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The terrestrial ecosystem in China mitigates 21%–45% of the national contemporary fossil fuel CO2 emissions every year. Maintaining and strengthening the land carbon sink is essential ...for reaching China’s target of carbon neutrality. However, this sink is subject to large uncertainties due to the joint impacts of climate change, air pollution, and human activities. Here, we explore the potential of strengthening land carbon sink in China through anthropogenic interventions, including forestation, ozone reduction, and litter removal, taking advantage of a well-validated dynamic vegetation model and meteorological forcings from 16 climate models. Without anthropogenic interventions, considering Shared Socioeconomic Pathways (SSP) scenarios, the land sink is projected to be 0.26–0.56 Pg C a−1 at 2060, to which climate change contributes 0.06–0.13 Pg C a−1 and CO2 fertilization contributes 0.08-0.44 Pg C a−1 with the stronger effects for higher emission scenarios. With anthropogenic interventions, under a close-to-neutral emission scenario (SSP1-2.6), the land sink becomes 0.47-0.57 Pg C a−1 at 2060, including the contributions of 0.12 Pg C a−1 by conservative forestation, 0.07 Pg C a−1 by ozone pollution control, and 0.06-0.16 Pg C a−1 by 20% litter removal over planted forest. This sink can mitigate 90%–110% of the residue anthropogenic carbon emissions in 2060, providing a solid foundation for the carbon neutrality in China.
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Forestation is important for sequestering atmospheric carbon, and it is a cost-effective and nature-based solution (NBS) for mitigating global climate change. Here, under the ...assumption of forestation in the potential plantable lands, we used the forest carbon sequestration (FCS) model and field survey involving 3365 forest plots to assess the carbon sequestration rate (CSR) of Chinese existing and new forestation forests from 2010 to 2060 under three forestation and three climate scenarios. Without considering the influence of extreme events and human disturbance, the estimated average CSR in Chinese forests was 0.358 ± 0.016 Pg C a–1, with partitioning to biomass (0.211 ± 0.016 Pg C a–1) and soil (0.147 ± 0.005 Pg C a–1), respectively. The existing forests account for approximately 93.5% of the CSR, which will peak near 2035, and decreasing trend was present overall after 2035. After 2035, effective tending management is required to maintain the high CSR level, such as selective cutting, thinning, and approximate disturbance. However, new forestation from 2015 in the potential plantable lands would play a minimal role in additional CSR increases. In China, the CSR is generally higher in the Northeast, Southwest, and Central-South, and lower in the Northwest. Considering the potential losses through deforestation and logging, it is realistically estimated that CSR in Chinese forests would remain in the range of 0.161–0.358 Pg C a–1 from 2010 to 2060. Overall, forests have the potential to offset 14.1% of the national anthropogenic carbon emissions in China over the period of 2010–2060, significantly contributing to the carbon neutrality target of 2060 with the implementation of effective management strategies for existing forests and expansion of forestation.
Electrification of all sectors needs net zero electricity (NZE) to slash greenhouse gas emissions (GHG), 38% of the global annual energy-related GHG of 34 Gt CO2eq. NZE is to avoid climate ...catastrophe, predicted at 2.7 °C rise in global mean temperature by 2100 (at 50% probability). There is no consensus approach to the sustainable development of NZE systems. This study has developed a novel, rigorous, holistic life cycle assessment methodology for a sustainable NZE roadmap or pathway. It identifies the leading fifteen countries with the highest gross domestic products with over 90% GHG. It compiles Ecoinvent life cycle inventory for in-country NZE systems and calculates their life cycle impacts using ReCiPe, Impact 2002+, and Environmental Prices methods. The global mean ranking of non-fossil systems is (kg CO2eq/GJ, US$/GJ): hydro-run-of-river (1.49, 0.73), hydro-reservoir (7.77, 0.91), wind:1–3 MW (7.37, 3.9), solar-20MW (13.94, 4.18), solar-50MW (15.29, 4.84), wind:>3 MW (9.55, 9.68), geothermal (19.99, 9.84), and bioenergy (12.09, 36.28). In decreasing order of significance, sustainability determinants are particulate emissions, land use, human toxicity, climate change, acidification, and ionisation radiation. To hit NZE (0.02–0.24 kg CO2eq/kWh), Brazil, the USA, Spain, Germany, France, Canada, Japan, Italy, and the UK need 52–95% decarbonization. Russia, Indonesia, Mexico, and Turkey can achieve 61%, 31%, 6%, and 4% decarbonization to 0.24–0.56 kg CO2eq/kWh, while with 0.52 and 0.65 kg CO2eq/kWh, China's and India's transitioning may slow down by this time. Robust NZE relies on improving health in developing countries, de-fossilized resource-technology diversification, and natural soil organic carbon sequestration, enhancing biodiversity and forestation.
