Seed bank longevity and germination ecology of invasive and native grass species from Mediterranean wetlands

Abstract

Most Mediterranean wetlands are overexploited and degraded by different factors and are especially vulnerable to alien and invasive species. Currently, there is still a lack of knowledge on certain aspects of plant invasions, especially from an applied point of view, as key tools in restoration and conservation programmes. In this sense, Cortaderia selloana has showed a rapid expansion in the western Mediterranean Basin, threatening habitats of special interest such as wetlands. A comparative study between C. selloana and Saccharum ravennae, a representative plant of Mediterranean marshlands, was carried out to characterize the biological pattern that has made C. selloana a potential threat. The role of these plant species in soil seed banks and the potential competitive displacement of S. ravennae were evaluated through seed germination and viability tests under accelerated ageing conditions and seedling root development, considering seed morphological characteristics, seed maturity and plant sexuality as influential factors. Additionally, the potential allelopathic effects of C. selloana leaves on S. ravennae seed germination were evaluated. The study found differences between the species in all the tested parameters, seed morphology, germination response and longevity, adsorption isotherm curves, and allelopathic effects. All these factors establish a complex interaction that contributes to the proven invasive character of C. selloana. These results provide useful data for eradication and management programmes.