Relationships between lichen functional traits, microclimate, and ecosystem functions: tools for studying global change

This doctoral thesis investigates the relationship between microclimate, nonvascular epiphytic communities, and their environment, focusing on three main objectives. First, it explores how microclimatic factors influence epiphytic communities, particularly in terms of water dynamics and thermal patterns. The research highlights the poikilohydric nature of nonvascular organisms, examining their hydration responses and the management of water resources within these communities. Furthermore, an innovative tool has been used to map water distribution with the aim of deeply understand how different epiphytic organisms, such as lichens and bryophytes, interact with their environment during dehydration cycles. Indeed, the management of water indirectly influences the superficial thermal patterns of nonvascular epiphytic communities, which, at their scale, can be implied in the ecosystem function. The second objective examines how microclimatic variations affect lichen physiology, specifically their response to acute thermal stress. The study also models the effects of different climatic conditions on lichen survival and photosynthetic activity at various growth stages, providing insights into how environmental factors shape the functional traits of lichens. The third part focuses on the influence of microclimate on biotic interactions, particularly between lichen communities and epiphytic invertebrates. The research emphasises the role of lichens as micro-refuges, highlighting how community composition can drive invertebrate assemblages by modifying the surface microclimate. This work sheds light on the broader ecological functions of nonvascular epiphytes and their dynamic responses to changing environmental conditions.