Fire risk assessment on the wildland–urban interface (WUI) and adjoined urban areas is crucial to... more Fire risk assessment on the wildland–urban interface (WUI) and adjoined urban areas is crucial to prevent human losses and structural damages. One of many interacting and dynamic factors influencing the structure and function of fire-prone ecosystems is vegetation ignitability, which plays a significant role in spreading fire. This study sought to identify areas with a high-level probability of ignition from time series multispectral images by designing a pattern recognition neural network (PRNN). The temporal behavior of six vegetation indices (VIs) before the considered wildfire event provided the input data for the PRNN. In total, we tested eight combinations of inputs for PRNN: the temporal behavior of each chosen VI, the temporal behavior of all indices together, and the values of VIs at specific dates selected based on factor analysis. The reference output data for training was a map of areas ignited in the wildfire. Among the considered inputs, the MSAVI dataset, which reflec...
River adjustment to an artificial disturbance is examined in the ephemeral mountainous stream-Nah... more River adjustment to an artificial disturbance is examined in the ephemeral mountainous stream-Nahal Oren, Mt. Carmel, Israel. We compare sedimentological and morphological characteristics of two sections, 50 and 500 m downstream of an artificial pond. Our results indicate that the deprivation of bed load floodwater in the upper section generates high calculated entrainment potentials as indicated by the large differences between measured and calculated D 50 which exceed 80%. Each flow produces an effective flow (Q > 0.125 m 3 s -1 ) of between 17 and 58% of the flood duration to entrain pebbles of the D 50 size (50 mm). In a large flow of 12m 3 s -1 (recurrence interval of 10 years), resulting bank erosion, in the upper section exceeded 4 tons per 20 m long section, whereas during the period 1999-2004 only minor degradation of <40 cm occurred at the lower section. The eroded material from the upper reach is loosely deposited, transported downstream and selectively deposited in...
Long-term environmental monitoring is addressed to identify physical and biological changes and p... more Long-term environmental monitoring is addressed to identify physical and biological changes and progresses taking place in the ecosystem. This basic action of landscape monitoring is an essential part of the systematic longterm surveillance, aiming to evaluate, assess and predict the spatial change and progresses. Indeed, it provides a context for wide range of diverse studies and research frameworks from regional or global scale. Spatial-temporal trends and changes at various scales (massive to less certain) require establishing consistent baseline data over time. One of the spatial cases of landscape monitoring is dedicated to soil formation and pedological progresses. It is previously acknowledged that changes in soil affect the functionality of the environment, so monitoring changes recently become important cause considerable resources in areas such as environmental management, sustainability services, and protecting the environment healthy. Given the above, it can be concluded...
Rainfall is the key factor to understand soil erosion processes, mechanisms, and rates. Most rese... more Rainfall is the key factor to understand soil erosion processes, mechanisms, and rates. Most research was conducted to determine rainfall characteristics and their relationship with soil erosion (erosivity) but there is little information about how atmospheric patterns control soil losses, and this is important to enable sustainable environmental planning and risk prevention. We investigated the temporal and spatial variability of the relationships of rainfall, runoff, and sediment yield with atmospheric patterns (weather types, WTs) in the western Mediterranean basin. For this purpose, we analyzed a large database of rainfall events collected between 1985 and 2015 in 46 experimental plots and catchments with the aim to: (i) evaluate seasonal differences in the contribution of rainfall, runoff, and sediment yield produced by the WTs; and (ii) to analyze the seasonal efficiency of the different WTs (relation frequency and magnitude) related to rainfall, runoff, and sediment yield. Th...
During 2–5 December 2010, an area of 2500ha in the Carmel forests was consumed by a severe wildfi... more During 2–5 December 2010, an area of 2500ha in the Carmel forests was consumed by a severe wildfire, causing soil erosion from the exposed slopes. Whereas most studies show that post-fire erosion rates tend to decline after the second year, in this case, we aim to address the ongoing consequences that different management practices had on soil erosion 3 and 4 years after a fire. Three management operations were applied: (a) preservation management (PM) – mulching wood chips on the burned area; (b) tree-clearing management (TCM) – burned trees were cut and removed; and (c) skid-trail formation (ST) – provisional pathways were formed while trees were dragged outside. Consequently, the objectives of the study were: (1) to monitor the effects of these post-fire practices 3 and 4 years after fire; and (2) to characterise the physical features of the eroded soil. The sediments were collected after every effective rain event over two rainy seasons (2013–14, 2014–15). TCM and ST practices r...
