Total Tree Height Research Articles

Individual models for diameter and height projection with contribution of competition index in Pinus taeda L. stands

The aim if this work was to assess and propose projection models for diameter at breast height and total height of individual pine trees and the contribution of competition indexes in these models. Data was obtained from 1056 permanent sampling units of non-thinned Pinus taeda L. stands located in the Telêmaco Borba region, Paraná, Brazil, with ages between 3.4 and 19.5 years. In order to project the diameter and total height of the trees, linear models were tested according to the variable in the current age, the projection age in the future, the basal area, and the site index, as well as their transformations. The Spearman correlation was obtained between competition indexes and dendrometric and stand variables, with the GH (Glover and Hool), LO (Lorimer) and ST (Stage) indexes being selected. These indexes were assessed as independent variables in the models, whose contributions were verified through the “F ci ” test on the incremental contribution. The models were assessed through the adjusted coefficient of determination, standard error of the estimate, and boxplots of residuals. The models provided precise and bias-free projections. The competition indexes statistically contributed to diameter and total height projection according to the “F ci ” test, increasing the precision of projected values for the majority of models tested. The indexes with major contributions to individual tree modelling for diameter and total height projection of Pinus taeda were Glover and Hool (GH) and Lorimer (LO), respectively.

Assessment on Carbon Stock of Natural and Plantation Forest in Setema District, Jimma Zone, South West Ethiopia

A Carbon Stock of Natural and Plantation Forest in Setema District, Jimma, South West Ethiopia was conducted. Carbon (C) densities of the biomass and soil (0–40 cm) in the natural forest and plantations of E.globulus and C. lusitanica in the Setema forest were determined and compared. In the stratum or forest stand, sample plots of 20 m x 20 m,(square) were randomly laid to measure the biomass of woody plants, a total of 90 (30 in each stratum) sample plots were taken for C stock inventory. Biomass C densities were estimated from total tree height, breast height diameter and wood density using allometric functions developed for tropical species and an assumed C content of 50%. Belowground biomass C densities were estimated using root: shoot biomass ratios. Soil organic C (SOC) densities were calculated from measured organic carbon contents (0–20 and 20–40 cm layers) and modeled bulk density values. Mean total biomass C densities for natural forest were greater than those of the plantations, and mean total SOC densities for plantations were greater than those of the natural forest, and the difference was significant (p < 0.05) in the cases of plantation and natural forest, but not significant in SOC in the case of E. globulus plantation species. Natural forests can store more total C stocks than plantations of exotic species, but the difference between natural forest and plantation of exotic was depended on plantation species. Therefore, species selection is vital when establishing tree plantations with the aim of the restoration of degraded soils and biomass carbon stocks. Conservation of the natural forest will have an imperative implication to the total C density and ensuring its viability. Keywords: biomass; carbon stocks ; C. lusitanica; E. globulus; natural forest ; soil carbon stocks DOI: 10.7176/JETP/12-1-01 Publication date: January 31 st 2022

Phenotypic divergence among half-sib progenies of African mahogany.

Divergence studies are essential for the conservation of genetic resources and guidance in genetic improvement programs. This study aimed to assess the phenotypic dispersion of half-sib progenies using Gower's algorithm and the non-metric multidimensional scaling analysis based on qualitative and quantitative traits. Twenty-two half-sib progenies of African mahogany (Khaya senegalensis) were evaluated in a randomized block design with 22 treatments (progenies/origin), with 30 replications and one plant per plot, totaling 660 plants. The total tree height (cm), diameter at soil level (cm), chlorophyll A and B, presence of bifurcation, presence of lateral branches, stem tortuosity, and the phytosanitary and nutritional status according to a rating scale were evaluated. Data analysis was performed at the progeny mean level for the quantitative traits and the modal value was used for the qualitative traits. The technique used presented the distance between the progenies of K. senegalensis in a graphical form. The dispersion of the progenies in the graph is indicative that there is phenotypic variation in the progeny test, allowing to select individuals with characteristics of interest to improve mahogany for Piauí. Gower's algorithm applied to mixed data and non-metric multidimensional scaling are efficient methods to describe phenotypic similarities between progenies.

