祁连圆柏和青海云杉叶稳定氮同位素变化及其与环境因子的关系

δ15N Variations in Leaves and the Relation to Environmental Factors of Sabina przewalskii and Picea crassifolia

植物氮同位素值(δ15N)被广泛用来解析生态梯度上氮循环的变化模式,其也是反映一个种群生境条件的重要指标.然而,δ15N与环境和气象因子的关系仍然存在争议.选择青藏高原东北部生态脆弱区生长的祁连圆柏(Sabina przewalskii)和青海云杉(Picea crassifolia)为对象,测定不同地区生长的两种植物叶片δ15N,探索二者的变化特征及其与环境因子的关系.研究结果表明,青海云杉叶δ15N的变化幅度明显大于祁连圆柏,二者的变异系数分别为132.16%和44.63%.祁连圆柏和青海云杉叶δ15N存在正相关关系,且年均气温与两种树叶δ15N均呈正相关;海拔和年均降雨量与祁连圆柏叶δ15N呈正相关,与青海云杉叶δ15N呈负相关;比较δ15N与年均气温和年均降雨量相关系数,反映出青海云杉对环境因子的依赖程度大于祁连圆柏.由此可见,种间差异是影响植物δ15N变化及其与环境关系的重要因素,这可归因于局地环境差异与植物的互馈反应.

Theδ15N of plant has been used to explain the variable model of nitrogen cycle in ecological gradient,and it is an important factor to reflect the habitat of a plant community.However,the relationships betweenδ15N and the environment and climatic factors have been argued.Sabina przewalskii and Picea crassifolia of ecological vulnerable zone in Northeast of Qinghai-Tibet plateau are selected to determine the value ofδ15N in their leaves,and explore the variable characteristics and their relationship with environmental factors.The results show that theδ15N variation of Picea crassifolia is higher than that of Sabina przewalskii,and the coefficient is 132.16%and 44.63%.There is a positive relation between theδ15N values of Sabina przewalskii and Picea crassifolia,and a positive relation between theδ15N value and the annual average temperature.Elevation and annual average precipitation is positively related to theδ15N of Sabina przewalskii,and negatively related to theδ15N of Picea crassifolia.The comparison betweenδ15N and annual average temperature and annual average precipitation shows that the dependence on environment in Picea crassifoliais is higher than that of Sabina przewalskii.Therefore,interspecies difference is an important factor that affects the variation ofδ15N and environmental factors.