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Wildfires are a threat to water security worldwide, due to the negative effect of the post-fire mobilization of sediments and associated nutrients and contaminants on the waterbodies located downstream of burned areas. Such impacts have been assessed in field studies and, more recently, also through modelling approaches. Models are valuable tools for anticipating the potential negative impacts of wildfires, allowing to test different environmental scenarios. The state of the art in post-fire model adaptation has shown that most studies simulate the hydrological and erosion response in the first post-fire year in situ, without considering the cascading effects on downstream waterbodies. In addition, few studies have evaluated the long-term impacts of wildfires, likely due to the limited available data. Among the existing gaps in post-fire modelling, ash transport has recently been identified as a priority. The lack of ash modelling studies has been ascribed to the limited understanding of ash behavior and the difficulties of incorporating ash-related processes into the structure of existing models.As a way to fulfill these research gaps and advance the state of the art in post-fire hydrological modeling, the authors provided several contributions in recent years.For instance, a watershed model has been coupled with a reservoir model to simulate the effects of fires on drinking water supplies, using the outputs of the main streams as inputs to the reservoir branches. As most simulations commonly end at the watershed outlet, a simple methodology was proposed to assess how the impacts on watercourses propagate to the drinking water supply inlet. The results showed that integrated modeling frameworks are critical for anticipating the off-site impacts of fires.Post-fire management can also influence the impacts of fires beyond the first post-fire rainfall events, when the soil is exposed and ash and sediment transport is greatest. Another modelling exercise evaluates the long-term impacts of different post-fire management options, more specifically terracing, mulching and natural recovery, on water availability and quality.As post-fire ash and sediment mobilization is typically limited to the duration of the rainfall events, which typically lasts for a few hours, hydrological models that run at a daily time-step can underestimate the environmental impacts of fires. To improve the knowledge of post-fire hydrological processes at event-based scale, two hydrological models (LISEM and MOHID) were calibrated, accounting for burn severity and initial soil moisture conditions before each specific rainfall event.The work done in the past years is expected to be of added value for the post-fire modeling community, providing future directions on post-fire hydrological modelling studies.

The objective of this paper is to develop a framework to overcome problems of soil nutrient legacies and poor quality of water bodies raised by agricultural practices. A multicriteria decision analysis (MCDA) approach is proposed to evaluate different alternatives to help to define sustainable vineyard agricultural solutions. The methodology developed was applied to a basin in the north-central part of Portugal, the São Lourenço basin. The land cover of the basin consists predominantly of vines. A number of alternatives based on different vineyard management practices and land use are evaluated against environmental and socioeconomic criteria by means of the soil and water assessment tool (SWAT) model and considering information included in some databases. The preference ranking organization method for enrichment evaluation (PROMETHEE) outranking method is used to rank the alternatives and to evaluate weight stability intervals assigned to criteria. A supplementary analysis is performed by a different MCDA method (technique for order of preference by similarity to ideal solution (TOPSIS)), belonging to the family of compensatory methods, to provide additional insights to the decision makers. The results show the best and the worst alternatives for vineyard agricultural practices according to the weights assigned to the criteria. The sensitivity analysis of the weights indicated most stable ranking cases and the criterion that presents the narrow stability intervals. This work offers the opportunity to discuss comparisons between different types of agricultural practices and give insights for future developments of other areas where intensive vineyard cultivation is implemented.

Wildfires constitute a source of contamination to both freshwater and marine ecosystems. This study aimed to compare the antioxidant defense response of the freshwater clam Corbicula fluminea and the marine cockle (Cerastoderma edule) to wildfire ash exposure and the concomitant metal body burden. Organisms were exposed to different concentrations (0%, 12.5%, 25%, 50%, and 100%) of aqueous extracts of Eucalypt ash (AEAs) from a moderate-to-high severity wildfire. The activity of various enzymes, as well as lipid peroxidation, protein content, and metal body burden, were determined after 96 h of exposure. A significant increase in the protein content of soft tissues was observed for C. edule at AEA concentrations ≥ 25%, unlike for C. fluminea. Similarly, significant effects on lipid peroxidation were observed for cockles, but not for clams. For both species, a significant effect in the total glutathione peroxidase activity was observed at AEA concentrations ≥ 25%. Relative to the control, AEAs-exposed clams showed higher Cd content, whereas AEAs-exposed cockles showed higher Cu content, thus exhibiting different responses to the exposure to wildfire ash. The susceptibility of bivalves to ashes, at environmentally relevant concentrations, raises concern about the effects of post-fire runoff to bivalve species.

