滇池流域富磷区不同土壤磷水平下植物叶片的养分化学计量特征

Leaf nutrient stoichiometry of plants in the phosphorus-enriched soils of the Lake Dianchi watershed,southwestern China

滇池流域是我国典型的富磷区,分析该区域内不同土壤磷含量下主要植物的化学计量特征,有助于理解该区域的生态环境特点和生态恢复的特殊性。该研究测定了滇池流域滇中地区75种常见植物叶片的碳(C)、氮(N)、磷(P)及钾(K)含量,综合分析了该区域不同土壤磷水平(富磷和正常)下不同生活型植物叶片的C、N、P和K的计量特征。结果表明,研究区域植物叶片C、N和K含量的算术平均数分别是441.42、16.17和13.57mg·g-1,P含量的几何平均数为1.92mg·g-1,植物叶片的N、P和K含量之间呈显著的正相关;富磷区域植物叶片的P和K含量显著高于正常区域,N/P、K/P显著低于正常区域。无论是富磷还是正常区域,草本植物的N、P和K含量均高于木本植物,乔木与灌木差异不明显。植物叶片的P含量及N/P与土壤磷水平呈显著相关;叶片N/P分析结果表明,N是影响滇池流域植物生长和群落恢复的主要限制元素。研究指出,在滇池流域增加陆地植物群落及生态系统的氮素来源是进行生态修复和面源污染防治的重要切入点。

Aims Understanding the stoichiometry of nutrient elements of plants growing in phosphorus-enriched areas can help characterize plant differentiation and guide ecological restoration in different biogeochemical environments.The Lake Dianchi watershed of southwestern China has P-enriched soils,and its main plant species may illustrate the relationship between plant ecological traits and the environment.Our aim was to test whether different plant life forms living at different P levels in this area have different patterns of leaf nutrient stoichiometry.Methods We collected leaf samples from 75 adult plants and soil samples from their root-zones in P-enriched areas and reference sites within the watershed.We determined N,P and K contents of leaves and total P contents of soil samples and calculated element ratios.Important findings The arithmetic means of leaf C,N and K were 441.42,16.17 and 13.57 mg？g-1,respectively,and the geometric mean of leaf P was 1.92 mg？g-1.Significant correlations among leaf C,N,P and K were ob-served in all plant species.Higher P and K contents were observed in plants growing in higher P areas,but higher N/P and K/P were observed in lower P sites.Leaf nutrient concentration was significantly higher in herbaceous plants than in woody plants,but there was no difference in leaf nutrient concentrations between trees and shrubs.Leaf N/P and K/P were correlated negatively with soil P content.Results suggested that plant growth and vegeta-tion development in the Lake Dianchi watershed were limited by low soil N contents and plant growth enhanced by N addition should be important for vegetation resilience and prevention of non-point source pollution in the process of ecosystem restoration.