Ecosystem response of Mediterranean grasslands to the dominance of the plant invader Oxalis pes-caprae L.

One of the most aggressive invaders of the Mediterranean-type ecosystems is the exotic plant species Oxalis pes-caprae  L., which comes from the Cape of South Africa. This research studies the ecosystem response of the herbaceous vegetation understory of olive groves in SE Lesbos to the dominance of the plant invader O. pes-caprae. They were selected 30 and 28 observational stations for the year 2004 and 2005, respectively. Each station consists of a pair of plots: the reference plot and the invaded one. The plant invader O. pes-caprae was absent from the reference plot, while  it was dominant in the invaded one. In each pair of plots, it was estimated the total biomass production (above- and belowground biomass production) and the aboveground biomass per functional groups (grasses, legumes, forbs and the  invader). The dominance of plant invader O. pes-caprae has caused a significant decrease of the aboveground biomass production for both years, while the belowground biomass production has showed a significant increase, contributing to a significant increase of the total biomass production in the invaded plots for the second years of this study.