Comparing conventional and organic olive groves in central Greece: plant and bird diversity and abundance

Abstract

The present study was conducted in Magnesia Prefecture, central Greece, during the period May-June 2007. It aimed at the comparison between conventional and certified organic olive groves with regard to olive and olive oil production, diversity of plants (herbaceous and woody) and diversity and abundance of avifauna. Correlations between variables within herbaceous plants (linear regression) and woody plants (Principal Component Analysis), and the role of integration time of olive groves to the organic system were investigated. Also, finding easily measurable parameters indicating high bird diversity levels within organic and conventional management systems was a main target of the study. According to our findings, neither edible olive yield nor olive oil yield showed significant differences between conventional and certified organic olive groves. There is an increasing trend for alpha and beta diversity of herbaceous plant species, woody plant beta diversity, density and cover of woody plants, and density of breeding birds in certified organic olive groves (10 years) in comparison with conventional ones. The effect of time since the adoption of organic procedures is very important and produces benefits for the biodiversity. In the total olive groves 15 insectivorous, six granivorous and three insectivorous/ granivorous birds species were recorded. Nine bird species distinguished by Ward's hierarchical clustering were identified as typical (indicator value, IndVal > 50%) of specific farming systems. Among them, the Eurasian jay, associated with the 10-year certified organic olive groves, and the common cuckoo, Orphean warbler and Red-backed shrike, associated with the 6-year certified organic olive groves, should be regarded as characteristic species (IndVal > 70%). Conclusively, organic farming favors some aspects of diversity of herbaceous and woody plants of olive grove ecosystems. On the contrary, similar effects on breeding bird diversity and density were not clearly recorded. However, breeding bird density proved a good indicator of their richness.

Contribution of Agro-Environmental Factors to Yield and Plant Diversity of Olive Grove Ecosystems (Olea europaea L.) in the Mediterranean Landscape

“…The above results for the herbaceous plant species richness are in line with the theory that claims that the correlations between herbaceous plant species richness and diversity are simple, positive and powerful [59]. Tuomisto and Ruokolainen (2005), Sulivan and Sulivan (2006), and Solomou and Sfougaris (2011) [60][61][62] found in their research a positive correlation between the species richness and the Shannon diversity index of herbaceous plants in orchards, olive groves and natural ecosystems.…”

Natural vegetation management to conserve biodiversity and soil water in olive orchards

“…The families Poaceae, Asteraceae, and Fabaceae, which are among the richest families of the Mediterranean flora and the most common in olive orchards (e.g., Solomou & Sfougaris, 2011), were the predominant families in both mowing and tillage management systems. However, a clear effect of soil management on plant species diversity was observed almost from the first year of treatment application.…”

“…Furthermore, the four species that ranked higher IV in NVT (above 50), were previously reported in association with tillage (Verdú & Mas, 2004;Plaza et al, 2011). On the other hand, some of the more important species within NVM assemblage (Hordeum murinum L., Torilis nodosa (L.) Gaertner, Calendula arvensis L., Lamarckia aurea (L.) Moench, Campanula erinus L., and Poa annua L.) were reported in association with mowing (Mas et al, 2007) and other (Lolium rigidum Gaudin, Aegilops triuncialis L., Medicago spp., Galium tricornutum Dandy, and Hordeum murinum) with less intense tillage farming systems (Saavedra & Pastor, 1995;Plaza et al, 2011;Solomou & Sfougaris, 2011). Moreover, Galium tricornutum and Anthemis arvensis L., associated only with NVM, are arable species threatened in other European countries (Storkey et al, 2012).…”

“…Intensification also results in decline of agroecosystems plant diversity that is detrimental to the overall ecosystem equilibrium (Storkey et al, 2012). Plant diversity enhances wildlife food and shelter availability (Potts et al, 2006;Nekhay & Arriaza, 2009) and maintains pest natural predator populations, hence diminishing the need for pesticides (Solomou & Sfougaris, 2011;Paredes et al, 2013). It is also one of the most relevant factors to enhance soil stability (Pohl et al, 2009), foster microbial and fungal community richness and functional diversity, and thus N mineralization rates (Zak et al, 2003;Lamb et al, 2011).…”

“Organic is More of an American Term … We Are Traditional Farmers”: Discourses of Place-based Organic Farming, Community, Heritage, and Sustainability

“…Nelson et al (2011) found that organic intercropping or other polycultural cropping systems can substantially improve the microbial and fungal health of multiple kinds of soil. Solomou and Sfougaris (2011) found through their studies of multiple organic farms in Greece that the use of multiple organic techniques such as intercropping and organic fertilizers can increase interspecies biodiversity of flora and fauna, which can have multiple benefits for ecosystem health such as resilience against disease; higher and faster rates of, and more stable methods for, pollination, and the potential for more nutritious produce. Another study conducted by Bilalis et al (2013) found that, in comparing conventional and organic maize and tomato farms in a semi-arid climate in Zimbabwe (a very similar climate to New Mexico), multiple alternative organic technologies reduced energy inputs by more than 25%.…”