Biomass,stem basic density and expansion factor functions for five exotic conifers grown in Denmark

Adequate allometric equations are needed for estimating carbon pools of fast growing tree species in relation to international reporting of CO₂ emissions and for assessing their possible contribution to increasing forest biomass resources. We developed models for predicting biomass, stem basic density and expansion factors of stem to above-ground biomass for five fast growing conifers. Data included destructive measurements of 236 trees from 14 sites, covering a wide range of growth conditions. To ensure model efficiency, models for predicting stem, crown and total above-ground biomass for the five species were estimated simultaneously using a linear, mixed effects model that allowed contemporaneous correlations between the different tree components. Models differed among species and included dbh and tree height. The models explained more than 98% of the variation in above-ground biomass and reflected differences in the allometry between tree species. Stem density differed among species but generally declined with increasing site index and dbh. The overall model for predicting stem basic density included dbh, H₁₀₀ and site index and explained 66% of the total variation. Expansion factors decreased from 1.8–2.0 in small trees (dbh < 10 cm) to 1.1–1.2 for large trees (dbh > 25 cm), but differed among species. The overall model explained 86% of the variation and included quadratic mean diameter and dbh.     

Relationships between diameter and height of trees in natural tropical forest in Tanzania

The relationship between tree height (h) and tree diameter at breast height (dbh) is an important element describing forest stands. In addition, h often is a required variable in volume and biomass models. Measurements of h are, however, more time consuming compared to those of dbh, and visual obstructions, rounded crown forms, leaning trees and terrain slopes represent additional error sources for h measurements. The aim of this study was therefore to develop h–dbh relationship models for natural tropical forest in Tanzania. Both general forest type specific models and models for tree species groups were developed. A comprehensive data set with 2 623 trees from 410 different tree species collected from a total of 1 191 plots and 38 sites covering the four main forest types of miombo woodland, acacia savanna, montane forest and lowland forests was applied. Tree species groups were constructed by using a k-means clustering procedure based on the h–dbh allometry, and a number of different non-linear model forms were tested. When considering the complexity of natural tropical forests in general and in particular variations of h–dbh relationships due to high species diversity in such forests, the model fit and performance were considered to be appropriate. Results also indicate that tree species group models perform better than forest type models. Despite the fact that the residual errors level associated with the models were relatively high, the models are still considered to be applicable for large parts of Tanzanian forests with an appropriate level of reliability.     

Lianas and self-supporting plants during tropical forest succession

Lianas (woody vines) are an important component of tropical forests, with a strong impact on forest dynamics, but their responses during forest succession have received relatively little attention. Here, we present an analysis of the changes in stem density, biomass, and species richness of lianas and self-supporting plants during tropical forest succession. We surveyed lianas ≥0.5 cm diameter at breast height (dbh) and self-supporting plants ≥2.5 cm dbh in 0.1 ha inventory plots in a chronosequence of 30 sites in northeastern Costa Rica, 23 sites on abandoned pastures 10–44 years of age, and seven sites in old-growth forest. Stem density of self-supporting plants showed no predictable chronosequence trend, but liana stem density declined significantly with forest age. Aboveground biomass of self-supporting vegetation increased rapidly during succession, with forests 31–44 years exhibiting higher levels of biomass than old-growth forests. Liana biomass accumulated more slowly, with the highest levels in old-growth sites. Species richness of self-supporting vegetation increased significantly during succession, but species richness of lianas showed no change or a slight decline with forest age, depending on the method of assessment. The differences between tree and liana responses during succession stem from the unique physiology and life history traits of lianas.     

Wood density,phytomass variations within and among trees,and allometric equations in a tropical rainforest of Africa

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 methodology and calculation procedures to assess biomass for tropical tree species of contrasted tree shapes in Africa, (2) to identify factors affecting within and between trees wood density, (3) to propose an allometric model that integrates these factors and (4) to evaluate the reliability of using generalized allometric equations in this type of forests. Models were developed to predict wood density and phytomass of the trees based on the harvesting of 42 trees from 16 species, representing three guild status in the wet evergreen forest of Boi Tano in Ghana. Results indicated that the wood density was highly influenced by the tree species, guild status, size of the tree and pith to bark distance. Dry mass of a tree was influenced by diameter at breast height, crown diameter and wood density. The wood density depends on the position of the wood within the tree and the guild status considered. The use of generalized allometric models in literature is limited by the specific climate zone, the consideration of tree height and species specific wood density. In considering those factors, using generalized allometric equations could result in an error of 3%. Further research should better consider the bigger trees and the influence of the topography and ecosystem history.     

