United States Department of Agriculture Aspen Biology, Community Forest Service Classification, and Management Pacific Northwest Research Station in the Blue Mountains General Technical Report PNW-GTR-806 May 2010 David K. Swanson, Craig L. Schmitt, Diane M. Shirley, Vicky Erickson, Kenneth J. Schuetz, Michael L. Tatum, and David C. Powell The Forest Service of the U.S. Department of Agriculture is dedicated to the principle of multiple use man- agement of the Nation’s forest resources for sustained yields of wood, water, forage, wildlife, and recreation. Through forestry research, cooperation with the States and private forest owners, and management of the national forests and national grasslands, it strives—as directed by Congress—to provide increasingly greater service to a growing Nation. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or part of an individual’s income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, 1400 Independence Avenue, SW, Washington, DC 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. Author David K. Swanson was an area ecologist, U.S. Department of Agriculture, Forest Service, P.O. Box 907, Baker City, OR 97814, is now an ecologist with the U.S. Department of the Interior, National Park Service, 4175 Geist Rd., Fairbanks, AK 99709. Craig L. Schmitt is a zone pathologist, U.S. Department of Agriculture, Forest Service, 1401 Gekeler Lane, La Grande, OR 97850. Diane M. Shirley is a forestry technician, U.S. Department of Agriculture, Forest Service, Umatilla National Forest, P.O. Box 158, Ukiah, OR 97880. Vicky Erickson is the regional geneticist, and David C. Powell is a forest silviculturalist, U.S. Department of Agriculture, Forest Service, Umatilla National Forest, 2517 Hailey Avenue, Pendleton, OR 97801. Kenneth J. Schuetz (deceased) was a forest wildlife biolo- gist, and Michael L. Tatum is a forest silviculturist, U.S. Department of Agriculture, Forest Service, Malheur National Forest, P.O. Box 909, John Day, OR 97845. Cover photo: Aspen stand with buck-and-pole fence constructed of local thinning slash 8 years prior to photo. Regeneration is lacking around the mature trees outside of the fenced area on the right. Blue Mountain Ranger District of the Malheur National Forest, in the vicinity of Camp Creek and Starr Ridge. Photo by Michael Tatum, Malheur National Forest. Abstract Swanson, David K.; Schmitt, Craig L.; Shirley, Diane M.; Erickson, Vicky; Schuetz, Kenneth J.; Tatum, Michael L.; Powell, David C. 2010. Aspen biology, community classification, and management in the Blue Mountains. Gen. Tech. Rep. PNW-GTR-806. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 117 p. Quaking aspen (Populus tremuloides Michx.) is a valuable species that is declining in the Blue Mountains of northeastern Oregon. This publication is a compilation of over 20 years of aspen management experience by USDA Forest Service workers in the Blue Mountains. It includes a summary of aspen biology and occurrence in the Blue Mountains, and a discussion of aspen conservation and management techniques such as fencing, conifer removal, and artificial propagation. Local data on bird use of aspen stands, insects and diseases in aspen, and genetic studies of aspen are also included. An aspen community classification developed from over 200 sample plots is presented, with plant species composition and cover, environment and soils, and management considerations. Keywords: Populus tremuloides, forest management, forest ecology, plant community classification. Preface This publication is a collaboration that draws on the efforts of many people who have worked with aspen in the Blue Mountains. Primary authorship of the various sections is as follows: • Aspen Biology and Ecology–David K. Swanson, Kenneth J. Schuetz (Bird use of aspen on the Malheur National Forest), David C. Powell, and Michael L. Tatum • Genetic Diversity and Structure of Aspen Stands in the Blue Mountains–Vicky Erickson • Insects and Diseases of Aspen in the Blue Mountains–Craig L. Schmitt • Aspen Management in the Blue Mountains–David K. Swanson, Diane M. Shirley, Michael L. Tatum, and Vicky Ericson with contributions from most of the collaborators • Aspen Community Classification in the Blue Mountains–David K. Swanson i ii Aspen Biology, Community Classification, and Management in the Blue Mountains David K. Swanson, Craig L. Schmitt, Diane M. Shirley, Vicky Erickson, Kenneth J. Schuetz, Michael L. Tatum, and David C. Powell With contributions from (listed alphabetically): Roderick R. Clausnitzer, Lynda Cobb, Bill J. Collar, Elizabeth A. Crowe, Terry Hicks, Jerold Hustafa, Charles G. Johnson, Jr., Betsy H. Kaiser, Cynthia L. Kranich, Mark A. Penniger, Roy Schwenke, Joseph M. Sciarrino, Paul W. Survis, and Martin