摘要
红树林保护与修复是应对气候变化的重要自然解决方案(NbS),然而针对生态修复后红树林湿地沉积物有机碳储量时空演变特征及其驱动机制的研究仍存在不足。本研究在广东省海丰红树林湿地采集了1根1 m长的沉积物柱芯HF21-Man1,并以1 cm为分辨率切割,通过210 Pb同位素定年技术构建沉积物柱芯自1885~2021年的年代序列,分析基本理化指标、碳氮含量、元素比值(C/N)及其稳定同位素(δ13C、δ15N),系统解析了人工红树林沉积物有机碳储量演变规律、累积动力学特征及其碳源贡献。结果表明:1)海丰红树林湿地沉积物有机碳含量均值为16.31±2.59 g/kg,在约1950年以前人类活动较弱时期,有机碳含量较高,而在约1950年以来人类活动较强时期,有机碳含量总体下降;2)140年来湿地沉积物有机碳累积速率均值为117.11±59.04 g/(m^(2)·a),1 m内的有机碳储量为146.69 Mg/ha。有机碳累积速率历史变化呈显著上升趋势,人类活动较弱时期(约1950年以前)、种植农业发展阶段(1950~1990年)、养殖农业发展阶段(1990~2013年)、红树林种植阶段(2013~2021年)的有机碳累积速率分别为44.08 g/(m^(2)·a)、98.56 g/(m^(2)·a)、160.53 g/(m^(2)·a)和154.70 g/(m^(2)·a),其阶段性增长与围垦开发、养殖扩张等人类活动引起的沉积通量增加呈现显著正相关(R2=0.90)。红树林重建使碳累积速率提升38.85%,并增加了11.02 Mg/ha的碳储量;3)基于端元混合模型估算,沉积物有机碳源贡献依次为海洋来源(64.62%±13.15%)、陆地来源(20.77%±7.36%)和红树林来源(14.60%±6.26%)。尽管δ13C和δ15N值在种植红树林阶段呈现显著负偏(Δ=-5.27‰)和正偏(Δ=4.06‰),指示红树林来源有机物贡献逐步增强。但是当前海丰红树林湿地碳储量(较全球均值低47.98%)与累积速率(较全球均值低28.15%)仍受限于生长环境、植被重建时间较短(<30年)和植被群落结构单一等因素。本研究通过构建百年尺度的高分辨率人工红树林湿地碳累积记录,为评估红树林生态修复的固碳效益提供了实证依据,为制定和完善碳中和政策提供了重要参考,同时指出需要建立长期且全面的监测体系以准确量化植被恢复过程中的碳汇动态。
Mangrove protection and restoration are important Natural-based Solutions(NbS) for climate change. While numerous studies have evaluated the ecological benefits of mangrove restoration through comparative analyses of carbon sequestration indicators between artificial mangroves and other habitats. However, there is still a lack of research on the spatiotemporal evolution characteristics and driving mechanisms of sediment organic carbon storage of artificial mangrove wetlands. To address this knowledge gap, this study conducted a comprehensive investigation of the Haifeng mangrove wetland in Guangdong Province, China. A 1-meter-long sediment core HF21-Man1 (22.83°N, 115.22°E) was collected and sectioned on-site at 1 cm intervals. Through the application of 210Pb isotope dating technology, we established a detailed chronological framework spanning from 1885 A.D. to 2021 A.D. Furthermore, by integrating stable isotope(δ13C, δ15N) and element ratio(C/N) tracing methods, we systematically examined the evolutionary patterns, accumulation kinetics, and carbon source contributions of sediment organic carbon. The results showed that: (1) The sediment total organic carbon(TOC) content in the study area averaged 16.31±2.59 g/kg, exhibiting a significant positive correlation solely with total nitrogen content. During periods of weak human activity, TOC content remained relatively high but demonstrated a marked decline following 1950 A.D., coinciding with intensified anthropogenic disturbances. (2) The sediment organic carbon stock within the upper 1-meter sediment layer reached 146.69 Mg/ha, with 11.02 Mg/ha accumulated post-vegetation reconstruction. Since 1885 A.D., the TOC accumulation rate has shown a pronounced increasing trend, averaging 117.11±59.04 g/(m^(2)·a). Distinct accumulation rates were observed across different historical phases: 44.08 g/(m^(2)·a) during weak human activity phase(pre-1950 A.D.), 98.56 g/(m^(2)·a) during agricultural development phase(1950~1990 A.D.), 160.53 g/(m^(2)·a) during aquaculture expansion phase(1990~2013 A.D.), and 154.70 g/(m^(2)·a) during mangrove restoration phase(2013~2021 A.D.). This phased growth exhibited a strong positive correlation(R2=0.90) with increased sediment flux driven by human activities such as land reclamation and aquaculture expansion. Compared with the pre-restoration period, the TOC accumulation rate increased by 38.85 %, indicating that the enhanced carbon sequestration potential of sediments following mangrove rehabilitation. (3)Based on the δ13C constructed end member mixed model, the contribution of organic carbon sources in sediments is estimated to be from marine sources(64.62 % ±13.15 %), terrestrial sources(20.77 % ±7.36 %), and mangrove self generated sources(14.60 % ±6.26 %). During the agricultural development phase, δ13C depletion reflected increased terrestrial inputs, while δ15N enrichment indicated nutrient influx from chemical fertilizer application. The aquaculture expansion phase was characterized by δ13C enrichment, suggesting phytoplankton proliferation driven by aquaculture wastewater. During the mangrove restoration phase, significant δ13C depletion(Δ=-5.27 ‰) and δ15N enrichment(Δ=4.06 ‰) indicated a growing contribution from mangrove-derived sources. However, current carbon stock(47.98 % below the global average) and accumulation rates(28.15 % below the global average) remain constrained by growth environment, limited vegetation reconstruction duration(< 30 years), and a single vegetation community structure. In summary, this study identified the temporal dynamic changes in organic carbon storage, accumulation rate, and sources of sediment in mangrove wetlands over the past 140 years, providing reliable data support for comparative assessments of carbon storage across diverse mangrove ecosystems and scientific support based on typical cases for large-scale assessment of blue carbon storage. There are also limitations to this study, such as the limited number of research sites and short monitoring time. Future investigations should implement optimized spatial sampling strategies incorporating stratified heterogeneity sampling and long-term carbon flux monitoring. Such methodological advancements will enable comprehensive quantification of mangrove ecosystem carbon source-sink dynamics, thereby providing robust scientific underpinnings for precision ecological restoration and adaptive management of coastal wetlands.
作者
刘婷
鲍锟山
周种乐
方佳丽
高常军
LIU Ting;BAO Kunshan;ZHOU Zhongle;FANG Jiali;GAO Changjun(School of Geography,South China Normal University,Guangzhou 510631,China;School of Geography Sciences,East China Normal University,Shanghai 200241,China;Guangdong Provincial Key Laboratory of Silviculture,Protection and Utilization,Guangdong Academy of Forestry,Guangzhou 510520,China;Guangdong Haifeng Wetland Ecosystem National Research Station,Guangzhou 510520,China)
出处
《第四纪研究》
北大核心
2025年第3期752-765,共14页
Quaternary Sciences
基金
广东省基础与应用基础研究基金项目(批准号:2025A1515011992和2021A1515011670)共同资助。
关键词
红树林
蓝碳
碳累积速率
有机碳来源
生态恢复
mangrove wetland
blue carbon
carbon accumulation rate
carbon sources
ecological restoration
