【作者】 蒋云峰；

【导师】 殷秀琴；

【作者基本信息】 东北师范大学 ， 自然地理学， 2013， 博士

【摘要】 森林凋落物是森林生态系统有机物和养分的储存库，它的分解对促进森林生态系统正常的物质循环和养分平衡具有重要作用。土壤动物作为影响凋落物分解的重要生物因子，通过破碎、搅动、摄食、刺激(微生物活性)和接种(微生物)等活动，调控着分解过程。本论文采用网袋法对长白山针阔混交林4种主要凋落物（红松、水曲柳、紫椴和色木槭）单种及混合种分解过程进行为期2年的野外监测。综合运用方差分析、多变量分析、稀疏曲线法等，比较不同种凋落物在分解速率和元素释放上的差异；分析参与分解的土壤动物群落变化；研究土壤动物与分解速率和元素释放之间的关系，探讨不同土壤动物类群在该生态系统中的功能，并比较混合凋落物对分解速率、元素释放及土壤动物群落的影响。主要结论如下：（1）在2年分解试验期间，不同网袋内各种凋落物分解速率存在一定的季节变化，4种凋落物夏秋季分解速率高于冬春季，其中水曲柳全年分解速率相对较高。凋落物分解也存在一定的年际变化，水曲柳第一年的累计分解量显著高于第二年；色木槭为第二年高于第一年，而红松和紫椴年际差异不显著。单种凋落物分解速率差异较大，其中水曲柳分解最快，至试验结束几乎完全分解，其次是紫椴和色木槭，红松最慢。混合凋落物对分解速率的影响随分解阶段和凋落物种类组成不同而变化。（2）各凋落物分解过程中，N和P元素在分解第一年都有明显的富集，进入第二年除红松凋落物外，其他凋落物N和P逐渐释放。Ca元素，除红松凋落物在4mm和2mm网袋有富集外，其他3种凋落物则随分解而减少。C和Mg元素残留量在各种凋落物中均随分解而降低。Mn元素除水曲柳凋落物含量一直较高外，其他凋落物则随分解而降低。各种凋落物纤维素含量在分解期间呈波动变化，木质素含量则逐渐升高。方差分析显示凋落物种类，分解时间及其交互作用对各元素残留率都具有显著影响。混合凋落物对各元素释放影响不同，对C元素释放的影响随分解阶段而变化；对N元素释放具有促进作用，但主要体现在分解第一年；对P元素释的影响依混合凋落物物种组成和分解阶段而不同；对Ca、Mg和Mn元素释放主要具有一定的抑制作用。（3）参与凋落物分解的土壤类群共有42大类，分属于3门7纲（寡毛纲、腹足纲、蛛形纲、倍足纲、唇足纲、综合纲和昆虫纲）。其中优势类群为甲螨亚目、等节跳科和球角跳科，常见类群为辐螨亚目、革螨亚目、长角跳科、拟亚跳科、鳞跳科、线蚓科和双翅目幼虫。在分解过程中，各凋落物中土壤动物群落组成存在差异。水曲柳凋落物中土壤动物个体和类群密度高于其他3种凋落物，而红松最低，紫椴和色木槭介于两者之间。通过PCA、稀疏曲线和方差分析显示：凋落物性质是影响参与分解的土壤动物群落主要因素，而混合凋落物的影响则相对不明显。（4）参与凋落物分解的主要土壤动物类群（螨类、弹尾类、线蚓类和双翅目幼虫等）个体密度，土壤动物总个体和类群密度与凋落物分解速率之间存在显著的正相关关系。土壤动物对各种凋落物分解的作用存在差异性，其中对水曲柳分解促进最大，为16.87%，紫椴分解最小，为2.77%。土壤动物对C、N、Ca和Mg元素释放都具有明显的促进作用，而对P和Mn元素释放的影响相对微弱。不同土壤动物类群对元素释放率的作用大小依凋落物处理不同而有差异，并且土壤动物对凋落物分解及元素释放的促进作用主要体现在分解试验的第二年。更多还原

