Transpiration estimates in Pinus sylvestris var.mongolica plantation based on the radial pattern of sap flow and its influencing factors
Aims Pinus sylvestris var.mongolica is one of the key afforestation species in the semi-arid region of western Liaoning Province.Precise estimation of its transpiration is crucial for the scientific management of these plantations.Methods This study utilized multi-point TDP probes with different probe sizes to examine the radial pattern of sap flow in 30-year-old P.sylvestris var.mongolica on sandy terrain,and to explain the factors affecting transpiration.Important findings Results revealed significant differences in the radial pattern of sap flow within the plantation,which also varied across seasons.In August,the sap flow exhibited a distinct unimodal radial pattern,peaking at 15 mm depth from sapwood.However,in October,the radial pattern showed a significant difference,presenting a gradual decline from the outer sapwood towards the heartwood.Based on radial sap flow changes,the daily transpiration of 30-year-old P.sylvestris var.mongolica in August and October was estimated to be between 25.32-27.45 and 14.05-16.49 kg,respectively.The transpiration from the outer 0-20 mm of the sapwood accounted for a substantial majority of the whole tree's transpiration.Estimation of the entire P.sylvestris var.mongolica transpiration based on a single point could lead to significant errors,with the highest error reaching up to 133.22％.There was a notable correlation between sap flux densities at different depths(5,15,25 mm)out of sapwood,and a satisfactory linear fit was observed between sap flux density at various depths and weighted mean sap flux density on a sapwood area basis.Thus,a single-point estimation of individual tree transpiration can be achieved using conversion equations.The most significant effect on sap flow at different depths in P.sylvestris var.mongolica was from photosynthetically active radiation.However,the response degree of sap flow at different depths to meteorological factors were different,implying that meteorological influences on whole-tree transpiration cannot be predicted based on the impacts at a single depth.
sap flowPinus sylvestris var.mongolicaplantationradial variationtranspirationmeteorological factor
万方数据
维普
