Post-fire management effects on hillslope-stream sediment connectivity in a Mediterranean forest ecosystem. (15th August 2022)

• Record Type: Journal Article
• Authors: González-Romero, J.; López-Vicente, M.; Gómez-Sánchez, E.; Peña-Molina, E.; Galletero, P.; Plaza-Álvarez, P.; Fajardo-Cantos, A.; Moya, D.; De las Heras, J.; Lucas-Borja, M.E.
• Is Part Of: Journal of environmental management. Volume 316(2022)
• Publication Date: 2022-08-15
• Subjects: Forest fire -- Post-fire management -- Sediment connectivity -- Hillslope erosion -- Wildfires; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2022.115212
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: Forest fires intensify sediment transport and aggravate local and off-site consequences of soil erosion. This study evaluates the influence of post-fire measures on structural and functional sediment connectivity (SC) in five fire-affected Mediterranean catchments, which include 929 sub-catchments, by using the "aggregated index of connectivity" (AIC) at two temporal scenarios: I) immediately after the fire and before implementing post-fire practices ('Pre-man'), and II) two years after the fire ('Post-man'). The latter includes all the emergency stabilization practices, that are hillslope barriers, check-dams and afforestation. The stream system was set as the target of the computation (STR), to be representative of intense rainfall-runoff events with effective sediment delivery outside the catchments. Output normalization (AICN ) allows comparing the results of the five basins between them. The sedimentological analysis is based on specific sediment yield (SSY) –measured at the check-dams installed after the fire –, and this data is used for output evaluation. Stream density and slope variables were the most influential factors on AICN-STR results at the sub-catchment scale. Post-fire hillslope treatments (barriers when built in high densities and afforestation) significantly reduced AICN-STR in comparison with untreated areas in both structural and functional approaches. Despite the presence of hillslope treatments, the higher erosive rainfall conditions resulted in higher AICN-STR values in the Post-man scenario (functional approach). A positive and good correlation was found between the measured SSY and the AICN-STR changes due to the post-fire practices and vegetation recovery, showing the good correspondence of the computation results and the real sediment dynamics of the studied catchments. Overall, AICN demonstrated to be a useful and versatile tool for post-fire management, which needs further research to optimize its applicability. Graphical abstract: Image 1 Highlights: High-density hillslope barriers and afforestation boosted lower connectivity. Under intense rainfall conditions, an increase of lateral connectivity is observed. Check-dams produced a clear and local disconnectivity in the flow path. Changes in connectivity correlated well with measured SSY and stabilization measures density. AIC reflected satisfactorily the effects of the different emergency stabilization measures.