Leaf Hydrophobicity and Canopy Storage Relationships of Common Species in Semi-Arid Environments of the Western United States

点击翻译按钮获取中文摘要

The repellency of a water droplet by a leaf surface (i.e., leaf hydrophobicity) is a common adaptation among plant species in habitats exposed to daily precipitation. Leaf hydrophobicity may be an important variable that influences canopy storage capacity during a rainfall event. Canopy storage capacity is the amount of water held by the canopy during a rainfall event before water starts to drip as indirect throughfall. Species with highly repellent leaf surfaces may increase the quantities of throughfall at a site and result in greater hydrological inputs beneath the canopy. Professor Curtis Holder in the Department of Geography and Environmental Studies at the University of Colorado at Colorado Springs will examine the extent to which leaf hydrophobicity influences canopy storage capacity in common species of the semi-arid Western United States. Specifically, the three objectives of this project are to determine if leaf hydrophobicity and canopy storage capacity differs between species with contrasting leaf habits and growth forms, to compare methodologies that calculate leaf hydrophobicity and canopy storage capacity, and to determine if leaf hydrophobicity influences canopy storage capacity on a leaf area basis. To address these three objectives, the investigator will measure canopy storage capacity by a mass-balance approach with rainfall simulation and an immersion method. Additionally, the investigator will measure leaf hydrophobicity by calculating the contact angle between a water droplet and the leaf surface using a digital camera and goniometer. Canopy characteristics (leaf and woody area, leaf orientation, and leaf surface properties) of each species will also be determined. If differences in leaf hydrophobicity and canopy storage capacity between species are significant, then hydrological inputs to a watershed may be significantly influenced by vegetation changes. Within this context, this project will increase our understanding of hydrological processes and inform the planning and management of vegetation cover in watersheds contributing as raw water source regions for municipalities. This project will enhance our understanding of hydrologic fluxes within watersheds by examining the significance of leaf hydrophobicity as a mechanism that influences canopy storage capacity. By measuring leaf hydrophobicity and canopy storage capacity of common species within a watershed, this project will provide information on the significance of leaf hydrophobicity in forest hydrology models that could enhance our understanding of the delivery of water resources from municipal watersheds. Several undergraduate and graduate students will receive valuable educational opportunities by participating directly in field data collection during this project.