Forest fires can threaten amphibians because ash-associated contaminants transported by post-fire runoff impact both terrestrial and aquatic ecosystems. Still, the effects of these contaminants on the skin microbiome of amphibians have been overlooked. Thus, the main objective of this study was to assess the effects of ash from different severity wildfires (moderate and high) on the skin microbiome of the Iberian frog (Rana iberica). Bacterial isolates sampled from R. iberica skin microbiome were tested for their antimicrobial activity against the pathogen Aeromonas salmonicida. The isolates with antimicrobial activity were identified and further exposed to several concentrations (0, 6.25, 12.5, 25, 50, 75, and 100%) of Eucalypt (Eucalyptus globulus) aqueous extracts (AAEs) of ash from both a moderate and a high severity wildfire. The results showed that 53% of the bacterial isolates presented antimicrobial activity, with Pseudomonas being the most common genus. Exposure to AAEs had diverse effects on bacterial growth since a decrease, an increase or no effects on growth were observed. For both ash types, increasing AAEs concentrations led to an increase in the number of bacteria whose growth was negatively affected. Ash from the high severity fire showed more adverse effects on bacterial growth than those from moderate severity, likely due to the higher metal concentrations of the former. This study revealed that bacteria living in Iberian frogs' skin could be impaired by ash-related contaminants, potentially weakening the individual's immune system. Given the foreseen increase in wildfires' frequency and severity under climate change, this work raises awareness of the risks faced by amphibian communities in fire-prone regions, emphasising the importance of a rapid implementation of post-fire emergency measures for the preservation and conservation of this group of animals.

Ash and sediments transported by post-fire runoff are a source of hazardous substances, like metals, posing a risk of contamination to the downstream aquatic ecosystems. In the present study, metal mobilization was evaluated using 16 m2 bounded runoff-erosion plots at a eucalypt plantation in Albergaria-a-Velha (Aveiro district, North-Central Portugal) that burnt with moderate severity in September 2019. In total, 9 plots were installed: 3 were treated with eucalypt chopped-bark mulch, another 3 were treated with an innovative barrier-based technique developed within the scope of the LIFE REFOREST project (LIFE17 ENV/ES/000248) consisting of geotubes containing a mycotechnosol and, 3 others were left untreated. Eroded sediments and overland flow were collected during the first post-fire hydrological year. Sediment and overland flow samples were analysed for vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd) and lead (Pb), which are of concern for both environmental and human health. Given the most recent climate change scenarios, which foresee an increase in fire severity and frequency for the Mediterranean region, this work provides key information for resource managers to define adaptative strategies to effectively safeguard surface water resources.

The magnitude of forest fires' impacts on the environment is directly related to the changes induced on soil physical, chemical and biological properties. Using available organic resources to rehabilitate burnt forest soils can help reduce post-fire soil fertility loss, accelerating ecosystem recovery. In the present study, the potential of four soil amendments: a mycotechnosol, a eucalypt residue mulch, dredged sediments from a freshwater lagoon and an organic-mineral biofertilizer, to improve the quality of burnt forest soils in terms of organic matter, carbon, nitrogen and phosphorus contents, was evaluated. Two experiments were set-up, one in a recently burnt eucalypt plantation and another in the laboratory using soils from the same area, to assess the effects of the amendments on soil quality, with both experiments lasting for 7 months. The effects of the amendments on nutrient leaching along the soil profile were also evaluated in the laboratory, to investigate possible negative impacts on groundwater and surface water quality. All amendments increased the organic matter and nutrient contents of burnt soils, confirming their potential for ecosystem rehabilitation. The biofertilizer, however, was found to promote nutrient losses by leaching, largely owing to its high solubility, increasing the risk of contamination of ground and surface waters. Using available organic resources to rehabilitate burnt forests as was done in the present work complies with the idea of a circular economy, being key for the sustainability of forest ecosystems.

Environmental contamination influences the diversity of the resident skin microbial community of amphibians, ultimately affecting the individual's immune system. Wildfires are expected to impact the skin microbiome, since post-fire runoff typically transports hazardous substances, that can affect terrestrial and aquatic ecosystems. The present study is the first to assess the effects of Eucalypt and Pine wildfire ash on cultivable bacterial isolates from the skin microbiome of amphibians, in particular the fire salamander (Salamandra salamandra), a common species in fire-prone Mediterranean ecosystems. To achieve this goal, samples of skin bacteria of adult individuals of S. salamandra were collected at a site without influence of wildfires. The bacterial isolates were tested against the pathogenic agent Aeromonas salmonicida for assessing their antimicrobial activity, before exposing them to a series of dilutions of aqueous extracts of Eucalypt and Pine ashes (AAEs) from high severity wildfires. From the 80 bacterial isolates collected, 48 (mostly Pseudomonas spp.) showed antimicrobial activity. Exposure of bacteria with antimicrobial activity to the Eucalypt and Pine AAEs at concentrations of 0, 6.25, 12.5, 25, 50, 75, and 100%, revealed that bacterial growth could be significantly inhibited, stimulated or unaffected by ash. Growth inhibition was found for Pine and Eucalypt AAEs at concentrations as low as 6.25% and 12.5%, respectively, but were more expressive at concentrations equal or above 50%. Eucalypt AAEs had a higher negative impact on bacterial growth than Pine AAEs, likely due to differences in metal concentrations between ash types. These findings raise concern about the future of amphibians in fire-prone regions since the foreseen increase in fire frequency and severity owing to climate changes are likely to alter the skin microbiome of amphibians, weaken the immune system and consequently increasing the incidence of infections or diseases, further contributing to the decline of the populations.

