Present and future threats by invasive alien plants in Georgia
The spread and occurrence of invasive alien plant species in Georgia has increased significantly over the decades due mainly to changes in land use and habitat destruction. Recent estimates highlight 380 alien plant species in the country of which 134 are established and 16 of these are having detrimental impacts on native biodiversity. From these 16 species, Thalmann et al. (2015) selected the 9 most abundant species - or those species with a high potential to cause impacts - and conducted species distribution modeling to predict their future occurrence in Georgia and specifically within 43 protected areas in Georgia (Table 1). Using occurrence data for each species from the native and introduced ranges, coupled with bioclimatic data, the models were run to evaluate habitat suitability for each species. The results showed that Ambrosia artemisiifolia (EPPO List of IAP), Robinia pseudoacacia and Ailanthus altissima (EPPO List of IAP) had the highest potential area of distribution in Georgia. A. altissima was shown to have the highest potential for range expansion over the next 50 years. As a result of this study, the authors have identified two regions in Georgia that are specifically vulnerable to invasive alien plants. Tiblisi in the east of Georgia and Adjara in the west of the country are regions which have ecological conditions that are favorable to many of the invasive plant species present in the country.
Table 1. Invasive plant species used in the distribution modeling
|
Species
|
Origin
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Established in the EPPO region*
|
|
Ailanthus altissima (EPPO List of IAP)
|
Asia
|
CH, FR, GB
|
|
Ambrosia artemisiifolia (EPPO List of IAP)
|
N-America
|
Widespread
|
|
Clerodendrum bungei
|
Asia
|
GE
|
|
Miscanthus sinensis (EPPO Alert List)
|
Asia
|
Widespread
|
|
Opuntia humifusa
|
N-America
|
BG, HR, FR, GI, GR, IT, PT, ES, CH
|
|
Opuntia phaeacantha
|
N-America
|
CZ, ES
|
|
Robinia pseudoacacia
|
N-America
|
Widespread
|
|
Spiraea japonica
|
Asia
|
AT, DK, GE, NO, SE
|
|
Vitex rotundifolia
|
Asia
|
GE
|
* The distribution of species has been checked in the Q-bank database, as well as the DAISIE, NOBANIS and PQR databases. When the species was recorded in several countries, its distribution was approximated to ‘widespread’.
Sources
Thalmann DJK, Kikodze D, Khutsishvili M, Kharazishvili D, Guisan A, Broennimann O, Müller-Schärer (2015) Areas of high conservation value in Georgia: present and future threats by invasive alien plants. Biological Invasions 17, 1041-1054.