Lygeum Research Articles

Isolation and Characterization of Novel Cellulose Micro/Nanofibers from Lygeum spartum Through a Chemo-Mechanical Process.

Recent studies have focused on the development of bio-based products from sustainable resources using green extraction approaches, especially nanocellulose, an emerging nanoparticle with impressive properties and multiple applications. Despite the various sources of cellulose nanofibers, the search for alternative resources that replace wood, such as Lygeum spartum, a fast-growing Mediterranean plant, is crucial. It has not been previously investigated as a potential source of nanocellulose. This study investigates the extraction of novel cellulose micro/nanofibers from Lygeum spartum using a two-step method, including both alkali and mechanical treatment as post-treatment with ultrasound, as well as homogenization using water and dilute alkali solution as a solvent. To determine the structural properties of CNFs, a series of characterization techniques was applied. A significant correlation was observed between the Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) results. The FTIR results revealed the elimination of amorphous regions and an increase in the energy of the H-bonding modes, while the XRD results showed that the crystal structure of micro/nanofibers was preserved during the process. In addition, they indicated an increase in the crystallinity index obtained with both methods (deconvolution and Segal). Thermal analysis based on thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) confirmed improvement in the thermal properties of the isolated micro/nanofibers. The temperatures of maximum degradation were 335 °C and 347 °C. Morphological analysis using a scanning electron microscope (SEM) and atomic force microscope (AFM) showed the formation of fibers along the axis, with rough and porous surfaces. The findings indicate the potential of Lygeum spartum as a source for producing high-quality micro/nanofibers. A future direction of study is to use the cellulose micro/nanofibers as additives in recycled paper and to evaluate the mechanical properties of the paper sheets, as well as investigate their use in smart paper.

Characterization of thermomechanical properties and damage mechanisms using acoustic emission of Lygeum spartum PLA 3D-printed biocomposite with fused deposition modelling

This study examines the morphological, physicochemical, mechanical, and thermal properties of 3D-printed biocomposite fabricated using fused deposition modeling (FDM) with short Lygeum spartum fibers and PLA. Scanning electron microscopy (SEM) was used to analyze fracture surfaces and fiber dispersion within the PLA matrix after mechanical testing. Chemical and thermal properties were characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Mechanical performance was assessed through tensile and flexural testing, supplemented by digital image correlation (DIC) and acoustic emission techniques. The incorporation of 10% short natural fibers mitigated the brittle behavior of 3D-printed PLA, resulting in a more ductile biocomposite. These materials exhibited improved mechanical and thermal properties, including increased flexural modulus, higher elongation at break, and enhanced thermal stability compared to neat PLA. These findings underscore the potential of these biocomposites as biodegradable and eco-friendly materials for various applications.

Analysis of the state of floristic diversity by the comparison of germination between two native species Atriplex halimus and Lygeum spartum; sustainability of the steppe landscape of western Tlemcen Algeria

This article proposes a comparison of the germination of two halophytes. Atriplex halimus and Lygeum spartum subjected to different concentrations of Na + Cl- (2g / l, 4g / l, 5g / l, 6g / l, 7g / l , 9g / l) and in different culture media (Nutrient agar, Mac Conkey, Mannitol Mobility, Chapman, PDA). To remove the dormancy of the seeds, four pretreatments were carried out: scarification with razor blade, distilled water, boiling water and sulfuric acid. The seeds exhibit various behaviors with respect to the concentration of Na+ Cl- and the chemical composition of culture medium. It suggests that Lygeum spartum supports high salinity compared to the Atriplex halimus. Thus, the PDA culture medium accelerates the germination of the seeds because of its richness in phosphorus.

