15.01.2024 15:00 Eun Joo Kim (TUM):
Multimodal Tropical Tree Cover States in Monostable Dynamical Systems - Reconsidering theory and observationsOnline: attend (945856)

The Amazon rainforest, as one of the world’s largest ecosystems vulnerable to climate change, presents a crucial topic of study regarding the potential transition from forest to savanna states in the region. The presence of multiple modes in the tree cover distribution has been attributed to the existence of multistable states in the system. However, theoretical findings suggest that multimodality can also arise within a monostable system. This study further explores the feasibility of generating multimodality within the dynamical system. It introduces two monostable models: the first involves two variables following either a step or sigmoid function of tree cover, while the second includes two variables (temperature and precipitation) with unimodal input, along with an additional unknown variable featuring bimodal input. The second model incorporates productivity and mortality dynamics dependent on temperature and precipitation characteristics. The interaction between the lower and higher levels of the step or sigmoid function of tree cover could lead to the emergence of trimodality in the first model, while the presence of an additional variable with bimodal input played a pivotal role in generating trimodality in the second model. Both models are capable of generating multimodal frequency distributions of tree cover, highlighting that the presence of multistability alone is not a prerequisite for multimodality. However, the identification of pertinent empirical variables for these models remains indispensable.