Juniperus Thurifera Research Articles

Phytochemical Diversity and Biological Effects of Juniperus Thurifera L., Essential Oil : A Comparative Study using In Vitro and In Silico Methods.

Juniperus thurifera L., a plant endemic to the Moroccan High Atlas Mountains, thrives in extreme climatic conditions, resulting in the production of valuable secondary metabolites. This study aims to elucidate the phytochemical diversity and biological activities of J. thurifera essential oil (JTEO) through a comparative analysis of samples from two distinct regions: Tensift-Al Haouz and Azilal, using both in vitro and in silico methods. Gas Chromatography-Mass Spectrometry (GC-MS) analysis revealed 21 components in the Tensift-Al Haouz JTEO (99.99 % of the oil) and 23 components in the Azilal JTEO (99.58 % of the oil), with oxygenated monoterpenes being the predominant compounds in both. The biological activities were assessed in vitro. Antioxidant properties, evaluated using DPPH, FRAP, and ABTS assays, showed significant activity in both oils. Antibacterial activity was tested against two strains of Gram-positive and two strains of Gram-negative bacteria, with both oils demonstrating notable bacterial growth inhibition. Enzymatic assays assessed the antidiabetic (α-amylase and α-glucosidase), dermo-protective (tyrosinase and elastase), and neuroprotective (AChE and BChE) activities. Both oils displayed substantial inhibitory effects across all tested activities, with variations attributed to their distinct chemical compositions. In silico analyses of six target enzymes confirmed significant binding affinities of the major compounds. Notably, 2,2'-Thiobis(6-tert-butyl-p-cresol) exhibited strong binding affinities with AChE, BChE, α-amylase, α-glucosidase, tyrosinase, and elastase, with binding energies ranging from -10.0 to -6.2 kcal/mol. These findings indicate that JTEO is a rich source of bioactive compounds with promising potential in pharmacological and cosmetic applications.

Chemical composition and repellent effects of powders and essential oils from Juniperus oxycedrus, Juniperus phoenicea, and Juniperus thurifera against Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)

The present study evaluated the chemical composition and the potential repellent effect of powders and essential oils (EOs) from Juniperus oxycedrus, Juniperus phoenicea, and Juniperus thurifera against T. castaneum adults. The EOs were extracted by the hydrodistillation method, and their chemical composition was analyzed using gas chromatography-mass spectrometry (GC-MS) analysis. The repellent effect of powders and EOs was assessed using the area preference method. GC-MS revealed that the major components of the studied EOs were α-pinene (28.27%) and cubenol (10.75%) for J. phoenicea, β-Eudesmol (23.74%), hedycaryol (12.54%), and olopanone (10.04%) for J. oxycedrus, and oplopanone (26.84%) and α-Santanol acetate (17.28%) for J. thurifera. The powders of three Juniperus species had a repellent effect (class IV) against T. castaneum adults. Among the powders tested, J. phoenicea had the highest average repellency rate of 75.40%, followed by J. oxycedrus with 62.30%, and J. thurifera had the lowest average repellency rate of 60.30%. Moreover, J. phoenicea EO had the highest average repellency rate of 72.50%, followed by J. oxycedrus with 67.40%, while J. thurifera had the lowest average repellency rate of 61.80%.The potential of Juniperus species can be used as biopesticides to control T. castaneum infestations as an alternative to synthetic pesticides.

Stem Growth and Dehydration Responses of Mediterranean Tree Species to Atmospheric and Soil Drought.

