Abstract: In order to explore the decomposition characteristics of mixed litters in arid desert region,Reaumuria soongarica (Pall.) Maxim,Nitraria sphaerocarpa Maxim and Salsola passerina Bunge were used as the research objects in this study. The changes of mass loss rate and nutrient residue rate of single and mixed litter were measured and analyzed,and the additive and non-additive effects of mixed litter decomposition were revealed. The results showed that:The mass loss rate of each litter increased with the extension of decomposition time; The residual rate of C and N in each litter decreased with the decomposition time,indicating that the C and N nutrient elements were released; The mass loss rate of mixed litter showed an additive effect. The residual rate of C was an additive effect in the early stage of decomposition,and an antagonistic non-additive effect at the end of decomposition. The residual rate of N was antagonistic and synergistic in the early stage of decomposition,and an additive effect at the end of decomposition; After litter mixing,higher species richness would lead to enhanced non-additive effect of nutrient residual rate. In summary,the mixing effect of nutrient changes in mixed litter decomposition varies with the decomposition time. The species richness of mixed litter will affect the mixed effects of nutrient elements,which can improve the nutrient cycle of arid desert ecosystem.

Key words: Litter decomposition, Arid desert region, Non-additive effect, Antagonistic effect, Mass loss rate

摘要： 为探究干旱荒漠区混合凋落物的分解特征,本研究以红砂(Reaumuria soongarica (Pall.)Maxim)、泡泡刺(Nitraria sphaerocarpa Maxim)和珍珠(Salsola passerina Bunge)为研究对象,分析了单一和混合凋落物质量损失率和养分残留率的变化,揭示了混合凋落物分解的加性与非加性效应。结果表明:各凋落物质量损失率随分解时间延长呈增加趋势;各凋落物C和N残留率随分解时间推移为降低趋势,说明C和N养分元素呈释放模式;混合凋落物质量损失率表现为加性效应,C残留率在分解前期为加性效应,分解末期为拮抗的非加性效应,N残留率在分解前期为拮抗和协同的非加性效应,分解末期为加性效应;凋落物混合后,较高的物种丰富度会导致养分残留率的非加性效应增强。综上,混合凋落物分解中养分变化的混合效应因分解时间而不同,混合凋落物物种丰富度会影响养分元素的混合效应,能改善干旱荒漠生态系统的养分循环。

关键词: 凋落物分解, 干旱荒漠区, 非加性效应, 拮抗效应, 质量损失率