Total Tree Height Research Articles

Accuracy and Precision in Urban Forestry Tools for Estimating Total Tree Height

Background: Urban tree inventories are fundamental to the monitoring and management of urban forests. Various handheld tools and methods exist to conduct tree mensuration, ranging from the simple stick method to laser rangefinders. This study examines the accuracy and precision of the stick method, clinometer, and laser rangefinder, and introduces tree type (i.e., conifer versus broadleaf) comparisons of accuracy and precision. Methods: Measurements were taken from 127 trees comprised of 85 (66.9%) broadleaf and 42 (33.1%) coniferous trees. Trees were distributed across 4 urban land use types: park, golf course, street, and trail system. A drone-mounted measurement tape was used to determine true height. Results: Measured heights ranged from 4.67 m to 25.71 m (x̄ = 13.19 m). Measurements from the stick method yielded statistically similar results to both the rangefinder and clinometer methods. The methods had a Cronbach’s Alpha of 0.991 (N = 3). Accuracy was highest for the rangefinder and lowest for the stick method. Precision was greatest between the rangefinder and the clinometer. Root-meansquare error (RMSE) and percent error were highest for the stick method and broadleaf trees for all 3 measurement methods. Conclusions: The findings indicate greater accuracy and precision across all tools when measuring conifers. The rangefinder was similar in accuracy to the clinometer, with notable changes in accuracy when using the stick method.

Vegetative Characteristics of Three Apricot Cultivars Grafted on Six Different Rootstocks

The continuous innovation in the aspect of apricot cultivars and rootstocks requires comparative trials, which can be evaluated by precise and repeated measurements. An experiment is established, initiated from the recent trends for the Central-European region. Our aim was to evaluate the characteristics of the observed rootstock-scion combinations during their non-bearing period under irrigated conditions. ‘Montclar’, ‘Myrobalan 29C’, ‘Wavit’, ‘Rootpac R’ and ‘Fehér besztercei’ were used as rootstock, in addition to the apricot selected seedling. Evaluation of rootstocks was carried out in combination with ‘Bergarouge’, ‘LilyCot’, and the traditional Hungarian cultivar called ‘Gönci Magyar kajszi’. The control combination was ‘Gönci Magyar kajszi’ grafted on apricot selected seedling. The experiment was established in spring of 2018 with 3 × 5 m spacing. The results showed strong influence of rootstock on the vigor of grafted scions. The regression relationships between the total height of trees and the canopy diameter, and the shoot length were linear. Furthermore, relationships between the trunk cross-section area and the total height of trees, the canopy diameters, the shoot lengths, as well as the canopy volume were positive and non-linear.

Small-Scale Analysis of Characteristics of the Wildland–Urban Interface Area of Thessaloniki, Northern Greece

In the past few years, the continuous expansion of urban development has created mixed forested, agricultural, and urban areas. These areas are called the wildland–urban interface (WUI), and they are characterized by increased human activities and land-use conversion, and they usually contribute to a high risk of wildfire occurrence. In the case of the peri-urban areas of Thessaloniki city, an effort was made to map, classify, and describe this wildland–urban interface, using Sentinel-2 satellite images of the area and very large scale orthophotos (VLSO) for the human settlements. Object-based image analysis (OBIA) was applied to classify landcover, combined with analysis of field data. The results showed that the WUI area in the city of Thessaloniki appears to the north and east of the city and covers an area of 2203.98 ha. The main characteristics affected by the ecological conditions of this area are the building (or human infrastructure) density, type, and the structure of forest vegetation. Human population pressure was found to be greatly differentiated between WUI areas belonging to different municipalities, the most affected was the municipality of Thessaloniki. A set of fire prevention silvicultural treatments are suggested for mitigating the fire danger in the area, accompanied by appropriate human awareness actions and the involvement of the local society. These measures include the reduction in crown bulk density and increase in crown base height through pruning (at least to 1/3 of total tree height), and low thinning, aiming to ensure that tree crowns of mature Pinus brutia trees are not in contact with one another. Both in the young P. brutia forest and the evergreen vegetation areas, thinning, pruning, and vegetation clearing is recommended adjusted according to each ecosystem.

