Regional Carbon Storage Research Articles

Effects of land use change on soil organic carbon and total nitrogen storage in Karst immigration regions of Guangxi Province, China.

Land use change is an important factor affecting soil carbon and nitrogen cycle, and this is a hot spot in the study of global climate change. Based on the fixed depth method (FD) and the equivalent mass method (ESM), we explored the effects of land use change on soil organic carbon (SOC) and total nitrogen (TN) storage from the perspectives of forest reclamation and farmland vegetation restoration in Karst area. The storage of SOC and TN significantly decreased after the fore-sts were converted to grassland, eucalyptus and farmland. On average, the SOC and TN losses calculated by the FD method were 47.4% and 41.6%, respectively, the losses of SOC and TN calculated by ESM method were 54.8% and 49.7%. The SOC and TN storage increased significantly after abandonment of farmland to grassland or planting eucalyptus. On average, the SOC and TN stocks calculated based on the FD method increased by 60.5% and 49.7%, while the SOC and TN calculated by the ESM method increased by 85.5% and 70.8% respectively. The difference between FD method and ESM method was analyzed, it was concluded that FD method ignored the difference of soil bulk density after land use change. Soil bulk density was significantly increased after forest destruction. The loss of SOC and TN storage was overestimated by the FD method. Soil bulk density decreased after vegetation restoration, FD method will underestimate the enhancement of SOC and TN storage. It is suggested that the ESM method should be used to estimate the impacts of land use change on SOC and TN storage.

Impacts of fire on sources of soil CO2 efflux in a dry Amazon rain forest.

Fire at the dry southern margin of the Amazon rainforest could have major consequences for regional soil carbon (C) storage and ecosystem carbon dioxide (CO2 ) emissions, but relatively little information exists about impacts of fire on soil C cycling within this sensitive ecotone. We measured CO2 effluxes from different soil components (ground surface litter, roots, mycorrhizae, soil organic matter) at a large-scale burn experiment designed to simulate a severe but realistic potential future scenario for the region (Fire plot) in Mato Grosso, Brazil, over 1year, and compared these measurements to replicated data from a nearby, unmodified Control plot. After four burns over 5years, soil CO2 efflux (Rs ) was ~5.5t Cha-1 year-1 lower on the Fire plot compared to the Control. Most of the Fire plot Rs reduction was specifically due to lower ground surface litter and root respiration. Mycorrhizal respiration on both plots was around ~20% of Rs . Soil surface temperature appeared to be more important than moisture as a driver of seasonal patterns in Rs at the site. Regular fire events decreased the seasonality of Rs at the study site, due to apparent differences in environmental sensitivities among biotic and abiotic soil components. These findings may contribute toward improved predictions of the amount and temporal pattern of C emissions across the large areas of tropical forest facing increasing fire disturbances associated with climate change and human activities.

Impact of drought on vegetation carbon storage in arid and semi-arid regions

Drought is a common phenomenon in arid and semi-arid regions. In global carbon cycle, semi-arid ecosystem plays a crucial role in interannual variability and greening trend. The vegetation carbon storage and its relation with drought in India are not well understood. The impact of drought on vegetation carbon storage is investigated using Standardized Precipitation Evapotranspiration Index (SPEI) and CASA (Carnegie-Ames-Stanford Approach) derived Net Primary Production (NPP) during 2001–2013. A strong positive correlation is found between regional NPP and SPEI. CASA derived NPP shows good agreement (R2 = 0.57, significance > 95%) with field based observation in arid and semi-arid regions of Gujarat. A significant Increasing trend of 0.2 TgC Yr−1 (about 2 % per year) is observed during the period of 2001–2013. The highest decreased of 24% (2.79 TgC Yr−1) in NPP was found during 2002 and a notable increase of 17% (1.61 TgC Yr−1) was seen during 2013 due to consecutive drought and surplus rainfall years respectively. The study suggests that consecutive droughts have brought an immense impact on vegetation productivity. During the drought years, dry sub-humid region was the most vulnerable as it was dominated by agriculture land, while semi-arid region was less affected due to forest cover. Despite many droughts, some part of north-west and south-west regions had shown an increase in vegetation carbon storage, which indicates that these parts are not affected by the drought. The study also suggests that in addition to rainfall, heat wave also played a major limiting factor in vegetation productivity. The study will be useful in identifying the regions which are more vulnerable to drought. Present study, will also be helpful in combating the regional climate change as vegetation carbon storage is directly linked with agricultural productivity.

