Effects of eucalypt crown burn severity, and post-fire salvage logging and post-logging mulching on soil erosion following the 15-October-2017 mega-wildfire in north-central Portugal

Abstract

Intensifying wildfire regimes have been raising societal concerns and scientific interests about their direct and indirect impacts, including the well-documented strong-to-extreme erosion-by-water responses in recently burnt areas. The role of fire severity and forest management operations in post-fire erosion, however, have received comparatively little research attention. This applies to post-fire operations such as salvage logging but especially also erosion mitigation measures following salvage logging. Therefore, the present study monitored post-fire sediment losses at a contour-plowed eucalypt plantation in north-central Portugal that had been affected by contrasting tree crown burn severities and was logged 14 months after the wildfire. Sediment losses were monitored using three 16-m²-plots per treatment. Sediment losses did not differ significantly or markedly between plots where crowns were completely consumed compared to plots where crowns were only scorched, in spite of contrasting litter loads and covers at the start of the experiment. Post-fire salvage logging, however, significantly and notably increased the average sediment losses. Over the entire 14-month post-logging period, they averaged 0.05 versus 0.47 Mg ha⁻¹ for the plots without as opposed to with skid tracks. This impact operated through reduced soil surface storage, increased vegetation disturbance and/or decreased topsoil bulk density. Mulching reduced the sediment losses from the plots with skid tracks in a consistent manner. The average sediment losses from the mulched plots were 77% lower than those from the untreated plots, while the sediment losses of the individual mulched plots were 30–91% lower than those of their paired untreated plots.

Keywords

Forest management practices / Soil mobilization / Fire severity / Erosion mitigation

References

[1] APHA (1998) American Public Health Association. Total suspended solids dried at 525 103–105 °C, method 2540D. In: Clesceri, L.S., Greenberg, A.E., Eaton, A.D., Franson, M.A.H. (Eds.), Standard methods for the examination of water and wastewater. American Public Health Association, American Water Works Association and Water Environment Federation Publishers, Inc.,Washington D.C., 529 USA, ISBN: 0-87553-235-7

[2] Balocchi F, Flores N, Neary D, White DA, Silberstein R, Ramírez de Arellano PThe effect of the ‘Las Maquinas’ wildfire of 2017 on the hydrologic balance of a high conservation value Hualo (Nothofagus glauca (Phil.) Krasser) forest in central Chile. For Ecol Manag, 2020, 477: 118482.

[3] Basso M, Vieira DCS, Ramos TB, Mateus MAssessing the adequacy of SWAT model to simulate postfire effects on the watershed hydrological regime and water quality. Land Degrad Dev, 2020, 31(5): 619-631.

[4] Coelho CA, Shakesby RA, Walsh RPD (1995) Effects of forest fires and post-fire land management practice on soil erosion and stream dynamics, Agueda Basin, Portugal. Directorate general for science, research and development, European Commission, Environment and Research Programme. Soil and Groundwater Research Report V, EUR 15689 EN

[5] Crandall T, Jones E, Greenhalgh M, Frei RJ, Griffin N, Severe E, Maxwell J, Patch L, St Clair SI, Bratsman S, Merritt M, Norris AJ, Carling GT, Hansen N, St Clair SB, Abbott BWMegafire affects stream sediment flux and dissolved organic matter reactivity, but land use dominates nutrient dynamics in semiarid watersheds. PLoS ONE, 2021, 16(9e0257733

[6] da Costa JBCaracterização e constituição do solo, 1985Fundacao Colouste Gulbenkian

[7] Fernández C, Vega JA, Fonturbel T, Pérez-Gorostiaga P, Jiménez E, Madrigal JEffects of wildfire, salvage logging and slash treatments on soil degradation. Land Degrad Dev, 2007, 186): 591-607.

[8] Fernández C, Vega JA, Fontúrbel TComparison of the effectiveness of needle cast and straw helimulching for reducing soil erosion after wildfire in NW Spain. J Soils Sediments, 2020, 20(1): 535-541.

[9] Gee G, Bauder J (1986) Particle size analysis. In:Methods of Soil Analysis, Part A Am Soc Agron, Madison, WI 9(2) 383–411

[10] Girona-García A, Vieira DCS, Silva J, Fernández C, Robichaud PR, Keizer JJEffectiveness of post-fire soil erosion mitigation treatments: a systematic review and meta-analysis. Earth Sci Rev, 2021, 217103611

[11] Gómez-González S, Ojeda F, Fernandes PMPortugal and Chile: longing for sustainable forestry while rising from the ashes. Environ Sci Policy, 2018, 81104-107.

[12] González Barrios P, Pérez Bidegain M, Gutiérrez LEffects of tillage intensities on spatial soil variability and site-specific management in early growth of Eucalyptus grandis. For Ecol Manag, 2015, 346: 41-50.

