Search Results (7)

Soil aggregates play a crucial role in maintaining the health and stability of artificial forest soil ecosystems, and microorganisms contribute to the formation and maintenance of soil aggregates. However, the impact of different tree species in mixed forests on soil aggregate microbial communities remains unclear. In this study, high-throughput sequencing technology was employed to analyze the bacterial and fungal diversity and community composition of four soil aggregate sizes (<0.25 mm, 0.25–1 mm, 1–2 mm, and >2 mm) in pure Castanopsis hystrix plantations (CK), mixed C. hystrix and Acacia crassicarpa plantations (MCA), mixed C. hystrix and Pinus massoniana plantations (MCP), and mixed C. hystrix and Mytilaria laosensis plantations (MCM). The results indicate that (1) establishing mixed forests enhances the diversity of bacterial and fungal communities in soil aggregates, and that soil aggregates with size <0.25 mm support higher microbial diversity. (2) The fungal and bacterial composition of soil aggregates in mixed forests differs from that of pure C. hystrix forests. The dominant bacterial phyla in the four forest types are Proteobacteria, Acidobacteria, Actinobacteria, and Chloroflexi. The dominant fungal phyla are Basidiomycota, Ascomycota, Mortierellomycota, and Mucoromycota. (3) PCoA analysis reveals that compared to pure C. hystrix forests, mixing with A. crassicarpa (MCA) results in marked changes in the bacterial community structure of soil aggregates; similarly, mixing with A. crassicarpa (MCA) and M. laosensis (MCM) leads to significant differences in the fungal community structure of soil aggregates. (4) RDA results show that NH₄⁺-N, pH, and OC are the main factors influencing microbial diversity in soil aggregates. In terms of dominant microorganisms, pH and AP are the key environmental factors affecting the structure of bacterial and fungal communities in soil aggregates. The findings of this study contribute to our understanding of the characteristics of microbial communities in soil aggregates affected by tree mixing and provide a scientific reference for the maintenance and enhancement of soil fertility in planted forests. Full article

Nutrient resorption (NR) is a critical ecological process in forest ecosystems. However, there is a lack of knowledge about this process in the peatlands of Indonesia, and this may be seen as a research gap. In the present study, NR in young trees of three native species (Macaranga pruinosa, Cratoxylum arborescens, and Macaranga gigantea) and one exotic species (Acacia crassicarpa) in a drained tropical peatland was investigated. This study was conducted at an experimental plot in Pelalawan-Riau, Indonesia. Nutrient resorption efficiency (RE) and proficiency (RP) were calculated and correlated with soil properties, foliar nutrients, and growth variables. Our results revealed that M. pruinosa exhibited an RE value for phosphorus (PRE) that was 64% higher than that for the second-ranked native species but still significantly (84%) lower than that for A. crassicarpa. RE values for nitrogen (NRE) and potassium (KRE) did not differ significantly among species, ranging from 39 to 42% and 41 to 56%, respectively, for native species, with figures of 45% and 66%, respectively, for A. crassicarpa. Finally, PRE exhibited strong and significant correlations with PRP and tree growth, a finding that indicated that the uptake and conservation of P nutrients are essential for the fitness of the three native species. Overall, the results of the present study may be seen as beneficial for species selection and the management of nutrients by those engaged in restoration of tropical peatland forests. Full article

Maturation-related loss in the shooting and rooting ability of a species through macro or micropropagation techniques has been a limiting factor in any forest tree improvement program. The rejuvenation capacity of mature elite trees of Acacia mangium, Acacia crassicarpa, Acacia auriculiformis, and Acacia aulococarpa was investigated by evaluating the sprouting ability of decapitated trunks. Thus, a total of 120 trees were selected based on their superior phenotypic characteristics from four provenance and five progenies of each species, and trunks of the elite trees were decapitated into two different height groups to induce coppicing from the collar and base of the trunk. Coppicing ability varies with species, provenance, progeny, and cutting height. A. auriculiformis was the easiest to produce shoots by having the highest shooting percentage (84%) and the number of shoots per trunk (13.5), followed by A. mangium (75%) and A. aulococarpa (40%). The total shoot number increased significantly with the increase in the height of the stumps. Data indicated that there is a possibility to rejuvenate matured cutting through coppicing in the natural environment. This study will help in the standardization of the stumping procedure for the rejuvenation of elite Acacia genotypes while simultaneously assisting in preserving germplasm through clonal propagation. 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