Stem growth responses to soil and atmospheric drought are critical to forecasting the tree carbon sink strength. Yet, responses of drought-prone forests remain uncertain despite global aridification trends. Stem diameter variations at an hourly resolution were monitored in five Mediterranean tree species from a mesic and a xeric site for 6 and 12 years. Stem growth and dehydration responses to soil (REW) and atmospheric (VPD) drought were explored at different timescales. Annually, growth was determined by the number of growing days and hours. Seasonally, growth was bimodal (autumn growth ≈ 8%-18% of annual growth), varying among species and sites across the hydrometeorological space, while dehydration consistently responded to REW. Sub-daily, substantial growth occurred during daytime, with nighttime-to-daytime ratios ranging between 1.2 and 3.5 (Arbutus unedo ≈ Quercus faginea < Quercus ilex < Pinus halepensis in the mesic site, and Juniperus thurifera < P. halepensis in the xeric site). Overall, time windows favourable for growth were limited by soil (rather than atmospheric) drought, modulating annual and seasonal growth in Mediterranean species, and stems maintained non-negligible growth during daytime. These patterns contrast with observations from wetter or cooler biomes, demonstrating the growth plasticity of drought-prone species to more arid climate conditions.

Natural forest colonisation as a management strategy to restore soil functioning of abandoned agricultural lands

Abstract Land abandonment promotes forest expansion into abandoned agricultural lands in Europe. This process leads to changes that affect several ecosystem services, but it is considered a low‐cost strategy to restore soil functions in past agricultural lands. Soil microbial communities play a key role in restoring functions. However, the relationship among forest expansion, microbial communities, and soil functioning is unclear. In this study, we used a Juniperus thurifera expansion gradient on abandoned agricultural lands in Alto Tajo National Park (Spain) to discover the changes elicited by the soil microbial communities and their functions along this gradient considering two microhabitats, under the canopy and open areas. Specifically, our objectives were (i) to analyse how soil properties (organic matter and pH), microbial communities (using PLFAs‐NFLAs) and enzymatic activities (related to C, N and P cycling) varied along the forest expansion gradient and between microhabitats and (ii) to decipher the pathways by which soil properties control the carbon and nutrient cycling in soils. The forest expansion gradient had a direct negative effect on phosphatase activity. The microhabitat showed a positive direct effect on organic matter content, pH, actinomycetes and arbuscular mycorrhizal fungi biomass and on soil C and P cycling. Moreover, the biomass of gram‐positive bacteria determined the biomass of other microbial groups. Synthesis and Applications: Though its effectiveness is variable, passive restoration can be more effective than active restoration. Our research indicates that passive tree colonisation of past agricultural land is enough to achieve soil functionality similar to a mature forest for most variables studied. However, some variables would need more time to reach mature forest levels, such as total microbial biomass and organic matter content. Therefore, to support ecosystem recovery, the management of this applied forest ecology strategy requires continuous monitoring of newly established trees and soil to elucidate the time needed to achieve mature soil properties.

Spatial and Temporal Variation in the Antagonistic and Mutualistic Interactions among Seed Predator Arthropods, Seed-Dispersing Birds, and the Spanish Juniper.

Plants interact with both antagonistic and mutualistic animals during reproduction, with the outcomes of these interactions significantly influencing plant reproductive success, population dynamics, and the evolution of plant traits. Here, we investigated the spatial and temporal variations in the interactions between Juniperus thurifera, its seed-dispersing birds, and three specific arthropod species that attack the fleshy cones during the predispersal period. We assessed how plant traits affect levels of cone damage by arthropods and seed dispersal by birds, the occurrence of competition among arthropod species, and the impact of seed predators on the activity of frugivores. Plant traits, cone damage by arthropods, and seed dispersal by birds showed spatiotemporal variability. Fluctuation in cone abundance was the leading factor determining damage by arthropods and bird dispersal with a secondary role of cone traits. Large crops satiated predispersal seed predators, although the amount of frugivory did not increase significantly, suggesting a potential satiation of bird dispersers. Crop size and cone traits at individual trees determined preferences by seed predator species and the foraging activity of bird dispersers. Competition among arthropods increased during years of low cone production, and seed predators sometimes negatively affected bird frugivory. High supra-annual variations in cone production appear to be a key evolutionary mechanism enhancing J. thurifera reproductive success. This strategy reduces the impact of specialized seed predators during years of high seed production, despite the potential drawback of satiating seed dispersers.

