Abstract

Olive orchards constitute important reservoirs of floristic diversity, including species that are strongly dependent on agroecosystems for their persistence. The conservation of floristic diversity enhances the provision of essential agroecosystem services, contributing to the sustainability of olive orchard agroecosystems. The main aim of this study was to provide a descriptive analysis of the floristic diversity of olive orchards, a topic that has not been investigated extensively in Crete. The study was designed to capture variation associated with management system (MS) and agroecological zone (AZ), providing a comprehensive assessment of floristic diversity. A seven-and-a-half-year floristic survey was conducted in the Messara Valley, Crete, Greece, across nine organic olive orchards implementing Green Infrastructure (GI), eight conventionally managed orchards, and two abandoned orchards. The orchards were located in both plain and hilly agroecological zones. Within each orchard, monthly surveys were conducted in three randomly assigned square sampling stations per hectare, which remained constant throughout the study period. A descriptive analysis and univariate comparisons between the MS and AZ were conducted using six pairs of organic and conventional orchards, with three pairs located in the hilly AZ and three in the plain AZ. In total, 331 species, belonging to 60 families and 28 taxonomic orders, were identified. Most recorded species were characterised as therophytes (55%) and hemicryptophytes (31%), mainly belonging to the families Asteraceae, Fabaceae, Poaceae, and Lamiaceae. Total species richness was higher in organic (257 species, 56 families) than in abandoned (195 species, 45 families) and conventional orchards (192 species, 50 families), however, the mean species richness did not differ statistically significantly among management systems. Mean species and family richness were significantly higher in the hilly AZ than in the plain AZ, and total species richness was also higher in the hilly AZ (316 species, 59 families) than in the plain AZ (128 species, 43 families). This study highlghts the role of olive orchards as reservoirs of floristic diversity in Crete and demonstrates the influence of MS, Green Infrastructure and AZ in shaping the floristic diversity of these agroecosystems.

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