Ecosystem Carbon Stocks Research Articles

Soil fungal guilds as important integrators linking plant richness and carbon, nitrogen and phosphorus stocks in oasis–desert ecosystems

Plant richness strongly affects ecosystem functions, especially ecosystem carbon and nutrients stocks. However, the mechanisms underlying positive richness–stock relationships remain uncertain. Plant–fungus linkages play crucial roles in modulating stocks of terrestrial ecosystems, but empirical evidence regarding the integration of soil fungal guilds into positive richness–stock relationship under natural conditions is still lacking. Here, observations from 81 plots along a natural plant richness gradient in oasis–desert ecosystems were used to assess the role of diversity within particular soil fungal guilds in integrating the associations of plant richness with vegetation and topsoil (0–30 cm) carbon (C), nitrogen (N) and phosphorus (P) stocks. We observed that plant richness has positive associations with vegetation and topsoil C, N and P stocks in oases and deserts. Mycorrhizal fungal abundance showed consistent and positive associations with plant richness and vegetation and topsoil C, N and P stocks in the oasis after accounting for groundwater, soil factors and soil enzyme activities, whereas similar patterns were found for saprotrophic fungal abundance in the desert. We further demonstrated mycorrhizal and saprotrophic fungal abundance as important integrators of the positive richness–stock relationships in oases and deserts, respectively. Moreover, guild-level fungal abundance surpasses whole fungal community attributes in linking plant richness and stocks in oases and deserts. The present study provides real-world evidence supporting the crucial roles of fungal functional groups diversity in integrating the positive associations of plant diversity with ecosystem C and nutrients stocks in oasis–desert ecosystems. By unravelling the importance of fungi for ecosystem C and nutrients stocks, our work emphasises that ecosystem restoration should consider not only plant richness to enhance ecosystem C and nutrients stocks but also the roles of key fungal groups.

Influence of Anthropogenic Activities on Forest Carbon Stocks—A Case Study from Gori Valley, Western Himalaya

Carbon stock assessment in various ecosystems is vital for monitoring the health of these ecosystems and national accounting for the United Nations convention on climate change. The influence of various anthropogenic drivers on carbon stock in different ecosystems has not been examined comprehensively. This study aims to determine the impact of anthropogenic pressures (lopping, cutting, grazing) on soil physico-chemical properties and carbon stock in four temperate broadleaf forests dominated by different species of oak, viz., Banj oak (Quercus leucotrichophora), Rianj oak (Quercus lanuginosa), Moru oak (Quercus floribunda) and Kharsu oak (Quercus semecarpifolia) along an elevation gradient from 1700–3000 m asl in Gori valley, western Himalaya. Biomass data were collected from 120 quadrats of 10 × 10 m size at three distinct altitudes (4 forest sites × 3 altitudes × 10 quadrats) and analysed for carbon stock, whereas soil samples were randomly collected in triplicate from three depths of each altitude of the forest site and further analysed for their physico-chemical properties. A total of 767 individual trees with a diameter of ≥31 cm were measured at twelve sites and standing biomass was estimated following the growing stock volume equations. Mean carbon stock was highest in Moru oak (396.6 ± 29.5 Mg C ha−1) and lowest in Banj oak forest (189.3 ± 48.6 Mg C ha−1). We also found soil to be the largest pool of forest carbon (43.0–59.7%) followed by aboveground biomass (31.5–45.0%), belowground biomass (8.4–11.7%) and litter (0.4–0.5%). The basal area showed significant effect on altitude and carbon stock, whereas disturbance showed significant (p < 0.05) negative correlation with the total carbon stock. Soil nitrogen exhibited a significant positive correlation (R2 = 0.60) with the basal area, indicating that nitrogen enhances tree growth and forest carbon stock. However, anthropogenic disturbance showed a significant negative impact on the basal area, soil nutrients and carbon stock of oak forests. This concludes that forest structure, anthropogenic pressure and soil parameters contribute to the carbon stock of the area. Considering the significance of these overexploited oak forests, it is recommended to conserve the old-growth forest species in the study area, since they have the highest carbon accumulation potential.

