Sensitive Plant Survey of the Proposed Glendo Silica Quarry Site
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.. - • < • Sensitive Plant Survey of the Proposed Glendo Silica Quarry Site, Platte County, Wyoming Prepared for VA Resources, Ltd. PO Box 3669, Casper, WY 82602 By Walter Fertig, Botanist Wyoming Natural Diversity Database 1604 Grand Ave. Laramie, WY 82070 23 September 1997 ,...--------- Table of Contents Page Introduction . 3 Methods . 3 Study Area . 3 Results ........ .. .. ............ ..................... .. .... 5 Discussion and Management Implications . 5 Literature Cited . 10 Figures 1. Location of the proposed Glendo silica mine permit site and distribution of alpine feverfew (Parthenium alpinum) . 4 2. Photograph of Alpine feverfew (Parthenium alpinum) . 7 Table 1. Common vascular plants of the Glendo quarry site 8 Appendix A. Element Occurrence Record for the alpine feverfew population at the Glendo mine permit site . 11 2 I ' ,. .. Introduction The rolling hills southeast of Glendo, Wyoming, have been identified as a significant source of high grade silica rock used in the manufacture of glass and related products (Harris 1988). This area, called the Cassa silica rock deposit, has recently been proposed as a quarry site. As part of a more comprehensive biological, cultural, and historical clearance of the area, VA Resources, Ltd, of Casper, Wyoming, contracted with the Nature Conservancy's Wyoming Natural Diversity Database (WYNDD) in the summer of 1997 to conduct a plant survey of the permit area. The objective of this study was to document the occurrence of listed or candidate Threatened and Endangered plant species at this site. Methods Prior to conducting an on-site survey, the rare species database of WYNDD was queried to determine if any populations of rare plant or animal species were already known from the mine permit area or its immediate vicinity. This search revealed that there were no known records in the permit area itself, although there were records for the alpine feverfew (Parthenium alpinum), a former candidate for listing, from similar habitats in southeastern Wyoming. An on-site survey was undertaken on 11 September, 1997 focusing on this species as well as the Ute ladies' tresses (Spiranthes diluvialis) and Colorado butterfly plant (Gaura neomexicana ssp. coloradensis), two wetland species already listed or proposed for listing under the Endangered Species Act (Fertig 1997). The entire permit area was explored on foot and notes were taken on the dominant vegetation types, the common plant species present, and the location, abundance, and habitat needs of the target rare species. Study Area The study area is located on State of Wyoming trust lands in the W4 of the NW4 of Section 35 and the E2 of the NE4 of Section 34 of Township 29N and Range 68W in northern Platte County, Wyoming (Figure 1). The mine permit area covers about 40 acres and is located 0.5 miles south of Horseshoe Creek and 1 mile west of the North Platte River on the east side of Wyoming State Highway 319, 5 miles southeast of Glendo. Four main vegetation types are found in the mine permit area. The most extensive of these is a shrub-grassland community dominated by Wyoming big sagebrush (Artemisia tridentata var. wyomingensis), broom snakeweed (Gutierrezia sarothrae), blue grama (Bouteloua gracilis) and needle-and-thread (Stipa comata). This community is found primarily on dry ridgetops and upper slopes of fine clay soils with an abundant surface layer of brown sandstone gravel. Sandier sites and lower ridgeslopes are dominated by a community of silver sagebrush (Artemisia cana var. cana), red three-awn (Aristida purpurea var. longiseta), and blue grama, although Wyoming big sagebrush may also be locally abundant. North-facing low cliffs of sandstone are occupied by small patches of 3 '(" Q' \ Figure 1. Location of the proposed Glendo silica mine permit site and distribution of alpine feverfew (Parthenium a/pim,m). GLENDO ,,,., ., ,~ 00 \, \" # \ , 4153 { np ~ "· 35 ~ \ Key: Yellow area indicates the boundaries of the mine pennit area Black area indicates the approximate location of the six main colonies of alpine feverfew observed in the study area and vicinity. ... .. ponderosa pine (Pinus ponderosa) and Rocky Mountain juniper (Juniperus scopulorum) woodlands with a semi-open understory of little bluestem (Andropogon scoparius), red three-awn, and sideoats grama (Bouteloua curtipendula). The smallest community type consists of mat-forming cushion plants and bunchgrasses restricted to scattered dry ridgetop clearings covered by a "gravel pavement" of broken sandstone fragments or colluvium (Harris 1988). This community is locally dominated by Hooker sandwort (Arenaria hookeri), stemless goldenweed (Haplopappus acaulis), stemless hymenoxys (Hymenoxys