Abstract: Based on the fact that its ecological deterioration, a rethinking on the former definition of 'transitional zone between agriculture and grassland' was proposed. It was recognized that this zone has been gradually and dynamically formed under the specific circumstances of history and anthroponomy in China. It should thus be re defined as 'ecotone between agriculture and pasture',instead of just focusing on its features of geography, ecology, and vegetation separately, as well as its character of transition. More attention should be put on its nature of complex system of ecology, society and economy, and then, derive relevant abating measures. Boreal ecotone has the functions of life support for a relatively dense population, as well as ecosystem services. Under the premise of unable copying the models for arid and semiarid areas in abroad, in particular developed countries, an unique strategy of capable of compromising both above mentioned functions, as well as ecological reconstruction, which is embodied in readjusting agro structure, rationally utilizing and conserving resources, and establishing 'polar' industries, such as grasses and livestock, should be the center of an interdisciplinary study approach.

Key words: surface drip irrigation, soil nitrogen, tree growth, water and nitrogen coupling, stem volume