Forest fires and post-fire practices influence sediment connectivity (SC). In this study, we use the ‘aggregated index of connectivity’ (AIC) to assess SC in five Mediterranean catchments (198–1090 ha) affected by a wildfire in 2012 in south-eastern Spain. Two temporal scenarios were considered, immediately after the fire and before post-fire management, and 2 years after the fire including all practices (hillslope barriers, check-dams, afforestation, salvage logging and skid trails). One LiDAR (light detection and ranging)-derived digital elevation model (DEM, 2 m × 2 m resolution) was generated, per scenario. The five catchment outlets were established as the computation target (AIC_OUT), and structural and functional SC were calculated. Index outputs were normalized to make the results of the non-nested catchments comparable (AIC_N-OUT). The output analysis includes the SC distribution along the catchments and at local scale (929 sub-catchments, 677 in the burned area), the hillslope and channel measures' effect on SC, and a sedimentological analysis using observed area-specific sediment yield (SSY) at 10 new (built after post-fire practices) concrete check-dams located in the catchments (SSY = 1.94 Mg ha⁻¹ yr⁻¹; σ = 1.22). The catchments with more circular shapes and steeper slopes were those with higher AIC_N-OUT. The structural SC maps – removing the rainfall erosivity influence – allowed evaluating the actual role played by the post-fire practices that reduced SC ( $\overline{x}$= − 1.19%; σ = 0.41); while functional SC was linked to the actual change of SC ( $\overline{x}$= + 5.32%; σ = 0.62). Hillslope treatments resulted in significant changes on AIC_N-OUT at sub-catchment scale with certain disconnectivity. A good and positive correlation was found between the SSY and the changes of AIC_N-OUT. However, the coarse DEM resolution explained the lack of effect of the rock check-dams – located on the secondary channels – on AIC_N-OUT. AIC_N-OUT proved to be a useful tool for decision making in post-fire restoration, but an optimal input data is still necessary to refine calculations.

中文翻译：

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火灾后管理对地中海森林生态系统中沉积物（断开）连通性的影响：渠道和集水区响应

森林火灾和火灾后的做法会影响沉积物连通性 (SC)。在这项研究中，我们使用“连通性综合指数”(AIC) 来评估 2012 年西班牙东南部受野火影响的五个地中海集水区（198-1090 公顷）的 SC。考虑了两种时间情景，即火灾后立即和火灾后管理之前，以及火灾后 2 年，包括所有做法（山坡屏障、拦河坝、植树造林、抢救伐木和滑道）。每个场景生成一个 LiDAR（光探测和测距）衍生的数字高程模型（DEM，2 m × 2 m 分辨率）。5个流域网点被确定为计算目标（AIC _OUT)，并计算结构和功能 SC。指数输出被标准化以使非嵌套流域的结果具有可比性 (AIC _N-OUT )。输出分析包括沿流域和局部尺度的 SC 分布（929 个子流域，677 个在燃烧区）、山坡和河道措施对 SC 的影响，以及使用观察到的特定区域沉积物产量 (SSY) 的沉积学分析) 位于集水区 (SSY = 1.94 Mg ha ^-1 yr ^-1 ; σ  = 1.22) 的10 个新的（在火灾后实践后建造的）混凝土止回坝。圆形较多、坡度较陡的集水区是 AIC _N-OUT较高的集水区. 结构 SC 地图——消除了降雨侵蚀性的影响——允许评估火灾后减少 SC 的做法所发挥的实际作用（ $\overline{X}$= - 1.19%; σ  = 0.41)；而功能性 SC 与 SC 的实际变化相关联（ $\overline{X}$= + 5.32%; σ  = 0.62）。Hillslope 处理导致在子流域尺度上 AIC _N-OUT发生显着变化，具有一定的断开性。SSY与AIC _N-OUT的变化之间存在良好的正相关关系。然而，粗略的 DEM 分辨率解释了位于次要渠道上的岩石止回坝对 AIC _{N-OUT 没有影响的原因}。事实证明，AIC _N-OUT是用于火灾后恢复决策的有用工具，但仍需要优化输入数据以改进计算。