Editing Vegetation (section)

==Dynamics==
Like all biological systems, plant communities are temporally and spatially dynamic; they change at all possible scales. Dynamism in vegetation is defined primarily as changes in species composition and structure.

===Temporal dynamics===
[[File:Last Glacial Maximum Vegetation Map.svg|thumb|Vegetation types at the time of [[Last Glacial Maximum]]]]
Temporally, many processes or events can cause change, but for the sake of simplicity, they can be categorized roughly as abrupt or gradual. Abrupt changes are generally referred to as [[Disturbance (ecology)|disturbances]]; these include things like [[wildfire]]s, high [[winds]], [[landslide]]s, [[flood]]s, [[avalanche]]s and the like. Their causes are usually external ([[exogenous]]) to the community—they are natural processes occurring (mostly) independently of the natural processes of the community (such as germination, growth, death, etc.). Such events can change vegetation structure and composition very quickly and for long periods, and they can do so over large areas. Very few ecosystems are without some disturbance as a regular and recurring part of the long-term [[system]] dynamic. [[Fire]] and wind disturbances are prevalent throughout many vegetation types worldwide. Fire is particularly potent because of its ability to destroy not only living plants but also the seeds, spores, and living [[meristem]]s representing the potential next generation, and because of fire's impact on fauna populations, [[soil]] characteristics and other ecosystem elements and processes (for further discussion of this topic see [[fire ecology]]).

Temporal change at a slower pace is ubiquitous; it comprises the [[ecological succession]] field. Succession is the relatively gradual structure and taxonomic composition change that arises as the vegetation modifies various environmental variables over time, including light, water, and [[nutrient]] levels. These modifications change the suite of species most adapted to grow, survive, and reproduce in an area, causing floristic changes. These floristic changes contribute to structural changes inherent in plant growth even in the absence of species changes (especially where plants have a large maximum size, i.e., trees), causing slow and broadly predictable changes in the vegetation. Succession can be interrupted at any time by disturbance, setting the system back to a previous state or off on another [[trajectory]] altogether. Because of this, successional processes may or may not lead to some static, [[climax community|final state]]. Moreover, accurately predicting the characteristics of such a state, even if it does arise, is not always possible. In short, vegetative communities are subject to many variables that set limits on future conditions' predictability.

===Spatial dynamics===
Generally, the larger an area under consideration, the more likely the vegetation will be heterogeneous. Two main factors are at work. First, the temporal dynamics of disturbance and succession are increasingly unlikely to be in synchrony across any area as the size of that area increases. Different areas will be at various developmental stages due to other local histories, particularly their times since the last significant disturbance. This fact interacts with inherent environmental variability (e.g., in soils, climate, topography, etc.), also a function of area. Environmental variability constrains the suite of species that can occupy a given area, and the two factors interact to create a mosaic of vegetation conditions across the landscape. Only in [[agricultural]] or [[horticultural]] systems does vegetation ever approach perfect uniformity. There is always heterogeneity in natural systems, although its scale and intensity will vary widely.