Elevational gradient regulates the effects of short-term nutrient deposition on soil microorganisms and SOM decomposition in subtropical forests

AimsAlthough studies have investigated how nitrogen (N) and phosphorus (P) deposition alone alter terrestrial ecosystems, the responses of soil microorganisms and their functions to interaction of N and P deposition have not been studied across an elevational gradient in subtropical forests.MethodsBy conducting N and P deposition experiments at three elevational levels in subtropical forests, we determined how the responses of soil microorganisms and their functions to N and P deposition differ at low (1300 m), moderate (1800 m), and high (2350 m) elevations.ResultsMicrobial biomass of most functional groups differed among the three elevations; microbial biomass was lowest at the moderate elevation, and the elevation-induced changes in microbial biomass were positively correlated with soil substrate quality (e.g., soil N/P). After two years of treatment, N deposition had negative effects on microbial biomass and interacted with P deposition at the low elevation, while N or P deposition had positive effects on microbial biomass at the moderate elevation. N deposition decreased SOM-C decomposition at the low (16%) and moderate (8%) elevations; N deposition decreased SOM-N decomposition (10%) at the low elevation but increased SOM-N decomposition (16%) at the moderate elevation. P deposition increased SOM-C decomposition (14%) at the low elevation but decreased SOM-C decomposition (6%) at the high elevation.ConclusionsOur results evidenced that short-term effects of nutrient deposition on soil microorganisms and SOM decomposition were altered by elevational gradient in subtropical forests, suggesting that the effect of nutrient deposition on belowground communities and functions are environmental context-dependent.

Automated summary

By conducting nitrogen and phosphorus deposition experiments at different elevations in subtropical forests, it was found that the effects of nutrient deposition on soil microorganisms and soil organic matter decomposition varied across elevational gradients. The results demonstrate that the short-term effects of nutrient deposition on soil microorganisms and soil organic matter decomposition are modulated by environmental context.