Soil priming effect and its responses to nutrient addition along a tropical forest elevation gradient

Area of Science:

• Terrestrial Ecology
• Soil Science
• Biogeochemistry

Background:

• Priming is crucial for terrestrial carbon cycling, but its patterns and drivers in tropical forests are poorly understood.
• The influence of nutrient addition on priming in these ecosystems remains unclear.

Purpose of the Study:

• To investigate the patterns and drivers of priming effects across a tropical forest elevation gradient.
• To determine how nutrient (N and/or P) additions influence priming and its relationship with initial soil nutrient availability.

Main Methods:

• Collected soils along an elevation gradient in a tropical forest.
• Conducted incubation experiments using 13C-labeled glucose and nutrient additions (N, P, NP).
• Analyzed soil organic carbon (SOC) content, pH, and nutrient availability.

Main Results:

• Priming effects increased soil organic matter decomposition by 44 ± 12% across elevations, with intensity decreasing with elevation.
• Soil organic carbon (SOC) content and pH were key negative and positive regulators of priming, respectively.
• Nutrient additions did not significantly alter priming, but their effects varied with initial soil nutrient availability, decreasing with higher initial N or P.

Conclusions:

• Proposed a conceptual framework integrating stoichiometric decomposition and nutrient mining hypotheses to explain nutrient addition effects on priming.
• Highlighted the importance of SOC content and soil pH in regulating priming intensity.
• Emphasized the role of initial soil nutrient availability in modulating the response of priming to nutrient additions in tropical forests.