Observed water and light limitation across global ecosystems

Abstract. With a changing climate, it is becoming increasingly critical to understand vegetation responses limiting environmental factors. Here, we investigate the spatial and temporal patterns of light water limitation on photosynthesis using an observational framework. Our study unique in characterizing nonlinear relationships between light, acknowledging approximately two regime behaviours (no varying degrees limitation). It also framework instead model-derived properties. We combine data from three different satellite sensors, i.e., sun-induced chlorophyll fluorescence (SIF) TROPOspheric Monitoring Instrument (TROPOMI), surface soil moisture Soil Moisture Active Passive (SMAP) microwave radiometer, greenness Moderate Resolution Imaging Spectroradiometer (MODIS). find both single-regime two-regime models describe SIF sensitivity photosynthetically active radiation (PAR) across globe. The distribution strength are mapped water-limited environments, while PAR limitations energy-limited environments. A behaviour detected 73 % cases for photosynthesis, detection much lower at 41 photosynthesis. strongly increases along gradients, reflecting mesic vegetation's adaptation making rapid usage incoming availability weekly timescales. transition point regimes connected type mean annual precipitation SIF–soil relationship SIF–PAR relationship. These thresholds therefore have explicit relation properties landscape, although they may be related finer details interactions not resolved by scales here. simple functions emergent capturing interaction many processes. coupling can used as benchmark information Earth system models, especially those that characterize gross primary production mechanisms dynamics.