Ant mounds reshape soil nematode food-web composition and energy flow uniformity during long-term desert revegetation

The mounds, engineered by ant activities, critically reshape the composition of the soil nematode food web in desert ecosystems by modifying key microhabitat conditions. This study examined soil nematode communities including food-web composition and energy flow in and outside ant mound microhabitats across five revegetated plantation ages (5a, 8a, 11a, 37a and 60a, ‘a’ denotes years since plantation establishment) of the Tengger Desert. We found general enhancement of the abundance of bacterivorous and fungivorous nematodes alongside revegetated plantation age. However, there was a significant increase in the abundance and diversity of omnivore-carnivores that was observed primarily in ant mounds relative to open spaces without mounds during later successional stages. Here, we crucially observed localized disturbance effects of ant mounds despite their functioning as ‘resource islands’: (1) both bacterivore and omnivore-carnivore abundance, and total energy flux of soil nematodes were found significantly lower in ant mounds compared to open spaces at the 11a plantation, suggesting a possible temporary suppressive effect; (2) Conversely after 11a onwards, through 37a toward 60a, ant mounds significantly increased omnivore-carnivore diversity and overall nematode energy flow uniformity. Partial least squares structural equation modeling revealed that ant mound effects, largely driven by variation in Formica cunicularia and Messor aciculatus abundance, influenced energy flux via bacterivores relative abundance, while energy flow uniformity increased with omnivore-carnivore diversity alongside revegetated plantation ages. Our results highlight the dynamic, stage-dependent role of ant mounds in regulating soil nematode food webs during long-term desert revegetation, acting as either resource hotspots and/or temporary disturbance-context depending on plantation age and ant activity intensity.