Structure of canopy and ground-dwelling arthropod communities in olive orchards is determined by the type of soil cover

Jesús Castro,Francisco S Tortosa,Antonio J Carpio

doi:10.14411/eje.2021.017

Abstract

The intensification of agriculture in olive groves, especially the modification or elimination of spontaneous vegetation, alters the relationships in arthropod communities and reduces their interactions and ecosystem services. This study was carried out in nine olive groves in which there was either a planted cover crop, spontaneous cover crop or bare ground. The interactions of ground-dwelling, canopy and flying arthropods in trophic webs were calculated for each olive grove soil management regime at the family level taking into consideration their different functional traits: feeding guilds, specific agricultural traits and trophic level. Olive groves with spontaneous cover had trophic webs with a higher number of plausible links between arthropod families and a more balanced distribution of specimens among trophic levels compared to those with planted cover and bare ground. There was a similar number of arthropod families consisting of both pests and their natural enemies in the planted cover regime, while olive groves with bare ground had simpler trophic webs. The complexity of plausible trophic links was greater in olive groves with spontaneous plant cover despite the similar values for family richness in the three-olive grove soil management regimes. Qualitative values (such as functional traits) were more diverse in agroecosystems with spontaneous plant cover in which there were more sources of food.

Highlights

Agricultural intensification includes practices, such as, the use of synthetic fertilisers and pesticides, increases in the size of fields, removal of hedgerows and woodlands and the intensification of tillage, which has led to a decline in biodiversity in cropping system and surrounding areas (McLaughlin & Mineau, 1995; Médiène et al, 2011)
A total of 2863, 2503 and 1636 arthropods were caught in the olive groves with planted, spontaneous and bare ground cover, respectively
Our results show that soil management in olive groves that results in a highly complex and structured diversity of herbaceous plants support the most diverse and interconnected arthropod communities

Summary

Introduction

Agricultural intensification includes practices, such as, the use of synthetic fertilisers and pesticides, increases in the size of fields, removal of hedgerows and woodlands and the intensification of tillage, which has led to a decline in biodiversity in cropping system and surrounding areas (McLaughlin & Mineau, 1995; Médiène et al, 2011). Perhaps of more concern is the consequences of the loss of biodiversity for ecosystem functioning and services (Naeem et al, 1994; Loreau et al, 2001). The loss of biodiversity in agroecosystems is, directly or indirectly, related to the reduction of ecosystem services in terms of pollination (Kremen et al, 2002), carbon sequestration (Kazemi et al, 2018), increases in soil erosion (Bender et al, 2016) and appearance and prevalence of pests (Karamaouna et al, 2019). The use of environmentally friendly systems (zero chemical weeding, less use of synthetic pesticides and fertilizers and application of environmentally-friendly ground vegetation management) are spreading in Mediterranean Europe resulting in considerable benefits in terms biodiversity and soil loss (Berg et al, 2018; Camarsa et al, 2018; De Luca et al, 2018)

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