Search Results (16)

Mixing and matching N₂-fixing leguminous species is a crucial strategy to enhance quality and efficiency in sustainable forestry. Tree leaves and rhizosphere are primary sites for matter and energy exchange, functioning as key assimilation organs that forests provide for ecological services. The introduction of functional species alters soil properties, which, in turn, directly or indirectly shape leaf functional traits, soil microbial dynamics, and their association. However, the correlation between aboveground functional traits and belowground rhizosphere soil microorganisms of dominant tree species in mixed leguminous and non-leguminous forests remains unclear. In this study, the responses and correlations of leaf functional traits and rhizosphere soil microbial communities of Castanopsis hystrix Hook. f. & Thomson ex A. DC. across three forest types were investigated. A pure forest (PF) of C. hystrix was designated as control forest, while a leguminous mixed forest (LMF) consisting of C. hystrix and the leguminous species Acacia mangium Willd. as well as a non-leguminous mixed forest (NMF) comprising C. hystrix and the non-leguminous species Schima superba Gardner & Champ. served as experimental forests. Seven leaf functional trait indices were measured, and the high-throughput sequencing of soil microbial communities was included in the analysis. The results were as follows: Firstly, compared to the pure forest, the specific leaf area (SLA) of C. hystrix significantly decreased in both mixed forest types (p < 0.05). Additionally, in comparison to the pure forest, the leaf area (LA) and leaf organic carbon content (LOC) of C. hystrix significantly reduced (p < 0.05), whereas the leaf total phosphorus content (LTP) significantly increased in the non-leguminous tree species mixed forest (p < 0.01). The leaf dry matter content (LDMC), relative chlorophyll content (RCC), and leaf total nitrogen content (LTN) of C. hystrix exhibited no significant differences among the three forest types (p > 0.05). Secondly, neither the dominant phyla of rhizosphere soil microorganisms nor the bacterial richness and diversity had differences in the mixed forests. However, the richness and diversity of rhizosphere soil fungi significantly increased in the mixed forests, and those in the leguminous mixed forest exhibited more positive effects compared to those in the non-leguminous mixed forest. Finally, redundancy analysis (RDA) showed significant correlations between plant leaf functional traits and rhizosphere soil microorganisms. Specifically, LDMC, SLA, LTN, and LTP of C. hystrix showed significant correlations with differences in the structure of bacterial community (p < 0.05), and LTN was significantly correlated with differences in the structure of the fungal community (p < 0.05). In summary, we found that plant leaf functional traits and the community of rhizosphere soil microorganisms displayed significant differences in the mixed forests, and those mixed with leguminous trees may further enhance the assimilation processes by modifying the utilization of nutrients such as carbon, nitrogen, and phosphorus by plants and microorganisms. Meanwhile, our results support the interaction of physiological and ecological processes between the aboveground and belowground parts of C. hystrix. These findings emphasize the important roles of N₂-fixing leguminous trees and synergy of aboveground–belowground processes in establishing sustainable artificial forests. Full article

Acacia hybrid (Acacia mangium Willd. × 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 × 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. Full article

Walls, as components of the lateral-force-resisting system of a building, are defined as shear walls. This study aims to determine the behavior of shear wall panel cross-laminated-timber-based mangium wood (Acacia mangium Willd) (CLT-mangium) in earthquake-resistant prefabricated houses. The earthquake performance of CLT mangium frame shear walls panels has been studied using monotonic tests. The shear walls were constructed using CLT-mangium measuring 2400 mm × 1200 mm × 68 mm with various design patterns (straight sheathing, diagonal sheathing/45°, windowed shear wall with diagonal pattern and a door shear wall with a diagonal pattern). Shear wall testing was carried out using a racking test, and seismic force calculations were obtained using static equivalent earthquake analysis. CLT-mangium sheathing installed horizontally (straight sheathing) is relatively weak compared to the diagonal sheathing, but it is easier and more flexible to manufacture. The diagonal sheathing type is stronger and stiffer because it has triangulation properties, such as truss properties, but is more complicated to manufacture (less flexible). The type A design is suitable for low-intensity zones (2), and types B, D, E1 and E2 are suitable for moderate-intensity zones (3, 4), and type C is suitable for severe-intensity zones (5). Full article

