Collaborative Research: RUI: Will Climate Change Lead to System Shifts on Tropical Mountains?: The Interplay of Epiphyte Losses on Host Tree Function, Microclimate, and Hydrology

Collaborative Research: RUI: Will climate change lead to system shifts on tropical mountains?: the interplay of epiphyte losses on host tree function, microclimate and hydrology. PI: Sybil G. Gotsch, University of Kentucky, Co-PIs: Todd E. Dawson, University of California- Berkeley; Lauren Lowman, Wake Forest University; Nalini M. Nadkarni, University of Utah Abstract Tropical Montane Cloud Forests (TMCFs) are under threat due to rapid changes in climate and in fact, recent work suggests that this ecosystem is predicted to contract substantially in the coming decades. In this proposal we address the following timely and important question: How will a loss of the diverse and abundant epiphyte communities in the TMCF impact tree health, energy balance and hydrologic function? We propose to conduct the first large-scale epiphyte removal experiment, in which we strip trees in forest and pasture of their entire epiphyte community. We will measure changes in crown-level microclimate (air temperature, relative humidity, leaf wetness, wind speed, solar radiation) as well as growth, water relations (water potential, sap flow, stomatal traits, carbon isotopes) and ecohydrological parameters (soil moisture, throughfall, stemflow) in and under the trees stripped of their epiphytes and compare those with paired trees with intact epiphyte communities (N= 20 trees). Direct field-based measurements will be coupled with remotely sensed parameters (NDVI, Air Temperature, Leaf Water Content) using a high-precision drone outfitted with an integrated multispectral imaging system. We will construct a numerical model of epiphyte- host tree water relations and couple this model to a land-surface hydrology model to scale up our field-based measurements and predict the effect of this loss on regional energy budgets and canopy water cycling. We will integrate our broader impacts activities to complement our intellectual merit outcomes throughout the course of our research. Field work will take place in five locations in the Monteverde Region of Central Costa Rica.