Two new tetralone derivatives named xylariol A （1） and B （2） were isolated from the EtOAc extract of the culture broth of Xylaria hypoxylon AT-028 （Xylariaceae）, and their structures were elucidated by MS, 1R, 1...Two new tetralone derivatives named xylariol A （1） and B （2） were isolated from the EtOAc extract of the culture broth of Xylaria hypoxylon AT-028 （Xylariaceae）, and their structures were elucidated by MS, 1R, 1D- and 2D-NMR spectra, and by X-ray diffraction analysis. 1 and 2 showed moderate cytotoxic activities against Hep G2 cells in the in vitro cytotoxic assay with IC50 values of 22.3 and 21.2 μg/mL, respectively.展开更多
Savannas constitute a mixture of trees and shrub patches with a more continuous herbaceous understory.The contribution of this biome to the soil organic carbon(SOC)and above-ground biomass(AGB)carbon(C)stock globally ...Savannas constitute a mixture of trees and shrub patches with a more continuous herbaceous understory.The contribution of this biome to the soil organic carbon(SOC)and above-ground biomass(AGB)carbon(C)stock globally is significant.However,they are frequently subjected to land use changes,promoting increases in CO_(2) emissions.In Uruguay,subtropical wooded savannas cover around 100,000 ha,of which approximately 28%is circumscribed to sodic soils(i.e.,subtropical halophytic wooded savannas).Nevertheless,there is little background about the contribution of each ecosystem component to the C stock as well as site-specific allometric equations.The study was conducted in 5 ha of subtropical halophytic wooded savannas of the national protected area Esteros y Algarrobales del Rio Uruguay.This work aimed to estimate the contribution of the main ecosystem components(e.g.,soil,trees,shrubs,and herbaceous plants)to the C stock.Site-specific allometric equations for the most frequent tree species and shrub genus were fitted based on basal diameter(BD)and total height(H).The fitted equations accounted for between 77%and 98%of the aerial biomass variance of Netuma affinis and Vachellia caven.For shrubs(Baccharis sp.),the adjusted equation accounted for 86%of total aerial biomass.C stock for the entire system was 116.71±11.07 Mg·ha^(-1),of which 90.7%was allocated in the soil,8.3%in the trees,0.8%in the herbaceous plants,and 0.2%in the shrubs.These results highlight the importance of subtropical halophytic wooded savannas as C sinks and their relevance in the mitigation of global warming under a climate change scenario.展开更多
We investigated the effects of precommercial thinning(PCT)applied at different levels on the growth parameters of natural Anatolian black pine stand.The experimental site was located in the province of Isparta in sout...We investigated the effects of precommercial thinning(PCT)applied at different levels on the growth parameters of natural Anatolian black pine stand.The experimental site was located in the province of Isparta in southern Turkey.PCT was set up using a randomized complete block design with three replicates and three treatments(control,2–2.5 m×–2.5 m and 3–3.5 m×–3.5 m spacing).The experimental plots were established in March 2014.At the end of the growing seasons for three years(2014–2016),growth parameters such as diameter,height and crown radius were measured.PCT was found to be significantly effective on diameter,height,individual tree basal area,and crown radius increment at the end of the third year(p<0.05).While diameter,individual tree basal area and crown radius increment increased with increasing PCT intensity,height increment was higher in control than PCT.Although the PCT treatments applied with 3–3.5 m spacing affected individual tree development positively,we need long-term results on wood quality and yield.According to the short-term results,it is thought that it is better to lower the stand closeness gradually,so,it may be advisable to apply PCT by 2–2.5 m×–2.5 m spacing.展开更多
Changes in forest diversity and the transforma- tion of coniferous plantations into more natural woodlands are of special interest in the Medi- terranean. The aim of this study was to investi- gate changes in land use...Changes in forest diversity and the transforma- tion of coniferous plantations into more natural woodlands are of special interest in the Medi- terranean. The aim of this study was to investi- gate changes in land use patterns and vegeta- tion cover from 1956 to 1999 in Pinus halepensis Miller plantations in Montes de Málaga State Park in southern Spain. At the landscape level, a FRAGSTAT analysis was performed using aerial photographs. At the community level, a total of 47 sample plots were analyzed. Field measure- ments indicated the presence of a total of 70 species in the different vegetation types sam- pled. Shannon-Wiener (H), and Simpson’s (D) diversity indices showed the greatest species richness in Aleppo pine plantations (H = 1.54 ± 0.2;D = 3.88 ± 0.6), while Holm oak stands in the forested areas (H = 1.37 ± 0.1;D = 3.35 ± 0.6) and agricultural land (H = 1.33 ± 0.01;D = 2.80 ± 0.03) had lower values. FRAGSTATS analyses at land- scape and community levels indicated increases in patch richness, patch number, and percent of landscape mainly for pine plantations, Holm oak forests and shrub habitats. Replacement of agri- culture by conifer plantations led to the homo- genization of landscape structure. This change has modified the landscape by facilitating the recovery of indigenous tree species including Holm oak, which will likely lead to the future establishment of native forests in this area. Our findings suggest that pine plantations could fa- vour woody species diversity by increasing abundance and species richness in contrast to the situation in non-forested agricultural land.展开更多
