Monographs of invasive plants in Europe:Carpobrotus

Abstract

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. Taxonomy Names and classificationScientific name: Carpobrotus edulis (L.) N. E.Br., 1926 Basyonym: Mesembryanthemum edule L., 1759

Ecophysiological differentiation between two invasive species ofCarpobrotuscompeting under different nutrient conditions

“…aff. acianciformis : Suehs et al., , b; Verlaque et al., ) (for details on taxonomic ambiguity, see Campoy et al., ). Wisura and Glen () also recognized the shape of the leaves (straight or very slightly curved in C. edulis , and scimitar‐shaped in C. acinaciformis ) as a discriminating character in the native range of the species.…”

“…acinaciformis morphotypes (hereafter, “taxa”). In fact, in Europe, due to hybridization processes, pure populations of C. acinaciformis cannot be found (Campoy et al., ). To represent the genetic diversity of both taxa, we randomly collected 40 genets per taxa at these four sites in northwestern Spain, yielding 80 genotypes.…”

“…The invasive South African species Carpobrotus edulis (L.) N.E.Br. and Carpobrotus acinaciformis (L.) L.Bolus (Aizoaceae) are trailing, mat‐forming succulent perennial herbs (Wisura and Glen, ) that inhabit coastal habitats in temperate regions around the world (Campoy et al., ). Their success in invading new areas has been attributed to several factors: their capacity to alter the invaded soils (Vieites‐Blanco and González‐Prieto, , b); their “grow‐and‐die” strategy, which transforms a hostile environment into a more favorable habitat for their offspring (Fenollosa et al., ) and a greater competitive ability than native species (D'Antonio and Mahall, ).…”

“…The taxonomic identity of the invasive Carpobrotus species in Europe and the Mediterranean has long been a subject of debate, and misidentification and ambiguous nomenclature raise doubts about the taxonomy of these invasives (see Campoy et al., for a review). On the basis of foliar and reproductive characters, Suehs et al.…”

“…aff. acinaciformis , coexist in many coastal dune systems (Campoy et al., ). These systems are typically characterized by a scarcity of soil nutrients (Kachi and Hirose, ).…”