ABSTRACT

Forests cover can significantly reduce the amount of rainfall reaching the ground and alter its chemistry. This process, called "interception," impacts water paths, soil erosion, and stormwater management costs. There are three major parts of the forest canopy: bark, leaves and epiphytes (the plants that live on the canopy). The effect of epiphytes on rainfall interception is not well understood, yet they can live in any forest ecosystem and represent some of Earth?s most water-absorbent land organisms. This study addresses this knowledge gap by monitoring interception variables for a southeastern US forest that hosts 3 major types of epiphytes that differ in how the intercept rainfall (lichen, resurrection fern, and Spanish moss). The study will involve multiple measurements in water and epiphytes, as well as monitoring weather conditions. Results will inform water and forest managers about conservation efforts for epiphyte-rich forests. The research will be led by primarily Undergraduate Institutions and will train undergraduate students in cutting-edge science. Outcomes of the project will be incorporated into educational outreach efforts reaching thousands of K-12 (kinder to twelfth grade) and undergraduate students, high school teachers, and community members. It will also provide research experiences to members of underrepresented groups, including those associated with African American economically disadvantaged, and military communities.

The first process in the rainfall-to-discharge hydrologic flow path in vegetated ecosystems is the partitioning of rain by forest canopies. Rain-canopy interactions have been documented to impact stormwater runoff and infrastructure costs, supply hundreds of kilograms of dissolved solutes per ha per year to soils and mitigate regional warming. A major process that has been overlooked on this topic is the role of epiphytes (plants that structurally live on canopies). Since epiphytes are ubiquitous across forest ecosystems and many can store >1000% of their dry weight in water, excluding these organisms significantly impacts canopy water balances and related solute exchanges. This study addresses this major knowledge gap at a forest with high biomass of 3 common types of epiphytes (lichens, ferns and bromeliads) that represent a water-control continuum, from poikilohydric (no internal water control, like lichens) to homoiohydric (presence of internal water controls, like the bromeliad, Spanish moss). Principal objectives are to: (1) assess storage, evaporation and drainage dynamics for these epiphytes; (2) evaluate ecohydrological traits that underlie epiphyte?s water balance and determine their vulnerability to projected changes in climate; (3) quantify epiphyte alterations to rainfall inorganic solute characteristics; and (4) scale findings to estimate current and future relative stand-level influence of epiphytes. Addressing these objectives may alter estimates and predictions of major hydrological processes linked to climatologically relevant energy exchanges and ecologically critical mass exchanges. The project will support 1 post-doctoral scholar and 6 undergraduate students to receive substantial research experiences (field work, instrumentation, data collection and processing, modeling and model evaluation, manuscript preparation, and results presentation) in a timely & critical subfield at the intersection of eco-hydrology and hydrometeorology. The project will also disseminate information to broad audiences through websites, workshops, interpretative signs installed in the study forest area, sequential art, including graphic novellas and character designs, and a time-lapsed video to be featured in a leading educational YouTube channel with international viewership (MinuteEarth).

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

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