UNDERSTANDING ABOVE- AND BELOWGROUND INTERACTIONS WITHIN INVASION BIOLOGY: AN INTEGRATIVE APPROACH ACROSS A FOREST COMMUNITY By COLIN G. COPE Submitted in partial fulfilment of requirements for the degree of Doctor of Philosophy Advisor: Dr. Jean H. Burns Department of Biology CASE WESTERN RESERVE UNIVERSITY August 2018 CASE WESTERN RESEREVE UNIVERSITY SCHOOL OF GRADUATE STUDIES We hereby approve the dissertation of Colin G. Cope Candidate for the Doctor of Philosophy degree*. Committee Chair: Karen C. Abbott Committee Member: Jean H. Burns Committee Member: Michael F. Benard Committee Member: David J. Burke Committee Member: Emily S.J. Rauschert Date of Defense: March 21st, 2018 *We also certify that written approval has been obtained for any proprietary material contained therein. ii Copyright © by Colin G. Cope All rights reserved iii Dedication To my father: Gregory A. Cope You are greatly missed and all of this would not be possible without all of the love and support you have provided me growing up. iv Table of Contents Dissertation Summary ..................................................... Error! Bookmark not defined. Chapter 1: Introduction ................................................................................................... 3 Chapter 2: A functional trait perspective on above and belowground interactions: invavsive earthworms and native deer .......................................................................... 10 Summary .................................................................................................................... 11 Introduction ............................................................................................................... 12 Methods ..................................................................................................................... 15 Study System........................................................................................................... 15 Study Design .......................................................................................................... 16 Statistical Analyses ................................................................................................ 17 Results ....................................................................................................................... 21 Earthworm Functional Groups .............................................................................. 21 Earthworm Body Size ............................................................................................. 22 Discussion .................................................................................................................. 23 Acknowledgements ................................................................................................... 27 Tables......................................................................................................................... 28 Figures ....................................................................................................................... 30 Chapter 3: The influence of overabundant white-tailed deer and invasive earthworms on above- and belowground communites ................................................ 34 Summary .................................................................................................................... 35 Introduction ............................................................................................................... 35 Methods ..................................................................................................................... 38 Study System........................................................................................................... 38 Study Design .......................................................................................................... 39 Statistical Analysis ................................................................................................. 41 Discussion .................................................................................................................. 45 Acknowledgements ................................................................................................... 49 Tables......................................................................................................................... 50 Figures ....................................................................................................................... 55 Chapter 4: Potential interactive effects between invasive Lumbricus terrestris and the invasive plant garlic mustard on a native plant ..................................................... 59 Summary .................................................................................................................... 60 v Introduction ............................................................................................................... 62 Materials and Methods .............................................................................................. 65 Plant Community Assessment Program dataset .................................................... 65 Factorial Experiment ............................................................................................. 65 Plant nutrient content and physiology ................................................................... 67 Statistical Analyses ................................................................................................ 69 Results ....................................................................................................................... 70 Plant Community Assessment Program Observational data ................................. 70 Factorial Experiment ............................................................................................. 71 Discussion .................................................................................................................. 72 Acknowledgements ................................................................................................... 74 Tables......................................................................................................................... 76 Figures ....................................................................................................................... 81 Chapter 5: Conclusions .................................................................................................. 88 Appendix A: Chapter 2 Supplementary Materials ..................................................... 92 Appendix B: Chapter 3 Supplementary Materials .................................................... 101 Appendix C: Chapter 4 Supplementary Materials .................................................... 103 Bibliography .................................................................................................................. 106 vi List of Tables Chapter 2: Table 2.1: A generalized linear model with binomial error distribution on the presence/absence of earthworms as a function of control and deer exclosure treatments, earthworm functional group, and the interaction between treatment and functional group with pH and the year of exclosure establishment as covariates…………………………28 Table 2.2: A generalized least squares model with square root transformed earthworm abundance as a function of control and deer exclosure treatments, earthworm functional group, the interactions between treatment and functional group, and functional group by average pH, with the year of exclosure establishment and pH as covariates. Latitude and longitude were used in a corSper correlation structure to model spatial autocorrelation. Contrasts within functional groups compared control to deer exclosure treatments. .......29 Chapter 3: Table 3.1: Generalized least squares of response variable ordination axes MDS1 and MDS2 for fungal communities with deer exclusion treatment and worm presence/absence as predictors. Latitude and longitude were included in the model as part of the error structure. …………………………………………………………………………………50 Table 3.2: Generalized least squares of response variable ordination axes MDS1 and MDS2 for fungal soil communities with deer exclusion treatment and earthworm presence/absence for each functional group as predictors. Latitude and longitude were included in the model as part of the error structure. …………………………………….51 Table 3.3: Generalized least squares of response variable ordination axes MDS1 and MDS2 for fungal soil communities with deer exclusion treatment and earthworm abundance for each functional group as predictors. Latitude and longitude were included in the model as part of the error structure. ………………………………………………52 Table 3.4: Generalized least squares of response variable ordination axes MDS1 and MDS2 for bacteria soil communities with deer exclusion treatment and earthworm presence/absence for each functional group as predictors. Latitude and longitude were included in the model as part of the error structure. Bacteria MDS1 had one row removed due to it being an outlier. ……………………………………………………………….53 Table 3.5: Generalized least squares of response variable ordination axes MDS1 and MDS2 for bacteria soil communities with deer exclusion treatment and earthworm abundance for each functional group as predictors. Latitude and longitude were included in the model as part of the error structure. Bacteria MDS1 had one row removed due to it being an outlier. ………………………………………………………………………...54 vii Chapter 4: Table 4.1: Observational