Effect of pruning treatment on the growth of woody pioneers under exclosure management in Tigray, Ethiopia

Abstract. Dey T, Ahmed S, Islam MA. 2021. Relationships of tree height-diameter at breast height (DBH) and crown diameter-DBH of Acacia auriculiformis plantation. Asian J For 5: 71-75. Measuring the height and crown diameter in the field is time-consuming and needs more logistical efforts. Thus, in this study, we have focused on evaluating the relationship between height and crown diameter with commonly and less effortlessly measured parameters such as diameter at breast height (DBH) to reduce the inventory costs and time by using these models. Different correlation-regression models for predicting tree height and crown diameter from DBH were developed for Acacia auriculiformis species at Char Kukri-Mukri Island in the Bhola district of Bangladesh. To achieve the goal, DBH, total height, and crown diameter of each tree were recorded. Coefficient of determination (R2) and p-value was used for evaluating the models. The correlation coefficients between DBH and height and between DBH and crown diameter showed positive and significant relationships. The calculated p-value and R2 value between DBH and height and between DBH and crown diameter in the correlation-regression analysis revealed that linear regression models were best fitted in both cases. The study concluded that the tree height could be estimated by the mean of DBH and vice versa, as well as crown diameter could be estimated by the mean of DBH and vice versa.

Maintaining trees on farmland improves the carbon sequestration potential of agricultural lands and contributes to global carbon balance. Samples of 35 trees were harvested for aboveground biomass (AGB) and carbon stock measurements in parkland agroforestry fields of Tigray, Ethiopia. Allometric equations were developed using the regression models that related the total AGB with a diameter at stump height (DSH), diameter at breast height (DBH), and a combination of DSH, DBH, height (H), and crown diameter (CD). The allometric model related to diameter at breast height, Ln (AGB) = -2.85 + 2.4 ln (DBH), was considered the best fit, with the highest adjusted coefficient of determination (0.88) and lowest prediction residuals sum of squares (3.51 kg), bias (-2 kg), root mean square error (0.3 kg), and Akaike information criterion (P < 0.01). The best-fitting model for aboveground biomass estimation was validated using cross-validation. When assessed with the aboveground biomass of F. albida data sets from this work, the species-specific and multi-species previously published models were substantially overestimated by 60% and underestimated by 50%, respectively. F. albida total aboveground biomass was 3372.25 kg ha−1 and 1584.96 kg ha−1 of carbon for a density of 47 trees ha−1 in the parklands. The results showed that the statistical fits of our model were generally good, enabling confidence in its use to predict the aboveground biomass of F. albida stands. Our study identified patterns of carbon distribution in different F. albida tree sizes that may serve as a guide for programs that measure, report, and verify carbon stock and promote a climate-resilient farming system.

Seven models for predicting crown diameter using diameter at breast height were tested for Picea orientalis L. (Link.) in Artvin. Data were obtained from 4208 trees measured on 117 temporary sample plots. Sample plots were grouped into categories with 20 year mean age class intervals. Similarly, sample plots were grouped into categories based on mean tree diameter at breast height (2 cm diameter class interval). Mean diameter at breast height and mean crown diameter of sample plots in age class were analyzed statistically. One linear and six non-linear diameters at breast height-crown diameter functions were selected as candidate functions to model diameters at breast height -crown diameter relationship. Regression analysis showed that there were statistically significant (P > 0.05) and strong (R2 > 0.80) relationship between diameter at breast height and crown diameter variables in P. orientalis. The results of the study indicated that the diameter at breast height-crown diameter relationship can be described by cubic, compound, growth or exponential model because of the same R2 values. But the cubic model gave the best result for relationship between diameter at breast height and crown diameter. Key words: Crown diameter, diameter-crown diameter model, oriental spruce, regression analysis.