Response of Soil Organic Carbon Stock to Bryophyte Removal Is Regulated by Forest Types in Southwest China

Bryophytes play an important role in biogeochemical cycles and functions in forest ecosystems. Global climate changes have led to the population decline of bryophytes; however, the effects of bryophyte loss on the soil organic carbon stock and microbial dynamic remain poorly understood. Here, bryophytes were artificially removed to simulate the loss of bryophytes in two forests in Southwest China, i.e., evergreen broad-leaved forest and temperate coniferous forest. Soil physicochemical properties, microorganisms, and soil organic carbon stocks were analyzed and factors regulating soil organic carbon stocks were explored. Results showed that bryophyte removal significantly decreased soil organic carbon in the coniferous forest but had a negligible effect on the evergreen broad-leaved forest. Bryophyte removal had an insignificant effect on soil properties and microbial PLFAs except that soil nitrogen significantly increased in the 0–10 cm layer in the evergreen broad-leaved forest, while soil temperature and bulk density increased in the coniferous forest in the 0–10 and 10–20 soil layers, respectively. Soil organic carbon stocks increased by 14.06% in the evergreen forest and decreased by 14.39% in the coniferous forest. In the evergreen forest, most soil properties and microorganisms contributed to the change of soil organic carbon stocks, however, only soil organic carbon and depth had significant effects in the coniferous forest. Our findings suggest that soil physiochemical properties and microorganisms regulated the different responses of soil organic carbon stocks after bryophyte removal in the two forests. More research is needed to better understand the effects of understory plants on soil organic carbon stocks in various forest ecosystems.

Spatial and Temporal Variation and Prediction of Ecosystem Carbon Stocks in Yunnan Province Based on Land Use Change.

The function of ecosystems as carbon sinks has emerged as a key strategy for advancing the concept of "carbon neutrality" and "carbon peaking". Ecosystem carbon stocks are impacted by land use changes that alter ecosystem structure and function. We evaluated the ecosystem carbon stocks of Yunnan Province in different periods with the aid of the carbon stock module of the InVEST model, analyzed the relationship between land use type shift and ecosystem carbon stock changes, and combine them with the CA-Markov model to predict land use types in 2030. The results showed that between 1990 and 2020, changes in land use primarily affected cropland, grassland, and forested areas. The ecosystem's average carbon stock from 1990 to 2020 was 8278.97 × 106 t. The carbon stocks of cropland, grassland, and unused land decreased by 31.36 × 106 t, 32.18 × 106 t, and 4.18 × 106 t during 1990-2020, respectively, while the carbon stocks of forest land, water area, and construction land increased by 24.31 × 106 t, 7.34 × 106 t, and 22.08 × 106 t. The main cause of the increase in carbon stocks in the ecosystem in Yunnan Province throughout the process of land use type shift was the development of forest land area, whereas the main cause of the decline was the shrinkage of cropland and grassland areas.

ENVIRONMENTAL EFFICIENCY OF DIPTEROCARP FOREST LAND MANAGEMENT AT YOK DON NATIONAL PARK

The dipterocarp forest is a featured ecological forest in the Central Highlands of Vietnam. However, humans and nature are disrupting the ecological balance structure of the forest. This study was conducted to evaluate the environmental efficiency of land management activities of the dipterocarp forest at Yok Don National Park by altering the dipterocarp forest ecosystem and soil organic carbon (SOC) stock for 2001–2020. The results show that the area of the forest converted to other ecosystems (such as meadow, shrub land, construction land, etc.) is 8,284.51 ha. Notably, there was a decrease of 6,107.30 ha in the last 10-year studying period. In Yok Don National Park, SOC varies from 14.3 to 246.8 tons/ha. The total SOC stock is estimated at 7,644,080.493 tons. The average SOC content in the dipterocarp forest in Yok Don National Park is higher than that in other dry dipterocarp forest land.

Developing nondestructive species‐specific tree allometry with terrestrial laser scanning

