三江源河岸带植物群落空间分布特征及其驱动因子解析

Spatial Distribution Characteristics of Plant Community and the Identification of Driving Factors in Riparian Zone of the Three-River Headwaters Region, China

三江源独特的地理与气候条件孕育了特色鲜明的植物种类和植被类型,为揭示三江源河岸带植物群落和土壤生境的空间分布规律及其影响机制,设置了14个调查样地(长江源10个,澜沧江源2个,黄河源2个),定量分析了土壤养分特征(尤其是土壤磷形态)、气候因子和河流地形地貌等环境因子对植物群落特征的影响.结果表明,三江源河岸带植物群落组成以多年生草本植物为绝对优势(72.2%),其次为一年生草本植物(20.4%)和灌木(7.4%).优势植物主要有紫花针茅、圆穗蓼、高山嵩草、蕨麻和麻花艽等.植物盖度、Shannon-Wiener指数和Pielou均匀度指数均值分别为(64.4%±23.6%)、(1.31±0.42)和(0.84±0.08).长江源植物群落多样性指数最高,澜沧江源次之,黄河源最小.长江源河岸带土壤pH显著大于澜沧江源,而土壤有机质、全氮和铁铝结合态磷含量均值显著低于澜沧江源.钙镁结合态磷为河岸带土壤磷的主要形态(63.89%).气温、土壤有机磷含量和pH值对三江源河岸带植物群落结构的影响显著,而土壤钙镁结合态磷含量对植物群落多样性的影响显著.研究结果可加深三江源河岸带植物群落演变趋势及其成因机制的科学认知.

The unique geographical and climatic conditions in the Three-River Headwaters Region gave birth to distinctive plant species and vegetation types.To reveal the spatial distribution of plant communities and soil habitats along the riparian zone of the Sanjiangyuan Region and their influencing mechanisms,14 survey plots were set up(ten from the Yangtze River source,two from the Lancang River source,and two from the Yellow River source),and the effects of soil nutrient characteristics(especially soil phosphorus morphology),climate factors,and river topography on plant community characteristics were quantitatively analyzed.The results showed that the plant community composition in the riparian zone of the source of the three rivers was dominated by perennial herbs(72.2%),followed by annual herbs(20.4%)and shrubs(7.4%).The dominant plants were Stipa purpurea,Polygonum orbiculatum,Carex parvula,Potentilla anserina,and Gentiana straminea.The average plant coverage,Shannon-Wiener index,and Pielou index were(64.4%±23.6%),(1.31±0.42),and(0.84±0.08),respectively.The plant community diversity index was the highest in the Yangtze River source,followed by that in the Lancang River source,and the lowest in the Yellow River source.The soil pH of the riparian zone of the Yangtze River source was significantly higher than that of the Lancang River source,whereas the mean contents of organic matter,total nitrogen,and Fe-Al combined phosphorus were significantly lower than those of the Lancang River source.The calcium and magnesiumcombined phosphorus was the main form of phosphorus in riparian soil(63.89%).Temperature,soil organic phosphorus content,and pH had significant effects on plant composition in the riparian zone of the Three-River Headwaters Region,whereas soil calcium and magnesium-combined phosphorus content had significant effects on plant community diversities.These results may deepen the scientific understanding of the evolution trend and genetic mechanism of plant communities in the riparian zone of the Three-River Headwaters Region.