Carbon Density Research Articles

Characteristics and Carbon Storage of a Typical Mangrove Island Ecosystem in Beibu Gulf, South China Sea

By studying the structural characteristics and carbon storage of the mangrove island ecosystem in the Beibu Gulf, this study provides a scientific basis for mangrove ecological compensation in the coastal areas of Guangxi, South China Sea. On the basis of the unmanned aerial vehicle remote sensing images and a sample plot survey, the object-oriented multi-scale segmentation algorithm is used to extract the mangrove community type information, and one-way analysis of variance is conducted to analyse the structural characteristics of the mangrove community. The carbon storage and carbon density of different mangrove ecosystems were obtained based on the allometric growth equation of mangrove plants. The analysis yielded four main results. (1) The island group covers about 27.10 ha, 41.32% (11.20 ha) of which represents mangrove areas. The mangrove forest is widely distributed in the tidal flats around the islands. (2) The main mangrove types were Aegiceras corniculatum, Kandelia obovata + Aegiceras corniculatum, Avicennia marina + Aegiceras corniculatum and Avicennia marina communities. (3) Amongst the mangrove plants, Avicennia marina had the highest biomass (18.52 kg plant–1), followed by Kandelia obovata (7.84 kg plant–1) and Aegiceras corniculatum (3.85 kg plant–1). (4) The mangrove carbon density difference was significant. Kandelia obovata had the highest carbon density (148.03 t ha–1), followed by Avicennia marina (104.79 t ha–1) and Aegiceras corniculatum (99.24 t ha–1). The carbon storage of the mangrove island ecosystem was 1194.70 t, which was higher than in other areas with the same latitude. The carbon sequestration capacity of the mangrove was relatively strong.

Stress-assisted design of stiffened graphene electrode structure toward compact energy storage

The low spatial charge-storage density of porous carbons greatly limits volumetric performance in electrochemical capacitors. An increase of charge-storage density requires structural refinements to balance the trade-offs between the porosity and density of materials, but the limited mechanical properties of carbons usually fail to withstand effective densifying processes and obtain an ideal pore structure. Herein, we design the stiffened graphene of superior bending rigidity, enabling the fine adjustments of pore structure to maximize the volumetric capacitance for the graphene-based electrodes. The in-plane crumples on graphene sheets are found to contribute largely to the bending rigidity, which is useful to control the structural evolution and maintain sufficient ion-accessible surface area during the assembling process. This makes the capacitance of stiffening activated graphene keep 98% when the electrode density increases by 769% to reach 1.13 g cm−3 after mechanical pressure, an excellent volumetric energy density of 98.7 Wh L-1 in an ionic-liquid electrolyte is achieved. Our results demonstrate the role of intrinsic material properties on the performance of carbon-based electrodes for capacitive energy storage.

Wildfire drives the transition from deterministic- to stochastic-dominated community assembly of abundant bacterial in forest soils

Wildfires are ecological disturbances that shift soil microbes and the ecosystem functions they drive in forests. The temporal dynamics and assembly processes of the bacterial community following fire are essential but remain unknown. This study aimed to investigate how the assembly processes and their associated factors mediate the abundant and rare bacterial communities across temporal trajectories (21 months from 2019 to 2020) in severely burned and contiguous unburned forest soils. Results revealed that the temporal turnover rate of abundant sub-community in unburned soils was lower than that of rare sub-community, and abundant taxa exhibited a wider niche breadth than rare taxa; null model analyses indicated that variable selection made a paramount contribution to bacterial community assembly, with stronger phylogenetic clustering of the rare taxa; soil ammonium nitrogen and pH were the most decisive factor for community assembly of abundant and rare taxa, as evidenced by how divergences in them decreased the proportion of stochasticity. Compared with the unburned soils, the temporal turnover of the soil bacterial community was accelerated in burned soils; moreover, determinism had more important roles in rare taxa, whereas the abundant taxa were primarily dominated by dispersal limitation; soil dissolved organic carbon and bulk density regulated the balance between deterministic and stochastic assembly of the abundant and rare bacteria, respectively. Overall, these findings suggested distinct community assembly of abundant taxa in burned and unburned forest soils, which is of great significance to understand the establishment and maintenance mechanism of the soil bacterial community in forests following wildfire.

