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1.
Sci Total Environ ; 810: 152231, 2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-34896141

RESUMO

Earth system models (ESMs) have been widely used to simulate global terrestrial carbon fluxes, including gross primary production (GPP) and net primary production (NPP). Assessment of such GPP and NPP products can be valuable for understanding the efficacy of certain ESMs in simulating the global carbon cycle and future climate impacts. In this work, we studied the model performance of 22 ESMs participating in the fifth and sixth phases of the Coupled Model Intercomparison Project (CMIP5 and CMIP6) by comparing historical GPP and NPP simulations with satellite data from MODIS and further evaluating potential model improvement from CMIP5 to CMIP6. In CMIP6, the average global total GPP and NPP estimated by the 22 ESMs are 16% and 13% higher than MODIS data, respectively. The multi-model ensembles (MME) of the 22 ESMs can fairly reproduce the spatial distribution, zonal distribution and seasonal variations of both GPP and NPP from MODIS. They perform much better in simulating GPP and NPP for grasslands, wetlands, croplands and other biomes than forests. However, there are noticeable differences among individual ESM simulations in terms of overall fluxes, temporal and spatial flux distributions, and fluxes by biome and region. The MME consistently outperforms all individual models in nearly every respect. Even though several ESMs have been improved in CMIP6 relative to CMIP5, there is still much work to be done to improve individual ESM and overall CMIP performance. Future work needs to focus on more comprehensive model mechanisms and parametrizations, higher resolution and more reasonable coupling of land surface schemes and atmospheric/oceanic schemes.


Assuntos
Ciclo do Carbono , Ecossistema , Carbono , Clima , Mudança Climática
2.
Sci Total Environ ; 811: 152480, 2022 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-34923008

RESUMO

Forest plays an important role in reducing pressure on the natural environment, weaking the influence of greenhouse effects, and sequestrating atmospheric carbon dioxide. So far, due to the lack of complete understanding of forest ecosystem processes and the limitations on the scope of application of evaluation methods, there are still great uncertainties in the researches on carbon fluxes of forest ecosystems in China at the national level. In this study, an individual tree species FORCCHN model, which could flexibly use the inventory data as the initial field (more accurately) or use the remote sensing information to inverse initial field was applied. The dynamics of key carbon cycle fluxes (net primary productivity (NPP) and net ecosystem productivity (NEP)) and carbon sequestration of forest ecosystems in China from 1982 to 2019 were simulated based on remote sensing data and FORCCHN model. The results showed that forest ecosystems in China had great carbon sequestration potential over the past 39 years. From 1982 to 2019, the NPP of Chinese forests presented a fluctuated increase. Total NPP from 2011 to 2019 ranged from 0.91 PgC·a-1 to 1.14 PgC·a-1. Annual average NEP of forest ecosystems in China from 2011 to 2019 was 0.199 PgC·a-1 (1Pg = 1015 g). Influenced by climate, soil and vegetation, carbon sequestration potential in Chinese forest ecosystems presented obvious regional differences in space. The spatial distribution of NEP gradually increased from Northwest to Southeast China. From 2011 to 2019, forests in Yunnan Province had the strongest carbon storage capacity (72.79 TgC·a-1, 1Tg = 1012 g), followed by forests in Guangxi (18.49 TgC·a-1) and forests in Guangdong (10.01 TgC·a-1). Our results not only address concerns about carbon sequestration but also reflect the importance of Chinese forest resources in the development of the national economy and society.


Assuntos
Ecossistema , Tecnologia de Sensoriamento Remoto , Ciclo do Carbono , Sequestro de Carbono , China , Florestas , Árvores
3.
Sci Total Environ ; 806(Pt 4): 150890, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34666084

RESUMO

As carriers of dissolved and particulate loads that connect continental surfaces to oceans, river systems play a major role in the global carbon cycle. Indeed, riverine particulate organic carbon (POC) is a melange of various origins characterized by their own 14C labeling. In addition, civil nuclear activities have brought new 14C source that remains poorly documented. We propose to unravel the Δ14C value of POC stored in a sedimentary archive collected downstream the most nuclearized European rivers (the Loire River). We postulate that riverine POC is a mixture of aquatic POC (which could be impacted by the liquid discharge from nuclear industry), terrestrial and petrogenic POC. With a combination of radiocarbon measurements, POC analyses and the palynofacies method, we assessed the respective Δ14C value of the POC origins. The gaps between the Δ14C values of the sedimentary POC and those of the atmosphere were the result of the dilution from dead-C, the freshwater reservoir effect imprinting the Δ14C of aquatic POC and the age and transit time of terrestrial POC within the catchment. Importantly, we consider that the unravelling of radiocarbon composition of riverine POC could be useful to determine either the transit time of material from source to sink, some past industrial or natural events, the resilience of the river system and milestones of the social and economic trajectory of a catchment. For the last three decades, riverine sediments could also act as a source of radiocarbon for the atmosphere.


