Using high resolution thermal remote sensing and the limits of species' tolerance to assess local vulnerability to climate extremes

Background/Question/Methods

Climate and land use changes are altering species’ distributions and contributing to extinction risk for many species. Understanding the timing and extent of such shifts is critical for conservation but predictions of how species will respond to change can be limited by the availability of thermal measurements at the scale of species’ habitat use. Current satellite remote sensing measurements are limited in their capacity to detect biologically relevant temperature shifts or microclimates, are difficult to validate with in situ temperature measurements, and a consequence of these limitations is that models of species’ responses to environmental changes can become highly uncertain at the local scales at which species experience their environments. Recent advances in unmanned aerial vehicle (UAV) technology have created opportunities to better evaluate the role of microclimates in local species extinctions. Here, we develop a new method for creating high-resolution maps of microclimates using UAV and thermal imaging technology that overcomes challenges related to limited in situ thermal sensor placement. We produced thermal maps, relative to butterfly species’ thermal limits, at 5cm resolution, and canopy height models (CHM) with 1cm resolution for 15 sites in an alvar ecosystem in Southeastern Ontario.

Results/Conclusions

This remote sensing technique measures the physical and thermal heterogeneity relative to species’ thermal limits, assesses the cumulative impacts of temperatures exceeding those limits, and applies these measurements at a resolution relevant to organismal movement within individual habitats. These models are related to observed butterfly species’ abundances collected concurrently to UAV remote sensing data collection. While measurements of species’ thermal positions can predict extinction risk and colonization potential at broad spatial extents, this is the first time that this technique has been translated and applied to microclimate measurement.