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1.
Ying Yong Sheng Tai Xue Bao ; 32(1): 369-376, 2021 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-33477246

RESUMO

Soil aggregate, as a basic component of soils, plays an important role in improving soil structure and enhancing soil organic carbon (SOC) sequestration. The special soil properties induced by salinization, such as high ion concentrations (mainly Na+), shortage of organic material and bad condition of microbe, inhibit the formation and stability of soil aggregate. Therefore, it is important and meaningful to explore the dynamics of aggregate in salinized soils. Coastal wetland and inland salinized marsh wetland are important salinized ecosystems. We systematically summarized the progress and achievements on soil aggregate in salinized agriculture and wetland ecosystems. Agricultural practices, such as organic and/or inorganic soil amendment application, tillage practice, vegetation type, straw return and saline water irrigation, advance the formation and stability of aggregate and aggregate-associated organic carbon in salinized soils. We discussed the problems and deficiency in the present studies of aggregate and aggregate-associated carbon in salinized soils as well as the research aspects and hot topics in the future. This review would be helpful for comprehensively understanding the advances and development directions on aggregate in salinized soils.


Assuntos
Carbono , Solo , Agricultura , Sequestro de Carbono , Ecossistema
2.
J Environ Manage ; 281: 111903, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33421934

RESUMO

The world's soils store vast amounts (≈2,500 GT) of Carbon which acts as a vital sink to counterbalance the effects of increasing atmospheric carbon dioxide. There have been fruitful efforts to quantify soil Carbon stocks at national scales, which are required for policy level decisions but lack the high resolution required to support farm specific decisions. It is hypothesised that farm scale evaluations of soils can provide insight that is masked in national scale studies and can allow for spatially explicit management approaches to optimise soil Carbon storage and sequestration, such that it can be prioritized within profitable production systems. The objective of the present study was to estimate Carbon stocks on a range of heavy textured soils at field and farm scale and to quantify Carbon storage relative to national scale estimates. Ten grassland dairy farms (mean area of 52.2 Ha) were surveyed, sampled and classified to determine soil types and quantify soil Carbon stores. The level of Carbon present (mean: 346.0 T/Ha) at these sites was greater than previous averages on such soils quantified at national scale (by a factor of 1.1-3.9 depending on soil type). Furthermore, if Carbon saturation potential was realised, the amount of Carbon stored could be increased by an average of 792.1 T/Ha in each profile (from 346.0 to 1138.1 T/Ha). Current management has fostered the retention of large stores of soil Carbon on such soils/farms which co-exist within highly productive farm systems. As there is a societal demand to retain and enhance soil carbon stores to mitigate climate change, high Carbon soils should be identified and, under appropriate policies, commodified to offer a direct incentive to retain soil Carbon. The value of this resource should be recognised and polices to ensure a spatially explicit approach for soil Carbon management should be adopted.


Assuntos
Mudança Climática , Solo , Sequestro de Carbono , Fazendas , Irlanda
3.
Environ Sci Pollut Res Int ; 28(8): 8968-8988, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33443736

RESUMO

Environmental global issues affecting global warming, such as carbon dioxide (CO2), have attracted the attention of researchers around the world. This paper reviews and discusses the ground improvement and its contribution to reducing CO2 in the atmosphere. The approach is divided into three parts: the Streamlined Energy and Emissions Assessment Model (SEEAM), the replacement of soil stabilisation materials that lead to the emission of a large amount of CO2 with alternatives and mineral carbonation. A brief discussion about the first two is reviewed in this paper and a detailed discussion about mineral carbonation and its role in enhancing soil strength while absorbing a large amount of CO2. It is emphasised that natural mineral carbonation requires a very long time for a material to reach its full capacity to form CO2; as a result, different acceleration processes can be done from increasing pressure, temperature, the concentration of CO2 and the addition of various additives. In conclusion, it was found that magnesium is more attractive than calcium, and calcium is complicated in terms of strength behaviour. Magnesium has a larger capacity for CO2 sequestration and it has a greater potential to increase soil strength than calcium.


