碳达峰碳中和目标下木材工业的发展路径分析

木材工业是能源消耗少、环境污染小的绿色低碳产业。在国家碳达峰碳中和目标的指引下,木材工业迎来重要发展机遇期,同时也面临一定挑战。本文深入分析木材和木制品的固碳效果以及木结构建筑的碳减排贡献,并针对木材工业存在的不足之处,从木材资源供给、能源消费结构、碳计量标准、碳排放基础研究、绿色低碳加工技术创新、木材和木制品的储碳周期、人才培养和宣传推广等方面提出具体发展路径。     

木材固碳量与含碳率研究进展

木材碳学是近年来兴起的一门科学,其主要研究内容包括木材碳素的储存量、木材储能、人工林木材固碳增汇与优质木材培育技术及木质产品固碳延伸等方面。文中简述了木材碳学研究中木材固碳量与含碳率、木材固碳量的影响因素、木材固碳量与木材热值的关系以及木质材料固碳量和固碳延伸等方面的研究现状,并对今后的研究方向进行了展望。     

清洁发展机制碳基金造林综述

今年,世界银行生物碳基金的清洁发展机制造林、再造林项目,在苍梧县和环江县实施。项目来自世行碳基金,旨在"通过造林碳吸收,出售碳汇以及木材和其它非木质林产品收益,增加当地农民和社区的收入","保护生物多样性"。笔者就清洁发展机制的背景、由来、规则和在我国实施的意义作简要综述。     

木材细胞中二氧化硅的吸收、运输与聚积

硅石在很多木材细胞中都可见(如紫果冷杉、樟科等),它与木材本身构成了一种复合材料即木材/无机质复合材,使木材的物理力学性能得以改善,克服了木材自身的一些缺陷(如易腐、易燃、尺寸不稳定性、各向异性等).作者根据前人对木材细胞中二氧化硅(SiO2)的分布、形态和含量的初步分析,归纳总结木材细胞中二氧化硅(SiO2)的形成过程及其影响因素即木材细胞中SiO2的吸收、运输及聚积,影响木材细胞中SiO2的吸收、运输及聚积的因素,为进一步研究木材细胞中硅生物矿化的形成过程做准备.     

国外林业科技文摘11则

一种测定木材水分及密度分布的新仪器在林产品研究中，木材内部水分及密度分布的测定具有重要意义，过去常用的仪器和方法有多种。最近研制了一种自动化仪器，可以方便地测定木材样品的水分和密度分布状况。这种自动化仪器采用了狭窄的Y一射线光束，对放置在传输带上的木材样品进行照射。水分含量的测定是根据241Am（钼）光子的吸收技术，即通过测定于、湿木材样品的线性吸收系数的差异来确定其含水量。这种方法不需考虑木材的厚度。密度是根据木材的衰减系数的测定来确定。这种仪器的优点是操作简便，测定的结果准确，不损坏木材，可测定…     

产业园区碳储量及生物因子关系研究——以杭州青山湖科技城为例

基于生态经济协调发展的视角,对杭州青山湖科技城园区植物进行了实地调查,采用生物量扩展因子法和统计分析法对科技城核心区云制造小镇内不同绿地类型植物碳储量进行了研究,并分析了碳储量与生物因子之间的关系。结果表明:云制造小镇公园绿地碳密度为55.19t/hm~2,道路绿地碳密度为40.76t/hm~2,水土保持林碳密度为67.59t/hm~2;对乔木、灌木碳储量影响最大的生物因子是种植密度,最小的是木材密度,乔木高度对碳储量的影响程度要大于胸径的影响程度,灌木则与乔木相反;园区碳储量较高的树种为:水杉、马尾松、无患子、银杏和香樟。     

褐腐对白杨木材固碳量的影响规律及机理

研究腐朽对木材固碳量的影响规律,揭示固碳量变化的内在机理,可为木材固碳减排及木材防腐提供理论依据。当前关于腐朽对木材碳排放的影响鲜有报道,缺乏相应的量化数据。采用褐腐菌(密粘褶菌,G.t)对白杨木材试件进行为期90 d的生物腐朽试验与分析。腐朽培养期间,在不同培养周期(间隔15 d)取出试件并测定其固碳量与化学成分数值,分析腐朽时间对固碳量及各化学成分的影响,研究固碳量变化规律并基于各化学成分的变化探讨固碳量的变化机理。结果表明:1)随腐朽时间增加,绝对固碳量(固碳量实测值)不降反而小幅上升,相对固碳量(相对于腐朽前木材原始质量来说,单位质量木材含有的固碳量)显著下降,表明褐腐对木材固碳量变化具有显著影响(R2=0.983,P 0.01);2)随腐朽时间增加,木材试样内木质素绝对含量和占比均小幅上升,综纤维素(包括α-纤维素和半纤维素)绝对含量和占比均明显下降。由于单位质量木质素含碳率64.08%大于综纤维素37.38%,导致木材内绝对固碳量产生了不降反升的现象。总之,褐腐过程中木质素比重变化是影响木材绝对固碳量变化的决定因素,质量损失率是影响木材相对固碳量变化的决定因素。该研究着眼于木材腐朽和木材固碳两个方面,系统分析了褐腐过程中随腐朽程度加深,白杨木材固碳量的变化规律和内在机理,为木材固碳减排及木材防腐积累了基础数据。     

