海螺沟冰川退缩区原生演替序列植被物种多样性与生物量的关系

Relationship between biodiversity and biomass along the primary succession chronosequence in the foreland of the Hailuogou Glacier

生物量-物种多样性关系是生态学研究的热点之一,其具体模式目前还未形成共识,背后机制也存在较大争议.在川西贡嘎山海螺沟冰川退缩区原生演替序列上建立样地,以空间代替时间的方法,对冰川退缩后第6、27、37、47、53、59、87、127、157年期间9个演替阶段(T1-T9)进行生物量和物种多样性调查,分析冰川退缩区植被原生演替过程中物种多样性演化格局及与植被生物量的关系.结果显示:(1)海螺沟冰川退缩区物种丰富,共记录植物27目31科58属68种,但不同演替阶段植物物种组成差异较大;(2)群落尺度上植物物种丰富度、Shannon-Wiener指数和E. Pielou指数呈“单峰”型,峰值分别出现在59年(29.00±2.00)、87年(2.68±0.21)和87年(0.88±0.07);(3)植物群落生物量介于0.95-207.80 t/hm^(2)之间,呈波动上升,在87年达到峰值;(4)群落尺度上生物量与物种多样性具有长期正线性相关关系,而乔、灌、草不同层次生物量-物种多样性关系无显著相关,仅少数呈负相关.本研究为生物量-物种多样性关系假说提供了一个实例,并表明不同演替阶段物种组成差异大,群落生物量-物种多样性关系存在正相关,但各层次内部无统一趋势.

The relationship between biomass and diversity is a hotspot of ecological research. The specific model describing this relationship has not yet reached a consensus, and the underlying mechanism remains controversial. This study investigated the variation in plant biodiversity and the relationships between species diversity and biomass along a primary vegetation successional chronosequence in the foreland of the Hailuogou Glacier in West Sichuan of China. The results indicated a high abundance of plants at the successional chronosequence, with 68 species, 58 genera, 31 families, and 27 orders recorded across successional stages.At the community level, a humped shape in the variation of plant species richness, Shannon-Wiener index, and E. Pielou index along the successional chronosequence was observed, with peaks at the 59(29.00 ± 2.00), 87(2.68 ± 0.21)-and 87(0.88 ± 0.07)-year time points. Moreover, the vegetation biomass varied at 0.95-207.80t/hm^(2) along the chronosequence, with fluctuations along the succession, peaking at 87 years. Across the successional chronosequence, there was a positive linear correlation between plant biomass and diversity at the community level and a negative or no significant correlation at the canopy, mid, or ground layers. This study provides empirical evidence supporting the biomass diversity hypothesis in forest ecosystems, thus contributing to extending the generality of this framework. The results showed significant differences in species composition at different succession stages and a positive correlation between community biomass and species diversity;however, there was no unified trend within each level.