Influence of fencing duration on community and population of Stipa grandis in a typical steppe.
Influence of fencing duration on community and population of Stipa grandis in a typical steppe.
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发表时间：
2010
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通讯作者：
Wu Jianbo;Bao Xiaoying;Li Jie;Zhao Nian-xi;Gao Yubao
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作者：
Wu Jianbo;Bao Xiaoying;Li Jie;Zhao Nian-xi;Gao Yubao
大针茅草原是内蒙古高原常见的稳定的、典型草原的代表性类型，不仅是内蒙古重要的牧草地，也是京津地区重要的绿色防护林，具有相当的生态和经济意义。由于人为干扰和动物过度放牧的加剧，退化的大针茅草原面积迅速扩大，建群种是恢复生态学中的重要组成部分。以往的研究主要集中在恢复后植被和土壤特性的变化上，而对建群种恢复的研究较少。事实上，建群种恢复后的植被是否能够通过自身的生长维持，是影响恢复成功的关键。以连续放牧草地中的大针茅种群为对照，选择围栏封育4年、9年和29年的大针茅种群为研究对象，通过样方调查，研究了围栏封育时间对恢复过程中巨杉种群和群落变化的影响结果表明，围栏封育对放牧过程中大针茅群落和种群的变化有一定的影响，随着围栏封育时间的延长，大针茅群落的物种多样性和物种数均比放牧区增加，围栏封育9年后，围栏群落的结构和组成与原始群落相似，多年生杂类草、灌木和半灌木的数量明显减少，围栏29年后，大针茅种群数量和形态特征均随围栏时间的延长而增加，围栏9年后，大针茅种群数量和形态特征均呈下降趋势，围栏29年后大针茅种群数量和形态特征显著低于围栏9年后的大针茅种群数量和形态特征，大针茅种群的生殖分配也随围栏时间的延长而增加围栏封育9年后，比叶面积随围栏封育时间的延长而减小，质量叶氮浓度随围栏封育时间的延长而减小，围栏封育9年后，质量叶氮浓度又逐渐升高，说明围栏封育9年后，在恢复期，长期围栏封育对植物种类和群落的生长发育有不利影响。
Stipa grandis steppe is the common stable,representative form of typical steppes in the Inner Mongolia plateau.It is not only an important pasture for Inner Mongolia,but also an important green protective windbreak for Beijing-Tianjin area,and has considerable ecological and economic importance.Recently,the area of degraded S.grandis steppe has rapidly expanded due to increased human disturbance and animal overgrazing.The restoration of degraded grassland is of prime importance in restoration ecology.Most studies have focused on the variation of the vegetation and soil characteristics after restoration with little research attention on the restoration of constructive species.In fact,it was considered that restoring vegetation of constructive species could be sustained by its own growth,which was the key influence on the success of the restoration.In the present study,we used the S.grandis populations in the continuous grazing pasture as a control,and selected fencing S.grandis populations at different times as research objects that had been fenced for 4 years,9 years and 29 years,respectively.We investigated the fencing times affecting the variations of the S.grandis population and communities in the restoration process using a quadrat survey method.Results showed that fencing had an impact on the communities and the populations of S.grandis during grazing.The diversity and the number of species of community increased with fencing time compared to that in the grazing plot.After being fenced for 9 years,the structure and component of the fenced community was similar to that of the original community.The number of perennial forbs and shrubs and semi-shrubs increased in the site fenced for 29 years.The population and morphological characters of S.grandis increased with fencing time and then decreased after being fenced for 9 years.Features of S.grandis in plot fenced for 29 years were significantly lower than those in plots fenced for 9 years.The reproductive allocation of S.grandis also increased with fencing time then decreased after fenced for 9 years.The specific leaf area decreased with fencing time,but the mass-based leaf nitrogen concentration decreased with fencing time and then increased after being fenced for 9 years.Results suggested that long term fencing had a negative impact on the growth and development of plant species and community when the pasture was in recovery after being fenced for 9 years.