Abstract Allometric equations predict organism attributes from simple measurements and underlie many global‐scale estimates, from plant productivity to ecosystem carbon stocks. In forests, destructive harvesting of trees in common groups (e.g. plant functional type) or at the species level is necessary to develop allometry but, since sampling is extremely difficult, predictions from these equations have high uncertainty due to low sample size, spatial bias and unrepresentative sampling of tree size. Terrestrial laser scanning (TLS) is a promising remote sensing technology that enables efficient and nondestructive estimates of tree‐level structure for developing allometric equations. Here, we nondestructively estimated component biomass of three coniferous tree species (Pinus ponderosa, Pinus contorta and Pseudotsuga menziesii) in Colorado, USA using TLS. We evaluated the suitability for this nondestructive data to be supplanted for destructive data in the development of species‐specific allometric equations and compared the prediction accuracy against a commonly used national‐scale allometry. We found TLS biomass estimates were consistently more precise across species (RMSE = ~19%) than nation‐scale allometry (RMSE = ~39%). Nondestructive biomass estimates from TLS are a suitable addition to or replacement for traditional sampling methods, with indistinguishable biomass predictions across most of the tested diameter range. We further show how TLS can be used to develop allometric equations compatible with airborne LiDAR and other remote sensing variables (e.g. height and crown area), developing generalized biomass predictions from crown area and tree height (R2 = 0.87). The ability for TLS to support the development of nondestructive allometry at a global scale will enable a more nuanced understanding of the drivers of individual tree architecture, while supporting the next generation of biomass remote sensing.

Blue carbon sinks in South Africa and the need for restoration to enhance carbon sequestration

Blue carbon ecosystems (mangroves, salt marshes, and seagrasses) contribute towards climate change mitigation because they are efficient at sequestering atmospheric CO2 into long-term total ecosystem carbon stocks. Destruction or disturbance therefore reduces sink capacity and leads to significant CO2 emissions. This study reports the first national estimates of: 1) total carbon storage, 2) CO2 emissions from anthropogenic activities, 3) the potential for restoration to enhance carbon sequestration for blue carbon ecosystems in South Africa. Mangrove ecosystems have the greatest carbon storage per unit area (253–534 Mg C ha−1), followed by salt marshes (100–199 Mg C ha−1) and seagrasses (45–144 Mg C ha−1). Salt marshes are the most extensive and contribute 67 % to the national carbon stock of 4000 Gg C. Since 1930, 6500 ha has been lost across all blue carbon ecosystems (26 % of the natural extent), equivalent to losing 1086 Gg C from the national carbon stock. Historic CO2 emissions were estimated at an average rate of 30,266 t CO2e yr−1. Despite losses, a total of 3998 ha could be restored to increase carbon sequestration and CO2 removals of 14,845 tCO2e.yr−1. Extractive activities have declined rapidly in recent decades, but abiotic pressures on estuarine ecosystems (flow modification, reduced water quality, and artificial breaching) have been increasing. There is an urgent need to quantify the potential impact of these pressures and include them in estuarine management and restoration plans. Blue carbon ecosystems cover a relatively small area in South Africa, but they are valued for their multiple ecosystem services that contribute towards climate change adaptation and biodiversity co-benefits. These ecosystems need to be included in national policies driving climate change response in the Agriculture, Forestry and Other Land-Use (AFOLU) sector, such as incorporating them into the wetland subcategory of the national GHG inventory.

Total ecosystem blue carbon stocks and sequestration potential along a naturally regenerated mangrove forest chronosequence

Naturally regenerated (NR) mangroves offer an excellent passive approach for climate change mitigation and adaptation under UN decade of restoration program. However, the support of NR mangroves on total ecosystem carbon (TEC) stocks and sequestration potential remained unclear across forest stand development process that can significantly vary spatially and temporally due to regeneration age. Using the ‘space for time’ approach, this study quantified the TEC stocks along the Merlimau - Kuala Sebatu fringing mangrove habitat expansion chrono-sequence that comprised of 3, 6, 12, 18, 25 years age and intact stands. We also estimated the carbon (C) sequestration potential of each stand-age by comparing with un-vegetated mudflats as control. We collected aboveground tree, belowground root, downed woody debris, litterfall and soil core up to 2 m for TEC quantification and C sequestration. Mean TEC stocks ranged from 232 ± 69 to 296 ± 49 Mg C/ha for NR3 and NR25 respectively at the study area. TEC stocks from different aged NR and intact mangroves were not significantly different from each other and therefore did not affect by age. Aboveground trees C and downed wood C pools were significantly affected by stand-age. In contrast, sediment C stocks (representing up to 80 %) remained generic over many years, driving the constant of TEC stocks in this study. Equally affected by age, the NR mangroves sequestered total C of 2.28 to 17.38 (mean ± SE: 7.36 ± 1.88 Mg C/ha yr−1), with younger stands (NR3) holding almost six times higher total C sequestration rates than older mangroves (NR25). Our study suggests that highly suspended sediments driving from upstream, especially in the younger mangrove stands at a lower elevation, supports higher bulk density and C accumulation rate in the sediment as they expand seaward. This study proves that NR mangroves comprised primarily of younger mangrove stands can be a C sequestrator powerhouse that promises nature-based climate solutions through avoidance and management. Though, future research is needed to understand how better management and conservation practices can affect or towards increasing trend of TEC especially sediment carbon stock that holds almost 80 % of total TEC.