Metal pollution in aquatic ecosystems translates into increased concentrations of sediment-bound metals, representing a risk for benthic species. This risk might be enhanced in soft and moderately hard waters, world widely distributed, due to the protective role of hardness against metal toxicity. As lead (Pb) and nickel (Ni) are amongst the more abundant metals in aquatic systems, and since their combined effects to benthic species have been overlooked, in this study we aimed to investigate the life-cycle toxicity of Pb and Ni (using spiked sediment) to the benthic species Chironomus riparius, considering both single and mixture exposures, in moderately hard water. Environmentally relevant concentrations of each metal were used (25 and 75 mg kg

In aquatic invertebrate (e.g., daphnids and Artemia sp.) and zebrafish cultures, in ecotoxicological bioassays, or when addressing complex population-level experimental designs, the counting of an organism's progeny is often required. This counting process is laborious, repetitive, and time-consuming, potentially posing health hazards to the operators, and necessarily entailing a higher likelihood of human error. We present an experimental evaluation of a computer-based device for counting neonates (Daphnia magna, Daphnia longispina, and Ceriodaphnia sp.), nauplii (Artemia salina and Artemia franciscana), and zebrafish (Danio rerio) eggs. Manual counts by an experienced technician were compared with the corresponding automated counts achieved by the computer-based counting device. A minimum of 55 counts/species was performed, with the number of counted organisms being up to a maximum of 150 neonates of Ceriodaphnia dubia, 200 neonates of D. magna and D. longispina, 200 nauplii of A. franciscana and A. salina, and 500 zebrafish eggs. Manual and automated counts were both performed in culture medium solutions of 50 ml of volume. Automated counts showed a mean relative acccuracy of 98.9% (97.9%-99.4%) and a relative standard deviation of 1.72%. The results demonstrate that the computer-based device can be used for accurately counting these aquatic organisms. This computer-based counting might be extended to other organisms of similar size, thus facilitating reproduction and life-cycle ecotoxicity tests. Environ Toxicol Chem 2022;41:1451-1458. © 2022 SETAC.

Wildfires are a recurring hazard in forested catchments representing a major threat to water security worldwide. Wildfires impacts on water quality have been thoroughly addressed by the scientific community through field studies, laboratory experiments, and, to a lesser extent, the use of hydrological models. Nonetheless, models are important tools to assess on-site and off-site wildfires impacts and provide the basis for post-fire land management decisions. This study aims to describe the current state of the art of post-fire model adaptation, understanding how wildfires impacts are simulated and the options taken by the modelers in selecting parameters. For this purpose, 42 publications on modeling wildfire impacts on the hydrologic cycle and water quality were retrieved from the SCOPUS database. Most studies simulated post-fire hydrological and erosion response in the first year after the fire, while few assessed nutrients changes and long-term impacts. In addition, most simulations ended at the watershed outlet without considering the fate of pollutants in downstream waterbodies. Ash transport was identified as a major research gap, given the difficulties of its incorporation in the current models’ structure and the high complexity in predicting the heterogeneous ash layer. Including such layer would improve models’ ability to simulate water quality in post-fire conditions, being ash a source of nutrients and contaminants. Model complexity and data limitations influenced the spatial and temporal scale chosen for simulations. Post-fire model adaptations to simulate on-site soil erosion are well established, mainly using empirical equations extensively calibrated in the literature. At the watershed level, however, physical and process-based models are preferred for their ability to simulate more complex burned area characteristics. Future research should focus on the simulation of the ash transport and the development of integrated modelling frameworks, combining watershed and aquatic ecosystem models to link the on and off-site impacts of fires.

Wildfires are well-known to negative affect forest both directly and indirectly, due to fire-enhanced runoff generation and the associated losses of wildfire ash, soil, organic matter and nutrients. In turn, post-fire runoff and erosion can, promote eutrophication and contamination of downstream surface water bodies. A variety of erosion mitigation measures have been tested in recently burnt areas, with especially mulching with straw having been applied in operational post-fire land management in the USA and Galicia. The present work, evaluates the effectiveness of a new erosion mitigation strategy, using geotubes filled with mycotechnosols and straw, and compares it to that of mulching. This was done for the two prevalent forest types in central Portugal and Galicia, i.e. an eucalypt plantation in Central Portugal and a pine plantation in Galicia that both burnt during the summer of 2019. Both study sites were instrumented with 9 bounded erosion plots of 16m2 with sediment traps at the bottom of the plots, divided over three blocks. The three treatments of doing nothing, mulching and geotubes were applied to one plot per block. In total, 4 geotubes were placed in each plot to create a barrier in the middle of the plot and at the bottom, just before the sediment deposition zone at the plot outlet. Mulching was done with chopped eucalypt bark at the eucalypt site and with pine needles at the pine site, at application rates of roughly 250 g m-2. Eroded sediments were collected on a bi-weekly to monthly basis, depending on occurrence of rain, during the first post-fire hydrological year. The results showed that the erosion rates of the control plots differed about one order of magnitude between the two sites, amounting to an average of 11 Mg ha-1 y-1 at the pine site as opposed to 1.0 Mg ha-1 y-1 at the eucalypt site. This discrepancy was probably related to soil type (derived from granite vs. schist) and stoniness. Mulching was somewhat more effective than the geotubes at the pines site, with reduction in average annual erosion rates of 84 and 77%, respectively. The opposite was true at the eucalypt site, with annual erosion reductions of on average 75 and 62%. The use of geotubes would therefore seem a further option for forest and water resources managers to decrease markedly the risks of both elevated and reduced soil (fertility) losses from recently burnt hillslopes and the associated risks for downstream values.

