围封年限对内蒙古羊草-针茅典型草原植物功能群及其多样性的影响

Impact of enclosure duration on plant functional and species diversity in Inner Mongolian grassland

以内蒙古锡林郭勒盟白音锡勒牧场境内的中国科学院内蒙古草原生态系统定位站羊草样地为研究对象,选取2004年,1999年和1979年围封羊草样地,分种记录生物量、盖度、密度、株高等相关指标,研究不同围封年限条件下草原群落的物种组成、生物多样性及群落的功能群特征。结果表明,随着围封年限的增加,植物功能群结构及其多样性发生了变化,且最终趋于稳定。1999和1979年围封与2004年围封相比,多年生禾草和灌木、半灌木累积优势度显著降低(P<0.05),多年生杂类草累积优势度出现不同程度升高;1999年和1979年围封条件下香农-韦弗指数显著高于2004年,1999年和1979年之间没有显著差异(P>0.05);丰富度指数和均匀度指数2004年围封条件下显著高于1999年和1979年围封条件,1999年和1979年之间没有显著差异(P>0.05);1999年和1979年围封条件下总生物量、多年生杂类草生物量、多年生禾草生物量及灌木和半灌木生物量均比2004年增加,其中总生物量及灌木和半灌木生物量显著高于2004年围封,1979年围封条件下灌木和半灌木生物量显著高于1999年围封,1999年和1979年围封条件下总生物量之间没有显著差异(P>0.05),杂类草生物量1999年,1979年和2004年围封之间均表现出显著差异(P<0.05),顺序为1979年>1999年>2004年。综上所述,长期围封促使草场灌丛化,降低草地利用价值,导致草地出现退化。

Plots in the Leyrnus chinensis steppe at （IMGERS） were fenced in 1979, 1999, and 2004 the Inner Mongolia Grassland Ecosystem Research Station The effect of enclosure duration on plant functional groups, species diversity and species composition was studied by testing biomass, coverage, density and height. There were differences in species composition, community characteristics and species diversity with increasing enclo sure duration until finally a steady state was reached. The cumulative dominance values of perennial grasses, shrub and sub-shrub from the steppes fenced in 1999 and 1979 were significantly （P〈0.05） higher than those fenced in 2004. Similar results were also observed for forbs. The Shannon-Weaver index, richness index and evenness index of the steppes fenced in 1999 and 1979, were remarkably higher than those of 2004. There was no significant difference between the 1999 and 1979 results. The total biomass, and biomass of forbs, perennial grass, shrubs and sub-shrubs of the 1999 and 1979 plots all showed an increasing trend. The total biomass, shrub and sub-shrub biomass of 1999 and 1979 were significantly higher than those of 2004, while the shrub and sub-shrub biomass of 1979 was considerably higher than that of 1999. There was no s in total biomass between the 1999, 1979 and 2004 the 1999 biomasse and 1979 biomasses. There were significant （P〈0.05） lgnl diff ficant difference erences between s and the order was 1979〉1999〉2004. It is concluded that these results will lead to a decrease in grassland use value and grassland degradation for invasion by shrubs and sub-shrubs.; biomass