Cellular Automaton Vegetation with Gridded Meteorology

This tutorial demonstrates implementation of the Cellular Automaton Tree-GRass-Shrub Simulator (CATGRaSS) [Zhou et al., 2013] on a flat domain. This model is built using components from the Landlab component library. CATGRaSS is 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 of 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_flat_domain.ipynb (this notebook)
- Inputs_Vegetation_CA.txt (Input parameters for the model)
- Ecohyd_functions_flat.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]

本教程演示了在平面域上实现细胞自动机树-草-灌木模拟器（CATGRaSS）[周等，2013]的方法。该模型采用Landlab组件库中的组件构建。CATGRaSS是一种空间显式的植物共存模型。它模拟了由降雨和太阳辐射驱动的局部生态水文学动态（土壤湿度、蒸散量、生物量）以及树木、草本植物和灌木植物功能类型（PFT）的空间演变。在模型网格的每个单元格中，可以容纳单一PFT或保持空白。树木和灌木植物将种子散布到其相邻单元格。假设每个单元格中都有草本植物种子。空白单元格中植物的建立是通过基于每个PFT的水分胁迫概率来确定的。水分胁迫较低的植物有更高的建立概率。植物的死亡率通过模拟老龄化、干旱胁迫等概率性因素来模拟。模型将很快增加火灾和放牧的模拟。该模型（驱动程序）包含以下内容：
- 一个局部植被动态模型，该模型通过耦合以下组件来模拟风暴和风暴间水分平衡、生态水文学通量（蒸散量、径流）和植物生物量动态：
- 降水分布
- 辐射
- 潜在蒸散量
- 土壤湿度
- 植被
- 一个空间显式的概率性细胞自动机组件，该组件通过跟踪植物基于土壤湿度胁迫的建立和死亡率来模拟植物竞争：
- VegCA
运行此Jupyter笔记本时，请确保以下文件位于同一文件夹中：
- cellular_automaton_vegetation_flat_domain.ipynb（此笔记本）
- Inputs_Vegetation_CA.txt（模型的输入参数）
- Ecohyd_functions_flat.py（实用函数）
[参考文献：周X，伊斯坦布尔卢奥卢E，维沃尼E.R.。“模拟半干旱气候中受方位控制的辐射对树木-草本植物-灌木植物共存生态水文学作用的模型。”水资源研究49.5（2013）：2872-2895]