Given the potential threat posed by climate change to the functioning and health of forested ecosystems, we conducted research to evaluate the efficacy of using stand density management in the form of thinnings to reduce the negative impacts of increasing temperatures and drought stress on tree growth. This research was conducted within managed and unmanaged red pine (Pinus resinosa Ait.) forests; forest types with high economic value and considerable ecological importance across the region. Dendrochronological methods were employed to assess the impacts of climatic events on forest stands with differing thinning histories. Tree ring growth was compared to historical monthly weather data including maximum temperature, minimum temperature, and precipitation to identify weather events and seasonality that impacted tree growth. Response function analysis was used to identify weather events and seasonality that were significant ( =0.05) drivers of tree ring increment over the study period (1960-2012). Additionally, an investigation of stand level characteristics related to this response was conducted by comparing mean sensitivity of tree ring growth to stand structural attributes, including quadratic mean diameter, mean stand age, and stand density index. We found evidence that stands with history of thinnings were less negatively impacted by later summer temperature extremes and precipitation deficit. We also found significant positive relationships between quadratic mean diameter, stand age, stand density index and mean sensitivity, suggesting greater sensitivity to climate in dense forests composed of older and larger trees. These results suggest that forest managers can alter stand structure using partial harvests to minimize negative climate impacts on tree growth within managed forest.
This research was supported by the Undergraduate Research Opportunities Program (UROP).
Evaluating climate the sensitivity of red pine (Pinus resinosa Ait.) in managed forests of northern Minnesota: an investigation of stand and management factors influencing responses..
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