Abstract

It is believed that plant communities in harsh and favorable habitats are organized in different ways. The former are mainly organized by abiotic environment and random processes (S model), and the latter are mainly organized by competition (C-S-R model). It can be expected that the characteristics of the organization affect the structure of the dominance of plant communities and its relationship to species richness. The goal of our study was to test this assumption on the example of herbaceous plant communities of relatively stable habitats of several regions and high-altitude belts of the western Caucasus (alpine snowbeds, heaths and meadows, subalpine meadows and marshes, low mountain meadows, grass layer of forests, steppes). The aboveground biomass of communities at the time of its maximum development was used as a criterion of the degree of environmental severity. The relative participation of species was estimated as the ratio of their biomass to the total aboveground biomass on the site (D) or to the biomass of the community remaining after the removal of the biomass of higher-ranking species (K) from it. Under the structure of dominance, relative participation in community of the first rank species (degree of dominance) was understood, as well as the ratio of the values of D and K for two or three species with the largest participation in the aboveground-community biomass. The following results were obtained: (1) If the dominance structure is estimated based on D, then it varies widely and is almost unrelated to the production of the habitats (environmental conditions). (2) In C‑S-R-communities, the K values for species of first rank (K₁) are on average higher than for less significant species (K₂ and K₃); in S-communities, they are on average approximately the same. Moreover, if we consider C-S-R- and S-communities separately, then the (K₁ – K₂) values are not related to the aboveground biomass of communities. The assumption is made that (K₁ – K₂) value can be considered as the index of the degree of expression in the dominants of C-strategy features. (3) The spatial variability of the parameters of the dominance structure is higher in areas of harsh habitats than in favorable ones. (4) C-S-R-communities are characterized by a closer relationship between the degree of dominance and species richness than S-communities. Our results suggest that this is due to the more intensive interspecies competition in C-S-R-communities and to the C-strategy of dominant species.

中文翻译：

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在恶劣和有利环境中的植物群落：其组织特征，优势结构及其与物种丰富度的关系

摘要

人们认为，在恶劣和有利的生境中的植物群落以不同的方式组织。前者主要由非生物环境和随机过程（S模型）组织，后者主要由竞争（CSR）组织模型）。可以预见，组织的特征会影响植物群落的优势结构及其与物种丰富度的关系。我们研究的目的是在西部高加索地区（高山雪床，荒地和草甸，亚高山草甸和沼泽，低山草甸，森林，草原的草层）。社区最大发展时的地上生物量被用作环境严重程度的标准。物种的相对参与度被估计为其生物量与场地上地上总生物量之比（D）或从中去除较高级别物种（K）的生物质后剩余的社区生物质。在优势结构下，了解了一级物种在群落中的相对参与度（优势度），以及参与地上生物量最大的两种或三种物种的D和K值之比。获得了以下结果：（1）如果基于D估算优势结构，则其变化范围很大，并且几乎与栖息地的生产（环境条件）无关。（2）在C‑SR社区中，一等物种的K值（K ₁）的平均水平要高于重要性较低的物种（K ₂和K ₃）；在S社区中，它们平均大致相同。此外，如果我们分别考虑CSR和S社区，则（K ₁ – K ₂）值与社区的地上生物量无关。假设（K ₁ – K ₂）值可以看作是C的优势表达程度的指标。策略功能。（3）恶劣生境地区优势结构参数的空间变异性高于有利生境地区。（4）CSR社区的特征是优势程度与物种丰富度之间的关系比S社区更紧密。我们的结果表明，这是由于CSR社区中物种间竞争更加激烈以及优势物种的C策略所致。