Net ecosystem productivity of Panjin Phragmites australis wetland during 1971 to 2020 and its impact factors.

Coastal estuarine wetland ecosystem has strong ability for carbon (C) storage and sequestration. Accurate assessment of C sequestration and its environmental impact factors is the basis of scientific protection and mana-gement of coastal estuarine wetlands. Taking the Panjin reed (Phragmites australis) wetland as the object, we used terrestrial ecosystem model, together with Mann-Kendall mutation test, statistical analysis methods, and scenario simulation experiment, to analyze the temporal characteristics, stability, changing trend of net ecosystem production (NEP) of wetlands and the contribution rate of environmental impact factors to NEP during 1971 to 2020. The results showed that the annual average NEP of Panjin reed wetland was 415.51 g C·m-2·a-1 during 1971 to 2020, with a steady increase rate of 1.7 g C·m-2·a-1, which would still have a continuous increasing trend in the future. The annual average NEP in spring, summer, autumn, and winter was 33.95, 418.05, -18.71, and -17.78 g C·m-2·a-1, with an increase rate of 0.35, 1.26, 0.14 and -0.06 g C·m-2·a-1, respectively. In the future, NEP would show an increasing trend in both spring and summer, but a declining trend in both autumn and winter. The contribution rates of environmental impact factors to NEP of Panjin reed wetland depended on temporal scale. At the interannual scale, the contribution rate of precipitation was the highest (37.1%), followed by CO2 (28.4%), air temperature (25.1%) and photosynthetically active radiation (9.4%). Precipitation mainly affected NEP in both spring and autumn with the contribution rates of 49.5% and 38.8%, while CO2 concentration (36.9%) and air temperature (-86.7%) were dominant in summer and winter, respectively.滨海河口湿地生态系统具有很强的储碳和固碳能力,正确评估其固碳变化及其环境影响因子是滨海河口湿地科学保护与管理的基础。本研究以盘锦芦苇湿地为对象,采用陆地生态系统模型,结合Mann-Kendall突变检验法、统计分析方法和情景模拟试验,分析了1971—2020年芦苇湿地净生态系统生产力(NEP)的变化特征、稳定性、未来趋势以及环境影响因子对NEP的贡献率。结果表明: 1971—2020年盘锦芦苇湿地的年均NEP为415.51 g C·m-2·a-1,以1.7 g C·m-2·a-1的速率稳定增长,且未来仍呈持续增加趋势。NEP在春、夏、秋和冬季的多年均值分别为33.95、418.05、-18.71和-17.78 g C·m-2·a-1,增长速率分别为0.35、1.26、0.14和-0.06 g C·m-2·a-1。未来春季和夏季的NEP呈增加趋势,而秋季和冬季的NEP呈减少趋势。不同尺度下环境因子对盘锦芦苇湿地NEP的贡献率不同。年尺度下降水的贡献率最高,达37.1%,高于CO2浓度(28.4%)、气温(25.1%)和光合有效辐射(9.4%)。春季和秋季的NEP主要受降水影响,贡献率分别达49.5%和38.8%,夏季的NEP主要受CO2浓度影响(36.9%),冬季的NEP主要受气温影响(-86.7%)。.