Abstract
The functional diversity and composition of plant traits within communities are tightly linked to important ecosystem functions and processes. Whereas vegetative traits reflecting adaptations to environmental conditions are commonly assessed in community ecology, floral traits are often neglected despite their importance for the plants’ life cycle. The consideration of floral traits covers important aspects such as sexual plant reproduction and pollinator diversity, which remain unobserved in studies focussing on vegetative traits only. To test whether vegetative and floral traits differ in their responses to elevation, we measured morphological and chemical traits of plant species occurring in pastures at seven elevations in the Austrian Alps. Variation in functional composition was examined using the concept of n-dimensional hypervolumes and vector analysis. Our data show that vegetative and floral traits vary differently with the elevational gradient. Whereas vegetative traits changed in a predictable manner with elevation, floral traits did not specifically respond to elevation. Overall variation in vegetative traits mainly resulted from phenotypical differences between plants in different elevations, whereas total variation in floral traits was a result from a high variation within communities. The assessment of functional changes in vegetative and floral traits along mountain slopes thus reveals different patterns in plant responses to elevation and may help to generate testable hypotheses on functional responses to current climate warming.
Highlights
Plant communities vary along elevational gradients both taxonomically and regarding the characteristics of their traits, which reflects responses to changing temperature regimes and other factors (Sundqvist et al 2013)
N-dimensional hypervolumes defined by vegetative traits, which is the hypervolume with n = 7 vegetative traits as dimensions occupied by the plant species present in each community, were smaller than those defined by n = 6 floral traits (Fig. 1a, paired t test: t7 = 3.24, p = 0.014, based on vol(pn) calculated using ‘gmean’ as aggregation method to enable comparison despite different numbers of traits considered)
Vector analysis in n-dimensional hypervolumes with all vegetative and floral traits as dimensions support the findings found in three-dimensional hypervolumes (Fig. 3c, d)
Summary
Plant communities vary along elevational gradients both taxonomically and regarding the characteristics of their traits, which reflects responses to changing temperature regimes and other factors (Sundqvist et al 2013). Pollination and floral traits are directly linked to plant reproduction and fitness, which are fundamental processes related to biomass gain and species diversity in communities. Both vegetative and floral traits may reflect the plants’ adaptation to the conditions at a given elevation, which would result in predictable changes of trait characteristics along an elevational gradient. Vegetative and floral traits may facilitate resource partitioning among plant species that compete either for light, water, or nutrients or for pollinators. In this scenario, traits dispersion would be large within a given community. The major goal of this study is to test whether vegetative and floral traits differ in their responses to elevation and in trait dispersion within and between communities
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