The study regarding correlation between diameter at breast height (DBH) and other variables like height, crown diameter, volume and carbon of the tree species of Schima wallichii and Castonopsis indica was not done yet. Thus, this research was objectively carried out to assess the correlation between DBH and different parameters particularly height, crown diameter, volume and carbon stock. The study was centered on the mid hill region where natural Schima-Castonopsis forest is abundantly found. Total 360 nested sample plots were established having 12.62 m radius for tree, 5.58 m radius for pole, 2.78 m radius for Sapling, 1.76 m radius for seedling measurement. The DBH and height were measured of these tree species in the plots. Collected data was analyzed using Pearson correlation to show the relation of different characteristics of tree and equations were examined using ANOVA and t-test. The descriptive statistics mean ± standard error (SE) of DBH was 28.65±1.25 cm, standard deviation was 19.682, minimum value was 5.2 and maximum value was 161.5 of Castonopsis indica. Similarly, mean±standard error of DBH was 22±0.96 cm, standard deviation 10.254, minimum value was 5.5 and maximum value was 54.3 of Schima wallichii. Moreover, there was positive and strong correlation between DBH and height of Castonospsis Indica with R square value 0.71 and the equation was Y=7.1075ln(X)-9.4467 whereas, Y is the height of the tree and X is DBH. This correlation between DBH and height of Schima wallichii also showed positive and strong with R square value 0.81 and the equation was Y=7.9982ln(X)-11.277. Same correlation was found between DBH and crown diameter of Castanopsis Indica having equation Y=3.4335ln(X)-6.8637 whereas Y is the crown diameter of the tree and X is DBH. Moreover, similar correlation between DBH and volume was also found. Statistically, ANOVA and t-test showed that there was significant correlation between DBH and tree characteristics like height, crown diameter and volume at 95% confidence level. This research will be useful for the decision maker and scientific community to assess the volume and carbon measuring single variable i.e. only DBH.

We developed species specific equations to predict aboveground biomass (AGB) of ten woody species in Borana rangelands of southern Ethiopia. A total of 150 plants 15 for each species were measured for biometric variables including the diameter at stump height (DSH), diameter at breast height (DBH), tree height (TH) and crown diameters were destructively harvested to obtain dry biomass. Many equations that related three biomass components: total aboveground, stem and branches to single or combination of predicator variables: DSH, DBH, TH, crown area (CA) and crown volume (CV) fit the data well to predict total AGB and by components for each of the species (adj.R2 > 0.80; P 0.80; P 0.93; P < 0.0001. A generalized mixed-species allometric model developed from the pooled data of seven species was most accurately predicted by the combination of three predicators (DSH-TH-CA models), with adj. R2 between 0.84 and 0.90 for all AGB categories. Hence, our species-specific allometric models could be adopted for the indirect biomass estimation in semi-arid savanna ecosystem of southern Ethiopia. The mixed species allometric models will give a good opportunity when species-specific equations are not available and contribute to estimate the biomass and carbon stock in woody vegetations of East African rangelands.

Forty-two genotypes were evaluated for juvenile wood yield and its components at three locations in Bihar, India. A significant difference was observed among the genotypes for all the characters under study. The highest value of genotypic and phenotypic coefficients of variation was observed in juvenile wood volume followed by diameter at breast height (DBH). Characters like plant height, clear bole height, crown diameter number of branches, angle of branch, diameter of branch, and length of branch showed moderate values for genotypic and phenotypic coefficients of variation. Very high heritability was estimated for clear bole height, crown diameter, angle of branch, and length of branch. Diameter and plant height showed moderate to high heritability. Relatively genetic advance expressed in percentage of mean or genetic gain was observed the highest in volume (30.86%), DBH (18.96), clear bole height (17.19%), angle of branch (17.39), length of branch (19.53), and in plant height (11.87%). Juvenile wood volume per plant showed significant and positive correlation with height (0.619), diameter (DBH, 0.770), clear hole height (0.305), number of branch (0.372); and positive association with crown diameter (0.145), angle of branch (0.055), diameter of branch (0.251), length of branch (0.200), and survival (0.166); and significant negative correlation with taper (−0.499) at the phenotypic level. In phenotypic path analysis diameter (DBH, 0.702), plant height (0.169), crown diameter (0.121), taper (0.027), and survival (0.050) showed positive direct effect on juvenile wood volume. The direct impact of the same through clear bole height (−0.366), number of branch (−0.130), angle of branch (−0.228), and length of branch (−1.567) was negative. Hence it is suggested that due importance should be given to diameter (DBH), plant height, crown diameter, diameter of branch, taper, and survival for selection of superior plant with high juvenile wood yield potential in poplar.

