A field survey of plant biodiversity and environmental factors was conducted along the transect from higher Quercus mongolica-Abies koreana community to lower Quercus serrata-Carpinus tschonoskii community, relative altitudinal difference is about 1,000 m. The change patterns of vegetation, plant species, soil, climate with altitude were studied and analyzed in detail, and the implication of this kind of gradient change with environmental changes was probed. The sites were chosen systematically about 100-m intervals of altitude; with 3 plots surveyed at each altitude, plot dimensions of 20x20 m, with 27 plots sampled in total.  For the shrub survey, four 5x5 m subplots were sampled in each plot, the species and number of stems was recorded.  We estimated density, cover, and measured height and crown width of herbs by species in four 1x1 m subplots of each plot; if possible, species were recorded on site, otherwise, specimens were taken back for later identification.

Results/Conclusions . The general trend in total species richness along altitudinal gradient was that species numbers gradually increased up to 525 m, decreased and following two more peaks at 745m and 1330m. Soil organic matter along altitudes was unimodal, with the highest value in the forest belt Soil pH changed dramatically from low to high elevation, pH was greater at low than high altitudes.  The plant species richness appeared to fluctuate, and plant biodiversity change along altitude had patterns which correlated with climatic and soil factors. The relationships between plant richness to soil and topographical factors were explored using PCA.  The available Mg²⁺ and Ca²⁺ had negative relationships with species richness.  Elevation had close relationship with NPK, organic matter and CEC.  The plant species richness appeared to fluctuate, and plant biodiversity change along altitude had patterns which correlated with climatic and soil factors. Both of the peaks of plant biodiversity occurred in transition areas, one from middle ranges of Mt. Jiri and the other from Quercus mongolica-Abies koreana community containing rich soils.  It is likely that elevation ranges with high richness are transition zones in which the effects of temperature, soil water and local environmental factors matching the change in richness of plant species to environmental factors along altitudinal gradient.