<正>运用Levins和Shannon-Wiener生态位宽度指数。对云南富源县光皮桦种群及其主要伴生树种的生态位进行了研究。结果表明：光皮桦生态位宽度最大，杉木、华山松次之，其他主要伴生树种的生态位宽度均较小，表明光皮桦对环境具有广泛的适应性，在群落中优势地位明显。光皮桦与杉木、华山松的生态位相似性比例较大，对资源有共享趋势；光皮桦与其他树种的生态位相似性比例较小。光皮桦群落中主要树种间的生态位重叠较低，表明主要树种间生态位分化程度较高，种间竞争关系较弱。

Iris germanica 8# and Iris tectorum were treated with different concentrations of NaC1 solutions: 0, 0.3%, 0.6% and 0.9%. The samples were analyzed for salt resistance after 4 days and 8 days of contact time. The results showed that the relative permeability of plasma membrane and the MDA content of I. germanica 8# were lower than I. tectorum. The SOD activity, proline and soluble protein contents of I. germanica 8# were much higher than I. tectorum. This research confirms that I. germanica 8# has a higher ability for salt resistance than that of I. tectorum. Low permeability and low MDA content, along with high SOD activity and high proline and soluble prolein contents are five important physiological indexes for salinity resistance in Iris L.