Enhanced interannual drought resilience in mixed stands: unveiling possible complementarity effects between tree species of the Spanish Northern Plateau

AbstractClimate change is expected to intensify drought in the Mediterranean region. Previous studies indicate that tree species mixing may reduce the water stress. Our study investigates the response to past drought events of four co-occurring Mediterranean species: Pinus pinea L. (stone pine), Pinus pinaster Ait. (maritime pine), Juniperus thurifera L. (Spanish juniper) and Quercus ilex L (holm oak). The study was performed at an interannual scale, both in monospecific and mixed stands. Annual tree ring widths data measured on increment cores and stem discs obtained from 281 trees were used to quantify the responses to drought events using complementary resilience indices. Additionally, we assessed tree intra- and inter-specific competition impact over the past 25 years. We fitted and compared generalised linear mixed models to determine the influence of species identity, stand composition as intra-specific and inter-specific competition on complementary resilience indices and annual basal area increment. The co-existence with other species enhanced the resistance to drought of the stone pine as the resilience capacity of the Spanish juniper. Conversely, maritime pine’s drought resistance declined considerably in mixed stands. Notably, only the anisohydric species Spanish juniper and holm oak were able to return to pre-disturbance growth rates after the drought. The influence of competition on tree growth was found to differ according to the hydrological conditions of each year and varied based on the specific source of competition. Our study showed that mixed stands in the Spanish Northern Plateau, especially with holm oak and Spanish juniper, are more resilient to prolonged droughts due to spatio-temporal complementarity and subsequent competition reduction. That is another reason for which such composed mixed stands should be promoted in the arid conditions of the Spanish Northern Plateau.

Valorization of the Sabinas Forest Waste (Juniperus phoenicea and Juniperus thurifera) as Source of Biopesticides

Objectives: The potential forestry use of Juniperus phoenicea and Juniperus thurifera pruning woods is studied by analyzing the composition of the woods and testing the biological activities of the corresponding components with the ultimate target of finding new biopesticides. Methods: The air-dried wood from each plant was crushed and subjected to hydrodistillation, and the residue was extracted with a Soxhlet apparatus using different solvents. The corresponding extracts were fractionated, and their composition were studied by gas chromatography-mass spectrometry and nuclear magnetic resonance techniques. The ixodicidal and antifungal activities of the different samples obtained were evaluated. Results: The fraction oxygenated of the essential oil from both J. thurifera (cedrol &gt;60%) and J. phoenicea shows a remarkable bioactivity as antitick with EC50 values of 3.4 μg/mg and 10 μg/mg, respectively. Cedrol and methyl hinokiate, present in the hexane extract J. thurifera, show a potent antifungal effect against Aspergillus niger with EC50 values of 45.99 and 52.23 μg/mL, respectively. Conclusions: Pruning woods from these species proved to be renewable and easily accessible sources of bioactive natural products such as cedrol, thujopsene, nootkatone, and totarol.

Three systems of molecular markers reveal genetic differences between varieties sabina and balkanensis in the Juniperus sabina L. range

Key messageJ. sabina var. balkanensis, that is of hybrid origin, and its maternal progenitor J. sabina var. sabina are genetically distinct with respect to cpDNA, SNP, and SilicoDArT loci. Mostly non-overlapping distributions of the sabina and balkanensis varieties are the result of their different climatic requirements.ContextJuniperus sabina L. is present in the Eurasian mountains, but its range is severely fragmented. In Europe, two varieties of J. sabina occur: var. sabina and var. balkanensis, the latter being an allotetraploid hybrid between the diploid var. sabina and a tetraploid ancestor of Juniperus thurifera L. The distribution of the two varieties is mostly disjunct.AimsAssess the taxonomic affiliation and genetic differentiation of the populations of var. sabina and var. balkanensis in Europe and Asia using cpDNA, SilicoDArT, and SNP markers. Identify climatic niches of both juniper varieties in Europe.MethodsAltogether, 21,134 SilicoDArT, 8,579 SNP, and four cpDNA loci were used. Seven climatic variables were compared in sites inhabited by var. balkanensis and the two parental species.ResultsThe SilicoDArTs and SNPs revealed a pattern of population differentiation that was congruent with the cpDNA analysis. The hybrid var. balkanensis occupies habitats with higher temperatures and intermediate levels of precipitation compared to both parental taxa.ConclusionThe low genetic variation and significant genetic differentiation among J. sabina populations likely result from the restriction of gene flow imposed by the mountain ranges. The balkanensis variety is able to cope with hot and dry climates probably thanks to the admixture of J. thurifera genes.

