Monographs of invasive plants in Europe: Carpobrotus

This report synthesizes all aspects of the taxonomy, distribution, history of introduction and
spread, ecological constrains (including preferred climate, substratum and habitats),
responses to biotic and abiotic factors, biology (including phenology, vegetative and reproductive
biology), economic importance and human uses, ecological impacts, legislation and
management of Carpobrotus N.E.Br. (Aizoaceae), a prominent invasive plant in Europe.
Carpobrotus species are mat-forming trailing succulent perennial herbs native from South
Africa, introduced in Europe for ornamental and soil stabilization purposes since the beginning
of the seventeenth century, now widely naturalized on coastal habitats of southern and
western Europe. C. acinaciformis and C. edulis are the main species recognized outside South
Africa, together with their hybrids and potential hybrid swarms. Identification conflicts both in
the native and invaded areas raise doubts on the taxonomy of these taxa, but hybridization
processes may boost adaptive changes in the invaded range.
The release of Carpobrotus in natural environments and protected areas is prohibited in
several European countries, but this taxon is not included in the list of invasive species of
Union concern. Carpobrotus is a pioneer of disturbed sites and coastal areas including cliffs
and sand dune systems, due to its tolerance to stress factors such as salinity, drought and
excess of light. Carpobrotus invasion ultimately affects patterns of native species diversity.
Moreover, it has been recognized as a major driver of soil conditions shifts and soil geochemical
processes disruptions, representing a serious threat for coastal habitats.
Management plans for Carpobrotus must consider its high plasticity for morphological and
ecophysiological traits, which may probably explain its tolerance to a wide range of ecological
conditions. Its flexible mating systems, which represent an optimal strategy to facilitate
local adaptation and habitat colonization, include ability to produce apomictic seeds, selfand
cross-pollination, and an intense vegetative clonality. In addition, Carpobrotus produces a
large seed bank with a moderate short-term persistence, and fruits are effectively dispersed
by mammals. The most efficient control methods are physical removal and herbicide application
on leaves, whereas integration of biological control with other conventional management
methods are likely to be most effective. A long-term monitoring of control actions and
restoration of soil conditions are needed to prevent recovering from clonal parts, seed bank
or mammal faeces as well as potential new invasions by other opportunistic species.