المستودع المؤسسي الرقمي لجامعة عمر المختار

يوفر المستودع المؤسسي الرقمي لجامعة عمر المختار وصولًا مفتوحًا ومنظمًا إلى النتاج العلمي والمعرفي المرتبط بالجامعة، بما يشمل المقالات العلمية، والرسائل والأطروحات، ومجلات الجامعة، والكتب والنشر الجامعي، وأوراق المؤتمرات، والبيانات البحثية والمواد المرافقة.

يهدف المستودع إلى حفظ السجل العلمي للجامعة، وتعزيز ظهوره واكتشافه على المستويين الوطني والدولي، ودعم الوصول المفتوح، وتحسين قابلية الاستشهاد العلمي، وتوفير ميتاداتا عالية الجودة وروابط دائمة للمواد العلمية.

يستند تنظيم المستودع إلى بنية مؤسسية واضحة، وسياسات معتمدة، ومعايير وصف وفهرسة تدعم العربية، بما يضمن سهولة الإيداع، ووضوح الاكتشاف، واستدامة الحفظ الرقمي.

روابط مهمة

المجتمعات والمجموعاتاتفاقية الاستخدامسياسة الخصوصيةالبحث في المستودعاتصل بنابوابة السياسات والمعلومات

بوابة جامعة عمر المختار لحفظ وإتاحة النتاج العلمي والمعرفي في بيئة رقمية موثوقة وداعمة للوصول المفتوح.

