No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
The effect of ash and needle cover on surface runoff and erosion in the immediate post-fire period
Abstract
Hillslopes are thought to be most susceptible to enhanced surface runoff and erosion immediately following wildfire due to removal of protective vegetation and litter cover, and in many cases a fire-induced reduction in soil wettability. This enhanced susceptibility declines as vegetation and litter layer recover. For logistical reasons, however, few studies have been able to examine the responses of burnt terrain immediately following burning and little is therefore known about the effect of the wettable ash layer that often covers the ground until it is redistributed or removed by wind or water erosion.
... Besides rainfall intensity, other natural factors such as land cover and soil slope degree may also affect the rate of soil erosion [4,[5][6][7][8][9]. To restrain the soil erosion, several methods have been employed, such as the use of vegetation [10], terracing [11], and soil cover [12]. ...
... Several types of mulches (i.e., pine needles, wood, olive, and vegetable residues) have been examined to investigate their potential to maintain and rectify soil quality against erosion. For example, Cerdà and Doerr [10] investigate the land cover effect (i.e., ash and needle) on the rate of erosion and runoff after a wood wildfire in Aleppo, Eastern Spain. They found that the combination of ash and needle cast effectively reduces the soil slope responses to erosion and runoff. ...
For the first time, this experimental research analyzed the efficacy of rice straw fiber as soil cover in controlling slope erosion using a physical model. Three variations of rainfall intensity, soil slope degree, and rice straw fiber were conducted in this research. The results showed that rice straw fiber in the physical model had reduced the amount of erosion significantly. In general, a higher erosion rate was obtained with the increases of rainfall intensity and soil slope degree. The experiment was conducted with the percentage 30%, 60%, and 90% of soil cover using rice fiber straw, reducing erosion rates by 92.09%, 95.55%, and 98.21 %, respectively. Therefore, the higher the percentage of rice straw fiber used as soil cover, the smaller the ground will be affected by erosion. The ratio from the soil affected by erosion was 7.91%, 4.45%, and 1.79%, respectively. The result reveals that there is a significant decrease in erosion due to the increase of fiber used in the experiments. Meanwhile, the amount of erosion in the physical model without soil cover was 98.21% for the same rainfall severity and soil slope degree. This research showed that the application of rice straw fiber as a soil surface shield is highly effective in controlling slope erosion.
... Soil water repellency (SWR) impacts both water and wind erosion as it provides readily available loose material for transport (Cawson et al., 2016;Cerdà and Doerr, 2008;Ravi et al., 2006). Water-repellent surfaces are widely known for their self-cleaning abilities Neinhuis and Barthlott, 1997). ...
... As erosion on a water-repellent soil is often considered with other factors, such as fire, there is still uncertainty about the specific effect of SWR on runoff and erosion (Cerdà and Doerr, 2008;Madsen et al., 2011;Woods and Balfour, 2008). There is also uncertainty on the impacts SWR and the other factors of runoff and erosion have on the loss of essential components from the soil. ...
Soil water repellency (SWR) increases the amount of runoff and erosion from soils. Previous experiments on water-repellent soils had shown intricate runoff movement and high rates of water and soil losses; our aim was to observe these processes, noting their influences and quantifying impacts. The experiment used a 60 × 60 cm rainfall simulation plot setup to represent an agricultural plot with packed water repellent soil and no interference of plants. We measured inputs, and monitored surface flows and erosion on 3°, 6° and 9° slopes. A surfactant treated plot was used as a control. Eroded sediment samples were collected and measured for particle size, and together with runoff analysed for organic carbon, nitrogen and macronutrients. Runoff coefficients were high (0.53 to 0.78) for untreated soil with erosion decreasing over the course of the experiment (1.41 t ha-1 to 0.74 t ha-1 over five 2 mm rainfall events, of 2 min duration, on the 9° slope). This resulted in cumulative erosion of up to 5.35 t ha-1 after a total of 10 mm of rainfall (5 × 2 mm). Importantly, silt and clay were preferentially eroded (up to 12 × higher in eroded soil than the baseline composition) and this correlated with the loss of organic carbon, nitrogen, and macronutrients. As expected, the steepest slope (9°) caused greater runoff and erosion than the lowest (3°), however, there was no significant difference in runoff and erosion between the 6° and 9° slope. Surfactant significantly decreased runoff coefficients by two orders of magnitude compared to the untreated soil. Surface flow was initially characterised by beading and rivulet formation, minimising soil contact. Over time, however, a perched, protective water layer formed over the surface, allowing subsequent water flow with reduced soil interaction. The runoff mechanisms for these small rain events were only observed on the water-repellent soils and likely reduced the degree of erosion given the high runoff coefficients. Initial water flow also promoted armouring of the soil by the attraction of smaller particles, leading to increased loss of organic carbon and nitrogen as well as macronutrients.
... The ash loads and bulk density values determined for our study sites were similar to those found for conifer forests in USA and Spain, where total ash loads ranged from 15 to 150 Mg ha À 1 and bulk density values ranged from 0.18 to 0.62 g cm À 3 (Goforth et al., 2005;Cerdà and Doerr, 2008;Woods and Balfour, 2008). The only relevant study in Australian eucalypt forest known to the authors was carried out by Santín et al. (2012) who investigated ash production in mature wet eucalypt forests near Melbourne affected by extreme fire severity during the 2009 'Black Saturday' fires. ...
... Water contamination potential of wildfire ash 3.3.1. Contamination potential from eroded ash Ash is usually highly water absorbent due to its high porosity (Cerdà and Doerr, 2008;Bodí et al., 2014). Therefore, despite it being more erodible than soil due to its loose nature and lower bulk density, wildfire ash can have a protective effect on the soil in post-fire landscapes, which have lost the interception capacity of the canopy and litter layer (Bodí et al., 2014). ...
... Ash released by wildfire and post-fire repellency may alter the hydrological response of burned soils compared to unburned site. In short, ash may clogs soil pores and induce surface sealing (Keesstra et al., 2014) or, in contrast, can increase water adsorption before infiltration (Cerdà and Doerr, 2008). Soil water repellency generally reduces water infiltration through inducing hydrophobicity (Doerr et al., 2000;Pierson et al., 2008). ...
... Fire tends to destroy obstacles, which reduces water storage and increase the erosive power of overland flow, occurring more readily on the soil surface (Shakesby and Doerr, 2006), although the small scale of our experiment did not allow to observe this effect. The decrease in peak flow in soils with increasing vegetation cover is expected, due to the beneficial effects on soil hydrology under dead or living vegetation (e.g., Cerdà and Doerr, 2008;Prats et al., 2012) and to the increasing infiltration rates. In contrast, Pierson et al. (2002) did not found significant differences in peak flows generating in burned and unburned soils covered by sagebrush. ...
This study evaluates soil hydrology in a semi-arid soil of Spain dominated by
Macrochloa tenacissima (a widely-spread species in Northern Africa and Iberian
Peninsula) after a wildfire. Rainfall simulations were carried out under three soil
conditions (bare soil, and burned or soils with unburned vegetation) and low-to-high
slopes, and infiltration, surface runoff and erosion were measured. Infiltration rates did
not noticeably vary among the three soil conditions (maximum variability equal to
20%). Compared to the bare soil, the burned area (previously vegetated with M.
tenacissima ) produced a runoff volume lowered by 27%. In contrast, in the area
covered by the same species but not burned, the runoff was lowered by 58%. The
burned areas with M. tenacissima produced soil losses that were similar as those
measured in bare soils, and, in steeper slopes, even higher. Erosion was instead much
lower (-83%) in the sites with unburned vegetation. Overall, the control of erosion in
these semi-arid lands is beneficial, to reduce the possible hydrological effects
downstream of these fire-prone areas, and, in this direction, the establishment of
vegetation strips of M. tenacissima in large and steep drylands of bare soil left by fire
may be suggested to land managers.
... The exact mixture of wildfire ash can depend on the geographical region, vegetation type, soil and biomass characteristics, on burn intensity, and fire-fighting approach (Barber et al., 2003;Harper et al., 2019). Post-fire rainfall and wind events facilitate the deposition of ash into freshwaters (Cerdà & Doerr, 2008;Leigh et al., 2015;Reneau et al., 2007). For example, a period of heavy rainfall (153 mm over 6 days) removed 36 mm of wildfire ash following a high intensity wildfire in eastern Spain (Cerdà & Doerr, 2008). ...
... Post-fire rainfall and wind events facilitate the deposition of ash into freshwaters (Cerdà & Doerr, 2008;Leigh et al., 2015;Reneau et al., 2007). For example, a period of heavy rainfall (153 mm over 6 days) removed 36 mm of wildfire ash following a high intensity wildfire in eastern Spain (Cerdà & Doerr, 2008). Wildfire intensity also plays a role in determining erosion events; heavily burned and de-vegetated catchments facilitate wind and rain erosion. ...
Climate and land-use changes are expected to increase the future occurrence of wildfires, with potentially devastating consequences for freshwater species and ecosystems. Wildfires that burn in close proximity to freshwater systems can significantly alter the physicochemical properties of water. Following wildfires and heavy rain, freshwater species must contend with complex combinations of wildfire ash components (nutrients, polycyclic aromatic hydrocarbons, and metals), altered light and thermal regimes, and periods of low oxygen that together can lead to mass mortality events. However, the responses of aquatic fauna to wildfire disturbances are poorly understood. Here we provide a systematic review of available evidence on how aquatic animals respond to and recover from wildfire disturbance. Two databases (Web of Science and Scopus) were used to identify key literature. A total of 83 studies from across 11 countries were identified to have assessed the risk of wildfires on aquatic animals. We provide a summary of the main ecosystem-level changes associated with wildfires and the main responses of aquatic fauna to such disturbances. We pay special focus to physiological tools and biomarkers used to assess how wildfires impact aquatic animals. We conclude by providing an overview of how physiological biomarkers can further our understanding of wildfire-related impacts on aquatic fauna, and how different physiological tools can be incorporated into management and conservation plans and serve as early warning signs of wildfire disturbances.
... Since the last century, they are focusing on the relation between wildfires, ecosystem recovery, soil restoration and water resources (Cerdà, 1998). Immediately after the fire, the absorbing properties of the ash layer can reduce the potential activation of runoff to a negligible rate, decreasing the soil water repellency (Cerdà and Doerr, 2008). However, recent investigations also affirm that the ash layer soon loses this biological ability and is drastically exposed to immediate raindrop impact (Oliveira-Filho et al., 2018). ...
... However, there was an exception for the first sampling campaign carried out in the burned pine area, which conserved an elevated soil moisture content. Possibly, the main reasons were the high content of ashes on the surface soil, which can retain the water after raining, generating a new layer with organic material (Cerdà and Doerr, 2008). Ryżak et al. (2015) found that a decrease in soil moisture content may significantly favour the amount of splashed soil. ...
This research aimed to estimate the splash erosion and its evolution during the first months in specific land uses after a forest fire. The study area was located in Congosto (North-West Spain), after a wildfire occurred in May 2012, which burned 15.56 ha of scrubland and Pinus reforestation. Two different burned land uses were selected and compared to control areas: i) burned pine forest; and, scrublands. Rainfall intensity and the number, sizes and speed of raindrops were measured by an optical disdrometer and soil loss by funnels. Moreover, infiltration, soil moisture content, aggregate stability, water repellence, pH and organic matter were also measured. Results showed that the highest soil losses occurred in the burned areas, especially in the scrubland plots. The most influential factors were the presence of bare soil and the very low vegetation recovery rate. Changes in soil properties did not significantly influence splash erosion, although an increase in the presence of smaller classes of aggregates could promote erosion in the scrubland. We conclude that the vegetation ecosystem restoration is the key issue to be considered after a wildfire, especially, in those types of land uses which are severely affected by the fire.
