The thickness and composition of forest floors plays an essential role for the efficiency and resilience of mountain forests to store carbon, water and nutrients. Up to now, the distribution of particularly thick organic forest floors (TOFF) in the Bavarian Calcareous Alps is poorly known and their ecosystem services deserve increased consideration under climate change. We wanted to improve the knowledge of the TOFF-distribution and to investigate the forcing processes and ecological functions of TOFF. We aimed to quantify their carbon storage potential and to model areas in which humus management is mandatory for sustainable forest use. We drew a stratified sample of soil profiles. Through the combination of relief and soil parameters, we identified crucial control variables and modelled actual and potential (without human disturbance) forest floor thickness in the Bavarian Calcareous Alps based on quantile regression and Generalized Additive Models (GAM). TOFF were predicted to occur on approximately 10% of the forest area of the Bavarian Alps. A decisive condition for the development of TOFF was the absence or only shallow development of mineral fine soil. Contrary to conventional wisdom, these TOFF were found across a wide range of (montane to subalpine) elevations. C-storage of TOFF amounts to ca. 6.9 t C/ha per cm of humus depth and ca. 5.2 Mt C in the study area, resulting in C accumulations comparable to peatlands. TOFF are decisive for the delivery of ecosystem services, especially in the protection forests of the Bavarian Calcareous Alps. Due to the absence or ephemeral depth of mineral soil, all ecological functions depend solely on the forest floor. Therefore, the careful handling of the humus stock is mandatory for a sustainable management in these forests.

森林地层的厚度和组成对于山地森林储存碳、水和养分的效率和恢复力起着至关重要的作用。到目前为止，巴伐利亚钙质阿尔卑斯山中特别厚的有机林地层 (TOFF) 的分布知之甚少，在气候变化下，它们的生态系统服务值得更多考虑。我们想提高对 TOFF 分布的了解，并研究 TOFF 的强迫过程和生态功能。我们旨在量化它们的碳储存潜力，并模拟腐殖质管理对于可持续森林利用是强制性的区域。我们绘制了土壤剖面的分层样本。通过结合地形和土壤参数，我们确定了关键的控制变量，并基于分位数回归和广义加性模型 (GAM) 对巴伐利亚石灰质阿尔卑斯山的实际和潜在（没有人为干扰）森林地坪厚度进行了建模。预计 TOFF 将发生在巴伐利亚阿尔卑斯山大约 10% 的森林面积上。TOFF 发展的决定性条件是没有或仅浅层发育矿物质细土。与传统观点相反，这些 TOFF 被发现在广泛的（山地到亚高山）海拔范围内。TOFF 的 C 存储量约为。每厘米腐殖质深度和约 6.9 吨碳/公顷。5.2 研究区的 Mt C，导致与泥炭地相当的 C 积累。TOFF 对生态系统服务的提供具有决定性意义，尤其是在巴伐利亚石灰质阿尔卑斯山的保护森林中。由于矿质土壤的缺乏或短暂的深度，所有的生态功能都完全依赖于森林地面。因此，仔细处理腐殖质对于这些森林的可持续管理是必不可少的。