Abstract: This paper analyse plant composition,aboveground biomass,the proportionof good grasses and nutrient element in soil at different degraded grassland in Dari county,Guoluo, Qinghai.The results show: The aboveground biomass at moderately degradedgrassland (MDG) is the highest (50.3g/0.25m²), it is the lowest at heavily degradedgrassland (HDG), The proportion of good grasses is the highest at non-degraded grassland(original vegetation) (78.40%),the lowest one at HDG,lightly degraded grassland (LDG)and MDG is between the both above-mentioned.The mean density of pikas is the highestat MDG(148 Indivi./ha),the destroy caused by pikas is very heavy(494m²/ha),they showthe positive correlation (r = 0.9888, df = 3, 0.01>P>0.001, solid degree of soil decreasewith increasing of the grassland degraded level.

Key words: Black soil type, Degraded grassland, Ecological process

摘要： 研究分析退化草地的植被组成、地上生物量、优良牧草比例、高原鼠兔密度以及土壤理化性质等特征,探讨“黑土型”退化草地的成因及生态过程。结果表明,中度退化草地生物量最高(50.3g/0.25m²),重度退化草地最低(34.0g/m²)。原生植被优良牧草比例最高(78.40%)。重度退化草地最低(4.49%),轻度和中度退化草地居中(57.2%和16.42%)。中度退化草地高原鼠兔平均密度较高(148只/hm²),其危害程度较严重(494m²/hm²),二者之间呈显著的正相关(r＝O.9888,df＝3,P<0.01)。土壤坚实度随草地退化程度加重而降低。“黑土型”退化草地的形成是一个长期的、连续的过程,草地退化则是诱发这一过程的主要因子,高原鼠兔挖掘洞道,破坏草皮及植被,又加剧了草地的进一步退化,最终导致了“黑土型”退化草地的形成和不断扩大。

关键词: 黑土型, 退化草地, 生态过程