Changes in soil and litter properties differentially influence soil nematode communities across three successional stages in two contrasting forests

Understanding the linkages between aboveground and belowground ecosystems is important for explaining the variation in soil organisms with plant communities on a spatiotemporal scale. Here, soil nematode communities were investigated across three successional stages (early, mid, and late) in two contrasting forests at low and high latitudes in China. We found that forest succession affected the relative abundance of some nematode trophic groups, whereas it did not alter the total nematode abundance in the two forests. Nonmetric multidimensional scaling analysis showed that nematode community composition changed significantly from the early and mid-stages to the late stage. The mantel analysis showed that total soil P at low latitude and litter C:N ratio at high latitude were more closely related to the variation in nematode community during forest succession, respectively. Total nematode diversity increased marginally with forest succession at low latitude, but first increased and then decreased with forest succession at high latitude. Interestingly, total nematode diversity was related to plant-feeding nematode diversity during forest succession in both the forests. In addition, structural equation models showed that the diversity of different nematode trophic groups was directly affected by forest succession and indirectly affected by the quantity of soil resources and the quality of soil and litter. More importantly, forest succession drives total nematode diversity by directly affecting plant-feeding nematode diversity. Collectively, forest succession alters the diversity and increases the dissimilarity of soil nematode communities. However, changes in soil and litter properties during forest succession at different latitudes differentially influence nematode communities.