青海高寒草原鼠丘植物群落结构及稳定性特征

高原鼢鼠(Eospalax baileyi)作为青藏高原最主要的营地下生活啮齿类动物,其通过挖掘行为将大量土堆积于草地,形成大小不一呈镶嵌式分布裸露土丘,对周围植物群落结构产生影响。本研究在封育与放牧条件下,对青海贵南高寒草原鼠丘及周边区域群落植物种组成和重要值、功能群生物量构成、物种多样性及群落稳定性进行定量分析,明晰鼠丘区域植物群落结构和稳定性特征在放牧和封育下的趋同规律。结果表明,1)封育和放牧样地鼠丘上植物种数极少,分别为17种和11种,封育利于鼠丘植物种的侵入和生长;2)鼠丘形成增加周围区域地上生物量122.71 g·m^–2和地面芽植物比例(20.77%),降低地下芽植物比例(22.50%),促使鼠丘周边区域草地由禾草/莎草群落向禾草群落转化,但对群落植物物种多样性无影响;3)封育降低了鼠丘周边区及非鼠丘区草地群落稳定性,放牧增加了鼠丘周边区及非鼠丘区草地稳定性;4)鼠丘草圈增加的植物生物量可部分补偿裸露鼠丘损失的地上生物量,封育和放牧样地分别补偿35.28%和57.93%的裸露鼠丘损失生物量。

Plateau zokor mound community vegetation structure and stability in the Qinghai alpine steppes

Eospalax baileyi is one of the most important rodents living underground in the Qinghai-Tibet Plateau.It accumulates a mound of soil on the grassland through excavation behavior,forming bare hills of different sizes with a mosaic distribution,which has some impact on the surrounding plant communities.In this study,the plant species composition and important values of biomass composition of functional groups,species diversity and community stability were quantitatively analyzed,and the convergence rule of plant community structure and stability characteristics under grazing and fencing was clarified.The results indicated that:1)Number of plant species was very small on mounds in fenced and grazing plots,there have 17 and 11 species,respectively.Fencing was beneficial to the invasion and growth of plants on the mound.2)The formation of the mound increased biomass(122.71 g·m–2)and the proportion of hemicryptophytes(20.77%),and decreased the proportion of geophytes(22.50%)in the surrounding plant communities,which promoted the transformation from grassland/sedge community to grass community,but had no effect on plant species diversity of the grassland community.3)Fencing decreased the stability,while grazing increased the stability of grassland communities around mound and nonmound areas.4)The increase in plant biomass in the mound meadow could partly compensate for the loss of biomass in the nude mound,with 35.28%and 57.93%loss in biomass in the nude mound in fencing and grazing plots,respectively.