Succession is a directional, cumulative change in the species composition (and other community attributes) that occupy a given area, through time.

How much time?  ...is the question.

• Not evolutionary time.  = much too long
• Not seasonal changes.  = too short

Thus, successional time is generally 10's of years to 100's of years  

Table: Stages of Succession

Community Stage	Community Description
Climax	a dynamic equilibrium state of a mature community no longer undergoing succession
Seral	a non-climax community (a sere)
Pioneer	a very young sere

Contrasting Pairs Of Successional Terms:

• primary vs. secondary
• autogenic vs. allogenic
• cyclic vs. directional
• progressive vs. retrogressive
• natural vs. induced

In succession, a community's structure and function change too:

Table: Selected Trends in Succession

Trait Of Succession	Earlier Stages	Later Stages
Biomass	less	more
Physiognomy	simple	complex
Importance of Detritus	less	more
Nutrient Reservoirs	abiotic	biotic
Mineral Cycles	faster	slower
Net 1o Productivity	more	less
Microenvironment	drier	moister
Stability	less	more
Species Diversity	lower	higher
Life History	r	K

Succession can be induced by grazing of domestic animals or other human-mediated perturbation.

Induced Retrogression - any induced change that is perceived to diminish successional attributes, e. g., overgrazing

Induced Progression - any induced change that improves successional attributes. e.g., reseeding

Table: Development of the ecosystem over time occurs simultaneously
with many other changes to produce a given set of ecosystem attributes

Given a certain set of the following controlling factors:	Results in a certain configuration of basic ecosystem attributes
time climate  initial organisms  relief  (topography)  parent material  chance events	Soil Vegetation Consumers  Decomposers  Microclimate

Range Condition Analysis

• Condition of rangeland refers to the configuration of components, NOT growing condition.
• In the past, succession WAS the exclusive basis of evaluating the condition of rangeland. It was called the Quantitative Climax Approach or Dyksterhuis Method.
• Stoddard (1975) said: "Range condition is described by means of condition classes which roughly correspond with stages in secondary succession, i.e., in departure from the climax stage."
• Four classes are used:  poor (early stages), fair & good (middle stages) through excellent (late stages).
• This approach is no longer deemed universally valid, for a variety of reasons, e.g.:
• In the Great Plains, there is less need for any such classification system of range condition, because there is not much to do to affect value for grazing other than change the stocking rate.  Burning and noxious weed control might help, too.  This actually constitutes a management paradigm: usually referred to as extensive.
• Intensive management on the other hand, refers to a higher degree of direct inputs, e.g.,  fertilizer, irrigation, pesticides, mowing, etc.
• Contemporary Range Condition Analysis: why?

• RVR - rating based on specific resource value, e. g., grazing, wildlife, or water
• Rangeland Health: Most widely utilized today by federal agencies, e.g., BLM, FS, NRCS
• State & Transition (briefly)   S&T (illustrated)
• Rangeland Monitoring (briefly)  Rangeland Monitoring (detailed)