Scars left by wildfires are easily noticeable in the Mediterranean landscape, turning these events a major issue for forest management. Like any wound, even those left by fires must be treated to properly regenerate.In a burned area the vegetation cover is often destroyed by the fire, leaving the soil unprotected and vulnerable to erosion. The alterations of soil properties induced by fires lead to an increase in surface runoff, promoting the detachment of sediments and consequently endangering the water quality of downstream aquatic systems. If left unmanaged, the spontaneous regeneration of vegetation will eventually cover the affected area, restoring its natural hydrological cycle. After a wildfire, in Portugal, following an economical based perspective, the burned areas are normally reforested with selected plants species, namely Eucalypt and Maritime Pine, not infrequently by resorting to the implementation of bench terraces.To define the best management strategy to adopt after a fire, the scientific community is continuously assessing the effects of these forestry practices on soils and the downstream water bodies. In this study, the Soil and Water Assessment Tool (SWAT) was used to simulate three different post-fire land management scenarios for a small catchment (21.9 ha) in central Portugal. The choice of this basin relates to the implementation of terraces to create a eucalyptus forest production area, 6 months after a fire burned the catchment completely. The model was calibrated for streamflow and water quality at the catchment outlet, both for the short post-fire period and the following eucalyptus cycle. In this study two post-fire scenarios were created, one with the recovery of the vegetation, and another in which a highly effective erosion mitigation measure (mulching) was applied to the high and moderate fire severity burned areas. The third scenario corresponded to the implementation of the terraces and the actual eucalyptus cycle.Both the mulch application and the eucalyptus cycle scenario showed an important reduction in soil loss and sediment transport when compared with the post-fire spontaneous recovery scenario. A smaller reduction in the total runoff, as well as a negligible change in total flow, was found in the mulching scenario when compared with the spontaneous recovery one. Despite the eucalyptus cycle presented the highest flow discharge for the overall period, it presents smaller discharge peaks when compared with the two post-fire management scenarios.

Wildfires constitute a diffuse source of contamination to aquatic ecosystems. In burnt hillslopes, ash and sediments transported by overland flow are a source of potentially hazardous substances, like metals, posing a risk for downstream water bodies. In the present study, post-fire metal mobilization by overland flow was evaluated in 16 m2 bounded plots at a eucalypt stand in Albergaria-a-Velha (Aveiro district, North-Central Portugal) that burnt with moderate severity in September 2019. Overland flow samples were collected on a weekly to bi-weekly basis, depending on the occurrence of rain, during the first 6 months after fire. Aside from overland flow samples collected at slope scale, water and sediment samples were also collected in a fire-affected stream within the Albergaria burned catchment, to assess the contamination risk posed by the fire. Samples were collected at three sites along the stream: one upstream, one within and another downstream from the burnt area, after major rainfall events. The metals analysed in this study included, vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd) and lead (Pb). Results showed that most metals exhibited a peak in exports immediately after the first significant post-fire rainfall event likely due to the wash-off of the ash layer and high sediment losses, but for some elements like Zn and Cu, exports were more or less constant over time. The fire seems to have had a low impact on the water quality of the affected stream, since metal concentrations were similar between the three study sites. The quality of stream sediments, on the other hand, was clearly affected by the fire, especially after the rainy season. As fire severity and frequency is forecasted to increase in the near future due to climate changes, the results of this work reinforce the importance of water managers to define adaptative strategies to effectively protect freshwater bodies.

Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds, found ubiquitously in all environmental compartments. PAHs are considered hazardous pollutants, being of concern to both the environmental and human health. In the aquatic environment, PAHs tend to accumulate in the sediment due to their high hydrophobicity, and thus sediments can be considered their ultimate sink. Concurrently, sediments comprise important habitats for benthic species. This raises concern over the toxic effects of PAHs to benthic communities. Despite PAHs have been the subject of several reviews, their toxicity to freshwater benthic species has not been comprehensively discussed. This review aimed to provide an overview on PAHs distribution in freshwater environments and on their toxicity to benthic fauna species. The distribution of PAHs between sediments and the overlying water column, given by the sediment-water partition coefficient, revealed that PAHs concentrations were 2 to 4 orders of magnitude higher in sediments than in water. The sediment-water partition coefficient was positively correlated to PAHs hydrophobicity. Toxicity of PAHs to benthic fauna was addressed through Species Sensitivity Distributions. The derived hazardous concentration for 5% of the species (HC5) decreased as follows: NAP (376 μg L-1) > PHE > PYR > FLT > ANT (0.854 μg L-1), varying by 3 orders of magnitude. The hazardous concentrations (HC5) to benthic species were inversely correlated to the hydrophobicity of the individual PAHs. These findings are pertinent for environmental risk assessment of these compounds. This review also identified future challenges regarding the environmental toxicity of PAHs to freshwater benthic communities, namely the need for updating the PAHs priority list and the importance of comprehensively and more realistically assess the toxicity of PAHs in combination with other stressors, both chemical and climate-related. published

