Analysis on Dynamic Change of Relative Water Content and Needle Water Conservation of Pinus sylvestris var. mongolica on Sandy Land

Morphological structure,water-retention ability of Pinus sylvestris var.mongolica,Pinus tabulaeformis,Pinus densiflora and dynamic change of relative water content(RWL)of Pinus sylvestris var.mongolica were analyzed and studied.The result shows that needle traits and structure of Pinus sylvestris var.mongolica is favored to drought-resistant,and the proportion of bound water of leaf water content is high.Leaf water conservation is stronger and initial rate of water loss is 2.5-4.1%;site condition,age class,density has no significant effect on RWL of Pinus sylvestris var.mongolica;needle RWL shows single peak change during growing season,that is,RWL is much lower in June and July,hitting the high in August and descend in Sept.and Oct.;needle RWL of 2-year-old Pinus sylvestris var.mongolica is correlated with air temperature.