The functional quality of decomposing litter outputs from an Arctic plant community is affected by long-term exposure to enhanced UV-B
The functional quality of decomposing litter outputs from an Arctic plant community is affected by long-term exposure to enhanced UV-B
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DOI：
10.1016/j.ecolind.2015.05.052
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发表时间：
2016
影响因子：
6.9
通讯作者：
Alan G. Jones;J. Bussell;A. Winters;J. Scullion;D. Gwynn‐Jones
中科院分区：
文献类型：
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作者：
Alan G. Jones;J. Bussell;A. Winters;J. Scullion;D. Gwynn‐Jones
植物暴露于增强的UV-B辐射下通常会引起叶片次生代谢物谱的变化，这些变化将在凋落物中遗传，影响凋落物分解和敏感植物群落的碳(C)动态。苯酚氧化酶是分解过程中的一个关键酶，它受凋落物质量的影响，因此是分解的生物指示物。在这里，我们研究了瑞典亚北极地区20多年来实验群落暴露于增强UV-B后的矮灌木凋落物分解。我们检验了叶面UV-B暴露会改变凋落物质量以提高酚氧化酶活性的假设。这是通过在我们的实验植被下新收集的混合群落凋落物中测量苯酚氧化酶活性来验证的。接下来，在分解试验中使用实验室微生态系统来调查个体物种在8周内的反应，重点关注分解凋落物（来自mempetrumhermaphroditum， vacinium vitis- ideaea,Vaccinium uliginosum）产生的渗滤液的质量。在试验中，每两周收集的渗滤液被分析酚氧化酶活性，以及总酚和溶解有机C （DOC）。在试验结束时，还测定了凋落物质量损失和呼吸C。对田间混合群落凋落物的初步评价发现，UV-B处理（以下简称“UV-B处理”）对苯酚氧化酶活性没有增强作用。然而，在受控的实验室中观实验中，UV-B处理的显著物种特异性效应是明显的，在vitis-理想的渗滤液中，酚氧化酶活性增加（P< 0.001），呼吸C.渗滤液中DOC的释放量显著减少（P= 0.05）， UV-B处理在疫苗种和对v的影响中都更大。木质素含量显著（P< 0.05）。UV-B处理对任何物种凋落物和渗滤液的总酚浓度均无影响，但渗滤液总酚含量在不同时间和物种间均存在显著差异。此外，从分解凋落物的渗滤液中酚的初始浓度。雌雄同体大于两种疫苗。结果表明，UV-B在影响酶功能和分解方面具有物种特异性作用，取决于个体性状。这对该系统和更广泛的分解动力学具有启示意义。我们的研究强调了使用实验室分析来获得对全球变化因子（UV-B）对分解的物种水平影响的机制理解的价值，否则这些影响被群落水平的响应所掩盖，并且难以在野外条件下确定。
Plant exposure to enhanced UV-B radiation typically induces changes in leaf secondary metabolite profiles which will be inherited in litter, affecting litter breakdown and the carbon (C) dynamics of sensitive plant communities. A key enzyme in the decomposition process is phenol oxidase which is influenced by litter quality and, hence, a decomposition bioindicator. Here we investigated dwarf shrub litter decomposition following experimental community exposure to enhanced UV-B over two decades in the Swedish sub-Arctic. We examined the hypothesis that foliar UV-B exposure would alter litter quality to elevate phenol oxidase activity. This was tested in the field by measuring phenol oxidase activity in freshly collected mixed-community litter from under our experimental vegetation. A laboratory mesocosm was next used in a decomposition assay to investigate individual species responses over eight weeks, with an emphasis on the quality of leachate outputs from decomposing litter (fromEmpetrumhermaphroditum,Vaccinium vitis-idaea,Vaccinium uliginosum). In the assay bi-weekly collections of leachate were analysed for phenol oxidase activity, together with total phenolics and dissolved organic C (DOC). At the end of the assay litter mass loss and respired C were also determined. The initial assessment on field mixed-community litter found no enhanced UV-B treatment (henceforth: ‘UV-B treatment’) effect on phenol oxidase activity. However, in the controlled laboratory mesocosm assay, significant species-specific effects of the UV-B treatment were evident, with increased phenol oxidase activity inV. vitis-idaealeachate (P< 0.001) and a significant reduction (P= 0.05) in respired C. Leachate DOC release from the UV-B treatment was greater in bothVacciniumspecies and the effect onV. uliginosumwas significant (P< 0.05). The UV-B treatment had no effect on the total phenolic concentration of litter or leachates for any species, but there were significant differences in leachate total phenolics, both over time and between species. Also the initial phenolic concentration in leachates from the decomposing litter ofE. hermaphroditumwas greater than bothVaccinumspecies. Results suggest a species specific role for UV-B in influencing enzyme function and decomposition, dependent on individual traits. This has implications for decomposition dynamics in this system and more widely. Our study highlights the value of using a laboratory assay to gain a mechanistic understanding the species level impacts of a global change factor (UV-B) on decomposition, which are otherwise obscured by community-level responses and difficult to determine under field conditions.