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TD21 As the base of the hills is approached the vegetation turns mixed and weedy, Figures TD6 and TD11. This condition persists up to the base of the calcined clay and into the vales between the ridges. The vegetation in these areas is'dominated by two shrubs, two grasses and one forb, Table TD3. The grasses are the better forage. The "lithic entosol" layer where the calcined clay outcrops supports an impoverished vegetation dominated by ponderosa pine, four shrubs and one forb, Table TD3, Figures TD12 and TD13. The shrub cover is quite good on north slopes, Figure TD13, but it is thin on west exposures. The mountain mahogany is an excellent browse plant. A total of 68 species of plants were identified at Dawson. These included two trees, 11 shrubs, 17 grasses and sedges and 38 forbs, Table TD4. The list includes one tentatively identified as Lechia, which is rare in Colorado (footnote to Table 7D4). Here, as elsewhere, the extended search required to assure that unique, rare or endangered plants were not present, could not be made. It should be pointed out, however, that calcined clay layers are not common. Furthermore, there is evidence elsewhere that underground fires may encourage genetic changes in plants. The lithic entosol on the calcined clay must therefore be regarded as a potential habitat for rare or unique plants, even though none was found. Productivity of the range at Datirson was rated poor by Dr. iJallace Johnson. He estimated average yeild of forage plants at not more than 400 pounds per acre for the grasslands, excluding the shrub type on the lithic entosol. Each area of grassland taken out of production therefore represents a present loss of about 8 cow-days of grazing annually. The shrub lands are important for ~•rinter range. As these lands are being grazed in the summer, they likely are not being used for 4rinter grazing of livestock.