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Effective land management in the Djeffara plain, southeastern Tunisia, is being constrained by increasing land degradation issues due to arid climate conditions and soil erosion. Thus, this study aims to assess the impact of the... more
Effective land management in the Djeffara plain, southeastern Tunisia, is being constrained by increasing land degradation issues due to arid climate conditions and soil erosion. Thus, this study aims to assess the impact of the integrated control measures, namely windbreaks and controlled grazing, on the restoration of land cover dynamics in six managed rangeland areas. Land cover changes were monitored using satellite data and the derived vegetation indices (the normalized difference vegetation index (NDVI) and the soil-adjusted vegetation index (SAVI)) from Landsat 8 (OLI), both within and outside the protected areas. The findings reveal that the implemented protection measures lead to an increase in vegetation cover, diversity, and plant density. They play an important role in stabilizing the upper soil layer. The oldest protected areas, particularly those that are well-maintained with controlled seasonal grazing, experienced a reduction in sand movement. The reintroduction of g...
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Abstract Salinity stress causes several physiological, biochemical and molecular damages in plants; however, few of them can tolerate the high salinity in their rhizosphere. Sulla carnosa (Desf.) is a legume forage species occupying the... more
Abstract Salinity stress causes several physiological, biochemical and molecular damages in plants; however, few of them can tolerate the high salinity in their rhizosphere. Sulla carnosa (Desf.) is a legume forage species occupying the saline depressions of Tunisia. To explain the distribution of this species and investigate its response to salinity, a greenhouse experiment was conducted on plants cultivated in different NaCl concentrations (0, 100, 200 and 250 mM). Seeds were harvested from the natural biotope, Sabkha d’El Kelbia (35°50′34′′ North, 10°16′18′′ East). Plant growth, ionic repartition, oxidative stress and antioxidant enzyme activities were investigated. special interest was attributed to the interrelation between some physiological and biochemical key parameters in order to scrutinize the mechanisms that control the response of the plant to salinity. Obtained results demonstrated that soil salinity increased sodium accumulation, MDA and H 2 O 2 contents and antioxidant enzymes such as SOD, CAT, and GPX with a significant decrease of biomass production, water use efficiency and potassium concentration. This forage legume revealed important tolerance to salinity with the capacity to grow until 250 mM NaCl. It allocates more potassium to shoots to avoid the excessive accumulation of the toxic ion, develops an efficient antioxidant system to detoxify the plant cells from high ROS accumulation, and maintains adequate water use efficiency.
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This study tests the diurnal variations of water status, leaf gas exchanges and chlorophyll fluorescence in Pistacia vera L. (P. vera L.) and Pistacia atlantica Desf. (P. atlantica Desf.) seedlings. At 40% of field capacity, diurnal... more
This study tests the diurnal variations of water status, leaf gas exchanges and chlorophyll fluorescence in Pistacia vera L. (P. vera L.) and Pistacia atlantica Desf. (P. atlantica Desf.) seedlings. At 40% of field capacity, diurnal variations in water uptake, relative water content (RWC) were estimated every hour between 5:00 am and 7:00 pm. The daily course of light, temperature, photosynthesis (A), stomatal conductance (gs), transpiration rate (E), intrinsic water use efficiency (A/gs), mesophyll efficiency (A/Ci), internal CO2 concentration (Ci) and chlorophyll fluorescence were measured every 3 h from 05:30 am to 7:30 pm in irrigated and stressed seedlings of the two studied species. The results showed a significant variation in all surveyed parameters over diurnal cycle. The stressed seedlings of P. atlantica exhibited considerably higher RWC, water uptake, A, gs, E, A/gs and A/Ci over diurnal cycles compared to P. vera stressed seedlings. In contrast, P. vera was more sensitive to water stress and excess light and temperature over the diurnal cycle. The midday stomatal conductance and photosynthesis decrease was more likely the result of low RWC caused by high transpiration rates, stomatal closture and photoinhibition. Photoinhibition is a protective mechanism of PSII, rather than a result of photo-damage of photosynthetic apparatus. P. atlantica revealed an important physiological feature that is maintaining photosynthesis at midday compared to P. vera. This might be due to internal regulation through several mechanisms mainly better osmotic adjustment, photoprotective mechanisms of PSII.
