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地区土壤碳(C)含量的重要性。这些地区的永久冻土土壤C与未来气候关系重大，因为这些土壤的融化可能导致大量二氧化碳排放，并对全球变暖产生积极反馈。然而，地球系统模型对这些排放的预测是不确定的，因为高纬度植被，特别是苔藓和地衣对生态系统C平衡的影响目前还很有限。这是由于缺乏用于模型输出验证的相应代理数据时间序列，也因为迄今为止在植被模型中很少考虑苔藓和地衣。作为这一问题的新解决方案，我们将在计划的项目中使用沉积古DNA （sedaDNA）在冰期-间冰期时间尺度上量化多年冻土区植被、气候和土壤C之间的长期关系。分析方法的进步（申请人U. Herzschuh）使确定土壤中植被（包括苔藓和地衣）的分类组成及其与土壤碳含量的关系成为可能。我们将应用这些发现来创建和验证由申请人P. Porada开发的基于过程的lib植被模型的新版本。LiBry模型能够基于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碳平衡的影响。这项工作将分为两个互补的子项目（A、B），每个子项目又分为三个工作包（WP），每个工作包将以一个综合WP结束。子项目A旨在适应和评估先进的sedaDNA方法（包括元条形码、霰弹枪测序和捕获方法），以识别现代永久冻土中的植被分类群，包括苔藓和地衣；以及它们与传统的古生态学方法相结合，在东西伯利亚可追溯到末次冰期及更久的永久冻土部分的应用。所有材料都是在以前的野外工作中收集的。在子项目B中，LiBry模型将通过多年冻土区最相关的土壤过程和更新的维管植被进行扩展，创建一个新版本的LiBry- perm。模拟的土壤C含量以及苔藓和地衣的比例将使用WP a收集的代理数据进行验证。利用新的lib - perm，将有可能重建末次冰期以来高纬度地区永久冻土土壤C的动态。最后，在综合WP中，考虑到苔藓和地衣的影响，我们将使用lib - perm来预测未来几十年的永久冻土土壤C。因此，我们将对未来地球系统模型的改进做出重大贡献，这些模型将估计永久冻土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.