Planted forest is catching up with natural forest in China in terms of carbon density and carbon storage

Over the last several decades, China has taken multiple measures for afforestation and natural forest protection, including setting the goal of carbon neutrality by the middle of 21th century. In order to support the practice of relevant policies from the scientific perspective, it is essential to precisely estimate the carbon storage of arbor forest, as it plays an important role in the carbon cycle of ecosystems. In this study, we first used the latest four phases of national forest inventory data to investigate the variation of carbon storage for both natural and planted arbor forest in China during the covered period (1999-2018). Then we used machine leaning methods to simulate the carbon density based on various kinds of environmental factors and analyzed the contribution of each influencing factor. Our results demonstrate that the total carbon storage for arbor forest in China kept increasing over the last two decades, but this increment was mainly brought about by the continuous expansion of forest land. The gap of carbon sequestration between natural forest and planted forest showed a significant trend of reduction. Additionally, tree age was identified as the dominant factor for influencing the spatiotemporal variation of carbon density among all the independent variables while the impact of climatic factor was limited. Therefore, the future improvement of carbon sequestration of arbor forest in should mainly rely on additional projects of afforestation, reforestation, green space conservation and reduction of emissions in China. Conclusions of this study have important implications for policy makers and other stakeholders to evaluate the previous achievement of environmental projects and can also help to set future plans and finally realize the goals of carbon neutrality.

Net carbon flux from cropland changes in the Central Asian Aral Sea Basin

The transboundary Aral Sea Basin (ASB) covers parts of the former Union of Soviet Socialist Republics (USSR), the central Asian portion of Kazakhstan (KAZ), Uzbekistan (UZB), Turkmenistan (TUK), Kyrgyzstan (KGZ), and Tajikistan (TAJ). During recent decades, the region has experienced widespread cropland changes and has therefore attracted attention. However, carbon flux caused by these changes, which is critical to understand the carbon cycle in the region and to develop strategies for carbon sequestration, has not been quantified. We applied the Bookkeeping Model to analyze carbon flux caused by cropland changes. We found that the cropland area expanded from 1975 to 2019. Prior to 1990, the net increment in cropland area was 64.47 kha yr−1; this decreased to 11.02–18.69 kha yr−1 after the collapse of the USSR (1991). Grasslands and bare lands with low carbon density were the main types of land that were converted to cropland, accounting for approximately 70.3–99.29% of the land cleared for cropland. In terms of cropland loss, grassland accounted for more than 40.69% of the cropland converted to other land cover types, followed by artificial surfaces, which accounted for 25.84–45.16%. The expansion of cropland served as a carbon sink owing to the increase in irrigation and fertilization. The overall potential carbon emission was −89.38 ± 35.34 Tg C, and contributions of the five countries were as follows: TUR (−33.65 ± 6.30 Tg C), UZB (−29.23 ± 25.35 Tg C), KAZ (−12.76 ± 12.16 Tg C), TAJ (−11.11 ± 5.47 Tg C), KGZ (−2.63 ± 7.83 Tg C). The net carbon flux was −2.04 ± 0.23 Tg C yr−1 before 1990, and it decreased to −1.87 ± 1.03 Tg C yr−1 during the post-Soviet era. Finally, we state sustainable agricultural management is urgently needed to deal with the environmental problems of the Aral Sea, which have been primarily caused by cropland expansion.

Ecosystem organic carbon storage and their drivers across the drylands of China

Earth’s drylands store large amounts of organic carbon and thus play an important role in regulating atmospheric CO2 concentrations and mitigating climate change. However, little is known about the magnitude and the drivers of organic carbon stocks because of limited data, in particular in desert ecosystems. To fill this gap, we surveyed 763 plots and collected 5091 soil samples from 170 sites covering grassland and desert ecosystems across the drylands of China. The results show that 10.96 Pg organic carbon is stored in these ecosystems (7.07 Pg in grasslands and 3.89 Pg in deserts). The effects of environmental variables on carbon density were found to be contingent on ecosystem type and soil depth. Mean annual precipitation had a strong positive effect on the spatial distributions of vegetation carbon density in both types of ecosystems. The spatial variations of surface (0–40 cm) and subsurface (40–100 cm) soil organic carbon (SOC) density in grasslands were mainly correlated with plant productivity and mean annual temperature (MAT), respectively, while in desert ecosystems, they were mainly correlated with soil salinity (electrical conductivity). The spatial sensitivities (linear regression slopes) of the surface SOC density versus MAT increased from dry subhumid to semi-arid regions and then gradually shifted to decrease from semi-arid to hyper-arid regions, indicating that the surface SOC stock is more sensitive to temperature in semi-arid regions. This study provides a comprehensive survey of ecosystem carbon stocks in China’s drylands, fills a gap in our knowledge about carbon stocks in deserts, complements estimates of ecosystem carbon stocks throughout China, and provides insights into our understanding of the carbon cycle in drylands.

