Einfluss des Wassergehalts, des Eintrags von Wurzeln und gelöster organischer Substanz und räumlicher Unzugänglichkeit auf den C-Umsatz & Bestimmung der räumlichen Variabilität von Bodeneigenschaften

含水量、根系输入和溶解有机物以及空间交通不便对碳周转的影响

• 批准号: 233424527
• 负责人: Professor Dr. Bernard Ludwig
• 金额: --
• 依托单位: Institut für Bodenökologie (IBOE) (aufgelöst)
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/233424527?language=en
• 关键词: Einfluss; des; Wassergehalts; Eintrags; von

It is well established that reduced supply of fresh organic matter, interactions of organic matter with mineral phases and spatial inaccessibility affect C stocks in subsoils. However, quantitative information required for a better understanding of the contribution of each of the different processes to C sequestration in subsoils and for improvements of subsoil C models is scarce. The same is true for the main controlling factors of the decomposition rates of soil organic matter in subsoils. Moreover, information on spatial variabilities of different properties in the subsoil is rare. The few studies available which couple near and middle infrared spectroscopy (NIRS/MIRS) with geostatistical approaches indicate a potential for the creation of spatial maps which may show hot spots with increased biological activities in the soil profile and their effects on the distribution of C contents. Objectives are (i) to determine the mean residence time of subsoil C in different fractions by applying fractionation procedures in combination with 14C measurements; (ii) to study the effects of water content, input of 13C-labelled roots and dissolved organic matter and spatial inaccessibility on C turnover in an automatic microcosm system; (iii) to determine general soil properties and soil biological and chemical characteristics using NIRS and MIRS, and (iv) to extrapolate the measured and estimated soil properties to the vertical profiles by using different spatial interpolation techniques. For the NIRS/MIRS applications, sample pretreatment (air-dried vs. freeze-dried samples) and calibration procedures (a modified partial least square (MPLS) approach vs. a genetic algorithm coupled with MPLS or PLS) will be optimized. We hypothesize that the combined application of chemical fractionation in combination with 14C measurements and the results of the incubation experiments will give the pool sizes of passive, intermediate, labile and very labile C and N and the mean residence times of labile and very labile C and N. These results will make it possible to initialize the new quantitative model to be developed by subproject PC. Additionally, we hypothesize that the sample pretreatment “freeze-drying” will be more useful for the estimation of soil biological characteristics than air-drying. The GA-MPLS and GA-PLS approaches are expected to give better estimates of the soil characteristics than the MPLS and PLS approaches. The spatial maps for the different subsoil characteristics in combination with the spatial maps of temperature and water contents will presumably enable us to explain the spatial heterogeneity of C contents.

众所周知，新鲜有机质供应的减少、有机质与矿物相的相互作用以及空间的不可达性都会影响底土中的碳储量，但是，为了更好地了解每种不同过程对碳固存的贡献，需要定量信息。底土中土壤有机质分解速率的主要控制因素也是如此，而且关于底土中不同性质的空间变量的信息也很少。将近红外光谱和中红外光谱 (NIRS/MIRS) 与地质统计学方法结合起来的少数研究表明，创建空间图具有潜力，该空间图可能显示土壤剖面中生物活性增加的热点及其对碳含量分布的影响目标是 (i) 通过应用分馏程序并结合 14 C 测量来确定地下 C 在不同部分中的平均停留时间；(ii) 研究含水量、 13 C 标记根的输入和溶解有机物的影响；自动微观系统中碳周转的物质和空间不可接近性；(iii) 使用 NIRS 和 MIRS 确定一般土壤特性和土壤生物和化学特征，以及 (iv) 使用以下方法将测量和估计的土壤特性外推到垂直剖面：对于 NIRS/MIRS 应用，样品预处理（空气干燥样品与冷冻干燥样品）和校准程序（改进的偏最小二乘 (MPLS) 方法与结合 MPLS 或遗传算法）。我们率先将化学分馏与 14C 测量和孵育实验结果相结合，给出被动、中间、不稳定和非常不稳定的 C 和 N 的池大小以及平均停留时间。不稳定和非常不稳定的碳和氮。这些结果将使初始化由子项目 PC 开发的新定量模型成为可能。此外，我们发现样品预处理“冷冻干燥”对于土壤生物的估计将更有用。特征GA-MPLS 和 GA-PLS 方法预计比 MPLS 和 PLS 方法能够更好地估计不同底土特征的空间图以及温度和含水量的空间图。大概将使我们能够解释 C 含量的空间异质性。