The relationships between climate conditions and wood density in tropical forests are still poorly understood.To quantify spatial dependence of wood density in the state of Minas Gerais(MG,Brazil),map spatial distribu...The relationships between climate conditions and wood density in tropical forests are still poorly understood.To quantify spatial dependence of wood density in the state of Minas Gerais(MG,Brazil),map spatial distribution of density,and correlate density with climate variables,we extracted data from the Forest Inventory of Minas Gerais for 1988 trees scaled throughout the territory and measured wood density of discs removed from the trees.Environmental variables were extracted from the database of the Ecological-Economic Zoning of Minas Gerais.For spatial analysis,tree densities were measured at 44 georeferenced sampling points.The data were subjected to exploratory analysis,variography,cross-validation,model selection,and ordinary kriging.The relationships between wood density and environmental variables were calculated using dispersion matrices,linear correlation,and regression.Wood density proved to be highly spatially dependent,reaching a correlation of 96%,and was highly continuous over a distance of 228 km.The distribution of wood density followed a continuous gradient of 514-659 kg m^(−3),enabling corre-lation with environment variables.Density was correlated with mean annual precipitation(−0.57),temperature(0.63),and evapotranspiration(0.83).Geostatistical methods proved useful in predicting wood density in native tropical forests with different climate conditions.Our results confirmed the sensitivity of wood density to climate change,which could affect future carbon stock in forests.展开更多
The objective of this work was to compare estimates generated by a diametric distribution model and a total stand model against the pre-cut inventory.The model efficiency was also evaluated.Data were evaluated from 30...The objective of this work was to compare estimates generated by a diametric distribution model and a total stand model against the pre-cut inventory.The model efficiency was also evaluated.Data were evaluated from 30 permanent sample plots in a Eucalyptus urophylla stand,comprising 24 sample plots used for model fitting,and six sample plots for validation.The volume of wood per hectare was estimated for different productive units(sites),using 7 years as the reference age.The model adjustment quality was verified by adjustment and precision statistics:the correlation between observed and predicted variables,root mean square error percentage,graphical analysis of residual distribution,and a frequency histogram for classes of relative errors and validation.Although the two-parameter Weibull probability density function adhered to the data for tree evolution in diameter classes for the reference age(7 years)in the different productivity classes,it generated imprecise estimates of the number of individuals.Consequently,it produced inaccurate volumetric production estimates.The total stand model provided reliable projections of production volumes in different productivity classes for both adjustment types,showing compatibility with the pre-cut inventory according to a Tukey test.In summary,the total stand model generated estimates that were compatible with the pre-cut inventory while the diametric distribution model did not.展开更多
This research assessed the relationship between wood physical-anatomical variables and charcoal physical-mechanical properties.Nine trees were harvested and mechanically processed into standard pieces for laboratory a...This research assessed the relationship between wood physical-anatomical variables and charcoal physical-mechanical properties.Nine trees were harvested and mechanically processed into standard pieces for laboratory analysis.The following variables were determined:wood density,fiber length and width,fiber lumen diameter and wall thickness,fiber wall fraction,and vessel frequency.The charcoal was produced in a laboratory and gravimetric yield,relative density,and mechanical properties established.Pearson’s correlation coefficients,multivariate statistical analysis of canonical correlation,and principal component analysis were used to evaluate the relationship between wood and charcoal properties.Fiber width was not significantly correlated with charcoal properties.Charcoal bulk density,hardness,and strength were positively correlated with wood density,fiber length,wall thickness,and wall fraction.Charcoal properties were negatively correlated with fiber lumen diameter and vessel frequency.These results will help identify the best wood with adequate physical-mechanical properties for industrial charcoal proces sing.展开更多
In North Africa, Cedrus atlantica forests are in decline, following decades of anthropogenic pressure and repeated drought events. Mixed C. atlantica-Quercus ilex stands located in the Theniet El Had National Park (no...In North Africa, Cedrus atlantica forests are in decline, following decades of anthropogenic pressure and repeated drought events. Mixed C. atlantica-Quercus ilex stands located in the Theniet El Had National Park (northwestern Algeria) were considered in the present study. Based on a stratified sampling, six temporary plots were established to describe structure (species composition, density, total height, diameter and basal area) and radial growth in relation to type of stand (pure and mixed), using a dendroecological approach. The diameter distribution of C. atlantica indicated the presence of few young individuals and a poor regeneration status in all the stands. The density and basal area of C. atlantica were significantly higher in pure stands, which necessitate silvicultural operations. In contrast, Q. ilex showed a progressive dynamic, at moderate altitude. Radial growth showed a significant decline from 1980 to the 2000s. The absence of an appropriate management plan and the increase in anthropogenic effects, without ruling out a role for the current climate conditions marked by drought, seem to be the causes of C. atlantica decline.展开更多
In integrated factories of pulp and paper, the bleaching control is made by kappa number and/or brightness. However, the product paper is evaluated and valued for its whiteness. The level of final brightness of pulp c...In integrated factories of pulp and paper, the bleaching control is made by kappa number and/or brightness. However, the product paper is evaluated and valued for its whiteness. The level of final brightness of pulp certainly affects the demand for optical brighteners in paper manufacturing, nevertheless, there is not a direct correlation between consumption of optical brightener and final brightness, being the method of bleaching pulp, especially from the final stage of bleaching, also important in relation to this demand. Therefore, this study aimed to evaluate the potential of using the parameter whiteness as a tool to control bleaching pulp, instead of the traditional brightness and evaluate the impacts of different methods of bleaching and the pulp final brightness level in action of optical brighteners, to improve their performance. It was observed that the whiteness and brightness of the pulp are highly correlated and that the control of the bleaching plant can be done by any one of these two parameters. It was also concluded that, considering current prices of bleaching reagents and of optical brighteners, it is better to bleach the pulp up to lower brightness values (e.g. 88% ISO) and use larger amounts of optical brighteners to brighten the mass until the whiteness of 130 CIE. This conclusion is valid for whiteness measured before the size press. Further studies are needed to validate this conclusion considering the finished product.展开更多
