Environmental Engineering Reference
In-Depth Information
5.1
INTRODUCTION
ecology are merging. Such a process may bring scien-
tists from backgrounds as diverse as ecology, soil
science, geography, economy, history, the social sci-
ences and more, in contact with non-academic profes-
sionals and practitioners who have an entirely different
way of thinking. Without clear language, such encoun-
ters will produce a tower of Babel, and nothing more.
In this section, we will introduce and defi ne some of
the basic concepts and terms of landscape ecology,
especially those that are most relevant for restoration.
Not so long ago, ecological restoration was considered
to be mainly a site-level activity where certain meas-
ures were taken to reverse an unwanted situation or
unwanted developments. However, it is becoming
increasingly clear that ecosystems do not function
independently from their surroundings and that spatial
relations matter a great deal (Hobbs & Harris 2001;
Thompson 2011). In other words, restoration ecology
and landscape ecology are growing closer together (see
also Chapter 4). One example is the use of the theory
of island biogeography (MacArthur & Wilson 1967 ) in
reserve design and restoration planning. Another
example is the use of ecohydrological knowledge (Succow
1982 ; Grootjans et al . 1996 ; Chapter 16 ), to assess
wetland functioning in relation to landscape water
fl ow paths. Hydrological manipulation in one particu-
lar area may cause disturbance in another, sometimes
distant, area and can affect restoration perspectives
signifi cantly (van Diggelen et al . 1994 ). The same is
true for the impacts and treatment of airborne pollu-
tion (Bobbink et al . 2010). Insights in spatial relations
are therefore essential when evaluating the restoration
perspectives of degraded sites.
The present chapter explores the links between land-
scape ecology and restoration perspectives, with a
focus on fl ows between landscape elements, landscape
alteration and landscape - scale restoration . It starts by
defi ning a landscape and describing the relationships
between scale, pattern and connectivity. These all have
a large effect on the 'percolation' of abiotic agents and
all kinds of biota through a landscape, and changes in
one or more of these features affect both community
composition and ecosystem functioning. Human activ-
ities have signifi cantly altered landscape constellation,
resulting in increasingly fragmented and impoverished
landscapes. Restoration at the landscape scale is, there-
fore, essential to stop further degradation and instead
improve conditions.
5.2.1
Landscape
The scientifi c concept of landscape has its roots in
central Europe and was mainly developed by German
scientists (Troll 1939 ; Schmitth ΓΌ sen 1963 ). At that
time the concept seemed clear and was exclusively
viewed from a human perspective. A typical 'Land-
schaft' was many square kilometres in size and included
several villages, farms and so on. For those researchers
there was no doubt that cultural elements should be
included in the concept. Later work, especially in less
densely populated areas, did not automatically assume
that a landscape should be viewed at the human level
and much less emphasis was put on the various cul-
tural aspects. As a consequence the concept became
increasingly vague and two subsequent analyses of
papers in the journal Landscape Ecology, by Wiens
(1992) and Golley (1995), showed no clear trend in
parameters such as scale of research, level of organiza-
tion or subjects of study. The only elements the papers
had in common were that they were all concerned with
spatial relations and they were all published in Land-
scape Ecology ! In the present chapter, in view of much
confusion about the term 'landscape' (see also Chapter
2), we do not adopt any exisiting defi nition, but rather
defi ne a landscape very simply as 'a spatial matrix in
which interactions of biotic and nonbiotic elements
take place'. Intentionally, we not include any scale in
this defi nition, and the result may seem to refer to
' habitat ' , rather than ' landscape ' . Indeed, there is often
confusion between the two terms. While geographers
and spatial planners are concerned with spatial matri-
ces and spatial relationships and talk about a 'land-
scape' that typically has the size of a few square
kilometers, biologists and nature conservationists tend
to focus on organisms and their use of a given piece of
the earth. To identify that piece of the earth, they will
5.2 CONCEPTS: THE LANDSCAPE AS
A SPATIAL MATRIX
As noted earlier in this topic, clear defi nitions of basic
terms are of utmost importance to facilitate communi-
cation and consensus-building, especially when inter-
disciplinary fi elds like landscape ecology and restoration
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