This was presented by Colby Bosley-Smith as a part of a series of contributed talks from the 2022 FEMC Annual Conference. To learn more about the conference, visit: https://www.uvm.edu/femc/cooperative/conference/2022. Understanding the influence of post-disturbance forest management practices on tree regeneration is critical for assessing ecosystem recovery and guiding future responses. Forests often show remarkable resilience to disturbance through recovery of fundamental structures and processes. Evidence suggests that ecosystem processes frequently remain relatively stable despite events prompting clear structural reorganization. While necessary for retrieval of lost timber revenue, post-disturbance management responses such as salvage logging may exacerbate disturbance impacts and disrupt or delay these natural processes. This study seeks to evaluate how salvage logging influences microsite and regeneration outcomes.
In July 2013, a rare tornado in northcentral Maine and subsequent salvage logging created an ideal situation in which to evaluate these influences. This series of events generated three clear "treatments": tornado blowdown, blowdown followed by salvage logging, and an undisturbed control. Nine years post-tornado, we inventoried tree regeneration within these treatments (16 plots per treatment) to examine differences in sapling abundance, species composition, and size structure. On these same plots, we also inventoried downed coarse woody debris (CWD), including height of each debris piece above the forest floor. Each sapling was evaluated for evidence of moose browse to determine whether abundant CWD in the blowdown created a 'caging effect,' thereby impeding access and browse by moose. Further, LiDAR data were analyzed to test for differences in canopy openness among treatments. Results revealed greater sapling abundance in the disturbed treatments compared to the control, but no apparent differences in sapling composition or size class. This difference in sapling abundance can be explained by lower canopy openness in the control, as evidenced by LiDAR data. The primary difference between blowdown and salvage was the observed 'caging effect'; that is, the greater volumes and heights of CWD in the blowdown translated to lower proportions of browsed saplings compared to the more structurally simple salvage treatment. Reduced browse in the blowdown may have implications for successional trajectories and future stand development. These results provide greater understanding of ecosystem recovery processes following the successive disturbances of blowdown and salvage logging.