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Given that industry is the major source of carbon emissions, clarifying the carbon transfer regularity triggered by industry production linkage is of great importance in realizing the synergistic development of industry to reduce pollution and carbon emissions. Based on the perspective of responsibility allocation, the study accounted for the industry carbon emissions and constructed a carbon transfer weighted directed network model and applied the social network analysis method to explore the structure of the industry carbon transfer network and its evolution characteristics from 2005 to 2020. The results showed that： ① The overall carbon emissions of industries from 2005 to 2020 presented a rapid growth trend and large differences occurred in emissions between industries. ② The scale of the carbon transfer network was expanding rapidly and the characteristics of the small-world network were significant. ③ The community structure of the carbon transfer network was obvious, including four optimal associations： high carbon emission, carbon transmission, carbon endogenous, and high spillover. ④ The construction industry and the metal smelting and rolling processing industry were the core of the carbon transfer network structure, with strong network control. In view of the above characteristics, we proposed countermeasures and suggestions in terms of implementing the allocation of carbon emission reduction responsibilities and differentiated emission reduction measures for associations as well as focusing on the management of core nodes of the network, with the intent of providing cross-sectoral synergistic emission reduction ideas for the development of sustainable low-carbon transformation in China's industry sector.

Economic activities among multiple regions are always accompanied by carbon transfers. Analyzing coupling characteristics of economic activities and carbon transfer linkages based on the supply-demand relationships, can further reveal the networked structures of the multiregional interactions and common development trend of various industries, shedding light on carbon emission governance and high-quality development. This study advances novel coupling network models at the regional and industrial levels, and empirically analyzes the coupling characteristics in China based on the input-output data in 2012, 2015, and 2017. The findings reveal a noticeable decoupling process of economic activities and carbon transfers, but with distinct characteristics at the regional and industrial levels. The widening differences in coupling among provinces indicate increasing regional disparities. The decoupling process at the industrial level is primarily driven by the decreased connectivity in networked carbon transfers, instead of economic activities, reflecting the significant variations of industries' low-carbon development. The carbon decoupling process is notably more pronounced in supply-demand chains associated with export as the final use, compared to those linked with capital formation and final consumption. Analysis of coupling characteristics and the identification of decoupling evolution process enhance our understanding of the relationship between economic activities and carbon transfer, and may provide valuable insights for prioritizing actions and achieving efficient carbon emission reduction., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The use of stable-isotope probing (SIP) allows tracing specific labeled substrates into fungi leading to a better understanding of their role in biogeochemical cycles and their relationship with their environment. Stable isotope probing combined with ribosomal RNA molecule, conserved in the three kingdoms of life, and messenger RNA analysis permits the linkage of diversity and function. Here, we describe two methods designed to investigate the interactions between plants and their associated mycorrhizal compartment by tracing carbon flux from the host plant to its symbionts., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Based on the gross trade accounting method and WIOD data, this paper quantifies the global carbon transfer from 2000 to 2014. The social network analysis and temporal exponential random graph model (TERGM) are employed to investigate the structural change and influencing factors of global carbon transfer network from a global value chains (GVCs) perspective. Results show that the deepening of the GVC division connection has enhanced the relations in global carbon transfer network, and the low reciprocity and high disassortativity lie in the difference in GVC division positions among economies. Block model analysis manifests that Plate Ⅱ acts as the engine plate in the network which consists of China and the other four economies. The GVC division connection and relative GVC division position significantly facilitate the formation of carbon emission transfer relations. Moreover, economies' attribute effects and endogenous network structure effects are non-negligible important determinants of network formation., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Mycorrhizal fungi can colonize multiple trees of a single or multiple taxa, facilitating bidirectional exchange of carbon between trees. Mycorrhiza-induced carbon transfer was shown in the forest, but it is unknown whether carbon is shared symmetrically among tree species, and if not, which tree species are better donors and which are better recipients. Here, we test this question by investigating carbon transfer dynamics among five Mediterranean tree species in a microcosm system, including both ectomycorrhizal (EM) and arbuscular (AM) plants. Trees were planted together in "community boxes" using natural soil from a mixed forest plot that serves as a habitat for all five tree species and their native mycorrhizal fungi. In each box, only the trees of a single species were pulse-labelled with 13 CO 2 . We found that carbon transfer was asymmetric, with oak being a better donor, and pistacia and cypress better recipients. Shared mycorrhizal species may have facilitated carbon transfer, but their diversity did not affect the amount, nor timing, of the transfer. Overall, our findings in a microcosm system expose rich, but hidden, belowground interactions in a diverse population of trees and mycorrhizal fungi. The asymmetric carbon exchange among cohabiting tree species could potentially contribute to forest resilience in an uncertain future., (© 2022 The Authors. Molecular Ecology published by John Wiley & Sons Ltd.)

