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Exogenous nitrogen addition can alter plant growth and community structure, thereby influencing soil carbon and nitrogen storage and ultimately impacting ecosystem services and functions. Previous studies have primarily focused on the effects of biological or abiotic factors on soil carbon and nitrogen storage in alpine meadows, but there is a lack of research investigating changes in soil organic carbon and total nitrogen storage as well as their controlling factors under nitrogen addition. Therefore, this study examined soil organic carbon and nitrogen storage across four levels of nitrogen addition. The results showed that nitrogen input significantly increased soil organic carbon and total nitrogen storage. Soil total nitrogen storage was positively influenced by soil total nitrogen, graminoid importance value, soil available nitrogen, and plant belowground biomass, while it was negatively affected by soil bulk density. Soil carbon storage was positively affected by soil organic carbon and soil nitrate nitrogen, and negatively affected by soil bulk density and forb importance value. This study emphasizes the positive effects of nitrogen addition on the accumulation of soil organic carbon and total nitrogen storage and highlights the combined effects of plant traits and soil physicochemical properties on soil total nitrogen storage. [ABSTRACT FROM AUTHOR]

Intercropped systems are regarded as a promising strategy for generating multiple benefits to the ecosystems in the rubber-plantation zone. However, knowledge about the impacts of intercropped systems with rubber on carbon and nitrogen storage in soils and their affecting factors is limited. In this study, three rubber-based intercropped systems, including rubber intercropped with Theobroma cacao, Coffea liberica, and Camellia sinensis, as well as rubber monoculture, were selected in Xishuangbanna, a typical rubber plantation zone in China. We collected soil samples from 0–10, 10–20, and 20–40 cm depths to analyze soil bulk density (BD), soil organic carbon (SOC), soil total nitrogen (TN), pH, the ratio of carbon and nitrogen (C/N), dissolved organic carbon (DOC), and dissolved organic nitrogen (DON). The results showed that rubber trees intercropped with C. liberica significantly increased the SOC and TN stocks of the 0–40 cm soil layer by 19.9% and 13.6%, respectively, compared to rubber monoculture. Soil properties usually had strong relationships with SOC and TN stocks. Our study demonstrated that rubber with the C. liberica intercropped system had greater potential for C and N sequestration in this tropical region. [ABSTRACT FROM AUTHOR]

Forest ecosystems contain a substantial terrestrial reservoir of soil organic carbon (SOC). Here, a "Detritus Input and Removal Treatments" experiment was conducted to explore the effects of litter and roots on soil labile, persistent, and total organic C (TOC) pools in the coniferous, broad-leaved, and coniferous-broad-leaved mixed forests (CF, BF, and CBF, respectively) in the subtropical and warm temperate transition zone in Henan province, eastern China. After 2–3 years of detritus manipulations, neither litter addition nor root exclusion affected soil temperature or moisture. In contrast, litter removal increased soil temperature but decreased soil moisture, regardless of forest types. Litter addition marginally decreased labile OC and TOC contents in the BF but not in the CF and CBF. Litter removal reduced labile OC and TOC contents in the CF and BF and persistent OC contents in the CF only. Root exclusion decreased labile OC contents in the CBF only, but reduced persistent OC and TOC contents in the CF and CBF. Structural equation models suggested that litter but not root manipulation altered SOC pools via changing soil temperature and moisture in the BF, whereas the effects of litter and root manipulation on SOC pools were not related to the changes in soil temperature and moisture in the CF and CBF. Our results suggest that the impact of litter and roots on SOC pools depends on forest types, which may indicate differential responses of SOC storage among forests under global change scenarios. [ABSTRACT FROM AUTHOR]

Microplastic is globally regarded as an important factor impacting biogeochemical cycles, yet our understanding of such influences is limited by the uncertainties of intricate microbial processes. By multiomics analysis, coupled with soil chemodiversity characterization and microbial carbon use efficiency (CUE), we investigated how microbial responses to microplastics impacted soil carbon cycling in a long-term field experiment. We showed that biodegradable microplastics promoted soil organic carbon accrual by an average of 2.47%, while nondegradable microplastics inhibited it by 17.4%, as a consequence of the virus-bacteria coadaptations to the microplastics disturbance. In the relevant functional pathways, nondegradable microplastics significantly (P < 0.05) enhanced the abundance and transcriptional activity related to complex carbohydrate metabolism, whereas biodegradable microplastics significantly (P < 0.05) promoted functions involved in amino acid metabolism and glycolysis. Accordingly, viral lysis enhanced in nondegradable microplastics treatments to introduce more complex organic compounds to soil dissolved organic matters, thus benefiting the oligotrophs with high carbon metabolic capabilities in exploitation competition. In contrast, biodegradable microplastics enriched viral auxiliary metabolic genes of carbon metabolism through "piggyback-the-winner" strategy, conferring to dominant copiotrophs, enhanced substrate utilization capabilities. These virus-host interactions were also demonstrated in the corresponding soil plastisphere, which would alter microbial resource allocation and metabolism via CUE, affecting carbon storage consequently. Overall, our results underscore the importance of viral-host interactions in understanding the microplastics-dependent carbon storage in the soil ecosystem. [ABSTRACT FROM AUTHOR]

The Bulianta Coal Mine is among the problematic coal mining areas in China that is still creating environmental damage, especially associated with soil destruction. Therefore, a scientific investigation was conducted to establish a scientific basis for evaluating the impact of planted forest on soil physical and chemical properties, as well as the ecological benefits following 15 years of vegetation restoration in the area. The soil physicochemical characteristics and distribution of organic carbon storage in the 0–80 cm layer soils of Pinus sylvestris forests, Prunus sibirica forests, and Hippophae rhamnoides forests restored after 5, 10, and 15 years were investigated. The immersion method was used to determine soil porosity and density followed by the determination of soil indicators, and a statistical ANOVA test was applied to examine the differential effects of different vegetation types and restoration years on soil properties. The results clearly demonstrated the following: (1) The recovery of vegetation was achieved after a period of 15 years, with the average bulk density of the 0–80 cm soil layer as follows: P. sylvestris forest (1.513 g·cm−3) > P. sibirica forest (1.272 g·cm−3) > H. rhamnoides forest (1.224 g·cm−3), and the differences among different forest types were statistically significant (p < 0.05). (2) In planted forests, soil nutrients were predominantly concentrated in the 0–20 cm layer, while soil carbon storage exhibited a decline with an increasing soil depth. (3) The soil carbon storage across the three forest types was as follows: P. sylvestris forest (45.42 t·hm−2) > P. sibirica forest (44.56 t·hm−2) > H. rhamnoides forest (41.87 t·hm−2). In summary, during the ecological vegetation restoration process in the Bulianta Core Mine, both P. sylvestris forest and P. sibirica forest exhibit superior carbon storage capacities compared to H. rhamnoides forest, as well as more effective soil improvement outcomes. [ABSTRACT FROM AUTHOR]

Abstract Background Grazing exclusion is a practical approach to restore vegetation in degraded grasslands and enhance soil organic carbon (SOC) sequestration. However, the dynamics and drivers of SOC in grasslands after grazing exclusion have not been well documented, especially in ecosystems with cold climates. Methods Here, we established 14 paired treatments (grazing exclusion vs. free-grazing) along a 600-km transect in the northeastern zone of the Qinghai-Tibet Plateau. After six years, we analyzed vegetation biomass dynamics and measured the soil physicochemical properties and organic C concentration across three depths (0–10, 10–20, and 20–30 cm). Results Grazing exclusion significantly increased above- and belowground biomass (139.85% and 43.30%, respectively), pH (1.38%), total phosphorus (3.29%), nitrate nitrogen (18.03%), and ammonium nitrogen (17.81%), but significantly decreased soil bulk density (2.43%) and clay content (10.49%), particularly in 0–30 cm. Specifically, SOC concentrations positively responded to grazing exclusion (0–10 cm) in 9 of the 14 sites evaluated. The effects of grazing exclusion on SOC concentrations were significantly higher in areas with a mean annual temperature (MAT) below 0 °C compared to those in sites with a high MAT (> 0 °C). The SOC concentrations significantly correlated with the mean annual precipitation (MAP) in both treatments, but these correlations diminished with increasing soil depth. Ridge regression analysis showed that soil chemical properties (e.g., total nitrogen and phosphorus) positively influenced SOC accumulation, while MAT negatively influenced it after grazing exclusion. Path analysis further revealed that MAT indirectly regulated SOC dynamics via soil chemical properties. Conclusions Our study highlights that grazing exclusion results in an asynchronous SOC and plant biomass accumulation and may be more beneficial for SOC sequestration in Qinghai-Tibet Plateau grasslands with lower temperatures. Also, humid climates promote SOC concentration in alpine grasslands. These results could help develop management practices and policies that promote sustainable grassland management.

