Forest dynamics
Forest dynamics describes the underlying physical and biological forces that shape and change a forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...

. That is, the continuous state of change that alters the composition and structure of a forest.
Two basic elements of forest dynamics are: forest succession (or ecological succession
Ecological succession
Ecological succession, is the phenomenon or process by which a community progressively transforms itself until a stable community is formed. It is a fundamental concept in ecology, and refers to more or less predictable and orderly changes in the composition or structure of an ecological community...

) and forest disturbance.


Forest disturbance is an event that causes changes in the structure and composition of the forest such as fire, flood, wind, or earthquake, or mortality caused by insect, disease outbreaks. Forest disturbance can also be caused by humans, such as timber
Timber may refer to:* Timber, a term common in the United Kingdom and Australia for wood materials * Timber, Oregon, an unincorporated community in the U.S...


Stand-replacing disturbance

A major disturbance that removes most or all of the existing trees in a forest is called a "stand-replacing" disturbance. This begins the first stage of forest succession called "stand initiation". Trees that arrive by seed begin to grow. When the canopy becomes closed the second stage "stem exclusion" begins. Trees begin to compete for light and mortality rate becomes high. At this point the canopy will be relatively smooth and consist one dominant cohort
Cohort (statistics)
In statistics and demography, a cohort is a group of subjects who have shared a particular time together during a particular time span . Cohorts may be tracked over extended periods in a cohort study. The cohort can be modified by censoring, i.e...

 (age group).

As the trees which make up the canopy begin to age, mortality rate may be high as the trees are the same age. "Understory reinitiation" begins. The crowns of the largest trees are now big enough and the growth rate of the mature trees slow that canopy gaps
Gap (ecology)
In forest ecology, a treefall gap is an opening in the forest canopy structure devoid of large trees. Gaps are formed after large trees die and fall which allows the regrowth trees and other plants as the shade is removed.-References:...

are filled with a younger cohort. The forest will now consist of two age classes. At some point there will be few or no remaining trees of the original cohort. The forest will consist of many age classes. Mortality is continuous. When large individual trees die large gaps are created in the canopy. This is a late-succession forest.
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