Tropical mountain peatlands in Brazil’s Southern Espinhaço Range are vital ecosystems,acting as carbon reservoirs,hydrological buffers,and biodiversity hotspots while sustaining traditional livelihoods and prese...Tropical mountain peatlands in Brazil’s Southern Espinhaço Range are vital ecosystems,acting as carbon reservoirs,hydrological buffers,and biodiversity hotspots while sustaining traditional livelihoods and preserving paleoenvironmental records.Despite their importance,peatlands outside protected areas face degradation by grazing and fires,threatening their ability to regulate ecosystem processes sensitive to temperature,such as greenhouse gas emissions,water cycling,biological activity,and organic matter decomposition.Since 2016,we have monitored peat temperatures in two contrasting peatlands–one preserved(within a protected area)and one disturbed(outside the protected area)–to understand how anthropogenic disturbances and climate variability impact these fragile ecosystems.Seasonal patterns dominated temperature variation,accounting for 60% of air and 81%–92% of peatland temperature variation.However,average temperatures and amplitudes differed between peatlands and depths.Interannual variability revealed stronger trends in the disturbed peatland,where a 1℃ increase in air temperature caused the trend to increase 0.70℃–0.87℃ on average at depths of 0.85 m–0.92 m.By contrast,the preserved peatland showed smaller increases(0.20℃–0.24℃)at comparable depths(1.06 m–1.24 m),suggesting a greater resilience.Temperature variation in the monitored peatlands was majorly driven by seasonal patterns,as revealed by time series decomposition and sinewave fit.Average temperature and amplitude varied between the two peatlands and among sampling sites,reflecting differences in environmental conditions and measurement depth.Interannual variability also exhibited distinct effects between peatlands and monitoring sites.The time series trend component showed more pronounced fluctuations at shallower depths and in the disturbed peatland.For every 1℃ increase in the trend component of the air temperature,the trend component of the peatland time series increased by 0.70℃ and 0.87℃on average at depths of 0.85 m and 0.92 m,respectively,in the disturbed peatland.In contrast,the preserved peatland exhibited smaller increases of 0.20℃ and 0.24℃ at comparable depths(1.06 m and 1.24 m).These findings highlight the potential for feedback responses between peatland disturbance and climate change,threatening their critical role in regulating carbon and water cycles.Expanding long-term monitoring,strengthening conservation efforts,and raising public awareness are essential to safeguard the ecosystem services provided by tropical mountain peatlands.展开更多
The little layer of tree plantations provides primary nutrients for uptake,buff ers changes in soil moisture,and provides habitat and substrate to soil epigeic fauna.However,this layer in eucalypt plantations is often...The little layer of tree plantations provides primary nutrients for uptake,buff ers changes in soil moisture,and provides habitat and substrate to soil epigeic fauna.However,this layer in eucalypt plantations is often removed to reduce fuel load during the fi re season in the Brazilian savanna(Cerrado).Therefore,it is necessary to quantify the eff ects of changes in litter dynamics on the function of these plantations,on key nutrient cycling processes and on epigeic fauna diversity and abundance.In two adjacent stands(one juvenile and one mature),the consequences of two years of litter removal were quantifi ed as monthly litterfall,leaf and fi ne wood litter decomposition,epigeic fauna abundance and diversity,soil biogeochemical variables,and tree diameter and basal area increments.Monthly litterfall rates in juvenile and mature stands did not change with litter removal over the study period.Annual litterfall ranged from 4.1 to 4.9 Mg ha^(−1)a^(−1)in litter removal plots and from 3.9 to 4.8 Mg ha^(−1)a^(−1)in control plots.Fine wood litter decomposition was slower in litter removal plots compared to controls,while leaf decomposition rates were similar in both.Two years of litter removal in the juvenile stand did not aff ect topsoil biogeochemical parameters but decreased available phosphorus at 20–40 cm depth relative to controls.In the mature stand,total cation exchange capacity(0–20 cm)was higher in controls(6.4 cmol c dm^(−3))relative to litter removal plots(6.3 cmol c dm^(−3)),while soil moisture(0–40 cm depth)was lower in litter removal(25.45 m 3 m^(−3))compared to control plots(26 m^(3)m^(−3))in the dry season.A non-metric multidimensional scaling ordination revealed an increased homogeneity in epigeic fauna where litter was removed.Litterfall,decomposition,diameter increment,four soil physical parameters and fourteen chemical parameters at 0–20 and 20–40 cm depth explained the diff erences in soil epigeic fauna composition between litter removal and control plots.Diameter increment decreased with litter removal only in the juvenile stand,which had reached its growth peak.The results indicate that removing excess litter to decrease fuel volume can alter soil biodiversity and edaphic conditions that negatively aff ect nutrient cycling and tree growth.展开更多
