This study addressed the effect of the dwarf shrub Sarcopoterium spinosum on soil properties, soil moisture and vegetation characteristics (plant density and richness) in a semi-arid ecosystem. Vegetation characteristics and soil sample data were obtained from three areas: 1) beneath the S. spinosum patch, 2) between the patches and 3) from the open area. The results showed that the area beneath S. spinosum had significantly higher soil moisture content, organic matter, available ammonium, nitrate, and phosphorus compared to the areas between shrubs and open areas. The results also showed that the total plant density and richness decreased significantly beneath the shrub canopy compared to the areas between shrubs and open areas. Certain plant species are found only beneath the shrub canopy. Our results indicated that S. spinosum creates habitat heterogeneity by modifying the area beneath its canopy and influencing the community structure. Interactions and the mechanisms of interactions between S. spinosum and other annual plants play an important role in determining community structure and affecting the distribution of plant species beneath and around the shrub canopy. Thus, understanding such interactions and understanding their mechanisms are important issues that should be considered for rangeland management and conservation.

Quantitative trait locus (QTL) genetics retains an important role in the study of biological and agronomic processes; however, its genetic resolution is often comparatively low. Community-based strategies are thus required to address this issue. Here we detail such a strategy wherein the widely used Solanum pennellii introgression lines (ILs) in the genetic background of the cultivated tomato (Solanum lycopersicum) are broken up into molecular marker-defined sublines as a community resource for map-based cloning.

Plant yield is the integrated outcome of processes taking place above and below ground. To explore genetic, environmental and developmental aspects of fruit yield in tomato, we phenotyped an introgression line (IL) population derived from a cross between the cultivated tomato (Solanum lycopersicum) and a wild species (Solanum pennellii). Both homozygous and heterozygous ILs were grown in irrigated and non-irrigated fields and evaluated for six yield components. Thirteen lines displayed transgressive segregation that increased agronomic yield consistently over 2 years and defined at least 11 independent yield-improving QTL. To determine if these QTL were expressed in the shoots or the roots of the plants, we conducted field trials of reciprocally grafted ILs; out of 13 lines with an effect on yield, 10 QTL were active in the shoot and only IL8-3 showed a consistent root effect. To further examine this unusual case, we evaluated the metabolic profiles of fruits from both the homo- and heterozygous lines for IL8-3 and compared these to those obtained from the fruit of their equivalent genotypes in the root effect population. We observed that several of these metabolic QTL, like the yield QTL, were root determined; however, further studies will be required to delineate the exact mechanism mediating this effect in this specific line. The results presented here suggest that genetic variation for root traits, in comparison to that present in the shoot, represents only a minor component in the determination of tomato fruit yield.

The effects of different vegetation types on runoff generation and soil erosion were investigated. The study was conducted at the Southern part of West Bank, about 10 Km north-west of Hebron city, during 2005, 2006 and 2007. Five treatments were implemented; forests planted with P. halepensis (F), natural vegetation dominated by S. spinosum (W.S), natural vegetation where S. spinosum was removed (W/o.S), cultivated land (C), and deforestation (Of). Three types of data were estimated in each plot: runoff after each rainfall event, sedimentation at the end of the rainy season, and chemical and physical soil properties. The obtained results indicate that there are significant and important differences in runoff generation and sediment production with respect to the different types of vegetative cover. Forest and natural vegetation dominated by S. spinosum treatments exhibited the lowest amounts of runoff, with averages of 2.02 and 1.08 mm, respectively, in comparison to other treatments. The removal of S. spinosum significantly increased the total amount of runoff and sedimentation compared to the forest and S. spinosum treatments. In addition, runoff significantly increased (4.03 mm) for the Df treatment compared to that of the forest site. The greatest amount of sedimentation was observed in cultivated land and with deforestation.The forest and S. spinosum treatments exhibited the highest percentages of organic matter of the five investigated treatments.The results indicate that forests and natural vegetation dominated by S. spinosum prevent or decrease the risk of runoff and soil erosion. In conclusion, the removal of S. spinosum and forest trees as a means to improve rangeland productivity increases runoff and sediment fluxes if not accompanied by careful grazing management. In addition, interchangeably using arid and semi-arid lands as rangeland and for cultivation may have significant negative impacts on the production potential of these lands. (C) 2010 Elsevier B.V. All rights reserved.

This study addressed the hydrological processes of runoff and sedimentation, soil moisture content, and properties under the effect of different water harvesting techniques (treatments). The study was conducted at three sites, representing environmental condition gradients, located in the southern part of the West Bank. For each treatment, the study evaluated soil chemical and physical properties, soil moisture at 30 cm depth, surface runoff and sedimentation at each site. Results showed that runoff is reduced by 65-85% and sedimentation by 58-69% in stone terraces and semi-circle bunds compared to the control at the semi-humid site. In addition, stone terraces and contour ridges significantly reduced the amount of total runoff by 80% and 73%, respectively, at the arid site. Soil moisture content was significantly increased by water harvesting techniques compared to the control in all treatments at the three study sites. In addition, the difference between the control and the water harvesting structures were higher in the arid and semi-arid areas than in the semi-humid area. Soil and water conservation, via utilization of water harvesting structures, is an effective principle for reducing the negative impact of high runoff intensity and subsequently increasing soil moisture storage from rainfall. Jessour systems in the valley and stone terraces were effective in increasing soil moisture storage, prolonging the growing season for natural vegetation, and decreasing the amount of supplemental irrigation required for growing fruit trees.

This study was part of a large project that was implemented by the Ministry of Environmental Affairs to combat desertification in the West Bank area. The study was conducted at two sites (Al-Dahria and Al- Samoo') located at the southern parts of the eastern slopes of the West Bank. More than 40 plant species were identified in each of the study sites. At both sites the dominant plant species were Poa bulbosa, Bromus syriacus, and Sarcopoterium spinosum. The total plant cover percentage was low in both sites (54.34 and 57%), while rock cover was relatively high (21.33 and 18.8%) in Al-Dahria and Al-Samoo', respectively. The vegetation biomass was low (711 and 929 kg dry matter/ha in Al-Dahria and Al- Samoo', respectively). The soil survey revealed that at both Sites, the soil texture was clay to clay loam, with low fertility. Range condition was poor and soil was eroded. The first priority should be improving the vegetative cover, applying the suitable management programs, and using the suitable and practical conservation techniques.