Herbaceous Plant Diversity and Identification of Indicator Species in Olive Groves in Central Greece

The present study is aimed at assessing the herbaceous plant diversity and determining the specific species related to different management systems in olive grove ecosystems [organic, conventional (unsprayed), and conventional (sprayed)] in two sites (Nies and Pteleos) of Magnesia Prefecture (central Greece). The sampling of herbaceous vegetation was carried out in randomly selected plots of 0.25 m(2) (0.5 mx0.5 m) each. The results showed that the organic system in Pteleos favored plant species richness and Shannon-Weiner, Simpson, Margalef, Brilluin, McIntosh, and Menhinick indexes more than the other management systems (P < 0.05). A Renyi diagram revealed the greatest plant diversity in the organic system in Pteleos site. According to cluster analysis results, the organic and the conventional (unsprayed) olive groves in Pteleos exhibited a strong similarity regarding plant diversity. The same was detected in the pairs: Nies conventional (unsprayed) and Nies organic, and in Nies conventional (sprayed) and Pteleos conventional (sprayed). IndVal analysis revealed three characteristic types of indices, Chenopodium album in the organic olive groves in Pteleos, Sinapis arvensis in the organic ones in Nies, and Aegilops geniculata in the conventional (unsprayed) olive groves in Nies.