New progress in the contribution of root/hyphal pathways in alpine forests to soil organic carbon accumulation under nitrogen deposition in Chengdu Biological Institute

 To this end, Yin Huajun's team from the Forest Ecological Process and Regulation Project Group of the Chengdu Institute of Biology, Chinese Academy of Sciences took Picea asperata , a subalpine coniferous forest with a high degree of ECM symbiosis, as the test object, and used ingrowth tube technology to distinguish roots and hyphae effects (F.

1 right), differentiated and quantified the magnitude and direction of the contribution of the root / hyphal pathway to forest SOC accumulation under nitrogen addition ( 0 .

25 kg N ha ^-1 yr ^-1 .

On this basis, with the aid of biomarkers (long-chain fatty acids, lignin phenols and amino sugars) analysis technology, the molecular composition of SOC (plant-derived C and microbial-derived C ) under the two pathways was analyzed, and the two pathways were accurately quantified and evaluat.

The energy efficiency change of the microbial carbon pump (MCP) induced by N addition under these pathways, that is, the ratio of the N - induced microbial residue C increment to the SOC incremen.

At the same time, combined with soil microbial community structure, extracellular enzyme activity and SOC The physical - chemical stability analysis identified the potential regulatory mechanisms of the changes in SOC storage and molecular composition mediated by the two pathways of root / hyphae under nitrogen depositio.

Figure Schematic diagram of the effect of root / hyphal pathway on soil carbon - nutrients (left) and the schematic diagram of the experimental design of in situ in-growth tubes (right)

 The results show that: 1) The annual average increase of soil SOC storage under N deposition is about 271 g m ^-2 yr ^-1 , in which the hyphal pathway plays a dominant role (about 66%) in N-induced soil C accumulation, about 271 g m -2 yr -
2 times the contribution to the root pathw.

2) Compared with the root pathway, the microbial residue C increment mediated by the hyphal pathway under nitrogen addition accounted for more than 80% of the SOC increment, while this ratio was only about 54% in the root pathway, indicating that The hyphal pathway has a more efficient functioning M.

3) Nitrogen addition enhanced the fungal metabolic activity of the hyphal pathway and the binding ability of fungal residue C to soil minerals was an important reason for the efficient MCP of the hyphal pathway (F.


The above results indicated that epitaxial mycorrhizal mycelium in alpine forests played a crucial role in regulating the formation, accumulation and stability of forest SOC under the background of aggravated nitrogen deposition

From the unique perspective of "mycorrhiza", the results of this study enrich and enhance the scientific understanding of the theory of typical forest soil carbon sink effect under global change, and provide important theoretical guidance for the adaptive management of alpine forests to cope with global climate chan.

F.

2 Relative contribution of root / hyphal pathways to soil organic carbon storage ( gm ^-2 yr ^-1 ) under increased nitrogen depositio.

PLRC: plant source C; BRC: bacterial residue C; FRC: fungal residue C; UNIC: unidentified carbon component <.