Background: Grazing exclusion is a practical approach to restore vegetation in degraded grasslands and enhance soil organic carbon (SOC) sequestration. However, the dynamics and drivers of SOC in grasslands after grazing exclusion have not been well documented, especially in ecosystems with cold climates. Methods: Here, we established 14 paired treatments (grazing exclusion vs. free-grazing) along a 600-km transect in the northeastern zone of the Qinghai-Tibet Plateau. After six years, we analyzed vegetation biomass dynamics and measured the soil physicochemical properties and organic C concentration across three depths (0–10, 10–20, and 20–30 cm). Results: Grazing exclusion significantly increased above- and belowground biomass (139.85% and 43.30%, respectively), pH (1.38%), total phosphorus (3.29%), nitrate nitrogen (18.03%), and ammonium nitrogen (17.81%), but significantly decreased soil bulk density (2.43%) and clay content (10.49%), particularly in 0–30 cm. Specifically, SOC concentrations positively responded to grazing exclusion (0–10 cm) in 9 of the 14 sites evaluated. The effects of grazing exclusion on SOC concentrations were significantly higher in areas with a mean annual temperature (MAT) below 0 °C compared to those in sites with a high MAT (> 0 °C). The SOC concentrations significantly correlated with the mean annual precipitation (MAP) in both treatments, but these correlations diminished with increasing soil depth. Ridge regression analysis showed that soil chemical properties (e.g., total nitrogen and phosphorus) positively influenced SOC accumulation, while MAT negatively influenced it after grazing exclusion. Path analysis further revealed that MAT indirectly regulated SOC dynamics via soil chemical properties. Conclusions: Our study highlights that grazing exclusion results in an asynchronous SOC and plant biomass accumulation and may be more beneficial for SOC sequestration in Qinghai-Tibet Plateau grasslands with lower temperatures. Also, humid climates promote SOC concentration in alpine grasslands. These results could help develop management practices and policies that promote sustainable grassland management. [ABSTRACT FROM AUTHOR]

Forests play a crucial role in global carbon cycling by absorbing and storing significant amounts of atmospheric carbon dioxide. Although boreal forests contribute to approximately 45% of the total forest carbon sink, tree growth and soil carbon sequestration are constrained by nutrient availability. Here, we examine if long‐term nutrient input enhances tree productivity and whether this leads to carbon storage or whether stimulated microbial decomposition of organic matter limits soil carbon accumulation. Over six decades, nitrogen, phosphorus, and calcium were supplied to a Pinus sylvestris‐dominated boreal forest. We found that nitrogen fertilization alone or together with calcium and/or phosphorus increased tree biomass production by 50% and soil carbon sequestration by 65% compared to unfertilized plots. However, the nonlinear relationship observed between tree productivity and soil carbon stock across treatments suggests microbial regulation. When phosphorus was co‐applied with nitrogen, it acidified the soil, increased fungal biomass, altered microbial community composition, and enhanced biopolymer degradation capabilities. While no evidence of competition between ectomycorrhizal and saprotrophic fungi has been observed, key functional groups with the potential to reduce carbon stocks were identified. In contrast, when nitrogen was added without phosphorus, it increased soil carbon sequestration because microbial activity was likely limited by phosphorus availability. In conclusion, the addition of nitrogen to boreal forests may contribute to global warming mitigation, but this effect is context dependent. [ABSTRACT FROM AUTHOR]

Legume-grass mixtures are often used to increase forage yield and soil fertility in managed grasslands, but it remains unclear whether these benefits could be further improved by utilizing optimal legume-grass seeding ratios and phosphorus (P) fertilization. Here, we conducted a 5-year field experiment across 3 sites to investigate the effects of legume-grass seeding ratio and P fertilization on forage yield and soil quality. This experiment included mixtures comprised of two legume species and two grass species at five legume-grass ratios (3:7, 4:6, 5:5, 6:4, and 7:3), and monoculture of each species. P fertilizer was applied at the rate of 0, 9, 18, or 27 kg P ha-1 year-1. Plant diversity effects, e.g., complementarity and selection effects, were assessed by comparing yield of mixtures with monocultures. Our results show that a legume-grass mixture with a seeding ratio of 3:7 under moderate P fertilization resulted in the highest forage yield among all monocultures and mixtures, for each of the three sites, with persistent and consistent transgressive overyielding. Notably, greater soil organic matter, total nitrogen, enzymatic activity, and microbial biomass were observed with the legume-grass ratio of 3:7, compared to monocultures or other seeding ratios. Structural equation modeling indicated that the legume-grass ratio of 3:7 achieved highest yield through directly improving complementarity effect, and indirectly promoting selection effects because of increased fungal biomass. P fertilization directly enhanced soil nutrient and enzymatic activities, and further improved complementarity effect, resulting in high forage yield and soil quality. These results indicate that forage diversification practices with low legume-grass seeding ratios and moderate P fertilization can simultaneously benefit forage production and soil quality in managed grasslands. Overall, our study suggests that low legume seeding proportion in legume-grass mixtures combined with moderate nutrient management is a useful strategy for sustainable and highly productive managed grasslands. [ABSTRACT FROM AUTHOR]

Tree‐mycorrhizal associations are associated with patterns in nitrogen (N) availability and soil organic matter storage; however, we still lack a mechanistic understanding of what tree and fungal traits drive these patterns and how they will respond to global changes in soil N availability. To address this knowledge gap, we investigated how arbuscular mycorrhizal (AM)‐ and ectomycorrhizal (EcM)‐associated seedlings alter rhizodeposition in response to increased seedling inorganic N acquisition. We grew four species each of EcM and AM seedlings from forests of the eastern United States in a continuously 13C‐labeled atmosphere within an environmentally controlled chamber and subjected to three levels of 15N‐labeled fertilizer. We traced seedling 15N uptake from, and 13C‐labeled inputs (net rhizodeposition) into, root‐excluded or ‐included soil over a 5‐month growing season. N uptake by seedlings was positively related to rhizodeposition for EcM‐ but not AM‐associated seedlings in root‐included soils. Despite this contrast in rhizodeposition, there was no difference in soil C storage between mycorrhizal types over the course of the experiment. Instead root‐inclusive soils lost C, while root‐exclusive soils gained C. Our findings suggest that mycorrhizal associations mediate tree belowground C investment in response to inorganic N availability, but these differences do not affect C storage. Continued soil warming and N deposition under global change will increase soil inorganic N availability and our seedling results indicate this could lead to greater belowground C investment by EcM‐associated trees. This potential for less efficient N uptake by EcM‐trees could contribute to AM‐tree success and a shift toward more AM‐dominated temperate forests. [ABSTRACT FROM AUTHOR]

