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The influence of altered fire regimes on the denudation of a catchment is determined from alluvial deposits of the last 10,000 yrs and by monitoring runoff and erosion before and after a wildfire. An increase in fire frequency beginning at 3,000–4,000 yrs BP, as a result of intensified Aboriginal burning, did not change the mechanisms or rates of denudation nor did it cause widespread alluviation as suggested by others. The results of monitoring show that before and after mild fires there is insufficient runoff on most slopes to entrain sediment. Only after intense fires are runoff and erodibility increased enough to significantly accelerate erosion. Conditions are then identified which are most likely to lead to accelerated erosion from altered fire regimes in other catchments.  相似文献   

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托马斯·杰斐逊是美国开国元勋之一,在美国历史上的地位勿庸置疑,其民主自由思想之博大精深,在美国几乎无出其右,被誉为"美国民主自由的试金石和代名词"(第3页).  相似文献   

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