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Background: Understanding the drivers of variations in carbon stocks is essential for developing the effective management strategies that contribute to mitigating climate change. Although a positive relationship between biodiversity and the aboveground carbon (AGC) has been widely reported for various Brazilian forest types, representing a win–win scenario for climate change mitigation, this association has not been commonly found in Brazilian subtropical forests. Therefore, in the present study, we aimed to evaluate the effects of Araucaria angustifolia, stand structure and species diversity in shaping AGC stocks in Brazilian subtropical mixed forest. We hypothesized that the effects on the AGC of stand structure and diversity would be mediated by A. angustifolia. We also evaluated the expectation of higher carbon stocks in protected forest as a result of their positive correlation with biodiversity conservation. Results: We found that stand structure, followed by A. angustifolia, played the most important role in shaping the AGC stock. Our hypothesis was partially confirmed, the indirect effects of A. angustifolia on stand structure being found to have shaped the AGC. Similarly, our expectation was partially supported, with the higher AGC in the protected area being related not to diversity, but rather to the presence of larger trees, denser stands, and a greater abundance of A. angustifolia. Conclusion: Although the win–win strategy between diversity conservation and carbon storage is not a peculiarity of Araucaria forests, we highlight the potential of these forests as a nature-based climate solution, maintaining high levels of carbon storage in harmony with the provision of keystone socio-economic resources. [ABSTRACT FROM AUTHOR]

Tree height is one of the most important variables for quantitative assessment of forest stocks, but it is difficult to directly measure. Such allometric relationships of trees can vary between geographical regions, however, mainly due to climatic, edaphic, and floristic gradients. Based on the hypothesis that different forest types influence the generic modeling of tree height–diameter relationships on geographical scales, this study aimed to (i) fit equations to estimate tree height in Atlantic Forest types in the state of Rio de Janeiro, Brazil; (ii) compare efficiency and precision between generic and specific equations for forest types; and (iii) test the effect of different forest types and species on the height–diameter relationship. Four allometric models were tested for all forests (generic) and three main forest types (specific). Effects of tree size, forest types, and species on tree height estimation were analyzed using multiple linear models and mixed-effect linear models. A significant effect of forest type and species on tree height was seen, showing the need to apply local specific equations to minimize the effects that are not captured by generic equations. Differences in tree allometry between forest types were associated with temperature, rainfall, soil, and forest structure. These results confirm the effect of the local environment on the height–diameter relationship of trees as found over large scales in tropical forests. [ABSTRACT FROM AUTHOR]

Considering the hypothesis that geostatistics provides improvement for understanding the spatial variability of natural forest formations and their soil characteristics, the aim of this study was to evaluate the spatial relationship between the soil chemical and granulometric attributes regarding the number of trees and the basal area of a Mixed Ombrophilous Forest remnant. The survey of soil attributes and vegetation was carried out in 200 units of 25 x 25 m georeferenced sampling units. Then, geostatistics was used to model the spatial continuity, and punctual ordinary kriging was employed to produce thematic maps. The results obtained confirmed that the spatial continuity of soil attributes, number of trees and basal area can be modelled, whreas non-spatial similarity was observed in the kriging maps. However, it was evident that among the soil variables considered, pH is the one with the greatest spatial relationship with the forest variables. [ABSTRACT FROM AUTHOR]

A lack of ecological knowledge leads to innovative tools for investigating spatial relationships in natural forests, among which geostatistics stands out as a set of statistical techniques for modeling and mapping. Thus, this paper aims to apply geostatistical analysis to map and correlate the spatial patterns and dynamics of the basal area for successional tree species groups in a Mixed Tropical Forest remnant in the southern part of Brazil. The floristic composition was obtained through continuous inventory conducted in 400 plots, where the basal area was evaluated for total stock and ecological groups: pioneer, early secondary, late secondary and climax. Subsequently, geostatistical analysis was used for modeling the spatial patterns of the basal area, and ordinary kriging interpolation was applied to compose thematic maps. The results show that the forest structure presents spatial dependence and heterogeneous distribution, in which the spatial behavior of successional tree groups is associated with species aggregation patterns. Moreover, spatial dynamics are influenced by basal area increment, in which spatial changes indicate a natural forest in an advanced secondary successional stage, reflecting a favorable conservation status. This shows the importance of Conservation Units policies as preservation strategies and biodiversity sources for forest restoration. [ABSTRACT FROM AUTHOR]