The strategic use of ruminant grazing in perennial cropland is steadily increasing throughout Mediterranean perennial agroecosystems. Integrated sheep-vineyard (ISV) management, where small ruminant livestock graze on understory vegetation, is viewed by some practitioners as a feasible transition opportunity to facilitate less petrochemically intensive vineyard understory management. However, our knowledge of soil carbon dynamics associated with grazing in perennial integrated crop-livestock (ICL) agroecosystems is notably limited, especially within Mediterranean climate contexts. Here, we use a series of on-farm paired surveys to assess soil ecosystem habitat and resource conditions related to SOC flux and storage in vineyards utilizing sheep-integration (ISV) and conventional understory management techniques (CONV). Our results show that long-term grazing increased the quantity of active, labile, and soluble carbon (C) within ISV soils, with much higher quantities of microbial biomass carbon (MBC). Vineyard soils with sheep grazing also showed increases in phospholipid fatty acid (PLFA) biomarkers, particularly amongst core functional groups related to decomposition. Soil microbial communities under ISV had higher C mineralization rates as well as higher carbon use-efficiency, as indicated by less CO2-C respired relative to the size of the MBC pool. Whereas inorganic soil nitrogen (N) and phosphorous (P) were also higher under ISV, microbial communities showed distinct metabolic investment strategies related to nutrient acquisition, with lower P-cycling enzyme activity and higher N-cycling enzyme activity. Additionally, ISV resulted in an increase in subsoil SOC storage, including higher quantities of physicochemical stabilization in the mineral-associated organic carbon (MAOC) pool of the deepest measured subsoil layer (30–45 cm). We observed no differences in soil structure indicators between treatments nor differences in the carbon fractions associated with four distinct aggregate size categories. We propose a framework to explain observed shifts in SOC dynamics of perennial ICL systems that include i) deposition of C and nutrient inputs with higher lability and solubility; ii) ruminant-induced decoupling of C from N and P, resulting in increased nutrient bioavailability; and iii) altered soil microbial metabolic strategies with more efficient biomass accumulation. These findings show strong potential of strategically applied ICL grazing to enhance soil functioning and increase SOC storage in Mediterranean perennial agroecosystems.

Purpose: Road traffic has long been recognized as a considerable source of ecological disturbance, compromising the integrity of natural ecosystems from their pristine baseline state. Pollutant deposition from vehicular emissions significantly contributes to environmental contamination, while associated human activities exacerbate ecosystem disruptions. In designated conservation zones, including nature reserves, land-use practices such as pastoralism and agriculture are subject to regulation. Nevertheless, the influence of road traffic on ecosystem structure and processes, particularly concerning carbon (C) sequestration and its spatial heterogeneity, warrants further research. This consideration is critically relevant in the understanding the intricate C fractions and their dynamic interplay with environmental factors. Materials and methods: In this study, we meticulously selected four distinct locations along a principal roadway within a national reserve. For each site, experimental measuring 2 m * 2 m were established at intervals of 2 m, 10 m, 20 m, 30 m, 40 m, and 50 m from the road's edge. Observational data were accrued during the peak of the vegetative growth seasons in August of both 2020 and 2021. Within each plot, soil and cut-ring samples were procured for comprehensive analysis of soil carbon fractions (Total Carbon, TC, g/kg; Carbon Density, g/m2; Readily Oxidizable Carbon, ROC, g/kg; Dissolved Organic Carbon, DOC, mg/kg; Microbial Biomass Carbon, MBC, mg/kg; Cumulative Mineralization Carbon, CMC, mg(CO2-C)*(kg*soil)−1; Soil Inorganic Carbon, SIC, g/kg), chemical properties (pH; Electrical Conductivity, EC, us/cm; Soil Organic Matter, SOM), and physical properties (Soil Water, SW, %; Bulk Density, BD, g/cm3; area conditions). Vegetation metrics, including above-ground biomass (AGB) and below-ground biomass (BGB), species composition, height, and coverage, were meticulously documented. The four sites were replicated, culminating in 24 uniformly oriented plots to mitigate wind influence. Results: Our analysis revealed that C stock, as determined by TC and C density increased with distance from the road edge, reaching a peak at approximately 30 m (TC: 19.43 g/kg, C density: 39.26 g/m2, SOM: 27.57 g/kg), followed by a subsequent decline. At the 30 m distance, there was a 60.6 %, 41.2 %, and 38.7 % enhancement in TC, C density, and SOM, respectively, compared to the 2 m distance, and a 23.9 %, 25.9 %, and 19.8 % increase relative to the 50 m distance. Levels of DOC, MBC, and CMC exhibited an upward trend from the road edge to 50 m, suggesting more favorable microbiological conditions in less disturbed locales. SEM demonstrated that SIC is directly influenced by BGB (β = −0.31), pH (β = 0.46), and labile C components (β = 0.56), culminating in a reduction of total C storage (total effect, β = −0.28). The dynamic changes of soil C stocks were primarily explained directly by soil labile C (β = 0.475, p < 0.001), and indirectly by vegetation biomass (β = 0.460) and pH (β = −0.570), and were closely correlated with ROC (0.54, the highest eigenvalue among Labile_C). Conclusion: The findings suggest that the buffering effect of the roadside in these nature reserves up to a distance of 30 m has an signficant impact on C stock, and that C losses attributable to biochemical processes and laible soil C fractions may contribute to diminished C levels in less disturbed zones 50 m away from the road. Our findings also substantiate the moderate disturbance hypothesis, particularly in the milieu of road traffic within the Hulunbuir Nature Reserve, Mongolia. A moderate distance from roadways enhances soil C storage compared to areas near the road or undisturbed natural landscapes.

In the move to decarbonise energy supplies to meet Net Zero targets, ground-mounted solar farms have proliferated around the world, with uncertain implications for hosting ecosystems. We provide some of the first evidence on the effects of ground-mounted solar panels on plant and soil properties in temperate agricultural systems. We sampled 32 solar farms in England and Wales in summer 2021. Plant cover and aboveground biomass, as well as soil nutrients and physiochemical properties, were quantified on land underneath solar panels, in the gaps between rows of solar arrays, and in control land (pasture) adjacent to three solar farms. Plant cover and aboveground biomass were significantly lower under solar panels than in the gaps between solar arrays and in pastures. Soil compaction was 14.4% and 15.5% higher underneath solar panels than in gaps and pastures, respectively. Soil organic carbon was 9% lower under solar panels than in gaps, while particulate organic matter was 29.1% and 23.6% lower under solar panels than in gaps and pastures, respectively. Soil mineral nitrogen was 30.5% higher under solar panels than in gaps, while soil (plant-available) phosphorus was approximately 60% higher in solar farm soils than in pasture soils. Reductions in solar radiation and changes to microclimate caused by solar panels may be driving lower plant productivity and growth, with consequences for nutrient cycling and soil properties. However, impacts must be considered in light of the previous land use and the total land area under solar panels, in the gaps between solar arrays, and around the margins of the solar farm. Our findings can inform solar farm design and management options (e.g. increase the proportion of land unaffected by solar panels, enhance plant cover under solar panels) to ensure the long-term provision of ecosystem services (e.g. soil carbon storage) within this fast-growing land use.

Forest thinning is a widely used silvicultural method in forest management and has complex effects on carbon sequestration in different types of forest ecosystems. The present study examined the short-term effects of different thinning intensities on carbon storage in an 11-year-old mixed broadleaved plantation. The results partially supported that different thinning intensities have varying impacts on carbon storage in different parts of forest ecosystems. The main results were as follows: (1) The effect of thinning on promoting the growth of fast-growing tree species (Michelia macclurei Dandy and Schima superba Gardn. et Champ.) was earlier than that of slow-growing tree species (Castanopsis hystrix Miq.). (2) A greater thinning intensity conferred greater effects on promoting the tree biomass carbon growth, litter carbon storage, and understory plant diversity, in the order of 41%~50% > 31%~40% > 20%~30%, but these values were lower than those for the unthinned plots. (3) The soil carbon storage declined most in the 41%~50% thinned plots, due to the reduced carbon storage in the humus layer. (4) The 20%~30% thinning intensity promoted carbon sequestration in the short term in the mixed broadleaved plantation. The results suggested that a lower thinning intensity promoted carbon sequestration in the short term, a greater thinning intensity reduced carbon storage at first, but the negative effect on carbon storage exhibited trade-offs later by the growth of tree and understory plant biomass carbon and the accumulation of litter layer carbon. [ABSTRACT FROM AUTHOR]

