Soil–plant–atmosphere continuum

In this chapter, we describe research for understanding how living systems function in the soil–plant–atmosphere continuum (SPAC). Through process-based modeling and earth observations it is evident that whole ecosystems function as living entities. Process-based models and observations at the cellular to plant canopy level of water, energy and carbon exchange have given us a significant understanding of how living systems function through the SPAC--creating and maintaining their biomes. However, a major and continuing challenge is how SPAC processes scale up to the regional and global scales. We provide an insight to this scaling challenge by describing how water movement, key to sustaining life on Earth, is being quantified at multiple scales, and by discussing the need to incorporate remote sensing as a means of bridging from plant level water use to whole ecosystems and up to global scales. To accomplish this scaling, SPAC research requires integrating multi-sensor remote sensing data over the full electromagnetic spectrum, incorporating commercial satellite observations, and employing not only process-based models but data assimilation, and machine learning techniques with cloud computing.