Invasive Acacia species can alter nutrient cycling processes in forest ecosystems, particularly affecting total litterfall production and litter decomposition patterns. This study examined the effects of exotic Acacia mangium Willd. on total litterfall production, nutrient concentrations in leaf litterfall fractions, leaf litter decomposition, and nutrient release in lowland heath (HF) and mixed dipterocarp forests (MDF) in Brunei Darussalam, Borneo. Above-ground litterfall traps were installed in HF and MDF with and without invasive Acacia present, representing four habitat types in total, and monthly collections were conducted for 12 months. Litter decomposition bags were deployed to determine the rates of decomposition and nutrient release. Habitats invaded by Acacia exhibited higher total litterfall production, increased leaf litter concentrations of nitrogen, potassium, and calcium, and increased addition of all nutrients measured in litter (nitrogen, phosphorus, potassium, calcium, and magnesium, especially in the Acacia-invaded mixed dipterocarp forest (AMDF) and nitrogen and potassium in Acacia-invaded heath forest (AHF)), reduced nitrogen and potassium use efficiencies in AHF, and reduced stand-level nitrogen and calcium use efficiencies in AMDF. Litter decomposition rates and nutrient release were lower in AMDF than in the three other habitats. The significantly higher total litterfall production coupled with higher nutrient addition in the two Acacia-invaded habitats is expected to progressively increase the abilities of these habitats to produce large quantities of nutrient-rich litter and will likely eventually lead to an enrichment of nutrients in the soil, thus facilitating further invasion by Acacia, particularly in the MDF. Full article

Mangium (Acacia mangium Willd.) is a fast-growing wood that is widely grown in Indonesia. The impregnation method is needed to improve the qualities of the wood. In this study, TiO₂ nanoparticle (79.17 nm) was produced using the hydrothermal method. The purpose of this study was to analyze the effect of TiO₂ nanoparticle impregnation on the density and dimensional stability of mangium and the effectiveness of the presence of TiO₂ nanoparticle in wood in degrading pollutants. The mangium samples (2 cm × 2 cm × 2 cm) were placed inside impregnation tube. The impregnation solutions included water (untreated), 1% TiO₂ nanoparticle, and 5% TiO₂ nanoparticles. The samples were analyzed for density, weight percent gain (WPG) dan bulking effect (BE). Samples were also analyzed by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). TiO₂ nanoparticle resulted in an increase in density, WPG, and BE-treated mangium. Based on XRD and FTIR results, TiO₂ nanoparticle was successfully impregnated into mangium wood. Scanning electron microscopy–energy-dispersive X-ray spectroscopy analysis indicated that TiO₂ nanoparticle covered the surface of the wood cells. The TiO₂-impregnated mangium wood has a higher photocatalyst activity than untreated, indicating better protection from UV radiation and pollutants. Full article

Asexual propagation techniques for producing good quality germplasm for breeding and dissemination purposes have proven difficult for acacia species comprised of mature planting material. The study was conducted to study the effect of rejuvenation on the rooting ability of mature cuttings. Shoots were induced from the lower branch by cutting a part of the mature branch of the crown and leaving it horizontally on the propagation bench under the misting system. Shoots were harvested and further used as stem cuttings to evaluate their rooting ability through the application of rooting hormone. The rooting ability of the cuttings is highly variable among species. The percentage of stem sections producing juvenile shoots was similar for Acacia mangium Willd. (88%) and Acacia auriculiformis A.Cunn. ex Benth. (90%). Only 52% of stem sections were able to produce shoots for Acacia crassicarpa A.Cunn. ex Benth., followed by Acacia aulococarpa A.Cunn. ex Benth. with only 31%. Overall, A. auriculiformis rooted better and recorded the highest mean value for all traits tested. Hormone treatment significantly enhances the rooting ability of A. auriculiformis and A. mangium. However, A. aulococarpa and A. crassicarpa did not respond well to the treatment. Rejuvenated stem cuttings were rooted better than mature cuttings, producing the highest mean value for all traits tested in all species, with or without hormone treatment. Results indicated that it is possible to rejuvenate mature cuttings through bud break in a controlled environment. Full article