To assess the effects of reforestation on ecosystem carbon storage, a long-term Forest Restoration Experimental Project (FREP) was established in 1991 on southern degraded red soil in Taihe County, Jiangxi Province, China. In this study, we selected five types of plantations: Schima superba plantation (SS), Liquidambar formosana plantation (LF), Pinus massoniana plantation (PM), Pinus elliottii plantation (PE), and P. elliottii and broadleaf mixed plantation (MEB). The unforested land was used as an experimental control check (CK). We aimed to assess the changes in carbon storage in plantations and the factors affecting them. Thirty years after reforestation, the ecosystem carbon storage of the five types of plantations was significantly higher than that of the control site, and there were also significant differences in the ecosystem carbon storage between the different plantation types (p < 0.05). The ecosystem carbon storage of SS, MEB, LF, PM, and PE were 211.71 Mg ha−1, 199.02 Mg ha−1, 160.96 Mg ha−1, 155.01 Mg ha−1, and 142.88 Mg ha−1, respectively. Compared to the CK, these values were increased by 436.8%, 404.6%, 308.1%, 293.1%, and 262.3%, respectively. The ecosystem carbon storage was significantly positively correlated with soil porosity, total nitrogen (TN), and stand density, and was significantly negatively correlated with pH, Pielou's evenness index (PEI), and the Shannon–Weiner diversity index (SWDI). The soil water content (SWC), bulk density (BD), SWDI, and stand density can be used as indicators of the impact of reforestation plantings on ecosystem carbon storage. The research results has shown that reforestation plantings significantly increase ecosystem carbon storage, and that afforestation should be encouraged on degraded land. [ABSTRACT FROM AUTHOR]

Although desert ecosystems are commonly considered to have low carbon storage owing to their sparse vegetation and limited carbon sequestration capacity, they comprise 13.5% of China's terrestrial ecosystems and cover approximately 35% of the Earth's land surface, so they still possess significant carbon storage. The carbon storage of desert ecosystems in China was estimated using MODIS-NDVI data in combination with ground survey, soil census, and literature statistical data. The results indicated that the carbon storage of desert ecosystems in China was 7.063 Pg in 2020. One-meter soil carbon storage accounted for the largest proportion (89.514%), approximately 6.322 Pg, followed by vegetation carbon at 0.741 Pg, and biological soil crust carbon at 0.002 Pg. The carbon density of desert ecosystems was 33.895 Mg.ha−1, with soil carbon density, vegetation carbon density, and biological soil crust carbon density at 30.330, 3.554, and 0.011 Mg.ha−1, respectively. This research provides important evidence for the correct understanding of the carbon storage of desert ecosystems in China.

Agriculture soils play a crucial role in carbon storage and food security. However, uncertainty remains about soil carbon stocks due to spatial variability. This study estimated soil carbon stocks in agricultural land and examined the impact of land use and soil properties on soil organic carbon in Ratchaburi Province, Thailand. Soil samples were collected at three depths (0-10, 10-20, and 20-30 cm) within five different land use types: cassava, coconut, paddy fields, pineapple, and sugarcane. The results revealed that soil organic carbon decreased with increasing depth. Significant differences in soil carbon and soil properties were observed among land uses. The carbon stocks at 0-30 cm depth were as follows: coconut (35.87 mg C/ha), paddy fields (31.17 mg C/ha), sugarcane (28.02 mg C/ha), pineapple (21.79 mg C/ha), and cassava (16.12 mg C/ha). The carbon stocks were significantly correlated with sand, density, clay, silt, and pH. This study highlights the impact of land use types on carbon stocks in agricultural soils and emphasizes the role of soil properties, particularly soil texture, in influencing carbon storage variability. Furthermore, the study highlights the carbon storage potential in agricultural areas, which could guide the formulation of policies to utilize agricultural land to offset CO2 emissions from other sectors.

The hilly region of the Loess Plateau has lush vegetation and high carbon sequestration potential. However, previous studies have not focused on differences in carbon storage of different forest types and their causes. This study aimed to explore the carbon storage of forest and identify the main influencing factors of carbon storage to provide basis for improving the carbon fixation capacity of planted forest in the region. Broad-leaved, coniferous, and mixed forests at different altitudes were selected from the Ziwuling Mountains in the Loess hilly region. The carbon storage as well as physical and chemical characteristics of the vegetation and soil samples from different soil layers were measured. The vegetation factor, terrain factor, and soil factor of the sample plot were evaluated by Mantel test and redundancy analysis (RDA). The carbon storage of the mixed forest (138.87 MgC hm−2) showed the highest carbon storage compared to broad-leaved forest (131.97 MgC hm−2) and coniferous forest (113.62 MgC hm−2) in the loess hilly region. The carbon storage of different components followed the order of soil carbon storage, vegetation carbon storage, and litter carbon storage. The soil organic carbon content and forest type had the highest explanations for total carbon storage, accounting for 57 and 26.9% of the variance, respectively. This indicates that forest type is an important factor affecting carbon storage, and selecting mixed forests can achieve better results when creating and transforming carbon sink forests.

Rice paddy soils have high organic carbon (OC) storage potential, but predicting OC stocks in these soils is difficult due to the complex OC stabilization mechanisms under fluctuating redox conditions. Especially in temperate climates, these mechanisms remain understudied and comparisons to OC stocks under natural vegetation are scarce. Semi-natural forests could have similar or higher OC inputs than rice paddies, but in the latter mineralization under anoxic conditions and interactions between OC and redox-sensitive minerals (in particular Fe oxyhydroxides, hereafter referred to as Fe oxides) could promote OC stabilization. Moreover, management-induced soil redox cycling in rice paddies can interact with pre-existing pedogenetic differences of soils having different degrees of evolution. To disentangle these drivers of soil OC stocks, we focused on a soil age gradient in Northern Italy with a long (30 + years) history of rice cultivation and remnant semi-natural forests. Irrespective of soil age, soils under semi-natural forest and paddy land-use showed comparable OC stocks. While, in topsoil, stocks of crystalline Fe and short-ranged Fe and Al oxides did not differ between land-uses, under paddy management more OC was found in the mineral-associated fraction. This hints to a stronger redox-driven OC stabilization in the paddy topsoil compared to semi-natural forest soils that might compensate for the presumed lower OC inputs under rice cropping. Despite the higher clay contents over the whole profile and more crystalline pedogenetic Fe stocks in the topsoil in older soils, OC stocks were higher in the younger soils, in particular in the 50–70 cm layer, where short-range ordered pedogenetic oxides were also more abundant. These patterns might be explained by differences in hydrological flows responsible for the translocation of Fe and dissolved OC to the subsoil, preferentially in the younger, coarse-textured soils. Taken together, these results indicate the importance of the complex interplay between redox-cycling affected by paddy-management and soil-age related hydrological properties.

Ecosystem services, such as crop provision, carbon storage, water retention, and nutrient retention, are crucial for sustainable agriculture and local participation. Assessing and mapping these services is crucial for promoting sustainable agriculture and ensuring the active involvement of local communities. However, accurately estimating the values of agricultural ecosystem services is challenging due to the lack of accurate data and an effective economic decision-making system. To address these issues, this study combines field data and modeling approaches to quantify the physical and monetary values of cropland ecosystem services in Yunlin County, Taiwan. The results indicated that the service of crop provision (rice) ranges from 7.96 to 9.70 tonnes ha−1 yr−1, valued at approximately US$7,710 to US$10,650 ha−1 yr−1. The service of soil carbon storage exhibits a carbon stock ranging from 38.2 to 51.9 tonnes of carbon ha−1 yr−1, valued at approximately US$13,150 to US$17,890 ha−1 yr−1. Water retention services retain around 5,380 m3 ha−1 yr−1, valued at approximately US$5,530 ha−1 yr−1. Nutrient retention services retain 1.65 kg ha−1 yr−1 of phosphorus and 30.5 kg ha−1 yr−1 of nitrogen per year, valued at approximately US$60 ha−1 yr−1. We also found that employing the field data approach unveils a higher total ecosystem service value of US$34,105 per hectare per year, which is 28.5 % greater than the value derived from the modeling approach. The results provide insights into enhancing local participation in sustainable soil and agricultural resource management. The quantification of physical and monetary values of ecosystem services can support informed decision-making and promote local participation in sustainable soil and agricultural resource management.