Potential changes in soil quality as result of intensive agriculture are increasingly raising concerns about associated impacts and the need to implement more sustainable agricultural practices. Among several intensive crops, maize, an important human food source, is one of the most intensely produced around the world, representing harmful consequences for soil quality. Therefore, it is fundamental to understand how different agricultural management practices can influence soil quality. Hence, the main objective of this study was to compare the implications of the conventional tillage versus non-tillage in soil quality. Additionally, it was also an objective to evaluate how the implementation of herbage strips, non-irrigated and fallow areas, contribute to soil sustainability and biodiversity preservation, compensating the impacts of intensive maize cultivation. For this purpose, an integrative approach was adopted including physical-chemical parameters (e.g. bulk density, pH, electrical conductivity, field capacity, organic matter, nutrients) and biological parameters (e.g. phosphatase activity, urease activity, ecotoxicological tests with soil organisms).The obtained results revealed the existence of differences between the analyzed practices, mainly associated with chemical parameters and nutrients. When comparing no-till and conventional sowing, higher mean values for no-till were observed for the following parameters: organic matter, cation exchange capacity, nitrogen, phosphorus, nitrates, calcium, copper, zinc, iron, manganese, urease activity and invertase activity. Hence, this study highlights the importance of the implementation of nonconventional agricultural practices, as is the case of no-till, as promoters of productivity and soil sustainability. Additionally, different management practices as herbage strip, non-irrigated and fallow areas around conventional areas play an additional role in soil quality and biodiversity preservation.

Wildfires constitute a diffuse source of contamination to aquatic ecosystems. In burnt areas, the increase in surface runoff and associated sediment losses after fire, promotes the mobilization of hazardous substances, such as metals and polycyclic aromatic hydrocarbons (PAHs), posing a risk for the adjacent water bodies. In the present study, post-fire metals and PAHs export by surface runoff was evaluated in 16 m2 bounded plots in a eucalypt stand in Albergaria-a-Velha (Aveiro district, North-Central Portugal) burnt in September 2019. Runoff samples were collected on a weekly to bi-weekly basis, depending on the occurrence of rainfall, during the first 6 months after fire. The metals analyzed in this study were, vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd) and lead (Pb). As for PAHs, the analyses focused on the 16 compounds classified as priority pollutants by the United States Environmental Protection Agency. Both dissolved and particulate fractions of metals and PAHs in runoff waters were analysed in this work. Preliminary results suggest that metals are more likely to affect the water quality of fire-affected water bodies than PAHs, since low levels of PAHs were found in runoff waters. This work provides valuable information for water managers to minimize the risks of wildfires both to the environment and to public health.

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.

Mediterranean landscapes have experienced extensive abandonment and reforestation in recent decades, which should have improved the provision of hydrological services such as flood mitigation, soil erosion protection and water quality regulation. However, these forests are fire-prone, and the post-fire increase in runoff, erosion and sediment exports could negatively affect service provision. This issue was assessed using the Soil and Water Assessment Tool model for the Macieira de Alcoba mountain catchment in northwestern Portugal, covered by agriculture and forest plantations, monitored in 2010-2014 and partially burnt in 2011. The model was validated for streamflow, sediment yield and erosion in agricultural fields and burnt hillslopes, showing that it can be adapted for post-fire simulation. Model results for a decadal assessment (2004-2014) show that the fire increased erosion in the burnt slopes from 0.1 to 46.5 Mg ha-1 y-1, and catchment sediment yield from 0.14 to 2.1 Mg ha-1 y-1. Erosion in the burnt forest during this decade was one order of magnitude above that in agricultural fields. Model results for different fire and land-use scenarios indicate that post-fire erosion and sediment yield were lower without post-fire soil management for reforestation, and when the fire occurred in pine forests (land-use before the 1990s) or in shrublands (land-use before afforestation in the 1930s). These impacts were robust to changes in post-fire weather and to a longer (20-year) unburnt period. The results suggest that, in the long term, Mediterranean fire-prone forests might not provide the anticipated soil protection and water quality regulation services.

Over the past decades, wildfires have affected extensive areas of the Mediterranean region with negative impacts on the environment. Most of the studies on fire-affected areas have focused on sediment losses by overland flow, whereas few have addressed post-fire nutrient export. The present study aimed to address this research gap by assessing nitrogen (nitrate and total nitrogen) losses by overland flow in a recently burnt area in north-central Portugal. To this end, three burnt slopes were selected for their contrasting forest types (eucalypt vs. pine) and parent materials (granite vs. schist). The selected study sites were a eucalypt site on granite (BEG), a eucalypt site on schist (BES) and a maritime pine site on schist (BPS). Overland flow samples were collected during the first six months after the wildfire on a 1- to 2-weekly basis, after which this study had to be cancelled due to bench terracing of some of the sites. A peak in total nitrogen concentrations was observed in burnt areas immediately after the first post-fire rainfall event as a response to the erosion of the N-enriched ash layer. After this initial peak, smaller peaks were observed throughout the study period, mainly as a response to overland flow and/or erosion events. Nitrogen export differed strikingly between the two types of forests on schist, being higher at the eucalypt than at the pine site, due to the lack of a protective soil layer. Parent material did not play an important role on nitrogen export by overland flow since no significant differences were found between the eucalypt sites on granite and schist. The present study provides some insight into the differences in post-fire soil fertility losses between forest types and parent materials in the Mediterranean region, which is crucial information for defining post-fire land management measures to reduce soil degradation.

