| dc.description.abstract | Due to human impacts on Earth′s biological system, the study of how environmental change affects ecosystem functioning has become increasingly important. Research in this area began with examining how individual ecosystem functioning is affected by biodiversity loss. While research has shown that the loss of biodiversity negatively impacts ecosystem functions, the reasons for the different responses of functions to biodiversity loss and how to predict them are not yet fully understood. Moreover, the ecosystem is appreciated for its ability to perform multiple ecosystem functions simultaneously (i.e., ecosystem multifunctionality, EMF); moreover, factors other than diversity could impact ecosystem functioning. However, our current understanding of the underlying mechanisms that explain EMF, especially in terms of temporal variabilities, remains limited. In addition, environmental change could mediate the species loss in a non-random way. Yet, the understanding of the consequence of non-random loss on ecosystem functioning remains unclear. Therefore, the aim of this thesis is to comprehend how ecosystem functioning responds to environmental change, specifically through the prokaryotic community in Feitsui Reservoir, Taiwan. In particular, I demonstrated that the consequences of biodiversity loss on ecosystem functioning could be predicted by two specificity indices based on the number of species that promotes the functions and substrate complexity (Chapter 2). I identified primary factors influencing substrate-utilization based EMF at different temporal scales: biotic factor (diversity) for short-term dynamics, exogenous factor (temperature) for seasonal variations, and endogenous factor (dissolved organic carbon) for inter-annual patterns (Chapter 3). Additionally, I evaluated the potential influence of environmental change on ecosystem functioning by considering the non-random loss of species, which is influenced by their niche breadth in relation to resource utilization. By proposing a link to anticipate the relationship between niche breadth and functional potential under environmental change, I revealed that the functional potential could actually increase, thereby buffering the impact of harsh nutrient conditions (Chapter 4). In conclusion, this thesis provides a comprehensive understanding of how ecosystem functioning of prokaryotic community in Feitsui Reservoir responds to environmental change through different aspects, which is essential for developing effective management strategies to preserve the planet′s biodiversity and its services to humanity. | en_US |