Study and Characterization of Algerian Spart Cellulosic Fibers (Lygeum spartum): Effect of Alkali and Acid Treatments on Their Physicochemical and Morphological Properties for Papermaking

Recently, non-wood plants have increasingly gained attention, due to their versatile advantages like cost and fast-growing period. The purpose of this study was to examine the effectiveness of different treatments on Algerian Spart fibers (Lygeum spartum) using sodium hydroxide at various concentrations (8, 10, 15, and 22% NaOH), and sulfuric acid at 30% for 2h at 100 °C. Fourier infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses were used to characterize the microstructural changes in the treated fibers. The results of FTIR confirmed the presence of cellulose in the raw fibers with a crystallinity index of 49.4%. The FTIR and XRD studies showed that an 8% NaOH treatment eliminated the amorphous constituents and improved the crystallinity index. Also, SEM micrographs confirmed the removal of impurities; for the acid treated fibers a pseudo-lignin was formed and deposited on fibers surfaces in the form of spherical droplets. Moreover, a decrease in the yield of cellulose at high alkali concentrations was noticed. The results suggest the possibility of exploitation of Spart fibers and their application in papermaking and as a reinforcement in composite materials.

Effect of Salinity and Drought on the Germination of Lygeum spartum L. in the Region of Saïda (Western Algerian Steppe)

Abstract Albardine (Lygeum spartum L.) is one of the major native grass species of the semi-arid and arid regions of the Mediterranean basin. In Algeria, it is much more widespread on the high plateaus of southern Oranais. This species occupies an important place in the steppe region because it has many ecological, economic, and fodder interests. The present work aims to study the tolerance of L. spartum seeds to water and salt stress, two abiotic factors that affect the physiology of the plant during the germinal stage. The methodology adopted consists of using increasing concentrations under a controlled temperature (15°C) for 21 days of germination. The germination responses of the seeds to different degrees of salt stress induced by NaCl (2, 4, 6, 8, 10 g/l) and water stress induced by polyethylene glycol (PEG;−2, -4, -6, -8, −10 bar), showed that the salt and water stresses retarded the germination rate of L. spartum L. seeds and also decreased their percentage during the time of the experiment. However, seeds soaked in distilled water (control) recorded a maximum germination rate of 80%. The results of this study show that L. spartum seeds are moderately salt and drought tolerant with a depressive effect on germination rate at a salt concentration of 10g/l and an osmotic pressure of −10 bar.

Threats affecting the distribution of Lygeum spartum Loefl. ex L. and its associated species in the Western Mediterranean desert of Egypt: Perspectives of conservation

The current study intends to evaluate the many hazards affecting the spread of the significant fodder grass Lygeum spartum Loefl. ex. L. and its associated species in Egypt's Western Mediterranean Desert over the past 60 years (from 1958 to 2020); depending on the data of the previous literature and the current situation evaluation by recent field trips. It also aims to assess its ecosystem services. Sixty-nine stands were collected from previous studies and unpublished data, in addition to 30 stands (10 m2) were added including 5 field trips during the period from spring 2019 to spring 2020. Measurements were taken to create a classification of this vegetation and to determine the main threats that affect its distribution composition. There are 142 species associated with the distribution of the studied plant in 6 habitats. While only 107 species were recorded in the recent stands in 7 habitats. Vegetation groups (G1- G8) obtained from TWINSPAN classification indicating that G1 (wadis) is the most diverse group with a species richness 34.7 species per stand, while G6 (dune) has the highest species turnover (4.57) during the period of 1958 to 2014. But in recent stands; G5 (saline and non-saline depression) is the most diverse group (30.875), while G2 (dunes) has the highest species turnover (4.819). Medicinal plants are the most represented (79.86%), followed by grazing plants (72.9%). The most common service is sand stabilization (92% of total services), followed by windbreak (natural) (40%). Threatened species represent 92.4%; habitat loss is the most affected threat (95 species), followed by over-collecting and over-cutting (82 species). Twenty out of 99 stands (20.2% of the total stands) have been destroyed due to human activity. Continuous monitoring of remaining patches of Egypt’s northwestern Mediterranean coast was required to save its natural flora from extinction.

