Forest Condition

Invasive, non-native plant species can change the structure an function of ecosystems. As they invade, they will increase their cover of forest and rangeland ground.

Tree crowns are both sites of primary production and habitat for arboreal species. Crowns may be damaged by human activity and pollution (e.g., ozone), as well as disease, insects, storms and fire.

Artificial and natural disturbance is usually followed by regeneration of species removed by the disturbance. Ideally the number of regernating native woody species will be close to expected, after disturbance.

Soil conditions can determine site productivity. This indicator uses soil horizon depth, compaction, condition and type to classify soils according to their humus condition. The index has been shown to correlate with stand productivity.

Trees and other plants require soil penetration to reach nutrients, avoid desiccation, and for physical stability. Soils and underlying geology will affect the depth to which plants can root, which will in turn affect plant survival and fitness.

This indicator will produce tabular and graphical information on the spread of selected invasive species and on the success in controlling new invasive species introductions. Invasive species constitute a major threat to the integrity of native forest ecosystems. Mild climate coupled with increases in commerce and influxes of new people have facilitated the introduction and spread of invasive pests. Invasive species reduce the diversity found in native forests and adversely affect populations of native species through predation, competition, altered fire regimes, or destruction of habitat.

Trees die for a variety of reasons, creating habitat, contributing to soil carbon and nutrients, and creating openings. Rates of mortality can indicate natural die-off of old or sick/damaged trees or forest and trees that are overly-stressed because of climatic, artificial, and pest sources of stress.

Forests are adapted to natural cycles of drought, flooding, and storms (wind, ice). Natural ranges of weather severity may result in changes in forest structure and composition. When events fall outside natural ranges of severity and frequency, the result may be large-scale die-offs of forest areas.

The Carbon to Nitrogen (C/N) ratio compares the amounts of these two important solid components. This ratio is indicative of nitrogen limitation in soils, which may limit plant growth.

Defoliation can be caused by disease, physical force (extreme storms), and pest insects. Most trees can recover from defoliation, but it can be a serious source of stress and will reduce photosynthetic activity and growth.