The objective of this work was to adjust traditional models of hypsometric relations for homogeneous candeia stands, under different initial spacing. Ten models were adjusted for hypsometric relations. The assessment criteria obeyed the highest determination coefficient and the lowest standard error of estimate in percentage. The F test was also evaluated, as well as the significance of the regression coefficients, the graphical analysis of the residues and the identity test when the same model was selected for different treatments. It was observed that, over time, the hypsometric curves reduce their tilt, move to the right and elevate, reducing the interval among them from the sixth year. The traditional hypsometric relation models as Henricksen, Stofells, Assman, Trorey and Curtis are efficient to estimate the total height of candeia in homogeneous stands and under different initial spacing in Minas Gerais State, Brazil. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the spatial correlations of soil chemical attributes with the development of teak (Tectona grandis) in the city of Nossa Senhora do Livramento, Mato Grosso State, Brazil. It was allocated 46 permanent plots of 15 m x 30 m. From the stand it was obtained the mean annual values of diameter at 1.3 m above the ground and total height of second to ninth years of age. Soil samples from 0 to 0.20 m depth were also obtained at the second year, to determine pH, calcium, magnesium and aluminum, phosphorus and potassium for subsequent modeling of spatial patterns by geostatistics. The diameter at 1.3 m and the total height of teak present higher spatial correlation with the chemical soil attributes pH and calcium, low spatial similarity with potassium and magnesium, absence for phosphorus and inverse relationship with aluminum. [ABSTRACT FROM AUTHOR]

This study aimed to adjust volumetric models to tropical pines, in pure stand, in the municipality of Vilhena, Rondonia State. The data came from 20 felled trees of Pinus caribaea var. hondurensis and 10 Pinus tecunumanii trees with discs collected at fixed positions of 0.20 m, 0.70 m, 1.30 m and in distances of one meter along the stem, for later counting and measurement of the growth rings at ages from 4 to 12 years. Eight volumetric models were adjusted. The selection criteria used were: standard error of estimate, adjusted coefficient of determination, F test, significance of regression coefficients, mean deviation, standard deviation of the differences, sum of square of the relative residual, percentage of the residuals and graphic analysis of residuals. The models from Näslund modified and from Spurr presented, respectively, best fit to estimate the volume for Pinus caribaea var. hondurensis submitted to the first thinning and for Pinus tecunumanii, with ages between 4 and 12 years, in Vilhena, Rondonia State, Brazil. [ABSTRACT FROM AUTHOR]

obtaining parameters to assess growth and the potential production of Pinus, the present work aims to adjust traditional models of hypsometric relation to species Pinus caribaea Morrelet var. hondurensis Barret & Golfari and Pinus tecunumanii Eguiluz & Perry, in pure stand, in the municipality of Vilhena, Rondônia State. Ten modal analysis of the residues. The model d/√h = βels were adjusted and the selection criteria followed the lower standard error of estimate (Syx%), higher adjusted coefficient of determination (R2aj.), F value and regression coefficients significant and graphic0 + β1.d + ϵi showed the better fit, with R2aj. of 0,896 and Syx% of 3,941% for P. caribaea var. hondurensis and R2aj. of 0,973 and Syx% of 6,319% for P. tecunumanii. [ABSTRACT FROM AUTHOR]

Biomass and wood volume estimates in forest ecosystems are fundamental to a variety of studies focusing at forest dynamics. These estimates are usually carried out through forest inventory techniques which rely upon statistical computations. This work aims at providing a new methodological approach to forest inventory processing when data is georeferenced. Specifically, geostatistical modelling is performed through ordinary cokriging using tree basal area and tree richness as a cofactor in an Amazonian rainforest site. The spatial interpolation provided the tools for the creation of two disjoint forest strata, which are processed following the principles of Stratified Forest Inventory. The spatially stratified forest inventory processing has shown a 14.29% decrease in error as directly compared to simple random sampling processing. Only two strata have been used following spatial interpolation, albeit it is argued that theoretically any number of them could be generated. The procedure is methodologically feasible and offers a framework to future research on its development and reach. Particularly, the geometries of forest strata and the behavior of spatial interpolation along a gradient of forest vertical structures are of potential interest in future work. [ABSTRACT FROM AUTHOR]