Assuntos
Carbono , Carbono/análise , Ciclo do Carbono , Monitoramento Ambiental , Rios
4.
Sci Total Environ ; 806(Pt 4): 151482, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34742811

RESUMO

Fire disturbance has increased in some tundra ecosystems due to anthropogenic climate change, with important ramifications for terrestrial carbon cycling. Assessment of the potential impact of fire-regime change on tundra carbon stocks requires long-term perspectives because tundra fires have been rare historically. Here we integrated the process-based Dynamic Organic Soil version of the Terrestrial Ecosystem Model with paleo-fire records to evaluate the responses of tundra carbon stocks to changes in fire return interval (FRI). Paleorecords reveal that mean FRIs of tundra ecosystems in Alaska ranged from centennial to millennial timescales (200-6000 years) during the late Quaternary, but projected FRIs by 2100 decrease to a few hundred years to several decades (70-660 years). Our simulations indicate threshold effects of changing FRIs on tundra carbon stocks. Shortening FRI from 5000 to 1000 years results in minimal carbon release (<5%) from Alaskan tundra ecosystems. Rapid carbon stock loss occurs when FRI declines below 800 years trigger sustained mobilization of ancient carbon stocks from permafrost soils. However, substantial spatial heterogeneity in the resilience/sensitivity of tundra carbon stocks to FRI change exists, largely attributable to vegetation types. We identified the carbon stocks in shrub tundra as the most vulnerable to decreasing FRI because shrub tundra stores a large share of carbon in combustible biomass and organic soils. Moreover, our results suggest that ecosystems characterized by large carbon stocks and relatively long FRIs (e.g. Brooks Foothills) may transition towards hotspots of permafrost carbon emission as a response to crossing FRI thresholds in the coming decades. These findings combined imply that fire disturbance may play an increasingly important role in future carbon balance of tundra ecosystems, but the net outcome may be strongly modulated by vegetation composition.


Assuntos
Ecossistema , Incêndios , Regiões Árticas , Carbono , Ciclo do Carbono , Mudança Climática , Solo , Tundra
5.
Sci Total Environ ; 806(Pt 3): 151335, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34743818

RESUMO

A fundamental challenge in verifying urban CO2 emissions reductions is estimating the biological influence that can confound emission source attribution across heterogeneous and diverse landscapes. Recent work using atmospheric radiocarbon revealed a substantial seasonal influence of the managed urban biosphere on regional carbon budgets in the Los Angeles megacity, but lacked spatially explicit attribution of the diverse biological influences needed for flux quantification and decision making. New high-resolution maps of land cover (0.6 m) and irrigation (30 m) derived from optical and thermal sensors can simultaneously resolve landscape influences related to vegetation type (tree, grass, shrub), land use, and fragmentation needed to accurately quantify biological influences on CO2 exchange in complex urban environments. We integrate these maps with the Urban Vegetation Photosynthesis and Respiration Model (UrbanVPRM) to quantify spatial and seasonal variability in gross primary production (GPP) across urban and non-urban regions of Southern California Air Basin (SoCAB). Results show that land use and landscape fragmentation have a significant influence on urban GPP and canopy temperature within the water-limited Mediterranean SoCAB climate. Irrigated vegetation accounts for 31% of urban GPP, driven by turfgrass, and is more productive (1.7 vs 0.9 µmol m-2 s-1) and cooler (2.2 ± 0.5 K) than non-irrigated vegetation during hot dry summer months. Fragmented landscapes, representing mostly vegetated urban greenspaces, account for 50% of urban GPP. Cooling from irrigation alleviates strong warming along greenspace edges within 100 m of impervious surfaces, and increases GPP by a factor of two, compared to non-irrigated edges. Finally, we note that non-irrigated shrubs are typically more productive than non-irrigated trees and grass, and equally productive as irrigated vegetation. These results imply a potential water savings benefit of urban shrubs, but more work is needed to understand carbon vs water usage tradeoffs of managed vs unmanaged vegetation.


