Carbon Storage In Terrestrial Ecosystems Research Articles

Large Soil Carbon Storage in Terrestrial Ecosystems of Canada

AbstractTerrestrial ecosystems of Canada store a large amount of organic carbon (C) in soils, peats and plant materials, yet little is known about the C stock size and distributions, both spatially and in various C pools. As temperature rises, C is becoming available for disturbance, decomposition and eventual release into the atmosphere, which makes the quantification of C stocks in terrestrial ecosystems of Canada of high interest for the assessment of climate change impacts and conservation efforts. We used a large number of field measurements, multisource satellite, climate and topographic data and a machine learning algorithm to produce the first wall‐to‐wall estimates of C stocks and uncertainties in plants and soils of Canada at 250 m spatial resolution. Our findings show that above and belowground live biomass and detritus store a total of 21.1 Pg of carbon (Pg C). Whereas the Canadian soils store 306 (±147, 90% confidence interval) Pg organic C in the top 1 m, 98 Pg C of which are stored in peatlands, confirming that the soil organic C dominates terrestrial carbon stocks in Canada. We also find previously under‐reported large soil organic C stocks in forested peatlands on the boreal shields of Canada. Given that Canada is warming twice the global average rate and Canadian soils store approximately 20.4% of world soil C stocks in top 1 m, initiatives to understand their vulnerabilities to climate change and disturbance are indispensable not only for Canada but also for the global C cycle.

Analysis of the effect of environmental protected areas on land-use and carbon storage in a megalopolis

Carbon storage in terrestrial ecosystems plays a vital role in climate control. However, urban expansion and damage to natural areas, especially the rise of megalopolises, have affected carbon storage. To mitigate this damage, various policies have been established by international, domestic, and local governments. This study focuses on the establishment and management of environmental protection areas and analyzes their impact on carbon storage. The study targets the cities of Gyeonggi-do province, South Korea, which make up a representative megalopolis, and the effectiveness of protected areas was analyzed by typifying the cities based on the proportion of available development areas and environmentally protected areas. In this study, the SLEUTH (Slope, Land-use, Excluded Area, Urban, Transportation, Hillshade) land-use change model was used to predict future land-use changes, and carbon storage was estimated using the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) Carbon model. When operating the model, we tested a control group scenario that only preserves the water zone, a scenario that preserves the legally protected areas, and a scenario that protects the areas with high environmental value. There are two significant effects of setting up protected areas: First, the “development inhibition effect” of reducing the development area itself. Second, the “development replacement effect” of moving development to relatively low environmental value areas. These two effects differ depending on the availability of development areas, with “development replacement effects” prominent in areas with high development availability and “development inhibition effects” predominant in areas with low development availability. Future policies for setting up and managing protected areas can be used in megalopolis in conjunction with policies focusing on securing the area of carbon sinks.

Land-use changes lead to a decrease in carbon storage in arid region, China

The carbon storage of terrestrial ecosystems is closely related to global climate change. Therefore, assessing the impact of land-use changes on carbon storage is instructive to reduce global carbon emissions. Taking an arid region in northwest China as an example, this paper analyzed the land-use changes in arid region from 1980 to 2015. It used the CA-Markov model to predict the land-use pattern from 2020 to 2050, the carbon storage and sequestration module in Integrated Valuation of Ecosystem Services and Tradeoffs (Invest) mode to assess and predict ecosystem carbon storage over the past 35 years and in the next 30 years and discusses the impact of land-use changes on the carbon storage of terrestrial ecosystems. The results showed that: (1) The high-value areas of carbon storage in arid region were primarily concentrated in grassland, forests and farmland, and the low-value areas of carbon storage were mainly in desert areas. (2) The carbon storage in arid region showed a downward trend. From 1980 to 2015, the carbon reserves of terrestrial ecosystems in arid region decreased by 90.95 Tg, and the net loss of carbon reserves from 2020 to 2050 was 14.72 Tg. Grassland degradation was the main reason for the reduction of carbon storage in arid region. (3) The carbon storage of farmland had increased significantly, but the expansion of farmland dominated by high carbon density grassland, wetland and forest, had reduced the overall carbon storage of the arid region.

