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  • Upscaling Sapflow Measurements to Footprint Transpiration Estimations in the Jornada Experimental Range, New Mexico, USA
Title: Upscaling Sapflow Measurements to Footprint Transpiration Estimations in the Jornada Experimental Range, New Mexico, USA
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 Mesquite’s average daily summer (JJAS) transpiration is about 2.9 mm/day, while Creosote’s is 1.7 mm/day. A proportional relationship between the plant’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.  more » « less
Award ID(s):
2025166
PAR ID:
10556949
Author(s) / Creator(s):
Publisher / Repository:
ProQuest
Date Published:
Format(s):
Medium: X
Institution:
The University of Texas at El Paso
Sponsoring Org:
National Science Foundation
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