The classical paradigm in ecology, with its emphasis on the
stable state, its suggestion of natural systems as closed and
self-regulating, and its resonance with the nonscientific
idea of the balance of nature, can no longer serve as an
adequate foundation for conservation.
(Pickettet al. 1992, p. 84)The fragmented world of biological communities in the
future will be so different from that of the past, that we
must reformulate preservation strategies to forms that go
beyond thinking only of preserving microcosms of the
original community types.
(Kellman 1996, p. 115)10.1 Islands and conservation
Our species has had a profound influence on the
ecology and biodiversity of the planet, altering the
composition and functioning of ecosystems across
the globe. Our actions in some respects represent
merely the latest driver of change, concentrated
largely within one interglacial of a period, the
Quaternary (the past c.2 Ma), which has seen
repeated dramatic fluctuations in climate. During
this time, individual species have experienced
alternating episodes of expansion and of contrac-
tion and fragmentation of ranges and have conse-
quently been re-sorted into combinations that have
often differed radically from those found today
(e.g. Bush 1994). There is nothing new about range
alterations. Now, however, it is humans who are
driving range shifts and extinctions. We have done
this for a long period of our history, and we are
doing so in an accelerating fashion and on a global
scale (Saunders et al. 1991; Bush 1996). Whether we
see particular changes in ecosystem properties as
beneficial or detrimental can depend as much on
our cultural perspective as on the nature of the
changes themselves. However, there is no doubting
the profound importance of the human agent in
biogeographical terms: not only in extinguishing
species but, as significantly, by bombarding areas
with sets of species gathered up from far-distant
regions of the globe, breaking bounds of isolation
that have lasted for many millions of years, and in
the case of oceanic islands for their entire existence.
The accelerated extinction of species on a plane-
tary scale is something that concerns all societies
and it should therefore be a high priority for natu-
ral scientists to study the processes involved, to
document the changes involved accurately, to
develop predictive models, and to provide scien-
tific guidance for the conservation of biodiversity.
This field of study is termed conservation biology,
and it is an area of research that has expanded
greatly in the last 20 years: yet, there remain many
uncertainties concerning the big picture. In illustra-
tion, we are currently unable to say to within an
order of magnitude how many species we share the
planet with (Gaston 1991; Groombridge 1992). A
second illustration is that although a large propor-
tion of land plants and animals are believed to be
rain forest species, we cannot be sure how large a
proportion, nor how much tropical forest exists, nor
with much precision, how fast these ecosystems are
being degraded of their biodiversity on a global
scale (Whitmore and Sayer 1992; Grainger 1993).
We know there to be a crisis, but we cannot be sure
of its precise magnitude.
Nature conservation as a social movement is not
motivated solely by a concern to reduce global
species extinction, but is also imbued with other
values and goals. However, a full consideration of251CHAPTER 10