CHAPTER 7
Applications of community ecology
approaches in terrestrial
ecosystems: local problems, remote
causes
Wim H. van der Putten
7.1 Introduction
7.1.1 Issues in applied community ecology
There are many examples of the applied value of
community interactions in terrestrial ecosystems.
Enhancing biological control of pests and plagues,
for example, has become a major arena for testing
bottom-up versus top-down control, direct versus
indirect defence of plants, and constitutive versus
induced defence (Karban and Baldwin 1997). This
field of applied community ecology has developed
important new concepts, such as the concept of
multitrophic interactions (Tscharntke and Hawkins
2002). It shows that applied and fundamental re-
search can go hand in hand fruitfully. Another field
is that of biodiversity and ecosystem functioning,
which started from the general concern about con-
sequences of human-induced loss of biodiversity
for the functioning of ecosystems. This led research-
ers to question how biodiversity loss may influence
ecosystem processes, their stability and resilience
(Loreauet al. 2001). These ecosystem processes and
properties have important consequences for the
sustainability of human society. However, when
compared with biological control, the biodiversity
debate is younger and the concepts are now being
deepened. Studies that went into more complex
community interactions were exciting and have
made considerable progress (Cardinaleet al. 2006).
A third well-known applied issue in community
ecology is that of the consequences of increased
habitat fragmentation for the dispersal and survival
of populations and species. Interesting progress in
that field of research has been made, for example
how species from different trophic levels are affect-
ed differently by habitat fragmentation. Habitat
fragmentation could affect trophic control of spe-
cies and, therefore, lead to either outbreaks or ex-
tinctions of species (Tscharntkeet al. 2005).
The above-mentioned examples have received
much attention in the past and there are many
overviews and reviews written on these interfaces
of fundamental and applied community ecology.
Here, I want to focus on a current issue: commu-
nity interactions across system boundaries. My
main point is that applied questions concerning
the management of species, communities or eco-
systems at a given place and time may depend on
processes that take place in adjacent subsystems,
or in remote ecosystems, or that have taken place
in the past. The soil will play an important role in
this chapter, because soil has a strong ‘memory’
and legacy effects can cause historical contingency
(see Chapter 4). Many soil organisms are relatively
poor dispersers, but they are assumed to exhibit
considerable redundancy in ecosystem processes.
Nevertheless, redundancy does not apply to all
functions and the response rate of soil commu-
nities to changes may be slower than that ob-
served above ground.83