This article presents the first applied results of using citric acid in combinations with a melamine-urea-formal-dehyde(MUF)resin for bonding wood veneers.The chemical reactions involved are shown based on a MALDI ToF...This article presents the first applied results of using citric acid in combinations with a melamine-urea-formal-dehyde(MUF)resin for bonding wood veneers.The chemical reactions involved are shown based on a MALDI ToF analysis of the reaction of the MUF resin with citric acid.The preliminary results of the physical and mechanical properties of the LVL prepared are also presented.Veneers from Populus sp were used to manufacture 5-layer laminated veneer lumber(LVL)of small dimensions.Five combinations of the amount of citric acid,MUF spread rate and pressing parameters were tested.LVL bonded with 20%of citric acid+100 g/m^(2)of MUF,hot-pressed using a 3-step process with maximum 1.5 MPa of pressure yielded the board with better dimensional stability and mechanical properties.It could be concluded that citric acid in combination with MUF can be used for bonding wood veneer and the research should be continued to study further the parameters involved and to enhance the results.展开更多
Background: Tropical forests play a fundamental role in the provision of diverse ecosystem services, such as biodiversity,climate and air quality regulation, freshwater provision, carbon cycling, agricultural support ...Background: Tropical forests play a fundamental role in the provision of diverse ecosystem services, such as biodiversity,climate and air quality regulation, freshwater provision, carbon cycling, agricultural support and culture. To understand the role of forests in the carbon balance, aboveground biomass(AGB) estimates are needed. Given the importance of Brazilian tropical forests, there is an urgent need to improve AGB estimates to support the Brazilian commitments under the United Nations Framework Convention on Climate Change(UNFCCC). Many AGB maps and datasets exist, varying in availability, scale and coverage. Thus, stakeholders, policy makers and scientists must decide which AGB product, dataset or combination of data to use for their particular goals. In this study, we assessed the gaps in the spatial AGB data across the Brazilian Amazon forests not only to orient the decision makers about the data that are currently available but also to provide a guide for future initiatives.Results: We obtained a map of the gaps in the forest AGB spatial data for the Brazilian Amazon using statistics and differences between AGB maps and a spatial multicriteria evaluation that considered the current AGB datasets. The AGB spatial data gap map represents areas with good coverage of AGB data and, consequently, the main gaps or priority areas where further biomass assessments should focus, including the northeast of Amazon State, Amapá and northeast of Pará. Additional y, by quantifying the variability in both the AGB maps and field data on multiple environmental factors,we provide valuable elements for understanding the current AGB data as a function of climate, soil, vegetation and geomorphology.Conclusions: The map of AGB data gaps could become a useful tool for policy makers and different stakeholders working on National Communications, Reducing Emissions from Deforestation and Degradation(REDD+), or carbon emissions modeling to prioritize places to implement further AGB assessments. Only 0.2% of the Amazon biome forest is sampled, and extensive effort is necessary to improve what we know about the tropical forest.展开更多
Biorefinery is a new term to designate two main subjects, bioproducts and bioenergy, which play important roles towards a more bio-based society. This paper reviews the current biorefineries model as well as its futur...Biorefinery is a new term to designate two main subjects, bioproducts and bioenergy, which play important roles towards a more bio-based society. This paper reviews the current biorefineries model as well as its future importance focusing on pulp mill opportunities. There are currently several different levels of integration in biorefineries which add to their sustainability, both economically and environmentally. Enzymatic pretreatment for biomass deconstruction aiming to release the polysaccharides is a key technology in the future biorefineries and it is currently the subject of intensive research.展开更多
As the largest jujube cultivating areas of the world,the market price and quality of Chinese jujube are obviously affected by its producing regions in China.Therefore,traceability of Chinese jujube has become an impor...As the largest jujube cultivating areas of the world,the market price and quality of Chinese jujube are obviously affected by its producing regions in China.Therefore,traceability of Chinese jujube has become an important issue.To search the suitable geographical labels of Chinese jujube,26 major cultivars from five geographical regions of China were investigated by evaluating their bioactive compounds and antioxidant activity profiling.Multivariate statistical techniques(e,g.,PCA,PLS,VIP value)applied to the above-obtained data were further used to identify geographical origin in different areas of Chinese jujube.The results indicated that the highest median contents of total phenols(TP)and flavonoids(TF)of Chinese jujube were originated from Ningxia and Henan provinces,both of which also exhibited the stronger bioactivity.p-Hydroxybenzoic acid and rutin exhibited the highest contents among the all detected individual phenolic compounds.The highest median contents of cyclic adenosine monophosphate(cAMP),cyclic guanosine monophosphate(cGMP)and polysaccharides were all found in Chinese jujube samples of Xinjiang province.In particular,p-hydroxybenzoic acid,rutin,cAMP,cGMP and polysaccharides can be regarded as the potential biomarkers in distinguishing the geographical origin of Chinese jujube.Additionally,the high altitude and latitude might be benefit for the accumulation of cAMP,cGMP and polysaccharides(primary metabolites),and high longitude and annual precipitation maybe improve the contents of TP and TF(secondary metabolites).These information could provide an effective methods in distinguishing the geographical features of Chinese jujube,and also be benefit for the products development.展开更多
文摘Two new tetralone derivatives named xylariol A （1） and B （2） were isolated from the EtOAc extract of the culture broth of Xylaria hypoxylon AT-028 （Xylariaceae）, and their structures were elucidated by MS, 1R, 1D- and 2D-NMR spectra, and by X-ray diffraction analysis. 1 and 2 showed moderate cytotoxic activities against Hep G2 cells in the in vitro cytotoxic assay with IC50 values of 22.3 and 21.2 μg/mL, respectively.
