Fitness and growth of the ephemeral mudflat species Cyperus fuscus in river and anthropogenic habitats in response to fluctuating water-levels

Jörg Böckelmann,Karin Tremetsberger,Kateřina Šumberová,Heinrich Grausgruber,Karl-Georg Bernhardt

doi:10.1016/j.flora.2017.07.012

Abstract

Cyperus fuscus is a representative of threatened ephemeral wetland plant communities in summer-dry shoreline habitats. We compared variation and plasticity in traits related to fitness and growth of plants germinating from the soil seed bank and established plants from river and secondary anthropogenic habitats. Plants from sites at rivers, fishponds and fish storage ponds were cultivated and selfed to get homogenous seed material for a germination and an environmental manipulation experiment involving three different water regimes. Differences in traits and their plasticities were evaluated by means of linear mixed models. Cyperus fuscus followed a low-oxygen escape strategy when flooded. Seeds of plants derived from the soil seed bank germinated faster than seeds of plants derived from established plants suggesting that short-term selection of genotypes is mediated by the particular conditions on the site during germination. The experiment revealed significant differences between river and secondary habitats as well as between the soil seed bank and established plants. For example, plants from river habitats produced the highest number of culms with inflorescences. The difference was most evident under partial submergence. Plants from fish storage ponds rapidly reached the reproductive phase, but produced less culms with inflorescences. This seemingly allows them to cope with numerous and irregular disturbances and intensive substrate moisture changes. Our results suggest that populations have adapted to conditions at secondary habitats provided by fish farming during the last centuries.

Highlights

Habitat loss and degradation are the primary environmental causes of biodiversity decline at local, regional and global scales (van Vuuren et al, 2006)
Cyperus fuscus followed a low-oxygen escape strategy to avoid the negative effects of partial submergence by growing taller when submerged (Voesenek et al, 2004; BaileySerres and Voesenek, 2008)
Leaves responded in a similar way, but leaf length did not further increase under severe flooding in comparison to moderate flooding, as it was the case for the culms, possibly due to reduced carbohydrate reserves to invest in longer leaves

Summary

Introduction

Habitat loss and degradation are the primary environmental causes of biodiversity decline at local, regional and global scales (van Vuuren et al, 2006). For both species and ecosystems, many of the changes assumed for the 21 st century can be best described as shifts in potential distribution, with favorable conditions vanishing in some places, which may cause local extinctions, and appearing in new places, which may result in colonizations (Pereira et al, 2010). Evolution can lead to specialization, generalization or adaptive phenotypic plasticity (Anderson et al, 2014). Generalization and adaptive phenotypic plasticity may evolve, when the individuals must face multiple environmental conditions during their or their parents’ lifetime (Anderson et al, 2014)

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Conclusion