Tree Volume Research Articles

A Combination of Biotic and Abiotic Factors and Diversity Determine Productivity in Natural Deciduous Forests

The relative importance of different biotic and abiotic variables for estimating forest productivity remains unclear for many forest ecosystems around the world, and it is hypothesized that forest productivity could also be estimated by local biodiversity factors. Using a large dataset from 258 forest monitoring permanent sample plots distributed across uneven-aged and mixed forests in northern Iran, we tested the relationship between tree species diversity and forest productivity and examined whether several factors (solar radiation, topographic wetness index, wind velocity, seasonal air temperature, basal area, tree density, basal area in largest trees) had an effect on productivity. In our study, productivity was defined as the mean annual increment of the stem volume of a forest stand in m3 ha−1 year−1. Plot estimates of tree volume growth were based on averaged plot measurements of volume increment over a 9-year growing period. We investigated relationships between productivity and tree species diversity using parametric models and two artificial neural network models, namely the multilayer perceptron (MLP) and radial basis function networks. The artificial neural network (ANN) of the MLP type had good ability in prediction and estimation of productivity in our forests. With respect to species richness, Model 4, which had 10 inputs, 6 hidden layers and 1 output, had the highest R2 (0.94) and the lowest RMSE (0.75) and was selected as the best species richness predictor model. With respect to forest productivity, MLP Model 2 with 10 inputs, 12 hidden layers and 1 output had R2 and RMSE of 0.34 and 0.42, respectively, representing the best model. Both of these used a logistic function. According to a sensitivity analysis, diversity had significant and positive effects on productivity in species-rich broadleaved forests (approximately 31%), and the effects of biotic and abiotic factors were also important (29% and 40%, respectively). The artificial neural network based on the MLP was found to be superior for modeling productivity–diversity relationships.

Forest recovery on skid trails and felling gaps following post-decadal selective logging in a moist semi-deciduous forest in Ghana

While several studies have been conducted on the impacts of logging on forest recovery in tropical forests, most of these studies have largely focused on short term forest recovery and without perspectives on how different logging intensities could influence the nature and extent of forest recovery in the long term. This study therefore aims to explore how varying site conditions, resulting from the creation of different disturbance types (skid trails and felling gaps) following selective logging at two logging intensities influenced long-term floristic composition eighteen years after logging. The study was conducted in the permanent sample plots located in a 134-ha compartment in the Pra-Anum Forest Reserve. Data collection was conducted on 160 recording plots distributed on three disturbance sites and an unlogged area, within two blocks of logging intensity of 26.32 m3/ha and 52.63 m3/ha (representing the volume of trees harvested per hectare). Results showed that the main skid trail had significantly lower species abundance and richness than the other disturbance types and the unlogged area. There was also a significant difference in species spatial distribution across all the four sites. These distribution patterns revealed differences in plant dominance at disturbance gradients, which indicate their success at competing for available resources within their niche space. Furthermore, the number of species belonging to particular ecological guilds classified from the different skid trails and unlogged areas as well logging intensities showed no significant variation. However, most of the species sampled across the disturbance regimes and unlogged area were observed to be shade tolerant. Logging disturbance and logging intensity did not influence the distribution of trees of national conservation importance (based on tree distribution, ecology, local abundance, interaction with ecosystem parameters and economic importance which have been used as basis conservation prioritization). However, disturbance type and higher logging intensities favoured tree species of minimal timber and national conservation importance, relative to the unlogged area. Given the increasing demand for timber products for both domestic and international markets, which is driving higher harvesting intensities legally and illegally, this study will inform forest management decision making on the long term dynamics of tree species recovery following logging.

