Pining for pine barrens

Heuss, M., D’Amato, A. W., & Dodds, K. J. (2019). Northward expansion of southern pine beetle generates significant alterations to forest structure and composition of globally rare Pinus rigida forests. Forest Ecology and Management 434, 119-130. PDF

Summary

Climate change has enabled the range of some forest insects to expand into novel ecosystems. The highly aggressive southern pine beetle (SPB) is one such insect that recently expanded northward from its native habitat of pine-dominated forests in the southeastern United States to the globally rare pitch pine barrens of the northeast. Heuss et al. (2019) examined the effects SPB infestation alone and in combination with management actions designed to address SPB (cut-and leave suppression, which entails cutting SPB infested trees and a buffer of healthy trees surrounding infestations) on the structure and composition of the Central Pine Barrens of Long Island, NY. The study found that SPB infestation and management reduced the amount of pitch pine within stands, but that management effectively reduced pitch pine mortality. Infestation and management did not impact tree regeneration which was largely composed of hardwood species. There were significantly more standing dead trees within infested stands, but downed woody materials volumes were greatest in managed stands. The results of this study suggest that, in absence of restoration efforts, SPB could functionally eliminate pitch pine from infested areas. This loss of pitch pine exacerbates the long-term succession toward hardwood dominance and away from barren conditions. However, combining fuel reduction treatments with pine barren restoration may effectively reduce fire hazard while increasing resilience to SPB.

Take home points

  • SPB presents a serious threat to the northeastern pitch pine barrens.

  • Cut-and-leave management can reduce SPB-induced pitch pine mortality, but preemptive restoration management is a more effective strategy for maintaining pine dominance.

Management implications

  • SPB may exacerbate the conversion of pine barrens to hardwood-dominated communities and could functionally eliminate pitch pine from infested stands.

  • Without direct management efforts, substantial pitch pine recruitment is unlikely.

  • Through the creation of dead woody material, SPB may increase forest fire risk.

  • Combining fuel reduction treatments with pine barren restoration may effectively reduce fire hazard while increasing resilience to SPB. This type of management can be preemptively applied to uninfested pine barrens to reduce susceptibility to infestation.

Keywords

Range Expansion; Impact Study; Dendroctonus frontalis; Pinus rigida; Pine barrens