华西雨屏区常绿阔叶林凋落叶分解过程中木质素降解对模拟氮、硫沉降的响应

Effects of Simulated Nitrogen and Sulfur Deposition on Lignin Degradation During Foliar Litter Decomposition in Evergreen Broad-leaved Forest in the Rainy Area of West China

[目的]探索亚热带常绿阔叶凋落叶分解过程中木质素降解对氮、硫沉降的响应。[方法]采用氮、硫双因素3水平试验设计方法,设置对照(CK)、低氮(LN, 50 kg·hm^(-2)·a^(-1))、高氮(HN, 150 kg·hm^(-2)·a^(-1))、低硫(LS, 200 kg·hm^(-2)·a^(-1))、高硫(HS, 400 kg·hm^(-2)·a^(-1))、低氮低硫(LNLS)、高氮低硫(HNLS)、低氮高硫(LNHS)和高氮高硫(HNHS)9个处理,分析氮、硫沉降对华西雨屏区常绿阔叶林凋落叶分解过程中木质素降解的影响。[结果]模拟氮、硫沉降1年时间,LN、LNLS和HNLS对木质素残留率、多酚氧化酶和过氧化氢酶活性的影响不显著;LS显著降低了木质素残留率,显著增加了凋落叶C/N、纤维素损失率、多酚氧化酶和过氧化物酶活性;HN、HS、LNHS和HNHS显著增加了木质素残留率,显著降低了凋落叶C/N、纤维素损失率、多酚氧化酶和过氧化物酶活性;氮沉降和硫沉降对木质素降解的交互作用显著。[结论]不同氮、硫沉降水平对华西雨屏区常绿阔叶林凋落叶分解过程中木质素降解及相关酶的影响不同,在氮、硫沉降量持续增加的背景下,氮、硫沉降相互作用,共同影响凋落叶分解过程中木质素的降解,进而影响凋落叶分解过程。

[Objective] To understand the effects of nitrogen and sulfur deposition on the degradation of lignin during the litter decomposition in evergreen broad-leaved forest in subtropical area.[Method] A one-year field experiment of simulating nitrogen and sulfur deposition was conducted in the rainy area of west China. Three nitrogen and three sulfur levels resulting nine treatments were investigated, including the control (CK), low nitrogen (LN, 50 kg·hm^-2·a^-1), high nitrogen (HN, 150 kg·hm^-2·a^-1), low sulfur (LS, 200 kg·hm^-2·a^-1), high sulfur (HS, 400 kg·hm^-2·a^-1), low nitrogen and low sulfur deposition (LNLS), high nitrogen and low sulfur deposition (HSLS), low nitrogen and high sulfur deposition (LNHS), and high nitrogen and high sulfur deposition (HNHS).[Result] After one-year's simulation of nitrogen and sulfur deposition, the LN, LNLS and HNLS showed no significant effects on lignin remaining rate, the activity of polyphenol oxidase and catalase, while the LS treatment significantly reduced the lignin remaining rate and significantly enhanced the leaf litter C/N, cellulose loss rate, polyphenol oxidase and peroxidase activity. However, the HN, HS, LNHS and HNHS treatments improved significantly the lignin remaining rate, significantly decreased leaf litter C/N, cellulose loss rate, polyphenol oxidase and peroxidase activity. Furthermore, the simulated nitrogen and sulfur deposition interacted with each other, which affected the rate together.[Conclusion] The effects of nitrogen and sulfur deposition levels on lignin degradation and related enzymes are different during litter decomposition in evergreen broad-leaved forest in rainy area of west China. With the increase of atmospheric deposition, the lignin degradation of the evergreen broad-leaved forest has potentially been affected by nitrogen and sulfur deposition. The foliar litter decomposition process may be affected by atmospheric nitrogen and sulfur deposition in the forest.