Androstachys Research Articles

Allelopathic effects of Androstachys johnsonii Prain on germination and growth of Zea mays L. and Vigna subterranea (L.) Verdc.

Allelopathic effects of the donor plants are mostly regarded as harmful to target plants such as traditional crops. Traditional crops play pivotal role as staple food for rural communities and hence ensuring food security. Study of the allelopathic effects of Androstachys johnsonii Prain on the germination and growth of Zea mays L. and Vigna subterranea (L.) Verdc was conducted. Different plant leachates concentrations of 0.675%, 1.25%, 2.5% and 5% were prepared through serial dilutions. Germination bioassays were arranged in a complete randomized setup of three replicates for each treatment for seven days. Germination rates were calculated, radicle and hypocotyl lengths were also measured. Germination rates of Z. mays L. and V. subterranea (L.) Verdc. ranged from 50 - 100% and 18 - 76%, respectively. Significant differences of P< 0.005 were noticed from the germination rates of V. subterranea (L.) Verdc subjected to high concentrations of different extracts used. Statistically there was no significant differences between germination rates of Z. mays L. treated with all concentrations of leaf leachates against germination rates of the seeds treated with distilled water. Outstandingly, the germination rate and early growth of Z. mays L. were promoted by less concentrated extracts of leaf, root, stem bark and soil which then suggest future use of allelochemicals from Androstachys johnsonii Prain for promotion of maize plant productions. Based on the beneficial attributes of allelochemicals from Androstachys johnsonii on the germination and growth of Z. mays L., planting of Androstachys johnsonii Prain in maize fields is highly recommended.

Characterization of the Arboreal Flora of Two Provinces in South of Mozambique

This study was carried out in two provinces in the south of Mozambique to characterize the structure and the floristic composition of the arboreal flora. 134 plots of 10020 m and 93 plotswerea random sampling allocated in Gaza and Inhambane province, respectively. The tree with DBH equal or superior than 10 cm were identified and measured. The results in Gaza province shows that a total of 2593 trees were measured corresponding to 106 tree species, 25 botanical families and 54 genus. The most important species in this province were Colophospermum mopane, Guibourtia conjugata, Androstachys johnsonii, Spirostachys africana, Acacia burkei, Combretum zeyheri, Combretum molle, Sclerocarya birrea, Strichynos madagascariensis and Terminalia sericea. In Inhambane province, 2556 trees were measured distributed to 108 species, 30 botanical families and 58 genus. The most important species in this province were Brachystegia spiciformis, Colophospermum mopane, Androstachys johnsonii, Spirotachysafricana, Guibourtiaconjugata, Acacia nigresscens, Sclerocarya birrea, Margaritariadiscoidea, Brachystegia manga and Pteleopsis mytifolia. The diversity of the Inhambane forest was larger than the one of the Gaza forest (index of Shannon = 3.36, Pielou index = 0.72 and 3.09, Pielou index = 0.66, respectively). The Index of Jaccard and Sorensen revealed low similarity among the two forest. The specificity of identified species in each province can be used to define restoration and conservation strategies of the south of Mozambique.

Effects of site and tree size on wood density and bark properties of Lebombo ironwood (Androstachys johnsonii Prain)

Background: Wood and bark are important renewable natural resources. Density is an important property that is used to describe wood and bark quality for a number of end uses. However, wood and bark density, bark proportion and dimensions vary with age and site, as well as among and within trees. The aim of this study was to investigate the effect of site, diameter class, and vertical position within the stem on the density of wood and bark, bark volume, bark dry-mass and thickness of Lebombo ironwood (Androstachys johnsonii Prain). Methods: The study was conducted on 93 Lemombo ironwood trees growing in Mozambique. Eight discs were sampled from each selected tree and diameter over and under bark was measured. Bark thickness, bark mass and bark density were determined along with the basic wood density of each disc. Results: The overall average whole-stem properties were estimated at: 786 kg m–3 wood density, 586 kg m–3 bark density, 19% bark volume, 19% bark dry-mass, and 9 mm bark thickness. Height level uniquely explained most of the variation in bark mass (97%), bark volume (95%) and wood density (86%). Diameter class explained most of the variation in bark density (51%) and bark thickness (51%). Site only explained a small proportion of the variation in all dependent variables. Conclusions: Overall, the patterns of variation of all wood and bark properties were highly dependent on tree diameter class and vertical position within the stem. Site differences were not a significant source of variation in the properties studied. Improved knowledge of the wood and bark properties of this species will aid its sustainable management and utilisation.

