冀北山地油松树干液流特征及其对环境因子的响应

Stem Sap Flow Characteristic of Pinus tabulaeformis and Its Response to Environmental Factors at Northern Mountain Areas of Hebei Province

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山自然保护区油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,研究油松树干液流对环境因子的响应。结果表明:(1)小五台地区,油松树干液流启动于4月下旬,结束于10月下旬,前后历时184d。晴天条件下,油松不同月份树干液流速率日变化均呈典型的单峰曲线。不同月份油松树干液流的启动、到达峰值、结束时间以及液流升降速率存在差异。(2)油松树干液流速率日均值变化,除4月和10月较低外,其余各月都达到0.02kg/(h·cm)以上,尤以5月和8月最高,分别达到0.028,0.027kg/(h·cm)。各月峰值变化与日均值变化基本一致。(3)油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。各环境因子对油松树干液流速率影响大小顺序为空气温度>净辐射>总辐射>空气湿度>风速。(4)油松整个生长季单株总耗水量为(2679.58±579.83)kg,以5月、8月耗水量最大,分别为(585.14±110.92)kg和(510.08±87.96)kg。

Based on tissue heat balance theory, thermal dissipation sap flow velocity probes （TDPs） were used to measure sap flow velocity of Pinus tabulaeforrnis at Xiaowutai natural reserve in northern mountain areas of Hebei province. To explore the response of stem sap flow to environmental factors, the air tempera- ture, relative humidity, solar net radiation, total radiation, and wind speed were simultaneously observed from March, 2015 to March, 2016. The results showed： （1） Stem sap flow of Pinus tabulaeformis started in late April and ended in late October, which lasted for 184 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） The diurnal average of stem sap flow velocity reached more than 0.02 kg/（h · cm） in every month except for April and October, especially higher in May and August in which it reached 0. 028 and 0. 027 kg/（h· cm）. The month- ly peak change of stem sap flow velocity was the same as diurnal average change. （3） Stem sap flow velocity was positively correlated with air temperature, solar net radiation, total radiation, vapor pressure and wind speed, whereas a negative correlation with relative humidity was observed. Influence of environmental factors to stem sap flow velocity was in the order of temperature 〉 solar net radiation 〉 total radiation relative humidity 〉 wind speed. （4） Water consumption of individual tree was （2 679.58±579.83）kg in the whole growth season, and the largest water consumption was in May and August with （585.14±110.92）kg and（510.08±87.96）kg.