Assuntos
Carbono , Temperatura Alta , Ciclo do Carbono , Clima , Tecnologia de Sensoriamento Remoto
6.
Sci Total Environ ; 810: 152315, 2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-34914988

RESUMO

The Angolan highlands are hydrologically and ecologically important, supporting peatland deposits. Peatlands are carbon rich ecosystems and are the largest terrestrial carbon store. We present a first estimate of the extent of peatlands in the Angolan Highlands, using Google Earth Engine. Our conservative estimate of peatland coverage is 1634 km2, 2.65% of a mapped area spanning approximately 61,590 km2. This is a crucial first step in providing the peatland carbon inventory for the region and to facilitate conservation and management strategies. We include the peatland characteristics with respect to topographic data and common remote sensing indices of Normalised Difference Vegetation Index and Normalised Difference Water Index. The results suggest that Angolan Highlands peatland is highly variable in terms of elevation, slope, vegetation cover and standing water occurrence. Radiocarbon dating of riparian peatlands suggest two stages of peatland initiation: one about 7100 cal. yr BP, during the African humid period, and another from about 1100 cal. yr BP to present after the African humid period ended. The temporal control of riparian peat formation is river dynamics and the formation of terraces. Source lake peatland is slightly younger and has average maximum age of 890 cal. yr BP. The Angolan Highlands ecosystem and peatlands are possibly under strain from anthropogenic influence and climate change, making this peatland deposit a potential carbon emission source.


Assuntos
Ecossistema , Solo , Carbono , Ciclo do Carbono , Mudança Climática
7.
Sci Total Environ ; 805: 150399, 2022 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-34818782

RESUMO

The forest floor is often considered the most important source of dissolved organic carbon (DOC) in forest soils, yet little is known about the relative contribution from different forest floor layers, understorey vegetation and deadwood. Here, we determine the carbon stocks and potential DOC production from forest materials: deadwood, ground vegetation, leaf litter, the fermentation layer and top mineral soil (Ah horizon), and further assess the impact of management. Our research is based on long-term monitoring plots in a temperate deciduous woodland, with one set of plots actively managed by thinning, understorey scrub and deadwood removal, and another set that were not managed in 23 years. We examined long-term data and a spatial survey of forest materials to estimate the relative carbon stocks and concentrations and fluxes of DOC released from these different pools. Long-term soil water monitoring revealed a large difference in median DOC concentrations between the unmanaged (43.8 mg L-1) and managed (18.4 mg L-1) sets of plots at 10 cm depth over six years, with the median DOC concentration over twice as high in the unmanaged plots. In our spatial survey, a significantly larger cumulative flux of DOC was released from the unmanaged than the managed site, with 295.5 and 230.3 g m-2, respectively. Whilst deadwood and leaf litter released the greatest amount of DOC per unit mass, when volume of the material was considered, leaf litter contributed most to DOC flux, with deadwood contributing least. Likewise, there were significant differences in the carbon stocks held by different forest materials that were dependent on site. Vegetation and the fermentation layer held more carbon in the managed site than unmanaged, whilst the opposite occurred in deadwood and the Ah horizon. These findings indicate that management affects the allocation of carbon stored and DOC released between different forest materials.


Assuntos
Carbono , Quercus , Ciclo do Carbono , Florestas , Solo
8.
Sci Total Environ ; 803: 150044, 2022 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-34525696

RESUMO

A typhoon is extreme weather that flushes terrestrial carbon (C) loads and temporally mixes the entire water columns of lakes in subtropical regions. A C flux varies based on the trophic level associated with the ecological cycle related to hydraulic retention time (residence time). Herein, we sought to clarify how the hydraulic retention time and the disturbance from a typhoon affect the C flux regimes in two subtropical mountain lakes in a humid region of Taiwan with different trophic levels-oligotrophic and mesotrophic. We investigated the meteorological data and vertical profiles of the water temperature, dissolved inorganic carbon (DIC), dissolved organic C (DOC), and chlorophyll a (Chl. a) during the pre-typhoon period (April-July), during the typhoon period (August-November), and the post-typhoon period (December-March) for five years (2009-2010 and 2015-2017). We applied a three-dimensional environmental model (Fantom) to investigate the hydraulic retention effect on the net ecosystem production (NEP) using the residence time in stratified lakes. The results demonstrate that typhoon-induced mixing associated with the hydraulic retention effect plays one of the critical roles in controlling the NEP and C flux in shallow subtropical lakes.