Impact of carbonization parameters on anatomic aspects and near-infrared spectra of three species from Mozambique

This study characterizes charcoal from Androstachys johnsonii (Picrodendraceae), Bobgunnia madagascariensis (Fabaceae) and Sterculia quinqueloba (Malvaceae), made by different carbonization processes, based on wood anatomy and NIR spectroscopy to verify the impact of the parameters and contribute to a database for charcoal identification and control. In the three species analyzed, changes in anatomical characteristics after carbonization were different and formed groups regarding charcoal programs as a result of anatomical and chemical characteristics. In vessel and ray dimensions and frequency, no linear relation to total time or final carbonization temperature was observed, although there were some interactions between species and program conditions. In the near-infrared spectra, the region from 4000 to 5000 cm−1 showed more distinction between the charcoal programs. There was a separation of samples carbonized with lower intensity (400 °C and 40 min), denoting minor chemical degradation of species, from samples submitted to other programs with a final temperature of 450 °C and total time between 2 and 6 h. Near-infrared spectroscopy showed potential to discriminate species in different carbonization processes. Final temperature had a stronger influence on species distinction than the total processing time.

Impact of Ethnobotanical Utilization on the Population Structure of Androstachys Johnsonii Prain. in the Vhembe Area of the Limpopo Province, South Africa

Due to high levels of impoverishment, rural communities in southern African are highly dependent on their surroundings to sustain their livelihood. However, the rampant harvesting of Androstachys johnsonii Prain. In Vhembe area is a cause for concern although its conservation status is of Least Concern. Androstachys johnsonii is a tree species used for a variety of purposes in the Vhembe Area of South Africa to maintain households.

Below- and aboveground architecture of Androstachys johnsonii prain: topological analysis of the root and shoot systems

This study aimed to analyse the topological branching pattern, area-preserving branching, and fractal branching pattern (self-similarity) of the root and shoot systems of 93 Androstachys johnsonii trees with diameter-at-breast heights of 5–32 cm. Topological parameters were calculated. Visual analysis indicated herringbone-like branching pattern for both the root and shoot systems. However, the topological index (TI) and topological trend (TT) suggested otherwise. This discrepancy was attributed to the fact that A. johnsonii has multiple laterals per stem/taproot node, suggesting that the topological indexes (TI and TT) might yield biased conclusions regarding the branching pattern when the main axis has multiple laterals per node. Hence, modified topological index (TIM) that could be applied in the cases of multiple laterals per node while conserving the values of TI for cases with one lateral per node was developed; the modified index was more efficient and realistic than TI. The area preserving branching was confirmed for each stem node confirming thus, the self-similar branching. For the root system, the area-preserving branching was only confirmed for the first node; therefore, self-similarity was not confirmed.

Tree component biomass expansion factors and root-to-shoot ratio of Lebombo ironwood: measurement uncertainty.

