CONSERVATION STRATEGY FOR TAHOE YELLOW CRESS (Rorippa subumbellata) August 2002 CONSERVATION STRATEGY FOR TAHOE YELLOW CRESS (Rorippa subumbellata) Developed by: Bruce Pavlik, Ph.D. Dennis Murphy, Ph.D. and the Tahoe Yellow Cress Technical Advisory Group August 2002 Citation: Pavlik, B. et al. 2002. Conservation Strategy for Tahoe Yellow Cress (Rorippa subumbellata). Tahoe Regional Planning Agency. Lake Tahoe, NV Table of Contents Conservation Strategy TABLE OF CONTENTS EXECUTIVE SUMMARY .........................................................................EX-1 I. INTRODUCTION A. BACKGROUND ...............................................................................1 B. HISTORY OF SPECIES CONSERVATION ...........................................5 II. CONSERVATION STRATEGY A. TAHOE YELLOW CRESS AND LAKE TAHOE. ..................................8 B. BIOLOGICAL OVERVIEW OF TAHOE YELLOW CRESS .....................13 C. CONCEPTUAL MODEL OF METAPOPULATION DYNAMICS ............27 D. ANALYSIS OF EXISTING DATA........................................................38 E. CONSERVATION ON PUBLIC AND PRIVATE LANDS........................62 F. CONSERVATION GOALS, OBJECTIVES, AND ASSOCIATED ACTIONS ........................................................................................65 G. DESCRIPTION OF MANAGEMENT ACTIONS ...................................73 H. ADAPTIVE MANAGEMENT FRAMEWORK .......................................84 I. IMMINENT EXTINCTION CONTINGENCY PLAN.............................89 J. STEWARDSHIP, EDUCATION, AND OUTREACH .............................92 K. MONITORING, SCIENCE, AND RESEARCH AGENDA ......................95 III. LITERATURE CITED .............................................................................101 IV. APPENDICES A. EXECUTIVE COMMITTEE MEMBERS................................................A-2 B. TECHNICAL ADVISORY GROUP MEMBERS ....................................A-3 C. OCCURRENCE AND ABSENCE OF NATIVE POPULATIONS OF TAHOE YELLOW CRESS, 1978 TO 2000. ....................................A-4 D. STEM COUNT DATA FOR NATIVE POPULATIONS OF TAHOE YELLOW CRESS, 1978 TO 2000 .......................................................A-5 E. OCCURRENCE, ABSENCE, AND STEM COUNT DATA FOR REINTRODUCED POPULATIONS OF TAHOE YELLOW CRESS..........A-7 F. SUMMARY OF STEM COUNTS AND PERSISTENCE DATA .................A-9 G. BIOLOGICAL METHODS SECTION...................................................A-10 H. AGENCY POLICIES AND GUIDELINES ............................................A-20 I. PROJECT REVIEW GUIDELINES.......................................................A-29 J. PROPOSED ACTIONS FOR CORE AND HIGH PRIORITY SITES .........A-32 K. REGULATORY AUTHORITY AND ENFORCEMENT GUIDELINES .....A-38 L. BEACH RAKING GUIDELINES .........................................................A-40 M. TAHOE YELLOW CRESS PROTECTION SIGN FOR PRIVATE LANDOWNERS................................................................................A-43 i Table of Contents Conservation Strategy N. SURVEY PROTOCOLS AND ARCHIVAL AND ANNUAL DATA SHEETS.................................................................................A-45 O. CORE AND HIGH PRIORITY RESTORATION SITE HISTORIES..........A-50 V. MEMORANDUM OF UNDERSTANDING/ CONSERVATION AGREEMENT .............................................................MOU-1 VI. LIST OF FIGURES 1. FREQUENCY OF MAXIMUM GAP LENGTHS .....................28 2. EFFECT OF COLONIZATION AND EXTIRPATION .............32 3. ALTERNATIVE FORMS OF METAPOPULATION STRUCTURES....................................................................32 4. PATTERNS OF TAHOE YELLOW CRESS PERSISTENCE.......43 5. MEAN PRESENCE .............................................................44 6. PRESENCE BY OWNERSHIP ...............................................45 7. RELATIONSHIP OF MEAN PRESENCE BY LAKE LEVEL ......45 8. RELATIONSHIP OF PRESENCE BY OWNERSHIP .................47 9. PRESENCE OF TAHOE YELLOW CRESS AROUND LAKE TAHOE....................................................48 10. CHANGES IN ABSOLUTE NUMBER OF TAHOE YELLOW CRESS ...................................................50 11. RELATIONSHIP BETWEEN TAHOE YELLOW CRESS SITES AND LAKE ELEVATION ...........................................51 12. RELATIONSHIP BETWEEN MEAN STEM COUNT AND LAKE ELEVATION ....................................................51 13. RELATIONSHIP BETWEEN MEAN STEM COUNT AND PERSISTENCE............................................................52 14. RELATIONSHIP BETWEEN MAXIMUM STEM COUNT AND PERSISTENCE............................................................52 15. LINEAR ORDINATION BY VIABILITY INDEX.....................58 16. CORE SITES AND HIGH PRIORITY RESTORATION SITES ..59 17. MEDIUM PRIORITY RESTORATION SITES .........................60 18. ADAPTIVE MANAGEMENT FRAMEWORK .........................85 19. TIMELINE DESCRIBING ANNUAL CYCLE OF ADAPTIVE MANAGEMENT ACTIONS ...............................86 20. ORGANIZATION OF STEWARDSHIP PROGRAM.................93 21. SEARCH AREAS FOR NEW COLONIZATIONS....................97 VII. LIST OF TABLES 1. GENETIC VARIABILITY IN TAHOE YELLOW CRESS ..........17 2. MICROHABITAT CHARACTERISTICS ASSOCIATED WITH TAHOE YELLOW CRESS..........................................25 ii Table of Contents Conservation Strategy 3. PLANT COMMUNITY CHARACTERISTICS ASSOCIATED WITH TAHOE YELLOW CRESS..........................................26 4. FACTORS THAT DETERMINE COLONIZATION.................30 5. FACTORS THAT DETERMINE C, E, P, AND 1-P THAT ARE READILY MANIPULATED ................................31 6. DOCUMENTED EXTIRPATION..........................................34 7. DOCUMENTED COLONIZATION......................................35 8. RECREATIONAL VISITATION AND TAHOE YELLOW CRESS PRESENCE..............................................................46 9. CALCULATED VALUES OF MINIMUM VIABLE POPULATION SIZE............................................................53 10. RANKED TAHOE YELLOW CRESS SITES AND THEIR CHARACTERISTICS...........................................................55 11. UNRANKED TAHOE YELLOW CRESS SITES AND THEIR CHARACTERISTICS................................................56 12. HABITAT AVAILABILITY IN LOW LAKE LEVEL.................61 13. ADOPTED RANKING OF KNOWN TAHOE YELLOW CRESS SITES......................................................................76 14. FIVE YEAR PLAN FOR MANAGEMENT AND MONITORING RESPONSIBILITIES .............................................................79 VIII. LIST OF ACRONYMS USED AMWG Adaptive Management Working Group CA Conservation Agreement CDFG California Department of Fish and Game CDPR California Department of Parks and Recreation CESA California Endangered Species Act CEQA California Environmental Quality Act CS Conservation Strategy CSLC California State Lands Commission CTC California Tahoe Conservancy GIS Geographic Information System GPS Global Positioning System ITM Intensive Transect Method KGID Kingsbury General Improvement District LTD Lake Tahoe Datum League League to Save Lake Tahoe MOU Memorandum of Understanding NDF Nevada Division of Forestry NNHP Nevada Natural Heritage Program NVSP Nevada Division of State Parks NSL Nevada Division of State Lands PAO Public Affairs Officers iii Table of Contents Conservation Strategy REP Rorippa Enhancement Plan RLM Reconnaissance Level Method SAG Scientific Advisory Group TAG Technical Advisory Group TLOA Tahoe Lakefront Owners' Association TRPA Tahoe Regional Planning Agency TYC Tahoe Yellow Cress TYCSG Tahoe Yellow Cress Stewardship Group USFS United States Forest Service USFWS United States Fish and Wildlife Service iv Executive Summary CONSERVATION STRATEGY FOR TAHOE YELLOW CRESS (Rorippa subumbellata) August 2002 EXECUTIVE SUMMARY CONSERVATION STRATEGY FOR TAHOE YELLOW CRESS I. INTRODUCTION AND BACKGROUND Tahoe yellow cress (Rorippa subumbellata Roll.) is a rare plant species endemic to the shores of Lake Tahoe in California and Nevada. It was listed as endangered by the State of California in 1982 (California Fish and Game Code 2050 et seq.) and is considered endangered throughout its range by the California Native Plant Society (Skinner and Pavlik 1994). Tahoe yellow cress is state-listed as critically endangered in Nevada (Nevada Revised Statutes 527.270 et seq.), and is considered threatened by the Northern Nevada Native Plant Society (Nevada Natural Heritage Program 2001). It is classified as a candidate species for listing under the Endangered Species Act of 1973, as amended (64 FR 57533). Survey results through the year 2000 showed that Tahoe yellow cress occupied only 27 percent of the known, historic sites (Figure A). Evidence suggests the current decline in the number of sites occupied by Tahoe yellow cress is primarily due to: Alterations in lake level dynamics caused by construction and operation of the Truckee River outlet dam and reservoir; destruction of actual and potentially suitable habitat by the construction of piers, jetties, and other structures; high levels of recreational activity associated with beaches and dunes; disturbance of the sand by public and private property maintenance activities; and possibly random environmental events. Because of the imminent threats facing the species, a task force has been formed to develop and implement a conservation strategy for Tahoe yellow cress. The strategy is coupled with a Memorandum of Understanding (MOU)/conservation agreement (CA) signed by the participating entities that demonstrates the commitment of all involved