The Ecology Notes presented in this book are intended for students in the fourth year of the scientific humanities, mainly those in the chemistry-biology option in the Democratic Republic of Congo. They can also be used as a textbook for students in the first years of Higher Education and University.In the current nomenclature, the fourth year of the scientific humanities represents what used to be called the sixth year of secondary school, sixth chemistry-biology, the class in which students prepare for state examinations in the Democratic Republic of Congo.Ecology is one of the chapters that make up the biology course in high school. It is therefore important to provide students or candidates for the state exams with notes that will allow them to assimilate the course or to prepare themselves well.