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In the saline depressions (Sebkhas) of Tunisia, Sulla carnosa expresses anarchic distribution, sometimes in association with halophytes sometimes individually. In order to explain this distribution, we investigated the effects of salinity... more
In the saline depressions (Sebkhas) of Tunisia, Sulla carnosa expresses anarchic distribution, sometimes in association with halophytes sometimes individually. In order to explain this distribution, we investigated the effects of salinity on seed germination, the osmotic and toxic limiting factors, and the importance of some stimulating agents (priming agents) in the improvement of the tolerance to salinity at the germinating stage. A study was conducted on seeds harvested from the natural biotope Sebkha d'El Kelbia (35°50′34″N, 10°16′18″E), and an increasing concentration of NaCl (0, 5, 10, 15, and 20 g L−1) was applied. Some priming agents were used to propose efficient, rapid, and low‐cost tools to improve the seed germination and tolerance of Sulla carnosa (Desf.) in saline depression. Salinity stress significantly decreased germination capacity and rate and delayed its initiation and maximum. Until 15‐g L−1 NaCl, the most limiting factor of seed germination is the osmotic e...
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Abstract Bioremediation using microorganisms have become innovative efficient tools for detoxifying a wide variety of urban and industrial wastewaters. In this study, we investigated for the first time the microbial detoxification of... more
Abstract Bioremediation using microorganisms have become innovative efficient tools for detoxifying a wide variety of urban and industrial wastewaters. In this study, we investigated for the first time the microbial detoxification of phosphate processing wastewaters (PPWW) by using the indigenous bacterium Serratia rubidaea NCTC12971, having numerous plant growth promoting traits. In fact, the isolated strain exhibited an attractive capacity of phosphate solubilization, siderophore production as well as indole acetic acid (IAA) secretion. Additionally, the strain has significant antifungal effect against Alternaria alternata. The monitoring of the bacterial growth at increasing concentrations of heavy metals showed minimum inhibitory concentrations (MICs) of 8, 6, 3 and 3 mg L−1, respectively for Pb, Cd, Cu and Zn. The 10-days treatment of PPWW by Serratia rubidaea significantly decreases its salinity in terms of electrical conductivity (EC), its chemical oxygen demand (COD), its biochemical oxygen demand (BOD5) and its total organic carbon (TOC). Regarding heavy metals removal, the detoxification rates were 94.4, 91.5, 85, and 66.5%, for Pb, Cd, Cu, and Zn, respectively. Moreover, the biological treatment of the PPWW declines its phytotoxicity toward lentils (Lens culinaris) and chickpea (Cicer arietinum) seeds germination. Hence, with the PPWW, the germination indices (GI) of chickpea (Cicer arietinum) and lentils (Lens culinaris) were 16.6 and 10%, respectively. While, with the biological treated (BTPPWW), the GI were significantly increased to approximately 76.6% for both seeds mentioned. Such results strengthened the potential use of Serratia rubidaea NCTC12971 for the establishment of biotechnological process aiming to minimize the harmful effects of PPWW as well as its use as plant growth promoting bacteria (PGPB). Highlights This study is the first report investigating the potential use of indigenous bacteria in the bio-treatment of wastewaters discharged from the Tunisian phosphate laundries units. Serratia rubidaea NCTC12971 was selected as a potent applicant for heavy metals detoxification. Serratia rubidaea NCTC12971 was characterized by its plant growth promoting traits and antifungal activity against Alternaria alternata.
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A greenhouse pot experiment was conducted at the faculty of sciences of Gafsa to evaluate the effect of phosphorus treatment on two pistachio species. The seedlings of Pistacia vera and Pistacia atlantica were subjected to six levels of... more
A greenhouse pot experiment was conducted at the faculty of sciences of Gafsa to evaluate the effect of phosphorus treatment on two pistachio species. The seedlings of Pistacia vera and Pistacia atlantica were subjected to six levels of phosphoric acid (P2O5) (0, 5, 15, 30, 60 and 120 ppm). Stomatal conductance, net photosynthesis, chlorophyll fluorescence (OJIP) and total chlorophyll content were measured after 1, 2, 3, 6, 8, 9 and 12 weeks of treatment. During the experiment, phosphorus application at 5 ppm increased photosynthesis and stomatal conductance, relative to the treatment 0 ppm only in P. atlantica. However, phosphorus supply at 60 and 120 ppm induced toxicity leading to an inhibition of CO2 photo-assimilation rate, an alteration of photosystem II (PSII) structure and function and reduction in leaf chlorophyll content in both species. The (OJIP) transient showed complex changes in O-J, J-I and I-P phases of fluorescence. Due to phosphorus toxicity, both donor and acceptor sides of PSII were damaged, electron transport perturbed and chlorophyll pigment reduced which resulted in the fall of CO2 photo-assimilation rate, followed by mortality in both species.
