Blue light is the key factor affecting leaf litter photodegradation

Sunlight impacts litter decomposition in terrestrial ecosystems through the process of photodegradation. Previous studies on litter photodegradation focused on the effects of ultraviolet (UV) radiation, and only recently have the photodegradation effects of other spectral regions of sunlight (e.g., blue and green light) been addressed.

Dr. Wang Qingwei from the Institute of Applied Ecology (IAE) of the Chinese Academy of Sciences (CAS), together with his colleagues, has revealed that blue light is the key factor affecting litter photodegradation.

The study was published in Plant and Soil.

The researchers reviewed the research on photodegradation. Through meta-analysis, they investigated the photodegradation processes of leaf litter of 110 plant species under ambient sunlight.

"Compared to darkness, the full spectrum of sunlight increased rates of litter decomposition by 15% on average across all studies, and blue light alone accounted for approximately 90% of this increase," said Dr. Wang. UV radiation, including UV-A and UV-B, were generally not responsible for global photodegradation in spite of its importance in particular environments.

The researchers also revealed that the rates of photodegradation could be affected by initial litter traits, for example, carbon and lignin contents, lignin to nitrogen ratio and specific leaf area.

The study confirmed that photodegradation is a major driver of litter decomposition, and highlighted that blue light is the predominant driver of plant litter photodegradation across biomes.