10种木本植物水力结构特征春季变化规律

在北京林业大学校园内 ,选择侧柏、雪松等 10个正常管理、正常生长的乔木、灌木和藤本树种为研究对象 ,于 2 0 0 2年 3月下旬到 5月中旬 ,选择天气晴朗之日 ,测定 1年生小枝的水势和水力结构参数 .测定结果表明 ,水势日变化呈单峰型趋势 ,即清晨和晚上的水势高 ,中午水势低 ,各月份水势变化趋势一致 ,水势季节变化趋势是 3月的水势值低于 4、5月水势值 .春季水势日变化与比导率日变化呈正相关关系 ,即早晚高、上下午低的单峰型变化趋势 ,但两者的变化趋势又不完全同步 .针叶树种比导率季节变化不明显 ,阔叶乔灌木、藤本的比导率季节变化比针叶树明显 ,且变化情况基本一致 ,5月份比导率略大于 3月份

Change law of hydraulic architecture characteristics in ten woody plants in spring

Ten healthy tree species under regular management selected in Beijing Forestry University, which respectively belong to tall tree, shrub and liana. The water potential, hydraulic architecture parameters of One_year_old twigs wer e measured in sunny days from late March to mid May in 2002 The results show t hat the daily change of water potential appears unimodal curve, i.e. the water p otential is hig her in the mor ning and in the evening, and is lower in the midday. The change trend of water p otential in different months is consistent. The seasonal change trend of water p otential appears lower in March than that in April and May. There is a similar r elationship between the daily change trend of water potential and special conduc tivity in spring, i.e. the higher the water potential, the higher the special co nductivity, but this trend of change is not entirely synchronic. The seasonal ch ange of special conductivity of conifer species is not obvious, and special cond uctivity of broad_leaved trees, shrubs and liana is larger than that of conifers , likewise, the change trend appears basically consistent. Generally, special conduct ivity in May is higher than that in March.