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In a changing climate, conservation tillage and agronomic biofortification are essential for enhancing crop yield, nutritional security, carbon stocks, and soil quality. Consequently, a field study was conducted in central India to assess the short‐term (4 years) effects of crop establishment techniques (CETs) and agronomic biofortification methods (ABMs) on soil health indicators, grain yield, and quality in the soybean–wheat cropping system. The experiment followed a split‐plot design with two CETs in the main plots (permanent broad bed furrow, PBBF, and conventional tillage, CT) and eight ABMs, each with three replications. The results indicated that PBBF and ABMs (seed inoculation with the microbial strains MDSR 14 + MDSR 34, and soil and foliar application of Zn+Fe) improved soil carbon stock (by 49.6% and 52.4%), available nitrogen, phosphorus, potassium, available Zn (by 30.0%), and Fe (by 21.9%) after the fourth year of the study. Similarly, PBBF and microbial inoculation increased soil enzyme activities (dehydrogenase, acid phosphatase, and β‐glucosidase), substrate‐induced respiration, and microbial biomass carbon content. As a result, a higher soybean equivalent yield (5.59% higher in PBBF and 14.2% higher with foliar spray of Zn+Fe) and seed quality attributes (crude protein yield, grain Zn, and Fe) were observed in PBBF and the foliar spray of Zn and Fe treatments compared to CT and control, respectively. Overall, adopting the short‐term PBBF system, microbial inoculation, and soil and foliar application of Zn and Fe improved rhizosphere biochemical properties, yield, and seed quality in the soybean–wheat system. [ABSTRACT FROM AUTHOR]

Biomass estimation forms the foundation for tackling global climate issues across diverse land use systems (LUSs). A research initiative was undertaken to identify the maximum biomass allocation using an allometric approach, and to assess the carbon stock, CO2 sequestration, and carbon credit across diverse land use systems (LUSs) in the Vindhyan region of Mirzapur, Uttar Pradesh, India. This study aims to address climate change by identifying land‐use strategies that stabilize income and are easily adoptable by farmers. Tropical dry deciduous forest, agriculture, plantation, horticulture and agri‐horticulture LUSs were investigated using three combinations of custard apple (Annona squamosa), guava (Psidium guajava), bael (Aegle marmelos), mustard (Giriraj) (Brassica nigra), mustard (Pitambri) (Brassica juncea), and lentil (Lens culinaris) in an agri‐horticulture system. Seven treatments with varying carbon stocks were identified: tropical dry deciduous forest (T1) LUS (TDDFLUS); wheat based agriculture (T2) LUS (WBALUS); plantation based on teak (Tectona grandis) (T3) LUS (TBPLUS); horticulture based on karonda (Carissa carandas) (T4) LUS (KBHLUS); bael + lentil (Hul‐57) (T5) LUS (BLBLUS); guava + mustard (Giriraj) (T6) LUS (GMBLUS); and custard apple + mustard (Pitambri) (T7) LUS (CAMBLUS). The results indicate that the lowest and the highest bulk densities (ρb) were recorded in TDDFLUS and WBALUS at the depths of 0–20 cm and 20‐40 cm, respectively. The mean value of the soil organic carbon (SOC) stock ranged from 11.24–18.09 t ha−1. The average value of biomass, biomass carbon stock and biomass CO2 sequestration of seven treatments varied from 9.76–88.49 t ha−1, 4.88–44.25 t ha−1, and 17.91–162.39 t ha−1, respectively. The total carbon stock, CO2 sequestration, and carbon credit for the seven treatments varied from 16.57–64.64 t ha−1, 60.82–237.28 t ha−1 and 3040.821–11 863.89US$ ha−1, respectively. The results demonstrated that different LUSs have specific advantages and their application at farm level can encourage sustainability and increase biomass accumulation, leading to carbon sequestration. Agri‐horticulture‐based LUSs can lead to better livelihoods and can also offer numerous advantages such as increased yields of staple food crops and fruits, improved soil health, reduced soil erosion, and significant contributions to the mitigation of anthropogenic warming through CO2 sequestration. [ABSTRACT FROM AUTHOR]

Natural forests are crucial for climate change mitigation and adaptation, but deforestation and degradation challenges highly reduce their value. This study evaluates the potential of natural forest carbon stock and the influence of management interventions on enhancing forest carbon storage capacity. Based on forest area cover, a study was conducted in nine purposely selected forest patches across various forest ecosystems. Data on diameter, height, and environmental variables from various forest management approaches were collected and analyzed with R Ver. 4.1. The findings revealed a substantial difference (p.029) in carbon stock between environmental variables and management interventions. The findings revealed a strong connection between environmental variables and the overall pool of carbon stock within forest patches (p.029). Carbon stocks were highest in the Moist‐montane forest ecosystem (778.25 ton/ha), moderate slope (1019.5 ton/ha), lower elevation (614.50 ton/ha), southwest‐facing (800.1 ton/ha) and area exclosures (993.2 ton/ha). Accordingly, natural forests, particularly unmanaged parts, are sensitive to anthropogenic stresses, decreasing their ability to efficiently store carbon. As a result, the study highlighted the importance of sustainable forest management, particularly area exclosures and participatory forest management, in increasing forest carbon storage potential. [ABSTRACT FROM AUTHOR]

Harvested wood products (HWP) may contribute to climate change mitigation by storing carbon and by replacing energy‐intensive materials and fossil energy, reducing greenhouse gas (GHG) emissions. However, when assessing improved HWP utilisations, interactions between wood use pathways, the carbon stock dynamics, and the resulting effect on the GHG balance are still not well‐understood. This research aims to assess the carbon sequestration effects of alternative wood product utilisations in four European Union (EU) countries. We conducted a material flow analysis of wood uses in France, Finland, Germany, and Spain for 2017 taking into account national production, imports, and exports. Then, we quantified the future dynamics of carbon stock in the HWP through time, assuming the same as in 2017 input and ignoring the forest sink. We then ran six alternative scenarios: two energy‐focused (Energy, Energy+), two material‐focused (Cascading, Material), one with extended half‐life of the wood products (HL) and one as business as usual. For the simulation period (2020–2050), the material scenario leads to the highest mitigation benefits with a cumulative HWP net CO2 removals of −502 Mt CO2 for Germany, −290 Mt CO2 for France, −118 Mt CO2 for Spain, and −116 Mt CO2 for Finland over the 30 years. The Energy+ scenario with an increase in wood usage for bioenergy generates a loss of the HWP pool of 351, 80, 77, and 6 Mt CO2 for the same countries, not accounting for energy substitution effects. Overall, our results suggest that the HWP carbon stock can be increased in the short‐medium term by prioritizing the use of wood for material purposes, while maintaining constant harvest. The HWP mitigation potential differed greatly according to national wood industry characteristics. Hence, tailoring the HWP mitigation strategies to the specific characteristics of the national wood chain would enhance the HWP climate benefits. [ABSTRACT FROM AUTHOR]

Tropical and subtropical forests play a crucial role in global carbon (C) pools, and their responses to warming can significantly impact C‐climate feedback and predictions of future global warming. Despite earth system models projecting reductions in land C storage with warming, the magnitude of this response varies greatly between models, particularly in tropical and subtropical regions. Here, we conducted a field ecosystem‐level warming experiment in a subtropical forest in southern China, by translocating mesocosms (ecosystem composed of soils and plants) across 600 m elevation gradients with temperature gradients of 2.1°C (moderate warming), to explore the response of ecosystem C dynamics of the subtropical forest to continuous 6‐year warming. Compared with the control, the ecosystem C stock decreased by 3.8% under the first year of 2.1°C warming; but increased by 13.4% by the sixth year of 2.1°C warming. The increased ecosystem C stock by the sixth year of warming was mainly attributed to a combination of sustained increased plant C stock due to the maintenance of a high plant growth rate and unchanged soil C stock. The unchanged soil C stock was driven by compensating and offsetting thermal adaptation of soil microorganisms (unresponsive soil respiration and enzyme activity, and more stable microbial community), increased plant C input, and inhibitory C loss (decreased C leaching and inhibited temperature sensitivity of soil respiration) from soil drying. These results suggest that the humid subtropical forest C pool would not necessarily diminish consistently under future long‐term warming. We highlight that differential and asynchronous responses of plant and soil C processes over relatively long‐term periods should be considered when predicting the effects of climate warming on ecosystem C dynamics of subtropical forests. [ABSTRACT FROM AUTHOR]

Floodplain restoration can enhance the capacity for carbon sequestration by facilitating higher water tables, deposition of fine sediment, and increased input and residence time of organic matter. We measured floodplain soil organic carbon stocks in nine stream restoration projects across the western United States and compared them to nearby degraded and reference condition floodplains. Degraded floodplains had the lowest soil mean carbon stocks in the majority of floodplains measured (range 161–894 Mg C/ha), and reference stocks had the highest stocks (range 391–904 Mg C/ha) of those with statistically significant differences between the three categories. Across all sites measured, stream restoration sites, referred to as treatment sites, had stocks (range 203–1028 Mg C/ha) similar to degraded condition floodplains but the largest range. When modeled under degraded conditions, four out of nine of the treatment sites had significantly higher OC stocks than predicted. Climate and geologic variables are most influential in predicting carbon stocks, and floodplains in the interior western USA have the highest carbon stocks. As the demand for carbon sequestration increases due to climate change, ecologically responsible floodplain restoration provides a significant opportunity for carbon storage. However, despite the statistically significant relationships we observed in this dataset, the variations within the data in relation to degraded/treatment/reference categories illustrate the uncertainties in quantifying the effects of restoration on floodplain carbon stocks. [ABSTRACT FROM AUTHOR]

