patches in the region, not from a mainland (Fig.
9.1). Island biogeography was important in early
conservation biology, despite the conceptual prob-
lem that islands (patches) require a mainland to
sustain their diversity, which makes it practically
useless to apply in reserve design. Metapopulation
models in which the number of colonizers depends
on how many patches are inhabited in the region,
and how isolated those patches are, provide a more
relevant model of the world, especially for conser-
vation of species in fragmented landscapes. The
general acceptance of the metapopulation concept
for single species was crucial for the later develop-
ment of metacommunity theory.
Although both island biogeography and meta-
population theory could be formulated to incorpo-
rate species interactions – in both cases by allowing
interspecific competition to increase extinction rates
(e.g. Hanski and Ranta 1983) – their basic formula-
tions and later interpretations, especially in conser-
vation biology, modelled the world as essentially
consisting of single species with independent dy-
namics. This limited the usefulness of metapopula-
tion theory for interacting communities. Only after
other areas of ecology, such as food webs (Poliset al.
1997), had provided a spatial perspective on species
interactions and community structure, the time be-
came ripe for an emerging metacommunity theory
that linked landscape ecology, food webs, metapo-
pulation dynamics and ecosystem functioning.
In the 1960s, niche theory for local communities
was also developed by MacArthur and Levins (see
Chapter 5). For example, the theory of limiting sim-
ilarity was used to explain the limits to local diver-
sity (see Chase and Leibold 2002). Classical niche
theory, despite its falling popularity, forms an im-
portant background for community ecology, and is
important for the discussion of why diversity might
affect ecosystem functioning. The complementarity
hypothesis (Loreauet al. 2001), which predicts in-
creases in various aspects of ecosystem functioning
as diversity increases, is based on niche differences
in resource utilization between species. However,
not until the last decade had niche theory devel-
oped to be integrated into a metacommunity frame-
work. Important ideas in this process were as
follows: (1) The recognition that a species’ environ-
mentalrequirements(resources and environmental
conditions allowing survival) and a species’impact
on the environment (withdrawing resources but
also incorporating ecological engineering and
other aspects of niche construction; Odling-Smee
et al. 2003) arebothmajor components of the niche
(Chase and Leibold 2002). (2) The idea that, when
environments vary over time or in space, stability of
ecosystem functioning is ensured by species with
similar effects on ecosystems while at the same time
showing a diversity of responses to environmental
variation (response diversity, Elmqvistet al. 2003;
insurance hypothesis, Loreauet al. 2003). (3) The
neutral community theory (Bell 2001; Hubbell
2001) was important by emphasizing the role of
dispersal limitation for community composition,
despite dismissing niches as being important for
species coexistence (building on earlier notions in
especially plant ecology).
Niche theory, as well as ecology in general, re-
garded the local habitat to be of prime importance.
This was especially so when dealing with conserva-
tion of single species or diversity. Local habitat
patches were the objects to be managed because
they were threatened by human activities. Habitats
of high value for conservation were set aside as
reserves or land-owners given payments to manage
them in an economically less rational way, often by
traditional practices. Metapopulation and land-
scape ecology theory allowed researchers and man-
agers to see effects of landscape and patch
configuration on species, but the incorporation of
this insight into management was slow. However,
the rise of the corridor concept – despite the con-
troversies surrounding it – opened up for a recog-
nition of the importance of landscape context, in
this case connectivity, for managing diversity in
individual patches.
In addition, insect ecologists had long recognized
the importance of larger-scale processes and dis-
persal in population dynamics. In fact, already in
the 1950s, metapopulation ideas were developed by
Andrewartha and Birch (1954). Migration between
crop fields and other habitats, both among pests
and among natural predators, was identified early
as important for conservation biological control
(Barbosa 1998).
From these sources emerged the modern view of
local habitat patches interacting via dispersal in aDIVERSITY AND ECOSYSTEM SERVICES 117