The urgent need to mitigate greenhouse gas (GHG) emissions has prompted the exploration of various strategies, including the adaptation of carbon farming practices, to achieve sustainability in agricultural systems. In this research, we assess the viability of carbon farming practices for organic vegetable growing in Europe. The study explores the potential benefits of these practices, including GHG emissions' mitigation and improved soil health, biodiversity, and ecosystem services, while also acknowledging the need for further research to optimize implementation strategies and foster widespread adoption. However, the suitability and effectiveness of carbon farming practices in organic vegetable production systems remain uncertain. The analysis considers the measurement and estimation methods employed to assess changes in soil carbon stocks and the potential environmental and economic implications for farmers. Despite a substantial body of data demonstrating the sustainable attributes of carbon farming and its multifaceted advantages, a degree of hesitancy persists. Considering this, we propose undertaking a concise strengths, weaknesses, opportunities, and threats (SWOT) analysis to evaluate multiple aspects of carbon farming. The findings reveal that carbon farming practices can be viable and advantageous in organic vegetable production. Carbon farming practices, such as cover cropping, reduced tillage, compost application, and agroforestry, can significantly enhance the sustainability of organic farming systems. Implementing these practices can mitigate greenhouse gas emissions, improve soil health and fertility, and promote biodiversity conservation. Farmer education and support, policy measures, and continued research are crucial for maximizing the potential of these practices for a sustainable future. These practices also contribute to developing climate-friendly agricultural systems, promoting environmental resilience, and reducing the ecological footprint of organic vegetable production. However, further research is needed to optimize implementation strategies, address site-specific challenges, and foster widespread adoption of carbon farming practices in organic vegetable production. [ABSTRACT FROM AUTHOR]

Agriculture soils play a crucial role in carbon storage and food security. However, uncertainty remains about soil carbon stocks due to spatial variability. This study estimated soil carbon stocks in agricultural land and examined the impact of land use and soil properties on soil organic carbon in Ratchaburi Province, Thailand. Soil samples were collected at three depths (0-10, 10-20, and 20-30 cm) within five different land use types: cassava, coconut, paddy fields, pineapple, and sugarcane. The results revealed that soil organic carbon decreased with increasing depth. Significant differences in soil carbon and soil properties were observed among land uses. The carbon stocks at 0-30 cm depth were as follows: coconut (35.87 mg C/ha), paddy fields (31.17 mg C/ha), sugarcane (28.02 mg C/ha), pineapple (21.79 mg C/ha), and cassava (16.12 mg C/ha). The carbon stocks were significantly correlated with sand, density, clay, silt, and pH. This study highlights the impact of land use types on carbon stocks in agricultural soils and emphasizes the role of soil properties, particularly soil texture, in influencing carbon storage variability. Furthermore, the study highlights the carbon storage potential in agricultural areas, which could guide the formulation of policies to utilize agricultural land to offset CO2 emissions from other sectors. [ABSTRACT FROM AUTHOR]

The strategic use of ruminant grazing in perennial cropland is steadily increasing throughout Mediterranean perennial agroecosystems. Integrated sheep-vineyard (ISV) management, where small ruminant livestock graze on understory vegetation, is viewed by some practitioners as a feasible transition opportunity to facilitate less petrochemically intensive vineyard understory management. However, our knowledge of soil carbon dynamics associated with grazing in perennial integrated crop-livestock (ICL) agroecosystems is notably limited, especially within Mediterranean climate contexts. Here, we use a series of on-farm paired surveys to assess soil ecosystem habitat and resource conditions related to SOC flux and storage in vineyards utilizing sheep-integration (ISV) and conventional understory management techniques (CONV). Our results show that long-term grazing increased the quantity of active, labile, and soluble carbon (C) within ISV soils, with much higher quantities of microbial biomass carbon (MBC). Vineyard soils with sheep grazing also showed increases in phospholipid fatty acid (PLFA) biomarkers, particularly amongst core functional groups related to decomposition. Soil microbial communities under ISV had higher C mineralization rates as well as higher carbon use-efficiency, as indicated by less CO2-C respired relative to the size of the MBC pool. Whereas inorganic soil nitrogen (N) and phosphorous (P) were also higher under ISV, microbial communities showed distinct metabolic investment strategies related to nutrient acquisition, with lower P-cycling enzyme activity and higher N-cycling enzyme activity. Additionally, ISV resulted in an increase in subsoil SOC storage, including higher quantities of physicochemical stabilization in the mineral-associated organic carbon (MAOC) pool of the deepest measured subsoil layer (30–45 cm). We observed no differences in soil structure indicators between treatments nor differences in the carbon fractions associated with four distinct aggregate size categories. We propose a framework to explain observed shifts in SOC dynamics of perennial ICL systems that include i) deposition of C and nutrient inputs with higher lability and solubility; ii) ruminant-induced decoupling of C from N and P, resulting in increased nutrient bioavailability; and iii) altered soil microbial metabolic strategies with more efficient biomass accumulation. These findings show strong potential of strategically applied ICL grazing to enhance soil functioning and increase SOC storage in Mediterranean perennial agroecosystems.

The inland and estuary wetlands that characterized by different natural environment perform distinctly in soil carbon (C) sink. It was deemed that estuary wetland has a higher organic C accumulation rate than inland wetland, due to its higher primary production and tidal organics input, thus having higher organic C sink capacity. While from CO2 budge in view, whether does the large organic input from tide restrict CO2 sequestration capacity of estuary wetland has not been discussed comparing with inland wetland. In this study, inland and estuary wetlands were selected to study the potential of CO2 sequestration capacity. It was found that inland wetland had most of soil organic carbon (SOC) derived from plant C, which brought remarkable organic C content and nourished higher microbial biomass, dehydrogenase, and β_glucosidase than estuary wetland. The estuary wetland instead accumulated less SOC, a considerable proportion of which came from tidal waters, therefore supporting lower microbial biomass and enzyme activities than that in inland wetland. However, estuary wetland was evaluated having higher capability in SOC mineralization than inland wetland in consideration of soil respiration (SR) and SR quotient. It was concluded that tidal organic C accelerated the SOC mineralization in estuarine wetland, thus weakening the CO2 sequestration. These results implied the importance of pollution control for reservation CO2 sink function in estuarine wetland. [ABSTRACT FROM AUTHOR]

Soils are important for ecosystem functioning and service provisioning. Soil communities and their functions, in turn, are strongly promoted by plant diversity, and such positive effects strengthen with time. However, plant diversity effects on soil organic matter have mostly been investigated in the topsoil, and there are only very few long‐term studies. Thus, it remains unclear if plant diversity effects strengthen with time and to which depth these effects extend. Here, we repeatedly sampled soil to 1 m depth in a long‐term grassland biodiversity experiment. We investigated how plant diversity impacted soil organic carbon and nitrogen concentrations and stocks and their stable isotopes 13C and 15N, as well as how these effects changed after 5, 10, and 14 years. We found that higher plant diversity increased carbon and nitrogen storage in the topsoil since the establishment of the experiment. Stable isotopes revealed that these increases were associated with new plant‐derived inputs, resulting in less processed and less decomposed soil organic matter. In subsoils, mainly the presence of specific plant functional groups drove organic matter dynamics. For example, the presence of deep‐rooting tall herbs decreased carbon concentrations, most probably through stimulating soil organic matter decomposition. Moreover, plant diversity effects on soil organic matter became stronger in topsoil over time and reached subsoil layers, while the effects of specific plant functional groups in subsoil progressively diminished over time. Our results indicate that after changing the soil system the pathways of organic matter transfer to the subsoil need time to establish. In our grassland system, organic matter storage in subsoils was driven by the redistribution of already stored soil organic matter from the topsoil to deeper soil layers, for example, via bioturbation or dissolved organic matter. Therefore, managing plant diversity may, thus, have significant implications for subsoil carbon storage and other critical ecosystem services. [ABSTRACT FROM AUTHOR]

