【作者】 史长婷；

【导师】 陈祥伟；

【作者基本信息】 东北林业大学 ， 水土保持与荒漠化防治， 2010， 硕士

【摘要】 为了系统的阐述不同林型水土保持林,及同一林型水土保持林在不同恢复年限的动态变化,对土壤结构特征和土壤可蚀性的影响。本文首先以典型黑土区不同林型的主要人工林地土壤为研究对象,通过对土壤容重、非毛管孔隙／毛管孔隙(NCP/CP).广义土壤结构指数(GSSI).土壤水稳性团聚体特征、土粒静水崩解能力、有机质含量的测定计算与对比分析研究了不同林型水土保持林对土壤结构性特征及对土壤可蚀性的影响规律。在此基础上选取结构较好、可蚀性较低的落叶松人工林,以林龄分别为8a、21a、30a、37a、52a为研究对象,通过结构性指标和不同粒级有机碳的含量与贮量的计算与分析,研究了不同林龄落叶松人工林土壤结构性特征及其有机碳的动态变化特征。研究结果表明：0-30cm土层范围内,不同林型的水土保持林中,水曲柳林和落叶松林在降低土壤容重方面略好于樟子松林和云杉林,林地土壤的平均NCP/CP值均显著高于撂荒地(p<0.05),增加幅度范围为59.75%-128.82%,土壤透气性、透水性能力提高,并以落叶松林提高幅度最大；各林地的平均GSSI值均显著高于撂荒地(p<0.05),增加幅度范围为2.98%-4.36%,说明林分可以有效改善土壤结构,使其能够更加接近旱地土壤理想结构,以水曲柳林和云杉林改良效果相对较强,但实现趋近理想土壤结构的途径、即相态的变化方式有所不同。林分对土壤水稳性团聚体组成的影响主要表现为提高较大粒级团聚体的比例,显著增加PA0.25、降低团聚体破坏率(p<0.05);林地土壤水稳性指数显著提高(p<0.05),增加幅度达4.46-7.92倍；林地内表层土壤有机质含量较耕地相对提高了32.6%-62.7%,差异显著(p<0.05);可以认为水土保持林能够有效降低土壤可蚀性,并以阔叶水曲柳林的作用效果最为显著。不同林龄落叶松人工林,土壤容重平均变化范围为1.06-1.19 g·cm-3,随林龄的增加人工落叶松林可以显著降低土壤容重(P<0.05)；NCP/CP平均变化范围为0.03-0.11,仅37a生人工林提高效果显著(P<0.05)；土壤GSSI值的变化范围为73.19-94.61,37a和52a生林分的差异不显著而与其他人工林林分的差异显著(P<0.05)。可以认为,在典型黑土区通过落叶松人工林的培育能够改善土壤结构,但这种影响并不是随着林龄增加而无限度的增强,37a是明显改善土壤结构的临界年龄。通过对土壤干团聚体组成、不同粒级团聚体有机碳含量及有机碳贮量的测定、计算与分析,研究了不同林龄落叶松人工林土壤团聚体有机碳分配特征及其动态变化规律。结果表明：在0-30cm土层范围内,各粒级团聚体组成比例随粒级从大到小呈“八”型分布,2-5mm粒级团聚体所占比例均最大且与其他粒级存在显著性差异(P<0.05)。表层土壤各粒级团聚体有机碳含量均大于下层土壤,表层土壤中各粒级团聚体有机碳平均变化范围为32.17-48.75g/kg,下层土壤中的变化范围28.82-33.53g/kg,并均以2-5mm粒级团聚体有机碳含量最低。团聚体有机碳贮量随林龄的变化表现为大粒级团聚体(5-10mm)有机碳贮量的降低和小粒级有机碳贮量的增加。表层土壤有机碳贮量大于下层土壤有机碳贮量,但均以2-5mm粒级团聚体有机碳贮量最高,故可以认为土壤有机碳贮量的变化主要取决于各个粒级团聚体组成比例而不是各个粒级团聚体有碳含量。研究结果为进一步评价人工林植被恢复对土壤有机碳的影响提供了理论依据和参考。更多还原

