Physiology and stable isotope ecology of moss growth for modelling spatial and temporal climatic signals

气候变化的影响预计将在极地地区特别强烈。在以苔藓为主要栖息地的北极地区，更温暖、更潮湿的条件可能会导致永久冻土融化和苔藓生长增加，而森林则会减少。我们现有的工作包括开发创新的模型，利用有机物的稳定同位素组成来提供关于苔藓生长的信息。这项工作既包括在南极泥炭苔藓岸边保存了数千年的苔藓，也包括通常生长在屋顶和小路上并在一场阵雨后迅速激活的耐干燥苔藓。我们以前的工作表明，碳的稳定同位素组成为苔藓生长季节和气候变化的影响提供了可靠的指标。然而，与降水输入和水蒸气交换有关的水中其他自然产生的稳定同位素信号(例如水中的18O)，到目前为止还没有被很好地定义为蒸发需求的标志。在这个建议中，我们将增加对苔藓生长动力学的理解，包括植物如何响应不同的蒸发条件，不同类型的苔藓如何生长，什么条件最有利于固定大气中的二氧化碳和通过合成有机物生长。苔藓生理学方面的这些发展将与当地的天气条件结合在一起，形成苔藓生长模型，可以在大范围内应用，以预测植物的生长期。我们将进行实验室实验，利用同位素标记和不同温度、湿度和干燥条件下的生长反应来操纵、监测和测量苔藓的生长。我们将致力于苔藓物种的研究，这些苔藓物种生长在从潮湿的泥炭沼泽到形成多毛类植物的山丘，再到耐干燥的合毛植物。在田间尺度上，同样的苔藓将在它们的自然环境中进行定期监测，以测试实验确定的动态如何应用于与生态相关的环境中。实验室和野外测量的结合将首先使我们能够确定随着气候条件的变化对苔藓有机质18O组成的控制。其次，将使用新开发的LIFT(激光诱导荧光瞬变)技术从几米远的地方进行遥感实地测量。通过在更大的空间尺度上了解苔藓生长动态和光合作用激活之间的联系，我们将建立一个基线，使未来能够使用遥感方法，如飞机和卫星的测量，来监测苔藓的表现。

The impact of climate change is predicted to be particularly intense in polar regions. Warmer and wetter conditions in the Arctic, where extensive moss dominated habitats are found, could lead to melting of permafrost and an increase in moss growth whilst forests decline. Our existing work has included developing innovative models which use the stable isotope composition of organic matter to provide information about moss growth. This work incorporated both moss preserved for thousands of years in Antarctic peat-moss banks, and desiccation-tolerant mosses that commonly grow on roofs and paths and are rapidly activated following a rain shower. Our previous work has shown that the stable isotope composition of carbon provides a reliable indicator of moss growing season, and the impact of climate change. However other naturally-occurring stable isotope signals in water (e.g 18O in water), associated with precipitation inputs and water vapour exchange, have until now been less well defined as markers of evaporative demand.In this proposal, we will increase our understanding of moss growth dynamics to include how plants respond to different evaporative conditions, how different types of moss grow, what conditions are best for the fixation of carbon dioxide from the atmosphere and growth through the synthesis of organic matter. These developments in moss physiology will be integrated with local weather conditions in models of moss growth that can be applied across large areas to predict periods of plant growth. We will carry out laboratory experiments in which moss growth is manipulated, monitored and measured, using isotope labels and growth responses under different temperature, humidity and drying regimes. We will work on moss species that grow in a range of habitats from wet bog Sphagnums, through hummock forming Polytrichales to desiccation tolerant Syntrichia. At the field scale, the same mosses will be regularly monitored in their natural environment, testing how the experimentally determined dynamics apply within an ecologically relevant setting. The combination of lab and field measurements will firstly allow us to determine the controls on moss organic matter 18O composition as climatic conditions vary. Secondly, remote sensing field measurements will be made from a distance of several metres using newly developed LIFT (laser induced fluouresence transient) technology. By understanding the link between moss growth dynamics and photosynthetic activation over this larger spatial scale we will establish a baseline that will allow remote sensing methodologies, such as measurements from aeroplanes and satellites, to be used to monitor moss performance in the future.