Tree Volume Research Articles

Vertical distribution of trunk and crown volume in tropical trees

Tree volume equations including branches are scarce in forestry literature, especially in diverse tropical forests, where the variability in tree shapes hampers the development of overall volume descriptions. We present species-composite cumulative volume profile models that describe the volume contained up to a given height in the trunks and crowns of tropical trees. We use terrestrial laser scanning (TLS) and quantitative structure models to estimate the trunk and crown volume of 177 trees (49 species) in a lowland tropical forest in the Barro Colorado Island in Panamá. These models were fitted using multilevel mixed-effects models recognizing the diversity of architectures in tropical trees. We found that (1) the rate at which volume accumulated with height was much higher and variable in the whole tree (trunk + branches) than only in the trunk; (2) the variability in the rate of volume accumulation was three times higher in the trunk and nine times higher in the whole tree across individuals within species than between species; and (3) parameters describing the rate of volume accumulation significantly depended on the height of attachment of the lowest branch, but not on the tree size. The resulting equations can be used to estimate the proportion of volume contained up to any height in tropical trees.

Growth Response of Ponderosa Pine to Intensive Cultural Treatments Varies with Site Quality and Plantation Age

Abstract Long-term forest experiments provide valuable knowledge in managing forests for productivity and other ecosystem services. California’s “Garden of Eden” experiment was established to determine growth potential of Pinus ponderosa plantations in response to intensive cultural treatments. We examined the 20-year growth-response of tree volume to intensive cultural treatments consisting of combinations of herbicide on competing vegetation (H), fertilization (F), and insecticide (I). We found that both H and F treatments synergistically increased tree growth at intermediate and lower-quality sites. Growth increased by 1.5–2.1 times with F, 2.1–2.5 times with H, and 2.3–3.8 times with HF treatments versus control (range = 39.3–109.2 m3 ha−1). Across the highest productive site, H and F effects on volume seemed additive at younger ages, but largely dissipated by age 20, with volume increasing by 1.6, 1.2, and 1.6 times relative to control in F, H, and HF treatments, respectively. However, 20-year mean annual increment was 21.7 m3 ha−1 yr−1 for the F treatment, the highest volume reported for ponderosa pine in California. The results underscore how site-specific cultural treatments, especially H and F, may widely enhance plantation productivity and boost stand development. Study Implications In Mediterranean climates, competing vegetation control is essential for ponderosa pine planation establishment and early growth, especially at intermediate and poor-quality sites. At higher-productivity sites, fertilization enhances stand growth and development, although fertilization’s beneficial effects on growth do not appear until canopy closure. Precommercial thinning in herbicide and fertilization treatments will not reduce overall stand growth 10 years postthinning. Intensively managed plantations appear to have a higher maximum stand density index compared to natural stands or unmanaged plantations. Therefore, these cultural treatments can be used to rapidly reforest areas after disturbances and subsequently promote larger trees on reforested landscapes.

Feature selection by genetic algorithm in nonlinear taper model

Tree stem profile results from a complex structure of shapes and dimensions determined by ecological processes within the forest. However, the feature selection in the development of taper models has been underinvestigated to date. We propose a genetic algorithm (GA) to assess factors that affect the stem taper and volume of Eucalyptus urograndis trees at different ages (2, 7, and 14 years) in Brazil. A total of 213 sample trees were measured in diameter and height along the stem, crown width, crown base height, crown length, and crown ratio. These variables and the stand age were supplied to the GA that selects variables, replacing those of Kozak’s 2004 model. The performance of models was evaluated using error statistics and residual plots. The GA model was efficient in predicting diameters and volumes, mainly by increasing the accuracy of the estimates in the extreme portions of the trees. This was attributed to the selection of morphometric variables as predictors of stem taper and volume, making them understandable in ecological terms. We highlight GA as a robust tool, since it incorporated the morphometric variables in Kozak’s model that contribute to the estimates.