Fifty per cent of European peatlands are in a damaged state. While intact peatlands are natural carbon sinks, degraded sites release important amounts of greenhouse gases into the atmosphere, contributing to global warming. Restoration of the hydrological functionality of peatlands has proved to be an efficient tool to avoid these emissions. In France, Tuffnell & Bignon's ministerial report (2019) emphasized the need for peatlands 'integration into the National Low Carbon Strategy, targeting carbon neutrality by 2050. However, current knowledge regarding French peatlands' distribution and carbon stocks is insufficient and does not allow decision makers and managers to prioritize areas for restoration. The most complete database to date is the 1949 Atlas, an inventory of exploitable peat deposits that was conducted during WWII for peat exploitation as fuel. Until its digitalization, the latter database was archived and never used in a scientific study. It provides detailed information about peatland surfaces, peat thicknesses and carbon contents at that time. We estimated peat carbon stocks from French peatlands to be 111 Mt C in 1949 for 63,290 ha identified as peaty sites, the equivalent of 3% of the organic carbon contained in the upper 30 centimetres of French soils. 34% of this stock was held in Lower Normandy (37.7 Mt C) and 12% in the Picardy's region (13.0 Mt C), in large lowland peatlands. However, not all peatlands were prospected in the 1949 inventory and the characteristics of the prospected peatlands may have changed with anthropic disturbances of the last decades, such as draining or climate change. These first results highlight the need for a recent inventory of French peatlands and carbon stocks based on local data aggregation. Data from the 1949 Atlas could help constituting this new inventory but should be validated before being used to describe the present. [ABSTRACT FROM AUTHOR]

Reducing emissions from deforestation and forest degradation (REDD+) is way key to reduce the emission of greenhouse gases (GHGs) while also protecting vulnerable forest ecosystems. The purpose of this study was to recognize suitable areas for REDD+ Programme projects and calculate the reduction in CO2 emissions through the prevention of forest cover degradation in the Central Hyrcanian forests. For this purpose, the cover changes of the Central Hyrcanian forests were assessed using LANDSAT satellite images. Applying the voluntary carbon standard (VCS) methodology and the calibration period 1984–2014 (30 years), forest cover changes were predicted. The results showed that under the business‐as‐usual scenario, 155,698 ha of Central Hyrcanian forests will be declined by 2044. In general, the REDD+ Programme project implementation will prevent the release of 1,209,231 tCO2e. Based on the social cost of carbon (SCC) approach, the REDD+ Programme project implementation can save 12,092,310 US$. In addition, this approach can be used for the project design document (PDD) of the forest development mechanism. [ABSTRACT FROM AUTHOR]

Excessive growth of invasive weeds in reclaimed coal mine sites are undesirable as they compete for nutrient with the planted species. To overcome this problem, these invasive species may be converted to biochar and used as an amendment during reclamation. Objectives of the present study are to prepare biochar from invasive weeds and apply as amendment in an 8‐year‐old reclaimed mine spoil (RMS) and study the changes in spoil physio‐chemical properties, enzymatic activity, and C‐stock. Biochar was prepared at 450°C and applied at 10 t/ha (BC10) and 20 t/ha (BC20) in field condition. The result showed that biochar ameliorates RMS physio‐chemical properties significantly with respect to moisture content (+27%), available‐N (+3%), exchangeable‐K (+15%), and cation exchange capacity (+35%) in BC20 compared to control. Geometric mean of enzymatic activities index increase in BC10 (8) and BC20 (10.2) compared to control (5.8) indicating improved microbial activities. BC20 had significantly high recalcitrant carbon, which indicates higher C‐sequestration potential by biochar application. Additionally, the total C‐stock increased by 13 and 91% at BC10 and BC20, respectively. CO2 sequestered increased by 13% at BC10 and 91% at BC20 amendment. In‐situ production and surface application of biochar at 20 t/ha will cost 239 USD/ha. The study concluded that invasive weed biochar has the potential to improve the spoil nutritional properties (N & K), increase C‐stock and C‐sequestration potential in coal mine spoil. [ABSTRACT FROM AUTHOR]

Peatlands at high latitudes have accumulated >400 Pg carbon (C) because saturated soil and cold temperatures suppress C decomposition. This substantial amount of C in Arctic and Boreal peatlands is potentially subject to increased decomposition if the water table (WT) decreases due to climate change, including permafrost thaw‐related drying. Here, we optimize a version of the Organizing Carbon and Hydrology In Dynamic Ecosystems model (ORCHIDEE‐PCH4) using site‐specific observations to investigate changes in CO2 and CH4 fluxes as well as C stock responses to an experimentally manipulated decrease of WT at six northern peatlands. The unmanipulated control peatlands, with the WT <20 cm on average (seasonal max up to 45 cm) below the surface, currently act as C sinks in most years (58 ± 34 g C m−2 year−1; including 6 ± 7 g C–CH4 m−2 year−1 emission). We found, however, that lowering the WT by 10 cm reduced the CO2 sink by 13 ± 15 g C m−2 year−1 and decreased CH4 emission by 4 ± 4 g CH4 m−2 year−1, thus accumulating less C over 100 years (0.2 ± 0.2 kg C m−2). Yet, the reduced emission of CH4, which has a larger greenhouse warming potential, resulted in a net decrease in greenhouse gas balance by 310 ± 360 g CO2‐eq m−2 year−1. Peatlands with the initial WT close to the soil surface were more vulnerable to C loss: Non‐permafrost peatlands lost >2 kg C m−2 over 100 years when WT is lowered by 50 cm, while permafrost peatlands temporally switched from C sinks to sources. These results highlight that reductions in C storage capacity in response to drying of northern peatlands are offset in part by reduced CH4 emissions, thus slightly reducing the positive carbon climate feedbacks of peatlands under a warmer and drier future climate scenario. [ABSTRACT FROM AUTHOR]

1. It is increasingly being recognized that tree species diversity has positive effects on forest ecosystem carbon (C) stock. However, at broad spatial scales, this relationship may depend on climate conditions and species mycorrhizal associations. 2. Here, observations from 667 forest plots in subtropical China were used to investigate the effects of species diversity, mean annual precipitation (MAP), mean annual temperature (MAT) and mycorrhizal type (arbuscular or ectomycorrhizal) on the forest C stock and its components (tree C stock, shrub layer C stock, herb layer C stock, litter layer C stock, root C stock and soil C stock). 3. We found positive effect of tree species diversity on total forest C stock. MAP had positive effects on total forest C stock and its components, while MAT had consistently negative effects on total forest C stock and most of its components. Different levels of MAP and MAT did modulate the strength of effect of species diversity on forest C stock and its components. In addition, species diversity, MAT and MAP showed a significant positive relationship with arbuscular mycorrhiza-associated tree C stock but had no or negative relationship with ectomycorrhiza-associated tree C stock. 4. Synthesis. Our results indicate that maintaining high level of species diversity may support the buffering of negative effects resulting from climate warming. Furthermore, under climate warming the specific C stock of AM trees can increase, which can potentially promote forest C stock. Taken together, our study suggests that afforestation policies should consider not only tree species diversity to increase forest C stock but also the effects of different tree mycorrhizal types. [ABSTRACT FROM AUTHOR]

The Brazilian Cerrado, the most biodiverse savanna globally with great importance for water and carbon conservation, faces the impacts of rapid and extensive land conversion, mainly for agricultural uses. The native Cerrado vegetation originally covered an area of 204 Mha however, 43% has been converted to human use. Pastures are the major land use category in Cerrado, covering 57 Mha, 28% of its area. Most of these pastures are underused and present some degree of degradation, representing an opportunity for restoration programs and agriculture expansion without further conversion of natural areas. The restoration of the Cerrado's degraded pastures is a source of recovery of ecosystem services, however, it might involve synergies and trade‐offs between ecosystem services and stakeholders.To evaluate potential trade‐offs, we modelled seven scenarios for prioritization for restoration, focusing on pasture areas on a biome scale. We considered biodiversity, water‐related ecosystem services, potential carbon stock and agriculture aptitude to understand the trade‐offs between each feature and the conflicts with agriculture. We also applied the same prioritization logic for one Cerrado ecoregion to understand the importance of planning on a finer scale.We identified important trade‐offs between the scenarios, especially with agriculture. The agriculture conflict scenario showed that 16 Mha of areas suitable to agriculture have also a high importance for restoration, representing a gain around 70% in ecosystem services and biodiversity. By refining the spatial scale of the prioritization process, we could also identify local conflicts and demands, which indicates the relevance of a local approach, allowing a more representative cover of the Cerrado's heterogeneity to minimize trade‐offs between different demands associated with restoration.Policy implications. The restoration of degraded lands is an international priority to mitigate climate change as well as protect the biodiversity. Our work provides a better understanding of the trade‐offs and conflicts involved in the restoration of the Cerrado, a megadiverse savanna with great importance in agriculture. This understanding is key to implementing public policies that enable large‐scale restoration projects while optimizing biodiversity conservation, ecosystem services provision and minimizing conflicts with agriculture. [ABSTRACT FROM AUTHOR]

