伊犁河谷围封草地群落组成及植物多样性的变化

以伊犁河谷昭苏马场春秋牧场不同围封年限草地为对象，对围封条件下退化草地自然恢复过程中草地植被特征及物种多样性的变化进行了初步分析。结果表明，随着围封年限的延长和立地条件的改善，草地植物群落由未围封的异株百里香（Thymus marschalianus）+草原苔草（Carex liparocarpos）逐步向适应当地气候条件的针茅（Stipa capillata）+草原苔草（Carex liparocarpos）方向演进。随围封年限的延长，草地植物的群落高度、生物量围封5年时达到最大，之后降低；而群落盖度和优良牧草比例继续增加，围封6年时达到最大；丰富度指数围封6年时达到最大，与其它样地之间差异显著（P<0.05）；多样性指数和均匀度指数都是在围封1年时达到最大；优势度指数围封6年时达到最大；不同围封年限草地之间的相似性指数都在0.65以上；围封6年与围封5年草地的相似性指数最大，说明草地恢复到一定阶段后群落趋于稳定，未围封草地受放牧干扰，物种变化波动较大，与围封草地群落的相似性指数较小。

Changes of community composition and plant diversity of enclosing grassland in Yili Valley

The grassland vegetation characteristics and plant diversity were analyzed to study the effect of enclosure on degraded grassland natural recovery in Yili Valley. The results showed that the dominant species transferred from Thymus asiaticus + Carex liparocarpos to Stipa capillata + Carex liparocarpos with enclosing. The above ground yields and community height increased highest in the 5th enclosure year and then decreased, however, the community coverage and the fine forage ratio continued increased and reached highest in the 6th enclosure year. The richness index reached climate in the 6th enclosure years, and it was significantly different with other sample areas. The diversity index and evenness index reached climate in the first enclosure year, and the dominance index reached climate in the 6th enclosure year. The similar index was over 0.65 is different enclosure times. The similar index reached highest between enclosure 6 years and 5 years, which demonstrated the grassland community tended to stable after the grassland recovery, and the non enclosure grassland was easy to disturbance which had lower similar index.