Effects of thinning on drought vulnerability and climate response in north temperate forest ecosystems

TitleEffects of thinning on drought vulnerability and climate response in north temperate forest ecosystems
Publication TypeJournal Article
Year of Publication2013
AuthorsD’Amato, Anthony, Bradford John B., Fraver Shawn, and Palik Brian J.
JournalEcological Applications
Pagination1735 - 1742
Date Published12/2013
Keywordsclimate change, growth–climate relationships, Minnesota, Pinus resinosa, USA

Reducing tree densities through silvicultural thinning has been widely advocated as a strategy for enhancing resistance and resilience to drought, yet few empirical evaluations of this approach exist. We examined detailed dendrochronological data from a long-term (>50 years) replicated thinning experiment to determine if density reductions conferred greater resistance and/or resilience to droughts, assessed by the magnitude of stand-level growth reductions. Our results suggest that thinning generally enhanced drought resistance and resilience; however, this relationship showed a pronounced reversal over time in stands maintained at lower tree densities. Specifically, lower-density stands exhibited greater resistance and resilience at younger ages (49 years), yet exhibited lower resistance and resilience at older ages (76 years), relative to higher-density stands. We attribute this reversal to significantly greater tree sizes attained within the lower-density stands through stand development, which in turn increased tree-level water demand during the later droughts. Results from response–function analyses indicate that thinning altered growth–climate relationships, such that higher-density stands were more sensitive to growing-season precipitation relative to lower-density stands. These results confirm the potential of density management to moderate drought impacts on growth, and they highlight the importance of accounting for stand structure when predicting climate-change impacts to forests.