Acacia hybrid (Acacia mangium Willd. x A. auriculiformis A. Cunn. Ex Benth.) dominates plantation wood production in central Vietnam. Dependence on a single species may increase biological risks. The potential of eucalypt as an alternative was examined by comparing the growth and survival of acacia hybrid and eucalypt hybrid (Eucalyptus urophylla S.T. Blake x E. pellita F. Muell.) clones in Quang Tri province at three planting densities (1333, 1667 and 2222 trees ha-1). The experiment was planted on an eroded shallow soil common in the region. At age 5 years, survival of acacia (74%) was higher than that of eucalypt (67%), a consequence of high mortality from wind damage for one eucalypt clone. Eucalypt was taller by about 2 m, but stem diameters of acacia and eucalypt were very similar. For both taxa, diameter decreased significantly as planting density increased. Across planting densities, mean standing volume was 107 and 108 m3 ha-1 for acacia and eucalyptus, respectively. Linear regressions of stocking at 5 years on volume accounted for over half of the variance in acacia and eucalypt plot volumes, demonstrating the strong effect of stocking on yield. There were similarly strong effects of stocking on stem diameter. Acacia hybrid plantations of nearby small growers had stockings at age 5 years that averaged over 2500 stems ha-1. Growers planted at higher densities and allowed their trees to multi-stem. Their standing volumes at age 5 years ranged from 83 to 102 m3 ha-1. Understanding how to reduce tree mortality would assist growers to choose planting densities and stand management that optimise growth, log diameter classes and net returns.

Acacia mangium is one of the most important hardwood plantation species in the tropics. The question of how to grow Acacia productively and sustainably remains a major issue for the forestry sector in many tropical countries. We analyzed the productivity of A. mangium plantations across five contrasting ecological zones in Vietnam. These covered gradients in rainfall from 1750 mm to 3060 mm and a mean annual temperature range of 22 - 27 degrees C. Plantation productivity across these zones varied from an MAI of 6 m(3) ha(-1) to 31 m(3) ha y(-1). A comprehensive suite of statistical methods was utilized for variable and model selection to minimize confounding and multicollinearity issues among predictors and identify determinants of plantation productivity using 27 biophysical variables. These variables encompass plantation age, climate parameters, as well as site and soil properties. Results showed that, apart from plantation age, the factors influencing plantation productivity and explaining a majority of variation in mean annual timber increment are soil organic carbon content and the number of foggy days. Soil carbon is probably an index of overall soil fertility and its significance reflects the fact that the plantations have often been established on relatively degraded sites. The lower productivity at sites having a higher frequency of foggy days (up to 57 days per year in some regions) may arise from lower solar radiation and temperature during fog. The results of this study can inform site selection and plantation management tools aimed at maximizing Acacia mangium productivity in Vietnam and other countries with similar ecological conditions. Planting A. mangium in high-intensity fog areas is not recommended. Further studies on the ecophysiological mechanisms of how fog influences the growth of tropical A. mangium plantations are also needed.

Acacia origena , a member of the Leguminosae family, thrives in the challenging A environmental conditions of southwestern Saudi Arabia and holds significant economic value. However, the recent occurrence of forest fires has posed a considerable threat to this species, prompting a comprehensive exploration of its resilience. This study investigates the impact of forest fires on Acacia origena , a resilient species in southwestern Saudi Arabia, with a focus on wood anatomy, soil chemical characteristics, and associated microorganisms in Al Mofareh Mountain, Alsoudah, southwestern Saudi Arabia. Fifteen samples from burned and unburned areas were analyzed. These samples were sectioned in both transverse and tangential planes to facilitate light microscopy and the analysis of wood anatomy, revealing distinctive coloration and structural changes in burned tissues. Larger-diameter specimens demonstrated greater resilience, accumulating tannins and forming tyloses to insulate damaged areas. Soil analysis indicated post-fire alterations in texture, composition, and nutrient levels. Microbial assessments highlighted varying responses in yeast and total germ colonies, it was increased by 75%. These findings provide valuable insights into the ecological responses of A. origena and soil ecosystems to fire, emphasizing the importance of comprehensive studies to guide conservation and management efforts in fire-affected regions .

