巴音布鲁克草原不同围封年限高寒草地植物群落演替分析

运用空间代替时间的方法对巴音布鲁克高寒草原不同围封年限的草地进行研究. 结果表明: 随着围封年限的延长, 群落由未围封的天山赖草( Leymus tianschanicus)+黄花棘豆(Oxytropis ochrantha Turcz)逐步向羊茅(Festuca ovina)+紫花针茅(Stipa purpurea) 方向演进. 丰富度指数和多样性指数都是在围封1 a的草地达到最大, 均匀度指数不断增大, 优势度指数在未围封草地最大. 各围封年限草地之间的相似性指数都在65%以上. 围封1 a草地的地上生物量与未围封、围封3a的差异性显著( P <0.05), 其它各样地之间差异性均不显著( P >0.05). 围封草地之间地下生物量(0～30 cm)差异显著( P <0.05), 而未围封草地与围封3 a、 5 a草地地下生物量差异性显著( P <0.05), 与围封1 a草地地下生物量差异性不显著( P >0.05). 随着围封年限的延长, 群落的演替指数和演替度分别为3.53, 4.28, 6.06, 6.43和43.57, 46.35, 52.25, 61.14, 二者都表现为逐渐增加.

The Succession of Plant Communities in Alpine Grasslands in Different Ages of Enclosing

Bayinbuluke alpine grassland is one of the largest sub-alpine grassland in China. Due to the serious degradation of grassland in the recent years, the state and autonomous regions invested to enclosing the grassland. By using the method of space substituting time, alpine grassland in different ages of enclosing was studied. Four flat plots with relatively uniform topography and enclosed time of 1 year (E1), 3 years (E3), 5 years (E5) and non-enclosure (G) were selected for studying. The grasslands were freely grazing pasture, grazing rate of 5.7 sheep·hm~(-2).After enclosure,it was used as spring pasture with 5.7-grazing sheep·hm~(-2).The non-enclosure plot was loaded 5.7-grazing sheep·hm~(-2)in addition to the winter.The results showed that the species of community from Leymus tianschanicus+Oxytropis ochrantha Turcz change to Festuca ovina + Stipa purpurea . E1 had the highest richness index and diversity index in the four plots;the Pielou's index increased gradually;index of Simpson was the maximum in G;index of Sorensen was higher than 65% within all the enclosures. The above-ground biomass of E1 was significantly higher than that of G and E3 ( P <0.05);the belowground biomass of E1, E3 and E5 was significantly different;in G it was significantly lower than that in E3 and E5. The soil porosity of G and E5 were in the two U-ends, the volume weight of G and E5 were in the two inverted U-ends. Along with the changes in the characteristics of the community, index of succession and degree of succession were 3.53, 4.28, 6.06, 6.43 and 43.57, 46.35, 52.25, 61.14, respectively. Both of them were gradually increasing.