NE CASC Holds "Biological Thresholds" Workshop

Monday, December 21, 2020

An NE CASC study indicates that the Canadian lynx population will be adversely affected by an approaching threshold--declining snowpack in their Maine habitat.

More than 160 members of the climate adaptation science community participated in a three-day NE CASC science planning workshop, “Biological Thresholds in the Context of Climate Change, ” which took place via Zoom on October 7th, 8th, and 27th. Designed to identify resource management priorities in addressing the potential climate change-induced crossing of biological thresholds—the points at which minor alterations in climatic conditions produce disproportionately large and undesirable responses in species or ecosystems—the workshop attracted representatives from 50 federal or state agencies spanning 21 states.

Impetus for the workshop arose from a recently completed NE CASC capstone project, “Mechanisms for species responses to climate change: Are there biological thresholds?” In this work, an interdisciplinary team of researchers used novel modeling techniques and field data to examine the effect of specific climate variables, land use change, and species interactions on vulnerable species such as songbirds, boreal mammals, and trees. The team found that climate change-driven thresholds are both ubiquitous and impactful for these species in terms of distribution and abundance. Researchers also concluded that attaining an understanding of thresholds and the mechanisms driving them can inform risk assessment for species and help guide short- and long-term management decision making.

Given the relevance of these findings for resource managers, NE CASC researchers and staff—led by an organizing committee that included Thomas Bonnot, Bethany Bradley, Anthony D’Amato, Addie Rose Holland, Toni Lyn Morelli, Richard Palmer, Michelle Staudinger and Jon Woodruff—designed the workshop to further explore the topic of biological thresholds with the broader management community. Relying on a pre-workshop survey and a series of breakout conversations that took place during the workshop, the committee sought to gauge the importance of thresholds to managers, to understand which thresholds and species are of greatest importance to them, and to discuss how NE CASC can support their work in developing or improving strategies for addressing thresholds. “Ultimately, this information-gathering process revealed that while managers are generally concerned about approaching thresholds for a variety of ecosystems and species, they do not currently possess the information required to properly recognize and anticipate these tipping points,” said Anthony D’Amato an NE CASC principal investigator and faculty member at the University of Vermont. “As a result, managers often find themselves in a difficult position because while they obviously want to avoid the negative consequences associated with crossing thresholds, they are also likely uncertain about the actions they should take to prevent this from occurring. Fortunately, NE CASC personnel can assist in filling the existing gaps in our current knowledge of biological thresholds. Drawing on a wide range of expertise, we can co-develop the field experiments and modeling necessary to shed light on this vitally important topic and provide managers with the tools needed to plan effectively.”

D’Amato points to recent NE CASC experiments designed to assess the impacts of varying precipitation regimes on the ability of common Northeastern tree species to establish as an example of how this process might work. “What we’ve found is that some species, such as yellow or black birch, are far more sensitive to water deficits than other species, such as red oak or American chestnut,” said D’Amato. “Consequently, when highly sensitive tree species approach the point at which their mortality rate will vastly increase due to a decline in precipitation, an effective adaptation strategy to maintain forest habitats might involve encouraging the growth of additional red oak or American chestnut. Alternately, if the priority is to maintain the population of these sensitive species, it might be best to thin areas since tree resilience increases as competition for moisture decreases.” In the end, D’Amato says, this experiment illustrates the importance of recognizing the combination of interrelated factors—including precipitation levels, temperature, and forest density—that control movement toward a given threshold. “While fully understanding this complexity is challenging,” he said, “it also helps open possibilities for developing creative management strategies to avoid crossing those thresholds.”

The strong participation in the workshop indicates that NE CASC will have ample opportunities to cultivate similar possibilities for addressing the problems posed by the crossing of biological thresholds in the future. “In planning this event, the organizing committee optimistically hoped that 75 or 80 members of the climate adaptation science community might register for the ‘Thresholds’ workshop,” said Toni Lyn Morelli, a research ecologist for NE CASC. “The fact that more than twice that number of managers and scientists ultimately participated suggests that our center has established a reputation for developing the innovative and actionable science that is essential to tackling the most challenging problems faced by resource managers. The outstanding turnout for the workshop will help NE CASC expand its network of partners, create new opportunities for collaboration, and open new avenues for delivering impactful science where it is needed most. In many respects, the enthusiastic participation of so many members of the climate adaptation science community serves both as an affirmation of our past research and an indicator that even better things lie on the horizon for NE CASC.”

View Biological Thresholds Workshop Proceedings Page >>>