黄土高原主要造林树种苗木蒸腾耗水特性

A Study on Transpiration Characteristics of Seedlings for Forestation in the Loess Plateau

选择34种乔木、灌木、果树树种,通过水分控制使苗木受到不同程度的水分胁迫,以分析苗木的蒸腾强度、气孔大小、叶水势、饱和亏缺与太阳总辐射、大气相对湿度、气温、风速、土壤含水量及叶面积等因素之间的关系。结果表明,侧柏对水分胁迫反应最为敏感,水分胁迫时,能迅速调整气孔开度以增加气孔阻力减少水分蒸腾,是其具有较强抗旱能力的重要生理基础;山杏、白榆有较大的临界饱和亏缺和较低的相对含水量,具较强的耐旱能力;当土壤含水量在6%以上时,土壤含水量与苗木蒸腾速率的关系密切,当土壤含水量低于6%时蒸腾速率与土壤含水量关系不密切;不同树种的蒸腾速率对气温、大气湿度、太阳辐射强度等环境因素的反应不同,可以选择关系密切的因子作为不同苗木蒸腾速率预测的指标。在干旱半干旱地区了解苗木蒸腾速率与土壤水分等环境因素的关系,可指导选择立地条件类型、墒情及把握造林时机,提高造林成活率。

This paper mainly analyzed the transpiration characteristics of some trees for forestation in the Loess Plateau.34 kinds of arbors,brushes and fruit trees were determined as trial species,by means of artificial control watering soil water content gradually declined from field capacity to wilting point,while transpiration rates,stomtal sizes,leaf potential,saturated deficit,gross radiation,air relative humidity,air temperature,soil water content and leave area and so on were observed,moreover the relation of transpiration rates of various seedlings to these factors was analyzed.The results show that Chinese arborvitae(Piatycladus orientalis) responds the most sensitive for water stress and can quickly adjust its stomtal open degree to increase stomatal resistance to decrease transpiration rate.This is important physiology foundation that it has ability of strong drought resistance.The apricot(Prunus sibirica) and elm(Ulmus pumila) have higher critical saturated deficit and lower relative water content,therefore have stronger ability of bearing drought.That leave water potential of some trees with a sensitive reaction to transpiration rate can be used as the main factor that predicts transpiration rate.At more than 6% soil water content,the soil water content has a close relation with the transpiration rates of the seedlings,but does not has closely the relation at less than 6% soil water content.Transpiration rates of different tree species react to different environmental factors including atmosphere temperature,atmosphere humidity and gross radiation,so we can choose the factors of close relation with the transpiration rates of different seedlings so as to predict their transpiration rates.It is very important to increase the survival rate of forestation through site selection and rational utilization of soil moisture as to catch hold of chance of forestation at arid and semiarid regions on the basis of the relation ship between the transpiration rates of the seedlings and environmental factors like soil water content.