Linking microbial necromass carbon to soil organic carbon: seasonal and elevational patterns and potential drivers in the mountain forest ecosystems of Southwest China

doi:10.1093/jpe/rtaf119

J Plant Ecol ›› Advance articles DOI:10.1093/jpe/rtaf119

Linking microbial necromass carbon to soil organic carbon: seasonal and elevational patterns and potential drivers in the mountain forest ecosystems of Southwest China

Dandan Zhang^a, Jinsheng Li^a*, Zhen Zhang^a, Xiaoli Cheng^b

^aSchool of Resources and Environment, Anhui Agricultural University, Hefei, 230036, P.R. China.
^bKey Laboratory of Soil Ecology and Health in Universities of Yunnan Province, School of Ecology and Environmental Sciences, Yunnan University, Kunming 650500, P.R. China.

^*Corresponding author: Dr. Li Jinsheng Email: l628js@126.com
School of Resources and Environment, Anhui Agricultural University, Hefei, 230036, P.R. China.

Online:2025-07-23 Published:2025-07-23
Supported by:
This research was financially supported by the National Natural Science Foundation of China (32401423, 32401424) and China Postdoctoral Science Foundation (2023M730015).

微生物残体碳与土壤有机碳的关联：中国西南山地森林生态系统中的季节性、海拔分布格局及其潜在驱动因素

Abstract

Abstract: Microbial necromass carbon (MNC) contributes largely to soil organic C (SOC) pool in terrestrial ecosystems. However, the pattern and underlying mechanisms of MNC and their contribution to SOC along elevational gradients are controversial due to montane ecosystems subject to environmental change. Here, in this study, we investigated the seasonal variation of MNC, its contribution to SOC, the necromass accumulation coefficient (NAC), and the influencing factors across different elevations in the mountain forests ecosystem of Southwest China. Soil microbial biomass rather than MNC showed seasonal variations, this decoupling pattern was mainly attributed to higher soil extracellular enzymes (i.e., N-hydrolyzing enzyme) and C:N ratio, which accelerated the decomposition of MNC especially bacteria necromass C (BNC) during the humid and warm wet season. In contrast, the drought and cold conditions in dry season inhibited microbial activities and conversion to MNC. During the dry season, the MNC and MNC/SOC exhibited hump-shaped pattern along elevational gradients. The fungal necromass C (FNC) was positive with fungal biomass, indicating that living biomass may have a greater influence on the accumulation of FNC than BNC. On average, MNC constituted about 15% of SOC, with the contribution from FNC (11.91%) surpassing that from BNC (3.09%). The joint effects of soil pH and clay composition significantly influenced MNC dynamics along elevational gradients. Thus, our findings demonstrated that the rapid decomposition of BNC is the main way of MNC loss in wet season in the mountain forests ecosystem and further highlighted the importance of microbial traits in MNC accumulation.

Key words: Microbial necromass, Montane ecosystems, Soil organic carbon dynamics, Enzyme activities, Alpine Forest.

摘要：
微生物残体碳(MNC)是陆地生态系统中土壤有机碳(SOC)库的重要组成部分，且在其中发挥着显著作用。然而，由于山区生态系统易受环境变化影响，沿海拔梯度的MNC分布格局及其对SOC的贡献及潜在机制仍存在争议。为此，本研究在中国西南地区的山地森林生态系统中，系统调查了MNC的季节变化、其对SOC的贡献、残体积累系数(NAC)及其影响因素。研究结果表明，土壤微生物生物量而非MNC表现出显著的季节性变化，这种解耦格局主要归因于较高的土壤胞外酶活性(即氮水解酶)和较大的碳氮比，这些因素在潮湿温暖的湿季加速了MNC，特别是细菌残体碳(BNC)的分解。相比之下，干旱寒冷的旱季条件抑制了微生物的活性及其向MNC的转化。在旱季，MNC及其在SOC中的比例沿海拔梯度呈现出驼峰型分布模式。真菌残体碳(FNC)与真菌生物量呈显著正相关，表明存活生物量对FNC的积累影响可能大于对BNC的影响。平均而言，MNC约占SOC的15%，其中FNC (11.91%)的贡献显著高于BNC (3.09%)。土壤pH与黏粒含量的联合作用在很大程度上影响了沿海拔梯度的MNC动态。上述研究揭示了BNC在湿季快速分解是MNC损失的主要途径，并进一步强调了微生物性状在MNC积累中的重要性。

关键词: 微生物残体, 山地生态系统, 土壤有机碳动态, 酶活性, 高山森林

Dandan Zhang, Jinsheng Li, Zhen Zhang, Xiaoli Cheng. Linking microbial necromass carbon to soil organic carbon: seasonal and elevational patterns and potential drivers in the mountain forest ecosystems of Southwest China[J]. J Plant Ecol, DOI: 10.1093/jpe/rtaf119.