基金funded by the Comision Sectorial de Investigacion Cientifica(CSIC)[ID-501]the Agencia Nacional de Investigacion e Innovacion(ANII)[POS_EXT_2023_1_174913]。
文摘Savannas constitute a mixture of trees and shrub patches with a more continuous herbaceous understory.The contribution of this biome to the soil organic carbon(SOC)and above-ground biomass(AGB)carbon(C)stock globally is significant.However,they are frequently subjected to land use changes,promoting increases in CO_(2) emissions.In Uruguay,subtropical wooded savannas cover around 100,000 ha,of which approximately 28%is circumscribed to sodic soils(i.e.,subtropical halophytic wooded savannas).Nevertheless,there is little background about the contribution of each ecosystem component to the C stock as well as site-specific allometric equations.The study was conducted in 5 ha of subtropical halophytic wooded savannas of the national protected area Esteros y Algarrobales del Rio Uruguay.This work aimed to estimate the contribution of the main ecosystem components(e.g.,soil,trees,shrubs,and herbaceous plants)to the C stock.Site-specific allometric equations for the most frequent tree species and shrub genus were fitted based on basal diameter(BD)and total height(H).The fitted equations accounted for between 77%and 98%of the aerial biomass variance of Netuma affinis and Vachellia caven.For shrubs(Baccharis sp.),the adjusted equation accounted for 86%of total aerial biomass.C stock for the entire system was 116.71±11.07 Mg·ha^(-1),of which 90.7%was allocated in the soil,8.3%in the trees,0.8%in the herbaceous plants,and 0.2%in the shrubs.These results highlight the importance of subtropical halophytic wooded savannas as C sinks and their relevance in the mitigation of global warming under a climate change scenario.
基金This study was a part of the doctoral dissertation and supported by Suleyman Demirel University Projects(Project numbers:OYP-05241-DR14 and 4167-OYP-D2-14).
文摘We investigated the effects of precommercial thinning(PCT)applied at different levels on the growth parameters of natural Anatolian black pine stand.The experimental site was located in the province of Isparta in southern Turkey.PCT was set up using a randomized complete block design with three replicates and three treatments(control,2–2.5 m×–2.5 m and 3–3.5 m×–3.5 m spacing).The experimental plots were established in March 2014.At the end of the growing seasons for three years(2014–2016),growth parameters such as diameter,height and crown radius were measured.PCT was found to be significantly effective on diameter,height,individual tree basal area,and crown radius increment at the end of the third year(p<0.05).While diameter,individual tree basal area and crown radius increment increased with increasing PCT intensity,height increment was higher in control than PCT.Although the PCT treatments applied with 3–3.5 m spacing affected individual tree development positively,we need long-term results on wood quality and yield.According to the short-term results,it is thought that it is better to lower the stand closeness gradually,so,it may be advisable to apply PCT by 2–2.5 m×–2.5 m spacing.
文摘Changes in forest diversity and the transforma- tion of coniferous plantations into more natural woodlands are of special interest in the Medi- terranean. The aim of this study was to investi- gate changes in land use patterns and vegeta- tion cover from 1956 to 1999 in Pinus halepensis Miller plantations in Montes de Málaga State Park in southern Spain. At the landscape level, a FRAGSTAT analysis was performed using aerial photographs. At the community level, a total of 47 sample plots were analyzed. Field measure- ments indicated the presence of a total of 70 species in the different vegetation types sam- pled. Shannon-Wiener (H), and Simpson’s (D) diversity indices showed the greatest species richness in Aleppo pine plantations (H = 1.54 ± 0.2;D = 3.88 ± 0.6), while Holm oak stands in the forested areas (H = 1.37 ± 0.1;D = 3.35 ± 0.6) and agricultural land (H = 1.33 ± 0.01;D = 2.80 ± 0.03) had lower values. FRAGSTATS analyses at land- scape and community levels indicated increases in patch richness, patch number, and percent of landscape mainly for pine plantations, Holm oak forests and shrub habitats. Replacement of agri- culture by conifer plantations led to the homo- genization of landscape structure. This change has modified the landscape by facilitating the recovery of indigenous tree species including Holm oak, which will likely lead to the future establishment of native forests in this area. Our findings suggest that pine plantations could fa- vour woody species diversity by increasing abundance and species richness in contrast to the situation in non-forested agricultural land.
