Mature Acacia Research Articles

Identification of the maturity of acacia honey by an endogenous oligosaccharide: A preliminary study

Mature honeys that brew naturally in the hive develop distinct bioactive components, and thus carry a higher premium due to their superior quality. However, how to identify mature honeys remains difficult. Trace oligosaccharides are a likely source of biomarkers to indicate maturity. Here, we profiled trace oligosaccharides in acacia honey by GC–MS and used a metabolomics strategy to screen oligosaccharides that distinguish honeys with different maturities. Turanose content increased gradually in acacia honey samples and was closely related to the days stored in the hive (p < 0.05). To accurately quantify turanose, a UPLC-ELSD method was developed. Using the established method, honeys with ≥1.20 g/100 g of turanose could be classified as mature acacia honey. Based on the preliminary study, 500 commercial acacia honeys were analyzed, and only 77.2 % of these samples had a satisfactory level of turanose. This work offers a potential method to evaluate the quality of honeys.

Effective in vitro culture using dormant bud of nodal sections from a mature Acacia tree

Effective in vitro culture using dormant bud of nodal sections from a mature Acacia tree

Problems and Management of Acacia-Dominated Urban Forests on Man-Made Slopes in a Subtropical, High-Density City

Acacia spp. are exotic tree species that have been widely planted on man-made slopes in Hong Kong since the 1960s. However, as they become mature and senescent, they may become a concern and cause various problems, including soil constraints for plant growth, decreasing provision of intended ecosystem services, declining syndromes, arrested succession, and high risk of failure. In this perspective paper, we present and discuss these problems using practical examples of Acacia-dominated urban forests on man-made roadside slopes in Hong Kong, based on a cross-disciplinary survey and a literature review. To conclude, we suggest that selective cutting, specific silvicultural operations of Acacia plantations, and the management of plantation edge and soils can be exercised, along with the planting of native species, to potentially alleviate these problems associated with mature Acacia plantations, by promoting the establishment of native forests, enhancing biodiversity, expediting succession, and providing better ecosystem services.

Density manipulation and pruning on fine root production and decomposition dynamics in a mature Acacia mangium Willd. stand in Kerala, India

Fine roots play a major role in water and mineral uptake and nutrient cycling in woody perennial-based ecosystems. Just as other biomass components, stand density manipulation and tree pruning may influence fine root production (FRP) and its decomposition dynamics. However, quantitative information on FRP and its turnover under different density and pruning regimes are meagre for most tropical trees. A field study was conducted to characterize FRP and associated nutrient release under varying stand density and pruning regimes in a 12-year-old Acacia mangium stand in Kerala, India. Soil ingrowth core method was employed for quantifying FRP and sequential core method for estimating standing fine root biomass. Annual FRP estimates were 5.78, 5.39, 3.74, and 3.38 Mg ha–1 for the 5000, 2500, 1250 and 625 trees ha−1 treatments, respectively. Allometric models based on tree diameter and basal area gave a good fit for annual FRP. Fine root turnover rates ranged from 2.81 to 3.16 yr−1, which however, was not influenced by stand density. Carbon stocks ranged from 1.36 to 2.39 Mg ha−1 with highest FRP during rainy season and lowest during the dry period. The litterbag study using nylon mesh bags indicated that annual fine root mass loss ranged from 76.2 (5000 trees ha−1) to 96.8% (625 trees ha−1). Tree pruning had only modest effects on tree growth, FRP, and carbon and nutrient release patterns. The study highlights the importance of stand density manipulation in altering A. mangium FRP, soil carbon and mineral nutrient dynamics.