Characterizing height-diameter relationships for Caribbean trees using mixed-effects random forest algorithm

Accurately characterizing the relationships between tree height and diameter at breast height (DBH) is vital to quantify productivity and predict tree growth for forest management. This study makes use of data from forest inventories in the Caribbean islands of Puerto Rico, Trinidad and the U.S. Virgin Islands to compare the efficacy of parametric mixed models, random forest and mixed-effects random forest algorithms (MERF) for modeling tree species-specific H-D relationships. MERF as a semi-parametric approach is advantageous for handling high dimensional and complex datasets using the random forest algorithm, as well as to provide species-specific predictions with random effects in the mixed model framework. A total of 37,124 observations used in analyses were collected from 645 permanent sample plots across three Caribbean islands, including 309 species in Puerto Rico, 121 species in the U.S. Virgin Islands and 34 species in Trinidad.Results showed that MERF can be used to reliably predict total tree height for diverse species, which produced more accurate predictions than the other two models. In addition to DBH, competition index was found to be the most important variable among all other stand and environmental variables in all islands. Adding climate-related variables can improve the prediction accuracy of total tree height in parametric mixed models, especially when sample size is small. Precipitation variables were selected most often, confirming the overall importance of precipitation to forest height. The results of this work will not only provide species-specific H-D relationship models for Caribbean trees, but also advance knowledge in modeling H-D relationships with broad application for mixed-species forests.

Identification of Apis dorsata Bee Nesting Plants in Natural Forest of Lalang Village Sanggau Regency

Apis dorsata is known as a forest bee that is very productive in producing honey. These bees can make nest combs only by relying on tree branches or branches. This study aims to identify the type of plant where Apis dorsata nests in the natural forest of Lalang Village, Meliau District, Sanggau Regency. This research was conducted using a survey method through interviews with respondents and site surveys to identify and measure tree height, tree diameter, and branch-free stems of the plant species where Apis dorsata bees nest. The data obtained is further analyzed and the results are presented in the form of tables and graphs. The results of our study found that there were 16 species of plants belonging to 8 families as Apis dorsata beehives. The family and names of these plants are Dipterocarpaceae (Anisoptera marginata, Shorea laevis, Dryobalanops lavevis, Dryobalanops beccarii, Anisoptera megistocarpa, Shorea parvifolia, Shorea leprosula), Fabaceae (Inga sp, Millettia borneensis, Koompassia sp, Koompassia excelsa), Apocaceae (Alstonia pneumatophora), Datiscaceae (Octomeles sumatrana), Lauraceae (Litsea sp), Malvaceae (Pterocymbium tubulatum), and Moraceae (Artocarpus sp). The dominant family is Dipterocarpaceae. The total height of Apis dorsata honeycomb trees is the most dominant (75%) in Lalang Village ranging from ±65-90 m, 10 species of sympodial branching (62.5%), and 68.75% of the trunk diameter found ranged from 50-159 cm.

Variation of tree crown height effects on flow behavior around finite vegetation

Finite-length vegetation has been previously studied for its ability to provide resistance against the tsunami by using just the trunk section of the tree stand structures. However, investigating the resilience of the vegetation while taking the crown section into account is yet unknown. Using a limited emergent vegetation model (EVM), this research examined the impact of changing the tree crown heights on the flow structure behavior between the vegetation and its surrounding gap region. Experimental variables included such as tree crown height ( in which is the crown height from the ground surface and is the total tree height), vegetation width to length ratio (W/L), and the initial Froude number condition , which ranged between 0.67 and 0.76. The outcomes demonstrated that, when the vegetation width to length ratio was small, the crown height ratio ( < 0.3) significantly reduced the velocity and fluid force behind the vegetation patch region as compared to no crown (NC) and highest crown height ratio ( > 0.3). On the other hand, the effect of crown cases in the small vegetation patch did not increase the velocity and fluid force in the gap region in comparison with NC. Whereas the increased width of the vegetation patch along with the lower crown height ratio ( < 0.4) further decreased the velocity and fluid force behind the vegetation patch but the increased width of the vegetation patch in combination with the lower crown height ratio increased the velocity and fluid force in the surrounding gap region as compared to its NC case.

