Root exudation can influence soil organic matter (SOM) decomposition via the rhizosphere priming effect (RPE). The RPE is becoming increasingly considered to be an important driver regulating soil carbon (C) and nitrogen (N) cycles. Plants can allocate up to one quarter of photo-assimilates to root-associated mycorrhizal fungi.  

 A research team from the Institute of Applied Ecology of the Chinese Academy of Sciences (CAS) conducted an experiment by employing a ¹³C natural abundance approach combined with a ¹⁵N dilution method. They grew five tree species associating with either arbuscular mycorrhizal fungi (AM) or ectomycorrhizal fungi (ECM) and aimed to investigate the magnitude of the RPE caused by tree-mycorrhizal associations and the underlying mechanisms. 

They found that SOM decomposition induced by AM-associated trees had a significantly higher C:N ratio than that of ECM-associated tree, which could be associated with the differences in microbial enzyme activities. Based on these findings, They developed a new framework centered on contrasting effects of tree-mycorrhizal association on SOM decomposition via RPE. 

These findings highlight that more attention should be paid to mycorrhizal types for their role in modulating soil biogeochemical cycling via the RPE.

This study was published in Soil Biology & Biochemistry entitled “Arbuscular mycorrhizal trees cause a higher carbon to nitrogen ratio of soil organic matter decomposition via rhizosphere priming than ectomycorrhizal trees”. 

This study was supported by the National Key R&D Program of China, the National Basic Research Program of China and the National Natural Science Foundation of China. 

FIG 1. A new framework centered on contrasting effects of tree-mycorrhizal association on RPE (Image by WANG Peng) 

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