Testing a novel technique, geotubes with mycotechnosoil, to mitigate post-fire erosion and enhance ecosystem recovery

Recently burnt areas have frequently been documented to produce strong to extreme catchment-scale hydrological and erosion responses to major rainfall events, even if these responses have rarely been quantified. These responses have raised important concerns, both among forest owners and managers on the on-site implications of soil (fertility) loss and among water resources managers for the off-side impacts on downstream values-at-risk such as road and hydraulic infrastructures, flood zones, and surface water quality in reservoirs or at river intake points. State-of-the-art emergency stabilization management, as practiced in the USA and Galicia, aims at reducing the hydrological and erosion response at its main source, i.e. the hillslopes. Based on years and decades of experience and pain-staking field monitoring in both the USA and Galicia, mulching is typically preferred over barrier-based methods, especially for being more effective in the case of high-intensity rainfall storms. Even so, the LIFE-REFOREST consortium (LIFE17 ENV/ES/000248) has developed an innovative barrier-based technique that is designed to be implemented easier and faster than log and shrub barriers and, at the same time, to improve vegetation recovery, using seeds of plant species that establish vegetation strips against runoff and erosion and/or seeds of tree and shrub species for re- or afforestation. The REFOREST barriers consists of geotubes containing, besides seeds, a mycotechnosoil as well as straw. The effectiveness of the LIFE-REFOREST geotubes is current being tested under field conditions in summer-2019 burnt areas in north-central Portugal and Galicia, in contrasting forest types (eucalypt vs. pine) on contrasting parent materials (schist vs. granite). Both field trials involve, besides 3 control plots and 3 plots with geotubes, also 3 plots mulched with either eucalypt logging residues or pine needles. The present poster will show preliminary results of the field trial in north-central Portugal, in a second-rotation eucalypt stand where tree crowns were scorched by the fire and soil burn severity was classified as moderate. These results concern the initial monitoring period till early spring 2020. However, this monitoring period has been quite rainy so far, arguably providing rather ideal conditions for testing the effectiveness of barrier-based solutions such as that of LIFE-REFOREST.