3D point cloud fusion from UAV and TLS to assess temperate managed forest structures

Light detection and ranging (LiDAR) technology has become one of the most dominant acquisition methods for modeling forest attributes, such as very accurate tree structure information, which is necessary for qualitative forest management and research activities. In this study, we evaluated the efficacy of standalone unmanned aerial vehicle-laser scanning (UAV-LS) and terrestrial laser scanning (TLS) data to accurately estimate forest tree metrics under differing management types. Furthermore, we combined the UAV-LS and TLS data to test whether fusion can improve the mapping of the three-dimensional (3D) structure of individual trees to favor accurate estimates of tree metrics. We initially calculated the percentage of point density per square meter aboveground in each height class at intervals of 1 m for the UAV-LS, TLS, and fusion datasets. This helped illustrate the vertical point density distribution that reflects the structural complexity between broadleaf and conifer trees. We then used tree-level point clouds to assess several tree metrics, such as diameter at breast height (DBH), total tree height (HT), crown projection area (PAC), crown width (WC), crown length (LC), 3D crown surface (SC), and 3D crown volume (VC). Our results indicated that LiDAR fusion can increase the estimation accuracy of DBH and HT, especially in broadleaves (97.8% accuracy). In addition, fusion significantly reshaped the modeled crown structures in both plots, which led to improved estimates for all crown metrics. The results show empirical evidence that LiDAR fusion can also have a determining role in supporting ecosystem services. For example, detailed 3D mapping of tree crowns can be used to assess the mitigation of rainfall`s kinetic energy by tree crowns concerning soil erosion and sedimentation near habitable zones.

Estimating the attributes of urban trees using terrestrial photogrammetry.

Today, different methods are used to measure two-dimensional (2D) and three-dimensional (3D) attributes of trees. One of these methods, which is considered in recent years is using point clouds and a 3D model extracted from terrestrial photogrammetry (TP). This study aims to estimate the 2D and 3D attributes of urban trees at three levels of seedlings, single trees and sample plot using TP. Structure-from-Motion with Multi-View Stereo-photogrammetry (SfM-MVS) method was used to derive the point clouds and the 3D model. Comparing estimated values of diameter at the middle of trunk of seedlings and diameter at breast height (DBH) of trees, using TP with measured values showed that the values of RMSE% were < 2% at three levels of seedlings, single trees and sample plot. Furthermore, validation of the estimated values of total height and crown height attributes of seedlings and trees at three levels showed that the RMSE% did not exceed 4% and 5%, respectively. Considering the overlap of tree crowns with each other in the sample plot, the average diameter of the crown attribute was estimated only in seedlings and single tree levels with RMSE% = 6.51% and 9.34%, respectively. The validation of estimated values of stem volume of seedlings and trees at three levels showed that the lowest errors were returned from trees within a sample plot with RMSE% = 14.37%, whereas the highest rates of errors were achieved for seedlings with RMSE% = 20.99%. As an alternative to approaches such as employing laser scanners, this method is quick, inexpensive, non-destructive, and does not need specialized equipment.

