晋西黄土区刺槐林耗水特征

Characteristics of water consumption by Robinia pseudoacacia forest on Loess Plateau of western Shanxi Province,China

应用TDP热扩散探针技术对晋西黄土区刺槐进行了一个生长季(2011年4—10月)的野外实地定位观测,结合同步测定的大气温度、日照时数、风速等气象因子,根据相应经验公式计算了刺槐林的蒸腾耗水量和大气蒸发力,并在此基础上进行了刺槐树干液流速率与刺槐林地大气蒸发力相关性研究。结果表明:5月和8月,刺槐林地大气蒸发力和刺槐树干液流速率均具有相似的连日变化规律,夜间值均明显小于白天,晴天和雨天表现出一定的昼夜变化规律,雨天波动幅度较晴天小,阴天基本无波动。在刺槐的整个生长季(4—10月),刺槐林地大气蒸发力和刺槐树干液流流速相关性在6、7、8三个月份达到显著水平,其余月份相关性不显著,该相关性在刺槐的整个生长季呈对称性分布;刺槐林各月平均蒸腾耗水量基本呈对称分布,最小值出现在4月,最大值出现在7月,刺槐林地大气蒸发力最小值出现在10月份,4月份与其大小相当,最大值出现在6月份;刺槐林在4—10月的最大可能蒸发量是刺槐林实测蒸腾耗水量的4.45倍。

By using thermal dissipation probe（TDP） technique,a field observation was conducted on the stem sap flow of Robinia pseudoacacia forest on Loess Plateau of western Shanxi Province in the growth season（April-October）,2011.Combining with the synchronically observed meteorological factors and by using corresponding empirical formula,the transpiration water consumption and atmospheric evaporation capacity of the forest were calculated,and the correlations of the stem sap flow velocity and atmospheric evaporation capacity were studied.In May and August,the stem sap flow velocity and atmospheric evaporation capacity of the forest had the similar diurnal variation patterns in sunny and rainy days,being obviously smaller at night than at daytime,but not obvious in cloudy days.In the growth season of R.pseudoacacia,the correlation between the sap flow velocity and atmospheric evaporation capacity was significant in June,July,and August,but insignificant in other months,presenting a symmetrical distribution.The mean monthly transpiration water consumption had a symmetrical distribution during the growth season,with the minimum in April and the maximum in July.The atmospheric evaporation capacity was the minimum in October and the maximum in June,and the potential maximum atmospheric evaporation capacity during the growth season was 4.45 times of that of the measured forest transpiration water consumption.