Grazing Stocking Rate and Rainfall Jointly Regulate Soil Methane Uptake in a Temperate Meadow Steppe, but Do Not...

Area of Science:

• Ecology
• Climate Science
• Biogeochemistry

Background:

• Grasslands are crucial methane (CH4) sinks, but their capacity is declining due to human activities and changing precipitation.
• Livestock grazing expansion significantly increases methane emissions, posing a threat to grassland CH4 sink function, especially in grazed Eurasian regions.

Purpose of the Study:

• To investigate the combined effects of grazing intensity and precipitation variability on grassland CH4 fluxes over an 11-year period.
• To assess both short-term and long-term influences of grazing and environmental factors on CH4 uptake dynamics in temperate grasslands.

Main Methods:

• Conducted an 11-year manipulative grazing-gradient experiment in temperate meadow grasslands.
• Measured soil CH4 uptake across varying grazing intensities and precipitation regimes (wet and dry years).
• Estimated livestock-derived CH4 emissions and analyzed biotic/abiotic drivers (vegetation, soil properties, microbial biomass).

Main Results:

• Over the long term, CH4 fluxes were jointly regulated by precipitation and grazing intensity; overgrazing exacerbated rainfall's suppressive effect on CH4 uptake.
• Soil CH4 uptake exhibited a lagged response to grazing, potentially triggered by extreme rainfall events.
• Moderate grazing sustained long-term CH4 uptake but did not offset livestock-derived CH4 emissions.

Conclusions:

• Grassland CH4 dynamics are complex, influenced by both grazing and precipitation, with significant implications for climate change.
• Overgrazing diminishes CH4 sink capacity, while moderate grazing shows potential but is insufficient to counteract emissions.
• Understanding these interactions is vital for managing grasslands as effective CH4 sinks under changing climatic conditions.