紫茎泽兰入侵云南松林土壤种子库物种结构特征

摘要

Pinus yunnanensis forests were generally disturbed by invasive species Eupatorium adenopho⁃rum,soil seed bank sampling and germination experiments were conducted to study the soil seed bank species structure of P.yunnanensis forest invaded by E.adenophorum.The results showed that invasion of E.adenopho⁃rum had strong influence on quantitative characteristics of seed bank in different layers.The frequency of E.ad⁃enophorum in the litter layer,0-2 cm,2-5 cm,5-10 cm was 100%. The seed storage,relative density,relative frequency and important value of E.adenophorum amount maximum,and it was a dominant species in correspond⁃ing layers.But the influence descended gradually along with the litter layer,0-2 cm,2-5 cm to 5-10 cm. The seed storage in the litter layer,0-2 cm was 1 523.4,2 301.6 ind/m2 ,respectively,but descended to 579.7 ind/m2 in 5-10 cm.The relative density in the litter layer was 97.21%,but descended to 52.33% in 5-10 cm.The rela⁃tive frequency in the litter layer was 42.11%,but descended to 11.59% in 5-10 cm.The important value in the litter layer was 139.31%,but descended to 63.92% in 5-10 cm.The species number and species richness in⁃dex in the litter layer were the lowest,but the indice tended to increase with the increase of soil depth.The eco⁃logical dominance index was the highest in the litter layer,but was the lowest in 5-10 cm. The changing rule was opposite to the former.The Shannon⁃wiener index and evenness index in 2-5 cm were the highest,the in⁃dice descended in the sequence of 5-10 cm,0-2 cm and the litter layer.Herb speices were the absolutely dom⁃inant life form in corresponding layers,accounting for 93.48%-98.90% of the total storage in the soil seed bank.The individual number and species number of wood speices were less,accounting for 1.10%-6.52% of the total storage.%云南松林普遍受到外来入侵种紫茎泽兰的干扰，采用土壤种子库取样和萌发实验相结合的方法，探讨紫茎泽兰入侵的云南松林土壤种子库的物种结构特征。结果表明：紫茎泽兰入侵对土壤各层种子库的数量特征产生了很大的影响。紫茎泽兰在凋落物层、0～2 cm、2～5 cm、5～10 cm土层出现的频度均为100％，其种子储量、相对密度、相对频度及重要值最大为各层的优势种。但这种影响沿着凋落物层、0～2 cm、2～5 cm到5～10 cm土层逐渐降低。其种子储量由凋落物层的1523．4粒／m2、0～2 cm土层的2301．6粒／m2下降到5～10 cm土层的579．7粒／m2；相对密度由凋落物层的97．21％下降到5～10 cm土层的52．33％；相对频度由凋落物层的42．11％下降到5～10 cm土层的11．59％；重要值由凋落物层的139．31％下降到5～10 cm土层的63．92％。凋落物层的物种数、物种丰富度最小，随着土层的加深，物种数、物种丰富度增大；但生态优势度大小变化趋势正好相反，以凋落物层的最大，5～10 cm的最小。 Shannon－Wiener指数、均匀度指数以2～5 cm土层的最大，5～10 cm、0～2 cm土层的依次减小，凋落物层的最小。不同层次土壤种子库的物种组成以草本为主，而且占绝对优势，占各层总储量的93．48％～98．90％，而木本植物的个体数量和物种数较少，仅占各层总储量的1．10％～6．52％。