土壤温度对油松树干液流启动与停止的影响

利用TDP (thermal dissipation probe)技术, 对九寨沟次生优势树种油松进行连续观测和初步研究。在2013—2015 年间, 利用土壤温度传感器采集其树下3, 10, 20, 30, 40和50 cm共6个深度的土壤温度数据, 分析温度与树干液流强度的关系。结果表明, 早春季节的3 cm浅层地表土壤温度和气温相比深层土壤对树干液流强度的影响更显著(相关系数为0.852)。对不同土层温度与树干液流密度进行相关性分析, 得到油松根系的最适温度为4.0~7.9℃。土壤温度通过对早春土壤水分要素的控制影响林下供水环境, 从而显著地影响蒸散发量。随着土壤温度升高, 油松在 3~4月间启动树干液流, 加剧九寨沟早春径流的衰竭。

Soil Temperature Triggers Sap Flow Onset and Offset of Pinus tabulaeformis

TDP (thermal dissipation probe) technology was used for continuous observation and preliminary studyof the secondary dominant tree species Pinus tabulaeformis in Jiuzhai Valley. A temperature sensor was used tocollect soil temperature gradients from 2013 to 2015 with 6 depth gradients at 3, 10, 20, 30, 40, and 50 cm belowthe tree. The analysis showed that the temperature of surface soil in the shallow 3 cm soil layer in early spring hada stronger influence on the sap flow intensity than the deep soil temperature and air temperature (correlationcoefficient was 0.852). The temperature gradient analysis reported that the optimum temperature for the rootsystem was 4.0–7.9°C. With the increase of soil temperature, the characteristics of sap flow initiated by Pinustabulaeformis in March and April would exacerbate the decrease of early spring runoff in Jiuzhai Valley.