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Harvard Forest REU Symposium Abstract 2019

  • Title: Climate Sensitivity in the Transitional Forest: A Betula Gradient Study
  • Author: Sophia PItney (University of Wisconsin - La Crosse)
  • Abstract:

    The forecasted impacts of climate change on forests in the Eastern U.S. are highly variable, models predict shifts in species composition, significant dieback and mortality, or little to no change. This uncertainty is especially prominent at the Harvard Forest in New England, located in the transitional forest where two major forest types meet. Three Betula species—papyrifera and alleghaniensis prominent in the north, and lenta prominent in the south—coexist in the Transitional Forest. This provides a unique opportunity to study climate sensitivity within one genus. In this study, I used tree growth and PRISM climate data to investigate how these species are responding to climate and competition in two different landscapes (flat and mesic/slope and dry). Study trees ranged in age from 60 to 140 years and ranged in canopy position from suppressed to dominant. While cross-dating, all three species exhibited missing and false rings, which made dating difficult, which can indicate Betula species have highly individualistic responses to climate. We found that B. papyrifera in the flat, mesic site is negatively correlated with summer temperatures minimums, while in the dry, slope site is positively correlated with March precipitation. B. lenta on the slope site is negatively correlated with June temperature maximums, and B. alleghaniensis on the mesic site is positively correlated with summer PDSI (Palmer Drought Severity Index). Gaining a deeper understanding of Betula species’ climate sensitivity will improve predictions about the future challenges experienced by the New England forests due to climate change.

  • Research Category: Physiological Ecology, Population Dynamics, and Species Interactions