SELEKSI POHON PLUS PADA UJI KETURUNAN Shorea leprosulaDI KALIMANTAN TENGAH

he progeny trial of Shorea leprosula was established in Central Kalimantan under the IUPHHK-HA management of PT. Erna Djuliawati by planting 30 families to examine the genetic superiority of trees asplywood raw material. The trial was laid-out using 8 blocks, 4 tree-plots and a spacing of 6 x 3 m. The aim of the study was to practice the plus trees selection in the progeny trial. The study was conducted using a survey method on phenotypically superior trees based on a diameter at breast height (dbh) baseline of ≥ 30 cm. The data collected and analyzed for the plus trees and comparison trees were total tree height (m), dbh (cm), and dbh increment (cm/yr). The results of the initial selection showed that 110 trees from 29 families were selected as candidate plus trees in the progeny trial. Futhermore, the honest significant difference test (BNJ) and scoring showed that there were 15 trees from 9 families that can be designated as plus trees

Kentsel yeşil alanlardaki ekosistem servislerinin hesaplanması: Eugene Pioneer Mezarlığı, Eugene, Oregon (ABD)

Objective: The objective of this study was to quantify four regulating ecosystem services; carbon sequestration and storage, avoided run-off, air pollution removal by trees and oxygen production in the Eugene Pioneer Cemetery, OR (USA).
 Material and Methods: For data preparation the field data of trees was collected on paper data sheets. Collected data in the field were land-use type, tree species, diameters of breast height-DBH (cm), total tree height (m), live crown height (m), crown base height (m), and crown percent missing. In data analysis I-Tree Eco model version 6 developed by the U.S. Forest Service, Northern Research Station was used.
 Results: The gross sequestration of the cemetery trees is about 7,136 metric tons of carbon per year. Trees in the cemetery were estimated to store 1,610 metric tons of carbon. The trees and shrubs of the cemetery help to avoid run-off by an estimated 452 cubic meters a year. It was estimated that trees remove 143,9 kilograms of air pollutions. Trees in the cemetery were estimated to produce 19,03 metric tons of oxygen per year.
 Conclusion: This study recommends large green areas (large permeable surfaces) and trees with large crowns in the planting design as a better solution for regulating ecosystem services.

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<sub>1.7</sub> [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.

Variable selection for estimating individual tree height using genetic algorithm and random forest

Tree height is an important trait in forest science and is highly associated with the site quality from which the trees are measured. However, other factors, such as competition and species interaction, may yield better estimates for individual tree height when taken into account, but these variables have so far been challenging in model fitting. We propose a hybrid approach using genetic algorithms for variables selection and a machine learning algorithm (random forest) for fitting models of individual tree heights. We compare our proposed hybrid method with a mixed-effects model and random forest model using a dataset of 5,608 trees and 189 environmental variables (forest inventory-based variables, soil, topographic, climate, spectral, and geographic) from sites in southeastern Brazil. The tree height models were evaluated using the coefficient of determination, absolute bias, and root means square error (RMSE) based on the validation of dataset performance. The optimal set of variables of the proposed method include the ratio of diameter at breast height to quadratic mean diameter, distance independent competition index, dominant height, the soil silt and boron content. Our findings showed that the proposed hybrid method achieved an accuracy comparable with other methodologies in estimating the total height of the individual trees, and such a modelling approach could have broader applications in forestry and ecological science where a studied response trait has a large number of potential explanatory variables.

General above-stump volume and biomass functions for Pinus radiata, Eucalyptus globulus and Eucalyptus nitens

Accurate estimations of stem volume and tree component biomass are of paramount importance for the study and management of forests. In Chile, the most important commercial tree species are Pinus radiata, Eucalyptus globulus and Eucalyptus nitens, which are successfully planted in other parts of the world. Available individual-tree allometric models are typically local models which do not include age or stand scale covariates and rely solely on stem diameter outside bark at breast height (DBH) and, in some cases, total tree height (H). We used data from 1571 trees across the distribution of the three species in Chile to develop general individual-tree equations for stem volume inside and outside bark, and biomass components (dead branch, live branch, foliage, bark and stem wood inside and outside bark). Our models include DBH or DBH and H as predicting variables, as well as stand-level variables like age, basal area and stand density. General allometric models that include stand-level variables have not been previously reported for P. radiata, E. globulus and E. nitens. Given the broad area of inference in our data, the models are applicable over a large geographical area and a variety of stand ages and characteristics and can be used to support management decisions or integrated in stand-level productivity models to enhance the accuracy and precision of model outputs. The collective effort behind this study is a remarkable example of cooperation across researchers and practitioners in order to address complex questions in a transdisciplinary world.