Assessment of the role of the protected land in the preservation of the steppe in Southwest Algeria (Case of the Rogassa Region)

In the Algerian steppe (Rogassa) overgrazing led to the reduction of the surface of the pasture land and its biodiversity. The objective of this work was to highlight the importance of the protected land in maintaining biodiversity and preserving the degraded areas. A mixed sampling for the two different sites was adopted, where fifty floristic surveys were conducted using the Braun-Blanquet method. The analysis of the real biological spectrum of the unprotected land was marked by the strong dominance of the therophytes. However, in the protected land the chamaephytes dominated all of the biological types. The analysis of the biogeographic spectra revealed the reappearance of the endemic species (+3%). The Shannon Index was very important in this matter (2.43). The Student’s t-test of the biodiversity’s index showed a highly significant difference between the two sites. The ascending hierarchical classification revealed that the protected land is subdivided into four groups dominated respectively by: Macrochloa tenacissima, Lygeum spartum, Artemisia erba-alba and Hordeum murinum. The results of the Jaccard dissimilarity index indicated a strong difference of the order of 80% between the two areas.

Synergistic enhancement of the phytostabilization of a semiarid mine tailing by a combination of organic amendment and native microorganisms (Funneliformis mosseae and Bacillus cereus)

The goal of this work was to evaluate the effects of fermented sugar beet residue and inoculation with a native arbuscular mycorrhizal (AM) fungus, Funneliformis mosseae (Nicol. and Gerd.) Gerd. and Trappe, or a native bacterium, Bacillus cereus Frankland & Frankland, alone or in combination, on the establishment of Lygeum spartum L. seedlings grown in a mine tailing under semiarid conditions. We conducted a field study to analyse root and shoot dry biomass, shoot nutrient contents, mycorrhization, plant nitrate reductase (NR) and acid phosphomonoesterase activities, soil enzyme activities and aggregate stability. Ten months after field transplanting, it was found that the three experimental factors had interacted synergistically with regard to shoot and root biomass, with increases of about 410% and 370%, respectively relative to plants in the untreated soil. The treatment combining all three factors increased the root content of all heavy metals, and the levels of nitrogen (N), phosphorus, potassium and NR activity in shoot tissues, whereas it decreased root acid phosphomonoesterase activity. Soil dehydrogenase, protease and β-glucosidase activities, total N content and aggregate stability were increased by the combined treatment. In conclusion, the combination of the organic amendment, the native AM fungus and the native bacterium can be regarded as a suitable tool for phytostabilization with L. spartum due to its ability to enhance the tolerance of plants to heavy metals, improve the plant nutritional status and increase the soil microbial function related to the C cycling.

Biometrics analysis of the stem fibers of some local Algerian plant species

Studying the biometric characteristics of the stems of plant species has been of great interest to researchers in the wood and paper industry. The use of plant fibers has been widespread in the fields of composites, buildings, insulation, plastics and automobiles. The present study aimed to investigate the biometric characteristics of the stem fibers of local Algerian plant species, viz. Group 1 (Lygeum spartum and Stipa tenacissima), Group 2 (Linum usitatissimum in the greenhouse and Linum usitatissimum in natural conditions), Group 3 (Retama monosperma and Retama raetam) and Group 4 (Phoenix dactylifera and Ricinus communis). The extraction process was carried out using 1 M NaOH at 60 °C for 48 hours, and the fiber length was calculated for all the species using a micrometer. The fiber length of stems of all the species ranged from 0.36 to 5.18 mm. Then, the difference between each of the two species was approximated using Student's test. The results obtained showed that the t value ranged from 0.50 to 1.79 for Groups 4 and 1, respectively. There was no significant difference between them. These results suggest that these species are promising raw materials for paper production due to their adequate fibre length.

Assessment of the antioxidative response and culturable micro-organisms of Lygeum spartum Loefl. ex L. for prospective phytoremediation applications