T The reed communities along lakeshores are important for preventing shore erosion and enhancing biological production by phytoplankton and benthic invertebrates. However, if reed communities are ...located in inundated areas when the water level rises, they can dam up waste that would otherwise flow downstream. Additionally, unless the reeds are regularly mown and the cut vegetation is removed, the dead reeds can be carried downstream. In Lake Teganuma in Chiba Prefecture, the dead material washed out of the reed beds can stop the operation of the drainage pump station, and it can cause fishery damage if carried downstream into the Tone River. In this study, we used topographic maps and aerial photographs to clarify the formation and mechanisms of reed community development at the mouth of the Ohori River, the inflow river of Teganuma, and we confirmed their present condition through field surveys. The aerial photographs and old topographic maps showed that the field survey sites were located within water bodies from 1947 to 1955 and that the reed colonies were not as dense as they are today. The results of this study indicate that, since the 1960s, the reed colonies at the mouth of the Ohori River have been artificially altered from their natural state to their present form.
•The emissions equivalent of shortwave forcing resulting from global dryland forestation has been revisited.•Overlooking hydroclimatic conditions leads to an overestimation of the emissions ...equivalent of shortwave forcing and an underestimation of the net carbon sequestration potential in prior assessments.•Evaluating the efficacy of forestation as a nature-based solutions should go beyond carbon-centric perspectives.
In the global pursuit of climate mitigation, extensive tree planting initiatives have targeted the vast drylands. However, the carbon sequestration potential of forestation in these regions remains uncertain, primarily due to the oversight of crucial factors like vegetation-climate interactions. By revisiting the benefits of dryland forestation using comprehensive Earth System Modeling, we underscore the vital role of hydroclimatic factors in shaping the effectiveness of nature-based solutions, urging a reassessment of criteria for accurate carbon-centric estimates and sustainable global climate change mitigation strategies.
As a nature‐based and cost‐effective solution, forestation plays a crucial role in combating global warming, biodiversity collapse, environmental degradation, and global well‐being. Although China is ...acknowledged as a global leader of forestation and has achieved considerable overall success in environmental improvements through mega‐forestation programs, many negative effects have also emerged at local scales due to the planting of maladapted tree species. To better help achieve carbon neutrality and the new vision of an ecological civilization, China has committed to further increase forestation. However, where forestation lands and such efforts should really be located is not so well understood yet and agreed upon, especially in the face of rapid climate change. Based on an ensemble‐learning machine, we predicted the spatial habitats (ecological niche) of the forest, grassland, shrubland, and desert under present and future climate conditions based on the natural climax vegetation distribution across China. We show that the potential forestation lands are mainly located in eastern China, which is east of the Hu Line (also known as the Heihe‐Tengchong Line). Under future climate change, forests will shift substantially in the latitudinal, longitudinal, and elevational distribution. Potential forestation lands will increase by 33.1 million hectares through the 2070s, mainly due to the conversions of shrub and grassland to forests along the Hu Line. Our prediction map also indicates that grassland rehabilitation is the universal optimal vegetation restoration strategy in areas west of the Hu Line. This analysis is consistent with much of the observed evidence of forestation failures and recent climate‐change‐induced forest range shifts. Our results provide an overview and further show the importance of adaptive science‐based forestation planning and forest management.
China is acknowledged as a global leader of forestation, and it has pledged to further increase forestation to better help achieve carbon neutrality and the new vision of an ecological civilization. Here, we show that the potential forestation lands are mainly located in eastern China, that is east of the Hu Line, while grassland rehabilitation is the universal optimal vegetation restoration strategy in west of the Hu Line. Under future climate change, potential forestation lands will increase by 33.1 million hectares through the 2070s, mainly due to the conversions of shrub and grassland to forests along the Hu Line.
•Hydrological sensitivities (HSf) to both deforestation and forestation, and their contributing factors are synthesized around the globe.•Hydrological sensitivities to forestation are significantly ...larger than to deforestation.•Annual climate is the primary contributor to HSf, but intra-annual synchronicity of water and energy has a significant impact on HSf to forestation.•Watershed properties such as LAI, watershed size, and water retention capacity also contribute to HSf.
Hydrological sensitivity to forest change, defined as hydrological response intensity (%) per unit of forest cover change (%), is essential for understanding the magnitude of possible hydrological consequences caused by forest disturbance (e.g., deforestation, wildfire, and insect infestation) or forestation (e.g., reforestation and afforestation). This synthesis estimated and compared hydrological sensitivities (HSf) of annual streamflow to deforestation and forestation based on quantitative analyses of 311 watersheds across the globe. The roles of climate (both inter-annual and intra-annual) and watershed properties (e.g., topography-related water retention capacity, site condition, watershed size, forest type, and soil type) in HSf were assessed in deforestation and forestation groups, respectively. The key findings are: (1) hydrological sensitivities to forestation are significantly larger than those to deforestation, with an average value of 1.24% and 0.91% change in annual streamflow following 1% forestation and deforestation, respectively; (2) annual climate dryness (defined by PET/P at the annual scale) is the primary contributor to HSf to deforestation and forestation, with a relative importance of 75.5% and 60.6%, respectively, but intra-annual synchronicity of water and energy (i.e., greater matching in the timing of maximum P and maximum PET at the monthly scale) produces a significant impact on HSf to forestation; (3) leaf area index (LAI) has a contrasting effect on HSf to deforestation (negative response) versus forestation (positive response); (4) water retention index (IR) has a negative role in HSf, demonstrating that watersheds with larger water retention capacities are less hydrologically sensitive, particularly in the forestation group; (5) contrast to our general expectation, hydrological sensitivities to forestation are significantly greater in larger watersheds; and (6) hydrological responses are more sensitive to deforestation in watersheds with pure forest types and are more sensitive to forest cover change in Lithosols-dominated watersheds. Our findings suggest that hydrological effects between deforestation and forestation are not simply reversed and demonstrate that hydrological sensitivities are significantly influenced by climate and watershed properties. Hydrological sensitivities and their contributing drivers must be considered in protecting water and other aquatic properties.