Особенности пространственно-временной структуры соснового древостоя на южном склоне восточного Саяна

Due to relatively long development and long life of forest-forming species most of the conclusions on stand dynamics are based on the data collected by indirect methods of comparative research and analysis of cenosis forming theoretically temporal and spatial succession sequences and need to be verified and clarified. The most reliable results on the stand dynamics can be received on stationary objects such as permanent sample areas. The article presents the analysis results of long-term monitoring (1968–2012) of a pine (Pinus sylvestris L.) stand in low-mountain Eastern Sayan on the south slope with a steepness of 7–8º. The intermittent test of morphometric indicators of trees mapped on the permanent sample area was used. It is shown that the sum of tree trunk cross-section areas at breast height (1.3 m) varied by no more than 10 % with timber reserves on the lower, central and upper equal sites of the sample area during the entire observation period. At the same time heterogeneity of ecological conditions, taking place even on a small section of a smooth slope, influences the plantation self-thinning intensity. In the 42-year-old stand density ratio at lower, central and upper sites was 1:1.5:2.1. Stand density difference along the slope had been decreasing gradually over time, although it remained around 30 % at the time of the last observation. Over the years of observation, 53, 47, and 32 % of pines on the lower, central, and upper sites, respectively, have survived. The calculated average age of the died trees showed that in all groups of natural diameter classes, there was an earlier die-off of pines at the bottom of the slope with an increase in dying age up to the slope. Trees with larger trunk diameter (first telling) died later. All this led to a rearrangement of the horizontal structure of the plantation, a decrease in the average diameter and average volume of trees up to the slope. Typical for mountain forests clinal tree distribution, which affects their morphological indicators, is important to consider when studying and modeling forest ecosystems, as well as when implementing forest management measures. For citation: Ovchinnikova N.F. Spatiotemporal Structure Features of a Pine Stand on the South Slope of the Eastern Sayan Mountains. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 5, pp. 34–47. DOI: 10.37482/0536-1036-2021-5-34-47

CARBON SEQUESTRATION POTENTIAL OF ROAD SIDE STANDING TREES IN KAMAREDDY MUNICIPALITY, TELANGANA, INDIA

In our study of Kamareddy Municipality area, we laid out a 27 sample plots linearly along the road side. 27 sample plots covered about 2.7 ha of land that means each plot size is 0.1 ha. We enumerated 229 number of tree individuals in sampled area. In the 27 sample plots, we calculated 53.5 M3 0f tree volume, mean volume per plot is 1.98 M3 . Total biomass (AGB+BGB) is about 44.7 tones; mean biomass per plot is around 1.65 tones. Total carbon calculated 1.3 tons, mean carbon is 0.78 tones per plot. The total Carbon sequestration potential is 77.9 tones, mean carbon sequestration potential per plot is about 2.88 tones. By the calculations we assumed per hectare volume is 19.81 M3 , biomass is 16.5 tones, carbon stock is 7.88 tones and carbon sequestration potential is 28.85 tons per hectare.

Stand structure and growth of Robinia pseudoacacia 'Jászkiséri' - 'Jászkiséri' black locust

Black locust (Robinia pseudoacacia L.) is one of the most widespread tree species introduced into Europe and also into Hungary. It covers 24% of the total Hungarian forest area, providing 25% of the annual timber output of the country. Due to the demands of consumers, new cultivars are to be produced by means of improvement techniques and are to be introduced into the practical forestry use. Mono- and multiclonal cultivars were developed, then variety comparison trials and cultivation tests were established. Based on preliminary yield tests the locust cultivar ‘Jászkiséri’ (Robinia pseudoacacia ‘Jászkiséri’) proved to be one of the best black locust cultivars. Consequently, a more precise investigation of the stand structure of this cultivar may also make a significant contribution to the improvement of the relevant cultivation technology. In this study, based on full inventories of 13 stands in 7 subcompartments, age of 5 to 35 years, relationships of mean tree volume to diameter (R<sup>2</sup> = 0.9797) and basal area (R<sup>2</sup> = 0.9781), furthermore the relationship between mean tree volume and diameter of the stands (R<sup>2</sup> = 0.9993) were examined. Besides that, the comparison of 15-year-old ‘Jászkiséri’ and common black locust (a case study) were presented in this paper, where ‘Jászkiséri’ proved to be better: significant differences (P < 0.05) were found in diameter, mean tree volume and stem form.

