不同年龄黄山松蒸腾速率及水分利用效率的比较研究

采用Li-6400便携式光合分析仪,研究不同年龄阶段的黄山松在不同季节的蒸腾及水分生理生态的变化.结果表明,3个年龄段黄山松1年生针叶的时蒸腾强度具有明显的日变化,均呈明显的双峰曲线,但是峰值出现时间不同;幼龄阶段的时蒸腾速率与时气孔导度的日变化趋势的基本相似,而中龄和中幼龄黄山松,其时均蒸腾速率与气孔导度的变化趋势具有明显的差异,说明幼龄黄山松受气孔的限制较明显;蒸腾速率日均值的季节变化3个年龄段黄山松均为夏季的蒸腾速率较高;各年龄段黄山松的水分利用效率变化曲线均为双峰型,年平均水分利用效率的排序为中幼龄(5.062)＞幼龄(3.383)＞中龄(3.011),中幼龄黄山松具有较高水分利用效率表明其能更好地适应干旱环境;通过季节均值比较,发现夏季黄山松具有较高的水分利用效率,是其能生长在土壤浅薄甚至岩缝中的一个主要原因之一.

Comparative studies on transpiration speed and water use efficiency for different age stages of Pinus taiwanensis

The transpiration and water physio-ecologic characteristics of needles of Pinus taiwanensis in different age stages were measured in field on typical sunny days at different seasons by using Li-6400 photosynthetic apparatus and the measured trees were selected in a natural community at 1 400 m altitude of Huangshan Mountain.The effect factors(stomata conduction,CO2 concentration in cell clearance photosynthetic active radiance,air temperature,relative humidity,etc.)were determined as well.The results were as follows:The diurnal variation of average transpiration rate for one-year-old needles of different age stages for Pinus taiwanensis all show obvious double curves,and the same thread of transpiration rate and stomata conduction is observed at juvenile stage.The seasonal variation of average transpiration speed of Pinus taiwanensis shows that it is higher in summer than that in any other seasons.The water use efficiency curves are also double peaked,and shows significant differences in different age stages of the tree species as the order of young to middle age(5.062>juvenile(3.383)>middle age(3.011).