UV radiation doubles microbial degradation of standing litter in a subtropical forest

Abstract

1. UV radiation has been recognized as a direct driver of litter decomposition by photodegrading organic matter in dryland ecosystems. However, the importance and mechanism of UV radiation on litter decomposition, especially on standing litter, in humid forest ecosystems remain unclear.2. We conducted a factorial experiment in a humid subtropical forest gap, manipulating the effects of UV radiation on the decomposition of standing litter under different microbial conditions.3. After 366 days of standing incubation, under normal conditions (UV pass with microorganisms), up to 40.63% of the litter mass was lost. However, under a UV pass without microorganisms, litter mass loss was only 16.30%. Under a UV block, the mass loss of litter with microorganisms was 27.68% and that of litter without microorganisms was 15.54%. Without microorganisms, UV radiation had no significant effect on the mass loss of litter carbon. However, UV radiation increased the DOC concentration of litter. And in the presence of microorganisms, UV radiation contributed to an increased mass loss of lignin by 16.72% and of cellulose by 14.75%. No negative effects of UV radiation on microorganisms were observed. These results suggest that UV radiation increased the net mass loss of litter by 106.67%, and this doubling promotion was achieved through microbial degradation.4. Synthesis. The increase in microbial degradation under UV radiation may be linked to the increased degradability of lignin and cellulose caused by photodegradation. Our study indicates that direct photodegradation by UV radiation could be weak in subtropical forests, but UV photofacilitation generates rapid turnover of carbon in this system.

The effect of litter decomposition mostly depends on seasonal variation of ultraviolet radiation rather than species in a hyper-arid desert

“…In summer, UV radiation contributed to 9.88% of the mass loss, indicating its significant role in litter decomposition under sufficient sunlight. However, UV radiation did not significantly increase the mass loss rate in autumn and winter (Jiang et al, 2022). In addition, our study revealed that the mass loss during summer was significantly higher than that during winter, with K. caspia, A. sparsifolia, and P. euphratica experiencing increases of 4.3%, 9.6%, and 6.8%, respectively, due to seasonal variation (Figure 6).…”

“…Seasonal variations have been reported to affect litter decomposition rates (Berenstecher et al, 2020;Jiang et al, 2022;Dirks et al, 2010;Ma et al, 2017;Gao et al, 2023). Some studies suggest that light intensity seasonally affects litter decomposition due to stronger solar radiation in summer than in winter (Ma et al, 2017).…”

The overall decomposition of the spring-detached litter is faster than the autumn-detached litter in a steppe ecosystem

“…Litter decomposition rate is not only affected by soil microbial communities, but also by solar radiation (Wang et al 2021a;Jiang et al 2022). Previous studies have proved that litter decomposition can be directly accelerated by solar radiation via photochemical mineralization, and indirectly via the encouraging process of biotic degradtion, known as photofacilitation, in many terrestrial ecosystems (Lee et al 2012;Austin et al 2016).…”

Canopy gaps control litter decomposition and nutrient release in subtropical forests

“…Page 16/ 24 We wish to express our thanks for the support received from the Castanopsis kawakamii Nature Reserve in Sanming City, Fujian province to allow us to collect samples. The authors wish to thank X.G.G., M.J.L., L.J., J.Y.…”