Concentration characteristics and the drivers of soluble components in freshly fallen plant litter

Soluble components leach rapidly during the early stage of litter decomposition and represent the earliest nutrient input to the soils after leaf fall, which have significant importance for the material cycle in ecosystems. However, the concentration characteristics and primary drivers of litter soluble components at the global scale remain unclear. Therefore, 303 observations of water soluble compounds (WSCs), dissolved organic carbon (DOC), and dissolved organic nitrogen (DON) and auxiliary plant functional traits (mycorrhizal association, taxon division, plant life form, and leaf type) were collected worldwide. Linear mixed-effect models were used to examine the relative effects of climate, soil, topography, and plant functional traits on the concentration of different soluble components of litter. The average concentrations of leaf litter WSCs, DOC, and DON were 22.50, 4.15, and 0.01%, respectively. The concentration of WSCs in leaf litter was regulated by plant functional traits and soil properties, with mycorrhizal association and soil microbial biomass carbon to nitrogen ratio as the primary drivers. The concentration of DOC in leaf litter was influenced by climate and topography, with elevation being the most important factor. Our study reveals the global patterns and drivers of different soluble components in leaf litter, which is crucial for predicting litter decomposition under future climate change.