Topoclimatic modulation of growth and production of intra-annual density fluctuations in Juniperus thurifera

Forest growth is driven by climate variability at continental to regional scales, but other factors play major roles at local scales (0.1–1 ha). Topography impacts on tree growth responses to climate stressors, including drought, by modifying radiation, evapotranspiration rates and the access to soil moisture. However, there is a lack of studies investigating how topographical factors (elevation, aspect, slope) affect climate-growth relationships considering both continuous (tree-ring width) and discrete wood-anatomical features (e.g., intra-annual density fluctuations–IADFs). Here, we investigated how topography modulated the influences of climate and drought on semi-arid Juniperus thurifera forests from north-eastern Spain. We compared two stands located in valley bottoms and two stands located in steep slopes. Radial growth was measured using dendrochronology which also allowed quantifying latewood IADFs. A proxy of topographic influence (incident radiation) was calculated. In addition, the Vaganov-Shashkin (VS) model was used to infer the main climatic constraints of growth at intra-annual scales. We found that junipers growing in valley bottoms were taller and produced more IADFs than junipers growing in steep slopes, but responded less to precipitation variability. This was confirmed by the VS model which showed that low soil moisture in June limited growth, particularly in steep-slope sites and during dry periods. Wet-cool late-summer conditions induced the formation of IADFs. The topoclimatic modulation of growth was explained by the interaction between incident radiation and tree age. Furthermore, climate-growth associations are changing as temperatures rise. Drought impacts on growth are strengthening, but less responsive junipers growing in valley bottoms may be buffered against intensified aridification.

Removal of Phenol from Water Using an Activated Carbon Prepared from Juniperus Thurifera Tree

The present paper aims to study the feasibility of using an activated carbon prepared by Juniperus thurifera tree as an adsorbent to remove phenol from water by adsorption. The impact of initial phenol concentration, contact time, pH, and adsorbent mass on phenol adsorp-tion capacity was investigated. It was reported that the highest adsorption capacity is achieved at pH=3.4, phenol concentration of 50 mg/L, adsorbent mass of 100 mg, and time 24 h. Freundlich, Langmuir, and Temkin isotherm equations were used to best fit our experimental data. Hence, Freundlich model was found to be the best model with R2 = 0.9893. The thermodynamic results revealed that the adsorption of phenol onto the activated carbon was spontaneous and exothermic. Furthermore, the adsorption kinetic study indicated that the adsorption process follows the pseudo-first-order kinetic model.

Effect of geographical origin on yield and secondary metabolite content of extracts of Moroccan Juniperus thurifera

