Factors affecting grassland succession retardation in the Juifang area.

摘要

This study classifies the vegetation status to determine the factors affecting grassland succession retardation in the Juifang area. Data derived from Land Use Investigation of Taiwan, GIS techniques, multivariate analysis, and on-site investigation was applied in this research. Discriminant analysis shows that forests that have low human disturbance cannot be correctly identified and classified by the topography and soil depth. This indicates that the topography and soil depth in the Juifang area are not the limiting factors of forest growth. Grasslands are usually susceptible to periodic wildfires. This can be used as an environmental index for disturbed and/or polluted soils. Comparing the current vegetation status with the vegetation distribution derived from discriminant analysis, potential wildfire frequency can be estimated. Acid sulfate soils and copper-contaminated soils are the major polluted soils in the Juifang area. Because the Juifang area is an important coal field in northern Taiwan, acid sulfate can be easily found in the spoiled soils of several mining spots due to sulfur oxidation from the soil and/or rock layers dug out during mining operations. Copper-contaminated soils were detected at the sites near the Li-Lo Copper Refining Plant and Taiwan Metal Mining Company. Polluted soils and periodic wildfires inhibiting the invasion of trees are the major factors retarding the succession of grasslands in the Juifang area.