Modelling of wildfire impacts on catchment hydrology applied to two case studies

We used a conceptual modelling approach on two western Canadian mountainous catchments that were burned in separate wildfires in 2003 to explore the potential of using modelling approaches to generalize post‐wildfire catchment hydrology in cases where pre‐wildfire hydrologic data were present or absent. The Fishtrap Creek case study (McLure fire, British Columbia) had a single gauged catchment with both pre‐fire and post‐fire data, whereas the Lost Creek case study (Lost Ck. fire, Alberta) had several instrumented burned and reference catchments providing streamflows and climate data only for the post‐wildfire period. Wildfire impacts on catchment hydrology were assessed by comparing pre‐wildfire and post‐wildfire model calibrated parameter sets for Fishtrap Creek (Fishtrap Ck.) and the calibrated parameters of two burned (South York Ck. and Lynx Ck.) and two unburned (Star Ck. and North York Ck.) catchments for Lost Ck. Model predicted streamflows for burned catchments were compared with unburned catchments (pre‐fire in the case of Fishtrap Ck. and unburned in the case of the Lost Ck.). Similarly, model predicted streamflows from unburned catchments were compared with burned catchments (post‐fire in the case of Fishtrap Ck. and burned in the case of the Lost Ck.). For Fishtrap Ck., different model parameters and streamflow behaviour were observed for pre‐wildfire and post‐wildfire conditions. However, the burned and unburned model results from the Lost Ck. wildfire did not show differing streamflow responses to the wildfire. We found that this hydrological modelling approach is suitable where pre‐wildfire and post‐wildfire data are available but may provide limited additional insights where pre‐disturbance hydrologic data are unavailable. This may in part be because the conceptual modelling approach does not represent the physical catchment processes, whereas a physically based model may still provide insights into catchment hydrological response in these situations. Copyright © 2015 John Wiley & Sons, Ltd.     

Negligible soil erosion in a burned mountain watershed,Canadian Rockies: field and modelling investigations considering the role of duff

Increased soil erosion in immediate post‐wildfire years has been well documented in the literature, but many unanswered questions remain about the factors controlling erosional responses in different regional settings. The field site for the present study was located in a closed canopy, subalpine forest in Kootenay National Park, British Columbia that was subjected to a high‐intensity crown fire in the summer of 2003. Low soil erosion values were documented at the study site in the years immediately following the 2003 wildfire, with estimates ranging from approximately 10^‐1 up to 10⁰ t ha^‐1. Following the wildfire, notable duff coverage (the duff layer is the combined fermentation and humus soil organic layers) remained above the mineral soil. This finding supports earlier studies documenting only partial duff consumption by high‐intensity wildfires in the boreal forest of Canada. It is postulated that remnant duff coverage after many high‐intensity wildfires impacts the hydrological and soil erosional response to rainstorm events in post‐wildfire years. In particular, duff provides detention storage for infiltrating rainfall and, therefore, may inhibit the generation of overland flow. Furthermore, duff also provides a physical barrier to soil erosion. The Green–Ampt model of rainfall infiltration is employed to better assess how interactions between rainfall duration/intensity and soil/duff properties affect hydrological response and the generation of overland flow. Model results show that duff provides an effective zone for detention storage and that duff accommodates all rainfall intensities to which it was subjected without the occurrence of surface ponding. In addition, the penetration of the wetting front is relatively slow in duff due to its high porosity and water storage potential. Copyright © 2011 John Wiley & Sons, Ltd.     

Long-term hydrologic recovery after wildfire and post-fire forest management in the interior Pacific Northwest

