The ecology of biological invasions: past, present and future - Invasive Plants: Ecological and Agricultural Aspects - page 3

purely practical and sentimental utility to a realization of the environmental
concerns and scientific interests associated with some NIS [5-8].
Concern over the potential impacts of certain NIS began in the late 18th
century. John Bartram, an 18th century botanist, noticed that some introduced
plants negatively affected the environment and some were extremely difficult
to control [7]. In 1793, the devastating yellow fever outbreak in Philadelphia
was blamed on shipments from the West Indies [9], further increasing public
awareness of the potential harmful impacts of NIS.
By the mid-to-late 19th century, a number of NIS-focused writings appeared
in the literature. Hooker [10] revealed that European plants were rapidly replac-
ing natives in New Zealand. During this period a uniquely American pragmat-
ic approach recognized the economic and agricultural threats from NIS
[11-13]. In 1897, Leland Howard, in his address to the American Association
for the Advancement of Science, said: “Potentially cosmopolitan forms … have
by [human] agency become dispersed over nearly all of the civilized parts of the
globe, while thousands of other species have been carried thousands of miles
from their native homes, and have established themselves and flourished, often
with a new vigor, in a new soil and with a novel environment” [14, p. 4].
Howard and his friend and colleague, Stephen Forbes, published many articles
on nonindigenous insects and their agricultural impacts [8].
The environmental concern that developed from the late 18th to late 19th
centuries was bound to ignite the interests of pure scientists and natural histo-
rians alike. The vigilant Charles Darwin did not let NIS pass his gaze unno-
ticed. In many instances in the Origin of the Species [15], Darwin uses NIS to
uncover or support aspects of his theory of natural selection [8]. For example,
to highlight the fact that natural selection does not produce absolutely fit spe-
cies, only species fit relative to those with which it has a history of struggle,
he noted the “introduced plants… have become common throughout whole
islands in a period of less than ten years” [15, p. 118]. He goes on to say that
“The endemic productions of New Zealand, are perfect one compared with
another; but they are now rapidly yielding before the advancing legions of
plants and animals introduced from Europe” [15, p. 229].
Similarly, many of the most influential early ecology and biogeography
texts [16-19] use NIS as examples of their theories, or at a minimum recog-
nized that they needed to be generally explained by their theories, as NIS are
real-world observations [8]. Yet these texts did not develop hypotheses or the-
ories to explain how and why NIS can sometimes invade intact communities.
Therefore invasion ecology, as an independent school of thought had yet to
appear.
It was not until the period from 1936-1958 that a distinct 'proto-invasion
ecology' began to emerge, where authors explicitly tried to understand strate-
gies of successful NIS. H.H. Allen [20] gave academic attention to the prob-
lem of NIS in New Zealand. Whereas earlier authors like Hooker [10] and
Tansley [21] thought that invaders as a group change a plant community with
uniform success, Allen [20] showed that the NIS were not a horde of compet-