Mangrove-Saltmarsh ecotone patterns as indicators for critical impacts of sea level rise and climate change on coastal wetlands – MASCOT

背景：亚热带滨海湿地通常由红树林和盐沼组成。虽然红树林大多位于经常被淹没的地区，但盐沼主要位于较干燥的地区，通常是高盐地带。两种生境类型之间的过渡被称为“红树林-盐沼过渡带”，是非生物因子对红树林和盐沼植被不同影响的指标。同时，植物也改变了当地的非生物和生物环境。这些双向反馈产生了典型的植被模式，例如植被的高度结构及其从突发性到漫漫性转变的清晰度。由于非生物条件的变化导致过渡带及其植被格局内的级联效应，它们可能是气候引起的变化及其对海岸稳定性和生态系统服务的影响的极好指标。根据对山地和北方树木谱系变化的研究，我们假设红树林-盐沼过渡带的形状是预测其对气候变化响应的关键。目的：通过这个项目，我们希望有助于对过渡带模式及其动态的机制的一般理解。我们想了解洪水与淡水输入相结合是如何塑造植物群落的，植物是如何设计它们的栖息地的，这些相互作用是如何导致观察到的栖息地类型的分区，它们的过渡区是如何形成的，以及在海平面上升和降雨改变的情况下可以预期的趋势。这将使我们能够利用红树林-盐沼交错带格局的变化作为（亚）热带海岸水文状况的观测和预测变化的关键影响指标。方法：我们将通过几个组件扩展红树林生态系统的机制模拟模型方法MANGA。这些包括对盐沼植物的描述，盐沼所需的不饱和土层，以及红树林的生理可塑性。新的Mascot模型将描述盐沼植物、红树林灌木、红树林树木和土壤水分之间的相互作用，从而可以模拟整个红树林-盐沼交错带。与来自中南美洲、亚洲和澳大利亚的合作伙伴一起，我们将系统地研究在变化的水文条件下不同过渡带模式的出现、持续和时间变化。在此基础上，我们将制定指标，通过交错带格局的时空变化，在早期阶段检测环境变化的强度和动态。

Background: (Sub)tropical coastal wetlands often consist of mangroves and salt marshes. While mangroves are mostly located in the regularly flooded zone, salt marshes dominate the upper drier, often hypersaline zone. The transition between the two habitat types is called "mangrove-saltmarsh ecotone" and is an indicator of the different effects of abiotic factors on mangrove and salt marsh vegetation. At the same time, plants change their local abiotic and biotic environment. These bidirectional feedbacks result in characteristic vegetation patterns that are reflected, for example, in the height structure of the vegetation and the sharpness of their transition, from abrupt to diffuse. Since changes in abiotic conditions lead to cascading effects within ecotones and their vegetation patterns, they might be excellent indicators of climate-induced changes and their consequences for coastal stability and ecosystem services. Following research on mountainous and boreal tree lineage shifts, we therefore hypothesise that the shape of mangrove-saltmarsh ecotones is the key to predicting their response to climate-induced change.Aim: With this project we want to contribute to the general understanding of the mechanisms underlying ecotone patterns and their dynamics. We want to understand how the flooding regime in combination with freshwater input shapes the plant community, how plants engineer their habitat, how these interactions lead to the observed zonation of habitat types, how their transition zone is formed and what trends can be expected under rising sea level and under altered rainfall regimes. This will allow us to use changes in patterns of mangrove-salt-marsh ecotones as indicators of critical impacts of observed and predicted changes in the hydrological regime of (sub)tropical coasts.Methods: We will extend the mechanistic simulation model approach MANGA for mangrove ecosystems by several components. These include the description of saltmarsh plants, the unsaturated soil layer required for saltmarshes, and the physiological plasticity of mangroves. The new Mascot model will describe the interactions between saltmarsh plants, mangrove shrubs, mangrove trees and soil water and thus allow the simulation of the entire mangrove-saltmarsh ecotone. Together with cooperation partners from South and Central America, Asia and Australia, we will systematically investigate the emergence, persistence and temporal shift of different ecotone patterns under changing hydrological conditions. Based on this, we will develop indicators by which the intensity and dynamics of environmental changes through spatio-temporal shifts in ecotone patterns can be detected at an early stage.