Effect of spacing on volume, form factor and taper for Pinus taeda trees in Paraná, Brazil

Several forestry procedures affect tree volume and shape, such as spacing, pruning, and thinning. Studying and understanding the effect of these operations on stand attributes are very important for forest management. This study aimed to evaluate volume, form factor, and taper for Pinus taeda trees stratified into diameter classes within two planting spacings. In addition, we aimed to evaluate the time spent to scale each tree, measured with a chronometer. Indirect scaling was performed using a Criterion RD 1000. Thirty trees were scaled on each planting spacing (3 m x 2 m and 4 m x 2 m), totaling 60 trees encompassing all diameter classes. Tree volume was calculated using the Smalian equation. Tree volume, form factor, and taper were calculated to each tree and evaluated by stand (independent t-test) and diameter class (variance analysis and Tukey test). The average scaling time was 4 minutes and 35 seconds, which decreased with practice (-24%). Form factor and taper differed with spacing and diameter class. Volume did not differ with spacing, but it did in the diameter classes. We concluded that indirect scaling is a practical method for tree volume assessment; higher planting density leads to more cylindrical stems with lower taper ratios in comparison with denser stands; and the fact that tree volume, form factor and taper differed among the diameter classes should be incorporated into studies of taper modeling.

Machine learning and regression models to predict multiple tree stem volumes for teak

The quantification of a stand’s wood stock is one of the most important procedures for Tectona spp. (teak) management. An optimal method for estimating tree volume must accommodate the variation of the data collected in the inventory. This study evaluated alternative methods to estimate the volume on stems of teak trees. We cut and measured the outside bark, inside bark, and heartwood diameters at heights of 0.1, 0.5, 1.5 m and every meter thereafter until the minimum outside bark diameter reached 3 cm, using 180 trees of ages 3 to 12 years. We tested two approaches (A1 and A2) to estimate stem volumes of the outside bark, inside bark, and heartwood (v ob, v ib and v hw, respectively): modelling the tree volume in A1, and the taper model in A2, with the techniques of regression, artificial neural network (ANN) and support vector regression (SVR). In addition, we obtained the percentages of heartwood, sapwood and bark in the stem. The accuracies of the estimates were evaluated using bias, correlation and root-mean- square error (RMSE). Validation was made for the outside bark, inside bark and heartwood volumes, and the outside bark, inside bark and heartwood diameters, from the taper models. In A1, the ANN technique more accurately predicted v ob and v ib, with RMSE% values of 18.88% and 18.54%, respectively; for v hw, the regression technique was more accurate, with RMSE% equal to 26.87%. In A2, the regression technique obtained the highest precision in the prediction of v ob, v ib and v hw, with RMSE% values of 13.99%, 13.31% and 26.50%, respectively. Approach A2 showed more accurate results compared with A1 for predicting the multiple volumes of teak trees with the three tested techniques.

Productivity curve models in eucalypt timber forwarding

Extraction is the most costly and complicated stage of timber harvest operations. The forwarder’s productive capacity in timber harvesting, from planted forests, is influenced by several operational variables, especially by extraction distance and tree volume. Prior knowledge about the effect of these variables on the operation is required for efficient planning. The goal of this research was to model and simulate a forwarder productivity curve for timber extraction in scenarios with different tree average volumes (TAV) and average extraction distances (AED). The research was carried out in a forestry company in the state of Mato Grosso do Sul, Brazil, in clonal eucalyptus stands with TAV varying from 0.186 to 0.310 m3 tree−1 and AED from 0 to 280 m. We performed a time and motion study of the forwarder, following the operation with a DJI-Phantom 4 Advanced drone. Productivity simulations were carried out in different operational scenarios. The models were evaluated using the adjusted determination coefficients (R 2 adj.), standard error of absolute estimate and F-value. Results have shown that as the TAV increased, productivity also increased 14% while the AED presented a relationship inversely proportional to productivity. The highest productivity of the machine occurred in the forest condition with a TAV of 0.31 to 0.36 m3 tree−1 and in the shortest extraction distances. The best-adjusted model explained 46.3% of the machine’s productivity variation. We concluded that TAV and AED variables had a significant impact on the forwarder’s productivity and that it is important to obtain the machine’s productivity curves for efficient forest operations planning.