Aboveground carbon accumulation by second‐growth forests after deforestation in Hawai'i

Successional processes ultimately determine and define carbon accumulations in forested ecosystems. Although primary succession on wholly new substrate occurs across the globe, secondary succession, often following storm events or anthropogenic disturbance, is more common and is capable of globally significant accumulations of carbon (C) at a time when offsets to anthropogenic carbon dioxide (CO2 ) emissions are critically needed. In Hawai'i, prior studies have investigated ecosystem development during primary succession on lava flows, including estimates of C mass accumulation. Yet relatively little is known regarding secondary succession of Hawaii's native forests, particularly regarding C mass accumulation. Here we documented aboveground C mass accumulation by native- and nonnative-dominated second-growth forests following deforestation of mature native lowland rainforests in the Puna District of Hawai'i Island. We characterized species composition and stand structure of three distinct successional forest stand types: those dominated by the native tree, Metrosideros polymorpha ('Ōhi'a), and those dominated by invasive nonnative trees, Falcataria moluccana (albizia) and Psidium cattleianum (strawberry guava). We compared M. polymorpha-dominated and F. moluccana-dominated second-growth forests to adjacent mature M. polymorpha-dominated forests as well as young M. polymorpha-dominated forests undergoing initial stages of primary succession on 36-years-old lava fields. Aboveground carbon density (ACD) values of mature primary forest stands (171 Mg/ha) were comparable to those of mature continental tropical forests. M. polymorpha-dominated second-growth stands attained nearly 50% of ACD values of mature primary forests after less than 30 years of post-disturbance succession and exhibited aboveground carbon accumulation rates of ~3 Mg C·ha-1 ·year-1 . Such rates were comparable to those of second-growth forests in continental tropics. Rates of ACD accumulation by second-growth forests dominated by nonnative F. moluccana stands were similar, or slightly greater than, those of M. polymorpha-dominated stands. However, M. polymorpha individuals were virtually absent from stands dominated by either P. cattleianum or F. moluccana. Taken together, results demonstrated that re-establishment and rapid accumulation of C mass by M. polymorpha stands during secondary succession is certainly possible, but only where populations of nonnative species have not already colonized areas during early stages of secondary succession.

Enhancement the Properties of Local Crude Oil using DE-asphalting Process

Asphaltene precipitation is one of the main hitches in the oil sector through the production and refining stages that causes real damages every year. The object of the present work is to study the effect of the deasphalting process of crude oils using different concentrations (5, 10, and 15 wt.%) of n-heptane as a solvent, the experiments were done at a laboratory scale. The deasphalting process quality was based on the sulfur content, conradson carbon residue, density, API, and kinematic viscosity. The results have been shown that the deasphalting process quality was enhanced with increasing weight fraction of added n-heptane, the API value and kinematic viscosity were increased by about 37 and 19.5% respectively, while the density, conradson carbon residue, and sulfur content were decreased by about 5, 17 and 26.8% respectively when 15 wt.% of n-heptane was used, i.e. , the quality of deasphalting methods was enhanced with increased solvent concentrations.

Beyond habitat boundaries: Organic matter cycling requires a system‐wide approach for accurate blue carbon accounting

