MoLiCarb - Impacts of mosses and lichens on permafrost soil carbon dynamics since the last glacial

该项目将调查植被，特别是苔藓和地衣对高纬度土壤碳含量的重要性。这些地区的冻土碳与未来的气候有很大的相关性，因为这些土壤的融化可能会导致二氧化碳的大量排放，并对全球变暖产生积极的反馈。然而，地球系统模型对这些排放量的预测是不确定的，因为高纬度地区的植被，特别是苔藓和地衣，对生态系统碳平衡的影响目前受到很大的限制。这是由于缺乏相应的代理数据时间序列模型输出验证，也因为苔藓和地衣迄今很少被考虑到植被模型。作为一个新的解决方案，我们将在我们计划的项目中使用沉积古DNA（sedaDNA）来量化冰川-间冰期时间尺度上永久冻土区植被，气候和土壤C之间的长期关系。分析方法的进展（申请人U。Herzschuh）的研究使得确定植物的分类组成成为可能，包括苔藓和地衣，在sedaDNA及其与土壤C含量的关系。我们将应用这些发现来创建和验证一个新版本的基于过程的LiBry植被模型，该模型由申请人P. Porada开发。LiBry模型能够根据气候和其他环境数据计算苔藓和地衣群落的生理特性和多样性及其对生态系统C平衡的影响。这项工作将分为两个相辅相成的分项目（A、B），每个分项目又分为三个工作包，最后将有一个综合工作包。分项目A的目的是调整和评价最先进的sedaDNA方法（包括元条形码、鸟枪测序和捕获方法），以确定现代永久冻土中的植物分类群，包括苔藓和地衣;并将其应用于东西伯利亚的永久冻土剖面，可追溯到最后一次冰期及以后，与传统的古生态学方法相结合。所有材料都是在以前的实地工作中收集的。在子项目B中，LiBry模型将通过永久冻土区最相关的土壤过程和更新的维管植被进行扩展，创建新版本的LiBry-PERM。将使用WP A中收集的替代数据验证模拟的土壤碳含量以及苔藓和地衣的比例。有了新的LiBry-PERM，将有可能重建自末次冰期以来高纬度地区冻土土壤C的动态。最后，在合成WP中，我们将使用LiBry-PERM来预测未来几十年的冻土土壤C，同时考虑苔藓和地衣的影响。因此，我们将为未来地球系统模型的改进做出实质性贡献，这些模型估计了永久冻土土壤C对全球变暖的作用。

This project will investigate the importance of vegetation, in particular mosses and lichens, for soil carbon (C) content at high latitudes. Permafrost soil C in these regions is of great relevance for future climate, since thawing of this soil will likely lead to strong emissions of CO2 and a positive feedback on global warming. The prediction of these emissions by Earth system models is uncertain, however, since the effects of vegetation at high latitudes, especially of mosses and lichens, on the ecosystem C balance are currently poorly constrained. This is due to the lack of respective proxy-data time-series for model output validation and also because mosses and lichens have so far rarely been taken into account in vegetation models. As a new solution to this problem, we will use sedimentary ancient DNA (sedaDNA) in our planned project to quantify the long-term relationships between vegetation, climate and soil C in permafrost areas on the glacial-interglacial time-scale. Advances in analytical methods (applicant U. Herzschuh) have made it possible to determine the taxonomic composition of vegetation, including mosses and lichens, in sedaDNA and its relationship to soil C content. We will apply these findings to create and validate a new version of the process-based LiBry vegetation model which was developed by applicant P. Porada. The LiBry model is able to calculate the physiological properties and diversity of moss and lichen communities and their effects on the C balance of ecosystems on the basis of climate and other environmental data. The work will be organized into two complementary sub-projects (A, B), each divided into three work packages (WP), which will be concluded with a synthesis WP. Subproject A aims at the adaptation and evaluation of cutting-edge sedaDNA methods (including metabarcoding, shotgun sequencing and capture approaches) for identification of vegetation taxa, including mosses and lichens, in modern permafrost soils; and their application to permafrost soil sections in eastern Siberia reaching back to the last glacial and beyond in concert with traditional palaeoecologcial methods. All material was collected during previous field works. In subproject B, the LiBry model will be extended by the most relevant soil processes of permafrost regions and updated vascular vegetation, creating a new version LiBry-PERM. The simulated soil C content and the proportions of mosses and lichens will be validated using the proxy data collected in WP A. With the new LiBry-PERM, it will be possible to reconstruct the dynamics of permafrost soil C at high latitudes since the last glacial. In the synthesis WP we will, finally, use LiBry-PERM to predict permafrost soil C for the next decades, taking into account the effects of mosses and lichens. Thus, we will make a substantial contribution to the improvement of future Earth system models, which estimate the role of permafrost soil C for global warming.