There is increasing evidence that intraspecific trait variation plays a role in governing rates of ecosystem functioning. While wood traits such as wood specific gravity (WSG) and wood carbon concentration (WCC) are key drivers of forest aboveground carbon (AGC) stocks, the sources of intraspecific variation in these wood traits and the consequences of this variation on AGC are poorly known, especially in the tropics.Here, we investigated intraspecific variation in wood specific gravity (WSG) and wood carbon concentration (WCC) from 556 individual trees belonging to 15 species that well characterize different successional stages of seasonal evergreen forests in Southeast Asia. Specifically, we tested the contribution of individual or species characteristics (tree size, growth rate and regeneration guilds) and local environmental conditions (topographic wetness index and successional stages) to intraspecific variation in WSG and WCC, and assessed the consequences of intraspecific variation in these wood traits on AGC estimates in 14 permanent forest plots established along a successional gradient in Khao Yai National park, Thailand.We found that tree size was the main driver of intraspecific variation in WSG and WCC as tree sizes increased from 10–100 cm in diameter, WSG increased by 7.3%, while WCC increased by 2.4% in heartwood, 1.6% and 2.7% in sapwood without and with volatile carbon included. There was no effect of the topographic wetness and other local environment condition in wood traits led to a slight overestimation of AGC in young secondary forests (+0.09% to +1.29%) and a small underestimation in older forests (−0.86% to −2.87%), but overall AGC estimates (13 of 14 forest plots) remained within error margins (the 95% interval).Our study provides evidence that tree size variation translates into intraspecific variability in wood traits, whereas local environmental conditions related to topography successional stages had no effect on wood trait variability. While size‐dependent variation in WSG and WCC have largely been undocumented and thus ignored in forest carbon assessment approaches, we highlight that it has a limited impact on AGC estimates, indicating that it does not invalidate current forest carbon stock estimation approaches. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Comparison of the carbon (C) stocks among different soil orders allows us to explore the role of various soil characteristics in long‐term C storage and their vulnerabilities. This study quantified and compared the accumulation rates of soil organic carbon (SOC) fractions (in 0–60 cm soil profile) in an Alfisol of Malda (25°27′33.9″N, 88°19′10.2″E) and an Entisol of Cooch Behar (26°09′62.7″N, 89°53′51.7″E) districts of West Bengal, India. We noticed a greater level of SOC (0–60 cm depth) in the Alfisol than the Entisol as the former soils were clayey in nature (fine textured) which provided the maximum stabilization of SOC compared to the Entisol (sandy textured). However, the storage of C fractions showed some peculiar results. The concentration of mineral‐associated carbon (Min‐C) was more or less similar in both the soil orders, but its stock was maximum in the Alfisol. While in the Entisol, permanganate oxidizable carbon (POX‐C) and particulate organic matter carbon (POM‐C) stocks recorded maximum among all the studied depths. A positive relation of SOC fractions and stocks with clay (r2 = >0.500 in the Alfisol; r2 = >0.700 in the Entisol) indicated the importance of finer fractions in profile storage of C. Min‐C contributed to SOC of about 75%–85% followed by POM‐C (3.27%–17.87%) and POX‐C (2.57%–4.22%). Higher stratification of SOC and POX‐C and POM‐C fractions was observed in Entisol; while in Alfisol, stratification of Min‐C was greater. Overall, this research demonstrated that the Alfisol has a greater potential in stabilizing Min‐C than the Entisol with POM‐C and POX‐C and the distribution of these fractions varied as per its stabilization. [ABSTRACT FROM AUTHOR]

Natural disturbances exacerbated by novel climate regimes are increasing worldwide, threatening the ability of forest ecosystems to mitigate global warming through carbon sequestration and to provide other key ecosystem services. One way to cope with unknown disturbance events is to promote the ecological resilience of the forest by increasing both functional trait and structural diversity and by fostering functional connectivity of the landscape to ensure a rapid and efficient self-reorganization of the system. We investigated how expected and unexpected variations in climate and biotic disturbances affect ecological resilience and carbon storage in a forested region in southeastern Canada. Using a process-based forest landscape model (LANDIS-II), we simulated ecosystem responses to climate change and insect outbreaks under different forest policy scenarios--including a novel approach based on functional diversification and network analysis--and tested how the potentially most damaging insect pests interact with changes in forest composition and structure due to changing climate and management. We found that climate warming, lengthening the vegetation season, will increase forest productivity and carbon storage, but unexpected impacts of drought and insect outbreaks will drastically reduce such variables. Generalist, non-native insects feeding on hardwood are the most damaging biotic agents for our region, and their monitoring and early detection should be a priority for forest authorities. Higher forest diversity driven by climate-smart management and fostered by climate change that promotes warm-adapted species, might increase disturbance severity. However, alternative forest policy scenarios led to a higher functional and structural diversity as well as functional connectivity--and thus to higher ecological resilience--than conventional management. Our results demonstrate that adopting a landscape-scale perspective by planning interventions strategically in space and adopting a functional trait approach to diversify forests is promising for enhancing ecological resilience under unexpected global change stressors. [ABSTRACT FROM AUTHOR]

Deep soil carbon (C) plays an important role in the global carbon cycle because it is more recalcitrant and remains in the soil for a longer period. Yet, very few studies have reported the impact of long‐term fertilization on soil organic carbon (SOC) dynamics in deep soil in a rice‐wheat system (RWS). Hence, the objectives of this study were to evaluate the long‐term fertilization impact on carbon sequestration and C pools in RWS in the Indo‐Gangetic Plain (IGP) of India. Application of 90 kg N, 20 kg P and 25 kg K ha−1 through mineral fertilizers (NPK) + green gram incorporation (GR) + 30 kg N ha−1 through farmyard manure (FYM) sequestered more C (25.86 Mg ha−1) in the 0–105 cm soil depth compared with mineral fertilizer alone (1.25 Mg ha−1). The C‐sequestration rate ranged between 0.61 to 1.23 Mg C ha−1 yr−1 under treatments having organic fertilizer and mineral fertilizer, whereas it varied from 0.06 to 0.39 Mg C ha−1 yr−1 in the treatments receiving mineral fertilizer only. Total C and critical C input were 197 Mg kg−1 and 1.94 Mg C ha−1 yr−1, respectively under NPK + GR + FYM treatment. Integrated application of mineral fertilizers and organics in treatments NPK + FYM, NPK + SPM (sulphitation press mud), NPK + GR, NPK + GR + FYM and NPK + CR (crop residue) resulted in higher sustainable yield index of RWS compared to mineral fertilizer alone. We conclude that application of organic material along with mineral fertilizers is essential to mitigate the atmospheric C load through C‐sequestration in deep soils and to attain sustainable RWS productivity in the IGP. [ABSTRACT FROM AUTHOR]

Experimental evidence of nutrient limitations on primary productivity in Afrotropical forests is rare and globally underrepresented yet are crucial for understanding constraints to terrestrial carbon uptake. In an ecosystem‐scale nutrient manipulation experiment, we assessed the early responses of tree growth rates among different tree sizes, taxonomic species, and at a community level in a humid tropical forest in Uganda. Following a full factorial design, we established 32 (eight treatments × four replicates) experimental plots of 40 × 40 m each. We added nitrogen (N), phosphorus (P), potassium (K), their combinations (NP, NK, PK, and NPK), and control at the rates of 125 kg N ha−1 year−1, 50 kg P ha−1 year−1 and 50 kg K ha−1 year−1, split into four equal applications, and measured stem growth of more than 15,000 trees with diameter at breast height (dbh) ≥1 cm. After 2 years, the response of tree stem growth to nutrient additions was dependent on tree sizes, species and leaf habit but not community wide. First, tree stem growth increased under N additions, primarily among medium‐sized trees (10–30 cm dbh), and in trees of Lasiodiscus mildbraedii in the second year of the experiment. Second, K limitation was evident in semi‐deciduous trees, which increased stem growth by 46% in +K than –K treatments, following a strong, prolonged dry season during the first year of the experiment. This highlights the key role of K in stomatal regulation and maintenance of water balance in trees, particularly under water‐stressed conditions. Third, the role of P in promoting tree growth and carbon accumulation rates in this forest on highly weathered soils was rather not pronounced; nonetheless, mortality among saplings (1–5 cm dbh) was reduced by 30% in +P than in –P treatments. Although stem growth responses to nutrient interaction effects were positive or negative (likely depending on nutrient combinations and climate variability), our results underscore the fact that, in a highly diverse forest ecosystem, multiple nutrients and not one single nutrient regulate tree growth and aboveground carbon uptake due to varying nutrient requirements and acquisition strategies of different tree sizes, species, and leaf habits. [ABSTRACT FROM AUTHOR]

