John D. Waldron

Simulating the reciprocal interaction of forest landscape structure and southern pine beetle herbivory using LANDIS

The reciprocal interaction of landscape structure and ecological processes is a cornerstone of modern landscape ecology. We use a simulation model to show how landscape structure and herbivory interact to influence outbreaks of southern pine beetle (Dendroctonus frontalis Zimmermann) in a landscape representative of the southern Appalachian Mountains, USA. We use LANDIS and its biological disturbance agent module to simulate the effects of landscape composition (proportion of landscape in host area) and host aggregation on the size and severity of insect outbreaks and the persistence of the host species, Table Mountain Pine (Pinus pungens Lamb.). We find that landscape composition is less important in the modeled landscapes than host aggregation in structuring the severity of insect outbreaks. Also, simulated southern pine beetle outbreaks over time tend to decrease the aggregation of host species on the landscape by fragmenting large patches into smaller ones, thereby reducing the severity of future outbreaks. Persistence of Table Mountain pine decreases throughout all simulations regardless of landscape structure. The results of this study indicate that when considering alternative restoration strategies for insect-affected landscapes, it is necessary to consider the patterns of hosts on the landscape as well as the landscape composition.

Restoration of Southern Pine Forests After the Southern Pine Beetle

The southern pine beetle (Dendroctonus frontalis Zimmermann) is the most destructive insect pest of pine (Pinus spp.) forests in the southern United States. Restoring and managing pine stands infested by southern pine beetle are critically important for forest health and sustainability in the region. The successful restoration of damaged pine forests requires the integration of information of beetle biology and behavior, pine ecology, and landscape restoration. Certain social, economic, and political issues also need to be considered concomitantly. The knowledge for effective restoration and management of southern pine forests has increased greatly in the past decade. In this chapter, we provide a synthesis of new and existing knowledge to address the goals, framework, implementation, social and political impacts on the restoration of the southern pine forests in the context of southern pine beetle. We also provide information on common restoration methods and cost estimates. More effective use and further development of such knowledge could substantially reduce the economic, ecological, and social impact of southern pine beetle within the southern United States and adjacent areas.