Effect of management strategies and substrate composition on functional and taxonomic macroinvertebrate communities in lowland ditches of Alto Adige/Südtirol.

Ditches could represent a tool for biodiversity enhancement and preservation in agricultural environments, also in Alpine regions. Macroinvertebrates and environmental factors describing water quality, substrate composition, hydrology, and geomorphology were collected in 10 ditches located in the Adige Valley, within the Biodiversity Monitoring program of South Tyrol. This study investigates the effects of ditch maintenance strategies operated in situ by the consortia (i. e., within an area of none, low and medium intensity) on taxonomic and functional macroinvertebrate diversity. We observed significant differences between management strategies in terms of both biological assemblages and environmental parameters. According to our results, these lowland ditches were mainly characterised by low substrate heterogeneity and dominated by fine organic sediments, with filamentous algae occurring only in managed sites. High concentrations of water nutrients, temperature and conductivity were associated with high intensities and frequencies of ditch maintenance. A significantly higher Shannon evenness index was found in low intensity management sites than in those with no or more intensive management. Furthermore, a decrease in %EPT and functional divergence was observed with increasing management intensity. Therefore, a sustainable management plan for ditch functioning is crucial to secure and improve both agricultural purposes and its biodiversity conservation potential in Alto Adige/ Südtirol.