Interweaving Monitoring Activities and Model Development towards Enhancing Knowledge of the Soil-Plant-Atmosphere Continuum

Abstract

The study of water pathways from the soil to the atmosphere through plants—the so-called soil–plant–atmosphere conƟ nuum (SPAC)—has always been central to agronomy, hydrology, plant physiology, and other disciplines, using a wide range of approaches and tools. In recent years, we have been witnessing a rapid expansion of interweaving monitoring acƟ viƟ es and model development related to SPAC in climaƟ c, ecological, and applicaƟ ons other than the tradiƟ onal agrohydrological, and it is therefore Ɵ mely to review the current status of this topic and outline future direcƟ ons of research. The iniƟ aƟ ve for the special secƟ on of Vadose Zone Journal on SPAC emanated from several sessions we recently organized in internaƟ onal conferences and meeƟ ngs. With a view to the specifi c research quesƟ ons covered in this special secƟ on, this arƟ cle introduces and reviews SPAC underlying issues and then provides a brief overview of the invited contribuƟ ons. We have grouped together the 15 contribuƟ ons under three main secƟ ons related to the local, fi eld, and landscape spaƟ al scales of interests. Within these secƟ ons, the papers present their innovaƟ ve results using diff erent measuring techniques (from classic tensiometers and TDR sensors to more advanced and sophisƟ cated equipment based on tomography and geophysics) and different modeling tools (from mechanisƟ c models based on the Richards equaƟ on to more parametrically parsimonious hydrologic balance models). They provide a snapshot of the current state of the art while emphasizing the signifi cant progress aƩ ained in this fi eld of research. New technological developments and applicaƟ ons are also highlighted. AbbreviaƟ ons: SPAC, soil–plant–atmosphere conƟ nuum Soil is a key component of the earth’s biosphere linking surface water and groundwater and the atmosphere. Most soil hydrological processes take place over vegetated land areas, and therefore the plant rooting system becomes the most active zone for transfer of water (and dissolved nutrients) between soil and atmosphere through the plants.