Early growth performances of 11 native tree species were investigated in three different sites in Mindanao, Philippines, to evaluate their adaptability and potential for plantation development. Three alien species were added to assess how native species could potentially compete with these alien species based on survival rate, diameter growth rate (DGR), and height growth rate (HGR). A year after planting, the native species common to all sites that obtained >80% survival rate were Casuarina equisetifolia L. Alstonia macrophylla Wall. ex. G.Don., Alstonia scholaris (L.) R.Br., and Parkia javanica (Lam.) Merr. and were comparable to an alien species Acacia mangium Willd. The species with the lowest survival rate (30%) across all sites was Duabanga moluccana Blume. Native species P. javanica, Eucalyptus deglupta Blume, and A. macrophylla all had a DGR of 34 mm year⁻¹ and were comparable with the alien species Schizolobium parahyba (Vell.) S.F.Blake with 38 mm year⁻¹. However, the HGR of native species E. deglupta (245 cm year⁻¹) and Melia dubia Cav. (230 cm year⁻¹) were higher than an alien species S. parahyba (222 cm year⁻¹). No native species can compete with the DGR (52 mm year⁻¹) and HGR (384 cm year⁻¹) of A. mangium. Rainfall significantly explained 13%–97% of DGR, HGR and survival rate of >70% of the species while air temperature explained about 17%–96% of the variations of similar variables. This early assessment provides a strong basis to better predict the early performances of native species in the Philippines. Through this, appropriate silvicultural intervention can be recommended towards improving the growth and survival of the native seedlings as alternative industrial tree plantation species in the country. Full article

Background and Objectives: The stable stand structure of mixed plantations is the basis of giving full play to forest ecological function and benefit. However, the monocultural Eucalyptus plantations with large-scale and successive planting that caused ecological problems such as reduced species diversity and loss of soil nutrients have presented to be unstable and vulnerable, especially in typhoon-prone areas. The objective of this study was to evaluate the nonspatial structure difference and the stand stability of pure and mixed-Eucalyptus forests, to find out the best mixed pattern of Eucalyptus forests with the most stability in typhoon-prone areas. Materials and Methods: In this study, we randomly investigated eight plots of 30 m × 30 m in pure and mixed-Eucalyptus (Eucalyptus urophylla S. T. Blake × E. grandis W. Hill) plantations of different tree species (Neolamarckia cadamba (Roxb.) Bosser, Acacia mangium Willd., and Pinus elliottii var. Elliottii Engelm. × P. caribaea Morelet) on growth status, characterized and compared the distribution of nonspatial structure of the monoculture and mixtures, and evaluated the stand quality and stability from eight indexes of the nonspatial structure, including preservation rate, stand density, height, diameter, stem form, degree of stem inclination, tree-species composition, and age structure. Results: Eucalyptus surviving in the mixed plantation of Eucalyptus and A. mangium (EA) and in the mixed plantation of Eucalyptus and P. elliottii × P. caribaea (EP) were 5.0% and 7.6% greater than those in pure Eucalyptus plantation (EE), respectively, while only the stand preservation rate of EA was greater (+2.9%) than that of the pure Eucalyptus plantation. The proportions of all mixtures in the height class greater than 7 m were fewer than that of EE. The proportions of EA and mixed plantation of Eucalyptus and N. cadamba (EN) in the diameter class greater than 7 m were 10.6% and 7.8%, respectively, more than that of EE. EN had the highest ratio of branching visibly (41.0%), EA had the highest ratio of inclined stems (8.1%), and EP had the most straight and complete stem form (68.7%). The stand stability of the mixed plantation of Eucalyptus and A. mangium presented to be optimal, as its subordinate function value (0.76) and state value (ω = 0.61) of real stand were the largest. Conclusions: A. mangium is a superior tree species to mix with Eucalyptus for a more stable stand structure in the early growth stage to approach an evident and immense stability and resistance, which is of great significance for the forest restoration of Eucalyptus in response to extreme climate and forest management. Full article

Understanding species-specific water use patterns across contrasting sites and how sensitivity of responses to environmental variables changes for different species is critical for evaluating potential forest dynamics and land use changes under global change. To quantify water use patterns and the sensitivity of tree transpiration to environmental drivers among sites and species, sap flow and meteorological data sets from three contrasting climatic zones were combined and compared in this analysis. Agathis australis from NZHP site, Schima wallichii Choisy (native) and Acacia mangium Willd (exotic) from CHS site, Liquidamber formosana Hance, Quercus variabilis Blume and Quercus acutissima Carruth from CJGS site were the dominant trees chosen as our study species. Biological traits were collected to explain the underlying physiological mechanisms for water use variation. Results showed that the strongest environmental drivers of sap flow were photosynthetically active radiation (PAR), vapor pressure deficit (VPD) and temperature across sites, indicating that the response of water use to abiotic drivers converged across sites. Water use magnitude was site specific, which was controlled by site characteristics, species composition and local weather conditions. The species with higher sap flow density (Fd) generally had greater stomatal conductance. Native deciduous broadleaved species had a higher Fd and faster response to stomatal regulation than that of native evergreen broadleaved species (S. wallichii) and conifer species A. australis. The analysis also showed that exotic species (A. mangium) consumed more water than native species (S. wallichii). Trees with diffuse porous and lower wood density had relatively higher Fd for angiosperms, suggesting that water use was regulated by physiological differences. Water use characteristics across sites are controlled by both external factors such as site-specific characteristics (local environmental conditions and species composition) and internal factors such as biological traits (xylem anatomy, root biomass and leaf area), which highlights the complexity of quantifying land water budgets for areas covered by different species. Full article

