Status of Porter’s Sagebrush (Artemisia porteri) in Wyoming Prepared for the Bureau of Land Management Wyoming State Office And Wyoming Natural Diversity Database, University of Wyoming By Walter Fertig Botanical Consultant 1117 West Grand Canyon Dr. Kanab, UT 84741 25 September 2002 Agreement # K910-A4-0011 Task Order No. TO-09 ABSTRACT Porter's sagebrush is endemic to the Wind River and Powder River basins in central Wyoming. It is found primarily in sparsely vegetated Artemisia pedatifida, A. longifolia, or A. porteri communities on barren clay or ashy badlands, flats, or gullies derived from the Wind River, Wagon Bed, or Frontier formations. This species is currently known from 11 extant occurrences consisting of at least 60 subpopulations covering less than 1250 acres. Individual colonies typically number from 100-1000 individuals and occupy areas of 1-50 acres. Based on surveys in 1999, the current population of Porter's sagebrush is conservatively estimated at 50,000-75,000 plants. Porter's sagebrush is primarily threatened by mineral development (oil, natural gas and uranium) within its limited range and specialized habitat. This species was designated as Sensitive by the BLM in 2001 and occurs primarily on BLM lands in the Buffalo, Casper, and Lander field offices. No populations currently receive formal protection, although the population in the Lysite Badlands is managed under special use regulations in the BLM Lander Resource Area Resource Management Plan. Porter's sagebrush is now known to be more widespread and abundant in Wyoming than previously suspected. Until sufficient habitat is afforded protection or management strategies are developed and implemented for this species in mineral extraction areas, A. porteri should remain a BLM state Sensitive species. ACKNOWLEDGEMENTS I would like to thank the following individuals for their contributions to this project: Laura Welp Fertig of WYNDD assisted with field surveys and established monitoring plots in 1999; Richard and Beverly Scott of Central Wyoming College shared information from their field surveys in 1999-2000; Amy Roderick Taylor provided information from her general floristic surveys of 1997- 1998; George P. Jones of WYNDD shared information on a new population from Johnson County he discovered in 1997; Sue Oberlie of the BLM provided information and maps from pipeline surveys in Fremont County; Scott Laursen of WYNDD assisted with digitizing element occurrence locations in ArcView; and Jeff Carroll of the BLM Wyoming State Office provided funding and logistic support. 2 Table of Contents Page Abstract ................................................................................................................................. 2 Acknowledgements ............................................................................................................... 2 Introduction .......................................................................................................................... 5 Methods .............................................................................................................................. 5 Species Information .............................................................................................................. 6 Classification ............................................................................................................ 6 Legal Status ............................................................................................................. 6 Natural Heritage Rank .............................................................................................. 6 Description ............................................................................................................... 7 Similar Species ........................................................................................................ 7 Geographic Range .................................................................................................... 8 Potential Distribution in Wyoming .......................................................................... 8 Extent of Surveys in Wyoming ................................................................................ 9 Habitat ..................................................................................................................... 13 Population Size and Trends ..................................................................................... 15 Population Biology and Ecology .............................................................................. 15 Current Management ................................................................................................ 15 Existing and Potential Threats ................................................................................. 18 Summary .............................................................................................................................. 18 Literature Cited .................................................................................................................. 18 3 Figures, Tables, and Appendices Page Figures 1. Line drawing of Artemisia porteri ................................................................................ 7 2. Photo of Artemisia porteri ............................................................................................. 8 3. Known and potential distribution of Artemisia porteri in Wyoming ........................... 9 4. Habitat of Artemisia porteri ............................................................................................ 13 Tables 1. Locations of Porter's sagebrush in Wyoming ................................................................... 7 2. Species commonly associated with Porter's sagebrush in Wyoming ............................... 14 3. Demographic information for known populations of Porter's sagebrush in Wyoming ... 16 Appendices A. Element Occurrence Records and population maps ....................................................... 21 B. Survey Routes................................................................................................................. 54 C. 1999 Monitoring Data .................................................................................................... 55 D. Potential Habitat Model of Artemisia porteri ................................................................. 64 4 INTRODUCTION Porter’s sagebrush (Artemisia porteri) was first collected by University of Wyoming botany professor Cedric L. Porter near the Sand Draw Oil Field in Fremont County, Wyoming in July 1949. It was described as a new species two years later by Arthur Cronquist of the New York Botanical Garden and named in honor of its discoverer (Cronquist 1951). Over the next 26 years this species was observed at only two other locations in the state and was recommended for listing as Threatened under the Endangered Species Act by the Smithsonian Institution in 1975 (Ayensu and DeFilipps 1978). Surveys by Robert Dorn, Robert Lichvar, Ellen Collins, and B.E. Nelson in 1979 documented two new occurrences and over 25 new subpopulations, prompting the US Fish and Wildlife Service to drop A. porteri from the candidate list in 1983. Due to its limited geographic range and high habitat specificity, Artemisia porteri has remained a species of special concern in Wyoming and was listed as “Sensitive” by the Bureau of Land Management (BLM) Wyoming State Office in 2001. In order to assess the conservation status of this species, the BLM contracted with the University of Wyoming and the Wyoming Natural Diversity Database (WYNDD) to assemble information on the known distribution, abundance, life history, and threats to Porter's sagebrush on public lands in central Wyoming. The results of this study are discussed in the following report. METHODS Information on the habitat and distribution of Artemisia porteri was obtained from scientific literature, specimens from the Rocky Mountain (RM) and Central Wyoming College herbaria, unpublished consultant reports and knowledgeable individuals. USGS topographic maps, geologic maps and BLM land status maps were used to identify areas of potential habitat for ground survey. Field surveys were conducted by Laura Welp and Walter Fertig of WYNDD in August 1999 (survey routes are shown in Appendix B). Data on habitat, reproduction, phenology, and associated species were collected using WYNDD plant survey forms. Locations of occurrences were mapped on 7.5 minute USGS topographic maps and digitized as an Arc-View theme. Voucher specimens were collected for deposit at the RM. Information gathered in the field was entered into the computerized Element Occurrence database of WYNDD. Three permanent demographic monitoring plots were established following the protocol of Lesica (1987). These transects consisted of a single belt 0.5 meters x 50 meters long, subdivided into 0.5 x 1 meter plots. Within each plot, individual plants were counted and assigned to one of four age classes: seedling, vegetative (non-reproductive), reproductive, and dead. This technique was designed to gauge population density and assess population change over time. Data from these transects are included in Appendix C. Rob Thurston of WYNDD and I developed a potential habitat model for Artemisia porteri (Appendix D) using Classification Tree Analysis and GIS (Fertig 1999; Fertig et al. 2002 in ed.; Fertig and Thurston 2002 in ed.). Based on information from WYNDD and RM, we used 19 randomly selected locations of