Elevated wildfire activity in many regions in recent decades has increased concerns about the short- and long-term effects on water quantity, quality, and aquatic ecosystem health. Often, loss of canopy interception and transpiration, along with changes in soil structural properties, leads to elevated total annual water yields, peak flows, and low flows. Post-fire land management treatments are often used to promote forest regeneration and mitigate effects to terrestrial and aquatic ecosystems. However, few studies have investigated the longer-term effects of either wildfire or post-fire land management on catchment hydrology. Our objectives were to quantify and compare the short- and longer-term effects of both wildfire and post-fire forest management treatments on annual discharge, peak flows, low flows, and evapotranspiration (AET). We analyzed ten years of pre-fire data, along with post-fire data from 1 to 7 and 35 to 41 years after wildfire burned three experimental catchments in the Entiat Experimental Forest (EEF) in the Pacific Northwest, USA. After the fire, two of the catchments were salvage logged, aerially seeded, and fertilized, while the third catchment remained as a burned reference. We observed increases in annual discharge (150–202%), peak flows (234–283%), and low flows (42–81%), along with decreases in AET (34–45%), across all three study catchments in the first seven year period after the EEF wildfire. Comparatively, annual discharge, peak flows, lows flows, and AET had returned to pre-fire levels 35–41 years after the EEF fire in the two salvage logged and seeded catchments. Surprisingly, in the catchment that was burned but not actively managed, the annual discharge and runoff ratios remained elevated, while AET remained lower, during the period 35–41 years after the EEF fire. We posit that differences in long-term hydrologic recovery across catchments were driven by delayed vegetation recovery in the unmanaged catchment. Our study demonstrates that post-fire land management decisions have the potential to produce meaningful differences in the long-term recovery of catchment-scale ecohydrologic processes and streamflow.     

Delineating groundwater potential zones in a hard-rock terrain using geospatial tool

Abstract

Geospatial techniques have become one of the leading tools in the field of natural sciences for assessment, monitoring and management of natural resources, particularly in groundwater research. The paper discusses the demarcation and assessment of groundwater potential zones using geospatial techniques in the Deccan Volcanic Province of Maharashtra, India, using multi-criteria analyses. The study incorporates integration of thematic information (geomorphology, lithology, drainage density, slope and lineaments) in a GIS environment in order to identify groundwater potential zones. The methodology adopted can be used as a rapid assessment tool in groundwater exploration and is helpful in predictive groundwater resource management. Multi-criteria evaluation techniques were used to integrate all the thematic layers. Individual themes and their corresponding categories were assigned a knowledge base ranking from 1 to 5, depending on their importance for groundwater potential. Using the Raster calculator tool in Arc GIS software, all thematic maps were integrated to produce a composite groundwater potential map of the study area. The identified groundwater potential zones were classified into four classes, from excellent to poor. The generated groundwater potential zones were validated with field checks and borewell/dugwell yield data, and showed consistency with the observations.

Citation Singh, P., Thakur, J. K., and Kumar, S. (2013) Delineating groundwater potential zones in a hard-rock terrain using geospatial tools. Hydrological Sciences Journal, 58 (1), 1–11.     

地铁火灾风险性的多级可拓综合评估

为了弥补现有地铁火灾风险评估方法的不足,并为地铁的消防设计与管理提供量化指标,建立了以层次分析法（AHP）、专家调查法为基础,以可拓法为核心的地铁火灾风险的多级可拓评估方法,并给出了评估流程。对一地铁算例进行了评估,并根据评估结果得到地铁火灾风险的薄弱环节及管理重点。通过对比分析可知,本文方法与模糊评估方法所得的评估结果一致,从而表明：将可拓原理应用到地铁火灾风险性的评估中是合理可行的,很好地解决了地铁火灾风险评估的实际问题,本文方法可应用到相关的风险评估领域中。最后,对地铁火灾安全提出了一些建议。     

Integrating process‐based flow and temperature models to assess riparian forests and temperature amelioration in salmon streams

The importance of riparian tree cover in reducing energy inputs to streams is increasingly recognized in schemes to mitigate climate change effects and protect freshwater ecosystems. Assessing different riparian management strategies requires catchment‐scale understanding of how different planting scenarios would affect the stream energy balance, coupled with a quantitative assessment of spatial patterns of streamflow generation. Here, we use the physically based MIKE SHE model to integrate simulations of catchment‐scale run‐off generation and in‐stream hydraulics with a heat transfer model. This was calibrated to model the spatio‐temporal distribution of hourly stream water temperature during warm low flow periods in a Scottish salmon stream. The model was explored as a “proof of concept” for a tool to investigate the effects of riparian management on high stream water temperatures that could affect juvenile Atlantic salmon. Uncertainty was incorporated into the assessment using the generalized likelihood uncertainty estimation approach. Results showed that by decreasing both the warming (daylight hours) and the cooling (night‐time hours) rates, forest cover leads to a reduction of the temperature range (with a delay of the time to peak by up to 2 hr) and can therefore be effectively used to moderate projected climate change effects. The modelling presented here facilitated the quantification of potential mitigating effects of alternative riparian management strategies and provided a valuable tool that has potential to be utilized as an evidence base for catchment management guidance.     

