Sap flow of black locust trees in response to supplementary interception of throughfall rainfall
Black locust (Robinia pseudoacacia) plantations are widely established in the semi-arid and sub-humid areas of central China. Under the condition of global climate change, which is introducing much uncertainty of precipitation patterns, it is of special significance to investigate their responses to precipitation. Here, we investigated sap flow response to reduced rainfall. By setting waterproof panels within tree rows, about 47.5% of the precipitation has been excluded in the treated plot since April 2015. Stem sap flow has been measured since 2014 using Granier-type sensors. The results showed that differences in soil moisture gradually developed between treated and control plots. While the trees in the control plot showed higher sap flux densities than those monitored in a dry period of the previous year, the trees in the treated plot did not show significant differences from their previous measurements. The responses of sap flux densities to vapor pressure deficit were also different either between the plots or between the 2-year measurements in the control plot. The control plot showed higher responses than it did in the dry period of the previous year, whereas the treated plot maintained low responses. The results suggest that transpiration was affected by soil water conditions and was lower under the treatment. Furthermore, sap flow responses to vapor pressure deficit became insensitive following the treatment. This may imply that decreases in precipitation would cause lowered transpiration, weak response to climatic variables, and lowered productivity.
He, Q.Y., Niu, C.M., Yan, M.J. and Du, S. (2018). Sap flow of black locust trees in response to supplementary interception of throughfall rainfall. Acta Hortic. 1222, 147-154
Robinia pseudoacacia, Granier-type sensors, rainfall exclusion, sap flux density, transpiration