3.2. Variation in erosion sediment yield
In all four slopes and most vegetation covers, erosion sediment yield was greatest in the first 5 minutes (Fig. 5). Thereafter, sediment yield dropped to less than a third of the maximum value and remained relatively constant throughout the rest of the sampling period. The interaction of slope with vegetation cover was as expected: on steeper slopes more sediment eroded in plots with 0% vegetation cover. On all slopes, 30% vegetation cover effectively decreased sediment erosion to almost zero.
[Insert Figure 5]
Under different vegetation covers, the difference of erosion sediment yield at the 5° slope was smaller (Fig. 6). Meanwhile, under vegetation covers and slopes as well as their combined effects, the difference of erosion sediment yield at the 10° slope with 30% vegetation covers was smaller too (Fig. 6c). On the whole, the difference of erosion sediment yield was larger at the 10° and 15° slope with different vegetation covers and it was significantly larger than that at 5° slope. At the 20° slope with 0% and 30% vegetation covers, however, the difference was smaller and it was gradually smaller than that at 15° slope. The result indicated that the effect of vegetation covers, slope factor and their interaction on erosion sediment yield was considerable at the 10° and 15°slope.
[Insert Figure 6]