Carbon stock measurements of a degraded tropical logged-over secondary forest in Manokwari Regency, West Papua, Indonesia

Several studies have been conducted in the past on carbon stock measurements in the tropical forests of Indonesia.This study is the first related research conducted in the New Guinea Island.In a degraded logged-over secondary forest in Manokwari Regency (West Papua,Indonesia),carbon stocks were measured for seven parts,i.e.,above-ground biomass (AGB),below-ground biomass (BGB),under-storey biomass (B u),necromass of dead leaves (N l),necromass of dead trees (N t),litter (L) and soil (S) using appropriate equations and laboratory analysis.Total carbon stocks were measured at 642.8 tC·ha-1 in the low disturbance area,536.9 tC·ha-1 in the moderate disturbance area and 490.4 tC·ha-1 in the high disturbance area.B u,N l and N t were not significant in the carbon stock and were collectively categorized as a total biomass complex.The carbon stock of litter was nearly equal to that of the total biomass complex,while the total carbon stock in the soil was eight times larger than the total biomass complex or the carbon stock of the litter.We confirmed that the average ratio of AGB and BGB to the total biomass (TB) was about 84.7% and 15.3%,respectively.Improvements were made to the equations in the low disturbance logged-over secondary forest area,applying corrections to the amounts of biomass of sample trees,based on representative commercial trees of category one.TB stocks before and after correction were estimated to be 84.4 and 106.7 tC·ha-1,indicating that these corrections added significant amounts of tree biomass (26.4%) during the sampling procedure.In conclusion,the equations for tree biomass developed in this study,will be useful for evaluating total carbon stocks,especially TB stocks in logged-over secondary forests throughout the Papua region.     

西非Sudanian热带林地11个树种地上生物量异速生长预测

Allometric models are necessary for estimating biomass in terrestrial ecosystems. Generalized allometric relationship exists for many tropical trees, but species- and region-specific models are often lacking. We developed species-specific allometric models to predict aboveground biomass for 11 native tree species of the Sudanian savanna-woodlands. Diameters at the base and at breast height, with species means ranging respectively from 11 to 28 cm and 9 to 19 cm, and the height of the trees were used as predictor variables. Sampled trees spanned a wide range of sizes including the largest sizes these species can reach. As a response variable, the biomass of the trees was obtained through destructive sampling of 4 754 trees during wood harvesting. We used a stepwise multiple regression analysis with backward elimination procedure to develop models separately predicting, total biomass of the trees, stem biomass, and biomass of branches and twigs. All species-specific regression models relating biomass with measured tree dimensions were highly significant (p < 0.001). The biomass of branches and twigs was less predictable compared to stem biomass and total biomass, although their models required fewer predictors and predictor interactions. The best-fit equations for total above-ground biomass and stem biomass had R ² > 0.70, except for the Acacia species; for branches including twig biomass, R²-values varied from 0.749 for Anogeissus leiocarpa to 0.183 for Acacia macrostachya. The use of these equations in estimating available biomass will avoid destructive sampling, and aid in planning for sustainable use of these species.     

Tree height in Brazil's ‘arc of deforestation’: Shorter trees in south and southwest Amazonia imply lower biomass