Application of farmyard manure (FYM) is common practice to improve physical and chemical properties of arable soil and crop yields. However, studies on effects of FYM application mainly focussed on topsoils, whereas subsoils have rarely been addressed so far. We, therefore, investigated the effects of 36‐year FYM application with different rates of annual organic carbon (OC) addition (0, 469, 938 and 1875 g C m−2 a−1) on OC contents of a Chernozem in 0–30 cm (topsoil) and 35–45 cm (subsoil) depth. We also investigated its effects on soil structure and hydraulic properties in subsoil. X‐ray computed tomography was used to analyse the response of the subsoil macropore system (≥19 μm) and the distribution of particulate organic matter (POM) to different FYM applications, which were related to contents in total OC (TOC) and water‐extractable OC (WEOC). We show that FYM‐C application of 469 g C m−2 a−1 caused increases in TOC and WEOC contents only in the topsoil, whereas rates of ≥938 g C m−2 a−1 were necessary for TOC enrichment also in the subsoil. At this depth, the subdivision of TOC into different OC sources shows that most of the increase was due to fresh POM, likely by the stimulation of root growth and bioturbation. The increase in subsoil TOC went along with increases in macroporosity and macropore connectivity. We neither observed increases in plant‐available water capacity nor in unsaturated hydraulic conductivity. In conclusion, only very high application of FYM over long periods can increase OC content of subsoil at our study site, but this increase is largely based on fresh, easily degradable POM and likely accompanied by high C losses when considering the discrepancy between OC addition rate by FYM and TOC response in soil. Highlights: A new image processing procedure to distinguish fresh and decomposed POM.The increase of subsoil C stock based to a large extend on fresh, labile POM.Potential of arable subsoils for long‐term C storage by large FYM application rates is limited.The increase in TOC has no effect on hydraulic properties of the subsoil. [ABSTRACT FROM AUTHOR]

Mangrove ecosystem provides important services for coastal communities. Unfortunately, this ecosystem has undergone physical pressures for decades, including land conversion for shrimp aquaculture. Rehabilitation of the degraded mangroves offers an effective solution for bringing back mangrove functions, including carbon sequestration capacity. This study aims to quantify carbon stock (CS) and sequestration rate of a rehabilitated mangrove ecosystem in Indonesia, particularly in Banten Province. We compared sediment CS and carbon accumulation rate (CAR) of a rehabilitated mangrove in Ciseukeut, Panimbang, with a natural mangrove in Cilintang, the Ujung Kulon National Park. The sediment CS to a depth of 1 m in a rehabilitated mangrove in Ciseukeut was higher than in a natural mangrove in Cilintang, constituting 364 Mg C ha−1 and 126 Mg C ha−1, respectively. However, CAR showed the opposite pattern, in which a natural mangrove showed an almost two‐fold higher rate (0.50 ± 0.42 Mg C ha−1 year−1) than that of a rehabilitated mangrove (0.27 ± 0.20 Mg C ha−1 year−1). Local hydrogeomorphological conditions play a role in affecting sediment CS and CAR in both sites. Enhancing hydrological modification can promote CAR, especially in an abandoned pond like in Ciseukeut. This study provided a knowledge base for suitable mangrove rehabilitation in the future that supports the Indonesian government's commitment to rehabilitating ca. 600,000 ha of degraded mangroves in Indonesia. Furthermore, the study also provides the first investigation of potential blue carbon for the world's natural heritage of the Ujung Kulon National Park. [ABSTRACT FROM AUTHOR]

Mathematical models of long‐term peatland development have been produced to analyse peatland behaviour. However, existing models ignore the mechanical processes that have the potential to provide important feedback. Here, we propose a one‐dimensional model, MPeat, that couples mechanical, ecological and hydrological processes via poroelasticity theory, which couples fluid flow and solid deformation. Poroelasticity formulation in the MPeat is divided into two categories, fully saturated and unsaturated. To validate this formulation, we compare numerical solutions of the fully saturated case with analytical solutions of Terzaghi's problem. Two groups of MPeat simulations are run over 6,000 years using constant and variable climate, and the results are compared to those of two other peat growth models, DigiBog and the Holocene Peat Model. Under both climatic conditions, MPeat generates the expected changes in bulk density, active porosity and hydraulic conductivity at the transition from the unsaturated to the saturated zone. The range of values of peat physical properties simulated by MPeat shows good agreement with field measurement, indicating plausible outputs of the proposed model. Compared to the other peat growth models, the results generated by MPeat illustrate the importance of poroelasticity to the behaviour of peatland. In particular, the inclusion of poroelasticity produces shallower water table depth, accumulates greater quantities of carbon and buffers the effect of climate changes on water table depth and carbon accumulation rates. These results illustrate the importance of mechanical feedbacks on peatland ecohydrology and carbon stock resilience. [ABSTRACT FROM AUTHOR]

Physiographic factors effectively alter soil properties and carbon storage. However, previous research on the effect of topographic factors affecting soil properties on carbon stocks in tea plantations has been limited in the humid Black Sea region. The aim of this study was to determine the effects of elevation, aspect, and soil depth on carbon stocks and soil properties of tea plantations in the Black Sea region. The tea plantations in the research area were divided into two elevation steps and two different aspect groups. Twelve soil sampling plots were then determined according to the stratified random sampling method in each elevation and aspect group; soil samples were taken at 0–10 cm and 10–30 cm soil depths. The amount of carbon stored at a soil depth of 30 cm was found to be 49.38 and 32.36 Mg C ha−1 at the upper and lower altitudes, respectively. Highest carbon density in the tea plantations in the research area was found to be 16.34 kg m−3 at a depth of 0–10 cm. The changes in the soil organic carbon (SOC) values according to elevation and soil depth were statistically significant, while the difference among the carbon storage values was not statistically significant. According to the results of our investigation, elevation is a more effective factor than aspect on SOC in tea plantation areas of highly humid climates. [ABSTRACT FROM AUTHOR]

Nitrogen‐fixing Nepalese alder (Alnus nepalensis D. Don.) is a rapidly‐growing pioneer tree species that often forms pure stands in areas affected by landslides, but also occurs mixed with other late‐successional species in the central Himalayas. In this study, we assessed the distribution of carbon in vegetation and soil in a chronosequence of A. nepalensis (3–270 years old) forest stands and evaluated its correlation with the stand and alder total basal area (TBA). The study was conducted in six different naturally occurring forest stands in a chronosequence, viz., alder‐early regenerating (AER), alder‐late regenerating (ALR), alder young‐mixed (AYM), alder mature‐oak (Quercus leucotrichophora) mixed (AMOM), alder mature‐rhododendron (Rhododendron arboreum) mixed (AMR), and alder old‐oak (Q. leucotrichophora) mixed (AOOM) forests. The chronosequence consisted of three young unreserved, AER, ALR, and AYM (age 3–25) and three older reserved, AMOM, AMR, and AOOM (age 80–270) stands. We used structural equation modelling (SEM) to quantify the contribution of various carbon pools on ecosystem carbon stock. Forest carbon stock significantly increased (p < 0.05) with forest age and TBA, indicating that succession is the driving factor of the forest ecosystem processes, carbon accumulation, and therefore, change in vegetation biomass carbon and soil carbon in the chronosequence of A. nepalensis forests. Total vegetation biomass carbon (tree, shrubs, herbs, and litter) contained ~12.54–289.85 Mg ha−1 (79.11–57.77% total carbon stock), and soil carbon (depths of 0–10 cm in AER, 0–30 cm in AYM, 0–100 cm in remaining forest stands) contained ~3.31–210.13 Mg ha−1 (20.8–42% total carbon stock) and positively increased with stand and A. nepalensis TBA. The tree layer biomass carbon stock was considerably higher than the understory (shrubs, herbs, and forest floor). The soil carbon stock was reported to be influenced by the successional stages. Therefore, these findings reflect that the A. nepalensis forest development in the central Himalayas lead to storage of large amount of carbon stock in both plant biomass and soil. [ABSTRACT FROM AUTHOR]

Spatially resolved estimates of change in soil organic carbon (SOC) stocks are necessary for supporting national and international policies aimed at achieving land degradation neutrality and climate change mitigation. In this work we report on the development, implementation and application of a data‐driven, statistical method for mapping SOC stocks in space and time, using Argentina as a pilot. We used quantile regression forest machine learning to predict annual SOC stock at 0–30 cm depth at 250 m resolution for Argentina between 1982 and 2017. The model was calibrated using over 5,000 SOC stock values from the 36‐year time period and 35 environmental covariates. We preprocessed normalized difference vegetation index (NDVI) dynamic covariates using a temporal low‐pass filter to allow the SOC stock for a given year to depend on the NDVI of the current as well as preceding years. Predictions had modest temporal variation, with an average decrease for the entire country from 2.55 to 2.48 kg C m−2 over the 36‐year period (equivalent to a decline of 211 Gg C, 3.0% of the total 0–30 cm SOC stock in Argentina). The Pampa region had a larger estimated SOC stock decrease from 4.62 to 4.34 kg C m−2 (5.9%) during the same period. For the 2001–2015 period, predicted temporal variation was seven‐fold larger than that obtained using the Tier 1 approach of the Intergovernmental Panel on Climate Change and United Nations Convention to Combat Desertification. Prediction uncertainties turned out to be substantial, mainly due to the limited number and poor spatial and temporal distribution of the calibration data, and the limited explanatory power of the covariates. Cross‐validation confirmed that SOC stock prediction accuracy was limited, with a mean error of 0.03 kg C m−2 and a root mean squared error of 2.04 kg C m−2. In spite of the large uncertainties, this work showed that machine learning methods can be used for space–time SOC mapping and may yield valuable information to land managers and policymakers, provided that SOC observation density in space and time is sufficiently large. Highlights: We tested the use of machine learning for space–time mapping of soil organic carbon (SOC) stock.Predictions for Argentina from 1982 to 2017 showed a 3% decrease of the topsoil SOC stock over time.The machine learning model predicted a greater temporal variation than the IPCC Tier 1 approach.Accurate machine learning SOC stock prediction requires dense soil sampling in space and time. [ABSTRACT FROM AUTHOR]