Abundant plant species in arid industrial areas are mining phyto-resources for sustainable phyto-management. However, the association with their rhizosphere is still poorly known for phytoremediation purposes. This study aims to assess the heavy metals (HMs) and metalloids uptake of Lygeum spartum Loefl. ex L. growing in cement plant vicinity and screen associated culturome for potential phytoremediation use. Bioaccumulation factor (BAF), the translocation factor (TF), and the mobility ratio (MR) were studied along with four sites. Lipid peroxidation (MDA), free proline (Pro), Non-protein thiols (NPTs), and reduced glutathione (GSH) were tested for evaluating the plant antioxidative response. Bacteria and fungi associated with L. spartum Loefl. ex L. were identified by 16S rRNA and fungal internal transcribed spacer (ITS1-ITS2) gene sequencing. Our results showed an efficient uptake of As, Pb, and Zn and enhanced GSH (0.34 ± 0.03) and NPTs (528.7 ± 14.4 nmol g−1 FW) concentrations in the highly polluted site. No significant variation of Arbuscular Mycorrhizal Fungi (AMF) was found. Among 29 bacterial isolates, potential bioremediation were Bacillus simplex and Bacillus atrophaeus. Thus, L. spartum Loefl. ex L. and its associated microbiota have the potential for phytoremediation applications. Novelty statement: This work has been set in line with the investigation of the integrative biology of Lygeum spartum Loefl ex L. and the screening of its associated microbiome for potential phytoremediation applications. This work is the first work conducted in a cement plant vicinity investigating the associated fungi and bacteria of L. spartum Loefl. ex L. and been part of a sectorial research project since 2011, for assessing the impact of industrial pollution and recognizing the accumulation potential of plant species for further phyto-management applications.

Performance of halotolerant bacteria associated with Sahara-inhabiting halophytes Atriplex halimus L. and Lygeum spartum L. ameliorate tomato plant growth and tolerance to saline stress: from selective isolation to genomic analysis of potential determinants.

The use of halotolerant beneficial plant-growth-promoting (PGP) bacteria is considered as a promising eco-friendly approach to improve the salt tolerance of cash crops. One strategy to enhance the possibility of obtaining stress-alleviating bacteria is to screen salt impacted soils. In this study, amongst the 40 endophytic bacteria isolated from the roots of Sahara-inhabiting halophytes Atriplex halimus L. and Lygeum spartum L., 8 showed interesting NaCl tolerance in vitro. Their evaluation, through different tomato plant trials, permitted the isolate IS26 to be distinguished as the most effective seed inoculum for both plant growth promotion and mitigation of salt stress. On the basis of 16S rRNA gene sequence, the isolate was closely related to Stenotrophomonas rhizophila. It was then screened in vitro for multiple PGP traits and the strain-complete genome was sequenced and analysed to further decipher the genomic basis of the putative mechanisms underlying its osmoprotective and plant growth abilities. A remarkable number of genes putatively involved in mechanisms responsible for rhizosphere colonization, plant association, strong competition for nutrients, and the production of important plant growth regulator compounds, such as AIA and spermidine, were highlighted, as were substances protecting against stress, including different osmolytes like trehalose, glucosylglycerol, proline, and glycine betaine. By having genes related to complementary mechanisms of osmosensing, osmoregulation and osmoprotection, the strain confirmed its great capacity to adapt to highly saline environments. Moreover, the presence of various genes potentially related to multiple enzymatic antioxidant processes, able to reduce salt-induced overproduction of ROS, was also detected.

Ecological indicators and bioindicator plant species for biomonitoring industrial pollution: Eco-based environmental assessment

Industrial pollution remains a driving force to ecosystem alteration. Pollutants are released in the atmosphere interacting in turn with other components of earth system such as plant species. Despite the long-term exposition of vegetation cover to pollution is drastically devastating, less is known about the contribution of ecological indicators for its monitoring. The aims of this study are (i) to introduce the ecological indicators in assessing the cement dust impact on plant species and its biomonitoring and (ii) to screen new indicator species for phytoremediation studies. Floristic surveys were conducted in the cement plant closeness following quadrat method. Vegetation indicators such as total plant cover, perennial and annual species densities and diversity were assessed. Bioindicator species were identified using the bioaccumulation factor (BF) and translocation factor (TF). A decrease of perennial species richness and a decline of total vegetation cover by 7 times as well as a diversity decrease ranging from 2.99 to 2.31 were found pertinent indicators of land degradation in the industrial area. Annual species densities were significantly affected by cement pollution. Species like Lygeum spartum, Atractylis serratuloides and Gymnocarpos decander arise as indicators of heavy metals pollution. Pollution in the cement plant vicinity excluded sensitive species like Helianthemum kahiricum, Stipa tenassissima, Plantago coronopus. This study allowed the identification of indicator species of potential use in phytoremediation applications and emphasized the possibility of relaying on the vegetation indicators to assess the impact of cement pollution.

