litter photodegradation under UV radiation: Global pattern and controlling factors

Photodegradation caused by solar radiation is widely recognized as a significant factor influencing litter decomposition and nutrient cycling across ecosystems. To comprehensively assess its impact, we conducted a meta-analysis of 27 published studies focusing on the effects of UV radiation on litter decomposition in situ. Our analysis aimed to identify how various experimental and environmental factors modulate these effects. In arid ecosystems, reducing UV radiation significantly increased the remaining litter mass by 18.63%, whereas in semi-arid ecosystems, this effect was observed to a lesser extent at 2.74%. In arid ecosystems, mean annual temperature (MAT) and altitude were identified as controlling factors for litter photodegradation, while in other ecosystems, litter quality played a predominant role. Despite these variations, the meta regression result in arid and other ecosystems was consistent, whereas semi-arid ecosystems exhibited a contrary trend. Our meta-analysis contributes to a deeper understanding of litter photodegradation dynamics, highlighting its variability across ecosystem types, climatic conditions, litter chemical characteristics, decomposition durations, and experimental methodologies. These insights enhance our ability to predict how terrestrial nutrient cycling will respond to future increases in aridity due to global changes.