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Transpiration Response of Residual Lodgepole Pine After Partial-cut and Strip-shelterwood Harvesting in Alberta's Southern Rocky Mountains
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- Author / Creator
- Karpyshin, Samantha
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Forest harvesting reduces forest canopy cover which can reduce evapotranspiration and affect the hydrologic regime of watersheds. Prior research has shown while transpiration is reduced by the removal of trees, it can also affect soil moisture and meteorological variables (e.g. temperature, wind, RH) governing water use of un-harvested residual trees. While this may increase transpiration of residual trees after harvesting, this has not been documented in older mature forests that would typically be harvested. Thus, the net affect of harvesting on total transpiration in harvested watersheds remains unclear. This study explores the transpiration response of mature (> 50 years) lodgepole pine (Pinus contorta) where transpiration, soil moisture, and meteorological conditions were evaluated for two growing seasons after partial-cut (PC) and strip-shelterwood (SC) harvesting. While transpiration was greatest during the non-moisture limiting, early growing season compared to the moisture limiting, late season in all stands, transpiration was 60 % greater in residual trees in the PC stand and ~ 40 % greater in the SC stand compared to the reference (un-harvested) stand. Atmospheric moisture demand increased by ~ 10 %, while the shallow soil moisture storage increased by ~ 50 % in the SC stand and in the deeper soil layers by 40 % in the PC stand compared to the reference stand. Spatial patterns in transpiration strongly mirrored the spatial and temporal patterns in these above-ground (atmospheric moisture demand) and below-ground (soil moisture) controls regulating transpiration after harvesting. When changes in post-harvest transpiration rates were scaled up to larger spatial scales, results suggest that increased transpiration by residual trees may compensate for the reduction of transpiration by trees removed during harvesting. This is an important finding, as area harvested may not serve as a direct proxy indicator of potential hydrologic change.
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- Subjects / Keywords
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- Graduation date
- Fall 2019
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.