Cellular_Automaton_Vegetation_on_Actual_Landscape

This tutorial demonstrates implementation of the Cellular Automaton Tree-GRass-Shrub Simulator (CATGRaSS) [Zhou et al., 2013] on a digital elevation model (DEM). This model is built using components from the Landlab component library. CATGRaSS is a spatially explicit model of plant coexistence. It simulates local ecohydrologic dynamics (soil moisture, transpiration, biomass) and spatial evolution of tree, grass, and shrub Plant Functional Types (PFT) driven by rainfall and solar radiation. Each cell in the model grid can hold a single PFT or remain empty. Tree and shrub plants disperse seeds to their neighbors. Grass seeds are assumed to be available at each cell. Establishment of plants in empty cells is determined probabilistically based on water stress for each PFT. Plants with lower water stress have higher probability of establishment. Plant mortality is simulated probabilistically as a result of aging and drought stress. Fires and grazing will be added to this model soon. This model (driver) contains: - A local vegetation dynamics model that simulates storm and inter-storm water balance and ecohydrologic fluxes (ET, runoff), and plant biomass dynamics by coupling the following components: - PrecipitationDistribution - Radiation - PotentialEvapotranspiration - SoilMoisture - Vegetation - A spatially explicit probabilistic cellular automaton component that simulates plant competition by tracking establishment and mortality of plants based on soil moisture stress: - VegCA To run this Jupyter notebook, please make sure that the following files are in the same folder: - cellular_automaton_vegetation_DEM.ipynb (this notebook) - Inputs_Vegetation_CA.txt (Input parameters for the model) - Ecohyd_functions_DEM.py (Utility functions) [Ref: Zhou, X, E. Istanbulluoglu, and E.R. Vivoni. \"Modeling the ecohydrological role of aspect-controlled radiation on tree-grass-shrub coexistence in a semiarid climate.\" Water Resources Research 49.5 (2013): 2872-2895]本教程演示了元胞自动机树木-草本-灌木模拟器（Cellular Automaton Tree-Grass-Shrub Simulator, CATGRaSS）[Zhou等人，2013]在数字高程模型（Digital Elevation Model, DEM）上的实现。该模型基于Landlab组件库构建。CATGRaSS是一款空间显式的植物共存模型，可模拟由降雨与太阳辐射驱动的局地生态水文动态（包括土壤湿度、蒸腾作用与生物量变化），以及树木、草本与灌木三类植物功能类型（Plant Functional Types, PFT）的空间演化过程。 模型网格中的每个单元格可承载单一植物功能类型，或保持空置状态。树木与灌木会将种子散播至相邻单元格，而草本种子默认在所有单元格均可获取。空置单元格内的植物定植概率由各植物功能类型的水分胁迫水平决定，水分胁迫程度越低，定植概率越高。植物死亡过程通过基于衰老与干旱胁迫的概率机制模拟实现。后续将为该模型添加火灾与放牧模拟模块。 本模型（驱动脚本）包含两大核心模块： 1. 局地植被动态模型：通过耦合以下组件，模拟暴雨与间歇期的水量平衡、生态水文通量（蒸散、径流）以及植物生物量动态： - 降水分布（PrecipitationDistribution） - 辐射（Radiation） - 潜在蒸散（PotentialEvapotranspiration） - 土壤湿度（SoilMoisture） - 植被（Vegetation） 2. 空间显式概率元胞自动机组件：通过追踪基于土壤水分胁迫的植物定植与死亡过程，模拟植物竞争关系： - 植被元胞自动机（VegCA） 若要运行本Jupyter Notebook，请确保以下文件处于同一工作目录中： - cellular_automaton_vegetation_DEM.ipynb（本笔记本文件） - Inputs_Vegetation_CA.txt（模型输入参数文件） - Ecohyd_functions_DEM.py（工具函数文件） [参考文献：Zhou, X, E. Istanbulluoglu 及 E.R. Vivoni. "Modeling the ecohydrological role of aspect-controlled radiation on tree-grass-shrub coexistence in a semiarid climate." Water Resources Research 49.5 (2013): 2872-2895]