الهيكل المؤسسي المعتمد

المظلات العليا المعتمدة لمستودع جامعة عمر المختار

النتاج العلمي للجامعة

الرسائل والأطروحات

مجلات الجامعة

الكتب والنشر الجامعي

المؤتمرات والوقائع

البيانات البحثية والمواد المرافقة

المواد والكيانات المرتبطة

أحدث التقديمات

Study and assessment of natural vegetation cover in the Jabal Al-Akhdar region (Final report)
(Omar Al-Mukhtar University, 2005) Omar Al-Mukhtar University
This exploratory study was initiated to assess the condition of shrub vegetation in the Jabal al-Akhdar region and to identify the causes of the deterioration that had become clearly evident in one of its most important components: long-lived evergreen juniper trees, which account for an estimated 80% of all mature trees in this important region of the Great Jamahiriya. The specialists who conducted the study considered it necessary to include natural rangelands, recognizing that the conservation and development of shrub cover can only be achieved by characterizing the vegetation of natural rangelands, identifying their ecological assets, and proposing measures for their improvement. Such measures would help reduce the pressures exerted on forest and scrubland areas by increasing numbers of livestock that roam through them in search of forage sufficient to meet their nutritional needs. The study was also undertaken to establish a scientific perspective grounded in factual evidence and quantitative measurements, with the aim of addressing the questions and interpretations circulated at all levels concerning the observed deterioration in the condition of natural vegetation across Jabal al-Akhdar. The following section presents the preliminary indications reached by the specialists through an exploratory investigation of a natural phenomenon whose occurrence involves complex interactions among biotic and abiotic factors. More detailed studies are required to determine the role of each factor. Because the characteristics of complex ecosystems change only over long time scales, it is difficult to establish the causes of their degradation within a period of no more than eighteen months, which was the duration of the present study. It is well established that a number of indicators are used to assess the condition of shrub and rangeland vegetation in a given area. Some have been proposed by major international agencies, such as the Food and Agriculture Organization of the United Nations (FAO) and the United Nations Environmental Protection Agency (UNEPA), while others have been adopted by international and regional organizations, including the International Union for Conservation of Nature (IUCN) and the World Wide Fund for Nature (WWF), which is concerned with Mediterranean forests. These indicators include measurements of growth rates, vigour, density, canopy cover, regenerative capacity, and the level of services available to people, such as recreation in the surrounding environment and the utilization of vegetation products. Natural vegetation may also be assessed according to its capacity to provide suitable conditions for wildlife and economically important insects, such as honey bees, and to protect soil against erosion, thereby slowing the acceleration of desertification and sand encroachment onto agricultural land and human settlements, particularly in arid and semi-arid regions. Modern technologies, including satellite imagery, are also used to document the total area occupied by natural vegetation across a defined tract of land at a particular historical point, in order to monitor subsequent changes in its extent or condition and to investigate their causes. Guided by these considerations, plans and implementation mechanisms for the study and assessment of natural vegetation in Jabal al-Akhdar were designed to address these vital aspects and ensure the achievement of the study objectives. This is reflected in the reports produced by the specialized working teams and in the resulting important database covering geology and mapping, soils and water resources, forests and rangelands, diseases and pests, and the socioeconomic characteristics of the region's population. On the basis of the field and laboratory observations and data obtained by these teams, documented in periodic reports throughout the exploratory study and compiled in this final report, marked deterioration in shrub and rangeland vegetation, together with a reduction in its extent, was recorded in several areas of Jabal al-Akhdar. Indicators of the deterioration of natural shrub cover - although varying in their manifestations and severity - were not confined to a single area. Degradation was recorded at several locations on the first coastal terrace, including Sidi Amer-al-Hamamah, Wadi al-Jabal, and Wadi Bualnidi; on the second terrace, including al-Sultiyah, Qandafurah, and Silyun; and on the third terrace, including Qasr Libya-Marawah, Wadi al-Mafwah, and Wadi al-Sudan. The results showed that the diseases and pests recorded in the Jabal al-Akhdar areas targeted by this exploratory study are common in such environments. These included spotting diseases affecting al-Sakhab, al-Butum, and al-Barish; soil fungi recorded on al-Zuhayrah and al-Shabraq; cicadas (Bourzin); and weevils. At this exploratory level, however, these organisms were not found to constitute a principal cause of the degradation affecting shrub cover in particular. Dense lichen growth on juniper trees in some severely degraded areas has attracted the attention of many observers and may lead them mistakenly to assume that the lichens caused tree mortality. In fact, these growths are opportunistic organisms that found a suitable habitat on trees after the trees had already undergone