The thuriferous juniper (Juniperus thurifera) is an important species in the Mediterranean region due to its ecological and economic values. It plays a significant role in preventing soil erosion and desertification, as well as being used in traditional medicine and as a source of essential oils for various industries. In addition, its extracts are considered as a source of bioactive compounds with various pharmacological activities, such as antioxidant, anti-inflammatory and antimicrobial effects. However in Morocco, it is considered as one of the undervalued and least preserved species. Its stands continue to be vigorously degraded. The present work aims to study the effect of the origin on the yield, the phenolic compounds, flavonoids and tannins contents and the antioxidant activity of the leaves extracts of this species. In order to accomplish this study, we carried out the extraction by soxhlet from the leaves of J. thurifera, coming from three geographical origins, using two solvents (hexane and ethanol). Then the dosage of different compounds (polyphenols, flavonoids and condensed tannins) and the evaluation of the antioxidant activity were carried out. The results show a significant variability between the samples coming from three different biogeographical zones, namely: the Eastern, Central and Western High Atlas in terms of yield and levels of polyphenols, flavonoids and condensed tannins. This allowed to demonstrate the effect of geographical origin and the interaction between environmental conditions and genotype on the production of secondary metabolites. In fact, we found that the Midelt population has a good yield in ethanolic extracts (9.41% ± 0.59) and hexane 6.57% ± 0.29. Furthermore, the El Haouz population is the richest in polyphenols in ethanolic extracts (191.30 ± 4.27 mg GAE /g Extract), as well as it has an important reducing potential (IC50 = 0.98 ± 0.05 mg/ml). These results can be exploited as bioindicators in all programs of valorization and conservation of Moroccan Juniperus thurifera

Promising antioxidant and antimicrobial effects of essential oils extracted from fruits of Juniperus thurifera: In vitro and in silico investigations

Abstract The objective of this work was to characterize the phytochemical composition of essential oil from Juniperus thurifera (L.) fruits (EOFT) and study its antioxidant, antibacterial, and antifungal effects. EOFT was extracted by hydrodistillation and fingerprinted by using GC–MS. The antioxidant effect of EOFT was evaluated using 2,2-diphenylpicrylhydrazyl (DPPH), ferric iron reduction assay (FRAP), and total antioxidant capacity (TAC) assays. Importantly, the antimicrobial activity of EOFT was performed against Candida albicans, Aspergillus niger, Aspergillus flavus, Fusarium oxysporum, Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Proteus mirabilis. In addition, the inhibitory capacity of NADPH oxidase and human acetylcholinesterase was also investigated using molecular docking. The results of the chemical composition reveal that EOFT constituted 11 terpenic compounds with dominance of elemol (33.86%), terpinen-4-ol (27.80%), and cryptomeridiol (18.36%). The antioxidant power of EOFT recorded IC50 values of 197.07 ± 0.09 μg/mL (DPPH) and 216.34 ± 0.06 μg/mL (FRAP), while TAC of EOFT was determined to be 181.06 μg AAE/mg. The antibacterial potency on solid medium revealed that EOFT induced inhibition zone diameters reaching 14 mm, and a minimum concentration up to 2.78 µg/mL against the studied bacterial strains. The EOFT also showed an important antifungal effect as the inhibition reached 42%, and the MIC was between 7.50 and 22.25 µg/mL. The in silico study showed that o-Cymene was the most active molecule against NAD(P)H oxidase followed by cadinol with a Glide score of −5.344 and −5.143 kcal/mol, respectively. Due to their promising results, the outcome of this work suggests that EOFT could be used as an interesting natural weapon to control microbial and freed radical-related diseases.

Geographical distribution of the Thuriferous juniper (Juniperus thurifera L.) and the influencing factors in the Atlas Mountains of Azilal (Central High Atlas, Morocco)

ABSTRACT The present study describes the contribution of geomatic science in mapping and determining the factors influencing the spatial distribution of Juniperus thurifera in the high mountains of Azilal, Morocco. The methodology adopted is based on the use of a Landsat 8 OLI satellite image to determine the spatial distribution of J. thurifera and a WorldClim database to extract the climat conditions.The Digital Elevation Model (DEM) of 30 m resolution was used to derive the topographic parameters. The geological map was digitized and used to derive the different lithological classes. The results obtained show that the J. thurifera tree is distributed in four distinct biogeographic zones (Ait Bouguemez, Zaouit Ahansal, Anergui and Tifirt N'ait Hamza). It is mainly found on the North and/or West-facing aspect at altitudes ranging from 1600 to 3400 m, and on moderate-to-high slopes. It develops with a predominance of limestone, marl-limestone, and sandstone. It prefers areas withclimate types: cold to very cold semi-arid and cold to very cold subhumid. Well-preserved J. thuriferastands can only be observed in certain regions.. These results can be useful in selecting potential sites for reforestation of J.thurifera in similar terrain conditions to develop and manage this species in mountainous areas.

