Key Laboratory of Cell Activities and Stress Adaptations Ministry of Education, School of Life Sciences, Lanzhou University, Tianshui Road 222, Lanzhou, Gansu, People's Republic of China.
Environnements et Paléoenvironnements Océaniques et Continentaux, University of Bordeaux, Bordeaux, France.
Sci Total Environ. 2023 Feb 10;859(Pt 2):160154. doi: 10.1016/j.scitotenv.2022.160154. Epub 2022 Nov 12.
In alpine systems, cushion plants act as foundation species by ameliorating local environmental conditions. Empirical studies indicate that contrasting phenotypes of alpine cushion species have different effects on understory plant species, either facilitative or competitive. Furthermore, dependent species within each community type might also exhibit different responses to each cushion phenotype, which can be clustered into several "response groups". Additionally, these species-groups specific responses to alpine cushion species phenotypes could alter community assembly. However, very few studies have assessed responses of dependent communities at species-group levels, in particular for both above- and below-ground communities. Here, we selected a loose and a tight phenotype of the alpine cushion species Thylacospermum caespitosum in two sites of northwest China, and use the relative intensity of interactions index to quantify cushion plant effects on subordinate communities of plants and soil fungi and bacteria. We assessed variations in responses of both above- and below-ground organisms to cushion plant effects at species-group level. Species-group level analyses showed that the effects of the phenotype varied among groups of each of the three community types, and different species-groups were composed by unique taxa. Additionally, we found that loose cushions enhanced stochastic processes in community assembly, for plants and soil fungi but not for soil bacteria. These variations of phenotypic effects on different species-group induced contrasting taxonomic composition between groups, and alter community assembly thereby. Our study highlights the occurrence of contrasting effects of two phenotypes of a foundation cushion plant on understory plants, soil fungi and bacteria community composition, but not necessarily on their richness. We also showed that assessing responses of understory species at the species-group level allows a more realistic and mechanistic understanding of biotic interactions both for above- and below-ground communities.
在高山系统中，垫状植物通过改善局部环境条件起到基础物种的作用。实证研究表明，高山垫状物种的不同表型对林下植物物种有不同的影响，既有促进作用，也有竞争作用。此外，每个群落类型中的依赖物种也可能对每个垫状表型表现出不同的反应，可以将其聚类为几个“反应组”。此外，这些物种组对高山垫状物种表型的特定反应可能会改变群落组装。然而，很少有研究评估依赖物种在物种组水平上对高山垫状物种表型的反应，特别是对地上和地下群落。在这里，我们选择了中国西北两个地点的高山垫状植物长瓣金莲花的疏松和紧实表型，并使用相互作用强度指数来量化垫状植物对植物和土壤真菌和细菌从属群落的影响。我们评估了地上和地下生物对垫状植物影响的物种组水平的反应变化。物种组水平分析表明，表型的影响在三种群落类型的每个组之间存在差异，并且不同的物种组由独特的分类群组成。此外，我们发现疏松垫状植物增强了群落组装中的随机过程，对植物和土壤真菌有影响，但对土壤细菌没有影响。这些表型效应在不同物种组之间的变化导致了组间的分类组成的对比，从而改变了群落组装。我们的研究强调了基础垫状植物的两种表型对林下植物、土壤真菌和细菌群落组成的不同影响，但不一定对其丰富度有影响。我们还表明，在物种组水平上评估林下物种的反应可以更真实和更具机制地理解地上和地下群落的生物相互作用。