Assuntos
Dióxido de Carbono , Carbonatos , Sequestro de Carbono , Minerais , Temperatura
4.
J Environ Manage ; 283: 111978, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33477098

RESUMO

Globally, various estimates are available on the above-ground (plant parts) carbon (C) sequestering potential of agroforestry systems (AFSs). However, information on soil organic carbon (SOC) sequestration potential is limited for AFSs. Furthermore, the impacts of AFSs established for the restoration of C in degraded soils (prone to soil erosion, C and nutrients loss, etc.) of Himalayas are rarely investigated. Thus, a study was conducted on an agroforestry block established in 1989 at the Indian Council of Agricultural Research (ICAR), Research Complex for North Eastern Hill (NEH) Region, Lembucherra, Tripura, India. The AFSs comprised of four multipurpose tree species viz., teak (Tectona grandis Linn), sissoo (Dalbergia sissoo Roxb. Ex DC.), eucalyptus (Eucalyptus globulus L.), and neem (Azadirachta indica A. Juss) in combination with pineapple (Ananas comosus L. merr.). Planted in three times replicated randomized block design. After 28 years of establishment, the impacts of these AFSs were assessed on SOC stocks and its fraction pools. Results revealed that sissoo + pineapple system stored the highest SOC stocks in 0-15 cm (22.1 ± 1.4 Mg/ha) and 30-60 cm (18.0 ± 4.3 Mg/ha) depths, whereas the SOC stocks in 15-30 cm (12.2 ± 1.2 Mg/ha) and 0-30 cm (34.0 ± 1.6 Mg/ha) were the highest under teak + pineapple. When considering the entire 0-100 cm soil profile, the SOC stocks ranged between 65.3 and 71.6 Mg/ha across the diverse AFSs which was significantly higher than that under cultivated land (52.8 ± 2.6 Mg/ha). The sissoo + pineapple system had the highest SOC stock in 0-100 cm (71.6 ± 5.8 Mg/ha). The share of passive carbon (PC, less labile + non-labile) pools to SOC stocks under AFSs followed the order of sissoo + pineapple > teak + pineapple > neem + pineapple > eucalyptus + pineapple. The PC or recalcitrant pools of SOC stocks at 0-100 cm were 54.2-60.6% under various AFSs. Results revealed that the establishment of AFSs with pineapple on degraded lands increased a significant amount of C and had a considerable effect on soil quality in comparison to C present in soils under cropland. Thus, a large scale adoption of AFSs may restore C lost through the cultivation of the crop in degraded lands and provide a feasible option for livelihood through concurrent cultivation of multipurpose tree species and agri-horticulture crops.


Assuntos
Carbono , Solo , Agricultura , Carbono/análise , Sequestro de Carbono , Índia
5.
Sci Total Environ ; 752: 142279, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33207510

RESUMO

The present study compared the ecosystem organic carbon (OC) stocks and soil OC sources between two 12-year-old monospecific mangrove sites comprised of different species (Kandelia obovata in tree form and Aegiceras corniculatum in shrub form). We tested whether the carbon sequestration performance following rehabilitation varied with plantation of species in different forms and whether mangrove vegetation sequestrate OC more rapidly than soil pool. The results showed that mangrove rehabilitation increased the ecosystem OC stock relative to that of a non-vegetated bare flat. The accumulation of soil carbon was accompanied by increased soil total nitrogen contents and decreased δ13C values of soil OC, indicating that the increases in OC and TN contents were a function of accumulation of 13C-depleted mangrove materials in the soil. The sequestrated OC over the 12 years was considerably less in soil than in biomass at each mangrove site, suggesting that mangrove vegetation contributes more rapidly than the soil to ecosystem OC sequestration following rehabilitation before the vegetation has reached maturity. Compilation of the carbon stocks from worldwide rehabilitated mangrove forests with various ages further supports this finding. The K. obovata site had an apparently higher biomass OC stock but less OC in the soil than those at the A. corniculatum site. There was a higher standing leaf litter stock on the forest floor and more mangrove materials incorporated into the top 15 cm soil at the A. corniculatum site. These results suggested that the two rehabilitated mangrove sites had different development trajectories of both biomass and soil OC sequestration. Moreover, the performance of ecosystem carbon sequestration was related to plantation of different mangrove species. These carbon sequestration feature of rehabilitated mangrove forests therefore deserve attention in future rehabilitation programs to promote carbon sequestration performance.


