对东方水韭(Isoëtes orientalis H. Liu et Q. F. Wang) 2 个自然样地(浙江松阳叔婆湾和小烂湖)生境土壤主要营养成分含量进行了比较分析,并对叔婆湾样地水体pH 值进行了测定,在此基础上,对导致东方水韭濒危的土壤及水体因素进行了讨论。结果显示:东方水韭叔婆湾样地的土壤有机质、总氮、速效磷、速效钾和总铁离子(包括Fe³⁺和Fe²⁺ )含量分别为102. 7 g·kg^-1 、3. 1 g·kg^-1 、18. 1 μg·g^-1 、15. 0 μg·g^-1 和221. 6 μg·g^-1 ;小烂湖样地土壤中上述营养成分的含量分别为122. 8 g·kg^-1 、4. 8 g·kg^-1 、13. 7 μg·g^-1 、7. 1 μg·g^-1 和240. 0 μg·g^-1 。小烂湖样地土壤中有机质、总氮和速效钾含量显著或极显著高于叔婆湾样地,2 个样地间速效磷和总铁离子含量差异不显著, 但2 个样地土壤中速效钾含量极低、总铁离子含量丰富。叔婆湾样地中上、中、下游水体的pH 值分别为pH 6. 35、pH 6. 53 和pH 6. 49,略呈中性。分析结果表明,东方水韭2 个自然样地的土壤均为有机质、总氮、速效磷以及总铁离子含量较为丰富且速效钾含量较低的土壤类型,土壤中速效钾极度缺乏和水体中性化很可能是限制东方水韭种群发展的重要环境因素

The content of main nutritional components in soil of natural habitat of two plots (Shupowan and Xiaolanhu in Songyang of Zhejiang Province) of Isoëtes orientalis H. Liu et Q. F. Wang was comparatively analyzed, and the pH value of water in plot of Shupowan was determined. On this basis, the factors of soil and water led to I. orientalis endangered were discussed. The results show that contents of organic matter, total nitrogen, available phosphorus, available potassium and total iron ions (including Fe³⁺ and Fe²⁺) in soil of Shupowan are 102. 7 g·kg^-1, 3. 1 g·kg^-1, 18. 1 μg·g^-1, 15. 0 μg·g^-1 and 221. 6 μg·g^-1, respectively, and those in soil of Xiaolanhu are 122. 8 g·kg^-1, 4. 8 g·kg^-1, 13. 7 μg·g-1, 7. 1 μg·g^-1 and 240. 0 μg·g^-1, respectively. The contents of organic matter, total nitrogen and available potassium in soil of Xiaolanhu are significantly or very significantly higher than those of Shupowan, while the content differences of available phosphorus and total iron ions are not significant between two plots. But the available potassium content in soil of two plots is very low, while the total iron ion content is rich. The water pH values in upper, middle and down streams of Shupowan are pH 6. 35, pH 6. 53 and pH 6. 49, respectively, showing approximately neutral. It is suggested that the soil type in the two natural plots is the type which the contents of organic matter, total nitrogen, available phosphorus and total iron ions are rich, and the available potassium content is low. And extreme lack of available potassium in soil and water neutralization are probably the important environmental factors to limit development of I. orientalis population.