GIS-based risk assessment of grassland fire disaster in western Jilin province, China

Grassland fire disasters have occurred frequently and adversely affected livestock agriculture and social-economic development greatly in the grassland regions of Jilin province, China. Moreover, both the frequency of grassland fire and loss from them are considered to be increasing with the global warming and economic development. This study presents a methodology for risk analysis and assessment of grassland fire disaster, taking western Jilin province as a case study area based on geographic information system (GIS). The composite grassland fire disaster risk index (GFDRI) combined the hazard of grassland fire, the exposure of the region, the vulnerability and emergency response and recovery capability for grassland fire disaster of the region were developed to assess and compare risk of grassland fire disaster in different counties in western Jilin province, China using the natural disaster risk index method (NDRIM), analytic hierarchy process (AHP) and weighted comprehensive method (WCM). Then, the risk degree of grassland fire disaster was assessed and regionalized in the western Jilin province, China based on GFDRI by using GIS. It is shown that the most places of western Jilin province were in mediate risk. Zhenlai, Tongyu were in heavy risk. Taobei, Ningjiang, Fuyu were in light risk. The information obtained from interviewing the district official committees in relation to result compiled was statistically evaluated. The GFDRI was developed to be an easily understandable tool that can be used to assess and compare the relative risk of grassland fire disaster in different counties in t western Jilin province, China, and to compare the different relative contributions of various factors, e.g., frequency of grassland fire and quality of emergency evacuation plan. The GFDRI is specifically intend to support local and national government agencies of grassland fire disaster management as they (1) make resource allocation decisions; (2) make high-level planning decisions; and (3) raise public awareness of grassland fire disaster risk, its causes, and ways to manage it.     

Hydrological impact of forest-fire from paired-catchment and rainfall–runoff modelling perspectives

Abstract

This study deals with the Rimbaud catchment, a sub-catchment within the Réal Collobrier hydrological observatory in southeastern France, managed by Irstea since 1966. This observatory suffered a wildfire in 1990. Because of the dense network of streamgauges and raingauges available, this site provides a unique opportunity to test and compare two types of analysis, one based on paired catchments and the other a rainfall–runoff model, used to assess the hydrological impact of forest fire. In the present case, more than 20 years of pre-fire and post-fire data are available. We compare the ability of the two approaches to detect gradual changes at a daily time step. This case study illustrates how natural climatic variability (here a long drought which preceded the wildfire) can make the identification of hydrological changes extremely difficult.     

Effect of storms during drought on post‐wildfire recovery of channel sediment dynamics and habitat in the southern California chaparral,USA

Current global warming projections suggest a possible increase in wildfire and drought, augmenting the need to understand how drought following wildfire affects the recovery of stream channels in relation to sediment dynamics. We investigated post‐wildfire geomorphic responses caused by storms during a prolonged drought following the 2013 Springs Fire in southern California (USA), using multi‐temporal terrestrial laser scanning and detailed field measurements. After the fire, a dry‐season dry‐ravel sediment pulse contributed sand and small gravel to hillslope‐channel margins in Big Sycamore Creek and its tributaries. A small storm in WY 2014 generated sufficient flow to mobilize a portion of the sediment derived from the dry‐ravel pulse and deposited the fine sediment in the channel, totaling ~0.60 m³/m of volume per unit length of channel. The sediment deposit buried step‐pool habitat structure and reduced roughness by over 90%. These changes altered sediment transport characteristics of the bed material present before and after the storm; the ratio of available to critical shear stress (τ_o/τ_c) increased by five times. Storms during WY 2015 contributed additional fine sediment from tributaries and lower hillslopes and hyperconcentrated flow transported and deposited additional sediment in the channel. Together these sources delivered sediment on the order of six times that in 2014, further increasing τ_o/τ_c. These storms during multi‐year drought following wildfire transformed channel dynamics. The increased sediment transport capacity persisted during the drought period characterized by the longer residence time of relatively fine‐grained post‐fire channel sedimentation. This contrasts with wetter years, when post‐fire sediment is transported from the fluvial system during the same season as the post‐fire sediment pulse. Results of this short‐term study highlight the complex and substantial effects of multi‐year drought on geomorphic responses following wildfire. These responses influence pool habitat that is critical to longer‐term post‐wildfire riparian ecosystem recovery. Copyright © 2017 John Wiley & Sons, Ltd.     