Comparative Analysis of Ethanolic Juniperus Thurifera Leaf, Stem Bark and Root Extract Using Gas Chromatography and Mass Spectrometry

Medicinal plants are reservoir of bioactive compounds or phytochemicals (terpenoids, alkaloids, tannins, flavonoids and so on) with marked pharmacological properties such as; antimicrobial, antioxidant, anti-inflammatory, antibacterial, analgesics, antiprotozoal, cytotoxic, anti-androgenic, antiviral, antipyretic, antitumor, anti-depressant, hypolipidemic and antihelminthic activities. This study was designed to examine the comparative analysis of ethanolic Juniperus thurifera leaf, stem bark and root extract using gas chromatography and mass spectrometry. Result obtained shows that Juniperus thurifera leaf extract contained 33 bioactive compounds which accounts to 75.47 % while Juniperus thurifera stem bark and root extract contained 37 and 50 phytochemicals with an aggregate of 80.77 % and 93.07 % respectively. Monoterpenes hydrocarbon (40.50 %), oxygenated monoterpenes (12.66 %), sesquiterpenes hydrocarbon (13.79 %) and oxygenated sesquiterpenes were found in Juniperus thurifera leaf extract while Juniperus thurifera stem bark and root extract contains monoterpenes hydrocarbon (48.72 %, 51.33 %), oxygenated monoterpenes (14.88 %, 20.49 %), sesquiterpenes hydrocarbon (10.71 %, 14.25 %) and oxygenated sesquiterpenes (6.56 %, 7.88 %) respectively. It was concluded that Juniperus thurifera leaf, stem bark and root ethanolic extract contains several secondary metabolites which can be used for the treatment of diseases without causing any deleterious effect on the environment and general performance of animals.

Increased recovery in coarse‐root secondary growth improves resilience to drought in transition forests

Abstract Interaction of global change drivers affects forest resilience. Land‐use changes (land abandonment) and climate change (a higher frequency and intensity of droughts) are interacting in the Mediterranean Region. Components of resilience in secondary stem growth have been widely studied but, despite the importance of root systems in forest functionality and resilience, non‐previous studies have assessed them in coarse roots. In this study, we use Juniperus thurifera tree‐ring chronologies in coarse roots and stems to assess biomass allometry and tree resilience to drought events comparing two stages of a forest expansion gradient (mature forests and transition zone) in Alto Tajo Natural Park. We extracted cores of stems and coarse roots in 48 trees distributed in different developmental stages and calculated cross‐sectional area increments, root‐stem allometric relationship and resilience components for both organs in each individual for two drought events (2005 and 2012). Stem and root growth as well as its allometric exponent were higher in the transition zone than in mature forests. Both organs exhibited a trade‐off between resistance and recovery in mature forests but maintenance of higher values in the transition zone. Resilience did not show differences between organs being higher in the transition zone than in mature forests. However, relative resilience in roots in the transition zone was higher than in mature forests, without differences in stems between stages. Finally, the 2012 drought event showed a higher impact on the components of resilience than the 2005 drought event. Synthesis. This study extends the knowledge of root response to drought events and highlights the potential of land‐use legacies to reduce the negative impact of climate change by promoting increased root recovery after drought events in trees established in past agricultural lands.

GC-MS Profiling, In Vitro Antioxidant, Antimicrobial, and In Silico NADPH Oxidase Inhibition Studies of Essential Oil of Juniperus thurifera Bark.

