PhD defence Casper Quist

Title Thesis: Impact of trophic ecologies on the whereabouts of nematodes in soil

Samenvatting (in Engels)

If the upper layer of the Earth’s crust contains sufficient minerals and organic material to support the presence of diversified forms life, it is called soil. In each soil across world microscopic roundworms, also referred to as nematodes, are found, often in overwhelming numbers. Being trophically diverse, nematodes occupy central positions in soil food webs and fulfil key-roles in soil functioning and plant growth. In this thesis, ‘Impact of trophic ecologies on the whereabouts of nematodes in soil’, Casper Quist used DNA barcode-based techniques to measure and map nematode communities in agricultural and natural settings. His work resulted in insight into the responses of nematodes to different farming strategies and plant species, at community, feeding type, life strategy and taxon-level. The degrees of nematode patchiness in visually homogeneous areas were elucidated at microscale (m2- level) and mesoscale (hectare-level) in arable and natural settings. These data provide detailed insights in the impact of various life strategies on spatial distributions, and – as practical spin off – enables the design nematode sampling schemes with predictable accuracies. This thesis shows the potential of nematode communities as indicator for the biological soil condition, and discusses how knowledge on the distributions and responses of nematodes can be applied to facilitate more sustainable (agro)ecosystem management.