Assuntos
Primulaceae , Rhizophoraceae , Biomassa , Carbono , Sequestro de Carbono , Ecossistema , Florestas , Solo
6.
Mar Pollut Bull ; 163: 111913, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33373889

RESUMO

Although seagrass ecosystems provide various ecosystem services, the implications in correspondence with temporal changes of the meadows is lacking. In this study, we analyzed two-decade changes of the seagrass area with the organic carbon storage and the sources at Libong island in Thailand. The seagrass area covered 841 ha in 2019, after two decades of decline (3.2 and 0.6% yr-1 between 2004 and 2009 and 2009-2019, respectively). Although δ13C was not significant between depth layers (p > 0.05), the general trend suggested that the terrestrial source of carbon is dominating bottom depth layer (31.7-37.2%), mixture of terrestrial (19.7-30.3%), seagrass (22.9-29.6%), mangrove (16.8-43.0%) and CPOM (11.2-25.4%) in the middle, and mangroves and seagrasses are dominating surface layer (28.3-66.2 and 29.3-36.5%, respectively). These trends approximately correspond to the areal changes of the meadows, as well as changes of urban area and water quality, providing detailed information on the meadow changes and possible causes.


Assuntos
Carbono , Ecossistema , Carbono/análise , Sequestro de Carbono , Sedimentos Geológicos , Tailândia
7.
Sci Total Environ ; 750: 141719, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32858285

RESUMO

Organic amendments (OAs) application is a practical strategy to improve soil organic carbon (SOC) in agriculture. The present study evaluated the impact of different OAs on the transformation of carbon and the dynamics of microorganisms in a 77-day incubation experiment. The OA treatments applied included wheat straw (U + WS), pig manure (U + PM), compost (U + CP), and improved compost (U + IC), and the no amendment group was the CK. After incubation, the SOC increased significantly in the U + WS group, but the other OA treatments had no significant effect relative to the CK. Among the OA treatments, U + CP and U + IC had lower CO2-C cumulative mineralization and the highest humification of dissolved organic carbon (DOC). U + PM had the lowest SOC content and the lowest aromatization of DOC. Redundancy analyses (RDA) showed that the CO2-C cumulative mineralization directly influenced the DOC, extracted organic carbon (EOC) and microbial biomass carbon (MBC) in all treatments. Proteobacteria positively correlated with SOC and MBC, Bacteroidetes were significantly related to DOC, and Gemmatimonadetes had a significant negative relationship with CO2-C cumulative mineralization. These results showed that U + CP and U + IC were more conducive to carbon sequestration, and U + PM was the most unfavourable during the incubation. Wheat straw played an important role in the steady improvement of the SOC.


Assuntos
Carbono , Solo , Agricultura , Animais , Sequestro de Carbono , Esterco , Microbiologia do Solo , Suínos
8.
J Environ Manage ; 277: 111388, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33002812

RESUMO

Land degradation due to soil salinity and sodicity is a serious concern in arid ecosystems. Despite the importance of conservation tillage in carbon sequestration and improving soil properties, its effect on saline-sodic soils under amendment application remains unknown. Therefore, the present study aimed to explore the combined effects of inorganic (sulfuric acid and gypsum) and organic (vermicompost) soil amendments and tillage systems (zero, reduced and deep tillage) on saline-sodic soil properties and wheat productivity. Deep tillage with vermicompost application significantly improved soil physical and chemical properties compared with control. Interestingly, integration between deep tillage and vermicompost decreased soil salinity and sodicity by 37% and 34%, respectively, compared with zero tillage and unamended soils. The application of vermicompost surpassed chemical amendments in the improvement of saline-sodic soils and consequently increased the growth and yield of wheat, provided that deep tillage was used as a suitable tillage system. Although deep tillage reduced soil organic carbon, application of vermicompost not only compensated this reduction, but also significantly increased soil organic carbon. This confirms the potential of combined deep tillage and vermicompost as a method for environmentally reclaiming saline-sodic soils.


