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树干液流是量化植物蒸腾耗水的基本指标。本研究于2015年5—10月采用FLGS-TDP热扩散式树干液流计对辽西北半干旱区的沙地樟子松树干液流进行连续观测,同时结合林内小气候观测系统,探讨樟子松树干液流的动态变化特征及其影响因素。结果表明:树干液流速率和日累积量均为晴天>阴天>雨天,树干液流速率变化均呈“倒U”型,晴天时出现“光合午休”现象;不同月际间(5—10月),树干液流速率与月累积量为7月>6月>8月>5月>9月>10月;不同季节间,树干液流启动时间夏季比秋季早1 h左右,且树干液流速率夏季>秋季。树干液流受气象因子的影响较大,其中光合有效辐射、空气温度、饱和水汽压差(VPD)和风速与树干液流呈显著正相关,空气相对湿度则相反;土壤温度和含水量对树干液流的影响较为复杂,随时间(月际)、天气状况(阴天、晴天和雨天)和土层深度(5、10、20、40和100 cm)的变化而变化,其中,生长季期间和不同月际间(5—10月)、表层土壤温度(0~10 cm)与树干液流均呈显著正相关,深层土壤(20~100 cm)则相反;生长季前(5月)和生长季末期(10月),树干液流随土壤水分的增多而增加,生长季期间(6—9月)则相反,树干液流随土壤含水量的增加而减弱。
Trunk flow is the basic indicator of quantified transpiration of plants. In this study, from January to October in 2015, FLGS-TDP thermal diffusive sap flow meter was used to observe the sap flow of Pinus sylvestris var. Mongolica in the semiarid areas of northwestern Liaoning. In the meantime, Dynamic Characteristics of Dry Liquid Flow and Its Influencing Factors. The results showed that both the sap flow rate and daily cumulated amount were in sunny day> cloudy day> rainy day, and the changes of sap flow rate were all “inverted U” type, and “sunny photosynthesis midday break” appeared in sunny days; (May-October), the sap flow rate and monthly cumulated amount were July> June> August> May> September> October. In different seasons, the sap flow start time was about 1 h earlier than that in autumn , And the sap flow rate in summer> autumn. The trunk flow was greatly affected by the weather factors. The photosynthetically active radiation, air temperature, VPD and wind speed were significantly and positively correlated with the sap flow and the relative air humidity was the opposite. The effects of soil temperature and water content on the trunk The effects of liquid flow are more complex and vary with time (monthly), weather conditions (overcast, sunny and raining) and depth of soil (5, 10, 20, 40 and 100 cm), where during the growing season (0-10 cm) and the sap flow in different months (May-October), while the depth of soil (20-100 cm) was opposite. Before the growth season (May) and At the end of the growing season (October), the sap flow increased with increasing soil moisture, whereas during the growing season (June-September) the sap flow was weakened with increasing soil moisture.