Environmental and economic impacts of substitution between wood products and alternative materials: a review of micro-level analyses from Norway and Sweden

This article gives a state of the art overview on quantitative analyses from Norway and Sweden of Life cycle analyses (LCA), which compare the environmental impacts of substitution between wood and alternative materials, with emphasis on greenhouse gas (GHG) emissions, economics and methodological issues. In all studies referred to this overview, wood is a better alternative than other materials with regard to GHG emissions. Furthermore, wood is causing less emissions of SO₂ and generates less waste compared to the alternative materials. Preservative treated wood, on the other hand, might have toxicological impacts on human health and ecosystems. Impacts on acidification, eutrofication and creation of photochemical ozone vary in different comparisons. Amount of greenhouse gases avoided due to substitution between wood and steel is in the range of 36–530 kg CO₂-equivalents per m³ input of timber with 4% discount rate; depending on waste management of the materials, and how carbon fixation on forest land is included. This amount is 93–1062 kg CO₂-equivalents for substitution between wood and concrete, if the wood is not landfilled after use. Many of the LCAs could be considerably improved, if the analyses were done with several alternative assumptions regarding boundaries of the system used in the LCA. This is important, not least to map what are the main assumptions for the results obtained and to compare with other studies. It is also important to consider the time-profile of the GHG emissions and other impacts over the life-cycle—it is surprising that this is not taken more seriously. Wood as a building material is competitive on price in those studies that include costs. It is a weak point of many LCAs that costs as well as other economic aspects influencing product substitution are not included, and a major research challenge is to combine traditional LCA with economic analysis in order to make both more policy relevant. In particular, one should develop dynamic input/output models where price and income substitutions as well as technological changes and cost components are included endogenously.     

Greenhouse gas balance of harvesting stumps and logging residues for energy in Sweden

Abstract

In this case study, forest fuel procurement chains of stumps and logging residues were evaluated using a Life Cycle Assessment perspective. Direct emissions from combustion were not included, but soil organic carbon change was included as changes in carbon stocks in litter and soil. The results showed that primary forest biomass for energy has a climate impact which is time dependent. However, in long-time perspectives, there are large greenhouse gas (GHG) savings. In a short-term (20 years), there were no GHG savings when natural gas or coal was replaced. This is due to the fact that the harvest lead to decreased input of organic matter to the soil which is compared to a reference where biomass are left to decompose. The reduction in soil organic carbon may have been underestimated in the stump harvest systems studied, as the effect of soil disturbance per se was not included. Important factors when assessing GHG balance of forest fuels, besides the time horizon used, were site productivity, geographical position and forest fuel resource (stumps or logging residues). When assessing the greenhouse gas savings, efficiency of the end-use, allocation method between heat and power and type of fossil fuel replaced were also important.     

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.     

Characteristic fuel consumption and exhaust emissions in fully mechanized logging operations

A study was done using eight different logging machines (harvesters and forwarders) in clear-felling operations to quantify the associated fuel consumption, and to define the inherent relationship between engine output power and fuel consumption. Exhaust emissions were also calculated on the basis of mean fuel consumption values, obtained by measurements, and from the developed regression and correlation model for diesel and rapeseed methyl ester (RME) fuels. The calculation considered exhaust emissions associated with the manufacture, distribution, and combustion of the respective fuels. It was found that carbon dioxide emissions amounted to 9.63 kg/m³ of delivered timber for diesel fuel, and to 10.64 kg/m³ for RME. It was also found that when using RME only 2.82 kg/m³ of carbon dioxide emissions originated from fossil resources, therefore, it is only this amount that can be deemed an environmental load, confirming RME as a lesser environmental pollutant.     

Whole-tree harvesting with stump removal versus stem-only harvesting in peatlands when water quality,biodiversity conservation and climate change mitigation matter

This article examines alternative forest harvesting regimes when ecosystem services in terms of water quality, biodiversity conservation and climate change mitigation are included in the analysis. The harvesting regimes are whole-tree harvesting with stump removal and conventional stem-only harvesting. The harvesting regimes are evaluated under two alternative climate policy contexts. The first alternative is a carbon neutral bioenergy policy, which assumes the carbon dioxide (CO₂) neutrality of bioenergy and produces substitution benefits, as bioenergy replaces fossil fuels. The second alternative climate policy, a carbon non-neutral bioenergy policy, takes into account the fact that bioenergy causes carbon dioxide emissions, producing substitution costs, and that harvested woody biomass affects the ability of a forest to act as a carbon sink. We extend the traditional Faustmann (1849) rotation model to include nutrient load damage, biodiversity benefits, and climate impacts. The empirical analysis is based on Finnish data from a catchment experiment carried out on drained peatland forests. The empirical results show that under a carbon neutral bioenergy policy, whole-tree harvesting with stump removal produces the highest net social benefits. However, if a carbon non-neutral bioenergy policy is assumed, the net social benefits are greater under stem-only harvesting.     

