Source/Sink Dynamics Projects

Background

DoD lands provide the best available habitat for numerous threatened, endangered and at-risk (TER-S) 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, and DoD resource managers can manage these disturbances with techniques that are difficult or impossible to employ on private lands. Restoration of habitat is another technique that may improve conditions for these species. Ideally, such management creates population sources (where births exceed deaths) that increase metapopulation viability. However, habitat management often has both beneficial and detrimental effects on populations of TER-S species. For example, where fires are necessary in grasslands to control woody plants and improve habitat quality for wildlife, those fires often kill animals, particularly less mobile juveniles. In this case, too-frequent management runs the risk of creating sinks (where deaths exceed births) rather than sources. Additionally, restoration and management have the potential to create ecological traps - habitat that animals perceive as high-quality, but acts as a population sink. Our work focuses on temporal change in habitat quality following management or restoration that may lead local habitat patches to cycle from sink to source status and back.