Manufacturing and Characterization of New Composite Based on Epoxy Resin and Lygeum Spartum L. Plant

Research development on the use of composites reinforced with natural fibers began in 1900 (Westman et al. 2010). For many decades, it has been a topic of great interest. In 1930s, Henry Ford devel...

Heavy metal transport and fate in soil-plant system: study case of industrial cement vicinity, Tunisia

During the last decades, Southeastern Tunisia has suffered from an industrial expansion leading to a serious pollution problem. In this work, heavy metal contamination near Gabes cement plant (Southeastern Tunisia) was assessed in the soils and statistically compared with a control site located 12 km away. Soil samples were collected from 5 to 15 cm below the surface layer. Concentrations of Cr, Mn, Co, Ni, Cu, Zn, Cd, Pb, and Fe and chemical parameters (conductivity, pH, CaCO3, OM) were measured. The variance analysis exhibited a significant difference (p < 0.05) in metal content between the two sites reflecting the cement plant contamination effect on the surrounding area. Eleven plant species widely distributed in the study area were collected together with the soil in which they were rooted, to assess their phytoextraction potential. Principal component analysis (PCA) was applied to understand the complex connection between soil, plants, and heavy metal contents. Lygeum spartum with respective total bioaccumulation factor (MBF = 1.48 ˃ 1 and Echiochilon fruticosum with a total translocation factor (MTF = 7.06) ˃ 1 were revealed as pertinent candidates for phytoremediation applications.

A formal classification of the Lygeum spartum vegetation of the Mediterranean Region

AbstractAimsWe examined all available literature and some unpublished data on the We examined all available literature and some unpublished data on the grasslands dominated by Lygeum spartum from Southern Europe and North Africa to produce a formalised classification of this vegetation and to identify the main factors determining its plant species composition.LocationMediterranean Basin and Iberian Peninsula.MethodsWe used a dataset of 728 relevés, which were resampled to reduce unbalanced sampling effort, resulting in a dataset of 568 relevés and 846 taxa. We classified the plots by TWINSPAN, interpreted the resulting pools, and used them to develop formal definitions of phytosociological alliances characterised by L. spartum vegetation. The definitions were included in an expert system to assist automatic vegetation classification. We related the alliances to climatic factors and described their biogeographical features and ecological preferences. The floristic relationships between these alliances were analysed and visualised using distance‐based redundancy analysis.ResultsWe defined eleven alliances of L. spartum vegetation, including the newly described Launaeo laniferae–Lygeion sparti from SW Morocco and the Noaeo mucronatae–Lygeion sparti from the Algerian highlands and NE Morocco. Biogeographical, climatic, and edaphic factors were revealed as putatively driving the differentiation between the alliances. Vegetations of clayey slopes and inland salt basins displayed higher variability in comparison with those of coastal salt marshes.Main conclusionsA comprehensive formal classification, accompanied by an expert system, of the grasslands from Southern Europe and North Africa dominated by Lygeum spartum vegetation was formulated. Eleven phytosociological alliances were recognised, whose plant species composition is influenced by biogeographic, climatic, and edaphic drivers. The expert system, containing formal definitions of the phytosociological alliances, will assist in identifying the syntaxonomic position of new datasets.

Functional similarity and competitive symmetry control productivity in mixtures of Mediterranean perennial grasses.

