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Purpose Previous studies have found biochar-induced effects on native soil organic carbon (NSOC) decomposition, with a range of positive, negative and no priming reported. However, many uncertainties still exist regarding which parameters drive the amplitude and the direction of the biochar priming. Materials and methods We conducted a quantitative analysis of 1170 groups of data from 27 incubation studies using boosted regression trees (BRTs). BRT is a machine learning method combining regression trees and a boosting algorithm, which can effectively partition independent influences of various factors on the target variable in the complex ecological processes. Results and discussion The BRT model explained a total of 72.4% of the variation in soil carbon (C) priming following biochar amendment, in which incubation conditions (36.5%) and biochar properties (33.7%) explained a larger proportion than soil properties (29.8%). The predictors that substantially accounted for the explained variation included incubation time (27.1%) and soil moisture (5.0%), biochar C/N ratio (6.2%), nitrogen content (5.5%), pyrolysis time during biochar production (5.1%), biochar pH (4.5%), soil C content (5.2%), sand (4.7%) and clay content (4.1%). In contrast, other incubation conditions (temperature, biochar dose, whether nutrient was added), biochar properties (biochar C, feedstock type, ash content, pyrolysis temperature, whether biochar was activated) and soil properties (nitrogen content, silt content, C/N ratio, pH, land use type) had small contribution (each < 4%). Positive priming occurred within the first 2 years of incubations, with a change to negative priming afterwards. The priming was negative for low N biochar or in high-moisture soils but positive on their reverse sides. The size of negative priming increased with rising biochar C/N ratio, pyrolysis time and soil clay content, but deceased with soil C/N ratio. Conclusions We determine the critical drivers for biochar effect on native soil organic C cycling, which can help us to better predict soil C sequestration following biochar amendment.

In type 1 and type 2 diabetes mellitus, increased cardiac fibrosis, stiffness and associated diastolic dysfunction may be the earliest pathological phenomena in diabetic cardiomyopathy. Endothelial‐mesenchymal transition (EndMT) in endothelia cells (ECs) is a critical cellular phenomenon that increases cardiac fibroblasts (CFs) and cardiac fibrosis in diabetic hearts. The purpose of this paper is to explore the molecular mechanism of miR‐21 regulating EndMT and cardiac perivascular fibrosis in diabetic cardiomyopathy. In vivo, hyperglycaemia up‐regulated the mRNA level of miR‐21, aggravated cardiac dysfunction and collagen deposition. The condition was recovered by inhibition of miR‐21 following with improving cardiac function and decreasing collagen deposition. miR‐21 inhibition decreased cardiac perivascular fibrosis by suppressing EndMT and up‐regulating SMAD7 whereas activating p‐SMAD2 and p‐SMAD3. In vitro, high glucose (HG) up‐regulated miR‐21 and induced EndMT in ECs, which was decreased by inhibition of miR‐21. A highly conserved binding site of NF‐κB located in miR‐21 5′‐UTR was identified. In ECs, SMAD7 is directly regulated by miR‐21. In conclusion, the pathway of NF‐κB/miR‐21/SMAD7 regulated the process of EndMT in T1DM, in diabetic cardiomyopathy, which may be regarded as a potential clinical therapeutic target for cardiac perivascular fibrosis.

There is an inverse linear correlation between fibrous cap thickness and plasma levels of inflammatory markers. The plasma hs-CRP concentration is the strongest independent predictor of TCFA.

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The largest area of planted forest in the world has been established in China through implementation of key forestry projects in recent years. These projects have played an important role in sequestering CO 2 from the atmosphere, which is considered to be a potential mitigation strategy for the effects of global climate change. However, carbon sequestration in soil (soil organic carbon, SOC) after afforestation or reforestation is not well understood, particularly for specific key forestry projects. In this study, the SOC change in the top 20 cm of soil for each type of restoration implemented under China's Grain for Green Project (GGP) was quantified by a meta-analysis of data from published literature and direct field measurements. Soil carbon sequestration due to the GGP during 1999-2012 was estimated using data on the annual restoration area at provincial level and functions that relate SOC stock change to controlling factors (e.g., plantation age, forest zone, and type of forestation). Soil carbon sequestration of the GGP was estimated to be 156±108 Tg C (95% confidence interval) for current restoration areas prior to 2013, with a mean accumulation rate of 12±8 Tg C yr À1. The soil carbon sequestration potential of existing plantation zones is predicted to increase from 156±108 Tg C in 2013 to 383±188 Tg C in 2050 under the assumption that all plantation areas are well preserved. Plantations in northwestern, southern, and southwestern zones contributed nearly 80% of total soil carbon sequestration, while soil C sequestration in northeastern China was much more variable. Improved data sources, measurements of SOC in the organic layer, greater sampling depth, and better distribution of sampling sites among GGP regions will reduce the uncertainty of the estimates made by this study.

Afforestation, the conversion of non-forested land into forest, is widespread in China. However, the dynamics of soil organic carbon (SOC) after afforestation are not well understood, especially in plateau climate zones. For a total of 48 shrub- and/or tree-dominated afforestation sites on the Qinghai Plateau, Northwestern China, post-afforestation changes in SOC, total nitrogen (TN), the carbon-to-nitrogen ratio (C/N) and soil bulk density (BD) were investigated to a soil depth of 60 cm using the paired-plots method. SOC and TN accumulated at rates of 138.2 g C m-2 yr-1 and 4.6 g N m-2 yr-1, respectively, in shrub-dominated afforestation sites and at rates of 113.3 g C m-2 yr--1 and 6.7 g N m-2yr-1, respectively, in tree-dominated afforestation sites. Soil BD was slightly reduced in all layers in the shrub-dominated afforestation plots, and significantly reduced in soil layers from 0–40cm in the tree-dominated afforestation plots. The C/N ratio was higher in afforested sites relative to the reference sites. SOC accumulation was closely related to TN accumulation following afforestation, and the inclusion of N-fixing species in tree-dominated afforestation sites additionally increased the soil accumulation capacity for SOC (p < 0.05). Multiple regression models including the age of an afforestation plot and total number of plant species explained 75% of the variation in relative SOC content change at depth of 0–20 cm, in tree-dominated afforestation sites. We conclude that afforestation on the Qinghai Plateau is associated with great capability of SOC and TN sequestration. This study improves our understanding of the mechanisms underlying SOC and TN accumulation in a plateau climate, and provides evidence on the C sequestration potentials associated with forestry projects in China.