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The composition of a forest is a reference to the biodiversity of the
landscape; this includes a diversity of vegetation species, types (e.g.,
trees, shrubs, forbs, etc.), and distribution. Tree species composition
affects many aspects of forest dynamics and function. A diversity of tree and
shrub species can confer greater resilience to climate change and beetle
outbreaks. The vegetation composition also affects fire dynamics, water
reliability, carbon pools and sequestration, and economic diversity pillars.
Since European settlement and the adoption of fire suppression and logging,
forests of the Sierra Nevada shifted to increased dominance of shade-tolerant
and fire-intolerant species like white fir and red fir, incense cedar, Douglas
fir, and tanoak. Other species like ponderosa pine, Jeffrey pine, sugar pine,
and black oak, which are more shade-intolerant and fire-tolerant, declined in
coverage. With increasingly larger and higher-severity fire occurring, forest-
cover loss may be significant and shrub cover will increase.

The Composition Element is described in the RRK by six metrics: seral stage
(early and late), tree cover, shrub cover, herbaceous cover, absolute change
in herbaceous cover, and distribution of obligate resprouting, obligate
seeding, and facultative seeding shrub species (and tree and herb). One metric
was selected to represent resilience for the forest and shrubland composition
element: tree cover (indicated by an asterisk). Condition scores range from +1
to -1 representing more favorable to less favorable conditions, respectively.
The Element condition score is the same as the tree cover.

* Metric Name: Element representation: Composition   

* Translation: Where is forest composition most resilient?