The extensive afforestation of the Mediterranean rim of Europe in recent decades has increased the number of wildfire disturbances on hydrological and sediment processes, but the impacts on headwater catchments is still poorly understood, especially when compared with the previous agricultural landscape. This work monitored an agroforestry catchment in the north‐western Iberian Peninsula, with plantation forests mixed with traditional agriculture using soil conservation practices, for one year before the fire and for three years afterwards, during which period the burnt area was ploughed and reforested. During this period, continuous data was collected for meteorology, streamflow and sediment concentration at the outlet, erosion features were mapped and measured after major rainfall events, and channel sediment dynamics were monitored downstream from the agricultural and the burnt forest area. Data from 202 rainfall events with over 10 mm was analysed in detail. Results show that the fire led to a notable impact on sediment processes during the first two post‐fire years, but not on streamflow processes; this despite the small size of the burnt area (10% of the catchment) and the occurrence of a severe drought in the first year after the fire. During this period, soil loss at the burnt forest slopes was much larger than that at most traditionally managed fields, and, ultimately, led to sediment exhaustion. At the catchment scale, storm characteristics were the dominant factor behind streamflow and sediment yield both before and after the fire. However, the data indicated a shift from detachment‐limited sediment yield before the fire, to transport‐limited sediment yield afterwards, with important increases in streamflow sediment concentration. This indicates that even small fires can temporarily change sediment processes in agroforestry catchments, with potential negative consequences for downstream water quality.

中文翻译：

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野火和战后土地管理对湿润地中海源头流域水文和泥沙过程的影响

近几十年来，欧洲地中海沿岸的广泛造林增加了对水文和泥沙过程的野火干扰，但是对水源流域的影响知之甚少，特别是与以前的农业景观相比。这项工作监测了伊比利亚西北部的一个农林业集水区，在火灾发生前的一年和之后的三年里，都采用人工土壤养护的方法将人工林与传统农业混合在一起，进行了三年的耕作。在此期间，收集了连续的气象数据，出口处的水流和沉积物浓度，并在发生重大降雨事件后绘制并测量了侵蚀特征，在农业和林地下游监测河道和沉积物的动力学。详细分析了202场降雨事件（超过10毫米）的数据。结果表明，大火对火灾后的头两年对沉积过程产生了显着影响，但对水流过程没有显着影响。尽管烧毁面积很小（流域的10％），大火后的第一年发生了严重的干旱，但仍存在这种情况。在此期间，烧过的森林坡度的土壤流失比大多数传统管理耕地的流失要大得多，最终导致沉积物枯竭。在集水规模上，无论是大火还是大火，暴风雨特性都是造成水流和泥沙产生的主要因素。但是，数据表明，大火之前已经脱离了受限制的沉积物产量，之后运输受限的泥沙产量，并大大增加了径流泥沙浓度。这表明即使是小火也可以暂时改变农林业集水区的沉积过程，对下游水质产生潜在的负面影响。