Liu Yunjie, Zhang Hanhan, Ma Changming, Liu Bingxiang, Ding Changjun
College of Forestry, Hebei Agricultural University, Baoding, China.
The County Forestry Development Service Center, Handan, China.
Front Plant Sci. 2022 Aug 30;13:946804. doi: 10.3389/fpls.2022.946804. eCollection 2022.
This study clarified the characteristics and influencing factors of sap flow in Carr. and L., and verified the applicability of Granier's original formula for measuring the sap flow of the two species, aimed to provide a basis for the accurate assessment of tree transpiration. and were used as research objects, their sap flow was measured by the thermal dissipation probe method (TDP), together with changes in meteorological factors and soil water content. Meanwhile, the transpiration of both species was measured by the liquid level equilibrium method (LLE) to verify the applicability of Granier's original formula. We found that: (1) the sap flow velocity of and under typical sunny and cloudy conditions showed unimodal or bimodal changes, which were highly significantly correlated with meteorological factors ( < 0.01), but they were all small and poorly correlated with meteorological factors on rainy days. (2) The sap flow velocity of both species was significantly and negatively correlated ( < 0.05) with the daily change in stem and soil water content at 10-20 cm. (3) Compared to that calculated with the LLE method, the sap flows of the two species calculated by the TDP technique using Granier's original formula were seriously underestimated, with error rates of -60.96% and -63.37%, respectively. The Granier's correction formulas for and established by the LLE method were F = 0.0287 ( = 0.941) and F = 0.0145 ( = 0.904), respectively, and the combined correction formula was F = 0.0235 ( = 0.957). It was verified that the errors of sap flow calculated by the specific correction formulas for and were -6.18% and -5.86%, and those calculated by the combined correction formula were -12.76% and -2.32%, respectively. Therefore, the characteristics of the sap flow velocity of and on sunny, cloudy and rainy days were different and significantly influenced by meteorological factors. The original Granier's formula for calculating their sap flow resulted in a large error, but can be measured more accurately by constructing specific correction and combination formulas through the LLE method.
本研究阐明了石楠（Carr.）和杜英（L.）的液流特征及影响因素，验证了Granier原始公式对这两个树种液流测量的适用性，旨在为准确评估树木蒸腾作用提供依据。以石楠和杜英为研究对象，采用热消散探针法（TDP）测量其液流，并同步监测气象因子和土壤含水量的变化。同时，采用液位平衡法（LLE）测量两个树种的蒸腾量，以验证Granier原始公式的适用性。研究发现：（1）石楠和杜英在典型晴天和阴天条件下的液流速度呈单峰或双峰变化，与气象因子高度显著相关（P < 0.01），但在雨天时液流速度均较小且与气象因子相关性较差。（2）两个树种的液流速度与10 - 20 cm处树干和土壤含水量的日变化均呈显著负相关（P < 0.05）。（3）与LLE法计算结果相比，采用Granier原始公式通过TDP技术计算的两个树种的液流严重低估，误差率分别为 - 60.96%和 - 63.37%。通过LLE法建立的石楠和杜英的Granier校正公式分别为F = 0.0287 （R² = 0.941）和F = 0.0145 （R² = 净光合速率0.904），联合校正公式为F = 0.0235 （R² = 0.957）。经验证，采用石楠和杜英的特定校正公式计算的液流误差分别为 - 6.18%和 - 5.86%，采用联合校正公式计算的误差分别为 - 12.76%和 - 2.32%。因此，石楠和杜英在晴天、阴天和雨天的液流速度特征不同，且受气象因子显著影响。Granier计算其液流的原始公式误差较大，但通过LLE法构建特定校正公式和联合公式可更准确地测量。
