Grime’s ecological strategies reveal contrasting patterns in alkaline and loess grasslands

Abstract

Studying the relationship between biodiversity patterns and processes in vegetation has been at the centre of interest in vegetation ecology for several decades. By studying the biomass of loess and alkaline grasslands along a water and salinity gradient, we aimed to analyse species diversity and Grime’s competitor-stress tolerator-ruderal (CSR) functional strategy patterns. We aimed to test the following hypotheses: i) The biomass and species richness scores and the species composition are significantly different between the sampled grassland community types. ii) The sampled communities are well separated based on the CSR strategy spectrum. iii) The amount of green biomass and litter are positively correlated with competitiveness and negatively with stress tolerance. The biomass and species richness scores and the species composition of the sampled communities along the sampled gradients were significantly different; the highest species richness, evenness and Shannon diversity values were found in loess grasslands. The highest level of litter accumulation was found in alkaline meadows. The communities were well separated in the ordinations but surprisingly, calculation of coordinates for CSR strategy types have not shown clear separation of the grassland community types. All the communities were proven to be characterised by a high level of stress (located in the right corner of the CSR ternary diagram), but they markedly differed in the magnitude of competition and levels of disturbance expressed in the differences of ruderality. These results might suggest that even in highly stressed communities the community composition is strongly dependent on the differences in disturbance intensity (e.g., intensity and duration of grazing) and it is also strongly influenced by the competitive ability of constituting species.