Sub-humid Bioclimate Research Articles

The Influence of Bioclimates and Soil Physicochemical Properties on Bacterial and Archaeal Communities from Forest Ecosystems in Côte d’Ivoire (West Africa)

Archaea and bacteria communities play pivotal roles in tropical forest ecosystems’ functioning, especially nutrient cycling, plant phenology, and health. The objective of this study was to explore the diversity of archaeal and bacterial communities in forest soil ecosystem of Côte d’Ivoire and to identify abiotic factors that influence their composition. Using high-throughput amplicon sequencing targeting the V4V5 hypervariable region of the 16S ribosomal RNA gene, we analyzed 22 soil samples taken from the 2 main forest areas of Côte d’Ivoire, namely the semi-deciduous moist forest and the evergreen moist forest, both of which are located in the humid and sub-humid areas of the country. The analysis revealed that the biodiversity at the phyla level was congruent with previous studies. Richness and Shannon diversity indices revealed the dominance of bacteria over archaea in all studied soils. Moreover, the predominant bacterial community consisted of Proteobacteria (29.8%), Acidobacteria (15.5%), and Actinobacteria (14.2%), while the archaeal community was dominated by Thaumarchaeota (1.93%). However, at the genus level, patterns emerged. The most abundant and ubiquitous members at the genus level included Bradyrhizobium, Rhodoplanes, Bacillus (bacteria), and Nitrosophaera (archaea). While bacterial core microbiome members were found in almost all soils, Nitrososphaera genus were selective to sub-humid bioclimate and cropland land use. These patterns were correlated to the soils’ physicochemical characteristics, bioclimate, and land use. This study sheds light on the intricate relationships between abiotic factors and microbial communities in Côte d’Ivoire’s forest soils and helps to identify keys species for future soil management.

Interspecific variability of 1,8-cineole content, phenolics and bioactivity among nine Eucalyptus taxa growing under the sub-humid bioclimate stage.

Background Eucalyptus essential oils and extracts are used since the ancient times in alternative medicine. The 1,8-cineole is the most significant constituent of Eucalyptus essential oil, while phenolic contents define the value of eucalyptus extracts. Based on the last considerations, interspecific variability of 1,8-cineole content, phenolics and antioxidant potentials among nine Eucalyptus taxa growing under the sub-humid bioclimate stage of Tunisia was investigated. Methods Essential oil profiling was assessed based on gas chromatography-mass spectrometry analysis. Total phenolic and flavonoid contents were assessed using Folin-Ciocalteau and aluminium chloride colorimetric methods, respectively. The antioxidant ability of Eucalyptus volatile metabolites and extracts was achieved based on two test systems namely DPPH and FRAP assays. Results Qualitative and quantitative variations in the composition of essential oils according to the studied taxon were shown. The total phenolic and flavonoid contents varied also significantly among the investigated samples. Based on the obtained results, the species Eucalyptus sideroxylon exhibits the highest 1,8-cineole content (76.24 ± 0.86), total phenolics and flavonoids contents (38.5 ± 1.4 mg GAE /g DW and 18.6 ± 0.3 mg RE /g DW, respectively). Moreover this species highlighted the highest free radical-scavenging ability and ferric reducing power for both essential oil and methanolic extracts. Chemometric multivariate analysis showed the classification of the nine studied taxa to three clusters. Conclusions The pattern of 1,8-cineole concentration, phenolic and flavonoid contents for the studied nine Eucalyptus species and hybrid showed E. sideroxylon species as the potential candidate for further improvement strategies regarding the production of eucalyptus essential oils and phenolics with high quality for pharmaceutical industry.

Evaluation of the Productivity Potential of Contemporary G.arboreum Cotton Genotypes on Vertic Haplustepts under Rainfed Conditions

