A population dynamics model for analysing the effect of rainfall seasonality on vegetation in the Karoo

Govender, Serayen

A population dynamics model for analysing the effect of rainfall seasonality on vegetation in the Karoo

Thesis / Dissertation

2025

Publisher

University of Cape Town

Department

Department of Statistical Sciences

Faculty

Faculty of Science

Abstract

The flora of the Cape Floristic Region is amongst the most diverse and unique on the planet, due mainly to the unique climate of this region. The effects of climate change are threatening many sensitive ecosystems around the world and so it is important to understand how factors of climate change may affect the Cape Floristic Region. This paper investigates the effect of changing rainfall seasonality on certain important species of plants in the Cape Floristic Region. The species are selected from different biomes and I focus on two growth forms, namely reseeder and resprouter. Data from an experiment conducted between two biomes in the Cape Floristic Region is used to model the growth of the two growth forms post- fire. Rainfall in this experiment is artificially manipulated on replicated plots at the two experiment sites. The population growth is modelled using state-space models, incorporating both an ecological process model and an observation model. This allows us to account for errors both in the observation of the data as well as in the natural variability in the biological state process that generated the data in order to account for both measurement and process error. My results suggest that increased summer rainfall in the Cape Floristic Region has a positive effect on the populations of reseeder species in both biomes and has little effect on the populations of resprouter species. A multivariate state-space model is also proposed to investigate the effects of interactions of species growth, within the replicated plots.

Keywords

Vegetation

Karoo

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