增温对杉木幼树不同季节叶片非结构性碳水化合物及碳氮同位素的影响

Effects of warming on leaf non-structural carbohydrates and carbon and nitrogen isotopes of Cunninghamia lanceolata saplings during different seasons

为揭示植物叶片非结构性碳水化合物(NSC)以及碳氮同位素特征对全球变暖的响应,在福建三明森林生态系统与全球变化国家野外科学观测研究站陈大观测点内开展土壤增温实验,设置对照(CT)和增温(电缆加热,+4℃)(W)两种处理,于2016年3月份开始增温,以杉木幼树为研究对象,分析杉木叶片NSC含量以及碳氮同位素的季节变化特征.结果表明:(1)增温处理显著降低春季叶片可溶性糖、淀粉、NSC含量,而其他季节两种处理间无显著性差异.(2)增温后春、冬季节叶片δ13C显著增加,各季节叶片δ15N均表现出增加趋势.(3)增温处理下,叶片δ13C、δ15N与NSC含量未表现出相关关系,而对照条件下,δ15N与δ13C、糖淀比表现为负相关关系,与淀粉表现为正相关关系.综上所述,植物在增温条件下会通过调整不同季节体内NSC含量进行渗透调节,同时改变养分循环特征,进而影响植物水分和养分利用策略维持植物的生长.未来应进一步研究长期增温背景下植物体内NSC含量以及碳氮同位素在各器官间的季节变化特征以及NSC含量与碳氮循环间的关系.(图4表2参40)

To reveal the response of non-structural carbohydrates (NSC) and carbon and nitrogen isotopes in plant leaves to global warming,we conducted soil warming experiments in the Fujian Sanming Forest Ecosystem and Global Change National Observation and Research Station of China.We designed two treatments:control (CT) and warming (W;cable heating,+4℃).Heating cables were installed 20 cm from each other at a depth of 10 cm and were heated in March 2016.In this study,Cunninghamia lanceolata saplings were used to analyze seasonal changes in leaf non-structural carbohydrates,and carbon and nitrogen isotopes.The results showed that (1) warming significantly reduced the soluble sugar,starch,and NSC content of leaves in spring but without any significant difference during other seasons.(2) Leaf δ13C increased significantly in spring and winter after warming,whereas leaf δ15N did not change significantly.(3) No significant correlation was observed between leaf δ13C,δ15N,or NSC content during the warming treatment,but a negative correlation was observed between leaf δ15N,δ13C,and sugar to starch ratio.A positive correlation between leaf δ15N and starch content was identified.In summary,when temperature increases,plants adjust the NSC content during different seasons for osmotic regulation,change the characteristics of the nutrient cycle,and alter the plant water and nutrient use strategies to maintain plant growth.In the future,we should further study the seasonal variation characteristics of NSC content and isotopes and the relationship between NSC content and the carbon and nitrogen cycles in plants under the context of long-term warming.