Search Results (9)

Timber and other biobased materials store carbon that has been captured from the atmosphere during photosynthesis and plant growth. The estimation of these biogenic carbon stocks in the harvested wood products (HWP) pool has received increasing attention since its inclusion in greenhouse gas reporting by the IPCC. It is of particular interest for long service life products such as timber in buildings; however, some aspects require further thought—in particular the handling of service lives as opposed to half-lives. The most commonly used model for calculating changes in the HWP pool uses first order decay based on half-lives. However other approaches are based on average service lives and estimates of residence times in the product pool, enabling different mathematical functions to be used. This paper considers the evolution of the two concepts and draws together data from a wide range of sources to consider service life estimation, which can be either related to design life or practical observations such as local environmental conditions, decay risk or consumer behaviour. As an increasing number of methods emerge for calculating HWP pool dynamics, it is timely to consider how these numerical inputs from disparate sources vary in their assumptions, calculation types, accuracy and results. Two groups are considered: half-lives for first order decay models, and service life and residence time population distributions within models based on other functions. A selection of examples are drawn from the literature to highlight emerging trends and discuss numerical constraints, data availability and areas for further study. The review indicated that issues exist with inconsistent use of nomenclature for half-life, average service life and peak flow from the pool. To ensure better sharing of data between studies, greater clarity in reporting function types used is required. Full article

The postagrogenic transformation of landscapes is one of the key problems leading to a decrease in soil fertility in the territory of Northwest Russia. In order to assess the degree of land degradation, field studies of soils from fallow lands in the Leningrad Region were carried out. Different evolutionary trends of ontogenesis of soils with types of soil parent materials were revealed. At morphological and micromorphological levels, degradation processes of old-arable horizons were noted, including secondary podzolization and decreasing Ap horizon thickness. Using a CHN analyzer, the stock levels of soil organic carbon and nitrogen of the studied chronoseries were estimated. The data obtained show that the carbon stocks of old-arable soils are lower than the benchmark ones due to the weak development of the Oi horizon. Carbon dynamics varied substantially by parent materials: soils on silt–clay materials showed a low 7.1% carbon decrease, while soils on sandy and bottom sediments increased by 139% and 163%, respectively, in old-arable horizons by the accumulation of coarse forms of carbon. For nitrogen, it was revealed that the highest stocks are observed in old-ploughed soils, which is due to the input of a large amount of plant residues from small-leaved forests. The content of biogenic elements in the soil showed separate evolutionary direction depending on parent materials: soils on silt–clay materials showed 7.6% phosphorus depletion and 15% potassium loss over 15–30 years, while soils on sandy materials demonstrated 18% phosphorus loss and 114% potassium increase during 30–86 years of fallow state. On the contrary, the content of nitrate and ammonium forms of nitrogen was higher than in the benchmark zonal soils, with nitrate nitrogen increasing by 150 times on sandy parent materials and ammonium nitrogen increasing by 102% in soils formed on bottom sediments over 35–70 years, which is due to the transformation of grass and forest plant residues. The duration of transformation and regradation of soils of fallow land depends on geogenic and bioclimatic conditions that determine the direction and speed of changes. Full article

Urban environments significantly contribute to carbon emissions, both through operational processes and the embodied emissions of construction materials, thus exacerbating climate change. Nevertheless, urban timber structures offer a viable alternative by acting as carbon sinks, capable of sequestering carbon for decades or even centuries. This study develops and applies a methodology to quantify the biogenic carbon stored in Santiago City’s timber-based buildings, conceptualized as a “Second Forest” that transfers and preserves the carbon capture capacity of trees in the built environment. The analysis estimates that Santiago’s urban timber constructions have expanded their wood-built surface area by 192,831 m² over the past eight years, reflecting the growing adoption of timber in urban construction. During the same period, biogenic carbon storage increased from 199.78 kt to 202.73 kt, equivalent to 10.84 kt of CO₂ under average conditions. These findings highlight the potential of urban planning strategies, such as promoting taller timber buildings and adopting circular timber practices, to enhance carbon sequestration and reduce reliance on carbon-intensive materials. This research highlights the fundamental role that timber buildings play in urban climate change mitigation, positioning them as active contributors to global carbon management efforts. Full article