Does natural stand dynamics generate an aggregated pattern of canopy openness? A case study in Abies-Picea-Fagus old-growth forests

The action of many agents causing the mortality of overstory trees may potentially induce the formation of an aggregated distribution of canopy gaps. In this study we tested the hypothesis that natural stand dynamics generates an aggregated pattern of canopy openness in old-growth forests formed by Fagus sylvatica L., Abies alba Mill. and Picea abies (L.) H. Karst. We compared canopy openness and its spatial heterogeneity in five stands in the Western Carpathians (Central Europe) and three stands in the Dinaric Mountains (Southeast Europe). The stands were between 4.48 and 9.24 ha in size. In each stand we took hemispheric photographs in a regular 20 × 20 m grid in the leafless period to minimize coverage by the understory. Tree species and the dbh of live trees of dbh ≥7 cm were recorded on circular plots with a radius of 7 m centered at the grid points. At the stage of picture processing, understory trees of dbh <25 cm and polar coordinates recorded during field measurements were removed from the pictures, and for every grid point the local canopy openness of the overstory layer was determined in the sky region defined by a zenith angle of 15°. We characterized the spatial pattern of canopy openness by using variograms and Moran’s I coefficients and tested the spatial dependence in the distribution patterns of grid points characterized by different levels of canopy openness. Depending on the stand, mean canopy openness varied between 17.5 and 41.0%, with the greatest values recorded in the Carpathian stands with a considerable proportion of Norway spruce and a more severe disturbance regime. Relationships between canopy openness and the overall number, basal area or volume of trees forming the overstory were strongly modified by variation in the density and species percentage in the mid-canopy zone. In all the stands small-scale variation determined for inter-point distances of 20 m accounted for the majority of the total variation in canopy heterogeneity and ranged between 61 and 100%. We found a tendency to form random patterns of canopy openness in the Dinaric stands, which were characterized by a greater basal area and probably also lower frequency of severe disturbances, and aggregated patterns in the Carpathian stands, which were characterized by a smaller basal area driven by more severe disturbances. The revealed spatial dependence in canopy openness may suggest that in the studied ecosystem canopy gaps are not only a legacy of the mortality of canopy trees but also self-organizing structural elements which, under a more severe disturbance regime, can affect the mortality rate in their neighbourhood. Nonetheless, the percentage of spatially structured variability in canopy openness observable at scales larger than the grid spacing used in our study was insignificant (83% on average). The close-to-random pattern of canopy heterogeneity may weaken the spatio-temporal synchronization of the juvenile growth, maturation and senescence of neighbouring trees and counteract the formation of coarse-grained patch mosaics.

HARVESTER PRODUCTIVITY AND COSTS IN CLEAR CUTTING Pinus taeda STANDS UNDER DIFFERENT MANAGEMENT REGIMES

The increased demand for several forest products makes it necessary to apply different management regimes in forest stands, which may influence the wood harvesting operations. This study aimed to evaluate the effect of average individual tree volumes obtained through different management regimes on harvester productivity and costs, thereby enabling to generate information for forest managers. The study was carried out in three Pinus taeda L. stands under clear cutting with different average individual tree volumes (AIV): I (0.367 m3); II (0.582 m3); and III (0.766 m3). Working cycle times, productivity per productive machine hour, energy yield and production costs were obtained by a time and motion study, in which the average values obtained were compared by the Tukey-Kramer test (α ≤ 0.05). The work elements of the harvester’s work cycles were affected by forest management regimes, mainly the movement and the processing, with significant statistical difference between stands, but no difference between total working cycle times. The management regime applied to forest stands influenced the spacing and whole trunk volume which consequently increased the average productivity of the machine from 36.8 to 74.1 m³ per productive machine hour in treatments I and III, respectively, and reduced production costs by 50%. The forest management regimes influenced the clear-cutting operation with harvester.

