邓恩桉林土壤腐殖质对模拟硫、氮复合沉降的响应

Responses of humus compositions to sulfur and nitrogen complex simulated depositions in an artificial young Eucalyptus dunnii plantation

为探究红壤地区人工林生态系统对酸沉降的响应机制,依据二次正交回归旋转组合设计原理,于2009年7月对邓恩桉人工幼龄林进行模拟硫、氮复合沉降试验,研究1 a模拟沉降后邓恩桉林下红壤团粒腐殖质成分状况。单因素方差分析(ANOVA)显示,17组样地中,<0.25 mm粒级土壤腐殖质、胡敏酸、富里酸含碳量差异达0.05显著水平;0.25-1 mm粒级土壤胡敏素含碳量、胡敏酸与富里酸含碳量比值(胡富比)差异达0.05显著水平;1-2 mm粒级土壤腐殖质各成分差异均达0.05不显著水平。选择以上5组差异显著成分进行分析和建模,结果表明,与空白对照组相比,腐殖质、胡敏酸、富里酸、胡敏素含碳量降低,胡富比先升高后降低。硫、氮沉降对以上5种腐殖质成分主效应存在差异,硫、氮沉降交互作用均不显著。研究表明,硫、氮沉降对腐殖质影响以单一效应为主,土壤肥力受硫、氮沉降影响先升高后降低,分界点对应的实际沉降量分别为20.02、63.70 kg·hm-2·a-1。

To explore the response mechanisms of plantation ecosystems to acid deposition in red soil areas , the experiment about the simulation of sulfur （ S） and nitrogen （ N） complex depositions was carried out in an artificial young Eucalyptus dunnii plantation in July, 2009.It was studied by the quadratic rotating orthogonal regression design principle , and the humus compositions in soil aggregates were tested after one year simulated depositions .The One-Way ANOVA between 17 treatments showed that under the 1 a simulated S and N deposition the variances of humus carbon content , humic acid carbon content and fulvic acid carbon content were significantly different in soil grain sizes lower than 0.25 mm, while humin carbon content and the ratio of humic acid carbon content and fulvic acid carbon content were significantly different in 0.25-1 mm grain sizes, but none of variance differences of five humus composition were significant in 1 -2 mm grain sizes at P 〈0.05.Those compositions in five significantly different groups were chosen to be analyzed and to establish models, the result showed that the carbon content of humus , humic acid, fulvic acid, humin in treatment groups were decreased compared to the control groups in the same grain sizes , but the ratios of humic acid carbon content and fulvic acid carbon content increased , followed by decrease in some values in red soil aggregates .The main effects of simulated S and N deposition on carbon content of the five kinds of humus components were different to each other factor , and all the interactions of two factors were insignificant .It has been proved that the effects of simulated S and N depositions on humus components in red soil aggregates of plantation ecosystems were dominated by single effect , and the soil fertility under S and N depositions increased followed by decrease, the actual depositions corresponding to the cut-off points were 20.02, 63.70 kg· hm-2· a-1.