黄土丘陵沟壑区乔灌木植物系数计算与适应性评价

Plant coefficients calculation and adaptability evaluation of arbors and shrubs in the gully-hilly region of Loess Plateau

利用长期定位试验资料,研究了黄土高原丘陵沟壑区乔木和灌木植物系数的计算方法,比较了两种代表性乔木(榆树和小叶杨)和两种代表性灌木(柠条和沙棘)的实际蒸散量和生育期土壤平均含水量的差异,分析了土壤含水量变化对植物根系吸水和土壤水分有效性的影响。结果发现:该地区灌木的实际蒸散量小于乔木,但同类植物的实际蒸散量没有显著差异;土壤含水量柠条最高,沙棘最低;榆树植物系数最小,柠条其次,沙棘最大,但榆树和小叶杨的土壤水分有效性高,耗水量大,所以灌木较适于该区生长。

Using the data getting from long-term experiments in situ, the calculating method of plant coefficients for arbors and shrubs in gully-hilly region of the Loess Plateau was studied in this paper, the actual evapotranspirations and mean soil water contents during the growing season for two representative arbors （Ulmaceae propinque and Populus simonii） and two representative shrubs （Caraganna korshinskii and Hippophae rhamnoides） were compared, and the impacts of soil water content fluctuations on plant roots absorbing soil water and soil water availability were analyzed. The results showed that, in this experimental region, the actual evapotranspirations of shrubs are less than that of arbors while there are no obvious differences between the same plant types. The plant coefficient of Ulmaceae propinque was the minimum among the studied plants, Caraganna korshinskii＇ s was the second and Hippophae rhamnoides＇s was the maximum. The soil water availability to the four plants had no notable distinction. But both the plant eoefficients and soil water restriction should be considered in calculation of vegetation ecological water requirement and selection of drought-resistant plant variety in arid area.