Savannas are mixed ecosystems characterized by a grass understory with a tree/shrub overstory and distinct wet and dry seasons. They are thought to contribute to approximately 17% of the global N2O production from terrestrial systems. However, relevant studies have been primarily conducted during the rainy season, and whether savanna soil is a source or sink of N2O during the dry season remains uncertain.
Researchers from Global Change Ecology Group of Xishuangbanna Tropical Botanical Garden (XTBG) evaluated the effects of precipitation reduction on soil N2O fluxes from a woody savanna ecosystem in Yuanjiang, Yunnan Province, Southwest China. They got their results published in Atmospheric Environment.
The researchers established a precipitation-excluding roof above the canopy of a woodland savanna and set up three exclusion treatments to evaluate the effects of precipitation exclusion on N2O emissions from the soil. They also determined whether the Yuanjiang savanna was an N2O source during both the rainy and dry seasons.
They studied the effects of precipitation reduction on N2O emissions for two continuous years in Yuanjiang savanna ecosystem, the most typical savanna ecosystem of China.
The researchers found that Yuanjiang savanna emitted N2O, precipitation reduction decreased N2O emissions. The decrease rate of precipitation exclusion on N2O emissions during the dry season was stronger than during the rainy season. Additionally, the N2O emissions decreased as precipitation exclusion continued, and no negative N2O fluxes were observed.
They thus concluded that t the savanna may be a source of N2O; the N2O emissions during the dry season may play a vital role in total N2O emissions. In addition, precipitation reduction decreased N2O emission from soil but did not change the soil from an N2O source to an N2O sink.
ZHANG YipingPh.D Principal Investigator
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China