黄土高原不同立地条件下沙棘的生产力与水分关系研究

对黄土高原丘陵沟壑区不同立地条件下的沙棘生产力与水分关系作了初步研究．结果表明。5种立地条件下的沙棘蒸腾变化趋势不尽相同．半阴坡清晨蒸腾较强烈，其它几种立地蒸腾较弱．随着太阳辐射角度的变化和不同立地土壤含水量的差异，阴坡、阳坡上午蒸腾呈下降趋势，峁顶变化较平稳．至中午12：00半阴坡蒸腾达最大值．从午后蒸腾趋势可看出，除阴坡外，其余各立地蒸腾均不同程度地下降。尤其半阴坡下降幅度最大．阳坡蒸腾速率始终处在较低的水平．沙棘蒸腾大小顺序为半阴坡>阴坡>半阳坡>峁顶>阳坡．黄土高原半干旱地区沙棘蒸腾与光照强度没有直接的相关性，与相对湿度相关性显著．不同立地条件导致了沙棘生物量的差异，阴坡生物量要显著高于半阴坡、半阳坡和峁顶．

Relationships between water and productivity of seabuckthorn (hippophae)in different habitats of the loess plateau,China

This paper deals with the relationships between water and productivity of seabuckthorn in different habitats of the Loess Plateau in north Shaanxi. The typical habitats were classified with hilltop, sunny, shady, semi-shady and semi-sunny hillside. The results showed that values of transpiration of five kinds of habitats were different, and transpiration of semi-shady was relatively stronger in the morning while others were weaker. With the variation of directions of sunshine, transpiration of shady and sunny was declining and meanwhile transpiration of hill-top was steady. transpiration of semi-shady reached the peak in 12:00. In the afternoon, these values of transpiration all reduced in different extents except seabuckthorn of shady, especially semi-shady. The mean transpiration of 5 habitats was ordered in semi-shade > shade > semi-sunny > hilltop > sunny. There were remarkable difference between diffuse resistance and transpiration, and same relationship was found between relative humidity and transpiration. But this relationship was not found between light intensity and transpiration. Different habitats had different productivities, and productivity of seabuckthorn in shade habitat was higher than those in other habitats.