Table 5 - uploaded by Stephen Adu-Bredu
Content may be subject to copyright.
Source publication
The development of tree allometric equations is crucial to accurate forest carbon assessment. However, very few allometric equations exist for sub-Saharan Africa and as a result generalized allometric equations, often established for forests in other continents, are used by default. The objectives of this study were (1) to propose a sampling method...
Contexts in source publication
Context 1
... wood density ranged from 0.11 to 1.01 g cm −3 , with an aver- age value of 0.59 ± 0.00484 (SD) g cm −3 ( Table 5). The wood density was significantly influenced by the guild status (p < 0.001, DF = 609): The pioneers (P) species had the lowest wood density value of 0.42 ± 0.012 (SD) g cm −3 ), followed in an increasing order by Non- Pioneer Light Demanders (NPLD) and Shade bearers (SB), with mean values of 0.63 ± 0.00388 g cm −3 and 0.64 ± 0.0107 g cm −3 , respectively. ...
Context 2
... the difference in wood density between NPLD and SB was not significant (p = 0.303, DF = 641). Within a guild, the wood density varied among tree species (Table 5). For example, the lowest wood density for the pioneer group was observed for Cecropia peltata (0.25 ± 0.0156 g cm −3 ) while the highest was for Ceiba pentandra (0.48 ± 1.92 10 −2 g cm −3 ). ...
Context 3
... overall average wood density of 0.59 g cm −3 reported in this study is very close to the reported values for trees in Africa. The average wood density of 0.62 g cm −3 reported by IPCC (2003) is 5% higher than that of this study, but the reported wood density for trees in Africa ranges between 0.58 and 0.67 g cm −3 , with an average value of 0.60 g cm −3 ( Table 5). The use of average wood density values instead of specific ones normally introduces Comparison with allometric equations found in the literature. ...
Similar publications
This paper presents the palaeoxylotomical study of silicified wood specimens found in Nanovitsa depression, Eastern Rhodope Mts. In this area, a Petrified Forest has been described, hosted by an Oligocene volcano-sedimentary formation. The Petrified Forest occurs in a deep gorge, east of Momchilgrad, and is represented by petrified wood remains occ...
This study aimed to assess vegetal cover evolution on a river island within the Ecological Station of (EEP), by remote sensing. For this purpose, Normalized Difference Vegetation Indexes were generated for Landsat 1 (1973) and Landsat 5 (1984, 1990, 2000 and 2011) images. Five landscape units were identified in the field: bare soil, Rough savanna,...
Citations
... These estimation errors often have a direct implication on expanded biomass/carbon estimation from volume. Henry et al. [96] found a significant bias in biomass estimates converted from volumes computed using a generic form factor of 0.6 across some African tropical forests. Nevertheless, the trend and significance of estimation errors from alternative values vary and may be dependent on relative variability in methodologies, species architecture, site, stand, and management conditions compared to the forests from which the form values were originally obtained. ...
The concept of tree or stem form has been central to forest research for over a century, playing a vital role in accurately assessing tree growth, volume, and biomass. The form factor is an essential component for expressing the shape of a tree, enabling more accurate volume estimation, which is vital for sustainable forest management and planning. Despite its simplicity, flexibility, and advantages in volume estimation, the form factor has received less attention compared to other measures like taper equations and form quotient. This review summarizes the concept, theories, and measures of stem form, and describes the factors influencing its variation. It focuses on the form factor, exploring its types, parameterization, and models in the context of various tropical species and geographic conditions. The review also discusses the use of the form factor in volume estimation and the issues with using default or generic values. The reviewed studies show that tree stem form and form factor variations are influenced by multiple site, tree, and stand characteristics, including site quality, soil type, climate conditions, tree species, age, crown metrics, genetic factors, stand density, and silviculture. The breast height form factor is the most adopted among the three common types of form factors due to its comparative benefits. Of the five most tested form factor functions for predicting tree form factors, Pollanschütz’s function is generally considered the best. However, its performance is often not significantly different from other models. This review identifies the “Hohenadl” method and mixed-effects modelling as overlooked yet potentially valuable approaches for form factor modelling. Using the form factor, especially by diameter or age classes, can enhance tree volume estimation, surpassing volume equations. However, relying on default or generic form factors can lead to volume and biomass estimation errors of up to 17–35%, underscoring the need to limit variation sources in form factor modelling and application. Further recommendations are provided for improving the statistical techniques involved in developing form factor functions.
