Wildfires are an environmental concern due to the loss of forest area and biodiversity, but also because their role as drivers of freshwater systems contamination by metals. In this context, the fish
...Gambusia holbrooki
was used as a model, deployed for in situ exposure in watercourses standing within a recently burnt area and further assessment of toxic effects. The fish were exposed during 4 days at four different sites: one upstream and another downstream the burnt area and two within the burnt area. Biochemical biomarkers for oxidative stress and damage were assessed. The extent of lipoperoxidative damage was monitored by quantifying malondialdehyde and DNA damage evaluated through erythrocyte nuclear abnormalities observation. Chemical analysis revealed higher metal levels within the burnt area, and exposed fish consistently showed pro-oxidative responses therein, particularly an increase of gill glutathione peroxidase and glutathione reductase activity, the records doubling compared to samples from sites in the unburnt area; also the activity of glutathione-S-transferases comparatively increased (by 2-fold in the liver) in samples from the burnt area, and malondialdehyde was produced twice as much therein and in samples downstream the burnt area reflecting oxidative damage. Consistently, the frequency of erythrocyte nuclear abnormalities was higher at sites within and downstream the burnt area. This study supports the use of sensitive oxidative stress and genotoxicity biomarkers for an early detection of potentially noxious ecological effects of wildfires runoff.
Wildfires have a strong impact on the environment, changing its structure, soil properties, and microclimate and subsequently its water cycle with implications on the surface energy fluxes. ...Persisting droughts and catastrophic forest fires initiated this case study of pure eucalyptus stands in north-central Portugal. Although many studies have investigated changes in actual evapotranspiration (ET
a
), surface energy flux patterns, and the related physical parameters, only a few concentrated on the fire-driven changes in pure eucalyptus stands in the Mediterranean climate. This study aims to understand the consequences of wildfires on the water cycle, namely the ET
a
, and the surface energy heat fluxes by applying a simplified two-source energy balance model in combination with medium-resolution imagery (Landsat 8). A total of 21 different burnt locations were evaluated, which burned between 2011 and 2013. Estimated surface energy fluxes and daily ET
a
were compared to nearby control sites (unburnt) during satellite overpass for the time after the fire (2013-2015). The fire scars were classified into their burn severity, using the differenced Normalized Burn Ratio. The absolute difference of ET
a
(
ET
a
) between unburnt and burnt locations was used to identify fire-driven changes in magnitude and its evolution over time. Our results show that for the unburnt stands, the contributions to the total latent heat flux were around 80% from the canopy and 20% from the soil, while for the burnt site the contributions were around 30% (canopy) and 70% (soil) shortly after the fire. Inter-annually, the difference in ET
a
increased during the rainy season, which was related to the epicormic shooting, the fast regrowth rate of foliage, and the abundance of water. Generally, smaller differences in ET
a
were related to the severity classification and stand properties (i.e. tree species and soil characteristics). Two to three years after the fire events,
ET
a
became non-significant for all severity classes, leading to an impact on the total water cycle smaller in comparison to other post-fire studies.
Scenarios serve science by testing the sensitivity of a system and/or society to adapt to the future. In this study, we present a new land use scenario methodology called ScenaLand. This methodology ...aims to develop plausible and contrasting land use and management (LUM) scenarios, useful to explore how LUM (e.g. soil and water conservation techniques) may affect ecosystem services under global change in a wide range of environments. ScenaLand is a method for constructing narrative and spatially explicit land use scenarios that are useful for end-users and impact modellers. This method is innovative because it merges literature and expert knowledge, and its low data requirement makes it easy to be implemented in the context of inter-site comparison, including global change projections. ScenaLand was developed and tested on six different Mediterranean agroecological and socioeconomic contexts during the MASCC research project (Mediterranean agricultural soil conservation under global change). The method first highlights the socioeconomic trends of each study site including emerging trends such as new government laws, LUM techniques through a qualitative survey addressed to local experts. Then, the method includes a ranking of driving factors, a matrix about land use evolution, and soil and water conservation techniques. ScenaLand also includes a framework to develop narratives along with two priority axes (contextualized to environmental protection vs. land productivity in this study). In the context of this research project, four contrasting scenarios are proposed: S1 (business-as-usual), S2 (market-oriented), S3 (environmental protection), and S4 (sustainable). Land use maps are then built with the creation of LUM allocation rules based on agroecological zoning. ScenaLand resulted in a robust and easy method to apply with the creation of 24 contrasted scenarios. These scenarios come not only with narratives but also with spatially explicit maps that are potentially used by impact modellers and other end-users. The last part of our study discusses the way the method can be implemented including a comparison between sites and the possibilities to implement ScenaLand in other contexts.
