View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Illinois Digital Environment for Access to Learning and Scholarship Repository Conservation Assessment for the Bigleaf Snowbell (Styrax grandifolius Ait.) Steven R. Hill, Ph.D. Division of Biodiversity and Ecological Entomology Biotic Surveys and Monitoring Section 1816 South Oak Street Champaign, Illinois 61820 Prepared for the U.S.D.A. Forest Service, Eastern Region (Region 9), Shawnee and Hoosier National Forests INHS Technical Report 2007 (65) Date of Issue: 17 December 2007 Cover photo: Styrax grandifolius Ait., from the website: In Bloom – A Monthly Record of Plants in Alabama; Landscape Horticulture at Auburn University, Auburn, Alabama. http://www.ag.auburn.edu/hort/landscape/inbloomapril99.html This Conservation Assessment was prepared to compile the published and unpublished information on the subject taxon or community; or this document was prepared by another organization and provides information to serve as a Conservation Assessment for the Eastern Region of the Forest Service. It does not represent a management decision by the U.S. Forest Service. Though the best scientific information available was used and subject experts were consulted in preparation of this document, it is expected that new information will arise. In the spirit of continuous learning and adaptive management, if you have information that will assist in conserving the subject taxon, please contact the Eastern Region of the Forest Service - Threatened and Endangered Species Program at 310 Wisconsin Avenue, Suite 580 Milwaukee, Wisconsin 53203. 2 Conservation Assessment for the Bigleaf Snowbell (Styrax grandifolius Ait.) Table of Contents Acknowledgments............................................................................................................................4 Executive Summary.........................................................................................................................5 Nomenclature and Taxonomy..........................................................................................................6 Description of the Species................................................................….……..................................7 Habitat and Ecology.........................................................................................................................7 Distribution and Abundance..........................................................................................................11 Protection Status............................................................................................................................13 Life History....................................................................................................................................14 Population Biology and Viability..................................................................................................15 Potential Threats............................................................................................................................17 Research and Monitoring...............................................................................................................20 Restoration.....................................................................................................................................22 Summary........................................................................................................................................23 References......................................................................................................................................24 Websites Consulted........................................................................................................................27 Contacts..........................................................................................................................................28 Appendix 1. Representative specimens of Styrax grandifolius examined or cited in the literature...............................................................................…................29 Appendix 2. The distribution of Styrax grandifolius. Information from herbarium specimens and the literature.........................................32 Appendix 3. Natural Diversity Database Element Ranking System..............................................33 3 Conservation Assessment for the Bigleaf Snowbell (Styrax grandifolius Ait.) ACKNOWLEDGMENTS I would like to thank the staffs of the United States Forest Service, Shawnee and Hoosier National Forests, for the opportunity to compile these conservation assessments and for their invaluable assistance with data and field opportunities. Beth Shimp and Steve Widowski have been particularly helpful in facilitating these cost share agreements. I would also like to thank the grants and contracts staff of the Illinois Natural History Survey and the University of Illinois, Champaign, for their assistance with logistics necessary to complete these reports. Curators of several herbaria, cited in the appendices to this report, were very helpful in allowing access to the collections to obtain data on this plant. Several people also assisted by contributing additional information on this locally rare plant, including George Yatskievych in Missouri, Mike Homoya in Indiana, and Mike Vincent in Ohio. This material is based upon work supported by the U.S.D.A. Forest Service, Eastern Region, under Cost Share Award No. AG03-CS-11090804-024. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the author and do not necessarily reflect the views of the U.S.D.A. Forest Service, Eastern Region. 4 Conservation Assessment for the Bigleaf Snowbell (Styrax grandifolius Ait.) EXECUTIVE SUMMARY This Conservation Assessment is a review of the taxonomy, distribution, habitat, ecology, and status of the Bigleaf Snowbell, Styrax grandifolius Ait., throughout the United States and in the U.S.D.A. Forest Service lands, Eastern Region (Region 9), in particular. This document also serves to update knowledge about the potential threats, and conservation efforts regarding the Bigleaf Snowbell to date. The Bigleaf Snowbell is an individual small tree or colonial shrub varying from 1 – 4 meters tall, with showy, fragrant white bell-like flowers in axillary racemes, and it is normally found on slopes in shade near streams in mesic to dry-mesic upland forests. The species is known only from the United States, and it grows primarily in the southeastern states. It is known historically from fifteen states, from Virginia and Florida west to Illinois, Arkansas and Texas. The Bigleaf Snowbell has not been found in Missouri. It has declined in recent decades and is scarce at the margins of its range in the upper Midwest. Globally, its ranking is G5 (secure world-wide); its National ranking in the United States is NNR (not ranked nationally). It is most common in Georgia, Louisiana, Mississippi, and North Carolina. The Bigleaf Snowbell is listed as Endangered in Illinois and Indiana, and it is presumed Extirpated in Ohio. In Forest Service Region 9, the Bigleaf Snowbell is included on the Regional Forester Sensitive Species list (RFSS) for the Shawnee National Forest but not the Hoosier National Forest where it has not been found. It is at risk at the northern margin of its range. In addition to species listed as endangered or threatened under the Endangered Species Act (ESA), or species of Concern by U.S. Fish and Wildlife Service, the Forest Service lists species that are Sensitive within each region (RFSS). The National Forest Management Act and U.S. Forest Service policy require that National Forest System land be managed to maintain viable populations of all native plant and animal species. A viable population is one that has the estimated numbers and distribution of reproductive individuals to ensure the continued existence of the entity throughout its range within a given planning area. The objectives of this document are to: -Provide an overview of the current scientific knowledge on the species. -Provide a summary of the distribution and status on the species range-wide and within the Eastern Region of the Forest Service, in particular. -Provide the available background information needed to prepare a subsequent Conservation Approach. 5 Conservation Assessment for the Bigleaf Snowbell (Styrax grandifolius Ait.) NOMENCLATURE AND TAXONOMY Scientific Name: Styrax grandifolius Ait. [1789; orig. Styrax grandifolium Ait.] Common Names: Bigleaf Snowbell; Big-leaf Snowbell; Bigleaf Snowbell Bush; Big-leaf Snowbell Bush; Large-leaf Snowbell; Large-leaved Storax Synonymy: none known Class: Magnoliopsida (Flowering Plants - Dicotyledons) Family: Styracaceae (The Storax Family) Plants Code: STGR4 (USDA NRCS plant database, W-1) http://plants.usda.gov/ The woody genus Styrax, described by Linnaeus in 1753, contains approximately 120 species worldwide, most of which are found in the Mediterranean region, Southeast Asia, western Malaysia, tropical America, and warm-temperate North America (Mabberley 1987). Four species grow in North America, north of Mexico, namely, Styrax americanus Lam. (widespread in the southeastern U.S.), Styrax grandiflorus Ait. (also southeastern U.S.), Styrax platanifolius Engelm. ex Torr. (Texas only; includes Styrax texanus Cory), and Styrax redivivus (Torr.) Wheeler of California (Kartesz and Meacham 1999). The genus is the type genus