Confronting the water potential information gap

Water potential directly controls the function of leaves, roots and microbes, and gradients in water potential drive water flows throughout the soil-plant-atmosphere continuum. Notwithstanding its clear relevance for many ecosystem processes, soil water potential is rarely measured in situ, and plant water potential observations are generally discrete, sparse, and not yet aggregated into accessible databases. These gaps limit our conceptual understanding of biophysical responses to moisture stress and inject large uncertainty into hydrologic and land-surface models. Here, we outline the conceptual and predictive gains that could be made with more continuous and discoverable observations of water potential in soils and plants. We discuss improvements to sensor technologies that facilitate in situ characterization of water potential, as well as strategies for building new networks that aggregate water potential data across sites. We end by highlighting novel opportunities for linking more representative site-level observations of water potential to remotely sensed proxies. Together, these considerations offer a road map for clearer links between ecohydrological processes and the water potential gradients that have the 'potential' to substantially reduce conceptual and modelling uncertainties. Continuous and discoverable observations of water potential could vastly improve understanding of biophysical processes throughout the soil-plant-atmosphere continuum and are achievable thanks to recent technological advances.

Automated summary

Water potential plays a crucial role in the functioning of leaves, roots, and microbes, as well as driving water flows in the soil-plant-atmosphere system. However, the measurement of water potential in situ is rare and observations of plant water potential are limited and not widely accessible. This hinders our understanding of biophysical responses to moisture stress and introduces uncertainty into hydrologic and land-surface models. In this paper, the potential gains of continuous and discoverable observations of water potential are outlined, along with improvements in sensor technologies and strategies for data aggregation. Linking representative site-level observations to remote sensing proxies is also highlighted as a novel opportunity. Overall, this paper provides a roadmap for improving our understanding of biophysical processes through continuous and discoverable observations of water potential.