Competition is a major factor structuring plant communities and controlling their productivity. The functional similarity between the interacting species and the context resource availability are assumed to be most critical factors that modulate the strength, sign, and outcome of plant competition, yet their roles and interactions are subjected to debate. In a glasshouse experiment, we constructed monocultures and bi-specific cultures of three common perennial grasses of Mediterranean drylands, the short grass Brachypodium retusum and the tussock grasses Stipa tenacissima and Lygeum spartum, and investigated how the functional similarity between these species modulate their interactions and culture productivity under contrasting levels of water availability. Regardless the degree of functional similarity between the interacting species, B. retusum consistently exhibited a greater competitive ability than the other two species, followed by L. spartum, and with S. tenacissima behaving as the weakest competitor. Bi-specific cultures of B. retusum and either L. spartum or S. tenacissima produced higher biomass than the average biomass of the respective monocultures (i.e. overyielding), whereas the combination of the most similar species, L. spartum—S. tenacissima, which exhibited the highest competition symmetry (i.e., the more similar mutual impact), did not show any significant overyielding. Higher water availability increased productivity and promoted transgressive overyielding for the most dissimilar species, B. retusum and L. spartum, which however exhibited intermediate competition asymmetry. This study calls attention to the thin line between differences in functional traits and competition asymmetry that could eventually lead to either competitive exclusion or resource partitioning and coexistence.

Is aided phytostabilization a suitable technique for the remediation of tailings?

Mining activity in Cartagena‐La Union mining district (SE Spain) dates back more than 2500 years. Consequently, large amounts of sterile materials with large metal(loid) contents (mostly Zn and Pb) have accumulated in tailings ponds. A reclamation strategy based on aided phytostabilization was carried out to reclaim one tailings pond to reduce environmental and public health hazards. The main goal of this study was to determine the effectiveness of the aided phytostabilization strategy after 30 months from its implementation in enhancing soil quality and fertility and reducing mobility of the metals. Marble waste, raw pig slurry and its solid phase after physical separation were applied as amendments, and 13 Mediterranean native plant species were planted or sown. Various soil physicochemical and biochemical properties, together with the pseudo‐total and bioavailable fraction of the metal(loid)s, As, Cd, Cu, Pb and Zn, were monitored for 30 months. Results showed that pH, total organic carbon (TOC), total nitrogen (TN), cation exchange capacity (CEC), available phosphorus (P), exchangeable potassium (K), microbial biomass carbon (MBC), basal soil respiration (BSR) and enzyme activities increased with the application of the amendments and development of vegetation. In addition, the available fraction of metals markedly decreased (90–99%). Most plant species present in the area did not transfer large amounts of trace elements to the aerial tissues. The roots ofLygeum spartumloefl. Ex L. andPiptatherum miliaceum(L.) Coss. accumulated the largest amounts of As, Pb and Zn. Thus, the application of marble waste to increase pH and immobilize metal(loid)s, and pig slurry as a source of organic matter and nutrients, together with the development of vegetation to immobilize metal(loid)s in the roots and rhizosphere, and the effect of microbial communities on organic matter stabilization and development, have contributed to improve soil quality and fertility. Once the soil quality of mine tailings was improved, the development of vegetation and microbial colonization increased, promoting integrated reclamation of the area. Therefore, aided phytostabilization was a suitable technique for remediation of this tailings pond.HighlightsWe evaluated effectiveness of mid‐term and large‐scale aided phytostabilization.Marble waste, pig slurry and native plants were used for reclamation of a tailings pond.Increased soil quality promoted plant development and microbial colonization.Lygeum spartumandPiptatherum miliaceumare good candidates to phytostabilize Pb, Zn and As.

A single species, two basic chromosomal numbers: case of Lygeum spartum (Poaceae)

The existence of two chromosome numbers (2n = 16 and 2n = 40) in Lygeum spartum is confirmed in the Algerian steppe populations of Oran region. Chromosome counts were established for 11 Algerian populations and three supplementary populations from Italy, Spain and Greece. The karyotypes were characterized by chromosome markers obtained using fluorescence in situ hybridization and fluorochrome bandings. The organization of 5S and 18S-5.8S-26S (35S) rDNA was studied in both cytotypes. Six signals of 35S and 2 signals of 5S were observed in 2n = 16 population, while 10 signals of 35S and 4 signals of 5S were detected in the population with 2n = 40. All 35S loci were also strongly marked by chromomycin, but negatively stained by Hoechst, which indicates the presence of GC rich DNA in rDNA regions. The B chromosomes were found in both cytotypes, bearing a 35S locus in 2n = 16 population. Genome size, determined by cytometry of 10 populations, ranged from 9.27 pg for 2n = 16 to 26.63 pg for 2n = 40 populations. The sequencing of plastid and nuclear DNA markers did not reveal major differences among 2n = 16 and 2n = 40 populations. However, given the differences between two cytotypes and based on their morphological and cytogenetic characteristics, the 2n = 16 cytotype merits novel taxonomic treatment.