This paper estimates the difference in stand biomass due to shorter and lighter trees in southwest (SW) and southern Amazonia (SA) compared to trees in dense forests in central Amazonia (CA). Forest biomass values used to estimate carbon emissions from deforestation throughout, Brazilian Amazonia will be affected by any differences between CA forests and those in the “arc of deforestation” where clearing activity is concentrated along the southern edge of the Amazon forest. At 12 sites (in the Brazilian states of Amazonas, Acre, Mato Grosso and Pará) 763 trees were felled and measurements were made of total height and of stem diameter. In CA dense forest, trees are taller at any given diameter than those in SW bamboo-dominated open, SW bamboo-free dense forest and SA open forests. Compared to CA, the three forest types in the arc of deforestation occur on more fertile soils, experience a longer dry season and/or are disturbed by climbing bamboos that cause frequent crown damage. Observed relationships between diameter and height were consistent with the argument that allometric scaling exponents vary in forests on different substrates or with different levels of natural disturbance. Using biomass equations based only on diameter, the reductions in stand biomass due to shorter tree height alone were 11.0, 6.2 and 3.6%, respectively, in the three forest types in the arc of deforestation. A prior study had shown these forest types to have less dense wood than CA dense forest. When tree height and wood density effects were considered jointly, total downward corrections to estimates of stand biomass were 39, 22 and 16%, respectively. Downward corrections to biomass in these forests were 76 Mg ha⁻¹ (∼21.5 Mg ha⁻¹ from the height effect alone), 65 Mg ha⁻¹ (18.5 Mg ha⁻¹ from height), and 45 Mg. ha⁻¹ (10.3 Mg ha⁻¹ from height). Hence, biomass stock and carbon emissions are overestimated when allometric relationships from dense forest are applied to SW or SA forest types. Biomass and emissions estimates in Brazil's National Communication under the United Nations Framework Convention on Climate Change require downward corrections for both wood density and tree height.     

杉木萌芽纯林与混交林生长量及经济效益的研究

在杉木林采伐迹地上,通过不炼山、套种火力楠与深山含笑,进行杉木萌芽纯林与混交林的对比试验,9a试验结果表明:混交林中杉木的平均胸径、树高、单株材积、地上部分单株生物量分别比杉木萌芽纯林增加4 04%、8 75%、16 3%、1 43%;混交林中火力楠和深山含笑生长良好,混交林总蓄积量和乔木层地上部分总生物量分别为杉木纯林的1 47倍和1 32倍;混交林的投入产出比高于杉木萌芽纯林,说明本模式是恢复和提高杉木连栽地土壤生产力的可行方法。     

王朗自然保护区引种竹笋：幼竹期异速生长规律的研究

本文以王朗1985年大熊猫主食竹类引种试验以来,筛选出的四个适应性最强的种:石棉玉山竹(Yushania lineolata)、青川箭竹(Fargesia rufa)、糙花箭竹(Fargesia scabrida)和冷箭竹(Bashania fangiana)及本地缺苞剪竹(Fargesia denudata)作材料,研究了各竹种当年生笋、一年生幼竹和二年生成竹的秆、枝、叶、箨和单株间以及与竹笋——幼竹期高径(D~2H)生长间的异速生长常数K的变化规律,建立了数学模型,并对竹笋到一年生幼竹的各器官(组分)的K值进行相关性研究,探讨在竹笋——幼竹期K值的变化规律。另外还根据笋秆K_s值与缺苞箭竹比较,确定各竹种竹笋——幼竹期的长短及进入稳定加固期的时间,评价各竹种的适应性能力。结果表明:笋期秆异速生长最显著的是糙花箭竹,顺次为石棉玉山竹、青川箭竹和冷箭竹。一年生幼竹器官异迷生长缺苞箭竹向多枝性发展,青川箭竹枝与秆之间生长近似于线性关系,秆、枝、叶和单株间成均衡性生长,而石棉玉山竹、糙花箭竹和冷箭竹则向少枝大秆型发展。单株生物量累积速度的主要因子是叶的生长,其次是秆、枝。二年生成竹的K值出现明显的变化,各竹种经竹笋——幼竹期进入稳定加固期的时间是不同的,石棉玉山竹和青川箭竹一般为1—2年,糙花箭竹和冷箭竹约为2—3年。竹笋——幼竹期K值因种和不同生长年龄而发生变化。笋期(秆、单株)生长速度与其笋成竹的秆、枝、叶和单株K值成负相关,但是笋期异速生长越快,则竹笋——幼竹期越长,进入稳定加固期较晚。对于可塑性强, 较为敏感的竹笋——幼竹来说,时间经历越长,对环境的生态适应能力将会变大。生产实践中,可用笋期秆异速生长常数K_s的大小来确定各竹种其笋进入幼竹和成年稳定后的适应能力及适应程度。表中的数字模型可用来预测生物量。     

Development of equations for predicting Puerto Rican subtropical dry forest biomass and volume