Juniperus thurifera is a native species to the mountains of the western Mediterranean region. It is used in traditional medicine as a natural treatment against infections. The present study aimed to carry out the chemical analysis and evaluate the antioxidant, antimicrobial, as well as in silico inhibition studies of the essential oils from Juniperus thurifera bark (EOEJT). Chemical characterization of EOEJT was done by gas chromatography (GC-MS). We have performed three antioxidant assays (Reducing power (FRAP), 2, 2-diphenylpicrylhydrazyl (DPPH), and total antioxidant capacity (TAC)) of the EOEJT. We next evaluated the antimicrobial activity against in silico study, which was carried out to help evaluate the inhibitory effect of EOEJT against NADPH oxidase. Results of the GC/MS analysis revealed seven major compounds in EOEJT wherein muurolol (36%) and elemol (26%) were the major components. Moreover, EOEJT possessed interesting antioxidant potential with an IC50 respectively of 21.25 ± 1.02 μg/mL, 481.02 ± 5.25 μg/mL, and 271 μg EAA/mg in DPPH, FRAP, and total antioxidant capacity systems. Molecular docking of EOEJT in NADPH oxidase active site showed inhibitory activity of α-cadinol and muurolol with a glide score of −6.041 and −5.956 Kcal/mol, respectively. As regards the antibacterial and antifungal capacities, EOEJT was active against all tested bacteria and all fungi, notably, against Escherichia coli K12 with an inhibition diameter of 21 mm and a MIC value of 0.67 mg/mL, as well as against Proteus mirabilis ATCC 29906 with an inhibition diameter of 18.33 ± 1.15 mm and a MIC value of 1.34 mg/mL. A more pronounced effect was recorded for the fungal pathogens Fusarium oxysporum MTCC 9913 with inhibition of 37.44 ± 0.28% and MIC value of 6.45 mg/mL, as well as against Candida albicans ATCC 10231 with an inhibition diameter of 20.33 ± 1.15 mm and a MIC value of 0.67 ± 0.00 mg/mL. Altogether, these results highlight the importance of EOEJT as a source of natural antibacterial and antioxidant drugs to fight clinically important pathogenic strains.

Why Intra-Annual Density Fluctuations Should Be Formed at Night? Implications for Climate–Growth Relationships in Seasonally Dry Conifer Forests

Trees grow at night, when the vapor pressure deficit (VPD) is low enough. Therefore, intra-annual density fluctuations (IADFs) should be formed when the VPD drops below a certain threshold. This idea is tested by assessing climate-latewood IADF relationships in six conifer species under Mediterranean climate conditions. Hourly climate and dendrometer data were analyzed for years with elevated IADF production in two species (Pinus halepensis, Juniperus thurifera). Lastly, climate–growth relationships were evaluated in two drought-prone sites to assess the relative role of minimum vs. maximum temperatures as growth drivers. Latewood IADF production was positively related to growth rate. IADFs were more abundant when monthly or 10-day long precipitation was high in the late growing season (August and September). According to dendrometer data, growth mainly occurred in early night (20–2 h) and early morning (6–8 h). This growth window corresponded to rainy periods with VPD below a minimum threshold associated with summer storms. Latewood IADFs are produced in response to these wet late-summer conditions, which could be related to bimodal growth. These associations are in line with correlations showing that high minimum (night) rather than maximum (day) temperatures reduce growth. This last idea should be further checked in drought-prone forests using global tree-ring databases.

