Format: ORAL

Eullia Pladevall-Izard, Pau Montan, Jaume Espuny, Aaron Prez-Haase

University of Barcelona

Phenotypic plasticity enables species to adapt to fast environmental changes. Therefore, it may provide a fitness advantage at a short-term response and may evolve through natural selection at long-term scales. Studying phenotypic plasticity in a climate change simulation experiment would allow predicting the viability of populations in their current distribution limits facing global change. Mires are sensitive ecosystems and peat mosses growth determine the ecosystem functioning. In Sphagnum hummocks, maintaining moisture in the apical part of shoots compromises Sphagnum survival, growth, and sexual reproduction. Therefore, many anatomical and morphological traits are key to retain water from precipitation. We carried out a field experiment on Sphagnum capillifolium hummocks in the Pyrenees. We simulated global warming by transplanting Sphagnum shoots from two mires at high altitudes (2190 m and 2340 m a.s.l.) to a subalpine mire (1770 m). We simulated drought by placing transparent roofs and digging ditches around hummocks. After two growing seasons, we analysed the performance of nine anatomical functional traits of Sphagnum shoots from the experiment and of other Sphagnum samples from the donor populations. Sphagnum shoots showed significant changes under drought conditions: leaf hyaline cells were wider and longer, and they had more but smaller pores. These changes coincide with a greater water absorption, transport and retention capacity. Thus, they could be considered an adaptation to drought. Plasticity varied according to donor populations, suggesting a region-specific adaptive potential. However, we could not demonstrate phenotypic plasticity when transplanting samples to lower altitudes, but only to drought conditions. Extended warm and dry summers compromise Sphagnum hummocks in the climatic edge of distribution. The outcome of our study suggests that Sphagnum capillifolium would have the potential for adaptation to future climatic scenarios to some extent. Furthermore, the experiment showed how hummock restorations are feasible using near populations as donors.