Assuntos
Tempestades Ciclônicas , Lagos , Carbono , Ciclo do Carbono , Clorofila A , Ecossistema
9.
Sci Total Environ ; 803: 150061, 2022 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-34525705

RESUMO

Downed woody material (DWM) is a unique part of the forest carbon cycle serving as a pool between living biomass and subsequent atmospheric emission or transference to other forest pools. Thus, DWM is an individually defined pool in national greenhouse gas inventories. The diversity of DWM carbon drivers (e.g., decay, tree mortality, or wildfire) and associated high spatial variability make this a difficult-to-predict component of forest ecosystems. Using the now fully established nationwide inventory of DWM across the United States (US), we developed models, which substantially improved predictions of stand-level DWM carbon density relative to the current national-reporting model ('previous' model, here). The previous model was developed from published DWM carbon densities prior to the NFI DWM inventory. Those predictions were tested using NFI DWM carbon densities resulting in a poor fit to the data (coefficient of determination, or R2 = 0.03). We present new random forest (RF) and stochastic gradient boosted (SGB) regression models to prediction DWM carbon density on all NFI plots and spatially on all forest land pixels. We evaluated various biotic and abiotic regression predictors, and the most important were standing dead trees, long-term annual precipitation, and long-term maximum summer temperature. A RF model scored best for expanding predictions to NFI plots (R2 = 0.31), while an SGB model was identified for DWM carbon predictions based on purely spatial data (i.e., NFI-plot-independent, with R2 = 0.23). The new RF model predicts conterminous US DWM carbon stocks to be 15% lower than the previous model and 2% higher than NFI data expanded according to inventory design-based inference. The new NFI data-driven models not only improve the predictions of DWM carbon density on all plots, they also provide flexibility in extending these predictions beyond the NFI to make spatially explicit and spatially continuous estimates of DWM carbon on all forest land in the US.


Assuntos
Carbono , Ecossistema , Biomassa , Carbono/análise , Ciclo do Carbono , Estados Unidos , Madeira/química
10.
Sci Total Environ ; 802: 149958, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34525750

RESUMO

Recently, urban reforestation programs have emerged as potential carbon sinks and climate mitigates in urban landscapes. Thus, spatially explicit information on net primary productivity (NPP) of reforested trees in urban environments is central to understanding the value of reforestation initiatives in the global carbon budget and climate regulation potential. To date, numerous studies have mainly focused on natural and commercial forests NPP at a regional scale based on coarse spatial resolution remotely sensed data. Generally, local scale NPP studies based on fine spatial resolution data are limited. Therefore, this study sought to estimate aboveground NPP of an urban reforested landscape using biophysical and Sentinel-2 Multispectral Imager data derived variables. Using the MOD17 model, results showed that mean NPP ranged between 6.24 Mg C ha-1 with high coefficient of determination (R2: 0.92) and low RMSE (0.82 Mg ha-1) across all reforested trees within the study area. Results also showed a considerable variation in NPP among the reforested trees, with deciduous Acacia and Dalbergia obovate species showing the highest NPP (7.62 Mg C ha-1 and 7.58 Mg C ha-1, respectively), while the evergreen Syzygium cordatum and shrub Artemisia afra had the lowest NPP (4.54 Mg C ha-1 and 5.26 Mg C ha-1). Furthermore, the multiple linear regression analysis showed that vegetation specific biophysical variables (i.e. leaf area index, Normalized Difference Vegetation Index and Fraction of Photosynthetically Active Radiation) significantly improved the estimation of reforested aboveground NPP at a fine-scale resolution. These findings demonstrate the effectiveness of biophysical and remotely sensed variables in determining NPP (as carbon sequestration surrogate) at fine-scaled reforested urban landscape. Furthermore, the utility of species biometric measurements and MOD17 model offers unprecedented opportunity for improved local scale reforestation assessment and monitoring schedules.