Assuntos
Solo , Triticum , Agricultura , Carbono , Sequestro de Carbono , Ecossistema
9.
J Environ Manage ; 280: 111698, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33349511

RESUMO

Ponds may hold significant stocks of organic carbon in their sediments and pond creation may offer a practical application for land managers to increase carbon storage. However, ponds are overlooked in global carbon budgets. Their potential significance is suggested by the abundance of ponds throughout terrestrial biomes and their high carbon burial rates, but we lack measures of sediment carbon stocks from typical ponds. We sampled sediment from lowland temperate ponds in north east England comparing carbon stocks from ponds categorised by surrounding land use, or dominant vegetation, or drying regime, along with measures of variation within ponds. Sediment carbon varied considerably between ponds. This variation was more important than any systematic variation between pond types grouped by land use, vegetation or drying, or any variation within an individual pond. Our estimates of pond sediment organic carbon give measures that are higher than from soils in widespread habitats such as temperate grassland and woodland, suggesting that ponds are significant for carbon budgets in their own right. Ponds are relatively easy to create, are ubiquitous throughout temperate biomes and can be fitted in amongst other land uses; our results show that pond creation would be a useful and practical application to boost carbon sequestration in temperate landscapes.


Assuntos
Carbono , Tanques , Carbono/análise , Sequestro de Carbono , Inglaterra , Sedimentos Geológicos
10.
Nat Commun ; 11(1): 5515, 2020 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-33168823

RESUMO

The carbon sink capacity of tropical forests is substantially affected by tree mortality. However, the main drivers of tropical tree death remain largely unknown. Here we present a pan-Amazonian assessment of how and why trees die, analysing over 120,000 trees representing > 3800 species from 189 long-term RAINFOR forest plots. While tree mortality rates vary greatly Amazon-wide, on average trees are as likely to die standing as they are broken or uprooted-modes of death with different ecological consequences. Species-level growth rate is the single most important predictor of tree death in Amazonia, with faster-growing species being at higher risk. Within species, however, the slowest-growing trees are at greatest risk while the effect of tree size varies across the basin. In the driest Amazonian region species-level bioclimatic distributional patterns also predict the risk of death, suggesting that these forests are experiencing climatic conditions beyond their adaptative limits. These results provide not only a holistic pan-Amazonian picture of tree death but large-scale evidence for the overarching importance of the growth-survival trade-off in driving tropical tree mortality.


Assuntos
Ecologia , Florestas , Árvores/crescimento & desenvolvimento , Biomassa , Brasil , Dióxido de Carbono , Sequestro de Carbono , Ecossistema , Monitoramento Ambiental , Modelos Biológicos , Modelos de Riscos Proporcionais , Fatores de Risco , Clima Tropical
11.
Mar Pollut Bull ; 160: 111168, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33181914

