Knowledge about resource limitation to soil microbes is crucial for understanding ecosystem functions and processes, and for predicting ecosystem responses to global changes as well.

Karst ecosystems are widespread in the world, and play a key role in regulating the global climate, however, the patterns of and mechanisms underlying microbial resource limitation in karst ecosystems remain poorly known.

Researchers from the Institute of Subtropical Agriculture (ISA) of Chinese Academy of Sciences investigated the microbial resource limitation in a karst region, by selecting four main land-use types, i.e. cropland, grassland, shrubland and secondary forest, in areas underlain by two lithology types, i.e. dolomite and limestone, in southwest China. Ecoenzymatic stoichiometry was used as an indicator of microbial resource limitation.

The team found that overall soil microbes in karst ecosystems were more limited by carbon and phosphorus, rather than by nitrogen. Further analyses revealed that the patterns of carbon and phosphorus limitation were different among land-use or lithology types.

Microbial carbon limitation was greatest in cropland and forest but lowest in grassland, and was greater under dolomite than under limestone. Microbial phosphorus limitation decreased from secondary forest to cropland under dolomite areas, but showed no difference among ecosystem types under limestone areas.

“This indicates that lithology controls the pattern of microbial phosphorus limitation along the post-agriculture succession.” said CHEN Hao, an associate professor at ISA.
The findings describe a general pattern of microbial resource limitation in karst ecosystems, and suggest that lithology may provide a new mechanism for explaining the variations of microbial resource limitation along the post-agriculture succession in different regions.

This work was funded by the National Natural Science Foundation of China (31872691, 41877094, 31500405), National Key Research and Development Program of China (2016YFC0502404), Natural Science Foundation of Guangxi Province of China (2017GXNSFAA198038), and the Chinese Academy of Sciences through its "Light of West China" Program to Hao Chen.
The study entitled “Resource limitation of soil microbes in karst ecosystems” has been published online in Science of the Total Environment. This article is available for download at https://doi.org/10.1016/j.scitotenv.2018.09.036.

Resource limitation of soil microbes in karst ecosystems. (Image by Chen Hao).

Contact: LI Dejun

E-mail: dejunli@isa.ac.cn

Institute of Subtropical Agriculture, Chinese Academy of Sciences