Team Soil, Water and Land Use, Wageningen Environmental Research, Droevendaalsesteeg 3, Wageningen, 6708RC, Netherlands.
Team Earth Informatics, Wageningen Environmental Research, Droevendaalsesteeg 3, Wageningen, 6708RC, Netherlands.
J Environ Manage. 2021 Jan 15;278(Pt 1):111510. doi: 10.1016/j.jenvman.2020.111510. Epub 2020 Oct 26.
Forest fires and post-fire management practices (PFMP) cause changes in the hydrological response of a hillslope. This study evaluates the effect of log erosion barriers (LB) and Easy-Barriers® (EB) on the spatial patterns and values of structural sediment connectivity (SC) in a Mediterranean mountainous pine forest affected by an arson fire in August 2017. A drone flight was done in July 2019 (23 months after the fire and 11 months after the PFMP) to obtain a high-resolution orthomosaic and DEM (at 0.05 m). Two contrasted areas, with and without PFMP, were selected along the same hillslope and 26 small basins were identified: 16 in the treated area (mean area, slope and vegetation recovery of 916 m, 60% and 25%; with 94 LB and 39 EB) and 10 in the untreated area (1952 m, 75% and 20%). The aggregated index of sediment connectivity (AIC) was chosen to compute SC in three temporal scenarios: Before and just after the fire and when all PFMP were implemented including the incipient vegetation recovery. Output normalization allowed the comparison of the non-nested basins among them. After accounting the intrinsic differences among the basins and areas, and the temporal changes of SC between the three scenarios, the contribution of the barriers was estimated in 27% from the total decrease of SC in the treated area (-8.5%). The remaining 73% was explained by the vegetation recovery. The effectiveness of the LB (11.3% on average) and EB (13.4%) did not diminish with increasing slope gradients. These percentages become relevant considering the small area affected by the LB (2.8%) and EB (1.3%). Independent metrics (convergence index, flow width, flat areas and LS factor) also reported clear differences between the two areas -higher soil erosive intensity in the untreated area- and in accordance with the AIC results.
森林火灾和火灾后管理措施 (PFMP) 会改变坡面的水文响应。本研究评估了原木侵蚀障 (LB) 和 Easy-Barriers® (EB) 对 2017 年 8 月纵火火灾后受影响的地中海山地松林的结构泥沙连通性 (SC) 的空间格局和值的影响。2019 年 7 月进行了一次无人机飞行，以获取高分辨率正射镶嵌图和 DEM（火灾后 23 个月，PFMP 后 11 个月）。在同一山坡上选择了两个具有和不具有 PFMP 的对比区域，并确定了 26 个小流域：16 个在处理区域（平均面积、坡度和植被恢复分别为 916m、60%和 25%；有 94 个 LB 和 39 个 EB）和 10 个在未处理区域（1952m、75%和 20%）。选择泥沙连通性综合指数（AIC）来计算三个时间情景中的 SC：火灾前后以及所有 PFMP 实施后，包括初始植被恢复。输出归一化允许对它们之间的非嵌套流域进行比较。在考虑了流域和区域之间的内在差异以及三个情景之间的 SC 时间变化之后，估计了在处理区域中 SC 总减少的 27%（-8.5%）归因于障碍物。剩余的 73%由植被恢复解释。LB（平均 11.3%）和 EB（13.4%）的有效性并没有随着坡度梯度的增加而降低。考虑到 LB（2.8%）和 EB（1.3%）的影响面积较小，这些百分比具有相关性。独立的指标（收敛指数、水流宽度、平坦区域和 LS 因子）也报告了两个区域之间的明显差异——未处理区域的土壤侵蚀强度更高——并与 AIC 结果一致。