... Outside of the burned area other effects can happen, namely an increase of floods risk and downstream water bodies pollution (Cerdà and Doerr, 2008;Shakesby, 2011). In addition to the direct and indirect effects of wildfires, forest management practices can also increase runoff and soil erosion in burned areas (Shakesby et al., 1996;Malvar et al., 2016), thus highlighting the need for application of effective post-fire erosion mitigation measures. ...
Forest wildfires typically increase runoff and associated soil and organic matter losses. Both ploughing and mulching with forest residues have been applied in recently burnt areas in Portugal to mitigate these effects in soil erosion, but their effectiveness has never been compared directly. To this end, soil and organic matter losses by water after a wildfire were studied in two eucalypt plantations in central Portugal that had been affected by the same wildfire (August 2015). One of the sites was instrumented with six erosion plots (2 m by 8 m), divided over two blocks with one treatment per block: control (doing nothing) and ploughing to 0.2 m depth with a tracked excavator. The other site was instrumented with nine erosion plots, divided over three blocks with three treatments in each block: control (doing nothing) and mulching with forest logging residues at reduced (2.6 Mg ha-1) and standard application rates (8 Mg ha-1). Mulching was performed one month after the wildfire, whereas ploughing took place one year after the wildfire. For this study, soil and organic matter losses were monitored at 12 occasions from July 2016 to May 2017, roughly coinciding with the second post-fire year. Over this relatively dry period sediment losses at the control plots of both ploughed and mulched sites averaged 1.6 and 0.6 Mg ha-1 respectively. The corresponding losses of the ploughed plots were 19% lower, whereas those of the mulched plots were 67 and 93% lower at the reduced and standard mulch rates, respectively. The organic matter content of the eroded sediments was 22% in the unploughed plots, and ploughing reduced this figure in half, which could be explained by the inversion of the topsoil horizons by the excavator. Mulching at the standard application rate seemed to produce a clear enrichment in organic matter content compared to mulching at the reduced rate as well as doing nothing (25 vs. 16 and 14%). The two main findings of this research were that i) erosion rates exceeded the 1 Mg ha-1 tolerable soil loss during the second post-fire year, indicating that mitigation measures have to be implemented, ii) ploughing was clearly less suited for mitigating post-fire erosion than mulching with forest logging residues, even at application rates as low as that typically used in operational post-fire emergency stabilization with straw mulching.
... The temporal persistence of these pyrogenic inputs is highly variable. The effects of fine ash are transient due to the mobile nature of ash (Cerdà and Doerr, 2008), but other soil properties, such as pH and OM content, may show persistant legacy effects of fire for > 45 years (James et al., 2018). ...
Prescribed fire is widely used for ecosystem restoration, yet the mechanisms that determine its effectiveness remain poorly characterized. Because soil hydrology influences ecosystem processes like erosion, runoff, and plant competition, it is important to understand how fire affects soil hydrology. A systematic approach to understanding relationships among vegetation, topography, and fire is needed to advance knowledge of how fire influences soil properties that in turn affect restoration success. Our objective was to characterize relationships among burn severity, vegetation, and soil hydrology in a heterogenous landscape under restoration management. Our study took place in a barrens-forest mosaic with recent prescribed fire history ranging from 0 to 10 burns since 1960, and additional variation in fuel loading, burn severity, vegetation cover, topography, and soils. We measured soil hydraulic conductivity (SHC) during two consecutive years, which represented control, prefire, postfire, and 1-year postfire conditions. Regression tree analysis identified an important threshold effect of antecedent soil moisture on SHC; soils with initial moisture < 13% had lower SHC than soils with initial moisture > 13%. Furthermore, above this threshold, sites with intermediate to high recent burn frequency (4–10 burns) had significantly greater SHC than unburned control sites. High fuel loads associated with brush cutting and piling increased SHC at barrens sites but not brush or pine sites, suggesting an interaction between vegetation cover and fire effects on SHC. At the local hillslope scale, toe-slopes had greater SHC than summits. Our results suggest that repeated prescribed fires of moderate to high frequency may enhance SHC, thereby reducing soil water retention and potentially restoring functional pine barren processes that limit woody plant growth. Prescribed fire may therefore be an important management tool for reversing mesophication and restoring a global array of open canopy ecosystems.
... In addition, some authors suggest the need for separate vegetation and soil burn severity assessment because these ecosystem components can be affected differently by wildfires depending on stand structure and fuel and fire behavior (Jain et al. 2004;Jain and Graham 2007;Fernández et al. 2020). The risk of soil erosion is higher in forest stands affected by crown fire than in stands in which the tree crowns are only scorched because the presence of needle cast enables water infiltration and thus favors a reduction in post-fire erosion loads (Cerdà and Doerr 2008;Neris et al. 2017;Fernández et al. 2020). Therefore, areas where soil burn severity should be assessed with a view to implementing urgent measures to mitigate post-fire soil erosion are those in which the vegetation is almost completely consumed during fire. ...
Background
Forest fires have increased in extent and intensity in the Mediterranean area in recent years, threatening forest ecosystems through loss of vegetation, changes in soil properties, and increased soil erosion rates, particularly in severely burned areas. However, establishing the relationships between burn severity and soil properties that determine infiltration remain challenging. Determining where soil burn severity evaluation should be carried out is critical for planning urgent measures to mitigate post-fire soil erosion. Although previous research has indicated that spectral indices are suitable for assessing fire severity, most of the classifications used consider combined effects in vegetation and soil. Moreover, the relationship between spectral indices and soil burn severity has scarcely been explored until now.
Results
We selected three pine stands in Spain for study immediately after being burned by wildfires. We analyzed various soil properties (soil saturated hydraulic conductivity, mean weight diameter of soil aggregates, and soil organic carbon) in relation to six levels of soil burn severity in all three stands. In addition, we established 25 field plots in the burned areas. We computed ten spectral indices for each plot by using Sentinel-2 satellite data. The soil burn severity categories indicated the degree of degradation of important soil properties related to soil erosion susceptibility. Of the spectral indices considered, the relativized burn ratio (RBR) was the best predictor of cumulative infiltration and mean weight diameter of soil aggregates. The differenced mid-infrared bispectral index (dMIRBI) was most closely correlated with soil organic carbon content.
Conclusions
The findings demonstrate the potential applicability of remote sensing to determining changes in soil properties after fire.
... While some it could exist some evidences that link the forest fires of 2017 to changes in water quality in the studied basin, these are not yet very clear. One reason can be related to ash having the ca- pacity of increase infiltration and prevent or delay the runoff up to a certain thresholds of rainfall quantity and intensity (Cerdà and Doerr, 2008). The precipitation of the hydrological year of 2017/2018 in the study are up until February were very low compar e to the normal precipitation of the last 30 years. ...
Following the major wildfires that affected the Central region of Portugal in 2017, a watercourse monitoring campaign was initiated in November 2017 to determine changes in water proprieties in a post-fire scenario, and establish the persistence of these effects. In the Mondego River basin, 10 points, from 6 watercourses, were chosen based on the size of the watershed and the percentage of burnt area. Monthly water monitorization featured in situ parameters and major ions analysis. A higher electrical conductivity was found in water in November 2017, before the first runoffs. Major ions have, in generally, decreased from December to January. However, the Cavalos brook showed an increase in NO3 concentration, and the downstream of Mondego River showing increase in Ca, HCO3 and NO3.
... Straw mulching is more viable than erosion barriers for decreasing soil erosion after severe wildfires, despite low rate application (Fernández and Vega 2016). Many studies agree that at least 60% of ground coverage is exposed to soil erosion after fires (Johansen et al. 2001;Vega et al. 2005;Cerdà and Doerr 2008). In agreement with Vega et al. (2014), straw mulch that covered approximately 60% of the affected area reduced soil erosion 70% during the first month after the fire, whereas erosion barriers reduced soil loss by only 32% during the first year of application and decreased rapidly afterwards (Fernández and Vega 2016). ...
The agricultural industry is one of the main economic contributors in developing countries, especially in tropical regions. Extensive land clearing has led to severe erosion within the watersheds, which increases the vulnerability of water catchments to natural disasters, such as floods. Cellulosic fibers, such as jute, sisal, kenaf, hemp, and coir, are gaining increasing worldwide attention for their potential application in controlling soil erosion, principally due to their remarkable biodegradable and physical properties. Nonetheless, the research on biocomposites in controlling soil erosion is limited compared to the natural fibers. This is perhaps due to poor availability and high cost of biodegradable polymers compared to natural fibers, which are abundant and inexpensive. Poor adhesive interactions between the matrix and natural fibers due to the hydrophilic characteristic of the fibers is another major drawback that limits the development of biocomposites for controlling soil erosion.
... The soil type in our study was classified as Leptosols, that are known for their low susceptibility to water repellency [40]. Ash might alter soil hydrological properties, increasing water retention and reducing sediment loss [41]. However, ash can also clog soil pores and increase surface erosion [42]. ...
There is a lack of information in the rural Mediterranean area about agricultural pile burning impacts on soil nitrogen (N) dynamic and the N loss. Therefore, this research aims to study the impacts of moderate (MS), and high (HS) severity burn on N transformation and N losses, compared to an unburned (C) during the first year. The experimental plots (10 m 2) were established in Croatia (43 • 58 N 15 • 31 E), in a slope~18 • , with a southwest exposition. Five days after the burn, C treatment had a significantly higher total N (TN) than MS and HS. Generally, the runoff was significantly different between burned and C treatments. Sediment yield, concentrations, and TN loss were significantly higher in MS than in C treatment. The concentrations of ammonium (NH 4-N) and nitrate (NO 3-N) in the runoff, and their losses were higher in burn treatments than in C treatment. These values were high in the first three months after burn, although the peaks in later periods correspond to extreme rainfall events. Principal component analysis showed that sediment yield was associated with sediment concentration, runoff, and TN loss (Factor 1). In addition, rainfall amount and intensity were inversely related to NH 4-N concentration and losses (Factor 2). The NO 3-N concentration was positively related to NO 3-N losses. Overall, MS treatment had severe effects on N loss and, sediment yield can be used as an indicator of soil degradation after pile burns.
... 12 Erosion could also generate deposition of soil materials in the reservoirs, irrigation schemes and waterways downstream. 13 It is true that the inherent characteristics of the soil greatly affect Int J Hydro. 2021;5(1):9-21. ...
Water induced soil erosion has been continued to threaten the land resources in sub humid northwestern highlands of Ethiopia. Human-induced land cover (LC) changes due to improper land management practices are contributing factors in deteriorating soil quality. Soil and water conservation measures have been implemented without site-specific scientifically quantified soil erosion data and priority bases in this regard; this study was conducted with a view to quantifying soil erosion in Anka-Shashara watershed. To do this, we have opted to use the RUSLE model based on geographic information systems. By collecting data on rainfall, soils, vegetation, slopes and conservation practices separately as a layer and determining the pixel values for each of these factors, a quantified assessment of erosion in the basin is obtained. The result reveals that the mean annual soil loss (15.22t/ha/yr) of the most parts of study area falls in tolerable levels and almost 66% (1594 ha), moderate level about 23% and 10% at high level of watershed. The soil loss of watershed is classified in to four main classes. None to Slight rates of soil erosion (0-10t/ha) is cover the almost 66% of watershed moderate about 23% and high about 10% of erosion rate as seen from the erosion rate distribution map. The upstream of catchment needs management and protection of those existing resources and the fundamental attention for SWC as recommended bases. Therefore, to reduce sedimentation problem and ensue sustainability of the watershed need to special attention for implementing recommended SWC intervention at the earlier.
