小钻杨树干液流特征及其与环境因子的关系

Characters of Sap Flow of Populus ×xiaozhuanica and Its Relations with Environment Factors

利用SF200茎流仪监测小钻杨树干液流的运移规律表明,整个生长季各月最大日平均液流速率为7月>8月>6月>9月>5月>10月>4月。液流速率的日变化曲线5、7、8、9月为双峰型,4、6、10月为单峰型,5月为峰型过渡阶段。夜间仍维持较低液流速率。阴雨天里液流启动较晚,停止较早,变化缓慢,在上升或下降的过程中发生波动现象。树冠东南侧液流速率大,西北侧液流速率小。不同径向深度各位点液流速率不同,液流速率随径深增加而增大,最高液流位点在20mm处,15和10mm次之,5mm处最小。土壤含水量与液流速率呈良好的对数关系,光照强度和空气温度与液流呈正相关,空气湿度与液流呈负相关,风速与液流关系复杂。通过多元线性回归,得出气象因子与液流速率呈极显著相关,相关系数均在0.795以上。空气温度和光照强度是影响液流速率最主要的因素。

Using SF200 to measure sap flow of Populus ×xiaozhuanica,it was resulted that the supreme daily average sap velocity in whole period of growth was JulyAugust June SeptemberMay OctoberApril.Daily variety of sap velocity was ＂double peak style＂ in July,August,September and ＂single peak style＂ in April,June,October,and transitional in May.There was little sap flow at night.Compared with sunny day,the flow started later,and stopped earlier,changed more slowly on cloudy and rainy day.It flucturated when ascending or descenging.The sap velocity was bigger in south and east crown than in north and west.It changed with the depth of diameter.The highest velocity was at 20 mm.It was lower at 15 mm,10 mm and the lowest at 5 mm.The relationship between sap velocity and soil water content was Logarithmic.It took on positive correlation between sap velocity and Li and Ta while it was negative correlation and RH.The relationship between sap velocity and wind velocity was complex.Though multiple regression analysis,it was showed that the correlation between sap velocity and Meteorological Factors was highly significant and its coefficient of correlation was more than 0.795.Ta and Li were the most principal factors which affected sap velocity.