Figure 1: Water potential links environmental drivers to biophysical responses.

Water flows “downhill” along gradients of water potential in the soils (Ψ_S, where water potential is relatively high, often >-1 MPa) through the stems (Ψ_x) to the leaves (Ψ_L, where potential is relatively low) and eventually to the air (Ψ_air, where it can be as low as −100 MPa). Water potential also directly controls key biological processes, including microbial function, mortality risk arising from damaged plant xylem, and plant-atmosphere gas exchange. While observations of environmental drivers, soil moisture content (θ) and carbon and water fluxes are broadly accessible from environmental networks and remote sensing, Ψ timeseries are more discrete, sparse, and generally not coordinated or discoverable.