Impact of land use/cover changes on carbon storage in a river valley in arid areas of Northwest China

Soil carbon pools could become a CO2 source or sink, depending on the directions of land use/cover changes. A slight change of soil carbon will inevitably affect the atmospheric CO2 concentration and consequently the climate. Based on the data from 127 soil sample sites, 48 vegetation survey plots, and Landsat TM images, we analyzed the land use/cover changes, estimated soil organic carbon (SOC) storage and vegetation carbon storage of grassland, and discussed the impact of grassland changes on carbon storage during 2000 to 2013 in the Ili River Valley of Northwest China. The results indicate that the areal extents of forestland, shrubland, moderate-coverage grassland (MCG), and the waterbody (including glaciers) decreased while the areal extents of high-coverage grassland (HCG), low-coverage grassland (LCG), residential and industrial land, and cultivated land increased. The grassland SOC density in 0–100 cm depth varied with the coverage in a descending order of HCG>MCG>LCG. The regional grassland SOC storage in the depth of 0–100 cm in 2013 increased by 0.25×1011 kg compared with that in 2000. The regional vegetation carbon storage (Srvc) of grassland was 5.27×109 kg in 2013 and decreased by 15.7% compared to that in 2000. The vegetation carbon reserves of the under-ground parts of vegetation (Sruvb) in 2013 was 0.68×109 kg and increased by approximately 19.01% compared to that in 2000. This research can improve our understanding about the impact of land use/cover changes on the carbon storage in arid areas of Northwest China.

Screening and evaluation of candidate trees for terrestrial carbon storage in regions with high air pollution and water stress

ABSTRACTTerrestrial carbon storage is one of many different ways to tackle the problem of greenhouse gases (GHG) emissions resulting from non-point sources. However, the development of large-scale urban forest acreage is not an easy undertaking, and will require significant resources. The systematic screening of candidate tree species and preliminary estimations of their atmospheric carbon removal potential can help stakeholders and policymakers devise site-specific strategies for developing and maintaining sustainable urban forest acreage.This study is focused on finding native candidate trees that are drought-resistant, and could continue to store (sequester) atmospheric carbon in significant quantities over an extended period (> 100 years). In the study, seven urban tree species were identified as the top candidates for terrestrial carbon storage in water-stressed Californian regions, which are also the regions with the worst air quality in the nation.Although the present study is focused on particular water-stressed and air-polluted regions of California, the methodology and strategies presented may serve as a starting point for launching site-specific scoping studies to evaluate the terrestrial carbon storage potential of future urban forest projects in other parts of the world.

Mapping Changes in Carbon Storage and Productivity Services Provided by Riparian Ecosystems of Semi-Arid Environments in Northwestern Mexico

We analyze the importance of riparian ecosystems (RE) as critical areas for carbon storage and productivity in semi-arid regions of Northwest Mexico. We calculated the carbon storage by land cover and compared temporal trends of basal productivity (MODIS) and pre-monsoon productivity (Landsat) of RE, to other land cover types. We used land cover maps generated previously for the region (years 1993, 2002, and 2011), assigning values of carbon stored in aerial and root biomass, as well as organic carbon stored in the soil. To estimate productivity (proxy), time series were generated using the Normalized Difference Vegetation Index (NDVI) values of Landsat 4–5 TM and MODIS for each land cover type. We found that RE stores 93,147 tC/ha, about 1.5 times the estimated storage for oak forest (65,048 tC/ha). Productivity of RE was similar to highly productive land cover types, such as agriculture and oak forest, and higher than in the rest of the ecosystems of the region. We also found that changes from RE to agriculture and cultivated grasslands represented a decrease in productivity (p < 0.001). Finally, we report a gradual decrease in basal productivity (p = 0.0151) and pre-monsoon productivity (p = 0.031) in the RE. These results help us understand that changes in land use, intensive use of water, and climate can influence the ecosystem services of productivity and carbon storage offered by RE in semi-arid areas.