Assuntos
Florestas , Árvores , Carbono , Ciclo do Carbono , Ecossistema , Folhas de Planta
11.
Sci Total Environ ; 805: 150226, 2022 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-34536883

RESUMO

Wood-based products can contribute to climate change mitigation by prolonging the storage of carbon in the anthroposphere. In Indonesia, however, many wood-based products originate from unsustainable sources due to widespread land-use changes over the past decades. To reconcile economic development and climate policy, a detailed and comprehensive carbon life cycle assessment is needed, covering biospheric and technospheric woody carbon flows and emissions over time. In this study, we combine dynamic material flow analysis, stock modeling, and life cycle assessment to estimate life cycle carbon emissions over time of wood products from different land conversion types in Indonesia on a hectare (ha) basis. Wood production from clear-cut primary forest conversions to oil palm, secondary forest, and timber plantations lead to net carbon emissions between 1206-1282, 436-449, and 629-958 t-CO2-eq/ha, respectively, at the end of the 200-year time horizon (TH). The counter-use scenarios of using non-renewable materials or energy instead of wood-based products for the same set of scenarios while leaving primary forests untouched display 44-57, 59-88, and 5-48% lower global warming potentials, respectively, at the end of the TH. Wood products from forest plantations on restored degraded land (DL_FP), reduced-impact logging (RIL), and improved reduced-impact logging (RIL-C) of primary forest went beyond carbon neutrality, displaying carbon removal potentials of up to around -218, -378, and -739 t-CO2-eq/ha, respectively, by year 200. At the one ha-scale, our results indicate that keeping primary forests intact is the climate-preferable option, even when emissions from the counter-use of non-renewable materials or energy are factored in, except if RIL is performed. Therefore, wood product utilization would only be favorable from a climate perspective in DL_FP or RIL pathways. These results help screen different land conversion policy options and providing information about the climate mitigation potential of wood products in different supply chains.


Assuntos
Carbono , Madeira , Animais , Biomassa , Ciclo do Carbono , Florestas , Indonésia , Estágios do Ciclo de Vida
12.
Glob Chang Biol ; 28(1): 227-244, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34651375

RESUMO

Lianas are a key growth form in tropical forests. Their lack of self-supporting tissues and their vertical position on top of the canopy make them strong competitors of resources. A few pioneer studies have shown that liana optical traits differ on average from those of colocated trees. Those trait discrepancies were hypothesized to be responsible for the competitive advantage of lianas over trees. Yet, in the absence of reliable modelling tools, it is impossible to unravel their impact on the forest energy balance, light competition, and on the liana success in Neotropical forests. To bridge this gap, we performed a meta-analysis of the literature to gather all published liana leaf optical spectra, as well as all canopy spectra measured over different levels of liana infestation. We then used a Bayesian data assimilation framework applied to two radiative transfer models (RTMs) covering the leaf and canopy scales to derive tropical tree and liana trait distributions, which finally informed a full dynamic vegetation model. According to the RTMs inversion, lianas grew thinner, more horizontal leaves with lower pigment concentrations. Those traits made the lianas very efficient at light interception and significantly modified the forest energy balance and its carbon cycle. While forest albedo increased by 14% in the shortwave, light availability was reduced in the understorey (-30% of the PAR radiation) and soil temperature decreased by 0.5°C. Those liana-specific traits were also responsible for a significant reduction of tree (-19%) and ecosystem (-7%) gross primary productivity (GPP) while lianas benefited from them (their GPP increased by +27%). This study provides a novel mechanistic explanation to the increase in liana abundance, new evidence of the impact of lianas on forest functioning, and paves the way for the evaluation of the large-scale impacts of lianas on forest biogeochemical cycles.


Assuntos
Ecossistema , Clima Tropical , Teorema de Bayes , Ciclo do Carbono , Florestas
13.
Glob Chang Biol ; 28(1): 296-306, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34687116

