Utah State University DigitalCommons@USU All Graduate Theses and Dissertations Graduate Studies 5-2011 Individualistic Response of Piñon and Juniper Tree Species Distributions to Climate Change in North America's Arid Interior West Jacob R. Gibson Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/etd Part of the Climate Commons, and the Ecology and Evolutionary Biology Commons Recommended Citation Gibson, Jacob R., "Individualistic Response of Piñon and Juniper Tree Species Distributions to Climate Change in North America's Arid Interior West" (2011). All Graduate Theses and Dissertations. 908. https://digitalcommons.usu.edu/etd/908 This Thesis is brought to you for free and open access by the Graduate Studies at DigitalCommons@USU. It has been accepted for inclusion in All Graduate Theses and Dissertations by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. INDIVIDUALISTIC RESPONSE OF PIÑON AND JUNIPER TREE SPECIES DISTRIBUTIONS TO CLIMATE CHANGE IN NORTH AMERICA'S INTERIOR WEST by Jacob R. Gibson A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in Ecology Approved: ____________________ ____________________ Thomas C. Edwards, Jr. James A. MacMahon Major Advisor Committee Member ____________________ ____________________ Terry L. Sharik Gretchen G. Moisen Committee Member Committee Member ____________________ Byron Burnham Dean of Graduate Studies UTAH STATE UNIVERSITY Logan, Utah 2011 ii ABSTRACT Individualistic Response of Piñon and Juniper Tree Species Distributions to Climate Change in North America's Arid Interior West by Jacob R. Gibson, Master of Science Utah State University, 2011 Major Professor: Dr. Thomas C. Edwards, Jr. Department: Wildland Resources Piñon and juniper tree species have species-specific climatic requirements, resulting in unique distributions and differential responses to climate change. Piñons and junipers co-dominate the arid woodlands of North America as groups with widespread hybridization. Two piñons, Pinus edulis; P. monophylla, and four junipers, Juniperus deppeana var. deppeana; J. monosperma; J. occidentalis; J. osteosperma, are endemic to the midlatitude interior west and form three groups of hybridizing sister species, P. edulis-P. monophylla; J. deppeana var. deppeana-J. monosperma; J. occidentalis-J. osteosperma. Recent droughts have caused widespread mortality among piñons, but have had less impact on junipers and indicate shifts in co-occurrence have already begun in response to global climate change. Within these groups hybridization likely plays an important role in such distribution changes. The central objective of this thesis is to forecast the distributions of piñons and junipers endemic to the US under modeled climate change for the 21st century. Species iii distribution models are built with an emphasis placed on aligning the life cycle dynamics of the species within the temporal and spatial resolution of predictor variables, and within the modeling technique. Two concerns surrounding species distribution modeling are addressed. First, concerns regarding the extent to which species are at equilibrium with the current climate are addressed by incorporating dispersal into the model building process. Second, concerns regarding the potential role of hybridization between closely related species are addressed by building distribution models for each of the three sister species groups as well as the six component species. Species distribution models exhibited individualistic responses to modeled climate change. Modeled areal loss was greater than gain for all species, which is reflected in changes of co-occurrence. Piñon-juniper richness is forecast to increase in the northern Colorado Plateau, eastern Great Basin, and Rocky Mountains. The sister-species models forecast greater areal gain, and less areal loss, along hybridization zones for P. edulis-P. monophylla and for J. occidentalis-J. osteosperma, but forecast greater areal loss along the periphery of the component species distributions. The sister-species model for J. deppeana var. deppeana-J. monosperma forecasts overall greater areal loss than the component species. In general, forecast changes in latitude and elevation are about one third of the changes inferred, from the fossil record, to have occurred following the transition to the current interglacial ~10,000 years ago. (104 pages) iv ACKNOWLEDGMENTS I would like to first thank my major advisor, Dr. Thomas C. Edwards, Jr., for creating a phenomenally heuristic environment, the BioDiversity Lab, for his students to learn and practice the techniques of research. Within this lab Tom provides cutting-edge resources and ample space for exploration. I have worked in this lab since 2005, when Tom took me on to work on a project with his colleagues Dr. Richard Cutler and Dr. Karen Beard, who I would also like to thank for treating me as a colleague and introducing me to the world of research. Tom's ability to challenge the understanding of his students is uncanny. I will always remember the early stages of this degree when I would work for a week or more on some idea to which Tom would respond with a simple question, transforming my perspective and launching me on new avenues of discovery. Adding to all of this, Tom provided indispensable support for me as I recovered from some of life's troubling curve- balls. I would like to thank Tom's former students whom I had the chance to share the lab with. Russell Norvell brought me into the lab as an undergraduate in 2005. Tammy Wilson and Adam Brewerton graciously shared the lab space. Both Russ and Tammy provided much moral support, encouragement, and guidance as fellow students navigating graduate school. I would also like to thank Phoebe Zarnetske who was finishing her master's as I entered the lab and immediately became my role model of a successful master's student. v My committee members have each taught me fundamentals of research in their own way. Dr. Jim MacMahon enlightened me to the field of biogeography in my final semester as an undergraduate and has always provided a genuinely human ear to me through this whole process. Dr. Terry Sharik fueled my passion for the investigation of the arborescent habit with his dendrology course. In addition to the technical support Dr. Gretchen Moisen provided, she also taught me much in the way of working with others. Among the numerous others who have provided support in various ways, I would like to thank Tracey Frescino of the Ogden FIA. Tracey has helped me with crucial bits of R code as well as patiently assisting my preparation of presentations. I would like to also thank those here at USU that have helped in so many ways. Ben Crabb encouraged my efforts all along and helped keep me light hearted. Marsha Bailey, Lana Barr, and Cecelia Melder have kept track of me and provided indispensable assistance with the realities of paper-work; I would have been toast without these three. I would also like to thank my blood-family and my greater friend-family. Both have been comprehensively supportive of my unusual work habits which often left me out of touch for weeks at a time. Yet they seemed always to show up with nutritious meals and open doors just when I needed it most. And finally, I would like to thank Jaynan Chanceler and Travis Sapp of the Da'wi drum and dance group, who provide a solid rhythm in my life. Jacob Gibson vi CONTENTS Page ABSTRACT.................................................................................................................ii ACKNOWLEDGMENTS ...........................................................................................iv LIST OF TABLES.......................................................................................................viii LIST OF FIGURES .....................................................................................................ix BACKGROUND. ........................................................................................................1 Overview..........................................................................................................1 Phylogeny and distribution of piñons and junipers..........................................1 Life cycle and coevolutionary relations of piñons and junipers ......................3 Fertilization..........................................................................................4 Dispersal ..............................................................................................5 Establishment.......................................................................................7 Persistence............................................................................................9 The integrated distribution...............................................................................12 Holocene and current distribution of piñons and junipers...............................14 INTRODUCTION .......................................................................................................17 METHODS .................................................................................................................23 Study area.........................................................................................................23 Study species....................................................................................................25 Dispersal ..........................................................................................................27