Environmental Engineering Reference
In-Depth Information
4
Ecosystems: trophic interactions
Jelte van Andel
4.1 Introduction: ecosystems and
biotic communities
other global systems. As to the scales in space and
time, Shugart (1998) referred to Delcourt et al. (1983),
who considered the time and space scale of different
disturbance factors, the ecological mechanisms that are
excited by these phenomena and the patterns produced
by the interactions between the disturbances and the
ecological mechanisms (Fig. 4.1).
The Society for Ecological Restoration (SER Inter-
national; SER 2002; www.ser.org) listed nine attributes
to provide a basis for determining when restoration
has been accomplished. In brief:
Shugart (1998) provided a nice overview of the
development of the ecosystem concept, from which
we take some information. The concept has its roots
in theories regarding the organization and dynamics
of natural systems, which were often seen as a super-
organism (Clements 1916): a highly organized and co-
evolved assemblage of plants and animals interacting
in a dynamic system analogous to the manner in which
cells in an embryo interact to produce an organism.
Tansley (1935) defined the term ecosystem as 'the whole
system (in the sense of physics), including not only
the organism-complex, but also the whole complex
of physical factors forming what we call the environ-
ment of the biome - the habitat factors in the widest
sense'. In brief, the biotic community plus its abiotic
environment act within a space-time unit of any
magnitude. Lindeman (1942), who explicitly con-
sidered a lake as an ecosystem, placed an emphasis
on understanding the material flows into and out of
components of the system. He asserted that a lake could
best be considered as an ecological unit in its own
right. Lindeman's theory nicely integrated the biotic
approach with the functional approach in his so-called
'trophic dynamic viewpoint', including community
change, successional patterns and energy flows.
Odum's (1953, 1971) textbook, Fundamentals of Eco-
logy , was organized around the concepts of ecosys-
tems and their structure and function, with emphasis
on the flows of energy and matter. The processing
of material and forms of energy through terrestrial
systems and the residence time of materials in differ-
ent ecosystems links terrestrial ecosystems directly to
1 the restored ecosystem contains a characteristic
assemblage of the species that occur in the refer-
ence ecosystem;
2 the restored ecosystem consists of indigenous
species to the greatest practicable extent;
3 all functional groups necessary for the continued
development and/or stability of the restored eco-
system are represented or have the potential to
colonize;
4 the physical environment of the restored ecosys-
tem is capable of reproducing populations of the
species necessary for its continued stability or
development;
5 the restored ecosystem apparently functions normally
for its ecological stage of development;
6 the restored ecosystem is suitably integrated into a
larger ecological matrix or landscape;
7 potential threats to the health and integrity of the
restored ecosystem from the surrounding landscape
have been eliminated or reduced as much as
possible;
8 the restored ecosystem is sufficiently resilient to
endure the normal periodic stress events in the local
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