【作者】 王意锟；

【导师】 方升佐；

【作者基本信息】 南京林业大学 ， 森林培育， 2012， 博士

【摘要】 本文采用杨树凋落叶和农作物秸秆为材料，通过野外实验和室内培养，研究了农林复合条件下杨树凋落物和农作物秸秆混合分解及养分释放的季节动态、土壤动物在分解过程中的作用以及混合分解对林地土壤呼吸的影响。同时，本文还探讨了改变添加频次对土壤碳氮矿化的影响。主要研究结果如下：（1）杨树养分内循环会影响凋落物基质质量，进而影响分解速率。栽培密度对杨树叶片N、P、Ca含量及转移效率有一定的影响，对K和Mg影响较小。南林-895杨的N、P和Ca含量较高，转移效率较小；而南林-95杨N和P含量较低，转移效率较高。（2）试验结束时（2012年1月初），杨树凋落叶和小麦秸秆的残留率较高，花生茎秆次之，花生叶的残留率最低；混合模式都表现出一定的促进分解作用，且杨树叶-花生叶模式的相互促更明显。（3）杨树叶和小麦秸秆中N和P元素表现为先富集，后释放；花生叶K含量低，失重率高于其他处理，而小麦秸秆K含量最高，前6个月的失重率却低于其他处理；随着凋落物的分解，各处理Ca元素的含量有所升高，Ca元素的释放主要集中在7月以后；花生叶处理和杨树叶处理表现出Mg元素的净释放，而小麦秸秆和花生茎秆在分解的初期存在一定程度的富集，然后才释放。混合模式能促进养分释放，且杨树叶-花生叶模式的促进作用最大。（4）凋落物中土壤动物优势类群为弹尾目和蜱螨目，夏季，土壤动物与凋落物的分解速率存在明显的正相关，冬季，土壤动物数量大幅减少，对凋落物分解速率的作用也很小。（5）春、夏季节，花生叶和花生茎秆的土壤呼吸速率高于杨树叶和小麦秸秆，而秋季时，花生叶和小麦秸秆呼吸速率较低。夏季时，杨树叶-花生叶和杨树叶-花生茎秆处理土壤呼吸速率高于杨树叶-小麦秸秆处理；秋季也存在相似的规律。（6）花生叶有机碳矿化累积量最大，花生茎秆和杨树叶次之，小麦秸秆最低。培养结束时（第52天），混合物表现出明显的促进矿化的作用；土壤微生物量碳氮与各残落物氮含量、C/N比存在显著的相关性；杨树叶、小麦秸秆及其混合物处理的土壤矿质态氮含量均低于对照，而添加花生叶、花生茎秆以及它们与杨树叶混合使矿质态氮含量高于对照。（7）分4次添加杨树叶的呼吸速率在1-7天较小，第8天后高于其他处理，且在9、17、25天出现峰值；分4次添加杨树叶最终的有机碳净矿化累积量高于一次添加处理；分4次添加杨树叶的土壤微生物量碳、氮高于一次性添加处理。添加残落物处理均降低了土壤矿质态氮含量，且这种现象在混合处理中更为明显。更多还原

【Abstract】 In the agroforestry system, the mixture of the forest litter and crop straw residues is differentin chemical compositions and physical structure from monoculture, and plays a key role inecosystem nutrient cycle. The agroforestry patterns of poplar-peanut and poplar-wheat, which arethe typical agroforestry models in northern Jiangsu province, were chosen to study the impacts ofmixed residues on decomposition rate, nutrient release, the change of soil fauna and soilrespiration. The main results are as follows:（1）The contents of N、P and Ca and their transfer efficiency in poplar leaves were differentin the various plantations (spacing6m×6m and spacing3m×8m); Compare to poplarNanlin-95, the contents of N、P and Ca were lower, and thetransfer efficiency was higher inpoplar Nanlin-895.（2）The decomposition rate displayed in the order of H＞HJ＞Y＞M for singleresidue treatments, while it was ranged as Y-H＞Y-HJ＞Y-M in mixed residue treatments. Atthe end of experiment, the mixture of the forest litter and crop residues demonstratedsignificantly stimulative effects on the decomposition rate.（3）N and P contents in poplar leaf litter and wheat straw residues mainly manifested asenrichment during the initial stage of decomposition, then released gradually. K content in peanutleaf residue was the lowest, but weight loss rate of total K was much higher than other treatments.On the contrary, K content in wheat straw residues was the highest, and weight loss rate of totalK was lower than other treatments during initial stage. In summer (July), Ca in the treatmentsbegan to release. N and P content in the poplar and wheat straw residues mainly manifested asenrichment during the initial stage of decomposition, then released gradually. There was asignificant net release of Mg in poplar leaf litter and peanut litter, while wheat and peanut stalkresidues demostrated enrichment effect for Mg during initial stage. The mixture of the forest litterand crop residues showed a significant stimulative effect on the nutrient release.（4）Acarina and Collembola were the dominant groups of soil fauna in litters. Duringsummer, the decomposition rate was well correlated with the population density of soil fauna, butthis phenomenon was not observed in winter.（5）In Spring and Summer, the soil respiration increased significantly after adding peanutleaf residue and peanut stalk residue. In Autumn, the soil respiration was lower in the treatmentsof adding peanut leaf residue and wheat straw residues into soils.（6）The cumulated carbon mineralization displayed in the order of H＞HJ, Y＞M＞CKfor single residue treatments, while it was ranged as Y-H＞Y-HJ＞Y-M in mixed residuetreatments. At the end of incubation, the mixture of the forest litter and crop straw residues demonstrated significant stimulative effect on the cumulated carbon mineralization. A significantcorrelation was observed among nitrogen contents in litters, carbon-nitrogen ratio and microbialbiomass carbon and nitrogen in the soil. In mixed residue treatments, higher microbial biomasscarbon and nitrogen, and lower carbon-nitrogen ratio in the soil were observed in treatment ofY-H, while lower microbial biomass carbon and nitrogen, and higher carbon-nitrogen ratio weremeasured in treament of Y-M. When poplar leaf litter, wheat straw residue and their mixture wereadded to the soil, the contents of mineral nitrogen was significantly lower than the control.However, when peanut leaf residue, peanut stalk residue, and their mixed residues with thepoplar leaf litter were added, the contents of mineral nitrogen in soil increased significantly.（7）The cumulated carbon mineralization was significantly higher in the treatment ofadding poplar leaf litter intervally than that of adding all at the first day. The microbial biomasscarbon and nitrogen were significantly higher in the treatment of adding poplar leaf litterintervally than that of adding all at the first day. Compared to the CK, the content of soilinorganic nitrogen decreased significantly for all the residue addition treatments, especially in themixed residues treatments.更多还原