Environmental Engineering Reference
In-Depth Information
longer possible in a relevant or 'reasonable' period of
time. Degradation, resulting from various factors,
including
climate change
and extreme events, as well
as human activities, generally reduces fl ows of
eco-
system goods and services
.
Desertifi cation
Degradation
of land in arid, semi-
arid and dry subhumid zones resulting from the
impact of various
disturbance factors
, including
climate disruptions and human activities. This de-
gradation is expressed in the deterioration of plant
cover, impaired soils and reduced availability of
water. At the scale of a human life, it causes diminu-
tion or destruction of the biological potential of
lands and their capacity to support resident popula-
tions of people and other living organisms.
Designer ecosystem
A n
ecosystem
without ana-
logues that is intentionally created to achieve
mitiga-
tion
, conservation of an
endangered species
or other
management goals (MacMahon & Holl 2001).
Differs from
emerging ecosystems
and
novel ecosys-
tems
, which are not planned but instead arise
spontaneously.
Disturbance
A signifi cant and often irreversible
change in environmental conditions, population
size, community composition and/or the magnitude
and direction of some ecosystem-level process - typi-
cally by reducing numbers of individuals, species or
habitat
. Can be caused by natural or human-induced
disturbance factors
. Some authors use ' perturbation '
but we avoid the term in this topic.
Disturbance factor
Natural or human - mediated
event or activity that changes the structure, content
and/or function of an
ecosystem
. The ecosystem may
either return to the previous steady state (
resistance
or
resilience
) or not (
disturbance
).
Ecohydrology
The science that studies hydrody-
namics, and more specifi cally the study of gains,
retention, losses and recycling of water is called
'
hydrology
' . The term ' ecohydrology ' is commonly
used to indicate the study of the relations between
plant communities and landscape-scale hydrody-
namics, an aspect of
landscape
ecology.
Ecological economics
' The union of economics
and ecology, with the economy conceived as a sub-
system of the Earth ecosystem that is sustained by a
metabolic fl ow or throughput from and back to the
larger system' (Daly & Farley 2010). Not to be con-
fused with
environmental economics
.
Ecological footprint
A concept and calculation
method developed and launched by Wackernagel
and Rees (1996) to analyse and compare human
impact on nature with respect to the biosphere's
ability to regenerate resources and provide services.
The total 'footprint' for a designated entity is meas-
ured in terms of 'global hectares' of biologically pro-
ductive space with an annual productivity equal to
the world average. Can be used to evaluate a corpo-
ration, an installation (e.g. a mine or an airport) or
a human individual or population's impact on eco-
systems of the global environment, but should not
be used too liberally. Often ' environmental impact '
or 'ecological impact' is a better term to use for
scientifi c discussions. However, ecological footprint
is a metaphor that has captured the attention of
the entire world and thus has great value for
communication.
Ecological function -
See
ecosystem function
.
Ecological indicator -
See
indicator.
Ecological rehabilitation -
See
rehabilitation
.
Ecological restoration
' The process of assisting
the recovery of an
ecosystem
that has been degraded,
damaged, or destroyed' (SER 2004). Note that the
term is often used, in a very broad and rather vague
way, to mean returning a site or a system to 'pre-
disturbance conditions ' .
Ecological structure -
See
ecosystem structure.
Ecology
The study of the interactions between
organisms and their environment, which includes
the physical environment (temperature regime,
water availability, etc.) and any infl uences on an
organism exerted by other organisms - the biotic
environment. The science of ecology covers a wide
range of spatial scales, organizational levels and
phenomena, moving from an individual molecule to
the entire global ecosystem.
Ecosystem
The system of relationships and interac-
tions among living organisms (plants, animals and
microorganisms), and the abiotic (nonliving) envi-
ronment, such as soil, water and air, at a specifi ed
location. Ecosystems occur at different spatial scales,
from a small pond, for example, to a whole
landscape
.
In principle, or metaphorically, one can even speak
of the Earth or the biosphere as a single ecosystem.
Ecosystem engineers
Organisms other than
humans - beavers, for example, and elephants and
earthworms - that cause physical and/or chemical
state changes in their environments and affect avail-
ability of resources to other species (Jones
et al
.
1994 ; Lavelle 1997 ). Rosemond and Anderson
(2003) urge greater use of nonhuman 'ecological
