摘要
以祁连山东段旱泉沟小流域为例,通过连续6年的定位观测,研究了紫花苜蓿人工草地退化特征.结果表明:紫花苜蓿人工草地建植以来,草地群落的盖度逐年下降,而群落密度增加,草层高度呈波动变化,地上生物量呈单峰曲线变化,最大值出现在建植后第3年;草地的物种数由7种增加到16种,物种替代速率为2.5～5.5,群落的Shannon-Wiener多样性指数呈上升趋势,Pielou均匀度指数表现出增减交替趋势,而Simpson优势度指数呈下降趋势.建植第5年,紫花苜蓿出现了自然稀疏,干草产量下降至129.8 g/m^2,草地裸斑增加、质量下降,部分草地已失去利用价值.2003-2008年人工草地群落经历了紫花苜蓿、多年生杂类草、多年生禾草优势阶段,草地退化严重,割草能力丧失,群落结构和功能趋于撂荒地演替格局.
Using 6 years of continuous location observation,we studied the degradation features of Medicago saliva grassland in the Hanquangou valley of eastern Qilian mountains.The results showed that in growing the Medicago sailva,the community coverage decreased,the community density increased and the community height showed a fluctuation change.Aboveground biomass varied with the single peak curve and the maximum value appeared in 2005.The species in the grasslands increased from 7 to 16 during 6 years.The inter-annual species replacement rate varied from 2.5 to 5.5.Shannon-Wiener diversity index showed an ascendant trend, Pielou evenness index showed a fluctuation change and Simpson index showed a declining trend.Medicago sailva species showed natural thinning in 2007,and the hay yield decreased to 129.8 g/m^2.The vacant land of grassland community increased and the quality declined,so part of the Medicago saliva grasslands lost utilization value.The grassland community went through three successive stages from 2003 to 2008,i.e. the advantage stage of Medicago sailva species,the perennial weeds stage and the perennial grasses stage. The grasslands exhibited a serious degradation and loss of function.The succession pattern of community structure and function concerning artificial grasslands had changed into abandoned arable lands succession pattern.
出处
《兰州大学学报（自然科学版）》
CAS
CSCD
北大核心
2010年第6期72-77,共6页
Journal of Lanzhou University(Natural Sciences)
基金
国家自然科学基金项目(40971039)
甘肃省科技支撑计划项目(1011FKCA157)
甘肃省高校基本科研业务费项目
关键词
紫花苜蓿
退化过程
退耕地
功能群结构
祁连山东段
Medicago saliva
degradation process
abandoned land
functional group structure
eastern Qilian mountain
