Astronomical events influence many of Earth’s physical processes and in turn are important in understanding ecological patterns through space and time. One such event, a total solar eclipse, acts as a unique atmospheric experiment by reducing the amount of solar radiation reaching Earth’s surface across both space and time, which sequentially influences abiotic environmental conditions. Temperature has long been understood as a fundamental abiotic condition that structures ecological patterns and processes, and is governed locally by patterns of heterogeneity within a landscape. A primary determinant of heterogeneity within landscapes is vegetation structure and composition, which serve to change microclimatic conditions by blocking solar radiation. To understand the magnitude of influence that vegetation structure and composition have on thermal patterns, we quantified thermal landscape dynamics through both space and time in a fragmented grassland during the August 21st, 2017 total solar eclipse. We report on the first use of a distributed temperature sensing (DTS) system in a natural landscape during such an event, which allowed us to measure thermal conditions as a continuous profile through the use of fiber optic cables (1 km in length) and laser pulse generators at spatial and temporal resolutions of 1 m and 1 minute, respectively.
Results/Conclusions
The measured thermal landscape decreased from a maximum of 52.6°C to a minimum of 30.6°C during the solar eclipse. This is compared to a decrease in ambient temperatures from 33.3°C to 30.6°C that was quantified at a weather station 800 m from our study site. The greatest change in temperatures during the eclipse occurred within mixed grass vegetation, while the least amount of change occurred in Juniperus virginiana canopies. Spatial autocorrelation of temperatures along the thermal cable were similar 10 minutes before and after the solar eclipse in the landscape (semi-variogram range = 74.9 and 76.8 m, respectively). However, during the peak of the solar eclipse, the semi-variogram range increased to 90.6 m due to homogenization of thermal conditions. Furthermore, the magnitude of thermal heterogeneity (through estimation of partial sills) 10 minutes before and after the eclipse was 15.4 and 30.4 times greater than during the peak of the eclipse, respectively. These results illustrate the importance of landscapes functioning as thermal moderators through modification of solar radiation levels reaching Earth’s surface. By quantifying changes in temperatures through space and time during the eclipse, we illustrate that patterns of thermal heterogeneity facilitated through vegetation cover are highly dynamic across spatio-temporal scales.