关键词: 水曲柳, 硝态N, 铵态N, pH值

Abstract: This paper discusses the position of urban districts in ecological study, role of principles of high efficiency and harmony in the reformation of urban districts and main problems required to be studied and solved in the respects of urban population, resource and environment.

Key words: Fraxinus mandshurica, Nitrate nitrogen, Ammonium nitrogen, pH value