| Autor: |
Zhang, Xinying, Dai, Guohua, Zhai, Guoqing, Yi, Wenxing, Ma, Lixiao, Huang, Zhenying, Ye, Xuehua, Ma, Wenhong, Wang, Yonghui, Zhang, Pujin, Feng, Xiaojuan |
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| Zdroj: |
Geophysical Research Letters; Nov2024, Vol. 51 Issue 22, p1-11, 11p |
| Abstrakt: |
Root‐borne microbial necromass carbon (MNC) is an under‐investigated contributor to soil organic carbon (SOC) in grasslands. Here we conduct a benchmark assessment of root‐borne MNC based on amino sugars in the fresh roots of 27 dominant species and mixed roots (including dead ones) of mixed species in Inner Mongolian grasslands. We find that mixed roots contain 9.1−62.4 mg g−1 MNC, which may contribute ∼10% of MNC in surface soils (0−10 cm) if all enters the soil without degradation. Root (and arbuscular mycorrhizal fungi; AMF) turnover rather than AMF biomass controls root‐borne MNC accumulation. Based on a microcosm decomposition experiment of mixed roots in model soils under optimal conditions (∼22°C; 60% of maximum water holding capacity), we further estimate that 43%−75% of root‐borne MNC remains after 2‐year decomposition, implying that root‐borne MNC is relatively stable. Hence, root‐borne MNC may be an overlooked potential source of soil MNC and SOC in grasslands. Plain Language Summary: The roots of most (>80%) grassland plants are colonized by endogenous microbes, in particular arbuscular mycorrhizal fungi (AMF). However, the direct contribution of root‐borne microbial necromass carbon (MNC) to grassland soil organic carbon (SOC) remains unknown. Here we conduct a benchmark quantification of root‐borne MNC based on amino sugars in the fresh roots of 27 dominant species and mixed roots (including dead ones) of mixed species in Inner Mongolian grasslands. We find that root‐borne MNC may contribute ∼10% of MNC in grassland surface soils if all transferred and preserved in soils. Root (and AMF) turnover rather than AMF biomass controls the accumulation of root‐borne MNC, such that both root‐borne MNC and its contribution to SOC are highest in the driest desert steppe with the lowest root mass owing to the rapid root turnover under dry condition. Furthermore, based on a microcosm decomposition experiment under optimal temperature and moisture conditions, we estimate that 43%−75% of root‐borne MNC remains after 2‐year decomposition, implying that root‐borne MNC is relatively stable. These findings highlight that root‐borne MNC may be an overlooked source of soil MNC and SOC in grasslands, which warrants better recognition in the heated study of microbial necromass. Key Points: Mixed roots contain 9−62 mg g−1 microbial necromass carbon (MNC) in grassland topsoil43%−75% of root‐borne MNC remained after 2‐year decomposition under optimal temperature and moisture conditionsRoot‐borne MNC supplies up to 3% of grassland soil organic carbon with root turnover unaccounted for, and rapid root turnover may enhance its contribution [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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