Machine learning techniques to estimate mechanised forest cutting productivity

The productivity of wood harvesting operations is one of the main viability indicators of the forestry enterprise, which is directly influenced by land, population, and operational planning characteristics. The variables that affect the productivity of harvesting machines are particularly difficult to measure and have complex relationships, making it challenging to predict the productivity of operations. This study generated a model using machine learning (ML) techniques to estimate harvesting productivity in Eucalyptus plantations in southeastern Brazil. The input variables for modelling harvesting productivity were the average individual tree volumes, wood volume in the stand, cutting age, spacing, operator experience, and the management regime. The database was randomly divided into training (70%) and validation (30%) datasets. Boosted, artificial neural network (ANN), and adaptive network-based fuzzy inference system (ANFIS) techniques were used to fit the model and were evaluated through statistics and graphical analysis of the residues. The configurations selected for training and validation to estimate harvester productivity resulted in correlation coefficient values greater than 0.9, and root-mean-square error (RMSE) percentages less than 12.41, indicating a strong correlation and high accuracy between the estimates and the observed values. The boosted technique yielded the best results, with correlation coefficients of 0.98 and 0.97, and RMSE percentages of 6.15 and 6.65 in training and validation, respectively. The worst performance for estimating harvesting productivity was obtained using the ANFIS technique. ML techniques were efficient in modelling the productivity of mechanised forest cutting with a harvesting model.

Growth of three types of sengon (Paraserianthes spp.) in varying planting spaces in agroforestry system

Abstract. Sopacua F, Wijayanto N, Wirnas D. 2021. Growth of three types of sengon (Paraserianthes spp.) in varying planting spaces in agroforestry system. Biodiversitas 22: 4423-4430. Sengon (Paraserianthes spp.) is a fast-growing tree species that is commonly cultivated in the agroforestry system by communities in Indonesia, mainly on Java Island. Among several types of sengon, Solomon sengon is currently gaining popularity due to the fast growth in height and stem diameter. Nonetheless, the spacing layout of selected sengon types is unclear, including Solomon sengon, which yields more optimal growth. This study aimed to examine the growth of three sengon types (i.e., Solomon F2, Solomon F1, and local Kendal) in three spacing patterns, namely 1.5x1.5m, 3x1.5m, and 3x3m. This research was conducted from October 2019 to January 2020 (three months) in the Cikabayan Forest, Bogor Agricultural University, Bogor, West Java. The parameters of sengon growth observed were plant height, height growth rate, stem diameter, stem diameter growth rate, tree volume, and canopy area. Data analysis was performed using ANOVA and continued with Duncan's. The results showed that all types of sengon had optimal growth in the agroforestry system at various spacings. The growth of Solomon F2 adapted well to denser spacings (1.5x1.5m and 1.5x3m) with the highest averages in plant height, stem diameter, volume, and canopy area of ??10.50 m, 8.65 cm, 0.36 m3, and 5.39 m2. Local Kendal had optimal growth at a wider spacing (3x3m) with the highest average stem diameter, volume, and canopy area of ??8.96 cm, 0.043 m3, and 1063 m2. While Solomon F1 adapted well to the three spacings with the highest average in plant height, the growth rate of plant height, stem diameter, volume, and canopy area of ??10.05 m, 1.54 m, 8.59 cm, 0.042 m2, and 2075.30 m2. In general, it can be concluded that the Solomon F1 sengon can adapt well to narrow distances or wide distances. While Solomon F2 is more recommended to be planted at a narrower distance and Kendal local sengon is more recommended to be planted at a wider distance to get optimal growth.

Estimation of Tree Height and Volume Based on the Produced Hammering Sound Using Deep Learning

Estimation of Tree Height and Volume Based on the Produced Hammering Sound Using Deep Learning

Local Allometric Equations for Estimating Above-Ground Biomass (AGB) of Mangroves (Rhizophora spp. and Avicennia germinans) from the Komo, Mondah and Rio Mouni Estuaries in Gabon

