West Mojave Plan FEIR/S - Desert Managers Group

an excellent opportunity to compare current vegetation data with sites where multiple MGS havebeen observed.The 1998 vegetation data relative to 19 of the 22 Aardahl-Roush sites are given in TableM-1 (Appendix M). Surveys were conducted prior to the current widespread use of GPS units,which is true for most of the non-military surveys up until a few years ago. However, transectslocations were relatively more accurate because their 19 sites were delineated on 7.5’ USGSquad maps, as opposed to CNDDB records, for example, which specify that a given MGS recordoccurred somewhere within a 160-acre, quarter section.Aardahl and Roush (1985) trapped a total of 350 MGS on the 19 sites reported in TableM-1. Like many other studies, they did not differentiate between adults and juvenile MGS, socaptured animals may have either been resident or dispersing through the trap area. That theytrapped the MGS at every site is significant, when one considers recent trapping efforts onregional scales where no MGS have been trapped (see Brooks and Matchett 2001).The 1998 surveys found that creosote bush scrub was found at 12 (63%) of their sites,saltbush scrub at 5 (26%) sites, and blackbush scrub at 2 (11%) sites. Of the 350 MGS trappedin 1985, 235 (67%) were in creosote, 107 (31%) were in saltbush, and the remaining 8 MGS(2%) were found in blackbush scrub. These data reflect what was also found on a regional scalewhen the prevalence of plant communities was compared to historic reports of the MGS: theprevalence of MGS is proportionate to the prevalence of a given plant community (Table 3-34,below), both at a regional level and among the 19 sites trapped by Aardahl and Roush 28 .Winterfat and/or hopsage were observed on 14 (74%) of the 19 sites. On one of the fivetransects where winterfat and hopsage were not observed (Aqueduct South), 16 winterfat plantswere observed in adjacent areas, although none was observed along the transect. On two othersites (Bowman Road South and Kramer Hills), although there were no winterfat or hopsage,chenopods were well represented, with 294 and 141 saltbush found, respectively. Given theseand other observations, it is important to exercise caution in reviewing results, such as the onespresented herein, and applying them to management practices. For example, it would bepremature to identify “source areas” (i.e., areas where MGS persist during prolonged drought)based solely on the presence or prevalence of winterfat and hopsage. However, these results dosupport the hypothesis that chenopods (particularly winterfat and hopsage) may be important toMGS foraging ecology.28 One must exercise caution when accepting plant community designations, for example, like “creosote bush scrub”and “saltbush scrub,” because of the variability of shrubs comprising such communities. Creosote bush (Larreatridentata), from which the community derives its name, is necessarily a part of the so-named plant community, butis often not the most abundant plant. For example, on the 12 Aardahl-Roush sites that LaRue identified as creosotebush scrub, creosote bush was the most abundant plant only on 1 (8%) of the 12 sites. The dominant perennials inthe remaining 11 creosote bush scrub communities included burrobush (Ambrosia dumosa) at 10 (91%) sites andCooper’s goldenbush (Ericameria cooperi) at 1 (9%) site. Burrobush was also the most abundant perennial speciesat 2 (40%) of the 5 sites characterized as saltbush scrub.Chapter 3 3-154