A spectral weighting function for abiotic photodegradation based on photochemical emission of CO2 from leaf litter in sunlight

Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2020

“…Recent assessments have emphasised the important role played by solar radiation in driving carbon cycling through litter decomposition to CO 2 in dryland ecosystems [ 149 , 167 ]. Since our last assessment [ 1 ], additional studies have provided more details about the significance of photodegradation in dry systems including an arid grassland [ 295 ], the Sonoran Desert [ 296 ], a semi-arid scrub system [ 297 ], and a semi-arid woodland ecosystem [ 298 , 299 ] (contributing towards SDG targets 15.1, 15.3). Other studies since our last assessment have shown that photodegradation is also associated with plant litter (dead plant material) decomposition in wetter ecosystems located in temperate and boreal forests [ 300 – 302 ].…”

“…Spectral weighting functions quantify the relative effectiveness of radiation, by wavelength, on photodegradation processes in aquatic [ 312 ] or terrestrial [ 296 ] environments. These functions are used to evaluate and compare the results from experiments examining the effect of radiation.…”

“…In terrestrial ecosystems, spectral weighting functions developed for photodecomposition of litter from the Sonoran Desert [ 296 ] showed that UV-A radiation was the most effective region of the solar spectrum in the photodegradation of leaf litter (Fig. 11 ).…”

“…11 a Mean weighting function for photodegradation to CO 2 from all litter types, with 95% CI, along with average solar noon spectral irradiance; b weighted solar noon irradiance, along with the total percentage effectiveness of the solar UV-B, UV-A and visible wavebands. Adapted from Day and Bliss [ 296 ] …”

Ecology: The Patagonian Sun Dance

“…This is because, as most of UV-B is filtered by the atmosphere, there is much more UV-A and visible radiation reaching plant tissues than UV-B. Consequently, these wavelengths have been estimated to be responsible for 90% of the photochemical CO 2 emission [15].…”