Pua Bar

Reducing Persistent Seed Banks of Invasive Plants by Soil Solarization—The Case of Acacia saligna

Abstract An important factor in controlling invasive plant infestations is frequently the acceleration of the deterioration of their persistent seed bank, which is often associated with physical dormancy mechanisms. We hypothesized that breaking dormancy by heat would enhance the vulnerability of the nondormant seeds to hydrothermal stresses. The aim of the present study was to examine the effect of soil solarization treatments (heating the soil by means of polyethylene mulching) on buried Australian Acacia seeds, with emphasis on Acacia saligna L. The results of three field experiments indicate that soil solarization treatments caused an almost complete eradication of buried seeds of Acacia saligna and two other Australian Acacia species, Acacia murrayana and Acacia sclerosperma. The killing mechanism of solarization was further studied in laboratory experiments. We observed two phases of the heat-induced deterioration of seed persistence: breaking the dormancy of the seeds and exposing the “weakened seeds” to lethal temperatures. From an ecological perspective of conservation, the present study shows for the first time the possible utilization of solar energy, by means of soil solarization, for reducing persistent seed banks of invasive woody plants. Nomenclature: Acacia saligna L.

The effect of anthropogenic resources on the space-use patterns of golden jackals†

ABSTRACT We studied the influence of agricultural villages on space-use patterns of golden jackals (Cants aureus Linnaeus) in the Mediterranean region of Israel. Villages in our research area attract jackals due to poor sanitation conditions in and around villages. As resources in these villages are abundant and predictable, we expected that space-use patterns of jackals near those villages, including home-range characteristics and movement paths, would differ from those of jackals inhabiting more natural areas. Using radio-locations from 16 individuals (8 near villages and 8 from more natural areas), we found that mean home-range size of jackals close to villages was 6.6 ± 4.5 km2 , smaller than mean home-range size of jackals in more natural areas (21.2 ± 9.3 km2 , P = 0.001). Similarly, core area size of jackals near villages was 1.2 ± 0.92 km2 , compared to 3.5 ± 1.62 km for individuals inhabiting more natural areas (P = 0.004). The core area/home--range ratio was greater for jackals near villages than for those occupying more natural areas (0.122 ± 0.045 vs. 0.095 ± 0.037, respectively, P = 0.004). Jackals moved little during the day, with day ranges smaller for jackals near villages than away from them (1.65 ± 0.67 vs. 7.5 ± 5.6 km2 , respectively, P = 0.028). However, jackals near villages moved as much at night as did jackals in more natural areas, although movement was in a less directional manner. Changes in distribution and predictability of resources due to anthropogenic activity affect not only the home-range size of jackals, but also how they utilize and move through space.

Restoration of Coastal Sand Dunes for Conservation of Biodiversity: The Israeli Experience

Two-thirds of the coastal dune area along the Israeli Mediterranean Sea has been lost owing to intensive urbanization and infrastructure development. The remaining dunes are fragmented and only a small part of them have been declared protected. Nizzanim LTER is the largest nature reserve (2,000 ha). Because of low wind velocity in the area, the dunes are experiencing a stabilization process followed by a reduction in the characteristic biodiversity and a shift in desert and psammophilic organisms into characteristic Mediterranean, opportunists and generalists’ species. In order to inhibit the complete stabilization of the entire dunes and to conserve the characteristic biodiversity of the nature reserve, the perennial vegetation was removed from several stabilized dunes in order to reactivate them to a mobile state and to encourage the re-establishment of sand-dwelling organisms. Four years later, the treated dunes are very different from the mobile or semi-stabilized dunes, but are still similar to the stabilized dunes.