decline or complete death as a result of other, non-pathogenic factors. The indicators of natural vegetation condition used in this study, including density, canopy cover, and regeneration, also showed that, despite the death of substantial numbers of juniper trees or parts of them, appreciable regeneration of the dominant tree and shrub species was recorded across the region. This was evident in the numbers of juniper seedlings along paved road verges and beyond, including at Qasr Libya-Marawah, Mirad Masoud, al-Aslab, and the coastal zone extending from Soussa to al-Hamamah. Resprouting of al-Shammari and al-Butum shrubs was also observed at sites from which they had been removed or where they had been destroyed by severe fires, including Talaq Nazar, Ras al-Hilal, and Sidi Hamad. In addition, terraces currently occupied by invasive trees, as in Mirad Masoud and al-Bayadah, are expected to recover their formerly dominant shrub cover - which was cleared in the 1980s for the cultivation of fruit trees - provided that seed sources are available and the soils are protected against erosion. These signs merit close attention and should be monitored, while suitable conditions should be created to extend their occurrence throughout Jabal al-Akhdar. Moreover, important sites such as Mirad Masoud-coast, Sidi Khalid, Ras al-Turab, and al-Zardah have retained the vigour, density, and diversity of their natural shrub cover, either because they were not exposed to indiscriminate fires or excessive cutting, or because favourable soil conditions were present, particularly adequate soil-profile depth and available moisture. Other contributing factors include fissures, fractures, and cavities resulting from tectonic movements, which are penetrated by tree and shrub roots and allow the retention of soil produced by weathering and leaching processes, thereby providing a degree of moisture and nutrients. Such conditions have been documented on the slopes surrounding the channels of Wadi al-Kuf and Wadi al-Sudan and on the hills extending from al-Hamamah to Sidi Amer, which are characterized by dense and diverse shrub cover. The study further showed that the areas occupied by natural forests and scrublands have declined in comparison with their extent in the early 1970s. An earlier report submitted by FAO indicated an area of approximately 320,000 hectares, whereas the present study estimates the current area at only about 299,000 hectares. This reduction is partly attributable to major agricultural development schemes under which important agricultural settlement projects were established on land excised from natural forests, as occurred in al-Wasitah, al-Marj, Farzu'ah, al-Bayadah, Mirad Masoud, and elsewhere. The sites selected at that time for these agricultural projects, as well as the areas allocated to them, were appropriate to the characteristics of the respective regions and demonstrated strong consistency with the principles of optimal land use and sustainable development. These principles enable productive land to be used for crop and fruit-tree cultivation while conserving natural vegetation in other areas that do not meet the criteria for such investment. However, the unsustainable human activities that followed and continue to the present - including the indiscriminate removal or deliberate burning of shrub cover to cultivate marginal crops or fruit trees, or to provide grazing land on shallow or rocky soils - have contributed both to the contraction of natural forests in these areas and to the spread of low-value invasive plants in their place. Accordingly, the quality and area criteria recommended by specialized international institutions and adopted as benchmarks in this exploratory study for assessing the condition of natural vegetation indicate degradation in some major components of shrub vegetation in Jabal al-Akhdar, including juniper and al-Shammari. The onset of this degradation cannot be attributed directly to drought resulting from reduced rainfall or poor rainfall distribution. Soils throughout Jabal al-Akhdar, across their different classifications, including those that supported well-developed shrub cover, had low moisture contents, and their capacity to provide moisture did not differ substantially from that of soils in areas characterized by severely degraded shrub cover. The study further indicates that, although the pests and diseases prevalent in these areas have important effects on natural vegetation, their severity is not sufficient to account for the level and intensity of degradation observed in several parts of Jabal al-Akhdar. Negative human practices, particularly indiscriminate cutting and overgrazing in sensitive environments such as mountain slopes and rangelands, constitute the most serious threat to ecosystems in general. The continued acceleration of both qualitative and quantitative degradation may ultimately lead to the loss of a national natural resource that would be difficult to replace. The study confirmed that the natural rangelands south of Jabal al-Akhdar are in a very poor condition as a result of the degradation of their natural vegetation. Indicators of degradation in these areas include the local disappearance of several annual plants and short evergreen shrubs, severe declines in their density and vigour, the spread of plants of low forage and economic value, or a combination of these conditions. Given the characteristics of the southern areas, which contain extensive and important rangelands such as Buzra', al-Nazur, al-Mukhayli, Jardas, Sidi Saad, and al-Habshah, and which are characterized by higher mean temperatures, degraded soil properties, lower rainfall, and