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  • Open access
  • 29 Reads
Eucalypt clonal hybrid influence the carbon amount of below-ground biomass in Oxisol, Brazil

The objective of this study was to evaluate whether there is the influence of different clonal hybrids of Eucalyptus urophylla on the carbon concentration and amount in below-ground biomass in trees cultivated in Oxisol, Brazil. Stumps and roots of three different eucalypt hybrid clones, AEC 0144, AEC 0223, and VM01, were selected, weighed immediately after removing from the ground, and sampled for carbon determination and moisture content at the laboratory. The Shapiro-Wilk’s and Bartlett tests were used to evaluate data distribution and the homogeneity of variances, respectively. Analysis of variance (ANOVA) complemented by the Scott-Knott test was used to evaluate the effects of specie/hybrid on the below-ground biomass (dry matter) and carbon amount per stump. The hybrid type of Eucalyptus urophylla does not influence the carbon concentration; however, there is a difference in below-ground biomass production and carbon amount being higher for Eucalyptus urophylla x Eucalyptus camaldulensis when compared to the species Eucalyptus urophylla and hybrid Eucalyptus urophylla x Eucalyptus grandis.

  • Open access
  • 49 Reads
Physical, chemical, and mechanical properties of two-age Bambusa tuldoides briquettes

The use of natural resources as an energy source is a well-studied alternative to fossil fuels. Some studies present bamboo as promising biomass for energy generation, and its transformation into briquettes can be a way to take advantage of its production residues. The objective of this study was to determine the physical and chemical properties of two bamboo ages (two and seven years old) of Bambusa vulgaris species, to evaluate the quality of biomass and its briquettes for energy generation. Regarding the higher heating value, there was no difference between treatments means values, which were 17.8 and 18.2 MJ kg-1 for two and seven years old, respectively, and these values were slightly below those found in the literature for Bambusa spp. The mechanical durability was of low quality for both treatments at the testing conditions, so they are not recommended for briquette production. The results of the proximate analysis were quite near to the literature and reinforce the positive qualities of bamboo for biofuel usage.

  • Open access
  • 19 Reads

Research Highlights: This study used the GOL (Growth-Oriented Logging) model, a concept for the sustainable management of timber resources in tropical forests, which aims to determine the growth model, the minimum logging diameter (MLD) and the cutting cycle (CC), defining these criteria for forest management by species. Background and Objectives: The objective of this work was to define specific forest management criteria for Manilkara huberi (Ducke) A. Chev. species through growth and increment models in diameter and volume, using Dendrochronology study by high frequency densitometry. Materials and Methods: The study was carried out in a forest management area in an upland forest in Central Amazonia. The studied species forms annual growth rings depending on the seasonal rainfall. To define the annual growth rings, a high frequency densitometry technique was applied, measuring the density variations in relation to the wood surface, from pith to bark, in high resolution, using the dielectric properties of the wood. With the time series of the annual growth rings thickness obtained, it was possible to determine the MLD and CC, thus being able to propose the most adequate management for the studied species. Results: The minimum logging diameter obtained was approximately 63.4 cm, and its cut cycle estimated at 47 years, mean time estimated to pass through classes of 10 cm in diameter, until reaching MLD with the age of 297 ± 13.8 years. The estimated volume, equivalent to MLD is 6.97 m3. Conclusions: The high-frequency densitometry method allowed the establishment of a growth model through the GOL method, and allowed the determination of criteria for species-specific forest management, being possible to use it for tropical, upland species, with the same characteristics of this species.

  • Open access
  • 15 Reads
Analysis of Dynamic Forest Structures Based on Hierarchical Features Extracted from Multi-station LiDAR Scanning

The point cloud distribution data were used for the first time to extract the characteristic parameters of tree trunks via multi-station scanning. The established hierarchical feature-based volume model will provide a reference for utilizing terrestrial laser scanning (TLS) to monitor dynamic changes in forest resources. Background and Objectives: The rapid development of active remote sensing laser scanning technology has led to the accumulation of substantial data on long-term forest changes. However, questions remain about how these data can be used to facilitate the accurate analysis of forest dynamics and which parameters can be used to reflect the high-precision information provided by point cloud data. Materials and Methods: This study collected three phases of data over 5 years from an artificial Liriodendron chinense forest. A series of the height-related characteristic parameters was extracted from the scanned points of each tree stem, which includes a novel feature of the height cumulative percentage (Hz%) proposed by us. Meanwhile, taking the manually measurements directly from the terrestrial laser scanning (TLS) data as the ground truth, the performance of various models combined with the characteristic parameters on the prediction of the wood volume of each tree was evaluated for the purpose of determination of the optimal parameters and prediction models suitable for the tree species of Liriodendron chinense. Results: The upper diameter accuracy obtained by multi-station scanning is high, and the correlation coefficient with manually measured data is 0.9864. The shape of the upper tree trunk extracted by the point cloud is equivalent to that of the analytical tree with inflection points at 25% and 50% of the height. Among the correlations between the hierarchical features and volumes, the parameters with the highest correlations are H25 and H50. The hierarchical parameters were selected for volume modeling. H25 and diameter at brest heigh (DBH) were used for all three phases, for which the fitted R2 reached 0.951, 0.957 and 0.901. The modeled dynamic volume change was highly correlated with the actual point cloud-extracted volume change. In the linear relation, the intercept is -0.081, and the slope is 1.14. Conclusions: The Hz% value provided by multi-station scanning was closely related to the characteristic stumpage parameters and could be used to invert the dynamic forest structure. The volume model based on point cloud hierarchical parameters could be used to monitor the dynamic changes in forest volume and provide an updatted reference for applying TLS point clouds for the dynamic monitoring of forest growth information.