Gossypium arboretum L. (desi cotton) possesses several useful traits like high ginning percentage tolerance to drought and salinity, make more suitable for cultivation under low input conditions. Apart from being more resilient to climate change and the low cost of cultivation, the availability of new varieties with excellent fibre quality and good locule retention makes desi cotton more attractive and remunerative to farmers. A field experiment was conducted during the Kharif season of 2019-20 to evaluate the productivity potential of some promising contemporary G. arboreum genotypes and understand their response to sowing dates and planting density under rainfed conditions under dry sub-humid bio-climate.The soil was clayey in texture, moderately alkaline, moderately shallow, 60 cm in depth, and is classified as clayey, smectitic hyperthermic family of Vertic Haplustepts. Results indicated that the sowing date had a significant influence on seed cotton yield, days to first flower and boll weight. Plant density had a significant effect on boll weight, plant height, and boll number m-2 but not on seed cotton yield. The genotypes differed significantly with respect to days to first flower, plant height, boll number m-2, boll weight and seed cotton yield. Genotypes PA-528 and PA-812 were the highest yielders. Genotypes PA-812 and PA- 760 were superior in terms of fibre quality. A delay in sowing by 15 days significantly reduced the yield of G. arboreum cultivars by 142 kg ha-1.A significant interaction observed between plant density and genotypes necessitates a need to evaluate the elite G. arboreum cultivars at specific plant density to exploit their productivity potential.

Comunidades de orla forestal en el suroeste de la península ibérica

Introduction: Forest and pre-forest fringe communities in the southwest of the Iberian Peninsula are semi-shaded perennial herbs of external fringe and open areas of evergreen or semi-deciduous woodlands and their pre-forestry mantles, linked to the Stachyo lusitanicae-Cheirolophenion sempervirentis suballiance. Objective: To evaluate the chorology, ecological features and floristic circumscription of the forest fringe communities of the southwestern Iberian Peninsula. Materials and methods: Forest fringe communities adscribed to the Stachyo lusitanicae-Cheirolophenion sempervirentis suballiance were analysed, using phytosociological approach (Braun-Blanquet methodology) and numerical analysis (hierarchical cluster analysis). Results and discussion: The statistical and phytosociological analysis of six formerly described associations and the samples of this study lead us to propose a new forest fringe association: Picrido spiniferae-Cynarietum algarbiensis, dominated by Cynara algarbiensis Coss. ex Mariz. This forest fringe community is characteristic of the thermomediterranean to mesomediterranean, lower sub-humid bioclimate and occurs in the potential areas of the Quercus suber L. forests (Lavandulo viridis-Quercetum suberis), mainly in the Monchique Sierran District. Conclusion: The statistical and phytosociological analysis were useful in the evaluation of forest fringe communities in the southwest of the Iberian Peninsula. Regarding the proposal of the new association Picrido spiniferae-Cynarietum algarbiensis, it is important to develop management strategies for the preservation of the endemic C. algarbiensis. Keywords: Stachyo lusitanicae-Cheirolophenion sempervirentis suballiance; phytosociology; Cynara algarbiensis; endemic flora; cluster analysis

Croissance radiale et réponse au climat du pistachier de l’Atlas (Pistacia atlantica Desf.) dans le Parc national de Theniet El Had (Algérie)

En Afrique du Nord, l’aire de répartition du pistachier de l’Atlas s’étend depuis l’Atlas tellien, où il se mêle au cèdre de l’Atlas, jusqu’au Sahara central où il côtoie l’acacia. Il possède une amplitude écologique remarquable et paraît candidat à une extension spatiale, à la faveur du réchauffement climatique. Après avoir rendu compte, dans un précédent article, des relations cerne-climat de cet arbre selon un gradient d’aridité, le présent travail concerne le déterminisme climatique de sa croissance radiale en milieu forestier, sous bioclimat subhumide. L’étude a été réalisée à Djebel Meddad sur deux expositions (nord et sud). L’analyse de la réponse aux événements climatiques extrêmes par le calcul des années caractéristiques révèle que le pistachier de l’Atlas est plus sensible aux événements extrêmes dans les expositions chaudes que fraîches, plus particulièrement aux événements qui inhibent la croissance. Les sensitivités moyennes sont très proches sur les deux versants mais restent faibles par rapport à celles obtenues dans les régions arides et semi-arides. L’analyse des indices de croissance montre que tous les cernes minces ou épais correspondent à des conditions particulièrement sèches ou pluvieuses. Les températures moyennes annuelles n’ont qu’un effet complémentaire. Aucun cerne extrêmement mince n’est enregistré au niveau des deux versants. Les fonctions de réponse montrent que les facteurs climatiques de l’année en cours jouent un rôle majeur dans la construction du cerne.

Chemical composition and antibacterial activities of seven Eucalyptus species essential oils leaves.