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This study was conducted to investigate the use of treated municipal wastewater (TWW) in agriculture. Experiments have been carried out from July 2013 to July 2014, irrigating Cenchrus ciliaris with TWW or tap water (TW). The study,... more
This study was conducted to investigate the use of treated municipal wastewater (TWW) in agriculture. Experiments have been carried out from July 2013 to July 2014, irrigating Cenchrus ciliaris with TWW or tap water (TW). The study, conducted under greenhouse conditions, compared the effect of TWW with the water normally used in irrigation, on the growth, phenological and phytomass production of C. ciliaris a species with high pastoral value. Firstly, our results evidenced that all the chemical parameters of TWW fell in the range of values permitted by Tunisian regulation except chloride. Additionally, TWW increased plant growth during the growth cycle, producing taller plant with respect to TW. All plants irrigated with TWW showed a better performance than plants irrigated with TW only. Similarly, TWW irrigations had positive impacts on flowering parameters during the reproductive cycle. Therefore, treated wastewater can be used as an alternative water resource in irrigation of annual fodder species, with the dual purpose of preserving fresh water and of increasing soil fertility as well as crop productivity.
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Little is known about the effect of seed natural long storage on the germination capacity of vascular plant species particularly those used in restoration programs. In the current paper, we aimed to study the effect of different seed... more
Little is known about the effect of seed natural long storage on the germination capacity of vascular plant species particularly those used in restoration programs. In the current paper, we aimed to study the effect of different seed storage durations (from 3 months to 22 years) on the germination of Argyrolobium uniflorum (Decne.) Jaub. & Spach, herbaceous legume of high pastoral value indigenous to the Mediterranean Basin. In this paper, we found that the seeds scarification, hasten germination capacity of scarified seeds (SS) to almost 80%. The seed germination is maintained for 14 years at the level of 78 to 60% and then decreases. Also, other measured parameters of water content, electric conductivity, seedling lengths and MGT were also modified along seeds age. The duration of storage affects the germination performance of Argyrolobium uniflorum seeds which decreases after approximately one decade and half which give us an idea about the longevity of soil seeds bank of this s...
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Research Interests: Earth Sciences, Environmental Science, Agronomy, Arid environments, Biological Sciences, and 15 moreEnvironmental Sciences, Community Dynamics, Eucalyptus, Acacia, Common Garden Experiment, Hydrophobicity, Infiltration, Growth rate, Available Phosphorus, Observational Study, Native Species, Arid Lands, Land improvement, Infiltration rate, and Ecosystem processes
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ABSTRACT Invasive exotic species are an ongoing cause of native biodiversity degradation, and allelopathy may assist in the degradation process. We studied the allelopathic potential of leaf and root aqueous extracts of Acacia saligna... more
ABSTRACT Invasive exotic species are an ongoing cause of native biodiversity degradation, and allelopathy may assist in the degradation process. We studied the allelopathic potential of leaf and root aqueous extracts of Acacia saligna (Labill.) Wendl. in the early settlement of three native Mediterranean shrubs (Astragalus armatus Willd., Retama raetam (Forssk.) Webb & Berthel., and Helianthemum kahiricum Del.). Aqueous extracts were applied at 0%, 5%, 10%, 15%, and 20%. For all three test species, increasing extract concentrations significantly increased the inhibition of seed germination and shoot and root elongation and gradually decreased seedling performance; the decreasing values of relative water content and F v /F m indicated that the plants had been exposed to stress. The leaf aqueous extracts of A. saligna were significantly more phytotoxic than the root aqueous extracts, even at the lowest concentration (5%). Fabaceae species had significantly less growth inhibition than Cistaceae species. The results from this study suggest that A. saligna has strong allelopathic potential, which emphasizes the importance of reducing its allelopathic effects and developing effective management strategies for mitigating invasion risk and protecting native species in Mediterranean arid environments.
