Abstract: Eco-redline is supposed to be the minimum area that should be strictly protected to ensure the regional eco-health and eco-service sustainability. To draw the eco-redline scientifically would be an effective way to improve eco-function. In this paper, we summarized the previous studies and rebuilt the eco-redline framework including eco-function redline, environment redline and resource redline by considering eco-function, environment and resource categories, respectively, which could be worked on time, space and management. The three redlines together constitute the urban eco-redline framework system. By taking eco-function redline as example, and from the aspect of ecosystem itself, we proposed a method to demarcate eco-function redline based on the pattern, process, function and amenity of urban system. Using Jixian County in Tianjin as an example, we draw out the regional eco-function redline with a total area of 11425 hm², which is mainly distributed in north mountain and river basins of Jixian. Combined with the regional characteristics and the corresponding eco-redline area, we also put forward some corresponding control measures. The exploration of our study in theory, method, model and application provides theoretical and methodical supports for further study on eco-redline in future.

Key words: nitrogen fertilizer, phosphorus fertilizer, potas-sium fertilizer, yield, watermelon, organic fertilizer