Abstract Mosses play an important role after wildfires, acting as early colonizers before the establishment of vascular vegetation, thus stabilizing, and protecting soil against erosion. However, ...little is known about the effect of moss development on soil recovery after wildfires. In this work, we studied effects of mosses on soil physicho-chemical properties in a burned eucalyptus plantation under two contrasting post-fire managements in Central Portugal, six years after wildfire. Post-fire managements were applied in two separate areas from the same wildfire and consisted of salvage logging vs. mulching with standard and low application rates (8 and 2.6 Mg ha-1, respectively). Six years after fire, for each area and management type (untreated, logged, mulched standard/low), we collected five soil samples at 0-2.5 depth with and without moss biocrusts (n=50). Soils were analysed for pH, electrical conductivity, oxidizable organic C, total N, available P, aggregate stability, macro-aggregate content, and wettability. The studied post-fire managements showed contrasting effects on soil properties in the medium-term. Whereas salvage logging did not negatively affect soils, the mulching at a standard rate increased soil fertility six years after the fire. The moss biocrust emerged after the wildfire preserved soil structure, thus decreasing the risk of soil erosion.
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.
Forest fires are probably the more deleterious event in forest and range areas in the Mediterranean nowadays. Despite the significant area burned every year, little has been done to develop ...strategies and techniques for soil and water conservation in burned areas, despite the major impacts on soil erosion and hydrological processes.
The main problem is the fast speed at which soil and water degradation occur right after the fire, in response to the first autumn rainfall events. This limits the opportunities to mitigate the deleterious impacts. This paper presents several ex-ante strategies and techniques, such as the forest planning, prescribed fire and preventive forestry, and several ex-post techniques, such as mulching, seeding, hillslope barriers, creating infiltration opportunities, channel treatments and ecosystem restoration. To be effective and implementable, techniques must be in place as soon as possible, if possible before the first rainfall events, since a significant exportation of ash and soil losses occur after the first rainfall events from burned systems.
The ex-post techniques can mitigate the degradation processes, but due to the fast implementation and to the associated costs, should be implemented in key points within the burned area, driven by the knowledge on how hydrological and erosion processes work in burned areas. The objective is to attain the most cost-effective strategies and techniques that might include the integration of several techniques at various scales, to reduce the output of water, sediments and nutrients, and therefore the degradation of local ecosystems.
