Agriculture Reference
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archaeophytes reached the area of the present Czech Republic by nearly thou-
sand years earlier than that of Great Britain (Fig. 3). This primarily reflects that
the onset of Neolithic agriculture in Great Britain (c. 6,000 yrs B.P. [37]) was
postponed compared to Central Europe (c. 7,300 yrs B.P. [29]). One might
expect the different geographical distances of these regions from the
Mediterranean, the area where archaeophytes originated, to play a role. Britain
is located further to the northwest, i.e., more distant, but the results do not sug-
gest that there was a delay in invasion by archaeophytes in this region due to
the time needed for reaching it. They rather indicate that as Neolithic people
brought about not only crops but also weeds [43], the invasion by archaeo-
phytes in both regions started immediately with the beginning of agriculture.
Discussion
The data analyzed above provide firm evidence that residence time is an
important factor that should be considered in studies on plant invasions. Our
study confirms the conclusions of previous papers; so far, the effect of resi-
dence time was highlighted in the literature namely by papers of Rejmánek
and his collaborators [23-27]. More evidence is available from New Zealand,
where the most widespread invaders are those which were introduced early
[24], and Tasmania [23]. Rejmánek et al. [23] concluded that the suggestions
made recently by some ecologists, that there is some constant proportion of
invasive taxa recruiting from the pool of introduced taxa [40, 56, 57] is unlike-
ly to hold. Rejmánek et al. [23] suggest that the reasonably constant propor-
tion of alien taxa that invade across a wide range of systems is, at least partly,
a result of the similar mean residence times of species in alien floras.
It should be noted that the dates of first species records are not in fact the
exact dates of invasion, i.e., time at which the species first occurred in the wild
after it has been unintentionally introduced or escaped from cultivation. That
it is usually not known exactly when this happened is why the term of “mini-
mum” residence time was suggested [24-26]. Nevertheless, this approach is
justified: It can be reasonably expected that the more common a species is the
more often it is recorded by floristic surveys, hence that common species were
first recorded earlier than less common species. For multi-species analyses, the
comparability increases if the information on all species in the set is derived
from the same primary sources [30, 46]. In general, potential for generaliza-
tion based on floristic records increases if biases associated with such data are
taken into account. In some papers attempts have been made to control for the
increasing intensity of floristic research over analyzed periods by involving the
information on the dynamics of native species under the same scenario [41, 47]
or on the increasing quantity of herbarium collections [57].
The present overview extends the view that residence time is important. We
showed that in modern invasions on the time scale of centuries, the longer the
alien species are present in the territory the higher their chance 1) to pass suc-
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