3: Maintenance of forest ecosystem health and vitality

The maintenance of forest health and vitality is dependent upon the ability of the ecosystem’s functions and processes to recover from or adapt to disturbances. While many disturbance and stress events are natural components of forest ecosystems, some may overwhelm ecosystem functions, fundamentally altering their patterns and processes and reducing ecological function. Decline in forest ecosystem health and vitality may have significant economic and ecological consequences for society including a loss of forest benefits and the degradation of environmental quality. Information gained on the impacts of biotic and abiotic processes and agents may inform management strategies to minimize and mitigate risk. The maintenance of forest ecosystem health and vitality is the foundation of sustainable forest management.

Associated Indicators

Acreage of timberland in need of restoration treatments to reduce or increase stocking

Quantifying reforestation and/or other silvicultural treatment needs provides insights on potential technical and financial assistance opportunities. Data are available for California timberland as a whole and separately for National Forests on reforestation needs. Data on forest area requiring treatments to reduce stocking may be provided in other chapters of the assessment and will be used to evaluate this indicator.

Amount of fuel treatment acres by treatment type and fuel type.

Both ecological disruption of natural fire regimes and in situ conditions of high hazard systems create support for land management policy using active treatment to reduce fuel hazards. We will evaluate recent fuel treatment activities by type of treatment and fuel type to evaluate whether this policy is effectively addressing both ecological and social concerns of adverse impacts from wildfire

Amount of wildfire by fuel type

Evaluate changing conditions in fire activity as they might relate to changes in fire hazard as a result of fuel dynamics, climate influences, and land-use patterns. This will be reported as acres burned by bioregion/fuel type by decade. Past analyses have indicated recent significant trends in increased amount of wildfire.

Biodiversity: Number of forest fragments in each size class

Forest fragmentation can affect richness and distribution of various wildlife and plant species. If native forest occurs primarily in small size class fragments (e.g., 10-100 Ha), it is likely that species dependent on large forest patches will be absent or in decline.

Climate change effects on fire season and fire severity

Climate change is likely to have many effects on natural, fire-prone systems. Some effects include: warming that leads to faster and more prolonged drying, shorter and/or more variable wet seasons, and increased tree mortality (and thus fuel load) due to stress from drought and warming.

Composition, diversity, and structure of forest vegetation

This indicator will provide tabular and graphical information about forest vegetation. A forest vegetation map is also desirable, but such a map will be a product of future assessment work and not a product of this indicator. The composition, diversity, and structure of vascular plants are important factors in assessing biological diversity of forested ecosystems. Vegetation is the source of primary production and a primary determinant of habitat for many species.

Conservation of Biological Diversity: Forest density

Forests naturally vary in density (i.e. number of trees per unit area). The impact of this density will vary with climatic conditions, soils, tree age/size class, and tree type.

Conservation of Biological Diversity: Status of forest and woodland communities of concern relative to the total

The proportion of all forest types that are considered under some kind of threat, in decline, or relatively rare compared to historic forests provides useful information about the level of threat to biodiversity in the region of interest.

Ecological Condition: Forest Extent and Type

While the amount of US forest land has remained nearly unchanged since the beginning of the 20th century, regional changes both in amount and types of forest cover have occurred as a result of changing patterns of agriculture and development. The distribution of various forest cover types is a critical determinant of the condition of forest ecosystems.

Fire regime departure metrics

Patterns and types of fires can depend on the type of dominant vegetation in an area. Fire frequency is an important characteristic of fire regimes for particular vegetation types. If a fires normally occur frequently for a particular type of vegetation in an area, but now occur infrequently, this can lead to increased risk of fire and fire severity in the future. The degree of departure of fire regimes from a normal range indicates risk from wildfire.