Predicting ecological responses to global warming in Iris pumila: an open-topped chamber experiment

Abstract

To predict short-term plant responses to global warming, an open-topped-chamber experiment was conducted in two sun-exposed natural populations of Iris pumila during a growing season. In each population, one half of all randomly selected clonal plants were experimentally warmed using a clear-sided, open-topped chamber (OTC), while the other half experienced the ambient temperature conditions. The air temperature within the OTCs was approx.1-2 ºC higher than that outside of the OTCs in general. In spring and summer of 2018, phenotypic values of the three functional leaf traits: specific leaf area (SLA), leaf dry mass content (LDMC), and leaf water content (LWC) were recorded on the ramets from each clone growing inside and outside of the OTC. The phenotypic expressions of all analyzed traits changed significantly with temperature in both populations, but in an opposite direction. While SLA and LWC tended to be greater in the ramets developing within the OTCs relative to those growing outside of them, their LDMC values reversed, being higher inside than outside of the OTCs. The analyzed traits varied seasonally as well. Regardless of the location within a clone, the values of SLA and LWC were greater in spring then in summer. Conversely, LDMC reached its maximum in the warmer season. Our results clearly suggest that I. pumila plants have the capacity to cope with increasing temperatures by plastic responses of leaf functional traits. This finding is of crucial importance to forecast the fate of Iris populations under global warming - that is, whether they will adopt or disappear.