Peatland water level fluctuations alter the phenolic response to temperature

Phenols can either directly or indirectly contribute to the inhibition of peatland carbon cycle. Three sites in a peatland near Riganqiao National Wetland Park in Hongyuan County of the Zoige Plateau were cultured at 5 ℃, 15 ℃, and 25 ℃ to study the composite response pattern of soil phenolics and temperature in peatlands with different groundwater levels. This study aimed to understand the response of peatland carbon output to global climate change. The results showed that the total phenol, water-soluble phenol, and simple phenol contents increased significantly with decreasing water level (P < 0.05). Although the total phenol content of S1, S2, and S3 varied with temperature, their ratio remained constant as the temperature increased. Warming significantly increased the content of water-soluble phenols in S1 by 172% (P < 0.05), with a greater increase at higher temperatures; meanwhile, that in S2 and S3 exhibited a slight increase and decrease, respectively. Furthermore, warming significantly increased the content of simple phenols in peatlands by 312% (P < 0.05); the greatest increase was observed in S1, followed by that in S2 and S3. The increase in simple phenols was the highest at 15 ℃, followed by that at 25 ℃ and 5 ℃. This study found that increasing temperature had no significant effect on the total phenol content, indicating that temperature mainly influenced the phenol composition in peat by altering the content of simple and water-soluble phenols. Moreover, the water level decrease in peat weakened the response of simple and water-soluble phenols to temperature.