黄土丘陵区刺槐生长季生态需水研究

Ecological Water Requirement of Robinia Perseudoacacia in Loess Hilly Region

刺槐林的生态需水量可以理解为该林地的蒸散耗水量,受大气环境、植被生长状况与生长特性、土壤水分条件的综合影响。林木暂时凋萎含水量和生长阻滞含水量分别是能保证林木基本生存和正常生长时土壤含水量的下限,因此,相应的刺槐林地耗水量分别为平均最小生态需水量和平均适宜生态需水量,其数值通过计算林地的潜在蒸散量并利用土壤水分修正系数和林木系数进行订正获得。经计算,黄土丘陵区燕沟流域刺槐幼年林生长季(5—10月)的最小生态需水量为420.3mm,适宜生态需水量为506.7mm;刺槐青年林的最小生态需水量为602.4mm,适宜生态需水量为730.4mm。

The ecological water requirement of Robinia perseudoacacia can be expressed by the evapotranspiration of trees in growing season. It can be influenced by weather, vegetation, and soil moisture. If soil moisture is above temporary-wih or growth-retard, tree growth can be sustained, basically or normally. Therefore, soil water contents for temporary-wilt and growth-retard can be taken as the minimum ecological water requirement and the suitable ecological water requirement of Robinia perseudoacacia, respectively. They can be estimated by introducing soil factor and tree species factor to potential evapotranspiration with Penman formula. Accordingly, the ecological water requirement （May to Oct. ） for Robinia perseudoacacia in Yangou watershed is estimated. The minimum and suitable ecological water requirements of childhood Robinia perseudoacacia are 420.3 and 506.7 mm, respectively. The minimum and suitable ecological water requirements of young Robinia perseudoacacia are 602.4 and 730.4 mm, respectively.