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The phytotoxicity potential of phosphate laundries wastewater (PLW) is assessed. Likewise, the assays of biotreatment of the PLW by microbial detoxification are investigated. Chemical characterization results show that PLW are alkaline,... more
The phytotoxicity potential of phosphate laundries wastewater (PLW) is assessed. Likewise, the assays of biotreatment of the PLW by microbial detoxification are investigated. Chemical characterization results show that PLW are alkaline, saline, highly turbid, and rich in suspended matter and total solids. PLW samples are loaded with potentially toxic metals, presented in decreasing order as follows: calcium (1230 mg L−1), potassium (1032 mg L−1), iron (275.45 mg L−1), lead (1.64 mg L−1), zinc (1.12 mg L−1), copper (1.04 mg L−1), and cadmium (1.03 mg L−1). Besides, PLW exhibits high phytotoxicity values for Raphanus sativus, Medicago sativa, and Sorghum bicolor seeds germination. The microbiological enumeration reveals considerable autochthonous microflora. Biotreatment includes five selected native strains (Se, S16, S19, S20, and S29) used as a tool of PLW detoxification. The strains tested manifest a bioprocessing performance according to the following decreasing order: S29 > S1...
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The potential of treating agro-wastes by recovering organic amendments for agricultural soils is promising for Mediterranean countries that produce olive oils. In this study, olive mill by-products...
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Date palm (Phoenix dactylifera L.) is attacked by many insect pests including species of rhinoceros beetles (Coleoptera: Scarabaeidae). Among rhinoceros beetles, the genus Oryctes is associated with palm trees and is severe pests of date... more
Date palm (Phoenix dactylifera L.) is attacked by many insect pests including species of rhinoceros beetles (Coleoptera: Scarabaeidae). Among rhinoceros beetles, the genus Oryctes is associated with palm trees and is severe pests of date palm. The rhinoceros beetle, Oryctes agamemnon Burmeister (Coleoptera, Scarabaeidae) was accidentally introduced in the southwestern oases of Tunisia where it becomes a serious pest. In the present study, the spatial distribution of Oryctes agamemnon in the oases of Rjim Maatoug was examined. Data showed that all these oases are infested by this insect but with a percentage of infestation which varies from 20% to 100%. The oases Rjiim1 and Rjiim2 are the least affected by the Oryctes, with 40% and 20% respectively. The others oases showed that all the prospected plots are infested by the pest. The percentage of infested plots by oasis varied between 35 to 100 %. The rates of infected feet and the number of different stadiums by date palm in the plot...
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We investigated the accumulation of Zn, Cu, Pb, and Cd in the soil and the leaves and bark of five common tree species (Eucalyptus occidentalis Endl., Acacia salicina Lindl., Cupressus sempervirens L., Casuarina equisetifolia L., and... more
We investigated the accumulation of Zn, Cu, Pb, and Cd in the soil and the leaves and bark of five common tree species (Eucalyptus occidentalis Endl., Acacia salicina Lindl., Cupressus sempervirens L., Casuarina equisetifolia L., and Tamarix aphylla (L.) Karst.) in the city of Gabès Tunisia to elucidate their bioaccumulation potential and determine their usefulness as biomonitors of metallic pollution in arid urban areas. Our results indicated that the bark had higher mean concentrations of Pb and Cd than leaves. In contrast, the leaves had higher mean concentrations of Zn and Cu than bark. No hyperaccumulation was detected for any of the analyzed metals in any of the studied species. E. occidentalis and T. aphylla had the highest mean concentrations of the investigated metals in leaves and bark. Based on the calculated metal accumulation index (MAI) values, these two species accumulated more metals than other studied tree species. Likewise, the concentrations of Zn, Cu, Pb, and Cd in soil had significant positive correlations with that in leaves and bark. Accordingly, E. occidentalis could be used for biomonitoring in arid areas subjected to industrial and traffic pollution. T. aphylla would be a good alternative when native species are a priority.
