Altered energy dynamics of soil nematode food web modify multifunctionality under precipitation regime change in a temperate grassland

Precipitation regimes in arid and semi-arid regions are exhibiting a trend of increase in rainfall intensity but reduction in frequency, affecting soil communities and ecosystem functions. Soil nematodes are essential components of soil communities, partaking in multiple energy channels and underpinning various crucial ecosystem functions. Understanding the impact of precipitation regime changes on energy fluxes within soil nematode food webs has a decisive impact on ecosystem function under global climate change.

This study conducted a long-term field experiment established in 2012 to simulate precipitation regime changes (the total precipitation added was 80 mm unchanged, but the size and frequency of applied precipitation events were varied) in a semi-arid grassland of Inner Mongolia. We quantified the metabolism and energetic structure of soil nematodes. We further investigated the responses of metabolic rate of trophic groups and energy fluxes within soil nematode to changes in precipitation regime, and how such changes in nematode energy dynamics affect ecosystem multifunctionality (EMF).

We found that heavy precipitation intensity increased the metabolic rates and energy fluxes of all trophic groups, and the EMF index was maximized. The EMF values were positively correlated with the metabolic rates and energy fluxes of bacterivores and omnivores/predators.

These results suggest that a shift toward higher-intensity and lower-frequency precipitation events could lead to an increase in energy fluxes within soil nematode food webs, thereby enhancing their contributions to EMF. These findings provide insights into the role of energy dynamics in affecting EMF under various scenarios of precipitation pattern changes.