春季侧柏树干边材液流的滞后效应分析

Analysis on Sap Flow Time Lag Effect of Platycladus orientalis in Spring

研究林木耗水规律及其影响机制对干旱半干旱地区林业建设战略规划、林种布局、树种选择、林分结构配置及林地水分管理等具有重要的指导意义。利用热扩散式边材液流测定系统和自动气象站对春季侧柏边材液流速率和太阳辐射、空气温湿度等气象因子进行了为期一年的同步测定。结果表明:侧柏边材液流和太阳辐射的日变化表现出明显的峰型特征,空气温湿度的峰型特征相对不明显。侧柏边材液流速率相对于太阳辐射、空气温度和空气湿度存在明显的"滞后"效应,滞后时间分别为110 min,-70 min,-60 min。在树干液流的数值模拟中,考虑液流相对于气象因子的滞后效应可以提高模型的拟合精度,而且仅用太阳辐射一个变量模拟侧柏边材液流就能达到理想的效果。

Studies on forest water consumption and its affected mechanism are of guiding significance to forestry construction program, forest types＇ layout, tree species selection, stand structure configuration and stand water management in arid-semiarid areas. The sap flow velocity of Platycladus orientalis and meteorological factors such as solar radiation, air temperature and air moisture were synchronously measured with thermal dissipation probe systems and an automatic weather station in spring. The results showed that diurnal changes of sap flow velocity of Platycladus orientalis and solar radiation demonstrated significant peak characters, whereas peak characters of air temperature and air moisture were not obvious . The sap flow lag effect existed compared to solar radiation, air temperature and air moisture, and the lag time was 110 min, -70 min and -60 min respectively. In conclusion, with time lag effect considered, model fitting precision would be improved and sap flow velocity of Platycladus orientalis could be well simulated only with solar radiation.