The ecology of biological invasions: past, present and future - Invasive Plants: Ecological and Agricultural Aspects - page 4

itive invaders. In fact relatively few NIS (48 of 603 species) became problem
species in New Zealand, and these few problem species represented a diverse
array of ecologies. Like Allen, Egler [22] thought NIS invaders were not a uni-
form group changing the ecology of Hawaii. Rather he saw NIS as a diverse
group, which made predicting the future of community types nearly impossi-
ble. They both thought that after grazing and disturbances were removed,
native communities would be much better suited to competing against NIS.
Stewart and Hall [23] clarified the biology of the invasive grass Bromus tec-
torum and how it was affecting the native communities of southern Idaho, USA.
Baker [24] used the invasions of Melandrium album and M. dioicum in Great
Britain to study the dynamics of invasion, range expansion and large-scale com-
petition. Finally, the control of problematic NIS was gaining momentum
because of famous early instances of successful biological control. These exam-
ples would include not only the control of Opuntia cacti by Cactoblastis cacto-
rum in Australia by 1926 [25] but also the control of Hypericum perforatum by
Chrysomela beetles in western United States [26, 27].
By the 1950s, researchers were explicitly studying NIS to understand the
invasion process. Theoreticians around this time were also using their tools to
understand invasion dynamics better. Skellam [28] used spatial spread models
describing the diffusion of particles to examine the spread of a reproducing
population over a two-dimensional landscape. He illustrated this idea using the
1905 introduction and spread of muskrat, Ondatra zibethica , in central Europe
[28]. D'Ancona [29] showed how Lotka-Volterra equations could be used to
understand the dynamics of species invasions.
The science of invasion ecology “as much as one can ever pinpoint the
beginning of a field to a single event” was “the publication of Charles Elton's
topic” [30, p. 806]. Elton [31] fit together disparate ideas and facts and came
up with explanatory theories and predictions about how invaders spread and
communities are invaded. The single most influential prediction from his
topic, and one that is still actively researched, was that more diverse commu-
nities ought to resist invaders better (see Biotic resistance hypothesis , below).
In the decades since Elton [31], several important published works have
expanded our understanding of invaders and the invasion process [5]. In 1965,
The genetics of colonizing species [32] compiled writings from many of the
world's leading ecologists and evolutionary biologists. This volume explicitly
examined what happens to individual species during and after the invasion
process. The most notable ideas from this volume include the notion that traits
of invaders can be used to predict impact and the realization that genetics and
evolution of invaders could help explain aspects of invasion ecology.
The 1970s and 1980s saw the rise of conservation concern in academic
research [5], and out of this concern grew organizations like SCOPE
(Scientific Committee on Problems of the Environment). Two important vol-
umes on invasion ecology were published by SCOPE during the 1980s:
Ecology of biological invasions of North America and Hawaii [33] and
Biological invasions: a global perspective [34]. The authors contributing to