环境因素对干旱-半干旱区城市银杏叶片碳同位素组成的影响

影响植物碳同位素组成的环境因素较多,在环境参数越复杂的地区控制因素则越多。城市环境相对于自然环境来说,不仅气象因素对植物同位素组成有较大的影响,而且,城市环境中人为因素如大气污染物、城市建筑等均可以影响植物的碳同位素组成。根据对兰州市校园中银杏（Ginkgo biloba）各向叶片生长期（四月至十月）的碳同位素组成分析,了解影响叶片同位素组成的环境参数特征,通过CANOCO统计分析确定各参数之间的相关性。分析表明,城市中大气污染物质量浓度的变化对植物同位素组成的影响较大（两者的相关性为r=0.550）,降水、光照、温度等也是影响植物碳同位素组成的重要因素。由于受到各个环境因素的综合影响,除有效湿度（两者的相关性为r=0.761）外,其它各种因素与叶片碳同位素组成之间的相关性并不强。而环境参数对植物叶片碳同位素组成影响主要由叶片气孔的开闭进行。

The influence of the environmental factors on carbon isotope composition of Gingko leaves in the arid-semi-arid area city

Many environmental factors had influence on the carbon isotope of plant leaves and where the environmental parameters were more complicated,the carbon isotope of leaves would be influenced by more environmental factors.Compared with natural environment,urban environment influenced carbon isotope of leaves not only by meteorological factors,but also by human factors such as air pollutants and buildings varying the effect of the light on the leaves.In this paper,the characteristics of the environmental factors influencing the carbon isotope of leaves were analized through the investigation of the carbon isotope of Gingko leaves in Lanzhou University from April to October and the relationships between factors and carbon isotope of leaves were ensured by CANOCO software.It was shown that the density of air pollutants had more influence on carbon isotope and precipitation,light and temperature were also important factors.Because of the comprehensive effect of many factors,the correlation between each envi-ronmental factor and carbon isotope was not significant except effective moisture.The influence of the environmental parameters on carbon isotope composition of plant leaves was attributed mainly by the stomatas＇ opening and closing.