Orchids rely on mycorrhizal symbiosis, especially in the stage of mycoheterotrophic protocorms, which depend on carbon and energy supply from fungi. The transfer of carbon from fungi to orchids is well-documented, but the identity of compounds ensuring this transfer remains elusive. Some evidence has been obtained for the role of amino acids, but there is also vague and neglected evidence for the role of soluble carbohydrates, probably trehalose, which is an abundant fungal carbohydrate. We therefore focused on the possible role of trehalose in carbon and energy transfer. We investigated the common marsh orchid ( Dactylorhiza majalis ) and its symbiotic fungus Ceratobasidium sp. using a combination of cultivation approaches, high-performance liquid chromatography, application of a specific inhibitor of the enzyme trehalase, and histochemical localization of trehalase activity. We found that axenically grown orchid protocorms possess an efficient, trehalase-dependent, metabolic pathway for utilizing exogenous trehalose, which can be as good a source of carbon and energy as their major endogenous soluble carbohydrates. This is in contrast to non-orchid plants that cannot utilize trehalose to such an extent. In symbiotically grown protocorms and roots of adult orchids, trehalase activity was tightly colocalized with mycorrhizal structures indicating its pronounced role in the mycorrhizal interface. Inhibition of trehalase activity arrested the growth of both symbiotically grown protocorms and trehalose-supported axenic protocorms. Since trehalose constitutes only an inconsiderable part of the endogenous saccharide spectrum of orchids, degradation of fungal trehalose likely takes place in orchid mycorrhiza. Our results strongly support the neglected view of the fungal trehalose, or the glucose produced by its cleavage as compounds transported from fungi to orchids to ensure carbon and energy flow. Therefore, we suggest that not only amino acids, but also soluble carbohydrates are transported. We may propose that the soluble carbohydrates would be a better source of energy for plant metabolism than amino acids, which is partially supported by our finding of the essential role of trehalase., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Ponert, Šoch, Vosolsobě, Čiháková and Lipavská.)

The application of organic fertilizers (OF) can supply carbon (C) to the soil in crop fields. OF-derived C (OF-C) is often estimated using the differential method that can be biased due to indirect effects of OF on soil C. This study tested three methods to quantify OF-C: (i) the widespread differential method, (ii) the synchronic isotope method comparing plots with and without OF and (iii) the asynchronic isotope method mimicking a trial without a control plot. These methods were implemented on an Arenosol and an Andosol supplied during 13 years with slurry or compost. The results highlighted the relevance of using the synchronic isotope method, which focuses on the direct effect of OFs on the soil organic matter (without bias of vegetation change) and considers control soil's evolution. The higher the isotopic difference between soil and OF, the shorter the method implementation time needed: for an initial difference of 7.5 ‰ and 3.5 ‰, quantification is suitable after 4 and 9 years of fertilization respectively. Attention should be paid to OF-δ 13 C variability to guarantee the method validity. The method proved to be suitable to study the factors controlling the OF-C fate in tropical soils.

Previous soil sampling from grazed pastures in New Zealand compared the changes of soil organic carbon (SOC) in adjacent irrigated and unirrigated portions of the same paddocks. It showed that irrigated portions had lower SOC stocks than unirrigated portions, with an average difference of 7.0 tC ha -1 or 0.6 tC ha -1  yr -1 . These findings have formed the basis of an assessment for the net effect of conversion of New Zealand's grazed pastures to irrigation. However, since cattle could move freely between irrigated and unirrigated portions of the studied paddocks, there could have been different grazing intensities and/or excreta transfer between the irrigated and unirrigated portions of the same paddocks. Both these factors could have affected SOC stocks. In this study, we used the process-based model, CenW, to simulate the consequences of this possible carbon transfer via animal excreta and different grazing intensities. We found that the observed increase of 0.6 tC ha -1  yr -1 in SOC stock in the unirrigated portions could result from a transfer of 20% excreta from the irrigated to unirrigated portions (with an area ratio of 6:1) of a paddock and with the unirrigated portions being grazed only lightly with 2.0 tDM ha -1 in foliage biomass residuals remaining after grazing. That means that the observed higher SOC stocks in the unirrigated portions could potentially be attributable to the behaviour of grazing animals. We suggest that a realistic extent of carbon transfer and/or differences in grazing intensities could be sufficient to account for the observed differences in SOC stocks even if irrigation per se caused no differences in carbon stocks. It is therefore inappropriate to ascribe the change of SOC to irrigation effects based on experimental findings where SOC changes can be affected by the behaviour of grazing animals., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest., (Copyright © 2021 Elsevier B.V. All rights reserved.)

