2025 CSDMS meeting-059
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A novel model uncovers the importance of dew deposition for canopy epiphytes in a tropical montane cloud forest
David Carchipulla-Morales,
(he/him/his),Wake Forest University Winston-Salem North Carolina, United States. carcpd21@wfu.edu
Tropical montane cloud forests (TMCFs) are ecosystems with high biodiversity that are threatened by deforestation, land use changes, and climate change. One of the unique aspects of TMCFs is the high biomass and diversity of epiphytes. Epiphytes are vascular and non-vascular plants that live in tree canopies, creating arboreal micro-ecosystems. They provide ecological services by capturing and retaining allochthonous nutrients from rain and fog, and by supporting the presence of canopy pollinators and other fauna. Predicted changes in cloudiness and land conversion threaten the abundance of epiphytes, and thus their capacity to contribute to ecosystem functions. However, how losses in epiphyte abundance will affect microclimate and host tree water status is still unclear and requires the ability to simulate the role of epiphytes in canopy water storage dynamics. We developed a water balance model for epiphytes in TMCFs. We consider epiphytes in the host tree as a water store inside the canopy that is filled via vertical and horizontal precipitation, and depleted via evapotranspiration and host tree water uptake. We tested the model using idealized and observed dry season conditions for TMCFs in Monteverde, Costa Rica. Results from the idealized and real model simulations capture how epiphytes regulate water and energy fluxes in the canopy at diurnal scales, and are consistent with observations. A key result is that dew deposition may recharge up to 34% of epiphyte water storage lost due to evapotranspiration over a 3-day dry-down event. We also found that energy and water mass balances are sensitive to the water storage size, i.e. the maximum water content and the abundance of epiphytes in the canopy. Our results provide the first quantitative demonstration of how epiphytes regulate temperature in TCMFs. This work sets the foundation for developing a process-based understanding of the effects of climate change on TMCF eco-hydrology.