Characterization of Land-Cover Changes and Forest-Cover Dynamics in Togo between 1985 and 2020 from Landsat Images Using Google Earth Engine

Carbon stocks in forest ecosystems, when released as a result of forest degradation, contribute to greenhouse gas (GHG) emissions. To quantify and assess the rates of these changes, the Intergovernmental Panel on Climate Change (IPCC) recommends that the REDD+ mechanism use a combination of Earth observational data and field inventories. To this end, our study characterized land-cover changes and forest-cover dynamics in Togo between 1985 and 2020, using the supervised classification of Landsat 5, 7, and 8 images on the Google Earth Engine platform with the Random Forest (RF) algorithm. Overall image classification accuracies for all target years ranged from 0.91 to 0.98, with Kappa coefficients ranging between 0.86 and 0.96. Analysis indicated that all land cover classes, which were identified at the beginning of the study period, have undergone changes at several levels, with a reduction in forest area from 49.9% of the national territory in 1985, to 23.8% in 2020. These losses of forest cover have mainly been to agriculture, savannahs, and urbanization. The annual change in forest cover was estimated at −2.11% per year, with annual deforestation at 422.15 km2 per year, which corresponds to a contraction in forest cover of 0.74% per year over the 35-year period being considered. Ecological Zone IV (mountainous, with dense semi-deciduous forests) is the one region (of five) that has best conserved its forest area over this period. This study contributes to the mission of forestry and territorial administration in Togo by providing methods and historical data regarding land cover that would help to control the factors involved in forest area reductions, reinforcing the system of measurement, notification, and verification within the REDD+ framework, and ensuring better, long-lasting management of forest ecosystems.

Impacts of indigenous agroforestry practices and elevation gradient on ecosystem carbon stocks in smallholdings’ farming system in South-Central Ethiopia

Impacts of indigenous agroforestry practices and elevation gradient on ecosystem carbon stocks in smallholdings’ farming system in South-Central Ethiopia

Soil geochemistry - and not topography - as a major driver of carbon allocation, stocks, and dynamics in forests and soils of African tropical montane ecosystems.

The lack of field-based data in the tropics limits our mechanistic understanding of the drivers of net primary productivity (NPP) and allocation. Specifically, the role of local edaphic factors - such as soil parent material and topography controlling soil fertility as well as water and nutrient fluxes - remains unclear and introduces substantial uncertainty in understanding net ecosystem productivity and carbon (C) stocks. Using a combination of vegetation growth monitoring and soil geochemical properties, we found that soil fertility parameters reflecting the local parent material are the main drivers of NPP and C allocation patterns in tropical montane forests, resulting in significant differences in below- to aboveground biomass components across geochemical (soil) regions. Topography did not constrain the variability in C allocation and NPP. Soil organic C stocks showed no relation to C input in tropical forests. Instead, plant C input seemingly exceeded the maximum potential of these soils to stabilize C. We conclude that, even after many millennia of weathering and the presence of deeply developed soils, above- and belowground C allocation in tropical forests, as well as soil C stocks, vary substantially due to the geochemical properties that soils inherit from parent material.

НЕУЧТЕННЫЕ ФАКТОРЫ, ОПРЕДЕЛЯЮЩИЕ ЗАПАСЫ УГЛЕРОДА В ЛЕСНЫХ ПОЧВАХ

The sources of uncertainties in estimating soil carbon stocks in forest ecosystems, including abiotic (mechanical composition of soil) and biotic (plants, earthworms) factors, are discussed. The results of comparative assessment of soil carbon storage in coniferous-broadleaved and taiga forests based on direct measurements and pedotransfer functions are presented. It is shown that the estimation of soil carbon stocks in forests based on both direct measurements and pedotransfer functions requires, along with other soil formation factors, taking into account the most dynamic ones, including plants and soil biota, as well as the history of nature management. The calculation of soil carbon stocks should be carried out with account of fine earth (<2 mm fraction) content.