This paper constructs an embodied carbon model in inter-provincial trade based on China's inter-provincial multi-regional input-output table. By analyzing the embodied carbon emissions for Guangdong with the forefront of economic development, this research reveals the impact of trade scale and structure between Guangdong Province and other provinces on embodied carbon emissions, and finds out key provinces and sectors for emission reduction. It can enable national and regional economic and environmental policies to be implemented into specific industries, guide capital flow to key sectors for emission reduction, provide comments for relevant national and provincial decision-making sectors to adjust trade structure, and play the role of inter-provincial trade in energy conservation and emission reduction.

Resource endowment and economic development of different provinces in China vary greatly, resulting in large amount of CO 2 transfers. We need further exploration to help decision makers allocate emission responsibilities reasonably. We construct China's embodied CO 2 transfer network (CTN) in 2012 from the perspective of provinces and sectors based on multi-regional input-output (MRIO) model and complex network analysis. The key CO 2 transfer nodes and paths, final demand decomposition, topological structure, clustering characteristics, and influencing factors are analyzed. The results show that the average CO 2 transfer length from one province (sector) to another is only 1.323 (1.584). The top three net CO 2 importers (45.39% of the total), located in developed eastern coastal area, mainly import CO 2 from energy-rich but underdeveloped provinces such as Heilongjiang. It presents a CO 2 transfer pattern from north to south and from west to east. CO 2 transfer in energy industry is mainly driven by urban household consumption. Non-adjacent provinces with distance greater than 750 km have no significant spillover effect and difference in technology level has the greatest impact on CTN. This work is important for differentiating the roles of provinces and sectors in CTN, guiding the allocation of carbon credits and controlling total CO 2 emissions.

As environmental issues aggravated heavily, China faces increasing pressure and challenges on carbon emission reduction and distribution. we used non-competitive input-output table (I-O table) combined with the methods of Structural Path Analysis (SPA) and Multidimensional Analytical Framework (MAF), based on the data of China in 2012, to analyze the current situation of inter-sector carbon emission transfer and identify the key sectors and the critical paths from multiple perspectives. Our results show that total fixed capital formation is the main final demand. The electricity, petroleum, and metal smelting are the largest carbon outflow sectors, which emit carbon at the upstream of the path. Construction and other services are the most obvious carbon inflow sectors, which belong to the middle and downstream of the path and lead to indirect carbon emissions through their demands for other sectors. "Metal smelting → Construction → Total fixed capital formation," "Nonmetallic products → Construction → Total fixed capital formation," and "Petroleum → Urban consumption," "Electricity → Urban consumption" are the top four paths with large carbon emission, which deserve attention. Finally, this paper puts forward some policy implications on emission reduction based on the results.

The difference in time lags between a labeling pulse of 13 CO 2 of the foliage and the appearance of labeled C in the respiration at different locations along the stem of a tall plant is used to estimate at which velocities the isotope tracer, i.e., the labeled carbohydrates, are transported in the phloem sap. Here we describe a method for pulse-labeling tall plants in the field and subsequently tracing 13 C in the respiratory efflux of CO 2 .

Arbuscular mycorrhiza (AM) fungi establish symbiotic interactions with plants, providing the host plant with minerals, i.e. phosphate, in exchange for organic carbon. Arbuscular mycorrhiza fungi of the order Glomerales produce vesicles which store lipids as an energy and carbon source. Acyl-acyl carrier protein (ACP) thioesterases (Fat) are essential components of the plant plastid-localized fatty acid synthase and determine the chain length of de novo synthesized fatty acids. In addition to the ubiquitous FatA and FatB thioesterases, AM-competent plants contain an additional, AM-specific, FatM gene. Here, we characterize FatM from Lotus japonicus by phenotypically analyzing fatm mutant lines and by studying the biochemical function of the recombinant FatM protein. Reduced shoot phosphate content in fatm indicates compromised symbiotic phosphate uptake due to reduced arbuscule branching, and the fungus shows reduced lipid accumulation accompanied by the occurrence of smaller and less frequent vesicles. Lipid profiling reveals a decrease in mycorrhiza-specific phospholipid forms, AM fungal signature fatty acids (e.g. 16:1ω5, 18:1ω7 and 20:3) and storage lipids. Recombinant FatM shows preference for palmitoyl (16:0)-ACP, indicating that large amounts of 16:0 fatty acid are exported from the plastids of arbuscule-containing cells. Stable isotope labeling with [ 13 C 2 ]acetate showed reduced incorporation into mycorrhiza-specific fatty acids in the fatm mutant. Therefore, colonized cells reprogram plastidial de novo fatty acid synthesis towards the production of extra amounts of 16:0, which is in agreement with previous results that fatty acid-containing lipids are transported from the plant to the fungus., (© 2018 The Authors The Plant Journal © 2018 John Wiley & Sons Ltd.)