甘肃省葡萄科木本植物种类及分布

甘肃产葡萄科木本植物4属20种1亚种8变种,绝大多数分布于全省天然林区,个别人工栽培;在多年调查研究的基础上,首次报道了甘肃葡萄科木本植物种类及分布。     

Soil CO<Subscript>2</Subscript>, CH<Subscript>4</Subscript> and N<Subscript>2</Subscript>O emissions from production fields with planted and remnant hedgerows in the Fraser River Delta of British Columbia

Planting hedgerows on farm field edges can help mitigate greenhouse gas (GHG) emissions from agricultural landscapes by sequestering carbon (C) in woody biomass and in soil. Sequestration rates however, must be assessed in terms of their overall global warming potential (GWP) which must also consider GHG emissions. The objectives of this study were to (1) compare carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) emissions from two types of hedgerows and adjacent annual agricultural production fields, and 2) better understand how climate, soil properties and plant species configurations affect hedgerow GHG emissions. At eight study sites in the lower Fraser River delta of British Columbia, we measured emissions from soil in both planted (P-Hedgerow) and remnant hedgerows (R-Hedgerow), as well as in adjacent annual crop production fields over 1 year using a closed-static chamber method. CO₂ emissions were 59 % higher in P-Hedgerow than R-Hedgerow, yet there were no significant differences of relative emissions of CH₄ and N₂O. The environmental variables that explained the variation in emissions differed for the three GHGs. CO₂ emissions were significantly correlated with soil temperature. CH₄ and N₂O and emissions were marginally significantly correlated with soil organic carbon (SOC) and soil water-filled pore space (WFPS), respectively. Emissions were not significantly correlated with hedgerow plant species diversity. While hedgerows sequester carbon in their woody biomass, we demonstrated that it is critical to measure hedgerow emissions to accurately ascertain their overall GHG mitigation potential. Our results show that there are no CO₂e emission differences between the management options that plant new diverse hedgerows or conserve existing hedgerows.     

Singular and interactive effects of blowdown, salvage logging, and wildfire in sub-boreal pine systems

The role of disturbance in structuring vegetation is widely recognized; however, we are only beginning to understand the effects of multiple interacting disturbances on ecosystem recovery and development. Of particular interest is the impact of post-disturbance management interventions, particularly in light of the global controversy surrounding the effects of salvage logging on forest ecosystem recovery. Studies of salvage logging impacts have focused on the effects of post-disturbance salvage logging within the context of a single natural disturbance event. There have been no formal evaluations of how these effects may differ when followed in short sequence by a second, high severity natural disturbance. To evaluate the impact of this management practice within the context of multiple disturbances, we examined the structural and woody plant community responses of sub-boreal Pinus banksiana systems to a rapid sequence of disturbances. Specifically, we compared responses to Blowdown (B), Fire (F), Blowdown-Fire, and Blowdown-Salvage-Fire (BSF) and compared these to undisturbed control (C) stands. Comparisons between BF and BSF indicated that the primary effect of salvage logging was a decrease in the abundance of structural legacies, such as downed woody debris and snags. Both of these compound disturbance sequences (BF and BSF), resulted in similar woody plant communities, largely dominated by Populus tremuloides; however, there was greater homogeneity in community composition in salvage logged areas. Areas experiencing solely fire (F stands) were dominated by P. banksiana regeneration, and blowdown areas (B stands) were largely characterized by regeneration from shade tolerant conifer species. Our results suggest that salvage logging impacts on woody plant communities are diminished when followed by a second high severity disturbance; however, impacts on structural legacies persist. Provisions for the retention of snags, downed logs, and surviving trees as part of salvage logging operations will minimize these structural impacts and may allow for greater ecosystem recovery following these disturbance combinations.     

甘肃瑞香科木本植物分布和种类

甘肃产瑞香科木本植物植物2属15种,分布于全省天然林区;在多年调查研究的基础上,首次报道了甘肃瑞香科木本植物种类及分布.     