... The amount of ash produced during a wildfire depends on the amount of fuel, its type and fire intensity. Ash layers covering between 30% and 100% of burned areas have been reported (Bodí et al., 2014) with thickness from 0·6 to 7 cm (Cerda & Doerr, 2008). In addition, ash composition is highly variable, although it contains significant amounts of polycations (mainly Ca and Mg). ...
... The addition of ash increases SWR and nutrient content and decreases hydraulic conductivity [53]. In addition, ash is often considered to cause increased runoff and erosion rates following fires [54][55][56][57]. In particular, ash is thought to wash or infiltrate into the soil, clogging soil pores and thus limiting infiltration rates, which explains the increased SWR [54,58]. ...
The paper investigates the changes in the physical, mechanical, and hydraulic properties of coarse-grained pyroclastic soils, considered under both wildfire-burned and laboratory heating conditions. The soil samples were collected on Mount “Le Porche” in the municipality of Siano (Campania Region, Southern Italy), hit by wildfires on 20 September 2019. The area is prone to fast-moving landslides, as testified by the disastrous events of 5–6 May 1998. The experimental results show that the analyzed surficial samples exhibited (i) grain size distribution variations due to the disaggregation of gravelly and sandy particles (mostly of pumice nature), (ii) chromatic changes ranging from black to reddish, (iii) changes in specific gravity in low-severity fire-burned soil samples different from those exposed to laboratory heating treatments; (iv) progressive reductions of shear strength, associated with a decrease in the cohesive contribution offered by the soil-root systems and, for more severe burns, even in the soil friction angle, and (v) changes in soil-water retention capacity. Although the analyses deserve further deepening, the appropriate knowledge on these issues could provide key inputs for geotechnical analyses dealing with landslide susceptibility on fire-affected slopes in unsaturated conditions.
... In this region, post-fire runoff and erosion are almost exclusively driven by high-intensity convective rainfall events that occur between June and September (Benavides-Solorio and MacDonald, 2005). The combustion of organic material during wildfire can create an ash layer that may initially increase infiltration capacity (Cerdà and Doerr, 2008;Woods and Balfour, 2008;Shakesby, 2011) in the absence of ash clogging of soil pores (Stoof et al., 2016). Once the ash is removed, subsequent raindrop impacts on bare soil can lead to soil sealing (Larsen et al., 2009) and reduced infiltration capacities via changes in soil organic matter, soil structure, and soil water repellency (Shakesby, 2011;Moody and Ebel, 2012). ...
Hillslope erosion has often been monitored with sediment fences, but these can underestimate sediment yields due to overtopping of runoff and associated sediment. We modified four sediment fences to collect and measure the runoff and sediment that overtopped the fence in addition to the sediment deposited behind the fence. Specific objectives were to: (1) determine the catch efficiency of sediment fences measuring post‐fire hillslope erosion; (2) assess particle sorting of sand, silt/clay and organic matter from each hillslope through the sediment fence and subsequent runoff collection barrels; (3) evaluate how catch efficiency and particle size sorting relate to site and rainfall‐runoff event characteristics; and (4) use runoff simulations to estimate sediment fence volumes for future post‐fire monitoring.
Catch efficiency ranged from 28‐100% for events and 38‐94% per site for the entire sampling season, indicating a relatively large underestimation of sediment yields by sediment fences. Most of the eroded sediment had similar proportions of sand and silt/clay as the hillslope soils, but the sediment behind the fence was significantly enriched in sand while the sediment that overtopped the fence was more strongly enriched in silt/clay. The sediment fences had capacities of 3 m³ for hillslopes of 0.19‐0.43 ha, but simulations of runoff for 2‐ to 100‐yr storms indicate that the sediment fences would need a capacity of up to 240 m³ to store all of the runoff and associated sediment. More accurate measurements of sediment yields with sediment fences require either increasing the storage capacity of the sediment fence(s) to accommodate the expected volume of runoff and sediment, reducing the size of the contributing area, or directly measuring the runoff and sediment that overtop the fence.
... The reduction in IR in the short term may be due to two synergistic effects. First, the presence of the ash layer left by fire may have clogged soil pores and induced sealing of the soil surface, [32,33], while it was not able to increase water adsorption before infiltration [31,53], due to its small thickness. Other studies about prescribed fire have shown that ash contributed to reduce infiltration, creating a thin layer (few mm) of low porosity and permeability [53]. ...
Prescribed fire is commonly used to reduce the wildfire risk in Mediterranean forests, but the soil’s hydrological response after fire is contrasting in literature experiences. The mulch treatment can limit the increases in runoff and erosion in the short term after fire. The use of fern is preferable to straw, due its large availability in forests. However, no experiences of post-fire treatment with fern mulch have been found in literature and therefore the mulching effectiveness has not been evaluated. This study has measured soil hydraulic conductivity (SHC) and water repellency (SWR) using a rainfall simulator in three Mediterranean forest stands (pine, oak and chestnut) of Calabria (Southern Italy) after a prescribed fire and mulching treatment with fern in comparison to unburned soil. Prescribed fire reduced water infiltration in all forests in the short term compared to the unburned conditions, and increased SWR in pine and oak forests. These reductions in SHC in the window of disturbance after fire increased the runoff generation capacity (conversely stable in unburned soils) in all soils, but had a lower effect on peak flows. However, soil mulching with fern llimited runoff rates and peak flows compared to the burned soils, but this treatment was less effective in pine forest. One year after fire, SHC increased in burned soils (treated or not) over time, and SWR disappeared. The effects of mulching have disappeared after some months from fire. The study confirms the usefulness of mulching in broadleaves forest in the short term, in order to control the hydrological effects of prescribed fire in Mediterranean forests. Both post-fire management techniques should be instead adopted with caution in conifer forests.
... Wildfires strongly modify the physical, chemical, and biological properties of forest soils and completely remove vegetation [9][10][11][12], and these fire actions determine often-irreversible damage to forest soils or degradation rates that need several years or even decades to be restored [10,13]. Moreover, runoff and erosion heavily increase immediately after a wildfire, with slow decreases (several months or some years), and they tend to decrease with time [14][15][16]. These negative impacts on the forest environment can be aggravated in the Mediterranean Basin [17], where the wildfire occurrence and effects are generally more severe compared to other ecosystems, due to the intrinsic climatic characteristics (dry and hot summers and frequent and intense rainstorms in autumn, immediately after the wildfire season) [10,11,18,19]. ...
Wildfire heavy impacts the quality of forest soils, and the precipitation occurring immediately after fire can determine high runoff and erosion rates, which may lead to noticeable soil degradation. Mulching is commonly used to limit the hydrological impacts of wildfire and climate, but this post-fire management technique may alter the erosion-deposition dynamics at the hillslope scale and, consequently, alter soil quality. In order to explore the magnitude and significance of these changes (little was studied in literature as far as now, this communication reports the first results of a field activity, which has evaluated the changes in soil quality in areas affected by a wildfire and subjected to different post-fire treatments in Mediterranean forests. The main properties of sediments eroded from burned and not treated soils, and mulched soils (using a straw dose of 0.2 kg/m2 of dry weight) have been measured after the first rainstorm (height of 37 mm and maximum intensity of 11.6 mm h−1) occurring two months after a wildfire (occurred on 30 June 2016) in pine forest of Castilla-La Mancha (Spain). This event produced a runoff volume of 0.07 ± 0.02 mm in mulched soils and 0.10 ± 0.10 mm in non-mulched soils; soil loss was 0.20 ± 0.06 g/m2 in mulched area and 0.60 ± 0.60 g/m2 in non-mulched area. In comparison to burned and non-treated areas, this study has shown: (i) increases in salinity, and reductions in organic matter, nutrients, nitrates and micro-elements in burned and untreated soils; (ii) reductions in runoff (−20%) and in soil erosion (−60%) as a result of mulch cover; (iii) effectiveness of mulching in limiting the declines in soil quality detected in burned and eroded areas; (iii) transport of low amounts (less than 10–15%) of some compounds (organic matter and nutrients) downstream of the fire-affected areas (both mulched and untreated). Phosphorous runoff towards valley areas and nitrate incorporation into the soil, detected in both mulched and untreated areas require attention, since these processes may cause eutrophication of water bodies or nitrate pollution in groundwater.
Keywords: wildfire effects; soil loss; deposition; organic matter; nutrients; micro-elements; pine forest; post-fire treatments
... Thus, our framework for combining erosion monitoring and CADRs would allow land managers to have a better understanding of the quantitative target rate of erosion that can maintain good ecological status and halt or potentially reverse land degradation [127]. This research illustrates that a quantitative target of a natural background rate of erosion would be particularly useful when planning and managing different land uses such as vineyards [21,26,122,125,128], specific locations impacted by wildfire [33][34][35], and construction sites [22,24,33]. ...
Land use changes often lead to soil erosion, land degradation, and environmental deterioration. However, little is known about just how much humans accelerate erosion compared to natural background rates in non-agricultural settings, despite its importance to knowing the magnitude of soil degradation. The lack of understanding of anthropogenic acceleration is especially true for arid regions. Thus, we used 10Be catchment averaged denudation rates (CADRs) to obtain natural rates of soil erosion in and around the Phoenix metropolitan region, Arizona, United States. We then measured the acceleration of soil erosion by grazing, wildfire, and urban construction by comparing CADRs to erosion rates for the same watersheds, finding that: (i) grazing sometimes can increase sediment yields by up to 2.3–2.6x, (ii) human-set wildfires increased sediment yields by up to 9.7–10.4x, (iii) after some post-fire vegetation recovered, sediment yield was then up to 4.2–4.5x the background yield, (iv) construction increased sediment yields by up to 5.0–5.6x, and (v) the sealing of urban surfaces led to one-tenth to one-half of the background sediment yields. The acceleration of erosion at the urban–rural interface in arid lands highlights the need for sustainable management of arid-region soils.
... In this context, regarding the bulk density of the most recent and high severity fire (1B-HS: 2019, 2 years since the fire) ( Table 2), it coincides with the results obtained by Goforth et al. [84] and Chandra and Bhardwaj [18] who showed that when fires are of high severity, the bulk density tends to increase in value and generates greater soil compaction. Likewise, Cerdà and Doerr [86] showed that the increase in bulk density is due to the collapse of aggregates and the clogging of pores by ash and dispersed clay minerals. As a consequence, soil porosity and permeability decrease as bulk density generally increases when ashes reach the first few centimeters of the soil [87]. ...
Humid montane scrublands (HMs) represent one of the least studied ecosystems in Ecuador, which in the last decade have been seriously threatened by the increase in wildfires. Our main objective was to evaluate the effects of wildfire severity on physicochemical soil properties in the HMs of southern Ecuador. For this purpose, fire severity was measured using the Normalized Burn Ratio (NBR) and the difference between pre-fire and post-fire (NBR Pre-fire-NBR Post-fire) over three contrasted periods (years 2019, 2017, and 2015) was determined. Likewise, 72 soil samples from burned HMs and 72 soil samples from unburned HMs were collected at a depth of 0 to 10 cm, and some physical (bulk density and texture) and biochemical (pH, soil organic matter, and total nutrients) soil properties were analyzed and statistically processed by one-way ANOVA and principal component analysis (PCA). Results indicate that burned HMs showed mixed-severity burning patterns and that in the most recent wildfires that are of high severity, SOM, N, P, Cu, and Zn contents decreased drastically (PCA: component 1); in addition, there was an increase in soil compaction (PCA: component 2). However, in older wildfires, total SOM, N, P, K, and soil pH content increases with time compared even to HMs that never burned (p-value < 0.05). These results can help decision makers in the design of policies, regulations, and proposals for the environmental restoration of HMs in southern Ecuador affected by wildfires.