Estimation of carbon dioxide assimilated in shoot biomass of mature Acacia seyal (Del.) Brenan and Eucalyptus microtheca (F.) Muell

Estimation of carbon dioxide assimilated in shoot biomass of mature Acacia seyal (Del.) Brenan and Eucalyptus microtheca (F.) Muell

Improving understanding of carbon stock characteristics of Eucalyptus and Acacia trees in southern China through litter layer and woody debris

Surveying the quality and quantity of carbon stock in litter layer and woody debris of Eucalyptus and Acacia plantations is critical in understanding their carbon pools. Here, the focus of the present study was on a number of Eucalyptus and Acacia plantations of different stand aged in the Pearl River Delta region of southern China. The plantation type proved to be a crucial driver of the carbon concentration in litter layer and woody debris, with Acacia exhibiting a superior ability to Eucalyptus to accumulate carbon with stand age in both these materials. The relative contribution of the litter layer and woody debris to the carbon stock of the ecosystem was also significantly higher under mature Acacia (8% and 7%, respectively) than that under mature Eucalyptus (4% and 1%, respectively). Most of the carbon stock within the litter layer was present in the leaf debris. The carbon stock in woody debris was mainly contained in the components within the 10–20 cm diameter class during the primary decay stage, represented as snags in middle-aged and mature Acacia, and as logs for mature Eucalyptus, respectively. The results indicate that both plantation type and stand age influence the characteristics of carbon stored in litter layer and woody debris significantly.

Discrimination of Natural Mature Acacia Honey Based on Multi-Physicochemical Parameters Combined with Chemometric Analysis.

Honey maturity is an important factor in evaluating the quality of honey. We established a method for the identification of natural mature acacia honey with eighteen physicochemical parameters combined with chemometric analysis. The analysis of variance showed significant differences between mature and immature acacia honey in physicochemical parameters. The principal component analysis explained 82.64% of the variance among samples, and indicated that total phenolic content, total protein content, and total sugar (glucose, fructose, sucrose) were the major variables. The cluster analysis and orthogonal partial least squares-discriminant analysis demonstrated that samples were grouped in relation to the maturity coinciding with the results of the principal component analysis. Meanwhile, the 35 test samples were classified with 100% accuracy with the method of multi-physicochemical parameters combined with chemometric analysis. All the results presented above proved the possibility of identifying mature acacia honey and immature acacia honey according to the chemometric analysis based on the multi-physicochemical parameters.

Response of open woodland and grassland mine site rehabilitation to fire disturbance on engineered landforms

The application of controlled fire on post-mine rehabilitation is currently underutilised as an ecological tool throughout fire prone landscapes such as eastern Australia. Despite widely accepted benefits of fuel management and ecological outcomes, mined land managers are generally reluctant to incorporate fire regimes on rehabilitated lands. We applied an experimental fire to 117 ha of 19- to 21-year-old coal mine rehabilitation in sub-tropical, semi-arid Central Queensland, Australia, and assessed the vegetation changes in five successive assessments for the two years following the burn. Vegetation metrics all showed trajectories towards pre-fire levels, or recovered to surpass pre-fire levels. Within two years of the burn, native species richness was significantly higher than pre-fire levels for both grassland and open woodland areas and vegetation cover had returned to pre-fire levels. Woody plant density (<2 m) increased from an average of 425–3,255 stems ha−1 in open woodland areas reaching values higher than those recorded at unburnt historical transects (n = 145); while stems greater than 2 m in height declined from 585 to 220 ha−1 due to the death of mature Acacia spp. The vegetative response following two wet seasons demonstrates short-term recovery following a range of fire impacts and demonstrates the potential to enhance the quality of the rehabilitation and increase the possibility of early relinquishment by reducing ecological, financial and reputational risks.