Nitrogen addition stimulates soil aggregation and enhances carbon storage in terrestrial ecosystems of China: A meta‐analysis

China is experiencing a high level of atmospheric nitrogen (N) deposition, which greatly affects the soil carbon (C) dynamics in terrestrial ecosystems. Soil aggregation contributes to the stability of soil structure and to soil C sequestration. Although many studies have reported the effects of N enrichment on bulk soil C dynamics, the underlying mechanisms explaining how soil aggregates respond to N enrichment remain unclear. Here, we used a meta-analysis of data from 76N manipulation experiments in terrestrial ecosystems in China to assess the effects of N enrichment on soil aggregation and its sequestration of C. On average, N enrichment significantly increased the mean weight diameter of soil aggregates by 10%. The proportion of macroaggregates and silt-clay fraction were significantly increased (6%) and decreased (9%) by N enrichment, respectively. A greater response of macroaggregate C (+15%) than of bulk soil C (+5%) to N enrichment was detected across all ecosystems. However, N enrichment had minor effects on microaggregate C and silt-clay C. The magnitude of N enrichment effect on soil aggregation varied with ecosystem type and fertilization regime. Additionally, soil pH declined consistently and was correlated with soil aggregate C. Overall, our meta-analysis suggests that N enrichment promotes particulate organic C accumulation via increasing macroaggregate C and acidifying soils. In contrast, increases in soil aggregation could inhibit microbially mediated breakdown of soil organic matter, causing minimal change in mineral-associated organic C. Our findings highlight that atmospheric N deposition may enhance the formation of soil aggregates and their sequestration of C in terrestrial ecosystems in China.

Reexamine China’s terrestrial ecosystem carbon balance under land use-type and climate change

Land use and climate change can strongly affect the terrestrial ecosystem carbon balance. However, there is a lack of clarity for existing studies that investigate total carbon balance for China’s terrestrial carbon balance (carbon storage and Net Ecosystem Productivity (NEP)). In this study, based on large data and the improved NEP model, we examined land use and climate change during 2000–2015 in China, calculated terrestrial ecosystem carbon storage change caused by land use change, and carbon sink/source variation under climate change; we found that during 2000–2015, 3.05 % of China’s land area had land use type changes and caused 32.97 Tg of carbon storage loss, consisting of 10.4 Tg from vegetation carbon storage and 22.57 Tg from soil organic carbon (SOC) loss. Built-up land occupying ecological land was the most obvious land transfer type, especially for grassland degeneration. Both temperature and precipitation showed decreasing trends throughout China. Mean annual NEP showed a carbon sink value of 41.73 g C.m−2.yr−1, and the NEPs of carbon sinks were mostly distributed in South and Midland China and partly in Northeast China. There were obvious regional differences and the carbon balance showed that North China and Northwest China were regions of net carbon sources. The other four regions were net carbon sinks. Land use changes caused carbon storage loss in all regions, NEPs in North China and Northwest China were carbon sources, while in the other regions were carbon sinks. All NEPs exhibited an increasing trend during 2000–2015, except for Mid-South China. Finally, according to regional carbon balance characters, different policy implications were drawn which can serve for the formulation of territorial spatial planning. Land exploitation should be limited and environmental conservation is needed in North and Northwest China. The temperature in Southwest China has been increasing continuously and merits attention. The control of built-up land expansion in other regions should be strengthened.