Lauraceae family has one of the highest values of importance in the Mixed Ombrophilous Forest (MOF). The commercial value of some of its species was a reason for intense forest exploitation in the southern region of Brazil. Considering the hypothesis that it provides an essential subsidy for the constitution of this forest type, the aim of this study was to identify and quantify the influence of Lauraceae family in the dynamics of a 15.2 ha MOF remnant. Census data were collected every three years, since 2007, in which all trees with a circumference at 1.3 m height equal to or greater than 30 cm were identified and measured. Dynamics were analyzed by periodic increment in diameter, recruitment, and mortality through the measurement periods, while cluster multivariate analysis and canonical correlation were applied for grouping species and assessing their importance on the forest remnant dynamics. Diameter distribution prognosis of Lauraceae and its species was obtained through a transition matrix. Eleven tree species of Lauraceae family were identified, which showed decreasing diameter distribution and value of importance equals to 9.51%. Using cluster analysis, five groups were obtained, while the canonical correlation of 0.551 was considered moderate and statistically significant by Wilks' Lambda test. By the projection of diameter distribution, it was verified that the study community is stable and self-regenerative. Although it is considered moderate, the influence of family on the forest remnant tends to increase with the advance of ecological succession. [ABSTRACT FROM AUTHOR]

This study aimed to evaluated two optimized planning strategies and analyze their performance in timber production. Data were obtained in Pinus spp. stands from a forestry company with unbalanced planted area over time. Maximization models of forest production (1) and net present value (2) were formulated and two minimization objective functions of the production deviation (3) and minimum and maximum production oscillation (4) were tested as alternatives to the traditional models. The highest thinning and clearcutting average areas were obtained in strategy 1. Strategies 1 and 2 resulted in the greatest variability of forestry operations. All strategies resulted in the highest timber production for sawn and special sawn wood and the lowest for veneer, while the pulpwood volume was almost constant. Strategies 1 and 2 provided the highest average timber volume and the greatest variability in the production, while strategies 3 and 4 were more efficient, since they supplied the industrial demand with homogeneous production. [ABSTRACT FROM AUTHOR]

The study aims to determine the local productive capacity of teak in Monte Dourado, Pará State, Brazil, with the analysis of site index curves. The data were obtained by stem analysis of ten dominant trees in a stand with 26 years of age. Were adjusted ten regression models and the criterion for selection followed the lowest standard error of estimate, the highest adjusted coefficient of determination, the significance of F test and of regression coefficients and graphical analysis of the residuals. The site index curves were built by the guide-curve method. The Spillman model present the best fit, by which were generated three curves of site index from 16m to 24m, at 26 years of index-age. The region of Monte Dourado - PA showed a productive potential for the development of teak. [ABSTRACT FROM AUTHOR]

Background: We analyzed the dynamics of carbon (C) stocks and CO2 removals by Brazilian forest plantations over the period 1990-2016. Data on the extent of forests compiled from various sources were used in the calculations. Productivities were simulated using species-specific growth and yield simulators for the main trees species planted in the country. Biomass expansion factors, root-to-shoot ratios, wood densities, and carbon fractions compiled from literature were applied. C stocks in necromass (deadwood and litter) and harvested wood products (HWP) were also included in the calculations.Results: Plantation forests stocked 231 Mt C in 1990 increasing to 612 Mt C in 2016 due to an increase in plantation area and higher productivity of the stands during the 26-year period. Eucalyptus contributed 58% of the C stock in 1990 and 71% in 2016 due to a remarkable increase in plantation area and productivity. Pinus reduced its proportion of the carbon storage due to its low growth in area, while the other species shared less than 6% of the C stocks during the period of study. Aboveground biomass, belowground biomass and necromass shared 71, 12, and 5% of the total C stocked in plantations in 2016, respectively. HWP stocked 76 Mt C in the period, which represents 12% of the total C stocked. Carbon dioxide removals by Brazilian forest plantations during the 26-year period totaled 1669 Gt CO2-e.Conclusions: The carbon dioxide removed by Brazilian forest plantations over the 26 years represent almost the totality of the country´s emissions from the waste sector within the same period, or from the agriculture, forestry and other land use sector in 2016. We concluded that forest plantations play an important role in mitigating GHG (greenhouse gases) emissions in Brazil. This study is helpful to improve national reporting on plantation forests and their GHG sequestration potential, and to achieve Brazil’s Nationally Determined Contribution and the Paris Agreement. [ABSTRACT FROM AUTHOR]

