| Due to the acceleration of climate warming in the 21st century and global ecological deterioration,the impacts of climate warming on ecosystem structure and functions have received great attention.Trait-based food web models are often used to predict ecosystem dynamics and characterize interactions between species by defining individual traits.Here species are characterized by three traits including body size,habitat trait,and optimal temperature.In this thesis,climate warming is added to the model to explore the cliamtic impacts on food web dynamics.Chapter 1 first summarizes warming history and its future and its trends.Then,we review the main impacts of climate warming on ecosystem dynamics from the perspectives of individuals,populations and communities,respectively.Finally,we propose our research questions and elaborate the research diagram.Chapter 2 describes in detail the trait-based food web model and particularly the impacts of temperature on individual physiology.We also perform dimensional scaling to reduce parameters.Then we demonstrate how to perform community assembly to mimic the progress of development of food web.Finally,based on collected climate data,we propose three warming patterns including uniform rise,normally distributed rise,and fluctuating rise.Chapter 3 shows long-term and short-term impacts of climate warming on closed food webs that do not allow for alien invasion.Results show that the four ecosystem functions such as species richness,primary productivity and maximum trophic level all show a downward trend,whereas the extent become more severe in the long-term warming situation.Interestingly,the averaged temperature of the ecosystem generally increases from 10℃ to about 12 ℃ in most simulations,indicating that the competitiveness of species with large temperature traits in the ecosystem is advantageous in the long-term warming situation.Chapter 4 collects the global invasion data,and reviews the history of global biological invasions.Based on these data,we identify three different species invasion mode.Different from Chapter 3,we couple the progress of climate warming and species invasion.Results show that regardless of whether the effects of warming are long-term or short-term,the pattern of species invasion is critical to the impacts of climate warming on food web dynamics.With random alien invasion,,ecosystem functions are enhanced by climate warming,except for the primary productivity,which declines only slightly.As for the other two invasion modes,ecosystem functions are negatively affected by climate warming.These findings suggest that invasion by species either at high trophic level or low trophic levels is detrimental to food web dynamics.Consistent with the climate impacts on closed ecosystems,long-term impacts lead to an increase in species richness and a decrease in maximum trophic levels.The final chapter summarizes the results of this research and come up with some thoughts and prospects for future research. |