Forming a backbone of the wood supply in Vietnam, approximately 50% of plantation areas are managed by individual households. Of the planted species, the Acacia (Acacia auriculiformis A. Cunn. ex Benth. × Acacia mangium Willd) hybrid is one of the most preferred by timber growers. Yet, information on the potential of this timber species for rural livelihoods is lacking. Taking Nam Dong and Phu Loc districts in Thua Thien Hue province as case studies, this paper aimed to explore the (i) characteristics of small-scale Acacia hybrid timber producers; (ii) contribution of Acacia hybrid timber production and commercialization to rural livelihoods; and (iii) socio-economic and contextual factors which determine the income from Acacia hybrid timber. We applied a mixed-methods approach including review of secondary data, interviews of 26 key informants, eight focus group discussions, direct observations and a survey of 300 Acacia hybrid producer households selected through multistage and purposive sampling. Qualitative and quantitative data were analyzed using thematic, descriptive and inferential statistics, such as variance analysis, correlation analysis and Bayesian model average (BMA) analysis. The results demonstrated the diversity of socio-economic characteristics, resource access and management as well as determinants of timber income of small-scale timber producers between the cases. Accounting for 33–56% of total household income, Acacia hybrid timber plantations played a crucial role in the current livelihood system. Nevertheless, timber income was skewed toward the wealth status of timber producers and ranged between 327 USD/household and 3387 USD/household in Nam Dong and between 397 USD/household and 9460 USD/household in Phu Loc district. Despite the substantial contribution the income from Acacia hybrid plantations could make to local poverty reduction, it was the main contributor to the overall income inequality. While this income source reduced the Gini coefficient by 1% in Nam Dong, it increased the Gini coefficient by 18% in Phu Loc district. Our study can be of interest for further policy interventions focusing on sustainable reforestation and livelihood development in Vietnam. Full article

A novel endophytic actinomycete strain GKU 173^T isolated from the roots of Acacia mangium Willd. showed potential plant growth promoting (PGP) activity. Phylogenetic analysis, based on 16S rRNA gene, indicated that strain GKU 173^T was the most closely related to Fodinicola feengrottensis HKI 0501^T—the only species in the genus Fodinicola. Morphology and chemotaxonomy of strain GKU 173^T indicated that it belongs to the genus Fodinicola by having meso-diaminopimelic acid in the cell wall and xylose as the characteristic cell-wall sugars. The cellular fatty acid profile mainly comprised iso-C_16:0, anteiso-C_17:0, iso-C_18:0, and iso-C_17:0. The major menaquinones were MK-9(H₄), MK-9(H₆), and MK-9(H₈). The main polar phospholipids contained diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), and phosphatidylinositol (PI). Genome analysis signified DNA G+C content of 67.81 mol%. The level of digital DNA-DNA relatedness between strain GKU 173^T and the type strain was 21.30%. On the basis of polyphasic characteristics, strain GKU 173^T clearly represents a novel species of the genus Fodinicola, for which the name Fodinicola acaciae sp. nov. (= TBRC 10620^T = NBRC 114213^T) is proposed. Furthermore, genome analysis of both strains suggested that members of the genus Fodinicola are promising sources of beneficial PGP-actinomycetes and novel secondary metabolites. Full article