文摘The relationships between climate conditions and wood density in tropical forests are still poorly understood.To quantify spatial dependence of wood density in the state of Minas Gerais(MG,Brazil),map spatial distribution of density,and correlate density with climate variables,we extracted data from the Forest Inventory of Minas Gerais for 1988 trees scaled throughout the territory and measured wood density of discs removed from the trees.Environmental variables were extracted from the database of the Ecological-Economic Zoning of Minas Gerais.For spatial analysis,tree densities were measured at 44 georeferenced sampling points.The data were subjected to exploratory analysis,variography,cross-validation,model selection,and ordinary kriging.The relationships between wood density and environmental variables were calculated using dispersion matrices,linear correlation,and regression.Wood density proved to be highly spatially dependent,reaching a correlation of 96%,and was highly continuous over a distance of 228 km.The distribution of wood density followed a continuous gradient of 514-659 kg m^(−3),enabling corre-lation with environment variables.Density was correlated with mean annual precipitation(−0.57),temperature(0.63),and evapotranspiration(0.83).Geostatistical methods proved useful in predicting wood density in native tropical forests with different climate conditions.Our results confirmed the sensitivity of wood density to climate change,which could affect future carbon stock in forests.
基金supported by the University of Brasilia and the National Council for Scientific and Technological Development(CNPq)。
文摘The objective of this work was to compare estimates generated by a diametric distribution model and a total stand model against the pre-cut inventory.The model efficiency was also evaluated.Data were evaluated from 30 permanent sample plots in a Eucalyptus urophylla stand,comprising 24 sample plots used for model fitting,and six sample plots for validation.The volume of wood per hectare was estimated for different productive units(sites),using 7 years as the reference age.The model adjustment quality was verified by adjustment and precision statistics:the correlation between observed and predicted variables,root mean square error percentage,graphical analysis of residual distribution,and a frequency histogram for classes of relative errors and validation.Although the two-parameter Weibull probability density function adhered to the data for tree evolution in diameter classes for the reference age(7 years)in the different productivity classes,it generated imprecise estimates of the number of individuals.Consequently,it produced inaccurate volumetric production estimates.The total stand model provided reliable projections of production volumes in different productivity classes for both adjustment types,showing compatibility with the pre-cut inventory according to a Tukey test.In summary,the total stand model generated estimates that were compatible with the pre-cut inventory while the diametric distribution model did not.
基金the Wood Science and Technology Laboratory of the Federal University of Lavras,Brazil for supporting this research。
文摘This research assessed the relationship between wood physical-anatomical variables and charcoal physical-mechanical properties.Nine trees were harvested and mechanically processed into standard pieces for laboratory analysis.The following variables were determined:wood density,fiber length and width,fiber lumen diameter and wall thickness,fiber wall fraction,and vessel frequency.The charcoal was produced in a laboratory and gravimetric yield,relative density,and mechanical properties established.Pearson’s correlation coefficients,multivariate statistical analysis of canonical correlation,and principal component analysis were used to evaluate the relationship between wood and charcoal properties.Fiber width was not significantly correlated with charcoal properties.Charcoal bulk density,hardness,and strength were positively correlated with wood density,fiber length,wall thickness,and wall fraction.Charcoal properties were negatively correlated with fiber lumen diameter and vessel frequency.These results will help identify the best wood with adequate physical-mechanical properties for industrial charcoal proces sing.
文摘In North Africa, Cedrus atlantica forests are in decline, following decades of anthropogenic pressure and repeated drought events. Mixed C. atlantica-Quercus ilex stands located in the Theniet El Had National Park (northwestern Algeria) were considered in the present study. Based on a stratified sampling, six temporary plots were established to describe structure (species composition, density, total height, diameter and basal area) and radial growth in relation to type of stand (pure and mixed), using a dendroecological approach. The diameter distribution of C. atlantica indicated the presence of few young individuals and a poor regeneration status in all the stands. The density and basal area of C. atlantica were significantly higher in pure stands, which necessitate silvicultural operations. In contrast, Q. ilex showed a progressive dynamic, at moderate altitude. Radial growth showed a significant decline from 1980 to the 2000s. The absence of an appropriate management plan and the increase in anthropogenic effects, without ruling out a role for the current climate conditions marked by drought, seem to be the causes of C. atlantica decline.
基金Funding provided by the Minas Gerais State Research Foundation(FAPEMIG)from the Brazilian National Council for Science and Technology Development(CNPq)is greatly appreciated.
文摘In integrated factories of pulp and paper, the bleaching control is made by kappa number and/or brightness. However, the product paper is evaluated and valued for its whiteness. The level of final brightness of pulp certainly affects the demand for optical brighteners in paper manufacturing, nevertheless, there is not a direct correlation between consumption of optical brightener and final brightness, being the method of bleaching pulp, especially from the final stage of bleaching, also important in relation to this demand. Therefore, this study aimed to evaluate the potential of using the parameter whiteness as a tool to control bleaching pulp, instead of the traditional brightness and evaluate the impacts of different methods of bleaching and the pulp final brightness level in action of optical brighteners, to improve their performance. It was observed that the whiteness and brightness of the pulp are highly correlated and that the control of the bleaching plant can be done by any one of these two parameters. It was also concluded that, considering current prices of bleaching reagents and of optical brighteners, it is better to bleach the pulp up to lower brightness values (e.g. 88% ISO) and use larger amounts of optical brighteners to brighten the mass until the whiteness of 130 CIE. This conclusion is valid for whiteness measured before the size press. Further studies are needed to validate this conclusion considering the finished product.