... Rainfall and snow-melt increase surface moisture and saturation, which will alter shear stresses operating on the slope and can initiate movement of poorly consolidated surface material, such as tephra (Horton 1933;Major & Yamakoshi 2005). Vegetation cover and the characteristics of soils underlying tephra will affect infiltration and rainfall interception, runoff and erosion rates (Major & Yamakoshi 2005;Cerd a & Doerr 2008;Woods & Balfour 2010;Jones et al. 2017). Rainfall simulation studies conducted using freshly fallen tephra deposits by Jones et al. (2017) reported that tephra grain movement was dominated by rainsplash detachment of coarse individual grains, with no rill formation or overland flow. ...
We explore the effect small‐scale surface features have on influencing the morphology and grain‐size distribution (GSD) of tephra layers within the Quaternary stratigraphy of sub‐polar landscapes. Icelandic thúfur, small cryogenic earth mounds, are used to assess how and why the morphology and GSD of tephra layers vary over such formations. Through measurement of tephra layer thickness and GSD, Hekla 1947 and Grímsvötn 2011 tephra layers are analysed. Results indicate that such microtopographic features do indeed alter the form of tephra deposits and therefore the tephra layer that is preserved in the stratigraphy. Tephra thickness is significantly greater in hollows than on the thúfur crests. There is greater variation in tephra thickness measurements from thúfur in comparison to control measurements from a surface where thúfur are absent. Thúfur crests contain larger grain sizes than hollows, for both H1947 and G2011 tephras; however this was only statistically significant for the G2011 tephra. Such morphological patterns are thought to arise from an interplay of tephra characteristics, altered topography from the thúfur formations and earth surface processes operating at the sites. This study provides insight into the potential of tephra layer morphology and internal structures as indicators of Quaternary landforms and processes. Additionally, it provides important context for the appropriate sampling of tephra layers to infer volcanological processes, as the characteristics of preserved layers do not necessarily reflect those of the original fall‐out.
... Soil erosion has on-site and off-site effect; soil quality and productivity as on-site effect (Haregeweyn et al. 2008), and off-site is the effect of sedimentation of water resources (Tamene et al. 2011). The off-site effect also generates deposition of soil materials in the reservoirs, irrigation schemes and waterways downstream (Cerdà and Doerr 2008). ...
... CS is also associated with both short-and long-term benefits to forest recovery, as it provides nutrients and "safe sites" (Christopoulou et al., 2014) for protecting seeds, along with mitigating erosion (Castro et al., 2011;Pausas et al., 2002). Finally, the CC category, with an important presence of ash layer, is expected to suffer the greatest alteration of soil properties and structure (Bodí et al., 2011;Pausas et al., 2002), enhancing runoff and sediment concentration especially in the long term (Cerdà and Doerr, 2008;Pérez-Cabello et al., 2012). ...
https://authors.elsevier.com/a/1bYne7qzSr75H
... Fires are considered a powerful and influential environmental factor in soil formation as they have a complex and multifaceted impact on ecosystem processes such as erosion, subtraction (runoff) of organic matter and plant succession (Baldock and Smernik 2002;Certini 2005Certini , 2014Cerdà and Doerr 2008;Guénon et al. 2013). Numerous studies of the influence of the pyrogenic factor on soil systems distinguish two types of this influence (Sharrow and Wright 1977;Bezkorovaynaya et al. 2007;Tsibart and Gennadiev 2008;Krasnoschekov and Cherednikova 2012;Smits et al. 2016;Dymov et al. 2018;Deviatova et al. 2019): (1) pyrogenic transformation or the combustion by heat of soils as a result of direct pyrolysis, i.e., change of physical and chemical properties, strengthening of processes of mineralization of organic matter, increasing the amount of water-soluble compounds, decreasing acidity, decomposition of aluminosilicates, changes in granulometric composition, modified water and thermal modes; and, (2) pyrogenic transformation of soil formation factors, i.e., creation of a secondary postfire relief resulting in the complexity and microcomplexity of soils, a lower level of perennial permafrost, swamping, natural draining of swamps, erosion, changes in the nature Abstract Temperatures of sandy podzols of middle taiga pine forests with moss and lichen ground cover were analyzed which had been exposed to ground fires of low to medium intensity. ...
Temperatures of sandy podzols of middle taiga pine forests with moss and lichen ground cover were analyzed which had been exposed to ground fires of low to medium intensity. In general, temperatures in lichen and moss plots of the pine forests under study, are close to each similar, but in the first year after a fire a noticeable contrast was observed. The reasons are an increase in the amplitude of daily temperatures on the soil surface and stronger heating of upper mineral layers. Temperatures in the mineral layer with depths up to 30 cm depend on the thickness of the forest floor. Analysis of the results show that the duration of post-fire effects in pine forests with sandy podzols is determined by a number of factors: the intensity of the fire, the degree of erosion of the ground cover and litter, and the recovery rate of these components.
... The forest floor layer is capable of altering the amount of water available for infiltrating into the soil and surface waterflow, thus water holding capacity in the litter layer is an important parameter in forest hydrology and modeling (Gerrits et al., 2007;Tsiko et al., 2012;Li et al., 2013Li et al., , 2014. The specific water holding capacity is defined as the ability of the forest litter layer to absorb and store water as a proportion of its dry weight (Cerdà and Doerr, 2008;Gerrits et al., 2010;Zagyvainé et al., 2019;Zhu et al., 2021). The main factor that affects litter interception is litter water holding (storage) capacity, which is regulated by litter mass, thickness, and rainfall distribution (Kim et al., 2014;Li et al., 2017;Zagyvainé et al., 2019). ...
The surface of the mineral soil is covered by the forest floor forming water absorbent layers. This is how the forest floor plays an important role in soil and water conservation. The aim of this study was to individualize three leaf litters (beech, hornbeam, and maple) applied at three density rates (6, 12, and 18 Mg ha⁻¹) to assess their soil protection capacities. A total of nine treatments were conducted (i.e., beech6, beech12, beech18, hornbeam6, hornbeam12, hornbeam18, maple6, maple12, maple18) on skid-compacted soils in the Hyrcanian forests of northern Iran to evaluate effects at reducing runoff and sediment yield, and to determine the oven-dry weights and water holding capacity of litters. A total of nine runoff plots with dimensions of 1 × 2 m were established on the skid trails during the study period from September to December 2017 in a field experiment under natural rainfall. At the study period, 29 events with a total of 752.2 mm rainfall were measured in the open space area, that 26% of the rainfall was intercepted by canopy cover. Regardless of leaf litter species, the runoff and sediment yield significantly decreased as the leaf litter rate increased. The average runoff in litter plots of beech, hornbeam, and maple was 102.71, 94.25, and 116.87 mm, whereas the average sediment yield was 27.07, 22.33, and 36.73 g m⁻² for the study period, respectively. The mean water holding capacity of beech, hornbeam, and maple litter plots amounted to 84.1, 59.16, and 25.81 mm for the study period, respectively. Our study shows that the different species of leaf litter have a diverse range of hydrological functions and litter water holding capacities, which reduced runoff and sediment yield.
... After wildfires, streamflow turbidity usually increases due to the suspension of ash and silt-to-clay-sized soil particles [53]. Turbidity is an important water quality parameter because high turbidity reduces municipal water quality and can adversely affect fish and other aquatic organisms. ...
Recent megafires and gigafires are contributing to the desertification of conifer forest ecosystems due to their size and severity. Megafires have been increasing in their frequency in the past two decades of the 21st century. They are classed as such because of being 40,469 to 404,694 ha in size, having high complexity, resisting suppression, and producing desertification due to erosion and vegetation type conversion. Increasingly, gigafires (>404,694 ha) are impacting coniferous forest ecosystems. These were once thought of as only pre-20th century phenomena when fire suppression was in its infancy. Climate change is an insidious inciting factor in large wildfire occurrences. Fire seasons are longer, drier, hotter, and windier due to changes in basic meteorology. Conifer forests have accumulated high fuel loads in the 20th and 21st centuries. Ignition sources in conifer forests have increased as well due to human activities, economic development, and population demographics. Natural ignitions from lightning are increasing as a result of greater severe thunderstorm activity. Drought has predisposed these forests to easy fire ignition and spread. Wildfires are more likely to produce vegetation shifts from conifers to scrublands or grasslands, especially when wildfires occur with higher frequency and severity. Severe erosion after megafires has the collateral damage of reducing conifer resilience and sustainability.
... The hydro-sedimentary response of a watershed to fire events is complex (Vieira et al., 2018). It is related to fire impact on soil properties and changes in the vegetation cover (Cerdà and Doerr, 2008;Neary et al., 1999;Neary et al., 2005;Shakesby, 2011). The difficulties in evaluating the hydrological and sediment regimes generally increase in the Mediterranean environment with intermittent river networks due to the high spatial variability of soil properties, land use, and climate (Fortesa et al., 2021). ...
Forest fires change soil surface properties, alter the hydrological processes, and increase soil erosion. Post-fire rehabilitation measures are useful to mitigate the effect of fire on soil erosion. This work aims to predict the effects of forest fires and post-fire mitigation measures on runoff and specific sediment yield (SSY) in a river basin (Celone, S-E Italy). The Soil and Water Assessment Tool model, calibrated with field observations, was used to evaluate runoff and SSY for the current land use (baseline) and six post-fire scenarios. From 1990 to 2011, at the basin scale, the average annual SSY was 5.60 t ha- 1y-1 (SD = 3.47 t ha-1y-1). 20% of the total drainage area showed a critical value of SSY (>10 t ha-1 y-1). The effects of different fire-severity levels were analysed for one year after the fire, acting on a limited area (2.3% of the total basin area). At the basin scale, the post-fire effect on surface runoff was negligible for all scenarios (< 0.4%), and the impact on SSY increased from 5.86 t ha-1 y-1 up to 12.05 t ha-1 y-1. At the subbasin scale, the post-fire logging scenario showed the highest increase of soil loss (SSY increased from 9.48 t ha-1 y-1 to 57.40 t ha-1 y-1). Post-fire mitigation treatments like straw mulching and erosion barriers effectively reduced soil erosion in high- and moderate-severity fires (19.12 t ha-1y-1 and 20.93 t ha-1 y-1, respectively). At the hydrological response unit level, the SSY estimated for the forest in the baseline ranged from 1.18 t ha- 1y-1 to 2.04 t ha-1 y-1. It increased more than one order of magnitude for the high-severity fire scenarios and ranged from 4.33 to 6.74 t ha-1 y-1 in the very low-severity fire scenario, underlining the scale effect from the HRU to the basin scale.
... The hydro-sedimentary response of a watershed to fire events is complex (Vieira et al., 2018). It is related to fire impact on soil properties and changes in the vegetation cover (Cerdà and Doerr, 2008;Neary et al., 1999;Neary et al., 2005;Shakesby, 2011). The difficulties in evaluating the hydrological and sediment regimes generally increase in the Mediterranean environment with intermittent river networks due to the high spatial variability of soil properties, land use, and climate (Fortesa et al., 2021). ...
