Functional Diversity of Alpine Plant Communities: A Case Study of Plant Height

Abstract

The parameters of functional diversity are studied on the example of plant height for four alpine communities (alpine lichen heaths, Festuca varia grasslands Hedysarum-Geranium meadows, and alpine snowbed communities) in Teberda Reserve of the northwestern Caucasus. The work tests the hypothesis that, when plants that use different volumes of air, a low volume of the environment is used more evenly than a high volume. It was assumed that the divergence in plant height is more pronounced in meadow communities, where the competitive relationship is stronger and the level of production is higher. For the four main types of phytocenoses (alpine heaths, Festuca varia grasslands Hedysarum-Geranium meadows, alpine snowbeds), data were obtained on the average height of the plant species forming them, the biomass of individual species, and the weighted average plant height in the communities. The indices of functional richness, evenness, and divergence were calculated based on these data. It is shown that taking into account the abundance of species in the community significantly affects the values of average height and indices of functional diversity. Contrary the a priori hypothesis, it was found that the value of evenness is significantly lower at a low air volume occupied by the community (alpine snowbeds) than for a high volume (Festuca varia grasslands). The functional divergence in alpine snowbed communities with low productivity is higher than that in the more productive meadow phytocenoses, e.g. Festuca varia grasslands. The aboveground production positively correlated with functional richness in the aggregate analysis of all data, but this correlation is not detected within communities. Functional evenness is not related to community production. An unimodal relationship between the index of functional-divergence and aboveground biomass was shown only for the Festuca varia grasslands (the maximal divergence is observed on plots with average biomass).