[13] González-Pelayo O, Prats SA, Amd V, Dcs V, Maia P, Keizer JJImpacts of barley (Hordeum vulgare L.) straw mulch on post-fire soil erosion and ground vegetation recovery in a strawberry tree (Arbutus unedo L.) stand. Ecol Eng, 2023, 195107074

[14] Hawtree D, Nunes JP, Keizer JJ, Jacinto R, Santos J, Rial-Rivas ME, Boulet AK, Tavares-Wahren F, Feger KHTime series analysis of the long-term hydrologic impacts of afforestation in the Águeda watershed of north-central Portugal. Hydrol Earth Syst Sci, 2015, 19(7): 3033-3045.

[15] Hersbach, H.. et al. (2025) ERA5 hourly time-series data on single levels from 1940 to present, January 2026, Climate Change Service (C3S) Climate Data Store (CDS). https://doi.org/10.24381/1cf1ad76.

[16] ICNF (2019) Instituto da Conservaçao da Natureza e das Florestas. 6° inventário florestal nacional, principais resultados 35 https://www2.icnf.pt/portal/florestas/ifn/resource/doc/ifn/ ifn6-res-prelimv1–1

[17] IPCC (2022) In: Pörtner, H.-O., Roberts, D.C., Tignor, M., Poloczanska, E.S., Mintenbeck, K., Alegría, A., Craig, M., Langsdorf, S., Löschke, S., Möller, V., Okem, A., Rama, B. (Eds.), Climate Change 2022: Impacts, adaptation and Vulnerability. Working Group II Contribution to the IPCC Sixth Assessment Report. Intergovernmental panel on climate change. Cambridge University Press, Cambridge, UK and New York, NY, USA. https://doi.org/10.1017/9781009325844

[18] ISO (2005) International Standard Organization. ISO 10390: Soil Quality — Determination of pH. Geneve, Switzerland.

[19] ISO (2017) International Standard Organization. ISO 11272: Soil quality - Determination of dry bulk density. Geneve, Switzerland

[20] IUSS (2022) International Union of Soil Sciences, Working Group WRB. World Reference Base for Soil Resources. International soil classification system for naming soils and creating legends for soil maps. 4th edition. IUSS, Vienna, Austria.

[21] Jester W, Klik ASoil surface roughness measurement—methods, applicability, and surface representation. CATENA, 2005, 64(2–3): 174-192.

[22] Johnston SG, Maher DTDrought, megafires and flood—climate extreme impacts on catchment-scale river water quality on Australia’s east coast. Water Res, 2022, 218118510

[23] Keizer JJ, Silva FC, Vieira DCS, González-Pelayo O, Campos I, Vieira AMD, Valente S, Prats SAThe effectiveness of two contrasting mulch application rates to reduce post-fire erosion in a Portuguese eucalypt plantation. CATENA, 2018, 169: 21-30.

[24] Kent M, Coker P (1995) Vegetation description and analysis: a practical approach. Wiley; 1st edition. ISBN-13: 978-0471948100

[25] Kottek M, Grieser J, Beck C, Rudolf B, Rubel FWorld map of the Köppen-Geiger climate classification updated. Metz, 2006, 15(3): 259-263.

[26] Londo G (1984) The decimal scale for relevés of permanent quadrats. In R. Knapp (Ed.), Sampling methods and taxon analysis in vegetation science: relieve surveys, ‘Vegetationsaufnahmen’, floristic analysis of plant communities 45–49 https://edepot.wur.nl/459509

[27] Lopes AR, Prats SA, Silva FC, Keizer JJEffects of ploughing and mulching on soil and organic matter losses after a wildfire in Central Portugal. Cuad Investig Geogr, 2020, 46(1): 303-318.

[28] Malvar MC, Prats SA, Keizer JJRunoff and inter-rill erosion affected by wildfire and pre-fire ploughing in eucalypt plantations of north-central Portugal. Land Degrad Dev, 2016, 27(5): 1366-1378.

[29] Malvar MC, Silva FC, Prats SA, Vieira DCS, Coelho COA, Keizer JJShort-term effects of post-fire salvage logging on runoff and soil erosion. For Ecol Manag, 2017, 400: 555-567.

[30] Martins MAS, Machado AI, Serpa D, Prats SA, Faria SR, Varela MET, González-Pelayo Ó, Keizer JJRunoff and inter-rill erosion in a Maritime Pine and a Eucalypt plantation following wildfire and terracing in north-central Portugal. J Hydrol Hydromech, 2013, 61(4): 261-268.

[31] Moody JA, Shakesby RA, Robichaud PR, Cannon SH, Martin DACurrent research issues related to post-wildfire runoff and erosion processes. Earth Sci Rev, 2013, 122: 10-37.