... T Bridge 25 V Beit Oren Ca rm el mo unt ai n Ein Alon V Nir Etzion T Ca rm el mountain 0 1 2 ... more ... T Bridge 25 V Beit Oren Ca rm el mo unt ai n Ein Alon V Nir Etzion T Ca rm el mountain 0 1 2 3 km Page 5. The Oren Bridge hydrometric station was active again since 1991. ... Carmel (Halfon 2004). However, a significant shortening of the rain season was documented. ...
Due to the challenges faced by resource managers in maintaining post-fire ecosystem health, there... more Due to the challenges faced by resource managers in maintaining post-fire ecosystem health, there is a need for methods to assess the ecological consequences of disturbances. This research examines an approach for assessing changes in post-fire vegetation dynamics for sites in Spain, Israel and the USA that burned in 1998, 1999 and 2002 respectively. Moderate Resolution Imaging Spectroradiometer satellite Normalized Difference Vegetation Index (NDVI) time-series data (2000–07) are used for all sites to characterise and track the seasonal and spatial changes in vegetation response. Post-fire trends and metrics for burned areas are evaluated and compared with unburned reference sites to account for the influence of local environmental conditions. Time-series data interpretation provides insights into climatic influences on the post-fire vegetation. Although only two sites show increases in post-fire vegetation, all sites show declines in heterogeneity across the site. The evaluation o...
Forestry management is crucial in mitigating erosion processes after extensive fires in Mediterra... more Forestry management is crucial in mitigating erosion processes after extensive fires in Mediterranean woodlands. Fire alters forest ecosystems, causing an increase in rates of geomorphic processes. The September 1989 fire in Mt. Carmel covered an area of 4 km2 in the main recreation area of a typical Mediterranean forest area. Six experimental plots, covering an area of 300-500 m(2) each, were established in order to determine the effect of forestry management practice on soil erosion after the fire; runoff and sediments were collected during and after each rainstorm. Rainfall was measured by two recorders and several rain gauges at the study site. During the first year following the fire, sediment yield was 100-500 times higher than on vegetated slopes. Sediment movement was increased mainly by the lack of vegetation. Results show that there is a clear trend of decrease in sediment yield between the first year and the next five. After this period the burnt areas recovered to simila...
... I remember having many small talks with Arnon about social geographical issues in Israel. Na&... more ... I remember having many small talks with Arnon about social geographical issues in Israel. Na'ama, I want to thank for the support in the research process and for showing me around in the beautiful Carmel Park and its surroundings. ...