RESUMO

Carbon cycle feedbacks were often quantified through the carbon-concentration and carbon-climate feedbacks with the assumption of no significant interaction between the two feedbacks in most previous studies. Here we calculated the strength of the interactions between the two responses using simulations of models participated in the phase 6 of the Coupled Model Intercomparison Project (CMIP6). We found that the nonlinear interaction contributed 11% of the land-atmosphere carbon exchange on average with large intermodel variation (from -20% to +162%). This nonlinear interaction is largely driven by the pattern of net primary production (NPP), with shifts in heterotrophic respiration that dampen the overall positive interactions from NPP. Photosynthetic rate per unit leaf area alone cannot adequately explain a wide variation of interactions in global NPP simulated by CMIP6 models. Plant respiration and processes that regulate leaf area are also important contributors to the interactions. Dominant factors that induce carbon-concentration and carbon-climate interactions are highly variable among models. One of those dominant factors is nutrient limitation. Using additional simulations of ACCESS-ESM1.5 that include both nitrogen and phosphorus limitation, we found that the estimated interactions by ACCESS-ESM1.5 with or without nutrient limitations covered the large intermodel variations among the CMIP6 models. It remains largely unknown how nutrient limitation complicates ecosystem's responses to simultaneously CO2 fertilization and warming at the global scale. Our modeling results point to a potential important role of nutrients, especially phosphorus on the nonlinear interactions. Yet, more studies are needed on ecosystem responses to concurrent changes in nutrient availability, atmospheric CO2 concentration, and warming.


Assuntos
Ciclo do Carbono , Ecossistema , Atmosfera , Carbono , Dióxido de Carbono , Retroalimentação , Nitrogênio
14.
Nat Commun ; 12(1): 7309, 2021 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-34911949

RESUMO

The ocean moderates the world's climate through absorption of heat and carbon, but how much carbon the ocean will continue to absorb remains unknown. The North Atlantic Ocean west (Baffin Bay/Labrador Sea) and east (Fram Strait/Greenland Sea) of Greenland features the most intense absorption of anthropogenic carbon globally; the biological carbon pump (BCP) contributes substantially. As Arctic sea-ice melts, the BCP changes, impacting global climate and other critical ocean attributes (e.g. biodiversity). Full understanding requires year-round observations across a range of ice conditions. Here we present such observations: autonomously collected Eulerian continuous 24-month time-series in Fram Strait. We show that, compared to ice-unaffected conditions, sea-ice derived meltwater stratification slows the BCP by 4 months, a shift from an export to a retention system, with measurable impacts on benthic communities. This has implications for ecosystem dynamics in the future warmer Arctic where the seasonal ice zone is expected to expand.


Assuntos
Carbono/análise , Camada de Gelo/química , Água do Mar/química , Oceano Atlântico , Ciclo do Carbono , Mudança Climática , Ecossistema , Groenlândia , Terra Nova e Labrador
15.
Ying Yong Sheng Tai Xue Bao ; 32(11): 3856-3864, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34898101

RESUMO

Facility agriculture, a typical agricultural production management mode, could affect carbon cycle due to its unique production environmental conditions and highly intensive utilization. With the five main sources as accounting objects, including agricultural film investment, energy consumption, pesticide and fertilizer application, CO2 fertilizer application, and facility soil, we estimated the amount and intensity of carbon emission of three facility agriculture (continuous greenhouse, solar greenhouse, and plastic greenhouse) in 31 provinces in 2018. The results showed that the total carbon emission of facility agriculture in China was 210.3817 million t CO2e, with the three facility agriculture types of plastic greenhouse, solar greenhouse, and continuous greenhouse accounting for 60.2%, 37.4% and 2.4%, respectively. Carbon emission of facility agriculture was mainly contributed by soil greenhouse gas, agricultural film and supplies investment. Carbon emission per unit area of continuous greenhouses was significantly lower than that of solar and plastic greenhouses. The scientific capital allocation rate and facility agriculture scale were the two main factors influencing the carbon emission in facility agriculture. Based on all the results, we presented the carbon emission reduction path from the three perspectives of improving the scientific investment, material consumption utilization rate, and facility area utilization rate of facility agriculture.


Assuntos
Agricultura , Carbono , Ciclo do Carbono , Fertilizantes , Solo
16.
Artigo em Inglês | MEDLINE | ID: mdl-34948666

