Management Recommendations for Washington's Priority Habitats
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This document should be cited as: Larsen, E. M., and J. T. Morgan. 1998. Management recommendations for Washington’s priority habitats: Oregon white oak woodlands. Wash. Dept. Fish and Wildl., Olympia. 37pp. Management Recommendations for Washington’s Priority Habitats: OREGON WHITE OAK WOODLANDS Eric M. Larsen and John T. Morgan January 1998 Washington Department of Fish and Wildlife 600 Capitol Way N Olympia, WA 98501-1091 TABLE OF CONTENTS LIST OF FIGURES .........................................................v ACKNOWLEDGMENTS .................................................... vi WASHINGTON DEPARTMENT OF FISH AND WILDLIFE REGIONAL CONTACTS ................................................ vii EXECUTIVE SUMMARY ................................................... ix INTRODUCTION ..........................................................1 PHS Management Recommendations ..........................................1 Goals ................................................................3 Format ...............................................................3 DEFINITION ..............................................................4 RATIONALE ..............................................................4 DISTRIBUTION ............................................................5 HABITAT DESCRIPTION ....................................................6 Climate .................................................................6 Soil ....................................................................6 Vegetation Communities ....................................................7 Tree Constituents .......................................................7 Understory Shrubs ......................................................7 Grasses and Forbs .......................................................8 Oak Reproduction .........................................................8 WILDLIFE USE ............................................................8 Oak Features Important to Wildlife ............................................8 Oak as a Source of Cavities ...............................................9 Oak as a Food Source ....................................................9 Oak-Associated Wildlife Species and Species Groups .............................10 Woodpeckers .........................................................11 Western Gray Squirrel ..................................................11 Neotropical Migrant Birds ...............................................12 Invertebrates ..........................................................12 January 1998 iii Washington Department of Fish and Wildlife IMPACTS OF LAND USE ...................................................12 Threats to Oregon White Oak ...............................................13 Land Conversion ......................................................13 Conifer Encroachment ..................................................13 Timber Harvest ........................................................14 Grazing .............................................................16 The Role of Fire in Oregon White Oak Woodlands ...............................17 MANAGEMENT RECOMMENDATIONS ......................................19 Goals .................................................................19 Land Use ..............................................................19 Land Conversion and Oak Removal ........................................19 Grazing .............................................................20 Recreation ...........................................................21 Oak Restoration and Enhancement ...........................................21 Prescribed Burning .....................................................21 Selective Harvest and Stand Thinning ......................................22 Retention of Valuable Trees ..............................................23 Creation of Snags When Thinning or Enhancing Oak Woodlands .................24 Retention of Contiguous Aerial Pathways ....................................25 Other Oak Enhancement Activities ...........................................25 REFERENCES CITED ......................................................26 PERSONAL COMMUNICATIONS ............................................31 APPENDICES ............................................................33 Appendix A. Common and scientific names of plants and animals mention in the text. ...33 Appendix B. Invertebrates known to occur in Oregon white oak woodlands ...........34 January 1998 iv Washington Department of Fish and Wildlife LIST OF FIGURES Figure 1. Range of Oregon white oak woodlands in Washington .......................5 January 1998 v Washington Department