Modeling the Impacts of Nitrogen Dynamics on Regional Terrestrial Carbon and Water Cycles over China with Noah-MP-CN

As an important part of biogeochemical cycling, the nitrogen cycle modulates terrestrial ecosystem carbon storage, water consumption, and environmental quality. Modeling the complex interactions between nitrogen, carbon and water at a regional scale remains challenging. Using China as a testbed, this study presents the first application of the nitrogen-augmented community Noah land surface model with multi-parameterization options (Noah-MP-CN) at the regional scale. Noah-MP-CN parameterizes the constraints of nitrogen availability on photosynthesis based on the Fixation and Uptake of Nitrogen plant nitrogen model and the Soil and Water Assessment Tool soil nitrogen model. The impacts of nitrogen dynamics on the terrestrial carbon and water cycles are investigated by comparing the simulations with those from the original Noah-MP. The results show that incorporating nitrogen dynamics improves the carbon cycle simulations. Noah-MP-CN outperforms Noah-MP in reproducing leaf area index (LAI) and gross primary productivity (GPP) for most of China, especially in the southern warm and humid regions, while the hydrological simulations only exhibit slight improvements in soil moisture and evapotranspiration. The impacts of fertilizer application over cropland on carbon fixation, water consumption and nitrogen leaching are investigated through a trade-off analysis. Compared to halved fertilizer use, the actual quantity of application increases GPP and water consumption by only 1.97% and 0.43%, respectively; however, the nitrogen leaching is increased by 5.35%. This indicates that the current level of fertilizer use is a potential concern for degrading the environment.

Exploring the impacts of urban growth on carbon storage under integrated spatial regulation: A case study of Wuhan, China

Abstract The increasing demand for natural resources due to urban growth has led to sharp conflicts between urban land demand and environmental protection, causing problems such as decrease in the carbon storage of terrestrial ecosystems. To achieve sustainable urban development, China has implemented spatial regulation to restrict urban growth, but there have been various conflicts among multiple spatial regulation plans. In this study, we explored the impact of urban growth on carbon storage under integrated spatial regulation in Wuhan, China by combining the SLEUTH and InVEST (Integrated Valuation of Environmental Services and Tradeoffs) models. Firstly, the SLEUTH model was adopted to simulate the urban growth under different scenarios from 2015 to 2030. Then, the InVEST model was employed to explore the impacts of urban growth on regional carbon storage. The results showed that the integrated spatial regulation can reduce the growth rate of urban areas, decrease the use of natural resources by urban land, and alleviate the conflicts between the construction needs of urban development and environmental protection. Besides, under integrated spatial regulation, the encroachment rate of high carbon density land by urban growth is gradually slowed down, effectively reducing the loss of regional carbon storage. These findings indicate that the implementation of urban development strategies under integrated spatial regulation will better facilitate regional sustainable development than traditional urban planning.

Patterns and environmental controls of soil organic carbon density in Chinese shrublands

The soils of shrublands are important for organic carbon storage in terrestrial ecosystems, but geographical patterns and environmental controls of soil organic carbon (SOC) remain largely understudied compared to other terrestrial ecosystems, leaving a significant gap in our understanding of terrestrial ecosystem carbon budgets. Here, we quantified SOC density (SOCD) and its potential determinants based on a comprehensive dataset with a consistent stratified random sampling of extensive soil profiles down to the parent material or to one meter depth across 1211 sites across China. Our up-to-date estimate of SOCD in Chinese shrublands is an average of 8.36 kg m−2, and ca. 43% of SOC is stored in the upper 20 cm relative to the one meter top soil, which is higher than estimates for shrublands globally. We also observed that SOCD was positively related to shrubland biomass and more so with belowground biomass. Furthermore, SOCD was positively related to mean annual precipitation (MAP), soil total nitrogen (N), phosphorus (P), clay and silt percent, but decreased with increasing mean annual temperature (MAT). Dark felty soils stored the highest SOCD and frigid desert soils stored the lowest. Soil total nitrogen (N), MAP, soil type, MAT, and belowground biomass, soil clay, and pH were the best predictors of total SOCD in Chinese shrublands. We concluded that Chinese shrubland soils store the lowest density of organic carbon so far recorded compared to forests and grasslands, and that the vertical distribution of SOC in Chinese shrublands was much shallower. While both climate (in particular MAP) and soil total N exerted dominant control over geographical patterns of SOCD across Chinese shrublands, soil type also played a significant role. Our study also emphasizes this key role of edaphic variables in determining the SOCD of shrublands and that they should be better incorporated into large-scale assessments of SOC dynamics. Our study extends existing work conducted in forest and grasslands and provides the most up-to-date knowledge on benchmark values for SOCD in Chinese shrublands, with important implications for predicting the fate of C stored in shrubland soils in response to climate change.

