Aim: As the two largest components of plant detritus input, leaf and root litter together determines ecosystem vegetation turnover and nutrient cycling rates. However, it remains unknown the similarities and differences between the controlling factors for their decomposition. We evaluated the relationship between leaf and fine root litter decomposition across biomes, and analyzed how litter traits, climate, soil conditions and decomposers shape their relationship.

Location: Global.

Time Period: 1984–2020.

Major Taxa Studied: Vascular plant.

Methods: We collected 352 paired leaf and fine root decomposition rates (k values) and ancillary traits, climate, soil condition and decomposer abundance data from 88 sites spanning the major global biomes. Boosted regression trees (BRTs) were applied to partition the factors that control root and leaf decomposition rates.

Results: Averaged across all biomes, leaf litter decomposes significantly faster (kleaf=0.72) than fine root (kroot=0.42). The BRTs indicated that plant traits best explained the variance in both leaf and root litter decomposition. The key chemical traits of leaf litter and fine root, including C:N, [P], N:P, [lignin], [cellulose], [NSCs] and [tannins], were positively correlated. Therefore, leaf and fine root k values were positively correlated within and across biomes, even after removing the influence of climate, soil conditions and decomposers. However, climate and decomposers had different impacts on leaf and fine root decomposition. Climate induced a greater impact on fine root litter decomposition, whereas decomposers had a greater influence on leaf litter decomposition.

Main Conclusions: Our finding indicates that plants evolve a coordinated nutrient supply and demand strategy. The high nutrient demand plants produce labile leaf and fine root litter, which decompose fast to meet their high nutrient requirements. However, leaf and fine root decomposition are also mediated by different combinations of trait, climate, soil condition and decomposer factors, which weakens the coordination between leaf and fine root decomposition.