Browsing by Subject "carbon sequestration"

Now showing 1 - 4 of 4
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    Current and future carbon stocks of natural forests in China
    (Elsevier, 2022-05-01) Chen, Shiyin; Lu, Nan; Fu, Bojie; Wang, Shuai; Deng, Lei; Wang, Lixin; Earth and Environmental Sciences, School of Science
    Natural regeneration of forests is the most cost-effective and most technically straightforward strategy to mitigate climate change. Natural forests account for 71% of China’s forested area, but their carbon stocks and sequestration potentials remain unclear. Here, we compiled data from 762 natural forest sites across China and found that natural forests had a carbon stock of 9.40 ± 1.45 Pg C in 2010. When naturally regenerated to the over-mature stage, existing natural forests can additionally sequestrate 8.67 ± 6.93 Pg C in the next two centuries, accounting for 48% of the carbon carrying capacity of the natural forest ecosystem in China, i.e. 18.07 ± 6.78 Pg C. Future carbon sequestration potential in natural forests is dominated by the tree layer at 6.88 ± 6.87 Pg, followed by the shrub layer at 1.02 ± 0.55 Pg, floor layer at 0.72 ± 0.74 Pg and herb layer at 0.05 ± 0.10 Pg. The natural forests are expected to achieve 70% of their future carbon sequestration potential by 2100. We also note that assisted regeneration via tree planting can play a significant role in natural forest restoration, as the carbon densities of natural and planted forests are rarely significantly different at the same age under 60 years old. Therefore, the preservation and expansion of natural forests is the key strategy for achieving long-term carbon sequestration.
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    Recent shift from dominant nitrogen to CO2 fertilization control on the growth of mature Qinghai spruce in China's Qilian Mountains
    (Elsevier, 2023-12) Wang, Ziyi; Liu, Xiaohong; Peñuelas, Josep; Camarero, J. Julio; Zeng, Xiaomin; Liu, Xueyan; Zhao, Liangju; Xu, Guobao; Wang, Lixin; Earth and Environmental Sciences, School of Science
    Terrestrial vegetation growth is stimulated by rising atmospheric CO2 concentration, a warmer climate, and increased soil nutrient availability. However, as plants age, progressive nutrient limitation is known to occur, especially in mature forests where soil nitrogen is deficient. Yet the long-term growth response of mature trees to rising CO2 accompanied by changing climate and nitrogen availability in semi-arid mountain regions is unclear. Here we used tree-ring widths and stable carbon (δ13C) and nitrogen (δ15N) isotopes to investigate the drivers of radial growth of mature Qinghai spruce (Picea crassifolia) in the central Qilian Mountains, northwest China, from 1840 through 2019. Tree growth benefited from improved nitrogen availability, chiefly via changes in bioavailable nitrogen pools modified by a favorable climate during 1930–1964. Enhanced intrinsic water-use efficiency (iWUE), driven by reduced stomatal conductance (gs) related to water deficit, lead to radial growth declines in 1985–2002. Recent acceleration of tree growth was largely attributed to a CO2 fertilization effect through enhanced iWUE during 2003–2019. Nitrogen availability was positively related to tree growth from the 1920s onward until greater CO2 fertilization ensued from 2000 onward. Hence, the negative effects of low nitrogen availability on growth could be mitigated or reversed by a high atmospheric CO2 concentration and warmer climate conditions. Our results suggest that mature spruce forests still harbor potential to increase ecosystem-level carbon sequestration and thereby partially mitigate climate warming. Such a nature-based solution in drought-prone forests would be achieved under warmer-wetter climate conditions in northwest China.
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    Soil organic carbon pools across paired no-till and plowed Alfisols of central Ohio
    (Wiley, 2016-12) Nakajima, Toru; Shrestha, Raj K.; Jacinthe, Pierre André; Lal, Rattan; Bilen, Serdar; Dick, Warren; Department of Earth Sciences, School of Science
    No-till (NT) farming can restore the soil organic carbon (SOC) pool of agricultural soils, but the SOC pool size and retention rate can vary with soil type and duration of NT. Therefore, the objectives of this study were to determine the effects of NT and soil drainage characteristics on SOC accumulation across a series of NT fields on Alfisols in Ohio, USA. Sites under NT for 9 (NT9), 13 (NT13), 36 (NT36), 48 (NT48) and 49 (NT49) years were selected for the study. Soil was somewhat poorly drained at the NT48 site but moderately well drained at the other sites. The NT48 and NT49 on-station sites were under continuous corn (Zea mays), while the other sites were farmers' fields in a corn–soybean (Glycine max) rotation. At each location, the SOC pool (0–30 cm) in the NT field was compared to that of an adjacent plough-till (PT) and woodlot (WL). At the NT36, NT48 and NT49 sites, the retention rate of corn-derived C was determined using stable C isotope (13C) techniques. In the 0- to 10-cm soil layer, SOC concentration was significantly larger under NT than PT, but a tillage effect was rarely detected below that depth. Across sites, the SOC pool in that layer averaged 36.4, 20 and 40.8 Mg C/ha at the NT, PT and WL sites, respectively. For the 0- to 30-cm layer, the SOC pool for NT (83.4 Mg C/ha) was still 57% greater than under PT. However, there was no consistent trend in the SOC pool with NT duration probably due to the legacy of past management practices and SOC content differences that may have existed among the study sites prior to their conversion to NT. The retention rate of corn-derived C was 524, 263 and 203 kg C/ha/yr at the NT36, NT48 and NT49 sites. In contrast, the retention rate of corn-C under PT averaged 25 and 153 kg C/ha/yr at the NT49 (moderately well-drained) and NT48 (somewhat poorly drained) sites, respectively. The conversion from PT to NT resulted in greater retention of corn-derived C. Thus, adoption of NT would be beneficial to SOC sequestration in agricultural soils of the region.
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    Where should we apply biochar?
    (IOP, 2019) Dokoohaki, Hamze; Miguez, Fernando E.; Dumortier, Jerome; School of Public and Environmental Affairs
    The heating of biomass under low-oxygen conditions generates three co-products, bio-oil, biogas, and biochar. Bio-oil can be stabilized and used as fuel oil or be further refined for various applications and biogas can be used as an energy source during the low-oxygen heating process. Biochar can be used to sequester carbon in soil and has the potential to increase crop yields when it is used to improve yield-limiting soil properties. Complex bio-physical interactions have made it challenging to answer the question of where biochar should be applied for the maximum agronomic and economic benefits. We address this challenge by developing an extensive informatics workflow for processing and analyzing crop yield response data as well as a large spatial-scale modeling platform. We use a probabilistic graphical model to study the relationships between soil and biochar variables and predict the probability and magnitude of crop yield response to biochar application. Our results show an average increase in crop yields ranging from 4.7% to 6.4% depending on the biochar feedstock and application rate. Expected yield increases of at least 6.1% and 8.8% are necessary to cover 25% and 10% of US cropland with biochar. We find that biochar application to crop area with an expected yield increase of at least 5.3%–5.9% would result in carbon sequestration offsetting 0.57%–0.67% of US greenhouse gas emissions. Applying biochar to corn area is the most profitable from a revenue perspective when compared to soybeans and wheat because additional revenues accrued by farmers are not enough to cover the costs of biochar applications in many regions of the United States.