The present paper contributes to bridging the gaps in modelling post-fire impact and mitigation measures on soil erosion. The specific aims were to predict the effects of forest fires and post-fire mitigation measures on runoff and specific sediment yield (SSY) in a river basin (Celone, S-E Italy). The Soil and Water Assessment Tool model, calibrated with field observations, was used to evaluate runoff and SSY for the current land use (baseline) and six post-fire scenarios. From 1990 to 2011, at the basin scale, the average annual SSY was 5.60 t ha- 1yr⁻¹ (SD = 3.47 t ha⁻¹yr⁻¹). 20% of the total drainage area showed a critical value of SSY (>10 t ha⁻¹ yr⁻¹). The effects of different fire-severity levels were predicted for one year after the fire, acting on a limited area (2.3% of the total basin area). At the basin scale, the post-fire effect on surface runoff was negligible for all scenarios (<0.4%), and the impact on SSY increased from 5.86 t ha⁻¹ yr⁻¹ up to 12.05 t ha⁻¹ yr⁻¹. At the subbasin scale, the post-fire logging scenario showed the highest increase of soil loss (SSY increased from 9.48 t ha⁻¹ yr⁻¹ to 57.40 t ha⁻¹ yr⁻¹). Post-fire mitigation treatments like straw mulching and erosion barriers effectively reduced soil erosion in high- and moderate-severity fires (19.12 t ha⁻¹yr⁻¹ and 20.93 t ha⁻¹ yr⁻¹, respectively). At the hydrological response unit level, the SSY estimated for the forest in the baseline ranged from 1.18 t ha- 1yr⁻¹ to 2.04 t ha⁻¹ yr⁻¹. SSY increased more than one order of magnitude for the high-severity fire scenarios and ranged from 4.33 to 6.74 t ha⁻¹ yr⁻¹ in the very low-severity fire scenario, underlining the scale effect from the HRU to the basin scale.
... Soil erosion may be a slow process that continues relatively unnoticed, or it may occur at an alarming rate causing serious loss of topsoil [2]. Soil erosion is a sequel of unsustainable land use [3] and other disturbances, such as, mining, fire or intensive agricultural uses [4]. The loss of soil may have critical impacts on the quantity and quality of soil ecosystem services, with severe economic, social and political implications [5], [6]. ...
... Certini (2005) reported that bulk density increased because of the destruction of aggregates and clogging of pores by the ash and deflocculated clay minerals; as a consequence, soil porosity and permeability diminished. Soil densification increases with ash depth (Cerdà and Doerr 2008). Boerner et al (2009) showed that the bulk density of forest soils increased significantly as a result of the forest fire. ...
The short-term impacts of prescribed combustion of wood shavings biomass (WSB) on soil properties were examined. The experimental five treatments comprising dried wood shavings biomass were spread uniformly on the experimental plots at the rate of 0, 12.5, 25, 37.5, and 50 tons ha. The WSB was burned to produce different fire intensities. The soil temperature in plots amended with-1 in situ prescribed wood shavings biomass of 50 kg ha was higher than that in other plots by 18-26%, respectively, at both soil depths. The highest-1 bulk density (1.59 and 1.62 Mg m) were in plots amended with 50 t ha wood shavings biomass, and was higher than other. Soil saturated-3-1 hydraulic conductivity in the plots amended with 37.5 and 50 t ha wood shavings biomass was lower) than that of the other plots by 33% in-1 both soil depths. The volumetric water content and soil water droplet penetration time decreased with burn severity. In contrast, soil pH, soil organic carbon, total nitrogen, exchangeable potassium, calcium, and magnesium and available phosphorus increased with burn severity by between 5-66%, respectively, after biomass burning at the rates applied. During low intensity prescribed fires, volatile constituents of soil organic carbon are not entirely incinerated at soil temperatures <50 C, and the quantity of SOC at the surface in the short run determines the o percent SOC and other nutrients available in the topsoil.
... The river in the lower reaches is quite shallow and sedimentation after wildfires could be a contributing factor to reduced streamflow recorded at the streamgage [75]. Furthermore, with fires of moderate severity, ground cover is often increased through needle cast and downed trees, protecting the soil from erosion and subsequent runoff of snowmelt/precipitation [76][77][78][79]. ...
We analyzed impacts of interannual disturbance on the water balance of watersheds in different forested ecosystem case studies across the United States from 1985 to 2016 using a remotely sensed long-term land cover monitoring record (U.S. Geological Survey Land Change Monitoring, Assessment, and Projection (LCMAP) Collection 1.0 Science products), gridded precipitation and evaporation data, and streamgaging data using paired watersheds (high and low disturbance). LCMAP products were used to quantify the timing and degree of interannual disturbance and to gain a better understanding of how land cover change affects the water balance of disturbed watersheds. In this paper, we present how LCMAP science products can be used to improve knowledge for hydrologic modeling, climate research, and forest management. Anthropogenic influences (e.g., dams and irrigation diversions) often minimize the impacts of land cover change on water balance dynamics when compared to interannual fluctuations of hydroclimatic events (e.g., drought and flooding). Our findings show that each watershed exhibits a complex suite of influences involving climate variables and other factors that affect each of their water balances differently when land cover change occurs. In this study, forests within arid to semi-arid climates experience greater water balance effects from land cover change than watersheds where water is less limited.
... Soil erosion by water is the process that separates particles in soil due to precipitation or runoff and then transports them with flowing water. It is followed by sedimentation in steep areas, reservoirs, irrigation systems and waterways [CERDÀ, DOERR 2008;EFTHIMIOU et al. 2016;KUNTA 2009]. Soil erosion is mainly caused by rain splash impact (separation), while rill and gully erosion are caused by flowing water (separation, transport) [CHAAOUAN et al. 2013;EFTHIMIOU et al. 2017;HAAN et al. 1994]. ...
Soil erosion is an important factor that should be considered when planning renewable natural resource projects, effects of which can be measured by modelling techniques. Therefore, disintegration models determine soil loss intensity and support soil conservation practices. This study estimates soil loss rates by water erosion using the Erosion Potential Method (EPM) in the Kebir Rhumel Watershed located in Northeast Algeria. The area is north to south sub-humid to semi-arid, receives irregular rainfall, and has steep slopes and low vegetation cover which makes it very vulnerable to erosion. The main factors in the EPM (soil erodibility, soil protection, slope, temperature, and rainfall) were evaluated using the Geographical Information System (GIS) and data provided by remote sensing technologies. The erosion intensity coefficient Z was 0.60, which indicates medium erosion intensity. While the results showed the average annual soil erosion of 17.92 Mg•ha-1 •y-1 , maximum and minimum losses are 190.50 Mg•ha-1 •y-1 and 0.21 Mg•ha-1 •y-1 , respectively. The EPM model shows satisfactory results compared to some studies done in the basin, where the obtained results can be used for more appropriate management of land and water resources, sustainable planning, and environmental protection.
... The waste ash produced from the incineration of this material, although having remarkable nutrients, is considered waste by the villagers; therefore, they dump the resulting ash along the valley or beside the rivers, which can be a pollutant of the environment ( Figure 2). To date, numerous studies have been conducted on different types of ash and their effects on soil physical and chemical properties (Bauer et al., 2019;Cerdà & Doerr, 2008;Demeyer et al., 2001;Nurmegawati et al., 2019;Pagliari et al., 2009Pagliari et al., , 2010. However, no research has been carried out on the effect of livestock manure (sheep and goat) ash on the physical properties of the soil. ...
This study investigates the effects of using livestock manure (LM), livestock
manure ash (LMA) and the combination of LM with LMA (LM + LMA) on
the soil moisture content and water infiltration rate of clay, clay loam and
sandy loam soils. The soil moisture content and water infiltration rate were
11.60, 8.90 and 6.85% and 1.98, 1.55 and 1.62 cm h‾¹ for clay, clay loam and
sandy loam soils, respectively, by the application of 15 t ha‾¹ LM. Moreover,
using 15 t ha‾¹ of LMA had the most desirable effects on the soil moisture content in the clay and clay loam soils. Using this treatment, the soil moisture content and water infiltration rate were 10.85, 11.20 and 7.24% and 2.40, 1.90 and
1.75 cm h‾¹ for clay, clay loam and sandy loam soils, respectively. Promising
results were obtained using 15 + 15 t ha‾¹ of LM + LMA, where the soil moisture content and water infiltration rate were 11.50, 10.20 and 8.20% and 2.80,
1.90 and 1.72 cm h‾¹ for clay, clay loam and sandy loam soils, respectively.
Both LMA and its combination with LM were found to be positive strategies to
achieve sustainable agricultural goals because of the increased water infiltrates
(less runoff) available for the plants.
... There have been a number of studies evaluating how different surface coverings reduce surface runoff and soil loss, including rock fragments [54][55][56][57][58], biological geotextiles [30], and crop residues [59][60][61][62][63][64][65][66], grass [67][68][69], geo-textiles [30,70], post-fire ash and cover [71][72][73], tillage [64,66,74,75], and combined cover such as rock and litter [76][77][78][79]. However, little leaf litter has been tested [42,80], with varying results [81]. ...
Trash mulches are very effective in preventing soil erosion; reduce sediment transport rate, runoff rate and increasing infiltration. The study was carried out with the objectives to observe the sediment outflow from sugar cane leaf (trash) mulch treatments at selected land slopes under simulated rainfall conditions by using rainfall simulator of size 10 m × 1.2 m × 0.5 m with the locally available soil material collected from Pantnagar. In the present study, trash mulches with different quantities were selected to observe the effect of mulching in soil loss reduction. The quantity of mulch was taken as, 6 t/ha, 8 t/ha and 10 t/ha, three rainfall intensities viz. 11cm/h, 13cm/h and 14.65cm/h at 0%, 2% and 4% land slopes were selected. The duration of rainfall was fixed (10 minutes) for every mulch treatment. The total runoff volume was found to be varying with different mulch rates for particular rainfall input and land slope. The runoff distribution pattern was observed to be increasing with the increase in land slope. The average sediment concentration (SC) and outflow was found to be increasing with the increasing land slope, but SC and outflow decreased with increasing mulch rate for particular land slope and rainfall intensity. The SOR (SOR) for no mulch treated land was higher as compared to trash mulch treated lands. Mathematical relationships were developed for relating SOR, SC, land slope and rainfall intensity for a particular mulch treatment. It was observed that values of SOR and average SC had a good correlation with rainfall intensity and land slope for each mulch treatment. The correlation coefficients of developed models were found to be more than 90%.
... Soil erosion has on-site and off-site effect; soil quality and productivity as on-site effect (Haregeweyn et al. 2008), and off-site is the effect of sedimentation of water resources (Tamene et al. 2011). The off-site effect also generates deposition of soil materials in the reservoirs, irrigation schemes and waterways downstream (Cerdà and Doerr 2008). ...
Soil erosion is the main drivers in the world and Ethiopia in particular. This study has been conducted at Dijo watersheds in the Rift valley Basins of Ethiopia to estimate soil erosion rate and identify erosion hotspot areas for proper planning using Geographic Information System and Universal Soil Loss Equation adapted to Ethiopian condition. 64 years mean annual rainfall data for estimating erosivity factor, digital soil map for estimating soil erodibility factor, Digital Elevation Model for estimating topographic (LS) factor, Land use land cover for cover factor detection from Ethiopian ministry of water resources. The result reveals that the soil loss ranges from 0 ton/ha/year in flat slope to 38.09 ton/ha/year from steep slopes. The average soil loss rate is 2.2 tons per hectare per year and has been classified into three erosion severity classes as very low, low and moderate. The result also reveals that most of the watershed erosion severity evaluated under very low and low soil erosion severity classes covering 97.3% of the watershed areas which is due to the effect of mixed plantation of various tree and terraces. However, moderate soil erosion in the upper parts of the watershed could be due to the inherent characteristics of vertisols, lack of vegetation cover and terraces which should be given first priority for conservation interventions. From the gross soil erosion, 43,762 ton/year sediment yields have been estimated at watershed outlet. Policy aim at keeping land productivity will need to focus to reduce low and moderate soil erosion through terracing, inter-cropping, contour farming, strip cropping, conservation tillage, mulching and biological stabilizers based on their slope range, soil type and land use type. The current finding on erosion was evaluated based on the past 10 years land use land cover scenario; therefore, soil erosion might be reduced if the current land use land cover scenario considered. Finally, the integration of USLE and GIS is an effective tool in mapping the spatial distribution of soil erosion from the entire watershed. The moderate and low soil erosion severity areas should be managed through terracing, inter-cropping, contour farming, strip cropping, conservation tillage, mulching and biological stabilizers based on their slope range, soil type and land use type. Free grazing and cultivation of steep slope(Northern parts) contributed for moderate soil erosion in the watershed should be managed by cut-carry system, limiting the number of cattle units to be grazed in the specific plot of land and leaving the marginal steep slope areas with no ground covers for natural regeneration. Finally, the current finding on erosion was evaluated based on the past 10-year land use land cover scenario. Therefore, the soil erosion could be reduced if the current land use land cover scenario is considered. Keywords Conservation priority · Dijo watershed · Sediment yield · Soil erosion · Sub-watersheds · GIS · USLE · SLMP Abbreviations DEM Digital elevation model FAO Food and agricultural organization USLE Universal soil loss equation SCRP Soil conservation research program yr Year LULC Land use land cover ha Hectare WBISPP Woody biomass inventory and strategic planning project Electronic supplementary material The online version of this article (https ://doi.org/10.1007/s4080 8-020-01017-z) contains supplementary material, which is available to authorized users.
