Variation of surface thermal heterogeneity and water dynamic within nonvascular epiphytic communities during a dehydration cycle
ID: 613 / 423
Proposed Symposium Title: Variation of surface thermal heterogeneity and water dynamic within nonvascular epiphytic communities during a dehydration cycle
G. Canali1, P. Hurtado Aragüés2,3, R. Rocha de Oliveira4,5, S. Gariglio4, C. Malegori2, P. Giordani2
Affiliations: 1 Department of Earth Sciences, Environment and Life, University of Genoa, Genova, Italy; 2 Department of Pharmacy, University of Genoa, Genova, Italy; 3 Área de Biodiversidad y Conservación, Universidad Rey Juan Carlos, Mostoles, Spain; 4 Department of Chemistry and Industrial Chemistry, University of Genoa, Genova, Italy; 5 Department of Chemical Engineering and Analytical Chemistry, Universitat de Barcelona, Barcelona, Spain
Nonvascular epiphytic communities include poikilohydric organisms, such as lichens and bryophytes which lack organs for active water uptake and regulation of thermal and gas exchange. Furthermore, they have no protective tissues, therefore they directly respond to fluctuations of ambient environment also for gas exchange and light. Shifting the perspective to the epiphytic scale, functional traits of lichens and bryophytes could act as effect traits influencing the surrounding temperature through the exchange of water and heat at the substrate-atmosphere interface. In this work, we hypothesised that the composition of nonvascular epiphytic community may affect the water availability and, consequently, the surface thermal pattern. We verified if i) in a dehydration process, the epiphytic water content and their thermal pattern co-varies following a trend linked to the community composition; and if ii) the greater thermal heterogeneity is linked to a more diverse epiphytic community. To test these hypotheses, we selected 32 different epiphytic community samples. Then, we monitored them during the dehydration process by regularly weighting the samples and capturing InfraRed images every 40 minutes. Using structural equation modelling, we evaluated the relationships between epiphytic communities, water-related variables and surface thermal pattern. The results confirmed our hypotheses: community composition showed both a direct effect on thermal patter and an indirect effect mediated by water content and dehydration dynamic. Community dominated by foliose lichens and bryophytes exhibited higher water content, less water loss and lower temperatures pattern. Conversely, communities with a greater cover of crustose lichens showed a faster water loss and an higher temperatures pattern. Hence, a more diversified community will have greater thermal heterogeneity.