Western Washington University Western CEDAR WWU Graduate School Collection WWU Graduate and Undergraduate Scholarship Winter 2016 Black Cottonwood (Populus Trichocarpa) Nutrition in the Dewatered Lake Aldwell Reservoir on the Elwha River, Washington Ezra H. Citron Western Washington University, [email protected] Follow this and additional works at: https://cedar.wwu.edu/wwuet Part of the Environmental Sciences Commons Recommended Citation Citron, Ezra H., "Black Cottonwood (Populus Trichocarpa) Nutrition in the Dewatered Lake Aldwell Reservoir on the Elwha River, Washington" (2016). WWU Graduate School Collection. 466. https://cedar.wwu.edu/wwuet/466 This Masters Thesis is brought to you for free and open access by the WWU Graduate and Undergraduate Scholarship at Western CEDAR. It has been accepted for inclusion in WWU Graduate School Collection by an authorized administrator of Western CEDAR. For more information, please contact [email protected]. BLACK COTTONWOOD (POPULUS TRICHOCARPA) NUTRITION IN THE DEWATERED LAKE ALDWELL RESERVOIR ON THE ELWHA RIVER, WASHINGTON By Ezra Citron Accepted in Partial Completion Of the Requirements for the Degree Master of Science Kathleen L. Kitto, Dean of the Graduate School ADVISORY COMMITTEE Chair, Dr. Peter Homann Dr. Jenise Bauman Dr. Rebecca Bunn MASTER’S THESIS In presenting this thesis in partial fulfillment of the requirements for a master’s degree at Western Washington University, I grant to Western Washington University the non‐ exclusive royalty‐free right to archive, reproduce, distribute, and display the thesis in any and all forms, including electronic format, via any digital library mechanisms maintained by WWU. I represent and warrant that this is my original work and does not infringe or violate any rights of others. I warrant that I have obtained written permissions from the owner of any third party copyrighted material included in this work. 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Ezra Citron February 18, 2016 BLACK COTTONWOOD (POPULUS TRICHOCARPA) NUTRITION IN THE DEWATERED LAKE ALDWELL RESERVOIR ON THE ELWHA RIVER, WASHINGTON A Thesis Presented to The Faculty of Western Washington University In Partial Completion Of the Requirements for the Degree Master of Science By Ezra Citron February 2016 Abstract Following dam removal on the Elwha River, WA, the ability of plants to access and uptake nutrients may be an important factor in ecosystem recovery. Foliage was collected in November 2014 from naturally-established black cottonwood (Populus trichocarpa) saplings growing in the dewatered Lake Aldwell reservoir sediments and adjacent forest. Analysis of variance was used to assess variability among reservoir sediment textures and the adjacent forest with respect to foliar macronutrient (N, P, K, Ca, Mg) and micronutrient (Fe, Mn, Zn, Cu, Ni) concentrations. Within the reservoir, foliar P, K, and Mn were higher, and foliar Ca was lower, in the fine sediments than in the coarse sediments. All reservoir environments had lower foliar Mg and Zn and higher foliar Mn than the adjacent forest. Correlation analyses indicated many significant correlations between nutrient pairs. Several positive nutrient correlations with N may indicate that N is stimulating protein synthesis, and several negative correlations between nutrient pairs may indicate that cations are competing for plant uptake. Considering seasonal nutrient fluctuation and senescence-induced nutrient resorption, foliar nutrient values measured in Lake Aldwell cottonwood were generally consistent with those reported in the literature from other populations of non-fertilized Populus. Exceptions were values for foliar Ca, Fe, and Cu, which were comparatively low. The majority of resorption- adjusted growing-season estimates for Lake Aldwell foliar macronutrients were within ranges reported as optimal in fertilized Populus, with the exception of high estimates for Mg in the adjacent forest and for N at all sites. Presently, black cottonwood productivity at Lake Aldwell does not seem to be constrained by nutrient limitation, but nutrient availability will be critical in determining species-compositional changes at dewatered Lake Aldwell and successional trajectories in other dewatered environments following dam removal. iv Acknowledgments This project was funded by a Huxley College Small Grant for Graduate Research awarded by Huxley College of the Environment. Travel to and from the 2015 Elwha River Science Symposium was supported by a Ross Travel Grant awarded by Western Washington University. I appreciate the support of these programs. I would like to thank the National Parks Conservation Association for allocating a scholarship for me to attend this Symposium, which provided valuable context within which to interpret the findings of my research. I would like to thank my thesis committee chair, Dr. Peter Homann, for his suggestions, perspective, and gentle guidance throughout this research process and graduate program. His detailed feedback has fostered my development as a responsible scientist and has challenged me to become more efficient and organized in my research process. I would like to thank the other members of my committee, Dr. Jenise Bauman and Dr. Rebecca Bunn, for the insight that they have provided as my project has developed, especially with respect to my statistical design, analysis, and interpretation. I would like to thank Olympic National Park and Jerry Freilich for allowing me to sample at the Lake Aldwell reservoir and Joshua Chenoweth for showing me appropriate Lake Aldwell sampling sites and sharing details about the Elwha River ecosystem restoration project, which helped to focus my research questions. I would like to thank my brothers, Noah Citron and Andrew Relihan, for their enthusiastic assistance with sample collection. Noah, your late-night help processing leaves in the lab was a memorable and appreciated contribution to my project. I would like to thank my parents, Anji and Todd Citron, for supporting me in every way imaginable throughout the duration of this project, including joining me at the lab on occasion to help me complete my chemical analyses. I would like to thank Dr. David Shull, Dr. Ruth Sofield, Fraser Wilkinson, Kyle Mikkelsen, and Erin Macri for providing me access to and technical assistance with analytical instrumentation, for helping me to procure lab supplies, and for helping me to understand the protocols of trace metals analysis. I would like to thank Chhaya Werner and Dr. Rebecca Brown for providing me with data from previous Elwha River studies. Lastly, I would like to thank John Jordy and Sarah Voth for their valuable support throughout this project. v Abstract ................................................................................................................................... iv Acknowledgments ................................................................................................................... v List of Figures ......................................................................................................................... ix List of Tables .......................................................................................................................... ix 1.0 Introduction .................................................................................................................. 1 1.1 Nutrient Limitation in Primary Successional Environments...................................... 1 1.2 Ecological Setting: The Dewatered Lake Aldwell Reservoir .................................... 2 1.3 Nutrients in the Elwha River Ecosystem.................................................................... 3 1.4 Study Objectives, Research Questions, and Hypotheses ........................................... 4 2.0 Background .................................................................................................................. 7 2.1 Plant Nutrition ............................................................................................................ 7 2.1.1 The Importance of Plant Nutrition ...................................................................... 7 2.1.2 The Essential Mineral Elements ......................................................................... 8 2.1.3 Nutrient Concentrations in Plant Tissue ............................................................. 8 2.1.4 Functions of Nutrients in Plants ........................................................................ 10 2.1.5 Nutrient Mobility and Translocation within Plants .......................................... 11 2.1.6 Leaf Growth, Senescence, and Nutrient Resorption ......................................... 14 2.1.7 Nutrient Interactions within Plants ................................................................... 17 2.2 Assessment of Plant Nutrition .................................................................................. 19 2.2.1 Plant-Tissue Nutrient Concentrations ..............................................................