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

Predicted change in precipitation & variation

As the climate naturally varies and is forced by climate change, precipitation amounts and timing are likely to change. Climate change models suggest that, in the future, California will have less winter snow and more rain-on-snow events. Precipitation may also vary spatially compared to its current distribution. Because both natural processes and economic activities depend on a certain range of precipitation amounts and timing, these potentially new conditions could result in both ecosystem and economic disruptions.

Snow Pack – April 1st (percent of normal)

Evaluate water availability from snow pack. April 1st is considered to be the peak of snow accumulation and can be used as a benchmark. By comparing the April 1st snowpack from the current year against the historic average the indicator can be used to measure if the peak snow pack for the given reporting period is above or below the historic average. This gives an indication of future water supply and seasonable water availability; potential effects on forest vegetation.

Soil surface loss or degradation

The loss or degradation of part or all of the soil surface layer or horizon is an indicator of a loss in site potential. In most sites, the soil at and near the surface has the highest organic matter and nutrient content. This generally controls the maximum rate of water infiltration into the soil and is essential for successful seedling establishment.

Soil surface resistance to erosion

This indicator assesses the resistance of the surface of the soil to erosion. Resistance depends on soil stability, microtopography, and on the spatial variability in soil stability relative to vegetation and microtopographic features. The stability of the soil surface is key to this indicator. Soil surfaces may be stabilized by soil organic matter which has been fully incorporated into aggregates at the soil surface, adhesion of decomposing organic matter to the soil surface, and biological crusts. The presence of one or more of these factors is a good indicator of soil surface resistance to erosion.

Spring Runoff from Major Watersheds (April – July)

Evaluate impact of warmer climate conditions on spring runoff, timing of peak flows, and seasonal water availability. This is calculated as the percent of the total water year runoff derived in Spring (April – July). Spring warming releases water as snowmelt. Recent studies by DWR show a declining trend in Spring runoff that is indicative of warmer winters and earlier Spring warming. This has implications on water availability across a range of beneficial uses. In addition, it can lead to reduced base flows and that may lead to early drying of forest vegetation and effect wildfire conditions.

Upland watershed condition for water production

Healthy, intact watershed uplands are more likely to collect, store, and gradually release water to downstream areas. The largest surface water reservoirs in California are the snow-covered upper watersheds in the Sierra Nevada, which release their water through spring melt and into summer.

Water quality indicators

There are dozens of possible water quality indicators, some of which were used previously in the 2003 and 2010assessments: temperature, sediment, nutrients, and herbicides. Indicators of water quality can be combined into a water quality index, depending on the availability of information about specific indicators.

Water quality of forest streams

This indicator will help assess the quality of water in forest streams. This indicator will provide tabular, graphical, and map information that integrates complex analytical water quality data and generates a single number expressing the degree of impairment of a given water body. Data for this indicator will be used to report the status of specific forest stream reaches and miles of forest streams or the percent of forest stream miles with a poor, fair, or good water quality index.