Carbon accounting, forest health monitoring and sustainable management of the subtropical dry forests of Puerto Rico and other Caribbean Islands require an accurate assessment of forest aboveground biomass (AGB) and stem volume. One means of improving assessment accuracy is the development of predictive equations derived from locally collected data. Forest inventory and analysis (FIA) measured tree diameter and height, and then destructively sampled 30 trees from 6 species at an upland deciduous dry forest site near Ponce, Puerto Rico. This data was used to develop best parsimonious equations fit with ordinary least squares procedures and additive models fit with nonlinear seemingly unrelated regressions that estimate subtropical dry forest leaf, woody, and total AGB for Bucida buceras and mixed dry forest species. We also fit equations for estimating inside and outside bark total and merchantable stem volume using both diameter at breast height (d.b.h.) and total height, and diameter at breast height alone for B. buceras and Bursera simaruba. Model fits for total and woody biomass were generally good, while leaf biomass showed more variation, possibly due to seasonal leaf loss at the time of sampling. While the distribution of total AGB into components appeared to remain relatively constant across diameter classes, AGB variability increased and B. simaruba and B. buceras allocated more carbon into branch biomass than the other species. When comparing our observed and predicted values to other published dry forest AGB equations, the equation developed in Mexico and recommended for areas with rainfall >900 mm/year gave estimates substantially lower than our observed values, while equations developed using dry forest data from forest in Australia, India and Mexico were lower than our observed values for trees with d.b.h. <25 cm and slightly higher for trees with d.b.h. >30 cm. Although our ability to accurately estimate merchantable stem volume and live tree AGB for subtropical dry forests in Puerto Rico and other Caribbean islands has been improved, much work remains to be done to sample a wider range of species and tree sizes.     

Allometric biomass equations for tree species used in agroforestry systems in Uganda

Estimates of above-ground biomass are required for better planning, sustainable management and monitoring of changes in carbon stocks in agroforestry systems. The objective of this study was to develop and compare biomass equations for Markhamia lutea, Casuarina equisetifolia, Maesopsis eminii and Grevillea robusta grown in a linear simultaneous agroforestry system in Uganda. These species were established in single rows in the middle of fields in 1995 from four-month old seedlings. A total of 57 trees were sampled for this study, 13 for M. lutea, 12 for C. equisetifolia, 16 for M. eminii and 16 for G. robusta. Biomass values of the various tree components (stem, branches and foliage) as well as the total above-ground biomass were fitted to linear and non-linear allometric models using total height, diameter-at-breast height (DBH), crown width as predictor variables. Although both DBH and height are typically used as independent variables for predicting above-ground biomass, the addition of height in biomass equations did not significantly improve model performance for M. eminii, M. lutea and G. robusta. However, addition of height significantly increased the proportion of variation explained in above-ground biomass for C. equisetifolia, while DBH did not significantly improve the prediction of biomass. The study confirmed the need for developing species-specific biomass equations.     

Vegetation competition effects on aboveground biomass and macronutrients,leaf area,and crown structure in 5-year old Douglas-fir

Vegetation control (VC) in forest plantations often increases growth of crop trees but can also affect biomass and nutrient partitioning to tree components. We examined above-ground biomass and macronutrients, leaf area and crown structure in 5-year old Douglas-fir (Pseudotsuga menziessi (Mirb.) Franco) growing with VC and with no vegetation control (NVC) in coastal Washington, United States of America. Trees in VC had larger stem, branch, foliage and total biomass than trees of equal stem diameter at 1.3 m above ground in NVC. The difference in component biomass between treatments was in the order: branch > foliage > stem. Trees in the VC regime did not differ in macronutrient concentration in stem, branch and foliage except for branch N which was greater in NVC than in VC. Differences in tree macronutrient stores between VC and NVC ranged from 2.2 times for Mg to 2.6 times for N and K. The relationship between stem diameter and leaf area was linear in both VC treatments. The relationship between stem diameter and foliage biomass was curvilinear for both VC treatments. Results of this study support the need for separated allometric equations to estimate biomass for young Douglas-fir growing in areas with and without VC.     