BackgroundIn this paper, we have studied the essential oils chemical composition of the leaves of seven Eucalyptus species developed in Tunisia. Eucalyptus leaves were picked from trees growing in different arboretums in Tunisia. Choucha and Mrifeg arboretums located in Sedjnene, region of Bizerte (Choucha: E. maideni, E. astrengens et E. cinerea; Mrifeg : E. leucoxylon), Korbous arboretums located in the region of Nabeul, North East Tunisia with sub-humid bioclimate, (E. lehmani), Souiniet-Ain Drahem arboretum located in region of Jendouba (E. sideroxylon, E. bicostata). Essential oils were individually tested against a large panel of microorganisms including Staphylococcus aureus (ATCC 6539), Escherichia coli (ATCC 25922), Enterococcus faecalis (ATCC29212), Listeria ivanovii (RBL 30), Bacillus cereus (ATCC11778).ResultsThe yield of essential oils ranged from 1.2% to 3% (w/w) for the different Eucalyptus species. All essential oils contain α-pinene, 1,8-cineol and pinocarveol-trans for all Eucalyptus species studied. The 1,8-cineol was the major compound in all species (49.07 to 83.59%). Diameter of inhibition zone of essential oils of Eucalyptus species varied from 10 to 29 mm. The largest zone of inhibition was obtained for Bacillus cereus (E. astrengens) and the lowest for Staphylococcus aureus (E. cinerea). The essential oils from E. maideni, E. astrengens, E. cinerea (arboretum of Bizerte), E. bicostata (arboretum of Aindraham) showed the highest antibacterial activity against Listeria ivanovii and Bacillus cereus.ConclusionThe major constituents of Eucalyptus leaves essential oils are 1,8-cineol (49.07 to 83.59%) and α-pinene (1.27 to 26.35%). The essential oils from E. maideni, E. astrengens, E. cinerea, E. bicostata showed the highest antibacterial activity against Listeria ivanovii and Bacillus cereus, they may have potential applications in food and pharmaceutical products.

Distribution and phytogeographical analysis of Quercus ithaburensis ssp. macrolepis in Greece

Cet article présente la distribution de Q. ithaburensis ssp. macrolepis en Grèce, ses conditions écologiques de base, telles que les caractéristiques du substrat et du sol, la topographie, les facteurs climatiques et bioclimatiques et des spectres chorologiques et des formes de vie. Les données ont été collectées à l’aide des questionnaires, envoyés à tous les services forestiers du pays et complétés par des observations et mesures sur le terrain. Les résultats montrent que Q. ithaburensis ssp. macrolepis couvrent une superficie de 29 631,8 ha, en formations forestières, dans les zones de plaines et semimontagneuses de la Grèce continentale et insulaire. Il est encore présent sous la forme d’arbres isolés dans plusieurs régions du pays. La sous-espèce se développe sur divers types de substrat et de sols avec des inclinaisons et expositions diverses, et sous différents types de bioclimats méditerranéens. Elle préfère des régions à basse et moyenne altitude, en bioclimat subhumide, sur des sols calcaires peu ou moyennement profonds. Tous ces critères combinés aux activités humaines influencent les structures de végétation dans chaque région. En raison du climat et des divers types d’interventions humaines, les éléments méditerranéens dominent. C’est seulement dans les forêts du nord du pays, que le pourcentage des éléments subméditerranéens augmente considérablement. En générale les forêts de Q. ithaburensis ssp. macrolepis sont caractérisées par la dominance des thérophytes.

Variabilité génétique des populations tunisiennes de Myrtus communis L. (Myrtaceae) estimée par des marqueurs isoenzymatiques et moléculaires (RAPD)

The genetic variation of six Tunisian Myrtus communis L. (Myrtaceae) populations was assessed using nine isozymes coding for 17 putative loci and 79 RAPD markers, amplified by five decamer random primers. The analysed populations belonged to three bioclimatic zones (lower humid, sub-humid and upper semi-arid). A high genetic diversity within populations was detected both by isozymes and RAPDs. The level of variation differed according to bioclimate. Populations collected from sub-humid bioclimate showed more polymorphism than those grown in the upper semi-arid zone. For all populations, the genetic diversity revealed by RAPDs was more pronounced than that detected with isozymes. A high differentiation among populations related to bioclimate and geographic distance was revealed by both methods. Population’s structure based on RAPD markers was more concordant with bioclimatic zones in comparison with isozymes. Differentiation between ecological groups was higher than that revealed within groups. Conservation programs should take into account the level of genetic diversity within population revealed by the two complementary classes of markers according to bioclimate.