This study was conducted to suggest the necessity of regulated stand density control in order to maintain the ratio of height to diameter at breast height (H/D ratio) of Hinoki cypress (Chamaecyparis obtusa) and Japanese cedar (Cryptomeria japonica) in South Korea. A total of 2,000 (1,000 each) Hinoki cypress and Japanese cedar were cut from various regions of South Korea, and their diameter at breast height (DBH), height and clear length were measured. The two species’ regional means of H/D ratio and crown ratio were then computed and compared to find the relationship with tree growth. The result of analyzing the relationship between the H/D ratio and tree growth by DBH class is as follows, 77.0% for small DBH class, 62.5% for medium DBH class, and 45.9% for large DBH class, with overall mean of 61.8%. The annual means of DBH growth were 4.6 mm, 7.4 mm, and 8.2 mm respectively for small, medium, and large DBH classes. As the DBH class went up, the H/D ratio decreased, showing a negative correlation (p < 0.0001) with the tree growth rate. However, the crown ratio showed a significant correlation with tree growth. Japanese cedar’s H/D ratios by DBH class were 100.5% for small, 74.9% for medium, and 53.6% for large, while its mean annual DBH growth were 5.1 mm, 7.6 mm, and 10.0 mm, from small to large DBH class respectively. Similar to that of Hinoki cypress, Japanese cedar’s H/D ratio showed a negative correlation with the growth rate (p < 0.0001), but no significant relationship could be established between the crown ratio and the tree growth. In both arboreal species, the correlation between the H/D ratio and growth rate is negative, and no significant correlation could be formulated between crown ratio and tree growth. In conclusion, both tree species tended to have a higher H/D ratio and a lower growth rate in small DBH class, while H/D ratio decreased and growth rate increased As DBH class got larger.

The energy source of a tree comes from solar radiation, and the crown is considered the tree organ that influences the interception of photosynthetic energy and, consequently, its growth. The influence of growth location, age of population, and meteorological elements on the relationship between crown diameter (CD) and diameter at breast height (DBH) of Acacia mearnsii De Wild. (black wattle) was studied. To this end, the study of the relationship between CD and DBH was conducted in stands of 1-7-year-old black wattle trees in two cultivation sites. CD increases proportionally to the increase in DBH, following a logarithmic relationship. The increase in CD as a function of DBH tended to decrease at different intensities, with the largest relative CD increase for the smallest DBH increase, and vice versa. The relationship between CD and DBH for the different ages and locations of the stands varied, generating dependent effects for these factors. The general equations generated to describe this relationship can be used for CD estimate, and their coefficients are correlated with rainfall and average maximum air temperature.

The rising demands for Parkia biglobosa due to its numerous benefits and the lack of active conservation measures have endangered the species in most of its natural ranges. Data on its dendrometry, which is a prerequisite for its sustainable management, are limited especially in Ghana. This study, therefore, investigated the relationships between five dendrometry variables and developed models for predicting them. The prediction models were developed using diameter at breast height and crown diameter as independent variables. Ten randomly distributed trees were sampled, and data collected and analyzed using Pearson correlation and simple linear regression. It was observed that stem diameter was positively correlated with all the other four variables measured. The correlation between stem diameter at breast height and crown diameter was 0.69. The co-efficient of determination between stem diameter at breast height and total height, crown diameter, crown ratio and crown height had R2 values of 0.16, 0.48, 0.19 and 0.28, respectively. Crown diameter, as the second indicator variable, was also positively related with total height with correlation co-efficient of 0.97 and R2 value of 0.09. The relationship between stem diameter at breast height and crown diameter was significant with f-value of 0.03 at 95% confidence level. The results will make significant contributions to the management of trees in the study area. The study will also be morale booster for similar studies to be conducted to assist improve the models developed.

Tree growth is an important indicator of forest health and can reflect changes in forest structure. Traditional tree growth estimates use easy-to-measure parameters, including tree height, diameter at breast height, and crown diameter, obtained via forest in situ measurements, which are labor intensive and time consuming. Some new technologies measure the diameter of trees at different positions to monitor the growth trend of trees, but it is difficult to take into account the growth changes at different tree levels. The combination of terrestrial laser scanning and quantitative structure modeling can accurately estimate tree structural parameters nondestructively and has the potential to estimate tree growth from different tree levels. In this context, this paper estimates tree growth from stem-, crown-, and branch-level attributes observed by terrestrial laser scanning. Specifically, tree height, diameter at breast height, stem volume, crown diameter, crown volume, and first-order branch volume were used to estimate the growth of 55-year-old larch trees in Saihanba of China, at the stem, crown, and branch levels. The experimental results showed that tree growth is mainly reflected in the growth of the crown, i.e., the growth of branches. Compared to one-dimensional parameter growth (tree height, diameter at breast height, or crown diameter), three-dimensional parameter growth (crown, stem, and first-order branch volumes) was more obvious, in which the absolute growth of the first-order branch volume is close to the stem volume. Thus, it is necessary to estimate tree growth at different levels for accurate forest inventory.

