Nitrogen deposition enhances accumulation of microbial and plant-derived carbon in forest soils: a global meta-analysis

Plant and microbial-derived carbon (C) constitute the soil C pool and determine its response to N deposition. However, the response of plant and microbial-derived C to exogenous N input in forest soils, accounting for 70% of the global soil C, remains unclear.

We conducted a global meta-analysis to assess the response of microbial-derived C (indicated by amino sugars) and plant-derived C (indicated by lignin phenols) in forest soils to the increasing N deposition.

Results revealed significant increases in both total amino sugar and lignin phenols, with a more pronounced increase in temperate forest soils experiencing low-level N addition. Glucosamine (GluN) exhibited no significant change, but muramic acid (MurN) was increased following N addition. Positive correlations were observed between total amino sugars and SOC and total phospholipid fatty acid (PLFA), as well as between MurN and bacterial PLFA. Lignin phenols were positively correlated with litterfall but unrelated to root biomass.

N deposition enhanced the accumulation of microbial and plant-derived C in soils, particularly in N-deficient temperate forest soils. The accumulation of microbial-derived C is primarily attribute to the increased microbial biomass and bacterial-derived C, while the accrual plant-derived C is mainly associated with the increase in aboveground C input caused by N addition. These findings collectively uncover the general patterns and mechanisms of microbial and plant-derived C in forest soils in response to N deposition, providing new insights into interpreting soil C dynamics and predicting soil C pools in forest ecosystems facing future climate changes.