Mechanisms for species responses to climate change: Are there biological thresholds?

Fiscal Year: 
Project Leader: 
Research Partners: 
Radley Horton (Columbia University); Toni Lyn Morelli (USGS); Frank Thompson (University of Missouri, Columbia)
Project Fellows: 
Science Themes: 

Climate change-driven shifts in distribution and abundance are documented in many species. However, in order to better predict species responses, managers are seeking to understand the mechanisms that are driving these changes, including any thresholds that might soon be crossed. We will leverage the research that has already been supported by the Northeast Climate Science Center (NE CSC) and its partners and use the latest modeling techniques combined with robust field data to examine the impact of specific climate variables, land use change, and species interactions on the future distribution and abundance of species of conservation concern. Moreover, we will document biological thresholds related to climate variability and change for critical species in the Northeastern and Midwestern U.S. Our objectives are to identify the primary drivers (climate change vs. urban growth) of species distribution changes in the Northeast; examine the nature of species landscape capability change over time to identify potential thresholds; determine how changing temperatures and snowpack characteristics will drive species interactions; determine the sensitivity of tree and bird responses to the magnitude, variability, periodicity, and seasonality of temperature and precipitation under climate change in the eastern U.S.; and develop projections based on discrete climate triggers that have been linked to known biological thresholds; and identify how discrete climate triggers such as extreme events will correlate with known biological thresholds. Focal species will include eastern tree species, songbirds, moose, Canada lynx, snowshoe hare, and southern pine beetle. Major outcomes will include 1) knowledge of the mechanisms that drive projected changes in the distribution of vulnerable wildlife and tree populations that will enable better assessment of vulnerability and adaptation planning; and 2) improving how these results are conveyed to stakeholders by identifying understandable responses in the form of thresholds.

Preliminary Results

  • (Griffin/DeLuca) When considering the 31 representaive species of focus for the DSL project in the northeast, it is more likely that southern species landscape capability is influenced by future development than climate change. However for more northern species, landscape capability is influence by both climate change and future development.
  • (Horton/Lesk) Yields of corn and soy in the northeast are found to be negatively affected by exposure to extreme hourly precipitation, as well as to anomalously large amounts of drizzle.  Moderate rainfall is found to benefit crop yields.
  • (Morelli/Siren) Species along southern range edges have positive association with snow and those on northern boundaries have negative relationship. Competitive interactions are present in at least 5 species pairs.
  • (Thompson/Bonnot/Fraser) Changes in monthly precipitation and maximum temperature generally had the largest effects on tree species.  Simulated increases in daily maximum temperature 4°C or more often resulted in 50% or greater reductions in biomass and stems.  In some instances species at the southern extent of their range (e.g., sugar maple in the Missouri Ozarks) failed to grow, suggesting the potential for local extirpation under those conditions. These results suggest that, when isolated, changes in total precipitation or temperature inherent in climate warming projections can exceed species thresholds for growth and thus would have the greatest potential for impacts.
  • American Ornithological Society meeting, Anchorage, AK, June 2019
  • Annual Wildlife Society Meeting in Reno, NV. 2019.
  • Canada Lynx Post-Delisting Monitoring Plan Meeting, Portland, ME, April 9-10, 2019
  • New England Society of American Foresters meeting, Burlington, VT, March 2019
  • ​American Ornithological Society, April 2018