花江峡谷岩生草本植物群落及其氮磷计量特征

Characteristics and Nitrogen-Phosphorus Stoichiometry of Rock Herb Communities in Huajiang Gorge

花江峡谷是位于喀斯特地区典型的中亚热带干热河谷。选取花江峡谷区域内的岩生草本植物群落为研究对象,研究不同海拔岩生草本植物群落的群落特征、氮磷化学计量特征及两者之间的关系。结果表明:调查区域内共有岩生草本植物16种,有荩草(Arthraxon hispidus)+显子草(Phaenonperma globosum)草本植物群落、荩草草本植物群落、荩草+白茅草(Imperata cylindrica)草本植物群落和白茅+小颖羊茅草(Festuca parvigluma)草本植物群落4种群落类型。各样地的物种相似度与海拔高度表现为正相关,而物种多样性、替代速率、土壤N、P含量和水热因子与海拔高度表现为负相关,生物量呈单峰型的曲线变化趋势,样地2获取的生物量最大。各样地土壤和植物叶片的N、P含量都极低,叶片N/P比值显示大多数植物的生长表现为缺N限制。物种重要值与植物叶片N/P比值表现为极强的正相关关系,与P含量表现为中等程度的负相关关系,而与N含量的相关性较弱。

Huajiang Gorge is a typical middle subtropical dry hot valley in Karst area. Taking the rock herb communities in Huajiang Gorge as research objects, the community characteristic, nitrogen-phosphorus stoichiometry and relationships between them were studied. The results show that a total of 16 species of rock herbs and 4 different rock herb communities ( Arthraxon hispidus+Phaenonperma globosum, Arthraxon hispidus, Arthraxon hispidus+Imperata cylindrica and Imperata cylindrica+Festuca parvigluma ) were found in study area. There was positive correlation between altitude and species similarity coefficient, and negative correlation between altitude and species diversity, substitution rate, soil nitrogen and phosphorus content, hydro-thermal feature. There was a trend of single peak curve in biomasses variation of 4 communities, and plot 2 had the largest biomass. The N and P contents of soils and plant leaves were extremely low in all plots, and the ratios of N/P indicate most of plants growth was limited by N. Strong positive correlation was found between the important value of the plants and the N/P ratios of plant leaves, moderate degree negative correlation was found between the important value of the plants and the P contents of plant leaves, and no significant relation was found between the important value of the plants and N content.