College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China; College of Life Science and Food Engineering, Huaiyin Institute of Technology, Huai'an 223003, China.
College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China; National Positioning Observation Station of Hung-tse Lake Wetland Ecosystem in Jiangsu Province, Hongze 223100, China.
Sci Total Environ. 2020 May 10;716:136996. doi: 10.1016/j.scitotenv.2020.136996. Epub 2020 Jan 28.
This study was conducted to understand how different wetland vegetation-land use types influenced the storage and stability of soil organic carbon (SOC) in surface soils. We determined the concentration and chemical composition of SOC in both density (including light fraction organic carbon (LFOC) and heavy fraction organic carbon (HFOC)) and particle size fractions (including <2 μm, 2-63 μm, 63-200 μm and 200-2000 μm) in four wetland land use types covered with different vegetation: lake-sedge, reed, willow and poplar wetlands. Results showed that the concentrations and stock of SOC and LFOC in willow and poplar wetlands were significantly higher than those in lake-sedge and reed. However, a higher proportion of alkyl-C and a lower proportion of O-alkyl-C were observed in lake-sedge and reed wetlands than in willow and poplar, suggesting that accumulated C in willow and poplar wetlands was less stable than that in lake-sedge and reed. For all particle-size fractions except the silt (2-63 μm), the SOC concentrations were highest in willow and lowest in reed wetland surface soils, while their alkyl-C/O-alkyl-C (A/O-A) and hydrophobic-C/hydrophilic-C ratios progressively decreased from lake-sedge and reed wetland surface soils to poplar and willow surface soils. Moreover, the ratios of A/O-A and hydrophobic-C/hydrophilic-C in surface soils generally decreased with increasing concentrations of SOC in particle-size fractions, with these stability indexes being lowest in the largest particle-size fraction. These results indicate that the wetland vegetation-land use types that could incorporate more C into finer particle-size fractions had a greater potential for sequestering more stable C in such wetland ecosystems. Different wetland vegetation-land use types resulted in significant changes in the concentration and chemical structure of SOC, which could affect soil C sequestration and dynamics, C cycling in wetland ecosystems. Although both willow and poplar forests could increase SOC stock, the stability of SOC in willow wetland was higher. Therefore, on balance (stock and stability) the land use of wetland for willow forest could be a more promising way for enhancing soil C sequestration in wetlands.
本研究旨在了解不同湿地植被-土地利用类型如何影响表层土壤中土壤有机碳（SOC）的储存和稳定性。我们测定了四种湿地植被覆盖下的不同土地利用类型（包括湖泊-莎草、芦苇、柳树和杨树湿地）中 SOC 的浓度和化学组成，包括密度（包括轻组有机碳（LFOC）和重组有机碳（HFOC））和颗粒大小（包括 <2μm、2-63μm、63-200μm 和 200-2000μm）。结果表明，柳树和杨树湿地中 SOC 和 LFOC 的浓度和储量明显高于湖泊-莎草和芦苇湿地。然而，在湖泊-莎草和芦苇湿地中观察到更高比例的烷基-C 和更低比例的 O-烷基-C，表明柳树和杨树湿地中积累的 C 不如湖泊-莎草和芦苇湿地中稳定。对于所有颗粒大小除粉土（2-63μm）外，柳树湿地中 SOC 的浓度最高，芦苇湿地中最低，而它们的烷基-C/O-烷基-C（A/O-A）和疏水性-C/亲水性-C 比值从湖泊-莎草和芦苇湿地表面土壤逐渐降低到杨树和柳树表面土壤。此外，表面土壤中 A/O-A 和疏水性-C/亲水性-C 的比值通常随颗粒大小分数中 SOC 浓度的增加而降低，这些稳定性指标在最大颗粒大小分数中最低。这些结果表明，能够将更多 C 纳入更细颗粒大小分数的湿地植被-土地利用类型在这些湿地生态系统中具有更大的潜力来固定更稳定的 C。不同的湿地植被-土地利用类型导致 SOC 的浓度和化学结构发生显著变化，这可能会影响土壤 C 的固存和动态变化、湿地生态系统中的 C 循环。尽管柳树和杨树都可以增加 SOC 储量，但柳树湿地中 SOC 的稳定性更高。因此，总的来说（储量和稳定性），将湿地用于柳树林的土地利用方式可能是增强湿地土壤 C 固存的更有前途的途径。