Genetic parameters of 9 oriental sweetgum (Liquidambar orientalis Mill.) populations were estimated at a common garden test. Open-pollinated seeds were collected from 16-27 families for each population. The common garden test was established in 2009 using a randomized complete block design in 25 blocks with single tree plot, with each block included 223 families. Breast height diameter, height and crown diameter were measured at the age of five. The purpose of study was to compare the genetic parameters of optimal and marginal populations and to assess the findings for genetic conservation. The study revealed significant variability in all traits evaluated. In variance components, variation among populations was three times higher than that of families. Individual heritability estimates for breast height diameter, height and crown diameter pooled across the whole dataset (marginal and optimal populations) were 0.21 ± 0.04, 0.27 ± 0.04 and 0.11 ± 0.03 and additive genetic coefficients of variation were 13.4%, 9.1% and 7.1%, respectively. Individual heritability estimates for breast height diameter, height and crown diameter in marginal and optimal populations were 0.27 ± 0.10, 0.19 ± 0.08 and 019 ± 0.08 and 0.19 ± 0.04, 0.29 ± 0.05 and 0.09 ± 0.03, respectively. Additive genetic coefficients of variation for breast height diameter, height and crown diameter were 16.7%, 8.3% and 10.8% in marginal and 12.8%, 9.1% and 6.2% in optimal populations, respectively. While breast height diameter and crown diameter were more heritable for marginal populations, height was more heritable for optimal populations. These findings are discussed in terms of genetic conservation of oriental sweet gum.

Canopy structural data can be used for biomass estimation and studies of carbon cycling, disturbance, energy balance, and hydrological processes in tropical forest ecosystems. Scarce information on canopy dimensions reflects the difficulties associated with measuring crown height, width, depth, and area in tall, humid tropical forests. New field and spaceborne observations provide an opportunity to acquire these measurements, but the accuracy and reliability of the methods are unknown. We used a handheld laser range finder to estimate tree crown height, diameter, and depth in a lowland tropical forest in the eastern Amazon, Brazil, for a sampling of 300 trees stratified by diameter at breast height (DBH). We found significant relationships between DBH and both tree height and crown diameter derived from the laser measurements. We also quantified changes in crown shape between tree height classes, finding a significant but weak positive trend between crown depth and width. We then compared the field-based measurements of crown diameter and area to estimates derived manually from panchromatic 0.8 m spatial resolution IKONOS satellite imagery. Median crown diameter derived from satellite observations was 78 percent greater than that derived from field-based laser measurements. The statistical distribution of crown diameters from IKONOS was biased toward larger trees, probably due to merging of smaller tree crowns, underestimation of understory trees, and overestimation of individual crown dimensions. The median crown area derived from IKONOS was 65 percent higher than the value modeled from field-based measurements. We conclude that manual interpretation of IKONOS satellite data did not accurately estimate distributions of tree crown dimensions in a tall tropical forest of eastern Amazonia. Other methods will be needed to more accurately estimate crown dimensions from high spatial resolution satellite imagery.

ABSTRACTCanopy structural data can be used for biomass estimation and studies of carbon cycling, disturbance, energy balance, and hydrological processes in tropical forest ecosystems. Scarce information on canopy dimensions reflects the difficulties associated with measuring crown height, width, depth, and area in tall, humid tropical forests. New field and spaceborne observations provide an opportunity to acquire these measurements, but the accuracy and reliability of the methods are unknown. We used a handheld laser range finder to estimate tree crown height, diameter, and depth in a lowland tropical forest in the eastern Amazon, Brazil, for a sampling of 300 trees stratified by diameter at breast height (DBH). We found significant relationships between DBH and both tree height and crown diameter derived from the laser measurements. We also quantified changes in crown shape between tree height classes, finding a significant but weak positive trend between crown depth and width. We then compared the field‐based measurements of crown diameter and area to estimates derived manually from panchromatic 0.8 m spatial resolution IKONOS satellite imagery. Median crown diameter derived from satellite observations was 78 percent greater than that derived from field‐based laser measurements. The statistical distribution of crown diameters from IKONOS was biased toward larger trees, probably due to merging of smaller tree crowns, underestimation of understory trees, and overestimation of individual crown dimensions. The median crown area derived from IKONOS was 65 percent higher than the value modeled from field‐based measurements. We conclude that manual interpretation of IKONOS satellite data did not accurately estimate distributions of tree crown dimensions in a tall tropical forest of eastern Amazonia. Other methods will be needed to more accurately estimate crown dimensions from high spatial resolution satellite imagery.