Forest plantations have expanded rapidly in response to financial support from the state and local governments and have had significant positive impacts on rural livelihoods and development in Vietnam, since the late 1980s. This study used net present value (NPV) and internal rate of return (IRR) to examine the economic performance of plantations for three species, Acacia mangium Willd, Eucalyptus (Eucalyptus urophylla S.T. Blake × Eucalyptus camaldulensis Dehn), and Manglietia conifera Dandy, in Bac Kan province. On the basis of an annual discount rate of 6%, the results showed that rural households earned positive financial returns from forest plantations with seven-year rotations. Eucalyptus generated the highest NPV but A. mangium generated the greatest IRR. The plantations were facilitated by financial support from the state, land tenure reforms, and wood exports. The results provide valuable business information and policy implications for both local farmers and policy makers. Since the farmers consider more of the short term and economic return of the plantations, the results provide valuable information for policy makers to apply subsidies and other support to promote plantations with significant ecological and environmental benefits for sustainable development of rural economies. Full article

Prerequisite for selection of appropriate tree species in afforestation programs is to understand their water use strategy. Acacia mangium Willd., Schima wallichii Choisy, and Cunninghamia lanceolata (Lamb.) Hook are the three main vegetation restoration pioneer species in southern China, but no comparative research on the water use strategy of these three tree species have been reported. Our objective was to gain a detailed understanding of how photosynthetically active radiation (PAR), vapor pressure deficit (VPD), and soil water content (SWC) at different soil depths control the sap flux density (J_s) in the dry and wet seasons. We measured the J_s of these three tree species by using the thermal dissipation method in low subtropical China. We found that both S. wallichii and C. lanceolata differed clearly in their stomatal behavior from one season to another, while A. mangium did not. The canopy conductance per sapwood area of S. wallichii and C. lanceolata was very sensitive to VPD in the dry season, but not in the wet season. The J_s of A. mangium was negatively correlated to SWC in all soil layers and during both seasons, while the other two species were not sensitive to SWC in the deeper layers and only positively correlated to SWC in dry season. Our results demonstrate that the three species have distinct water use strategies and may therefore respond differently to changing climate. Full article

Eucalyptus pellita has rapidly emerged as the species that has replaced Acacia mangium in broad-scale commercial plantations in Indonesia following widespread losses due to disease and in soils that have suffered a steady decline in phosphorus (P) under plantation forestry. Conversion from a nitrogen (N)-fixing to a non-N fixing species is expected to change the nutrient dynamics and the management required to maximise productivity. In this study in South Sumatra, responses of E. pellita to the application of N, P, potassium (K) and calcium (Ca) fertilisers were assessed at a number of trials on sites with varying site history; A. mangium was planted at one site to compare the species’ responses to N and P. The growth of E. pellita responded significantly (p < 0.01) to P’s application but not to N, K or Ca, with the addition of P increasing the stem volume by 32.6 m³ ha⁻¹ at 3 years of age compared with no addition of P fertiliser; the demand for P in the first two years of growth was, respectively, 4.8 and 6.8 kg ha⁻¹. This positive and large response appears to be because E. pellita has a lower efficiency in its use of P than A. mangium and is, therefore, more responsive than A. mangium to the addition of P. The reason for the lack of response to N remains unclear, although demand for N as well as K and Ca was high. These results suggest that sites recently converted to E. pellita from A. mangium and also new ex-native forest sites will be likely to only respond to P addition and that the response of E. pellita is likely to be greater than for A. mangium to maximise yield. At present, additional N, Ca or K fertilisers are not required, but this may change in the future. Full article

Harvest residues can play a crucial role in conserving nutrients for recycling in forests, but little is known about the rates of decomposition and nutrient release from these residues following logging in tropical acacia plantations. In this study, we examined the biomass and nutrient content of harvest residue components (bark, leaves, and branches) using the litterbag technique for a 1.5-year-period following harvest of a seven-year-old Acacia mangium plantation in Northern Vietnam. At harvest, the total dry biomass of harvest residues was 18 t ha⁻¹ comprising bark (8.9 t ha⁻¹), branches (6.6 t ha⁻¹), and leaves (2.5 t ha⁻¹). The retained bark on site conserved 51% N, 29% P, 32% K, 64% Ca, and 24% Mg content from harvest residues for recycling. Decomposition rate of the leaves was the most rapid (k = 1.47 year⁻¹; t_0.5 = 0.47 year), then branches (k = 0.54 year⁻¹; t_0.5 = 1.29 year), and bark (k = 0.22 year⁻¹; t_0.5 = 3.09 year). During decomposition, the loss of nutrients from harvest residues was K ≈ Ca > N > P> Mg. Decomposition of harvest residues and the associated rate of nutrient release can potentially supply a significant amount of nutrients required for stand development in the next rotation. Full article