Качество древесного опада как информативный индикатор функциональной классификации лесов

Relevance and goals. In the context of global climate change, the climate-regulating function of forests deserves special attention. There is still no functional classification of forests according to the effectiveness of their carbon storage function. The purpose of this article is to discuss an approach to such classification based on the assessment of the quality of tree litter. Objects and methods. To test the approach to the identification of functional types of forests (FTL) based on the quality of tree litter, taking into account the position in the landscape and the mechanical composition of soil-forming rocks, data on soils and vegetation obtained at 23 sites operating in the subzone of coniferous-broadleaf forests of the European part of Russia on the territory of Bryansk Polesie and Moskvoretsko-Okskaya plain were used. For indirect (on the ecological scale of E. Landolt using the SpeDiv program) to assess differences in the soil richness of forests belonging to different FTLS, the species composition of 160 descriptions of forest vegetation of the Moscow, Bryansk, Smolensk, Kostroma regions, Krasnodar Krai and the Republic of Adygea (North-Western Caucasus) was analyzed. Results. Examples of functional forest types (FTL) for coniferous and broad-leaved forests of the European part of Russia are given. The differences in the level of soil carbon accumulation between different FTLS are shown, and a preliminary assessment of the influence of the position in the landscape and the mechanical composition of soils on the accumulation of carbon in soils within FTLS is given. Conclusion. Based on the quality of the fall of tree litter, 15 FTL were identified, which are confirmed by examples based on geobotanical descriptions of forest communities common in the zone of coniferous-deciduous forests of the European part of Russia and in the belt of coniferous-deciduous forests of the North-Western Caucasus. The validity of the allocation of FTL for the efficiency of carbon accumulation in soils based on the quality of plant litter, taking into account the influence of “external factors” (the position in the landscape and the mechanical composition of soil-forming rocks) is confirmed by data obtained at 23 sites; estimates of the carbon reserves in the soil, as well as the soil richness estimated on an ecological scale, revealed differences between the allocated FTLS. Differences in carbon stocks in forest ecosystems in the same FTL formed on loamy and sandy loam soil-forming rocks were revealed. Differences in soil carbon reserves in forests belonging to the same FTL, but formed at different positions in the landscape, have been confirmed; in transit landscapes, soil carbon reserves are higher than in autonomous ones.

Detection of Carbon Use Efficiency Extremes and Analysis of Their Forming Climatic Conditions on a Global Scale Using a Remote Sensing-Based Model

Carbon use efficiency (CUE) represents the proficiency of plants in transforming carbon dioxide (CO2) into carbon stock in terrestrial ecosystems. CUE extremes represent ecosystems’ extreme proficiency in carbon transformation. Studying CUE extremes and their forming climate conditions is critical for enhancing ecosystem carbon storage. However, the study of CUE extremes and their forming climate conditions on the global scale is still lacking. In this study, we used the results from the daily Boreal Ecosystem Productivity Simulator (BEPS) model to detect the positive and negative CUE extremes and analyze their forming climatic conditions on a global scale. We found grasslands have the largest potential in changing global CUE, with the contribution being approximately 32.4% to positive extremes and 30.2% to negative extremes. Spring in the Northern Hemisphere (MAM) contributed the most (30.5%) to positive CUE extremes, and summer (JJA) contributed the most (29.7%) to negative CUE extremes. The probabilities of gross primary production (GPP) extremes resulted in CUE extremes (>25.0%) being larger than autotrophic respiration (Ra), indicating CUE extremes were mainly controlled by GPP rather than Ra extremes. Positive temperature anomalies (0~1.0 °C) often accompanied negative CUE extreme events, and positive CUE extreme events attended negative temperature anomalies (−1.0~0 °C). Moreover, positive (0~20.0 mm) and negative precipitation (−20.0~0 mm) anomalies often accompanied positive and negative CUE extremes, respectively. These results suggest that cooler and wetter climate conditions could be beneficial to enhance carbon absorptions of terrestrial ecosystems. The study provides new knowledge on proficiency in carbon transformation by terrestrial ecosystems.

