EP 1165-2-502
30 Sep 99
7. Ecosystem Restoration Philosophy and Policy.
a. Ecosystem. An ecosystem is a biotic community together with its physical environment,
considered as an integrated unit. Implied within this definition is the concept of a structural and
functional whole unified through life processes. An ecosystem may be characterized as a viable
unit of community and interactive habitat. Ecosystems are hierarchical and can be viewed as
nested sets of open systems in which physical, chemical and biological processes form interactive
subsystems. Some ecosystems are microscopic and the largest comprises the biosphere.
Ecosystem restoration can be directed at different sized ecosystems within the nested set, and may
encompass multiple states, more localized watersheds, or a smaller complex of aquatic habitat.
b. Habitat in the Context of Ecosystem Restoration. Historically, the concept of habitat in
animal ecology focused on the environment through the needs of individual species or small groups
of species. In this narrow context, habitat represents the location that is or could be occupied by
specific populations within a community of populations, often characterized by structural features.
In a broader view, habitat is the environmental setting of an entire community of plants, animals
and microorganisms. Additionally, habitat can be used in conjunction with indicator species to
help assimilate information about various components of ecosystem structure and function. These
views of habitat, which emphasize the importance of functional and structural integrity of the
community-habitat complex, are supportive of the holistic concept of ecosystem function and
structure.
c. Ecosystem Restoration is a primary missions of the Civil Works program. Civil Works
ecosystem restoration initiatives attempt to accomplish a return of natural areas or ecosystems to
a close approximation of their conditions prior to disturbance, or to less degraded, more natural
conditions. In some instances a return to pre-disturbance conditions may not be feasible.
However, partial restoration may be possible, with significant and valuable improvements made to
degraded ecological resources. The needs for improving or re-establishing both the structural
components and the functions of the natural area should be examined. The goal is to partially or
fully reestablish the attributes of a naturalistic, functioning, and self-regulating system.
d. Ecosystem Restoration. The purpose of Civil Works ecosystem restoration activities is to
restore significant ecosystem function, structure, and dynamic processes that have been degraded4.
Protection may be included as part of Civil Works ecosystem restoration initiatives, when such
measures involve efforts to prevent future degradation of elements of an ecosystem's structure and
4
The concepts of ecosystem function and structure are closely intertwined, and both include
abiotic and biotic elements and processes. Ecosystem structure is the state and spacial distribution of
material forms within the ecosystem at a specified time. It includes both microscopic and macroscopic
material components in diverse living and non-living assemblages. Ecosystem functions are dynamic
processes that can be characterized by rate and direction of change in material and energy flows through
time and space. Ecosystem functions redistribute components of structure through abiotic (non-living) and
biotic (living) processes.
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