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West Mojave Plan FEIR/S - Desert Managers Group

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proposed Ord-Rodman DWMA, west of and including the Cinnamon Hills. The USFWS (2002)reported that recreationists used legal routes to gain access to popular staging and camping sites,and that impacts emanated out from such areas, impacting less disturbed habitats. Stow (1988)reported that light OHV activity escalated into heavier use and more impacts. Vollmer et al.(1976) expressed concern that once an area was heavily used, recreationists would abandon thearea in search of new and intact environments.No OHV Impacts or Minimal Impacts Observed: Vollmer et al. (1976) found noindication that driving interfered with rodent reproduction, side-blotched lizard reproduction, oranimal population trends. Few shrubs were outright killed, and plant density and diversityremained essentially unaltered. They found creosote bush recovered if root crowns were notdestroyed; damaged plants were scarcely distinguishable after10 years. It was not clear that thedensity of annuals was reduced by vehicular traffic during their study.OHV Impacts Uncertain: In 2002, the USFWS concluded that reductions in the amountof open routes are likely to provide some level of benefit to the desert tortoise. However, neitherthe BLM nor the USFWS had definitive information on how differing route networks may affectthe desert tortoise; presumably, roadless areas would have the least adverse effect on deserttortoises and their habitat. Vollmer et al. (1976) found it difficult to gauge the impact of lessintensive OHV-use areas. The extent that any changes in the access network affect the deserttortoise would be difficult to measure because of the slow reproductive rate of the species andother factors, such as disease, drought, and predation, that may be affecting the number ofindividuals in a region. No quantitative information was available concerning how frequentlydesert users leave routes of travel to camp, stop, and park outside of existing disturbed areas. Inat least some areas that are occupied by the desert tortoise, the density of vegetation would likelyprevent most desert users from leaving the routes of travel (USFWS 2002).3.3.2.6.5 Off-Highway Vehicle Open AreasRelative Tortoise Occurrence in Open Areas: Eight BLM open areas occur, includingJohnson Valley, Stoddard Valley, El Mirage, Spangler Hills, Jawbone, Dove Springs, Rasor, andOlancha. Jawbone, Dove Springs, and Rasor are on the edge of the 2002 tortoise range, whileOlancha is north of the known range. These areas were either not surveyed (Jawbone orOlancha) during sign count surveys, or no tortoise sign was observed during surveys at Rasor(i.e., 26 of 35 mi 2 , 74%) and at Dove Springs (i.e., 3 of 6 mi 2 , 50%). Survey coverage wasrelatively good at Johnson Valley (231 of 294 mi 2 , 79%), Spangler Hills (i.e., 75 of 97 mi 2 ,77%), and Stoddard Valley (i.e., 63 of 85 mi 2 , 74%), and somewhat less representative of ElMirage (i.e., 16 of 40 mi 2 , 40%). Most of the following discussion is relative to Johnson Valley,Stoddard Valley, El Mirage, and Spangler Hills open areas (see Appendix L for moreinformation).Higher Density Tortoise Areas: Higher density sign count regions within open areas areshown in Map 3-14. There were four higher density tortoise areas in the Johnson Valley OpenArea, comprising 32 mi 2 . Two of these (28 mi 2 ) were contiguous to the Ord-Rodman DWMA.Higher density areas were also found throughout much of the northern part of the StoddardValley Open Area, and were contiguous to higher density areas east of Highway 247, in the Ord-Chapter 3 3-128

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