BEIJING, Aug. 14 (Xinhua) -- Chinese researchers have disclosed the relationship between soil respiration and long-term rainfall reduction.

Climate models predict that droughts will increase in Southeast Asia, said a recently published study in the journal Soil Biology and Biochemistry, yet little is known about how soil respiration changes following years of drought.

The researchers from the Xishuangbanna Tropical Botanical Garden of the Chinese Academy of Sciences conducted a field experiment of long-term artificial drought plots within a tropical rainforest in Xishuangbanna, southwest China's Yunnan Province, from 2009 to 2017.

Soil respiration includes heterotrophic respiration (Rh) and autotrophic respiration (Ra). The researchers separated Rh and Ra and measured dissolved organic carbon in the soil and microbial biomass.

The results showed that the forest Ra decreased 35 percent with 36 percent root biomass reduction in the seventh and eighth year of rainfall reduction, while the Rh and active inorganic nitrogen increased by 29 percent and 31 percent respectively.

However, changes in dissolved organic carbon, microbial biomass carbon and nitrogen were inconsistent with the increase in the Rh.

Soil temperature and moisture, together with litter contents, decide the dynamics of forest soil respiration. The research can promote recognition of the relationship between the long-term drought stress of tropical rainforests and soil ecosystems.

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