The impacts of forest fires on runoff and soil erosion have been assessed by many studies, so the effects of fires on the hydrological and geomorphological processes of burnt forest areas, globally and in the Mediterranean region, are well established. Few studies, however, have assessed post-fire runoff and erosion on large time scales. In addition, a limited number of studies are available that consider the effect of pre-fire land management practices on post-fire runoff and erosion. This study evaluated annual runoff and sediment losses, at micro plot scale, for 4 years after a wildfire in three eucalypt plantations with different pre-fire land management practices (i.e., plowed and unplowed). During the four years following the fire, runoff amounts and coefficients at the downslope plowed (1257 mm, 26%) and contour plowed eucalypt sites (1915 mm, 40%) were higher than at the unplowed site (865 mm, 14%). Sediment losses over the 4 years of study were also consistently higher at the two plowed sites (respectively, 0.47 and 0.83 Mg ha − 1 y − 1 at the downslope and contour plowed eucalypt site) than at the unplowed site (0.11 Mg ha − 1 y − 1 ). Aside from pre-fire land management, time-since-fire also seemed to significantly affect post-fire annual runoff and erosion. In general, annual runoff amounts and erosion rates followed the rainfall pattern. Runoff amounts presented a peak during the third year of monitoring while erosion rates reached their maximum one year earlier, in the second year. Runoff coefficients increased over the 4 years of monitoring, in disagreement to the window of disturbance post-fire recovery model, but sediment concentrations decreased over the study period. When compared with other long-term post-fire studies and with studies evaluating the effects of pre- and post-fire management practices, the results of the present work suggest that an ecosystem's recovery after fire is highly dependent on the background of disturbances of each site, as runoff and erosion values were higher at the plowed sites than at the unplowed site.

Over the past decades, wildfires have affected vast areas of Mediterranean ecosystems leading to a variety of negative on- and off-site environmental impacts. Research on fire-affected areas has given more attention to sediment losses by fire-enhanced overland flow than to nutrient exports, especially in the Mediterranean region. To address this knowledge gap for post-fire losses of phosphorus (P) by overland flow, a recently burnt forest area in north-central Portugal was selected and instrumented immediately after a wildfire. Three slopes were selected for their contrasting forest types (eucalypt vs. pine) and parent materials (granite vs. schist). The selected study sites were a eucalypt site on granite (BEG), a eucalypt site on schist (BES) and a maritime pine site on schist (BPS). Micro-plots were monitored over a period of six months, i.e. till the construction of terraces for reforestation obliged to the removal of the plots. During this 6-month period, overland flow samples were collected at 1- to 2-weekly intervals, depending on rainfall. Total P and PO4-P losses differed markedly between the two types of forests on schist, being lower at the pine site than at the eucalypt site, probably due to the presence of a protective layer of pine needle cast. Parent material did not play an important role in PO4-P losses by overland flow but it did in TP losses, with significantly lower values at the eucalypt site on granite than that on schist. These differences in TP losses can be attributed to the coarser texture of granite soils, typically promoting infiltration and decreasing runoff. The present findings provided further insights into the spatial and temporal patterns of post-fire soil nutrient losses in fire-prone forest types during the initial stages of the window-of-disturbance, which can be useful for defining post-fire emergency measures to reduce the risk of soil fertility losses.

Wildfire can induce, enhance, or destroy natural soil water repellency (SWR) depending mostly on soil burnt severity, soil and vegetation types, soil organic matter (SOM) content and type, soil texture, peak soil temperature and remaining time and, antecedent soil moisture content (SMC). In Portugal, SWR in eucalypt stands has been shown to increase surface runoff under dry antecedent SMCs in both burnt and unburnt sites, thereby enhancing soil erosion. Despite the many hydrological implications of SWR, intensive field monitoring under a wide range of SMCs is still limited. This study aimed to improve our understanding of the role of slope aspect and wildfire on the temporal evolution of SWR in Mediterranean environments, which will be helpful for hydrological modelling and post-fire soil erosion risk assessment. In this sense, two burnt eucalypt plantations (wildfire of July 2010) were selected along a neighbouring, long-unburnt eucalypt stand, in north-central Portugal, in order to assess SWR and SMC’s in a high temporal resolution. During the first two post-fire years, at 1–2 week intervals, surface (2.5 cm depth) SWR and SMC were monitored using the “molarity of an ethanol droplet” (MED) test and a soil probe, respectively. The results showed that the observed annual SWR was very high to extreme (80% of measurements ≥ 6 ethanol class) for all three sites. Wildfire reduced the annual median SWR by one class (extreme to very high) for both post-fire years. During prolonged dry periods the unburnt site was significantly more repellent (P

Wildfires affect vast areas of Mediterranean forests, thereby triggering changes in hydrological and geomorphological processes that can negatively affect both terrestrial and aquatic ecosystems. Although several studies have evaluated the post-fire hydrological and erosive response in burnt forest areas, an important knowledge gap remains with respect to nutrient mobilization by overland flow. To address this gap, a recently burnt area was selected near the Ermida village (north-central Portugal). The study area was instrumented shortly after a wildfire that occurred in July 2010, to evaluate the export of dissolved (nitrate – NO3-N and orthophosphate – PO4-P) and total nitrogen (TN) and phosphorus (TP) forms by overland flow. This was done in two burnt eucalyptus plantations due to their contrasting slope aspects (south-east vs. north-west). Bounded micro-plots were installed in August 2010 and monitored over two years. During this period, overland flow samples were collected on a 1- to 2-weekly basis, depending on the occurrence of rain. Results showed that the north west-facing slope (BE-N) presented higher nutrient losses than the south east-facing slope (BE-S), contradicting the findings of previous studies in the Mediterranean region. A logging operation that had taken place at the BE-N site shortly before the fire might account for these findings, by causing soil compaction and/or reducing the protective vegetation and litter cover. TN and TP exports were particularly pronounced during the first four months following the wildfire. After this initial period, further peaks in TN and TP exports occurred sporadically, mainly associated to intense rainfall events. The observed mid-term post-fire nutrient losses not only suggested a threat to the soil nutrient balance of Mediterranean eucalypt forests but also a potential risk of eutrophication of downstream water bodies.