Global vegetated coastal habitats (VCHs) represent a large sink for organic carbon (OC) stored within their soils. The regional patterns and causes of spatial variation, however, remain uncertain. The sparsity and regional bias of studies on soil OC stocks from Chinese VCHs have limited the reliable estimation of their capacity as regional and global OC sinks. Here, we use field and published data from 262 sampled soil cores and 181 surface soils to report estimates of soil OC stocks, burial rates and losses of VCHs in China. We find that Chinese mangrove, salt marsh and seagrass habitats have relatively low OC stocks, storing 6.3 ± 0.6, 7.5 ± 0.6, and 1.6 ± 0.6 Tg C (±95% confidence interval) in the top meter of the soil profile with burial rates of 44 ± 17, 159 ± 57, and 6 ± 45 Gg C/year, respectively. The variability in the soil OC stocks is linked to biogeographic factors but is mostly impacted by sedimentary processes and anthropic activities. All habitats have experienced significant losses, resulting in estimated emissions of 94.2–395.4 Tg CO2e (carbon dioxide equivalent) over the past 70 years. Reversing this trend through conservation and restoration measures has, therefore, great potential in contributing to the mitigation of climate change while providing additional benefits. This assessment, on a national scale from highly sedimentary environments under intensive anthropogenic pressures, provides important insights into blue carbon sink mechanism and sequestration capacities, thus contributing to the synchronous progression of global blue carbon management. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) is an acknowledged indicator for land degradation, but conventional determination of SOC remains tedious, especially regarding SOC stock (in kg C m−2 for a given depth layer), which is the product of SOC concentration (g C kg−1) by volumetric mass (kg dm−3). Diffuse reflectance infrared spectroscopy (DRIS) is a time‐ and cost‐effective approach, which uses calibrations for making predictions. The aim of this paper is to propose an overview of DRIS uses for estimating SOC, thus land degradation. Indeed, many papers have demonstrated the precision of DRIS for quantifying SOC concentration, at different scales. Current development of large soil calibration databases and improvements in spectral data analysis pave the way for ever‐wider use of DRIS, which should help solving the soil data crisis, regarding SOC especially. The increasing availability of portable spectrometers allows SOC quantification in the field, which seems particularly promising; but large calibration databases made of soil spectra acquired in the field are difficult to build, while large collections of analyzed soil samples (air‐dried, 2‐mm sieved) already exist. Some recent studies indicate that DRIS can also be used for predicting SOC stock, even from sieved samples, which represents an efficient option because determining the volumetric mass is particularly tedious and an obstacle for exactly specifying the role of soils in the global carbon cycle. In short, DRIS has strong potential for supporting better evaluation of soil and land degradation, and the availability of spectrometers at increasingly affordable prices reinforces this potential. [ABSTRACT FROM AUTHOR]

Globally, ravine landscapes are considered among the world's most degraded ecosystems. Restoring ravines is considered a high priority item in the conservation programmes, and tree establishment augmented with appropriate soil and water conservation measures is the most sought‐after restoration strategy. This study examined the impact of terracing and trenching on runoff, soil loss, and soil properties along with Sapota (Achras zapota) growth, fruit yield, biomass and carbon stock during 6 years (2010–2015) in a degraded ravine land of Western India. The four soil and water conservation strategies tested were (1) bench terracing + Sapota (Bt), (2) bench terracing + Sapota with crop cultivation (BtCr), (3) continuous slope + Sapota (Sl), and (4) continuous slope + Sapota with trenches (SlTr). All conservation techniques increased Sapota height (Bt: 54%; BtCr: 27%; SlTr: 35%) and basal diameter (Bt: 36%; BtCr: 18%; StCr: 22%) compared to Sl. Biomass and carbon stock of Sapota were in the order of Bt > SlTr > BtCr > Sl. During the droughtperiod, fruit yield was highest in Bt followed by BtCr, SlTr, and least in Sl. The treatment SlTr and Bt reduced runoff by 16–34% and soil loss by 15–25%, compared to Sl. The growth and biomass were strongly correlated with soil loss. The findings suggested that bench terracing is the best soil and water conservation measure for restoring highly degraded ravines of Western India. Under circumstances where terracing is not feasible, trenching could be a significant step along with Sapota plantation to restore these ravines. [ABSTRACT FROM AUTHOR]

The fate of soil organic carbon (SOC) under warming is poorly understood, particularly across large extents and in the whole‐soil profile. Using a data‐model integration approach applied across the globe, we find that downward movement of SOC along the soil profile reduces SOC loss under warming. We predict that global SOC stocks (down to 2 m) will decline by 4% (~80 Pg) on average when SOC reaches the steady state under 2°C warming, assuming no changes in net primary productivity (NPP). To compensate such decline (i.e. maintain current SOC stocks), a 3% increase of NPP is required. Without the downward SOC movement, global SOC declines by 15%, while a 20% increase in NPP is needed to compensate that loss. This vital role of downward SOC movement in controlling whole‐soil profile SOC dynamics in response to warming is due to the protection afforded to downward‐moving SOC by depth, indicated by much longer residence times of SOC in deeper layers. Additionally, we find that this protection could not be counteracted by promoted decomposition due to the priming of downward‐moving new SOC from upper layers on native old SOC in deeper layers. This study provides the first estimation of whole‐soil SOC changes under warming and additional NPP required to compensate such changes across the globe, and reveals the vital role of downward movement of SOC in reducing SOC loss under global warming. [ABSTRACT FROM AUTHOR]

Forests play an important role in both regional and global C cycles. However, the spatial patterns of biomass C density and underlying factors in Northeast Asia remain unclear. Here, we characterized spatial patterns and important drivers of biomass C density for Northeast Asia, based on multisource data from in situ forest inventories, as well as remote sensing, bioclimatic, topographic, and human footprint data. We derived, for the first time, high‐resolution (1 km × 1 km) maps of the current and future forest biomass C density for this region. Based on these maps, we estimated that current biomass C stock in northeastern China, the Democratic People's Republic of Korea, and Republic of Korea to be 2.53, 0.40, and 0.35 Pg C, respectively. Biomass C stock in Northeast Asia has increased by 20%–46% over the past 20 years, of which 40%–76% was contributed by planted forests. We estimated the biomass C stock in 2080 to be 6.13 and 6.50 Pg C under RCP4.5 and RCP8.5 scenarios, respectively, which exceeded the present region‐wide C stock value by 2.85–3.22 Pg C, and were 8%–14% higher than the baseline C stock value (5.70 Pg C). The spatial patterns of biomass C densities were found to vary greatly across the Northeast Asia, and largely decided by mean diameter at breast height, dominant height, elevation, and human footprint. Our results suggest that reforestation and forest conservation in Northeast Asia have effectively expanded the size of the carbon sink in the region, and sustainable forest management practices such as precision forestry and close forest monitoring for fire and insect outbreaks would be important to maintain and improve this critical carbon sink for Northeast Asia. [ABSTRACT FROM AUTHOR]

A growing number of initiatives at global, regional and national scales propose to plant millions, billions or even trillions of trees as a simple solution to resolve complex environmental problems. However, tree planting is much more complicated than it seems.We summarize the multifaceted decision‐making process needed and offer guidelines to increase the success of the proposed ambitious efforts to increase tree cover world‐wide.Given the varied definitions of and motivations for tree planting, it is critical that stakeholders work together to clearly define the biophysical and socioeconomic goals of each project. Then a series of questions must be addressed about where and how (e.g. planting trees vs. allowing for natural forest regrowth) to most effectively achieve these goals and minimize unintended negative consequences, as well as how, when and by whom success of efforts will be evaluated.Key guidelines to successfully increase tree cover include: (a) first addressing the underlying drivers of deforestation; (b) integrating decision‐making across scales from local to global; (c) tailoring tree planting strategies to clearly stated project goals and planning, adaptively managing and evaluating success over a sufficiently long timeframe; (d) focusing on the forest ecosystem as a whole, and not just the trees; (e) coordinating different land uses and (f) involving stakeholders at all stages of the planning process.Synthesis and applications. Tree planting, along with other strategies to increase tree cover in appropriate locations and contexts, can make a valuable contribution to ensuring the ecological and social well‐being of our planet in coming decades, but only if these efforts are considered as one component of multifaceted solutions to complex environmental problems and are carefully planned, implemented and monitored over a sufficiently long time‐scale with stakeholder engagement and broader consideration of socio‐ecological complexities. [ABSTRACT FROM AUTHOR]

