Do soil management practices affect the activity density, diversity, and stability of soil arthropods in vineyards?

Arthropods are important components of the soil fauna in improving soil quality and its structural properties. Arthropods are also very sensitive to soil management practices. Thus, a study was carried out in a vineyard in the Douro Demarcated Region (Northeast Portugal), to investigate the effect of three soil management practices (tillage, ground cover with spontaneous vegetation, and ground cover with sown vegetation) on the activity density, richness and diversity of soil arthropods, as well as on the stability of their communities. Soil-surface arthropods were assessed in 2014 and 2015 using pitfall traps, while soil-living arthropods were assessed in 2016 by collecting soil samples and extracting them through a Berlese-Tullgren funnel. The possibility of using the Soil Biological Quality index (QBS-ar index) as a tool to discriminate soils of vines subject to those management practices was also investigated. Results show that ground cover treatments significantly enhanced the activity density of soil-surface herbivores and of their potential natural enemies in both years and the activity density of detritivores in 2014. The richness of total soil-surface arthropods and potential predators was also increased by ground cover treatments in 2015. In both years, Simpson's diversity index of herbivores was enhanced by ground cover treatments, and in 2015, Simpson's diversity index of the total soil-surface arthropods, potential predators, and omnivores was significantly higher in spontaneous vegetation than in tillage or sown vegetation treatments. The soil-surface arthropods community stability was positively affected by both their activity density and richness in 2015, with that stability being better achieved in the sown vegetation treatment. In soil-living arthropods, activity density, richness and Simpson's diversity index were significantly higher in ground cover treatments than in the tillage treatment. The QBS-ar index was significantly higher in ground cover treatments than in the tillage, suggesting that this index can be a useful tool to discriminate soil management practices in vineyards. In conclusion, our results indicate that the ground cover with vegetation improves the activity density and diversity of soil arthropods in vineyards.