  • Open access
  • 104 Reads
Basic examination on the harvesting of small-diameter trees as unutilized forest biomass in Japan

In order to secure the supply source as well as promote the further utilization of “Untapped wood” following the completion of the Feed-in Tariff Scheme for Renewable Energy (FIT), small-diameter trees such as not only cleanings from young planted forests but also broad-leaved trees from coppice forests can be expected to be prospective in Japan. In order to discuss the effective method of harvesting such small-diameter trees as unutilized forest biomass appropriate for Japan, a basic model forest was assumed in this study, while the harvesting of small-diameter trees was experimented with a truck-mounted multi-tree felling head and time-studied. As a result, the machine used in the experiment could fell the maximum six trees inward a row from a forest road, but the harvesting (felling, accumulating, and chipping) cost was the cheapest when the machine felled five trees inward a row. The results of the sensitivity analysis suggested what kind of improvement should be necessary for the felling machine used in the experiment.

  • Open access
  • 86 Reads
Modifications of physical and mechanical characteristics induced by heat treatment: case study on Ayous wood (Triplochiton scleroxylon K. Schum)

Wood is a material of biological origin of fundamental importance for artisan and industrial uses. Its physical and mechanical properties make it suitable for the most diverse uses. In outdoor environments it is very attractive. However, being a material of biological origin, it is subject to degradation if exposed to the main degradation agents such as water, sunlight, temperature variations, biological attacks. To improve the durability of wood materials, preservatives are generally used, which can limit the effects caused by wood degradation agents. These treatments with toxic compounds to enhance natural durability have a high impact in terms of environmental pollution and human health, as well as significant costs. A valid alternative to chemical preservatives, which is increasingly established and widespread, is the thermal modification of the wood material. It consists in treating the wood at high temperature for exposure time depending on the desired objectives but limited to a few hours. The effects consist in the modification of the chemical structure of the wood, due to the degradation of hemicelluloses and cellulose, which results in a variation of the physical-chemical characteristics that make it more resistant to degradation.

The aim of this study is to evaluate the Ayous wood, (Triplochiton scleroxylon K. Schum), which was industrially subjected to thermal modification, in order to emphasize the influence of heat treatment on selected physical and mechanical characteristics. The thermally modification was conducted on planks of Ayous in an industrial system that used a slight initial vacuum in an autoclave (Maspell WDE Model TVS 6000) and a treatment temperature of 215 °C for three hours.

As a result of the heat treatment, the physical characteristics are generally reduced: the density in natural wood (TQ) was 379 kg/m3, in heat treated wood (TT) 319 kg/m3; the basal density in TQ was 327 kg/m3 in TT 299 kg/m3; shrinkage was significantly reduced in heat treated wood. Similarly, there was a general reduction in the mechanical properties of heat-treated wood compared to natural wood: the axial compression strength of heat-treated wood was reduced by 19%; the static bending strength of the heat-treated product was reduced by 41%. In addition, the samples, under the same environmental conditions in the laboratory, reached the equilibrium moisture content of 10% on TQ and 4% on TT. The Brinell hardness was reduced in TT. On the basis of the results of tests conducted on industrially heat treated wood, a decrease in the values of the selected physical and mechanical parameters was found, mainly due to deterioration of the structure and degradation of the cell wall compounds, evidence also confirmed by the equilibrium moisture content under laboratory conditions which was much lower than that of natural wood.

