Wood ash as a vegetative-growth promoter in soils with subsurface compaction

ABSTRACT Subsurface soil compaction and nutritional stress are among the main factors that limit the yield of crops. Using forest residues, such as wood ash, is a viable option in the chemical recovery of soils and can promote vigorous root development in soils with subsurface compaction. The objective of this study was to indicate the most adequate dose of wood ash for efficient management of this residue applied in rotational crops cultivated in soils with subsurface compaction. Safflower plants (Carthamus tinctorius), a rotational crop with a deep taproot system, were grown in clay soil fertilized with different doses of ash and with induced levels of compaction in the subsurface layer. The experiment was conducted in a randomized block design, under a 4 × 5 factorial scheme, composed of four doses of wood ash (8.0, 16.0, 24.0, and 32.0 g dm-3) and five levels of soil bulk density (1.0, 1.2, 1.4, 1.6, and 1.8 kg dm-3), with four replicates. Crop growth variables (plant height, number of leaves, stem diameter, and SPAD chlorophyll index) were evaluated at 15, 45, and 75 days after emergence. The results indicated that soil compaction was the most limiting factor to the vegetative development of safflower, regardless of the ash dose. The interaction between the wood ash dose and bulk density, when present, showed that the best growth response occurred for ash dose of 25 g dm-3 for a soil bulk density of 1.2 kg dm-3.

Carbon Accumulation and Partitioning Above and Belowground under Coppiced and Replanted Eucalypt Plantations

The extent to which the C sink strength of eucalypt plantations can be affected by coppicing or replanting remains unclear. To address this issue, we evaluated variations in C stocks under coppiced or replanted eucalypt stands formed by clones or seedlings. For each field assessment (0 [T0], 2.5, 3.5, 4.5, 5.5 and 7.0 years [at harvest]), tree biomass, litterfall, and soil C stocks (0–120 cm depth) were determined. At harvest, debarked stemwood productivity was similar under coppice or replanting, about 50.0 Mg C ha–1. Generally, coppiced stands favored subsoil C storage (40–100 cm), whereas replanted stands favored soil C accrual in topsoil (0–20 cm), depending on the genetic material. Relative to T0, soil C increased about 2.14, 1.91, and 1.84 Mg C ha–1 yr–1 under coppice, replanting with seedlings and clones, respectively. Coarse root biomass under these stands were about 17.3, 13.4, and 9.5 Mg C ha–1, respectively, equivalent to 50% of total harvest residues. Hence, inputs from coarse roots could represent a large contribution to soil C over multiple rotations under coppiced or replanted stands. Otherwise, short-term C losses can be high where stumps and coarse roots are harvested, especially following successive coppice cycles. Study Implications: Our findings have important implications for forest managers growing eucalypt plantations aiming to maximize C accumulation. Both coppiced and replanted stands can fix up to 50 Mg C ha−1 only in debarked stemwood over 7 years, with a comparatively higher C storage in coarse roots under coppice. Despite the increasing demand for forest residues in bioenergy production, harvesting stumps and coarse roots should be avoided, especially upon replanting eucalypt stands after successive coppice cycles.

PRODUÇÃO DE MÓVEIS RÚSTICOS COM MADEIRA RESIDUAL DA FLORESTA AMAZÔNICA

A exploração madeireira e as conversões de áreas de florestas para uso alternativo do solo na região Amazônica, em especial no estado do Amapá, resultam em grandes quantidades de madeira residual que em geral são abandonadas em campo. Essa problemática da geração de resíduos florestais e principalmente do desperdício e da falta de alternativas para o seu uso apropriado, resultou nesta proposta de pesquisa que teve como objetivo a produção de móveis rústicos artesanais como uma alternativa para o uso da madeira residual da floresta Amazônica. Foram coletados resíduos de madeira deixados no campo após a colheita de floresta Amazônica manejada, destinando-os à fabricação de mobiliário rústico, obtendo como resultado final os seguintes protótipos: banco peça de tora única, balcão para barzinho, aparador de madeira, pia de madeira, mesinha de centro com tampo de madeira, mesinha de centro com tampo de vidro. Foi testada a viabilidade técnica para fabricação artesanal das peças de mobiliário utilizando máquinas e ferramentas portáteis. Os resíduos de madeira se mostraram excelente fonte de matéria-prima para movelaria rústica possibilitando múltiplas alternativas de designs, apesar de certas dificuldades terem sido evidenciadas no decorrer do processo como: peso, dureza, orientação da grã da madeira, entre outras que, no entanto, não impossibilitaram a produção dos móveis. O uso da madeira residual para fabricação de móveis rústicos pode se constituir num novo e empreendedor negócio para a região Amazônica, contribuindo para a geração de renda local. Verificou-se que o método empregado proporcionou a produção de móveis originais, o que agrega valor à sua comercialização. Palavras-chave: trabalho artesanal; empreendedorismo; projeto. Rustic furniture production with wood residues from the Amazon forest ABSTRACT: Harvesting and conversions of forest areas to alternative land use in the Amazon region, especially in the Amapá state, result in large amounts of wood residues that are generally abandoned. This problem about the forest residues and mainly of its loss and the lack of alternatives for its proper use, resulted in this research proposal that aimed to produce handcrafted rustic furniture as an alternative to the use of wood residues from the Amazon forest. Wood residues left in the field after harvesting the managed Amazon forest were collected and destined for the manufacture of rustic furniture, obtaining the following prototypes as a final result: log bench, bar counter, wood dresser, wood sink, coffee table with wood top, coffee table with glass top. The technical feasibility of handcrafting furniture pieces using portable machines and tools were tested. Wood residues proved to be an excellent source of raw material for rustic furniture, enabling multiple design alternatives, although certain difficulties were evidenced during the process such as: weight, hardness, wood grain orientation, among others that did not prevent the furniture production. The use of wood residues to rustic furniture manufacture can constitute a new and entrepreneurial business for the Amazon region, contributing to the generation of local income. It was found that the method used provided the production of original furniture, which adds value to its marketing. Keywords: artisan work; entrepreneurship; design.