[32] Pancel LBasic outline of tree plantations in the tropics. Tropical forestry handbook, 2016Springer14411529.

[33] Pausas JG, Llovet J, Rodrigo A, Vallejo RAre wildfires a disaster in the Mediterranean basin? –A review. Int J Wildland Fire, 2008, 17(6): 713-723.

[34] Pereira JMC, Oom D, Silva PC, Benali AWild, tamed, and domesticated: three fire macroregimes for global pyrogeography in the Anthropocene. Ecol Appl, 2022, 32(6e2588

[35] Prats SA, MacDonald LH, Monteiro M, Ferreira AJD, Coelho COA, Keizer JJEffectiveness of forest residue mulching in reducing post-fire runoff and erosion in a pine and a eucalypt plantation in north-central Portugal. Geoderma, 2012, 191: 115-124.

[36] Prats SA, dos Santos Martins MA, Malvar MC, Ben-Hur M, Keizer JJPolyacrylamide application versus forest residue mulching for reducing post-fire runoff and soil erosion. Sci Total Environ, 2014, 468: 464-474.

[37] Prats SA, Wagenbrenner JW, Santos Martins MA, Malvar MC, Keizer JJMid-term and scaling effects of forest residue mulching on post-fire runoff and soil erosion. Sci Total Environ, 2016, 573: 1242-1254.

[38] Prats SA, González-Pelayo Ó, Silva FC, Bokhorst KJ, Baartman JEM, Keizer JJPost-fire soil erosion mitigation at the scale of swales using forest logging residues at a reduced application rate. Earth Surf Process Landf, 2019, 4414): 2837-2848.

[39] Pribyl DWA critical review of the conventional SOC to SOM conversion factor. Geoderma, 2010, 156(3–4): 75-83.

[40] Robichaud PR, Beyers JL, Neary DG (2000) Evaluating the effectiveness of postfire rehabilitation treatments. Gen. Tech. Rep. RMRS-GTR-63. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fort Collins, CO. 85

[41] Saleh ASoil roughness measurement: chain method. J Soil Water Conserv, 1993, 48(6): 527-529.

[42] San-Miguel-Ayanz J, Durrant T, Boca R, Libertà G, Branco A, de Rigo D, Ferrari D, Maianti P, Artés Vivancos T, Costa H, Lana F, Löffler P, Nuijten D, Ahlgren AC, Leray T (2018) Forest Fires in Europe, Middle East and North Africa 2017. EUR 29318 EN, ISBN 978-92-79-92832-1. https://doi.org/10.2760/27815

[43] Shakesby RAPost-wildfire soil erosion in the Mediterranean: review and future research directions. Earth Sci Rev, 2011, 105(3–4): 71-100.

[44] Shakesby RA, Doerr SHWildfire as a hydrological and geomorphological agent. Earth Sci Rev, 2006, 74(3–4): 269-307.

[45] SNIRH (2026) Serviço Nacional de Informação sobre Recursos Hídricos. www.snirh.pt (last visited during January 2026).

[46] Turco M, Jerez S, Augusto S, Tarín-Carrasco P, Ratola N, Jiménez-Guerrero P, Trigo RMClimate drivers of the 2017 devastating fires in Portugal. Sci Rep, 2019, 913886

[47] Verheijen FGA, Jones RJA, Rickson RJ, Smith CJ, Bastos AC, Nunes JP, Keizer JJConcise overview of European soil erosion research and evaluation. Acta Agric Scand Sect B Soil Plant Sci, 2012, 62(sup2): 185-190.

[48] Vieira DCS, Fernández C, Vega JA, Keizer JJDoes soil burn severity affect the post-fire runoff and interrill erosion response? A review based on meta-analysis of field rainfall simulation data. J Hydrol, 2015, 523: 452-464.

[49] Vieira DCS, Malvar MC, Fernández C, Serpa D, Keizer JJAnnual runoff and erosion in a recently burn Mediterranean forest–the effects of plowing and time-since-fire. Geomorphology, 2016, 270: 172-183.

[50] Vieira DCS, Borrelli P, Jahanianfard D, Benali A, Scarpa S, Panagos PWildfires in Europe: burned soils require attention. Environ Res, 2023, 217114936

[51] Wagenbrenner JW, MacDonald LH, Coats RN, Robichaud PR, Brown REEffects of post-fire salvage logging and a skid trail treatment on ground cover, soils, and sediment production in the interior western United States. For Ecol Manag, 2015, 335: 176-193.

[52] Wagenbrenner JW, Robichaud PR, Brown RERill erosion in burned and salvage logged western montane forests: effects of logging equipment type, traffic level, and slash treatment. J Hydrol, 2016, 541: 889-901.

Rights & permissions

Northeast Forestry University