acaulis), alpine feverfew (Parthenium alpinum), thread-leaved sedge (Carex filifoha) and sideoats grama. No wetland habitats are found within the study area. Results No populations of Ute ladies' tresses or Colorado butterfly plant were located during this survey. Both of these species are restricted to sub irrigated meadows or riparian habitats where they occur elsewhere in Wyoming (Fertig et al. 1994). No such habitats are present in the permit area. Six small to mid-sized colonies of alpine feverfew were discovered within the study area or immediately to the west of the staked boundaries (Figures 1-2). Most of the colonies were restricted to sparsely-vegetated ridgetops or slopes dominated by low cushion plant communities on dry, gravelly outcrops of Quaternary colluvium or sandstones of the Cretaceous Cloverly Formation (Harris 1988), although two small colonies were found in a rocky ponderosa pine/bunchgrass community near the southwest corner of the permit area. The two largest colonies each contained 150-200 plants in an area of 0. 75-2 acres. The entire population (all 6 colonies) was estimated at approximately 350-480 plants (Appendix A). A brief list of common plant species observed in the study area is included in Table 1. Additional species may be present, but were not in an identifiable condition when this survey was conducted. Discussion and Management Implications Ute ladies' tresses is currently the only Wyoming plant species that is officially listed and protected under the Endangered Species Act (US Fish and Wildlife Service 1996). No habitat for this species is found at the proposed Glendo quarry site and additional surveys for this species at the site are unwarranted. Colorado butterfly plant is currently a candidate for listing under the Endangered Species Act, but is not formally protected on non-federal lands at the present time (US Fish and Wildlife Service 1996). No potential habitat for this species was observed (or is expected to occur) within the permit site. Alpine feverfew was formerly a candidate for listing under the Endangered Species Act, but was dropped from consideration in 1985 due to a lack of identifiable threats to its survival (US Fish and Wildlife Service 1985). Since 1993, 21 new occurrences of this species have been documented in southeastern Wyoming and northeastern New Mexico, suggesting that it is more widespread and abundant throughout its range than was once 5 • r • suspected. In addition, recent studies by Hartman and Nelson (1994) have shown that alpine feverfew occupies a wider range of habitats than previously reported (Fertig et al. 1994), including sandstone grassland and cliff sites similar to those observed at the Glendo quarry site. These discoveries prompted WYNDD to drop alpine feverfew from its list of high priority species of concern to a lower priority "watch list" in 1997 (Fertig 1997). Parthen;um a/p;num is still listed as Sensitive by Region 2 of the US Forest Service, but is not protected by any other public land management agency or by the state of Wyoming. In summary, the discovery of new colonies of alpine feverfew at the proposed Glendo silica mine site is of interest in that it provides additional evidence that this species is more widespread and abundant than formerly thought. The population is not formally protected under the Endangered Species Act or other federal regulations. The loss of habitat at this particular site does not appear to constitute a significant threat to the overall survival prospects of alpine feverfew throughout its range. Figure 2 (page 7). Photograph of alpine feverfew in flower. This member of the sunflower family can be recognized by its marble-like greenish-white flower heads borne among hairy basal leaves. WYNDD photo by W. Fertig from near Alcova, WY, 1 May 1995. 6 Table l . Common Vascular Plants of the Glendo Quarry Site This list is based on a 1-day survey of the site by the author on 11 September 1997. Scientific Name Common Name Trees and Shrubs Artemisia cana var. cana Silver sagebrush Artemisia tridentata var. wyomingensis Wyoming big sagebrush Juniperus scopulorum Rocky Mountain juniper Pinus ponderosa Ponderosa pine Rhus trilobata Skunkbush Ribes cereum var. pedicellare Wax currant Yucca glauca Soapwell Amaranthus sp. Pigweed Antennaria umbrinella Umber pussytoes Arenaria hookeri Hooker sandwort Artemisia campestris Northern wormwood Artemisia frigida Fringed sagebrush Artemisia ludoviciana var. ludoviciana Louisiana sagewort Aster ericoides Heath aster Astragalus sericoleucus Silky milkvetch Calylophus serrulatus Yellow sundrop s Chenopodium pratericola Desert goosefoot Cirsium arvense Canada thistle Cirsium undulatum Wavyleaf thistle Conyza canadensis Canadian horseweed Cryptantha celosioides Cockscomb cryptantha Dalea purpurea Purple prairieclover Erigeron glabellus