AbstractAs coastal ecosystems become widely recognized for their capacity to sequester carbon (blue carbon), standard accounting methodologies for the generation of carbon credits are being developed. To ensure the applicability of these standards across blue carbon ecosystems, we investigated organic carbon provenance and burial in salt marshes and seagrass meadows of an arid, upwelling‐dominated Eastern Pacific lagoon. We found low carbon density in benthic sediments of Bahía de San Quintín (5.9 ± 0.5 mg C cm−3), only marginally higher in Zostera marina beds (6.9 ± 0.5 mg C cm−3), likely due to remineralization and hydrodynamically driven export of seagrass material, resulting in low carbon burial rates (4.5 ± 2.5 g C m−2 yr−1). Sediment organic carbon is mainly controlled by the fraction of fine sediment and its source is largely allochthonous, although sources differ spatially. Salt marshes at San Quintín derive 40% of their organic matter from autochthonous material and exhibit higher carbon burial rates (up to 414.7 ± 28.6 g C m−2 yr−1) and sediment carbon densities (32.0 ± 0.7 mg C cm−3) compared to benthic sediments. This study emphasizes the connectivity of blue carbon habitats with marsh plant detritus supplementing benthic carbon burial and incorporation of detrital eelgrass in marsh sediments. Our findings highlight the importance of allochthonous organic matter for carbon sequestration in blue carbon habitats, suggesting standard accounting practices that deduct allochthonous organic matter would miss the full potential for carbon burial.

Urban soil management in the strategies for adaptation to climate change of cities in the Tropical Andes

The unique characteristics of a city amplify the impacts of climate change; therefore, urban planning in the 21st century is challenged to apply mitigation and adaptation strategies that ensure the collective well-being. Despite advances in monitoring urban environmental change, research on the application of adaptation-oriented criteria remains a challenge in urban planning in the Global South. This study proposes to include urban land management as a criterion and timely strategy for climate change adaptation in the cities of the Tropical Andes. Here, we estimate the distribution of the soil organic carbon stock (OCS) of the city of Quito (2,815 m.a.s.l.; population 2,011,388; 197.09 km2) in the following three methodological moments: i) field/laboratory: city-wide sampling design established to collect 300 soil samples (0–15 cm) and obtain data on organic carbon (OC) concentrations in addition to 30 samples for bulk density (BD); ii) predictors: geographic, spectral and anthropogenic dimensions established from 17 co-variables; and iii) spatial modeling: simple multiple regression (SMRM) and random forest (RFM) models of organic carbon concentrations and density as well as OCS stock estimation. We found that the spatial modeling techniques were complementary; however, SMRM showed a relatively higher fit both (OC: r2 = 20%, BD: r2 = 16%) when compared to RFM (OC: r2 = 8% and BD: r2 = 5%). Thus, soil carbon stock (0–0.15 m) was estimated with a spatial variation that fluctuated between 9.89 and 21.48 kg/m2; whereas, RFM showed fluctuations between 10.38 and 17.67 kg/m2. We found that spatial predictors (topography, relative humidity, precipitation, temperature) and anthropogenic predictors (population density, roads, vehicle traffic, land cover) positively influence the model, while spatial predictors have little influence and show multicollinearity with relative humidity. Our research suggests that urban land management in the 21st century provides key information for adaptation and mitigation strategies aimed at coping with global and local climate variations in the cities of the Tropical Andes.

Dynamics of carbon pool in Oak dominated community forests of District Tehri Garhwal, Uttarakhand, India

The present study was carried out community forest of Tehri Garhwal Uttarakhand. The amount of growing stock volume density in the study region were ranges between 28.21 m3/ha and 44.59 m3/ha, above-ground biomass density ranges between 200.59 Mg ha-1 and 238.44 Mg ha-1, belowground biomass density range between 128.03 and 192.96 Mg/ha, total biomass density was in the range of 287.76 and 431.40 Mg ha-1 and total carbon density ranges between 162.40 and 194.13 Mg ha-1. The isolation of total biomass density into aboveground and belowground parts showed a similar pattern in every one of the forest locales. Present study proposes that community forests play a vital role in ecosystem health they are playing their job quietly in the moderation of environmental carbon and crucial for future planning. Loss of old community forestry system is centre for concern to the forest department, forest rangers and forestry researchers. Protection of community forests is an urgent need for the maintenance of community ecosystem in temperate region of Garhwal Himalaya Uttarakhand. Preservation of the both young and old growth forests is the best way to adapt to environmental change and a worldwide temperature alteration. As we probably are aware the pattern of old cultivating in the networks close to the urban communities is decrease and will be supplanted by present day procedures so we need to look through some new strategy and execution to monitor the old cultivating methods. The ground stock volume density shows moderate positive correlation with altitude (r =0.325) while above ground biomass density (r = 0.203) below ground biomass density, total biomass density and total carbon density shows week positive correlation with altitude (r =0.117, r = 0.194 and r = 0.194 respectively). The Linear regression shows that ground stock volume density, above ground biomass density, below ground biomass density, total biomass density and total carbon density not dependent only altitude some other factor affecting them. While as above ground biomass density show highly positive correlation with total biomass density and total carbon density whereas altitude show less positive correlation with below ground biomass density).