poor rainfall distribution, the continuation of prevailing grazing practices will have serious consequences. Of particular concern are the increase in livestock numbers to unrealistic levels and the failure to allow sufficient time for the remaining adapted native plants of relatively good forage value - such as al-Ramth, al-Qurtah, al-Hajram, and wormwood - to reproduce and regenerate naturally through appropriate rotational grazing systems. Continuation of these practices will diminish the importance of this rangeland vegetation and intensify desertification in these important parts of Jabal al-Akhdar. The deterioration of soil properties following the removal of mature trees by people - especially on steep slopes - and the destruction of old check dams, both characteristic of forest and scrubland areas in Jabal al-Akhdar, has stimulated other destructive processes, including soil erosion and the loss of soil fertility. Deliberately set fires, which have now become common in the forests of Jabal al-Akhdar and which destroy natural vegetation, provide the clearest illustration of the adverse role played by people in relation to ecosystems. In addition to destroying enormous numbers of trees and shrubs - especially juniper trees that formerly covered steep hills across vast areas including Ras al-Hilal, Talaq Nazar, Sidi Hamad, Sidi Amer, Wadi Marqus, and elsewhere - severe fires have also destroyed signs of natural regeneration and created opportunities for other low-value invasive species to become dominant. Overgrazing in these areas has likewise reduced the effectiveness of soil-development processes by compacting the soil, lowering the rate of water infiltration through the soil layers, and reducing the accumulation of organic matter. These effects have adversely affected vegetation and prevented the establishment of new seedlings, either because their growing environment has deteriorated or because livestock feed on them. Such effects are clearly visible in areas where grazing is intensive, and juniper in particular has failed to regenerate naturally in locations where it was formerly dominant. The reduced growth and vigour of shrub vegetation, which frequently accompany these negative human activities, have made plants more susceptible to diseases and pests, impaired their ability to grow and reproduce, and reduced their capacity to benefit from the distinctive environmental resources of the region, which remain capable of supporting significant vegetation cover. Despite the challenges it faces, the natural vegetation of Jabal al-Akhdar continues to represent a model of a unique ecosystem extending along an important part of the southern Mediterranean coast. This exploratory study documented and highlighted its natural assets, and its findings confirmed the diversity and distinctive character of the region's climate, landforms, soils, water resources, shrub cover, natural rangelands, and medicinal and aromatic plants. The study also emphasized its long-established social systems and human cultural heritage, which demonstrate the region's historical contribution to shaping the legacy of the past and its continuing efforts to sustain this vital ecological and human role in the present and the future.
الفقد الكتلي والتغير في تركيز المغذيات خلال تحلل أوراق أشجار الصنوبر الحلبي النامية في ترب الجبل الأخضر
(جامعة عمر المختار, 2009-07-20) الزوي, فرج
The aims of the present study were to determine Mass loss (ML%) and the changes patterns of Holocellulose (cellulose , hemicelluloses) , Lignin (Non- hydrolysable Residues; NHR), water and Ethanol- Solubles as well as the dynamics of N, P, Na , K , Ca , Mg , Mn , SO4, NO3. The concentration of N in Lignin C:N , Lignin:N and C:P were also determined .The influence of site properties on these parameters (Responses) were evaluated. To achieve these aims , the litter bag technique, which is a wellknown tool for the study of litter decomposition, was applied using bags of 10X10 cm dimentions and with 1mm diameter. The required numbers of the bags were fixed on the bottom of each Aleppo pine (Pinus halepensis Mill.) stands grown in three sites located at 410, 630, and 860m. a. s. l. of the Jabal Alakhdar eco- region, Libya by using a split design system in Four plots. The experiments started in 1.10.2006 and conducted for 18, 10 and 7 months the latter 2 plots Located at 860 m. a. s. l. The data obtained were statistically assessed using ANOVA, Correlation and Regression analysis. The ML (%) values were ca 25, after 7 months of decomposition with significant differences (P.0.05); after 10 months, these values increased to 31% in the stands located at 410 and 630 m. a. s. l. and both were significantly differed with (P.0.05) compared to the stands located at 860 m. a. s. l (ML of ca 20%) . ML Values reached 60% and 43% after 18 months in stands located at 410 and 630 m. a. s. l. respectively and were significantly differed (P.0.05); the water- and ethanol-solubles were significantly differed and decreased from ca 14% and 25% to ca 10% and 18% after 18 months of incubation (decomposition). However, the lignin (NHR) increased from 32 to 38% at both sites, whereas the holocelluloses increased from 27% to 33 and 29% respectively. The total concentration of carbon decreased from 48 to 46 % in both sites and this means that the loss of carbon did not exceed 2% after one and half year of decomposition and consequently the emission of CO2 was low under such pine forest systems. On the other hand, the total N increased up to 1.1 % confirming the fact of the chemical combination of nitrogen (as NH3) to the aromatic rings exposed during the biodegradation of lignin. Total phosphorus decreased from 0.23 to 0.1 and 0.07% in sites located respectively at 410 and 630 m. a. s. l. and no changes of total potassium were observed in both sites. Negative and positive r values between some responses were observed (P.0.05) and some values of R2 above ca 60 % were also noticed. Finally, it is of highly importance to wisely expand the area of Aleppo pine plantations in the bared localities spread in this eco-region. This is for increasing the contribution of such pin forest systems of carbon dioxide capturing and retarding its emission to the atmosphere of our green and fragile planet to reduce the tragedy of the global warming phenomenon.
