GR salvage

How does salvage logging alter ecosystem function of insect-disturbed forests?

Collaborators:  Monica Turner & Martin Simard (University of Wisconsin Madison)

Cooperators:    Bridger-Teton National Forest; University of Wyoming

Summary: Ecosystem management inevitably involves tradeoffs among ecosystem services.  In managed forest ecosystems, interactions between the provisioning services of timber and fiber supply, the regulating service of forest fire protection, and the supporting services of soil fertility and regeneration represent a significant challenge in the face of widespread forest disturbance.  Salvage logging is a common management practice following insect outbreak, often done to recover economic value or treat a perceived increase risk of fire.  Insect and logging disturbances differentially affect ecosystem components; salvage has a larger impact on the forest canopy than insects alone, and additional impacts on soil and understory plants that insect outbreak does not (Figure 2). Thus, the compound disturbances of beetles and salvage could yield different ecosystem responses compared to beetles alone and, therefore, impact a different combination of ecosystem services. Through cooperation with the USFS, I was able to use a before-after-control-impact experimental design to test the effects of salvage logging on 1) tree regeneration, 2) fuel loading, and 3) N cycling in beetle-killed forests.  Salvage had the greatest effect on fuels by decreasing canopy loads and increasing surface loads.  Salvage had moderate effects on sapling density in beetle-killed stands, including a reduction in total density and differential impacts by tree species, however changes in sapling density are unlikely to change stand successional trajectories.  Salvage had little to no short-term effect on litter-soil N cycling. Rather, salvage-logged stands followed a similar pattern of N cycling changes over time to those seen in beetle-killed stands without salvage.   Results of this work are directly applicable to forest management efforts to balance ecosystem services, and suggest that salvage operations may not be needed to reduce the risk of severe crown fire in beetle-killed forests, but also do not severely impact short-term regeneration or litter-soil N dynamics. (See Griffin et al. in press; This work was completed with funding from the United States Forest Service Western Wildlands Environmental Threat Assessment Center.)