Community Ecology Processes, Models, and Applications

regional dynamic processes in metacommunity the-
ory is then used to suggest guidelines for manage-
ment of biodiversity and ecosystem services in
human-dominated landscapes. As the literature on
these subjects is increasing rapidly, I do not attempt
to cover the recent literature. Instead, I use some
examples to illustrate how applied and basic ques-
tions in ecology can gain from being studied in
tandem in the same managed system. My examples
mainly derive from studies on biodiversity and
ecosystem services in terrestrial agricultural land-
scapes. I use the termsecosystem functioningand
ecosystem processesto refer to any process carried
out in ecosystems by organisms maximizing fitness,
for example biomass production or decomposition,
whileecosystem servicesare the subset of ecosystem
processes that benefit humans (or society).Diversity
is used synonymously with species richness, unless
stated otherwise.
Basic in biodiversity and ecosystem functioning
research is the role of diversity. It is important to
remember that diversity in itself does not carry out
any process. Ecosystem processes are carried out by
species (populations and individuals); diversity is

an indicator of species being present to do the work

in ecosystems (Bengtsson 1998). Management of

ecosystem services in heterogeneous landscapes ul-

timately relies on understanding communities of

interacting populations.

9.2 A theoretical background

9.2.1 A simplified historical narrative

Island biogeography and metapopulation theory

emerged during the 1960s almost simultaneously

and actually within the same intellectual environ-

ment (Worster 1994). Many ecologists seemed to

regard them as essentially the same, but from sev-

eral aspects and especially for conservation these

theories offer different views of the world. A major

conceptual difference is that island biogeography

(MacArthur and Wilson 1967) saw the world as

mainlands sending off migrants to islands, an ex-

treme source–sink situation with respect to coloni-

zation–extinction dynamics (but see Schoener

1976). On the other hand, in metapopulation theory

(Levins 1969) patches are colonized from other

Island biogeography

Diversity

For single species

For single species

Important

characteristics

View of the

world

Basic equation

solutions

Equilibrium proportion occupied

islands

P* = m/(e+m)

P* = 1 – e/m

For competitors: e = e 0 + eij

S* = IM/(E+I)

Importance for

management

Historically large but

in practice useless

because islands depend

completely on the mainland

Large

Diversity and species

persistence dependent

on isolation and regional

commonness

Single – few species

Internal pool of colonizers

Patches equal (can be relaxed)

Stochastic extinctions

Diversity

External mainland species pool

Islands sinks

Stochastic extinctions

Metapopulation dynamics

Figure 9.1Contrasting views on the world in the basic theories of island biogeography and metapopulation dynamics.
S, species number; M, mainland pool species number; E and I, number of extinct and immigrating species per unit time
(in island biogeography model); e and m, extinction and migration rates (in metapopulation model); P*, equilibrium
proportion of occupied islands/patches. See plate 3.

116 APPLICATIONS