Environmental changes and human activities may change above- and underground litter inputs to the soil, which can regulate the sequestration and storage of soil organic carbon by changing community composition and activity of soil microbes in forest ecosystems.A number of studies have examined the impacts of removing forest litter on soil microbes. However, the results of these studies are quite variable, which greatly limits their potential to predict soil organic carbon dynamics. 

A research team led by WANG Qingkui from the Institute of Applied Ecology, Chinese Academy of Sciences recently conducted a meta-analysis to explore a global-scale overview of the impacts of forest above- and underground litter on soil microbes.  

They collected data from 68 published articles which included litter removal experiments in these researches. And they found that the removal of roots could explain 11.7% of the drop in soil microbial biomass, which was significantly higher than that of removing aboveground litter (4.9%). 

The root removal effect on microbial biomass was greater with increasing experimental time, while the effect of removing aboveground litter was even smaller in high temperature and rainfall environment. 

The removal of roots increased bacterial biomass but reduced fungal biomass, resulting in a bacteria dominated community, while the removal of above-ground litter had opposite effects on bacterial and fungal biomass. 

The researchers concluded that the removal of underground litter (roots) had a greater impact on soil microbial biomass than removing aboveground litter, and that the two litter removal treatments had different effects on microbial community structure and stability of soil organic carbon pool. One should consider the different impacts of above-and underground litter when predicting the responses of microbes and soil carbon to environmental changes and human activities, the researchers say. 

The study titled "Effects of root dominate over aboveground litter on soil microbial biomass in global forest ecosystems" has been published in Forest Ecosystems, and it was supported by the National Natural Science Foundation of China.