وجود بكتيريا الكبريت في ترب داعمة للعرعر والبطوم تحت ظروف الجبل الأخضر-ليبيا
(جامعة عمر المختار, 2017-05-02) بوبكر, مفتاح
The aims of this study were to determine the persistence of the sulphur oxidizing bacteria in different decomposition stages "the humus layer" and in the soils supporting the (Juniperus phoenicea L and Pistacia lentiscus L). These bushes covers ca 80%' of the Gabal AlAkhdar eco-region, Libya. In the culturing media, the impacts of the pH, salts, temperature and the production of sulfates from such bacterial isolates were also examined. The least significant difference (LSD, 5%) and Pearson correlations between the variables were done using SPSS. To achieve these aims, two sites contain the two plants were selected in the Settia area located north east of Shahat town at ca 400 masl. From each plant and Rhodoxeralfs soils, composite samples were collected from the humus layers The separation of these stages were carried out according to the morphology of the litters. Soil samples were collected at (0-10 cm) depth. The physical (texture and moisture) and chemical analysis including the total N, P, K, S and sulphates and the total counts of bacteria were done at the lab of soil microbiology, Omar Al Mukhtar University. The bacterial strain grew in the thiosulphate medium during a period of 7-10 days. At pH = 8, colonies in a pure culture were appeared white to light yellow .These chemolithoautotrophic mobile short rod cells were a gram-negative, non-endo-spore forming. Such characteristics indicate that this isolate was a Thiobacillus thioparus.The persistence of T. thioparus in the late stages and in the soils supporting the Juniperus were higher than in the Pistacia. The number of the strain in the Pistacia and Juniperus ranged between 0.15 ×104 to 58 × 104 and 0.16 ×104 to 61 × 104, 0.032 ×104 to 50 ×104 and 5.6 × 104 to 91 in the first and the second sites, respectively. Positive correlations were observed between T. thioparus counts and the P, K, SO4-2 and the total count of the bacteria. Strong negative correlation (p<0.001 and R2 of ca 25%, n=60) with EC. The correlations between total count and pH, and total S were negative of p<0.024 and 0.001, R2 of ca 20 t0 25%, n=60, respectively. The total S positively correlated with R2 of ca 25%. Total S positively correlated with the total P (p<0.001 and R2 of ca 25%. Sulfates positively correlated with EC (p<0.001, R2 of ca 25%, n=60, also it negatively correlated with total N (p<0.006, R2 of 16%, n=60. The optimum effect of temperature (25, 30, 35, 40) on the strain after 7 days of incubation was at 30 C and the minimum was 40C. the effect of For the pH, the optimum and minimum were 8 and 5 and no growth at 4. NaCl, CaCl2 and MgCl2 conc. of ( 0.1, 1, 5 g / L ) showed a detrimental effects comparing with the control the sodium thiosulphate medium Conc. of (0.1,1,2,3,4,5,6,7 g) showed optimum and minimum growth at 5g "control" and 0.1g respectively. The effect of this bacterial strain on pH and sulphate production in the thiosulphate medium after about two weeks of incubation revealed that the pH decreased from 7.8 to 6.4 and by 1.4 (17.95%). Sulfate concentration also increased from 0.03% to 0.05%. The Starkey medium on the other hand, decreased pH values from 7.8 to 4.5 by 3.3 (42.31%) with an increase of 24.36% in the thiosulphate medium. This reflects the impact of the type of sulfuric compound "energy source" in increasing acidity, which confirms the superiority of sulfur element "S8" in recommending the development of this bacterial strain for the purpose of reclamation of the salt affected soils (sodic soils). It was observed that the high acidity does affect the growth of this strain but the growth of such bacterium In vivo differs than the growth In vitro "The Habitat" due to the presence of calcium carbonates ; the limestone 'the bed rock' and many other alkaline ions.
تقييم بعض خصائص الترب الساحلية ومصادر مياه الري بمنطقة الحنية – الجبل الأخضر
(جامعة عمر المختار, 2022-02-22) اجويلي, وجدي
Al-Hinya is known as a coastal area and is one of the largest areas of the coastal municipality. It is considered one of the most important agricultural areas in Jabal Al-Akhdar, about 25 km away from the city of Al-Bayda. Al-Henya area is of economic importance because of the crops it produces capable of meeting all the needs of Jabal Al-Akhdar. This makes the soil of the area in a state of depletion of its nutrients or even subject to deterioration as a result of intense pressure on it with fertilizers. Therefore, this area was targeted to monitor the condition of the soil in it and follow it during two different seasons. Forty sites were randomly selected to take soil samples that differ in terms of their proximity and distance from the coast. The samples are located at different altitudes from sea level. A number of wells used by farmers for irrigation were also selected. The study included routine procedures for soil by studying the chemical properties of the soil as well as the chemical properties For irrigation water, and therefore to determine its suitability for irrigation compared to global measurements issued by the US Department of Agriculture), USDA, 1954) and about the Food and Agriculture Organization (FAO, 1985) Chemical analyzes consist in knowing the degree of electrical conductivity "EC", the degree of pH and dissolved ions in addition to the use of many mathematical indicators that included the percentage of sorbed sodium "SAR" and the modified "RSC" and residual sodium carbonate "RSC" in addition to some other mathematical indicators for irrigation water.