Soil organic carbon pools and stocks in different land uses of a temperate Himalayan region

Land use is a main driver of carbon storage in terrestrial ecosystems, particularly under the resource constrained and temperate mountains of the Himalayas. Impact of different land uses on soil organic carbon (SOC) and its functional pools were recorded from two depths (0–15 and 15–30 cm). The study included seven different land use types, namely wetlands, forests, grasslands, apple orchards, vegetable fields, maize (Zea mays L.) and rice (Oryza sativa L.) fields. The average total SOC in surface and sub-surface soil layers of wetland, forest and grassland soils taken together was 2.6 times higher than average SOC recorded in cropped soils. Average labile carbon in the surface soil layers of wetlands was 11.20 g kg−1. Forests, grasslands, apple orchards, maize, vegetable and rice fields had 39, 25, 21, 20, 18 and 18 per cent more labile carbon, respectively compared with wetland soils. The wetlands store the highest quantity (28 Mg ha−1) of particulate organic carbon in the 0–30 cm soil layer, whereas vegetable soils of the zone retain the least (7 Mg ha−1). The microbial biomass carbon concentration in the rice soils (0.22 mg kg−1) was lowest, however, the highest concentration (0.87 mg kg−1) was observed in wetland soils. The greatest carbon management index among the soils was recorded in forest land use followed by grassland. The total SOC stocks were 18.84 to 61.09 Mg ha−1 in rice and wetland soils, respectively. Therefore, the carbon losses due to land use conversion from wetlands into rice or vegetable fields, and conversion of forest into maize fields are about 40 and 10 Mg ha−1, respectively, in the 0–30 cm soil layer.

Spatiotemporal Dynamics of Carbon Storage in Response to Urbanization: A Case Study in the Su-Xi-Chang Region, China

Terrestrial ecosystem carbon storage plays an important role in mitigating global warming. Understanding the characteristics and drivers of changes in carbon storage can provide a scientific basis for urban planning and management. The objective of this study was to reveal the ways in which urbanization influences the spatial and temporal variations in carbon storage. In this study, we investigated the changes in carbon storage from 1990–2000, 2000–2010, and 2010–2018 in the Su-Xi-Chang region, which is a typical fast-growing urban agglomeration in China, based on the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) model. Moreover, we analyzed the impacts of urbanization-induced land-use changes on carbon storage. The results showed that in terms of space and time, the greatest loss of carbon storage occurred in developing urban areas and during the rapidly urbanizing stage. Our study revealed that the reduction in cultivated land was the greatest contributor to carbon stock losses. In addition, we found that some types of land use conversion can enhance carbon storage. Based on the results, some suggestions are proposed aimed at promoting urban sustainable development. This study also provides insights into enhancing urban sustainability for other urban agglomerations throughout the world.

Effects of 21st-century climate, land use, and disturbances on ecosystem carbon balance in California.