Wildfires have become a recurrent threat for many Mediterranean forest ecosystems. The characteristics of the Mediterranean climate, with its warm and dry summers and mild and wet winters, make this a region prone to wildfire occurrence as well as to post-fire soil erosion. This threat is expected to be aggravated in the future due to climate change and land management practices and planning. The wide recognition of wildfires as a driver for runoff and erosion in burnt forest areas has created a strong demand for model-based tools for predicting the post-fire hydrological and erosion response and, in particular, for predicting the effectiveness of post-fire management operations to mitigate these responses. In this study, the effectiveness of two post-fire treatments (hydromulch and natural pine needle mulch) in reducing post-fire runoff and soil erosion was evaluated against control conditions (i.e. untreated conditions), at different spatial scales. The main objective of this study was to use field data to evaluate the ability of different erosion models: (i) empirical (RUSLE), (ii) semi-empirical (MMF), and (iii) physically-based (PESERA), to predict the hydrological and erosive response as well as the effectiveness of different mulching techniques in fire-affected areas. The results of this study showed that all three models were reasonably able to reproduce the hydrological and erosive processes occurring in burned forest areas. In addition, it was demonstrated that the models can be calibrated at a small spatial scale (0.5 m2) but provide accurate results at greater spatial scales (10 m2). From this work, the RUSLE model seems to be ideal for fast and simple applications (i.e. prioritization of areas-at-risk) mainly due to its simplicity and reduced data requirements. On the other hand, the more complex MMF and PESERA models would be valuable as a base of a possible tool for assessing the risk of water contamination in fire-affected water bodies and for testing different land management scenarios.

The impacts of wildfires on the hydrological and erosive response of forest ecosystems have been extensively studied worldwide. Nevertheless, few studies have measured post-fire runoff and erosion over large time scales in Mediterranean-climate type environments and even fewer studies considered the effects of pre-fire land management practices on post-fire hydrological and erosive processes. In a previous study in the Colmeal study area, Vieira et al. (2016) revealed that post-fire runoff and erosion may not follow the classic window of disturbance model, since the peak of post-fire response occurred in the second and third years after fire. This previous study also showed that pre-fire land management can substantially influence the post-fire response, since annual runoff and erosion were lower in pre-fire unplowed than plowed sites. In this follow-up work, a multiple regression model (MRM) analysis was performed to understand how several key factors influence the hydrological and erosive response of a burned Mediterranean forest, taking into account the wildfire; pre-fire land management practices (unplowed, downslope plowed, and contour plowed) and soil moisture conditions. Based on the results of the present study, post-fire runoff was largely explained by rainfall amounts and soil water repellency (SWR)-related variables, whereas erosion processes were better explained by rainfall intensity and ground cover variables. Fewer factors were found to control the hydrological response of plowed sites when compared to the unplowed site. Aside from rainfall intensity, which was the major factor controlling sediment losses, bare soil cover also seems to have been important for erosion processes at the unplowed site, whereas at the plowed sites stone cover was the second most relevant factor. Rainfall-related variables (rainfall and maximum 30-min rainfall intensity) were more important for explaining runoff and erosion under dry conditions than under wet conditions. The results of the MRM analysis are an important contribution to understand the dynamics of burned forest areas and should be considered when adapting hydrological and erosion models to post-fire environments.

Wildfires increase plot-scale soil erosion rates across the world. However, very few studies have monitored post-fire erosion losses at the catchment scale, especially in the Mediterranean region. The FIRECNUTS project was originally set out to address this research gap by selecting a recently burnt catchment and instrumenting its outlet with two flumes with maximum discharge capacities of 120 and 1700 l s-1. Six months after the fire, however, this experimental catchment was bench terraced by bulldozer. Furthermore, the smallest flume suffered from regular deposition of sediments from the onset of its construction. This study was therefore an attempt to explore whether quantifying this deposition of sediments could provide further insight into the sediment yield of a recently burnt and terraced catchment. To this end, the deposited sediments were removed and weighted on a total of 101 occasions during a three year period. The results revealed that: (i) the amounts of sediment deposited over the three hydrological years corresponded to relatively small erosion rates, varying between 0.030 and 0.046 Mg ha-1 yr-1; (ii) while bench terracing is generally viewed as a soil and water conservation technique, it did not produce a clear decrease in sediment deposition, as deposition per mm of streamflow was the same before and after terracing (0.8 kg mm-1); (iii) daily sediment deposition could be explained reasonably well by daily rainfall volume and maximum daily streamflow volume.

