Impacts of salvage logging

Research into the role of salvage logging initially grew out of intense controversy in the Pacific Northwest, regarding the effects of post-fire salvage logging.  We realized that there was little known about post-wind salvage logging in the eastern U.S., and this prompted the M.S. thesis work of Andrea Leach, who compared salvaged and unsalvaged sites after wind damage in Natchez Trace State Forest in central Tennessee.  Her thesis was completed in 2003, and the findings eventually published as Peterson & Leach 2008a (Forestry), and 2008b (Ecological Applications).  The Natchez Trace work was limited to the first two growing seasons after disturbance & salvaging, so necessarily can directly speak only to the initial regeneration. In the papers that came from the NTSF work, we reported what we think is the first attempt to quantitatively document cumulative severity, which combines the natural wind damage with the intensity of the salvage logging operation to estimate the total impact of the two disturbances on a site.

 cumulative severity

However, to our surprise, the salvaged areas did not have any detectable decrease in speed of regeneration or reduction in species diversity; species composition was different in the salvaged areas, but probably because those areas had somewhat greater wind damage than the unsalvaged areas.  We concluded that after moderate severity of natural disturbance, and moderate intensity of salvaging, the expected negative effects were not seen.

In the three sites we are studying in northern Georgia after the April 2011 tornado, we have set up recovery sampling plots in both salvaged and unsalvaged areas, to monitor dynamics of regeneration.

 blowdown

This work is still ongoing and no data have been quantitatively analyzed.  Initial impressions suggest that salvaged areas may differ somewhat in species composition, but that overall rate of regrowth and species richness are not reduced in the salvaged areas.  If these impressions are correct, this further implies that ecosystem functioning in the salvaged areas is not compromised, is has been widely expected.