Regional patterns of postwildfire streamflow response in the Western United States: The importance of scale‐specific connectivity

Wildfires can impact streamflow by modifying net precipitation, infiltration, evapotranspiration, snowmelt, and hillslope run‐off pathways. Regional differences in fire trends and postwildfire streamflow responses across the conterminous United States have spurred concerns about the impact on streamflow in forests that serve as water resource areas. This is notably the case for the Western United States, where fire activity and burn severity have increased in conjunction with climate change and increased forest density due to human fire suppression. In this review, we discuss the effects of wildfire on hydrological processes with a special focus on regional differences in postwildfire streamflow responses in forests. Postwildfire peak flows and annual water yields are generally higher in regions with a Mediterranean or semi‐arid climate (Southern California and the Southwest) compared to the highlands (Rocky Mountains and the Pacific Northwest), where fire‐induced changes in hydraulic connectivity along the hillslope results in the delivery of more water, more rapidly to streams. No clear streamflow response patterns have been identified in the humid subtropical Southeastern United States, where most fires are prescribed fires with a low burn severity, and more research is needed in that region. Improved assessment of postwildfire streamflow relies on quantitative spatial knowledge of landscape variables such as prestorm soil moisture, burn severity and correlations with soil surface sealing, water repellency, and ash deposition. The latest studies furthermore emphasize that understanding the effects of hydrological processes on postwildfire dynamic hydraulic connectivity, notably at the hillslope and watershed scales, and the relationship between overlapping disturbances including those other than wildfire is necessary for the development of risk assessment tools.     

Wildfire and earth surface processes

Wildfire is a landscape-scale disturbance that changes the rate and magnitude of many earth surface processes. The impacts of fire on earth surface processes can vary substantially from place to place depending on a variety of site-specific conditions, including topography, fire severity, regional climate, vegetation type, and soil type. This variation makes it critical to bring together scientists studying fire and earth surface processes from different perspectives and in different parts of the world. This special issue pulls together studies that present cutting-edge research addressing the geomorphic and hydrologic impacts of wildfire across a range of spatial and temporal scales, including advances in managing some of the negative, short-term effects of wildfire. Contributions to this collection cover the following themes: insights from field measurements, sediment and carbon redistribution, insights from process-based modeling, post-fire debris flows, and post-fire mitigation. The work presented in this special issue will help to advance the capabilities of scientists and land managers to observe, simulate, and anticipate changes to earth surface processes following fire.     

An analytical solution for rapidly predicting post-fire peak streamflow for small watersheds in southern California

Following wildfires, the probability of flooding and debris flows increase, posing risks to human lives, downstream communities, infrastructure, and ecosystems. In southern California (USA), the Rowe, Countryman, and Storey (RCS) 1949 methodology is an empirical method that is used to rapidly estimate post-fire peak streamflow. We re-evaluated the accuracy of RCS for 33 watersheds under current conditions. Pre-fire peak streamflow prediction performance was low, where the average R² was 0.29 and average RMSE was 1.10 cms/km² for the 2- and 10-year recurrence interval events, respectively. Post-fire, RCS performance was also low, with an average R² of 0.26 and RMSE of 15.77 cms/km² for the 2- and 10-year events. We demonstrated that RCS overgeneralizes watershed processes and does not adequately represent the spatial and temporal variability in systems affected by wildfire and extreme weather events and often underpredicted peak streamflow without sediment bulking factors. A novel application of machine learning was used to identify critical watershed characteristics including local physiography, land cover, geology, slope, aspect, rainfall intensity, and soil burn severity, resulting in two random forest models with 45 and five parameters (RF-45 and RF-5, respectively) to predict post-fire peak streamflow. RF-45 and RF-5 performed better than the RCS method; however, they demonstrated the importance and reliance on data availability. The important parameters identified by the machine learning techniques were used to create a three-dimensional polynomial function to calculate post-fire peak streamflow in small catchments in southern California during the first year after fire (R² = 0.82; RMSE = 6.59 cms/km²) which can be used as an interim tool by post-fire risk assessment teams. We conclude that a significant increase in data collection of high temporal and spatial resolution rainfall intensity, streamflow, and sediment loading in channels will help to guide future model development to quantify post-fire flood risk.     

