Positive and negative effects of UV irradiance explain interaction of litter position and UV exposure on litter decomposition and nutrient dynamics in a semi-arid dune ecosystem
Positive and negative effects of UV irradiance explain interaction of litter position and UV exposure on litter decomposition and nutrient dynamics in a semi-arid dune ecosystem
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紫外线辐照度的正面和负面影响解释了半干旱沙丘生态系统中凋落物位置和紫外线照射对凋落物分解和营养动态的相互作用
DOI：
10.1016/j.soilbio.2018.06.013
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发表时间：
2018-09-01
影响因子：
9.7
通讯作者：
Cornelissen, Johannes H. C.
中科院分区：
文献类型：
--
作者：
Erdenebileg, Enkhmaa;Ye, Xuehua;Cornelissen, Johannes H. C.
太阳辐射介导的落叶光降解已得到广泛研究，因为它在旱地生态系统中的碳（C）和养分循环中发挥着重要作用。然而，紫外线（UV）辐射及其与凋落物质量和微生物降解的相互作用影响旱地凋落物分解的机制仍不确定。在内蒙古半干旱毛乌素内陆沙丘进行了一项田间试验，研究了紫外线辐射和凋落物位置对代表不同凋落物质量的八种对比树种（三种多年生禾本科植物、三种灌木、两种一年生草本植物）在一整年的培育过程中叶凋落物分解的影响。结果表明，紫外线辐射增加了两种多年生禾本科植物和两种一年生草本植物的悬浮凋落物质量损失，但对其他四种考虑的物种没有显着影响；不同物种的质量损失增加百分比从 4.5% 到 27.3% 不等，平均为 13.7%。悬浮垃圾响应紫外线辐射而释放的碳显示出与质量损失类似的模式。土壤表面凋落物的氮（N）释放量低于悬浮位置，因为前者参与了微生物分解驱动的氮固定。紫外线辐射对地表垃圾的分解率没有净影响，这可能是由于光化学过程的积极作用抵消了对微生物的消极影响。多元线性回归表明，初始凋落物C:N比和叶片干物质含量(LDMC)可以预测凋落物分解速率，其中凋落物C:N比影响较强。基于多个物种的研究结果强调了不同非生物和生物驱动因素介导的光降解对旱地凋落物氮和/或碳矿化的重要性。
Solar radiation mediated photodegradation of leaf litter has been studied substantially as it plays important roles in the cycling of carbon (C) and nutrients in dryland ecosystems. However, the mechanism by which ultraviolet (UV) radiation and its interaction with litter quality and microbial degradation affect dryland litter decomposition is still uncertain. A field experiment was carried out in semiarid Mu Us inland dunes of Inner Mongolia, China to investigate the effects of UV radiation and litter position on leaf litter decomposition of eight contrasting species (three perennial grasses, three shrubs, two annual forbs) representing different litter qualities over a whole year of incubation. The results showed that UV radiation increased mass loss of suspended litters for two perennial grasses and two annual forbs, but had no significant effect on the other four species considered; across species the percentage increase in mass loss ranged from 4.5 to 27.3% with an average of 13.7%. C release from suspended litters in response to UV radiation showed similar patterns with mass loss. Nitrogen (N) release from litters on the soil surface was lower than in suspended position because the former was involved in N immobilization driven by microbial decomposition. There were no net effects of UV radiation on decomposition rates of surface litters possibly due to the positive effects of photochemical process offsetting negative effects on microbes. Multiple linear regressions showed that the C:N ratio of initial leaf litter and leaf dry matter content (LDMC) could predict the rate of litter decomposition, in which litter C:N ratio had stronger influence. The findings, based on multiple species, highlight the importance of photodegradation on litter nitrogen and/or carbon mineralization in drylands as mediated by different abiotic and biotic drivers.