BackgroundNational and regional aboveground biomass (AGB) estimates are generally computed based on standing stem volume estimates from forest inventories and default biomass expansion factors (BEFs). AGB estimates are converted to estimates of belowground biomass (BGB) using default root-to-shoot ratios (R/S). Thus, BEFs and R/S are not estimated in ordinary forest inventories, which results in uncertainty in estimates of AGB and BGB. Here, we measured BEF and R/S values (including uncertainty) for different components of Lebombo ironwood (Androstachys johnsonii Prain) trees and assessed their dependence on tree size.ResultsThe BEF values of tree components were unrelated or weakly related to tree size, and R/S was independent of tree size. BEF values varied from 0.02 for foliage to 1.31 Mg m−3 for whole tree; measurement uncertainty (SE) varied from 2.9% for stem BEF to 10.6% for whole-tree BEF. The belowground, aboveground, and whole-tree BEF-based biomass densities were 30 ± 2.3 (SE = 3.89%), 121 ± 7.84 (SE = 3.23%), and 151 ± 9.87 Mg ha−1(SE = 3.27%), respectively. R/S was 0.24 with an uncertainty of 3.4%.ConclusionsBased on the finding of independence or weak dependence of BEF on tree size, we concluded that, for A. johnsonii, constant component BEF values can be accurately used within the interval of harvested tree sizes.

Assessment of plant biodiversity on and off mature stands of Androstachys johnsonii Prain and Colophospermum mopane (J.Kirk ex Benth.) J. Leonard

The species that were growing on the stands of C. mopane and on open space stands weighed more than those on the stands of A. johnsonii in both loam and sandy soil areas. This is probably an indication that there are some toxic chemicals that are excreted from various parts of A. johnsonii that caused the suffering and hence lesser weights of the understory species of A. johnsonii. The conditions were found to be unfavorable for the majority of the understory species to grow and flourish well under the canopies of A. johnsonii. This therefore, might imply that even though A. johnsonii possess allelochemical materials, some understory species may adapt to such conditions in the proximity of its vicinity. The decomposition of different parts of the plant on the ground surface under A. johnsonii canopies probably results in relatively highest concentration of allelochemical materials in the soil on A. johnsonii stands. Limiting factors like shading, temperature, water availability, and soil type may not necessarily be causes of the observed differences as the investigation was carried out from the same areas. The present investigation revealed that A. johnsonii in woodlands chokes its understory plants and such plants might eventually die out. Key words: Allelochemical materials, Androstachys johnsonii, Colophospermum mopane, biodiversity, impact.

Estimation of Tree Biomass, Carbon Stocks, and Error Propagation in Mecrusse Woodlands

We performed a biomass inventory using two-phase sampling to estimate biomass and carbon stocks for mecrusse woodlands and to quantify errors in the estimates. The first sampling phase involved measurement of auxiliary variables of living Androstachys johnsonii trees; in the second phase, we performed destructive biomass measurements on a randomly selected subset of trees from the first phase. The second-phase data were used to fit regression models to estimate below and aboveground biomass. These models were then applied to the first-phase data to estimate biomass stock. The estimated forest biomass and carbon stocks were 167.05 and 82.73 Mg·ha −1 , respectively. The percent error resulting from plot selection and allometric equations for whole tree biomass stock was 4.55% and 1.53%, respectively, yielding a total error of 4.80%. Among in- dividual variables in the first sampling phase, diameter at breast height (DBH) measurement was the largest source of error, and tree-height estimates contributed substantially to the error. Al- most none of the error was attributable to plot variability. For the second sampling phase, DBH measurements were the largest source of error, followed by height measurements and stem-wood density estimates. Of the total error (as total variance) of the sampling process, 90% was attrib- uted to plot selection and 10% to the allometric biomass model. The total error of our measure- ments was very low, which indicated that the two-phase sampling approach and sample size were effective for capturing and predicting biomass of this forest type.

