Local experimental growth rates respond to macroclimate for the lichen epiphyte Lobaria pulmonaria

Background: Bioclimatic models are widely applied in biogeography and conservation biology; however, the functional relevance of macroclimate as an explanation for species performance (e.g. establishment, growth and survival, fecundity) has been challenged. Aims: In this study, we aimed to determine whether the ecological performance of an epiphytic lichen is related to coarse-grained macroclimate. Methods: A meta-analysis was carried out to compare local growth rates for a lichen epiphyte, Lobaria pulmonaria, to coarse-grained interpolated climate surfaces. Growth rates were sampled from small-scale experiments conducted within different forest settings and for different regions of the world. Generalised linear mixed models were used to compare thallus growth (response) to a suite of climatic variables derived from the WorldClim dataset. Results: A significant relationship between thallus growth measured for experimental forest microhabitats and macroclimatic variables (total precipitation and annual mean temperature) was found. This relationship was validated through a comparison with L. pulmonaria's North American range for which projected growth rates were higher and lower where the species tended to be present and absent, respectively. Conclusions: The ecological relevance of coarse-grained macroclimate applied in bioclimatic modelling has been challenged. We show that the use of macroclimatic data may be functionally defensible where correlated with independent measures of local ecological success.