Abstract: Landscape pattern optimization is popular yet difficult in landscape ecology. The ecological safety of the three Gorges Reservoir region, which is the ecological link between the upper and middle reaches of Yangtze River, becomes a top priority. This paper selects Fengjie County as the research region and builds the leastcost distance model to study the landscape ecological security pattern and function division in the research region by considering land use, topographic index, and soil erosion as the resistance factors, with support of GIS technology to deal with landscape map in 2012. In order to enhance the stability of landscape ecological pattern and improve the ecological functional division, this paper constructs the landscape pattern components consisting of ecological sources, ecological corridors and strategic points based on the leastcost resistance surface to strengthen and improve the spatial connectivity of ecological network. According to the cost resistance mutation point, the research region is divided into four functional areas including water conservation area, ecological buffer area, ecological sensitive area, production and living area, and the proportions of each area are 36.74%, 24.16%, 15.48% and 23.62%, respectively. At the same time, the expansion of construction land is simulated by integrating the natural and social economic factors so as to provide a reasonable basis for the planning of urban expansion.

Key words: apple tree, new shoot growing stage, soil nitrogen budget., germination stage, nitrogen level, nitrogen fate