Soil seed banks, habitat heterogeneity, and regeneration strategies in a Mediterranean coastal sand dune

This study investigated the effects of microhabitat characteristics on soil seed bank structure, regeneration strategies, and plant composition in a Mediterranean coastal sand dune in Israel. Three different microhabitats were selected: (a) open patches between shrubs, (b) shrub understorey, and (c) open, disturbed patches in pedestrian trails. In each microhabitat two types of sampling plots were established: (a) seedling removal and (b) control (seedlings not removed). Emerging seedlings in each microhabitat were identified, counted, and removed every two weeks. In the controls, the vegetation was sampled only once at the peak of the herbaceous growing season. At the end of the growing season in plots where seedlings were removed, the upper soil was collected and sieved before seeds set. Viable non-germinated seeds were identified and counted. An estimation of persistent seed banks was obtained for each plot. Species composition, species richness, species diversity, and aboveground biomass by species were estimated. Germination fractions among species and plant functional groups were measured. Microhabitats differed in soil seed bank density, germination characteristics, above-ground biomass production, and species composition. The open patches between shrubs generally had the highest densities of seeds, seedlings, and mature individual herbaceous plants. Important density differences between total seedlings removed and mature vegetation may indicate strong plant mortality in all microhabitats. Annual and perennial grasses, composites, annual crucifers, and annual forbs produced transient seed banks, while legumes, umbelifers, and perennial forbs had persistent seed banks. Disturbance by public trampling in trails led to low seed and plant densities in this microhabitat. No effects of facilitation of shrubs on the annual vegetation were noted in shub understorey. Habitat heterogeneity had a strong impact on vegetation structure and regeneration strategies.

Two Stages Decision Process Toward Organic Food: The Case of Organic Tomatoes in Israel

We analyzed consumers of organic and nonorganic tomatoes in Israel with respect to their sociodemographic characteristics and attitudes to organic food consumption (tomatoes). A double-hurdle model was used. Here, consumers could choose either to be organic or nonorganic consumers and/or how much tomatoes they consume. Instead of concentrating on willingness to pay (WTP) for a premium (as is customary for many studies), our respondents were faced with a given premium and were asked about their preferences for organic tomatoes. Results reveal that price premium was not an important component in the decision to be or not to be an organic tomatoes consumer. However, it did prove important with respect to how many tomatoes to consume. While previous studies point to health benefits as the main motive for buying organic food, with concern for the environment and taste mentioned as secondary reasons, our study found that environmental concerns were the primary factor influencing whether or not to buy organic, while price and taste were factors in determining how much organic food to purchase.

Plant Silicon and Phytolith Contents as Affected by Water Availability and Herbivory: Integrating Laboratory Experimentation and Natural Habitat Studies

AbstractPurpose When studying the effects of environmental variables on plant Si contents, results of laboratory and field experiments do not always agree with each other. However, new insights into the roles silicon plays in plant life can be gained if both approaches are integrated. Methods Experimental and natural-habitat studies of the effects of water availability and herbivory on plant silicon contents are reviewed and integrated. Results Although higher water availability is expected to have a positive effect on plant silicon contents, naturally-growing plants often have high silicon contents when grown under drought conditions. Likewise, although experimentation suggests that herbivory has a positive effect on plant silicon contents, such a correlation is not often found in nature. Conclusions Stronger effects of multiple environmental variables or selection in favour of constitutive silicon uptake and deposition as protection from drought and grazing stresses are the reasonable causes of discrepancies between experimental and natural-habitat studies.

Consumers’ Preferences Toward Organic Tomatoes: A Combined Two-Phase Revealed-Stated Approach

ABSTRACT We analyzed consumers of organic and nonorganic tomatoes in Israel with respect to their sociodemographic characteristics and their attitudes regarding organic food consumption. More specifically, we were interested in the public motives (environmental attitudes) vs. private motives (health). Since environmental motives dictate a binary decision, while health motives can be accommodated with a range of intermediate decisions, consumers in our model could choose to be either organic or nonorganic consumers, as well as choose how many tomatoes they consume. The decision was rested with repeated price premiums for organic tomatoes. Results reveal that price was not an important component in the decision to be or not to be an organic tomato consumer. However, price premium was important when considering the amount of tomatoes to consume. Thus, our study does not confirm the results of other studies that point to the sole motive of health benefits for buying organic food.