Combining Sample Plot Stratification and Machine Learning Algorithms to Improve Forest Aboveground Carbon Density Estimation in Northeast China Using Airborne LiDAR Data

Timely, accurate estimates of forest aboveground carbon density (AGC) are essential for understanding the global carbon cycle and providing crucial reference information for climate-change-related policies. To date, airborne LiDAR has been considered as the most precise remote-sensing-based technology for forest AGC estimation, but it suffers great challenges from various uncertainty sources. Stratified estimation has the potential to reduce the uncertainty and improve the forest AGC estimation. However, the impact of stratification and how to effectively combine stratification and modeling algorithms have not been fully investigated in forest AGC estimation. In this study, we performed a comparative analysis of different stratification approaches (non-stratification, forest type stratification (FTS) and dominant species stratification (DSS)) and different modeling algorithms (stepwise regression, random forest (RF), Cubist, extreme gradient boosting (XGBoost) and categorical boosting (CatBoost)) to identify the optimal stratification approach and modeling algorithm for forest AGC estimation, using airborne LiDAR data. The analysis of variance (ANOVA) was used to quantify and determine the factors that had a significant effect on the estimation accuracy. The results revealed the superiority of stratified estimation models over the unstratified ones, with higher estimation accuracy achieved by the DSS models. Moreover, this improvement was more significant in coniferous species than broadleaf species. The ML algorithms outperformed stepwise regression and the CatBoost models based on DSS provided the highest estimation accuracy (R2 = 0.8232, RMSE = 5.2421, RRMSE = 20.5680, MAE = 4.0169 and Bias = 0.4493). The ANOVA of the prediction error indicated that the stratification method was a more important factor than the regression algorithm in forest AGC estimation. This study demonstrated the positive effect of stratification and how the combination of DSS and the CatBoost algorithm can effectively improve the estimation accuracy of forest AGC. Integrating this strategy with national forest inventory could help improve the monitoring of forest carbon stock over large areas.

Spatial variation of soil organic carbon in the Qinghai Lake watershed, northeast Qinghai-Tibet Plateau

Soil organic carbon (SOC) on the Qinghai-Tibet plateau is of global significance, due to the high carbon density and potential positive feedbacks to climate warming. Qinghai Lake watershed is an important soil pool in Qinghai-Tibet plateau, but the magnitude and characteristics of SOC stock in the high-altitude basin were not clear. To understand better how much SOC was stored and its spatial patterns in the watershed, this study analyzed the vertical variation of SOC content, quantified its influence by varied environmental factors, and further predict its storage in the entire basin. Results showed that, the SOC content decreased with the increasing depth, and was the highest in the alpine meadow in all depths, following by the alpine steppe and temperate steppe, respectively. It was generally higher in the permafrost region than that in the non-permafrost region at all depths. Soil profile depth, soil water content and NDVI could together explain about 72.6% of total variation in SOC density. The regression-kriging method was the best upscaling approach for the prediction of SOC in the study area. Approximately 317 Tg organic carbon was stored in the entire soil profile of Qinghai Lake watershed, in which 136, 140, and 41 Tg were at 0–30 cm, 30–100 cm, and below 100 cm, respectively. The higher SOC density mainly appeared on the northeast and southern region of Qinghai Lake, while the high-altitude area in the northwest of the watershed had the lower values. Moreover, it increased firstly and then decreased with the increase of altitude, with the maximum values at 3350–3400 m, which was dominated by the elevational variation of soil profile depth and NDVI. Overall, the comprehensive assessment of SOC demonstrated high storage and strong heterogenicity of soil carbon in the Qinghai Lake watershed, and it is critical for the sustainability of regional terrestrial ecosystem with future climate change.