ABSTRACT Soil water repellency (WR) is one of the properties most affected by combustion during a... more ABSTRACT Soil water repellency (WR) is one of the properties most affected by combustion during a forest fire. Different factors such as temperatures reached, type and amount of fuel, affect the changes observed in this property. Measurements of water repellency can be made directly in the field or in soil samples under laboratory conditions. On the other hand, previous laboratory findings have demonstrated that some soil properties can be key factors controlling the development of WR by burning. One of the objectives of this research was to confirm findings from laboratory-burning under wildfire field conditions. In summer 2008 WR was assessed in five areas recently affected by fires in Mt. Carmel (NW Israel) and Alicante (SE Spain). Study sites are quite similar with regard to vegetation and climate, the main difference between sites being the type of soil and therefore soil characteristics. In each one of the study areas WR was tested beneath Pinus halepensis in both burned and unburned (control) adjacent sites. WR test were conducted under field conditions in triplicate using the water drop penetration time (WDPT) test in the top of the A horizon. A total of 300 field measurements were done. Soil samples from the first 0–2.5 cm depth were also taken from the same microsites where WR was assessed for laboratory measurements. Estimations of temperatures reached in burned samples were also made using NIR models developed under laboratory conditions. In general terms, without distinguishing between areas, fire increased the frequency of occurrence of WR in af-fected soils. However, the magnitude of this effect was quite different depending on the studied area. Three of the study sites, showed very low WR values both in burned and unburned areas. The results are in agreement with those from our previous laboratory experiments (Arcenegui et al., 2007; Mataix-Solera et al., 2008), and are not explained as a consequence of different temperatures reached in the soils. Organic matter and clay content together with the mineralogy of the clay fraction seem to be responsible for the different soil behaviour. Although there is a correlation between field and laboratory WR data (R 2 = 0.549; P b 0.01), the comparison between field and laboratory measurements of WR showed differences, with higher values for the field data. Since the soil water content was very low when field measurements of WR were made – similar to air-dried samples in laboratory – this factor is not suspected to be the responsible. The observed differences could be explained however because the measurements in field were made on the soil surface, while in laboratory the measurements are made in disturbed samples taken from the top to some depth (in our case from 0 to 2.5 cm). Taking into account that soil WR is a property that can vary with depth probably diminishing in parallel with soil organic matter content, the results seem to be logical. Moreover, the disturbance of samples and the sieving could also be partly responsible for the observed differences.
Of the five classical factors of soil formation, climate, parent material, topography, time, orga... more Of the five classical factors of soil formation, climate, parent material, topography, time, organisms, and recently recognized human activity, it is the latter factor which discretely includes fire and post-burn impact. However, it is considered that soil undergoing fire just experience a temporary removal of the top organic horizon, thus slightly modified and often labeled as ’temporarily disturbed’ soil or soil ’under restoration/rehabilitation’. In fact the suggested seventh factor, post-burned produced ash, can act both dependently and independently of the other soil forming factors (Levin et al., 2013; Certini 2013). They are interdependent in cases where ash influences occur on time scales similar to ‘natural’ soil formation (Keesstra et ai., 2014) such as changes in vegetation. On the other hand, in post-fire areas a strong dependency is expected between soil–water retention mechanism, climate and topography.
Fire risk assessment on the wildland–urban interface (WUI) and adjoined urban areas is crucial to... more Fire risk assessment on the wildland–urban interface (WUI) and adjoined urban areas is crucial to prevent human losses and structural damages. One of many interacting and dynamic factors influencing the structure and function of fire-prone ecosystems is vegetation ignitability, which plays a significant role in spreading fire. This study sought to identify areas with a high-level probability of ignition from time series multispectral images by designing a pattern recognition neural network (PRNN). The temporal behavior of six vegetation indices (VIs) before the considered wildfire event provided the input data for the PRNN. In total, we tested eight combinations of inputs for PRNN: the temporal behavior of each chosen VI, the temporal behavior of all indices together, and the values of VIs at specific dates selected based on factor analysis. The reference output data for training was a map of areas ignited in the wildfire. Among the considered inputs, the MSAVI dataset, which reflec...
River adjustment to an artificial disturbance is examined in the ephemeral mountainous stream-Nah... more River adjustment to an artificial disturbance is examined in the ephemeral mountainous stream-Nahal Oren, Mt. Carmel, Israel. We compare sedimentological and morphological characteristics of two sections, 50 and 500 m downstream of an artificial pond. Our results indicate that the deprivation of bed load floodwater in the upper section generates high calculated entrainment potentials as indicated by the large differences between measured and calculated D 50 which exceed 80%. Each flow produces an effective flow (Q > 0.125 m 3 s -1 ) of between 17 and 58% of the flood duration to entrain pebbles of the D 50 size (50 mm). In a large flow of 12m 3 s -1 (recurrence interval of 10 years), resulting bank erosion, in the upper section exceeded 4 tons per 20 m long section, whereas during the period 1999-2004 only minor degradation of <40 cm occurred at the lower section. The eroded material from the upper reach is loosely deposited, transported downstream and selectively deposited in...
