Carbon and water relations of Salix monticola in response to winter browsing and changes in surface water hydrology: An isotopic study using δ¹²C and δ¹â¸O
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Authors: K. P. Alstad, J. M. Welker, S. A. Williams, and M. J. Trlica
Date: 1999
Journal: Oecologia
Volume: 120
Number: 3
Pages: 375-378
Summary of Methods: This study was designed to address the physiological factors which may be responsible for poor woody plant regeneration in montane riparian habitats of Rocky Mountain National Park, Colorado. There were two levels of browsing (browsed and unbrowsed) created with the use of grazing exclosures. Beaver use was simulated by damming ephemeral streams to slow stream flow and result in ponding. Carex plants were collected nutrient and δ¹³C analysis. Physiological measurements and water samples were also taken.
Article Summary / Main Points:
• Winter browsing by elk effected the carbon and water relations of Salix, in a few cases proximity to active streams also effected the carbon and water relations.
• Elk browse increased summer plant water potentials and integrative measures of gas exchange. Instantaneous photosynthetic rates and the sources of water measure by the isotope δ¹³C values of xylem water were not affected by elk use.
• Salix derives approximately 80% of its water from streams, in contrast to Carex that receive 50% of their water from rainfall.
• Under mesic conditions browsing may have a positive effect on carbon and water relations of Salix, and competition for water resources with surrounding graminoids and may not hinder water acquisition or carbon fixation.
• Drier conditions may cause Salix plants to likely experience water stress due to the reliance on streams for water, leading to reductions in Salix carbon fixation.
• Decreases in carbon gain may in turn lead to reductions in browsing resistance which would threaten the regeneration of Salix in these ecosystems.Vegetation Types: Other (includes Forest and Eastern) Riparian and Wetlands
MLRA Ecoregions: 48A Southern Rocky Mountains 48B Southern Rocky Mountain Parks
Agrovoc Control Words: Riparian zones Rangelands Wildlife
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: stable isotopes, plant-animal interactions, rocky mountain national park, riparian ecosystems, ungulates
Annotation: The results of this replicated 3 year study are applicable to all rangelands with willows and willow regeneration issues across the Rocky Mountain States. As is true for all grazing research, the results are most directly applicable to areas with similar landscapes, type of herbivore, weather conditions and season of use.
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