The aboveground biomass (AGB) of Gabonese mangroves is commonly estimated from equations calibrated in other countries, and is generally adapted poorly to the local context. This paper focuses on developing local allometric equations for the AGB estimation and to evaluate their accuracy compared to other general equations. The local equations for Rhizophora spp and Avicennia germinans were performed with tree volume, bark and wood densities, and are used with the diameter as an independent variable. The heights and diameters of 408 trees (314 Rhizophora spp and 94 Avicennia germinans) were measured at 13 sites in Estuaire Province. Sixty-four aliquots were taken from the trunks of both species at the Mondah site. This site has tree diameters ranging from 2 to 127 cm for Avicennia and from 1.4 to 75.8 cm for Rhizophora. The tree height ranges from 0.9 to 24 m for Avicennia, and from 1.1 to 53 m for Rhizophora. Avicennia has an overall trunk density of 0.88 g/cm3 and Rhizophora has 1.17 g/cm3. The coefficient of determination (R2) of the equations are 0.98 for Rhizophora spp, 0.97 for Avicennia germinans, and 0.99 for the general equation. The seven equation display biases that are less than 1% and the root mean square errors vary between 0.073 and 1.68. Compared to other equations generally used, these local equations improve the accuracy of aboveground biomass estimations of Gabonese mangroves.

Моделювання якісної структури стовбурів сосни звичайної за допомогою випадкового процесу

The study highlights methodological aspects of predicting stem volume of merchantable Scots pine trees by grade categories using distribution models of different quality zones along stems. The study is based on empirical data collected in the mature stand during clear-cut harvesting. In total it includes measurements of 245 tree stems for which sequence and lengths of different quality categories were evaluated. A semi-Markov model was applied to characterize a random process of height-relevant co-occurrence and length of merchantable wood, firewood, and residues. The model was determined by the following parameters: 1) input occurrence probabilities of specific grade category in the butt section of tree stems (initial state of the system); 2) distribution matrix of grade categories by lengths; 3) matrix with transition probabilities between grade classes on different stem heights. In this study, we considered the process in which the initial state of the system was associated with merchantable wood which was true for most pine stems. We used beta-function to model lengths of grade categories which parameters were fitted using relative stems height. We also used empirical data to calculate probabilities of transition between merchantable wood, firewood, and residuals along pine stems. The analysis indicates that the length distribution of merchantable wood and firewood depends on the relative height where the grade is observed, and total tree stem height. Thus, we identified four zones where the function of beta-distribution was used to model lengths of each grade category with customized parameters depending on the relative height of their location on tree stem. As a result, we developed a methodology that can be used to simulate datasets with tree stem characteristics, and further to predict the distribution of volume by grade categories depending on their diameters, heights, and merchantability. It is worth noting that our study is focused merely on merchantable pine stems, and one should expect another relationship for stems of different tree species as well as for merchantable pulpwood trees. Given the new standard for merchantable wood classification adopted in Ukraine, the developed methodology is suitable for updating existing tables of distribution of tree stem volumes by wood grade categories.

Morphological Traits of Silver Fir (Abies alba Mill.) in the Bosnian-Herzegovinian Provenance Test

Abstract
 Aim of study: This research aims to determine if there are statistically significant differences among provenances of silver fir (Abies alba Mill.) as one of the most important tree species in Bosnia and Herzegovina, to choose a provenance with the best productivity for further silvicultural activities of silver fir in the country.
 Material and methods: The height and diameter at breast height were measured, and the basal area and volume of silver fir trees were calculated in the silver fir provenance test. The test contains nine provenances from Bosnia and Hezegovina and was launched in 1991, with 5-year-old seedlings (3+2). The data were collected in 2013.
 Main results: Variance analysis for all traits showed statistically significant differences among provenances. Average breast height diameter in 27-year-old plants for all provenances amounted to 11.0 cm, average height 8.4 m, average basal area 0.010342 m2, and average volume 0.070845 m3 
 Highlights: The research results confirmed the existence of variability among silver fir provenances in Bosnia and Herzegovina, considering the morphological indicators. Provenance Bosanski Petrovac showed the highest values of all traits, which implies it is the best provenance for the further activities on seed collecting and producing planting material for afforestation in Bosnia and Herzegovina.