Reactive oxygen species (ROS) are related to several degenerative diseases. In this study, Acacia, a genus with many fast-growing species, was investigated to explore the many phytochemical compounds that are biologically active in processes dealing with ROS-related diseases. This study aimed to select extracts of Acacia heartwood on the basis of their pharmacological and phytochemical profiles and identify their bioactive compounds. Five methanolic extracts from Acacia heartwood were evaluated for their antioxidant activity using three different in vitro assays: toxicity toward Artemia salina and phenolic and polyphenolic content. Multivariate analysis was conducted to select two promising extracts and then their bioactive compounds were identified using liquid chromatography coupled with mass spectrometry. Acacia crassicarpa extracts showed the highest antioxidant activity, as well as phenolic and hydrolyzable tannin contents, but low toxicity. The A. mangium extract exhibited high flavonoid and condensed tannin content, whereas A. decurrrens had the highest toxicity with low antioxidant activity. Pearson’s correlation analysis demonstrated no correlation between antioxidant activity and toxicity. Moreover, the phytochemical profile exhibited an association with pharmacological parameters. Principal component analysis followed by cluster analysis divided the extracts into three clusters. Two heartwood extracts of A. crassicarpa and A. auriculiformis were chosen as the best extracts. Identification showed that these extracts were dominated by phenolic compounds, as well as anthraquinone and xanthone. Full article

Research Highlights: This study provides a comprehensive set of wood and pulping properties of Acacia crassicarpa A.Cunn. ex Benth. to assess variation and efficient sampling strategies for whole-tree level phenotyping. Background and Objectives: A. crassicarpa is an important tree species in Southeast Asia, with limited knowledge about its wood properties. The objective of this study was to characterize important wood properties and pulping performance of improved germplasm of the species. Furthermore, we investigated within-tree patterns of variation and evaluated the efficiency of phenotyping strategies. Materials and Methods: Second-generation progeny trials were studied, where forty 50-month-old trees were selected for destructive sampling and assessed for wood density, kraft pulp yield, α-cellulose, carbohydrate composition, and lignin content and composition (S/G ratio). We estimated the phenotypic correlations among traits determined within-tree longitudinal variation and its importance for whole-tree level phenotyping. Results: The mean whole-tree disc basic density was 481 kg/m³, and the screened kraft pulp yield was 53.8%. The reliabilities of each sampling position to predict whole-tree properties varied with different traits. For basic density, pulp yield, and glucose content, the ground-level sampling could reliably predict the whole-tree property. With near infrared reflectance spectroscopy predictions as an indirect measurement method for disc basic density, we verified reduced reliability values for breast height sampling but sufficiently correlated to allow accurate ranking and efficient selection of genotypes in a breeding program context. Conclusions: We demonstrated the quality of A. crassicarpa as a wood source for the pulping industry. The wood and pulping traits have high levels of phenotypic variation, and standing tree sampling strategies can be performed for both ranking and high-accuracy phenotyping purposes. Full article

In order to understand how carbon storage and allocation patterns vary among plantation types, we estimated carbon allocation between above- and below-ground compartments in four subtropical plantations and a naturally recovered shrubland (as a control). Results indicated that the carbon storage and allocation pattern varied greatly among forest types and was highly dependent on specific traits of trees and understory vegetation. The fast-growing species, such as Eucalyptus urophylla, accumulated more carbon in plant biomass. The biomass carbon was about 1.9- and 2.2-times greater than the 10-species mixed plantation and Castanopsis hystrix plantations, respectively. Meanwhile, the plantations sequestered 1.5- to 3-times more carbon in biomass than naturally recovered shrubland. The carbon allocation pattern between above- and below-ground compartments also varied with plantation type and stand age. The ratio of tree root carbon to tree aboveground carbon decreased with stand age for Eucalyptus urophylla and the 10-species mixed plantation. In contrast, the ratio increased for Acacia crassicarpa. Our data suggested that planting the fast-growing species in the degraded land of subtropical China was an effective choice in terms of carbon sequestration. The information about carbon allocation patterns was also valuable for decision making in sustainable forest management and climate change mitigation. Full article