of Fish and Wildlife ACKNOWLEDGMENTS Appreciation is extended to all those individuals who assisted in bringing this document to completion. In particular, Noelle Nordstrom and Stephen Penland who assisted with editing and formatting and Darrell Pruett who created the cover illustration. Also, the Department would like to thank the many individuals who provided information and who reviewed the document. January 1998 vi Washington Department of Fish and Wildlife WASHINGTON DEPARTMENT OF FISH AND WILDLIFE REGIONAL CONTACTS For Assistance with PHS Information Specific to Your County, Contact the Following WDFW Representative. If you live in... Contact... Asotin, Columbia, Ferry, Garfield, Lincoln, John Andrews Pend Oreille, Spokane, Stevens, Walla Walla, Whitman 8702 N. Division St. Spokane, WA 99218-1199 Phone: (509) 456-4082 Adams, Chelan, Douglas, Grant, Okanogan Tracy Lloyd 1550 Alder St. NW Ephrata, WA 98823-9699 Phone: (509) 754-4624 Benton, Franklin, Kittitas, Yakima Ted Clausing 1701 24th Ave. Yakima, WA 98902-5720 Phone: (509) 575-2740 Island, King, San Juan, Skagit, Snohomish, Whatcom Ted Muller 16018 Mill Creek Blvd. Mill Creek, WA 98012-1296 Phone: (206) 775-1311 Clark, Cowlitz, Klickitat, Lewis, Skamania, Wahkiakum Bryan Cowan 2108 Grand Blvd. Vancouver WA 98661 Phone: (360) 696-6211 Clallam, Grays Harbor, Jefferson, Kitsap, Mason, Pacific, Pierce, Steve Keller Thurston 48 Devonshire Rd. Montesano, WA 98563-9618 Phone: (360) 249-4628 January 1998 vii Washington Department of Fish and Wildlife January 1998 viii Washington Department of Fish and Wildlife EXECUTIVE SUMMARY Oregon white oak (Quercus garryana) is Washington’s only native oak. Although limited and declining, oaks and their associated floras comprise distinct woodland ecosystems. The various plant communities and stand age mixtures within oak forests provide valuable habitat that contributes to wildlife diversity statewide. In conjunction with other forest types, oak woodlands provide a mix of feeding, resting, and breeding habitat for many wildlife species. More than 200 vertebrate and a profusion of invertebrate species use Washington’s oak woodlands. Some species occur in especially high densities, whereas others are not typically found in Washington. Oaks provide habitat for species that are state listed as Sensitive, Threatened, Endangered, or candidates for these listings. Oregon white oaks occur within the Puget Trough, Washington’s south-central counties, along the Columbia Gorge, and northward along the east side of the Cascade range. Some small stands and relict groves can be found in the San Juan Islands, along Hood Canal, and in the Willapa Hills. Oregon white oaks are generally restricted to lower elevations, drier areas, and areas with historically limited conifer competition. West of the Cascades, oaks are found within the Western Hemlock Forest Zone and often occupy the narrow sub-zone between prairies and conifer forests. East of the Cascades, oaks are found within the Ponderosa Pine Forest Zone and occupy the transition zone between conifers and shrub-steppe. The Columbia Gorge is a transitional area where a mixture of east and west forest plant constituents can be found. Oregon white oaks tolerate an array of soil types but flourish in the deep loams of southwestern Washington. This tree species reproduces by seed and sprout. Priority Oregon white oak woodlands are stands of pure oak or oak/conifer associations where canopy coverage of the oak component of the stand is $25%; or where total canopy coverage of the stand is <25%, but oak accounts for at least 50% of the canopy coverage present. The latter is often referred to as an oak savanna. In non-urbanized areas west of the Cascades, priority oak habitat is stands $0.4 ha (1 ac) in size. East of the Cascades, priority oak habitat is stands $2 ha (5 ac) in size. In urban or urbanizing areas, single oaks, or stands of oaks <0.4 ha (1 ac), may also be considered priority habitat when found to be particularly valuable to fish and wildlife (i.e., they contain many cavities, have a large diameter at breast height [dbh], are used by priority species, or have a large canopy). Oregon white oak woodlands are used by an abundance of mammals, birds, reptiles, and amphibians. Many invertebrates, including various moths, butterflies, gall wasps, and spiders, are found exclusively in association with this oak species. Oak/conifer associations provide contiguous aerial pathways for animals such as the State Threatened western gray squirrel, and they provide important roosting, nesting, and feeding habitat for wild turkeys and other birds and mammals. Dead oaks and dead portions of live oaks harbor insect populations and provide nesting cavities. Acorns, oak leaves, fungi, and insects provide food. Some birds, such as the Nashville warbler, exhibit