Allometric equations for biomass estimations in Cameroon and pan moist tropical equations including biomass data from Africa

Moist tropical forests in Africa and elsewhere store large amounts of carbon and need accurate allometric regressions for their estimation. In Africa the absence of species-specific or mixed-species allometric equations has lead to broad use of pan moist tropical equations to estimate tree biomass. This lack of information has raised many discussions on the accuracy of these data, since equations were derived from biomass collected outside Africa.     

Comparison of allometric equations and biomass expansion factors for six evergreen broad-leaved trees in subtropical forests in southern Korea

This study was conducted to compare the allometric equations and biomass expansion factors (BEFs) of six dominant evergreen broad-leaved trees (Camellia japonica L, Castanopsis sieboldii Hatus, Quercus acuta Thunb, Q. glauca Thunb, Machilus thunbergii S. et Z., and Neolitsea sericea Koidz) in subtropical forests. A total of 86 trees were destructively sampled to quantify the aboveground biomass of each tree component (i.e., leaves, branches, and stem). Species-specific or generalized allometric equations and species-dependent BEFs were developed for each tree component of the six broad-leaved forest trees. Species-specific allometric equations were significant (P < 0.05), with the diameter at breast height (DBH) accounting for 68–99% of the variation, whereas generalized allometric equations explained 64–96% of the variation. The values of stem density ranged broadly from 0.49 g cm^?3 for C. sieboldii to 0.79 g cm^?3 for Q. glauca, with a mean value of 0.68 g cm^?3. The BEFs were significantly (P < 0.05) lower for C. sieboldii (1.25) than for M. thunbergii (2.02). Stem density and aboveground BEFs had a significant negative relationship with tree ages. The results indicate that species-specific allometric equations and species-dependent BEFs are applicable for obtaining accurate biomass estimates of subtropical evergreen broad-leaved forests.     

Developing general allometric relationships for regional estimates of carbon sequestration—an example using Eucalyptus pilularis from seven contrasting sites

General non-site-specific allometric relationships are required for the conversion of forest inventory measurements to regional scale estimates of forest carbon sequestration. To determine the most appropriate predictor variables to produce a general allometric relationship, we examined Eucalyptus pilularis aboveground biomass data from seven contrasting sites. Predictor variables included diameter at breast height (dbh), stem volume, dbh² × H, dbh × H and height (H). The data set contained 105 trees, ranging from 6 to over 20,000 kg tree⁻¹, with dbh ranging from 5 to 129 cm. We observed significant site differences in (1) partitioning of biomass between the stem, branch wood and foliage; (2) stem wood density and (3) relationship between dbh and height. For all predictor variables, site had a significant effect on the allometric relationships. Examination of the model residuals of the site-specific and general relationship indicated that using dbh alone as the predictor variable produced the most stable general relationship. Furthermore, the apparent site effect could be removed by the addition of a constant value to the measured diameter (dbh + 1), to account for the differing diameter distribution across the seven sites. Surprisingly, the inclusion of height as a second predictor variable decreased the performance of the general model. We have therefore demonstrated that for E. pilularis a general allometric relationship using dbh alone as the predictor variable can be as accurate as site-specific allometry, whilst being applicable to a wide range of environments, management regimes and ages. This simplifies regional estimates of aboveground biomass from inventory measurements, eliminating the need for site-specific allometric relationships or modifiers such as height, wood density or expansion factors.     

Additive biomass equations for small diameter trees of temperate mixed deciduous forests

The carbon stored in small diameter trees of temperate forests has been ignored in most studies and there is a lack of biomass equations for this component of forests. We harvested nine main tree species at sapling stage (dbh?相似文献   

Assessment of Carbon Balance in Community Forests in Dolakha, Nepal

This study assessed the net above-ground carbon stock in six community forests in the Dolakha district, Nepal. A survey was conducted of above-ground timber species, using random sampling. A tree-ring chronology for Pinus roxburghii was created to construct a growth model representative of the various mainly-pine species. The allometric model combined with tree ring analysis was used to estimate carbon stock and annual growth in the above-ground tree biomass. The out-take of forest biomass for construction material and fuelwood was estimated on the basis of interviews and official records of community forest user groups. The average annual carbon increment of the community forests was 2.19 ton/ha, and the average annual carbon out-take of timber and fuelwood was 0.25 ton/ha. The net average carbon balance of 1.94 ton/ha was equivalent to 117.44 tons of carbon per community forest annually. All the community forests were actively managed leading to a sustainable forest institution, which acts as a carbon sink. It is concluded that community forests have the potential to reduce emissions by avoiding deforestation and forest degradation, enhance forest carbon sink and improve livelihoods for local communities.     

