Soil carbon, the largest carbon pool in terrestrial ecosystems, includes both organic matter and inorganic carbon stored in global soils.

The rhizosphere priming effect is a mechanism by which plant roots interact with soil functions, and is an important factor affecting the decomposition of soil organic matter and thus soil carbon source-sink relationships. Previous studies focused on quantifying the rhizosphere priming effect (RPE) in growing seasons and found that RPE varies with plant species and can be altered by soil nutrient availability. So far, however, little is known about RPE in non-growing seasons.

Prof. Wang Peng and assistant researcher Lu Jiayu from the Underground Ecological Process Group of the Institute of Applied Ecology (IAE) of the Chinese Academy of Sciences (CAS) recently quantified RPEs of four perennial herbs in a non-growing season, that is, after leaf senescence and before shoot regrowth.

The researchers used stable isotope technology and found that, though all four species (Elymus dahuricus, Stipa grandis, Medicago sativa and Melissilus ruthenicus) had positive RPEs in the non-growing season, the RPE values were greater for the legume species (Medicago sativa and Melissilus ruthenicus) than for the non-legumes (e.g. Elymus dahuricus).

According to the researchers, the interspecific difference in RPE can be explained by plant root traits: plants with larger root-to-shoot ratio, root diameter, and hyphal colonization rate may lead to greater RPEs in non-growing seasons. And according to their estimation, the non-growing-season cumulative RPE of Stipa grandis and Medicago sativa accounted for approximately 1/3 of the annual soil CO2 flux of each species, indicating the importance of RPE in non-growing seasons.

This study has been published in Geoderma, entitled “Rhizosphere priming effect of four non-woody perennials after leaf senescence and before shoot regrowth”, and it was funded by the Natural Science Foundation of China, the National Key R&D Program of the Ministry of Science and Technology, and the (Class A) Strategic Priority Research Program of CAS.

Contact 

YUE Qian

Institute of Applied Ecology, Chinese Academy of Sciences 

Tel: 86-24-83970324 

E-mail: yueqian@iae.ac.cn  

Web: http://english.iae.cas.cn