刺槐春夏季树干液流变化规律

用热扩散式树干茎流计(TDP)于4-8月对刺槐树干液流进行连续观测,结果表明:刺槐边材液流速率日变化呈宽峰曲线,每日6:50左右启动,13:00左右达到峰值,19:30左右开始迅速下降,没有明显的液流停止界限,夜间有较高的液流存在;夏季液流每天启动的时间早于春季10min左右,达到峰值的时间早于春季1h左右,迅速下降的时间晚于春季1h左右,即夏季液流高峰维持的时间长于春季,但是夏季的峰值、日平均液流速率和液流通量小于春季;树干液流速率与直径关系不大,但日周期单木耗水量随树干直径的增大而增加,与树干直径和边材面积相关显著,相关系数分别为0.983和0.999.

Variation of Stem Sap Flow of Robinia pseudoacacia in Spring and Summer

Stem sap flow of Robinia pseudoacacia was continuously detected with the thermal dissipation probe(TDP)from April to August in 2006.Results showed that the diurnal variation of sap flow displayed a wide-peaked curve.The sap flow started to increase about at 6:50,and reached to the peak about at 13:00,then declined quickly about at 19:30.There was no obvious stopping sign of the sap flow even over night.In summer,the starting time of increase in diurnal sap flow was about 10 minutes earlier than that in spring,and the peak was reached about an hour earlier than that in spring,and the rapid-falling time was about an hour later than that in spring.The duration of the peak lasted longer in summer than that in spring,however the peak height,the sap flow and daily average sap flow were lower than those in spring.There was no significant correlation between the stem sap flow and the stem diameter,whereas there existed significant correlations between the daily water consumption and the stem diameter(r=0.983),and the sapwood area(r=0.999).