The effect of slope aspect on growth attributes of Shorea leprosula Miq. in a rehabilitated hilly landscape

Shorea leprosula Miq. is one of Indonesia’s native red meranti species with a higher growth increment than other meranti species. Gunung Dahu Research Forest is a rehabilitated hilly landscape planted with various species of Dipterocarpaceae. This study aims to analyze the growth performance of 24 years old of S. leprosula stands in various slope classes of line planting technique at Gunung Dahu Research Forest. Growth analysis of S. leprosula was carried out by measuring the stem diameter, total tree height, basal area, diameter increment, height increment, and Leaf Area Index (LAI). Slopes were divided into three classes: mild/gentle (15-25%), steep (>25-45%) and very steep (>45%). The results showed that slope class significantly affected height growth and the canopy cover of S. leprosula, but it did not affect the diameter growth. A very steep slope provided the best growth to diameter (average diameter 30.07 cm; MAI 1.25 cm/year) and height (average height 23.7 m; MAI 0.99 m year−1). Furthermore, a linear relationship was formed between the crown cover and slope class in which denser crowns were established in response to a steeper slope (LAI 3.4). Thus, planting S. leprosula as a rehabilitation effort in steep slope landscape delivers beneficial as they showed better growth performance.

Bark thickness models for oak forests being converted from coppice to high forests in Northwestern Turkey.

The research was carried out in the coppice-originated pure oak stands that are being converted to high forests in northwest Turkey. The main goal of the research was to determine the bark thickness (BT) based on tree variables, such as tree diameter at breast height (DBH), total tree height (H), crown diameter (CD), and age (AGE) of the stem sections taken from a total of 350 trees that were destructively sampled from different sites, different oak species (Quercus petraea, Quercus frainetto, Quercus cerris), and different development stages. Models were developed with stepwise multiple regression analysis to predict BT based on the variables.For all oak species, all models obtained by stepwise multiple regression analysis were found to be significant at p = 0.001 level. In Quercus petraea, only the DBH-dependent model explained the variation in BT at a rate of 73%, estimating with an absolute error rate of 21%. The fit statistics of the models (based on DBH and DBH-H explanatory variables) obtained for Quercus frainetto are very close to each other, and they explained the variation in BT at a rate of 69% and estimated with an error rate of 26%. Models (based on DBH and DBH-H explanatory variables) explain the variation in BT in Turkey oak at a rate of 91%, indicating species-specific results. The models based on only DBH can be used with high accuracy to estimate BT.

Land use impacts on Boswellia dalzielii Hutch. an African frankincense tree in Burkina Faso

Boswellia dalzielii Hutch., an African frankincense tree, is a socio-economically important aromatic and medicinal tree. It is currently threatened by uncontrolled exploitation, and therefore requires action to ensure its sustainable management. This study assessed the population structure and regeneration of its natural stands across three land use types in Burkina Faso: woodlands, fallows and farmlands. Sixty, fifty and fifty 50 m × 20 m plots were established respectively in woodlands, fallows and farmlands. All the plots were surveyed for adult tree (dbh ≥ 5 cm) density, dbh, total height and health conditions. Data on regeneration density (dbh < 5 cm), source (generative, stem shoots, suckers), total height and collar diameter were also collected. The results show similar total tree heights (7.0 m-9.0 m) but significantly (p < 0.05) smaller tree dbh in woodlands (mean ± SD: 20.5 ± 0.49 cm) and fallows (29.3 ± 0.64 cm) than in farmlands (32.8 ± 0.15 cm). Adult tree density (trees/ha) was 1.3 and 2.7 times higher in woodlands (82.37 ± 6.57) than in fallows (62.00 ± 3.98) and farmlands (30.02 ± 1.63), respectively. The density of regeneration in woodlands was 28 and 6 times higher than in fallows and farmlands, respectively. The majority (> 50%) of regenerating plants were suckers and no seedling regeneration was found in farmlands. The distribution of trees in diameter classes was J-shaped in woodlands, bell-shaped in farmlands and positive asymmetric in fallows, indicating recruitment bottlenecks. We found that 80.18% of individuals encountered were unhealthy. Intensive debarking and cutting were the main threats to the species and no conservation strategy was in place in the study region. We suggest measures to reduce intensive debarking and cutting, which should contribute to better management of the species.