RESUMO

Climate Change solutions include CO2 extraction from atmosphere and water with burial by living habitats in sediment/soil. Nowhere on the planet are blue carbon plants which carry out massive carbon extraction and permanent burial more intensely concentrated than in SE Asia. For the first time we make a national and total inventory of data to date for "blue carbon" buried from mangroves and seagrass and delineate the constraints. For an area across Southeast Asia of approximately 12,000,000 km2, supporting mangrove forests (5,116,032 ha) and seagrass meadows (6,744,529 ha), we analyzed the region's current blue carbon stocks. This estimate was achieved by integrating the sum of estuarine in situ carbon stock measurements with the extent of mangroves and seagrass across each nation, then summed for the region. We found that mangroves ecosystems regionally supported the greater amount of organic carbon (3095.19Tg Corg in 1st meter) over that of seagrass (1683.97 Tg Corg in 1st meter), with corresponding stock densities ranging from 15 to 2205 Mg ha-1 and 31.3 to 2450 Mg ha-1 respectively, a likely underestimate for entire carbon including sediment depths. The largest carbon stocks are found within Indonesia, followed by the Philippines, Papua New Guinea, Myanmar, Malaysia, Thailand, Tropical China, Viet-Nam, and Cambodia. Compared to the blue carbon hotspot of tropical/subtropical Gulf of Mexico's total carbon stock (480.48 Tg Corg), Southeast Asia's greater mangrove-seagrass stock density appears a more intense Blue Carbon hotspot (4778.66 Tg Corg). All regional Southeast Asian nation states should assist in superior preservation and habitat restoration plus similar measures in the USA & Mexico for the Gulf of Mexico, as apparently these form two of the largest tropical carbon sinks within coastal waters. We hypothesize it is SE Asia's regionally unique oceanic-geologic conditions, placed squarely within the tropics, which are largely responsible for this blue carbon hotspot, that is, consistently high ambient light levels and year-long warm temperatures, together with consistently strong inflow of dissolved carbon dioxide and upwelling of nutrients across the shallow geological plates.


Assuntos
Sequestro de Carbono , Ecossistema , Ásia Sudeste , China , Golfo do México , Indonésia , Malásia , Papua Nova Guiné , Filipinas , Tailândia , Vietnã , Áreas Alagadas
12.
PLoS One ; 15(10): e0239906, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33031401

RESUMO

Shifting cultivation has resulted in large-scale deforestation and forest degradation in the tropics; however the abandoned fallows are known to have high potential for carbon capture. The paper is an attempt to determine the forest recovery patterns following shifting cultivation by evaluating the tree species composition, diversity and abundance with respect to topographical factors in Manipur, India. We also used ordination analysis to understand the change in species composition with regard to environmental variables. The living woody biomass carbon of each fallow was quantified, and the factors affecting the recovery of carbon stock along an increasing fallow gradient was assessed. Our results showed that the species richness and basal area recovered relatively with time since abandonment, and the north-facing lower elevation fallow sites displayed higher species richness and stem density than those in higher elevations. Environmental variables had no impact on the regeneration of Elaeocarpus floribundus Blume and Castanopsis hystrix Hook. f. & Thomson ex A. DC. which suggests that they may be capable of effective restoration of degraded forest areas. As these species appear naturally in the forests, it would facilitate quicker rehabilitation and reinstate the soil nutrients making the soil reusable in a short term. We also found that fallow age plays a vital role in recovering above-ground biomass carbon from living woody species followed by the aspect of the site. The total living woody biomass carbon ranged from 0.98 Mg ha-1 in 5 years fallow to 142.58 Mg ha-1 in 20 years fallow. The above-ground biomass carbon recovery of the oldest fallow was 39% to 40% of the reference undisturbed forest and the estimated time for the shifting cultivation fallows to reach that of the undisturbed forest level was approximately 39 years to 41 years.


Assuntos
Agricultura , Conservação dos Recursos Naturais , Florestas , Árvores/crescimento & desenvolvimento , Biomassa , Carbono/metabolismo , Sequestro de Carbono , Índia
13.
Mar Environ Res ; 162: 105156, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33032080

RESUMO

Coralline macroalgae are globally distributed rhodopyhtes that remove carbon from their immediate environment and transform it into carbonate sediments through the senescence of their calcified tissues. In this study, the calcium carbonate (CaCO3) stocks in the tissue of Jania adhaerens and sediments in Tanjung Adang Shoal, Johor were quantified for a 13-month study period. The detailed maps of the geographical distribution based on the spatial and temporal variations of biomass and CaCO3 were also assessed. The highest amount of biomass, CaCO3 and organic carbon (OC) stocks in the tissues showed the highest in May 2018 and May 2019. The biomass values ranged from 65 to 143 g DW m-2, which contained 53-147 g CaCO3 m-2 and 3-11 g OC m-2. These findings provided insights into the biogeochemical cycling of these inputs, which can be used to estimate the overall carbon budget of the macrophyte meadow.


