The Johnson OHV area is one of the largest in the Mojave Desert, and draws thousands of OHV enthusiasts each year. OHV use takes a heavy toll on the viability of desert habitat, so much of the area has already been degraded by years of intense OHV use. However, desert plant and wildlife would still be impacted by the heavy military use of the area, and the Marines expect that anywhere from 121 to 189 adult desert tortoises could be impacted in the acquired training lands, although more would be impacted by translocation and testing activities. The military would attempt to mitigate impacts on the crucifixion thorn, a special status plant species that grows in rocky desert washes.
The military assesses that biological resources could benefit overall in areas restricted to public access because the reduced OHV usage would decrease harm to biological resources. The military would designate specific areas for exercises, but other areas would be left relatively untouched. In its survey of the biological resources in the Johnson OHV area, many "highly disturbed" lands were identified as a result of the constant OHV recreation use, including the area photographed below.
However, some of the proposed military exercise routes would still impact areas that could have relatively higher desert tortoise density. The exercise routes are not yet final, and should be adjusted to avoid the most biologically intact habitat. Some of the areas under consideration for high impact exercises are assessed to host tortoise densities up to 31 tortoises per square mile. Not surprisingly, most of the most biologically intact areas appear to be in parts of the OHV area that are less accessible or contain fewer vehicle race course routes.