Department of Environmental Science & Engineering, SRM University-AP, Andhra Pradesh 522240, India.
Department of Environmental Science & Engineering, SRM University-AP, Andhra Pradesh 522240, India; Centre for Geospatial Technology, SRM University-AP, Andhra Pradesh 522240, India.
Sci Total Environ. 2024 Jul 1;932:173078. doi: 10.1016/j.scitotenv.2024.173078. Epub 2024 May 8.
Coastal wetland ecosystems make an important contribution to the global carbon pool, yet their extent is declining due to aquaculture-related land use changes. We conducted an extensive investigation into the carbon stock and area coverage of macrophytes in a tropical coastal Ramsar wetland, Kolleru in Andhra Pradesh, India. A total of 72 quadrats of size 1 × 1 m were laid in the wetland, 19 species of macrophytes were collected and analyzed for carbon content using a CNHS analyzer. To assess changes in the wetland macrophytes, Normalized Difference Vegetation Index (NDVI) was estimated using Landsat time series data from 1975 to 2023. The importance value index (IVI) of macrophytes scored highest for the Ipomoea aquatica (41.4) and the lowest for Ottelia alismoides (1.9). Non-metric multidimensional scaling (NMDS) significantly (r = 0.1905, p = 0.0361) revealed a clear separation of macrophytes in ordination space. ANOVA indicated highly significant (p < 0.0001) variations in the carbon content of aboveground and belowground components of macrophytes. Among the different macrophytes, the highest carbon content was found in Phragmites karka (0.6 g. g) and the lowest was recorded in Utricularia stellaris (0.2 g. g). On an average, emergents in the Kolleru wetland sequester 1525 ± 181 g C m yr, rooted floating species sequester 858 ± 101 g C m yr, submerged macrophytes sequester 480 ± 60 g C m yr, and free-floating macrophytes sequester 221 ± 90 g C m yr. Land cover mapping revealed a decrease in spread of aquatic vegetation from 225.2 km in 1975 to 100.6 km in 2023. Although macrophytes are vital carbon sinks, the wetland conversion into fishponds has resulted in a loss of 55.3 % of carbon storage. Therefore, immediate restoration of macrophyte cover is vital for the proper functioning of carbon sequestration and mitigation of climate change impacts.
滨海湿地生态系统对全球碳库做出了重要贡献，但由于水产养殖相关的土地利用变化，其面积正在减少。我们对印度安得拉邦科勒鲁的一个热带滨海拉姆萨尔湿地的大型植物碳储量和面积覆盖情况进行了广泛调查。在湿地中布置了 72 个 1×1 米的样方，采集了 19 种大型植物，并使用 CNHS 分析仪分析其碳含量。为了评估湿地大型植物的变化情况，我们使用了 1975 年至 2023 年的 Landsat 时间序列数据估算归一化差异植被指数（NDVI）。大型植物的重要值指数（IVI）最高的是空心菜（Ipomoea aquatica）（41.4），最低的是水鳖（Ottelia alismoides）（1.9）。非度量多维尺度分析（NMDS）显著（r=0.1905，p=0.0361）揭示了排序空间中大型植物的明显分离。方差分析表明，大型植物地上和地下部分的碳含量存在高度显著（p<0.0001）的变化。在不同的大型植物中，最高的碳含量出现在芦苇（Phragmites karka）（0.6 g. g）中，最低的出现在狸藻（Utricularia stellaris）（0.2 g. g）中。平均而言，科勒鲁湿地的挺水植物每年固碳 1525±181 g C m yr，根生漂浮植物每年固碳 858±101 g C m yr，沉水植物每年固碳 480±60 g C m yr，自由漂浮植物每年固碳 221±90 g C m yr。土地覆盖图显示，从 1975 年的 225.2 公里到 2023 年的 100.6 公里，水生植被的分布范围减少了。尽管大型植物是重要的碳汇，但湿地转化为鱼塘导致碳储存减少了 55.3%。因此，立即恢复大型植物覆盖对于碳封存的正常运作和缓解气候变化影响至关重要。