Initial hydrologic and geomorphic response following a wildfire in the Colorado Front Range

A wildfire in May 1996 burned 4690 hectares in two watersheds forested by ponderosa pine and Douglas fir in a steep, mountainous landscape with a summer, convective thunderstorm precipitation regime. The wildfire lowered the erosion threshold in the watersheds, and consequently amplified the subsequent erosional response to shorter time interval episodic rainfall and created both erosional and depositional features in a complex pattern throughout the watersheds. The initial response during the first four years was an increase in runoff and erosion rates followed by decreases toward pre‐fire rates. The maximum unit‐area peak discharge was 24 m³ s^?1 km^?2 for a rainstorm in 1996 with a rain intensity of 90 mm h^?1. Recovery to pre‐fire conditions seems to have occurred by 2000 because for a maximum 30‐min rainfall intensity of 50 mm h^?1, the unit‐area peak discharge in 1997 was 6.6 m³ s^?1 km^?2, while in 2000 a similar intensity produced only 0.11 m³ s^?1 km^?2. Rill erosion accounted for 6 per cent, interrill erosion for 14 per cent, and drainage erosion for 80 per cent of the initial erosion in 1996. This represents about a 200‐fold increase in erosion rates on hillslopes which had a recovery or relaxation time of about three years. About 67 per cent of the initially eroded sediment is still stored in the watersheds after four years with an estimated residence time greater than 300 years. This residence time is much greater than the fire recurrence interval so erosional and depositional features may become legacies from the wildfire and may affect landscape evolution by acting as a new set of initial conditions for subsequent wildfire and flood sequences. Published in 2001 by John Wiley & Sons, Ltd.     

Post-earthquake estimates of different ground motion intensity measures for the 2012 Emilia earthquake

Estimates of the earthquake ground motion intensity over a geographical area have multiple uses, that is, emergency management, civil protection and seismic fragility assessment. In particular, with reference to fragility assessment, it is of interest to have estimates of the values of different ground-motion intensity measures in order to correlate them with the observed damage. To this purpose, the present paper uses a procedure recently proposed in the literature to estimate the ground-motion intensity for the 2012 Emilia mainshocks, considering different ground motion intensity measures and directionality effects. Ground motion prediction equations based on different site effect models, and spatial correlation models are calibrated for the Emilia earthquakes. The paper discusses the accuracy of the shakemaps obtained using the different soil effect models considered and presents the obtained shakemaps as supplementary material. The procedure presented in the paper is aimed at providing ground motion intensity values for seismic fragility assessment and is not intended as a tool to estimate shakemaps for rapid emergency assessment.     

Impacts of successive wildfire on soil hydraulic properties: Implications for debris flow hazards and system resilience

Climate and land use changes have led to recent increases in fire size, severity, and/or frequency in many different geographic regions and ecozones. Most post-wildfire geomorphology studies focus on the impact of a single wildfire but changing wildfire regimes underscore the need to quantify the effects of repeated disturbance by wildfire and the subsequent impacts on system resilience. Here, we examine the impact of two successive wildfires on soil hydraulic properties and debris flow hazards. The 2004 Nuttall-Gibson Complex and the 2017 Frye Fire affected large portions of the Pinaleño Mountains in southern Arizona, creating a mosaic of burn severity patterns that allowed us to quantify differences in wildfire-induced hydrologic changes as a function of burn severity and recent fire history (i.e. burned in only the Frye Fire or burned in both fires). Field observations after the 2017 Frye Fire indicated debris flow activity in areas burned predominantly at low severity. Many of these areas, however, were also affected by the 2004 Nuttall-Gibson Complex, suggesting that the relatively short recovery time between the two wildfires may have played a role in the geomorphic response to the most recent wildfire. Field measurements of soil hydraulic properties suggest that soils burned at moderate severity in 2004 and low severity in 2017 have a lower infiltration capacity relative to those that remained unburned in 2004 and burned at low severity in 2017. Simulations of runoff demonstrate that measured differences in infiltration capacity between once- and twice-burned soils are sufficient in some cases to influence the rainfall intensities needed to initiate runoff generated debris flows. Results quantify the impact of wildfire history and burn severity on runoff and debris flow activity in a landscape affected by successive wildfires and provide insight into how the resilience of geomorphic systems may be affected by successive wildfires. © 2019 John Wiley & Sons, Ltd.     

