Rangeland

JOHN DAVID SWANSON, range conservationist, Soil Conservation Service, helped prepare this section.

About 15 percent of the survey area is rangeland. Less than 1 percent of the annual farm and ranch income is derived from the cattle industry. The major rangeland areas are in the mountains along the coast north of Santa Cruz and in the southeastern quarter of the county. Many areas have been cleared of native brush and trees, and these areas provide good range forage for livestock and wildlife. Introduced annual grasses and forbs have replaced the native perennial grasses and presently constitute most of the range forage production in most areas of the county.

The soils in the northern areas of the county generally are loamy and are very shallow over fractured mudstone or sandstone. These soils support annual grasses and forbs and some areas of shrubs and coastal live oak. The direct influence of coastal fog appreciably increases the annual production of vegetation. In much of the southeastern part of the county, the soils are deep loams that have moderate to high available water capacity and good fertility. These soils support stands of shrubs that provide browse; they also support stands of annual high producing grass.

The major management concern on most of the range land is to control grazing in order to maintain or increase the kinds and amounts of desirable plants that make up the optimum plant community for livestock and wildlife. Controlling brush and minimizing soil erosion are also important management concerns. If sound range management based on the soil survey information and rangeland inventories is applied, there is good potential for increasing the productivity of the rangeland in the survey area.

In areas that have similar climate and topography, differences in the kind and amount of vegetation that range land can produce are related closely to the kind of soil. Effective management is based on the relationships among soils, vegetation, and water.

Table 2 shows, for each kind of soil, the name of the range site; the total annual production of vegetation in favorable, normal, and unfavorable years; the characteristic vegetation; and the expected percentage of each species in the composition of the potential natural plant community. Soils not listed cannot support a natural plant community of predominately grasses, grasslike plants, forbs, or shrubs suitable for grazing or browsing. The following are explanations of column headings in table 2.

A range site is a distinctive kind of rangeland that differs from other kinds of rangeland in its ability to produce a characteristic natural plant community. Soils that produce a similar kind, amount, and proportion of range plants are grouped into range sites. For those areas where the relationship between soils and vegetation has been established, range sites can be interpreted directly from the soil map. Properties that determine the capacity of the soil to supply moisture and plant nutrients have 53 the greatest influence on the productivity of range plants. Soil reaction, salt content, and a seasonal high water table are also important.

Total production refers to the amount of vegetation that can be expected to grow annually on well managed rangeland that is supporting the potential natural plant community. It is expressed in pounds per acre of air-dry vegetation for favorable, normal, and unfavorable years. In a favorable year the amount and distribution of precipitation and the temperatures are such that growing conditions are substantially better than average; in a nor mal year these conditions are about average for the area; in an unfavorable year, growing conditions are well below average, generally because of low available soil moisture.

Dry weight refers to the total air-dry vegetation produced per acre each year by the potential natural plant community. Vegetation that is highly palatable to livestock and vegetation that is unpalatable are included. Some of the vegetation can also be grazed extensively by wildlife.

Characteristic vegetation-the grasses, grasslike plants, forbs, and shrubs that make up most of the potential natural plant community on each soil-is listed by common name. Under Composition, the expected proportion of each species is presented as the percentage, in air-dry weight, of the total annual production of herbaceous and woody plants. The amount that can be used as forage depends on the kinds of grazing animals and on the grazing season. Generally all of the vegetation produced is not used.

Range management requires, in addition to knowledge of the kinds of soil and the potential natural plant community, an evaluation of the present condition of the range vegetation in relation to its potential. Range condition is determined by comparing the present plant community with the potential natural plant community on a particular range site. The more closely the existing community resembles the potential community, the better the range condition. The objective in range management is to control grazing so that the plants growing on a site are about the same in kind and amount as the potential natural plant community for that site. Such management generally results in the maximum production of vegetation, conservation of water, and control of erosion. Some times, however, a range condition somewhat below the potential meets grazing needs, provides wildlife habitat and protects soil and water resources.