  • Open access
  • 34 Reads
Spatial-temporal analysis of the forest fragments surrounding a conservation unit in southern Brazil

In recent years, anthropogenic actions have intensified forest fragmentation, causing several damages to the landscape’s natural components, such as the loss of biodiversity. This study aims to present a space-time analysis of the forest fragments found in a conservation unit located in southern Brazil. An evaluation of the fragments’ spatial pattern was carried out for the years 1998, 2008 and 2018, by using landscape metrics. Classification of remote sensing imagery of the Landsat satellite were applied to generate land use cover maps. The following metrics were analyzed: area and edge, shape, core area, and aggregation. The results indicated an increase of 16.88% in the total area of vegetation. As a consequence, the percentage of fragments in the landscape increased from 16.16% to 18.89%. The number of fragments decreased by 2257 due to their union, which resulted in an increase of the mean area by 5.4 ha and an increase by 0.103 of the irregularity of the spots measured by the average shape index. The percentage of vegetation under border effect changed from 40.2% to 37.1%. Isolation between fragments showed a decrease over the analyzed period. In 1998, the average Euclidean nearest neighbor distance was 155.4 m, and in 2018, 149.7 m. However, this distance is still classified as a high degree of isolation, which hinders the movement of organisms and the dispersion of species. Thus, all the analyzed metrics indicated a decrease in the fragmentation, except for the edge density metric, in which its increase by 1.86 pointed to a lower degree of conservation during the analyzed period. A study of this nature is important since it provides subsidies for future research on the management of forest fragments and can contribute to adopting action strategies in the management plan of the area.

  • Open access
  • 30 Reads
Exploring the Relationship between Forest Structure and Health

There are many evidences that green space in urban neighborhood is associated with physical activity and it is well known that physical activity contributes to human health. Physical activity fosters normal growth and development, can reduce the risk of chronic diseases, and can make people feel better and function better. Evidences also show that exposure to natural places can lead to positive mental health outcomes, whether a view of nature from a window, being within natural places, or exercising in these environments. The study aims to identify the factors of forest structure and socioeconomic characteristics influencing adults’ physical activity and health. A sample of 148,754 respondents from the Korea Community Health Survey, conducted in 2016, was analyzed. Measures included frequency of physical activity, stress, depression, and landscape metrics of forest patch. Hierarchical multiple regression analysis, controlling for socio-demographic characteristics, revealed that larger forest patches and the more irregular shapes were associated with more physical activity. The study also showed that the shape of forest patch and slope were associated with less mental health complaints, whereas composition related landscape metrics were not.

  • Open access
  • 36 Reads
Savannas are more sensitive to rainfall variability than riparian forests

Reported changes in precipitation may impact processes linked to growth and survival, with potential consequences to carbon balance in the tropics. Furthermore, precipitation regimes partially modulate the occurrence of forests and savannas in these regions. However, the local mechanisms responsible for the resilience of those ecosystems remain uncertain. We aim at understanding how forests and savannas under the same precipitation regime respond in terms of GPP to seasonal rainfall variability. We hypothesize that savannas respond faster to precipitation by changing their greenness (EVI2) because savanna trees and grasses usually occur in areas far away from the water table, while riparian forests occur in valleys with shallower water tables. We sampled a total of 20 (200m2) field plots, with 10 in cerrado stricto sensu (savanna) and 10 in riparian evergreen forests, at the Chapada dos Veadeiros National Park (PNCV), located within the Cerrado biome, in Brazil. We measured tree cover using a concave densiometer, and calculated the coupling, i.e. Kendall correlation, between EVI2 from Landsat8 and the monthly precipitation calculated from CHIRPS dataset, using time-series from 2013 through 2018. In savannas where trees and grasses co-exist, we standardized coupling values by tree cover to account only for the effect savanna trees have on the EVI2. Forests and savannas respond differently to precipitation. Maximum coupling in savannas is greater than in forests but when considering only trees in both ecosystems, we found similar responses. Furthermore, savannas respond faster than forests. Our results indicate that the GPP may depend on the proximity of the water table. However, further studies are necessary to understand which mechanisms are driving the patterns found here. Therefore, forests and savannas at the PNCV are functionally distinct, in agreement with structural differences they present, particularly taking into account the differences in the response time of forest and savanna communities.

  • Open access
  • 30 Reads
Seasonal variation of wild ungulates abundance in a hunting ban beech forest. The case study of Amiata Mountain - Central Italy

Several studies focused on the impact of ungulates on agricultural systems but the magnitude of their antagonistic role in forest renovation dynamics has long been underestimated and rarely considered. Ungulate species abundance is susceptible to seasonal variations according to their autecology, human management choices and territorial planning. Therefore, the appropriate choice of counting period is crucial. In this case study, we used camera traps to assess wild boar and roe deer seasonal abundance variations in a 600 hectares hunting ban beech forest (95.48%) in southern Tuscany managed for timber production. Camera-trapping sessions were performed in both early summer and autumn. The roe deer abundance index is higher in early summer, although statistically not significant, potentially affecting seedling survival. Inversely, wild boars significantly (F = 79.125; p = 0.001) increase their abundance at the local scale in autumn when, probably according to the ecology of fear, they temporary shift home range toward refuge areas. In autumn, high density of wild boars can reduce seed availability at local scale. Further analysis assessing the correlation between seasonal wild ungulates abundance and forest regeneration rate are in progress, based on data recorded within and around three fenced sample plots.