Thereupon , in the 3rd chapter , the characteristics of the ecological systems are discussed and the necessity of aggregation is proposed , then , the method of choosing macro - variables is discussed , and the aggregation method for the systems of ordinary differential equation is proposed . in the 4th and 5th two examples : the model of single population and the model of two populations in different environment are discussed , the method which have proposed in 3rd chapter is implemented in the two examples 同時在第四章和第五章中分別介紹生態(tài)系統中的兩種情況:單物種的發(fā)展模型和兩物種在不同環(huán)境中競爭的模型,分別介紹了對這兩種模型建立過程,并且應用第3章中介紹的方法對上述兩種模型進行聚合。然后,對聚合后的聚合模型進行分析,得到聚合模型的穩(wěn)定狀態(tài)。