科尔沁沙地草地植被对围封和放牧的响应

研究了科尔沁沙地疏林草地、针茅草原和草甸植被盖度、地上和地下生物量、物种多样性对围封和放牧的响应。结果表明：（1）围封与放牧草地的优势植物不同，围封草地植物群落优势植物为多年生禾本科植物，放牧草地中一年生植物和小半灌木优势明显。（2）围封和放牧草地的植物盖度、凋落物量、地上生物量和物种丰富度存在明显差异（P<0.05）；围封显著提高了植被盖度和地上生物量，由疏林草地、针茅草原到草甸，植物盖度和地上生物量逐渐增加，而3种草地植被凋落物量大小顺序为针茅草原> 疏林草地> 草甸；放牧条件下植物盖度、凋落物量和物种丰富度差异不显著（P>0.05）。（3）3种草地之间的地下生物量无显著差异（P>0.05），但围封与放牧之间、不同土壤层次之间地下生物量存在明显差异（P<0.05）；围封显著提高草地的地下生物量（P<0.05）；草地地下生物量随着土壤深度表现出下降趋势（P<0.05）。长期放牧增加了草地一年生植物和小半灌木植物的优势，消除了不同草地之间植被盖度和物种丰富度的差异；而围封能提高草地多年生禾本科植物的优势、增加其物种丰富度，对于草地质量和植物多样性的恢复和保育具有积极作用。

Response of Grassland Vegetation in Horqin Sandy Land to Exclosure and Grazing

The response of plant coverage, aboveground and belowground biomass, and species richness of different types of grassland(elm scattered grassland, Stipa steppe and meadow)in Horqin sandy land for the exclosure and grazing were studied. The results showed that dominant plants in fencing grassland were perennial grasses, while annual and sub-shrub in grazing grassland. The vegetation coverage, litter biomass, aboveground biomass and species richness in three types of grassland under fencing and grazing had significant difference (P<0.05), of which enclosure significantly increased their coverage and aboveground biomass that added from to elm scattered grassland to Stipa steppe to meadow. The litter biomass of grassland being fenced added in the following order: Stipa steppe>elm scattered grassland>meadow. The differences of coverage, litter biomass and species richness of different grazing grassland were non-significant(P>0.05).The root biomass between three grassland had non-significant difference(P>0.05), which significantly different between exclosure and grazing, different soil depth. The exclosure significantly increased root biomass of grassland. The long-term grazing increased the advantages of annuals and small sub-shrubs, eliminated the differences of plant coverage and species richness between three grasslands. The exclosure can raise the dominance of perennial grasses, increase their species richness, and have a positive effect on recovery and conservation of grassland quality and plant diversity.