黄河三角洲滨海湿地退化和恢复对芦苇光合特征的影响

Changes in Photosynthetic Characteristics of Phragmites australis during Wetland Degradation and Restoration in the Yellow River Delta

湿地在全球生态系统碳循环过程中发挥着重要作用。探究了黄河三角洲滨海湿地在退化恢复过程中芦苇净光合速率等参数的变化,及影响芦苇净光合速率的土壤和植物因素。恢复的滨海湿地表层土壤含水量和氮含量显著增加,土壤电导率显著降低,表明滨海湿地恢复有利于土壤水盐条件和氮营养的改善。与退化湿地相比,恢复湿地显著提高了芦苇叶片的生理性状,包括净光合速率、气孔导度、胞间CO 2浓度、蒸腾速率以及水分利用效率。在滨海湿地退化和恢复过程中,芦苇的净光合速率正相关于土壤含水量、总氮以及叶片其他指标,而负相关于土壤电导率,表明滨海湿地恢复导致的水盐条件和营养改善促进了芦苇的光合作用,进而导致地上生物量碳固持的增加。本研究通过探究滨海湿地动态变化对植物光合作用的影响,为提高滨海湿地生态系统碳固持提供了理论参考。

Wetlands play an important role in global ecosystem carbon cycle.The changes in photosynthetic rate and physiological characteristics of Phragmites australis and the factors affecting photosynthetic rate to detect soil and plant factors during wetland degradation and restoration in the Yellow River Delta are studied.The results show that wetland restoration significantly increases surface soil water content and nitrogen content,but decreases soil electrical conductivity.That indicates that wetland restoration is beneficial to the improvement of soil water and salt conditions,and nitrogen.Compared with degraded wetlands,the restored wetland improves greatly the physiological characteristics of Phragmites australis,including stomatal conductance,intercellular CO 2 concentration,transpiration rate and water use efficiency.In addition,the photosynthetic rate in restored wetlands is significantly higher than that in degraded wetlands.In restored-degraded wetlands,photosynthetic rate is positively related to soil water content,nitrogen,and leaf physiological characteristics,and negatively related to soil electrical conductivity.These suggest that wetland restoration results in the increase in water,nutrition,and improving plant physiological characteristics promoted photosynthesis,further enhancing plant carbon fixation.This research provides a theoretical basis for improving the carbon sequestration of wetland ecosystems by exploring the effects of dynamic wetlands on plant photosynthesis.