Functional Traits and Resource-Use Strategies of Native and Invasive Plants in Eastern North American Forests
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Syracuse University SURFACE Dissertations - ALL SURFACE 5-15-2015 Functional traits and resource-use strategies of native and invasive plants in Eastern North American forests Jacob Mason Heberling Syracuse University Follow this and additional works at: https://surface.syr.edu/etd Part of the Life Sciences Commons Recommended Citation Heberling, Jacob Mason, "Functional traits and resource-use strategies of native and invasive plants in Eastern North American forests" (2015). Dissertations - ALL. 213. https://surface.syr.edu/etd/213 This Dissertation is brought to you for free and open access by the SURFACE at SURFACE. It has been accepted for inclusion in Dissertations - ALL by an authorized administrator of SURFACE. For more information, please contact [email protected]. ABSTRACT Despite the presumption that native species are well adapted to their local environment, non- native invaders seem to outperform native plants. Intuitively, it appears paradoxical that non- native species, with no opportunity for local adaptation, can exhibit greater fitness than native plants with this advantage. Here, I compared traits of native and invasive shrub and liana species in Eastern North American (ENA) forests to test the overarching hypothesis that non-native understory species invasive to this region have superior resource-use strategies, or alternatively, they share the same metabolic tradeoffs as the native flora. First, at a global scale, I addressed the largely untested hypothesis that biogeography places significant constraints on trait evolution. Reanalyzing a large functional trait database, along with species’ native distribution data, I found that regional floras with different evolutionary histories exhibit different tradeoffs in resource capture strategies. Second, using a common garden to control for environment, I measured leaf physiological traits relating to resource investments, carbon returns, and resource-use efficiencies in 14 native and 18 non-native invasive species of common genera found in ENA understories, where growth is presumably constrained by light and nutrient limitation. I tested whether native and invasive plants have similar metabolic constraints or if these invasive species (predominantly from East Asia) are more productive per unit resource cost. Despite greater resource costs (leaf construction, leaf N), invaders exhibited greater energy- and nitrogen-use efficiencies, particularly when integrated over leaf lifespan. Efficiency differences were primarily driven by greater mean photosynthetic abilities (20% higher daily C gain) and leaf lifespans (24 days longer) in invasive species. Third, motivated by common garden results, I conducted a resource addition experiment in a central NY deciduous forest to investigate the role of resource limitation on invasion success in the field. I manipulated understory light environments (overstory tree removal) and N availabilities (ammonium-nitrate fertilization) to create a resource gradient across plots each containing 3 invasive and 6 native woody species. Invasive species generally exhibited greater aboveground productivity and photosynthetic gains. After two treatment years, invasive species displayed more pronounced trait responses to the resource gradients, primarily light, relative to the weaker responses of native species. Lastly, I asked whether species exhibit similar resource-use strategies in their native and invasive ranges. I measured leaf functional traits of Rhamnus cathartica (native to Europe, invasive in ENA) and Prunus serotina (native to ENA, invasive in Europe) in populations across central NY and northern France. Notably, I found invasive US populations of R. cathartica had markedly greater photosynthetic rates (50% higher) and reduced leaf N resorption rates in autumn (30% lower) than native French populations. Contrastingly, I found minimal leaf trait differences in P. serotina between native (US) and invasive (French) populations. Collectively, my results highlight the utility of functional trait perspectives and support a mechanistic explanation for invasion success based on differential abilities of species to convert limiting resources to biomass. FUNCTIONAL TRAITS AND RESOURCE-USE STRATEGIES OF NATIVE AND INVASIVE PLANTS IN EASTERN NORTH AMERICAN FORESTS by J. Mason Heberling B.S. Pennsylvania State University 2010 DISSERTATION Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Biology Syracuse University May 2015 Copyright © JM Heberling 2015 All Rights Reserved ACKNOWLEDGMENTS I am thankful to so many people that it is difficult to express my gratitude here and avoid cliché. I hope I have expressed my thanks beyond the brief words on this page. First, I am fortunate to be connected to Allison Heberling, who was more than supportive in this venture, both personally and academically. She selflessly moved to Syracuse for my dream (not hers), whilst maintaining her independence. I was absent many weekends and evenings, including a month long trip to New Zealand when she dealt with a rambunctious dog in the unfriendly Syracuse winter – all while pregnant. She knows more about plant ecology than she’ll admit and physically contributed more to data collection than anyone else realizes. I am incredibly thankful to my advisor, Jason Fridley. He provided not only academic advice, but also personal support and confidence to continue in science. All of the chapters were co-authored with him. I cannot describe here the many ways he has inspired and mentored me. I know he is one of the best advisors out there because he was more than just an advisor. I am grateful to many collaborators. Guillaume Decocq and Thomas Kichey warmly welcomed me in France and were essential to Ch 4. I appreciate the other Fridley lab members, especially Elise Hinman for our chats and her fieldwork. Tom and Randi Starmer were extremely generous to allow my unrestricted access to their property. Tom was even out there with a chainsaw for Ch 3. Mara McPartland has gone well beyond a field assistant to make important decisions for Ch 3. I also thank my research committee, Doug Frank, Martin Dovciak and Mark Ritchie, for their input and time. Lastly, and most recently, I thank Susan Kalisz and her lab at U. of Pittsburgh for support. The last year away from Syracuse would not have been nearly as productive without her motivation and guidance. v TABLE OF CONTENTS LIST OF ILLUSTRATIVE MATERIALS ............................................................................................ vii INTRODUCTION. Understanding modern floristic interchange through functional traits................1 CHAPTER 1. Biogeographic constraints on the worldwide leaf economics spectrum .................. 12 CHAPTER 2. Resource-use strategies of native and invasive plants in Eastern North American forests ...................................................................................................................................... 43 CHAPTER 3. Influence of resource availability on understory invasion success: ecophysiological responses to an experimental light and nitrogen gradient in an Eastern North American deciduous forest ...................................................................................................................... 88 CHAPTER 4. Plant functional shifts in the invaded range: a test with reciprocal forest invaders of Europe and North America ................................................................................................... 133 SYNTHESIS. Proximate and ultimate mechanisms of plant invasions ......................................... 170 APPENDIX 1. A practical guide for measuring leaf-level photosynthesis ................................... 176 APPENDIX 2. Code for Bayesian implementation of FvCB C3 photosynthesis model ............... 195 VITA ............................................................................................................................................ 199 vi LIST OF ILLUSTRATIVE MATERIALS INTRODUCTION. Figure 1. Relationship between photosynthetic capacity (Amax) and leaf nitrogen (N) in a global dataset ......................................................................................................................... 3 Figure 2. Hypothesized functional differences between native and invasive species .............. 4 CHAPTER 1. Table 1. Standardized major axis (SMA) regression parameters, coefficients of determination, and sample sizes for each floristic contrast and trait relationship ............... 38 Figure 1. Hypothetical differences in leaf economic trait relationships between plants of evolutionarily distinct floristic regions ................................................................................ 41 Figure 2. Leaf economic trait relationships for each floristic contrast ................................... 42 CHAPTER 2. Table 1. Woody, deciduous species measured in this study ................................................... 72 Table 2. Mean values (± 1 SE) of photosynthetic, biochemical, structural, and resource-use efficiency leaf traits among native and invasive species ..................................................... 74 Figure 1. Average modeled light response curves for 12 native and 18 invasive species ...... 79 Figure 2. Standardized major axis relationships for maximum C assimilation parameters and leaf N ...................................................................................................................................