【作者】 柳剑丽；

【导师】 王宗礼； 徐柱；

【作者基本信息】 中国农业科学院 ， 草业科学， 2013， 博士

【摘要】 本研究在对刈割与放牧利用下锡林郭勒典型草原植被与土壤样线调查与定位监测的基础上，开展典型草原植被演替中物种组成与群落结构及土壤特性的研究，分析刈割与放牧利用下典型草原群落演替植被与土壤变化规律。主要结果如下：（1）依据群落物种生活型功能群组成与地上现存量指标对锡林郭勒典型草原区刈割与放牧利用的19个不同地段的羊草与针茅群落进行聚类分析，划分为未退化、轻、中、重度四个退化演替阶段，中度退化群落又进一步分为4种类型，包括一二年生植物占有较大比例的群落、冷蒿占据重要地位的群落、糙隐子草占据优势地位的群落与杂类草占据优势地位的群落。重度退化群落包括两种类型：以冷蒿与星毛委陵菜为优势种的群落与以一二年生植物为优势种的群落。放牧与刈割主导的草地生态系统的退化伴随着草地植物饲用品质与土壤有机质含量的降低。物种多样性指数（H）在中度退化演替阶段最高为1.99，未退化群落最低为1.38。土壤有机质以轻度与未退化草地含量最高分别为47.08g/kg、45.35g/kg，重度度退化草地的有机质含量最低为21.46g/kg。（2）在割草利用下，典型草原不同群落的发展演变趋势不同。以羊草为单优种的群落是一个相对稳定、依靠营养繁殖进行自我调节的群落，刈割未对该群落产生明显影响。克氏针茅+羊草+冷蒿群落在刈割的影响下，短期内表现为进展演替，克氏针茅取代羊草成为群落优势种。羊草+糙隐子草+米氏冰草群落呈退化演替趋势，在刈割利用下，羊草优势地位逐渐丧失，冷蒿增加，一二年生植物增加，群落退化演变为冷蒿+黄蒿+羊草群落，结构不稳定。（3）群落总体关联性测度表明,羊草单优群落VR值为1.03，表现出近似无关联，说明该群落在刈割利用下，处于自身环境下的相对稳定状态，群落中各物种总体上呈分散独立关系。处于演替过渡状态的群落的VR值分别为0.91、0.77、0.91，总体关联性为负关联，群落处于相对不稳定的阶段。相同物种对在不同群落中关联性质、关联程度不同。（4）各植物在不同演替群落中生态位宽度不同。相同物种对生态位重叠在不同群落中而异。处于演替过渡状态的群落生态位重叠高于结构稳定的羊草单优种群落。（5）土壤有机质及养分含量以未退化的羊草群落最高，处于退化状态群落的土壤有机质及全量养分含量最低。放牧样地群落与主要植物种的N/P比显著低于刈割利用的群落，氮磷含量则显著高于刈割利用群落。羊草在不同的干扰方式下、不同的退化演替阶段均保持较稳定的N/P比值。糙隐子草与冷蒿的N/P比值较低，波动范围分别在9.91-11.69、11.35-15.83。更多还原

【Abstract】 By route and located monitoring survey on Xinlingol typical steppe in mowing and grazing, studieson species composition and community structure, soil characteristics of vegetation succession of typicalsteppe were conducted, and analysis of variation law was done on vegetation and soil change insuccession of typical steppe. The main results are as follows:(1) According to functional group composition and aboveground biomass,19Leymus chinensiscommunities and Stipa spp. communities in mowing and grazing in different section in typical steppezone were divided into4successional stages, non-degraded, light, moderate and severe degradation ofby cluster analysis. Moderate degraded communities were further divided into four types, includingcommunities which annual and biennial plants accounting for a large proportion, communities whichArtemisia frigida occupied an important position, communities which Cleistogenes quarrosa was thedominant species and communities which forbs were dominant species. Severely degraded communitiesincluded two types: communities which Artemisia frigida and Potentilla acaulis were dominantspecies, community which annual and biennial plants were dominant species. Grassland ecosystemdegraded with the decreasing of forage feeding level in mowing and grazing in typical steppe. Speciesbiodiversity index including Shannon-weaver index (H) were the highest in moderate degraded statecommunities, and the lowest in non-degraded communities, respectively1.99and1.38. Soil organicmatter was the highest in non-degraded and light degraded grassland and the lowest in the severedegraded grassland, respectively47.08g/kg,45.35g/kg and21.46g/kg.(2)Different community had different succession trends in mowing. The community of Leymuschinensis as a single dominant species was relatively stable community relying on self-regulation ofvegetative propagation, which mowing utilization had not significant impact on it. The community StipaKrylovii+Leymus chinensis+Artemisia frigida showed recovery succession in short term. Stipakrylovii replaced Leymus chinensis and became the most dominant species. The community Leymuschinensis+Cleistogenes quarrosa+Agropyron michnoi showed degraded succession. Leymus chinensislost the dominant position and Artemisia frigida and biennial plant Artemisia scoparia increased. Thecommunity structure was unstable.(3)Leymus chinensis mono-dominant community showed no association with VR value1.03. Inmowing the community remained stable state and species was dispersed independent relationship. Thecommunities in succession state showed a negative association, respectively VR value0.91,0.77and0.91. And communities were in relatively unstable state. The same species pairs showed differentassociation properties and association degree.(4) The niche breadth of species showed difference in different succession state communities. Thesame species pair showed different niche overlaps in different community. Community niche overlapwas higher in succession state than stable Leymus chinensis community.(5)Soil organic matter and nutrition were highest in none degraded Leymus chinensis grassland, and lowest in degraded grassland. The N/P ration of main species and community in grazing communityis significantly lower than mowing community, and the contents of N, P in grazing community weresignificantly higher than mowing community. Leymus chinensis had a stable N/P ratio in differentsuccession state under mowing and grazing. The N/P ratio of Cleistogenes quarrosa and Artemisiafrigid were low and changed between9.91-11.69、11.35-15.83.更多还原