Predicting how belowground carbon storage reflects changes in aboveground vegetation biomass is an unresolved challenge in most ecosystems. This is especially true for fire-prone savannas, where frequent fires shape the fraction of carbon allocated to root traits for post-fire vegetation recovery. Here I review evidence on how root traits may respond to frequent fires and propose to leverage root traits to infer belowground carbon dynamics in fire-prone savannas. Evidently, we still lack an understanding of trade-offs in root acquisitive vs. conservative traits in response to frequent fires, nor have we determined which root traits are functionally important to mediate belowground carbon dynamics in a frequently burned environment. Focusing research efforts along these topics should improve our understanding of savanna carbon cycling under future changes in fire regimes. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) in shrublands is an important component of global carbon cycling. However, there is a dearth of large-scale systematic observations of SOC stocks at different soil depths, and it remains uncertain whether and how the relative importance of biotic and abiotic variables in regulating SOC stocks changes with soil depth. Here, we quantified large-scale patterns and controlling factors of SOC storage per area (SOCD, kg m−2) for both topsoils (0–30 cm) and subsoils (30–100 cm) by taking full advantage of a consistent stratified random sampling study of one-meter soil profiles across 1211 sites in Chinese shrublands. We found that subsoils stored about 53.30% of total SOCD, falling into the range of previously reported values for terrestrial ecosystems. SoilGrids250m model-derived assessments overestimated SOCD by 13.72 and 65.49% for topsoils and subsoils, respectively. The effects of climate means and seasonality on SOCD were equally strong in both topsoils and subsoils. The predominant effects of edaphic properties on SOCD were more robust in subsoils than in topsoils. Belowground biomass of shrublands was the only significant predictor of topsoil SOCD, but it did not predict subsoil SOCD accurately. These findings have refined our understanding of the pivotal role of shrublands in SOC storage and sequestration potential and could serve as an ecologically valuable baseline for large-scale improvement and validation of depth-dependent SOC dynamics for multilayer SOC modules in Earth Systems Models. [ABSTRACT FROM AUTHOR]

Although desert ecosystems are commonly considered to have low carbon storage owing to their sparse vegetation and limited carbon sequestration capacity, they comprise 13.5% of China's terrestrial ecosystems and cover approximately 35% of the Earth's land surface, so they still possess significant carbon storage. The carbon storage of desert ecosystems in China was estimated using MODIS-NDVI data in combination with ground survey, soil census, and literature statistical data. The results indicated that the carbon storage of desert ecosystems in China was 7.063 Pg in 2020. One-meter soil carbon storage accounted for the largest proportion (89.514%), approximately 6.322 Pg, followed by vegetation carbon at 0.741 Pg, and biological soil crust carbon at 0.002 Pg. The carbon density of desert ecosystems was 33.895 Mg.ha−1, with soil carbon density, vegetation carbon density, and biological soil crust carbon density at 30.330, 3.554, and 0.011 Mg.ha−1, respectively. This research provides important evidence for the correct understanding of the carbon storage of desert ecosystems in China. [ABSTRACT FROM AUTHOR]

Crop-livestock reintegration could reduce the environmental footprint of decoupled crop and livestock production related to biogeochemical cycles. Previous experiments showed that replacing fallow periods in annual crop rotations with grazed cover crops increases total nitrogen (N) and organic carbon (SOC), based on topsoil sampling and stocks compared by equivalent soil depth. Stock comparisons based on topsoil sampling or equivalent soil depth, rather than whole-profile sampling or equivalent soil mass, can erroneously report stock gains that have not occurred. Evidence of crop-livestock integration effects on commercial farms is needed. This study assessed on-farm if winter grass forages and beef cattle grazing in annual crop rotations lead to greater soil total N and SOC to a soil depth of 1 m. We sampled soil at eight paired commercial fields, four integrated crop-livestock (ICL) fields with grazed or ungrazed winter forage (annual ryegrass, oat) in the crop rotation (cereals, grain legumes, industrial crops), and four neighboring fields with winter fallow in the rotation, in volcanic soils in Ñuble Region, central-southern Chile, in fall 2022 and 2023. In each field, 10 soil cores were sampled from a 1 ha plot and separated into four depth layers (0–15 cm, 15–30 cm, 30–60 cm, and 60–100 cm). We quantified soil total N and SOC concentrations and stocks, on an equivalent soil mass basis, and soil texture throughout the soil profile. ICL sites had 10 % higher total N (+0.05 % N) and 8 % higher SOC concentrations (+0.5 % SOC) compared to paired non-ICL sites in the top 15 cm soil layer. The topsoil layer at ICL sites had 11 % higher N (+0.37 Mg N ha−1) and 9 % higher SOC (+3.9 Mg SOC ha−1) stocks, based on an equivalent soil mass. Cumulative stocks below 15 cm to a depth of 1 m were similar between ICL and non-ICL sites. Across the 1 m soil profile, 52 % and 53 % of N and SOC stocks were below 30 cm depth. We provided on-farm evidence suggesting that integrating non-leguminous winter forages and grazing into annual crop rotations can retain N and store SOC in topsoil, with relevance to land managers and decision-makers who seek to build soil fertility and health through biodiversity and reduce N fertilizer use, though further research is recommended. Sampling soil to at least 60 cm depth can help capture management effects on N and SOC and quantify deeper N retention and SOC storage. [Display omitted] • Integrating livestock into cropping systems may increase soil fertility. • On-farm paired survey assessed soil nitrogen and carbon in annual cropped fields with fallow or winter forages and grazing. • We sampled soil to a depth of 1 m and quantified nitrogen and carbon stocks on an equivalent soil mass basis. • Sites with crop-livestock integration had higher topsoil nitrogen and carbon concentrations and stocks. • Crop-livestock integration retains nitrogen and accumulates soil organic carbon in the topsoil. [ABSTRACT FROM AUTHOR]

Regenerating tropical forests are increasingly important for their role in the global carbon cycle. Carbon stocks in above‐ground biomass can recover to old‐growth forest levels within 60–100 years. However, more than half of all carbon in tropical forests is stored below‐ground, and our understanding of carbon storage in soils during tropical forest recovery is limited.Importantly, soil carbon accumulation does not necessarily reflect patterns in above‐ground biomass carbon accrual during secondary forest succession, and factors related to past land use, species composition and soil characteristics may influence soil carbon storage during forest regrowth.Using tree census data and a measure of tree community shade tolerance (species‐specific light response values), we assessed the relationship between soil organic carbon stocks and tree functional groups during secondary succession along a chronosequence of 40‐ to 120‐year‐old naturally regenerating secondary forest and old‐growth tropical forest stands in Panama.While previous studies found no evidence for increasing soil C storage with secondary forest age, we found a strong relationship between tree functional composition and soil carbon stocks at 0–10 cm depth, whereby carbon stocks increased with the relative influence of light‐demanding tree species. Light demanding trees had higher leaf nitrogen but lower leaf density than shade‐tolerant trees, suggesting that rapid decomposition of nutrient‐rich plant material in forests with a higher proportion of light‐demanding species results in greater accumulation of carbon in the surface layer of soils.Synthesis. We propose that soil carbon storage in secondary tropical forests is more strongly linked to tree functional composition than forest age, and that the persistence of long‐lived pioneer trees could enhance soil carbon storage as forests age. Considering shifts in tree functional groups could improve estimates of carbon sequestration potential for climate change mitigation by tropical forest regrowth. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Warming is known to reduce soil carbon (C) stocks by promoting microbial respiration, which is associated with the decomposition of microbial residue carbon (MRC). However, the relative contribution of MRC to soil organic carbon (SOC) across temperature gradients is poorly understood. Here, we investigated the contribution of MRC to SOC along two independent elevation gradients of our model system (i.e., the Tibetan Plateau and Shennongjia Mountain in China). Our results showed that local temperature increases were negatively correlated with MRC and SOC. Further analyses revealed that rising temperature reduced SOC via decreasing MRC, which helps to explain future reductions in SOC under climate warming. Our findings demonstrate that climate warming has the potential to reduce C sequestration by increasing the decomposition of MRC, exacerbating the positive feedback between rising temperature and CO2 efflux. Our study also considered the influence of multiple environmental factors such as soil pH and moisture, which were more important in controlling SOC than microbial traits such as microbial life‐style strategies and metabolic efficiency. Together, our work suggests an important mechanism underlying long‐term soil C sequestration, which has important implications for the microbial‐mediated C process in the face of global climate change. [ABSTRACT FROM AUTHOR]