Comparison of Modeling Approaches for the Height–diameter Relationship: An Example with Planted Mongolian Pine (Pinus sylvestris var. mongolica) Trees in Northeast China

In the process of modeling height–diameter models for Mongolian pine (Pinus sylvestris var. mongolica), the fitting abilities of six models were compared: (1) a basic model with only diameter at breast height (D) as a predictor (BM); (2) a plot-level basic mixed-effects model (BMM); (3) quantile regression with nine quantiles based on BM (BQR); (4) a generalized model with stand or competition covariates (GM); (5) a plot-level generalized mixed-effects model (GMM); and (6) quantile regression with nine quantiles based on GM (GQR). The prediction bias of the developed models was assessed in cases of total tree height (H) predictions with calibration or without calibration. The results showed that extending the Chapman–Richards function with the dominant height and relative size of individual trees improved the prediction accuracy. Prediction accuracy was improved significantly when H predictions were calibrated for all models, among which GMM performed best because random effect calibration provided the lowest prediction bias. When at least 8% of the trees were selected from a new plot, relatively accurate and low-cost prediction results were obtained by all models. When predicting the H values of Mongolian pine for a new stand, GMM and BMM were preferable if there were available height measurements for calibration; otherwise, GQR was the best choice.

Molecular Phylogeny of Selected Kenyan Eucalyptus Species Inferred from MatK, rbcL and TrnL-F Genes and Their Suitability for Power Transmission Poles

Genus Eucalyptus belongs to the family Myrtaceae and consists of more than 900 species, various hybrids and varieties. The major species that are grown in Kenya are Eucalyptus grandis, E. globulus, E. saligna and E. camaldulensis. Most Eucalyptus species are highly dependent on rainfall and this is challenged by climatic changes owing to global warming making it difficult to effectively match the availability of mature trees and the market demand especially for use as power transmission poles. With the widespread availability of other naturally occurring Eucalyptus species such as E. camaldulensis and E. globulus, it becomes important to determine the genetic diversity and to analyze the phenotypic traits of these species for suitability as power transmission poles in order to counter the overdependence on E. grandis. Phenotypic traits investigated included measuring total tree height and diameter at breast height (DBH), while molecular data were obtained from sequencing MatK, rbcL and TrnL-F genes from selected species and evolutionary analyses such as nucleotide substitution rates, base composition disparity indices, evolutionary divergence, nucleotide diversity indices and phylogeny construction were conducted in MEGA 11. Significant differences in DBH and height among Eucalyptus species were observed when the phenotypic data were subjected to ANOVA. In this study, E. robusta, E. paniculata, E. maculata, E. dunnii, E. camaldulensis and E. citriodora are fit to be used as power transmission poles but they are limited by their short height. However, E. tereticornis and E. glaucina have the desired DBH and height and hence can be used as substitutes for E.grandis. Generally, the molecular phylogeny study has shown that the studied Eucalyptus species are closely related and form various monophyletic clades which can be attributed to the short genetic distances, low substitution rates, low nucleotide bias disparity indices and low diversity scores. Further phylogenetic and gene expression studies involving more Eucalyptus species are needed to better understand Eucalyptus phylogeny, and diversity and identify species with similar genetic make-up to that of E. grandis which has been used extensively for the provision of electricity transmission poles.

Hollow occurrence and tree spacing in Eucalyptus tereticornis

ABSTRACT A ground-based survey of 400 Eucalyptus tereticornis trees examined the incidence of visible hollows suitable for hollow-dependent fauna. As well as the expected relationship with stem diameter, data analysis revealed a relationship between the incidence of hollows (with entrance diameter ≥10 cm) and spacing between neighbouring trees. When the distance between trees is equivalent to 0.3 times total tree height, a tree is more likely to suffer branch breakage and subsequent hollow formation. This influence of spacing, likely due to branches clashing during storms, appears to contribute a twofold difference in the incidence of hollows. This offers opportunities for the management of regrowth forests and restoration plantings, especially where one of the objectives is to encourage the formation of hollows.

