Surface runoff and soil loss after fire and post-fire treatments in forests of Castilla-La Mancha: a meta-analysis on a 10-year database

Aim of the study: A meta-analysis was applied to evaluate surface runoff and soil loss after fires of different severity and post-fire treatments in semi-arid forests of Central Eastern Spain. Area of study: Four sites (Lezuza, Agramón, Liétor and Ayna) were identified in Castilla-La Mancha and were monitored throughout 10 years at the plot and event scale. Material and methods: Rainfall simulations and observations after natural rainfalls were carried out to measure surface runoff and soil loss in unburned sites, burned and untreated sites, and burned sites treated with post-fire management techniques. The log response ratio of runoff and soil loss was calculated at the same site in order to evaluate the hydrological response to fire and post-fire management. Main results: The meta-analysis has shown: (i) prescribed fires do not noticeably increase runoff, while wildfires at every severity is able to trigger erosion, except in the case of low-severity fires and less intense rainfall; (ii) runoff generation capacity of burned soils is higher after moderate rainfalls; (iii) fire changed soil erodibility according to rainfall intensity between unburned and burned soils; (iv) in general, the evaluated treatments were not effective at reducing surface runoff (except for mulching using wood chips and manual logging); (v) in contrast, soil erosion under burned conditions decreased after almost all techniques, especially with mulching using Loranthus europaeus J. and wheat straw; (vi) the mulch made of the latter substrate (combined with manual logging or not) seems to be the most feasible post-fire anti-erosive action. Research highlights: Forest managers should prioritise areas potentially affected by high-severity wildfires for fire prevention. The most effective post-fire management technique is mulching, using wheat straw and wood chips to mitigate soil erosion and surface runoff, respectively.