Mangrove forests are large pools of soil organic carbon (SOC) found across the world, and play a vital role in global carbon (C) cycling. In this study, to investigate the effects of spatial factors on SOC in mangrove forests, soil samples at different depth layers from upper estuary (UE), lower estuary (LE), and tidal inlet (TI) in the Qinglangang mangrove forest in Southern China were collected and the differences in SOC among the layers and geomorphological settings were compared. The mean SOC content showed a pattern of LE (4.63 ± 1.28%) > UE (2.94 ± 0.73%) > TI (1.44 ± 0.33%). SOC content and storage decreased with soil depth in TI, but increased in UE. The total SOC storages (0–80 cm) of sites TU, UE, and LE, were 104.41 ± 16.63, 207.14 ± 44.83, and 228.78 ± 19.37 Mg/ha, respectively. The results suggested that top- and subsoil organic C content and storage were largely dependent on their specific location, which underwent different river-sea interactions and human activities. The SOC of the soil profile varied at different sites, implying that the current C storage of mangrove ecosystems can be accurately estimated by quantifying the C of sediments at sites. [ABSTRACT FROM AUTHOR]

Carbon dioxide removal (CDR) that increases the area of forest cover or bio-energy crops inherently competes for land with crop and livestock systems, compromising food security, or will encroach natural lands, compromising biodiversity. Mass deployment of these terrestrial CDR technologies to reverse climate change therefore cannot be achieved without a substantial intensification of agricultural output, i.e., producing more food on less land. This poses a major challenge, particularly in regions where arable land is little available or severely degraded and where agriculture is crucial to sustain people's livelihoods, such as the Global South. Enhanced silicate weathering, biochar amendment, and soil carbon sequestration are CDR techniques that avoid this competition for land and may even bring about multiple co-benefits for food production. This paper elaborates on the idea to take these latter CDR technologies a step further and use them not only to drawdown CO2 from the atmosphere, but also to rebuild fertile soils (negative erosion) in areas that suffer from pervasive land degradation and have enough water available for agriculture. This way of engineering topsoil could contribute to the fight against malnutrition in areas where crop and livestock production currently is hampered by surface erosion and nutrient depletion, and thereby alleviate pressure on intact ecosystems. The thrust of this perspective is that synergistically applying multiple soil-related CDR strategies could restore previously degraded soil, allowing it to come back into food production (or become more productive), potentially alleviating pressure on intact ecosystems. In addition to removing CO2 from the atmosphere, this practice could thus contribute to reducing poverty and hunger and to protection of biodiversity.

Crop rhizospheres are the foundational support for multiple ecosystem services, ranging from food production to carbon sequestration and soil fertility. Land use intensification is known to impact these fundamental ecosystem services. However, little is known about how root traits regulate the responses of rhizosphere ecosystem services to land use intensification. Here, we conducted a field experiment to explore the responses of rhizosphere ecosystem services to phosphorus (P) fertilization and maize-alfalfa intercropping, and specifically evaluated how root traits drive these responses. Results showed that unfertilized intercropping treatments produced the highest values of rhizosphere ecosystem services, including enhanced plant-soil mutualism, and the greatest abundance of soil decomposers. Unfertilized intercropped alfalfa increased nutrient cycling, soil carbon storage, and soil microbial diversity. Crop-specific root traits such as exudation and morphology are critical in explaining the responses of the rhizosphere. The exudation traits of alfalfa, and morphological traits of maize in unfertilized intercropping treatments were most important for the increases in ecosystem services. Our results highlight the importance of root traits in promoting rhizosphere ecosystem services under land use intensification. Intercropping supported rhizosphere multiservices under the more sustainable low-input system through plant-specific root trait complementarity. This is critical for developing management policies to promote the far-reaching development of agroecosystems. • Unfertilized intercropping supported a larger range of rhizosphere multiservices. • Crops optimized P capture in unfertilized soil through root traits complementarity. • Root traits regulate the response of multiservice to intercropping and fertilization. • Maize increased soil microbial diversity, nutrient cycling by morphological traits. • Alfalfa promoted soil carbon storage and microbial biomass carbon by exudate traits. [ABSTRACT FROM AUTHOR]

• Wetlands topsoil can sequester more C than farmlands and forestlands. • Soil water content was important factor affecting microbial abundance and enzyme activity. • Higher soil water content can increase soil C storage by stimulating C fixing enzyme activity. • Soil C storage were negatively driven by soil bacterial abundance under different land-use. Soil carbon storage plays a crucial role in mitigating the climate warming and is significantly impacted by the land use pattern. To better understand soil carbon stability and the underlying microbial mechanism, based on qPCR, ELISA, and fluorescence techniques, the effects of land use changes on soil microbial abundance, enzyme activity, and soil carbon storage were investigated in the complex ecosystems of cropland, forestland, and wetland along three typical river (Wolvlan river, Bielahong river, Wusuli river) basin in Sanjiang Plain, China. We hypothesised that croplands soil carbon storage is lower than forestlands and wetlands, which is regulated by soil water content, microbe and enzyme activity. Results showed that topsoil TC in wetlands (85.54 mg·g−1) was higher than those in croplands (33.46 mg·g−1) and forestlands (46.13 mg·g−1). Topsoil water content increased 73.90 % and 71.64 % in wetlands than in farmland and forestlands, respectively. Additionally, reclamation diminished topsoil carbon storage. In croplands, soil dissolved organic carbon, microbial biomass carbon, microbial biomass nitrogen, available nitrogen, bacterial abundance, and soil enzymes (i.e., RubisCO, β-glucosidase, cellobiohydrolase, 1,4-N-acetylglucosaminidase and acid phosphatase) activities were substantially lower than those in wetlands. Structural equation modeling showed that soil carbon storage was positively related to soil water content and RubisCO activity but negatively related to soil bacterial abundance. Soil water content had the largest standardised total positive effect coefficient and indirectly influenced soil carbon storage by affecting RubisCO activity. Soil depth had a greater effect on SMC, hydrolase and site had a greater effect on bacteria and fungi abundance. The results highlight that the alteration of carbon fixing enzyme activity by soil water content is a crucial mechanism for soil carbon sequestration in response to land-use change. Management strategies that conserve natural wetlands, increase soil water content and minimize land disturbance would be effective in maintaining soil carbon stocks. [ABSTRACT FROM AUTHOR]

Despite the increasing interest in mangroves as one of the most carbon-rich ecosystems, arid mangroves are still poorly investigated. We aimed to improve the knowledge of biomass and soil carbon sequestration for an arid mangrove forest located at the Azini creek, Sirik, Hormozgan Province (Iran). We investigated the biomass and organic carbon stored in the above and belowground biomass for three different regions selected based on the composition of the principal species: (1) Avicennia marina, (2) mixed forest of A. marina and Rhizophora mucronata, and (3) R. mucronata. Topsoil organic carbon storage to 30 cm depth was also estimated for each analyzed area. Biomass carbon storage, considering both aboveground (AGB) and belowground biomass (BGB), was significantly different between the cover areas. Overall, the mean forest biomass (MFB) was 283.1 ± 89 Mg C ha−1 with a mean C stored in the biomass of 128.9 ± 59 Mg C ha−1. Although pure Rhizophora stand showed the lowest value of above and below tree carbon (AGC + BGC); 17.6 ± 1.9 Mg C ha−1), soil organic carbon stock in sites under Rhizophora spp. was significantly higher than in the site with pure stand of Avicennia spp. Overall, forest soil stored the highest proportion of Sirik mangrove ecosystem organic carbon (59%), with a mean value of 188.3 ± 27 Mg C ha−1. These results will contribute to broaden the knowledge and the dataset available, reducing the uncertainties related to estimates and modeling of carbon pools in arid mangrove ecosystem, which also represent an important climatic threshold of mangrove worldwide distribution. [ABSTRACT FROM AUTHOR]