Terrestrial ecosystems are an important sink for atmospheric carbon dioxide (CO2), sequestering ~30% of annual anthropogenic emissions and slowing the rise of atmospheric CO2. However, the future direction and magnitude of the land sink is highly uncertain. We examined how historical and projected changes in climate, land use, and ecosystem disturbances affect the carbon balance of terrestrial ecosystems in California over the period 2001–2100. We modeled 32 unique scenarios, spanning 4 land use and 2 radiative forcing scenarios as simulated by four global climate models. Between 2001 and 2015, carbon storage in California's terrestrial ecosystems declined by −188.4 Tg C, with a mean annual flux ranging from a source of −89.8 Tg C/year to a sink of 60.1 Tg C/year. The large variability in the magnitude of the state's carbon source/sink was primarily attributable to interannual variability in weather and climate, which affected the rate of carbon uptake in vegetation and the rate of ecosystem respiration. Under nearly all future scenarios, carbon storage in terrestrial ecosystems was projected to decline, with an average loss of −9.4% (−432.3 Tg C) by the year 2100 from current stocks. However, uncertainty in the magnitude of carbon loss was high, with individual scenario projections ranging from −916.2 to 121.2 Tg C and was largely driven by differences in future climate conditions projected by climate models. Moving from a high to a low radiative forcing scenario reduced net ecosystem carbon loss by 21% and when combined with reductions in land‐use change (i.e., moving from a high to a low land‐use scenario), net carbon losses were reduced by 55% on average. However, reconciling large uncertainties associated with the effect of increasing atmospheric CO2 is needed to better constrain models used to establish baseline conditions from which ecosystem‐based climate mitigation strategies can be evaluated.

A Land Use/Land Cover Based Green Development Study for Different Functional Regions in the Jiangsu Province, China.

Land use/land cover (LULC) change can strongly affect carbon storage in terrestrial ecosystems. The rapid development of China’s economy has formed different functional regions. These functional regions profoundly affect land use patterns. Thus, assessing the carbon storage induced by LULC changes is significant for green development. Selecting the typical region of the Jiangsu Province as the study area, this study first examines the research associated with the regional functional characteristics and various high accuracy data and methods have been used to greatly improve the research accuracy. The results showed that from 1995 to 2015, approximately 10.26% of the entire land area had LULC type changes. Additionally, decreases in the built-up land expansion and ecological land were the main LULC change characteristics, which are mainly affected by socioeconomic development. The total carbon storage of the Jiangsu Province decreased by 714.03 × 104 t and the four regions all presented decreasing carbon storage levels. The economically developed regions presented a more obvious loss of carbon. The region with small LULC changes had a lower carbon loss. The land transfer of cultivated land to built-up land is the main transfer type causing the carbon storage loss. This study investigates the human-environmental interactions from the new perspective of functional zoning and, thus, it enriches the comparative analysis of carbon storage in functional regions and provides references for the green development of a developing country’s developed areas.

Assessing historical and projected carbon balance of Alaska: A synthesis of results and policy/management implications.

We summarize the results of a recent interagency assessment of land carbon dynamics in Alaska, in which carbon dynamics were estimated for all major terrestrial and aquatic ecosystems for the historical period (1950-2009) and a projection period (2010-2099). Between 1950 and 2009, upland and wetland (i.e., terrestrial) ecosystems of the state gained 0.4TgC/yr (0.1% of net primary production, NPP), resulting in a cumulative greenhouse gas radiative forcing of 1.68×10-3 W/m2 . The change in carbon storage is spatially variable with the region of the Northwest Boreal Landscape Conservation Cooperative (LCC) losing carbon because of fire disturbance. The combined carbon transport via various pathways through inland aquatic ecosystems of Alaska was estimated to be 41.3TgC/yr (17% of terrestrial NPP). During the projection period (2010-2099), carbon storage of terrestrial ecosystems of Alaska was projected to increase (22.5-70.0TgC/yr), primarily because of NPP increases of 10-30% associated with responses to rising atmospheric CO2 , increased nitrogen cycling, and longer growing seasons. Although carbon emissions to the atmosphere from wildfire and wetland CH4 were projected to increase for all of the climate projections, the increases in NPP more than compensated for those losses at the statewide level. Carbon dynamics of terrestrial ecosystems continue to warm the climate for four of the six future projections and cool the climate for only one of the projections. The attribution analyses we conducted indicated that the response of NPP in terrestrial ecosystems to rising atmospheric CO2 (~5% per 100 ppmv CO2 ) saturates as CO2 increases (between approximately +150 and +450 ppmv among projections). This response, along with the expectation that permafrost thaw would be much greater and release large quantities of permafrost carbon after 2100, suggests that projected carbon gains in terrestrial ecosystems of Alaska may not be sustained. From a national perspective, inclusion of all of Alaska in greenhouse gas inventory reports would ensure better accounting of the overall greenhouse gas balance of the nation and provide a foundation for considering mitigation activities in areas that are accessible enough to support substantive deployment.