Innovative wood use can enable carbon-beneficial forest management in California

Responsible stewardship of temperate forests can address key challenges posed by climate change through sequestering carbon, producing low-carbon products, and mitigating climate risks. Forest thinning and fuel reduction can mitigate climate-related risks like catastrophic wildfire. These treatments are often cost prohibitive, though, in part because of low demand for low-value wood “residues.” Where treatment occurs, this low-value wood is often burned or left to decay, releasing carbon. In this study, we demonstrate that innovative use of low-value wood, with improved potential revenues and carbon benefits, can support economical, carbon-beneficial forest management outcomes in California. With increased demand for wood residues, forest health–oriented thinning could produce up to 7.3 million (M) oven-dry tonnes of forest residues per year, an eightfold increase over current levels. Increased management and wood use could yield net climate benefits between 6.4 and 16.9 million tonnes of carbon dioxide equivalent (M tCO2e) per year when considering impacts from management, wildfire, carbon storage in products, and displacement of fossil carbon-intensive alternatives over a 40-y period. We find that products with durable carbon storage confer the greatest benefits, as well as products that reduce emissions in hard-to-decarbonize sectors like industrial heat. Concurrently, treatment could reduce wildfire hazard on 4.9 M ha (12.1 M ac), a quarter of which could experience stand-replacing effects without treatment. Our results suggest that innovative wood use can support widespread fire hazard mitigation and reduce net CO2 emissions in California.

Greenhouse Gas Emission Offsets of Forest Residues for Bioenergy in Queensland, Australia

Harnessing sustainably sourced forest biomass for renewable energy is well-established in some parts of the developed world. Forest-based bioenergy has the potential to offset carbon dioxide emissions from fossil fuels, thereby playing a role in climate change mitigation. Despite having an established commercial forestry industry, with large quantities of residue generated each year, there is limited use for forest biomass for renewable energy in Queensland, and Australia more broadly. The objective of this study was to identify the carbon dioxide mitigation potential of replacing fossil fuels with bioenergy generated from forest harvest residues harnessed from commercial plantations of Pinus species in southeast Queensland. An empirical-based full carbon accounting model (FullCAM) was used to simulate the accumulation of carbon in harvest residues. The results from the FullCAM modelling were further analysed to identify the energy substitution and greenhouse gas (GHG) emissions offsets of three bioenergy scenarios. The results of the analysis suggest that the greatest opportunity to avoid or offset emissions is achieved when combined heat and power using residue feedstocks replaces coal-fired electricity. The results of this study suggest that forest residue bioenergy is a viable alternative to traditional energy sources, offering substantive emission reductions, with the potential to contribute towards renewable energy and emission reduction targets in Queensland. The approach used in this case study will be valuable to other regions exploring bioenergy generation from forest or other biomass residues.

Towards Comparable Carbon Credits: Harmonization of LCA Models of Cellulosic Biofuels

Decarbonization programs are being proposed worldwide to reduce greenhouse gas (GHG) emissions from transportation fuels, using Life Cycle Assessment (LCA) models or tools. Although such models are broadly accepted, varying results are often observed. This study describes similarities and differences of key decarbonization programs and their GHG calculators and compares established LCA models for assessing 2G ethanol from lignocellulosic feedstock. The selected LCA models were GHGenius, GREET, JRC’s model, and VSB, which originated calculators for British Columbia’s Low Carbon Fuel Standard, California’s Low Carbon Fuel Standard, Renewable Energy Directive, and RenovaBio, respectively. We performed a harmonization of the selected models by inserting data of one model into other ones to illustrate the possibility of obtaining similar results after a few harmonization steps and to determine which parameters have higher contribution to closing the gap between default results. Differences among 2G ethanol from wheat straw were limited to 0.1 gCO2eq. MJ−1, and discrepancies in emissions decreased by 95% and 78% for corn stover and forest residues, respectively. Better understanding of structure, calculation procedures, parameters, and methodological assumptions among the LCA models is a first step towards an improved harmonization that will allow a globally accepted and exchangeable carbon credit system to be created.