Conservation of forest biodiversity and ecosystem properties in a pastoral landscape of the Ecuadorian Andes

High Andean cloud forests are home to a diversity of unique wildlife and are important providers of ecosystem services to people in the Andean regions. The extent of these cloud forests has been widely reduced through conversion to pasture for livestock, which threatens the forests’ ability to support biodiversity and provide ecosystem services. This paper explores whether impacts on woody plant biodiversity and four ecosystem properties (woody plant species richness, juvenile timber tree abundance, soil organic matter content and soil moisture) from converting forest to pasture can be mitigated if some woody forest vegetation is maintained within pastures. Woody vegetation in pastures was found to conserve those woody plant species that are more tolerant to exposure and grazing, but conservation of the high montane cloud forest community required areas of forest from which livestock were restricted. The sampled sites clustered according to woody plant species cover; these clusters represented a gradient from pasture with patches of shrubs to mature forest. Clusters differed in both woody plant species richness and number of juvenile timber trees whereas soil organic matter and soil moisture were observed to be similar among all clusters. This suggests that the different habitats may have some equivalent ecosystem properties. We conclude that the presence of woody vegetation in pastures may reduce some of the impacts of converting forest to pasture, but should not be considered a substitute for protecting large areas of forest, which are essential for maintaining woody plant species diversity in high Andean cloud forest.     

Social preferences toward energy generation with woody biomass from public forests in Montana,USA

In Montana, USA, there are substantial opportunities for mechanized thinning treatments on public forests to reduce the likelihood of severe and damaging wildfires and improve forest health. These treatments produce residues that can be used to generate renewable energy and displace fossil fuels. The choice modeling method is employed to examine the marginal willingness of Montanans' to pay (MWTP) for woody biomass energy produced from treatments in their public forests. The survey instrument elicited social preferences for important co-benefits and costs of woody biomass energy generation in Montana, namely the extent of healthy forests, the number of large wildfires, and local air quality. Positive and statistically significant MWTP is found for woody biomass energy generation, forest health and air quality. MWTP to avoid large wildfires is statistically insignificant. However, MWTP for woody biomass energy diminishes quickly, revealing that Montanans do not support public forestland management that produces more than double the current level of woody biomass harvested for energy generation. These findings can be used by policy makers and public land managers to estimate the social benefits of utilizing residues from public forest restoration or fuel treatment programs to generate energy.     

木本植物磷效率的调控机制及遗传改良研究进展

磷素是植物必需营养元素之一,是植物体内许多重要化合物的成分,在植物的各种生理生化反应中扮演着重要的作用,自然界土壤中缺磷已经成为植物生长的限制因子之一。本文结合国内外植物营养遗传的最新进展, 就木本植物利用土壤中难溶性磷的遗传特性、耐低磷胁迫的适应机制、以及木本植物磷高效性状的遗传改良等进行述评,希望对今后定向培育磷高效性状的木本植物具有一定的指导意义。     

Nutrient and carbon budgets in forest soils as decision support in sustainable forest management

Knowledge about the nutrient and carbon budgets in forest soils is essential to maintain sustainable production, but also in several environmental issues, such as acidification, eutrophication and climate change. The budgets are strongly influenced by atmospheric deposition as well as forestry. This study demonstrates how budget calculations for nitrogen (N), carbon (C) and base cations (BC) can be used as a basis for policy decisions on a regional level in Sweden.The study was based on existing nutrient and C budget calculations on a regional scale in Sweden. The nutrient budgets have been calculated for each square in a national 5 km × 5 km net by means of mass balances including deposition, harvest losses, leaching, weathering (BC) and fixation (N). Scenarios with different deposition and forestry intensity have been run and illustrated on maps. A simplified C budget has been estimated by multiplying the N accumulation with the C/N ratio in the organic layer, based on the assumption that the C/N ratio in the accumulating organic matter is equal to the ratio in the soil organic matter pool. The budget approaches differ from earlier budget studies since they involve regional high resolution data, combine deposition and forestry scenarios and integrate different environmental aspects.The results indicate that whole-tree harvesting will cause net losses of N and base cations in large parts of Sweden, which means that forestry will not be sustainable unless nutrients are added through compensatory fertilization. To prevent net losses following whole-tree harvesting, compensatory fertilization of base cations would be required in almost the whole country, whereas N fertilization would be needed mainly in the northern half of Sweden. The results further suggest that today's recommendations for N fertilization should be revised in southern Sweden by applying the southwest–northeast gradient of the N budget calculations. The C and N accumulation calculations show that C sequestration in Swedish forest soils is not an effective or sustainable way to decrease the net carbon dioxide emissions. A better way is to apply whole-tree harvesting and use the branches, tops and needles as biofuel replacing fossil fuels. This could reduce the present carbon dioxide emissions from fossil fuels substantially.The study shows that high resolution budget calculations that illuminate different aspects of sustainability in forest ecosystems are important tools for identifying problem areas, investigating different alternatives through scenario analyses and developing new policies. Cooperation with stakeholders increases the probability that the research will be useful.     