Conservation agriculture with trees amplifies negative effects of reduced tillage on maize performance in East Africa

Conservation agriculture (CA) is widely promoted in sub-Saharan Africa both in open fields and in agroforestry where the practice is known as ‘conservation agriculture with trees’ (CAWT). Although advantages and disadvantages of CA are well studied under sole cropping, less is known about its impact in agroforestry systems. The performance of open pollinated maize varieties under CA, CAWT, sole maize under conventional tillage (CT) and conventional tillage with trees (CTWT) was compared on-farm in equatorial savannah areas over four consecutive seasons in Rwanda and two seasons in Ethiopia. The tree species considered in the study were mature Grevillea robusta (A. Cunn.) and Senna spectabilis (DC.) in Rwanda and mature Acacia tortilis (Forssk.) in Ethiopia. Both CA and the presence of trees consistently reduced maize emergence, leaf area (LA), plant height, and maize yields. Crop emergence was significantly reduced under CAWT compared with CTWT. Maize emergence rates in CAWT and CTWT were respectively 46.9% and 70.1%, compared with 74.7% and 79.8% in sole maize under CA and CT. Grain yield in CAWT and CTWT were respectively 0.37 t dry matter (DM) ha−1 and 1.18 t DM ha−1 as compared with 1.65 t DM ha−1 and 1.95 t DM ha−1 in CA and CT. We conclude that CAWT strongly reduces crop yield in the equatorial savannah of East Africa. CA is incompatible with agroforestry under the conditions of our study. There is an urgent need for rigorous research to revisit if, when and where CAWT can generate benefits for smallholder farmers.

A Liquid Culture System for Improved Micropropagation of Mature Acacia nilotica (L.) Del. ssp. indica and Ex Vitro Rooting

A micropropagation method using liquid culture medium has been developed for mature Acacia nilotica (L.) Del. ssp. indica. Nodal segments obtained from 15 to 20 years old mature trees were used as explants and cultured on 0.8 % agar-gelled Murashige and Skoog medium containing 6-benzylaminopurine for shoot bud induction. Once culture got established, explants were transferred to Murashige and Skoog liquid medium containing 6-benzylaminopurine or kinetin for shoot multiplication. Shoot multiplication was influenced by plant growth regulators, size of vessels, amount of medium in culture vessels and repeated transfer of mother explants. Murashige and Skoog liquid medium containing 4.4 μM 6-benzylaminopurine was found to be the best for shoot multiplication. The performance of liquid and agar-gelled medium for shoot multiplication was compared. About ten times increase in shoot number in liquid culture medium was achieved. Micropropagated shoots were rooted ex vitro. Shoots treated with 2.46 mM indole-3-butyric acid solution for 1 h followed by 1.41 mM chlorogenic acid for 5 min exhibited highest percent of rooting in the green house. This process of micropropagation of A. nilotica, can be utilized for plant production on a large-scale.

Growth Performances of Three Indigenous Tree Species Planted in a Mature Acacia mangium Plantation with Different Canopy Openness under a Tropical Monsoon Climate

With the aim of establishing silvicultural techniques for tree species indigenous to monsoon tropical areas, we examined the survivorship and growth performance of three tree species under different light conditions. A 23-year-old Acacia mangium plantation was thinned in different ways: group selection thinning (gap creation, 50 m by 60 m in size), 2/3 random selection thinning based on basal area, 1/3 random selection thinning, and no thinning (control). The seedlings of Hopea odorata, H. ferrea, and Xylia xylocarpa var. kerrii were planted in each treatment area with three replications. At 30 months after planting, all species achieved a high survival rate (>90%) in all treatments, perhaps owing to intensive tending in the experimental plots. Both stem thickening and height growth were promoted as light conditions improved: most in the gap plot and least in the control plot for all species. H. ferrea grew to a large height even in dark conditions, suggesting that this species is considerably shade-tolerant. In contrast, X. xylocarpa var. kerrii was light-demanding owing to vigorous growth in the gap plot. The growth of the seedlings seemed to be associated with regeneration patterns in their natural habitats. The group selection thinning seemed to be most suitable for the growth of indigenous tree species.