Impact of mangrove planting on forest biomass carbon and other structural attributes in the Rufiji Delta, Tanzania

Mangrove forests provide important ecosystem services to the human society and nature including mitigation of climate change. The quality and quantity of ecosystem services offered by mangrove forests are however at risk when mangroves are degraded. The restoration of mangrove areas is considered as a natural solution to recover lost ecosystem services such as securing of carbon stocks. This study was set to assess the extent to which mangrove planting activities compensate for the loss of biomass carbon stocks and other structural attributes in Rufiji Delta-Tanzania through analysis of biomass carbon loss and gain as a result of conversion of mangroves forest into rice farms and planting of mangroves respectively. Circular sampling plots were established in good, degraded and restored mangrove areas where total tree heights and Diameter at Breast Height (DBH) of all standing trees were measured and recorded by species and used to compute biomass carbon stock. The mangrove species composition changed from 7 in 1989 to 2 species in degraded plots in 2016. The species dominance changed from Avicennia marina in 1989 to Rhizophora mucronata in 2016 in good mangrove plots and from A. marina and Sonneratia alba to an invasive Baringtonia racemosa in degraded plots. Bruguiera gymnorrhiza was the only mangrove species used for restoration through planting in the delta and the overall survival rate was 37%. The above-ground carbon (AGC) and below-ground carbon (BGC) for the good natural mangrove plots ranged from 28.18 to 299.43 and 16.00–164.51 Mg C ha−1 respectively compared to 0–150.88 and 0–967.01 Mg C ha−1 in the degraded plots. The total biomass carbon stock in the good natural mangrove plots ranged from 44.14 to 463.94 Mg C ha−1 while for the degraded plots the range was 0–247.89 Mg C ha−1. The carbon stocks in 5, 10 and 15 year old planted mangroves were 13.65, 20.13 and 57.53 Mg C ha−1 respectively. The biomass loss of 172.91 Mg C ha−1 was estimated in a period of 25 years (1989–2016), equivalent to an annual loss rate of 6.9 Mg C ha−1year−1, demonstrating that degradation has a significant contribution to loss of carbon stocks. Nevertheless, an average of 3.8 Mg C ha−1year−1 was stocked by 15 years old planted mangroves, demonstrating that there is potential for the planted mangroves to compensate for the lost carbon if the anthropogenic drivers such as rice farming is controlled. These findings call for urgent collective actions among stakeholders to consider and improve the integrated management of the delta.

ECOLOGICAL REHABILITATION INDICATORS FOR ONE EUCALYPTUS REFORESTATION WITH AN OAK FOREST AS REFERENCE

The evaluation of reforestation for ecological restoration purposes in an area requires the comparison of similarity indicators with nearby reference forests. The objective of this study was to compare the vegetal composition, structure, falling debris, and their decomposition in the soil of a reforestation site of Eucalyptus camaldulensis Dehnh, planted more than 50 years ago, and a neighbouring forest dominated by Quercus deserticola Trel. and Q. laeta Liebm (used as reference), in an area of the State of Mexico; and obtain quantitative indicators of the trajectory of rehabilitation through the use of non-native species of Mexico. In reforestation and oak forest, we established 12 sampling sites where the composition, structure and two ecological processes (falling debris and decomposition) were determined. In addition, solar radiation was estimated by taking zenith photos of the canopy, using a hemispherical lens. When data was within normal distribution, we used the Student test, and when it was not, the Wilcoxon test was used to compare the variables studied. The reference forest outperformed reforestation (p ≤ 0.05) in: richness (68 and 50 species); diversity (Simpson index, 1.6-2.6 and 0.7-2.3); normal diameter (21.3 and 13.7 cm), accumulated leaf litter (18.2 and 9.2 Mg ha-1), detritus fall (0.606 and 0.321 Mg ha-1 per month), and litter decomposition (0.443 and 0.251 Mg ha-1 per month). Reforestation had a higher total radiation (5384 vs. 4376 MJ m-2 year-1) and tree height (8.1 vs. 7.4 m). The percentage values of importance were 32.8 and 26.9 % for Quercus deserticola and Q. laeta in the oak forest, and 70 % for E. camaldulensis in the reforestation. After 50 years, reforestation still showed statistical differences from forest in composition, structure, and soil processes.

