Cortaderia selloana invasion across a Mediterranean coastal strip

Abstract

ABSTRACT The invasive success of Cortaderia selloana , an alien perennial grass introduced from South America, was assessed by comparing plant and population performance in ruderal and non-ruderal habitats across a Mediterranean coastal strip. The main habitat differentiation criterion was the absence or presence of visible signs of recent disturbances. Plant functional group richness (i.e. number of plant groups classified as grasses, herbs, shrubs, vines and trees), total plant cover and percentage of bare ground was calculated in each habitat. In addition, soil samples were randomly taken in order to analyse total soil C, total N, CaCO 3 , pH and soil texture. Cortaderia selloana populations were characterized by calculating total density, proportion of juvenile plants, plant volume, number of panicles and reproductive effort (i.e. number of panicles/plant volume) and fecundity per unit area (number of panicles per ha). We compared whether population characteristics and plant performance were associated with biotic and abiotic habitat factors. We expected a better performance of C. selloana in ruderal habitats than in non-ruderal habitats. As expected, ruderal habitats had larger and denser C. selloana populations and recruitment was very high (the proportion of juvenile plants was more than 50%). In consequence, in ruderal habitats, on average, plants were smaller, produced fewer panicles, and had a lower reproductive effort. The high percentage of bare ground, low pH and low functional group richness were the best explanatory variables associated to C. selloana invasion success.