Above and below ground development of Acacia saligna shrubs grown under different irrigation frequencies in an arid environment

Many arid and semiarid areas of the world remain barren due to the lack of water even though the use of ephemeral local water sources, such as runoff water, could change the biomass production patterns. The objective of the present study was to determine the effects of levels of water application and modes of application on the biomass below and above ground development of mature Acacia saligna (Labill.) H.L. Wendl. shrubs. The application treatments were: flooded once a year, low and high frequency irrigation with and without an additional annual flooding, and well-watered. An analysis of the standing biomass data after 5 years of growth indicated that the yearly runoff floods contributed significantly to increase the total above ground biomass. The data collected during the 1999 season, indicated however that during this season flooding had no significant effect on any of the measured growth parameters, while application frequency had a significant effect on the growth rates, water use efficiency and leaf and stem production of shrubs. Below ground, two periods of root growth were observed for the higher irrigation frequency treatments: an initial moderate increase followed by a rapid reduction. The period of rapid reduction in root biomass matched well with the period of rapid increments in above ground biomass production. Furthermore, increased irrigation frequencies resulted in bigger root systems but for lower irrigation frequencies rooting depth increased.

Effect of Inoculation with Rhizobia on the Gum-Arabic Production of 10-Year-Old Acacia senegal Trees

ABSTRACT The aim of our study was to assess if the inoculation of Rhizobium on mature Acacia senegal trees would have an effect on the gum-arabic yield. A plantation located in Rotto (Department of Linguere Senegal) containing 80 similar 10-year-old trees was identified. The distance between each tree planted was about 5 m. Soil analysis showed soil characteristics were not different within the plantation. The plantation was divided into two parts: one part where the 10-year-old trees were inoculated at the beginning of the rainy season (August 2002 and August 2003) with 1 L of a liquid inoculum prepared with dried alginate beads containing a mixture of selected rhizobial strains (CIRADF 300, CIRADF 301 and CIRADF 302). The taping was done at the same intensity on each tree and when the leaves started to fall. The gum-arabic production was measured for every tree during two years (December 2002/April 2003 and December 2003/April 2004). The rainfall the first year was low, about 250 mm. The effect of the inoculation was assessed in terms of percentage of trees producing gum and amount of gum-arabic produced. Results were not significantly different (P ≤ 0.05). Before the second rainy season, mature trees from the inoculated plot were reinoculated and tree taping accomplished. The annual rainfall the second year was around 440 mm. Data suggested that gum-arabic yield of inoculated trees was significantly higher compared to the noninoculated tree gum-arabic yields. We can assume that the inoculation of 10-year old-trees will enhance the gum-arabic yield under natural conditions.

Multi‐scale patterns and bush encroachment in an arid savanna with a shallow soil layer

Abstract.Question:Bush encroachment (i.e. an increase in density of woody plants often unpalatable to domestic livestock) is a serious problem in many savannas and threatens the livelihood of many pastoralists. Can we derive a better understanding of the factors causing bush encroachment by investigating the scale dependency of patterns and processes in savannas?Location:An arid savanna in the Khomas Hochland, Namibia.Methods:Patterns of bush, grass, and soil nutrient distribution were surveyed on several scales along a rainfall gradient, with emphasis on intraspecific interactions within the dominant woody species,Acacia reficiens.Results:Savannas can be interpreted as patch‐dynamic systems where landscapes are composed of many patches (a few ha in size) in different states of transition between grassy and woody dominance.Conclusions:In arid savannas, this patchiness is driven both by rainfall that is highly variable in space and time and by inter‐tree competition. Within the paradigm of patch‐dynamic savannas, bush encroachment is part of a cyclical succession between open savanna and woody dominance. The conversion from a patch of open savanna to a bush‐encroached area is initiated by the spatial and temporal overlap of several (localized) rainfall events sufficient forAcaciagermination and establishment. With time, growth and self‐thinning will transform the bush‐encroached area into a matureAcaciastand and eventually into open savanna again. Patchiness is sustained due to the local rarity (and patchiness) of rainfall sufficient for germination of woody plants as well as by plant‐soil interactions.