RESUMO

The interactions between CO2 flux, an important component of ecosystem carbon flux, and climate change vary significantly among different ecosystems. In this research, the inter-annual variation characteristics of ecosystem respiration (RE), gross ecosystem exchange (GEE), and net ecosystem exchange (NEE) were explored in the temperate grassland (TG) of Xilinhot (2004-2010), the subtropical artificial coniferous forest (SACF) of Qianyanzhou (2003-2010), and the tropical rain forest (TRF) of Xishuangbanna (2003-2010). The main factors of climate change affecting ecosystem CO2 flux were identified by redundancy analysis, and exponential models and temperature indicators were constructed to consider the relationship between climate change and CO2 flux. Every year from 2003 to 2010, RE and GEE first increased and then decreased, and NEE showed no significant change pattern. TG was a carbon source, whereas SACF and TRF were carbon sinks. The influence of air temperature on RE and GEE was greater than that of soil temperature, but the influence of soil moisture on RE and GEE was greater than that of air moisture. Compared with moisture and photosynthetically active radiation, temperature had the greatest impact on CO2 flux and the exponential model had the best fitting effect. In TG and SACF, the average temperature was the most influential factor, and in TRF, the accumulated temperature was the most influential factor. These results provide theoretical support for mitigating and managing climate change and provide references for achieving carbon neutrality.


Assuntos
Ecossistema , Traqueófitas , Carbono , Ciclo do Carbono , Dióxido de Carbono , Mudança Climática , Florestas , Pradaria , Floresta Úmida , Estações do Ano
17.
Cells ; 10(12)2021 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-34943893

RESUMO

In vascular plants, cryptochromes acting as blue-light photoreceptors have various functions to adapt plants to the fluctuating light conditions on land, while the roles of cryptochromes in bryophytes have been rarely reported. In this study, we investigated functions of a single-copy ortholog of cryptochrome (MpCRY) in the liverwort Marchantia polymorpha. Knock-out of MpCRY showed that a large number of the mutant plants exhibited asymmetric growth of thalli under blue light. Transcriptome analyses indicated that MpCRY is mainly involved in photosynthesis and sugar metabolism. Further physiological analysis showed that Mpcry mutant exhibited a reduction in CO2 uptake and sucrose metabolism. In addition, exogenous application of sucrose or glucose partially restored the symmetrical growth of the Mpcry mutant thalli. Together, these results suggest that MpCRY is involved in the symmetrical growth of thallus and the regulation of carbon fixation and sucrose metabolism in M. polymorpha.


Assuntos
Ciclo do Carbono , Criptocromos/metabolismo , Marchantia/metabolismo , Sacarose/metabolismo , Sequência de Aminoácidos , Ciclo do Carbono/efeitos da radiação , Criptocromos/química , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Glucose/metabolismo , Luz , Marchantia/efeitos da radiação , Mutação/genética , Fotossíntese/genética , Fotossíntese/efeitos da radiação , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Transcrição Genética/efeitos da radiação
18.
PLoS One ; 16(12): e0261654, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34972143

RESUMO

Mangrove ecosystems, where litter and organic components are degraded and converted into detrital materials, support rich coastal fisheries resources. Sesarmid (Grapsidae) crabs, which feed on mangrove litter, play a crucial role in material flow in carbon-rich and nitrogen-limited mangrove ecosystems; however, the process of assimilation and conversion into detritus has not been well studied. In this study, we performed microbiome analyses of intestinal bacteria from three species of mangrove crab and five sediment positions in the mud lobster mounds, including the crab burrow wall, to study the interactive roles of crabs and sediment in metabolism. Metagenome analysis revealed species-dependent intestinal profiles, especially in Neosarmatium smithi, while the sediment microbiome was similar in all positions, albeit with some regional dependency. The microbiome profiles of crab intestines and sediments were significantly different in the MDS analysis based on OTU similarity; however, 579 OTUs (about 70% of reads in the crab intestinal microbiome) were identical between the intestinal and sediment bacteria. In the phenotype prediction, cellulose degradation was observed in the crab intestine. Cellulase activity was detected in both crab intestine and sediment. This could be mainly ascribed to Demequinaceae, which was predominantly found in the crab intestines and burrow walls. Nitrogen fixation was also enriched in both the crab intestines and sediments, and was supported by the nitrogenase assay. Similar to earlier reports, sulfur-related families were highly enriched in the sediment, presumably degrading organic compounds as terminal electron acceptors under anaerobic conditions. These results suggest that mangrove crabs and habitat sediment both contribute to carbon and nitrogen cycling in the mangrove ecosystem via these two key reactions.


