Respiration and CH4 fluxes in Tibetan peatlands are influenced by vegetation degradation

Abstract

Vegetation plays a critical role in regulating ecosystem carbon (C) processes in peatlands, but vegetation faces serious degradation on the Tibetan Plateau, China. However, how vegetation degradation affects on carbon processes of peatlands remains unclear. Using the static chamber technique, we compared ecosystem respiration (Re) and methane (CH4) fluxes for healthy vegetation (HV) and degraded vegetation (DV) during two growing seasons (2013 and 2014) on peatlands of the Tibetan Plateau. We also determined the dominant factors controlling Re and CH4 fluxes. The average Re flux for DV (218.04 ± 95.08 mg C m-2h−1 in 2013 and 219.03 ± 140.96 mg C m-2h−1 in 2014) was considerably larger than that at the HV(163.78 ± 87.51 mg C m-2h−1 in 2013 and143.91 ± 84.44 mg C m-2h−1 in 2014), whereas the average CH4 fluxes for DV (0.06 ± 0.20 mg C m-2h−1 in 2013 and 0.04 ± 0.07 mg C m-2h−1 in 2014) were significantly lower than the corresponding fluxes for HV (2.19 ± 2.05 mg C m-2h−1 in 2013 and 0.85 ± 0.95 mg C m-2h−1 in 2014). The Re fluxes for the two vegetative treatments had the same temporal trends, with the peaking flux observed in July 2014. The temporal patterns of CH4 fluxes were similar to Re for two vegetation treatments where fluxes peaked in July 2014. Soil temperatures were found to be the primary factors influencing temporal Re fluxes. Soil temperatures and soil water content (SWC) were found to be the dominant factors influencing temporal CH4 flux for HV, while the main control for CH4 emission was the SWC for DV. Therefore, vegetative condition must be considered when estimating Re and CH4 flux from peatlands, particularly under the current situation of climate warming.