Forests in Mediterranean Europe including Portugal are highly susceptible to wildfires. Freshwaters are often exposed to post-wildfire contamination that contains several toxic substances, which may impose risk to freshwater organisms and ecosystem functions. However, knowledge on the impacts of post-wildfire runoffs from different origins on freshwater biota is scarce. In forest streams, invertebrate shredders have a major contribution to aquatic detrital-based food webs, by translocating energy and nutrients from plant-litter to higher trophic levels. We investigated the leaf consumption behaviour and the responses of oxidative and neuronal stress enzymatic biomarkers in the freshwater invertebrate shredder Allogamus ligonifer after short-term exposure (96 h) to post-wildfire runoff samples from Pinus and Eucalyptus plantation forests and stream water from a burnt catchment in Portugal. Chemical analyses indicated the presence of various metals and PAHs at considerable concentrations in all samples, although the levels were higher in the runoff samples from forests than in the stream water. The shredding activity was severely inhibited by exposure to increased concentrations of post-wildfire runoff samples from both forests. The dose-response patterns of enzymatic biomarkers suggest oxidative and neuronal stress in the shredders upon exposure to increasing concentrations of post-wildfire runoffs. The impacts were more pronounced for the runoffs from the burnt forests. Moreover, the response patterns suggest that the energy from the feeding activity of shredders might have contributed to alleviate the stress in A. ligonifer. Overall, the outcomes suggest that the post-wildfire contamination can induce sublethal effects on invertebrate shredders with impacts on key ecological processes in streams.
Government Regulation (GR) of Indonesia No. 4/2001 concerning Environmental Damage and/or Pollution Control related to Forest and/or Land Fire summarizes the general criteria for damage to soil properties, both on mineral and peat soil due to forest and or land fires. This GR focuses more on soils in its function as a planting medium and only lists the general criteria for qualitative soil damage, the value of which is only written as up or down without mentioning numbers. Soil has a buffering capacity and resilience capability, therefore, changes in soil properties are temporary. Soils has also chemical, physical and biological properties with a wide range of values. Soils that experiences a change in soil properties in a negative direction should be not referred as damaged soil, but degraded soil. The level of soil degradation (light, medium, heavy and very heavy) will be related to land suitability class and productivity level. Recovery costs can be then calculated from the costs required to procure ameliorant materials so that the productivity of the soil returns to its original state.
Increased fire pressure on forests and recent increase in human needs have lead to diverse outputs in forest ecosystem management strategies for the sake of sustainability of forests. Increase in CO2 releases and substantial greenhouse gases have created unexpected climatic events which are highly determinant on forest fires. The plant community composition tends to change its current distribution map and the terrains previously dominated with fire-susceptible species are transforming into a more ignitable plant composition. Concurrent conversion of plant community compartments is affecting the soil chemistry, biology, and water budget. The most common problems arising following fires are loss of organic matter by ignition, susceptibility to erosion, and evaporation of forms of C and N compounds. We hypothesized that fire as an important dominating factor in the Mediterranean ecosystems has lead to several changes: (I) adaptation of plant communities and dynamics has been fostered; (II) consecutive fires convert soil conditions which become less tolerant; (III) water-dependent competitions are more severe than earlier periods. As conclusion, the reactions of the ecosystem in total have become more vulnerable, more susceptible, within the shortened adaptation time.
Wildfire is a worldwide phenomenon that is expected to increase in extent and severity in the future, due to fuel accumulations, shifting land management practices, and climate change. It immediately affects the landscape by removing vegetation, depositing ash, influencing water-repellent soil formation, and physically weathering boulders and bedrock. These changes typically lead to increased erosion through sheetwash, rilling, dry ravel, and increased mass movement in the form of floods, debris flow, rockfall, and landslides. These process changes bring about landform changes as hillslopes are lowered and stream channels aggrade or incise at increased rates. Furthermore, development of alluvial fans, debris fans, and talus cones are enhanced. The window of disturbance to the landscape caused by wildfire is typically on the order of 3–4 years, with some effects persisting up to 30 years.
Understanding post-fire recovery is important for post-fire management. However, an in-depth evaluation of the spatiotemporal dynamics of burn degree is rarely reported around the world. This study aimed to assess the changes in the degree of burn during the early post-burn period (June 15, 2018–July 27, 2019) to influence the post-fire management. The dNBR-based burn index model was used to estimate the changes in burn degree. The results revealed that the burn degree had decreased from severe burns on June 15, 2018 to moderate burns on July 27, 2019, and the post-fire recovery period takes a long time. The rate of decrease in burn degree in the latter period (January 25, 2019–July 27, 2019) was much higher than that in the earlier period (June 15, 2018–January 25, 2019). The survival and growth of Dicranopteris pedata primarily led to a marked reduction in the burn degree in the latter period. The burned areas would have a markedly negative effect on the environment in the earlier period (within approximately half a year after the fire). Moreover, the lower severely burned sites can continue to degenerate and translated into higher ones during the earlier period owing to poor environmental conditions for the growth of vegetation and the influence of seasonal changes. These findings emphasize the importance of the timely strengthening of the earlier post-fire recovery in our area. In brief, our study enriches the knowledge of the early post-fire recovery in southeast China.
Forest is an important ecosystem service to human beings. In recent decades the forest is facing tremendous pressure from anthropogenic activities. One of the activities is the burning of forest floor for easy collection of non-timber forest produce. As a result of this number of incidences of forest fires has increased in the tribal-dominated area of the world. These forest fires have adverse impacts on soil properties which will ultimately in the long term have impacts on the forest ecosystem. Taking into consideration this fact this study was attempted to assess the impacts of controlled forest fires on the physicochemical properties of forest soil in the Gadchiroli forest circle of Central India. To assess the impacts six sampling sites from the forest where identified from the study area where no previous forest fire history was recorded in that season. Initial soil sampling before controlled forest fire was carried out in summer 2019 by quartering method in the topsoil layer (1-5 cm). A controlled forest fire was carried out in the same area. The soil was prepared for soil analysis and analysed by adopting standard methods for bulk density, water holding capacity, pH, electrical conductivity, organic carbon, and organic matter. Results revealed that forest fires increase the bulk density of soil, at 50% (n = 3) sampling locations water holding capacity got reduced down; whereas, at other half increased in capacity was observed. In the case of soil pH 66% (n = 4) sample reported increased in soil pH and at other reduction in soil pH was recorded. Except at one sampling location electrical conductivity was reduced. A similar trend was also noticed for organic carbon and organic matter. Bulk density and water holding capacity will have long term impacts; whereas, pH, electrical conductivity, organic carbon and organic matter will have short term impacts. Furthermore, in those sampling locations where forest fire does not occur in the last 2-3 years organic carbon and organic matter content of the soil is high. Thus, measures to be taken to reduce forest fires activities by incorporating an effective forest fire management system at a place by incorporating fire load management subsystem and fire suppression subsystem.
Wildfire plays a fundamental role in landscape evolution and the hydrologic and sediment regimes of the fluvial system. Wildfire accelerates rock weathering and alters hillslope soil properties, influencing infiltration, runoff, fluvial hydrology, hillslope and channel erosion, transport, and sedimentation. Morphodynamics and riparian habitat are changed as a result. Viewing post-wildfire processes within a fluvial systems framework highlights the variation of possible geomorphic responses. This view accommodates zones of overlapping processes with areal extents that may expand and contract over various temporal and spatial scales. Improved understanding of geomorphic responses to wildfires is a growing concern under climate variability and change.
Burn severity influences on post-fire recovery of soil-hydraulic properties controlling runoff generation are poorly understood despite the importance for parameterizing infiltration models. We measured soil-hydraulic properties of field-saturated hydraulic conductivity (Kfs), sorptivity (S), and wetting front potential (ψf) for four years after the 2013 Black Forest Fire, Colorado, USA, at six sites across a gradient of initial remotely sensed burn severity using the change in the normalized burn ratio (dNBR). These measurements were correlated with soil-physical property measurements of bulk density (ρb), loss on ignition (LOI, a measure of soil organic matter), and ground cover composition to provide insight into causal factors for temporal changes in Kfs, S, and ψf. Modeled infiltration using the Smith-Parlange approach parameterized with measured Kfs, S, and ψf further discerned the role of precipitation intensity on runoff generation.
Temporal trends of soil-physical properties and ground cover showed influences from initial burn severity. Trends in soil-hydraulic properties, surprisingly, were not strongly influenced by initial burn severity despite inferred effects of ρb, LOI, and ground cover on trends in Kfs and S. Calculations of dNBR at the time of sampling showed strong correlations with Kfs and S, demonstrating a new approach for estimating long-unburned Kfs and S values, infiltration model parameters after fire, and assessing the time of return to pre-fire values. Simulated infiltration-excess runoff, in contrast, did depend on initial burn severity. Time series of the ratio S²/Kfs ≈ ψf tended to converge between 1 and 10 mm four years after wildfire, potentially (i) defining a long-unburned forest domain of S²/Kfs and ψf from 1 to 10 mm with relatively high Kfs values, and (ii) providing a new post-fire soil-hydraulic property recovery metric (i.e. S²/Kfs ≈ ψf in the range of 1 to 10 mm) for sites in the Rocky Mountains of the USA.
Wildfires and associated wetting-induced slope stability issues (i.e., erosion, shallow landslides, and debris flows) are common problems all around the world. The water-retention mechanism of the burnt soil after a severe wildfire is adsorption followed by capillary condensation as saturation increases. During this time, soil is more susceptible to runoff-dominated erosion and associated debris flows. The water vapor sorption behavior of wildfire-burnt soil and wildfire ash is not fully known. This study investigates the evolution of water vapor sorption behavior of wildfire-burnt soil over a year and the impact of wildfire ash on the sorption behavior of burnt soil. Soil samples were collected from the surface and from 50-cm depth, and ash samples were collected from the surface at varying times after the 2019 Williams Flats Wildfire in Colville Indian Reservation, Washington State. Soil water retention curves of the surface soil and 50-cm soil were measured using a potentiometer. Hysteretic water vapor sorption isotherms were obtained along adsorption and desorption paths using a dynamic water vapor sorption analyzer. Several different parameters including maximum adsorbed water content, degree of hysteresis, specific surface area, and transition relative humidity were calculated from water vapor sorption isotherms and used to evaluate the sorption behavior of wildfire-burnt soil and wildfire ash. The results indicate that (1) wildfire ash is hydrophilic, has an active surface, and contributes to water retention; and (2) spatial redistribution of ash may result in fluctuations in the water retention of burnt soil over time.