Multi-model approach to integrate climate change impact on carbon sequestration potential of afforestation scenarios in Quebec, Canada

Afforestation of unproductive or currently non-forested territories can increase carbon land sinks and thus contribute to mitigate climate change. However, investments on large-scale afforestation could be risky because of the predicted effect of climate change on forest productivity of newly created plantations. The aim of this study was to assess the carbon sequestration and mitigation potential of afforestation scenarios with different species (Picea mariana, Picea glauca, Pinus banksiana, Pinus resinosa and Populus spp) on open woodlands and abandoned farmlands in the Province of Quebec (Canada) under different radiative forcing projections. We modelled carbon dynamics in these lands under three Representative Concentration Pathways projections (RCP 2.6, RCP 4.5, and RCP 8.5) over the 2021–2100 period. The forest gap model PICUS was used to model tree growth of afforested species as a function of the Representative Concentration Pathways 2.6, 4.5 and 8.5; these data were then used as input in the Carbon Budget Model – Canadian Forest Sector 3 to simulate the evolution of ecosystem carbon stocks and fluxes as a function of forest management and climate. Carbon transfer to harvested wood products, and carbon fluxes associated with product life cycles and substitution effects on markets, were also included in the analyses. Results showed that Pinus species responded more strongly to variations in radiative forcing than for the other simulated species. Overall, aboveground biomass was particularly altered by increased radiative forcing, which in turn reduced harvesting yield and transfers to wood processing and products. At the end of the simulation, despite the expected impacts of radiative forcing on ecosystems, afforestation scenarios on open woodlands with black spruce, white spruce, and jack pine can deliver carbon mitigation of 32% – 70% over the baseline scenario and 4% – 12% for red pine on abandoned farmlands and, hence, contribute to efforts to reduce GHG emissions, especially over the long term. Although climate change is expected to impact the growth of newly planted areas as part of afforestation efforts, the results of our study suggest that the choice of species to plant and the selected forest management strategy have a greater impact on carbon stocks than climate change itself. This study provides a better understanding of the dynamics of afforestation under climate change and whether investments in plantation can contribute to GHG reduction targets.

Increased forest coverage will induce more carbon fixation in vegetation than in soil during 2015–2060 in China based on CMIP6

As components of terrestrial carbon sinks, vegetation and soil carbon pools are important for offsetting CO2 emissions. However, differences in their carbon sequestration capacities and their responses to global change in the future are poorly understood. This study assessed the changes in vegetation and soil carbon and their ratios and drivers under the SSP126 scenario from 2015 to 2060, using Coupled Model Intercomparison Project phase 6 simulations in China, a major carbon sink region in global terrestrial ecosystems. The content of vegetation carbon (29 ± 1 PgC) was observed to be lower than that of soil carbon (113 ± 23 PgC), and the ratio of vegetation to soil carbon was the highest in the subtropical-tropical monsoon climatic region (0.55 ± 0.12). Moreover, the total stock of vegetation and soil carbon increased by 10 ± 1 PgC during the study period, and the increase in vegetation carbon was 4.31 times that of soil carbon, because the responses of vegetation carbon stocks to increased forest coverage and atmospheric CO2 were greater than that of soil carbon stocks, especially in the subtropical-tropical and temperate monsoonal climatic regions. However, bare land encroachment on grasslands reduced their increments in the temperate monsoonal and high-cold Tibetan Plateau climatic regions. Furthermore, compared with SSP245 and SSP585 scenarios, vegetation and soil carbon sinks can offset a greater amount of carbon emissions in 2060 under the SSP126 scenario, accounting for 53% of all carbon emissions, offsetting 60%–79% of carbon emissions from China under its policy of increasing forest coverage. The study revealed the important role of afforestation in increasing ecosystem carbon stocks, additionally, grassland conservation and deep reductions in carbon emissions cannot be ignored in the future. This study provides a basis for determining the response of vegetation and soil carbon to environmental factors and the realization of net-zero emissions globally.

Evaluation of Soil Organic Carbon Stock in Coastal Sabkhas under Different Vegetation Covers