低碳经济视角下木材工业的发展展望

探讨了低碳经济发展背景下木材工业的经济角色,以及木材工业在替代高碳释放材料、延长木质林产品碳储存期和节能降耗方面的技术途径,提出了木材工业在纤维资源配置、建筑领域拓展和废弃木质资源碳贸易三个重点方向的经济技术策略。     

非破坏性木材内部缺陷检测--木材CT扫描研究动态

对断层扫描技术(CT)在木材工业中应用的可行性,以及在木材工业中实际应用之前需要解决的问题进行了探讨.针对木材CT图象的各种处理方法,以及各国目前在该领域的研究动态进行了回顾.将CT技术引进木材工业,将使锯材和单板生产的价值最优化成为可能.     

CT技术在木材科学中的应用

CT技术作为一种先进的无损检测方法已在木材构造检测和物理性能评价领域得到广泛利用,逐渐成为木材科学领域中一种重要的检测方法。文中介绍了CT技术的基本原理,综述了普通医学CT和工业CT检测木材宏观构造、密度,以及利用高分辨率CT研究木材微观结构的研究进展,并展望了CT技术在木材科学领域的应用前景。     

Variation in growth,wood density and carbon concentration in five tree and shrub species in Niger

There is little information about variation in growth, wood density and carbon concentration in native tree and shrub species in Africa. This information is needed to make realistic projections about carbon sequestration of different species in different environments. Farmers manage natural regeneration of many native species in the drylands of Niger, so there is interest in carbon sequestration potential of the species. The objectives of this study were to determine: (1) if tree height, stem diameter, mean ring width, wood density and carbon concentration differ among five tree and shrub species (Combretum glutinosum, Combretum micranthum, Combretum nigricans, Guiera senegalensis, Piliostigma reticulatum) in Niger; (2) if variation within species is affected by land use type (parkland agroforests, woodlands), soil type (sandy, rocky), terrain type (temporarily flooded, flat, hill slope) and mean annual rainfall; and (3) if growth variables, wood density and carbon concentration are correlated in the five species. Environmental variables did not have strong effects on growth and wood variables of the species, and some effects differed among species. Height across species increased with mean annual rainfall. Stem diameter and mean ring width across species were greater in parkland agroforests than in woodlands. Carbon concentration was positively correlated with growth variables of four species, but was not correlated with wood density in most species. Correlations between wood density and growth differed in sign among some species. We conclude that above-ground carbon sequestration per tree probably increases with mean annual rainfall and is greater in parkland agroforests than in woodlands.     

Comparison of uncertainties in carbon sequestration estimates for a tropical and a temperate forest

We compare uncertainty through sensitivity and uncertainty analyses of the modelling framework CO2FIX V.2. We apply the analyses to a Central European managed Norway spruce stand and a secondary tropical forest in Central America. Based on literature and experience we use three standard groups to express uncertainty in the input parameters: 5%, 10% and 20%. Sensitivity analyses show that parameters exhibiting highest influence on carbon sequestration are carbon content, wood density and current annual increment of stems. Three main conclusions arise from this investigation: (1) parameters that largely determine model output are stem parameters, (2) depending on initial state of the model, perturbation can lead to multiple equilibrium, and (3) the standard deviation of total carbon stock is double in the tropical secondary forest for the wood density, and current annual increment. The standard deviation caused by uncertainty in mortality rate is more than 10-fold in the tropical forest case than in the temperate managed forest. Even in a case with good access to data, the uncertainty remains very high, much higher than what can reasonably be achieved in carbon sequestration through changes in forest management.     

