Data from: Contrasting impacts of nitrogen enrichment on soil nematode diversity in natural and managed ecosystems

Soil nematode communities are increasingly subjected to pressures from
multiple global change drivers, such as nitrogen (N) enrichment and land
management practices. Although the critical role of N inputs in regulating
soil nematode communities has been well studied, the contrasting responses
of soil nematode diversity to N enrichment in natural versus managed
ecosystems remain poorly understood. To address this knowledge gap, we
conduct a global meta-analysis using 3323 paired observations from 173
publications to quantify the impacts of mineral N inputs on the richness
and abundance of soil nematode diversity across natural ecosystems (e.g.,
unmanaged grasslands and forests) and managed ecosystems (e.g.,
croplands). N enrichment significantly reduced the richness and abundance
of soil nematode communities in natural ecosystems, primarily driven by
the prohibiting effects of N enrichment-induced soil ammonium toxicity and
soil acidification on the abundances of plant-feeding, fungal-feeding, and
omnivorous-carnivorous nematodes. In contrast, while N enrichment reduced
the taxon richness of soil nematode in managed ecosystems, it did not
diminish their total abundance. This discrepancy may be explained by the
increased soil microbial biomass under N enrichment, which favored the
dominance of bacterial-feeding nematodes. These nematodes thrived at the
expense of other trophic guilds with low resource competitiveness and high
N sensitivities, leading to a loss of species diversity but maintaining
overall community abundance. Furthermore, the responses of soil nematode
richness and abundance to N enrichment in managed ecosystems were not
regulated by N addition regimes and climate factors. This suggests that
management practices may override the constraints imposed by climate
change on nematode diversity. Synthesis and application: Our
findings demonstrate that N enrichment exerts a greater negative impact on
soil nematode diversity in natural ecosystems compared to managed cropping
systems, which arises from the distinct responses of different soil
nematode trophic guilds to management practices and environmental changes.
Understanding the mechanisms underlying the contrasting effects of N
enrichment on soil nematode diversity in natural versus managed ecosystems
is critical for enhancing the ecological resilience of soil food webs and
sustaining soil biodiversity in the face of global change.