insects might impact the region?s forests, we created a typology of owner responses then developed a map of the landowner types. To do this, we first grouped land owners based on patterns of survey responses and compared and contrasted each group with respect to survey-reported age, education, income, and other individual- or household-level demographics. We then developed a statistical model that predicts group membership as a function of geographic features, allowing us to map landowner group probabilities across the landscape. 

We then used this map of landowner types along with regional forest inventory data to predict the harvest response to the emerald ash borer, a new rapidly spreading invasive insect in the region. Our analysis suggests that 25% of the woodland parcels in the Connecticut Watershed may intend to harvest in response to emerald ash borer. If the emerald ash borer continues to spread at its current rate within the region, and therefore the associated management response occurs in the next decade, this could result in an increase in harvest frequencies, from 2.6% per year to 3.7% per year, through to approximately 2030. 

Simultaneously, we examined how the emerald ash borer affected harvesting in the MidWest, where the insect has been present for much longer. We investigated the influence of the highly impactful emerald ash borer on the annual probability of harvest, the intensity of harvest, and the diameter of harvested trees, for both ash and non-ash species on private land. We found that emerald ash borer detection had a negative impact on annual harvest probability, and a positive impact on harvest intensity, resulting in a net increase in harvested biomass. Furthermore, our estimates suggest that emerald ash borer detection will influence private landowners to harvest greater quantities of ash, relative to non-ash species. We also found that harvested trees in emerald ash borer-infested areas had smaller diameters, on average, compared to those unaffected by emerald ash borer. 

Our research has helped forest policy makers and managers. We created guides for extension agents to help inform land owners about how insects might affect harvest regimes. This research was also an important part of undergraduate and graduate education. Two undergraduates (one at Hunter College and one at University of Massachusetts) wrote their senior thesis using data and models from the project. Also, one PhD student at Duke conducted much of the research as part of his disertation.  

Last Modified: 04/19/2022
Modified by: Jonathan R Thompson