Liu Tingting, Chen Xuechu, Du Minghui, Sanders Christian J, Li Changda, Tang Jianwu, Yang Hualei
State Key Laboratory of Estuarine and Coastal Research, Institute of Eco-Chongming, Center for Blue Carbon Science and Technology, East China Normal University, 3663 N. Zhongshan Road, Shanghai 200062, PR China.
State Key Laboratory of Estuarine and Coastal Research, Institute of Eco-Chongming, Center for Blue Carbon Science and Technology, East China Normal University, 3663 N. Zhongshan Road, Shanghai 200062, PR China; Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, 500 Dong Chuan Road, Shanghai 200241, PR China; Yangtze Delta Estuarine Wetland Ecosystem Observation and Research Station, Ministry of Education & Shanghai Science and Technology Committee, Shanghai 202162, PR China.
Sci Total Environ. 2024 Apr 15;921:170952. doi: 10.1016/j.scitotenv.2024.170952. Epub 2024 Feb 14.
Climate change provides an opportunity for the northward expansion of mangroves, and thus, the afforestation of mangroves at higher latitude areas presents an achievable way for coastal restoration, especially where invasive species S. alterniflora needs to be clipped. However, it is unclear whether replacing S. alterniflora with northward-afforested mangroves would benefit carbon sequestration. In the study, we examined the key CO and CH exchange processes in a young (3 yr) northward-afforested wetland dominated by K. obovata. We also collected soil cores from various ages (3, 15, 30, and 60 years) to analyze the carbon storage characteristics of mangrove stands using a space-for-time substitution approach. Our findings revealed that the young northward mangroves exhibited obvious seasonal variations in net ecosystem CO exchange (NEE) and functioned as a moderate carbon sink, with an average annual NEE of -107.9 g C m yr. Additionally, the CH emissions from the northward mangroves were lower in comparison to natural mangroves, with the primary source being the soil. Furthermore, when comparing the vertical distribution of soil carbon, it became evident that both S. alterniflora and mangroves contributed to organic carbon accumulation in the upper soil layers. Our study also identified a clear correlation that the biomass and carbon stocks of mangroves increased logarithmically with age (R = 0.69, p < 0.001). Notably, both vegetation and soil carbon stocks (especially in the deeper layers) of the 15 yr northward mangroves, were markedly higher than those of S. alterniflora. This suggests that replacing S. alterniflora with northward-afforested mangroves is an effective long-term strategy for future coasts to enhance blue carbon sequestration.
气候变化为红树林向北扩张提供了契机，因此，在高纬度地区种植红树林是实现海岸恢复的可行途径，尤其是在需要清除入侵物种互花米草的地方。然而，用向北种植的红树林取代互花米草是否有利于碳固存尚不清楚。在本研究中，我们调查了以秋茄为主的年轻（3年）向北种植的湿地中关键的CO和CH交换过程。我们还采集了不同树龄（3年、15年、30年和60年）的土壤芯，采用空间换时间的方法分析红树林林分的碳储存特征。我们的研究结果表明，年轻的向北种植的红树林在生态系统净CO交换（NEE）方面表现出明显的季节变化，并且起到了中度碳汇的作用，年平均NEE为-107.9 g C m² yr⁻¹。此外，向北种植的红树林的CH排放低于天然红树林，主要来源是土壤。此外，比较土壤碳的垂直分布时，很明显互花米草和红树林都促进了上层土壤中有机碳的积累。我们的研究还发现了一个明显的相关性，即红树林的生物量和碳储量随树龄呈对数增加（R = 0.69，p < 0.001）。值得注意的是，15年树龄的向北种植的红树林的植被和土壤碳储量（尤其是深层）均明显高于互花米草。这表明用向北种植的红树林取代互花米草是未来海岸增强蓝碳固存的有效长期策略。