Early Differentiation of the Phenotypic Space and Performance of Juniperus thurifera Across Woodland-Expanding Areas

Forest expansion after rural abandonment is changing landscapes, bringing new challenges and opportunities. Juvenile performance has an effect in the establishment of new forests and the subsequent acclimation of adult trees. However, most studies have focused on the performance of adult trees. Here, we analysed differences in the phenotypic trait space of juveniles across gradients of Juniperus thurifera woodland expansion and explored which traits shape juveniles’ performance, seeking specific drivers of such differentiation and the role of the ontogeny. Thus, we surveyed functional leaf and plant-size traits in 180 juveniles growing in 18 plots at three different tree density stages (mature woodland, recently established area and a transition zone between both) and recorded local environmental conditions around each individual. We also estimated their radial growth and resilience to drought (in terms of resistance, recovery and resilience) as performance indicators. We found no relevant effects of the study environmental variables, but we did find a shift in the phenotypic space among juveniles across the gradient, with taller crowns and higher amount of leaf N and δ13C at the expanding edge. This trait differentiation across the gradient implied higher performance of young trees growing in old agricultural fields, both in growth rate and drought resilience terms. Our results showed a relevant land-use legacy on early trait differentiation that shapes more efficient phenotypes in the expanding edge compared to those in mature woodlands, suggesting that the future of these new forests is not compromised under current conditions.

Comparative Analysis of Ethanolic Juniperus Thurifera Leaf, Stem Bark and Root Extract Using Gas Chromatography and Mass Spectrometry

Medicinal plants are reservoir of bioactive compounds or phytochemicals (terpenoids, alkaloids, tannins, flavonoids and so on) with marked pharmacological properties such as; antimicrobial, antioxidant, anti-inflammatory, antibacterial, analgesics, antiprotozoal, cytotoxic, anti-androgenic, antiviral, antipyretic, antitumor, anti-depressant, hypolipidemic and antihelminthic activities. This study was designed to examine the comparative analysis of ethanolic Juniperus thurifera leaf, stem bark and root extract using gas chromatography and mass spectrometry. Result obtained shows that Juniperus thurifera leaf extract contained 33 bioactive compounds which accounts to 75.47 % while Juniperus thurifera stem bark and root extract contained 37 and 50 phytochemicals with an aggregate of 80.77 % and 93.07 % respectively. Monoterpenes hydrocarbon (40.50 %), oxygenated monoterpenes (12.66 %), sesquiterpenes hydrocarbon (13.79 %) and oxygenated sesquiterpenes were found in Juniperus thurifera leaf extract while Juniperus thurifera stem bark and root extract contains monoterpenes hydrocarbon (48.72 %, 51.33 %), oxygenated monoterpenes (14.88 %, 20.49 %), sesquiterpenes hydrocarbon (10.71 %, 14.25 %) and oxygenated sesquiterpenes (6.56 %, 7.88 %) respectively. It was concluded that Juniperus thurifera leaf, stem bark and root ethanolic extract contains several secondary metabolites which can be used for the treatment of diseases without causing any deleterious effect on the environment and general performance of animals.

What happens to species at the rear‐edge of their distribution in arid regions? The case of Juniperus thurifera L. in the Aurès Mountains (Algeria)

AbstractAlgerian populations of Juniperus thurifera are the most restricted in terms of distribution and the least studied among all populations of the entire range of the species in the western Mediterranean region. Although this species is regarded as being of least concern according to the International Union for Conservation of Nature (IUCN), many studies have pointed to the need for its conservation, especially in North Africa, where populations are fragmented and the potential for regeneration is reduced. Understanding the current range of distribution of J. thurifera in Algeria and the environmental factors responsible for this is of key importance for the protection and restoration of these populations. In the present study, a maximum entropy approach (MaxEnt) was used to model the distribution of J. thurifera. Thirty occurrence records were analyzed in combination with climatic, topographic, and anthropogenic predictors at two different spatial resolutions (900 m and 30 m). The best‐performing model included climatic, topographic, and anthropogenic predictors, suggesting that the distribution of the species is influenced by a combination of factors, while the performance of climatic and topographic models was similar. The most important predictors of the occurrence of Algerian J. thurifera are water‐related factors. However, when considering only topographic variables, altitude has a huge impact. Finally, using improved resolution for modeling distribution enhanced the prediction capability of the model (AUC = 0.942). The findings of the present study confirmed the resilience of J. thurifera, and highlighted the tolerance to drought of Algerian populations.