Rebrota de cepas de árvores adultas de acácia-negra (Acacia mearnsii De Wild.)

O rejuvenescimento de árvores que alcançaram a maturidade de acácia-negra (Acacia mearnsii De Wild.) torna-se necessário devido à dificuldade do enraizamento de ramos adultos. Desse modo, o objetivo do presente trabalho foi estudar a influência da altura de cepa no desenvolvimento de brotações e o melhor período para o corte das árvores. Os ensaios foram instalados em um plantio comercial de acácia-negra aos cinco anos de idade, desenvolvendo-se em espaçamentos de 1,0 x 1,30 m. Utilizou-se o delineamento em blocos ao acaso com seis repetições e seis plantas por parcela. Os tratamentos foram constituídos de diferentes alturas de cepa com corte à altura de: (a) 15 cm, (b) 30 cm, (c) 45 cm e (d) 60 cm. Os ensaios foram instalados no outono (março) e na primavera (setembro). Foram feitas avaliações aos 45, 90 e 150 dias, através da contagem de cepas com brotações e número de brotações por cepa. O corte das árvores na altura de 60 cm promoveu elevado índice de rebrota, com aproximadamente 90% das cepas apresentando brotações novas. Na primavera, obteve-se melhor rebrota de árvores adultas de acácia-negra, em comparação com o ensaio do outono. Esses resultados indicaram a influência da altura de cepa e do período do ano na capacidade de rebrota de indivíduos adultos de Acacia mearnsii.

Genomic DNA methylation of juvenile and mature Acacia mangium micropropagated in vitro with reference to leaf morphology as a phase change marker.

Genomic DNA methylation was analyzed in Acacia mangium Willd. microshoots micropropagated in vitro from juvenile and mature explants, and in relation to leaf morphology of the microshoots, which is considered a phase change indicator. Based on high performance liquid chromatography (HPLC) analyses, we found more DNA methylation in microshoots exhibiting juvenile leaf morphology (22.4%) than in microshoots of the mature phyllode morphological type (20.7%), irrespective of the age of the source material. Overall, the degree of DNA methylation in A. mangium microshoots was consistent with values reported for other angiosperms. Complementary investigations based on methylation sensitive amplification polymorphism (MSAP) techniques established that, of 1204 fragments revealed by the different primer pairs used, 49 (i.e., 4.08%) were derived from C(5m)CGG methylated sites. Three of these C(5m)CGG sites were exclusive to the juvenile plant material, and three sites were exclusive to the mature source. No fragments were associated specifically with leaf morphology, rather than with plant age. Thus, although the two age classes could not be distinguished based on a quantitative HPLC measure of DNA methylation, qualitative differences existed, as demonstrated by the six age-specific markers identified by MSAP. The reliability of the MSAP data was confirmed on a larger sample of juvenile plant material, which suggested that the total of six methylation markers detected is probably an underestimation of the age-related differences in DNA methylation that may exist between juvenile and mature plant materials.

In vitro micropropagation and rooting of Acacia mangium microshoots from juvenile and mature origins

Acacia mangium microshoots from juvenile and mature genotypes were micropropagated through a regular subculture regime for more than 3 yr in vitro. Average multiplication rates of 5.5 for the juvenile source and of 3.9 for the mature clone were obtained during this period on the 6-benzylaminopurine-enriched multiplication medium. Although the juvenile material displayed higher potential for axillary shoot and root formation than the mature clone overall, the differences were not statistically significant with noticeable variations in the course of time from one subculture to another. On specific rooting media, the juvenile material rooted overall in greater proportions than the mature material, notwithstanding noteworthy interactions between the age of the plant material and the various experimental factors tested, i.e. sucrose concentration, macrosalt formulation and light regime. The stimulating effect of darkness on juvenile plant material rooting rates was more obvious than for the mature clone, which responded more inconsistently. Addition of 4 μM indole-3-acetic acid, indole-3-butyrie acid, or 1-naphthaleneacetic acid in the rooting medium significantly increased the proportion of rooted microshoots of both origins. The rooting criteria observed were also prone to vary depending on the experimental date. The data indicate that rooting of juvenile and mature Acacia mangium materials have average rates of 90% and 77%, respectively. These are high enough to consides possible applications of these procedures toward operational activities.

