Introduction to Ecological Risk Assessment - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 576

reason to include ecological soil quality in procedures and regulations for contami-
nated site management is the assumption that, unlike human beings, the ecosystem
cannot, or can only to a limited extent, protect itself. Humans have a voice, can eval-
uate the risk they are experiencing, and can contribute to solutions or even escape the
problems associated with contaminated sites. Most soil organisms only have indirect
possibilities, such as adaptation and avoidance, in order to escape the consequences
of soil and groundwater contamination.
13.1.2 Terminology, Ranking and Classification
Soil organisms are part of soil ecosystems . Ecosystems may be defined as sys-
tems where chemical substances and energy are exchanged between organisms, and
between organisms and their abiotic environment. In this definition the soil ecosys-
tem includes the soil and groundwater itself. The biocoenose (or biocenose, biotic
community, or ecological community) comprises the interactions between organ-
isms in a specific habitat. The range of variation in the physical and chemical factors
in soil is dependent on climate, soil type and land use. As a consequence, every sin-
gle ecosystem is unique. Therefore, an infinite number of different ecosystems exist
worldwide.
The unicity of soil ecosystems also means that different requirements apply
for optimal functioning of different soil ecosystems. And since the physical and
chemical factors are changing over time (for example: temperature, rain), the soil
organisms must be able to perform and to survive under changing conditions.
Moreover, species will adapt to changing conditions over time and, hence, the
ecosystem will be changing continuously.
In the framework of this topic, the protection target 'soil ecosystem' is
approached from the perspective of the living organisms in soil, or in other words,
the soil biology . According to this viewpoint, soil organisms have the highest rank-
ing within the hierarchy of an ecosystem. Abiotic factors in soil are approached as
elements that impact these organisms.
Organisms can be classified (taxonomically ranked) in different entities, for
which the lowest rank is species (see Fig. 13.1 ). In total, eight higher taxonomic
ranks are distinguished in biological classification, as presented in Fig. 13.1 .
Several classifications exist for ecological functions (Ecosystem Services).
Wallace ( 2007 ), however, claims that systems employed mix processes (means) for
achieving services and the services themselves (ends) within the same classification
category.
The condition of the soil ecosystem is often described as Ecological Health (aka:
Ecosystem Health, Soil Health ,or soil vitality )or Ecological Integrity . Ecological
Integrity refers to the unimpaired condition in which ecosystems show no influence
from human activities. Ecological Health relates to the preferred state of the soil
ecosystem, allowing human activities to influence the state of the ecosystem.
There has been a lot of debate about the good and bad points of the phrase
'Ecological Health', especially with regard to the position of the soil ecosystem