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上的不可及性都会影响底土中的碳库。然而，为了更好地了解每一种不同过程对底土固碳的贡献以及改进底土碳模型所需的定量信息很少。控制土壤有机质分解速率的主控因素也是如此。此外，关于底土中不同性质的空间变异性的信息也很少。现有的将近红外和中红外光谱(NIRS/MIRS)与地统计学方法相结合的少数研究表明，有可能创建空间地图，显示土壤剖面中生物活动增加的热点及其对C含量分布的影响。目标是：(I)通过结合14C测量，通过应用分级程序来确定底土C在不同组分中的平均停留时间；(Ii)研究水分含量、13C标记的根和溶解有机质的输入以及空间不可达性对自动微观系统中C周转的影响；(Iii)利用近红外光谱和微红外光谱确定土壤的一般性质和土壤生物化学特征；以及(Iv)利用不同的空间内插技术将测量和估计的土壤性质外推到垂直剖面。对于NIRS/MIRS应用，样品前处理(风干样品与冷冻干燥样品)和校准程序(改进的偏最小二乘法(MPLS)方法与遗传算法与MPLS或PLS相结合)将得到优化。我们假设化学分馏结合14C测量和孵化实验的结果将得到被动、中间、不稳定和非常不稳定的C和N的池大小以及不稳定和非常不稳定的C和N的平均停留时间。这些结果将使PC子项目开发的新的定量模型的初始化成为可能。此外，我们假设样品的前处理“冷冻干燥”将比风干更适用于土壤生物学特性的评估。遗传-最大似然法和遗传-最小二乘法比最大似然法和最小二乘法能更好地估计土壤特性。不同土壤特性的空间分布图与土壤温度和水分的空间分布图相结合，可以解释土壤中碳含量的空间异质性。