The intensification of European agriculture increased food production but severely impacted farmland biodiversity and essential ecosystem services, making farming systems more vulnerable to environmental and economic challenges. To mitigate these effects, the EU’s Common Agricultural Policy (CAP) promotes agri-environment schemes that incentivise nature-friendly farming practices, though their success varies depending on implementation and local conditions. One such measure, green covers in orchards, can enhance biodiversity and ecosystem services, but its effectiveness varies a lot depending on factors like landscape complexity and farm management intensity. To better understand this, a recent SHOWCASE study, written by partners Wageningen University and CSIC, investigated whether living green covers in Mediterranean orchards can support biodiversity in farms with a wide range of management intensities. This further allows to test competing hypotheses on whether land use intensity amplifies or diminishes the benefits of agri-environmental measures.
The study was conducted in the Vega del Guadalquivir region of Southern Spain, where 15 stone fruit orchards were selected to represent a gradient of management intensity. A co-designed experiment introduced a green cover mixture in orchard alleys, while control alleys varied in vegetation management. Additionally, a management intensity index was developed based on nitrogen use and the number of field operations. Biodiversity assessments focused on pollinators, spiders and natural pest enemies using transects, suction sampling and sticky traps.
What was discovered was that compared to the control alleys, green covers in stone fruit orchards significantly increased pollinator, flower, spider, predator and parasitoid abundance and species richness. This effect was the strongest for pollinators and flowers, where interestingly, the benefits of green covers increased with management intensity, likely due to better establishment success of green covers in intensively managed orchards. In contrast, spiders, predators and parasitoids responded positively to green covers but were not influenced by management intensity, possibly due to their mobility and the stability of orchard tree rows. These findings suggest that green covers can enhance biodiversity and potentially contribute to ecosystem services like pollination and pest control even in intensively managed farms.
Read the full study here.
Image: Response of pollinator abundance and species richness to management intensity in green cover and control plots. Shaded areas represent 95 % confidence intervals.