Forest Inventory and Analysis National Program

Program Features

Forest Health Indicators

Crown Condition Indicator

Many physical and biological components influence forest trees. Individual sapling and tree growth and vigor are determined by a variety of physiological and external effects, such as age, available light, water, and nutrients. Since tree crowns are a component of forest ecosystem structure, they directly affect the composition, processes, and vigor of the understory plant and animal components of the forest.

Why is the Crown Condition Indicator Important?

Information about crowns can be used to answer questions about forest ecosystems such as:

• What proportion of trees (by species and forest type) in a region have more crown dieback or less crown density than normal?
  
  
• Is there a regional change in the proportion of trees (by species and forest type) that show a change in crown condition?
  

The crown is one component of net primary production and its dimensions reflect general tree health. Large, dense crowns are associated with potential or previous vigorous growth rates. Small, sparse crowns suggest unfavorable site conditions (such as competition from other trees, moisture stress, or moisture excess) or other influences (such as insect defoliation, foliage diseases, or hail storms). Some changes in crown measurements may be temporary, especially when the stressing condition can be eliminated or reduced. Continued poor conditions however, may be reflected in a tree with increasingly poor vigor.

Tree crown information contributes to the investigation of several key forest ecosystem attributes: biodiversity, productivity, sustainability, aesthetics, forest environment, and wildlife.

For more information about the Crown Condition Indicator visit the Crown Indicator website http://srsfia2.fs.fed.us/crowns/index.shtml .