Diversity, functionality and evolution of medullosan seed ferns: Vegetation-climate interactions in a seasonally dry in-situ habitat of early Permian age

髓子蕨的多样性、功能和进化：二叠纪早期季节性干燥原地栖息地的植被与气候相互作用

基本信息

批准号：
426451586
负责人：
Dr. Ludwig Luthardt
金额：
--
依托单位：
UMR AMAP - botAnique et Modélisation de lArchitecture des Plantes et des végétations
依托单位国家：
德国
项目类别：
Research Fellowships
财政年份：
2019
资助国家：
德国
起止时间：
2018-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/426451586?language=en
关键词：
Diversity functionality evolution medullosan seed

项目摘要

The project focuses on the ecological and evolutionary dynamics of early Permian seed plants and their relationships to climate change in the late Palaeozoic. This period was characterised by extensive glaciation, comparable to the present Ice Age, whereas the Icehouse-Greenhouse transition in the early Permian is of particular interest. In contrast to the main glaciation phase in the Carboniferous, this period shows a considerable data gap regarding the CO2 partial pressure of the atmosphere. In palaeoclimate research, fossil plants play a key role, as they provide measurable parameters on precipitation, temperature, and CO2 content of the atmosphere. However, so far, these have only been obtained from isolated plant organs, what limits their palaeoecological significance. Among the widespread Permian seed plants, medullosans in particular offer an above-average water conduction potential quite comparable to that of modern broadleaved trees. Accordingly, they can be recognised as climate-sensitive and thus promising for palaeoclimate studies.Aims of the project are: 1) Investigating and reconstructing functionality of medullosans at their Permian type locality of Chemnitz, 2) whole-plant hydraulic modeling in order to contribute to optimising methods of plant palaeoclimate proxies, 3) evaluating a novel approach for the calculation of the CO2 partial pressure of the early Permian atmosphere.The fossils originate from the Chemnitz Fossil Forest, an in-situ preserved, oasis-like habitat of early Permian age (291 myrs), in which relationships between organisms and their environment can be investigated. The site offers a worldwide remarkable diversity of medullosans, dominating this dense hygrophilous plant community that was exposed to seasonal droughts. Due to rapid burial by volcanic deposits, some of the trees were found still standing upright enabling to study them at their places of growth by taking into account a variety of site-specific parameters such as palaeoclimate, soil, and vegetation.Three almost completely preserved medullosans will be investigated including various organs from the roots to the crown. The function of special, hitherto not reflected anatomical details suggests the comparison with modern cycads, the nearest living relatives of the medullosans. This includes an ecologically relevant water storage and supply system in the form of a hollow-cylindrical, horizontal tracheid network, as well as root structures that suggest a comparison with coralloid, symbiotically active cycad roots. All measurable parameters on the water conductivity potential of plants are to be determined and evaluated in the context of established calculation methods with regard to their palaeoecological significance. These anatomical data on water conductivity will be used to test a promising approach of modeling the CO2 partial pressure of the atmosphere, alternatively to the commonly applied method based on stomata density of leaves.

该项目重点研究早二叠世种子植物的生态和进化动态及其与晚古生代气候变化的关系。这一时期的特点是广泛的冰川作用，与现在的冰河时代相当，而二叠纪早期的冰室-温室过渡尤其令人感兴趣。与石炭纪的主要冰川期相比，这一时期的大气二氧化碳分压数据存在相当大的差距。在古气候研究中，植物化石发挥着关键作用，因为它们提供了有关降水、温度和大气二氧化碳含量的可测量参数。然而，到目前为止，这些只能从分离的植物器官中获得，这限制了它们的古生态意义。在广泛分布的二叠纪种子植物中，髓质植物尤其具有高于平均水平的导水潜力，与现代阔叶树相当。因此，它们可以被认为是气候敏感的，因此在古气候研究中很有前景。该项目的目标是：1）调查和重建开姆尼茨二叠纪类型地点的髓质植物的功能，2）全植物水力建模，以贡献优化植物古气候代理方法，3）评估计算早二叠世大气二氧化碳分压的新方法。化石来自开姆尼茨化石森林 (Chemnitz Fossil Forest)，是一个原位保存的、二叠纪早期（291 迈尔斯）的绿洲状栖息地，可以在其中研究生物与其环境之间的关系。该地点提供了世界范围内显着的髓类植物多样性，在这个遭受季节性干旱的茂密嗜湿植物群落中占主导地位。由于火山沉积物的快速掩埋，一些树木被发现仍然直立，从而可以通过考虑各种特定地点的参数（例如古气候、土壤和植被）来研究它们的生长地。三棵几乎完全保存下来将研究髓质，包括从根到冠的各种器官。迄今为止尚未反映的解剖细节的特殊功能表明与现代苏铁类植物（髓类植物最近的亲戚）的比较。这包括一个与生态相关的水储存和供应系统，其形式为空心圆柱形、水平管胞网络，以及与珊瑚状、共生活跃的苏铁根进行比较的根结构。植物水电导率的所有可测量参数均应在已建立的计算方法的背景下确定和评估其古生态意义。这些水电导率的解剖数据将用于测试一种有前途的大气二氧化碳分压建模方法，以替代基于叶子气孔密度的常用方法。