陕北山杏树干茎流变化及其影响因子分析

采用热扩散式树干茎流计（TDP）于2009年5—9月对农牧交错带的常用造林树种山杏（Prunussibirica L.）树干茎流的时空动态变化及其与相关环境气象因子（温度、湿度、太阳辐射等）的关系进行了观测研究。结果结果表明：（1）山杏茎流速率日变化呈宽峰曲线,每日约7：40启动,12：00—14：00达到峰值,约18：30迅速下降,没有明显的茎流停止界限,夜间有较高的茎流存在;日树干茎流量集中在8：00—l8：30,占全天树干茎流量的60%以上。（2）在典型的晴天、阴雨天气下,山杏树干茎流的日变化差异显著,茎流速率表现为晴天高于阴雨天气。（3）山杏茎流的月变化呈现为先上升后下降的趋势。7月份平均茎流速率最大,为64.247g/h;其次是6月份,其平均值为58.139g/h;9月最小,其平均值为49.156g/h。（4）主枝与侧枝茎流日变化趋势一致,主枝流速高于侧枝;侧枝对环境变化响应更加灵敏,波动强烈,与侧枝相比,主枝茎流变化响应迟钝且有明显滞后效应。（5）不同坡位山杏的茎流速率差异显著,茎流速率大小顺序为：下坡〉中坡〉上坡。（6）山杏茎流变化受周围环境因子的影响,影响强弱大小依次为：空气温度〉饱和蒸汽压〉相对湿度〉太阳辐射〉风速〉土壤温度。

Variation of Stem Sap Flow in Prunus Sibirica L.in North Shaanxi Province

The dynamics of sap flow rates in apricot and related environmental factors in ecotone of agriculture and animal husbandry were observed using TDP sap flow measuring meter from May to September in 2009 in Wuqi County.The results showed that:(1) Abroad peak curve of diurnal sap flow change was occurred in apricot forest with the beginning of sap flow at 7:40 and the peak value at 12:00-14:00 and the quick declining at 18:30.And obvious stopping sign of the sap flow did not exist even at night.Moreover the sap flux from 8:00 to 18:30,which accounted for 60% of the sap flux of whole day,was the major part of sap flux.(2) The significant difference in the change of sap flow was detected in typical sunny and rainy day with a higher daily sap flow rate in sunny day than in rainy day.(3) The value of sap flow increased first and then decreased with time.And the highest value occurred in July with a mean value of 64.247 g/h,followed in June whose mean value was 58.139 g/h,while the lowest value of 49.156 g/h appeared in September.(4) The variation trend of sap flow in bough was similar to that in lateral branch.But compared to lateral branch,the bough had a higher sap flow velocity.The lateral branch was more sensitive to the variation of environmental factors than the bough and the response of bough to sap flow was slower than lateral branch and showed an obvious lag efffect.(5) There was significant difference in the sap flow rate of apricot among different positions.The sap flow rate in the upper side is higher than that in the middle part which is higher than lower part.(6) Environmental factors influenced the sap flow variances of apricot.The order of intensity of influence was as follows: air temperaturesaturation vapor pressurerelative humiditysolar radiationwind speedsoil temperature.