The recent catastrophic wildfires near Melbourne in 2009 occurred during unprecedented extreme fire weather when dry northerly winds gusting up to 100 km/h coincided with the highest temperatures ever recorded in this region. These conditions, combined with the high fuel loads of mostly long-unburnt eucalypt forests, very low fuel moisture and steep topography, generated extreme burning conditions. Here we report on preliminary outcomes of a rapid response project, launched to determine heat input into the soils during burning, and associated effects on soil properties and seed bank survival. The data derived provides some insight into likely fire behaviour for this unusually extreme event. Three replicate sites each were sampled for extremely high burn severity and high burn severity, and four sites to represent long unburnt control terrain, within mature mixed-species eucalypt forests in April 2009 near Marysville, ~80 km NE of Melbourne. Additional exploratory sampling was carried out in 'rainforest'. Ash (where present) and surface soil (0-2.5 cm and 2.5-5 cm) were collected at 20 sample grid points at each site. Long-unburnt sites were sampled for fuel load and control soil. Samples analysis included carbon and metal content, particle size, water repellency and seed bank survival. Field and laboratory assessments suggest that heat input to the soil was less than might be supposed given the extreme fireline intensity of >70,000 kW/m estimated for this event. Our data indicate that soil temperatures in the top 0-2.5 cm did not exceed ~200ºC. The comparatively limited heating of the soil stands in stark contrast to the extreme fire intensity. Whilst this fire event has been extreme in many respects, the heat input into the ground, and the associated impacts, appear to have been limited. We speculate that this results from an unusually fast-moving fire front associated with the extreme wind speeds, causing a particularly short fire-residence time. Here we (i) present some of the data collected, (ii) discuss the factors that may have contributed to the limited heat penetration into the ground, and (iii) briefly explore the implications of the findings for future fire events that are anticipated under future climatic and land management conditions. The samples collected in this project are available to the scientific community for further investigation.
In this chapter, the physical properties of soils were determined after forest fires in pine forests near the city of Togliatti (Russia) in 2010. The aim of the study was to assess (1) what part organic matter of pyrogenic origin played in the formation of the fire-affected clay fraction and (2) the degree of hydrophobicity of the soil under the influence of pyrogenic exposure. The soil parameters studied were the particle size distribution, solid-phase density, specific surface area, contact angle of soil wetting, soil organic matter content and air-dry moisture. Two methods of particle size distribution were compared: laser diffraction and classical sedimentation methods. The sedimentation method revealed a higher clay content due to underestimation of the density and an increase in black carbon components, rather than an actual increase in very fine earth particles. This method enabled the effect of the pseudo-fraction to be observed, when particles of organic matter, including components of black carbon, partially form a clay fraction that was not there previously. While the set of methods proposed has proven suitable to assess changes in post-fire soils, there is a need to harmonise the methods of particle size distribution. The electrophysical profiling effectively identified the vertical heterogeneity of the soil layers. The contact angle of wetting showed an increase in hydrophobicity in the upper horizons of the soil after fires, especially crown fires. These expose soil to surface runoff and thus a higher risk of erosion. Further, deeper interdisciplinary research is needed to determine soil quality and degradation risks in fire-prone forest ecosystems.
In recent years, a problematic cycle of drought, forest fires, precipitation, and rain-induced debris flows has affected California, but limited research has been performed on how the underlying soil is potentially weakened after additional soil-like material (ash) is produced. Additionally, while a large amount of research has been performed on characterizing forest fire ash, fewer studies have been performed on geotechnical characteristics of soil/ash mixtures. This study focuses specifically on the characterization of ash samples from a brushfire and the large displacement and residual shear strength of ash/soil mixtures and pure ash, respectively. Two types of samples are tested: (i) brushfire ash samples collected from fire exposed areas and (iii) ash/soil mixtures of pure brushfire ash and laboratory sand. Characterization of ash indicated a silty sand grain size distribution with chemistries that were expected for ash derived from biomass. However, it was determined that carbon content is not equivalent to loss-on-ignition (LOI) for biomass materials with high calcium content. Direct shear testing of ash/soil mixtures indicated that large displacement strength behavior was governed by frictional resistance between sand particles until ash quantity reaches 10% by weight, at which point the friction angle decreased by an average of 2°. Additionally, the residual strength of normally-consolidated pure ash was high (above 30°), and the residual strength was reached at strains less than 1%.
Wildfires completely remove the vegetal cover, affect plant diversity and promote soil erosion in the forest ecosystems. Reforestation is essential to recover these important forest components, also in view of the forecasted climate change. Clear indications about suitable soil preparation techniques and a cautious choice of the planted species for successful reforestation actions are needed by forest managers. To improve this knowledge, this study, carried out seven years after a wildfire in a forest area of Central-Eastern Spain, evaluates: i) the short-term effectiveness of a post-fire reforestation work on growth and diversity of planted species, using ten types of shrubs and two soil preparation techniques (machinery planting spot, MPS, and linear subsoiling, LS); ii) the short-term effects of MPS and LS techniques on naturally regenerated plants. In the reforestation work, four of the ten planted species (Pistacia lentiscus L., O. europaea var. sylvestris L., Rhamnus lycioides L., Rosmarinus officinalis L.) showed the highest survival rate, while all individuals of E. fragilis Desf., Arbutus unedo L., Viburnum tinus L., and P. angustifolia L. were dead. Our results showed that P. lentiscus L. and O. europaea var. sylvestris were the species with the highest abundance in the soils treated with MPS and LS, respectively. In relation to naturally regenerated plants, higher number and height of plants were found in areas treated with LS. Both soil treatments influenced the plant diversity, although the species richness decreased in the treated soils compared to the burned and not treated areas. Overall, this study suggests that P. lentiscus appears as the most suitable reforestation species under the experimental conditions. Moreover, soil preparation is not ideal for reforestation after a wildfire, due to the lower regeneration, survival, and species richness found in treated plots in comparison to the burned and not treated areas.
This state-of-knowledge review about the effects of fire on soils and water can assist land and fire managers with information on the physical, chemical, and biological effects of fire needed to successfully conduct ecosystem management, and effectively inform others about the role and impacts of wildland fire. Chapter topics include the soil resource, soil physical properties and fire, soil chemistry effects, soil biology responses, the hydrologic cycle and water resources, water quality, aquatic biology, fire effects on wetland and riparian systems, fire effects models, and watershed rehabilitation.
In soil micromorphology most studies are done with light and electron microscopes on thin sections from selected samples. Information is obtained on nature, distribution, size, form, quantity, etc. of soil constituents and features. Significant data, not readily obtainable from thin sections, can be supplied by using sieve fractions. Amongst such data are specific soil structures (rounded macro-aggregates, micro-aggregates and coated plant fragments) which may, partly or wholly, have been made by soil biota.
After a century of fire suppression, dense forests in California have fueled high-severity fires. We surveyed mixed conifer forest with 995-1178 trees ha-1 (stems > 10 cm diameter at breast height), and nearby pine–oak woodland having 175-230 trees ha-1, 51 days after a severe burn, to contrast the spatial extent and properties of thermally altered soil at sites with different tree densities. Water-repellent soils were more extensive in forest than woodland. Deposits of white ash, composed largely of calicite, covered at most approximately 25% of the land surface, in places where large fuel items (e.g. logs, branches, exfoliated oak bark) had thoroughly combusted. At least 1690 kg ha-1 of CaCO3 in ash was deposited over the forest, and at least 700 kg ha-1 was added to the woodland. Combustion of logs and large branches also reddened the underlying yellow-brown soil as deep as 60 mm (average 8 mm), and over approximately 1-12% of the land surface. The reddened soils have magnetic susceptibilities that are three to seven times greater than surrounding unreddened soils within the burn, indicating thermal production of maghemite. Such fire-altered conditions persist over spatial and temporal scales that influence soil genesis in Mediterranean-type climate regions.
(1) Measurements were made of water infiltration, water retention and porosity of soils of burned and unburned plots of heathland. (2) On the burned plot the rate of infiltration was decreased by up to 74% compared to the unburned plot. (3) Moisture retention in the top soil of the burned plot was increased considerably compared to the unburned plot. (4) Mercury intrusion porosimetry (MIP) was used to investigate the porosity of the surface layers of soil following burning of the vegetation. An explanation of the results, based on the incorporation of ash particles, accords with the observed effects upon water infiltration and retention.
Needle cast from partially burnt conifer trees commonly occurs after
forest fires. The effectiveness of needles in reducing soil erosion was
investigated in this study. Two needle types, ponderosa pine and Douglas
fir needles, were used at four different cover amounts (0, 15, 40, and
70 percent) on granitic and volcanic derived soils. Simulated rainfall
was used to examine interrill erosion; added inflow was used to
determine rill erosion in a laboratory setting. After a series of
"runs," data showed that sediment delivery was greater for the granitic
soil compared with the volcanic soil. Douglas fir needles were more
effective at reducing interrill erosion compared with the ponderosa pine
needles. Ponderosa pine needles, because of their shape and being
bundled together, often caused minidebris dams to form. The minidebris
dams formed by ponderosa pine needles reduce flow within the rill,
resulting in less rill erosion than the Douglas fir needles. A 50
percent cover of Douglas fir needles reduced interrill erosion by 80
percent and rill erosion 20 by percent. A 50 percent cover of ponderosa
pine needles reduced interrill erosion by 60 percent and rill erosion by
40 percent. We also compared the effectiveness of using stream power,
rather than shear stress, to model rill erosion. Stream power was a
better predictor of sediment load than shear stress. Rill detachment
rates based on stream power decreased with increasing cover for both
needle types. These results challenge the use of shear stress detachment
rates in current erosion models and provide insight into the use of
stream power detachment rates.
Raindrop impact destroys the surface aggregates of soils and gradually
forms a continuous crust. Infiltration rates of bare soils are
determined by this process. A theoretical model presented previously was
tested under field conditions with a sandy loam soil. The effect of the
crust's structure was tested under three rainfall intensities and in
wetting and drying cycles. The results of the tests confirmed the
theoretical model. According to the model potential infiltration rates,
in bare soils, can be predicted by the equation It =
(Ii - If)
·e-γptl + If. The study
demonstrated quantitatively that the major factor determining the
reduction of infiltration rates is crust formation and not moisture
regime.
Observations of the results of erosion on hillslopes destabilized by fire were made over various periods up to 4.5 years in the Sydney Basin, Australia. On many sites a microrelief form of litter dams and microterraces were noted and the conditions favouring their formation identified. Litter dams formed during the first runoff event after the fire. In normal conditions they stabilized rapidly then slowly deteriorated over 3 or 4 years. A general model of litter dam and microterrace morphology and sedimentology is presented and their significance in the genesis of hillslope soils is discussed.
Thousands of hectares of wildlands are burned annually in the western United States. The composition and mineralogy of wood-ash produced by severe burning, and the changes in pH of soils underlying the ash, were examined at five sites in Califor-nia. Soil pH increased by as much as 3 pH units (to pH 10.5) immediately after burn-ing compared with unburned soil. Approx-imately 1 to 2% of each burn area was affected to a maximum observed depth of 20 cm. The major component of fresh, white wood-ash is calcite, while K and Na carbonates are present in minor amounts. The initial very high pH values of wood-ash and surface soil are caused by K and Na oxides, hydroxides, and carbonates. These compounds are very soluble and do not persist through the wet season. The calcite is much less soluble and was present in soils 3 years after burning, maintaining moderately alkaline pH in surface soils that are normally neutral to strongly acid.
