冀北山地华北落叶松全生长季树干液流及蒸腾耗水特征

摘要

依据组织热平衡原理,运用热扩散探针法,于2015年3月1日-2016年3月1日对冀北山地小五台自然保护区华北落叶松的树干液流速率进行连续监测,并同步观测气温、相对湿度、净辐射、总辐射、风速等环境因子的变化,研究其树干液流特征以及与环境因子的关系.结果表明:(1)小五台地区,华北落叶松树干液流启动于4月下旬,结束于10月上旬,前后历时160多d.晴天条件下,不同月份树干液流速率日变化均呈典型的单峰曲线,且液流的启动、到达峰值、结束时间以及液流升降速率存在差异.(2)生长季华北落叶松树干液流速率峰值以7、8、9月最高,都达到0.034 kg·h1cm-1以上;日均值以7、8月最高,达到0.014 kg·h-1cm-1以上.(3)华北落叶松树干液流速率与空气温度、净辐射、总辐射、水汽压亏缺、风速呈极显著正相关,与空气湿度呈极显著负相关.环境因子对树干液流速率影响的大小顺序为:净辐射＞空气温度＞总辐射＞空气湿度＞风速. (4)整个生长季华北落叶松单株总耗水量为2 145.73±379.30 kg,其中以7、8月耗水量最大,分别为517.23±54.60和515.01±71.58 kg.%Based on tissue heat balance theory,thermal dissipation sap flow velocity probes (TDPs) were used to measure sap flow velocity of Larixprincipis-rupprechtii at Xiaowutai natural reserve in northern mountain areas of Hebei province.To research the response of stem sap flow characteristic to environmental factors,the air temperature,relative humidity,solar net radiation,total radiation,wind speed were simultaneously observed from March,2015 to March,2016.The results showed:(1) Stem sap flow of Larixprincipis-rupprechtii started in late April and ended in early October,which lasted for more than 160 days at the Xiaowutai areas.On sunny days,the daily change of stem sap flow velocity presented unimodal curve in different months.There were differences in starting,peak and ending time and changing rate of stem sap flow in different months.(2) Peak of stem sap flow velocity was highest in July,August and September in growth season,which reached more than 0.034 kg·h1cm-1.In July and August,diurnal average of stem sap flow reached to highest level that is more than 0.014 kg·h-1cm-1.(3) Stem sap flow velocity was positively correlated with air temperature,solar net radiation,total radiation,vapor pressure deficit and wind speed,whereas a negative correlation with relative humidity was detected.Influence of environmental factors to stem sap flow velocity was in the order of solar net radiation ＞ air temperature ＞ total radiation ＞ relative humidity ＞ wind speed.(4) Water consumption of individual tree was 2 145.73 ±379.30 kg in the whole growth season,maximum in July and August with 517.23 ±54.60 and 515.01 ±71.58 kg.