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We investigated the study of the phytotoxic potential of olive mill wastewaters (OMW) on the germination and growth responses of the faba bean ‘Vicia faba L.’ leguminous plant cultivated under arid Mediterranean climate. The results... more
We investigated the study of the phytotoxic potential of olive mill wastewaters (OMW) on the germination and growth responses of the faba bean ‘Vicia faba L.’ leguminous plant cultivated under arid Mediterranean climate. The results showed that the raw OMW blocked the germination of the seeds tested, while OMW treated soil extracts stimulate the seeds germination rate. The monitoring of the faba bean growth parameters in the different OMW treated soils showed that the optimal growth of the faba bean plants has been recorded for the soil amended with 25 m3 ha−1 of OMW. Although the 50 m3 ha−1 dose is the most suitable for the soil studied, our results showed that the 25 m3 ha−1 dose is the most suitable for the vegetative development as well as for the productivity of the plant tested ‘Vicia faba L.’.
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Studying relationships of plant traits to ecosystem properties is an emerging approach aiming to understand plant's potential effect on ecosystem functioning. In the current study, we explored links between morphological and... more
Studying relationships of plant traits to ecosystem properties is an emerging approach aiming to understand plant's potential effect on ecosystem functioning. In the current study, we explored links between morphological and nutritional leaf traits of two Mediterranean perennial grass species Stipa tenacissima and Lygeum spartum, widely used to prevent desertification process by stabilizing sand dunes. We evaluated also relationships in terms of nitrogen (N) and phosphorus (P) availability between leaves of the investigated species and the corresponding soil. Our results showed that leaf P was very low in comparison with leaf N for the two investigated species. In fact, chlorophyll content, photosynthesis capacity and water conservation during photosynthesis are mainly linked to leaf nitrogen content. Our findings support previous studies showing that at the species levels, morphological and nutritional leaf traits were not related. On the other hand, significant relationships were obtained between soil N and leaf N for S. tenacissima (P = 0.011) and L. spartum (P = 0.033). However, leaf P was not significantly related to soil P availability for both species. We suggest that any decrease in soil N with the predicted increasing aridity may result in reduction in leaf N and thus in worst dysfunction of some biological processes levels. Resume L'etude des relations entre des caracteristiques d'une plante et les proprietes de l'environnement est une approche emergente visant a comprendre l'effet potentiel de la plante sur le fonctionnement de l'ecosysteme. Dans cette etude, nous avons explore les liens entre des caracteristiques morphologiques et nutritionnelles des feuilles de deux especes de graminees mediterraneennes perennes, Stipa tenacissima et Lygeum spartum, largement utilisees pour empecher les processus de desertification en stabilisant les dunes de sable. Nous avons aussi evalue les relations en termes de disponibilite en azote (N) et en phosphore (P) entre les feuilles des especes etudiees et le sol correspondant. Nos resultats ont montre que le P des feuilles etait tres bas par rapport au N des feuilles pour les deux especes etudiees. En fait, le contenu en chlorophylle, la capacite de photosynthese et la conservation de l'eau pendant la photosynthese sont principalement lies au contenu des feuilles en azote. Nos resultats confirment des etudes anterieures qui montrent qu'au niveau de l'espece, les caracteristiques morphologiques et nutritionnelles des feuilles ne sont pas liees. D'autre part, nous avons obtenu des relations significatives entre le N du sol et celui des feuilles pour S. tenacissima (P = 0.011) et L. spartum (P = 0.033). Cependant, chez les deux especes, le P des feuilles n'etait pas lie a la disponibilite du sol en P. Nous suggerons que toute diminution de l'azote du sol, resultant de l'aridite croissante predite, pourrait entrainer une reduction de l'azote des feuilles et donc de graves disfonctionnements de certains niveaux de processus biologiques.