Assuntos
Carbono , Alga Marinha , Sequestro de Carbono , Ecossistema , Sedimentos Geológicos
14.
Nat Commun ; 11(1): 4241, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32901006

RESUMO

Land vegetation is currently taking up large amounts of atmospheric CO2, possibly due to tree growth stimulation. Extant models predict that this growth stimulation will continue to cause a net carbon uptake this century. However, there are indications that increased growth rates may shorten trees' lifespan and thus recent increases in forest carbon stocks may be transient due to lagged increases in mortality. Here we show that growth-lifespan trade-offs are indeed near universal, occurring across almost all species and climates. This trade-off is directly linked to faster growth reducing tree lifespan, and not due to covariance with climate or environment. Thus, current tree growth stimulation will, inevitably, result in a lagged increase in canopy tree mortality, as is indeed widely observed, and eventually neutralise carbon gains due to growth stimulation. Results from a strongly data-based forest simulator confirm these expectations. Extant Earth system model projections of global forest carbon sink persistence are likely too optimistic, increasing the need to curb greenhouse gas emissions.


Assuntos
Sequestro de Carbono , Carbono/metabolismo , Árvores/crescimento & desenvolvimento , Mudança Climática , Simulação por Computador , Longevidade , Mortalidade , Árvores/metabolismo
15.
Ecotoxicol Environ Saf ; 205: 111359, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32961490

RESUMO

As one of the most commonly used and frequently detected herbicides in the coastal seawater, the ecotoxicity of atrazine to phytoplankton has been well demonstrated. However, little attention has been paid to the ecotoxicity of its two major hydrolysates (desisopropylatrazine (DIA) and desethylatrazine (DEA)), which are also widely distributed in natural seawater. Here we present a comprehensive analysis of the photosynthetic physiology and chromophoric dissolved organic matter (CDOM) characteristics of the diatom Phaeodactylum tricornutum Pt-1 (CCMP 2561) under atrazine, DIA and DEA stress, respectively. The results showed that both atrazine and the two derivatives had significant negative effects on the concentration of chlorophyll a, maximum quantum efficiency (Fv/Fm) and relative electron transport rates (rETR) of P. tricornutum Pt-1. Furthermore, the CDOM pattern released by P. tricornutum Pt-1 cells also changed significantly after 7-day exposure. Compared with the control group, the fluorescence intensity (3D-EEM spectra) of protein-like components was obviously lower, while that of the humic acid-like components was higher. The findings of this study indicate that the ecotoxicity of atrazine might have been underestimated in previous investigations: both atrazine and its two major derivatives are not only phototoxic to microalgae but also influence the carbon sequestration potential in the coastal seawater.


Assuntos
Atrazina/toxicidade , Sequestro de Carbono , Diatomáceas/fisiologia , Fotossíntese/efeitos dos fármacos , Clorofila A , Diatomáceas/efeitos dos fármacos , Transporte de Elétrons , Fluorescência , Herbicidas/toxicidade , Microalgas , Fitoplâncton/efeitos dos fármacos , Água do Mar
16.
Nature ; 585(7826): 545-550, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32968258

RESUMO

To constrain global warming, we must strongly curtail greenhouse gas emissions and capture excess atmospheric carbon dioxide1,2. Regrowing natural forests is a prominent strategy for capturing additional carbon3, but accurate assessments of its potential are limited by uncertainty and variability in carbon accumulation rates2,3. To assess why and where rates differ, here we compile 13,112 georeferenced measurements of carbon accumulation. Climatic factors explain variation in rates better than land-use history, so we combine the field measurements with 66 environmental covariate layers to create a global, one-kilometre-resolution map of potential aboveground carbon accumulation rates for the first 30 years of natural forest regrowth. This map shows over 100-fold variation in rates across the globe, and indicates that default rates from the Intergovernmental Panel on Climate Change (IPCC)4,5 may underestimate aboveground carbon accumulation rates by 32 per cent on average and do not capture eight-fold variation within ecozones. Conversely, we conclude that maximum climate mitigation potential from natural forest regrowth is 11 per cent lower than previously reported3 owing to the use of overly high rates for the location of potential new forest. Although our data compilation includes more studies and sites than previous efforts, our results depend on data availability, which is concentrated in ten countries, and data quality, which varies across studies. However, the plots cover most of the environmental conditions across the areas for which we predicted carbon accumulation rates (except for northern Africa and northeast Asia). We therefore provide a robust and globally consistent tool for assessing natural forest regrowth as a climate mitigation strategy.


