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

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. 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. 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. 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.

紫外线辐射（UV radiation）已被证实可通过光降解旱地生态系统中的有机质，直接驱动枯落物分解。然而，紫外线辐射对枯落物分解的重要性与作用机制，尤其是湿润森林生态系统中的立枯凋落物分解，仍不明晰。我们在亚热带湿润林窗中开展了一项析因实验，调控不同微生物条件下紫外线辐射对立枯凋落物分解的影响。经过366天的立枯培养后，在正常条件（允许紫外线通过且存在微生物）下，枯落物质量损失率可达40.63%。但在仅允许紫外线通过但无微生物参与的条件下，枯落物质量损失仅为16.30%。在紫外线阻隔条件下，有微生物参与的枯落物质量损失率为27.68%，无微生物参与的则为15.54%。在无微生物的情况下，紫外线辐射对枯落物碳的质量损失无显著影响，但可提升枯落物的溶解性有机碳（DOC）浓度。在存在微生物的条件下，紫外线辐射可使木质素质量损失增加16.72%，纤维素质量损失增加14.75%。未观测到紫外线辐射对微生物产生负面影响。上述结果表明，紫外线辐射可使枯落物净质量损失提升106.67%，这一翻倍的促进效应通过微生物降解实现。综合来看，紫外线辐射下微生物降解作用的增强，可能与光降解导致的木质素与纤维素可降解性提升有关。本研究表明，紫外线辐射的直接光降解作用在亚热带森林中可能较弱，但紫外线的光促进效应可驱动该生态系统中碳的快速周转。