Pua Kutiel

The effect of fire on nutrients in a pine forest soil

The effect of a hot summer fire on soil nutrient contents in the upper 2 cm of Aleppo pine forest with a dense woody understory was studied from September 1985 to May 1986.In comparison with the adjacent unburned forest, total nitrogen decreased by 25% but available forms of nitrogen were much higher. In burned and unburned soils there was a similar trend to increase and decrease in NH4+−N, However, while (NO2−+NO3−−N decreased in the unburned soil it rose rapidly in the burned ash soil. Total phosphorus increased by 300% after the fire but decreased again 2 months later. Also water-soluble P increased up to November and then decreased to the levels of the unburned soils. The same was true for electrical conductivity and pH, increasing immediately after the fire and then leveling off again.This increase in nutrient levels in the “ash soil” was reflected in the striking increase in shoot and root biomass and in the content of N, P, Mg, K, Ca, Zn and Fe in wheat and clover plants grown in pots in these soils. These nutrient levels were much higher in the wheat plants, which also produced 12 times more seeds in the “ash soil.”It seems that fire in these pine forests causes a short-term flush of the mineral elements in the upper “ash soil” layer which is reverted gradually via the herbaceous post-fire to the ecosystem.

Effect of surface roughness on runoff and erosion in a mediterranean ecosystem: the role of fire

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 impacts on soil nutrients and soil erosion in a Mediterranean pine forest plantation

Summary Detailed measurements of soil nutrients, runoff and sediment discharge were made in two plots about 200 m 2 each in a plantation of Aleppo and Brutia pine in the Mediterranean climatic region of Israel. One of the plots was affected by a moderate wildfire at the end of summer 1988. The soil nutrient content in the burnt plot was increased significantly. Runoff and erosion rates were low in both plots. However, on the burnt plot they were lower than on the unburnt plot, due to increased infiltration capacity. These results suggest that light and moderate forest fires may increase soil fertility without causing a marked difference in soil runoff and erosion.

Vegetation establishment on the southern Israeli coastal sand dunes between the years 1965 and 1999

Abstract Since 1960, the Israeli coastal dunes have undergone a stabilization process that is manifested in the increase of vegetation cover and in a decrease in the abundance of sand-living flora and fauna species. The objective of the study was to quantify, using remote sensing and GIS, the rate and extent of vegetation expansion and their resultant temporal changes on Israel’s southern coastal dunes between the years 1965 and 1999. The results indicate that during the entire study period, the vegetation-covered area grew by 82% at an annual average growth rate of 1.75%. Concurrently, the bare shifting dune area decreased by 37% at an annual average growth rate of 1.34%. The conspicuous trend over the period studied, despite regressive processes, is a transition from bare shifting dunes to stabilized, vegetation-covered dunes. The extrapolation of the results, assuming continuation of processes and no destruction effects, indicates that with the decrease in the bare shifting dunes, the ratio of bare shifting dunes and sparse vegetation coverage landscape will equalize by between 2007 and 2010. According to this extrapolation, between 2012 and 2015, no bare shifting dune landscape will remain, and the study area will be covered with sparse- and dense-level vegetation cover. Beginning in 2035, the entire study area will be covered in vegetation whose density will be between 60 and 100%. Meso-climate and land use changes are among the factors that might explain this phenomenon.

The effect of fire-induced surface heterogeneity on rainfall-runoff-erosion relationships in an eastern Mediterranean ecosystem, Israel

Abstract The effect of forest fire on rainfall-runoff-erosion relationships at the micro-scale (plot) and at the meso-scale (hillslope) were studied in a Mediterranean mountainous region near Haifa, Israel. Rainfall simulation experiments were carried out on several plots at different times since the fire. Runoff and sediment yield were collected during the experiments. Soil samples from the upper soil layer (0–4 cm) were collected for analysing physical and chemical properties The results obtained show that the total runoff and sediment yield varied considerably in both space and time. High spatial variability, at the plot scale, together with relatively low fire intensities and a well-structured and stable soil, were considered to be the main reasons for the very low runoff and sediment yield at the meso-scale (hillslope).

