Ecomorphology of Stomata in Temperate Ferns Under Contrasting Environments
Stomata are crucial structures for plants to better adapt themselves to the environment, in relation to many ecological variables. In this sense, it is widely accepted that (a) stomatal size is much more genetically fixed than density, which can be dynamically modified in new leaves to adjust them to changing conditions and (b) density is expected to increase with light and to decrease with water availability. These statements come from research done mainly for the angiosperms and gymnosperms, whilst ferns remain highly understudied. The main objective of this work is to investigate the relationship between morphological traits of fern stomata and light and water environments. We selected 15 species of different ecological preferences, representing contrasted habitats of light and water. Fifteen to twenty individuals of each species were sampled, and from each one, we chose three different adult fronds. One measurement of density and five measurements of stomata length were done under OM in each frond. The functional variable potential conductance index (PCI) has been calculated from length and density and used as a proxy of transpiration area. This study allows extending the knowledge of ecomorphology of stomata in temperate fern species. Generally speaking, these ferns behave in similar ways to other known plant groups: length has more genetic significance, whilst density is usually modified depending on the environment. However, temperate ferns seem to modify density by modifying ordinary epidermal cells instead of size of stomata, a fact that is known only for a small number of angiosperms. Species that inhabit low water availability environments (exposed rocks, crevices and cliffs) developed significant shorter stomata, but at higher densities and with higher potential conductance, species from low light availability environments (shadowed rocks and forests) have longer stomata and lower density. These results increase the knowledge on how temperate ferns can adapt their bodies to occupy different ecological niches.
KeywordsAdaptation Ecology Forests Light environment Morphology Rocks Water availability
This work has been partially funded by Universidad Complutense Research Groups Programme (“Biodiversity and Taxonomy of Cryptogamic Plants”, UCM 910801) and by the EU-ERASMUS mobility programme. We thank the curator of MACB herbarium for her willingness to facilitate us the use of the material.
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