Vavra. United States Department of Agriculture, Forest Service, Pacific Northwest Research Station General Technical Report PNW-GTR-806 May 2010 iii iv Contents 1 Introduction 1 Aspen Biology and Ecology 1 Aspen Clones and Root System 1 Reproduction 4 Ecological Range 6 Competition and Succession 6 Fire Effects 7 Herbivores and Aspen 7 Aspen Occurrence in the Blue Mountains 9 Decline of Aspen in the Blue Mountains 10 Invasive Plants and Aspen 10 Bird Use of Aspen Habitats in the Blue Mountains 12 Genetic Diversity and Structure of Aspen Stands in the Blue Mountains 16 Genetic Variation at the Stand Level 16 Geographic Variation in Genetic Structure 17 Genetic Evidence for Decline of Aspen Clones 17 Management Implications 17 Insects and Diseases of Aspen in the Blue Mountains 18 Stem Decays 19 Trunk Butt and Root Rots 19 Canker Diseases 21 Foliage Diseases 22 Insect Pests of Aspen 25 Aspen Management in the Blue Mountains 25 Overview 28 Conifer Removal 30 Fencing 34 Fire 35 Aspen Felling and Girdling 35 Mechanical Site Preparation 36 Thinning 36 Establishment of Aspen Outside of Existing Stands 38 Vegetative Propagation 40 Propagation of Aspen From Seed 41 Restoring Understory Plant Diversity in Aspen Stands 42 Assessment of Aspen Regeneration 43 Aspen Stand Quick Assessment and Desired Future Condition 47 Aspen Community Classification in the Blue Mountains 47 Study Area 48 Plant Association Concept v 48 Field Methods 49 Classification and Data Analysis Methods 50 Data Presentation 50 Keys to Aspen Communities of the Blue Mountains 51 Key to Riparian and Wetland Aspen Vegetation 52 Key to Upland Aspen Vegetation 53 Upland Grand Fir Series Aspen Type Key 54 Upland Ponderosa Pine and Douglas-Fir Series Aspen Type Key 55 Riparian and Wetland Aspen Plant Communities 55 Aspen-Engelmann Spruce Types 55 Aspen-Engelmann Spruce/Fowl Mannagrass-Bluejoint Reedgrass Plant Community Type 56 Aspen-Tall Shrub Types 56 Aspen/Mountain Alder-Red-Osier Dogwood Plant Community Type 56 Aspen/Mountain Alder-Common Snowberry Plant Community Type 56 Aspen/Black Hawthorne Plant Community Type 57 Aspen/Tall Shrub Wetland Plant Communities on Slopes 58 Riparian Aspen/Common Snowberry Types 58 Grand Fir/Common Snowberry (Floodplain) Plant Community Type 58 Douglas-Fir/Common Snowberry (Floodplain) Plant Association 58 Ponderosa Pine/Common Snowberry (Floodplain) Plant Association 58 Aspen/Common Snowberry Plant Community Type 62 Herbaceous Aspen Meadow Types 62 Aspen/Aquatic Sedge Plant Community Type 62 Aspen/Woolly Sedge Plant Association 65 Aspen/Yellow Sedge Plant Community Type 66 Aspen/Bluejoint Reedgrass Plant Community Type 68 Aspen/Kentucky Bluegrass Plant Community Type 68 Aspen/Meadow Foxtail Plant Community Type 68 Aspen/Mesic Forb Plant Community Type 72 Upland Aspen Communities 72 Talus and Rock Outcrop Aspen Types 72 Aspen (Rubble, High) Plant Community Type 72 Aspen (Rubble, Low) Plant Community Type 75 Aspen Types of the Subalpine Fir Series 75 Aspen (Subalpine Fir)/Western Coneflower Plant Community Type 77 Aspen Types of the Grand Fir Series 77 Grand Fir/Twinflower Plant Association 78 Grand Fir/Big Huckleberry Plant Association 81 Grand Fir/Rocky Mountain Maple Plant Association 83 Aspen (Grand Fir)/Oceanspray Plant Community Type vi 83 Aspen (Grand Fir)/Snowberry Plant Community Type 86 Other Grand Fir Series Aspen Communities 88 Aspen Types of the Ponderosa Pine and Douglas-Fir Series 88 Aspen/Chokecherry Plant Community Type 90 Aspen(Douglas-Fir)/Bitter Cherry Plant Community Type 92 Aspen (Ponderosa Pine–Douglas-Fir)/Snowberry Plant Community Type 95 Aspen/Pinegrass Plant Community Type 95 Aspen/Elk Sedge Plant Community Type 95 Aspen/Exotic Grass Plant Community Type 99 Other Douglas-Fir and Ponderosa Pine Series Aspen Communities 101 Acknowledgments 101 Metric Equivalents 102 References 109 Appendix A: Aspen Stands Sampled as Part of the Blue Mountains Genetics Study 112 Appendix B: Plant Names Used in This Report 117 Appendix C: Current PLANTS Database Synonyms for the Names Used in This Report vii Introduction together, variations in one or more of these characteristics can sometimes be used to identify different clones in the Stands of quaking aspen (Populus tremuloides Michx.) field without the cost of genetic testing. are an uncommon and unique habitat type in the Blue Aspen roots can grow laterally far from their parent trees Mountains (fig. 1). As one of very few broadleaf decidu- and produce suckers. Excavations of aspen root systems in ous trees in a region dominated by conifers and semi- the Great Lakes region revealed root growth rates of 2.5 ft/ desert grassland and scrub, aspen brings important diversity year (Day 1944) to 4.5 ft/year (Buell and Buell 1959) in good to the landscape.