PRUNING HEIGHT IN EUCALYPTUS CLONES ESTABLISHED IN AN AGROSILVOPASTORAL SYSTEM

The aim of the current study is to evaluate the effect of pruning intensity on the diameter and height of three eucalyptus clones established in an agrosilvopastoral system. The study followed a completely randomized block design in a split-plot arrangement, with repeated measures in time. Plots were represented by three eucalyptus clones (VE01, VE07 and VE06) and sub-plots were represented by three pruning heights (0%, 25% and 50% of total tree height), and the repeated measures were months. Trees were pruned at 18 and 24 months after planting, by keeping the same proportion of pruning Heights. Diameter at Breast Height (DBH) and total Tree Height (Ht) were measured every six months since the first pruning; periodic increase in both variables was calculated. Clone VE01 recorded DBH and Ht values lower than the ones recorded for VE07 and VE06. Pruning treatments did not show significant effects on tree growth.

Genetic parameters in a clonal test of Tectona grandis in Mato Grosso, Brazil

Teak (Tectona grandis) is a high-value timber species in tropical regions. In Brazil, although teak has a high productivity, there are few studies related to its genetic improvement. This work aimed to estimate genetic parameters and evaluate potential gains of selection in a clonal test of teak installed in the state of Mato Grosso, Brazil. The experimente is in a randomized block design, with five replications, 3x3 m spacing, 22 treatments, and plots with six individuals. At five years, the genotypes were evaluated for survival (S), tree total height (H) and girth at breast height (GBH). There was significance and feasibility of selection for S and GBH. For H, the result was not significant, indicating few gains with the selection. The genetic parameters of clonal mean heritabilities and accuracy were of moderate magnitude for S and GBH and low for H. To best of our knowledge, this is the first work that estimates genetic parameters in a clonal teak test in the field in Brazil.

Canopy structure metrics governing stemflow funnelling differ between leafed and leafless states: Insights from a large‐scale rainfall simulator

AbstractAn increasing number of studies have examined the effects of various biotic and abiotic factors on stemflow production. Of those that have ascribed the importance of canopy structure to stemflow production, there has been a bias towards field studies. Coupling Bayesian inference with the NIED (National Research Institute for Earth Science and Disaster Resilience, Tsukuba, Japan) large‐scale rainfall simulator, this study leveraged a unique opportunity to control rainfall amounts and intensities to pinpoint the canopy structural metrics that differentially influence stemflow funnelling ratios for three common tree species between leafed and leafless canopy states. For the first time, we examined whether canopy structure metrics exert a static control on stemflow funnelling ratios or whether different elements of canopy structure are more or less important under leafed or leafless states, thereby allowing us to determine if tacit assumptions about the static influence of canopy structure on stemflow production (and funnelling) are valid (or not). Rainfall simulations were conducted at 15, 20, 30, 40, 50, and 100 mm h−1 under both leafed and leafless tree conditions (12 simulations in total) to detect any differential effects on the presence or absence of foliage on stemflow funnelling ratios. For leafed conditions, the highest percentages of best‐fitting models (ΔDIC ≤2) indicated that stemflow funnelling ratios were mainly controlled by total dry aboveground biomass (Ball), diameter at breast height (DBH), total dry foliar biomass (Bf), tree height (H), and woody to foliar dry biomass ratio (BR). Whilst for the leafless state, the highest percentages of best‐fitting models (ΔDIC ≤2) indicated that total dry branch biomass (Bbr) was relatively dominant as was the interaction effects between crown projection area and species (CPA:species). These results compel us to reject any assumption of a static effect of different elements of canopy structure on stemflow funnelling.

