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

Fire Regime in a forest: fire spatial extent in hectares

Fires naturally vary in size, depending on climatic conditions, material available to burn, and artificial control. In a healthy fire-adapted ecosystem, fire extent can frequently be small (a few hectares) and less frequently be large (thousands of hectares). In a less healthy system, for example one which has had fire suppression, small fires may be more common due to suppression, but may eventually escape control and become very large due to buildup of vegetation.

Fire Regime in a forest: length of fire events (from hours to weeks)

Fires naturally vary in length, with larger fires tending to burn longer. Longer-burning fires may generally emit more smoke and consume more vegetation, as well as potentially consuming more resources for fire control.

Fire Regime in a forest: occurrence of low intensity (forest litter fire) to high intensity (crown fire) fires

Fires naturally vary in intensity, with low-intensity fires burning the underbrush and forest-floor surface and high-intensity fires burning tree stems and crowns. Although crown fires naturally occur and are not necessarily harmful to forest ecology, they cause more change in forest structure than low-intensity fires.

Fire Regime in a forest: recurrence interval for fires

Each vegetation type will have a range of fire recurrence interval, which will be determined by the dominant pant species, geographic location and other factors. If fire recurrence in a place falls outside this range, then the vegetation type may change in type or structure, which may also cause other secondary changes in geomorphology and habitat quality.

Fire Regime Interval Departure (FRID)

Evaluate the broad ecosystem-level impacts of disruption of pre-European fire regimes associated with fire suppression, land-use change, and long-term ecosystem dynamics. FRID measures the current era (1906 to present) fire frequency patterns against reference conditions that occurred during the pre-European Settlement period. It reflects modern-era difference in fire frequency and potential ecological instability that this divergence might cause. FRID can exist both as a positive (more fire than reference conditions) and negative (less fire than reference conditions) values, and carries some inference regarding ecosystem stability and dynamics of vegetation under current fire management policy.

Fire size by type, size by region, severity, area “treated”

Fires can be tracked using various metrics that can tell us whether or not fires are occurring naturally, or if they are becoming more (or less) severe, larger (or msaller0, or if they are significantly affected by vegetation "treatment".

Fire weather change

Fire weather describes the climatic conditions that contribute to fire ignition, rate of spread, and intensity. Hot, dry, windy conditions are the most likely to foster fire ignition, spread and high intensity. Climate change may change fire weather conditions in forested landscapes.

Forest fuel conditions and trends related to wildfire risks

This indicator will provide information in both tabular and map form on forest fuel conditions and progress in managing forest fuel conditions. Both the public and policy makers want to know where and the how much of the state's forests are in a condition that is resilient to catastrophic wildfires and, over time, is the condition improving or worsening.

Forest structure: Height differentiation index of Von Gadow

Stand structure can be defined as the horizontal and vertical spatial distribution of trees of different diameters and heights in a forest ecosystem. The height differentiation index takes into account variations in tree heights in a forest area. Stand structure heterogeneity (horizontal and vertical) leads to a higher number of species and contributes to higher stability and forest integrity.

Forest structure: Leaf Area Index (LAI)

This is green-leaf area (one side of leaves) per unit area of ground. For conifers, the leaf area is half of the surface area per needle. The LAI can be used to predict primary productivity.