The Norris Geyser Basin in Yellowstone National Park contains a large number of hydrothermal systems, which host microbial populations supported by primary productivity associated with a suite of chemolithotrophic metabolisms. We demonstrate that Metallosphaera yellowstonensis MK1, a facultative autotrophic archaeon isolated from a hyperthermal acidic hydrous ferric oxide (HFO) spring in Norris Geyser Basin, excretes formaldehyde during autotrophic growth. To determine the fate of formaldehyde in this low organic carbon environment, we incubated native microbial mat (containing M. yellowstonensis) from a HFO spring with (13)C-formaldehyde. Isotopic analysis of incubation-derived CO2 and biomass showed that formaldehyde was both oxidized and assimilated by members of the community. Autotrophy, formaldehyde oxidation, and formaldehyde assimilation displayed different sensitivities to chemical inhibitors, suggesting that distinct sub-populations in the mat selectively perform these functions. Our results demonstrate that electrons originally resulting from iron oxidation can energetically fuel autotrophic carbon fixation and associated formaldehyde excretion, and that formaldehyde is both oxidized and assimilated by different organisms within the native microbial community. Thus, formaldehyde can effectively act as a carbon and electron shuttle connecting the autotrophic, iron oxidizing members with associated heterotrophic members in the HFO community.

Potassium (K) is an important limiting factor of tree growth, but little is known of the effects of K supply on the long-distance transport of photosynthetic carbon (C) in the phloem and of the interaction between K fertilization and drought. We pulse-labelled 2-year-old Eucalyptus grandis L. trees grown in a field trial combining K fertilization (+K and -K) and throughfall exclusion (+W and -W), and we estimated the velocity of C transfer by comparing time lags between the uptake of (13)CO2 and its recovery in trunk CO2 efflux recorded at different heights. We also analysed the dynamics of the labelled photosynthates recovered in the foliage and in the phloem sap (inner bark extract). The mean residence time of labelled C in the foliage was short (21-31 h). The time series of (13)C in excess in the foliage was affected by the level of fertilization, whereas the effect of throughfall exclusion was not significant. The velocity of C transfer in the trunk (0.20-0.82 m h(-1)) was twice as high in +K trees than in -K trees, with no significant effect of throughfall exclusion except for one +K -W tree labelled in the middle of the drought season that was exposed to a more pronounced water stress (midday leaf water potential of -2.2 MPa). Our results suggest that besides reductions in photosynthetic C supply and in C demand by sink organs, the lower velocity under K deficiency is due to a lower cross-sectional area of the sieve tubes, whereas an increase in phloem sap viscosity is more likely limiting phloem transport under drought. In all treatments, 10 times less (13)C was recovered in inner bark extracts at the bottom of the trunk when compared with the base of the crown, suggesting that a large part of the labelled assimilates has been exported out of the phloem and replaced by unlabelled C. This supports the 'leakage-retrieval mechanism' that may play a role in maintaining the pressure gradient between source and sink organs required to sustain high velocity of phloem transport in tall trees., (© The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The use of stable-isotope probing (SIP) allows tracing specific labeled substrates into fungi leading to a better understanding of their role in biogeochemical cycles and their relationship with their environment. Stable-isotope probing combined with ribosomal RNA molecule, conserved in the three kingdoms of life, and messenger RNA analysis permits the linkage of diversity and function. Here, we describe two methods designed to investigate the interactions between plant and its associated mycorrhizal compartment by tracing carbon flux from the host plant to its symbionts.

