Soil aeration - the key factor of oak decline?

这是一种“复杂的疾病”。这一结果因其模糊性而难以证伪。致病真菌的重要贡献并非没有争议，因为主要致病性尚未得到证实（Johnsson，2004）。我们的出发点是Gaertig等人（2002）的研究，他们发现在巴登-符腾堡州的28个橡树林的空间整合水平上，橡树健康的症状与土壤通气性显著相关。在过去的几十年里，橡树林土壤结构的大规模变化可以归因于伐木的机械化（Vossbrink和Horn，2004年）以及酸化土壤中土壤活性的降低。在建议的项目中，我们希望在三维空间中建立根与通气相关参数之间的关系。这个费力的过程是必要的，因为土壤-空气通道是高度异质的，并且通过这种方式形成三维图案。这使得一维模型效率低下。通过在三维空间中模拟土壤空气的进入，我们想测试通气假设。生根的重要指标是细根的聚集，坏死或空间歧视。通过在同一空间分辨率下同时评估土壤化学和土壤物理参数，可以检验备选假设。作为建模工具，点统计，非参数回归（GAM），和一个三维的解决方案的不稳定的气体扩散方程将被使用。

it is a „complex disease . This result can hardly be falsified because of its fuzziness. A significant contribution of pathogenic fungi is not without controversy, because the primary pathogenicity is not proven (Johnsson, 2004). Our starting point is the research of Gaertig et al. (2002) who found that on a spatial integration level of 28 oak stands in Baden-Wuerttemberg the symptoms of oak health are significantly correlated with soil aeration. Large-scale changes of soil structure in oak stands during the last decades can be attributed to the mechanization of logging (Vossbrink and Horn, 2004) as well as to a decrease of earthworm activity in acidified soils. In the proposed project we want to establish a relationship between roots and aerationrelevant parameters in a three-dimensional space. This laborious procedure is necessary because the soil-air access is highly heterogeneous and by this way forms a three-dimensional pattern. This makes one-dimensional models inefficient. By modelling the soil air access in a three-dimensional space we want to test the aeration hypothesis. Important indicators of rooting are clustering of fine roots, necrosis, or space discrimination. By assessing simultaneously soil-chemical and soil-physical parameters in the same spatial resolution, alternative hypotheses can be tested. As modelling tools point statistics, non parametric regression (GAM), and a three dimensional solution of the instationary gas-diffusion equation will be used.