Spatial Distribution of Soil Moisture Content and Tree Volume Estimation in International Institute of Tropical Agriculture Forest, Ibadan, Nigeria

The role of soil moisture in the survival and growth of trees cannot be over-emphasized and it contributes to the net productivity of the forest. However, information on the spatial distribution of the soil moisture content regarding the tree volume in forest ecosystems especially in Nigeria is limited. Therefore, this study combined spatial and ground data to determine soil moisture distribution and tree volume in the International Institute of Tropical Agriculture (IITA) forest, Ibadan. Satellite images of 1989, 1999, 2009 and 2019 were obtained and processed using topographic and vegetation-based models to examine the soil moisture status of the forest. Satellite-based soil moisture obtained was validated with ground soil moisture data collected in 2019. Tree growth variables were obtained for tree volume computation using Newton’s formular. Forest soil moisture models employed in this study include Topographic Wetness Index (TWI), Temperature Dryness Vegetation Index (TDVI) and Modified Normalized Difference Wetness Index (MNDWI). Relationships between index-based and ground base Soil Moisture Content (SMC), as well as the correlation between soil moisture and tree volume, were examined. The study revealed strong relationships between tree volume and TDVI, SMC, TWI with R2 values of 0.91, 0.85, and 0.75, respectively. The regression values of 0.89 between in-situ soil data and TWI and 0.83 with TDVI ascertain the reliability of satellite data in soil moisture mapping. The decision of which index to apply between TWI and TDVI, therefore, depends on available data since both proved to be reliable. The TWI surface is considered to be a more suitable soil moisture prediction index, while MNDWI exhibited a weak relationship (R2 = 0.03) with ground data. The strong relationships between soil moisture and tree volume suggest tree volume can be predicted based on available soil moisture content. Any slight undesirable change in soil moisture could lead to severe forest conditions.

Ground-based/UAV-LiDAR data fusion for quantitative structure modeling and tree parameter retrieval in subtropical planted forest

Light detection and ranging (LiDAR) has contributed immensely to forest mapping and 3D tree modelling. From the perspective of data acquisition, the integration of LiDAR data from different platforms would enrich forest information at the tree and plot levels. This research develops a general framework to integrate ground-based and UAV-LiDAR (ULS) data to better estimate tree parameters based on quantitative structure modelling (QSM). This is accomplished in three sequential steps. First, the ground-based/ULS LiDAR data were co-registered based on the local density peaks of the clustered canopy. Next, redundancy and noise were removed for the ground-based/ULS LiDAR data fusion. Finally, tree modeling and biophysical parameter retrieval were based on QSM. Experiments were performed for Backpack/Handheld/UAV-based multi-platform mobile LiDAR data of a subtropical forest, including poplar and dawn redwood species. Generally, ground-based/ULS LiDAR data fusion outperforms ground-based LiDAR with respect to tree parameter estimation compared to field data. The fusion-derived tree height, tree volume, and crown volume significantly improved by up to 9.01%, 5.28%, and 18.61%, respectively, in terms of r RMSE. By contrast, the diameter at breast height (DBH) is the parameter that has the least benefits from fusion, and r RMSE remains approximately the same, because stems are already well sampled from ground data. Additionally, particularly for dense forests, the fusion-derived tree parameters were improved compared to those derived from ground-based LiDAR. Ground-based LiDAR can potentially be used to estimate tree parameters in low-stand-density forests, whereby the improvement owing to fusion is not significant. • Mitigation of the limitations of tree localization in case of ground-based/ULS LiDAR data co-registration using virtual keypoints. • Fusion of ground-based/ULS LiDAR data based on removal of redundant and noisy points. • Investigation and evaluation of the utility of ground-based/ULS LiDAR data fusion for tree parameter estimation. • Ground-based/ULS LiDAR data fusion improved estimation of tree height, tree volume, and crown volume. • Ground-based/ULS LiDAR data fusion has strong potential in QSM of trees particularly in high-stand-density forest.

