Effect of plant succession, ploughing, and fertilization on the microbiological oxidation of atmospheric methane in a heathland soil

The effect of plant succession on methane uptake was measured on intact soil cores collected from seven heathland sites. Six of the sites had undergone either secondary succession with grass or oak, ammonium fertilization or ploughing, while the seventh site was located in the native heathland. There was a positive relationship between methane uptake rate and time elapsed since the plant invasion had taken place in the native heathland. The native heathland site showed an insignificant atmospheric methane uptake of 0.01 mg CH4 m-2 d-1, whereas the established oak brushwood (70 years old) and the grass invaded heathland (13 years old) showed rates of 1.36 mg CH4 m-2 d-1 and 0.73 mg CH4 m-2 d-1, respectively. In the fertilized heathland plot (112 kg N ha-1 six years prior to this study) grass had become the dominating species and showed a methane oxidation rate of 0.28 mg CH4 m-2 d-1. Ploughing of the heathland resulted in methane oxidation rates seven times the rates measured in the native heathland. The results suggested that an increased future atmospheric nitrogen deposition in heathlands and other nutrient poor ecosystems may have a stimulating effect on the soil sink for atmospheric methane.