B12 Accelerated establishment and spread of 
invasive alien species within countries are 
primarily driven by direct drivers, notably changes 
in land- and sea-use (Figure SPM.5) (well 
established) {2.2.1, 3.3.1, 3.6.2}. Land- and sea-use 
changes may increase the vulnerability of natural 
ecosystems to the establishment and spread of invasive 
alien species through increasing fragmentation and habitat 
disturbance, for example by changing grazing, fire regimes, 
soil disturbance, or watershed flow (well established)
{3.3.1.2, 3.3.1.5}. Transportation and utility infrastructures 
such as roads, tracks, railways, pipelines, canals and 
bridges, among others, can create corridors that facilitate 
the spread of invasive alien species, including into remote, 
undisturbed and protected areas (well established) {3.3.1.3, 
Box 2.7, Box 3.7}. Marine and aquatic infrastructure may 
alter seascapes and the functioning of marine ecosystems, 
facilitating the spread of invasive alien species (established 
but incomplete) {3.2.2.4, 3.3.1.4, 5.6.1.4}. The numbers of 
invasive alien species were reported to be 1.5 to 2.5 times 
higher on pontoons and pilings than on natural rocky reefs 
(established but incomplete) {3.3.1.4}. More generally, 
land-use change can facilitate biological invasions through 
alteration of processes that cause natural disturbance of 
landscapes, such as wildfire or grazing regimes (established 
but incomplete) {3.3.1.5}. In several regions of the world, 
grazing by feral alien ungulates (horses, camels, buffalo, 
pigs) facilitates the spread of invasive alien plants, 
sometimes through complex species interactions involving 
the suppression of native species and the facilitation of other 
alien species (well established) {3.3.1.5.1}. As a specific 
example, invasive alien ungulates (wild boar, deer) can 
transport invasive ectomycorrhizal (root associated 
symbiotic) fungi, which are beneficial for the establishment 
and spread of alien pine trees, over long distances, 
rendering habitats susceptible to pine invasion (well 
established) {Box 3.10}. Climate change, along with the 
continued intensification and expansion of land-use change 
may lead to future increases in the establishment and 
spread of invasive alien species in disturbed habitats and in 
nearby natural habitats (established but incomplete) {3.3.4}.
 <Section-header> B12  </Section-header> 

SUMMARY FOR POLICYMAKERS
19SUMMARY FOR POLICYMAKERS
BACKGROUND
A GLOBAL DISTRIBUTION OF ESTABLISHED ALIEN SPECIES 