科尔沁沙地樟子松人工林幼树水分生理生态特性

水分是沙地樟子松(Pinus sylvestris var. mongolica)生长最重要的生态因子,在对科尔沁沙地东南缘樟子松疏林草地土壤水分监测的同时,对13年生沙地(疏林草地)樟子松人工幼树的叶片水势(ψ)、蒸腾速率(E)、气孔导度(g)及其相应环境因子进行测定,探讨疏林草地人工樟子松幼树的水分生理生态特性.结果表明:蒸腾速率和气孔导度具有明显的日变化和季节变化规律,两者的变化趋势相似,即在生长季节樟子松蒸腾速率呈现出较明显的双峰曲线;影响其变化的主要内在因子为气孔导度,外在因子是空气湿度和气温.针叶水势在一定程度上受到降水量、土壤水分含量及树木本身生长特性的影响.樟子松针叶水势、蒸腾速率等水分生理生态特征表明,对于13年生沙地樟子松人工幼树(密度为378株/hm2),即使在年降水量较丰富的年份,疏林草地樟子松生长仍然受到一定程度的干旱胁迫.

Study on Water Physiological Properties of the Artificially-planned Saplings of Pinus sylvestris var. mongolica in the Horqin Sandland

Water supply is one of the most important limiting factors to the survival and growth of Pinus sylvestris var.mongolica growing in sandy land.In order to explore the water physiological properties of the saplings of Pinus sylvestris var.mongolica growing in sandy land over steppe,in this study some water physiological indexes,such as water potential,transpiration rate and stomatal conductance of leaves of 13-year-aged saplings of Pinus sylvestris var.mongolica were measured with Psypro Dew Point microvoltmeter(Wescor,Inc.,USA) and Li-6400P Portable Photosynthesis System(LI-COR,Inc.,USA).Moreover,soil moisture content under the artificially-planned saplings of Pinus sylvestris var.mongolica in a density of 378 saplings per hectare) in the steppe was also measured with FDR(Profile Probe PR2,U.K.).The relationship between the water physiological properties of the saplings of Pinus sylvestris var.mongolica and the environment factors are analyzed.The results reveal that the daily and seasonal variations of transpiration and stomatal conductance of the sapling leaves of Pinus sylvestris var.mongolica are significant.The curve of the transpiration of sapling leaves of Pinus sylvestris var.mongolica in growing season is in a bimodal pattern,and the transpiration is closely related to some environmental factors, such as relative humidity and temperature.Change of the stomatal conductance is the most significant factor affecting the transpiration of the sapling leaves of Pinus sylvestris var.mongolica.Water potential of the sapling leaves of Pinus sylvestris var.mongolica is affected by some environmental factors,such as precipitation and soil moisture content.Water supply for the growth of the 13year-aged saplings of Pinus sylvestris var.mongolica under current planting density is restricted by the water physiological properties of the samplings,such as water potential,transpiration rate and stomatal conductance of their leaves.