【Abstract】 The litter decomposition plays a critical role in regulating the buildup of the forest soilorganic matter, releasing of nutrients for plant growth, and influencing the carbon cycling.Soil fauna play an important role in litter decomposition processes through breakdown oflitter, digestion and stimulation of microbial activities. A litter decomposition experiment wasconducted in a Pinus koraiensis mixed broad-leaved forest, which is one of the typical forestvegetation types in the Changbai Mountains (42°24′N,128°05′E), located in northeasternChina. The four most abundant tree specie litters in study site (Pinus koraiensis, Fraxinusmandshurica, Tilia amurensis and Acer mono) were used by litterbags, including4mm,2mmand0.01mm in order to control the different body size of soil fauna exiting or entering, tostudy the decomposition and nutrient release of the monoculture and mixed litters. FromOctober2009to October2011, litter samples were carefully retrieved from the field tolaboratory on the26th of each of the four months of April, June, August, and October. Basedon the data of decay rate, dynamics of the C, N, P, Ca, Mg and Mn of litter and soil faunacommunity, the combination of variance analysis, multivariate analysis, rarefaction andmultiple regressions were used to analyze the dynamics of litter decomposition process,nutrient release, and soil fauna community, to establish the relationship between the soil faunaand litter decomposition，and to explore the role of different soil fauna groups in litterdecomposition and nutrient releasing. The main results are summarized as follows:(1) During the2years study period, the litter decay rate had seasonal dynamics with theseasonal fluctuation of temperature and moisture. The loss rate of litter in summer andautumn were higher than that in winter and spring. The four different litter speciesdecomposed in monoculture at different rates, ranging from almost60%mass loss for litter ofP. koraiensis to almost complete mass loss for F. mandshurica after two-year of incubation.Three broadleaf leaf litters mixed with pine litter had idiosyncratic effects on the totaldecomposition rates, and the direction of these effects varied with the feld incubation timeand composition species. At the early stage of decomposition, all litter mixing treatmentsshowed that the remaining litter mass was signifcantly higher than that of the predictedvalues, indicating that the litter mixing retarded the decomposition. However, the signifcanceof this difference disappeared in the later phases of the study period, with the exception ofP.koraiensis+T.amurensis, indicating that the litter mixing had not brought positive effects tolitter decomposition.(2) Repeated measures ANOVA showed that litter treatments, field incubation time andtheir interaction had a significant impact on the rate of elements releasing. For N and P, alllitter treatments had an obvious enrichment process in the first year. While in the second year,the absolute content of the elements in each litter treatments gradually reduced except forP.koraiensis. For the Ca, the P.koraiensisthe in4mm and2mm litterbags also hadenrichments process; those in the other three kinds of litter gradually reduced with decomposition. For C and Mg, they reduced with decomposition in all kinds of litter. Mnelement content also reduced with decomposition in addition to F.mandshrica litter. Thechanges of cellulose content in all litters were fluctuated, while lignin content increasedduring the experiment. By comparing the observed values of each element releasing rate withthat of predicted values, it showed that the mixture of litter had different effects on differentelements releasing. For C releasing, the direction of effects varied with field incubation time.For N element, the mixed litter promoted the rate of releasing, but it was mainly manifested inthe first year of decomposition. For P element, it had idiosyncratic effects on the release rate,and the direction of these effects varied with the field incubation time and compositionspecies. For Ca, Mg and Mn elements, it had a certain inhibitory effects, with exception of theP.koraiensis+F.mandshurica+T.amurensis+A.mono for Ca release rate.(3)42groups of soil fauna were obtained in litterbags during the2years study period.The most abundance taxa were Acarina, Collembola Enchytraeidae and Diptera (larvae).Rarefaction curves showed that the species richness was signifcantly different among the fourmonoculture litters. F. mandshurica showed the highest richness of soil fauna, while P.koraiensis showed the lowest. The PCA results showed that the composition of the soil faunacommunities varied among the four monoculture litter species during the decompositionperiod. By PCA, rarefaction and variance analysis, the litter mixture treatments did notsupport more species richness of soil fauna than the components of monoculture litter. Theindependent t-tests showed that the litter mixing did not promote the total density of richness,abundance and diversity of soil fauna (relative to the predicted values).(4) Soil fauna had great contribution to litter decomposition, and also had greatinfluences on the element cycle in ecosystems. There were significant positive relationshipsbetween individual and group’s density of soil fauna and litter decay rate. Throughout theexperimental period, litter species, field incubation time, mesh size and they interaction had asignificant impact on the litter decomposition rate (P<0.05). Contribution rate of soil fauna toF. mandshurica litter decomposition was great,16.87%; less to T. amurensis litterdecomposition,2.77%after two-year study period. The main groups of soil fauna individualdensity (Acarina, Collembola, Enchytraeidae and Diptera (larvae) and total soil fauna densityhad signifcantly positive relative to releasing of C, N, Ca and Mg, while had weak relative toP and Mn elements. The Contribution of different group soil fauna (macrofauna,meso-microfauna) to litter decomposition and nutrient elements releasing were varied amonglitter treatments. In addition, the soil fauna accelerated to litter decomposition and nutrientelements releasing mainly manifested in the second year of the decomposition experiment.更多还原