There has been increasing focus on conserving coastal ecosystems as they have been recognized as high ecosystem carbon stocks and are in the process of land conversion. The present study aims to examine how different vegetation covers impact the soil organic carbon (SOC) stock in coastal sabkhas. To this end, the study was carried out at ten sampling sites represent ten sabkhas in Saudi Arabia’s southern Red Sea coast for two main goals: (1) to examine the vertical distribution of SOC content, SOC density, and the soil bulk density (SBD) based on different vegetation covers, and (2) to assess these locations’ SOC stocks. This study posits that sabkhas with different vegetation covers had distinct parameters specified above. Significant SBD differences were observed in sabkhas with different vegetation covers, with the lowest mean values of sabkhas having >75–100% vegetation cover and the highest mean values of sabkhas having 0–25% vegetation cover. The studied sabkhas also showed significant difference in the total means of SOC density, SOC content, and SOC stock in terms of different vegetation covers, with the highest mean values of sabkhas having >75–100% vegetation cover and the lowest mean of sabkhas having 0–25% vegetation cover. The present study is the first to focus on Saudi Arabia’s sabkha blue carbon stocks and its results can help add to the literature on sabkhas carbon stock, thus aiding relevant government agencies working towards sabkhas management, encouraging public awareness regarding sabkhas conservation stocks, and their part in climate change mitigation.

Dynamics of Soil Properties and Ecosystem Carbon Stocks for Different Types of Land Use (Middle Taiga of Karelia)

Dynamics of Soil Properties and Ecosystem Carbon Stocks for Different Types of Land Use (Middle Taiga of Karelia)

Analisis Karbon dalam Sedimen pada Ekosistem Lamun di Teluk Gilimanuk, Bali


 
 
 
 The increased CO2 emissions in the atmosphere have caused several environmental changes. Therefore, a larger CO2 absorption capacity is required. Seagrass can absorb carbon relatively fast and able to store it. Seagrass beds can trap sediment, so the absorption of organic carbon from the sediment by seagrass can be influenced by the size of the substrate. It has been found that the larger the substrate grain, the lower the ability of plants to absorb the organic matter. This study aimed to determine the seagrass density and cover as well as carbon storage in seagrass bed sediments. The variable measured was Sediment-Organic Carbon Content (S-OCC) and Sediment-Organic Carbon Stock (S-OCS) of seagrass ecosystems in Gilimanuk Bay. Employing purposive sampling, 20 sampling points were selected randomly where seagrass beds were present. The data were obtained using a 1×1m quadrant transect. The carbon content of the sediment was calculated by the Loss of Ignition (LOI) method by removing organic matter at a temperature of 600? in a furnace. This study found four seagrass species: Enhalus acoroides, Cymodocea rotundata, Cymodocea serrulate, and Halophila ovalis. The average density of seagrasses in this habitat ranged from 17 – 179 #/m2, with seagrass cover values ranging from 25 to 100%. The sediment carbon content, measured as carbon stock, on seagrass ecosystems at Gilimanuk Bay was 0.21% - 5.51% for S-OCC and 0.002 – 0.059 g Corg cm-3 for S-OCS. Total S-OCS in Gilimanuk Bay was 11165.84 Mg g Corg.
 
 
 

Harvesting Intensity and Aridity Are More Important Than Climate Change in Affecting Future Carbon Stocks of Douglas-Fir Forests

Improved forest management may offer climate mitigation needed to hold warming to below 2°C. However, uncertainties persist about the effects of harvesting intensity on forest carbon sequestration, especially when considering interactions with regional climate and climate change. Here, we investigated the combined effects of harvesting intensity, climatic aridity, and climate change on carbon stocks in Douglas-fir [Pseudotsuga menziesii Mirb. (Franco)] stands. We used the Carbon Budget Model of the Canadian Forest Sector to simulate the harvest and regrowth of seven Douglas-fir stand types covering a 900 km-long climate gradient across British Columbia, Canada. In particular, we simulated stand growth under three regimes (+17%, −17% and historical growth increment) and used three temperature regimes [historical, representative concentration pathways (RCP) 2.6 and RCP 8.5]. Increasing harvesting intensity led to significant losses in total ecosystem carbon stocks 50 years post-harvest. Specifically, forests that underwent clearcutting were projected to stock about 36% less carbon by 2,069 than forests that were left untouched. Belowground carbon stocks 50 years into the future were less sensitive to harvesting intensity than aboveground carbon stocks and carbon losses were greater in arid interior Douglas-fir forests than in humid, more productive forests. In addition, growth multipliers and decay due to the RCP’s had little effect on total ecosystem carbon, but aboveground carbon declined by 7% (95% confidence interval [−10.98, −1.81]) in the high emissions (RCP8.5) scenario. We call attention to the implementation of low intensity harvesting systems to preserve aboveground forest carbon stocks until we have a more complete understanding of the impacts of climate change on British Columbia’s forests.