Modelling Amazonian Carbon Budgets and Vegetation Dynamics in a Changing Climate

Modelling the Amazon terrestrial carbon budget and vegetation dynamics is still at an early stage, despite the large amount of research on dynamic vegetation models and landatmosphere exchange. We give an overview of the most important issues and state of the art until 2014 concerning the modelling of carbon budgets and vegetation dynamics of the Amazon forests, and tropical forests in general. This includes water relations, temperature dependence, CO2 and nutrient dependence, patterns in growth and mortality, and fire. In water relations, it is most urgent to better represent in models the different plant strategies in avoiding water stress. Models need to adopt temperature dependence for primary production and respiration that is both representative for tropical conditions and is also able to acclimate to changing climate. To enable realistic response to increasing CO2 levels, it is essential that models include dependence on soil nutrients in a dynamic way, including feedbacks of changing vegetation on nutrient availability. For that, and also to better understand the spatial variation of biomass over the Amazon, dynamic allocation modelling and better understanding of tree mortality processes are essential which both need to move away from assuming fixed rates. Finally, the implementation of fire needs improving in all models. All in all, this chapter presents both a challenging research and experimental agenda and an outlook to more robust models for Amazonian vegetation in the near future.