基金This study was financed in part by the Coordenacao de Aperfeiçoamento de Pessoal de Nivel Superior-Brasil(CAPES)-Finance Code 001the Brazilian Conselho Nacional de Pesquisa-CNPq(study and research grants and research funding-Process 303666/2018-8,408162/2018-0,441335/2020-9,302969/2021-7,and 50484/2022-4)Fundacao de ApoioaPesquisa do Estado de Minas Gerais-FAPEMIG(study grants and research funding-Process CRA/APQ 0100-18,APQ-03364-21 and CAG/PPM 00568-16).
文摘Tropical mountain peatlands in Brazil’s Southern Espinhaço Range are vital ecosystems,acting as carbon reservoirs,hydrological buffers,and biodiversity hotspots while sustaining traditional livelihoods and preserving paleoenvironmental records.Despite their importance,peatlands outside protected areas face degradation by grazing and fires,threatening their ability to regulate ecosystem processes sensitive to temperature,such as greenhouse gas emissions,water cycling,biological activity,and organic matter decomposition.Since 2016,we have monitored peat temperatures in two contrasting peatlands–one preserved(within a protected area)and one disturbed(outside the protected area)–to understand how anthropogenic disturbances and climate variability impact these fragile ecosystems.Seasonal patterns dominated temperature variation,accounting for 60% of air and 81%–92% of peatland temperature variation.However,average temperatures and amplitudes differed between peatlands and depths.Interannual variability revealed stronger trends in the disturbed peatland,where a 1℃ increase in air temperature caused the trend to increase 0.70℃–0.87℃ on average at depths of 0.85 m–0.92 m.By contrast,the preserved peatland showed smaller increases(0.20℃–0.24℃)at comparable depths(1.06 m–1.24 m),suggesting a greater resilience.Temperature variation in the monitored peatlands was majorly driven by seasonal patterns,as revealed by time series decomposition and sinewave fit.Average temperature and amplitude varied between the two peatlands and among sampling sites,reflecting differences in environmental conditions and measurement depth.Interannual variability also exhibited distinct effects between peatlands and monitoring sites.The time series trend component showed more pronounced fluctuations at shallower depths and in the disturbed peatland.For every 1℃ increase in the trend component of the air temperature,the trend component of the peatland time series increased by 0.70℃ and 0.87℃on average at depths of 0.85 m and 0.92 m,respectively,in the disturbed peatland.In contrast,the preserved peatland exhibited smaller increases of 0.20℃ and 0.24℃ at comparable depths(1.06 m and 1.24 m).These findings highlight the potential for feedback responses between peatland disturbance and climate change,threatening their critical role in regulating carbon and water cycles.Expanding long-term monitoring,strengthening conservation efforts,and raising public awareness are essential to safeguard the ecosystem services provided by tropical mountain peatlands.
基金supported by the Coordination for the Improvement of Higher Education Personnel(CAPES)the research funding of the University of Brasília。
文摘The little layer of tree plantations provides primary nutrients for uptake,buff ers changes in soil moisture,and provides habitat and substrate to soil epigeic fauna.However,this layer in eucalypt plantations is often removed to reduce fuel load during the fi re season in the Brazilian savanna(Cerrado).Therefore,it is necessary to quantify the eff ects of changes in litter dynamics on the function of these plantations,on key nutrient cycling processes and on epigeic fauna diversity and abundance.In two adjacent stands(one juvenile and one mature),the consequences of two years of litter removal were quantifi ed as monthly litterfall,leaf and fi ne wood litter decomposition,epigeic fauna abundance and diversity,soil biogeochemical variables,and tree diameter and basal area increments.Monthly litterfall rates in juvenile and mature stands did not change with litter removal over the study period.Annual litterfall ranged from 4.1 to 4.9 Mg ha^(−1)a^(−1)in litter removal plots and from 3.9 to 4.8 Mg ha^(−1)a^(−1)in control plots.Fine wood litter decomposition was slower in litter removal plots compared to controls,while leaf decomposition rates were similar in both.Two years of litter removal in the juvenile stand did not aff ect topsoil biogeochemical parameters but decreased available phosphorus at 20–40 cm depth relative to controls.In the mature stand,total cation exchange capacity(0–20 cm)was higher in controls(6.4 cmol c dm^(−3))relative to litter removal plots(6.3 cmol c dm^(−3)),while soil moisture(0–40 cm depth)was lower in litter removal(25.45 m 3 m^(−3))compared to control plots(26 m^(3)m^(−3))in the dry season.A non-metric multidimensional scaling ordination revealed an increased homogeneity in epigeic fauna where litter was removed.Litterfall,decomposition,diameter increment,four soil physical parameters and fourteen chemical parameters at 0–20 and 20–40 cm depth explained the diff erences in soil epigeic fauna composition between litter removal and control plots.Diameter increment decreased with litter removal only in the juvenile stand,which had reached its growth peak.The results indicate that removing excess litter to decrease fuel volume can alter soil biodiversity and edaphic conditions that negatively aff ect nutrient cycling and tree growth.
基金financed under the scheme of Laboratory of Excellence ARBRE by the French Agence Nationale de la Recherche(ANR).