Standard carbon accounting methods and metrics undermine the potential of fast-growing biogenic materials to decarbonize buildings because they ignore the timing of carbon uptake. The consequence is that analyses can indicate that a building material is carbon-neutral when it is not climate-neutral. Here, we investigated the time-dependent effect of using fast-growing fibers in durable construction materials. This study estimated the material stock and flow and associated cradle-to-gate emissions for four residential framing systems in the US: concrete masonry units, light-frame dimensional timber, and two framing systems that incorporate fast-growing fibers (bamboo and Eucalyptus). The carbon flows for these four framing systems were scaled across four adoption scenarios, Business as Usual, Early-Fast, Late-Slow, and Highly Optimistic, ranging from no adoption to the full adoption of fast-growing materials in new construction within 10 years. Dynamic life cycle assessment modeling was used to project the radiative forcing and global temperature change potential. The results show that the adoption of fast-growing biogenic construction materials can significantly reduce the climate impact of new US residential buildings. However, this study also reveals that highly aggressive, immediate adoption is the only way to achieve net climate cooling from residential framing within this century, highlighting the urgent need to change the methods and metrics decision makers use to evaluate building materials. Full article

Basic inventory is required for proper understanding and utilization of Earth’s natural resources, especially with increasing soil degradation and species loss. Soil carbon is newly refined at >30,000 Gt C (gigatonnes C), ten times above prior totals. Soil organic carbon (SOC) is up to 24,000 Gt C, plus plant stocks at ~2400 Gt C, both above- and below-ground, hold >99% of Earth’s biomass. On a topographic surface area of 25 Gha with mean 21 m depth, Soil has more organic carbon than all trees, seas, fossil fuels, or the Atmosphere combined. Soils are both the greatest biotic carbon store and the most active CO₂ source. Values are raised considerably. Disparity is due to lack of full soil depth survey, neglect of terrain, and other omissions. Herein, totals for mineral soils, Permafrost, and Peat (of all forms and ages), are determined to full depth (easily doubling shallow values), then raised for terrain that is ignored in all terrestrial models (doubling most values again), plus SOC in recalcitrant glomalin (+25%) and friable saprock (+26%). Additional factors include soil inorganic carbon (SIC some of biotic origin), aquatic sediments (SeOC), and dissolved fractions (DIC/DOC). Soil biota (e.g., forests, fungi, bacteria, and earthworms) are similarly upgraded. Primary productivity is confirmed at >220 Gt C/yr on land supported by Barrow’s “bounce” flux, C/O isotopes, glomalin, and Rubisco. Priority issues of species extinction, humic topsoil loss, and atmospheric CO₂ are remedied by SOC restoration and biomass recycling via (vermi-)compost for 100% organic husbandry under Permaculture principals, based upon the Scientific observation of Nature. Full article

Eucalyptus plantations play an important role in capturing and storing atmospheric carbon, mitigating global climate change. Forest management policies encouraging integrated livestock-forestry systems require quantitative estimates of temporal and spatial patterns of carbon storage for these agricultural systems. This study quantified the effects of eucalyptus management and arrangement on carbon stock dynamics in integrated livestock-forestry (ILF) systems versus monoculture eucalyptus plantings. Arrangement and management resulted in equal storage of carbon in both monoculture and ILF systems (34.7 kg per tree). Both factors are important to better understand how forest species in integrated systems stock carbon and how this can compensate for other agricultural system components, such as cattle. The extent to which ILF systems offset beef cattle (Nellore) emissions was determined by estimating changes in carbon stock over time for Eucalyptus urophylla × E. grandis, clone H13, under three scenarios (S) of wood use. These scenarios were (S1) tree growth without thinning, (S2) trees used for biomass energy without thinning, and (S3) 50% of trees used for biomass energy at five years old and 50% of trees used for both timber and energy after eight years, considering the full life cycle of eucalyptus. The S1 and S3 systems can stock 510 and 73 metric tons (t) of CO₂ ha⁻¹, respectively, while S2 emits 115 t CO₂ ha⁻¹ of biogenic carbon. Full article

