Kc. Tucker et Dm. Richardson, AN EXPERT-SYSTEM FOR SCREENING POTENTIALLY INVASIVE ALIEN PLANTS IN SOUTH-AFRICAN FYNBOS, Journal of environmental management, 44(4), 1995, pp. 309-338
The development and application of an expert system is described for s
creening alien woody plants for their invasive potential in South Afri
can fynbos. The system is proposed for use by potential introducers to
demonstrate low invasive risk before importing woody alien species fo
r cultivation. Rules for the system were derived from empirical eviden
ce by quantifying invasion windows and barriers that have limited the
set of widespread woody invaders (trees and shrubs) in fynbos to fewer
than 20, out of several hundred introduced species. The system first
compares broad-scale environmental conditions (climate and soil) betwe
en the home environment of a species and fynbos. Features of the plant
in its home environment (basic life history traits, population charac
teristics, regeneration biology, habitat preferences) are then assesse
d. Finally, an assessment is made of life history adaptations to the p
revailing fire regime in fynbos (juvenile period, fire-survival capaci
ty of adult plants, seed bank longevity). The reasoning is explicit an
d the steps leading to a conclusion (high risk/low risk) can be retrac
ed. Besides the obvious application in identifying species with a high
risk of invading, the system has considerable potential for modelling
, and for teaching the concepts of biological invasions. The rules pro
vide an explicit conceptualization of invasion processes in fynbos and
identify multiple paths to invasive success (not all of which have be
en realized yet). The system can therefore be used in planning control
operations (for optimal allocation of control effort to critical stag
es in invasion), and for predicting the outcome of changes (e.g. in fi
re frequency) on the dimensions of invasion windows, and for assessing
what changes are needed to prevent or reduce the extent of invasion b
y a given taxon. Application of the system is demonstrated on Pinus an
d Banksia taxa and a selection of species from Californian chaparral.
(C) 1995 Academic Press Limited