What Are Fluxes of CH₄, CO₂ and N₂O and their Relationships with Environmental Factors in Alpine Wetland and Alpine Grassland of Tianshan Mountains

Sep 30, 2014     Email"> PrintText Size

Global mean surface temperature has increased over the last century by approximately 0.7°C. Annual mean temperature will continue to rise more rapidly in the coming decades as a result of increasing greenhouse gases concentration. Methane (CH₄), carbon dioxide (CO₂) and nitrous oxide (N₂O) are considered as the important greenhouse gases that play important roles in climate warming.

Wetlands cover about 5% of the global land surface, and the ecosystems contribute significantly to the global greenhouse gases budget. However, there is a lack of information about emissions of CH₄, CO₂ and N₂O in the alpine wetland of the Tianshan Mountains up to now. Furthermore, researches about the fluxes of CH₄, CO₂ and N₂O in the alpine grassland of the mountains are also scarcely.

To evaluate the flux differences of CH₄, CO₂ and N₂O between the alpine wetland and alpine grassland, and to determine the effects of environmental factors on CH₄, N₂O and CO₂ fluxes in the Tianshan Mountains, LI Kaihui et al. conducted a field experiment in the growing season (from May to October) of 2010 to 2012 in the Bayinbuluk Grassland Eco-system Research Station, Chinese Academy of Sciences.

In the Tianshan Mountains, the average flux values of CH₄, CO₂ and N₂O in the alpine wetland were higher than those in the alpine grassland. The alpine wetland acted as the source of CH₄ while the alpine grassland acted as the sink of CH₄. However, both the alpine wetland and alpine grassland are sources of N₂O. All the fluxes of CH₄, CO₂ and N₂O showed large seasonal and annual variations with strong fluxes occurring in the growing season while weak fluxes occurring in the non-growing periods.

Environmental factors including air temperature, precipitation, soil temperature and soil water content greatly influenced the CH₄, N₂O and CO₂ fluxes. Relationships between CH₄ fluxes and environmental factors indicated that CO₂ fluxes were significantly positively and negatively correlated with soil temperature, air temperature and soil water content in the alpine wetland and alpine grassland, respectively. However, for CO₂ and N₂O fluxes, they were all significantly positively correlated with these environmental factors both in the alpine wetland and alpine grassland.

The findings of the study can improve a reference for understanding the fluxes of greenhouse gases in the high-altitude of the Tianshan Mountains. The study will be published in Journal of Arid Land in December 2014.