Chin J Plant Ecol ›› 2023, Vol. 47 ›› Issue (4): 571-583.DOI: 10.17521/cjpe.2022.0177

• Research Articles • Previous Articles     Next Articles

Variation of sap flow rate of Cunninghamia lanceolata and its response to environmental factors in the source area of Xinʼanjiang River

YANG Li-Lin, XING Wan-Qiu*(), WANG Wei-Guang, CAO Ming-Zhu   

  1. State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, College of Hydrology and Water Resources, Hohai University, Nanjing 210098, China
  • Received:2022-05-05 Accepted:2022-09-12 Online:2023-04-20 Published:2022-09-13
  • Contact: *(
  • Supported by:
    National Natural Science Foundation of China(51979071);Fundamental Research Funds for the Central Universities(B220202034)


Aims The variability of climatic conditions and complexity of underlying surface conditions in the humid regions of southern China have brought difficulties to the measurement and estimation of evapotranspiration. Tree transpiration is the key component of forest evapotranspiration. The monitoring and measurement of sap flow has become the main method to determine transpiration. Cunninghamia lanceolata forest as a representative vegetation in the source area of Xinʼanjiang River, is crucial to soil and water conservation and climate regulation in the area.

Methods In order to investigate the controlling mechanism of environmental factors on the change of the sap flow rate (Js) during the growing season of C. lanceolata (April to September 2020), the Js of C. lanceolata were monitored by the sap flow measurement system and environmental observations and soil water content were measured by the meteorological gradient tower in the source area.

Important findings The Js of C. lanceolatahad obvious seasonal variations with the largest in August and the lowest in May. Among the environmental factors, net solar radiation (Rn) and vapor pressure deficit (VPD) were the strongest factors correlating with Js. The results of principal component analysis indicated that the variance contribution rates of the first principal component were 59.1% and 57.9% at the hourly and daily scales, respectively. Furthermore, VPD and Rn played a major role in the first principal component and were the main environmental factors affecting the change of the sap flow rate of C. lanceolata in the study area. During the observation period, the maximum Js occurred earlier than the maximum VPD by approximately (20 ± 3) min and occurred later than the maximum Rn by approximately (100 ± 5) min. The changes in soil water content caused by rainfall in the growing season of C. lanceolata did not significantly affect the sap flow, while the sap flows under different weather conditions varied significantly: Js was higher and mainly showed a unimodal change with early start and late end in sunny days, but showed a multimodal change with late start and early end in rainy days.

Key words: the source area of Xin’anjiang River, thermal diffusion probe, sap flow rate, dominant environmental factor, time lag, soil water content