... This approach accounted for a further 33 % of species. For species without any genus-level data available, a default wood density value of 0.60 g cm − 3 was applied, according to Henry et al. [68]. A widely used conversion factor of 0.47, common in tropical African studies [8,[69][70][71], was applied to convert AGB to carbon values,. ...
... In all volume estimation cases, the inclusion of other tree variables than DBH doesn't improve the model. The finding is inconsistent with (Henry et al., 2010), which stated that the inclusion of more than one tree variable improves the allometric equation. ...
... The study showed that there is a significant difference in mean wood basic density between tree species p<0.05, which is in line with the findings of (Asrat et al., 2020a;Henry et al., 2010;Tesfaye et al., 2016;Ubuy et al., 2018). The nature of tree species and the environmental conditions in which they grow contribute to differences in wood basic density. ...
Forest biomass is estimated using a volume model, wood basic density (wbd), and biomass expansion factor (BEF). However, in Ethiopia, there is a shortage of volume models, hence the volume estimation was carried out using a generic model. As a result, estimation may be subject to bias when applied in areas outside its original geographic range of development. Consequently, there is a need for further research and data collection to enhance the accuracy and reliability of these equations. This study aims to develop species-specific volume models, biomass expansion factors, wood basic densities, and form factors for selected tree species in the moist evergreen Afromontane Forest of Ethiopia. A total of 59 trees were harvested for volume model, BEF, and wbd development. Nonlinear regression was employed to develop the models, and the developed models were compared with previously established models using goodness-of-fit measures. For the volume model, diameter at breast height explained 89 % - 99 % of the volume variation. Comparison with previously developed models indicates that the currently developed model yields the least error. The mean BEF for the study species was 1.58, while the mean wood basic density for all tree species was 0.58 g/cm3. The study demonstrated that species-specific volume models reduce errors in the estimation of forest volume and biomass.
... It is a key functional trait as it is closely related to the tree's mechanical support, water transport efficiency, and storage capacity . It is also a strong indicator of the state of succession in tropical trees, where a low value of wbd is associated with early successional characteristics of pioneer species (Henry et al., 2010). Wood basic density is an important indicator of wood quality as it is directly related to strength properties, yield and quality of pulp, and the energy yield or wood calorific value (Zobel and Van Buijten, 1989). ...
... Wood basic density is an important indicator of wood quality as it is directly related to strength properties, yield and quality of pulp, and the energy yield or wood calorific value (Zobel and Van Buijten, 1989). Moreover, it is one of the important variables used in allometric models to estimate forest biomass (Chave et al., 2014(Chave et al., , 2005Henry et al., 2010). ...
... It varies also between individual trees of a given species, which is often related to tree age (Deng et al., 2014;Githiomi and Kariuki, 2010). Moreover, within individual trees, variations in wbd occur between different sections of the tree (Njana et al., 2016), radially from pith to bark (Bastin et al., 2015;Henry et al., 2010;Osazuwa-Peters et al., 2014;Plourde et al., 2015), and vertically along the main axis of the trunk (Billard et al., 2021;Longuetaud et al., 2017;Machado et al., 2014;Njana et al., 2016;Yeboah et al., 2014). The vertical variation is less studied than the radial variation. ...
Wood basic density (wbd) is one of the important predictors of aboveground biomass (AGB) of trees. It is subjected to great variability, and different factors explain this variation. Because of interest in the global carbon cycle, estimating forest biomass with sufficient accuracy has become increasingly important. Therefore, assigning accurate wbd values is important to reduce uncertainties in biomass estimations. This study aimed to determine the wbd of the dominant tree species in a dry Afromontane Forest and examine the variation in wbd among species and height positions along the vertical axis of the stem. The effect of competition and slope on wbd was also evaluated. Twelve dominant tree species were targeted and stem discs for wbd determination were collected at three height positions along the vertical axis of the stem for each species. A one-way analysis of variance was carried out to evaluate wbd variations among the species and the three height positions within the trees. A linear mixed effect model was applied to see the effect of competition and slope on wbd. The studied species showed a significant variation in their wbd values. The species-wise overall mean wbd value was 0.75 g cm−3, with a range between 0.607 and 0.911 g cm−3. Only one among the 12 species has wbd value in the Global Wood Density (GWD) database. Competition and slope had a significant effect on wbd, where an increase in competition and slope gradient was associated with an increase in wbd. The obtained wbd data and information can add to the limited knowledge on wbd values of tree species growing in dry Afromontane forests. Moreover, applying the wbd values obtained from this study while estimating AGB using the previously developed multispecies model for Desàa dry Afromontane Forest could significantly improve the accuracy of the biomass estimate.
