Plant canopy influences on local temperature regimes: radiometric to kinetic considerations across spatial scales

Abstract:

A growing body of evidence shows that changes in canopy structure and composition, including transitions between forests, grasslands, and croplands, can profoundly influence local temperature regimes. For example, temperate and tropical forests tend to cool the surface when compared to nearby grasslands and croplands. Consequently, there is a heightened need to consider the thermal impacts of proposed natural climate solutions alongside with their carbon cycle benefits. Much of this work has historically been limited to evaluating how canopy characteristics influence surface temperature, which can be measured by satellites or radiometers positioned on flux towers. While surface temperature remains a key variable, arguably air temperature within the atmospheric boundary layer is the more climate-relevant target (e.g. measures such as global warming potential). Moreover, quantifying (empirically) the energy balance consequences of altered canopy cover has largely been limited to comparison of ecosystems co-located within a similar climate regime (i.e. paired sites). At larger spatial scales, variation in macroclimate confounds efforts to attribute variations in temperature to plant cover changes. In this talk, new strategies are discussed for: 1) leveraging flux tower energy balance measurements to uncover how plant canopies simultaneously alter surface and air temperature, and 2) merging meteorological reanalysis data and site-level meteorological measurements to deconvolve how canopy function is affecting temperature regimes without relying on paired site approaches. The usefulness of these approaches for elucidating how Eastern US forests representing different water use strategies (i.e. isohydric, anisohydric) mediate local temperature regimes before and during periods of hydrologic stress is also discussed.