In a new study, Dr. LU Xiankai and his colleagues, from South China Botanical Garden (SCBG) of the Chinese Academy of Sciences (CAS), found that plant resource inputs can lead to rapid alterations of forest soil dissolved organic matter (DOM) composition.

DOM plays a key role in forest carbon biogeochemistry by linking soil organic carbon (SOC) sequestration and water fluxes. Although changes in plant resource inputs significantly impact SOC sequestration, it remains unclear how they affect soil DOM composition, which regulates SOC sequestration capability due to its mobility and biological instability.

In 2019, Dr. LU initiated a research platform on plant resource inputs and belowground ecological processes in a primary tropical forest at Dinghushan Natural Reserve. The experiment treatments include control (no changes in both litter and root inputs), no aboveground litter (NL), double aboveground litter (DL), no roots (NR), no roots and no aboveground litter (NR +NL), and no roots and double aboveground litter (NR +DL). They found that short-term (eight-month) treatment significantly altered soil DOM’s optical properties, and the most pronounced changes were observed in the humification index and fluorescent components. In litterfall removal and no-input plots, molecular characteristic values increased greatly, such as O/C, double-bond equivalent, aromaticity index, and proportion of carboxyl- rich alicyclic molecules, while bio-labile compounds decreased. The abundance of lignin-like and tannin-like compounds was more than 20% higher in litter removal plots and in no-input plots.

"This study provide a good research base to link DOM dynamics with soil carbon sequestration capability in forest ecosystems under global changes, indicating an important implication for ecosystem carbon balance and management", said LU. 

This study, published in the journal Geoderma, was supported by the National Natural Science Foundation of China and the Key-area Research and Development Program of Guangdong Province. Link: https://doi.org/10.1016/j.geoderma.2024.117047

Figure . Changes in the spectroscopic characteristics (left panel) and biochemical components (right panel) of soil DOM under alterations of plant resource inputs in Dinghushan primary tropical forest.