... The existing models exhibited prediction errors as high as 56%, with a model efficiency of approximately 40%, all overestimating sengon stem volumes. This follows common reports that regional or pantropical models are often deficient in accurately capturing site or species differences in forest stock estimation (Chave et al. 2005;Henry et al. 2010;Tiryana et al. 2021;Hossain et al. 2023). The limited suitability of existing regional models to estimate stem volumes for sengon plantations in this study can be attributed to several factors. ...
... WD varies throughout a tree's main stem from the base to the apex, and from pith to bark (Henry et al. 2010) (Fig. 3.3). Commonly, WD is reduced at the stump to the midline of the tree and then it rises towards the top (Espinoza 2004). ...
Recent research has shed light on the crucial role of wood density, a fundamental physical property, as a functional trait. This means wood density isn't just about how much a piece of wood weighs, but how it influences a plant's entire strategy for survival and growth. While variations exist between individual species, a surprising trend has emerged: the majority of this variation can be traced back to a plant's genus or even family. This strong phylogenetic signal indicates that wood density is a deeply ingrained characteristic, shaped by a plant's evolutionary history. This newfound understanding allows us to leverage wood density as a taxon-based functional trait. By considering the typical wood density of a plant group (like a genus or family), we can improve models and predictions related to various ecological and functional aspects in forests and plantations. Over the past couple of decades, scientists have been actively exploring the connections between wood density and a wide range of plant functions. Denser wood is often linked to slower growth rates, delayed reproduction, and increased mechanical strength. It also influences a plant's ability to transport water, resist death (mortality rate), and manage internal water balance (water potential). Additionally, wood density is closely tied to physiological aspects such as gas exchange and xylem hydraulic conductance, which are crucial for nutrient and water movement. Wood density is also an important parameter to determine the carbon sequestration capacity of a tree or vegetation, thus important in climate change research. This proposed book will delve into these fascinating connections, highlighting how wood density acts as a key player in shaping the lives of plants and the overall health of forest ecosystems.
... Allometric equations have been used to predict biomass and productivity of both mixed, multispecies and mature forests, covering a wide range of diameter and height classes (Andersson 1970). To date, several allometric equations have been developed (Basuki et al. 2009;Brown 1997Brown , 2002Brown et al. 1989;Chave et al. 2005Chave et al. , 2014Henry et al. 2010;Litton and Kauffman 2008;Mugasha et al. 2013;Nelson et al. 1999;Pilli et al. 2006;Smith 1993;Vieilledent et al. 2012;Whittaker and Woodwell 1968). But in Africa in general, and in Ethiopia in particular, the limited availability of species-specific or mixed allometric equations has led to widespread use of pantropical equations for estimating tree biomass. ...