Assuntos
Braquiúros/metabolismo , Ciclo do Carbono , Ecossistema , Microbioma Gastrointestinal , Sedimentos Geológicos , Intestinos/metabolismo , Ciclo do Nitrogênio , Acetileno/química , Animais , Carbono/metabolismo , Celulase/metabolismo , Celulose/química , Florestas , Metagenoma , Microbiota , Nitrogênio/metabolismo , Nitrogenase/metabolismo , Fenótipo , RNA Ribossômico 16S/metabolismo , Análise de Sequência de DNA , Análise de Sequência de RNA , Especificidade da Espécie , Tailândia
19.
PLoS One ; 16(12): e0261683, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34972150

RESUMO

Accurately predicting the crown photosynthesis of trees is necessary for better understanding the C circle in terrestrial ecosystem. However, modeling crown for individual tree is still challenging with the complex crown structure and changeable environmental conditions. This study was conducted to explore model in modeling the photosynthesis light response curve of the tree crown of young Larix principis-rupprechtii Mayr. Plantation. The rectangular hyperbolic model (RHM), non-rectangular hyperbolic model (NRHM), exponential model (EM) and modified rectangular hyperbolic model (MRHM) were used to model the photosynthetic light response curves. The fitting accuracy of these models was tested by comparing determinants coefficients (R2), mean square errors (MSE) and Akaike information criterion (AIC). The results showed that the mean value of R2 of MRHM (R2 = 0.9687) was the highest, whereas MSE value (MSE = 0.0748) and AIC value (AIC = -39.21) were the lowest. The order of fitting accuracy of the four models for Pn-PAR response curve was as follows: MRHM > EM > NRHM > RHM. In addition, the light saturation point (LSP) obtained by MRHM was slightly lower than the observed values, whereas the maximum net photosynthetic rates (Pmax) modeled by the four models were close to the measured values. Therefore, MRHM was superior to other three models in describing the photosynthetic response curve, the accurate values were that the quantum efficiency (α), maximum net photosynthetic rate (Pmax), light saturation point (LSP), light compensation point (LCP) and respiration rate (Rd) were 0.06, 6.06 µmol·m-2s-1, 802.68 µmol·m-2s-1, 10.76 µmol·m-2s-1 and 0.60 µmol·m-2s-1. Moreover, the photosynthetic response parameters values among different layers were also significant. Our findings have critical implications for parameter calibration of photosynthetic models and thus robust prediction of photosynthetic response in forests.


Assuntos
Larix/fisiologia , Fotossíntese/fisiologia , Árvores/fisiologia , Ciclo do Carbono , Dióxido de Carbono , China , Ecossistema , Florestas , Geografia , Luz , Modelos Biológicos , Taxa Respiratória
20.
Nutrients ; 13(12)2021 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-34960114

RESUMO

The 5-10-methylenetetrahydrofolate reductase (MTHFR) enzyme is vital for cellular homeostasis due to its key functions in the one-carbon cycle, which include methionine and folate metabolism and protein, DNA, and RNA synthesis. The enzyme is responsible for maintaining methionine and homocysteine (Hcy) balance to prevent cellular dysfunction. Polymorphisms in the MTHFR gene, especially C677T, have been associated with various diseases, including cardiovascular diseases (CVDs), cancer, inflammatory conditions, diabetes, and vascular disorders. The C677T MTHFR polymorphism is thought to be the most common cause of elevated Hcy levels, which is considered an independent risk factor for CVD. This polymorphism results in an amino acid change from alanine to valine, which prevents optimal functioning of the enzyme at temperatures above 37 °C. Many studies have been conducted to determine whether there is an association between the C677T polymorphism and increased risk for CVD. There is much evidence in favour of this association, while several studies have concluded that the polymorphism cannot be used to predict CVD development or progression. This review discusses current research regarding the C677T polymorphism and its relationship with CVD, inflammation, diabetes, and epigenetic regulation and compares the evidence provided for and against the association with CVD.


Assuntos
Doenças Cardiovasculares/epidemiologia , Metilenotetra-Hidrofolato Redutase (NADPH2)/genética , Metilenotetra-Hidrofolato Redutase (NADPH2)/metabolismo , Polimorfismo Genético , Ciclo do Carbono , Diabetes Mellitus/epidemiologia , Epigênese Genética , Feminino , Ácido Fólico/metabolismo , Fatores de Risco de Doenças Cardíacas , Homocisteína/metabolismo , Humanos , Inflamação/epidemiologia , Masculino , Metionina/metabolismo , Doenças Vasculares/epidemiologia , Vitamina B 12/metabolismo
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