Soil Microbial Co-Occurrence Networks Across Climate and Land Use Gradient in Southern Italy.

Despite extensive research on microbiota across land use gradients, it remains unclear if microbial co-occurrence relationships exhibit consistent patterns. Here, we assessed microbial co-occurrence networks of seven natural ecosystems-Quercus ilex forest, Fagus sylvatica forest, Abies alba forest, Mediterranean and mountain grasslands, and subalpine and Mediterranean shrublands-and five agroecosystems, including vineyards, horticulture, greenhouse, a polluted agricultural system, and an arid greenhouse. Soil chemistry, such as pH, organic carbon and total nitrogen, was characterised, and soil microbiota were profiled using high-throughput sequencing from 242 soil samples. Our results revealed that mountain grasslands had the highest organic carbon (86.4 g/kg), while the arid greenhouse had the lowest (6.1 g/kg). Mediterranean grasslands had the lowest pH of 5.79, and vineyards had the highest electrical conductivity of 0.901 dS/m. Notably, natural ecosystem networks exhibited greater modularity, with protected horticulture showing exceptionally the highest (0.937), while intensive agriculture within agroecosystems had a significantly lower modularity of 0.282. Modularity and the number of modules were positively correlated with soil P