In vitro rooting of juvenile and mature Acacia mangium microcuttings with reference to leaf morphology as a phase change marker

Rooting capacity of microshoots derived from a mature clone of Acacia mangium Willd. and from its juvenile progeny was compared in different in vitro conditions and in relation to leaf morphology as a phase change marker. Rooting capacity of the mature clone appeared to depend a lot on rooting medium composition, in contrast to the juvenile plant material. On a SH/3 derived medium with 4 µM IAA, the rooting rates varied significantly according to microshoot morphology and light regime starting from day 14. Maintaining the microshoots for 3 weeks in total darkness prior to transfer to the standard 16-h photoperiod increased the rooting rates overall. Mature-like microshoots of juvenile origin rooted in much lower proportions than the juvenile-like ones under the 16-h photoperiod, whereas no difference in rooting rates between the two morphological types was observed after 3 weeks in total darkness. The results were totally opposite for the mature clone for which 3 weeks in darkness, in contrast to the 16-h photoperiod, induced morphology-related differences in rooting rates with higher scores for the juvenile type. This study shows that under certain conditions, A. mangium microshoots from mature origin but with juvenile morphology can root in vitro with similar success rates (70%) to microshoots from juvenile plant material. However, the inconsistencies observed between the two age classes of microshoots in relation to photoperiod refute the use of foliar morphology as a reliable marker of rooting ability in A. mangium, although these two traits are classically referred to as phase change indicators.

CHANGES IN SOIL PROPERTIES AND NUTRIENT ACCUMULATION IN NEEM UNDER THE CANOPY OFACACIA TORTILIS

ABSTRACT Investigations were made on the growth of young neem (Azadirachta indica A. Juss) seedlings, planted among mature Acacia tortilis trees, and associated soil properties, to determine whether seedlings could be successfully introduced among old tree stands in the arid environment. Size measures of 52 mo-old neem seedlings planted along the mature and unlopped trees of Acacia tortilis (mean height 8.3 m, crown diameter 12.6 m and diameter at breast height 24.7 cm), indicated that A. tortilis significantly affected the growth of neem seedlings planted under the canopy. Maximum size reduction was observed in the plants found under the inner crown (IC) compared to the plants in the outer crown (OC) and outside crown (OS) zone. Soil parameters (0 to 75 cm depth) of pH, electrical conductivity, and P, Ca and Mg concentrations, were higher in the soil of the OC (6 to 9 m) zone of A. tortilis compared to the IC zone (1 to 4 m) and OS zone (15 to 24 m). The concentration of K, NH4-N and NO3-N were highest u...

In vitro shoot apex micrografting of mature Acacia mangium

Prospects for in vitro micrografting shoot apices of mature Acacia mangium trees were investigated with the use of 432 micrografts. Overall success rates of 51.5%s% were obtained for shoot apices ranging from 200 to 400 μm in length, and a short basal wedge of underlying tissues top-grafted in aseptic conditions onto 2-to-3-month old in vitro grown Acacia mangium seedlings. The successfully established micrografts displayed, however, substantial variability in terms of further scion elongation as 41% of these micrografts, or 21.2% only of the total amount of the micrografts performed, had resumed growth two months after micrografting. The elongated scions exhibited different types of morphology, ranging from juvenile-like type composed leaves to the predominant mature-like phyllode morphology. Side-grafting, a more difficult procedure to perform than top-grafting, or placing the micrografts for 2 weeks in darkness after grafting, did not improve the scores. Moreover, attempts to micrograft meristems (150–200 μm) resulted in 5% success only.