Assessing fruit production and harvesting effects on Carapa procera DC. population, a threatened oil tree in Burkina Faso, West Africa

The exploitation of non-timber forest products contributes considerably to local livelihoods for subsistence in developing countries. The study aims to assess the structure and fruit production of C. procera natural populations in harvesting and non-harvesting sites and to compare the structure characteristics and fruits yields of the two sites.The study was carried out in Burkina Faso on both, harvesting and non-harvesting sites. Eighty fruits bearing trees (40 per site) were sampled, from each, all the fruits were counted. Dendrometric parameters were measured in 80 plots of 1000 m². In each plot, diameter at breast height (dbh) and total height of trees were measured. Density, basal area, mean diameter and height were computed for each site. Analyses of variance were performed to test differences between sites based on measured variables. Weibull theoretical model was used on size class distribution to analyze trees structure in both sites.The results showed that the production of fruits reaches a mean of 6462.73 ± 4237.51 fruits/ha and 9103.44 ± 7631.88 fruits/ha, respectively in non-harvesting and harvesting site. Significant differences (p < 0.05) were found for tree densities, basal area and tree height between sites with highest values in the harvesting site. The size class distribution of trees showed in both sites the existing of potential regeneration with the dominance of young trees (1 < c < 2) with some survival difficulties during the growth stages. C. procera populations exhibit a high potential of fruit production and natural regeneration but are influenced by pressures impact.

Additive biomass model for Heritiera fomes (Buch.-Hum.) in the Sundarbans Reserved Forest, Bangladesh

Mangroves are recognised as an important carbon sequester and therefore demand accurate biomass and carbon stock estimations. This study aimed to develop additive biomass models for Heritiera fomes, the most dominant tree species of the Sundarbans Reserved Forest in Bangladesh. Using a non-destructive method, 219 small branches (diameter < 7 cm) were harvested from 97 individual trees to develop biomass models for leaves and smaller branches. The biomass of bigger branches (diameter > 7 cm) and stem was calculated from the volume and mean wood density value after debarking while the biomass of all other components was derived from the determined fresh to oven dry weight conversion ratio. Finally, the biomass of one individual tree was calculated by adding the biomass of trimmed and untrimmed leaves, small and large branches, foliage and stem. An independent data set was used to validate the best-fit model. A component-wise (leaves, branches, bark and stem) biomass model was developed by recovering subsequent cross-component correlations which were then aggregated using the weighted Gaussian maximum likelihood estimation method. Among the components model, D (diameter at breast height) alone performed best for leaves and branches while the product of D and H (total tree height) proved the better results for stem and bark. Our best-fit model (Biomass = 0.0389D 2.3773 H 0.4178 + 0.0492D 2.3027 + 0.0112D 1.1144 H 1.4572 + 0.0306D 1.8507) showed the highest model efficiency with the lowest AIC, RMSE%, MAE, and MPE values. The efficiency of our non-destructive model has shown that it is as effective as other widely used pan-tropical models. Our built models can therefore be used for accurate estimation of biomass and carbon stock in H. fomes of the Sundarbans Reserved Forest, Bangladesh.

Small-tree volume equations for subtropical hardwood plantation species

ABSTRACT Estimation of stem volume is needed to determine timber yield and forest carbon, but equations to estimate volume from easily assessed inventory measures are lacking for hardwood plantation species in the subtropics. We assessed the merits of three volume equations that combine measurements of tree diameter at breast height (DBH) and total tree height for five hardwood plantation taxa (Corymbia citriodora subsp. variegata, Corymbia hybrids, Eucalyptus cloeziana, E. longirostrata and E. dunnii). Goodness-of-fit statistics indicated that model 1 (comprehensive combined variable equation) and model 2 (the Schumacher and Hall equation) fitted the data well (e.g. adjusted R 2 > 98). Analysis of bias in different diameter classes indicated that these models did not show any systematic bias patterns with tree size. Model 3 (combined variable volume equation) is the least desirable as it showed evidence of overestimation of volume for larger trees in some taxa. Models 1 and 2 provide a useful initial set of volume equations for five potentially important hardwood plantation species in subtropical Queensland. These equations are based on stems with a DBH range of 5−30 cm and hence there is a need to collect data for larger stems (>30 cm DBH) as existing plantations mature.

