BIRD RESPONSE TO LANDSCAPE PATTERN AND DISTURBANCE ACROSS PRODUCTIVITY GRADIENTS IN FORESTS OF THE PACIFIC NORTHWEST by David Burch McWethy A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Ecology and Environmental Sciences MONTANA STATE UNIVERSITY Bozeman, Montana May 2007 © COPYRIGHT by David Burch McWethy 2007 All Rights Reserved ii APPROVAL of a dissertation submitted by David Burch McWethy This dissertation has been read by each member of the thesis committee and has been found to be satisfactory regarding content, English usage, format, citations, bibliographic style, and consistency, and is ready for submission to the Division of Graduate Education. Dr. Andrew Hansen, Committee Chair Approved for the Department of Ecology Dr. David Roberts, Department Head Approved for the Division of Graduate Education Dr. Carl A. Fox, Vice Provost iii STATEMENT OF PERMISSION TO USE In presenting this dissertation in partial fulfillment of the requirements for a doctoral degree at Montana State University, I agree that the Library shall make it available to borrowers under rules of the Library. I further agree that copying of this dissertation is allowable only for scholarly purposes, consistent with “fair use” as prescribed in the U.S. Copyright Law. Requests for extensive copying or reproduction of this dissertation should be referred to ProQuest Information and Learning, 300 North Zeeb Road, Ann Arbor, Michigan 48106, to whom I have granted “the exclusive right to reproduce and distribute my dissertation in and from microform along with the non- exclusive right to reproduce and distribute my abstract in any format in whole or in part.” David Burch McWethy May, 2007 iv ACKNOWLEDGEMENTS I would like to thank the National Council for Air and Stream Improvement and the National Fish and Wildlife Foundation for their support of this research. I also thank my graduate advisor, Andy Hansen, for giving me the opportunity to work on this project and for his guidance and advice. I am grateful for the contributions of my graduate committee: Dave Roberts, Cathy Whitlock, and Bruce Maxwell. I am indebted to my colleagues in the Landscape Biodiversity Lab who provided technical assistance, expertise and feedback throughout critical phases of this project. I am particularly grateful for the contributions of my colleague Jake Verschuyl whom I worked on nearly all aspects of this research with. A very special thank you also goes out to the field assistants who made this project possible: Andy Arens, Jose Blanco, Caanan Cowles, Jessica Eselius, Julia Esposito, Valerie Eurs, Louise Gava, Carolyn Matkovich, Jen Verschuyl, and Karen Weber. Finally, I would like to thank my wife, Sauny, and son, Aldo, for their laughter, encouragement, and continued support for my work on this project. v TABLE OF CONTENTS 1. INTRODUCTION TO DISSERTATION .......................................................................1 Introduction......................................................................................................................1 Organization of the Dissertation ......................................................................................2 Literature Cited................................................................................................................4 2. EDGE DENSITY AND FOREST PRODUCTIVITY INTERACT TO INFLUENCE BIRD DIVERSITY IN THE PACIFIC NORTHWEST..................................................5 Abstract............................................................................................................................5 Introduction......................................................................................................................6 Methods..........................................................................................................................12 Study Area ..............................................................................................................12 Springfield, OR..................................................................................................12 Cle Elum, WA....................................................................................................13 Study Design............................................................................................................14 Bird Sampling ..........................................................................................................15 Landscape Pattern Mapping.....................................................................................16 Landscape Predictor Data ........................................................................................18 Statistical Analysis...................................................................................................19 Response to Edge Density--Species Level ........................................................19 Response to Edge Density--Community level...................................................20 Ecosystem Productivity Effects: Species Level.................................................20 Ecosystem Productivity Effects: Community Level..........................................22 Results............................................................................................................................23 Landscape Structural and Productivity Characteristics ...........................................23 Bird Response to Gradients in Edge Density...........................................................25 Individual Species..............................................................................................25 Community-Level Response..............................................................................29 Ecosystem Productivity Effects ...............................................................................29 Individual Species..............................................................................................29 Individual Species--Edge Density-Productivity Interaction ..............................30 Community-Level Response..............................................................................33 Discussion......................................................................................................................34 Landscape Effects ....................................................................................................34 Landscape Effects as a Function of Productivity.....................................................36 Scale Effects.............................................................................................................37 Scope and Limitations..............................................................................................37 Management Implications..............................................................................................39 Conclusions....................................................................................................................41 vi TABLE OF CONTENTS - CONTINUED Literature cited...............................................................................................................42 3. BIRD RESPONSE TO DISTURBANCE VARIES WITH FOREST PRODUCTIVITY IN THE PACIFIC NORTHWEST..................................................49 Abstract..........................................................................................................................49 Introduction....................................................................................................................50 Methods..........................................................................................................................57 Study Area ...............................................................................................................57 Springfield, OR..................................................................................................57 Cle Elum, WA....................................................................................................57 Study Design............................................................................................................59 Landscape Pattern Mapping.....................................................................................60 Bird Sampling ..........................................................................................................61 Landscape Predictor Data ........................................................................................62 Site Productivity.......................................................................................................62 Statistical Analysis...................................................................................................64 Results............................................................................................................................65 Discussion......................................................................................................................67 Management implications..............................................................................................70 Conclusions....................................................................................................................74 Literature cited...............................................................................................................76 4. TAILORING FOREST MANAGEMENT TO SUPPORT SPECIES DIVERSITY ACROSS PRODUCTIVITY GRADIENTS................................................................