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The present study is carried out at the full protected area (Z1) of the national park of Bou Hedma, reserve of biosphere since 1977, that still shelters the unique wooded steppe of Acacia tortilis in Tunisia. It aimed at establishing the... more
The present study is carried out at the full protected area (Z1) of the national park of Bou Hedma, reserve of biosphere since 1977, that still shelters the unique wooded steppe of Acacia tortilis in Tunisia. It aimed at establishing the current ecological systems map of this area (in 2003). To meet this objective, a satellite imagery (SPOT) taken in March 2000, was treated and visually digitalized meaning a GIS program (Arcview 3.2) and validated with analyzed field data. The produced of the current vegetal map (year 2003) of the studied area has permitted to distinguish four main plant formations according to the region geomorphology : the mountainous ecological systems, those of the piemont, those of the valley and those of streams. These four big vegetation units include fifteen different ecological systems. Key words : Cartography, ecological systems, Bou Hedma national park .
Acacia tortilis subsp.raddiana is one of the most uncommon species and is still present in North African regions. Indeed, the region of Bled Talah, in the south of Tunisia, constitutes today an ecosystem where the species continues to... more
Acacia tortilis subsp.raddiana is one of the most uncommon species and is still present in North African regions. Indeed, the region of Bled Talah, in the south of Tunisia, constitutes today an ecosystem where the species continues to grow on a large surface of 16,488 ha. There is little information on the long-term dynamics of Acacia trees. The overall objectives
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ABSTRACT
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The aim of this study was to evaluate the compositional and nutritional potential of methanolic extracts of various parts of Acacia leucophloea Roxb. concerning the chemical composition and antioxidant potential of which limited... more
The aim of this study was to evaluate the compositional and nutritional potential of methanolic extracts of various parts of Acacia leucophloea Roxb. concerning the chemical composition and antioxidant potential of which limited information is available. Compositional studies indicated carbohydrates as major components in both seed and pods. Despite differences in mineral content among the leaves, pods and seeds, calcium was found in the highest amount and zinc in the lowest. The amino acid profile indicated aspartic acid as the major amino acid and proline as the minor. Among protein fractions, globulin was present in higher amounts than other fractions. Linoleic acid was the major fatty acid detected in the oil from both pods and seeds, while g-tocopherol was the major component of the tocopherol observed from same oil. Moreover, significant antioxidant potential was observed from the extracts of all three parts investigated. The results obtained in this study clearly indicate tha...
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Cette etude consiste a suivre l'interaction entre Acacia tortilis ssp. raddiana et la strate herbacee sous l'effet des variations pluviometriques au sein du parc national du Bou Hedma. Le recouvrement vegetal et la densite des... more
Cette etude consiste a suivre l'interaction entre Acacia tortilis ssp. raddiana et la strate herbacee sous l'effet des variations pluviometriques au sein du parc national du Bou Hedma. Le recouvrement vegetal et la densite des especes perennes et annuelles ont ete ainsi observes sous et hors canopee de l'arbre. Les principaux resultats montrent qu'Acacia raddiana influence positivement les deux parametres de la vegetation. Lorsque les conditions hydriques sont favorables, l'amelioration du recouvrement vegetal resultant de l'effet de l'arbre peut atteindre 55%. Sous l'effet de la secheresse, cette amelioration est d'environ 70%. Dans ces memes conditions hydriques, la densite de la vegetation perenne accuse elle-meme, une amelioration de l'ordre de 89% en presence de l'arbre. Cependant, elle reste un peu influencee par la pluviometrie. En revanche, la densite des annuelles est fortement menacee par l'absence des pluies. L'ameliorat...
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Biological soil crusts (BSCs) composed of cyanobacteria, green algae, bryophytes, and lichens are a major biotic component of arid and semi-arid rangeland environments worldwide. They are recognized and studied in many parts of the world.... more
Biological soil crusts (BSCs) composed of cyanobacteria, green algae, bryophytes, and lichens are a major biotic component of arid and semi-arid rangeland environments worldwide. They are recognized and studied in many parts of the world. However, they have been the subject of very few studies in Africa. The current study deals with the assessment of the influence of BSCs on soil chemistry in an arid ecosystem in Southern Tunisia. Our main objective is to test whether biological soil crusts are able to improve soil chemical properties. Our investigation showed that biological soils crusts had an expressive effect on soil chemistry. In fact, biologically crusted soils had higher levels of pH, electrical conductivity, organic matter, organic carbon, nitrogen, phosphorus, Ca, K, Na, Cl and lower C: N ratio compared to biologically un-crusted soils. The differences between crusted and un-crusted soils were statistically significant at 95% confidence. The PCA results demonstrate further ...