Soil invertebrates facilitate plant nitrogen assimilation in a tropical seasonal secondary forest

Nitrogen is an essential nutrient for plant development, and its availability frequently constrains primary productivity during forest recovery. Soil invertebrates play a crucial role in nitrogen mineralization via litter decomposition. Despite their importance for nitrogen cycling, the direct role of soil invertebrates in facilitating plant nitrogen assimilation is not well understood. We carried out a 15-month invertebrate exclusion experiment in a tropical seasonal secondary forest, using nitrogen-stable-isotope (15N) tracers to track nitrogen transfer from 15N-labeled-leaf litter to plants in the presence or absence of soil invertebrates. Invertebrates increased 15N atom percentage in plant leaves by 59.4% through enhancing 15N release from litter by 6.3%. Here we provide evidence that soil invertebrates are vital for decomposition and plant nutrition in secondary forests. These findings suggest that decline in invertebrate populations could have cascading consequences for plant nutrient dynamics during forest recovery, which could ultimately dampen the capacity for secondary forests to sequester carbon.