Soil health in Moroccan olive agroecosystems: The bioindication role of terrestrial nematode dynamics

Terrestrial nematodes are important soil microorganisms that modulate biological processes in soil ecosystems. Thus, these microorganisms have strong potential as soil health bioindicators. This study aimed to investigate their distribution patterns in Moroccan olive agroecosystems and to evaluate their structural and functional dynamics shaping soil disturbance status. An extensive survey was conducted across 65 representative olive fields (orchards and nurseries combined) located in 7 distinct regions during the 2023 season. For each region, several indices were calculated to assess nematode biodiversity alongside their involvement in soil food web diagnostics. The results revealed 63 nematode genera that were detected and classified into different trophic groups: 21 bacterial feeders, 7 fungal feeders, 6 omnivores, 6 predators, and 22 plant feeders. Most soil ecosystems showed low to moderate disturbance with maturing food web conditions, whereas a few showed notable soil disturbance with bacterial and conducive properties. Structural and functional dynamics revealed that both bacterial and plant feeders effectively contributed to undisturbed and disturbed soils, respectively. This study provides novel insights into the biodiversity and dynamics of terrestrial nematodes associated with Moroccan olive agroecosystems and their contribution as effective soil health bioindicators.