Effects of forest fire disturbance on carbon density of eucalyptus forest ecosystem in Guangdong Province

Forest fire, as a discontinuous ecological factor of forest, causes the changes of carbon storage and carbon distribution in forest ecosystem, and affects the process of forest succession and national carbon capacity. Taking the burned land with different forest fire interference intensity as the research object, using the comparison method of adjacent sample plots, and taking the combination of field investigation sampling and indoor test analysis as the main means, this paper studies the influence of different forest fire interference intensity on the carbon pool of forest ecosystem and the change and spatial distribution pattern of ecosystem carbon density, and discusses the influence mechanism of forest fire interference on ecosystem carbon density and distribution pattern. The results showed that forest fire disturbance reduced the carbon density of vegetation (P < 0.05). The carbon density of vegetation in the light, moderate and high forest fire disturbance sample plots were 67.88, 35.68 and 15.50 t∙hm-2, which decreased by 15.86%, 55.78% and 80.79% respectively compared with the control group. In the light, moderate and high forest fire disturbance sample plots, the carbon density of litter was 1.43, 0.94 and 0.81 t∙hm-2, which decreased by 28.14%, 52.76% and 59.30% respectively compared with the control group. The soil organic carbon density of the sample plots with different forest fire disturbance intensity is lower than that of the control group, and the reduction degree gradually decreases with the increase of soil profile depth. The soil organic carbon density of the sample plots with light, moderate and high forest fire disturbance is 103.30, 84.33 and 70.04 t∙hm-2 respectively, which is 11.670%, 27.899% and 40.11% lower than that of the control group respectively; the carbon density of forest ecosystem was 172.61, 120.95 and 86.35 t∙hm-2 after light, moderate and high forest fire disturbance, which decreased by 13.53%, 39.41% and 56.74% respectively compared with the control group; forest fire disturbance reduced the carbon density of eucalyptus forest, which showed a law of carbon density decreasing with the increase of forest fire disturbance intensity. Compared with the control group, the effect of light forest fire disturbance intensity on the carbon density of eucalyptus forest was not significant (P > 0.05), while the effect of moderate and high forest fire disturbance intensity on the carbon density of eucalyptus forest was significant (P < 0.05).

Current and future carbon stocks of natural forests in China

Natural regeneration of forests is the most cost-effective and most technically straightforward strategy to mitigate climate change. Natural forests account for 71% of China’s forested area, but their carbon stocks and sequestration potentials remain unclear. Here, we compiled data from 762 natural forest sites across China and found that natural forests had a carbon stock of 9.40 ± 1.45 Pg C in 2010. When naturally regenerated to the over-mature stage, existing natural forests can additionally sequestrate 8.67 ± 6.93 Pg C in the next two centuries, accounting for 48% of the carbon carrying capacity of the natural forest ecosystem in China, i.e. 18.07 ± 6.78 Pg C. Future carbon sequestration potential in natural forests is dominated by the tree layer at 6.88 ± 6.87 Pg, followed by the shrub layer at 1.02 ± 0.55 Pg, floor layer at 0.72 ± 0.74 Pg and herb layer at 0.05 ± 0.10 Pg. The natural forests are expected to achieve 70% of their future carbon sequestration potential by 2100. We also note that assisted regeneration via tree planting can play a significant role in natural forest restoration, as the carbon densities of natural and planted forests are rarely significantly different at the same age under 60 years old. Therefore, the preservation and expansion of natural forests is the key strategy for achieving long-term carbon sequestration.

Variation in carbon stock and soil properties in different Quercus leucotrichophora forests of Garhwal Himalaya

Oak (Q. leucotrichophora) are the oldest forest in temperate region of Himalaya and grow in wide altitudinal ranges. Oak provides various ecosystem services and conserved soil and water and sustained the Himalayan agriculture for subsistence including storing and sequestering CO2. The Oak forests fulfill the needs of the Himalayan people and therefore the potential of carbon storage changes accordingly of the forests in different altitudes. Thus; the present study was conducted to investigate the variation in carbon stock and soil properties in five different oak forest sites of Pauri and Tehri districts of Uttarakhand, Himalaya. Three sample plots were laid out randomly on each site (each of a size of 0.1 ha) for the measurements of tree height, diameter and collecting soil samples. The results of the study showed that the maximum volume, biomass and carbon density of trees were recorded in the Bharsar site. The values of biomass, carbon and density parameters were recorded significant (p < 0.05) at different altitudes of study sites. The soil in all the studied sites were rich in nutrients, where, the maximum values of pH (5.6), soil organic carbon (1.95%), reported in Lansdowne, available nitrogen (217.38 kg/ha) in Chandrabadni and available phosphorus (98.04 kg/ha) in Chopariyal area. The results suggested that the forest site of Bharsar has good capacity of storing biomass and carbon stock in trees and Lansdowne site accumulating higher amount of carbon in the soil compared to other sites. However, it is concluded that, for better conditions of these forests for soil and carbon storing potential, forest needs good management practices, especially in community forests areas to avoid illegal felling, impact of fire, overexploitation of fuel and fodder. The good management practices would be helpful in mitigating the impact of climate change and sustainable outcome of the resources for the community benefits.