Open cast coal mining causes complete loss of carbon sink due to the destruction of vegetation and soil structure. In order to offset the destruction and to increase sequestration of carbon, afforestation is widely used to restore these mine spoils. The current field study was conducted to assess the ecosystem status, soil quality and C pool in an 8 years old reclaimed mine spoil (RMS), compared to a reference forest (RF) site and unamended mine spoil (UMS). Biochar (BC) prepared from invasive weed Calotropis procera was applied in this 8 year RMS at 30 t ha⁻¹ (BC₃₀) and 60 t ha⁻¹ (BC₆₀) to study its impact on RMS properties and C pool. Carbon fractionation was also conducted to estimate inorganic, coal and biogenic carbon pools. The C stock of 8 year old RMS was 30.98 Mg C ha⁻¹ and sequestered 113.69 Mg C ha⁻¹ CO₂. BC₃₀ and BC₆₀ improved the C-stock of RMS by 31% and 45%, respectively, and increased the recalcitrant carbon by 65% (BC₃₀) and 67% (BC₆₀). Spoil physio-chemical properties such as pH, cation exchange capacity, moisture content and bulk density were improved by biochar application. The total soil carbon at BC₃₀ (36.3 g C kg⁻¹) and BC₆₀ (40 g C kg⁻¹) was found to be significantly high compared to RMS (21 g C kg⁻¹) and comparable to RF (33 g C kg⁻¹). Thus, eco-restoration of coal mine spoil and biochar application can be effective tools for coal mine reclamation and can help in achieving the UN sustainable development goal 13 (climate action) by increasing carbon sequestration and 15 (biodiversity protection) by promoting ecosystem development. Full article

Carbon cycling within the deep mangrove forest floor is unique compared to other marine ecosystems with organic carbon input, mineralization, burial, and advective and groundwater export pathways being in non-steady-state, often oscillating in synchrony with tides, plant uptake, and release/uptake via roots and other edaphic factors in a highly dynamic and harsh environment. Rates of soil organic carbon (C_ORG) mineralization and belowground C_ORG stocks are high, with rapid diagenesis throughout the deep (>1 m) soil horizon. Pocketed with cracks, fissures, extensive roots, burrows, tubes, and drainage channels through which tidal waters percolate and drain, the forest floor sustains non-steady-state diagenesis of the soil C_ORG, in which decomposition processes at the soil surface are distinct from those in deeper soils. Aerobic respiration occurs within the upper 2 mm of the soil surface and within biogenic structures. On average, carbon respiration across the surface soil-air/water interface (104 mmol C m⁻² d⁻¹) equates to only 25% of the total carbon mineralized within the entire soil horizon, as nearly all respired carbon (569 mmol C m⁻² d⁻¹) is released in a dissolved form via advective porewater exchange and/or lateral transport and subsurface tidal pumping to adjacent tidal waters. A carbon budget for the world’s mangrove ecosystems indicates that subsurface respiration is the second-largest respiratory flux after canopy respiration. Dissolved carbon release is sufficient to oversaturate water-column pCO_2, causing tropical coastal waters to be a source of CO₂ to the atmosphere. Mangrove dissolved inorganic carbon (DIC) discharge contributes nearly 60% of DIC and 27% of dissolved organic carbon (DOC) discharge from the world’s low latitude rivers to the tropical coastal ocean. Mangroves inhabit only 0.3% of the global coastal ocean area but contribute 55% of air-sea exchange, 14% of C_ORG burial, 28% of DIC export, and 13% of DOC + particulate organic matter (POC) export from the world’s coastal wetlands and estuaries to the atmosphere and global coastal ocean. Full article

Questions regarding the net effect of biofuels on carbon dioxide (CO₂) emissions have been difficult to resolve because of methodological uncertainties. One method of choice is lifecycle assessment (LCA), which takes a fuel product system as its object of analysis. LCA uses a static system model, with carbon flows averaged over a defined “lifecycle”. Although it may evaluate some carbon stock changes, the LCA convention of treating biogenic CO₂ emissions as fully offset by the carbon embodied in a biofuel’s feedstock renders its results independent of the dominant portion of carbon uptake on the land from which the feedstock is sourced. An application of material flow analysis termed annual basis carbon (ABC) accounting captures system dynamics and is fully sensitive to changes in carbon uptake. This paper compares the LCA and ABC methods, and contrasts their respective results for a case study of real-world biofuel production. It highlights the large impact of baseline carbon uptake, which can affect the sign of the results from either a likely decrease or a likely increase in net CO₂ emissions even before considering economically-induced effects. Implications include the need for further methodological work, new program-scale model development, an empirical re-analysis of biofuel systems, and a reconsideration of existing public policies and research priorities. Full article