Recent climate change research
Our AI looks at papers published in Carbon Balance and Management from BMC.
The individual reports and extracts below - including each headline - were generated automatically by our machine-reading software from recent research published by Carbon Balance and Management.
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A review of the literature on forest carbon accounting and life cycle assessments identifies a suite of assumptions that do not support or only partially support the use of wood products for climate change mitigation.
Christina Howard et al. (2021) reported on wood product carbon substitution benefits. Four assumptions in the way displacement factors are employed are analyzed. Changes in harvest or production rates will lead to a corresponding change in consumption of wood products, wood building products are substitutable for concrete and steel, and there are no market responses to increased wood use. The researchers conclude suggesting that many studies assessing forest management or products for climate change mitigation depend on a suite of assumptions. Wood products are likely a better option than steel or concrete in the building sector, in terms of climate change mitigation and reduced emissions. Policy instruments that allow for the external costs of carbon emissions to be internalized will provide a structural change. Governments could help reduce the uncertainty caused by the assumptions reviewed above by committing to global climate action that includes the forest sector.
Aspects of the authors’ results claim to diverge from prior studies in this field: “If demand for multi-family buildings made of concrete and steel goes down, the subsequent fall in the price of steel and concrete would increase the use of such materials elsewhere. We have not been able to find studies on cross-sectoral leakages in the construction industry,” Howard said. The authors note that “A limitation of the Brock Hall study was the lack of available data concerning certain context-specific environmental information. More data would be necessary in order for decision-makers to rely on these or similar results in planning future projects. However, acquiring much of this data can be time consuming, and that it may not be feasible to collect during the design phase of future buildings.” They recommend that there is some evidence that increased harvests will increase consumption of wood products. There are limited studies available that show this relationship empirically given historic data. It may be important to show this linear relationship in future studies focused on harvest rates and resulting effects on consumption.
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Researchers in China have found a positive relationship between above-ground and below-ground carbon stocks of mangrove forests in China and worldwide, which could be used to improve assessments of global carbon stocks.
Meng and colleagues (2021) reported on relationships between above- and below-ground carbon stocks in mangrove forests facilitate better estimation of total mangrove blue carbon. Average below-ground carbon stock was dominant, accounting for 69–91% of total carbon stock. More than 10% of terrestrial particulate carbon, including dissolved organic carbon, is exported into the ocean through mangroves. Mangrove forests only occupy 0.5% of global coastal area. Assessments of below-ground mangrove soil and ecosystem carbon stocks are generally limited to small-scale regions. The carbon stock ratio of soil to ecosystem was 0.43–0.88 for mangroves in China; the same trend exists when expanded to global Mangroves. Mangroves are one of the most important carbon sinks in global ecosystems.
The researchers observe that “Large-scale accurate estimation of carbon stock for mangrove ecosystems can be achieved by applying the local relationship between above- and below-ground ecosystem carbon stocks after remote sensing.” Data and code to reproduce the analyses can be found at: http://data.cma.cn.
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Astragalus sinicus L. and rice straw retention combined with reduced mineral fertilizer is better in reducing chemical fertilizer amount, increasing crop yield and carbon input, which is more conductive to sustainable development of agriculture.
Liu and colleagues (2021) reported on comparison of carbon footprint and net ecosystem carbon budget under organic material retention combined with reduced mineral fertilizer. Treatment RB is better in reducing chemical fertilizer amount, increasing crop yield and carbon input. Greenhouse gas emissions from all the treatments ranged from 9731 to 19,584 kg CO2 equivalent ha−1. The difference of GHG emissions between treatments RA, RC and control CK was significant. increasing studies indicate that straw retention can sequestrate C and mitigate GHG emissions through directly inputting soil organic carbon. The group conducted a 2-year field experiment to test the following hypotheses: whether organic material retention combined with reduced mineral fertilizer can increase crop C input? A mixed linear model was used to analyze the effects of fertilizer and year on mean GHG, CO2, C input, C footprint, crop biomass, and NECB.
Aspects of the researchers’ conclusions claim to corroborate earlier work in this subject: “Compared with C footprint of control CK, treatments RA and RC increased by 60.32% and 34.92%. Treatment RB decreased by 17.46% which may attributed to the less N fertilizer application amount,” Liu suggested.
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A large-scale study of cumulative forest disturbance in the Chilcotin watershed in British Columbia, Canada, has shown that carbon stocks and sequestration can be sustained despite a dramatic increase in disturbance rates.
In ‘Dramatic increase in water use efficiency with cumulative forest disturbance at the large forested watershed scale’, Giles-Hansen and colleagues (2021) reported that forest disturbance induced changes in the coupling of forest carbon and water have important consequences for ecosystem functioning and sustainable forest management. With the dramatic forest disturbance increase from 2000 to 2016 which was mainly due to Mountain Pine Beetle, watershed-level carbon stocks and sequestration showed an insignificant reduction. A concurrent significant decrease in annual evapotranspiration (ET), led to a 19% increase in WUE.
Some of the results look to corroborate previous studies in this area: “The cohort of young, fast growing forest has the effect of increasing the overall growth rate of the watershed. This finding is similar to other retrospective studies in British Columbia that found carbon uptake in recovering young forests was able to partially offset disturbance emissions,” Giles-Hansen said. However, “Study periods usually cover just a few years following disturbance. Forest disturbances of different types cumulate over space and long periods of time. Effects on forest carbon, water and WUE may be different.” Giles-Hansen and colleagues contend that studies investigating long term trends in WUE under the effect of climate change have mixed results. Those looking at leaf or tree intrinsic WUE have often found an increase that is attributed to CO2 fertilization or other climate factors.
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A study of carbon stocks in the páramo ecosystem of South Ecuador has shown that pine plantations can store high amounts of carbon above and belowground, without negatively affecting the soils.
Dahik and colleagues (2021) described impacts of pine plantations on carbon stocks of páramo sites in southern Ecuador. At seven locations within an elevational gradient from 2780 to 3760 m a.s.l., they measured and compared carbon stocks of three types of land use: natural grassland, grazed páramo, and Pinus patula Schlltdl Patula plantations. The biomass of roots was calculated by the collection of one soil sample at three depths: 0–15 cm, 15–30 cm, and 30–45 cm. The researchers found that total soil organic carbon was high across all sites (118.6 to 373.2 tC/ha). Since the 1990’s, afforestation programs in the páramo have been implemented to offset carbon emissions through carbon sequestration. Many pine plantations have been established in order to capture and fix carbon dioxide from the atmosphere through the program PROFAFOR. This study suggests that forestry plans should be assessed case by case, considering the limiting factor of elevation.
In 1875, the first species of Eucalyptus were introduced with the intention to produce timber, fuel and to restore degraded Andean soils. In 1928, around seventy species of conifers were introduced including some Pinus spp., and after several years of testing, the government implemented afforestation programs with the best adapted species. Some of the results appear to corroborate previous studies in this subject: “For our study we selected three types of land use which correspond to different intensities of human intervention. Páramo natural grassland sites had characteristics similar to those in good state of conservation as described by Hofstede et al,” Dahik posited.
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