Carbon cycle depends on the relationship between soil and plant in a rangeland ecosystem and management practices play an important role in carbon sequestration, but direct evidence is generally lacked. This study was carried out to assess the rangeland potentials for carbon storage and its sequestration in southern slopes of central Alborz rangeland, Iran. Exclosure and grazing effects on the rangeland carbon pools in soil and pasture plants were surveyed as two rangeland management practice. The data analysis was revealed that the carbon content on litter in exclosure significantly increased, by 48.5%. The carbon sequestration by aboveground biomass in exclosure was greater than that in grazing plot, on average by 17.5%. The rangeland management practice increased the root - soil carbon content ratio in the exclosure area and the main Carbon sequestration was recorded by the soil profile. This study also showed that the exclosure practice increased the biomass carbon content but there was a significant decrease in the soil carbon storage. From these results it can be concluded that the suitable rangeland management practice must be to graze up to the rangeland carrying capacity. [ABSTRACT FROM AUTHOR]

Summary: Arbuscular mycorrhizal fungi (AMF) are important contributors to both plant and soil health. Twenty‐five years ago, researchers discovered 'glomalin', a soil component potentially produced by AMF, which was unconventionally extracted from soil and bound by a monoclonal antibody raised against Rhizophagus irregularis spores. 'Glomalin' can resist boiling, strong acids and bases, and protease treatment. Researchers proposed that 'glomalin' is a 60 kDa heat shock protein produced by AMF, while others suggested that it is a mixture of soil organic materials that are not unique to AMF. Despite disagreements on the nature of 'glomalin', it has been consistently associated with a long list of plant and soil health benefits, including soil aggregation, soil carbon storage and enhancing growth under abiotic stress. The benefits attributed to 'glomalin' have caused much excitement in the plant and soil health community; however, the mechanism(s) for these benefits have yet to be established. This review provides insights into the current understanding of the identity of 'glomalin', 'glomalin' quantification, and the associated benefits of 'glomalin'. We invite the community to think more critically about how glomalin‐associated benefits are generated. We suggest a series of experiments to test hypotheses regarding the nature of 'glomalin' and associated health benefits. [ABSTRACT FROM AUTHOR]

Forest soils are an important carbon (C) sink and critical component of the global C cycle. Warmer temperatures and increased atmospheric nitrogen (N) deposition are altering the biogeochemistry in forest soils and disrupting the intricate balance between C storage and C respired across the globe. The molecular biogeochemistry of soil organic matter (SOM) with warming, N-addition, and simultaneous warming and N-addition was analyzed in soil samples from the Soil Warming × Nitrogen Addition Study at the Harvard Forest Long-term Ecological Research Site using advanced techniques. The results unequivocally demonstrate that warming and N-addition alter the molecular composition of SOM as individual stressors uniquely and in combination. Warming alone and in combination with N-addition accelerated SOM decomposition while N-addition alone slowed SOM degradation. The two-factor N-addition and warming plots contain SOM more like the warming only plots but exhibited unique changes over time (from 4 to 10 years) that could not be predicted by studying N-addition or warming alone. The specific SOM components and the overall SOM decomposition suggests that N-addition and warming impacts are not additive. N-addition may hinder warming impacts antagonistically over time but not to the extent where advanced SOM decomposition from warming is supplanted. As such, the results from warming alone and N-addition alone are not necessarily additive compared to the observed SOM molecular compositional changes when these treatments are applied simultaneously. Marked evolution in the molecular biogeochemistry of SOM demonstrates the sensitivity of SOM trajectories to multiple interactive global environmental changes and the continued need to study long-term impacts more holistically. [ABSTRACT FROM AUTHOR]

Grazing exclusion is a common management strategy for improving grasslands degraded due to overgrazing. Although previous meta‐analyses proved that grazing exclusion improved soil carbon (C) storage of grasslands in China, we know little about its effect on grassland ecosystems elsewhere and whether litter accumulation induced by grazing exclusion regulates soil C storage. Using meta‐analysis, we integrated 91 publications to examine the effects of grazing exclusion on community litter and soil C storage, accompanied by analysis of the regulating roles of body size of herbivore, climatic conditions, and grazing exclusion duration. We found that grazing exclusion enhanced litter biomass and decomposition rate but did not change litter chemical quality. Generally, grazing exclusion enhanced plant production and soil C storage across grassland worldwide. Exclusion of medium and small herbivores had stronger effects on aboveground litter production and soil C storage than exclusion of large herbivores, and grazing exclusion's enhancement on litter production and soil C storage tended to increase as grazing exclusion proceeded. Notably, grazing exclusion‐induced increase in aboveground litter biomass was attributed to the increase in biomass of graminoids, while root biomass, not aboveground litter biomass, primarily regulated the increase in soil C storage. The stimulating effect of grazing exclusion on soil C storage was enhanced possibly due to enhanced root biomass response along a precipitation gradient. Generally, our study provided new insights that management practice under grazing exclusion should take plant community dynamics, grazing exclusion duration, preceding grazer type, and climate conditions into account simultaneously. [ABSTRACT FROM AUTHOR]

Optimal methods for incorporating soil microbial mechanisms of carbon (C) cycling into Earth system models (ESMs) are still under debate. Specifically, whether soil microbial physiology parameters and residual materials are important to soil organic C (SOC) content is still unclear. Here, we explored the effects of biotic and abiotic factors on SOC content based on a survey of soils from 16 locations along a ~4000 km forest transect in eastern China, spanning a wide range of climate, soil conditions, and microbial communities. We found that SOC was highly correlated with soil microbial biomass C (MBC) and amino sugar (AS) concentration, an index of microbial necromass. Microbial C use efficiency (CUE) was significantly related to the variations in SOC along this national‐scale transect. Furthermore, the effect of climatic and edaphic factors on SOC was mainly via their regulation on microbial physiological properties (CUE and MBC). We also found that regression models on explanation of SOC variations with microbial physiological parameters and AS performed better than the models without them. Our results provide the empirical linkages among climate, microbial characteristics, and SOC content at large scale and confirm the necessity of incorporating microbial biomass and necromass pools in ESMs under global change scenarios. [ABSTRACT FROM AUTHOR]

Soil Carbon Storage has emerged as a feasible strategy for removing carbon dioxide from the atmosphere, raising important questions regarding whether the general public supports the strategy as a means to address climate change. We analyzed data from a national probability survey of 1222 US adults who reported believing in climate change at least “somewhat” to estimate public support for Soil Carbon Storage and how it compares to other leading Carbon Dioxide Removal (CDR) strategies. Overall, a majority of the sample expressed support for Soil Carbon Storage—regardless of whether the strategy involved the use of biochar (a form of charcoal made from organic matter) or not (55% and 62%, respectively)—placing Soil Carbon Storage ahead of Bioenergy plus Carbon Capture and Storage (32%) and Direct Air Capture (25%), and behind only Afforestation and Reforestation (73%), in terms of public support. In addition, perceiving Soil Carbon Storage as “natural” strongly predicted individual-level support, a pattern that held for every CDR strategy featured on the survey. Results demonstrate broad US public support for Soil Carbon Storage as a climate change mitigation strategy at a time when scientists and policymakers are actively considering the political, not just technical, feasibility of different climate solutions. [ABSTRACT FROM AUTHOR]