Modelling surface runoff to evaluate the effects of wildfires in multiple semi‐arid,shrubland‐dominated catchments

Wildfires change the infiltration properties of soil, reduce the amount of interception and result in increased runoff. A wildfire at Northeast Attica, Central Greece, in August 2009, destroyed approximately one third of a study area consisting of a mixture of shrublands, pastures and pines. The present study simultaneously models multiple semi‐arid, shrubland‐dominated Mediterranean catchments and assesses the hydrological response (mean annual and monthly runoff and runoff coefficients) during the first few years following wildfires. A physically based, hydrological model (MIKE SHE) was chosen. Calibration and validation results of mean monthly discharge presented very good agreement with the observed data for the pre‐wildfire and post‐wildfire period for two subcatchments (Nash–Sutcliffe Efficiency coefficient of 79.7%). The model was then used to assess the pre‐wildfire and post‐wildfire runoff responses for each of seven catchments in the study area. Mean annual surface runoff increased for the first year and after the second year following the wildfires increased by 112% and 166%, respectively. These values are within the range observed in similar cases of monitored sites. This modelling approach may provide a way of prioritizing catchment selection with respect to post‐fire remediation activities. Additionally, this modelling assessment methodology would be valuable to other semi‐arid areas because it provides an important means for comprehensively assessing post‐wildfire response over large regions and therefore attempts to address some of the scaled issues in the specific literature field of research. Copyright © 2015 John Wiley & Sons, Ltd.     

What is wrong with post-fire soil erosion modelling? A meta-analysis on current approaches,research gaps,and future directions

In the near future, a higher occurrence of wildfires is expected due to climate change, carrying social, environmental, and economic implications. Such impacts are often associated with an increase of post-fire hydrological and erosive responses, which are difficult to predict. Soil erosion models have been proven to be a valuable tool in the decision-making process, from emergency response to long-term planning, however, they were not designed for post-fire conditions, so need to be adapted to include fire-induced changes. In recent years, there have been an increasing number of studies testing different models and adaptations for the prediction of post-fire soil erosion. However, many of these adaptations are being applied without field validation or model performance assessment. Therefore, this study aims to describe the scientific advances in the last 20 years in post-fire soil erosion modelling research and evaluate model adaptations to burned areas that aim to include: (i) fire-induced changes in soil and ground cover; (ii) fire-induced changes in infiltration; (iii) burn severity; and (iv) mitigation measures in their predictions. This study also discusses the strengths and weaknesses of these approaches, suggests potential improvements, and identifies directions for future research. Results show that studies are not homogeneously distributed worldwide, according to the model type used or by region most affected by wildfire. During calibration, 73% of cases involved model adaptation to burned conditions, and only 21% attempted to accommodate new processes. Burn severity was addressed in 75% of cases, whilst mitigation measures were simulated in 27%. Additionally, only a minor percentage of model predictions were validated with independent field data (17%) or assessed for uncertainties (13%). Therefore, further efforts are required in the adaptation of erosion models to burned conditions, to be widely used for post-fire management decisions. © 2020 John Wiley & Sons, Ltd.     