Characterization of Diameter Distribution and Prediction of Weibull Parameters Equation for Plantation-grown Eucalyptus Species

Aim: To characterization of the diameter distribution and prediction of Weibull parameters of a plantation-grown Eucalyptus species.&#x0D; Study design: Stratified sampling method was adopted, in which the plantation was stratified into four age series.&#x0D; Place and duration of study: Afaka Forest Reserve, one month.&#x0D; Methodology: Fifty (50) sample plots of 20 x 20 m were laid across the age series. In each of the plot, all the trees were counted and data of variable of interest was collected and processed. A separate Weibull distribution is fitted to the diameter at breast height (dbh) frequency data from each of the plot for the estimation of Weibull parameters (location, scale and shape). The data set obtained from the Weibull parameter estimate was then used to develop regression equations with the stand variables. Coefficient of Determination (R2) and Root Mean Square Error (RMSE) was used as goodness of fit test.&#x0D; Results: The result on the stand characteristics revealed that, the mean diameter at breast height (dbh) ranges between 13.4 – 18.2 cm across the four stands. This indicates that the species are still of pole sizes. The average site productivity of the species ranges between 24.0 m to 37 m at an index of 25 years. The mean Basal area varies between 14.13 to 26.85 m2 per ha, while the average tree total height ranges between 24.6 to 28.2 m across the four species. The result on diameter class distribution shows that most of the species fell within dbh class of 11 -20 cm class except E. cloeziana in which the highest frequency fell into 16 – 20cm dbh class. Best equation were selected for each of the Weibull parameters (α, β, ) per species based on fit statistics. The formation of straight line pattern from the plotted normal probability plots indicates the adequacy of the selected models for predicting Weibull parameters. A fluctuation pattern exists between the Weibull parameters and the stand characteristics. this may be due to variation in climatic factor, most especially fluctuations in rainfall pattern in the area at that particular period.&#x0D; Conclusion: The ease of fit and high value of coefficient of determination of the models in this study has re-affirmed the use of Weibull parameter in prediction of stand characteristics as been suggested by many authors in the literature.

Conventional and additive models for estimating the biomass, carbon and nutrient stock in individual Shorea robusta Gaertn. f. tree of the Sal forests of Bangladesh

Accurate tree biomass estimation is critical and crucial for calculating carbon stocking as well as for studying climate change, forest health, productivity, nutrient cycling and budget etc. A total of 50 individuals of Shorea robusta Gaertn. f. were harvested to assess the biomass of tree components (leaf, branch, bark and stem). Carbon and nutrients (N, P and K) content in the tree components were also measured. This study adopted component biomass models with cross-validation technique. Additive biomass models were developed following the modified Gaussian maximum likelihood aggregated approach using open source software R (version 4.0.1). Component and additive biomass model used D (Diameter at Breast Height) as a sole predictor performed satisfactorily, the inclusion of total tree height (H) in Da*Hb form showed its supremacy over all the models. The best fitted additive model (AGB = 0.002056*D2.923998*H−0.69278 + 0.00848*D2.3896*H0.29648 + 0.04224*D2.06986*H0.65549 + 0.00552*D2.06723*H0.70536) and conventional model (Ln (AGB) = -2.7977 + 2.1829*ln(D) + 0.5073*ln(H)) took the lowest AIC, MPE and MAE and the highest model efficiency values. The derived species-specific additive and non-additive model showed its superiority over the frequently used pan-tropical models and suggested using this model for estimating aboveground biomass of S. robusta in Bangladesh.

Impact of training on different observers in forest inventory

Observers with different experience levels are involved in the measurement of large number of sample plots during forest inventories, particularly in national forest inventories. However, limited information exist on the quality of data produced by different observers in forest inventory after certain levels of training. This study tries to evaluate the measurement error in forest inventory associated with observers' experience after initial and field-based training for measuring the most fundamental variables- DBH (cm), total tree height (m), and horizontal distance (m) together with bearing (azimuth) to tree from the plot-centre. On completing the second level of training, the mean of the differences in DBH measurement decreased for both the ‘experienced’ and ‘inexperienced’ groups. The mean of the differences in height measurement in the case of the experienced observers was very low as compared to the inexperienced ones. However, the mean of the differences in azimuth measurement showed that the experienced groups were overestimating by at least 1 degree. There was no trend in deviation of measurement for all four variables regardless of tree size. The decrease in the mean and error of differences in measurements after second training showed that field-based training with supervision and training on the use of instruments at laboratories were required for inexperienced surveyors whereas update in working and measurement procedure would be sufficient for the experienced ones.