(C) Williams & Wilkins 1993. All Rights Reserved.
Changes in overland flow and infiltration after a wildfire (summer 1989) in a typical Mediterranean scrubland were measured during the winters of 1990, 1991, 1992 and 1995 by means of simulated rainfall. Infiltration increases gradually from 1990 (sixth months after the forest fire) to 1995 (five and a half years after the forest fire). Overland flow decreases from 45% of rainfall after the forest fire to less than 6% five and a half years later. The reduction in overland flow was greatest in the first two years after the fire because of the quick recovery of vegetation. The steady-state infiltration capacity increased every year after the fire. Runoff and infiltration changes are mainly determined by the gradual recovery of vegetation. © 1998 John Wiley & Sons, Ltd.
Sandy soils are often water repellent when dry. In sloping areas this may result in surface runoff and erosion. Water repellency in soils can be classified with the solid-liquid contact angle which is difficult to determine. Another method is the water drop penetration time. This method is not only easier to apply but provides a more useful scale for classifying water repellent soils. Moreover, it is directly related to erosion hazard because runoff depends on the time required for the infiltration of rain drops. A close relationship was found between the contact angle and the water drop penetration time in dune soils along the coast of the Netherlands.
The conventional view of soil water repellency is that it promotes overland flow and soil erosion, but this is not always borne out by observations. This study aimed to isolate the effects of repellency on long-unburnt and recently burnt terrain on infiltration, overland flow and erosion at the small plot scale (0·36 m2). Rainfall simulations (30 min; intensity 100 mm h−1), using untreated water, and water treated with surfactants to eliminate repellency, were conducted on in situ repellent soils in fire-prone Eucalyptus globulus plantations, north-central Portugal at (i) a long-unburnt site with and without litter, and (ii) a recently burnt site. On long-unburnt terrain, the mean overland flow coefficient (33%) was 16 times higher and mean slopewash was 23 times higher under repellent compared with wettable conditions. On recently burnt terrain, no overland flow was recorded under wettable conditions, while under repellent conditions the mean coefficient was 70%. The water storage capacity of the litter layer under 10-year-old eucalyptus stands for dry antecedent conditions was at least 3 mm water depth per cm litter depth, implying at least a delay to the onset of overland flow. Severe repellency (36% ethanol) was found to persist through a 30-min storm (100 mm h−1) when a litter layer was present. A continuous wetting front was observed in the upper ∼1 cm of exposed soil, indicating a breakdown in repellency at the time of observation. Below ∼1 cm, repellent, dry soil conditions generally persisted through the simulated storm event. A major implication is that prediction of hydrological impacts of repellency must also take into account the infiltration characteristics of any litter layer and any non-repellent soils, if present. Copyright © 2007 John Wiley & Sons, Ltd.
Soil water repellency is generally thought to enhance runoff responses, thus representing a potentially important factor in hydrological modelling. Attempts to quantify its impacts have, however, either focused on soil profiles or plot scales and/or have been unable unequivocally to isolate repellency effects from other hydrologically important parameters. This research gap is addressed here by comparing responses of the same soil or terrain at a range of scales in highly repellent and wettable states, thereby limiting the impact of other variables. Hydrological responses of forest soils in north-central Portugal are assessed using laboratory wetting and rainfall simulation experiments at the point (0·002 m²) and microplot scales (0·12 m²), and field runoff responses from plot (16 m²) and catchment scales (0·33 km²).
Chemical and physical properties are important in the development of processes for the disposal and utilization of wood ash. Ash yield was seen to decrease by approximately 45% as the combustion temperature increased from 538 to 1093°C. Potassium, sodium, zinc and carbonate content decreased with temperature, whereas other metal ions remained constant or increased. Wood ash leachate contained 92% hydroxide and 8% carbonate. The rate of ash leaching was rapid in an orbital shaker, and approximately 60% of the total potassium and sodium dissolved. The total dissolved solids increased by 500% as the pH decreased from 13 to 5. The ash had an average particle size of 230 μm. Scanning electron micrographs showed large porous carbon particles and inorganic particles which reacted with water to form clusters of rosettes. X-ray diffraction patterns suggested that calcium silicate hydrate may be responsible for some of the swelling that occurs when ash and water react.
Wildfire can lead to considerable hydrological and geomorphological change, both directly by weathering bedrock surfaces and changing soil structure and properties, and indirectly through the effects of changes to the soil and vegetation on hydrological and geomorphological processes. This review summarizes current knowledge and identifies research gaps focusing particularly on the contribution of research from the Mediterranean Basin, Australia and South Africa over the last two decades or so to the state of knowledge mostly built on research carried out in the USA.
Mechanisms at the micro (patch) scale influencing runoff and erosion processes following a forest fire were investigated. The study was conducted in a Mediterranean mountainous region with a mean annual rainfall of 690 mm, Terra Rossa soil, and vegetation composed of a dense shrubland of Pinus halepensis and Quercus calliprinos. Simulated rainfall experiments were carried out on plots representing different intervals of time elapsed since a fire; i.e., immediately after fire, two weeks after fire, one year after fire. Unburned plots were also used for comparison. At a local scale, great variability was found whereby some patches produced high runoff and sediment yields following fire, while others did not. The conclusion is that the main effect of fires of low to moderate intensity is to produce a mosaic-like surface containing both rough patches in which there is almost no chance for runoff generation, and relatively smooth patches in which fire can subsequently lead to higher runoff and erosion rates.
Fire-induced or enhanced soil water repellency is often viewed as a key cause of the substantial increases in runoff and erosion following severe wildfires. In this study, the effects of different fire severities on soil water repellency are examined in eucalypt forest catchments in the Sandstone Tablelands near Sydney, burnt in 2001 and 2003. At sites affected by different fire severities and in long-unburnt control sites, repellency persistence was determined in situ and in the laboratory for surface and subsurface soil samples (n=846) using the Water Drop Penetration Time (WDPT) test. All long-unburnt samples were found to be water repellent, with severe to extreme persistence (>900 s) being dominant for surface (0–2.5 cm) and slight to moderate persistence (10–900 s) for subsurface (2.5–5 cm) soil, indicating naturally very high ‘background’ levels of repellency. In contrast to the generation or enhancement of repellency usually reported following forest fires of similar severity in previous studies, burning caused widespread destruction of repellency. The mineral soil depth to which repellency was destroyed (0.5–5 cm) was found to increase with burn severity. Below this charred wettable layer, persistence of pre-existing water repellency increased. Two years after the fire, the frequency of extreme repellency persistence was reduced in the surface and subsurface. However, recovery to pre-fire repellency levels had not been achieved.
This paper describes the heat transfer mechanisms operating as heat moves downward in the soil along steep temperature gradients during both wildfires and prescribed fires. The transfer of heat downward in the upper part of the soil is enhanced by the vaporization and movement of water and organic compounds. Available information on the changes in the chemistry of vaporized organic compounds is summarized and discussed. An operational theory describing the formation of a highly water repellent soil condition during fire is presented. The relationship between the formation of this fire-related watershed condition and subsequent surface runoff and erosion from wildland ecosystems is explored. Worldwide literature describing fire-induced water repellency is reviewed and summarized.
A rainfall simulator designed to perform experiments in rugged terrain is presented. The portability of the apparatus allows the researcher to work in remote areas and on steep slopes. Rainfall intensity and distribution within the plot (0.24 m2) and drop-size were measured under different water pressure. For the best simulated rainfall distribution (1.55 kg cm2 of water pressure and 55 mm h−1 of rain intensity) the drop velocity and the kinetic energy were measured.
Infiltration is the key process in the rainfall-runoff relationship. Little is known, however, about the seasonal and spatial variability, which is important for the behaviour of the slope surface geomorphological processes.The infiltration rates for contrasting slopes in southeast Spain have been measured by means of simulated rainfall and ponding. A north- and a south-facing slope were selected to analyze effects of aspect. The results show that aspect as well as slope position and vegetation cover determine the steady state infiltration rates.Moreover, seasonal changes play an important role in the soil hydrology. During summer the infiltration rates are high, no runoff is observed on vegetation covered soils. On the bare surfaces, runoff was only 10% of the rainfall. During the wet season, especially in autumn, the infiltration rates are lower, and runoff coefficients equal to 0.3. For the vegetated surfaces, runoff is negligible.Infiltration measurements by means of ponding and simulated rainfall are both suitable to study the infiltration process. In the present study, the infiltration rates measured by cylinder infiltrometer were 8 times greater than by rainfall simulation at 55 mm h−1.
This paper reports the results of a study on how fire effects water and sediment losses in the Central Spanish Pyrenees where land abandonment results in an increase of the scrubland and fire-affected surfaces. In 1991, two plots (control and burnt) were installed to collect runoff, suspended sediments and solutes. One of the plots was burnt (burnt-1) and the other was covered by shrubs and herbs (control). During 1993, another burnt plot was installed (burnt-2). Data was collected from the three plots until 1999 and is used as the basis for assessing the soil erosion changes after the fire. Runoff, solute and suspended sediment concentration and erosion rates were slightly greater during the first 2 years following fire on burnt-1 compared to the control plot. The average runoff coefficients during the 8-year study period were 4.2% and 7%, the total sediment concentrations were 189 and 181 mg l−1, and the erosion rates were 89 and 143 kg ha−1 year−1 for the control and burnt-1 plots, respectively. In contrast, burnt-2 plot responded differently than burnt-1 plot to fire, although these two plots were designed to be replicated treatments. The average runoff coefficient for burnt-2 plot was two times greater than that for the control plot. Likewise, total sediment concentration was 649 mg l−1 and erosion rate was 566 kg ha−1 year−1, which are 3.6 and 4.5 times greater than the control plot. Differences between burnt and control plots were analysed at hourly, daily, monthly and yearly temporal scale. Both burned plots began to recover after the fire. However, burnt-1 plot had a recovery time of 2 years compared to burnt-2 plot; while 7 years after the fire, the runoff sediment concentration and erosion rates from burnt-2 were higher than those for the control plot. Water and sediment losses from the two burnt plots were markedly different.
Effects of fire on soil: a state-of-knowledge
- C G Wells
- R E Campbell
- L F Debano
- C E Lewis
- R L Fredriksen
- E C Franklin
- R C Froelich
- P H Dunn
Wells, C.G., Campbell, R.E., DeBano, L.F., Lewis, C.E., Fredriksen, R.L., Franklin, E.C.,
Froelich, R.C., Dunn, P.H., 1979. Effects of fire on soil: a state-of-knowledge. General
Technical Report WO, vol. 7. United States Department of Agriculture, Forest
Service.
Erosional processes after wildfires: the impact of vegetative ash and the morphology of debris flows
- A Bookter
Bookter, A., 2006. Erosional processes after wildfires: the impact of vegetative ash and
the morphology of debris flows. M.S. Thesis, Department of Geology, University of
Montana, Missoula. Montana. 69 p.
submitted for publication. The effect of ash on runoff and erosion after a forest wildfire
- S W Woods
- V Balfour
Woods, S.W., Balfour, V., submitted for publication. The effect of ash on runoff and
erosion after a forest wildfire, Montana, U.S.A. International Journal of Wildland
Fire.
Precipitaciones máximas en España. Monografía 21, ICONA. Ministerio de Agricultura
- F Elias
- L Ruiz
Elias, F., Ruiz, L., 1979. Precipitaciones máximas en España. Monografía 21, ICONA.
Ministerio de Agricultura. 545 pp.
Effects of contrasting wildfire severity on soil wettability in Australian eucalypt catchments
- Doerr
Effects of fire on soil: a state-of-knowledge
- Wells