滨海盐碱地不同衰退程度刺槐树干液流规律

以滨海盐碱地31 a衰退刺槐为研究对象，采用TDP树干液流测定系统测定树干边材液流变化规律，同时进行全自动微型气象站全天候检测林分气象和土壤生态环境因子。结果表明:衰退树木同方位同高度液流速率降低，高度愈大下降愈快，树木衰退与液流速率呈显著相关。正常树体液流速率日变化呈宽峰曲线，随着衰退程度的增加逐渐变为窄峰，树体液流启动时间晚，开始迅速，下降时间早；正常树体1.5 m处液流启动时间在每天7:00左右，12:30左右出现峰值，19:00左右开始迅速下降，中等衰退树体在7:30左右启动，13:30左右出现峰值，18:30左右迅速下降，严重衰退树体在9:30左右启动，12:00左右出现峰值，17:30左右迅速下降，随高度增加，启动时间、峰值出现时间和下降时间提前。北侧液流速率显著高于南侧，随着衰退程度增加，南北侧液流速率相差减小。健康木不同高度液流速率6 m>4 m>1.5 m，随着衰退程度增加，6 m和4 m液流速率减小，不同高度速率差异变小。南北方位液流速率相差显著，北侧显著大于南侧。

A Study on Variation of Stem Sap Flow of Declined Robinia pseudoacacia in Costal Saline Soil

Taking the 31 a black locust growing in the coastal saline-alkali area as research objects,variations of stem sap flow were measured by TDP (thermal dissipation sap flow velocity probe).Meanwhile,meteorological and soil ecological and environmental factors were measured by the automatic micro-weather station.The sap flow velocity of declined black locust at the same direction and height decreased,the higher the tree height,the faster the decrement.There were significant correlations between declined black locust and sap flow velocity.The daily variation of normal black locust sap flow velocity could be described with a broad peak.But with the increase of the declining degree,the curve turn to be a narrow peak,and the sap flow started later,then decreased rapidly.The sap flow of normal black locust at 1.5 m started to increase at about 7:00,and reached to the peak value at about 12:30,then decreased quickly at about 19:00.The sap flow of black locust with mediate decline degree started to increase at about 7:30,and reached to the peak value at about 13:30,then decreased quickly at about 19:00.The sap flow of the trees close to death started to increase at about 9:30,and reached to the peak value at about 12:00,then decreased quickly at about 17:30.With the increase of the tree height,starting time,reaching peak time,and decreased time were advanced.The sap flow in the north side was significant higher than in the south side,with the increase of the declining degree,the value of difference of the sap flow between two sides decreased.The sap flow of different heights was in the order of 6 >4 >1.5 m,with the increase of the declining degree,the sap flow of 6 m and 4 m decreased.There were significant differences between the sap flow in two sides,and the sap flow in the north side was significant higher than in the south side.