Zhou Guixiang, Zhang Jiabao, Mao Jingdong, Zhang Congzhi, Chen Lin, Xin Xiuli, Zhao Bingzi
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
Jiujiang University, Jiujiang 332005, China.
Sci Rep. 2015 Oct 1;5:14851. doi: 10.1038/srep14851.
The role of photodegradation, an abiotic process, has been largely overlooked during straw decomposition in mesic ecosystems. We investigated the mass loss and chemical structures of straw decomposition in response to elevated UV-B radiation with or without soil contact over a 12-month litterbag experiment. Wheat and maize straw samples with and without soil contact were exposed to three radiation levels: a no-sunlight control, ambient solar UV-B, and artificially elevated UV-B radiation. A block control with soil contact was not included. Compared with the no-sunlight control, UV-B radiation increased the mass loss by 14-19% and the ambient radiation by 9-16% for wheat and maize straws without soil contact after 12 months. Elevated UV-B exposure decreased the decomposition rates of both wheat and maize straws when in contact with soil. Light exposure resulted in decreased O-alkyl carbons and increased alkyl carbons for both the wheat and maize straws compared with no-sunlight control. The difference in soil contact may influence the contribution of photodegradation to the overall straw decomposition process. These results indicate that we must take into account the effects of photodegradation when explaining the mechanisms of straw decomposition in mesic ecosystems.
在湿润生态系统中，光降解这一非生物过程在秸秆分解过程中的作用在很大程度上被忽视了。我们通过一项为期12个月的垃圾袋实验，研究了在有或无土壤接触的情况下，增强的UV-B辐射对秸秆分解过程中质量损失和化学结构的影响。将有和无土壤接触的小麦和玉米秸秆样本暴露于三种辐射水平下：无阳光对照、环境太阳UV-B以及人工增强的UV-B辐射。未设置有土壤接触的区组对照。12个月后，对于无土壤接触的小麦和玉米秸秆，与无阳光对照相比，UV-B辐射使质量损失增加了14%-19%，环境辐射使其增加了9%-16%。当与土壤接触时，增强的UV-B照射降低了小麦和玉米秸秆的分解速率。与无阳光对照相比，光照导致小麦和玉米秸秆中的O-烷基碳减少，烷基碳增加。土壤接触的差异可能会影响光降解对整个秸秆分解过程的贡献。这些结果表明，在解释湿润生态系统中秸秆分解的机制时，必须考虑光降解的影响。
