To understand the formation process of typical poisonous plant degraded grassland, we studied the cha-racteristics of vegetation and soil during the gradual expansion of Ligularia virgaurea into the native grassland of Qinghai-Tibet Plateau. The results showed that population density, plant height, coverage, and biomass of L. virgaurea increased during the formation of L. virgaurea degraded grassland. In comparison with native grassland, the degraded grassland had higher total aboveground biomass (113.9%), soil total nitrogen concentration (61.0%), NH4+-N (77.9%), organic carbon concentration (45.3%), available phosphorus concentration (78.8%) as well as soil microbial biomass carbon (42.1%) and nitrogen (47.4%), but lower NO3--N (40.1%) and species richness (28.5%) and aboveground biomass (45.7%) of other species beyond L. virgaurea. The extremely strong abilities of interspecific inhibition and morphological plasticity of L. virgaurea, as well as efficient nutrient accumulation and utilization were the keys to its successful expansion, which facilitated the formation of typical L. virgaurea degraded grassland.
为深入了解典型毒草型退化草地形成的过程,本文对青藏高原原生草地上黄帚橐吾逐渐扩张形成典型毒草型退化草地过程中植被和土壤特征进行研究。结果表明: 黄帚橐吾型退化草地形成过程中,黄帚橐吾种群密度、株高、盖度和生物量均增加;相比原生草地,退化草地的总地上生物量增加113.9%,土壤全氮、铵态氮、有机碳和速效磷含量分别增加61.0%、77.9%、45.3%和78.8%,土壤微生物生物量碳、氮分别增加42.1%和47.4%,而土壤硝态氮含量和物种丰富度分别减少40.1%和28.5%,除黄帚橐吾以外其他植物的生物量减少45.7%。黄帚橐吾极强的种间抑制能力、形态可塑性、高效的养分蓄积能力和利用效率是其成功扩张的关键,促进了黄帚橐吾型退化草地的形成。.
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