Assuntos
Sequestro de Carbono , Carbono/metabolismo , Agricultura Florestal/estatística & dados numéricos , Agricultura Florestal/tendências , Florestas , Mapeamento Geográfico , Árvores/crescimento & desenvolvimento , Árvores/metabolismo , Conservação dos Recursos Naturais , Coleta de Dados , Recuperação e Remediação Ambiental , Aquecimento Global/prevenção & controle , Internacionalidade , Cinética
17.
PLoS One ; 15(9): e0239552, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32970779

RESUMO

Low productivity and climate change require climate-smart agriculture (CSA) for sub-Saharan Africa (SSA), through (i) sustainably increasing crop productivity, (ii) enhancing the resilience of agricultural systems, and (iii) offsetting greenhouse gas emissions. We conducted a meta-analysis on experimental data to evaluate the contributions of combining organic and mineral nitrogen (N) applications to the three pillars of CSA for maize (Zea mays). Linear mixed effect modeling was carried out for; (i) grain productivity and agronomic efficiency of N (AE) inputs, (ii) inter-seasonal yield variability, and (iii) changes in soil organic carbon (SOC) content, while accounting for the quality of organic amendments and total N rates. Results showed that combined application of mineral and organic fertilizers leads to greater responses in productivity and AE as compared to sole applications when more than 100 kg N ha-1 is used with high-quality organic matter. For yield variability and SOC, no significant interactions were found when combining mineral and organic fertilizers. The variability of maize yields in soils amended with high-quality organic matter, except manure, was equal or smaller than for sole mineral fertilizer. Increases of SOC were only significant for organic inputs, and more pronounced for high-quality resources. For example, at a total N rate of 150 kg N ha-1 season-1, combining mineral fertilizer with the highest quality organic resources (50:50) increased AE by 20% and reduced SOC losses by 18% over 7 growing seasons as compared to sole mineral fertilizer. We conclude that combining organic and mineral N fertilizers can have significant positive effects on productivity and AE, but only improves the other two CSA pillars yield variability and SOC depending on organic resource input and quality. The findings of our meta-analysis help to tailor a climate smart integrated soil fertility management in SSA.


Assuntos
Agricultura/métodos , Fertilizantes/análise , Solo/química , África ao Sul do Saara , Carbono/análise , Sequestro de Carbono/fisiologia , Esterco/análise , Minerais , Nitrogênio/análise , Fósforo , Triticum , Zea mays/metabolismo
18.
Chemosphere ; 254: 126881, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957288

RESUMO

Application of biochar (BC) derived from rice straw has generated increasing interest in long-term storage of soil organic carbon (SOC), however its carbon (C) sequestration potential vary widely among agricultural soils despite the same BC dose used. These discrepancies in the ability of soils to sequester C after BC application are poorly understood. Metabolic quotient (qCO2) is a reflection of "microbial efficiency" and linked to SOC turnover across ecosystems. Therefore, we investigated the SOC sequestration and qCO2 in a Yellow River alluvium paddy soil (YP) and a quaternary red clay paddy soil (QP) under rice-wheat annual rotation following 4-year of BC application rate of 11.3 Mg ha-1 per cropping season. BC application consistently brought 65.3 Mg C ha-1 into the soils over 4-year experimental period but increased SOC by 57.6 Mg C ha-1 in YP and 64.5 Mg C ha-1 in QP. Calculating SOC mass balance showed 11.7% of BC-C losses from YP and only 1.16% from QP. BC application stimulated the G+ bacterial, fungi, and actinomycetes by increasing O-alkyl C content in YP, while decreased the same microorganisms by decreasing anomeric C-H content in QP. Importantly, higher clay and amorphous Fe (Feo) contents in QP after BC application protected SOC from further decomposition, which in turn decreased microorganisms and resulted in higher SOC sequestration than YP. Our results indicated that soil properties controlled the extent of SOC sequestration after BC application and site-specific soil properties must be carefully considered to maximize long-term SOC sequestration after BC application.