Addressing uncertainty and bias in land use, land use change, and forestry greenhouse gas inventories

National greenhouse gas inventories (NGHGIs) will play an increasingly important role in tracking country progress against United Nations (UN) Paris Agreement commitments. Yet uncertainty in land use, land use change, and forestry (LULUCF) NGHGHI estimates may undermine international confidence in emission reduction claims, particularly for countries that expect forests and agriculture to contribute large near-term GHG reductions. In this paper, we propose an analytical framework for implementing the uncertainty provisions of the UN Paris Agreement Enhanced Transparency Framework, with a view to identifying the largest sources of LULUCF NGHGI uncertainty and prioritizing methodological improvements. Using the USA as a case study, we identify and attribute uncertainty across all US NGHGI LULUCF “uncertainty elements” (inputs, parameters, models, and instances of plot-based sampling) and provide GHG flux estimates for omitted inventory categories. The largest sources of uncertainty are distributed across LULUCF inventory categories, underlining the importance of sector-wide analysis: forestry (tree biomass sampling error; tree volume and specific gravity allometric parameters; soil carbon model), cropland and grassland (DayCent model structure and inputs), and settlement (urban tree gross to net carbon sequestration ratio) elements contribute over 90% of uncertainty. Net emissions of 123 MMT CO2e could be omitted from the US NGHGI, including Alaskan grassland and wetland soil carbon stock change (90.4 MMT CO2), urban mineral soil carbon stock change (34.7 MMT CO2), and federal cropland and grassland N2O (21.8 MMT CO2e). We explain how these findings and other ongoing research can support improved LULUCF monitoring and transparency.

Volumetric overestimation of small branches in 3D reconstructions of &lt;i&gt;Fraxinus excelsior&lt;/i&gt;

Terrestrial laser scanning (TLS) has been applied to estimate forest wood volume based on detailed 3D tree reconstructions from point cloud data. However, sources of uncertainties in the point cloud data (alignment and scattering errors, occlusion, foliage...) and the reconstruction algorithm type and parameterisation are known to affect the reconstruction, especially around finer branches. To better understand the impacts of these uncertainties on the accuracy of TLS-derived woody volume, high-quality TLS scans were collected in leaf-off conditions prior to destructive harvesting of two forest-grown common ash trees ( L.; diameter at breast height ~28 cm, woody volume of 732 and 868 L). We manually measured branch diameters at 265 locations in these trees. Estimates of branch diameters and tree volume from Quantitative Structure Models (QSM) were compared with these manual measurements. The accuracy of QSM branch diameter estimates decreased with smaller branch diameters. Tree woody volume was overestimated (+336 L and +392 L) in both trees. Branches measuring &lt; 5 cm in diameter accounted for 80% and 83% of this overestimation respectively. Filtering for scattering errors or improved coregistration approximately halved the overestimation. Range filtering and modified scanning layouts had mixed effects. The small branch overestimations originated primarily in limitations in scanner characteristics and coregistration errors rather than suboptimal QSM parameterisation. For TLS-derived estimates of tree volume, a higher quality point cloud allows smaller branches to be accurately reconstructed. Additional experiments need to elucidate if these results can be generalised beyond the setup of this study.Fraxinus excelsior

Geographic variation in growth and wood traits of &lt;i&gt;Neolamarckia cadamba&lt;/i&gt; in China

<italic>Neolamarckia cadamba</italic> is an indigenous, timber-producing tree species in Southern China that plays an important role in the sustainable development of the local forestry industry. However, the geographic genetic variation across its natural distribution area in Southern China has yet to be characterized for best utilization. Here, we report the geographic genetic variation in growth and wood properties of <italic>N. cadamba</italic> from 10 provenances that represent the entire natural distribution of<italic> N. cadamba</italic> in Southern China. There was significant geographic variation in diameter breast height (DBH), height (H), volume (V), vessel length (VL), vessel diameter (VD), VL/VD, and wood basic density (WBD). The variation in tree volume across provenances was greater than that of other growth traits, indicating that volume has a greater potential for selection in provenance trials. The provenance heritabilities of growth traits and wood properties ranged from 0.59 to 0.67 and from 0.40 to 0.45, respectively. Trend surface analysis revealed that patterns of geographic variation associated with growth traits were weakly negatively correlated with those of wood properties. The pattern of geographic variation in growth traits showed a gradual increase from the periphery to the central region, whereas wood properties showed the opposite pattern, and latitude had the greatest effect on both. Wood property measurements suggested that the YNMS provenance produced superior timber wood, whereas the GXLZ, GXFCG, and GXNN provenances produced the best pulpwood. These provenances could potentially provide more valuable breeding materials for the genetic improvement of <italic>N. cadamba</italic>.