SLOPE ASPECT EFFECT ON SOIL AND VEGETATION IN A MEDITERRANEAN ECOSYSTEM

Differences in soil properties were found between north- and south-facing slopes located in a Mediterranean region with an average annual rainfall of 690 mm. In general, the differences are small, and in some cases even insignificant. The amount of organic matter, Na, Cl, and K, and available nitrogen (N-NH4 and N-NO3) are higher in the northern aspect than in the southern one. However, pH, CaCO3, and available P are significantly higher in the southern than the northern aspect. The differences between the aspects in plant species diversity are very great and are expressed mainly in relatively dry winters. The higher species diversity in the south-facing slope is due to the presence of herbaceous, mainly annual, plants. The importance of such differences in the Mediterranean region is discussed.

Effects of soil type, plant composition and leaching on soil nutrients following a simulated forest fire

Abstract The objective of this study was to determine the effects of a simulated light fire (250°C) on the availability of N and P, and on concentrations of ions in solutions of two typical Mediterranean soils (Chromic Luvisol and Lithic Xerothent) that support an oak shrubland and an Aleppo pine forest respectively. Likewise, the effect of fire on soil taken from beneath pine trees (Pinus halepensis) and from the adjacent interspace was investigated. Soil nutrients in all the types of soil and in all the treatments increased after the fire. However, the extent of the increase of the nutrients and their dynamics depends on the characteristics of the soil and of the microhabitat (the underlying and nearby interspace), on the tree species burnt during the fire, and on the leaching process. The overall conclusion in this study is that fire increases nutrient concentrations in mineral soil. Yet, changes are distributed in a mosaic pattern, a fact which contributes to the complexity of the ecosystem.

EFFECT OF SLOPE ASPECT ON SOIL AND VEGETATION PROPERTIES ALONG AN ARIDITY TRANSECT

ABSTRACT This study has investigated the effect of south- and north-facing hillslopes (SFS and NFS, respectively) on soil and vegetation properties along a climatic transect that covers four climatic zones: Mediterranean, semiarid, arid, and extreme-arid. The results indicate that differences between NFS and SFS in organic matter and soil moisture contents were significantly higher in the Mediterranean zone than in any other site along the climatic transect, particularly at the end of the rainy season. Both soil properties were higher on NFS than on SFS. Similarly, differences between the opposite hillslopes in species richness along the climatic transect were found significant only in the Mediterranean zone, where species richness was higher on the SFS than on the NFS. However, species diversity on SFS was significantly higher than that on NFS at all sites, except for the semiarid zone, where no significant difference between aspects was found. Species diversity on SFS changed along the climatic transect...

Effect of simulated forest fire on the availability of N and P in mediterranean soils

The effect of soil burning on N and P availability and on mineralization and nitrification rates of N in the burned mineral soil was studied by combustion of soils in the laboratory.At a fire temperature of 600°C, there was a complete volatilization of NH4 and a significant increase of pH, from 7.6 in the unburned soil to 11.7 in the burned soil. Under such conditions ammonification and nitrification reactions were inhibited. Less available P was produced immediately after the fire at 600°C, as compared to P amount produced at 250°C. Burning the soils with plants caused a decrease in NH4-N and (NO2+NO3)-N concentrations in the soil as well as a reduction in ammonification and nitrification rates. Combustion of soil with plants contributed additional available P to the burned soil.The existence of a non-burned soil under the burned one played an important role in triggering ammonification and nitrification reactions.

Spatial distribution of soil surface coverage on north and south facing hillslopes along a Mediterranean to extreme arid climatic gradient

Four research sites were established along a climatic gradient in Israel representing Mediterranean, xeric Mediterranean, arid and extreme arid climate conditions. The cover percentage of eight soil surface components [vegetation (annual and perennial forms), biogenic crust (mosses, lichens, cyanobacteria, and dwarf grass), stones and bare soil patches] were measured. Transects along hillslopes on each of two opposite aspects (south and north facing slopes) were established at each site (altogether eight transects). Dominance and soil surface cover diversity indices, and similarity coefficients between the transects were calculated. High similarity values in soil surface cover were found between the south facing slopes located in the xeric Mediterranean, arid, and extreme arid areas. These hillslopes are dominated by stones and bare soil patches. In contrast, lower similarity values were found between the northern slope aspects dominated by biotic components (vegetation and biogenic crusts). The study along a climatic gradient together with the comparison between northern and southern aspects provide useful information that can be utilized for evaluation of changes in soil surface cover characteristics given various scenarios of future climate regimes in that region.