Exclosures are used to regenerate native vegetation as a way to reduce soil erosion, increase rain water infiltration and provide fodder and woody biomass in degraded grazing lands. Therefore, this study assessed the impact of grazing exclosure on carbon sequestration and soil nutrients under 5 and 10 years of grazing exclosures and freely grazed areas in Tigray, northern Ethiopia. Carbon stocks and soil nutrients increased with increasing grazing exclusion. However, open grazing lands and 5 years of grazing exclosure did not differ in above‐ and belowground carbon stocks. Moreover, 10 years of grazing exclosure had a higher (p < 0.01) grass, herb and litter carbon stocks compared to 5 years exclosure and open grazing lands. The total carbon stock was higher for 10 years exclosure (75.65 t C ha‐1) than the 5 years exclosure (55.06 t C ha‐1) and in open grazing areas (51.98 t C ha‐1). Grazing lands closed for 10 years had a higher SOC, organic matter, total N, available P, and exchangeable K + and Na + compared to 5 year's exclosure and open grazing lands. Therefore, establishment of grazing exclosures had a positive effect in restoring degraded grazing lands, thus improving carbon sequestration potentials and soil nutrients. [ABSTRACT FROM AUTHOR]

Wetlands contain a large proportion of carbon (C) in the biosphere and partly affect climate by regulating C cycles of terrestrial ecosystems. China contains Asia's largest wetlands, accounting for about 10% of the global wetland area. Although previous studies attempted to estimate C budget in China's wetlands, uncertainties remain. We conducted a synthesis to estimate C uptake and emission of wetland ecosystems in China using a dataset compiled from published literature. The dataset comprised 193 studies, including 370 sites representing coastal, river, lake and marsh wetlands across China. In addition, C stocks of different wetlands in China were estimated using unbiased data from the China Second Wetlands Survey. The results showed that China's wetlands sequestered 16.87 Pg C (315.76 Mg C/ha), accounting for about 3.8% of C stocks in global wetlands. Net ecosystem productivity, jointly determined by gross primary productivity and ecosystem respiration, exhibited annual C sequestration of 120.23 Tg C. China's wetlands had a total gaseous C loss of 173.20 Tg C per year from soils, including 154.26 Tg CO2‐C and 18.94 Tg CH4‐C emissions. Moreover, C stocks, uptakes and gaseous losses varied with wetland types, and were affected by geographic location and climatic factors (precipitation and temperature). Our results provide better estimation of the C budget in China's wetlands and improve understanding of their contribution to the global C cycle in the context of global climate change. [ABSTRACT FROM AUTHOR]

Urban green spaces provide manifold environmental benefits and promote human well‐being. Unfortunately, these services are largely undervalued, and the potential of urban areas themselves to mitigate future climate change has received little attention. In this study, we quantified and mapped city‐wide aboveground carbon storage of urban green spaces in China's capital, Beijing, using field survey data of diameter at breast height (DBH) and tree height from 326 field survey plots, combined with satellite‐derived vegetation index at a fine resolution of 6 m. We estimated the total amount of carbon stored in the urban green spaces to be 956.3 Gg (1 Gg = 109 g) in 2014. There existed great spatial heterogeneity in vegetation carbon density varying from 0 to 68.1 Mg C ha‐1, with an average density of 7.8 Mg C ha−1. As expected, carbon density tended to decrease with urban development intensity (UDI). Likely being affected by vegetation cover proportion and configuration of green space patches, large differences were presented between the 95th and 5th quantile carbon density for each UDI bin, showing great potential for carbon sequestration. However, the interquartile range of carbon density narrowed drastically when UDI reached 60%, signifying a threshold for greatly reduced carbon sequestration potentials for higher UDI. These findings suggested that urban green spaces have great potential to make contribution to mitigating against future climate change if we plan and design urban green spaces following the trajectory of high carbon density, but we should be aware that such potential will be very limited when the urban development reaches certain intensity threshold. [ABSTRACT FROM AUTHOR]

Abstract: The accumulation of soil carbon (C) is regulated by a complex interplay between abiotic and biotic factors. Our study aimed to identify the main drivers of soil C accumulation in the boreal forest of eastern North America. Ecosystem C pools were measured in 72 sites of fire origin that burned 2–314 years ago over a vast region with a range of ∆ mean annual temperature of 3°C and one of ∆ 500 mm total precipitation. We used a set of multivariate a priori causal hypotheses to test the influence of time since fire (TSF), climate, soil physico‐chemistry and bryophyte dominance on forest soil organic C accumulation. Integrating the direct and indirect effects among abiotic and biotic variables explained as much as 50% of the full model variability. The main direct drivers of soil C stocks were: TSF >bryophyte dominance of the FH layer and metal oxide content >pH of the mineral soil. Only climate parameters related to water availability contributed significantly to explaining soil C stock variation. Importantly, climate was found to affect FH layer and mineral soil C stocks indirectly through its effects on bryophyte dominance and organo‐metal complexation, respectively. Soil texture had no influence on soil C stocks. Soil C stocks increased both in the FH layer and mineral soil with TSF and this effect was linked to a decrease in pH with TSF in mineral soil. TSF thus appears to be an important factor of soil development and of C sequestration in mineral soil through its influence on soil chemistry. Overall, this work highlights that integrating the complex interplay between the main drivers of soil C stocks into mechanistic models of C dynamics could improve our ability to assess C stocks and better anticipate the response of the boreal forest to global change. [ABSTRACT FROM AUTHOR]

Premise of the Study: Basic wood density is an important ecological trait for woody plants. It is used to characterize species performance and fitness in community ecology and to compute tree and forest biomass in carbon cycle studies. While wood density has been historically measured at 12% moisture, it is convenient for ecological purposes to convert this measure to basic wood density, i.e., the ratio of dry mass over green volume. Basic wood density can then be used to compute tree dry biomass from living tree volume. Methods: Here, we derive a new exact formula to compute the basic wood density Db from the density at moisture content w denoted Dw, the fiber saturation point S, and the volumetric shrinkage coefficient R. We estimated a new conversion factor using a global wood technology database where values to use this formula are available for 4022 trees collected in 64 countries (mostly tropical) and representing 872 species. Key Results: We show that previous conversion factors used to convert densities at 12% moisture into basic wood densities are inconsistent. Based on theory and data, we found that basic wood density could be inferred from the density at 12% moisture using the following formula: Db = 0.828D12. This value of 0.828 provides basic wood density estimates 4–5% smaller than values inferred from previous conversion factors. Conclusions: This new conversion factor should be used to derive basic wood densities in global wood density databases. Its use would prevent overestimating global forest carbon stocks and allow predicting better tree species community dynamics from wood density. [ABSTRACT FROM AUTHOR]

Abstract: In striking contrast to heartening events in the adjacent Amazon, Brazil's Cerrado biome has seen continued deforestation over the past decade. Though approved in 2012, no study evaluated the impacts of new Brazilian Forest Code (FC) revision on biodiversity and ecosystem services. Here, we report the first assessment of the likely loss and gain in biodiversity and ecosystem services expected if the FC is properly enforced across 200 million hectares of the Cerrado. We also discuss the challenges associated to compliance with the law and present opportunities for conservation. Establishing restoration programmes in private properties with currently less native vegetation than required by the FC could create habitat for 25% more threatened species than now found in these places and could also increase water security and carbon stock in 56.6 MtC. More important, trading environmental reserve quotas coupled with the strategic expansion of protected areas on private and public land could definitely rescue the Cerrado from the brink. [ABSTRACT FROM AUTHOR]

Abstract: Despite the general recognition that fragmentation can reduce forest biomass through edge effects, a systematic review of the literature does not reveal a clear role of edges in modulating biomass loss. Additionally, the edge effects appear to be constrained by matrix type, suggesting that landscape composition has an influence on biomass stocks. The lack of empirical evidence of pervasive edge‐related biomass losses across tropical forests highlights the necessity for a general framework linking landscape structure with aboveground biomass. Here, we propose a conceptual model in which landscape composition and configuration mediate the magnitude of edge effects and seed‐flux among forest patches, which ultimately has an influence on biomass. Our model hypothesizes that a rapid reduction of biomass can occur below a threshold of forest cover loss. Just below this threshold, we predict that changes in landscape configuration can strongly influence the patch's isolation, thus enhancing biomass loss. Moreover, we expect a synergism between landscape composition and patch attributes, where matrix type mediates the effects of edges on species decline, particularly for shade‐tolerant species. To test our conceptual framework, we propose a sampling protocol where the effects of edges, forest amount, forest isolation, fragment size, and matrix type on biomass stocks can be assessed both collectively and individually. The proposed model unifies the combined effects of landscape and patch structure on biomass into a single framework, providing a new set of main drivers of biomass loss in human‐modified landscapes. We argue that carbon trading agendas (e.g., REDD+) and carbon‐conservation initiatives must go beyond the effects of forest loss and edges on biomass, considering the whole set of effects on biomass related to changes in landscape composition and configuration. [ABSTRACT FROM AUTHOR]

The Royal Belum forest reserve is one of the oldest tropical rainforests in the world and it is one of the largest virgin forest reserves in Malaysia. However, not many studies have been conducted to understand the ecology of this forest. In this study we estimated the aboveground biomass (AGB) of the forest using diameter at breast height (DBH) and height of trees (h), tree species and hemispherical photographs of tree canopy. We estimated AGB using five allometric equations. Our results demonstrated that the AGB given by the one tree species specific allometric equation does not show any significant differences from the values given by the non‐tree species specific allometric equations at tree and plot levels. The AGB of Intsia bijuga species, Koompassia malaccensis species and Shorea genera were comparatively higher, owing to their greater wood density, DBH and h. This has added importance because some of these species are categorized as threatened species. Our results demonstrated that mean AGB values in this forest (293.16 t ha‐1) are the highest compared to some studies of other areas in Malaysia, tropical Africa and tropical Bazilian Amazonia, implying that the Royal Belum forest reserve, is an important carbon reservoir. [ABSTRACT FROM AUTHOR]

