Effects of UV-B filtration on the chemistry and decomposition of Fraxinus excelsior leaves
Effects of UV-B filtration on the chemistry and decomposition of Fraxinus excelsior leaves
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DOI：
10.1016/j.soilbio.2011.12.010
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发表时间：
2012-04
影响因子：
9.7
通讯作者：
D. Messenger;S. Fry;S. Yamulki;A. McLeod
中科院分区：
文献类型：
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作者：
D. Messenger;S. Fry;S. Yamulki;A. McLeod
多项研究表明，生长季节户外 UV-B 补充对叶子化学成分（包括碳水化合物的可提取性）和随后的落叶分解有一系列影响。然而，这项研究利用环境阳光的过滤，研究了几种级别的紫外线辐射对叶子碳水化合物化学和随后分解的影响。白蜡树 (Fraxinus excelsior) 幼苗在英国户外环境太阳照射下生长，并经过过滤处理，排除 UV-B 或同时排除 UV-A 和 UV-B。在半天然混合林地的枯落物层中经过一年的分解后，在整个生长季节中根本没有接受紫外线或没有接受 UV-B 的叶子中，干质量的损失相对于起始质量高出 10%（P<0.05）。对分解前细胞壁材料的分析显示，在排除紫外线的情况下，总碳水化合物和木质素含量没有显着趋势，叶面氮和碳氮比没有变化，仅在综合排除 UV-A 和 UV-B 的情况下，叶面碳增加了 2%（P<0.05）。用一系列提取剂（磷酸盐缓冲液、草酸铵、尿素、氢氧化钠和甲酸）连续提取碳水化合物，在排除紫外线的情况下没有显示任何趋势，但用真菌酶混合物 Driselase 消化表明，排除 UV-B 仅导致细胞壁多糖的鼠李糖和甘露糖残基抵抗 Driselase 消化 排除所有紫外线会产生相反的效果。尽管一些研究报告称，补充灯带来的 UV-B 辐射增加会增加随后叶片分解的速度，但该过滤研究的环境控制中较高的 UV-B 水平导致分解率比过滤后的 UV 处理低 29%。
Several studies have demonstrated a range of effects of outdoor UV-B supplementation during the growing season on leaf chemistry including carbohydrate extractability and on the subsequent decomposition of leaf litter. However, this study investigates the effects of several levels of UV radiation on leaf carbohydrate chemistry and subsequent decomposition using filtration of ambient sunlight. Fraxinus excelsior seedlings were grown outdoors in the UK under ambient solar irradiation and under filtration treatments which excluded either UV-B or both UV-A and UV-B. After one year of decomposition in the litter layer of a mixed semi-natural woodland, the loss of dry mass was 10% greater, relative to starting mass, in the leaves which had received no UV at all or no UV-B throughout the growing season (P<0.05). Analysis of the cell wall material before decomposition revealed no significant trends in total carbohydrate and lignin content with UV exclusions, no change in foliar nitrogen and C-to-N ratio and a 2% increase in foliar carbon (P<0.05) only with the combined exclusion of UV-A and UV-B. A sequential extraction of carbohydrate with a series of extractants (phosphate buffer, ammonium oxalate, urea, sodium hydroxide and formic acid) showed no trends with UV exclusions but digestion with the fungal enzyme mixture Driselase revealed that exclusion of UV-B only caused rhamnose and mannose residues of the cell-wall polysaccharides to resist Driselase digestion whist exclusion of all UV had the opposite effect. Whereas some studies have reported that elevated UV-B radiation from lamp supplementation can increase rates of subsequent leaf decomposition, the higher UV-B levels in the ambient controls of this filtration study resulted in 29% lower decomposition rates than the filtered-UV treatments.