Estimating impacts of non-vascular vegetation on global biogeochemical cycles from the geological past to the future

非维管植被，如地衣、苔藓植物、陆生蓝藻和藻类，被认为对全球生物地球化学循环有重要贡献，例如通过生产力和固氮作用。它们可能保护永久冻土免受未来变暖的影响，而且它们可能通过增强化学风化作用从而减少大气中的二氧化碳，在过去的地质时期造成了全球冰川。然而，关于非血管效应的定量知识仍然不完整，主要涉及对未来气候变化的响应，全球碳和营养收支的作用，以及整个地球历史对气候的影响。为了限制这些影响，需要一种基于过程的非维管植被建模方法。然而，目前的模型并不能充分代表基本过程。因此，我们将创建一个新版本的非维管植被模型LiBry，该模型将包括co2施肥下养分有效性对生产力的限制作用。我们将提供气候变化下未来生产力的第一个全球估计，并量化对未来永久冻土土壤温度和生物固氮的非维管效应。除了新的lib之外，我们还将开发一个风化模型，该模型将与lib结合，明确模拟非维管植被对生物增强化学风化的影响。随后，我们将把该模型应用于古生代和元古代的几个时期，量化早期非维管植被对过去气候和大气成分的影响。新图书馆的开发工作将由申请人负责，而化学风化模型将由一名博士生负责。合作者将进行实验，这将补充我们的工作，并将使未来的模型应用于区域和地方尺度。将我们的工作与全球地表模型JSBACH结合起来，将有助于研究与维管植被、火灾和泥炭地未来碳平衡的相互作用。我们的估计将有助于限制古气候和过去大气成分的模拟。波茨坦大学被选为主办机构，是因为它专注于植被建模、地球科学、生态学和进化，以及附近的研究机构GFZ、AWI和PIK。

Non-vascular vegetation, such as lichens, bryophytes, terrestrial cyanobacteria and algae, have been suggested to contribute significantly to global biogeochemical cycles, e.g. via productivity and nitrogen fixation. They may protect permafrost soil against future warming, and they probably caused global glaciations in the geological past, by enhancing chemical weathering and thereby reducing atmospheric CO2. However, quantitative knowledge on non-vascular effects is still incomplete, which mainly concerns the response to future climate change, the role for global carbon and nutrient budgets, and impacts on climate throughout Earth’s history. To constrain these effects, a process-based modelling approach for non-vascular vegetation is necessary. Current models, however, do not sufficiently represent the essential processes. For this reason, we will create a new version of the established non-vascular vegetation model LiBry, which will include the limiting effect of nutrient availability on productivity under CO2-fertilisation. We will provide a first global estimate of future productivity under climate change and also quantify non-vascular effects on future permafrost soil temperature and biological nitrogen fixation. Additionally to the new LiBry, we will develop a weathering model, which will, in combination with LiBry, explicitly simulate effects of non-vascular vegetation on biotic enhancement of chemical weathering. Subsequently, we will apply the weathering model to several periods in the Paleozoic and the Proterozoic, and quantify the impacts of early non-vascular vegetation on past climate and atmospheric composition. Development of the new LiBry will be performed by the applicant, while the model of chemical weathering will be developed by a PhD student. Collaborators will perform experiments, which will complement our work and which will enable future model application to regional and local scales. Combining our work with the global land surface model JSBACH, where LiBry is already integrated, will facilitate research on interactions with vascular vegetation, fire, and future carbon balance of peatlands. Our estimates will be useful to constrain simulations of paleoclimate and past atmospheric composition. Potsdam University is selected as the host institution due to its focus on vegetation modelling, Earth sciences, ecology and evolution, as well as the nearby research institutions GFZ, AWI, and PIK.