DoD lands provide remarkably important habitat for numerous threatened, endangered and at-risk species. Many of these species do best on DoD lands because they require disturbance-dependent habitats such as those created by fires and localized floods. DoD resource managers can manage these disturbances with techniques that are difficult or impossible to employ on private lands. Ideally, such management creates population sources that increase metapopulation viability; however, a sophisticated understanding of population dynamics is required for success because too-frequent disturbance runs the risk of creating population sinks. As a result, there has been a long-standing research need to collect the data necessary to assess the source-sink consequences of habitat disturbance management and restoration.
Dr. Elizabeth Crone from Tufts University and her team led a SERDP funded project that investigated the source-sink dynamics of species being managed on military lands using three species of endangered butterflies. The team measured demography and movement at all phases of the disturbance cycle following management or restoration. They then used these data to parameterize detailed spatially explicit individual-based simulation models linked to real landscapes with dynamic changes in habitat quality due to management. Finally, the team validated their general approach by comparing patterns in the focal species to general, cross-taxa, patterns.
This project resulted in significant and important findings. For the focal species work, researchers found that, in most cases, habitat restoration created “source” habitat. In all cases, restoration had both positive and negative effects on individual vital rates, but to fully understand population health, it was necessary to integrate these effects across the life cycle to calculate the net effects of restoration. The team further discovered that animals tend to have faster movement in lower-quality habitat. This pattern means that matrix and sink habitat may increase connectivity in mixed-use landscapes even when it does not enhance population viability.
For this significant work, Dr. Crone and her team received the 2018 SERDP Project-of-the-Year Award for Resource Conservation and Resiliency for their project titled, Endangered Butterflies as a Model System for Managing Source-Sink Dynamics on Department of Defense Lands.