Effects of Carpobrotus edulis invasion on main litter and soil characteristics in backdune and rocky coastal habitats with oceanic climate.

Abstract

Background and aims: Carpobrotus edulis invades coastal areas throughout the world, decreasing plant diversity and hampering restoration efforts by changing soil properties. Some of its effects on soils are known but there is a knowledge gap about the effects in rocky areas and micronutrients that we aimed to fill for dunes and rocky habitats with temperate-humid climate. Methods: We compared invaded vs non-invaded paired plots in two backdune and two rocky areas by measuring 18 variables in litter and 24 in soils (0-5 and 5-10 cm layers). Results: Invasion effects increased with the accumulated alien necromass, decreased with soil depth and are substrate-dependent: soil pH, Al, Fe and P increased in dunes, while these variables and Mg, Cu and Zn decreased in rocky sites. Carpobrotus necromass is richer in Mg and Ca and poorer in Al, Co, Cu, Fe, Ni and Zn than native necromass. Conclusions: Invader effects on soils are largely mediated by its necromass, which has contrasting characteristics with the autochtonous necromass. Carpobrotus edulis ability to discriminate against Al uptake, while favouring Mg and Ca uptake, and its lower requirement (or higher resorption) of key micronutrients (Co, Cu, Fe, Ni, Zn) than native vegetation could partly explain its invasiveness.