Abstract: The vegetation composition and coverage, the grass group altitude, the species number, the grass productivity of natural pasture were investigated in the karst area of southwest China from 2006-2012 year. There were positive correlation between the output of grassland vegetation and the degree of coverage, the height of grass during seven tested years. Gradually regression equation was Y=7.75X₁+9.37X₂+110.76 (Y-output, X₁-degree of coverage, X₂-vegetation height). The vegetation undulation rate showed the change of "wave form". The growth of vegetation was better in 2006, 2010 and 2012 than that in control year, whereas the growth of vegetation was worse in 2007, 2008, 2009 and 2011 than that in control year. The comprehensive evaluation of grassland indicated that the natural pasture of tested area was ranked "middle"; the grassland vegetation of tested area was ranked "good" and "reasonable utilization".

Key words: Karst region, Natural grassland, Vegetation dynamics, Fluctuation ratio

摘要： 通过对2006—2012年中国西南岩溶地区天然草地植被组成、覆盖度、草群高度、物种数、产草量等进行监测研究，探讨该地区天然草地植被动态变化，为合理使用该地区草地资源提供基础依据。结果表明：7年间研究区草地植被产量（Y）与盖度（X₁）、高度（X₂）成正相关（r=0.8978），其逐步回归方程为：Y=7.75X₁+9.37X₂+110.76；草地植被波动率总体呈“波浪式”变化，2006年、2010年和2012年3年的植被生长状况比正常年好；2007年、2008年、2009年和2011年4年的植被生长状况比正常年差。总体看，研究区天然草地等级评定为“中质中产”草地，利用状况为合理利用，草地植被基况良好。

关键词: 岩溶地区, 天然草地, 植被动态, 波动率