We investigated in the field the carbon (C) transfer between sugar maple (Acer saccharum) saplings and the spring ephemeral Erythronium americanum via the mycelium of arbuscular mycorrhizal (AM) fungi. Sugar maple saplings and E. americanum plants were planted together in pots placed in the ground of a maple forest in 1999. Ectomycorrhizal yellow birches (Betula alleghaniensis) were added as control plants. In spring 2000, during leaf expansion of sugar maple saplings, the leaves of E. americanum were labelled with 14 CO 2 . Seven days after labelling, radioactivity was detected in leaves, stem and roots of sugar maples. Specific radioactivity in sugar maples was 13-fold higher than in yellow birches revealing the occurrence of a direct transfer of 14 C between the AM plants. The quantity of 14 C transferred to sugar maple saplings was negatively correlated with the percentage of 14 C allocated to the storage organ of E. americanum. A second labelling was performed in autumn 2000 on sugar maple leaves during annual growth of E. americanum roots. Radioactivity was detected in 7 of 22 E. americanum root systems and absent in yellow birches. These results suggest that AM fungi connecting different understorey species can act as reciprocal C transfer bridges between plant species in relation with the phenology of the plants involved.

Interspecific C transfer was studied in laboratory microcosms containing pairs of 6-month-old Betula papyrifera Marsh, and Pseudotsuga menziesii (Mirb.) Franca seedlings growing in individual, root-restrictive (28μm pore size) pouches filled with field soil. Interspecific transfer was examined by reciprocal labelling of seedlings with 13 CO 2(gas) and 14 CO 2(gas) . At the time of labelling, the root zones of ectomycorrhizal (EM) B. papyrifera and P. menziesii were interconnected by an extensive network of EM mycelium. Carbon transferred through EM connections was distinguished from that through soil pathways by comparing microcosms where interconnecting hyphae were left intact vs. those where they were severed immediately before labelling. Transfer was bidirectional, and represented 5 % of total isotope uptake by both B. papyrifera and P. menziesii together. P. menziesii received on average 50% more 14 C and 66% more 13 C from paper birch than vice versa, however, differences between species were not statistically significant. Neither net nor bidirectional transfer differed between severing treatments, leaving in question the relative importance of EM hyphae versus soil transfer pathways. The tendency for P. menziesii to receive more isotope than B. papyrifera corresponded with a 10-fold greater net photosynthetic rate per seedling and two-fold greater foliar N concentration of B. papyrifera than P. menziesii.

To investigate the long-distance transport of nitrogen and carbon from mature leaves, two stable isotopes, (15)N and (13)C, were introduced to a single mature sunflower leaf for less than 2 hr in the forms of NO2 and CO2, and the fate of (15)N and (13)C in plants was followed. In the first experiment, about 4 ppm (15)NO2 was applied to a mature sunflower leaf for 65 min in light, and the fate of (15)N was followed over 72 hr. (15)NO2 absorbed in sunflower was first incorporated into the ethanol-soluble fraction, then gradually incorporated into the ethanol-insoluble fraction: after 24 hr, only 12% remained in the soluble fraction in the fed leaf. Some (15)N was transferred from the fed leaf, first to the stems and next to the young growing leaves and roots, although negligible transfer to other mature leaves was detected. In the second experiment, 3.1 ppm (15)NO2 and 300-400 ppm (13)CO2 were simultaneously introduced to a single mature leaf for 110 min in light, and the fate of the two isotopes was followed for 28 days. Most of the (13)C transfer from the fed leaf took place within 1 day, whereas the transfer of (15)N continued gradually during the experimental period after a small rapid transfer within 1 day. Just after isotope feeding, the ratios of transferred (13)C to (15)N were high in all parts and remained high in the lower stem and the root, although they decreased very rapidly in the upper leaves and the upper stem. In the root, (15)N did not show a significant loss while some (13)C loss occurred during the experimental period. The transfer of (13)C and (15)N to the lower leaves was very low. (13)C Studies showed that carbon of the flower originated from both reserved carbon and current photosynthates., (Copyright © 1980. The Japanese Society of Plant Physiologists.)

In intact seedlings of Eucalyptus pilularis Stn. ectomycorrhizal with Pisolithus tinctorius (Pers.) Coker & Couch in growth pouches, and labelled photosynthetically with 14 C 4 more radioactivity was translocated into mycorrhizal than to non-mycorrhizal roots. Results from autoradiography of intact root systems were supported by data from scintillation counting of individual root tips. Greater 14 C accumulation occurred in young than in older mycorrhizas. It is proposed that individual mycorrhizal roots act most strongly as carbon sinks early in their life and that there is a progressive reduction in the amount of photosynthate translocated to them as they age.