Scale- and taxon-dependent patterns of plant diversity in steppes of Khakassia, South Siberia (Russia)

Abstract

The drivers of plant richness at fine spatial scales in steppe ecosystems are still not sufficiently understood. Our main research questions were: (i) How rich in plant species are the natural steppes of Southern Siberia compared to natural and semi-natural grasslands in other regions of the Palaearctic? (ii) What are the main environmental drivers of the diversity patterns in these steppes? (iii) What are the diversity–environment relationships and do they vary between spatial scales and among different taxonomic groups? We sampled the steppe vegetation (vascular plants, bryophytes and lichens) in Khakassia (Russia) with 39 nested-plot series (0.0001–100-m2 plot size) and 54 additional 10-m2 quadrats across the regional range of steppe types and measured various environmental variables. We measured β-diversity using z-values of power-law species–area relationships. GLM analyses were performed to assess the importance of environmental variables as predictors of species richness and z-value. Khakassian steppes showed both high α- and β-diversity. We found significant scale dependence for the z-values, which had their highest values at small spatial scales and then decreased exponentially. Total species richness was controlled predominantly by heat load index, mean annual precipitation, humus content and soil skeleton content. The positive role of soil pH was evident only for vascular plant species richness. Similar to other studies, we found that the importance of environmental factors strongly differed among taxonomic groups and across spatial scales, thus highlighting the need to study more than one taxon and more than one plot size to get a reliable picture

Species–area relationships in continuous vegetation: Evidence from Palaearctic grasslands

“…The superiority of the power function has also been shown at similar grain sizes and in continuous vegetation as well as habitats other than grasslands (e.g. Moreover, power function SARs provide, with their exponent (z-value), a meaningful (and standardized) beta-diversity measure in continuous vegetation (Jurasinski et al, 2009;Polyakova et al, 2016), enabling the effective comparison of species turnover among taxa or between different ecological conditions. This leads us to conclude that the power function is a suitable (and mostly the best possible) model for SARs in nearly any situation, provided the areas from which the relationship is constructed are contiguous.…”

Ecology and Conservation of Steppes and Semi-Natural Grasslands

“…In addition to vascular plants, dry grasslands of the class Koelerio-Corynephoretea can also harbour high diversity of bryophytes and lichens . Although recent publications on grassland diversity have largely focused on semi-natural grasslands (Chytrý et al 2015, there is some evidence that also natural Palaearctic steppes, which are still very much understudied, could be extremely rich in small grain sizes (Polyakova et al 2016).…”

Step(pe) up! Raising the profile of the Palaearctic natural grasslands

“…Since they resemble ecologically and floristically the meadow steppes of the forest steppe zone in Eastern Europe and Middle Asia one might wonder why equally high or even higher small-scale richness values are not found in the natural meadow steppes. This Special Issue contains two contributions that applied standardised EDGG multi-scale phytodiversity sampling (Turtureanu et al 2014) for the first time in natural steppe vegetation: Kuzemko et al (2016) in Central Podolia, Ukraine, a part of the forest-steppe zone of the European steppe region, and Polyakova et al (2016) for Khakassia, Russia, at the transition from the Middle Asian to the Mongolian region. Both author teams found high vascular plant species richness across spatial scales, with maxima, however, that were below the maxima in semi-natural grasslands of Central Europe.…”

“…Across the Siberian and Central Asian steppes, the Virgin Lands Campaign of the Soviet Union led to Fig. 1 Simplified map of the Palaearctic steppe biome (with main steppe ecoregions after Wesche et al 2016) with localisation of the studies included in this Special Issue: (1) Kuzemko et al (2016); (2) Polyakova et al (2016); (3) Sutcliffe et al (2016); (4) Dembicz et al (2016); (5) Kajtoch et al (2016); (6) Weking et al (2016); (7) Mathar et al (2016); (8) Lameris et al (2016); (9) Wang and Wesche (2016); (10) Addison and Greiner (2016); (11) Niu et al (2016); (12) Novenko et al (2016); (13) Deák et al (2016); (14) Ambarlı et al (2016); (15) Kamp et al (2016); (16) Brinkert et al (2016); (17) Kämpf et al (2016). Reviews summarising data across countries are indicated by large asterisks (i.e.…”