Characteristics, significance, and human dimension of global invasive weeds - Invasive Plants: Ecological and Agricultural Aspects - page 238

Can we predict the invasiveness of a plant species? Many have attempted to
characterize a successful invader [33-35]. But no one seems to agree on the
general characteristics common to invasive species, and some believe that
these traits as described earlier have little value in prediction of invasiveness.
In general, plants with aggressive potential vegetative reproduction potential
may be invasive in a new environment. However, Pyˇek [36] found that clon-
al plants account for only 36% of the non-native plant species established in
central Europe. This suggests that clonal growth is not the only factor associ-
ated with invasiveness.
Different traits favor invasiveness in different habitats [37]. Factors that ren-
der habitats invasible include low intensities of competition, altered distur-
bance regimes and low levels of environmental stress. These factors probably
often interact. Invasive potential can be classified as “highly invasive”, moder-
ately invasive” and “potentially invasive”. Using multiple logistic regressions,
Scott and Panetta [38] found that for agricultural weeds introduced from
southern Africa to Australia the highest level of variation was explained by
weed status in native region. They predicted the future status of a number of
recently arrived or not yet introduced species. In general, it was agreed that
species known to be invasive elsewhere in the world under similar climatic
conditions were perhaps the indicators of future invasive potential.
According to Parker [39], the invasiveness of a plant species could be pre-
dicted as follows: Invasive potential A (rhizomatous, climbing, small and read-
ily dispersed seed), Damage potential B (competitive, toxic, allelopathic),
Geography potential C (the magnitude of range of geography or ecologies to
be invaded), and Entry potential D (mode of entry either deliberate or acci-
dental). These parameters are then considered as the product of A*B*C*D, to
estimate a plant invasive potential. In this approach, inclusion of C and D com-
bined with major predictive characteristics of weeds imparts an improved
means for predicting the invasiveness of alien species. As we understand more
and more on the biology of many of the invasive weed species, we would be
able to make progress in developing a good predictive model on invasiveness
of species.
References
1 Mooney HA, Hobbs RJ (2000) (ed.): Invasive species in a changing world. Island Press,
Washington DC
2 Yaduraju NT, Bhowmik PC, Kushwaha S (2000) The potential threat of alien weeds to agriculture
and environment. In: PK Jha, SB Karmacharya, SR Baral, P Locoul (eds): Environment and agri-
culture: at the crossroad of the new millennium , 2000 Ecological Society (ECOS), Kathmandu,
Nepal, 229-234
3 Pimentel D, Lach L, Zuniga R, Morrison D (2000) Environmental and economic costs of non-
indigenous species in the United States. BioScience 50: 53-65
4 Westbrooks R (1998) Invasive plants, changing the landscape of America: Fact book . Federal
Interagency Committee for the Management of Noxious and Exotic weeds (FICMNEW),
Washington DC, 109