Weed Species Diversity and Community Dynamics in Organic Olive Orchards as Influenced by Cover Crop Management

Abstract

Weed community composition and species diversity in organic olive (Olea europaea L.) orchards are profoundly shaped by soil disturbance regime, ground cover management practices, and the intensity of competitive interactions between spontaneous vegetation and deliberately established cover crops, collectively determining the balance between weed suppression, biodiversity conservation, soil protection, and agroecosystem service provisioning that defines the ecological performance of organic production systems. Despite the growing adoption of cover crop-based floor management strategies in organic olive cultivation as alternatives to tillage and synthetic herbicide applications, systematic investigations quantifying the influence of contrasting cover crop management approaches on weed species diversity, community structure, functional group composition, and temporal dynamics across the annual cropping cycle remain insufficiently documented, limiting evidence-based optimization of floor management programs designed to reconcile productive and conservation objectives in organic orchard systems. This study evaluated weed species diversity and community dynamics in organic olive orchards subjected to contrasting cover crop management treatments including spontaneous vegetation control, seeded grass-based cover crops, seeded legume-based cover crops, and mixed grass-legume cover crop combinations managed through mowing, rolling, and minimal tillage interventions across multiple seasonal assessment periods. Weed floristic surveys were conducted at phenologically standardized intervals using nested quadrat sampling protocols, with species abundance, frequency, and cover recorded for all spontaneous vegetation components within inter-row and under-canopy zones across replicated experimental plots. Diversity indices including species richness, Shannon-Wiener diversity, Simpson dominance, Pielou evenness, and Sørensen similarity coefficients were calculated to characterize alpha and beta diversity dimensions of weed communities across management treatments and sampling periods.