文摘This article presents the first applied results of using citric acid in combinations with a melamine-urea-formal-dehyde(MUF)resin for bonding wood veneers.The chemical reactions involved are shown based on a MALDI ToF analysis of the reaction of the MUF resin with citric acid.The preliminary results of the physical and mechanical properties of the LVL prepared are also presented.Veneers from Populus sp were used to manufacture 5-layer laminated veneer lumber(LVL)of small dimensions.Five combinations of the amount of citric acid,MUF spread rate and pressing parameters were tested.LVL bonded with 20%of citric acid+100 g/m^(2)of MUF,hot-pressed using a 3-step process with maximum 1.5 MPa of pressure yielded the board with better dimensional stability and mechanical properties.It could be concluded that citric acid in combination with MUF can be used for bonding wood veneer and the research should be continued to study further the parameters involved and to enhance the results.
基金part of the Sao Paulo Research Foundation (FAPESP) Grant No.2013/20616–6 and 2018/18493–7the project LiDAR Remote Sensing of Brazilian Amazon Forests:Analysis of Forest Biomass,Forest Degradation,and Secondary Regrowth funded by the USAID Prime Award Number AID-OAA-A-11-00012。
文摘Background: Tropical forests play a fundamental role in the provision of diverse ecosystem services, such as biodiversity,climate and air quality regulation, freshwater provision, carbon cycling, agricultural support and culture. To understand the role of forests in the carbon balance, aboveground biomass(AGB) estimates are needed. Given the importance of Brazilian tropical forests, there is an urgent need to improve AGB estimates to support the Brazilian commitments under the United Nations Framework Convention on Climate Change(UNFCCC). Many AGB maps and datasets exist, varying in availability, scale and coverage. Thus, stakeholders, policy makers and scientists must decide which AGB product, dataset or combination of data to use for their particular goals. In this study, we assessed the gaps in the spatial AGB data across the Brazilian Amazon forests not only to orient the decision makers about the data that are currently available but also to provide a guide for future initiatives.Results: We obtained a map of the gaps in the forest AGB spatial data for the Brazilian Amazon using statistics and differences between AGB maps and a spatial multicriteria evaluation that considered the current AGB datasets. The AGB spatial data gap map represents areas with good coverage of AGB data and, consequently, the main gaps or priority areas where further biomass assessments should focus, including the northeast of Amazon State, Amapá and northeast of Pará. Additional y, by quantifying the variability in both the AGB maps and field data on multiple environmental factors,we provide valuable elements for understanding the current AGB data as a function of climate, soil, vegetation and geomorphology.Conclusions: The map of AGB data gaps could become a useful tool for policy makers and different stakeholders working on National Communications, Reducing Emissions from Deforestation and Degradation(REDD+), or carbon emissions modeling to prioritize places to implement further AGB assessments. Only 0.2% of the Amazon biome forest is sampled, and extensive effort is necessary to improve what we know about the tropical forest.
基金Funding provided by the European Community’s Seventh Framework Programme FP7/2007-2013 under grant agreement no KBBE-2009-3-244362 LignoDeco,from the Minas Gerais State Research Foundation(FAPEMIG)
文摘Biorefinery is a new term to designate two main subjects, bioproducts and bioenergy, which play important roles towards a more bio-based society. This paper reviews the current biorefineries model as well as its future importance focusing on pulp mill opportunities. There are currently several different levels of integration in biorefineries which add to their sustainability, both economically and environmentally. Enzymatic pretreatment for biomass deconstruction aiming to release the polysaccharides is a key technology in the future biorefineries and it is currently the subject of intensive research.
基金This work was supported by the Key Development Projects in Shaanxi Province(2018ZDXM-NY-082)Key projects to promote scientific and technological achievements by Northwest A&F University(XTG 2018-35).
文摘As the largest jujube cultivating areas of the world,the market price and quality of Chinese jujube are obviously affected by its producing regions in China.Therefore,traceability of Chinese jujube has become an important issue.To search the suitable geographical labels of Chinese jujube,26 major cultivars from five geographical regions of China were investigated by evaluating their bioactive compounds and antioxidant activity profiling.Multivariate statistical techniques(e,g.,PCA,PLS,VIP value)applied to the above-obtained data were further used to identify geographical origin in different areas of Chinese jujube.The results indicated that the highest median contents of total phenols(TP)and flavonoids(TF)of Chinese jujube were originated from Ningxia and Henan provinces,both of which also exhibited the stronger bioactivity.p-Hydroxybenzoic acid and rutin exhibited the highest contents among the all detected individual phenolic compounds.The highest median contents of cyclic adenosine monophosphate(cAMP),cyclic guanosine monophosphate(cGMP)and polysaccharides were all found in Chinese jujube samples of Xinjiang province.In particular,p-hydroxybenzoic acid,rutin,cAMP,cGMP and polysaccharides can be regarded as the potential biomarkers in distinguishing the geographical origin of Chinese jujube.Additionally,the high altitude and latitude might be benefit for the accumulation of cAMP,cGMP and polysaccharides(primary metabolites),and high longitude and annual precipitation maybe improve the contents of TP and TF(secondary metabolites).These information could provide an effective methods in distinguishing the geographical features of Chinese jujube,and also be benefit for the products development.