First Report of Citrus Bent Leaf Viroid and Citrus Dwarfing Viroid in Argentina

Citrus Bent Leaf Viroid (CBLVd) and Citrus Dwarfing Viroid (CDVd), from genus Apscaviroid, are two of the widely distributed citrus viroids among the eight reported to date. They have been found to induce reduction in canopy volume and fruit production in citrus trees on trifoliate and trifoliate orange hybrids rootstocks. Moreover, citrus trees infected only with CBLVd or in combinations with Citrus Exocortis Viroid (CEVd), Hop Stunt Viroid (HSVd) and CDVd have been associated with a poor development of the root system. Samples of citrus trees showing viroid symptoms collected from citrus orchards in Tucumán, Salta, and Jujuy provinces (NW region in Argentina) were initially indexed on citron (Citrus medica) and then analyzed by s-PAGE. These samples were found to be infected with different viroid species, among them, CEVd and HSVd have been already identified. In order to determine the presence of other viroids, we performed a RT-PCR assay using specific primers for CBLVd, CDVd, CBCVd and CVd-V. Forty two samples including 15 lemons, 15 oranges, 8 grapefruits, 2 citrumelos and 2 Cleopatra mandarins were analyzed so far. On the basis of amplification of the appropriately sized DNA, CDVd was detected in thirty eight samples and CBLVd in all grapefruit samples. CBCVd and CVd-V were not found in any samples to date. Analysis of the sequence of amplicons revealed 96% and 97% identity with CBLVd GenBank reference sequences, and 96% to 98% with CDVd GenBank reference sequences. This is the first report of CBLVd and CDVd in citrus trees in Argentina.

Eucalypt clone modelling in agrosilvopastoral systems

The objective of this work was to evaluate height-diameter, volumetric, and taper models to estimate the height, volume, and bole profile of trees of eucalypt clones (Eucalyptus grandis × Eucalyptus urophylla) in an agrosilvopastoral system. Data were collected from permanent plots in an eight year-old agrosilvopastoral system, composed by three eucalypt clones (VE01, VE06, and VE07), located in the municipality of Coronel Xavier Chaves, in the state of Minas Gerais, Brazil. Two height-diameter, three volumetric, and four taper models were fit to the data of each clone and compared to each other, in order to select the best-fitting one. The equations fitted well to the observed data, and those of the models of Campos, Schumacher-Hall, and Garay stood out as the best ones. In addition, Graybill’s F-test showed that the height-diameter and volumetric equations must be fitted separately for each genetic material. The model of Garay was the best taper model to estimate the bole profiles of all clones using a single equation.

Multiple forest structural elements are needed to promote beetle biomass, diversity and abundance

Retention forestry is a management strategy aiming to mitigate biodiversity loss by retaining structural elements such as dead trees that would otherwise be removed. Here we analyze the biomass, diversity and abundance among forest beetles collected using window traps on 128 1-ha forest sites reflecting gradients in the amount of structural elements in southwestern Germany. We found that beetle biomass increased with mean diameter at breast height (a measure of tree size), and decreased with stand structural complexity. Biomass of individual feeding guilds responded differently to forest structural elements, namely lying deadwood, understory complexity, tree basal area and stand structural complexity. Beetle family diversity increased with the effective number of layers, i.e. 1-m forest strata occupied by vegetation assessed via terrestrial laser scanning. Abundance of feeding guilds responded to only elevation and share of deciduous trees. Community composition in terms of biomass was structured by forest elements similar to biomass of individual feeding guilds, with the addition of lying deadwood. This differed from community composition in terms of abundance of feeding guilds, which was structured by primarily standing deadwood volume and share of deciduous trees. Our results show that biomass, diversity and abundance respond differently to forest structural elements. This suggests that the concurrent prioritization of multiple forest elements is needed to promote forest beetles, with more focus placed on the differing resource needs among feeding guilds. In addition, retention strategies should also consider the varying responses of beetle biodiversity metrics when assessing the importance of forest structural elements.

