Environmental Engineering Reference
In-Depth Information
Gleasonian
succession theory
An explanation of succession emphasizing the importance
of the attributes of individual organisms as the fundamental
basis.
Indicator species
Plants or animals whose presence implies the past or pres-
ent conditions at a given location.
Monoclimax
The concept that one mature vegetation will eventually be
produced by successional processes in a given region.
Polyclimax
The concept that multiple mature, stable-vegetation types
can develop from the successional processes operating in
a given region.
SIGMATIST
A school of vegetation science emphasizing the classifica-
tion of vegetation.
Time-for-space
substitution
The collection of vegetation data from different locations
at which succession has been initiated at different times in
the past to piece together the pattern of succession.
Definition of the Subject and Its Importance
“Ecological Succession” is an ordered progression of structural and compositional
changes in communities toward an eventual unchanging condition, the climax
community [
1
-
3
]. The term “Community” is used in two ways [
4
]. The “Abstract
Community” refers to an abstract group of organisms that recurs on the landscape,
a definition, which usually carries with it an implication of a level of integration
among its parts that in extreme could be called organismal or quasi-organismal; the
“Concrete Community” concept refers to the collection of organisms found at
a specific place and time. These terms and their meanings are topics of significant
debate among ecologists, both historically and today [
5
,
6
]. These differences in the
meaning and cause of ecological succession strongly affect the formulation of
policies for ecosystems management and restoration.
Succession is important in sustainability science for several reasons: Many of the
laws and regulations regarding the maintenance and restoration of terrestrial
ecosystems contain assumptions that are products of different theories as to how
ecological succession proceeds in a given environment. Laws might require resto-
ration to a natural condition, which is often the vegetation that is considered the
stable single vegetation type on a map that is itself based on the idea that vegetation
undergoes succession a vegetation type appropriate to the climate (the climax
vegetation). Further, the management of land systems often has as their basis
concepts as to how succession works. For example, if one subscribes to
a successional theory that abused land under an inappropriate management scheme
will return to its natural state if the inappropriate management is relaxed, then one
can utilize land until monitoring indicates the ecosystem is over stressed. If an