Long-term environmental monitoring is addressed to identify physical and biological changes and p... more Long-term environmental monitoring is addressed to identify physical and biological changes and progresses taking place in the ecosystem. This basic action of landscape monitoring is an essential part of the systematic longterm surveillance, aiming to evaluate, assess and predict the spatial change and progresses. Indeed, it provides a context for wide range of diverse studies and research frameworks from regional or global scale. Spatial-temporal trends and changes at various scales (massive to less certain) require establishing consistent baseline data over time. One of the spatial cases of landscape monitoring is dedicated to soil formation and pedological progresses. It is previously acknowledged that changes in soil affect the functionality of the environment, so monitoring changes recently become important cause considerable resources in areas such as environmental management, sustainability services, and protecting the environment healthy. Given the above, it can be concluded...
Rainfall is the key factor to understand soil erosion processes, mechanisms, and rates. Most rese... more Rainfall is the key factor to understand soil erosion processes, mechanisms, and rates. Most research was conducted to determine rainfall characteristics and their relationship with soil erosion (erosivity) but there is little information about how atmospheric patterns control soil losses, and this is important to enable sustainable environmental planning and risk prevention. We investigated the temporal and spatial variability of the relationships of rainfall, runoff, and sediment yield with atmospheric patterns (weather types, WTs) in the western Mediterranean basin. For this purpose, we analyzed a large database of rainfall events collected between 1985 and 2015 in 46 experimental plots and catchments with the aim to: (i) evaluate seasonal differences in the contribution of rainfall, runoff, and sediment yield produced by the WTs; and (ii) to analyze the seasonal efficiency of the different WTs (relation frequency and magnitude) related to rainfall, runoff, and sediment yield. Th...
During 2–5 December 2010, an area of 2500ha in the Carmel forests was consumed by a severe wildfi... more During 2–5 December 2010, an area of 2500ha in the Carmel forests was consumed by a severe wildfire, causing soil erosion from the exposed slopes. Whereas most studies show that post-fire erosion rates tend to decline after the second year, in this case, we aim to address the ongoing consequences that different management practices had on soil erosion 3 and 4 years after a fire. Three management operations were applied: (a) preservation management (PM) – mulching wood chips on the burned area; (b) tree-clearing management (TCM) – burned trees were cut and removed; and (c) skid-trail formation (ST) – provisional pathways were formed while trees were dragged outside. Consequently, the objectives of the study were: (1) to monitor the effects of these post-fire practices 3 and 4 years after fire; and (2) to characterise the physical features of the eroded soil. The sediments were collected after every effective rain event over two rainy seasons (2013–14, 2014–15). TCM and ST practices r...
... T Bridge 25 V Beit Oren Ca rm el mo unt ai n Ein Alon V Nir Etzion T Ca rm el mountain 0 1 2 ... more ... T Bridge 25 V Beit Oren Ca rm el mo unt ai n Ein Alon V Nir Etzion T Ca rm el mountain 0 1 2 3 km Page 5. The Oren Bridge hydrometric station was active again since 1991. ... Carmel (Halfon 2004). However, a significant shortening of the rain season was documented. ...
Due to the challenges faced by resource managers in maintaining post-fire ecosystem health, there... more Due to the challenges faced by resource managers in maintaining post-fire ecosystem health, there is a need for methods to assess the ecological consequences of disturbances. This research examines an approach for assessing changes in post-fire vegetation dynamics for sites in Spain, Israel and the USA that burned in 1998, 1999 and 2002 respectively. Moderate Resolution Imaging Spectroradiometer satellite Normalized Difference Vegetation Index (NDVI) time-series data (2000–07) are used for all sites to characterise and track the seasonal and spatial changes in vegetation response. Post-fire trends and metrics for burned areas are evaluated and compared with unburned reference sites to account for the influence of local environmental conditions. Time-series data interpretation provides insights into climatic influences on the post-fire vegetation. Although only two sites show increases in post-fire vegetation, all sites show declines in heterogeneity across the site. The evaluation o...