Lianas (woody climbers) have a greater amount of leaves relative to basal area or standing biomass than trees, and very wide vessels that permit efficient water transport. These features suggest that lianas possibly consume proportionally more water through transpiration than trees. Despite their potential importance, researchers have made only limited attempts to evaluate effects of lianas on forest water dynamics., We conducted sap flow measurements for 1 year using a thermal dissipation method for four species each of lianas and trees in a liana-rich, warm-temperate forest in Japan and estimated the contribution of lianas to stand canopy transpiration., Based on a calibration measuring water uptake rates from cut-stem ends, the actual sap flux ( Fd) in liana stems was several times greater than those estimated from the original calibration provided for the method. In the field, lianas showed an average of 2-4 times greater Fd than trees throughout the year. Except for this difference, diurnal and seasonal patterns of relative changes of Fd were similar in both groups. The whole-plant transpiration ( Qt) of sample plants was exponentially related to basal diameter for both lianas and trees; Qt of lianas increased more steeply with basal diameter than that of trees. By extrapolating the relationships between Qt and basal diameter to the inventory data of the study plot, we estimated that lianas contributed 12·8% to the annual stand canopy transpiration while comprising 2·3% of stand basal area, which probably reflected the top-heavy architecture of lianas., Our results indicate that the contribution of lianas to forest water dynamics may be several times greater than their contribution to forest basal area. This implies that a slight increase of liana abundance might have greater effects on water dynamics and, through competitions with trees for limited water, the carbon sequestration capacity of forests than expected from the increase in basal area. This study underlines the necessity of evaluating the relative importance of lianas to forest water dynamics in forests world-wide., A is available for this article. [ABSTRACT FROM AUTHOR]

Global carbon cycles are impacted by human activity primarily via fossil fuel combustion and forest carbon budget alterations. In this study, the temporal dynamics and spatial distribution of forest biomass carbon ( FBC) stock and density in China were analyzed to assess the large-scale effects of humans on FBC. The results indicated that from 1977 to 2013, the FBC stock increased by 62.9%, from 4,335 to 7,064 Tg C, owing to human-driven forestation and ecological restoration programs. Because of intensive human impacts, 44.2%-54.6% of the FBC stock was concentrated in four provinces (Heilongjiang, Yunnan, Inner Mongolia, and Sichuan) and the FBC density increased from the densely populated southeastern provinces to the sparsely populated northeastern and western provinces. On a spatial scale, the FBC density was significantly negatively related to population density, and the degree of the dependence of the FBC density on population density has been declining since 1998. This improvement in human-forest relations is related to economic development and programs in China that have promoted forestation and reduced deforestation. These results suggest that human impacts, including forestation, deforestation, population density, and economic development, have played significant roles in determining the temporal and spatial variations of FBC in the anthropogenic era. Moreover, our findings have implications for forest management and improvement of the forest carbon sink in China. [ABSTRACT FROM AUTHOR]

Most of the Earth System Models ( ESMs) project increases in net primary productivity ( NPP) and terrestrial carbon (C) storage during the 21st century. Despite empirical evidence that limited availability of phosphorus (P) may limit the response of NPP to increasing atmospheric CO2, none of the ESMs used in the previous Intergovernmental Panel on Climate Change assessment accounted for P limitation. We diagnosed from ESM simulations the amount of P need to support increases in carbon uptake by natural ecosystems using two approaches: the demand derived from (1) changes in C stocks and (2) changes in NPP. The C stock-based additional P demand was estimated to range between −31 and 193 Tg P and between −89 and 262 Tg P for Representative Concentration Pathway ( RCP) 2.6 and RCP8.5, respectively, with negative values indicating a P surplus. The NPP-based demand, which takes ecosystem P recycling into account, results in a significantly higher P demand of 648-1606 Tg P for RCP2.6 and 924-2110 Tg P for RCP8.5. We found that the P demand is sensitive to the turnover of P in decomposing plant material, explaining the large differences between the NPP-based demand and C stock-based demand. The discrepancy between diagnosed P demand and actual P availability (potential P deficit) depends mainly on the assumptions about availability of the different soil P forms. Overall, future P limitation strongly depends on both soil P availability and P recycling on ecosystem scale. [ABSTRACT FROM AUTHOR]

Land degradation has been a global environmental issue, and its cause includes poorly managed grazing. Quantitative information is needed to support policy actions for food and water security and development. The objective of this study was to assess and characterize CO2-C emissions in degraded (DP) and managed pasture (MP) areas located close to one another, describing their spatial-temporal variability and any correlation with possible controlling factors. A grid of 100 × 100 m with 102 sample points in each area was set up. Measurements of CO2-C emission (FCO2), soil temperature ( Tsoil), soil water content (WCsoil), soil physical (i.e. soil texture, soil bulk density, macro-porosity, micro-porosity, air-filled pore space and total pore volume) and chemical (i.e. pH, calcium, magnesium, phosphorus, potassium and cation exchange capacity) analysis were conducted at each sample point. Total emissions calculated from the area below the FCO2 graphs were 640.7 and 440.0 kg CO2-C ha−1 in the DP and MP, respectively. Soil temperature in the MP was lower ( t-test, p < 0.01) throughout the experimental period when compared with the DP. This study found that the degraded pasture area released significantly more CO2-C compared with the well-managed pasture. Therefore, the introduction of best management practices in pasture areas is an important strategy to reduce soil CO2-C losses and promote soil C accumulation. The MP presented lower FCO2 despite its higher soil C stock, indicating a more stable soil C condition when compared with the DP area. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Ensuring ecological sustainability in fragile ecosystems has always been a top priority in China. Under the 'Grain for Green' Program (GGP), Caragana korshinskii Kom plantations are valued for their important use in soil and water conservation efforts on the Loess Plateau. This study was to estimate biomass increment and carbon accumulation in five different age classes [young age (YO), middle age (MI), pre-mature (PR), mature (MA) and post-mature (PO)], as well as the distribution of carbon stock among the various biomass components and soil depths. The results showed afforestation with C. korshinskii resulted in a significant increase in plant biomass and carbon stock, and soil organic carbon stocks. The total ecosystem carbon stock showed a notable carbon sink increase rate of 1.33 Mg ha−1 yr−1 from the YO to the MA stage, and then slightly decreased. The total biomass carbon of the understory plants represented only a relatively small fraction in the ecosystem, accounting for 2.4%-8.7% (median 3.8%). The proportion of ligneous components (roots, stems and branches) of C. korshinskii was increased following stand development. Our study suggested that C. korshinskii plantations should be harvested and revegetated following the MA stage (~35 years). Continuation of the GGP on the Loess Plateau, together with maturation of C. korshinskii trees over the next few years, will increase carbon sequestration in the medium term. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

More than half of the cultivation-induced carbon loss from agricultural soils could be restored through improved management. To incentivise carbon sequestration, the potential of improved practices needs to be verified. To date, there is sparse empirical evidence of carbon sequestration through improved practices in East-Africa. Here, we show that agroforestry and restrained grazing had a greater stock of soil carbon than their bordering pair-matched controls, but the difference was less obvious with terracing. The controls were treeless cultivated fields for agroforestry, on slopes not terraced for terracing, and permanent pasture for restrained grazing, representing traditionally managed agricultural practices dominant in the case regions. The gain by the improved management depended on the carbon stocks in the control plots. Agroforestry for 6-20 years led to 11.4 Mg ha−1 and restrained grazing for 6-17 years to 9.6 Mg ha−1 greater median soil carbon stock compared with the traditional management. The empirical estimates are higher than previous process-model-based estimates and indicate that Ethiopian agriculture has greater potential to sequester carbon in soil than previously estimated. [ABSTRACT FROM AUTHOR]

The relationship between biodiversity and ecosystem function has increasingly been debated as the cornerstone of the processes behind ecosystem services delivery. Experimental and natural field-based studies have come up with nonconsistent patterns of biodiversity-ecosystem function, supporting either niche complementarity or selection effects hypothesis. Here, we used aboveground carbon ( AGC) storage as proxy for ecosystem function in a South African mistbelt forest, and analyzed its relationship with species diversity, through functional diversity and functional dominance. We hypothesized that (1) diversity influences AGC through functional diversity and functional dominance effects; and (2) effects of diversity on AGC would be greater for functional dominance than for functional diversity. Community weight mean ( CWM) of functional traits (wood density, specific leaf area, and maximum plant height) were calculated to assess functional dominance (selection effects). As for functional diversity (complementarity effects), multitrait functional diversity indices were computed. The first hypothesis was tested using structural equation modeling. For the second hypothesis, effects of environmental variables such as slope and altitude were tested first, and separate linear mixed-effects models were fitted afterward for functional diversity, functional dominance, and both. Results showed that AGC varied significantly along the slope gradient, with lower values at steeper sites. Species diversity (richness) had positive relationship with AGC, even when slope effects were considered. As predicted, diversity effects on AGC were mediated through functional diversity and functional dominance, suggesting that both the niche complementarity and the selection effects are not exclusively affecting carbon storage. However, the effects were greater for functional diversity than for functional dominance. Furthermore, functional dominance effects were strongly transmitted by CWM of maximum plant height, reflecting the importance of forest vertical stratification for diversity-carbon relationship. We therefore argue for stronger complementary effects that would be induced also by complementary light-use efficiency of tree and species growing in the understory layer. [ABSTRACT FROM AUTHOR]

