有机组分对凋落物分解酸抑制效应的影响  

Effect of Organic Components on the Inhibition of Litter Decomposition by Acid Deposition

作　　者：付宁 林永慧[1] 何再华[1] 何兴兵[1] FU Ning;LIN Yonghui;HE Zaihua;HE Xingbing(College of Biology and Environmental Sciences,Jishou University,Jishou,Hunan 416000,China)

机构地区：[1]吉首大学生物资源与环境科学学院,湖南吉首416000

出　　处：《江西农业大学学报》2023年第3期553-563,共11页Acta Agriculturae Universitatis Jiangxiensis

基　　金：国家自然科学基金项目(31560205、32060332、31670624)。

摘　　要：[目的]酸沉降极大地影响了森林生态系统的物质循环过程,而森林凋落物作为联系该系统养分物质循环的纽带,其分解速率也直接受大气酸沉降影响。以处于不同分解时期的香樟凋落叶片作为分解底物,分析香樟人工林各凋落物层对不同梯度酸沉降的响应。[方法]选取亚热带地区生态优势树种香樟凋落叶作为分解材料,采用野外原位网袋分解法,在不同取样时期分析分解动态。[结果]与对照相比,酸处理(pH4.8、pH4.0)抑制了各层[未分解层(N)、上分解层(U)和下分解层(L)]的凋落物分解,在L层表现为随着酸度增加,抑制分解效应增强,然而在N层和U层却相反(强酸引起的分解较弱酸更快),这可能是由于强酸能够促进纤维素含量较高的叶片分解,所引起的酸解效应部分抵消酸对分解者活性的抑制;不同凋落物层之间质量损失结果为N>U>L,未分解层和上分解层中易分解成分(糖类、可溶性化合物)较多,纤维素含量相对较高,而下分解层中木质素等难分解成分比例升高,导致分解速率下降;微生物呼吸速率、纤维素木质素分解酶等指标对酸处理及凋落物各分解层的响应基本与质量损失情况表现一致。[结论]酸沉降对凋落物分解有一定的抑制作用,但这种抑制效应在凋落物各分解层表现不同,其抑制程度依赖于各分解层凋落物有机组分的成分含量。[Objective]Acid deposition significantly affects the material cycling process of forest ecosystem.The decomposition rate of forest litters,as the link of nutrient cycling in the system,is also directly affected by atmospheric acid deposition.Cinnamomum camphora leaf litter at different decomposition stages was used as the decomposition substrate to analyze its response to acid deposition with different gradients.[Method]The leaf litter of C.camphora,an ecologically dominant tree in the subtropical region,was selected as the decomposition material and the decomposition dynamics were analyzed using the in-situ net bag decomposition method at different sampling periods.[Result]Compared with the control,acid treatments(pH4.8 and pH4.0)inhibited the decomposition of litters in undecomposed layer(N),upper decomposed layer(U)and lower decomposed layer(L).In the L layer,with the increase of acidity,the effect of inhibiting decomposition is enhanced,but it was opposite in N and U layer(leaf litter decomposition in strong acids was faster than in weak acids).This may be due to the fact that strong acid can promote the decomposition of leaves with higher cellulose content,and the acid hydrolysis effect partially offset the inhibition of acid on the activity of decomposers.The mass loss of different litter layers showed the pattern of N>U>L.The undecomposed layer and the upper decomposed layer had more easily decomposed components(sugars and soluble compounds),and the content of cellulose was relatively high,while the lower decomposed layer had a higher proportion of refractory components such as lignin,which led to a decrease in decomposition rate.In addition,the results of microbial respiration rates,cellulose and lignin decomposition enzymes in acid treatments and in different leaf litter decomposition layers were consistent with the performance of litter mass loss.[Conclusion]Acid deposition can inhibit the leaf litter decomposition to some extent,the inhibition effects are different in different litter decomposition lay

关 键 词：酸沉降 香樟 凋落物分解 酶活性 质量残留率 

分 类 号：S714[农业科学—林学]