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

• Published in: Global change biology 2021-06, Vol.27 (12), p.2793-2806
• Main Authors: Feng, Jiguang, Tang, Mao, Zhu, Biao
• Format: Article
• Language: English
• Subjects: Availability; Carbon cycle; Decomposition; elevational patterns; enzyme activity; Incubation period; Microorganisms; Mineral nutrients; Nutrient availability; nutrient enrichment; nutrient mining hypothesis; Organic carbon; Organic matter; Organic soils; pH effects; Priming; priming effect; Soil; Soil chemistry; Soil organic matter; Soil pH; Soil properties; Soils; stoichiometric decomposition hypothesis; Terrestrial environments; Tropical climate; Tropical forests
• ISSN: 1354-1013; 1365-2486
• DOI: 10.1111/gcb.15587

Priming plays important roles in terrestrial carbon cycling, but the patterns and drivers of priming and its responses to nutrient addition in tropical forests remain unclear. By collecting soils along a tropical forest elevation gradient, we conducted an incubation experiment with 13C‐labeled glucose and nutrient (N and/or P) additions. Results showed that priming effects increased soil organic matter decomposition by 44 ± 12% across elevations, and priming intensity decreased significantly with elevation. Among soil and microbial properties, soil organic carbon (SOC) content and pH were two key factors negatively and positively regulating priming, respectively. Across elevations, the additions of N, P, or both of them (NP) did not significantly change priming. However, the variations in the effects of nutrient (N and/or P) addition on priming significantly correlated with initial soil nutrient (N or P) availability. The intensity for the effects of N addition on priming decreased significantly with initial soil N availability, and that for the effects of P and NP addition on priming decreased with initial soil P availability. Based on these relationships, we proposed a conceptual framework linking stoichiometric decomposition and nutrient mining hypotheses, in which the former dominates in low‐nutrient availability soils and the latter dominates in high‐nutrient availability soils. This conceptual framework can help to explain the contrasting effects of nutrient addition on priming. Collectively, our findings highlight the roles of SOC content and soil pH in regulating priming intensity, and the role of initial soil nutrient availability in regulating the effects of nutrient addition on priming. Soil organic carbon content and pH have important regulations on priming effect. The effects of nutrient addition on priming depend on initial soil nutrient availability, with N‐addition effects on priming decreasing with soil N availability, and P‐ and NP‐addition effects on priming decreasing with soil P availability. Based on these relationships, we propose a conceptual framework linking two nutrient‐centered hypotheses regarding priming (i.e., stoichiometric decomposition and nutrient mining), in which the former dominates in low‐nutrient availability soils and the latter dominates in high‐nutrient availability soils. This framework can help to explain the contrasting effects of nutrient addition on priming.