不同年限封育对黄土高原典型草原地上植被的影响

为了揭示自然恢复过程中植被动态变化规律,以黄土高原典型草原为研究对象,采用野外调查与室内分析相结合的方法,分析不同年限封育(0、5、15、23和32年)对草地植被特征、物种多样性和群落演替动态变化的影响。结果表明,随着封育年限的增加,枯落物量和厚度呈递增趋势,群落盖度呈先增加后降低趋势,群落密度呈递减趋势,地上生物量和禾草地上生物量均呈先增加后降低的趋势,且均在封育23年草地达到了峰值。不同年限的封育对Simpson多样性指数和Pielou均匀度指数影响不显著(P0.05)。地上植被的物种丰富度呈先增加后降低趋势,且在封育15年达到峰值。地上植被群落封育演替的一般模式为杂类草生长阶段→本氏针茅(Stipa bungeana)逐渐占优势阶段→本氏针茅稳定发展阶段。

Effect of different enclosure durations on aboveground vegetation in typical steppe on Loess Plateau

In this study,we analyzed community structure,species diversity,and succession dynamics of the aboveground vegetation in different enclosure durations of a typical steppe on the Loess Plateau.We conducted field surveys and laboratory analyses to disclose the dynamic variation of aboveground vegetation during the natural restoration process.The results showed that both the biomass and thickness of litter increased,the to-tal community increased initially and then gradually decreased,and the community density decreased with in-creasing fencing years.The total aboveground biomass and grass biomass both increased initially and then grad-ually decreased,and were the highest in grasslands with 32 years grazing exclusion.Species richness increased first and then decreased after the grasslands were fenced.There was no significant effect of fencing year on the Simpson diversity and Pielou evenness indices (P>0.05).The natural restoration under fencing management followed a general pattern,in which 1)forbs dominated in the early succession stage,2)Stipa bungeana grad-ually became dominant,and 3)the development of S.bungeana stabilized.