河源市建成区城市绿地木本植物调查

调查了河源市4个绿地类型1163个样地木本植物状况,结果表明,共有木本植物78科227属401种(含种下单位),其中常绿木本植物为333种,占比为83.1％,木本植物以常绿为主;观花植物179种,占木本植物的44.6％,花色以红色、白色和黄色系列为主,花期集中在春、夏和秋三季.建成区城市绿地木本植物种类数在国内已有报道...     

Carry-over effects of ozone on root growth and carbohydrate concentrations of ponderosa pine seedlings

Ozone exposure decreases belowground carbon allocation and root growth of plants; however, the extent to which these effects persist and the cumulative impact of ozone stress on plant growth are poorly understood. To evaluate the potential for plant compensation, we followed the progression of ozone effects, with particular emphasis on the development of new roots. Ponderosa pine (Pinus ponderosa Dougl. ex Laws.) seedlings were exposed to ozone for 2 years. Following removal of the seedlings from ozone, root growth was assessed to characterize the carry-over effects on new root production, and carbohydrate concentrations were measured to determine if allocation strategies differed among ozone treatments. Four months after removal from ozone, dormant seedlings had significantly lower starch concentrations in stems, coarse roots and fine roots than control seedlings. Following root flushing, starch concentrations in all seedlings decreased, with ozone-treated seedlings containing significantly less starch, sucrose, fructose, glucose and total monosaccharides than control seedlings. There was some evidence that stem starch was mobilized to compensate partially for the lower concentrations of root starch in ozone-treated seedlings; however, there was significantly less new root production in seedlings previously exposed to ozone for 2 years than in control seedlings. Early senescence of older needle age classes, perhaps resulting in inadequate available photosynthate, may be responsible for the reduction in new root production during the year following exposure to ozone. Stored carbohydrate reserves, which were depleted in seedlings previously exposed to ozone, were insufficient to compensate for the ozone-induced reduction in canopy photosynthate. We conclude that there are carry-over effects of ozone exposure on ponderosa pine seedlings, including an enhanced potential for seedling susceptibility to other stresses even in respite years when ozone concentrations are low.     

Plant functional groups based on vegetative and reproductive traits in a subtropical forest community

Plant functional types (PFTs) are essential for us to research on community structure and dynamics. A proper criterion for assessing PFTs in a broad-leaved community is yet to be established, and the reports for correlations between PFTs and plant succession are still rare. The current study aimed to: (1) detect which functional trait(s) of woody species would best characterize PFTs in a forest community, and (2) explore general trends of functional traits with plant succession. We sampled fruit-bearing twigs of 55 woody species in a subtropical forest in southwest China, and recorded two sets of sizes of functional traits including both vegetative and reproductive organs. A principal components analysis (PCA) was performed on the functional traits studied, and the functional types were grouped out with K-means clustering. Next, the relationship between PFTs and species succession status was examined. The PCA revealed that of all the functional traits studied, twig sizes may exert a greatest impact on the traits assemblages and PFTs’ performances in this community, i.e., twig size may act as an important determinant for PFTs at the species level. The 55 woody species were classified into three distinct PFTs whose sizes tended to increase with the advance of species succession. Twig size tended to combine with leaf size, and so was the fruit size with seed size.     

Tree chitinases – stress‐ and developmental‐driven gene regulation

In recent years, a considerable number of studies have harnessed the power of genomics to decipher the role of pathogenesis‐related (PR) proteins in plant defence against various biotic and abiotic stresses. Chitinases are PR antifungal proteins expressed constitutively at low levels in plants and induced during biotic pressures and are demonstrated to be involved in the plant defence responses. Remarkable induction of chitinase enzymes by various abiotic agents (salicylic acid, jasmonic acid, ethylene and ozone) and biotic components (pathogens, insect pest, fungal cell wall components and oligosaccharides) is well demonstrated in plants. Several reviews on plant chitinase expression during host–pathogen interaction are available for annual species, whilst reports of their expression in tree species are limited to a few woody perennials: Populus, Pinus, Picea, Eucalyptus, Castanea and Pseudotsuga. The aim of this paper is to review the induction of chitinase during various stresses and developmental processes in forest tree species.     

