Inventory of Western Spiderwort {Tradescantia occidentalis) in Alberta, 2002 Alberta Species At Risk Report No. 61 Inventory of Western Spiderwort (Tradescantia occidentalism in Alberta, 2002 Sue Peters Alberta Species At Risk Report No. 61 January 2003 Project Partners: ydlbsffa Canada SUSTAINABLE RESOURCE DEVELOPMENT Alberta Conservation Association Publication No.: 1/092 ISBN: 0-7785-2335-7 (Printed Edition) ISBN: 0-7785-2336-5 (On-line Edition) ISSN: 1496-7219 (Printed Edition) ISSN: 1496-7146 (On-line Edition) Illustration: Brian Huffman For copies of this report, contact: Information Centre - P ublications Alberta Environment/Alberta Sustainable Resource Development Fish and Wildlife Division Main Floor, Great West Life Building 9920 - 108 Street Edmonton, Alberta, Canada T5K 2M4 Telephone: (780) 422-2079 OR Information Service Alberta Environment/Alberta Sustainable Resource Development #100, 3115- 12 Street NE Calgary, Alberta, Canada T2E 7J2 Telephone: (403) 297-6424 Or visit our web site at: http://www3.gov.ab.ca/srd/fw/riskspecies/ and click on “Reports” This publication may be cited as: Peters, S. 2003. Inventory of Western Spiderwort (T radescantia occidentals ) i n Alberta, 2002. Alberta Sustainable Resource Development, Fish and Wildlife Division, Alberta Species At Risk Report No. 61. Edmonton, AB. 16 pp. li DISCLAIMER The views and opinions expressed are those of the author and do not necessarily represent the policies or positions of the Department or of the Alberta Government. Digitized by the Internet Archive in 2016 https://archive.org/details/inventoryofweste00pete_0 TABLE OF CONTENTS Acknowledgements. vii Executive Summary. v iii 1 .0 Introduction 1 2.0 Study Area. 2 3.0 Methods 2 4.0 Results. 5 5.0 Discussion. 10 6.0 Management Implications and Future Directions 11 7.0 Literature Cited. 13 Appendices 15 v LIST OF FIGURES Figure 1. Western spiderwort inventory locations in 2002: Pakowki Lake North (1), Pakowki Lake South (2), and Lost River (3). See Table 1 for more details of each location 4 LIST OF PHOTOS Photo 1. The habitat at patch 1 6 Photo 2. The habitat at patch 2 6 Photo 3. The habitat at patch 3 7 Photo 4. The habitat at patch 4... 7 Photo 5. The habitat at patch 5 8 Photo 6. The habitat at patch 8, looking north to patches 9-14 8 Photo 7. The habitat at patches 9-14 ....9 Photo 8. The habitat at patch 15 9 LIST OF TABLES Table 1: Description of western spiderwort inventory locations within the study area in southeastern Alberta. 3 LIST OF APPENDICES Appendix 1 : Summary of the 2002 western spiderwort inventory data for Alberta 15 Appendix 2: Monthly total precipitation (mm) for Medicine Hat, Manyberries and Onefour, Alberta, in years that western spiderwort has been inventoried (1986, 1987, 1990, 1999, 2001,2002) 1 6 vi ACKNOWLEDGEMENTS Richard Quinlan (Alberta Sustainable Resource Development) initiated this project, as part of the larger Milk River Basin Species At Risk Project. Thanks to Joel Nicholson (Alberta Sustainable Resource Development), Terry Hood (Public Land Specialist with Agriculture, Food and Rural Development), Dale Eslinger (Alberta Sustainable Resource Development), Vem Peters (University of Alberta), Reg Ernst (ecological consultant) and Terry Clayton (Alberta Sustainable Resource Development) for their assistance in the field. Much appreciation is extended to the landowners and leaseholders who granted us land access permission to conduct the inventory. Ksenija Vujnovic (Alberta Natural Heritage Information Centre, Parks and Protected Areas, Alberta Community Development), Joyce Gould (University of Alberta), Bonnie Smith (botanical consultant), and Cliff Wallis (Cottonwood Consultants Ltd.) provided very helpful botanical advice. Erin Anderson (Geowest Environmental Consultants) provided information on additional sand dune vegetation surveys conducted (independent of the western spiderwort project) in 2002. John McIntyre (Environment Canada) provided weather data for southeastern Alberta. Robin Gutsell (Alberta Sustainable Resource Development), Dawn Bim and Ksenija Vujnovic reviewed an early draft of the report. Funding for this project was provided by the Alberta Conservation Association and the Government of Canada Habitat Stewardship Program for Species at Risk. The Fish and Wildlife Division of Alberta Sustainable Resource Development provided valuable in-kind support. vii EXECUTIVE SUMMARY Alberta Sustainable Resource Development (Fish and Wildlife Division), together with the Alberta Conservation Association, initiated an inventory of western spiderwort (T radescantia occidentalis) in southeastern Alberta in July 2002. The objective of this inventory was to provide an updated population estimate for western spiderwort in Alberta, which has been recommended by the Alberta Endangered Species Conservation Committee as Endangered. The only known population at the Pakowki Lake Sandhills near Manyberries was surveyed, as well as the surrounding habitat. Two other locations with suitable habitat in southeastern Alberta were also surveyed, including the sandhills southeast of Pakowki Lake, and those close to Onefour (near the Lost River). Other potential western spiderwort habitat in Alberta was searched in 1987 (Wallis and Wershler 1988), but could not be searched again in 2002. The presence of western spiderwort was confirmed only at the Pakowki Lake Sandhills near Manyberries. A l arge number of plants was found at this location, so only a p ortion of the total population could be counted, while the remainder was extrapolated using GPS polygons. A t otal of 1,255 plants (defined as clumps of multi-stemmed shoots, based on Smith 2001a) was counted, and the total Alberta population was estimated to be approximately 7,450 plants (19,750 shoots). The small area where the previously known population was located contained only 16 of these plants (48 shoots). The population was scattered over an area of approximately 19,890 m2 (area of occupancy of 0.02 km2), based on the total area of the GPS polygons delineating patches of plants. Their extent of occurrence (the total area encompassing all patches of plants and the area between them) was approximately 2 k m2. In 2002, western spiderwort plants had an average of 2.9 shoots per plant. On average, 95% of plants were reproductive (mean of 2.2 flowers per plant). Eighty-nine percent of the counted portion of the population had developing capsules (fruit structures), an indication of good seed production and future population potential. Browsing was patchy, ranging from 0-44% (average 15%) of plants within different patches. Browsing did not appear to be inhibitive for the population and was likely done primarily by native herbivores, because cattle had not yet (in 2002) been allowed to graze in most of the area where spiderwort was growing. Precipitation records for Onefour, Alberta during the spring and summer of 2002 show much higher than average precipitation levels. The relatively large population of spiderwort close to that area this year seems to agree with previous observations that western spiderwort populations fluctuate with moisture. The population of western spiderwort seems to be resilient to at least short periods of drought in southern Alberta. More widespread inventories of western spiderwort need to be conducted in Alberta in years of high spring moisture. viii