Effects of carbon turnover time on terrestrial ecosystem carbon storage

Abstract. Carbon (C) turnover time is a key factor in determining C storage capacity in various plant and soil pools as well as terrestrial C sink in a changing climate. However, the effects of C turnover time on ecosystem C storage have not been well explored. In this study, we compared mean C turnover times (MTTs) of ecosystem and soil, examined their variability to climate, and then quantified the spatial variation in ecosystem C storage over time from changes in C turnover time and/or net primary production (NPP). Our results showed that mean ecosystem MTT based on gross primary production (GPP; MTTEC_GPP = Cpool/GPP, 25.0 ± 2.7 years) was shorter than soil MTT (MTTsoil = Csoil/NPP, 35.5 ± 1.2 years) and NPP-based ecosystem MTT (MTTEC_NPP = Cpool/NPP, 50.8 ± 3 years; Cpool and Csoil referred to ecosystem or soil C storage, respectively). On the biome scale, temperature is the best predictor for MTTEC (R2 = 0.77, p < 0.001) and MTTsoil (R2 = 0.68, p < 0.001), while the inclusion of precipitation in the model did not improve the performance of MTTEC (R2 = 0.76, p < 0.001). Ecosystem MTT decreased by approximately 4 years from 1901 to 2011 when only temperature was considered, resulting in a large C release from terrestrial ecosystems. The resultant terrestrial C release caused by the decrease in MTT only accounted for about 13.5 % of that due to the change in NPP uptake (159.3 ± 1.45 vs. 1215.4 ± 11.0 Pg C). However, the larger uncertainties in the spatial variation of MTT than temporal changes could lead to a greater impact on ecosystem C storage, which deserves further study in the future.

A Preliminary Study of the Carbon Emissions Reduction Effects of Land Use Control.

Land use change not only directly influences carbon storage in terrestrial ecosystems but can also cause energy-related carbon emissions. This study examined spatiotemporal land use change across Jiangsu Province, China; calculated vegetation carbon storage loss caused by land use change and energy-related carbon emissions; analysed the relationship among land use change, carbon emissions and social-economic development; and optimized land use structure to maximize carbon storage. Our study found that 13.61% of the province’s land area underwent a change in type of land use between 1995 and 2010, mainly presented as built-up land expansion and cropland shrinkage, especially in southern Jiangsu. Land use change caused a 353.99 × 104 t loss of vegetation carbon storage loss. Energy-related carbon emissions increased 2.5 times from 1995 to 2013; the energy consumption structure has been improved to some extent while still relying on coal. The selected social-economic driving forces have strong relationships with carbon emissions and land use changes, while there are also other determinants driving land use change, such as land use policy. The optimized land use structure will slow the rate of decline in vegetation carbon storage compared with the period between 1995 and 2010 and will also reduce energy-related carbon emissions by 12%.

Stimulation of terrestrial ecosystem carbon storage by nitrogen addition: a meta-analysis

Elevated nitrogen (N) deposition alters the terrestrial carbon (C) cycle, which is likely to feed back to further climate change. However, how the overall terrestrial ecosystem C pools and fluxes respond to N addition remains unclear. By synthesizing data from multiple terrestrial ecosystems, we quantified the response of C pools and fluxes to experimental N addition using a comprehensive meta-analysis method. Our results showed that N addition significantly stimulated soil total C storage by 5.82% ([2.47%, 9.27%], 95% CI, the same below) and increased the C contents of the above- and below-ground parts of plants by 25.65% [11.07%, 42.12%] and 15.93% [6.80%, 25.85%], respectively. Furthermore, N addition significantly increased aboveground net primary production by 52.38% [40.58%, 65.19%] and litterfall by 14.67% [9.24%, 20.38%] at a global scale. However, the C influx from the plant litter to the soil through litter decomposition and the efflux from the soil due to microbial respiration and soil respiration showed insignificant responses to N addition. Overall, our meta-analysis suggested that N addition will increase soil C storage and plant C in both above- and below-ground parts, indicating that terrestrial ecosystems might act to strengthen as a C sink under increasing N deposition.

