西安市林草植被净化大气污染的时间变化及同步性研究

在长期观测自然发生状态下植被生长季相变化的基础上,提出了植被叶面指数的概念,并利用近3年大气污染数据,分析了西安市大气污染与植被叶面指数的年内时间变化,结果显示:大气污染物浓度的年内变化呈"U"字型,冬季污染物浓度较高,夏季较低;植被叶面指数的年内变化呈倒"U"字型,夏季叶面指数较大,冬季较小;大气污染浓度与植被叶面指数年内变化存在时间不同步性.在此基础上,依据相互作用模型,测定出植被大气污染物净化量,发现这种时间不匹配性严重影响植被净化大气污染生态功能的发挥,具体表现为:冬季大气污染严重,由于叶面指数低,净化量较低;夏季植被茂盛,而大气污染浓度较低,净化量亦受到影响.图4,表2,参8.

Study on Annual Changes and Synchronousness of Atmosphere Pollution Reduction by Woodland and Grassland in Xi'an

On the basis of monitoring annual change of vegetation growth in the natural conditions,the conception of vegetation leafage's index is established. With the statistical data of atmosphere pollution in Xi'an from 2003 to 2006,annual changes of atmosphere pollution and vegetation leafage's index are analyzed.The results showed that the annual change of atmosphere pollution concentration,which is higher in winner and lower in summer,presents "U" figure,the annual change of leafage's index,which is larger in summer and lower in winner,presents inverse "U" figure,and the annual changes of atmosphere pollution and vegetation leafage's index are evidently inverse synchronous.According to interactive model,atmosphere purification quantity is measured.It is discovered that because of the inverse synchronousness,the ecological function of vegetation is badly affected,that is,in winner,atmosphere pollution concentration is higher, but leafage's index is lower,which conduce to reducing purification quantity;in summer,vegetation is flourish,atmosphere pollution concentration is lower and the purification quantity is also affected.