Community Managed Protected Areas Conserve Aboveground Carbon Stocks: Implications for REDD+

Protected Areas (PAs) represent a broad spectrum of outcomes and governance systems. Among PAs, Community Managed PAs have emerged from communities that are not exclusively indigenous and have developed social organizations to acquire land rights, participate in forest governance, and in some cases, engage in REDD+. However, regardless of the scale or counterfactual, there is no clear consensus about Community Managed PAs’ effectiveness in forest conservation and climate change mitigation. Furthermore, previous studies have been devoted to estimating PAs’ effects on deforestation before REDD+ projects began to operate. Based on Community Concessions in Petén (Guatemala) and Extractive Reserves in Acre (Brazil), we analyzed Community Managed PAs’ temporal and spatial effects on carbon stocks and avoided emissions relative to unprotected lands, other Sustainable Use PAs (IUCN V-VI), and Strict PAs (I-IV). We used carbon density maps, matching methods, geographic discontinuity designs, and sensitivity analysis between 2003 and 2015. After controlling for the influence of market access and agriculture suitability, our analysis shows that Community Managed PAs were more effective than Other Lands (i.e., unprotected) and Sustainable Use PAs, and at least as effective as Strict PAs, in preserving carbon stocks and avoiding emissions. For instance, relative to Other Lands between 2011 and 2015, Community Managed PAs resulted in net avoided emissions of 4.6 tCO2-eq/ha in Petén (Guatemala) and 2.15 tCO2-eq/ha in Acre (Brazil). While these net avoided emissions were lower than in previous years, they seem to be driven by a reduction in carbon emissions outside Community Managed PAs. Spatially, the boundaries of Community Managed PAs varied across jurisdictions. For example, the boundaries of Acre’s Community Managed PAs’ have become less effective in avoiding emissions, which translates into reduced effects on conserving carbon stocks. Our results highlight the need to assess temporal effects to exhibit jurisdiction-wide land-use dynamics and spatial effects to identify local land-use pressures emerging inside or around the boundaries of PAs. Our analysis also shows that decentralized governance in Community Managed PAs may contribute to climate change mitigation through REDD+ and forest conservation targets.

Biomass distribution pattern and stoichiometric characteristics in main shrub ecosystems in Central Yunnan, China.

BackgroundWith the exacerbating effects of the global climate change and the more and more attention to the study of plant carbon sink, an increasing number of researches on plant carbon sinks has grown. Although many studies exist on shrub vegetation, soil and litters, most studies focus on the community structure, biomass, surface soil of single plant and shrub layer vegetation, and lack the studies which included the potential relationships between climate change and ecological stoichiometric elements, comprehensive research on main species, even herb and litter layer. In order to provide relevant theoretical basis and data support, it is necessary to take the main terrestrial shrub ecosystem in Central Yunnan as the starting point to analyze and explore its carbon sink distribution characteristics, formation causes, the correlation between climatic factors (temperature and precipitation) and stoichiometric elements, which from community and species levels.MethodsPlants which originated from 12 main shrub species, litter and soil samples which collected in 69 plots were from 23 plots (Q1–Q23) of 11 cities (countries) in the central Yunnan, China. The biomass and carbon density distribution pattern of each shrub ecosystem and the potential correlations with main climate factors was explored and identified. Some indexes were analyzed such as biomass and carbon density of each part of the shrub ecosystem distribution pattern, correlation, significant changes, formation reasons with the mean value (±standard deviation: SD). Through the redundancy analysis(RDA) of carbon (c), nitrogen (n), phosphorus (P) and main climate factors (precipitation and temperature), the distribution pattern of stoichiometric elements in shrub ecosystem can be judged.Results(1) The above-ground biomass (AGB), under-ground biomass (UGB) and root-shoot ratio (R/S) were between 1.13–2.03 t/hm2, 0.62–1.49 t/hm2, and 0.38–0.84, the carbon element was distributed in herb layer under-ground part and rhizomes of the shrub layer mostly. (2) The fitting slope of AGB and UGB of shrub communities and species was in accordance with the allometric distribution growth relationship, the R/S of shrubs was smaller than other vegetation types. Mean annual temperature (MAT) and mean annual precipitation (MAP) are not the main factors which affect the biomass and R/S. (3) The contents of C, N and P elements in leaves were significantly higher than other parts in shrub layer. P in shrub layer above-ground part is much higher than under-ground part. The surface soil layer has the highest C content, and decreased with the depth, so as the impact of vegetation and litter on the content of soil elements. Both of the correlation of MAT with N content of leaf, C/N of stem, the correlation of MAP with C content, C/N of soil is the greatest.