Erratum to: Quantifying and monetizing potential climate change policy impacts on terrestrial ecosystem carbon storage and wildfires in the United States

Author(s): Mills, D; Jones, R; Carney, K; Juliana, AS; Ready, R; Crimmins, A; Martinich, J; Shouse, K; DeAngelo, B; Monier, E

Improving the application of laser-induced breakdown spectroscopy for the determination of total carbon in soils.

The increase of atmospheric greenhouse gases such as CO2 has caused noticeable climate change. Since increased CO2 may contribute to carbon storage in terrestrial ecosystems through the CO2 cycle between the atmosphere and vegetation, it is necessary to improve methods for measuring C in soil. In this study, we determined the total carbon concentrations of soils using a highly sensitive and rapid method, laser-induced breakdown spectroscopy. The presence of C has been measured by detecting signal at the wavelength of 247.86 nm. The obstacle of Fe interference at the C measurement wavelength of 247.86 nm was reduced by selecting the optimal delay time of 1.4 μs. The ratio of peak intensities (areas) at 247.86 nm for C and 248.20 nm for Fe was then successfully applied to the calibration curve. In addition, to dismiss the problem of measuring the C lines at 247.86 nm, 193.03 nm has been used to observe C emission. Both the 193.03- and 247.86-nm lines provided significant linear calibrations. The 193.03-nm lines presented stronger relative accuracies in predicting the lower C concentrations of the unknown samples than that one at 247.86 nm.

Variations in soil organic carbon contents and isotopic compositions under different land uses in a typical karst area in Southwest China

Land use changes can affect soil carbon storage in terrestrial ecosystems by altering either the biotic or the abiotic processes involved in carbon cycling, such as the adsorption of carbon on soil minerals. In this study, the organic carbon contents and their stable carbon isotopic compositions (δ13C) of five soil profiles under different land uses in the Maolan karst region in Southwest China were analyzed. Four non-forest samples from the karst were selected and examined to determine whether farmlands or grasslands that were converted from forestland were more effective in sequestering carbon in soils. The soil organic carbon (SOC) contents decreased in the following order: virgin forest, burnt grassland, shrubland, grassland, and farmland. However, no differences were observed in the δ13C values at the bottom of the five profiles, which indicated that most of the soil organic carbon was derived from the original virgin forest. The percentages of SOC that resulted from C4 plants in the virgin forest were significantly lower than the percentages in the other plots, while the percentages of SOC that resulted from C3 plants in the virgin forest were significantly higher than the percentages in the other plots. The δ13C values in the topsoils of the various profiles decreased in the following order: burnt grassland, farmland, grassland, shrubland, and virgin forest. From the surface to the base of the farmland profiles, little variation occurred in the δ13C values of the SOC (from -25.1 to -29.1‰). This variation in the δ13C values of the SOC in the surface soils was associated with changes in the vegetation cover. In addition, our results suggest that the plant functional type is important for controlling the depth-related changes in the SOC contents and the δ13C values of the SOC.

