Date of Award

2020

Document Type

Masters Thesis

Degree Name

M. S.

Organizational Unit

Biological Sciences

First Advisor

Patrick H. Martin, Ph.D.

Second Advisor

Anna Sher, Ph.D.

Third Advisor

Michael Kerwin, Ph.D.

Keywords

Conifer, Subalpine, Drought

Abstract

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.

Publication Statement

Copyright is held by the author. User is responsible for all copyright compliance.

Rights Holder

Alex Goke

Provenance

Received from ProQuest

File Format

application/pdf

Language

en

File Size

58 p.

Discipline

Ecology, Biology, Plant sciences

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