Growth responses of mesquite (Prosopis juliflora (SW) DC.) during establishment stage to planting methods and amendments were studied in a highly alkali soil (Aquic Natrustalf, ESP 94), at the experimental farm of the Central Soil Salinity Research Institute, Karnal in July, 1984. Six combinations of planting methods and amendments with and without Karnal grass (Diplachne fusca Linn. P Beauv) in the inter-row space were compared in a four times replicated field experiment in randomised block design. The mean plant height (MPH), diameter at stump height (DSH), diameter at breast height (DBH), lopped biomass 16 months past planting and total biomass attained in 2 years period were significantly less when inter-row space was planted with Karnal grass. The MPH (cm), DSH and DBH (mm) attained in 2 years period were 319, 43.4 and 15.1 in with grass as compared to 405, 53.4 and 20.3 in without grass treatments. Similarly, the total biomass attained in 2 years was about 3 times more where inter-row space was not planted with grass. Growth was better when mesquite was planted by auger hole and pit methods than in trench plantation, when the original soil was treated with gypsum at 3 kg plant−1 and then refilled. However, using trenches of dimensions 30 × 30 cm and filled with a mixture of original soil, 3 kg gypsum and 8 kg farm yard manure plant−1 appeared to be promising method for establishing mesquite plantations on highly deteriorated alkali soils. The effect of amendments on growth decreased in the order gypsum + FYM, gypsum + rice husk, gypsum, control. In two years period, 37 percent mesquite died in the trenches in which the original soil was left unchanged. Effect of treatments on nutrient concentrations and total accumulations in different segments of mesquite is discussed. Karnal grass gave 25.3 t ha−1 green forage yield in 8 cuts without amendment in a growth period of 26 months proving its great potential as a folder crop for the adverse sites. The inorganic chemical composition of the shoots, including trace elements Fe, Mn, Zn and Cu, is such as to make this species a highly promising plant for the exploitation of alkali soils. Growing Karnal grass with mesquite for a period of about 2 years reduced soil pH and EC significantly and improved organic carbon and available N contents. The grass improved water infiltration rates and moisture storage in the lower layers of the profile.

Tree crown plays a crucial role in the process of photosynthesis and the formation of biomass. The site conditions and stand density have a significant impact on tree and crown growth, as well as biomass formation. Understanding crown growth and its influence on the allometric growth of the biomass of various organs under diverse site conditions and densities is critical to comprehending forest adaptation to climate change and management. This study examined the growth of trees, crown, and biomass in 36 plots of young Platycladus orientalis plantations across three site conditions (S1: thin soil on the sunny slope; S2: thick soil on the sunny slope; S3: thin soil on the shady slope) and four densities (D1: ≤1500 plants/hm2; D2: 1501–2000 plants/hm2; D3: 2001–3000 plants/hm2; and D4: ≥3001 plants/hm2). The findings of this study showed that S3 demonstrated the best tree growth, with considerably higher DBH and V than S1 and S2. In addition, as the number of trees grew, the average diameter at breast height (DBH), height (H), and volume (V) all decreased greatly. Poor site (S1) suppressed the canopy, decreasing crown width (CW), crown length (CL), crown ratio (CR), crown surface area (CCSA), and crown volume (CCV), while increasing crown efficiency (CEFF). This same trend was seen in D4, where CR, CCSA, and CCV were all much smaller than the other densities, but CEFF was the highest. Subjective and objective indicators were less responsive to changes in crown growth than crown composite indicators like CCSA, CCV, CEFF, and CR. Site condition and density had a major impact on biomass accumulation, with S1 and D4 having a much lower biomass than S2, S3, D1, D2, and D3. More biomass was allocated to the stem in S3 and D1, and more biomass was allocated to branches and leaves in S2, S3, D1, D2, and D3, resulting in a nearly isotropic growth of branches and leaves. The effect of crown indicators on the biomass of each organ varied according to site condition and density. In varied site conditions, crown and DBH ratio (RCD) contributed the most to stem biomass, whereas CL contributed the most to branch and root biomass. CL had the largest effect on biomass accumulation at various densities. This study demonstrates how site condition and density affect tree and crown development and biomass accumulation, providing theoretical guidance for plantation management under climate change.