Chromated copper arsenate (CCA) is a wood preservative containing Cr, Cu, and As and leaching of these heavy metals into agricultural fields raises concern about food safety. The heavy metals enter the plants due to hydrophilic nature and prevalent mobility by damaging the photosynthetic process and hindering metabolism of plants. Phytoremediation is one of the constructive methods employed in mitigation of toxic metals from the soil. Nevertheless, only limited studies have been conducted on the effect of heavy metals and chelating agents on biochemical parameters in tree species. Overall, the present study advocates the possible effects of CCA components, EDTA and DTPA, on total carbohydrates, protein, and chlorophyll content of Acacia auriculiformis and Casuarina equisetifolia seedlings. Experiments on the effect of CCA and chelating agents on biochemical parameters of seedlings were conducted in potting medium. The plastic pots transplanted with 1-month-old seedlings of Acacia auriculiformis and Casuarina equisetifolia were supplied with sufficient air-dried soil and compost followed by treatment of six different concentrations (250-2500 mg kg(-1) soil) of CCA. Simultaneously, in a separate set of experiments, pots with planting media were supplied with CCA (1000 mg kg(-1) soil) followed by treatment of four different concentrations of EDTA and DTPA (0.1-1.5 mu M kg(-1)). The leaves of 6-month-old seedlings of both tree species exposed to different concentrations of CCA and chelating agents were harvested and the amount of total carbohydrates, protein, and chlorophyll content was estimated by spectrophotometric methods. The results of different treatments were compared with the control. Results of the study showed significant decrease (p <= 0.05) in the amount of total carbohydrates, proteins, and chlorophyll content with an increase in concentrations of CCA (750-2500 mg kg(-1)) in the seedlings of A. auriculiformis and C. equisetifolia. Similarly, the seedlings of both tree species treated with 1.5 mu M kg(-1) each of EDTA and DTPA showed significantly (p <= 0.05) increased total carbohydrate, proteins, and chlorophyll content. The studies conclude that the CCA components affect the total carbohydrate, protein, and chlorophyll content of the A. auriculiformis and C. equisetifolia seedlings. However, moderate to higher concentrations of EDTA and DTPA were effective in ameliorating CCA toxicity.

The pulp and paper industry in Sumatra, Indonesia, completely changed its key plantation forest species during 2012-2017 from their previous mainstay, Acacia mangium (which had become severely damaged by diseases) to Eucalyptus pellita and related hybrids. This rapid wholesale change posed major challenges to management and ongoing wood production. We present here long-term experimental results and operational pre-harvest inventory of the two species covering five successive rotations, spanning three decades. This is the first such report of longterm, multi-rotation productivity trends for plantations from a tropical equatorial environment. Highlights include: (i) the trends in productivity in the experiments and inventory are parallel and were characterised by an initial increase, followed by a decrease and then recovery of productivity in response to ecosystem stress, species change and management interventions, (ii) the growth rates of E. pellita are significantly lower than those of A. mangium across soils and sites (iii) the conservation of site organic matter during the inter-rotation phase is as critical for eucalypt as it was for acacia, (iv) the response to applied P is more widespread and stronger in E. pellita than in A. mangium, and (v) significant production losses are occurring due to high tree mortality. We also highlight some of the emerging issues warranting attention. Productivity varies widely across sites, so does the relative responses to management inputs in this environment. The reasons for this need to be better understood so that site-specific management practices can be applied. For example, the depth at which an impeding horizon occurs in some soil profiles is a strong factor influencing growth, regardless of species. The legacy effects of A. mangium, especially of fixed N and nutrient cycling are benefitting eucalypts. The adoption of research outcomes by managers have enabled gains of 8-19% in the productivity of eucalypts planted in recent years compared to that obtained in the first eucalypt rotation. Further improvements are possible through adaptive management, guided by both experimental results and inventory, aimed at gains in operationally realisable productivity. The companies are committed to using only plantation grown wood for processing and are not expanding their own land base allocated for production. The imperative, therefore, is to focus on sustainably increasing the productivity per unit area on their existing land management units that are now under the fifth or sixth rotation.

Owing to the order of the day, we are searching for an ecofriendly binding ingredient instead of cement, which is now universally used in concrete. Almost everyone extensively exploits construction materials due to their good durability and compressive characteristics. The present study examines the use of Acacia nilotica ash as a cement substitute. It is known that Acacia nilotica`s aggressive roots are extremely presumptuous and invasive and spoil the foundation of buildings. By gripping water from adjoining areas, they change soil nitrogen and are a major source of affecting plant growth. In this work, the M 35- grade geocomposite was investigated by incorporating Acacia nilotica ash at 0%, 2.5, 5%, 7.5%, 10%, 12.5%, and 15% for fly ash. Mechanical and durability studies were carried out by changing the magnitude of Acacia nilotica ash and evaluating it with the standard composite samples.