Selection of clones of Eucalyptus camaldulensis (Dehnh.) based on stability for tree volume

A study on the stability of 21 clones of Eucalyptus camaldulensis was carried out in four trials established in the southern part of India viz., Ariyalur and Marakkanam in Tamil Nadu and Karaikal in Puducherry and Tripathi in Andhra Pradesh during 2010. Trials were laid out in Randomised Block Design (RBD) with four replications each with 16 trees. Single tree volume was estimated after measuring tree height, diameter and form factor after seven years of planting. The volume calculated for individual clones present in all four trials were subjected to AMMI stability analysis using CROPSTAT. The average single tree volume of the clones studied varied from 0.035 to 0.11 m3 across locations. The Additive Main Effects and Multiplicative Interaction (AMMI) analysis revealed that the genotypic, environmental and GEI effects were 9.6, 68.6 and 21.8 per cent of the total sum of squares, respectively. Planting site plays a major role when compared to genotype and its interaction with the site. IPCA1 captured 75.43 per cent (p=0.001) followed by IPCA2 that captured 19.29 per cent (p=0.007) of the interaction effects. The AMMI Stability Values (ASV) showed a variation from 0.04 to 1.17. The study identified two clones out of twenty-two to be highly stable across the four locations studied for single tree volume. Key words: Eucalyptus camaldulensis, Genotype by Environment Interaction, Single tree volume, AMMI analysis  

WOOD VOLUMETRY OF Tachigali vulgaris PURE PLANTATIONS IN DIFFERENT PLANTING SPACINGS

The aim of this study was to develop volumetric equations for tachi-branco trees (Tachigali vulgaris L. G. Silva & H. C. Lima), by assessing the effect of initial planting spacing in volume estimates, as well as developing an equation to estimate the equivalent diameter (deq). Data are from an experiment located in north Pará. The experiment was conducted with the randomized blocks design, being three blocks with six treatments each. The most used volumetric models were assessed for two distinct situations: considering each trunk as a tree and using the tree deq as independent variables in the volumetric model. The need for individual equations for initial planting spacing was tested. In addition, an equation for deq estimate was proposed. The use of deq provided more precise and accurate volumetric estimates regarding diameter at breast height. Among the models tested, the Schumacher-Hall model was selected. Through the model identity test, the equation can be used to estimate tree volume of Tachigali vulgaris, regardless of planting spacing. The equivalent diameter can be estimated via equation from minimum and maximum diameters of tree trunks. The maximum percentage differences of volume by hectare obtained with the measurement of all trunks and deq were only 5% without loss in production accuracy per unit of area

Age trends in genetic parameters for growth performance across country-wide provenances of the iconic conifer tree Araucaria angustifolia show strong prospects for systematic breeding and early selection

Understanding the growth patterns of long-lived conifer tree species is important to devise breeding and early selection strategies, predict future biomass productivity and assess adaptive tree fitness for long term conservation efforts. We investigated the genetic variation for growth traits of Araucaria angustifolia, the grandiose renowned “Paraná pine” tree, in a trial involving 122 families across 15 provenances covering the entire natural range of the species in Brazil. Measurements at ages 7, 24, 32, 33 and 35 were used to adjust continuous growth curves based on nonlinear mixed-effect models for all 2158 trees, providing annual estimates for unmeasured ages in the 7-to-35-year interval. Estimated values closely matched observed ones and a reduction of the coefficient of residual variation was observed in the estimated data, possibly due to removal of random error in the observed measurements, making the estimated curves more reliable to predict growth patterns. Genetic variation for growth within provenances was greater than between, with a trend of increasing heritabilities over time for most provenances. Substantial genetic variation found both within and between families could drive efficient early selection at both levels. All provenances included individual trees and families with good potential to be selected for shorter rotations. Growth curves show that trees invest first in height and later in diameter growth. Considerable variation was observed across provenances for the optimal age and optimal tree volume at which annual growth increment peaks, a tipping point that could be used as a predictor of the optimal rotation age and expected tree volume. The data clearly indicate potential for early selection for growth at age 7–10 with an 85% prediction accuracy of growth at age 35. Additionally, growth data indicate potential of shortening harvest age from 30–35 to 15–20 years by selecting the best individuals and families. These results underscore the potential of expanding investments in breeding and plantation forestry of A. angustifolia, which in parallel could contribute to enhancing conservation efforts of this iconic subtropical conifer.

