河岸带加拿大一枝黄花化学计量学及入侵机理研究

Nitrogen and phosphorus stoichiometry and invasion mechanisms of Solidago canadensis L. in riparian zone

通过对河岸带土壤与加拿大一枝黄花（Solidago canadensis L.）全年各生长时期氮、磷质量分数的研究,分析河岸带土壤环境特性,以期探究加拿大一枝黄花成功入侵河岸带的机理.结果显示：研究区土壤中氮元素质量分数上层1.22mg/g,下层0.96mg/g、磷元素质量分数上层0.59mg/g,下层0.55mg/g,较全国土壤平均氮、磷质量分数均偏低,年际变化不明显.N/P平均值较低,且随季节变化逐渐减小.加拿大一枝黄花各部位氮磷质量分数为叶〉茎〉根.与其他草本植物相比,植株中氮质量分数稍低,磷质量分数则明显偏高.随植物生长期的变化,植株各部分氮磷质量分数均显示前期较高,中期有所下降,后期逐渐升高的趋势.加拿大一枝黄花N/P变化范围2.25～4.75,明显低于其他草本植物,主要原因在于植株有很高的磷质量分数以及土壤环境中氮素的匮乏,说明其生长受到氮素的限制.对植株茎、叶、根中氮、磷元素与N/P进行相关分析表明,茎、叶中磷质量分数与N/P具有显著负相关关系（P〈0.05）,而根中氮质量分数与N/P具有极显著正相关关系（P〈0.01）.说明了磷素主导了植物地上部分的生长,而氮素主导地下部分.研究区内土壤氮质量分数严重匮乏、磷质量分数也明显偏低,但加拿大一枝黄花植株中氮质量分数仅稍低于其他草本植物,磷质量分数却显著高于其他植物,可以认为其对氮、磷元素的吸收、积累能力远高于其他草本植物,这可能是加拿大一枝黄花得以在河岸带特殊环境中成功入侵的机理.

By analyzing several environmental properties of soil in the riparian zone, particularly, our studies on nitrogen and phosphorus content of Solidago Canadensis L. each growth period one year, revealed mechanism of how S. Canadensis L. successfully invaded in riparian zone. Research results show that： Nitrogen content, in the upper and lower soil area respectively, is 1.22mg/g and 0.96mg/g. In comparison, phosphorus content in the upper soil is 0.59mg/g, in the lower one is 0.55mg/g, which are lower than national average soil nitrogen and phosphorus content. In addition, obvious interannual variation was not observed and N/P average we measured was apparently low and decreased with the seasons changed. Each part of the S. Canadensis L. nitrogen and phosphorus content is leaf 〉stem 〉root. Comparing with other herbs, the nitrogen content of S. Canadensis L. is much low, however, the phosphorus content is obviously on the high side. Along with the change of vegetation growth, nitrogen and phosphorus content of each part in the plant demonstrates a trend of decreasing at beginning then increases at the end. N/P of S. Canadensis L. ranging from 2.25 to 4.75, is significantly lower than the other herbs. Plants of S. Canadensis L. has a high phosphorus content and a lack of nitrogen in the soil so as to its growth was limited by N. By analyzing nitrogen and phosphorus in plant stem, leaf, root element and the N/P correlation shows that the phosphorus content in the stem and leaf and N/P has significant negative correlation（P 0.05）, while nitrogen content in the root and the N/P has a significant positive correlation（P 0.01） which illustrates the phosphorus dominated the growth of plants and nitrogen dominated the underground part. With a grave shortage of soil nitrogen content and phosphorus content obviously lower in the study, the nitrogen content in the plant of S. Canadensis L. is only slightly lower than other herbaceous plants and the phosphorus content is significantly higher than that of other plants. It could be probably that its ability of absorption and accumulation nitrogen and phosphorus is much higher than other herbs, which might be the mechanism of S. canadensis invaded in the special environment of riparian zone successfully.