This study was aimed at building a basic database of natural forest ecosystems. It incorporated a detailed and exhaustive survey and recorded all of the spatial positions and other data of individual plants. The records were used to create a two-dimensional distribution map, which was then used to discuss α-diversity, species population ecology, distribution patterns, spatial structures and successions of plant community in order to lay an initial foundation of the integration and conservation technology in the broad leaf forests in the Nansi area. The following is a summary of the research results: 1. There were more than ten plant societies (for example the spruce community) located from Tataka saddle to Meilan saddle of the Nansi Forest Road. There was a tremendous social diversity from conifer forests to broad leaf forests, and evergreens to secondary deciduous forests, with the spruce forest ranking number one in Taiwan and also having the best forest ecosystem in the west part of Yushan National Park. 2. Broad leaf forest stands of permanent sample plot could be classified as the “Castanopsis carlesii－Michelia compressa－Cyclobalanopsis stenophylla community” based on its dominant species. It has a complete spatial structure differentiation. 3. The surface area of the forest stands was tabulated and a graph of the species numbers was constructed, which marked the first time that a detailed measurement of Taiwan’s species diversity was conducted. It can be determined from the graph that there are 72.9 species of plants per 100 m2. 4. A two-dimensional distribution graph and an age structure chart for the population of the main species in the forest stands were constructed.