本研究利用類地毯草、南美蟛蜞菊及百慕達草三種草類於坡長22.13m、平均坡度9%、寬度3m之試驗區,以下坡面10m草帶配置,探討植物性狀對土壤沖蝕及地表逕流的影響。試驗結果得以下結論: 裸露區總沖蝕量為333.865 kg,各草類產出之總沖蝕量分別為類地毯草9.74 kg、南美蟛蜞菊為5.28 kg、百慕達草12.83 kg,平均土砂攔截率均達到80%以上,而影響沖蝕之植物特徵包括植物地表覆蓋百分率、植物匍匐莖覆蓋百分率及植物之根長密度(RLD),其中地表覆蓋百分率、根長密度較高之南美蟛蜞菊所產出的沖蝕量較低。 試驗期間所監測到的總逕流量分別為類地毯草19.687 m3、南美蟛蜞菊9.811m3、百慕達草24.951m3;各草帶之平均逕流係數Cest變化介於0.06~0.19之間,顯示植物特徵上的差異對地表糙度帶來不同的影響,因此導致阻截逕流之能力亦不盡相同。
Field observations were conducted on 4 runoff plots at National Pingtung University of Science and Technology. Each plot measured 22.13m along the slope, 3m across the slope, with average gradient of 9%. In order to explore the influence by characteristics of plants on soil erosion and surface runoff, We set up a 10-m buffer at the downslope position at each runoff plot. Grass species include Carpet grass, W. trilobata and Bermuda grass. Following conclusions can be drawn from this study: The total amount of sediment that generated from one rainy season for each plot was 9.74 kg for Carpet grass, 5.28 kg for Trilobate Wedelia, and 12.83 kg for Bermuda grass, respectively. The average sediment trapping efficiency exceeds 80%. The main factors of grass strips controlling soil erosion were vegetation cover, percentage of plant stolons coverage, and root length density (RLD). The grasses with high root length density have the least sediment yield. During the observation period, the total runoff, for Carpet grass, Trilobate Wedelia , and Bermuda grass is 19.687 m3, 9.811m3 and 24.951m3 respectively. Average runoff coefficient of the grass strips varies from 0.06 to 0.19. The result shows that grass strip of 10-m in width is sufficient to increase runoff infiltration. Differences in plant characteristics have different impacts on surface roughness, thus lead to the ability of grasses in intercepting runoff. However, runoff formation process as well as the roots of grasses also plays an important role.