Date of Award

2024-08-01

Degree Name

Master of Science

Department

Environmental Sciences

Advisor(s)

Hernan Moreno

Abstract

This study proposes a new method for computing transpiration across an eddy covariance footprint using field observations of plant sap flow, phytomorphology sampling, uncrewed aerial system (UAS) digital image processing, and eddy covariance micrometeorological measurements. The method is applied to the Jornada Experimental Range, New Mexico where we address three key questions: (1) How do daily summer transpiration rates of Mesquite (Prosopis glandulosa) and Creosote (Larrea tridentate) individuals of different ages compare? (2) How can the contributions of plants of varying sizes and ages be integrated for terrain-wide transpiration estimates? (3) What is the contribution of transpiration to total evapotranspiration within the eddy covariance footprint? Data collected from June to October 2022, during the North American Monsoon season, include hourly evapotranspiration and precipitation rates from the Ameriflux eddy covariance system (US Jo-1 Bajadasite) and sap flux rates from heat-balance sensors. We used plant biometric measurements and supervised classification of RGB imagery to upscale from the patch- to footprint-scale estimations. Our results show that Mesquiteâ??s average daily summer (JJAS) transpiration is about 2.9 mm/day, while Creosoteâ??s is 1.7 mm/day. A proportional relationship between the plantâ??s horizontal projected area and the number of water flow conduits was extended to the eddy covariance footprint via UAS data. The summer transpiration to evapotranspiration ratio (T/ET) was 0.52, increasing to 0.83 following significant precipitation in September 2022. Further testing of this method is needed in different regions to validate its applicability. With appropriate adjustments, it could be relevant for other areas with similar ecological conditions.

Language

en

Provenance

Recieved from ProQuest

File Size

56 p.

File Format

application/pdf

Rights Holder

Habibur R Howlider

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