高寒草甸“黑土型”退化草地的成因及生态过程

Ecological Process of Forming“Black-Soil-Type”Degraded Grassland

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。

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.