Effects of Temperature and Water Level Changes on Enzyme Activities in Two Typical Peatlands: Implications for the Responses of Carbon Cycling in Peatland to Global Climate Change

As enzymes are involved in soil nutrient and carbon cycle in peatlands, they were expected to play a key role in regulating soil organic carbon decompose process in peatlands. In addition, temperature and water levels are both crucial factors affecting enzyme activities. Therefore, we investigated the effects of temperature and water level change on enzyme activities in two typical peatlands, swamp and bog in northeast China, by using incubation experiments in laboratory. The results indicated that with the reducing of water levels, a significant increase of the acid phosphatase activity was observed both in bog and swamp (F=13.535, P≪0.01, F=8.252, P≪0.01 respectively); The variation of phenol oxidase activity in bog and swamp were not statistically significant, but the activity decreased obviously at the surface of both swamp and bog cores; Furthermore, significant variations in pH (F=12.168, P≪0.01) with water level lowering have also been found in swamp. The responses of β-glucosidase activity to water level changes appeared to be various depending on specific bog or swamp samples. However, a potential decrease in the activity of β-glucosidase with increasing depth was observed in both peatlands. In addition, a great increase of acid phosphatase activity (71%-110%) has been observed in bog when the incubation temperature rise from 15°C to 25°C, while no similar phenomena was found in swamp. As a whole, the activities of acid phosphatase, β-glucosidase and phenol oxidase increased with water levels drawdown in bog and swamp. However, almost no distinctive trends of these enzymes were observed with temperature increasing in bog and swamp, except for the activity of acid phosphatase enhanced with increasing temperature in bog. Therefore, the effects of temperature and water levels change on carbon loss in these two typical peatlands still want further study.