Forestry management is crucial in mitigating erosion processes after extensive fires in Mediterra... more Forestry management is crucial in mitigating erosion processes after extensive fires in Mediterranean woodlands. Fire alters forest ecosystems, causing an increase in rates of geomorphic processes. The September 1989 fire in Mt. Carmel covered an area of 4 km2 in the main recreation area of a typical Mediterranean forest area. Six experimental plots, covering an area of 300-500 m(2) each, were established in order to determine the effect of forestry management practice on soil erosion after the fire; runoff and sediments were collected during and after each rainstorm. Rainfall was measured by two recorders and several rain gauges at the study site. During the first year following the fire, sediment yield was 100-500 times higher than on vegetated slopes. Sediment movement was increased mainly by the lack of vegetation. Results show that there is a clear trend of decrease in sediment yield between the first year and the next five. After this period the burnt areas recovered to simila...
... I remember having many small talks with Arnon about social geographical issues in Israel. Na&... more ... I remember having many small talks with Arnon about social geographical issues in Israel. Na'ama, I want to thank for the support in the research process and for showing me around in the beautiful Carmel Park and its surroundings. ...
ABSTRACT Soil water repellency (WR) is one of the properties most affected by combustion during a... more ABSTRACT Soil water repellency (WR) is one of the properties most affected by combustion during a forest fire. Different factors such as temperatures reached, type and amount of fuel, affect the changes observed in this property. Measurements of water repellency can be made directly in the field or in soil samples under laboratory conditions. On the other hand, previous laboratory findings have demonstrated that some soil properties can be key factors controlling the development of WR by burning. One of the objectives of this research was to confirm findings from laboratory-burning under wildfire field conditions. In summer 2008 WR was assessed in five areas recently affected by fires in Mt. Carmel (NW Israel) and Alicante (SE Spain). Study sites are quite similar with regard to vegetation and climate, the main difference between sites being the type of soil and therefore soil characteristics. In each one of the study areas WR was tested beneath Pinus halepensis in both burned and unburned (control) adjacent sites. WR test were conducted under field conditions in triplicate using the water drop penetration time (WDPT) test in the top of the A horizon. A total of 300 field measurements were done. Soil samples from the first 0–2.5 cm depth were also taken from the same microsites where WR was assessed for laboratory measurements. Estimations of temperatures reached in burned samples were also made using NIR models developed under laboratory conditions. In general terms, without distinguishing between areas, fire increased the frequency of occurrence of WR in af-fected soils. However, the magnitude of this effect was quite different depending on the studied area. Three of the study sites, showed very low WR values both in burned and unburned areas. The results are in agreement with those from our previous laboratory experiments (Arcenegui et al., 2007; Mataix-Solera et al., 2008), and are not explained as a consequence of different temperatures reached in the soils. Organic matter and clay content together with the mineralogy of the clay fraction seem to be responsible for the different soil behaviour. Although there is a correlation between field and laboratory WR data (R 2 = 0.549; P b 0.01), the comparison between field and laboratory measurements of WR showed differences, with higher values for the field data. Since the soil water content was very low when field measurements of WR were made – similar to air-dried samples in laboratory – this factor is not suspected to be the responsible. The observed differences could be explained however because the measurements in field were made on the soil surface, while in laboratory the measurements are made in disturbed samples taken from the top to some depth (in our case from 0 to 2.5 cm). Taking into account that soil WR is a property that can vary with depth probably diminishing in parallel with soil organic matter content, the results seem to be logical. Moreover, the disturbance of samples and the sieving could also be partly responsible for the observed differences.
Of the five classical factors of soil formation, climate, parent material, topography, time, orga... more Of the five classical factors of soil formation, climate, parent material, topography, time, organisms, and recently recognized human activity, it is the latter factor which discretely includes fire and post-burn impact. However, it is considered that soil undergoing fire just experience a temporary removal of the top organic horizon, thus slightly modified and often labeled as ’temporarily disturbed’ soil or soil ’under restoration/rehabilitation’. In fact the suggested seventh factor, post-burned produced ash, can act both dependently and independently of the other soil forming factors (Levin et al., 2013; Certini 2013). They are interdependent in cases where ash influences occur on time scales similar to ‘natural’ soil formation (Keesstra et ai., 2014) such as changes in vegetation. On the other hand, in post-fire areas a strong dependency is expected between soil–water retention mechanism, climate and topography.
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