Variability of selected wood characteristics in 40 half-sib families of black spruce (Picea mariana)

Summary Based on 15-year-old black spruce (Picea mariana) trees from 40 half-sib families sampled from 9 blocks of a family test in New Brunswick, this study examined intertree and intratree variation in various wood density and ring width characteristics. Of various variance components of the intertree variation, a remarkable variance component due to family was found in wood density characteristics (viz. average wood density, average earlywood density and latewood density of the tree), and these characteristics are thus under strong genetic control (h _i ² ranging from 0.60 to 0.86, and h _f ² from 0.56 to 0.68). It, to a lesser extent, applies to ring width characteristics at the tree level (viz. average ring width, and average earlywood width, latewood width and latewood percent of the tree) that show a lower heritability (h? from 0.18 to 0.28, and h _f ² from 0.22 to 0.36). Both block and block × family interaction contribute little to the total intertree variation encountered in 40 families from 9 blocks, while tree-to-tree variation within the family accounts for most (over 3/4) of the total intertree variation.Compared to the intertree variation (tree-to-tree variation within the family), the intratree variation in various wood characteristics studied is considerably larger in this species. It appears that most intraring wood density characteristics show a relatively smaller intertree variation but a relatively larger intratree variation as compared to ring width characteristics (except latewood width and latewood percent). Latewood width and latewood percent show the smallest intertree variation and the largest intratree variation. Between the two sources of the radial intratree variation, cambial age explains much more variation in most intraring wood density characteristics, while ring width accounts for more variation in earlywood width, latewood width and intraring density variation. This indicates that wood density of growth rings in this species is dependent more on cambial age than ring width (growth rate). Among various wood density and ring width characteristics studies, maximum (latewood) density shows the strongest response to calendar year. This characteristics is thus a useful dendroclimatic parameter in this species.I would like to thank Dr. E.K. Morgenstern and Mr. D. Simpson for their involvement in the planning of this study. Thanks are also due to G. Chauret, T. Keenam, R. Ploure, V. Steel and C. Reitlingshoefer for their technical assistance     

Carbon,Fossil Fuel,and Biodiversity Mitigation With Wood and Forests

Life-cycle analyses, energy analyses, and a range of utilization efficiencies were developed to determine the carbon dioxide (CO₂) and fossil fuel (FF) saved by various solid wood products, wood energy, and unharvested forests. Some products proved very efficient in CO₂ and FF savings, while others did not. Not considering forest regrowth after harvest or burning if not harvested, efficient products save much more CO₂ than the standing forest; but wood used only for energy generally saves slightly less. Avoided emissions (using wood in place of steel and concrete) contributes the most to CO₂ and FF savings compared to the product and wood energy contributions. Burning parts of the harvested logs that are not used for products creates an additional CO₂ and FF savings. Using wood substitutes could save 14 to 31% of global CO₂ emissions and 12 to 19% of global FF consumption by using 34 to 100% of the world’s sustainable wood growth. Maximizing forest CO₂ sequestration may not be compatible with biodiversity. More CO₂ can be sequestered synergistically in the products or wood energy and landscape together than in the unharvested landscape. Harvesting sustainably at an optimum stand age will sequester more carbon in the combined products, wood energy, and forest than harvesting sustainably at other ages.     

Growing common plantation tree species in Kenya for sale of carbon and wood supply: what is the best bet?

The introduction of carbon finance as an incentive in forestry farming has a potential of increasing the amount of carbon sequestered. However, this has created a daunting task among investors in forestry to optimise the joint production of wood and carbon sequestration. For instance, investors might find it profitable to give up some timber returns in exchange for carbon credits. This study evaluated expected income from growing Cupressus lusitanica Mill., Pinus patula Schiede ex Schltdl. & Cham., Eucalyptus saligna Sm. and Juniperus procera Hochst. ex Endl. for wood and/or the carbon market in central Kenya. The global average unit price of carbon and stumpage royalty were used to estimate expected returns from sale of carbon credits and wood, respectively. There were significant differences (p < 0.01) in the expected amount of income from sale of carbon and wood among the four species. Specifically, at economic rotation of 30 years with stand density of 532 trees ha^?1 P. patula and C. lusitanica yielded US$28 050 and US$23 650, respectively, from sale of carbon compared with US$59 000 and US$51 000, respectively, from sale of wood. This was twice the value investors receive from clear-felling as compared with sales from carbon. Similarly, at economic rotation of 33 years with stand density of 150 trees ha^?1, a forest investor in E. saligna would earn US$15 400 from sale of carbon compared with US$33 000 from sale of wood. Overall, the amount expected to be realised from sale of carbon was lower compared with that from sale of wood. This demonstrates that the price dynamics of carbon offsets in the voluntary and the compliance markets need to remain competitive and attractive for the forest owners to give up some timber returns in exchange for carbon income or to modify forest management regulation in order to increase carbon sequestration.     

Development of a method for sorting picea abies pulp wood with respect to basic density

The basic density of pulp wood can be used to convert green volume to dry weight, and as an indicator of the fibre quality. Because the methods for measuring basic density are cumbersome, a practical, on‐line method for sorting Norway spruce pulp wood with respect to basic density was developed. The relationship between mean annual ring width and basic density was used to sort the pulp wood. Brief visual inspection could separate piles of logs with different mean annual ring widths from each other with an acceptable precision. The resulting classes had significantly different mean basic densities (380, 400 and 434 kg m^?3). Means of other properties, such as juvenile wood content, heartwood content, and dry matter content, also differed among classes.     

