Chanda Abhra, Akhand Anirban
School of Oceanographic Studies, Jadavpur University, Kolkata 700032, West Bengal, India.
Department of Ocean Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China.
Life (Basel). 2023 Aug 21;13(8):1787. doi: 10.3390/life13081787.
The Sundarban is the world's largest contiguous mangrove forest and stores around 26.62 Tg of blue carbon. The present study reviewed the factors causing a decline in its blue carbon content and poses a challenge in enhancing the carbon stock of this region. This review emphasized that recurrent tropical cyclones, soil erosion, freshwater scarcity, reduced sediment load into the delta, nutrient deficiency, salt-stress-induced changes in species composition, mangrove clearing, and anthropogenic pollution are the fundamental drivers which can potentially reduce the total blue carbon stock of this region. The southern end of the Ganges-Brahmaputra-Meghna Delta that shelters this forest has stopped its natural progradation due to inadequate sediment flow from the upper reaches. Growing population pressure from the north of the Sundarban Biosphere Reserve and severe erosion in the southern end accentuated by regional sea-level rise has left minimal options to enhance the blue carbon stock by extending the forest premises. This study collated the scholarly observations of the past decades from this region, indicating a carbon sequestration potential deterioration. By collecting the existing knowledge base, this review indicated the aspects that require immediate attention to stop this ecosystem's draining of the valuable carbon sequestered and, at the same time, enhance the carbon stock, if possible. This review provided some key recommendations that can help sustain the blue carbon stock of the Indian Sundarban. This review stressed that characterizing the spatial variability of blue carbon with more sampling points, catering to the damaged trees after tropical cyclones, estuarine rejuvenation in the upper reaches, maintaining species diversity through afforestation programs, arresting coastal erosion through increasing sediment flow, and combating marine pollution have become urgent needs of the hour. The observations synthesized in this study can be helpful for academics, policy managers, and decision makers willing to uphold the sustainability of the blue carbon stock of this crucial ecosystem.
孙德尔本斯是世界上最大的连片红树林，储存着约26.62太克的蓝碳。本研究回顾了导致其蓝碳含量下降的因素，并对增加该地区的碳储量提出了挑战。该综述强调，反复出现的热带气旋、土壤侵蚀、淡水稀缺、进入三角洲的沉积物负荷减少、养分缺乏、盐胁迫引起的物种组成变化、红树林砍伐和人为污染是可能降低该地区总蓝碳储量的根本驱动因素。庇护这片森林的恒河-布拉马普特拉-梅克纳河三角洲南端，由于上游泥沙流量不足，已停止自然延伸。孙德尔本斯生物圈保护区北部不断增长的人口压力以及区域海平面上升加剧的南端严重侵蚀，使得通过扩大森林面积来增加蓝碳储量的选择微乎其微。本研究整理了该地区过去几十年的学术观察结果，表明碳固存潜力正在恶化。通过收集现有知识库，本综述指出了需要立即关注的方面，以阻止这个生态系统排放宝贵的固碳，同时尽可能增加碳储量。本综述提供了一些有助于维持印度孙德尔本斯蓝碳储量的关键建议。该综述强调，通过增加采样点来表征蓝碳的空间变异性、应对热带气旋后受损的树木、恢复上游河口活力、通过造林计划维持物种多样性、通过增加泥沙流量阻止海岸侵蚀以及对抗海洋污染已成为当务之急。本研究综合的观察结果对那些希望维护这个关键生态系统蓝碳储量可持续性的学者、政策管理者和决策者可能会有所帮助。
