The theoretical basis of my research project is how abiotic factors such as the presence of water and topography influence vegetation distribution and abundance. Some ecological processes that relate to my hypothesis are the water cycle and nutrient flow. The ideas that underpin my research are that topography and the presence of flowing water will influence vegetation abundance within the same forest ecosystem. Keywords that would describe my research would be topographic influence, vegetation abundance, and hydrological influence.
A good start to the theoretical basis that will form your introduction. You will have to dig deeper into these ideas for your intro and find some relevant references.