The relationships between patch size and Sarcopoterium spinosum association properties at the Mediterranean fringe—Israel

Habitat loss and landscape fragmentation are considered factors that cause a significant decrease in biodiversity and changes in the community composition. The impact of fragmented natural patches of various sizes on plant species richness, plant composition, and soil properties were investigated in this study. The study area was located in a semiarid Mediterranean region (average annual rainfall 300 mm/ winter) and dominated by Sarcopoterium spinosum L. (SP) association. The results indicated that: (a) SP dwarf-shrubs were absent from patches of less than one hectare; (b) SP and other perennial coverage increased with patch size; however (c) herbaceous plants dominated the patches (70-100%); (d) the annual grasses Stipa capensis Thunb. and Avena sterilis L. were the dominant species and their coverage was significantly higher in the small patches; (e) species richness increased with patch size; (f) the total number of species for all the patches was almost two times higher than in the adjacent nature reserve; (g) native weeds such as Chrysanthemum coronarium L. and Centaurea hyalolepis Boiss. abounded in the patch edges; (h) the similarity between the patches and the adjacent nature reserve increased with patch size, but was less than 35%; and (i) rock fragments were almost absent from the small patches where the soil was shallower than in the large patches. In conclusion, on the patch scale, it is important to conserve larger patches. However, on the landscape scale, it is recommended to conserve the various patch sizes because of their high biodiversity.

Visitor trampling impacts on soil and vegetation: the case study of Ramat Hanadiv Park, Israel

ABSTRACTIn recent decades, recreational activities in natural open areas have increased substantially. At the same time, stresses imposed upon these areas have increased considerably as a result of a significant reduction in their dimension. These activities strongly affect ecosystem attributes and processes.This paper intends to review several studies that were conducted in one of the protected areas in Israel, Ramat Hanadiv Park, aiming to (a) quantify the rate of pedestrian trail development and (b) examine the impact of high and low trampling intensities on soil and vegetation properties at different trail sections (center, edge and control – a natural area adjacent to the trail).The following properties were examined: soil compaction, bulk density, aggregate size distribution, organic matter, moisture, electrical conductivity, pH, sodium and potassium concentrations, vegetation cover, species richness, and composition.The results indicated that: (a) the number of pedestrian trails increased slightly between the years 1944 and 1990; (b) soil properties, except for soil compaction and aggregate size, were not affected by low trampling intensity. A slight decrease in the soil measured properties was recorded at trail centers. However, under high trampling intensity, a reduction in most soil measured properties was detected on all trail sections; (c) vegetation cover, height and species richness were lower at the trail center under high and low trampling intensities. Herbaceous plant species that are common in compacted soils were found under intense trampling impacts.The conclusions from the studies conducted at Ramat Hanadiv Park were: (a) there is a positive correlation between trampling intensities and soil and vegetation properties; (b) an increase in trampling intensity is followed by spatial degradation of soil properties beyond the trails visible boundaries (what we referred as the “control”); and (c) most of the trails in Ramat Hanadiv Park experience low trampling intensities.

Stabilization of Sand Dunes: Do Ecology and Public Perception Go Hand in Hand?

Abstract This chapter focuses on economic valuation of coastal dunes in Israel, based on public and professional ecological perspectives. The contingent valuation method (CVM) was applied in the Nizzanim Long-Term Ecosystem Research (LTER) nature reserve in Israel, and concurrently, data of plant species composition on stabilized and mobile dunes were used to calculate the ecological value index (EVI) of the different dune states. These two values were then compared and used to estimate the expected change in economic value resulting from a state shift from mobile to stabilized dunes. The outcome from these results suggests that neither method outweighed the other in this study. Rather, both value assessments should be presented to decision makers.