极端干旱区湖岸柽柳径向生长对水环境演变的响应

该文利用黑河下游内蒙古西居延海3道湖岸堤上的湖岸林柽柳树轮年表，研究了柽柳树轮生长对水环境演变的生态响应. 对3个年表进行的主成分分析结果表明，第一主成分的贡献率达到53.3％，它反映了3道湖岸堤上柽柳轮宽生长对同一环境因子的共同响应;第二主成分的贡献率达到30.7％，它反映了3道湖岸堤上柽柳轮宽生长对第一主成分以外因素的响应. 相关分析表明,第一主成分与生长季节（5—8月）湖泊水位波动呈显著正相关关系,第二主成分与区域年降水量呈显著正相关关系,与地下水位波动呈微弱负相关关系. 上述结果表明，在地下水位可以满足湖岸柽柳生长条件下，地下水位的变化对柽柳轮宽生长作用占绝对优势.反之，天然降水将对维持柽柳的基本生存具有重要的贡献. 柽柳径向生长的生态响应模式不仅体现在3道湖岸堤的空间尺度上，同样体现在同一样点年表在时间序列上的变化. 通过石羊河、黑河和塔里木河3个干旱区内陆河流域柽柳生态水位对比，认为非地带性植被——柽柳的最大生态水位差异是由于区域降水差异造成的. 

Response of radial growth of lakeshore tamarisk to changes in the water environment in extreme and arid regions

Using tree-ring chronology on samples from tamarisk,growing on beach bars at the shores of Lake West-Juyan,the terminal of the Heihe River in west China,the response of radial growth to the lake water environment has been measured and analysed by principal component analysis.The first principal component(PC1),which accounted for 53.3% of the total variance,reflects a common growth response of tree-rings,at three beach bars sites,to environmental factors.The second principle component(PC2) accounted for 30.7% of the variance and reflects tree-ring growth response at the three beach bars to other factors.Correlation analysis indicates that the relationship between PC1 and fluctuations in the lake water level during the growing season,from May to August,is statistically significant as is the relationship between PC2 and annual precipitation;PC2 seems slightly correlated with fluctuations in the groundwater level.The results show that fluctuations in the groundwater level are the major factor controlling tree-ring growth while groundwater is suitable for tree-ring growth.In contrast,precipitation is the major factor in maintaining basic growth of tamarisk. In this tree-ring chronology the response models of radial growth exhibit both spatial and temporal patterns.We are of the opinion that the difference between the maximum groundwater level and the water level in the Shiyang,Heihe and Talimu watersheds was brought about by the differences in local precipitation.