Intraspecific variability of some functional traits of Trigonocaryum involucratum (Steven) Medw., a caucasus endemic plant

Abstract

Plant traits have been used to predict species and community responses to environmental gradients. We studied variation of leaf area (LA), specific leaf area (SLA), flowering shoot number and seed mass along an elevation gradient in the case of Trigonocaryum involucratum, a scree-growing plant endemic to the Caucasus ecoregion. The study had two major aims: (1) to compare the role of intra-population and inter-population variation of functional trait values; and (2) to ascertain dependence between elevation and trait values and their variation. We collected trait data in several populations in Dagestan (Russian Federation), where the species has about a 1000-m amplitude of elevational distribution. The intraspecific variability of trait values was assessed via standard statistical tools (one-way ANOVA and linear regression analysis). The trait values mostly have high inter-population variation (more than 90% for each of the trait values compared to intra-population variation of each trait), indicating adaptation of populations to site conditions. Much higher intra- vs. inter-population variation in SLA at subnival elevations indicates local micro-site diversity and may serve as a buffer against future stress related to climate change. All the trait values negatively but significantly correlate (weakly or moderately) with elevation. Negative correlation presumably shows a certain increase in the limiting effect of the elevation gradient associated with changes in temperature, soil nutrient availability and soil water content, as well as with high solar radiation. More evidence from a broader study of the species throughout its distribution range is needed for firmer conclusions about the intraspecific variability of T. involucratum.