Soil micro‐organisms and competitive ability of a tussock grass species in a dry ecosystem

Abstract Drylands are among the most threatened ecosystems in the world because of the effects of global change and because they are not particularly resilient. Regeneration after disturbance is quite slow and secondary succession can be delayed to the point of nearly stop. This is exacerbated when the community is strongly dominated by a single species able to quickly respond after disturbance. One example of such monospecific dominance is the colonization of abandoned fields in SE Spain by an early successional and native tussock grass, Lygeum spartum, that seems to halt succession. Here we tested the competitive ability of Lygeum against Salsola oppositifolia, a shrub species that can be found interspersed with Lygeum in mid‐successional stages, and assessed how plant–soil interactions mediate the outcome of plant–plant competition. To do so, we sowed seeds and grew plants of Lygeum and Salsola in either intra‐ or interspecific competition under controlled conditions using sterile field soils inoculated with either live (i.e., with micro‐organisms) or sterile soil extracts from the understories of either Lygeum or Salsola. Soil nutrient content, seed germination rate, and shoot mass growth were determined after 5 months, and soil bacterial communities were characterized by sequencing. Lygeum soil micro‐organisms and soil properties, such as the high content of N and organic matter, enhanced seed germination rate of Lygeum individuals. By contrast, Salsola adults outperformed Lygeum when growing in interspecific competition. Synthesis. The enhanced competitive ability of Lygeum, which was mediated by soil micro‐organisms, may lead to complete dominance of Lygeum in the plant community right after abandonment of agricultural fields. However, when the plant community is already developed, Lygeum would be unable to enforce such dominance. We conclude that positive plant–soil feedbacks combined with certain plant traits such as clonal growth support the strong resilience of Lygeum and allow for its dominance in extreme habitats.

Rainfall patterns of Algerian steppes and the impacts on natural vegetation in the 20th century

Since 1960, the steppe regions of North Africa have been subject to an increasing desertification, including the degradation of traditional pastures. The initially dominant species (Artemisia herba-alba, Lygeum spartum and Stipa tenacissima) declined and were progressively replaced by other species (Atractylis serratuloides and Salsola vermiculata) that are more tolerant to the new conditions. It is not clear whether these changes are due to anthropogenic reasons or climatic determinism. We have carried out a statistical analysis of the climate to detect putative rainfall changes during the 20th century in the Algerian steppes based on data from 9 meteorological stations, including 2 Saharan stations (El Oued and Touggourt), 3 pre-Saharan stations (Biskra, Laghouat and Ain Sefra) and 4 steppe stations (Djelfa, Saida, Méchéria and El-Bayadh) located in the arid high plains, which represent the bioclimate diversities of the region. Previous studies suggested that significant rainfall changes for the 20th century only had records in the south of the Oran region. Most of the studies, however, looked at restricted territories over limited periods, and did not integrate the rainiest period 2004–2014. Our work is designed to integrate all the longest time series of meteorological data available for the steppe regions of Algeria. Our results confirm the spatial rainfall distribution (significant rainfall changes only recorded in the southwestern region) evidenced by previous studies, and reveal a decreasing rainfall gradient from northeastern to southwestern Algeria. Moreover, the results reveal a trend of significant decrease of rainfall in the southern Oran region, marked by two drought periods in 1980–1985 and 1999–2003. However, with the exception of the southwestern region, rainfall overall has not declined since the beginning of the 20th century. While less marked in other regions, the drought appear to have affected all territories of the Algerian steppe. Consequently, our study implies that the climate was not a leading influence in the on-going degradation of the vegetation cover of steppe landscapes. Such a vegetation evolution thus appears to be have been determined more by human activities than by climate forcing.