How do Araucaria angustifolia trees grow in overstocked stands?

The objective of this study was to evaluate growth along the stem of Araucaria angustifolia (Bertol.) Kuntze trees competing in overstocked stands, in order to identify periods when growth and trunk shape are differentiated during the trees' lifespan. The research was carried out in a planted forest of Araucaria angustifolia established in 1946 in the Açungui National Forest in Campo Largo, Paraná, Brazil, when these trees were 65 years old. One thinning was recorded, at some time between 1970 and 1980. Forty-six trees were selected and divided into three development classes (DC) at 65 years of age; these classes considered diameter at 1.30 m (breast height, dbh) with a range of 20 cm (from 10 cm to 70 cm). In addition to dbh, total tree height, and crown height and diameter were measured in the field. From each tree, 14 disks were removed to analyze growth rings and confirm the age of the stand. Some trees in the smallest DC (10 ≤ dbh < 30 cm) were the product of natural regeneration (younger trees that grew after the initial planting). In 63% of the trees, at least one growth ring was missing at breast height. Missing rings at breast height were more common in trees with smaller dbh and crown diameters. The need for more growing space was observed at different periods during the studied lifespan of the trees from three DCs. It resulted in changes in stems shape from conical to cylindrical. Different growth patterns could be observed during the lives of some trees as they outgrew their competition.

ALEPPO PINE ALLOMETRIC MODELING THROUGH INTEGRATING UAV IMAGE-BASED POINT CLOUDS AND GROUND-BASED DATA

Abstract. Effective monitoring of Mediterranean forest is essential to determine the role of forest management in mitigating climate change and ensuring the maintenance of its environmental services. Most of the allometric models to estimate dry above-ground biomass (AGB) at tree level are based on knowing the diameter of the trunk at breast height (DBH). However, it is difficult, if not impossible, to estimate DBH from airborne/spaceborne sensors within the context of a remote sensing-oriented approach, being common to draw upon regression models to relate DBH to remotely sensed dendrometric variables such as total tree height (H) and tree crown diameter (CD). This study uses UAV (unmanned aerial vehicle) image-based data to estimate the dendrometric variables H and CD of the repopulated Aleppo pine (Pinus halepensis Mill.) located in a semiarid continental Mediterranean forest of Almería (southeast of Spain). DBH data were gathered through field work. Both bivariate (DBH = Φ(H)) and multivariate (DBH = Ψ(H, CD)) allometric models were developed by applying least-squares-based regression and machine learning regression methods. The results showed that multivariate allometric models performed better than bivariate at predicting DBH, both in terms of goodness-of-fit and stability against changes in training or testing samples. In addition, least-squares-based regression (linear and potential) provided statistically similar results to those obtained from complex machine learning ensemble algorithms. In this way, the easy-to-apply multivariate linear allometric model DBH = −4.84 + 1.73149H + 3.08114CD (R2 = 89.23%) would be recommended to locally estimate DBH in Aleppo pine from remotely sensed H and CD data.

Relationships between tree slenderness coefficients and stand characteristics for major plantation-grown species in North-western Nigeria

