Salinity and inundation drivers shift microbial necromass carbon distribution patterns in estuarine mangrove wetlands
Microbial necromass carbon (MNC) plays an important role in the long-term preservation of soil organic carbon (SOC) in coastal wetlands. However, the impact of increased salinity and inundation due to sea-level rise on MNC remains unclear. Here, we established a gradient experiment with three salini...
Saved in:
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-08-01
|
| Series: | Geoderma |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0016706125002514 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | Microbial necromass carbon (MNC) plays an important role in the long-term preservation of soil organic carbon (SOC) in coastal wetlands. However, the impact of increased salinity and inundation due to sea-level rise on MNC remains unclear. Here, we established a gradient experiment with three salinity levels (7.4 ‰, 15.6 ‰, 21.2 ‰) and four inundation periods (5 h/d, 7 h/d, 11 h/d, 13 h/d) across six mangrove sampling sites to investigate vertical distribution patterns of MNC and the environmental factors influencing its dynamics. Depth-resolved analyses revealed distinct MNC distribution patterns, and the topsoil (0–20 cm) exhibited considerably higher MNC concentrations (4.6–8.2 mg g−1) than the subsoil (3.0–5.4 mg g−1, 40–50 cm), whereas the proportional contribution of MNC to SOC showed opposite trends (topsoil: 22.2 %–28.1 %; subsoil: 24.3 %–36.5 %). This inverse relationship suggests differential preservation mechanisms across soil depths. Different salinity and inundation periods induced pronounced responses. Under high salinity condition (21.2 ‰), MNC concentrations decreased by 30.2 % relative to those under low salinity conditions (7.4 ‰), and MNC/SOC showed a 13.6 % reduction. Prolonged inundation (13 h/d) further worsened these effects, leading to a 28.6 % decline in MNC relative to intermittent inundation (5 h/d). In addition, fungal necromass carbon (FNC) is the main component of MNC in coastal estuary mangrove wetlands. Redundancy analyses revealed that SOC, total nitrogen (TN), soil water content (SWC) and clay had a substantial impact on MNC. Elevated salinity and inundation period were identified as the main factors hindering MNC accumulation in mangrove sediments. Our research demonstrates that MNC is a crucial component of the soil carbon pool in mangroves, contributing 27.1 % of SOC. However, high salinity and prolonged inundation severely disrupt this carbon sequestration process, thereby suppressing MNC production by nearly 30 %. Additionally, sea-level rise and saltwater intrusion lead to the decomposition of recalcitrant carbon components and the loss of existing carbon pools. |
|---|---|
| ISSN: | 1872-6259 |