Soil quality: a key factor in understanding plant invasion? The case of Carpobrotus edulis (L.) N.E.Br.

The cycles of carbon, nitrogen and phosphorus are essential components of the processes and functioning of ecosystems. The functional capacity of the soil microbial community that drives these cycles varies among soils dominated by different plant species. This work aims to quantify changes in soil features of coastal ecosystems of the Iberian Peninsula caused by the invasion of Carpobrotus edulis by analysing soil chemical properties and extracellular soil enzymes. We also analyse the influence of these changes on the germination and early development of native species Malcolmia littorea (L.) R.Br. and Scabiosa atropurpupea L. and the alien C. edulis. Our results reveal that when C. edulis invades a dune ecosystem, it causes significant changes to pH, enzymatic activities, nutrients, salinity and moisture content of the soil (the level of the change depends on the initial characteristics of the invaded ecosystem). These changes alter the germination process of native and invasive plants in different ways. The results of this work suggest mechanism whereby C. edulis competes with native species at an early stage and breaks the initial abiotic resistance of newly invaded landscapes. This study highlights the importance of studying the effects of invasive plant-soil interactions on the germination and emergence of different plant species in order to fully understand the effects of invasion and to consider options for restoration activities in areas invaded by C. edulis.