Assuntos
Agricultura/métodos , Sequestro de Carbono , Carvão Vegetal/química , Carbono/metabolismo , Argila , Ecossistema , Oryza/metabolismo , Solo/química
19.
PLoS One ; 15(8): e0237351, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32764813

RESUMO

Karst systems represent an important carbon sink worldwide. However, several phenomena such as the CO2 degassing and the exchange of cave air return a considerable amount of CO2 to the atmosphere. It is therefore of paramount importance to understand the contribution of the ecosystem to the carbon budget of karst areas. In this study conducted in a mid-succession ecosystem developed on abandoned karst grassland, two types of model were assessed, estimating the gross primary production (GPP) or the net ecosystem exchange (NEE) based on seven years of eddy covariance data (2013-2019): (1) a quadratic vegetation index-based empirical model with five alternative vegetation indices as proxies of GPP and NEE, and (2) the vegetation photosynthesis model (VPM) which is a light use efficiency model to estimate only GPP. The Enhanced Vegetation Index (EVI) was the best proxy for NEE whereas SAVI performed very similarly to EVI in the case of GPP in the empirical model setting. The empirical model performed better than the VPM model which tended to underestimate GPP. Therefore, for this ecosystem, we suggest the use of the empirical model provided that the quadratic relationship observed persists. However, the VPM model would be a good alternative under a changing climate, as it is rooted in the understanding of the photosynthesis process, if the scalars it involves could be improved to better estimate GPP.


Assuntos
Ciclo do Carbono , Sequestro de Carbono , Pradaria , Clima , Ecossistema , Modelos Biológicos , Fotossíntese
20.
Sci Total Environ ; 747: 141237, 2020 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-32791408

RESUMO

Forest deadwood is a relevant factor in the provision of ecosystem services (forest biodiversity, carbon sequestration, recreational and aesthetic values), but it also influences the risk and impact of forest perturbations. Hence, reliable estimations are urgently need in the lack of detailed information in Mediterranean forests at large scales. In this study we provide, for the first time, national-level estimations for Spain based on the information from the Spanish National Forest Inventory (38,945 plots). In addition, we compare and validate two approaches for estimating deadwood stocks where data is lacking; the first of these being a modelling approach based on stand, climatic and physiographical variables, and the other considers the ratio between deadwood and living biomass. We also examine the different patterns stock across forest types in four biogeographical regions according to a broad-spectrum of species groups and forests with different degrees of anthropogenic influence. The degrees are based on levels of protection and naturalness categories. The modelling approach provides more robust deadwood estimates and better predictive capacity than the ratio approach. Alpine (6.09 Mg.ha-1) and Atlantic (3.53 Mg.ha-1) bioregion forests store significantly higher mean deadwood biomass stocks than Macaronesian and Mediterranean forests. However, the share of deadwood in relation to the total biomass stock is greater in Mediterranean biogeographical region. As regards species groups, the mean deadwood stock of mixed forests doubled the stocks found in conifer and broadleaved dominated forests. We also found significant differences in deadwood biomass stocks between forests with different levels of anthropogenic protection. However, forest types with intensive forest management had contrasting figures for deadwood stock. The mean values obtained at national level according to forest type, bioregion and degree of anthropogenic influence, provide baseline information for carbon accounting as well as for other forest policy planning and management strategies.


Assuntos
Ecossistema , Florestas , Biomassa , Carbono/análise , Sequestro de Carbono , Espanha , Árvores
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