%0 Journal Article %A Shi-Qin XU %A Xi-Bin JI %A Bo-Wen JIN %T Dynamics and responses of sap flow of typical sand binding plants Haloxylon ammodendron to environmental variables %D 2015 %R 10.17521/cjpe.2015.0085 %J Chinese Journal of Plant Ecology %P 890-900 %V 39 %N 9 %X <i>Aims</i>

Transpiration is one of important physiological activities for plants, which is regulated by many environmental variables. Our objectives were to understand the responses of sap flow density of Haloxylon ammodendron to environmental variables and simulate its diurnal change under different micrometeorological conditions.

<i>Methods</i>

Sap flow in stems of H. ammodendron was measured with stem heat balance method using commercial sap-flow gauges from May to October, 2014, in the oasis-desert ecotone, located in the middle range of Hexi Corridor, Northwestern China.

<i>Important findings</i>

Sap flow velocity of H. ammodendron exhibited a positive relationship with stem diameter, but sap flow density (Js) decreased with stem diameter. The first three axes of principal component analysis (PCA) explained 49%, 15%, 12% of variances in the environmental datasets, respectively, and vapour pressure deficit (VPD), photosynthetically active radiation (PAR), temperature in the first axes indicated the atmospheric evaporative demand. A sigmoid function could explain 86% of the variation in Js in typical sunny days, while only 65% on rainy days. It was worth noting the simulated Js using the established sigmoid function agreed well with the measurements (R2 = 0.90) if the time lags of Js to principle environmental variables were taken into consideration. Plots of 30-min Js against PAR, VPD, and evaporative demand index (EDI) revealed a counter-clockwise hysteresis for PAR, but a clockwise hysteresis for VPD and EDI, it was possibly affected by water stress and time lags of sap flow density to principle environmental variables.

%U https://www.plant-ecology.com/EN/10.17521/cjpe.2015.0085