关键词： CO₂ 浓度升高；施氮；叶片氮；小叶章；光合作用中图分类号：S718.5;S153;X131.1 文献标识码：A文章编号：1001-9499（2025）04-0040-06

Nitrogen Application Changed the Physiological Response of Calamagrostis angustifolia to Elevated CO₂ in Sanjiang Plain Wetland

WANGJianboFUXiaoling LIU Yingnan ZHONGHaixiu** （Institute of Natural Resourcesand Ecology，Heilongjiang Academy ofSciences，HeilongjiangHarbin ）

AbstractAmbient or elevated CO₂ concentration （400，550 and 700μmol/mol ）andNapplication （O and 8gN/m²⋅y， ，low N，high N，respectively） were set up in an open-top chamber （OTC） to study the potential responses of Calamagrostis angustifolia in Sanjiang Plain wetland with different soil N availability.N application strongly increased leaf soluble protein content in different CO₂ treatments，increased leaf nitrogen content under elevated CO₂， and decreased leaf starch content and leaf C/N ratio under elevated CO₂ Elevated CO₂ concentration significantly reduced leaf nitrogen content under both CK and HN treatments.Nitrogen fertilization not only alleviated the decreaseofleaf nitrogen content，butalsomediated the increase of leaf C/N under elevated CO₂ In both CK and HN treatment， the net photosynthetic rate （Pn） in June increased under elevated CO₂， however，the increase of net photosynthetic rate was significantly higher in HN treatment than that in CK treatment.In July and August，Pn decreased with the increase of CO₂ concentration，which may be due to photosynthetic adaptation caused by long-term CO₂ fumigation. N applicationnotonlysignificantlydecreasedthe trend，butalsosignificantly increased leafnetphotosynthetic rate.Atthe end of the growing season，N fertilization significantly increased the biomass of plants growing in different CO₂ conditions，especiallyat

Key wordsNapplication; elevated CO₂ ；leafN;Calamagrostis angustifolia;photosynthesis

大气中二氧化碳浓度升高和氮沉降一直是全球变化研究中的重要问题。大量研究表明， CO₂ 浓度升高或 CO₂ 升高与氮沉降互作均会对植物产生影响[1]。根据政府间气候专门委员会（IPCC）预测，大气 CO₂ 浓度将会在21世纪中期达到 500～700μmol/mol^[2] 而全球N沉降也由1961年的 14TgN/a 增加到2000年的 68TgN/a ，预计到2050年全球N沉降量将达到 200TgN/a^[3] 。

CO₂ 是植物光合作用的原料，大气 CO₂ 浓度升高对植物的生长发育、形态结构等均会产生一定的影响[4，5]。高 CO₂ 浓度下，植物会出现不同程度的氮含量降低，因此，植物对 CO₂ 浓度升高的响应会因氮素不足而受到限制，而氮素充足会促进植物对高CO₂ 浓度的响应。

在大多天然陆地生态系统中，植物的生长发育都受到氮素营养的限制。由于天然群落具有一定的复杂性，我们要探究 CO₂ 浓度升高对野外原位生长的植物所产生的影响以及植物对其作出的响应，就有必要在野外自然条件下进行监测和研究，以期能真实地揭示植物对外界环境变化所做出的响应。三江平原是我国面积最大，分布最为集中的湿地区，是具有重要代表性和国际意义的湿地生态系统[6]。小叶章（Calamagrostis angustifolia）是禾本科拂子茅属多年生根茎型草本植物，是三江平原典型草甸、沼泽化草甸的建群植物和优势植物。本研究旨在揭示不同 CO₂ 浓度处理和不同施氮条件下，野外原位生长的小叶章气体交换、碳水化合物和生物量的响应，以期为未来湿地植物应对大气CO₂ 浓度升高的研究提供理论依据。……