Arthropod, bacterial and fungal communities in vineyards with different soils and management in Oltrepò Pavese (Italy): a multidisciplinary approach

Soils are a key reservoir of global biodiversity, and their fundamental role is to support soil functions and ecosystem services. Biodiversity is part of the complexity and is linked to other parameters that characterise soils, and changes in soil health status influence the provision of goods and services to its beneficiaries. Knowing the biodiversity of a soil in vineyard systems and trying to relate it to other soil characteristics helps to improve soil health, apply the more suitable NBS to reduce land degradation, to improve the ecosystem services provided by the soil and to make viticulture more sustainable.

Six vineyards were selected in Oltrepò Pavese, one of the most important high-quality wines areas in Northern Italy, in different geological contexts soils with different inter-row management techniques: permanent grass cover, tillage and alternate tillage. Soil samples were collected in each vineyard, where a 1.0 m × 2.0 m trench was dug, in order to determine the geological, chemical, agronomic and physical properties. With a multidisciplinary approach, these properties were compared with the fungal, bacterial and arthropod communities.

Environmental DNA (eDNA) was extracted, and bacterial and fungal communities were detected by NGS analysis of 16S and ITS1 DNA barcodes, respectively. Arthropod communities were described by soil biological quality (QBS-ar) and biodiversity indices, after morphological identification of the different biological forms detected.

Inter-row management techniques and geological characteristics affect bacterial, fungal and arthropod communities’ composition. Soil managed with permanent grass cover are in general richer of fungal and bacterial biodiversity. Arthropods seem to be more influenced by soil texture and consequently by the chemical and physical characteristics of the soil than by tillage or grassing in the dry season. A positive correlation was found between Fungi and Bacteria orders, a negative correlation between Arthropods and Fungi orders and a weak and not significant correlation between Arthropods and Bacteria orders. The composition of the bacterial community was radically different in soil under repeated tillage and mineral fertilisation where Bacteroidia, Bacilli, Clostridia and Fusobacteria prevailing, in permanent grass cover soils the classes Alphaproteobacteria, above all, Acidobacteria-6 and Actinobacteria prevailed. Repeated tillage results in a different composition of the prevalent fungal Classes, with a predominance of Malasseziomycetes, which are not present in permanent grass cover soils. Fungi showed a positive correlation with water content, nitrogen and organic matter, while bacteria have a positive correlation with plastic limit and pH.

The results of the study can be used to helps farmers in the selection of the best inter-row management techniques in vineyards in order to reduce the effects of climate change and mitigate the effects of erosion.