Chin J Plant Ecol ›› 2023, Vol. 47 ›› Issue (2): 262-274.DOI: 10.17521/cjpe.2022.0162

• Research Articles • Previous Articles     Next Articles

Spatiotemporal dynamics of nocturnal sap flow of Populus tomentosa and environmental impact factors

FAN Yun-Xiang1, DI Nan2,*(), LIU Yang1, ZHANG Yu-Wen1, DUAN Jie1, LI Xin3, WANG Hai-Hong4, XI Ben-Ye1   

  1. 1Key Laboratory for Silviculture and Conservation of Ministry of Education, Beijing Forestry University, Beijing 100083, China
    2School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China
    3Beijing Sinton Technology, Beijing 100085, China
    4Liangshui People’s Government, Liaocheng, Shandong 252037, China
  • Received:2022-04-25 Accepted:2022-09-05 Online:2023-02-20 Published:2022-09-20
  • Contact: *(
  • Supported by:
    National Natural Science Foundation of China(32001304);National Natural Science Foundation of China(32171763);Natural Science Foundation of Nei Mongol(2020BS03002)


Aims In order to better understand the mechanisms of nocturnal water activity in tree stems, this paper explores the spatiotemporal dynamics of nocturnal sap flow and stem water filling in typical poplar plantations in the North China Plain and environmental influencing factors.

Methods Taking rainfed Populus tomentosa as the research object, the thermal diffusion method was used to continuously monitor the sap flow rate at different heights of stem in different growing periods. Soil water content and meteorological factors were measured simultaneously. Dynamics of nocturnal sap flow at different heights and its correlations with environmental factors were compared.

Important findings Before the rainy season, the ratio of nocturnal sap flow to daily sap flow at 0.35 and 1.30 m of the stem was significantly higher than that after the rainy season, while the ratio at 7.00 m increased by 49% after the rainy season. Nocturnal sap flow rate at different heights of the stem showed a high synchronization before the rainy season, and decreased with the increase of stem height. After the rainy season, the main water resource of nocturnal water use changed from root water uptake to stored water in stem base, which leading to 66% decrease of nocturnal sap flow at stem base. Meanwhile, the spatial characteristics of nocturnal sap flow at different heights also varied in different periods. After the rainy season, stem water refilling mainly occurred in 4.00-7.00 m stem segment with mean daily water refilling amount of 4.16 L, while the refilling amount in 1.30-4.00 m stem segment was much lower than others, possibly due to its primary function of water transport. Before the rainy season, vapor pressure deficit, air temperature and soil water content at 3 m depth were significantly correlated with nocturnal sap flow rate at different heights, but this relation was obviously weakened after the rainy season. And the correlations between the environmental impact factors and nocturnal sap flow were different at each height. This study finds the spatiotemporal variations of nocturnal sap flow and stem water refilling, which provide scientific support for optimizing diurnal water cycle and motion process simulation of poplar plantation in North China Plain.

Key words: poplar plantation, nocturnal sap flow, stem height, stem water refilling