Factors affecting succession retardation of grassland at the temperate-humid climate zone in northeastern Taiwan.

• Main Authors: Jain-Rong Zeng, 曾建榮
• Other Authors: 林昭遠
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/25564980278993695318

碩士 === 國立中興大學 === 水土保持學系所 === 105 === Northeastern Taiwan belongs to temperate-humid climate zone where the land should be covered by forest. Surprisingly, grass communities still dominate a large area in northeastern Taiwan. Generally, the land cover in initial succession is grassland. The vegetation should succeed to forest biomes naturally without disturbance. However, northeastern Taiwan is still dominated by grass communities as a result of some disturbances. Therefore, factors affecting succession retardation of grassland is necessary to explore. Grasslands of succession retardation could be extracted from multi-temporal satellite images. In order to calculate the coverage ratio of grassland on a slope unit, the homogenous slope units can be transferred from sub-divisions delineated by certain threshold. Furthermore, the cluster analysis was applied to classify high, medium and low coverage ratio of grassland as dependent variable. The independent variable was topographical factors (elevation, slope and aspect) and the distance to coal mines and/or smelter. The optimal slope unit can be defined by discrimination analysis. Finally, the factors affecting succession retardation of grassland on a slope unit can be divided into three groups using the factors of topography and the distance to coal mines and/or smelter would be discussed. The results of multivariate analysis showed that grassland which locates at low elevation, gentle slope, southwest aspect and adjacent to the coal mines were affected by the discarded coal slag. Grassland which locates at high elevation, steep slope, south aspect and adjacent to the smelters were affected by the emission from smelters. Grassland which locates at medium elevation, medium slope and southeast aspect were affected by strong evapotranspiration due to the low precipitation on southeast aspect slope in summer. Therefore, the acidic ions are vulnerable to be transported from deep to surface soil layer owing to capillary action and affecting grassland succession.