Background: Most of the biomass equations were developed using sample trees collected mainly from pan-tropical and tropical regions that may over-or underestimate biomass. Site-specific models would improve the accuracy of the biomass estimates and enhance the country's measurement, reporting, and verification activities. The aim of the study is to develop site-specific biomass estimation models and validate and evaluate the existing generic models developed for pan-tropical forest and newly developed allometric models. Total of 140 trees was harvested from each diameter class biomass model development. Data was analyzed using SAS procedures. All relevant statistical tests (normality, multicollinearity, and heteroscedasticity) were performed. Data was transformed to logarithmic functions and multiple linear regression techniques were used to develop model to estimate aboveground biomass (AGB). The root mean square error (RMSE) was used for measuring model bias, precision, and accuracy. The coefficient of determination (R 2 and adjusted [adj]-R 2), the Akaike Information Criterion (AIC) and the Schwarz Bayesian information Criterion was employed to select most appropriate models. Results: For the general total AGB models, adj-R 2 ranged from 0.71 to 0.85, and model 9 with diameter at stump height at 10 cm (DSH 10), ρ and crown width (CW) as predictor variables, performed best according to RMSE and AIC. For the merchantable stem models, adj-R 2 varied from 0.73 to 0.82, and model 8) with combination of ρ, diameter at breast height and height (H), CW and DSH 10 as predictor variables, was best in terms of RMSE and AIC. The results showed that a best-fit model for above-ground biomass of tree components was developed. AGB Stem = exp {-1.8296 + 0.4814 natural logarithm (Ln) (ρD 2 H) + 0.1751 Ln (CW) + 0.4059 Ln (DSH 30)} AGB Branch = exp {-131.6 + 15.0013 Ln (ρD 2 H) + 13.176 Ln (CW) + 21.8506 Ln (DSH 30)} AGB Foliage = exp {-0.9496 + 0.5282 Ln (DSH 30) + 2.3492 Ln (ρ) + 0.4286 Ln (CW)} AGB Total = exp {-1.8245 + 1.4358 Ln (DSH 30) + 1.9921 Ln (ρ) + 0.6154 Ln (CW)} Conclusions: The results demonstrated that the development of local models derived from an appropriate sample of representative species can greatly improve the estimation of total AGB.
... This classification of wood type based on WD can contribute to better forest management by defining methodologies and management practices applicable to each group [42]. Grouping these species and attempting to explain the different patterns of vertical density variability along the stem aids in understanding how this variable is interconnected with the life history strategies of trees and their ecological functions in the forest [19,[43][44][45][46]. Because WD is a determinant of biomass, it also affects the forest's role in carbon storage and the global climate. ...
... The patterns of vertical variability in the WD of the species evaluated in this study (Figures 4-6) align with previous findings [3,41,44,45]. When grouped by wood type, lowdensity-wood species (typically pioneers or early secondary species) tend to increase their WD towards the tree canopy [3] These species have a short lifespan [49,50] and require high growth rates in their early growth stages [19,43,51], initially producing low-density wood but later producing denser wood as growth rates decrease to maintain structural stability [45,52]. ...
... Vertical variability may be related to radial variation in the stem, and when analyzed together, these types of variation can better explain the trends of many species [15,17,26,44]. It was not possible to analyze radial variations in the present study, but this does not bias the results on vertical variation because the samples were taken in the form of complete disks (heartwood, sapwood, and bark). ...
Wood basic density (WD) plays a crucial role in estimating forest biomass; moreover, improving wood-density estimates is needed to reduce uncertainties in the estimates of tropical forest biomass and carbon stocks. Understanding variations in this density along the tree trunk and its impact on biomass estimates is underexplored in the literature. In this study, the vertical variability of WD was assessed along the stems of large trees that had a diameter at breast height (DBH) ≥ 50 cm from a dense ombrophilous forest on terra firme (unflooded uplands) in Acre, Brazil. A total of 224 trees were sampled, including 20 species, classified by wood type. The average WD along the stem was determined by the ratio of oven-dry mass to saturated volume. Five models were tested, including linear and nonlinear ones, to fit equations for WD, selecting the best model. The variation among species was notable, ranging from 0.288 g cm−3 (Ceiba pentandra, L., Gaertn) to 0.825 g cm−3 (Handroanthus serratifolius, Vahl., S. Grose), with an average of 0.560 g cm−3 (±0.164, standard deviation). Significant variation was observed among individuals, such as in Schizolobium parahyba var. amazonicum (H. ex D.), which ranged from 0.305 to 0.655 g cm−3. WD was classified as low (≤0.40 g cm−3), medium (0.41–0.60 g cm−3), and high (≥0.61 g cm−3). The variability in WD along the stem differs by wood type. In trees with low-density wood, density shows irregular variation but tends to increase along the stem, whereas it decreases in species with medium- and high-density wood. The variation in WD along the stem can lead to underestimations or overestimations, not only in individual trees and species but also in total stocks when estimating forest biomass. Not considering this systematic bias results in significant errors, especially in extrapolations to vast areas, such as the Amazon.
