執行成果摘要
This project was to build soil and water loss plots of betel palms under different slopes at Lienhuachih Research Center of Taiwan Forestry Research Institute. The soil and water loss plots had be treated with different locations of buffer forest strips for measuring surface runoff and soil erosion in this third year. From field data of surface runoff and soil erosion, the best location of buffer forest strips would be identified for helping management of illegal planting fruits on hillslope of national forested lands. Based on the measured results of the third year, the average heights and breast diameters of betel palms were 6.2-7.7 m and 9.8-10.8 cm for 5 plots of 25% gentle slope, as well as 6.6-8.8 m and 10.2-11.9 cm for 5 plots of 45% steep slope, respectively. Comparing with growing condition of betel palms, the steep slope was better than gentle slope. The cover densities of herbaceous vegetation were 49.3%-70.8% for 5 plots at 25% gentle slope and 46.6%-73.3% for 5 plots at 45% steep slope, respectively. The cover density differences of herbaceous vegetation for 5 plots at 25% gentle slope were lower than those of herbaceous vegetation for 5 plots at 45% steep slope. The average heights and their standard deviations of Michelia formosana buffer forest strips were 2.06-2.42 m and 0.20-0.41 m for 4 plots of 25% gentle slope, as well as 1.89-2.23 m and 0.08-0.30 m for 4 plots of 45% steep slope, respectively. Planting buffer forest strips after one year and seven months, the average heights of Michelia formosana buffer forest strips for 4 plots of 25% gentle slope were higher than those of Michelia formosana buffer forest strips for 4 plots of 45% steep slope. The macro-porosities and total porosities of soil were 5.7%-7.9% and 33.0%-45.0% for 5 plots of 25% gentle slope, as well as 7.5%-8.7% and 44.9%-47.4% for 5 plots of 45% steep slope, respectively. Comparing with macro-porosities and total porosities of soil, the steep slope was a little more than gentle slope. The surface runoff depths and ratios under 2885.0 mm of annual rainfall amount were 282.0-794.9 mm and 8.4%-27.60% for 5 plots at 25% gentle slope, as well as 388.4-1424.3 mm and 13.5%-49.4% for 5 plots at 45% steep slope, respectively. The surface runoff depths and ratios were small for Michelia formosana planted among whole slope or Michelia formosana buffer forest strips of 3 rows planted along lower slope. The soil erosion amounts and depths under 2885.0 mm of annual rainfall amount were 15.7-179.8 kg and 0.06-0.67 mm for 5 plots at 25% gentle slope, as well as 43.1-223.8 kg and 0.16-0.83 mm for 5 plots at 45% steep slope, respectively. The soil erosion amounts and depths were small for Michelia formosana buffer forest strips of 3 rows planted along lower slope. However, the effects for Michelia formosana planted among whole slope and Michelia formosana buffer forest strips of 3 rows planted along lower slope on decreasing surface runoff and soil erosion depths for big storm rainfall were small than those for annual rainfall.