DU Meng-Ge, Wang Shan-Ju, Fan Jun, Ge Hong-Yuan
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling 712100, Shaanxi, China.
Gansu Qilian Mountains National Nature Reserve Administration, Zhangye 734000, Gansu, China.
Ying Yong Sheng Tai Xue Bao. 2022 Apr;33(4):931-938. doi: 10.13287/j.1001-9332.202204.021.
As an important part of ecological hydrology, transpiration is the basis for analyzing forest water cycle and healthy growth, and important for forest protection and scientific management. We used thermal diffusion probes (TDP) to continuously monitor sap flow of in the Qilian Mountains from 2017 to 2018 to explore water consumption of , and analyze the main controlling factors for the growth and transpiration of spruce. The results showed that the instantaneous change of sap flow showed a single-peak curve in sunny days, a multi-peak or double-peak curve in cloudy days, and basically no obvious regularity in rainy days. The sap flow density of Qinghai spruce was consistent with the dynamics of solar radiation. The sap flow started earlier and ended later on sunny days, and lasted for 12 to 14 hours. Due to the high altitude (2700 m), low air temperature, and low vapor pressure difference (VPD) in this area, the overall sap flow density was low, with an average of (0.86±0.49) kg·d. On the hourly scale, the instantaneous rate of sap flow was significantly affected by solar radiation and VPD. On the daily scale, soil temperature and soil moisture content of the 0-40 cm layer were significantly related to sap flow density. The spruce sap flow density decreased with the decreases of solar radiation, air temperature, and VPD. In the high-altitude forest area of Qilian Mountains, lower soil and air temperature as well as lower VPD and solar radiation were the causes of low sap flow in in this area.
作为生态水文学的重要组成部分，蒸腾作用是分析森林水循环和健康生长的基础，对森林保护和科学管理具有重要意义。我们于2017年至2018年使用热扩散探针（TDP）连续监测祁连山林区青海云杉的液流，以探究其耗水量，并分析云杉生长和蒸腾的主要控制因素。结果表明，青海云杉液流的瞬时变化在晴天呈单峰曲线，阴天呈多峰或双峰曲线，雨天基本无明显规律。青海云杉的液流密度与太阳辐射动态一致。晴天液流开始早、结束晚，持续12至14小时。由于该地区海拔高（2700米）、气温低、水汽压差（VPD）小，总体液流密度较低，平均为（0.86±0.49）千克·天。在小时尺度上，液流瞬时速率受太阳辐射和VPD显著影响。在日尺度上，0至40厘米土层的土壤温度和土壤含水量与液流密度显著相关。云杉液流密度随太阳辐射、气温和VPD的降低而减小。在祁连山林区高海拔地区，较低的土壤和气温以及较低的VPD和太阳辐射是该地区青海云杉液流较低的原因。