Allometric relationships predicting foliar biomass and leaf area:sapwood area ratio from tree height in five Costa Rican rain forest species

We developed allometric equations to predict whole-tree leaf area (A(l)), leaf biomass (M(l)) and leaf area to sapwood area ratio (A(l):A(s)) in five rain forest tree species of Costa Rica: Pentaclethra macroloba (Willd.) Kuntze (Fabaceae/Mim), Carapa guianensis Aubl. (Meliaceae), Vochysia ferru-gi-nea Mart. (Vochysiaceae), Virola koshnii Warb. (Myris-ticaceae) and Tetragastris pana-mensis (Engl.) Kuntze (Burseraceae). By destructive analyses (n = 11-14 trees per species), we observed strong nonlinear allometric relationships (r(2) >/= 0.9) for predicting A(l) or M(l) from stem diameters or A(s) measured at breast height. Linear relationships were less accurate. In general, A(l):A(s) at breast height increased linearly with tree height except for Penta-clethra, which showed a negative trend. All species, however, showed increased total A(l) with height. The observation that four of the five species increased in A(l):A(s) with height is consistent with hypotheses about trade--offs between morphological and anatomical adaptations that favor efficient water flow through variation in the amount of leaf area supported by sapwood and those imposed by the need to respond quickly to light gaps in the canopy.     

Changes in above- and belowground biomass in early successional tropical secondary forests after shifting cultivation in Sarawak,Malaysia

Uncertainties in the rate of biomass variation with forest ageing in tropical secondary forests, particularly in belowground components, limit the accuracy of carbon pool estimates in tropical regions. We monitored changes in above- and belowground biomass, leaf area index (LAI), and biomass allocation to the leaf component to determine the variation in carbon accumulation rate with forest age after shifting cultivation in Sarawak, Malaysia. Nine plots in a 4-year-old forest and fourteen plots in a 10-year-old forest were monitored for 5 and 7 years, respectively. Forest and plant part biomass were calculated from an allometric equation obtained from the same forest stands. Both above- and belowground biomass increased rapidly during the initial decade after abandonment. In contrast, a much slower rate of biomass accumulation was observed after the initial decade. LAI also increased by approximately double from the 4-year-old to 10-year-old forest, and then gently increased to the 17-year-old forest. We also found that allocation variation in leaf biomass and nitrogen was closely related to the rate of biomass accumulation as a forest aged. During the first decade after abandonment, a high biomass and nitrogen allocation to the leaf component may have allowed for a high rate of biomass accumulation. However, reduction in those allocations to leaf component after the initial decade may have helped to suppress the biomass accumulation rate in older secondary forests. Roots accounted for 14.0–16.1% of total biomass in the 4–17-year-old abandoned secondary forests. We also verified the model predicted values for belowground biomass by Cairns et al. (1997) and Mokany et al. (2006), although both models overestimated the values throughout our data sets by 45–50% in the 10-year-old forest. The low root:shoot ratio in the secondary forests may have caused this overestimation. Therefore, our results suggest that we should modify the models to estimate belowground biomass considering the low root:shoot ratio in tropical secondary forests.     

乐昌含笑造林试验及效果分析

对福建省邵武市桂林乡乐昌含笑人工林进行调查,结果表明:8年生乐昌含笑与杉木1∶1混交林的乐昌含笑和杉木胸径、树高年均生长量、单株材积及总蓄积量均大于各自纯林。不同坡位9年生乐昌含笑人工纯林的胸径、树高及蓄积生长量均以下坡林分为最高,表现为:下坡>中坡>上坡。8年生乐昌含笑和杉木人工纯林的平均木生物量分别为31.55 kg和33.74kg;乔木层生物量分别为41.73 t.hm-2和45.55 t.hm-2;地上部分生物量的比例分别为94.28%和96.85%,灌木层和草本层所占比例较少;乐昌含笑和杉木平均木生物量各器官的比例分别表现为:干>根>枝>叶>皮、干>根>叶>枝>皮。