Research on Forest Management in the Context of Carbon Sequestration

As resources are exploited around the world, the environment is being affected as never before, and one of the more serious problems is global warming. This paper presents a more comprehensive study of forest management plans in areas such as the Cariboo Forest. First, the paper fit the relationship between tree age and volume using logistic regression, and then estimate the forest's maximum carbon storage 𝐶𝑠𝑢𝑚 using the biomass conversion factor method along with a modified Leslie model. In this paper, three aspects of economic benefit, social demand and carbon storage are balanced, and a forest decision-making model based on multi-objective linear programming is established. This paper applies the model to the Cariboo Forest area and optimizes the carbon sequestration assessment model using the first-order decay method (FOD), taking into account the carbon release from wood products.

The Composition and Vegetation Potention Study of Production Forest in Kphp Dampelas Tinombo Area, Pariasanagung Village, Dampelas Sub District of Donggala, Central Sulawesi Province

The production forest area in the Dampelas Tinombo KPH (Forest Management Unit is an organization that works at the site level and is expected to be a prerequisite for the implementation of a sustainable and equitable forest management system) area which was included in the area of Parisan Agung Village, Dampelas District which was indicated to be damaged had an area of about 410 Ha, so that a study was needed on the composition and potential of production forest in Parisan Agung Village in order to plan the utilization and development of plantation forests that were aims to provide welfare for people living around forest areas without changing their main function. This research was carried out for 3 months starting from June to September 2018. The location of this research was in a production forest located in the Dampelas Tinombo KPHP Model area which was included in the Parisan Agung Village area, Dampelas sub district of Donggala, Central Sulawesi Province. The composition of forest vegetation types in Parisan Agung Village consisted of 28 types of vegetation. at the tree level in the plot as many as 165 individuals from 25 types of vegetation while the pole level vegetation as many as 140 individuals from 25 types of vegetation, at the sapling level as many as 145 individuals from 28 types of vegetation and seedling level as many as 154 individuals from 28 types of vegetation. While the potential volume of trees in the observation plot was 162.53 m3 from 165 individuals, the type of bayas had the highest volume with 13. 17 m3 and the volume of the pole level in the observation plot was 17.89 m3 from 140 individuals, the prupuk species had a volume of 17.89 m3. the largest with 1.63 m3

Individual Tree Volume Models and Form Factors for Woody Species in Dry Afromontane Forest, Central Ethiopia

Individual Tree Volume Models and Form Factors for Woody Species in Dry Afromontane Forest, Central Ethiopia

Adapting a Quercus robur allometric equation to quantify carbon sequestration rates on the Middle Elbe floodplain

Destructively sampling old Pedunculate oak (Quercus robur) trees on the active floodplain of the Middle Elbe to create an allometric equation to estimate carbon stocks (CS) and carbon sequestration rates (CSR) would defeat the purpose of protecting increasingly vulnerable and threatened primeval floodplain forests. To nondestructively estimate CS and CSR, we have adapted a two-parameter allometric equation which uses tree height (H) and diameter at breast height (DBH) (Dik 1984, Zianis et al. 2005) into a 1-parameter equation that requires only DBH to quantify stocks and annual changes in carbon stock (carbon sequestration rates) for individual Q. robur trees. The equations have also been adapted to estimate below- and above-ground carbon stocks of individual trees.The new method has:•Adapted a 2-parameter Quercus robur allometric equation which estimates tree volume to a 1-parameter equation which estimates above and below-ground carbon stock•Removed the requirement of tree height to reconstruct the carbon stock of trees at an annual timestep•An almost perfect linear relationship (Pearson R2= 0.998) between carbon sequestration rate and basal area increment (BAI)

