The collaborative project “A comparison of methane (CH4) emissions from high-altitude and high-latitude wetlands during freeze-thaw period” was funded by the Academy of Finland and the Chinese Academy of Science. The project PIs are Dr. Xuefei Li from INAR, University of Helsinki and Dr. Hao Wang from Lanzhou University, China.
Large number of wetlands exist in high-latitude (>60°; HL) and high-altitude (>2500 m; HA) regions, and they are important contributors of global CH4 emissions. Both regions are characterized by the cold temperature, short growing season and wetlands in both regions are sensitive to changes in climate. We analyze the meteorological parameters as well as the CH4 and CO2 fluxes measured by Eddy covariance techniques in the last decades from two northern peatlands, Siikaneva fen a boreal oligotrophic fen located in Southern Finland (61°50′ N, 24°12′ E, 160 m a.s.l.) and Lompolojänkkä fen (67° 58' N, 24° 21' E, 200m a.s.l) in Finland and a high-altitude peatland, Haibei (37°35′ N, 101°20′ E, 3250 m a.s.l) located in the northeastern part of the Qinghai- Tibetan Plateau, Qinghai province, China. We aim to compare the carbon dynamics and the drivers of CH4 emission burst during the freeze-thaw period from three different yet similar ecosystems. The outcome of this project will contribute to a better prediction of the responses of HL and HA wetlands under future climate change scenarios.
Jianbin Wang, PhD student from Lanzhou University, has recently visited INAR for three months working on data analysis. Preliminary results showed that under similar climatic conditions, the annual mean temperature and annual mean precipitation from Haibei and Lompolojänkkä are similar, however, the seasonal patterns of precipitation are different. In Haibei, precipitation mainly happened in the growing season (>85%), while in Lompolojänkkä and Siikaneva it occurred throughout the year. The great differences in the snow coverage between HL and HA wetlands had large impact on the soil temperature and maximum soil frozen depth during the non-growing season, and consequently on the seasonal freeze-thaw pattern. In general, the non-growing season of HL wetland was longer, but the time of spring-thawing and autumn-freezing was shorter. Haibei was the strongest CO2 sink at the annual scale among the three sites. At the same time, all three sites emitted substantial amount of CH4 from the soil. The seasonal dynamics of the CH4 flux varied greatly, where Haibei and Lompolojänkkä showed the "two-peak" pattern throughout the year. Although the spring-thawing period was very short, the contribution of CH4 in this period to the whole year cannot be ignored.