Inter-tree and intra-tree variations in ring width and wood density components in balsam fir (Abies balsamea)

This study quantified and compared intra-tree and inter-tree variations in ring width and wood density components in balsam fir (Abies balsamea) grown in Quebec, Canada. In addition, the study examined correlations between ring width and wood density components at different stem positions from the stump level to the stem top. Ring width and wood density components of individual rings were measured by X-ray densitometry. Both the intra- and inter-tree variations in balsam fir are large, but the inter-tree variation is relatively smaller than the intra-tree variation. Much of the intra-tree variation is due to the radial variation, whereas the axial variation is much smaller. Compared to ring width and its components, wood density characteristics show a considerably smaller variation at both the inter- and intra-tree level. In almost all wood characteristics studied (except for latewood width), the intra- and inter-tree variations are more or less influenced by tree age. Cambial age explains more intra-tree variation in wood density components than ring width, whereas more intra-tree variation in ring width components is due to ring width. Cambial age and ring width explain a comparable percentage of variation in ring density. Only a few of the correlations between ring width and wood density components vary significantly with stem position from the stump to the stem top at the inter-tree level. In balsam fir, a negative correlation between ring density and ring width is significant in the butt log, but the correlation decreases to an insignificant level at and above a height of 3.0 m.     

Volume growth and wood density of plus tree progenies of Pinus contorta in two Swedish field trials

Seventy‐four half‐sib families of lodgepole pine (Pinus contorta ssp. latifolia Engelm.) plus trees were measured for vigour, height growth, stem diameter, wood density and ring width in two Swedish field trials at age 9. Height growth, wood density and ring width differed between families within provenances with variance components of 3–8 %. Coefficients of variation were highest for height growth and lowest for ring width. Heritabilities were similar for height growth and wood density but lower for ring width. These genetic parameters seemed to be equal for all provenances. Indirect selection for high dry stem biomass was more effective using height growth than wood density, and a correlated response in wood density of 2.1 % of mean by selecting the 15 highest parent trees was indicated. Juvenile wood density looks uncertain as a selection criterion for mature wood density.     

Genetic correlations between wood quality traits of <Emphasis Type="Italic">Pinus pinaster</Emphasis> Ait

• ? It is essential to understand how characteristics are related to each other in breeding programmes to select wood properties, in order to avoid that, in selecting for one trait, we are negatively affecting another. Moreover, measuring wood properties is time consuming and expensive.
• ? This study assesses genetic and phenotypic correlations between wood density components and spiral grain of 46 half-sib families of Pinus pinaster in seventeen-year-old trees.
• ? Results showed that genetic correlations for all wood density components were higher than corresponding phenotypic correlations. Furthermore, all wood density components were highly genetically correlated with ring density, and also closely associated among themselves. Results showed a higher genetic correlation of ring density with earlywood density (r _g = 0.96) than with latewood density r _g = 0.79). A moderate to high positive genetic correlation was found between spiral grain and wood density characteristics (0.29–0.61).
• ? We conclude that ring density (overall wood density) can be improved by increasing either earlywood density, latewood percent, or both of these traits, and spiral grain can be modify in future plantations.

     

Modeling effects of soil,climate, and silviculture on growth ring specific gravity of Douglas-fir on a drought-prone site in Western Washington

Because wood specific gravity (SG), also known as relative or basic density, is correlated with many physical and mechanical properties it is a widely used indicator of wood quality. Furthermore, because SG measures dry weight per unit green volume and dry wood contains about 49% carbon and 20 MJ/kg energy, SG is useful for converting tree volume to carbon and energy content equivalents. Although many studies have investigated variables affecting SG, few have developed models to predict SG at the local level from age, silvicultural treatment, and growing environment variables. This study developed a four-parameter logistic model with mixed effects to predict the specific gravity of annual growth rings (RSG) from forty six 76-year-old Douglas-fir (Pseudotsuga menziesii, Mirb. Franco) trees sampled from a thinning and biosolids fertilization experiment on a drought-prone site in Western Washington. RSG for up to sixty rings per tree was measured with X-ray densitometry on strips taken from disks removed from the top of the first 5 m log. Inter-annual RSG was modeled using treatment variables; local temperature, precipitation, and soil moisture deficit as growing environment variables; and ring number, area, width, and radius to the ring as tree variables. Ring age, ring area, March to May mean temperature, July soil moisture deficit, and whether or not biosolids had been applied were important predictors of RSG on this site. The equation for RSG can be easily converted to carbon or energy content equations by multiplying by the dry wood carbon and energy content factors.