【作者】 陈小燕；

【导师】 吕家珑；

【作者基本信息】 西北农林科技大学 ， 农业环境保护与食品安全， 2008， 硕士

【摘要】 黄土高原不同植被覆盖下土壤有机质的分解和累积、土壤肥力的变化、有机酸变化能够为该区农业结构调整、水土保持措施及生态环境布局提供一方面的理论依据。本文通过常规分析结合液相色谱分析,研究了子午岭林区不同植被覆盖下土壤的化学性质,并以玉米、大油芒、苜蓿、辽东栎和沙棘作为腐解材料,研究了不同植被覆盖下土壤中的植物残体腐解特征和有机酸的动态变化。得到以下主要结论:1.不同植被类型覆盖对土壤有机质、活性有机质、全N、以及碱解N、速效P、速效K有显著影响,其养分含量均基本符合随植被演替阶段提高而升高的规律。土壤全P和全K含量变化不显著;弃耕地各项养分指标均低于农田土壤。土壤活性有机质含量表现为:乔木>灌木>草地>农田>弃耕地,且变化趋势与有机质一致。说明随植被正向演替,即弃耕地转换为草地、灌丛和乔木生态系统,提高了土壤活性有机碳含量。2.根据腐解残留量的变化可将腐解过程分为四个阶段:快速分解阶段---分解停滞阶段---缓慢分解阶段---趋于稳定阶段,利用Olson指数衰减模型对植物残体腐解率和腐解时间进行拟合检验的结果达显著相关水平。3.不同植物残体有机C含量在最初一个月都表现为下降趋势,之后基本保持不变。不同腐解期植物残体全N含量的变化为0～1个月有少量增加,2～6个月基本停滞,7～12个月逐渐上升阶段;13～15个月趋于稳定阶段,基本保持不变。K含量在植物残体腐解过程中总体呈下降趋势,除0~1月有一定量的下降外,这几种植被都是在的6~8月快速下降,此后基本上不变。4.不同植被类型覆盖下,土壤有机酸含量为:乔木>灌木≈草本>农田>弃耕地。随植被演替阶段的提高,不同植被覆盖下土壤的有机酸含量逐渐升高。植物残体腐解过程中有机酸含量变化的差异显著。5.在玉米与玉米+N处理样品中五种预设酸:草酸、酒石酸、苹果酸、乙酸、柠檬酸中检测到四种,柠檬酸都未检测到;在大油茫和大油芒+N样品中检测到草酸、苹果酸、乙酸;在苜蓿样品中只检测到三种有机酸:草酸、苹果酸、乙酸;灌木植物样品沙棘中检测到草酸、苹果酸、乙酸、柠檬酸四种;在乔木样品中辽东栎及其+N处理都检测到五种有机酸:草酸、酒石酸、苹果酸、乙酸、柠檬酸。草酸随腐解时间的延长表现为呈增长趋势;苹果酸在腐解过程中,除辽东栎以外随腐解时间的延长,含量逐渐减少,这是因为苹果酸易被微生物利用,积累较少;乙酸含量变化随腐解时间延长成基本呈线性下降。酒石酸在腐解过程中在辽东栎中变现为上升趋势,在玉米中为下降趋势。柠檬酸含量成上升趋势,在腐解的最后达到最大值。更多还原

【Abstract】 In the area of Ziwuling forest after recovering of secondary forest, the degrees of soil development were varies in different parts of landform because of the variations in soil water contents, the sequence of vegetation recovery and vegetation types. This study has analyzed the soil nutrient under different vegetations. Selecting corn remainder, Spodiopogon sibiricus remainder, alfalfa remainder, Quercus liaotungensis remainder and Hippophae rhamnoides remainder as decaying materials, the characteristics of the remainders during the process of decaying and the change of organic acids in remainders during the process of decaying was also studied by normal analysis combined with HPLC. It can accumulate data for the research of the accumulation and decomposition of soil organic matter, the situation of soil fertility, the dynamic of organic acid, and also can provide foundations for soil and water conservation and the reconstruction of environment. The main conclusions were as follows:1. The vegetation types made a significant effect on the content of soil organic matter, active organic matter, total N, available N, available P and available K, and the nutrient content almost increased followed by the sequences of vegetation succession. There is no significant effect on total P and total K, the soil nutrients in abandoned field were lower than those of farmland, which proved that the condition of agroecotype had a certain protective effect on soil fertility. In the hill area of the Loess Plateau, rebuilding of forest from cropland in slopes and vegetation recovery could improve the status of soil nutrients.2. According to the changes of decaying remainders, the decaying process can be divided into 4 stages: the stage of fast decomposition---the stage of stagnation decomposition ----the stage of slow decomposition---the stage of tending to be stable. Olsen’s exponential attenuation model performed well in regressing the relationship between the decaying rate of plant remainder and the decaying time.3. The changes of organic C, N and K in decay remainders were different. The content of organic C almost did not change during the whole decay time. The content of nitrogen increased in 7-12months gradually, and then kept steady. The content of K decreased slowly in 0-1months and decreased quickly in 6-8months, and then kept steady.4. Under the different vegetation type, the content of soil organic acid was basically in the order of Tree bush≈herb >farmland abandoned land. Therefore, it can be seen that the content of soil organic acids were increased gradually along with the enhancement of vegetational succession stage.5. Oxalic acid, Tartaric acid, Malic acid, Acetic acid were detected in corn and corn+N . In Spodiopogon sibiricus and Spodiopogon sibiricus+N we detected oxalic acid, malic acid, acetic acid. In alfalfa we only detected three of them: oxalic acid, malic acid, acetic acid. Oxalic acid, malic acid, acetic acid, criric acids were detected in Hippophae rhamnoides. In Quercus liaotungensis, all of the organic acids were detected by HPLC.Oxalic acid in decomposition, all of the remainders have a growth trend. Malic acid in the process of decomposition, with the decomposition of the extension of time, the content gradually reduced, this is because Malic acid is easy for microbial use, Acetic acid content accumulate less of the decomposition extend. Tartaric acid during decomposition is less and less in corn and corn+N,while it is accumulated in Quercus liaotungensis更多还原