草地土壤固碳潜力研究进展

PDF HTML阅读 XML下载 导出引用 引用提醒 草地土壤固碳潜力研究进展 DOI: 10.5846/stxb201310212541 作者: 作者单位: 中国科学院地理科学与资源研究所,中国科学院地理科学与资源研究所,中国科学院地理科学与资源研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点基础研究发展计划(973计划)(2011CB403206, 2012CB416906); 国家科技支撑计划(2013BAC03B04); 国家自然科学基金项目(41371196) Review on soil carbon sequestration potential in grassland ecosystems Author: Affiliation: Institute of Geographic Sciences and Natural Resources Research,-A Datun Road,Chaoyang District,Beijing,Institute of Geographic Sciences and Natural Resources Research,-A Datun Road,Chaoyang District,Beijing,Institute of Geographic Sciences and Natural Resources Research,-A Datun Road,Chaoyang District,Beijing Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:土壤固碳功能和固碳潜力已成为全球气候变化和陆地生态系统研究的重点。草地土壤有机碳库,作为陆地土壤有机碳库的重要组成部分,其较小幅度的波动,将会影响整个陆地生态系统碳循环,进而影响全球气候变化。因此,深入研究草地土壤固碳功能和固碳潜力对于适应和减缓气候变化具有重要意义。在土壤固碳潜力相关概念界定基础上,结合《2006年IPCC国家温室气体清单指南》,从样点及区域尺度上综述了目前关于草地土壤固碳潜力的一般估算方法,同时对各类方法的特点及适用性进行了评述,提出了草地生态系统固碳潜力研究概念模型。最后在对草地土壤固碳的影响因素及固碳措施总结的基础上,阐明了草地土壤有机碳固定研究中存在的问题和发展前景。 Abstract:Global climate change has aroused wide concern from the international community, and national or regional GHG (greenhouse gas) emission has become a focus of the intergovernmental diplomatic dispute and mediation. The stability, release or increment of the soil carbon stock is closely related to the change of the atmospheric carbon stock. Even a minor change in soil organic carbon (SOC) storage may result in a significant change in atmospheric CO2 concentration. Whether the soil carbon stock can increase becomes an essential theoretical basis for terrestrial ecosystems to absorb atmospheric CO2, and serve as carbon sink. Therefore, increasing soil carbon sink in terrestrial ecosystems has become an important strategy for controlling the rise in atmospheric CO2 concentration. As one of the world's most widespread terrestrial ecosystems, covering over 15% of the world's land surface, grassland ecosystems account for over 10% of the total carbon storage in terrestrial ecosystems, with nearly 90% of the carbon storing in top soil. Besides, grassland soil organic carbon could be strongly influenced by management practices. During the past decades, owing to the climate change, overgrazing and other unreasonable management practices, the grasslands in the world had been seriously degraded and the soil organic carbon had significantly decreased. However, improved management practices such as enclosure and recovery of degraded grassland and conversion of cropland to abandoned fields, may reverse the loss of soil organic carbon, and even help to sequestrate carbon in the atmosphere. Therefore, under the background of climate change, the function and potential of soil organic carbon sequestration in grassland ecosystems has become a key issue. In this essay, the recent research on soil carbon sequestration potential was reviewed, including quantitative methods for estimating soil carbon sequestration potential on both regional and sample scales, dominant affecting factors and management practices of carbon sequestration, and future research direction was also proposed lastly. Research on quantitative estimation of soil carbon sequestration in grassland ecosystems had been well developed in recent years, from simple statistics on sample scale to mechanism modeling coupled with GIS and RS on regional scale. IPCC also issued guidelines for national greenhouse gas inventories so as to provide a relatively uniform method for national carbon sequestration estimation, which contained three tiers on estimation of soil organic carbon storage in grassland: Tier1, Tier2, and Tier3. Among all the quantitative methods, mechanism modeling of soil carbon cycle became a major method to assess the carbon sequestration of terrestrial ecosystems and the reduction of greenhouse gas emission in the world. The dominant factors affecting soil organic carbon sequestration included natural factors (temperature, precipitation and CO2 concentration etc.) and human factors (reclamation, grazing, fire, enclosure, fertilization, irrigation and reseeding etc.), which held complicated influences on carbon sequestration with various time and intensity of management practices. There also existed many problems needed to be solved in the future, such as the methodology and adaptability of models and the uncertainty of estimation on regional scale. The potential and mechanism of carbon sequestration, and the relationship between carbon sequestration and environmental effects would be the key scientific problems. 参考文献 相似文献 引证文献