This study established relationships between tree slenderness coefficient (used as an index of resistance of trees to windthrow) and some stand characteristics of three major tree species used for plantation establishment in some part of North-western Nigeria. Tree measurements for diameter at breast height (DBH) and total tree height were conducted on 60 randomly selected temporary sample plots (TSP) of 20 × 20 m, while tree slenderness coefficient (TSC), basal area (BA), and tree volume were computed from the field data. Pearson correlation was used to establish a relationship between TSC and other tree variables, while nonlinear regression analysis was used in developing models for predicting TSC from DBH and tree height. Results from descriptive statistics indicate that there were low slenderness coefficient values across the three species under study. TSC was found to be negatively correlated with tree DBH, BA, and volume but positively correlated with tree height. Five candidate models were selected as base models to predict TSC from DBH alone and result from the nonlinear regression analysis revealed that the exponential function produced better fit statistics and it was further modified to include an additional tree variable (height). Results of the regression model that includes additional tree variables have better fit statistics compared to those models (base models) without additional tree variables. An exponential function model is recommended for estimating TSC from DBH and tree height for the three major plantation-grown species in North-western Nigeria.

Total tree height predictions via parametric and artificial neural network modeling approaches

Height-diameter relationships are of critical importance in tree and stand volume estimation. Stand description, site quality determination and appropriate forest management decisions originate from reliable stem height predictions. In this work, the predictive performances of height-diameter models developed for Taurus cedar (Cedrus libani A. Rich.) plantations in the Western Mediterranean Region of Turkey were investigated. Parametric modeling methods such as fixed-effects, calibrated fixed-effects, and calibrated mixed-effects were evaluated. Furthermore, in an effort to come up with more reliable stem-height prediction models, artificial neural networks were employed using two different modeling algorithms: the Levenberg-Marquardt and the resilient back-propagation. Considering the prediction behavior of each respective modeling strategy, while using a new validation data set, the mixed-effects model with calibration using 3 trees for each plot appeared to be a reliable alternative to other standard modeling approaches based on evaluation statistics regarding the predictions of tree heights. Regarding the results for the remaining models, the resilient propagation algorithm provided more accurate predictions of tree stem height and thus it is proposed as a reliable alternative to pre-existing modeling methodologies.

Response of Timber Yield, Biomass, CAI and Carbon Sequestration to Varied Pruning Intensities of Dalbergia sissoo Roxb. in Agrisilviculture System in Central India

In Central India, an experiment was carried out on a 22 year old Dalbergia sissoo based agrisilviculture model in 2020-21 to investigate the response of different pruning intensities on Rabi seasonal diameter growth, timber production, CAI of total biomass, and carbon sequestration potential. Each year, paddy followed by wheat is grown under trees spaced at 5m × 5m continuously being treated with four different pruning intensities, i.e., 0% (P0: No pruning), 25% (P25: Light pruning), 50% (P50: Moderate pruning) and 75% (P75: Heavy pruning) of the total tree height. It was reported that different rates of pruning had a significant effect. Maximum Rabi seasonal D.B.H. increment was recorded in P0 (0.68 cm) and minimum in P75 (0.49 cm). Maximum seasonal yield of large-sized timber, small-sized timber, and fuelwood (5.80 m3 ha-1, 0.62 m3 ha-1 and 7.48 q ha-1, respectively) were recorded under light pruning treatment (P25). However, the minimum seasonal yield of large-sized timber and fuelwood (5.80 m3 ha-1 and 5.14 q ha-1, respectively) were under heavy pruning (P75) and the minimum seasonal yield of small-sized timber (0.32 m3 ha-1) under moderate pruning (P50). Maximum annual above-ground biomass, annual below-ground biomass and current annual increment of total biomass (171.63 q ha-1 yr-1, 34.33 q ha-1 yr-1, and 205.95 t ha-1 respectively) were recorded under light pruning treatment (P25), while minimum (84.50 q ha-1 yr-1, 16.90 q ha-1 yr-1 and 101.40 t ha-1 respectively) under heavy pruning (P75). Carbon sequestration potential was reported to be higher with light pruning (92.68 q ha-1 yr-1), followed by moderate pruning (63.69 q ha-1 yr-1), while minimum under heavy pruning (45.63 q ha-1 yr-1) and no pruning (46.91 q ha-1 yr-1) at all. It was concluded that light pruning of 25% was best among the four treatments in terms of timber and biomass yield.

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 &lt; 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