Hydrological resilience to forest fire in the subarctic Canadian shield

Understanding the role of forest fires on water budgets of subarctic Precambrian Shield catchments is important because of growing evidence that fire activity is increasing. Most research has focused on assessing impacts on individual landscape units, so it is unclear how changes manifest at the catchment scale enough to alter water budgets. The objective of this study was to determine the water budget impact of a forest fire that partially burned a ~450 km² subarctic Precambrian Shield basin. Water budget components were measured in a pair of catchments: one burnt and another unburnt. Burnt and unburnt areas had comparable net radiation, but thaw was deeper in burned areas. There were deeper snow packs in burns. Differences in streamflow between the catchments were within measurement uncertainty. Enhanced winter streamflow from the burned watershed was evident by icing growth at the streamflow gauge location, which was not observed in the unburned catchment. Wintertime water chemistry was also clearly elevated in dissolved organics, and organic-associated nutrients. Application of a framework to assess hydrological resilience of watersheds to wildfire reveal that watersheds with both high bedrock and open water fractions are more resilient to hydrological change after fire in the subarctic shield, and resilience decreases with increasingly climatically wet conditions. This suggests significant changes in runoff magnitude, timing and water chemistry of many Shield catchments following wildfire depend on pre-fire land cover distribution, the extent of the wildfire and climatic conditions that follow the fire.     

Disturbance,geomorphic processes and recovery of wildfire slopes in North Tyrol

Wildfires in the sub‐alpine belt of the Austrian Limestone Alps sometimes cause severe vegetation and soil destruction with increased danger of secondary natural hazards such as avalanches and debris flows. Some of the affected areas remain degraded to rocky slopes even decades after the fire, raising the question as to whether the ecosystems will ever be able to recover. The mean fire interval, the duration of recovery and the role of geomorphic processes for vegetation regeneration are so far unknown. These questions were tackled in a broad research approach including investigation of historical archives to determine the frequency of historical wildfires, mapping vegetation regeneration on 20 slopes of different post‐fire ages, and soil erosion measurements on two slopes. To date, > 450 historical wildfires have been located in the study area. The mean fire interval per square kilometre is c. 750 years, but can be as low as 200–500 years on south‐facing slopes. Vegetation regeneration takes an extremely long time under unfavourable conditions; the typical window of disturbance is between 50 and 500 years, which is far longer than in any other wildfire study known to us. Soil erosion constantly increases in the years after the fires and the elevated intensity can be maintained for decades. A two‐part vegetation regeneration model is proposed depending upon the degree of soil loss. In the case of moderate soil erosion, spreading grassland communities can slow down shrub re‐colonization. In contrast, after severe soil destruction the slopes may remain degraded for a century or longer, before rather rapid regeneration occurs. The reasons are not fully understood but are probably governed by geomorphic process intensity. The interdependence of vegetation regeneration and geomorphic processes is a paradigm of ecology–geomorphology interaction, and is a unique example of a very long‐lasting disturbance response caused by wildfire in a non‐resilient ecosystem. Copyright © 2012 John Wiley & Sons, Ltd.     

How geomorphic context governs the influence of wildfire on floodplain organic carbon in fire-prone environments of the western United States

We draw on published studies of floodplain organic carbon storage, wildfire-related effects on floodplains in temperate and high latitudes, and case studies to propose a conceptual model of the effects of wildfire on floodplain organic carbon storage in relation to climate and valley geometry. Soil organic carbon typically constitutes the largest carbon stock in floodplains in fire-prone regions, although downed wood can contain significant organic carbon. We focus on the influence of wildfire on soil organic carbon and downed wood as opposed to standing vegetation to emphasize the geomorphic influences resulting from wildfire on floodplain organic carbon stocks. The net effect of wildfire varies depending on site-specific characteristics including climate and valley geometry. Wildfire is likely to reduce carbon stock in steep, confined valley segments because increased water and sediment yields following fire create net floodplain erosion. The net effect of fire in partly confined valleys depends on site-specific interactions among floodplain aggradation and erosion, and, in high-latitude regions, permafrost degradation. In unconfined valleys in temperate latitudes, wildfire is likely to slightly increase floodplain organic carbon stock as a result of floodplain aggradation and wood deposition. In unconfined valleys in high latitudes underlain by permafrost, wildfire is likely in the short-term to significantly decrease floodplain organic carbon via permafrost degradation and reduce organic-layer thickness. Permafrost degradation reduces floodplain erosional resistance, leading to enhanced stream bank erosion and greater carbon fluxes into channels. The implications of warming climate and increased wildfires for floodplain organic carbon stock thus vary. Increasing wildfire extent, frequency, and severity may result in significant redistribution of organic carbon from floodplains to the atmosphere via combustion in all environments examined here, as well as redistribution from upper to lower portions of watersheds in the temperate zone and from floodplains to the oceans via riverine transport in the high-latitudes. © 2019 John Wiley & Sons, Ltd.