【Abstract】 In order to explain the effect of different water and soil conservation forest types and the dynamic change of the same one in different forest restoration on character of soil structure and soil erodibility. Soil structural characters of different types of forests in black soil area were studied by measuring and analyzing the soil bulk density, NCP/CP, GSSI. We also investigated the effects of different stands on soil structure characters of soil water-stable aggregates, capacity of soil collapse, and organic matter content in this study were studied by measuring and analyzing. Base on this experiment, a study on 8、21、30、37 and 52-year-old larch plantations in typical black soil region was undertaken to examine soil structural characteristics and dynamic changes of plantations. The characters of soil structural and dynamic change of organic carbon in Larch Plantations were studied by measuring and analyzing the structural indicators and organic carbon content in different size aggregates.Results showed that, in 0-30cm soil, the bulk densities of Manchurian ash and Dahurian larch plantations were lower than that of Mongolian Scots pine and Korean spruce stands, Average NCP/CP of different plantations was all higher than that of abandoned land (P<0.05) increased from 59.75% to 128.82% relatively, Soil aeration and permeability were enhanced, especially in Dahurian larch plantation. Average GSSI of different plantations was higher than abandoned land too(P<0.05), with the increased range of 2.98%-4.36%. So soil and water conservation plantations can promote soil approaching ideal soil structure, Manchurian ash and Korean spruce stands performed better than the others. However they have different ways of changing three phases to be close to ideal soil three phase, or ideal soil structure, the percentage of larger size aggregates of the four stands all get increased, PA0.25 and PAD0.25 was significantly increased and decreased separately(P<0.05).Soil water stability index in stands was significantly enhanced, with 4.46-7.92 times more than that in tillage(P<0.05).Organic matter content of top soil in forest land was relatively increased from 32.6% to 62.7% compared with tillage significantly(P<0.05).Thus we conclude that soil and water conservation forests can reduce soil erodibility, especially for the Manchurian Ash plantation.During soil depth of 0-30cm in different forest age larch plantations in typical black soil region, bulk density variation among different plantations was 1.06-1.19 g·cm-3, and it could decrease obviously with plantation age increasing(P<0.05).Ratio of NCP/CP were observed between 0.03 and 0.11, only which in 37-year-old larch plantations improved significantly (P＜0.05). Values of GSSI changed from 73.19 to 95.82 with the maximum belonging to natural secondary forest. There was no significant difference of GSSI between natural secondary forest and 37-yare-old plantation, and neither was between natural secondary forest and 52-yare-old plantation. However there would be dramatically variation between natural secondary forest and the plantation with age of 8a、21a、and 30a (P＜0.05). We confirm that larch plantation can improve soil structure, but this kind of amelioration could not lastingly increase with plantation aging.37 years old larch plantation was indicated as the critical age in this study.A study was undertaken to examine soil organic carbon distribution characteristics of aggregates and dynamic changes of plantations by measuring and analyzing composition of dry aggregates, organic carbon content and organic carbon storage of different aggregate size fraction. Results showed that during soil depth of 0-30cm, the composition proportion of aggregates was distribution in shape of "∧"with decreasing size fraction. The percentage of 2-5mm size fraction accounted the largest proportion and existed significant difference from those of other size fractions (P<0.05). The organic carbon contents of all different size aggregates in topsoil, range of 32.17-48.75g/kg, were higher than those in subsoil, range of 28.82-33.53g/kg. Lowest organic carbon content was found in 2-5mm aggregate and which was significant different from those of other size fraction aggregates (P<0.05). The changing trend of organic carbon storage during soil profile was very similar to that of dry aggregate distribution among larch plantations with different ages. The soil organic carbon storage in topsoil was higher than that in subsoil. Organic carbon storage in 2-5mm aggregate was also the highest in all size fractions. we concluded that changes of organic carbon storage in soil aggregates were mainly determined by the composition of soil aggregates, but for the organic carbon contents. It presents a theoretical basis for further researches and assessments on SOC of larch plantation.更多还原