高寒生态脆弱区不同扰动类型草地植被群落状况

通过实地调查及实验室方法测定天祝高寒生态脆弱区5种扰动生境(一年生草地、多年生草地、围栏草地、牧道草地及"黑土滩"草地)的植被群落状况。结果表明,植物群落组成在一年生草地中99%为燕麦、多年生草地中80%为垂穗披碱草和无芒雀麦、3种天然草地中以嵩草、苔草、针茅、珠芽蓼、棘豆、委陵菜为主。群落高度、植被盖度及地上生物量在一年生草地中都相对较大,是人为因素(如农耕)干扰最强,其优势度随时间推移而上升,生境内植物种类多样性下降;而优势度在"黑土滩"草地中呈现低水平,是自然环境压力包括生物因素(如鼠类)干扰最强,原始植被破坏程度高,需要进行大量植被恢复工作,其群落高度、植被盖度及地上生物量也相对较低;其他生境的优势度随着放牧程度的增加而减小。由此可见,放牧和鼠害仍然是高寒草甸生态破坏的一个最重要原因。

Characters of vegetation in different disturbed habitats of alpine grassland in vulnerable ecological region

The status of vegetation of alpine grassland in Tianzhu county,the vulnerable ecological region, were investgated. The field samples were selected as the typical habitats of disturbance in the area,which were fenced rangeland, unfenced rangeland and rodent hill. The results applied that the form of plant community was that Kobresia bellardii , Carex spp. Stipa capillata , Polygonum viviparurn , Oxytropis spp. Potentilla chinensis were the dominant species in three types of rangeland. The height of plant community and coverage of vegeta- tion and above ground biomass in fenced rangeland was lager than other habitats,which was the habitat gained the least disturbance from human,like farming, the original vegetation was altered completely, the dominance in- creased but diversity decreased accordingly. The height of plant community and coverage of vegetation and a- bove ground biomass was smaller in rodent hill,which was the habitat gained the most pressure from environ- ment including the destruction by rodents,the original vegetation changed,and the habitat of rodent hill needs a mount of recovery of vegetation. For other habitats, the dominance declined while the degree of grazing got improved. So grazing and rodents was still the most important reasons for the damage of alpine rangeland ecosystem.