•Soil degradation as a consequence of forest fires•Preventive strategies•List and evaluation of post-fire mitigation techniques
Carbon dioxide (CO
) efflux from soil represents one of the biggest ecosystem carbon (C) fluxes and high-magnitude pulses caused by rainfall make a substantial contribution to the overall C ...emissions. It is widely accepted that the drier the soil, the larger the CO
pulses will be, but this notion has never been tested for water-repellent soils. Soil water repellency (SWR) is a common feature of many soils and is especially prominent after dry periods or fires. An important unanswered question is to what degree SWR affects common assumptions about soil CO
dynamics. To address this, our study investigates, for the first time, the effect of SWR on the CO
pulse upon wetting for water-repellent soils from recently burned forest sites. CO
efflux measurements in response to simulated wetting were conducted both under laboratory and in situ conditions. Experiments were conducted on severely and extremely water-repellent soils, with a wettable scenario simulated by adding a wetting agent to the water. CO
efflux upon rewetting was significantly lower in the water-repellent scenarios. Under laboratory conditions, CO
pulse was up to four times lower under the water-repellent scenario as a result of limited wetting, with 70% of applied water draining rapidly via preferential flow paths, leaving much of the soil dry. We suggest that the predominant cause of the lower CO
pulse in water-repellent soils was the smaller volume of pores in which the CO
was replaced by infiltrating water, compared to wettable soil. This study shows that SWR should be considered as an important factor when measuring or predicting the CO
flush upon rewetting of dry soils. Although this study focused mainly on short-term effects of rewetting on CO
fluxes, the overall implications of SWR on physical changes in soil conditions can be long lasting, with overall larger consequences for C dynamics.
The present paper describes the procedures used to measure and compute the kinetic energy and various other rainfall characteristics as well as the concurrent splash erosion rates in a recently ...terraced forest plantation in Soutelo, north-central Portugal, from May to September 2007. This involved the use of an optical disdrometer, a standard automated rain gauge and two types of splash erosion measurement devices (i.e. 10 cups and 10 funnels). In the computation of the kinetic energy, the raindrops exceeding a specific threshold size were considered to not have a spherical shape. Without this correction for the shape of the bigger raindrops, the kinetic energy can be overestimated by 50% of its real value. A meteorological analysis indicated that four weather types with a western component produced more precipitation and kinetic energy, and, thus, a higher erosive power. The relationship between splash erosion and various rainfall characteristics set was analyzed in an exploratory manner, since the splash data only concern nine sampling periods. It showed well-defined relationships of increasing splash erosion with, amongst others, increasing total rainfall as well as total kinetic energy but these relationships require further analysis using additional data. The splash erosion figures obtained with the two types of devices showed a strong agreement but appeared to corroborate that the funnels are a more effective design than the cups.
In order to maintain and improve the water quality in European rivers, the Water Framework Directive (WFD) requires an integrated approach for assessing water quality in a river basin. Although the ...WFD aims at a holistic understanding of ecosystem functioning, it does not explicitly establish cause-effect relationships between stressors and changes in aquatic communities. To overcome this limitation, the present study combines the typical WFD physicochemical and biological approaches with an ecotoxicological approach. The main goal was to assess river water quality through an integrated manner, while identifying potential risk situations for aquatic communities in the Cértima river basin (Portugal). To achieve this goal, surface water samples and macroinvertebrate specimens were collected under contrasting hydrological conditions (autumn and spring seasons) at three river sites exposed to distinct pollution levels defined according to the WFD (low, moderate and highly polluted). Physicochemical water quality status was defined according to the Portuguese classification for multipurpose surface waters, whereas biological water quality was assessed in accordance with the South Invertebrate Portuguese Index. Ecotoxicological assays included four standard species, a bacterial species (Vibrio fischeri), a unicellular algae (Pseudokirchneriella subcapitata), a macrophyte (Lemna minor) and a crustacean (Daphnia magna), which were exposed to different river water concentrations. The study sites represented a clear and pronounced gradient of pollution, from the unpolluted reference site to the sites under moderate to high anthropogenic pressure. In the latter sites, clear signs of organic pollution were found, such as low dissolved oxygen concentrations, high nutrient loads and prevalence of highly tolerant macroinvertebrate species. Despite the evident signs of pollution, no clear evidence of toxicity was observed in test species, suggesting that ecotoxicological assays using standard laboratory species and methodologies might not be suitable for assessing the effects of organic pollution. Nevertheless, the integrated methodology presented in this study provided important additional information on the Cértima's water quality status. Its wider use could contribute to a more comprehensive assessment of the effects of anthropogenic pollution on the status and functioning of aquatic ecosystems under the WFD and, thereby, improve the scientific foundations for the sustainable future management of surface water resources.
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