Macroinvertebrates play a crucial role in maintaining soil structure, ecosystem function, and ecosystem services. They are highly sensitive to human disturbances and are used as bioindicators to ...assess interference with soil components. The primary objective of this study was to investigate the impact of secondary forestation on soil macroinvertebrates in the Caspian Hyrcanian forests. A comprehensive DNA barcoding approach was employed to examine community structures, diversity, and density of soil macroinvertebrates in relation to natural forests and re-planting strata. Macroinvertebrates were collected using transects and quadrates, and the composition of communities between natural and planted forests was compared on both broad (sampling locations/central part of the forest) and local (each forest) scales. A total of 172 OTUs (132 MOTUs and 40 MorphOTUs) were identified in this study. On the local scale, total density and diversity did not differ between the habitat types (natural and planted forests), unlike the broad scale. However, there was a significant change in community composition. The results of β-diversity and phylogenetic β-diversity approaches revealed a turnover between the two habitat types, with Hymenoptera (ants), Annelida (earthworms), and Arachnida contributing most to the dissimilarity between natural and secondary forests. Overall, despite observed changes in community composition, the stability in total populations between the two habitat types suggests that forests that have been deforested and replanted with trees for >20 years have had enough time to recover. Given the significant decrease in the Hyrcanian forests, particularly in recent decades, comprehensive information on the apparent impact of human disturbance on soil biota is necessary to address conservation issues.
•Soil pH decreased by 0.23 unit after forestation over the globe.•Climate was the most important predictor of soil pH change after forestation.•Forestation significantly decreased soil pH in humid ...areas but not in arid areas.
Forestation is a key strategy to mitigate climate change caused by anthropogenic carbon dioxide emissions. However, the impacts of forestation on soil pH remain unclear, despite critical roles of soil pH in regulating key soil biogeochemical processes. Here, we collected a global dataset of soil pH change after forestation, which included 1082 observations from 171 published papers. Results showed that soil pH declined significantly by 0.23 after forestation over the globe. Soil pH consistently declined after forestation, no matter the forest was established naturally or by planting, on croplands or grasslands. The decline of pH after forestation was generally larger in neutral soils (pH 6–7) than in acidic soils (pH < 6) and alkaline soils (pH > 7), and larger in boreal and temperate forests than in tropical forests. Soil pH decreased significantly in humid areas but not in arid regions. Random forest analysis showed that climate was the most important regulatory factor to influence soil pH change after forestation. Mean annual temperature and precipitation probably affected soil pH both directly and indirectly via altering soil physiochemical properties. Given vital roles of soil pH in regulating carbon and nutrient dynamics, our findings have important implications for the long-term impacts of forestation on carbon and nutrient dynamics.
In this study, a comparative literature-based assessment of the impact of operational factors such as climatic condition, vegetation type, availability of land, water, energy and biomass, management ...practices, cost and soil characteristics was carried out on six greenhouse gas removal (GGR) methods. These methods which include forestation, enhanced weathering (EW), soil carbon sequestration (SCS), biochar, direct air capture with carbon storage (DACCS) and bioenergy with carbon capture and storage (BECCS) were accessed with the aim of identifying the conditions and requirements necessary for their optimum performance. The extent of influence of these factors on the performance of the various GGR methods was discussed and quantified on a scale of 0–5. The key conditions necessary for optimum performance were identified with forestation, EW, SCS and biochar found to be best deployed within the tropical and temperate climatic zones. The CCS technologies (BECCS and DACCS) which have been largely projected as major contributors to the attainment of the emission mitigation targets were found to have a larger locational flexibility. However, the need for cost optimal siting of the CCS plant is necessary and dependent on the presence of appropriate storage facilities, preferably geological. The need for global and regional cooperation as well as some current efforts at accelerating the development and deployment of these GGR methods were also highlighted.
•The impact of operational factors on GGR methods have been quantified on a 0–5 scale.•Bio-geophysical factors have a major influence on the deployment of most GGR methods.•Tropical and temperate zones to play key role in GGR deployment.•The CCS-based methods have a larger locational flexibility.
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