Wildfires have increased in Portugal in the recent decades, raising concerns about the long-term negative effects of fire recurrence on the environment. We studied the impacts of recurrent fires on the nitrogen (N) and phosphorus (P) content of mineral soil in the first year after a fire. Total nitrogen (TN) and phosphorus (TP) losses by runoff were also evaluated within the two years after a fire. Nine sites in a maritime pine forest were selected following a large wildfire in September 2012 that affected roughly 3000 ha of the Viseu municipality. Three sites had been burnt four times in the past 40 years (4 ×), three sites had been burnt once in September 2012 (1 ×), and three control sites had not been burnt (0 ×). Runoff was collected in 9 micro-plots (0.25 m2) at each site after rain events from September 2012 to September 2014. Soil N and P content were significantly higher in both burnt sites relatively to the control sites. Nitrogen as well as phosphorus losses via runoff were significantly higher at the 4 × burnt sites than at both the 1 × burnt and unburnt sites. Nutrient loss was particularly high after heavy rains. Vegetation and litter cover played an important role in reducing runoff and the associated N and P transport at the 4 × burnt sites, since a decrease in both variables was observed with the increase in vegetation cover after fire.

Studies that address the potential effects of climate and land use changes on surface water quality are scarce in the Mediterranean region. In the present work, the impacts of climate and land use changes on nutrient and copper exports from a humid Mediterranean catchment (São Lourenço) were evaluated using the SWAT model. SWAT reproduced reasonably well total nitrogen (TN), phosphorus (TP) and copper (Cu) exports in São Lourenço, providing an adequate baseline scenario as well as a suitable model parameterization for assessing the impacts of climate and land use changes under the A1B and B1 emission scenarios for the end of the 21st century (2071–2100). Land use changes scenarios were generated along the same storylines as climate change scenarios to assess the combined effects of the two stressors. Climate changes itself led to a decline in annual TN and TP exports under both emission scenarios mostly due to a decrease in runoff and erosion induced by a reduction in rainfall, but it hardly affected Cu exports largely due to its strong immobilization in soils. Land use changes per se resulted in an increase in streamflow, but the changes in water quality varied markedly according to the scenarios. A substantial decrease in TN, TP and Cu exports was observed under scenario A1B, due to a reduction in vineyard areas. Under scenario B1, however, TP exports decreased much less while TN exports hardly changed, reflecting differences in the preferential transport pathways of these compounds. Cu exports also remained the same, as no changes occurred in the vineyard areas. The combination of climate and land use change scenarios revealed additive impacts on the exports of all three contaminants, emphasizing the importance of integrated approaches to define adaptive land management practices that can ensure the future sustainability of Mediterranean water resources.

The impacts of climate and land use changes on streamflow and sediment export were evaluated for a humid (São Lourenço) and a dry (Guadalupe) Mediterranean catchment, using the SWAT model. SWAT was able to produce viable streamflow and sediment export simulations for both catchments, which provided a baseline for investigating climate and land use changes under the A1B and B1 emission scenarios for 2071-2100. Compared to the baseline scenario (1971-2000), climate change scenarios showed a decrease in annual rainfall for both catchments (humid: - 12%; dry: - 8%), together with strong increases in rainfall during winter. Land use changes were derived from a socio-economic storyline in which traditional agriculture is replaced by more profitable land uses (i.e. corn and commercial forestry at the humid site; sunflower at the dry site). Climate change projections showed a decrease in streamflow for both catchments, whereas sediment export decreased only for the São Lourenço catchment. Land use changes resulted in an increase in streamflow, but the erosive response differed between catchments. The combination of climate and land use change scenarios led to a reduction in streamflow for both catchments, suggesting a domain of the climatic response. As for sediments, contrasting results were observed for the humid (A1B: - 29%; B1: - 22%) and dry catchment (A1B: + 222%; B1: + 5%), which is mainly due to differences in the present-day and forecasted vegetation types. The results highlight the importance of climate-induced land-use change impacts, which could be similar to or more severe than the direct impacts of climate change alone.

The current fire regime in the Mediterranean Basin constitutes a serious threat to natural ecosystems because it drastically enhances surface runoff and soil erosion in the affected areas. Besides soil particles themselves, soil cations can be lost by fire-enhanced overland flow, increasing the risk of fertility loss of the typically shallow and nutrient poor Mediterranean soils. Although the importance of cations for land-use sustainability is widely recognized, cation losses by post-fire runoff have received little research attention. The present study aimed to address this research gap by assessing total exports of Na + , K + , Ca 2 + and Mg 2 + in a recently burnt forest area in north-central Portugal. These exports were compared for two types of planted forest (eucalypt vs. maritime pine plantations), two types of parent materials (schist vs. granite) and for two spatial scales (micro-plot vs. hill slope). The study sites were a eucalypt plantation on granite (BEG), a eucalypt plantation on schist (BES) and a maritime pine plantation on schist (BPS). Overland flow samples were collected during the first six months after the wildfire. Cation losses differed strikingly between the two forest types on schist, being higher at the eucalypt than pine site. This difference was evident at both spatial scales, and probably due to the extensive cover of a needle cast from the scorched pine crowns. The role of parent material in cation export was less straightforward as it varied with spatial scale. Cation losses were higher for the eucalypt plantation on schist than for that on granite at the micro-plot scale, whereas the reverse was observed at the hill slope scale. Finally, cation yields were higher at the micro-plot than slope scale, in agreement with the general notion of scaling-effect in runoff generation.