Functional traits of non-vascular epiphytes influence fine scale thermal heterogeneity under contrasting microclimates: insights from sub-Mediterranean forests

Lichens and bryophytes contribute to regulating the forest microclimate and support ecosystem functions. Exploring the thermal heterogeneity at a trunk-level may help elucidate the effect of thermoregulation of epiphytes. We hypothesized that (i) the thermal patterns of epiphytic communities depend on the microclimatic conditions of the surrounding atmosphere and (ii) the thermal heterogeneity at a trunk-level may in turn depend on functional traits of epiphytic communities, such as thallus colour and growth form. We carried out two measurement sessions under contrasting microclimatic conditions (wet vs. dry). Using a thermal camera, we acquired infra-red (IR) images of 50 trees during the same time period under the contrasting wet and dry conditions. Results showed significant differences in thermal characteristics of the trees when contrasting wet with dry conditions and that colour and growth form were significantly associated with changes in thermal patterns at the trunk-level. The study highlights the importance of understanding the thermoregulatory processes of epiphytic communities.