Microbial traits drive soil priming effect in response to nitrogen addition along an alpine forest elevation gradient

Area of Science:

• Soil Science
• Ecology
• Microbiology

Background:

• The priming effect significantly influences the soil organic carbon (SOC) cycle.
• Drivers and patterns of the priming effect in response to nutrient addition in alpine forests remain poorly understood.

Purpose of the Study:

• To investigate the priming effect and microbial traits in alpine forest soils under nutrient addition.
• To elucidate the role of microbial communities and soil enzymes in regulating carbon decomposition along an elevational gradient.

Main Methods:

• A 28-day incubation experiment using soils from the southeastern Tibetan Plateau (3500-4300 m).
• Analysis of the priming effect using 13C-stable glucose.
• Assessment of microbial traits via bioinformatics and soil enzyme activity assays.

Main Results:

• Carbon priming effect (PEc) ranged from 0.45 to 1.63 mg C g-1 SOC, correlated with soil organic carbon and total nitrogen.
• Nitrogen addition inhibited PEc and increased the activity of key soil enzymes (glucosidase, N-acetyl-glucosaminidase, cellobiosidase, xylosidase).
• Microbial community networks became more complex and stable with nitrogen addition, with fungal communities driving PEc.

Conclusions:

• Microbial communities, particularly fungi, are key drivers of the priming effect in response to nitrogen addition in alpine regions.
• Soil enzymes act as crucial intermediaries in nitrogen-mediated soil carbon mineralization.
• Alpine microorganisms exhibit higher sensitivity to nitrogen than carbon, influencing the soil carbon cycle under global environmental change.