Dispersal, migration and management - Ecological Applications: Toward a Sustainable World - page 82

understand that marine reserves need to be big enough for replenishment by local dispersal of
propagules and/or close enough to neighboring reserves for propagule dispersal among them
realize that the necessary steps to vegetation restoration vary according to the dispersal powers
of key species and whether a seed-bank is still present in the soil
note that countless invasive plants, animals and microorganisms travel the world's trade and tourist
routes on people and their goods
appreciate why sustainable power generation, forestry and agriculture may depend on our under-
standing of animal dispersal and migration

4.1 Introduction -
why species mobility
matters

Maria is a businesswoman who wants to turn wind power into electricity. She's
angry. ' You'd think with all the concern about global climate change that the public would
be keen to see wind farms developed . Wind power promises a much cleaner and, just as
important, more sustainable supply of electricity than the fossil-fuel power stations that
spew out carbon dioxide. ' Indeed, this is why some international wildlife organiza-
tions are in favor of wind power development. But there are plenty of people who
fi nd something to object to. Maria comes from the Netherlands, famous for its his-
toric landscape of windmills, and fi nds the notion of wind farms rather romantic,
but others think a horizon dominated by wind turbines will be ugly. And she points
out: ' People living in the area we want to develop are suffering from a bad case of NIMBY
syndrome (Not in My Back Yard!). ' Then again, local conservationists are worried
about migration routes and endangered birds getting chewed up by the turbines.
Maria's not a happy woman.
A useful distinction can be made between dispersal (the spreading of individuals
away from each other) and migration (a mass directional movement - Box 4.1). Local
bird populations, with their daily dispersal movements, as well as wider-ranging
species that follow set migration routes may both be at some risk from wind farms.
But movement is not just critical to birds. Even an oak tree ( Quercus robur ) is where
it is because an acorn was moved to that location before it germinated. On a very
different scale, an arctic tern ( Sterna paradisaea ) migrates from its breeding site in
the Arctic to the Antarctic and back again each year. Movement, then, ranges from
passive to active, short to long range, and from random to purposeful. Maria will
have to wait until Section 4.5 to read about the signifi cance of understanding move-
ments of animals and plants for the management of power generation (as well as
other production industries - forestry, agriculture). First, I will deal with the appli-
cation of knowledge about dispersion and migration to problems of conservation
(Section 4.2), restoration (Section 4.3) and invasion control (Section 4.4).
I have already discussed species traits in Chapter 3. The timing, location and
distance involved in dispersal and migration vary from species to species and are
themselves species traits. Individuals of some migratory species are more likely to
go extinct because of a complex need for different types of habitat at different times
in their life cycle. Similarly, some specie s are more likely to arrive under their own
steam in restoration projects, or as unwanted invaders, because of the details of their
dispersal or migration traits. This suite of traits deserves the prominence of a chapter
of its own because of the particular signifi cance of species mobility in applied
ecology.