Total and Merchantable Volume Equations for 25 Commercial Tree Species Grown in Canada and the Northeastern United States

Accurate estimates of tree bole volume are fundamental to sustainable forest management. Total inside and outside bark and merchantable volume equations were developed for 25 major commercial tree species grown in natural stands in eastern and central Canada and the northeastern United States. Data used to develop these equations was collected from 9647 trees sampled from natural stands across the study area. The number of trees sampled varied among species. Jack pine (Pinus banksiana Lamb.) had the most observations (1648 trees) and American basswood (Tilia americana) and red oak (Quercus rubra L.) had the fewest (28 trees each). Two mathematically consistent volume equations (dimensionally compatible and combined variable) were fitted to inside and outside bark and merchantable tree volume data from these tree species. The final volume equation was selected based on fit statistics, predictive accuracy, and logical consistency. Its predictive accuracy was compared with a volume equation previously developed by Honer. Both (total and merchantable) volume equations were fitted using a nonlinear mixed-effects modelling approach. However, random effects were significant for total volumes for only four tree species. A weight (power function) was used to address heteroscedasticity in the data. The modified form of the dimensionally compatible volume equation outperformed the combined variable volume equation in terms of fit statistics and predictive accuracy and was selected as the total inside and outside bark and merchantable volume equations for all tree species. This equation produced logically consistent estimates of total and merchantable volumes and was more accurate than that previously developed by Honer to estimate volumes for most of the tree species used in this study. This new equation can be used to estimate total inside and outside bark and merchantable volumes of major commercial tree species in eastern and central Canada and the northeastern United States.

Production Potential and Development of a Decision Support Models for the Plantations of Aleppo Pine in the Oued Laou Watershed in the Moroccan Rif

The present study was carried out in the Oued Laou watershed belonging to the Moroccan Rif. It aims at the elaboration of mathematical tariffs for cubing Aleppo pine, the morphometric and increments study. The data analyzed for this purpose were collected after a preliminary stratification of the forest based on the plantation age. The study of the region’s climate shows that the western sector of the watershed is part of the temperate humid bioclimate, and the eastern sector belongs to the warm variant subhumid. The analysis of the stand-study structure shows that the distribution of the number of stems as a function of the circumference is a distribution close to normal. Cubic rates have been constructed to estimate the volume of trees. The mean annual volume increment of Aleppo pine varies between 3.10 and 4.83 m3/ha/year from one plot to another; this small fluctuation largely reflects the homogeneity of the study area. Aleppo pine has a wide ecological and spatial plasticity: colonization of all substrates, bioclimates ranging from semi-arid to temperate humid. It’s a species that exhibits uniform behavior despite topographic and edaphic variations.

Forest above-ground volume assessments with terrestrial laser scanning: a ground-truth validation experiment in temperate, managed forests.

Quantifying the Earth's forest above-ground biomass (AGB) is indispensable for effective climate action and developing forest policy. Yet, current allometric scaling models (ASMs) to estimate AGB suffer several drawbacks related to model selection and uncertainties about calibration data traceability. Terrestrial laser scanning (TLS) offers a promising non-destructive alternative. Tree volume is reconstructed from TLS point clouds with quantitative structure models (QSMs) and converted to AGB with wood basic density. Earlier studies have found overall TLS-derived forest volume estimates to be accurate, but highlighted problems for reconstructing finer branches. Our objective was to evaluate TLS for estimating tree volumes by comparison with reference volumes and volumes from ASMs. We quantified the woody volume of 65 trees in Belgium (from 77 to 2800 L; Pinus sylvestris, Fagus sylvatica, Larix decidua, and Fraxinus excelsior) with QSMs and destructive reference measurements. We tested a volume expansion factor (VEF) approach by multiplying the solid and merchantable volume from QSMs by literature VEF values. Stem volume was reliably estimated with TLS. Total volume was overestimated by +21 % using original QSMs, by +9 % and -12 % using two sets of VEF-augmented QSMs, and by -7.3 % using best-available ASMs. The most accurate method differed per site, and the prediction errors for each method varied considerably between sites. VEF-augmented QSMs were only slightly better than original QSMs for estimating tree volume for common species in temperate forests. Despite satisfying estimates with ASMs, the model choice was a large source of uncertainty, and species-specific models did not always exist. Therefore, we advocate for further improving tree volume reconstructions with QSMs, especially for fine branches, instead of collecting more ground-truth data to calibrate VEF and allometric models. Promising developments such as improved co-registration and smarter filtering approaches are ongoing to further constrain volumetric errors in TLS-derived estimates.