Effects of protected areas on soil nematode communities in forests of the North of Portugal

Abstract Nature conservation policy is mainly concerned with aboveground terrestrial species and soil biodiversity has been largely ignored, resulting in a lack of information about the conservation status of most soil organisms and about the effects that nature conservation policies have on soil systems. Forests in Northern Portugal are characterized by a remarkable diversity of ecosystems and provide habitat for an enormous diversity of living organisms. This study aims to investigate whether and to what extent protected areas and forest typology (native vs. exotic) affect soil nematode biodiversity and functions in forest ecosystems. We studied soil nematode communities, which have been widely used for their bioindicator value, to: (i) assess differences in soil biodiversity and functions between protected and non-protected areas, and between native and exotic forest types; and (ii) infer how protected areas deal with pressures and drivers of soil biodiversity and functions. We showed that current work done by nature conservation in Northern Portugal is producing some significant effects on the soil system, showing a larger Structure and Omnivore footprints and greater abundance of fungivorous and omnivorous nematodes in protected areas. Furthermore, native forest areas are better suited to ensure soil biodiversity and ecological functioning and should have a greater importance in nature conservation measures. Soil organic carbon, apparent density, soil moisture, and deciduous forest cover mainly influenced soil functional biodiversity with higher nematode trophic groups being positively associated with soil organic carbon and moisture and negatively associated with apparent density. Finally, conservation efforts targeted at the protection of native forests need to better consider effects on soil biodiversity and function, to provide an integrated protection of both aboveground and belowground components.