Land use and land cover change influence on soil organic carbon content for a pastoral area: use of geographical information system

Data on land use and cover change and soil organic carbon (SOC) in rangelands are essential. This is because rangelands ecosystems are fragile, and poor land-use practices can significantly threaten their sustainability by depleting SOC and increasing atmospheric carbon dioxide. This study investigated soil organic carbon variations as influenced by land use/land cover changes in the unprotected area of the Sanga agropastoral ecosystem, southwestern Uganda. Landsat images provided data for land use and cover for 1987 and 2020. Soil organic carbon contents were investigated in farmland (FL), grassland (GL), woodland (WL), and bare land (BL) as control at 0-15 cm and 15-30 cm depths. Soil samples were analyzed for organic carbon and bulk density using the colorimetric and core ring methods, respectively. Total soil organic carbon content was significantly high in grassland (31.55 Mg C ha-1), p=0.005, and woodland (27.89 Mg C ha-1), p=0.028 compared to bare land (16.17 Mg C ha-1). Additionally, total soil organic carbon concentration in grassland (2.10%) was higher than SOC concentration in farmland (1.39%) p=0.001 and bare land (1.00%), p&lt;0.001, respectively. Similarly, woodlands soil organic carbon concentration (1.98%) was higher than soil organic concentrations in bare lands, p=0.003 and farmlands, p=0.028. Bulk density was significantly different at lower horizons, with farmland having a higher bulk density than other land use types, p=0.013. Roots and litter inputs in woodlands and grasslands contributed to higher organic carbon than farmland and eroded/bare lands. Cultivation also increased the soil bulk density. This study concludes that land use and the land cover change affected soil organic carbon sequestration and bulk density. Therefore, farmers need to increase farm management practices to avoid an increase in bulk density. Further study to compare the effects of grazing intensity on SOC and modeling future SOC content in the study area is recommended.

Fine-Scale Improved Carbon Bookkeeping Model Using Landsat Time Series for Subtropical Forest, Southern China

Subtropical forests easily suffer anthropogenic disturbance, including deforestation and reforestation management, which both highly affect the carbon pools. This study proposes spatial-temporal tracking of the carbon density dynamics to improve bookkeeping in the carbon model and applied to subtropical forest activities in Guangzhou, southern China, during the period of 1995 to 2014. Based on the overall accuracy of 87.5% ± 1.7% for forest change products using Landsat time series (LTS), we found that this is a typical period of deforestation conversion to reforestation activity accompanied with urbanization. Additionally, linear regression, random forest regression and allometric growth fitting were proposed by using forest field plots to obtain reliable per-pixel carbon density estimations. The cross-validation (CV) of random forest with LTS-derived parameters reached the highest accuracy of R2 and RMSE of 0.763 and 7.499 Mg ha−1. The RMES of the density estimation ranged between 78 and 84% of the mean observed biomass in the study area, which outperformed previous studies. Over the 20-year period, the study results showed that the explicit carbon emissions were (6.82 ± 0.26) × 104 Mg C yr−1 from deforestation; emissions increased to (1.02 ± 0.04) × 105 Mg C yr−1 given the implicit carbon not yet released to the atmosphere in the form of decomposing slash and wood products. In addition, a carbon uptake of about 1.91 ± 0.73 × 105 Mg C yr−1, presented as the net carbon pool. Based on the continuous detection capability, biennial reforestation activity has increased carbon density by a growth rate of 1.55 Mg ha−1, and the emission factors can be identified with LTS-derived parameters. In general, the study realizes the spatiotemporal improvement of carbon density and flux dynamics tracking, including the abrupt and graduate change based on fine-scale forest activity. It can provide more comprehensive and detailed feedback on the carbon source and sink change process of forest activities and disturbances.