... The wood density (kg/m 3 ) was obtained for each species using eq. 2 (Aboal et al., 2005;Henry et al., 2010;Ribeiro et al., 2011;Zhu et al., 2010). ...
Studies addressing how different forest management methods affect the ecosystem services provided by forests in different geographical areas are essential. The objective of this study was to investigate how regulating and supporting services are affected by conservation management and differences in elevation. This was achieved by comparing several ecosystem indicators between the protected and unprotected areas. The forests under study were divided into two elevation ranges (1000-1500 and 1500-2000 m above sea level), and 66 sample plots (area 300 m 2) were established in each area. Quantitative and qualitative characteristics of the trees were recorded, and soil and litter samples were obtained in all sample plots. Increment cores were also obtained from the main tree species in the area. In addition, regulating services (regulation of CO 2 , water and soil) and supporting services (nutrient cycling in soil, and above-ground net primary production) were also evaluated. All of the indicators studied in the regulating services section, except annual carbon sequestration by the trees and the soil loss, in the protected were more than in the unprotected area. No significant differences between the two regions were observed regarding annual carbon sequestration and soil regulation indicators. Regarding the supporting services indicators, total nitrogen, assimilable potassium and average trunk volume of the trees were higher in the protected than in the unprotected area; the opposite was true for the total phosphorus index. The results suggest positive effects of conservation management on regulating and supporting services in the protected area of the Arasbaran forests. The findings of the study indicate that conservation management practices have a positive impact on both regulating and supporting services within the protected area of the Arasbaran forests. This suggests that the implementation of conservation measures in this region has resulted in beneficial outcomes for the ecosystem services provided by the forests. The results highlight the importance of protecting and managing forest areas to enhance their ability to regulate CO 2 , water, and soil, as well as support nutrient cycling and above-ground net primary production. These outcomes highlight the crucial role of conservation efforts in maintaining and enhancing the overall health and functioning of the Arasbaran forests. It indicates that protective management is essential for promoting key ecosystem services. The study also underscores the importance of considering factors such as altitude and habitat conditions when formulating forest management strategies or plans.
... The field measurement data for pantropical regions were mainly acquired from five widely used public data sets (Cannell, 1982;Falster et al., 2015;Jucker et al., 2017;Schepaschenko et al., 2017;Usoltsev, 2020) and compared with the original sources (Fayolle et al., 2013;Goodman et al., 2014;Henry et al., 2010;Vieilledent et al., 2012). The assessed regions cover or partly cover 25 countries in Africa, Central and South America, South and Southeast Asia, Northern Australia, and the southern part of East Asia (Figure 1). ...
Forest above‐ground biomass (AGB) is often estimated by converting the observed tree size using allometric scaling between the dry weight and size of an organism. However, the variations in biomass allocation and scaling between tree crowns and stems due to survival competition during a tree's lifecycle remain unclear. This knowledge gap can improve the understanding of modelling tree biomass allometry because traditional allometries ignore the dynamics of allocation.
Herein, we characterised allometric scaling using the dynamic ratio ( r ) of the stem biomass (SB) to AGB and a dynamic exponent. The allometric models were biologically parameterised by the r values for initial, intermediate and final ages rather than only a regression result. The scaling was tested using field measurements of 421 species and 2213 different‐sized trees in pantropical regions worldwide.
We found that the scaling fluctuated with tree size, and this fluctuation was driven by the trade‐off relationship of biomass allocation between the tree crown and stem depending on the dynamic crown trait. The allometric scaling between SB and AGB varied from 0.8 to 1.0 for a tree during its entire lifecycle. The fluctuations presented a general law for the allometric scaling of the pantropical tree biomass and size. Our model quantified the trade‐off and explained 94.1% of the allometric relationship between the SB and AGB (93.8% of which between D ² H and AGB) for pantropical forests, which resulted in a better fit than that of the traditional model. Considering the effects of the trade‐off on modelling, the actual biomass of large trees could be substantially greater than conventional estimates.
These results highlight the importance of coupling growth mechanisms in modelling allometry and provide a theoretical foundation for better describing and predicting forest carbon accumulation.
