4: Conservation and maintenance of soil and water resources

Soil and water underpin forest ecosystem productivity and functions. Forest ecosystems play an important role in the regulation of surface and groundwater flow and, together with associated aquatic ecosystems and clean water, they are essential to the quality of human life. The interaction of soil, water and topography influence the character and health of streams and rivers flowing through and from forests. Monitoring change in the chemical, physical, and biological characteristics of soil, water and aquatic systems provides valuable information to support sustainable forest management.

Forest management activities can significantly alter forest soils, water quality and associated aquatic habitats. Inappropriate management may result in soil compaction, the loss of the soil A horizon, loss of riparian buffering capacity, increased sediment loads in streams, degradation and destruction of aquatic habitats and altered flow regimes. Change in water flow can also create an increased risk of flooding or the complete desiccation of streams. Both have harmful implications for human safety, property, and economies. Soil and water resources may be protected through the allocation of land for that purpose or through appropriate management regimes and best management practices.

Associated Indicators

Number or proportion of impaired waterbodies (303d)

Listing water-bodies under the Clean Water Act, section 303(d) is conducted when these water-bodies are found to be demonstrably impaired by pollutants (e.g., temperature, nutrients, sediment, mercury). The Regional Boards are responsible for listing water-bodies within each region, so comparisons are best made within regions, not among regions across the state.

Percent and area of surface water bodies on rangeland with impaired water quality

Characterize the general status of surface water quality on California rangelands. This indicator measures the percentage or area of surface water bodies with impaired water quality, when compared with beneficial uses defined under the Clean Water Act. Surface water includes the length of small, medium, and large streams and rivers, and the area of lakes and reservoirs. Impairment may be reflected in 303-d listings of watersheds where ranching uses are identified as source of pollution.

Percent and area of surface water bodies on rangeland with impaired water quality

Characterize the general status of surface water quality on California rangelands. This indicator measures the percentage or area of surface water bodies with impaired water quality, when compared with beneficial uses defined under the Clean Water Act. Surface water includes the length of small, medium, and large streams and rivers, and the area of lakes and reservoirs. Impairment may be reflected in 303-d listings of watersheds where ranching uses are identified as source of pollution.

Percent of stream miles in rangeland catchments in which stream channel geometry significantly deviates from the natural channel geometry

This indicator tracks changes in stream channel geometry (that is, in cross section, in profile, and in channel bed materials) from a baseline condition. Changes in cross section are defined by the width/depth ratio at “bankfull” stage. Changes in profile are defined by sinuosity and channel slope. Changes in bed material are defined by the particle-size distribution of materials comprising the streambed. Baseline conditions can be defined by natural, historic, or reference channels located in the same hydro-physiographic position on the landscape. Changes in channel conditions in a rangeland watershed correspond to changes in streamflow and sediment supply in the basin, as well as human manipulation of the channels, and therefore are a good indicator of sustainable rangeland management.

Percent of surface water on rangeland areas with unacceptable levels of chemical, physical, and biological properties

This indicator measures the percent of surface water with impaired water quality, when compared with beneficial uses defined under the Clean Water Act. Surface water includes the length of small, medium, and large streams and rivers, and the area of lakes and reservoirs. Water quality criteria are defined that protect beneficial uses and include ambient concentration of an important parameter such as dissolved oxygen, pH, temperature, or heavy metals. An LD50 or other metric of these parameters is used to ensure that the designated use or uses for a given water segment are not impaired. Impaired water quality means that one or more of the criteria adopted to protect the designated use or uses of an individual water body segment are not being met. Leading causes of water quality impairment in our nation are excess nutrients (nitrogen and phosphorus), sediment/siltation, pathogens, and metals.

Percent of water bodies in rangeland areas with significant changes in aquatic biota assemblage composition

The importance of this indicator lies in its relation to watershed conditions and natural biological diversity. To estimate rangeland condition and trend in condition, plant composition existing at a given moment in time is compared with the plant composition that the given area is capable of supporting at its potential. Downward trends in rangeland condition can also be associated with declines in water quality, aquatic and riparian habitats, and the ability of aquatic habitats to support native biota. These changes can cause aquatic native biota assemblages to shift away from that which would be expected to occur under natural, unimpaired hydrologic conditions.

Plant community composition and distribution relative to infiltration and runoff

Vegetation growth form is an important determinant of infiltration rate and interrill erosion. The distribution of the amount and type of vegetation has been found to be an important factor controlling spatial and temporal variations in infiltration and interrill erosion rates on rangelands in Nevada, Idaho, and Texas.