Stem volume equation for constructing local volume table of Pinus merkusii Jungh et de Vriese in Tana Toraja community forest

Pinus merkusii Jungh et de Vriese is a plant with high market and economic values due to providing a variety of products, including wood. Good management is needed to preserve pine forest products. The first step toward effective forest management is developing a management plan based on estimated stock data. The volume table used has a significant impact on the accuracy of the stock potential estimate. This study aims to determine the best equation model for compiling a local volume table for P. merkusii Jungh et de Vriese in Tana Toraja Regency. The research was conducted at the community pine forest in Gandang Batu Sillanan and Mengkendek districts, Toraja Regency. The number of sample measured was 100 trees. An analytical method was used to calculate the amount of tree volume on allometric equations. The equation for the stem volume was made using the allometric equation. The research results showed that diameters' mean, standard deviation, and sampling error values were 28.34 cm, 7.39 cm, and 1.45, respectively, heights were 23.77 m, 7.37 m, and 1.44; volume was 1.44 m3, 0.96 m3, and 0.19. The regression equation modelling showed that the best equation model for estimating volume P. merkusii Jungh et de Vriese based on height and diameter was 𝑉=𝑎𝐷2𝐻.

Growth and Productivity Modeling of Seven Eucalyptus Species in Souiniet’s Arboretum in the Northwestern of Tunisia

This study consists of the development of tree growth models to deduce stands productivity and determine the highest productive species in the conditions of the concerned plantation. Seven Eucalyptus, introduced in the arboretum of Souiniet (north-west of Tunisia, wet Mediterranean bioclimate) in a Cork Oak natural forest, were studied. Stem analysis and non-linear growth modeling regression equations were used to predict wood productivities. Gompertz and Chapman–Richards growth function appeared as being great numerical models to estimate the Eucalyptus tree diameter and height evolutions, respectively. Moreover, an adapted Chapman–Richards model allowed predicting the volume of trees in an efficient manner. The values of mean annual volume productivity of the Eucalyptus spp.studied, allow us to classify them in order of increasing annual productivity, as follows: E. sideroxylon, E. cinerea, E. maidenii, E. macrorhyncha, E. tereticornis, E. viminalis and E. bicostata. The first three Eucalyptus spp. appeared as the best-adapted and most suitable Eucalyptus trees for new plantations in this area. These species had the highest mean annual increments, ranged from 5 to 10 m3.ha−1.year−1 with 15 to 20 years of rotation. E. bicostata is the most promising, with annual average production exceeding 10 m3.ha−1.year−1 after 25 years, and reaching 20 m3.ha−1.year−1 at 40 years old. These modeling approaches provide additional knowledge on the productivity of the different Eucalyptus species, thus enabling forestry operators to simulate the development of forest stands in order to optimize timber production and harvesting.

Influences of determined and estimated dendrometric variables on the precision of volumetric modelling

The use of independent variables in volumetric modelling is an important step in fitting models to represent tree or stand characteristics. The DBH measured at 1.3 m from the ground level and total tree height (Ht) are the most commonly used independent variables when modelling individual tree volumes. This work aimed to analyze the importance of independent variables in fitting and selecting volumetric equations. A total of 750 trees from an experiment with three Eucalyptus spp. clones planted in five spacings in the semi-arid region of Pernambuco were used. Four statistical procedures were applied to compare the equations: Adjusted Fit Index (AFI), Akaike information criterion (AIC), mean absolute percentage error (MAPE), and a completely random design having the real tree volume as control and the fit equations as treatments. The error measuring heights in the field (EH) was also analyzed. Four heights were evaluated: Ht, height estimated in the field (He) and heights adjusted (Ha) from hypsometric relationships using the DBH [Ha (a)] and D&lt;sub&gt;1.7&lt;/sub&gt; [Ha (b)], which was the diameter most correlated with the volume. The result indicates that all 18 fitted models provided high precision volumetric equations which do not differ at the 5% significance level.