[1] The fraction of absorbed photosynthetically active radiation, fAPAR, is an important biophysical characteristic in models of gas exchange between the terrestrial boundary layer and the atmosphere, as well as in the analysis of vegetation productivity. Synoptic estimation of fAPAR has been performed by using NDVI as a linear proxy of fAPAR, despite the saturation of NDVI at fAPAR beyond 0.7....

Decomposition of leaf litter is a key component of biogeochemical cycles but the mechanisms driving it in arid and semiarid ecosystems (drylands) remain unresolved. Here, we review recent findings that demonstrate dual roles of solar radiation (ultraviolet and photosynthetically active radiation) and soil–litter mixing as drivers of decomposition in drylands. We focus on the known and potential...

Photosynthesis is fundamentally driven by photon flux rather than energy flux, but not all absorbed photons yield equal amounts of photosynthesis. Thus, two measures of photosynthetically active radiation have emerged: photosynthetic photon flux (PPF), which values all photons from 400 to 700 nm equally, and yield photon flux (YPF), which weights photons in the range from 360 to 760 nm accord...

Colonies of Stylophora pistillata maintained for four years in indoor aquaria in the near absence of ultraviolet radiation (UVR) contained only small amounts (,5 nmol mg21 protein) of 10 identified mycosporine-like amino acids (MAAs, which act as UV sunscreens), the largest number reported in any organism. The concentrations of most MAAs increased linearly or exponentially when colonies were ex...

GSRad (global solar radiation) is a software component containing models to estimate extra-terrestrial and ground-level solar radiation (global and photosynthetically active; direct, diffuse, and reflected components) from alternative methods. Radiation data are estimated as either 1-h or 24-h values. Moreover, GSRad provides methods to compute clear sky transmissivity, slope and aspect angles ...

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