Naama Tessler

Soil water repellency persistence after recurrent forest fires on Mount Carmel, Israel

Variations in forest fires regime affect: (1) the natural patterns of community structure and vegetation; (2) the physico-chemical properties of soils and consequently (3) runoff, erosion and sediment yield. In recent decades the Mediterranean ecosystem of Mount Carmel, north-western Israel, is subjected to an increasing number of forest fires, thus, the objectives of the study were to evaluate the long-term effects of single and recurrent fires on soil water repellency (WR) and organic matter (OM) content. Water repellency was studied by applying water drop penetration time (WDPT) tests at sites burnt by single-fire, two fires, three fires and unburnt control sites. Water repellency in the burnt sites was significantly lower than in the unburnt control sites, and the soil maintained its wettability for more than 2 decades, whereas after recurrent fires, the rehabilitation was more complicated and protracted. The OM content was significantly lower after recurrent than after a single fire, causing a clear proportional decrease in WR. The rehabilitation of WR to natural values is highly dependent on restoration of organic matter and revegetation. Recurrent fires may cause a delay in recovery and reduced productivity of the soil for a long period.

Vegetation cover and species richness after recurrent forest fires in the Eastern Mediterranean ecosystem of Mount Carmel, Israel

Fire is a common disturbance in Mediterranean ecosystems, and can have a destructive, influential, and even essential, effect on vegetation and wildlife. In recent decades there has been a general increase in the number of fires in the Mediterranean Basin, including in Mount Carmel, Israel. The effects of recurrent forest fires on vegetation cover and species richness were determined in the spring of 2009 and 2010 by field surveys. The results of this study showed that the vegetation cover changes after recurrent forest fires, and can serve as a good indicator of the influence of fire and the resulting ecosystem rehabilitation. The dominant cover in most fire-damaged areas was composed of shrubs and dwarf-shrubs, especially Cistus salviifolius and Calicotome villosa. Tree cover was severely damaged after recurrent fires, and in those areas there was a drastic decrease of the total plant cover. Species richness increased mainly in the first decade after the recurrent fires, and decreased when the forest canopy began to close. Fire recurrence with short intervals (4-6years) between fires may lower the rehabilitated processes of the ecosystem and change its equilibrium.

Wildfires in the eastern Mediterranean as a result of lightning activity – a change in the conventional knowledge

No records exist in the scientific literature about lightning fires in the eastern Mediterranean (EM). Although thunderstorms are frequent in winter, if spontaneous fire is ignited, it will immediately be extinguished by rain. No thunderstorms occur in summer, and therefore no favourable weather conditions for natural ignitions exist. In October 2014, the synoptic conditions over the EM comprised a Red Sea Trough (RST) with an easterly axis (a less frequent version of this system). A convective storm, accompanied by thunderstorms with intense local rains developed rapidly. Simultaneously, six wildfires were reported from different locations in northern Israel (in the EM). Lightning activity documented by the Israel Electric Co. was at the same time and locations as the reported wildfires. To the best of our knowledge, this is the first case recorded in recent history of wildfires in the EM as a result of lightning. Moreover, in the literature, the RST is associated with fires only when its axis is in a western position, thus driving very hot and dry air masses. A different way of thinking is needed on the potential of lightning in autumn as a possible cause of fires under different situations of the RST.

Accelerated weathering of carbonate rocks following the 2010 wildfire on Mount Carmel, Israel

Massive destruction of carbonate rocks occurred on the slopes of Mount Carmel during the severe wildfire in 2010. The bedrock surfaces exhibited extensive exfoliation into flakes and spalls covering up to 80–100% of the exposed rocks; detached boulders were totally fractured or disintegrated. The fire affected six carbonate units – various types of chalk, limestone and dolomite. The burned flakes show a consistent tendency towards flatness, in all lithologies. The extent of the physical disruption depends on rock composition: the most severe response was found in the chalk formations covered by calcrete (Nari crusts). These rocks reacted by extreme exfoliation, at an average depth of 7.7 to 9.6 cm and a maximum depth of 20 cm. Scorched and blackened faces under the upper layer of spalls provide strong evidence that chalk breakdown took place at an early stage of the fire. It is possible to explain the extreme response of the chalks by the laminar structure of the Nari, which served as planes of weakness for the rock destruction. Three years after the fire, the rocks continue to exfoliate and break down internally. As the harder surface of the Nari deteriorates, the more brittle underlying chalk is exposed to erosion.

Erratum to: The Human and Physical Determinants of Wildfires and Burnt Areas in Israel

The original version of this article unfortunately contained a mistake. The small typos which related to unit conversion have been corrected in this erratum. And, the original article was also corrected. The correct information is given below 1. In the “Abstract” section, the fourth sentence should read as: We hypothesized that the physical and human factors explaining the spatial distribution of burnt areas derived from remote sensing (mostly large fires, >100 ha) will differ from those explaining site-based wildfires recorded by national agencies (mostly small fires,<10 ha). 2. In the “Results” section, under the heading “Spatial and Temporal Patterns of Wildfire”, the first sentence should read as: The GIS point dataset of wildfires was mostly composed of small wildfires (91 % smaller than 10 ha), with only six wildfires larger than 1000 ha (Table S1).