鄱阳湖沙山优势植物种叶片氮磷特征

对鄱阳湖沙山14种优势植物的叶片氮、磷含量进行研究,以探讨沙山植物的生理生态适应机制,为鄱阳湖沙化土地的植被恢复提供科学依据。结果表明:鄱阳湖沙山14种优势植物叶片氮含量变化范围为3.10～16.5mg·g^-1,平均值10.21mg·g^-1;叶片磷含量变化范围为0.70～2.10mg·g^-1,平均值1.24mg·g^-1。其中,叶片氮含量仅相当于中国及全球不同植物叶片氮平均含量的一半,叶片磷含量则分别是中国及全球不同植物叶片磷平均含量的85%、70%。鄱阳湖沙山植物较低的叶片氮、磷含量主要受低土壤养分含量控制。蔓荆子作为沙山普遍分布的物种,其叶片氮、磷含量受沙山土壤养分含量低的影响,总体保持较低水平,同时表现出随沙化程度的增加而增加的趋势,这是一种对于水分胁迫的生理适应,以提高水分利用效率。鄱阳湖沙山植物叶片N:P平均比值为9.0,表明沙山植物生长更多地受氮的限制。

Study on nitrogen and phosphorus content in the leaves of dominant plant species in sandy hills along Poyang Lake

To discuss the ecophysiological adaptation mechanisms of plants to sandy soil and thus to provide a scientific basis for vegetation restoration, the authors analyzed nitrogen (N) and phosphorus (P) content in the leaves of 14 dominant plant species in sandy hills along Poyang Lake. Results showed that N content in the leaves of dominant plant species ranged from 3.10～16.5mg·g^-1, with an average value of 10.21mg·g^-1. P content in the leaves varied at a range of 0.70～2.10mg·g^-1, with an average value of 1.24mg·g^-1. The N content was approximately 50% lower than the average N content in the leaves of national and global plants. The P content was about 85% of the average P content in the leaves of national plants and about 70% of global plants, respectively. The relatively lower N and P content might be mainly controlled by low nutrient in the soil. Moreover, as the most dominant plant species in sandy hills, Vitex trifolia Linn. var. simplicifolia Cham had a low level of N and P content due to low soil nutrient. However, N and P content in the leaves of Vitex trifolia Linn. var. simplicifolia Cham increased with sandy intensity, which was an adaptation to water stress for higher water use efficiency. Additionally, the average ratio of N to P in the leaves was approximately 9.0, indicating that plant growth in sandy hills was mainly limited by nitrogen, rather than phosphorus.