Invasibility of three native plant communities tο the establishment of the plant invader Oxalis pes-caprae L.

Although some invasive plants are cosmopolitan, not all ecosystems are invaded to the same degree. Yet, there is little experimental work on how ecosystem resistance to invasion at the establishment phase differs among ecosystems. We conducted a field experiment to examine establishment of the plant invader Oxalis pes-caprae in coastal dunes, shrublands and herbaceous understory of olive groves in Lesbos. We selected thirty (30) observational stations, ten per native plant community. Each station consists of a pair of plots: the invaded plot and the reference one. In each invaded plot, we sowed a hundred bulbs of O. pes-caprae, measured the number of seedlings of the plant invader and estimated local species richness, diversity and evenness of native plant communities. In addition, we recorded not only the geographical longitude, the geographical latitude and the elevation in each observational station, but also precipitation and mean temperature for the period between sowing and sampling. Local species richness and vegetation structure were not a good predictor for seedling establishment in costal dunes and herbaceous understory of olive groves. All abiotic factors did not determine the ecosystem invasibility of native plant communities. Finally, we found out that differences in local species richness and diversity of shrublands were only associated to differences in establishment rates of plant invader. Consequently, we concluded that any species poor shrublands are more susceptible to the invasion of the plant invader O. pes-caprae.