Can forest trees compensate for stress-generated growth losses by induced production of volatile compounds?

Plants produce a variety of volatile organic compounds (VOCs). Under abiotic and biotic stresses, the number and amount of produced compounds can increase. Due to their long life span and large size, trees can produce biogenic VOCs (BVOCs) in much higher amounts than many other plants. It has been suggested that at cellular and tree physiological levels, induced production of VOCs is aimed at improving plant resistance to damage by reactive oxygen species generated by multiple abiotic stresses. In the few reported cases when biosynthesis of plant volatiles is inhibited or enhanced, the observed response to stress can be attributed to plant volatiles. Reported increase, e.g., in photosynthesis has mostly ranged between 5 and 50%. A comprehensive model to explain similar induction of VOCs under multiple biotic stresses is not yet available. As a result of pathogen or herbivore attack on forest trees, the induced production of VOCs is localized to the damage site but systemic induction of emissions has also been detected. These volatiles can affect fungal pathogens and the arrival rate of herbivorous insects on damaged trees, but also act as signalling compounds to maintain the trophic cascades that may improve tree fitness by improved efficiency of herbivore natural enemies. On the forest scale, biotic induction of VOC synthesis and release leads to an amplified flow of BVOCs in atmospheric reactions, which in atmospheres rich in oxides of nitrogen (NOx) results in ozone formation, and in low NOx atmospheres results in oxidation of VOCs, removal in ozone from the troposphere and the resulting formation of biogenic secondary organic aerosol (SOA) particles. I will summarize recent advances in the understanding of stress-induced VOC emissions from trees, with special focus on Populus spp. Particular importance is given to the ecological and atmospheric feedback systems based on BVOCs and biogenic SOA formation.     

长春市木本植物模纹绿地应用现状的调查与分析

通过对长春市木本植物模纹绿地园林应用现状的调查与分析,结果表明:木本植物模纹绿地的栽植密度过大、株型结构不合理是缩短更新周期的主要因素,并导致一定的经济损失。培育合理株型结构的苗木、采用适宜的栽植密度是保证景观效果与降低经济成本的基本措施。     

Short- and long-term effects of thinning and prescribed fire on carbon stocks in ponderosa pine stands in northern Arizona

Euro-American logging practices, intensive grazing, and fire suppression have increased the amount of carbon that is stored in ponderosa pine (Pinus ponderosa Dougl. Ex Laws) forests in the southwestern United States. Current stand conditions leave these forests prone to high-intensity wildfire, which releases a pulse of carbon emissions and shifts carbon storage from live trees to standing dead trees and woody debris. Thinning and prescribed burning are commonly used to reduce the risk of intense wildfire, but also reduce on-site carbon stocks and release carbon to the atmosphere. This study quantified the impact of thinning on the carbon budgets of five ponderosa pine stands in northern Arizona, including the fossil fuels consumed during logging operations. We used the pre- and post-treatment data on carbon stocks and the Fire and Fuels Extension to the Forest Vegetation Simulator (FEE-FVS) to simulate the long-term effects of intense wildfire, thinning, and repeated prescribed burning on stand carbon storage.The mean total pre-treatment carbon stock, including above-ground live and dead trees, below-ground live and dead trees, and surface fuels across five sites was 74.58 Mg C ha⁻¹ and the post-treatment mean was 50.65 Mg C ha⁻¹ in the first post-treatment year. The mean total carbon release from slash burning, fossil fuels, and logs removed was 21.92 Mg C ha⁻¹. FEE-FVS simulations showed that thinning increased the mean canopy base height, decreased the mean crown bulk density, and increased the mean crowning index, and thus reduced the risk of high-intensity wildfire at all sites. Untreated stands that incurred wildfire once within the next 100 years or once within the next 50 years had greater mean net carbon storage after 100 years compared to treated stands that experienced prescribed fire every 10 years or every 20 years. Treated stands released greater amounts of carbon overall due to repeated prescribed fires, slash burning, and 100% of harvested logs being counted as carbon emissions because they were used for short-lived products. However, after 100 years treated stands stored more carbon in live trees and less carbon in dead trees and surface fuels than untreated stands burned by intense wildfire. The long-term net carbon storage of treated stands was similar or greater than untreated wildfire-burned stands only when a distinction was made between carbon stored in live and dead trees, carbon in logs was stored in long-lived products, and energy in logging slash substituted for fossil fuels.