Antimicrobial activity of Androstachys johnsonii Prain

Extracts of leaf, root, bark and soil leachates of Androstachys johnsonii screened for antibacterial activity had a significant inhibitory effect on most Gram-positive bacteria tested. Gram-negative bacteria were resistant to most extracts. Of the Gram-negative bacteria tested, 1% leaf extract significantly inhibited the growth of all bacteria tested and both 1% root and bark extract inhibited only one bacterial strain. At the concentration of 1 mg/ml, soil extracts showed less inhibitory activity against the bacteria tested. The growth of three out of five Gram-positive bacteria was inhibited by leaf extracts. At 0.1 mg/ml, four Gram-positive bacteria were inhibited. In both 0.01 and 0.1 mg/ml of leaf extracts, all Gram-negative bacteria were uninhibited. Root extract did not inhibit the growth of four Gram-positive bacteria at 0.01 mg/ml and two Gram-positive bacteria at 0.1 mg/ml, but had a noticeably higher level of activity against all Gram-positive bacteria, than bark and soil extracts. From the results obtained in this study, we conclude that the crude extracts of A. johnsonii exhibit significant antibacterial activity. Key words: Antimicrobial activity, Androstachys johnsonii, bacteria.

Structure and Composition ofAndrostachys johnsoniiWoodland across Various Strata in Gonarezhou National Park, Southeast Zimbabwe

A study on the structure and composition of Androstachys johnsonii Prain (Euphorbiaceae) woodland across three strata was conducted in Gonarezhou National Park (GNP), southeast Zimbabwe. Specifically, the objectives of the study were: (i) to determine the spatial structure and composition of A. johnsonii woodland in GNP and (ii) to determine factors that influence the structure and composition of A. johnsonii woodland in GNP. This study was based on a stratified random design with three major soil groups, and 30 plots were sampled in May 2010. The three soil strata were comprised of soils derived from (i) rhyolite, (ii) malvernia and (iii) granophyre bedrocks. A total of 1258 woody plants were assessed and 41 woody species were recorded. There were significant differences in mean tree heights, tree densities, basal area and species diversity in A. johnsonii woodland across the three soil strata. In contrast, there were no significant differences in the mean number of dead plants per ha in the three study strata in the GNP. Our study findings suggest that A. johnsonii woodland in GNP is being degraded. GNP management should develop a monitoring program through establishing monitoring plots in A. johnsonii woodland, and further studies need to be carried out, particularly on recruitment of A. johnsonii in the GNP.

Anatomical characteristics, properties and use of traditionally used and lesser-known wood species from Mozambique: a literature review

Mozambique is a country with vast forestry resources that include native wood species with high commercial value. Thus, the trade of timber as raw material, as well as wooden finished products are commercial options of considerable valuable for the country. This work presents information about anatomical characteristics, physical and mechanical properties and use of some native wood species from Mozambique, namely, Afzelia quanzensis, Androstachys johnsonii, Erytrophleoum suaveolens, Khaya nyasica, Pterocarpus angolensis, Milletia stuhlmannii and the emerging lesser-known species Pericopsis angolensis, Sterculia appendiculata and Sterculia quinqueloba. The study concludes that these Mozambican wood species are similar in several aspects. They are generally described as very hard, dense, having high mechanical strength and durable. The study also concludes that although the lesser-known wood species, S. quinqueloba, has similar properties to the traditionally used one, A. quanzensis, it is less used because of its poorly known properties and potential uses. Thus, further research to determine the properties and suitable end uses of other lesser know species is likely to be beneficial to the country.

Beyerane diterpenes: structure and reactivity of the α-ketol ent-3β-hydroxybeyer-15-ene-2,12-dione, its corresponding diosphenol, and synthesis of the isomeric α-ketol acetates

The major diterpenoid constituents of the heartwood of the Euphorbiaceae Androstachys johnsonii Prain are ent-3β-hydroxybeyer-15-ene-2,12-dione and the corresponding 2,3,12-trione. The four isomeric 2,3-α-ketol acetates were prepared by new and established methods and the chemistry of these α-ketols was investigated. A condensation reaction with ethylene glycol led to the useful ring A 2,3-ethylenedioxy blocking group. The 12-equatorial alcohol was eliminated yielding the new tetracyclic skeleton ent-14(13 → 12)abeo-beyerane. The ent-3β-hydroxy-2-ketone function was epimerised to the ent-3α-acetoxy-2-ketone function via the derived pyrrolidine enamine.