<正>应用PEG处理人工模拟干旱胁迫环境条件，采用完全随机试验设计，在人工气候室研究了8个品种类型楸树1年生扦插苗在4种不同水分胁迫CK、4％、8％和12％下的光合特性。结果表明：水分胁迫下各品种类型楸树的净光合速率、蒸腾速率、气孔导度、胞间CO2浓度、Fv/Fm和Fv’/Fm’均降低。周2、光叶、梓树和南阳的净光合速率下降由气孔导度引起，而楸树、圆长、‘豫1’和金丝则由非气孔导度因素即叶肉细胞光合能力下降引起。综合表明，南阳、光叶、周2和金丝抗旱性稍强，其余4品种稍差。

Species diversity and stability of Abies chensiensis communities in Shiren Mountains nature reserve was studied in this paper. A set of data total 20 plots were used. The results showed that the differences of the richness indices, diversity indices and evenness indices among different communities were great. The diversity indices and richness indices of the plant communities were obviously affected by the type and structure of the communities. The more complicated of the structure, the bigger of the diversity indices and richness indices and the smaller evenness indices included. There was a greater variation in species diversity among different life form. However, It was found that this variation was not always statistically significant. The results of community stability calculated by improved M. Godron method were very low. Furthermore, there is not a clear relation between the stability and diversity of the communities. This showed that the five types communities were all in the process of succession in various degree. This study is important to protect A. chensiensis community in Shiren Mountains nature reserve.