تأثير معدلات الري بمياه الصرف الصحي لمدينة البيضاء بالجبل الأخضر علي خصائص التربة ونمو النبات
(جامعة عمر المختار, 2009-04-18) المهدي, محمد
Fresh water resources are limited in most arid and semiarid regions. Libya is not an exception . Jabal Al-Akhdar north – east of libya, receives the highest annual rainfall in the country, but fluctuation in rainfall coupled with increasing demand for fresh water to meet domestic, agricultural and industrial activities posed serious pressure on groundwater which practically represents the sole source of fresh water in the province . A national strategy to utilize domestic sewage effluent to irrigate some forage crops was implemented early in the 1973's. The strategy was limited to two projects namely, Al-Hadba project near Tripoli and Al-Gawarsha project near Benghazi. Other parts in the country including Jabal Al-Akhdar were not included in this national strategy. The current study was aimed toward evaluating the potential for utilizing the untreated domestic sewage effluent of Al-Bayda city in Jabal Al-Akhdar for irrigation on soil chemical properties and the growth of maize ( Zea mays L.), barley ( Hordeum vulgare L. ) and alfalfa ( Medicago sativa L.) in pot experiment under semi–controlled conditions . The two soils are representing forest soils ( Lithic Rhodoxeralfs ) northern part of Jabal Al-Akhdar and pastoral soil ( Lithic Xeric Haplocalcids) southern part of Jabal Al-Akhdar. Groundwater and the untreated sewage effluent of Al-Bayda city were used for irrigation. Two irrigation levels were evaluated based on plant vegetative and root biomass as well as their nutrient and toxic elements content. Each treatment was imposed in triplicates as in Complete Randomized Block Design (RCBD). The data were analyzed statistically by utilizing the software (Genstat ). The impact of irrigation practices on the chemical properties of the two soils were also evaluated . The results of this study has revealed that sewage water contains good concentrations of essential plant nutrients; including nitrogen, phosphorus, potassium, calcium, magnesium, copper and zinc, In addition some pollutant elements such as nickel and lead. Their concentration of the polluting elements was within the accepted range for agricultural use according to local standards as well as Food and Agriculture Organization ( FAO, 1976) and the United States Environment Protection Agency ( USEPA, 1993 ) guidelines. The wastewater was also chacteristized by its low content of soluble salts . The use of the domestic wastewater affected the two soil’s chemical properties positively even though the time span of this study was limited. A significant increase in available phosphorus, total nitrogen, soil organic matter content and cation exchange capacity was observed. The irrigation with ground water or wastewater caused a marginal change in soil рH and soluble salt contents in the two soils . Results has indicated higher plant root weights were produced by crops included in this study when irrigated with the untreated effluent as compared to groundwater. This seems to enhance plant ability to absorb more water and plant nutrients as well as pollutant ions from the soil, which were further reflected positively on wet and dry weight of vegetative parts of these crops and their contents from nutrients such as phosphorus, potassium and calcium . The use of the untreated effluent for irrigating maize, barley and alfalfa led to an increase in nickel, copper, lead and zinc concentration in the two soils and plants tissues, but their concentrations remained within the local and international permissible limits. The concentrations of pollutant elements were highest in the roots of these plants. This reflects important plant selectivity for absorbing ions, and appreciable control for their translocation to the upper plant parts through accumulation in their root systems. This study indicated that the utilization of untreated domestic effluent of Al-Bayda city even for supplementary irrigation of maize, barley and alfalfa under semi controlled conditions and for one season has resulted in significant increase in weight of the vegetative part production of these crops. Moreover, there is no increase in the concentration of pollutant elements in plant tissues that may pose risks to human or domestic animals were detected. Moreover, the use of this nontraditional water source for irrigation under the prevailed conditions of this study has improved the two soil’s chemical properties. [ It seems imperative to pursue this annovative investigation for further evaluation on long term effects of this water resource under field conditions. The chemical make-up of Al-Bayda domestic effluent appear to be acceptable. This will enhance the potential for its use to improve crop production, combating desertification and rehabilitating rangeland. In addition to improvement of the natural ecosystems distinguishing Jabal Al-Akhdar, the adoption of a well planned strategy in this direction will no doubt result in lifting some of the pressure on the limited fresh groundwater of the region.