PARTNERS: University of Maryland Center for Environmental Science, USDA Forest Service Northern Research Station

SUMMARY: Significant consequences result when landscapes are converted from natural areas to those used intensively by humans, which affect many species of plants and animals and alter the productivity and services provided by forest ecosystems. The viability of populations living within fragmented landscapes depends on species-specific dispersal characteristics and structural features of the landscape that link otherwise isolated habitat patches. Collaborative activities were proposed in June 2006 that would assess the consequences of landscape change on the dispersal success of forest-dwelling species to result in: the development of analysis protocols including refinement of efficient dispersal algorithms to establish standard methods for analysis; the use of matrices summarizing landscape dispersal success to characterize network and metapopulation dynamics in fragmented landscapes; and landscape-scale consideration of effective corridor design and restoration. The results of this work are expected to be directly applicable to Forest Service resource assessments and land management activities within the Chesapeake Watershed as well as at national scales.     

STATUS: Ongoing

PROGRESS: In 2007, the reintroduction of the Delmarva Fox Squirrel, a forest obligate endangered species threatened by forest fragmentation, was chosen as the first case study. Using information on its life-history and dispersal characteristics, together with data on the composition and configuration of land cover on the Delmarva Peninsula, an individual-based simulation model (J-walk) was used to simulate the dispersal of millions of squirrels among potentially sustainable habitat patches. The large volume of output generated by the model was specifically tailored for synthesis and visualization using mathematical morphology (Vogt et al. 2009) and graph theory (Lookingbill et al. in review). The generality of the methods and their potential application to modeling the spread of exotic species in fragmented forests were the topics of a special symposium at the 2008 US-IALE Conference on Landscape Patterns and Ecosystem Processes (http://www.usiale.org/madison2008/session_presentation.php?id=3d). A paper describing the analysis of simulated exotic plant invasions using graph theory is in press in Biological Invasions.

Vogt, P., J. R. Ferrari, T. R. Lookingbill, R. H. Gardner, K. H. Riitters, and K. Ostapowicz. 2009. Mapping functional connectivity. Ecological Indicators 9:64-71. doi:10.1016/j.ecolind.2008.01.011 http://dx.doi.org/10.1016/j.ecolind.2008.01.011

Lookingbill, T. R., R. H. Gardner, J. R. Ferrari, and C. E. Keller. in review. Network analysis of critical connectors and habitat for the recovery of the Delmarva Fox Squirrel. Ecological Applications.

Ferrari, J. R., and T. R. Lookingbill. 2009. Initial conditions and their effect on invasion velocity across heterogeneous landscapes. Biological Invasions. doi:10.1007/s10530-008-9330-2 http://dx.doi.org/10.1007/s10530-008-9330-2 

LINKS:

University of Maryland Center for Environmental Science

USDA Forest Service Northern Research Station

CONTACT:

• Robert H. Gardner, Appalachian Laboratory, University of Maryland Center for Environmental Science, gardner@al.umces.edu or (301) 689-7125 
• Todd Lookingbill, Appalachian Laboratory, University of Maryland Center for Environmental Science, tlookingbill@al.umces.edu or (301) 689-7203