Plastic responses of Iris pumila leaf functional traits to experimental warming in situ

Abstract

The ongoing climate change creates critical challenges for plant population persistence innatural communities. To investigate plant responses to future climate warming conditions, weemployed an in situ temperature manipulation experiment in two sun-exposed natural populations of Iris pumila. One half of each randomly chosen clonal plant was experimentally warmed(about 1-2 ºC) using a clear-sided open top chamber (OTC), while the other half faced the ambient temperature conditions. During the summer season, phenotypic values of key functionalleaf traits - leaf dry mass per area (LMA), leaf succulence (SU) and stomatal density (SD) - wererecorded simultaneously on the ramets from each clone growing inside and outside of the OTC.The phenotypic expression of all analyzed traits changed with temperature, being smaller in theramets developing within the OTCs compared to those growing under ambient temperature conditions. Observed difference was found to be statistically signifcant for LMA and SU, while thoserelated to SD could be described as tendency. In addition, the association between the pairs ofleaf and abiotic variables was tested. The recorded soil temperature appeared to be signifcantlyconcordant with SD, but, as well as leaf and air temperature, discordant with SU. Our results suggest that I. pumila plants have the capacity to adjust to rising temperatures by plastic responses ofleaf functional traits. This is of great importance to anticipate the future of Iris populations underupcoming warmer climate.