Understanding how studies have been carried out in the region helps to understand the Amazon rainforest potential in mitigating climate change. In addition, evaluating scientific production is essential to verify the main methods and places researched. Thus, this study objective was to build an overview and identify the main gaps regarding research related to biomass and carbon stocks with the coverage limit of the Amazon rainforest. Therefore, an analysis of the publications indexed in the Scopus database was developed until 2020, performing a bibliometric analysis and a systematic and state-of-the-art review. Initially 2042 publications were obtained, of which 786 met the inclusion criteria. The first work indexed in the Scopus database related to the theme was published in 1982. Over time, it was possible to observe an increasing behavior in relation to the interest in the theme. Natural environments were the most researched and change in the land use and occupation of the Amazon Rainforest is still poorly evaluated. Brazil is the country with the highest number of studies, followed by Peru and Colombia. Guyana and Suriname appear as possible scientific gaps and potential environments to be studied. Studies preferentially explore the biomass carbon, with the soil being little evaluated when compared to the total amount of papers found. When observing only the biomass studies, the aboveground biomass is the most evaluated, while the roots and necromass are little studied. The main variables used in biomass equations were diameter at 1.3 m above ground and total tree height. The biomass to carbon conversion factor has been widely used, but it can generate unreliable results. It is recommended to carry out local assessments of the carbon content, especially using the dry combustion method, which generates less waste, with more precise results and shorter execution time of the analyses. Such assessments present values for the location that can avoid false or misinterpretations of the biomass and carbon stocks in the Amazon Rainforest. • Amazon rainforest is potential in mitigating climate change. • We assessed papers related to land use and occupation over the Amazon Rainforest. • Our study found that aboveground biomass is the widely studied parameter. • The biomass to carbon conversion factor has been widely used but is unreliable. • Local assessments of the carbon content are expected to generate precise results. [ABSTRACT FROM AUTHOR]

The aim of this work was to adjust, evaluate and select taper functions for estimating diameters along the stem for commercially exploited species in the Amazon Rainforest in Mato Grosso State. The research was conducted in forest management units in areas of the Amazon Rainforest, located in Santa Carmen, Mato Grosso State. To adjust the taper functions, 449 trees were cubed, of the following species: Goupia glabra, Qualea albiflora, Trattinnickia burseraefolia, Erisma uncinatam and Mezilaurus Itauba. The non-segmented models of Schöepfer (1966), Kozak et al. (1969), Hradetzky (1976), and Demaerschalk (1972), adapted for Moura (1994), and segmented model of Max e Burkhart (1976) were fitted. In order to evaluate the accuracy of adjustments we used the determination coefficient, standard error of estimate in percentage and graphical analysis of the waste, weighted value of statistical scores, and auxiliary statistics: standard deviation, standard deviation of differences, sum of squared residuals and relative percent residue. The function of taper Demaerschalk (1972) was the most accurate to estimate the diameter along the stem for forest species of Amazon Matogrossense. Such function allows to describe the shape of the stem as well as the possibility of determining assortments for multiple products of wood. [ABSTRACT FROM AUTHOR]

• Site-effect induce changes on tree allometry along studied environmental gradient. • Soil properties have significant effect on tree height, volume and bark thickness. • Climate significantly influence height-diameter relationship and tree volume. • Bark thickness was not associated with climate across studied environmental gradient. Tree allometric models are generally developed at local scales and thus potentially biased when used for different locations and at broader spatial scales. Because allometric relationships vary with forest structure, climatic conditions and edaphic properties, one potential way to address this issue and consistently estimate tree allometry, may involve including new explanatory variables into allometric models. Here, using an extensive dataset of 566 trees widely distributed over Rio de Janeiro state, Brazil, we investigated the influence of stand structure, climate, soil fertility and texture in tree allometry (bark thickness, height, and stem volume) in hyperdiverse and structurally complex Atlantic Forest. Water stress, soil texture and to a lesser extent basal area, soil fertility and precipitation, were strong predictors of tree height and volume. Wetter forests with richer soils support higher-statured trees with greater woody volume, whilst drier environments with moderate to low nutrient availability are associated with small-statured and low tree volume. In contrast, bark thickness was solely determined by soil fertility and ph. Negligible relationship between bark thickness and climatic variables is likely associated with our studied gradient that did not encompass dry forests that are adapted to frequent and intense fires, and where bark investment to stem protection ensures survival. These findings suggest that more appropriate approach to reliably estimate tree height, volume and bark thickness at regional and landscape scale, should incorporate environmental descriptors that are strongly associated with forest structure. [ABSTRACT FROM AUTHOR]