Linking managed and natural ecosystems through evapotranspiration and NASAs upcoming ECOSTRESS mission

Authors: SPATER, MOLLY - National Aeronautics And Space Administration (NASA); KIM, SOL - National Aeronautics And Space Administration (NASA); KUCERA, LEAH - National Aeronautics And Space Administration (NASA); FISHER, JOSHUA - National Aeronautics And Space Administration (NASA); LEE, CHRISTINE - National Aeronautics And Space Administration (NASA); French, Andrew

Submitted to: Earthzine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/14/2017
Publication Date: 6/14/2017
Citation: Spater, M., Kim, S., Kucera, L., Fisher, J., Lee, C., French, A.N. 2017. Linking managed and natural ecosystems through evapotranspiration and NASAs upcoming ECOSTRESS mission. Earthzine. https://earthzine.org/2017/06/14/linking-managed-and-natural-ecosystems-through-evapotranspiration-and-nasa-upcoming-ecostress-mission/.

Interpretive Summary: We are now in a world of increased climatic variability, which necessitates the ability to monitor the impacts of drought on vegetation in managed and natural ecosystems as an integrated unit. Heat and water stress damage essential physiological functions of plants with the potential to devastate yield and escalate rates of species richness loss by reducing community resistance to extreme conditions. Until now monitoring tools suited for multiple scales have been unavailable. However in the next year NASA will launch a thermal infrared sensor called ‘ECOSTRESS’ that will enable monitoring of water use by plants at fine scales: hourly to daily at 40-80 meter resolution. To be prepared for this mission a study was undertaken to evaluate the impact of water use at local and global scales using thermal infrared observations. In a Maricopa, Arizona cotton study conducted in 2013 and 2014, thermal data revealed the dominant influence of plant variety upon heat drought stress. This dominance was confirmed over multiple biomes at global scales, where evapotranspiration was strongly affected by richness of plant diversity.

Technical Abstract: Evapotranspiration (ET), the combination of evaporation from the Earth’s surface and transpiration from plants, is an environmental variable able to capture information about both the hydrological and energy cycles -- two known determinants of plant life. Measures of ET record stomatal response to water stress via changes in canopy temperature. With the impending launch of the NASA ECOSTRESS sensor, there is an emerging potential to observe and interpret ET at multiple spatial and temporal scales. To be prepared to interpret these observations, we explored the utility of ET to identify water-efficient crops at the local scale and to track larger changes in species richness at the global scale. For the local scale we analyzed ET and thermal infrared temperatures collected over a two-year cotton experiment, 2013-2014, conducted at Maricopa, Arizona. The experiment evaluated the effects of heat and drought stress on 35 different cotton varieties under two levels of irrigation. For the global scale, we assessed monthly 0.5º x 0.5º resolution thermal data collected from the Advanced Very High Resolution Radiometer (AVHRR) and from the International Satellite Land Surface Climatology Project, Initiative II (ISLSCP II) for correspondence between ET and species richness across 867 ecoregions. Results from infrared temperatures observed at local scales showed that cotton variety dominated the drought and heat response. This finding was confirmed by ET results at global scale, which showed that water availability was most sensitive to higher biodiversity in equatorial regions, while water availability at mid-latitudes was dominated by seasonality effects.