In the fragile hilly ecosystem of North-eastern Himalayan Region (NEHR) of India, interaction of land use change and soil organic carbon (SOC) holds significance in sustaining land productivity. However, because of limited data, the effect of land use on SOC inventory at regional level is poorly quantified. The present study assessed the influence of seven major land uses and agrophysical variables (soil texture, bulk density, annual rainfall and mean temperature) on SOC concentration and stock across altitudinal gradients (6-3,500 masl) of NEHR of India. Results revealed that non-agricultural land uses (grasslands and forests) registered significantly higher SOC concentration (2·20 to 2·51%) and stock (35·2-42·1 Mg ha−1) compared with agricultural (shifting and settled-up and lowlands), plantation and horticultural land uses (SOC, 1·44 to 1·63%; stock, 27·4-28·4 Mg ha−1). Principal component analysis exhibited that the variation in SOC concentration among the land uses was mostly contributed by finer fractions of soil separates (silt and clay contents), and altitudinal gradient led variation in climatic variables (rainfall and temperature). Trend analyses depicted that SOC increased with an increase in rainfall and clay content but decreased with mean temperature and soil bulk density. Along the altitudinal gradient (6 to 1,000 masl), an inconsistent increase in silt + clay, annual rainfall, SOC concentration, and stock was also observed. However, beyond 1,000 masl, the corresponding increase was linear. The wide variability in SOC concentration and stock, therefore, resulted from the interaction of land uses, altitudinal gradients, textural gradients and climatic variables Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Aim We developed a set of statistical models to improve spatial estimates of mangrove aboveground biomass ( AGB) based on the environmental signature hypothesis ( ESH). We hypothesized that higher tidal amplitudes, river discharge, temperature, direct rainfall and decreased potential evapotranspiration explain observed high mangrove AGB. Location Neotropics and a small portion of the Nearctic region. Methods A universal forest model based on site-level forest structure statistics was validated to spatially interpolate estimates of mangrove biomass at different locations. Linear models were then used to predict mangrove AGB across the Neotropics. Results The universal forest site-level model was effective in estimating mangrove AGB using pre-existing mangrove forest structure inventories to validate the model. We confirmed our hypothesis that at continental scales higher tidal amplitudes contributed to high forest biomass associated with high temperature and rainfall, and low potential evapotranspiration. Our model explained 20% of the spatial variability in mangrove AGB, with values ranging from 16.6 to 627.0 t ha−1 (mean, 88.7 t ha−1). Our findings show that mangrove AGB has been overestimated by 25-50% in the Neotropics, underscoring a commensurate bias in current published global estimates using site-level information. Main conclusions Our analysis show how the ESH significantly explains spatial variability in mangrove AGB at hemispheric scales. This finding is critical to improve and explain site-level estimates of mangrove AGB that are currently used to determine the relative contribution of mangrove wetlands to global carbon budgets. Due to the lack of a conceptual framework explicitly linking environmental drivers and mangrove AGB values during model validation, previous works have significantly overestimated mangrove AGB; our novel approach improved these assessments. In addition, our framework can potentially be applied to other forest-dominated ecosystems by allowing the retrieval of extensive databases at local levels to generate more robust statistical predictive models to estimate continental-scale biomass values. [ABSTRACT FROM AUTHOR]

Understanding the responses of lake systems to past climate change and human activity is critical for assessing and predicting the fate of lake carbon (C) in the future. In this study, we synthesized records of the sediment accumulation from 82 lakes and of C sequestration from 58 lakes with direct organic C measurements throughout China. We also identified the controlling factors of the long-term sediment and C accumulation dynamics in these lakes during the past 12 ka (1 ka = 1000 cal yr BP). Our results indicated an overall increasing trend of sediment and C accumulation since 12 ka, with an accumulation peak in the last couple of millennia for lakes in China, corresponding to terrestrial organic matter input due to land-use change. The Holocene lake sediment accumulation rate ( SAR) and C accumulation rate ( CAR) averaged (mean ± SE) 0.47 ± 0.05 mm yr−1 and 7.7 ± 1.4 g C m−2 yr−1 in China, respectively, comparable to the previous estimates for boreal and temperate regions. The SAR for lakes in the East Plain of subtropical China (1.05 ± 0.28 mm yr−1) was higher than those in other regions ( P < 0.05). However, CAR did not vary significantly among regions. Overall, the variability and history of climate and anthropogenic interference regulated the temporal and spatial dynamics of sediment and C sequestration for lakes in China. We estimated the total amount of C burial in lakes of China as 8.0 ± 1.0 Pg C. This first estimation of total C storage and dynamics in lakes of China confirms the importance of lakes in land C budget in monsoon-influenced regions. [ABSTRACT FROM AUTHOR]

Natural forests in South-East Asia have been extensively converted into other land-use systems in the past decades and still show high deforestation rates. Historically, lowland forests have been converted into rubber forests, but more recently, the dominant conversion is into oil palm plantations. While it is expected that the large-scale conversion has strong effects on the carbon cycle, detailed studies quantifying carbon pools and total net primary production (NPPtotal) in above- and belowground tree biomass in land-use systems replacing rainforest (incl. oil palm plantations) are rare so far. We measured above- and belowground carbon pools in tree biomass together with NPPtotal in natural old-growth forests, 'jungle rubber' agroforests under natural tree cover, and rubber and oil palm monocultures in Sumatra. In total, 32 stands (eight plot replicates per land-use system) were studied in two different regions. Total tree biomass in the natural forest (mean: 384 Mg ha−1) was more than two times higher than in jungle rubber stands (147 Mg ha−1) and >four times higher than in monoculture rubber and oil palm plantations (78 and 50 Mg ha−1). NPPtotal was higher in the natural forest (24 Mg ha−1 yr−1) than in the rubber systems (20 and 15 Mg ha−1 yr−1), but was highest in the oil palm system (33 Mg ha−1 yr−1) due to very high fruit production (15-20 Mg ha−1 yr−1). NPPtotal was dominated in all systems by aboveground production, but belowground productivity was significantly higher in the natural forest and jungle rubber than in plantations. We conclude that conversion of natural lowland forest into different agricultural systems leads to a strong reduction not only in the biomass carbon pool (up to 166 Mg C ha−1) but also in carbon sequestration as carbon residence time (i.e. biomass-C:NPP-C) was 3-10 times higher in the natural forest than in rubber and oil palm plantations. [ABSTRACT FROM AUTHOR]

In Malaysia, the main land change process is the establishment of oil palm plantations on logged-over forests and areas used for shifting cultivation, which is the traditional farming system. While standing carbon stocks of old-growth forest have been the focus of many studies, this is less the case for Malaysian fallow systems and oil palm plantations. Here, we collate and analyse Malaysian datasets on total carbon stocks for both above- and below-ground biomass. We review the current knowledge on standing carbon stocks of 1) different forest ecosystems, 2) areas subject to shifting cultivation (fallow forests) and 3) oil palm plantations. The forest ecosystems are classified by successional stage and edaphic conditions and represent samples along a forest succession continuum spanning pioneer species in shifting cultivation fallows to climax vegetation in old-growth forests. Total carbon stocks in tropical forests range from 4 to 384 Mg C/ha, significantly wider than the range of total carbon stocks of oil palm plantations, 2 to 60 Mg C/ha. Conversion of old-growth forest areas to oil palm plantations leads to substantial reduction in carbon storage, while conversion of forest fallows to oil palm plantations may sustain or even increase the standing carbon stock. [ABSTRACT FROM AUTHOR]

Central Asia has a land area of 5.6 × 106 km2 and contains 80-90% of the world's temperate deserts. Yet it is one of the least characterized areas in the estimation of the global carbon (C) stock/balance. This study assessed the sizes and spatiotemporal patterns of C pools in Central Asia using both inventory (based on 353 biomass and 284 soil samples) and process-based modeling approaches. The results showed that the C stock in Central Asia was 31.34-34.16 Pg in the top 1-m soil with another 10.42-11.43 Pg stored in deep soil (1-3 m) of the temperate deserts. They amounted to 18-24% of the global C stock in deserts and dry shrublands. The C stock was comparable to that of the neighboring regions in Eurasia or major drylands around the world (e.g. Australia). However, 90% of Central Asia C pool was stored in soil, and the fraction was much higher than in other regions. Compared to hot deserts of the world, the temperate deserts in Central Asia had relatively high soil organic carbon density. The C stock in Central Asia is under threat from dramatic climate change. During a decadal drought between 1998 and 2008, which was possibly related to protracted La Niña episodes, the dryland lost approximately 0.46 Pg C from 1979 to 2011. The largest C losses were found in northern Kazakhstan, where annual precipitation declined at a rate of 90 mm decade−1. The regional C dynamics were mainly determined by changes in the vegetation C pool, and the SOC pool was stable due to the balance between reduced plant-derived C influx and inhibited respiration. [ABSTRACT FROM AUTHOR]