Knowledge of tree species’ ability to tolerate drought is necessary to anticipate future forest dynamics with climate change, especially at the seedling stage given their role in shaping forest structure. We used precipitation reduction shelters to mimic drought for subalpine conifer seedlings (A. lasiocarpa and P. engelmannii) in the Rocky Mountains and compared survivorship and morphological and physiological responses to assess relative degrees of drought tolerance. We detected no significant investment in morphological tolerance traits (e.g. root biomass, leaf:stem area ratio) but substantial reductions in net photosynthesis. While shading partially ameliorated drought effects when precipitation reduction was moderate, complete exclusion caused declines in survivorship in both sun and shade tied to poor carbon balances. We identified a lack of stomatal control as a driver of physiological decline in seedlings suggesting a prioritization of traits that, while useful for early establishment, may portend substantial vulnerability of seedling populations to future drought.
","abstract_html":"<p>Knowledge of tree species’ ability to tolerate drought is necessary to anticipate future forest dynamics with climate change, especially at the seedling stage given their role in shaping forest structure. We used precipitation reduction shelters to mimic drought for subalpine conifer seedlings (<em>A. lasiocarpa</em> and <em>P. engelmannii</em>) in the Rocky Mountains and compared survivorship and morphological and physiological responses to assess relative degrees of drought tolerance. We detected no significant investment in morphological tolerance traits (e.g. root biomass, leaf:stem area ratio) but substantial reductions in net photosynthesis. While shading partially ameliorated drought effects when precipitation reduction was moderate, complete exclusion caused declines in survivorship in both sun and shade tied to poor carbon balances. We identified a lack of stomatal control as a driver of physiological decline in seedlings suggesting a prioritization of traits that, while useful for early establishment, may portend substantial vulnerability of seedling populations to future drought.</p>","abstract_has_math":false,"creators":["Goke, Alex"],"institution":null,"degree_name":"M. S.","degree_level":"Masters Thesis","degree_discipline":null,"degree_department":null,"school":null,"contributors":["Patrick H. Martin, Ph.D.","Anna Sher, Ph.D.","Michael Kerwin, Ph.D."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2020,"date_issued":"2020-01-01T08:00:00Z","date_published":"2020-01-01T08:00:00Z","updated_at":"2026-07-24T02:03:35Z","subjects":["Conifer","Subalpine","Drought","Ecology and Evolutionary Biology","Forest Biology","Life Sciences","Other Ecology and Evolutionary Biology","Plant Biology","Plant Sciences"],"languages":["en"],"rights":["Copyright is held by the author. User is responsible for all copyright compliance.
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"],"dc:format":["application/pdf"],"dc:identifier":["https://digitalcommons.du.edu/etd/1769"],"dc:language":["en"],"dc:rights":["Copyright is held by the author. User is responsible for all copyright compliance.
"],"dc:subject":["Conifer","Subalpine","Drought","Ecology and Evolutionary Biology","Forest Biology","Life Sciences","Other Ecology and Evolutionary Biology","Plant Biology","Plant Sciences"],"dc:title":["Subalpine Forest Tree Seedling Response to Drought"],"thesis:degree_level":["Masters Thesis"],"thesis:degree_name":["M. S."]},"updated_at":"2026-07-24T02:03:35Z"}