A statistical analysis of spatiotemporal variations and determinant factors of forest carbon storage under China’s Natural Forest Protection Program

The Natural Forest Protection Program (NFPP) is one of the key ecological forestry programs in China. It not only facilitates the improvement of forest ecological quality in NFPP areas, but also plays a significant role in increasing the carbon storage of forest ecosystems. The program covers 17 provinces, autonomous regions, and municipalities with correspondingly diverse forest resources and environments, ecological features, engineering measures and forest management regimes, all of which affect regional carbon storage. In this study, volume of timber harvest, tending area, pest-infested forest, fire-damaged forest, reforestation, and average annual precipitation, and temperature were evaluated as factors that influence carbon storage. We developed a vector autoregression model for these seven indicators and we studied the dominant factors of carbon storage in the areas covered by NFPP. Timber harvest was the dominant factor influencing carbon storage in the Yellow and Yangtze River basins. Reforestation contributed most to carbon storage in the state-owned forest region in Xinjiang. In state-owned forest regions of Heilongjiang and Jilin Provinces, the dominant factors were forest fires and forest cultivation, respectively. For the enhancement of carbon sequestration capacity, a longer rotation period and a smaller timber harvest are recommended for the Yellow and Yangtze River basins. Trees should be planted in state-owned forests in Xinjiang. Forest fires should be prevented in state-owned forests in Heilongjiang, and greater forest tending efforts should be made in the state-owned forests in Jilin.

基于人工神经网络与空间仿真模拟的区域森林碳估算比较——以龙泉市为例

PDF HTML阅读 XML下载 导出引用 引用提醒 基于人工神经网络与空间仿真模拟的区域森林碳估算比较——以龙泉市为例 DOI: 10.5846/stxb201603010352 作者: 作者单位: 浙江农林大学,浙江农林大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（30972360，41201563）；浙江农林大学农林碳汇与生态环境修复研究中心预研基金；浙江省林业碳汇与计量创新团队项目（2012R10030-01）；浙江省林学一级重中之重学科学生创新计划项目资助（201515） Comparison of regional forest carbon estimation methods based on back- propagation neural network and spatial simulation: A case study in Longquan County Author: Affiliation: Zhejiang A & F University,Zhejiang A & F University 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:森林是生态系统的重要组成部分，准确估算森林碳储量及其分布对于评价森林生态系统的功能具有重要意义。以龙泉市为研究区，利用2009年99个森林资源清查样地数据和同年度 Landsat TM 影像数据，采用高斯序列协同仿真（SGCS）与BP神经网络方法（BPNN）分别模拟森林地上部分碳密度及其分布，并进行了对比分析。随机将样本数据分成70个建模样本和29个检验样本。通过模型检验，BP神经网络预测值与实测值的相关性达到0.67，相对均方根误差为0.63，空间仿真方法预测值与实测值的相关性为0.68，相对均方根误差为0.63，空间仿真方法预测能力略高于神经网络方法。仿真结果表明，基于BP神经网络模拟的森林碳总量为11042990 Mg，平均碳密度为36.10 Mg/hm2，总体森林碳密度均值高于样地平均值8.82%。基于空间仿真模拟的森林碳总量为11388657 Mg，平均碳密度为37.23 Mg/hm2，总体森林碳密度均值高于样地平均值9.40%。对比分析可知：高斯协同仿真模拟和BP神经网络虽然在碳总量估算值上与抽样数据估计值相近，但两种方法在估测值的频率分布以及研究区碳分布上有较大的差异。与BP神经网络相比，序列高斯协同模拟结果更接近系统抽样样地实测值，全部样地预测值与实测值的相关性达到0.75，在估计区域森林碳空间分布上有明显优势。在碳密度值域与频率分布方面，序列高斯协同模拟结果分布更合理。综上所述，序列高斯协同模拟在森林碳空间估计方面要优于BP神经网络。 Abstract:Quantifying the carbon stocks of forest is critical for understanding the dynamics of carbon fluxes in terrestrial ecosystems and the atmosphere as well as monitoring ecosystem responses to environmental changes. However, due to the lack of methods and data, results of forest carbon estimation from different studies shown large difference, which presents a great uncertainty in the evaluation of forest carbon sink. Different methods can be used to estimate the carbon storage in the same study area, which can be compared with the advantages and disadvantages of each method and provides guidance for forest carbon estimation. On the basis of National Forest Inventory (NFI) data and the Land-sat TM image data collected in Longquan County, Zhejiang Province in 2009, we applied two methods, namely error back-propagation neural network (BPNN) and sequential Gaussian co-simulation (SGCS) to reproduce the distribution of above-ground forest carbon. We randomly divided plots into two sets, a 70-plot set for modeling and a 29-plot set for testing. For the model test, the correlation coefficient of predictive value and the plot data was 0.67 and 0.68 for BPNN and SGCS, respectively. Both of the two methods have the same RRMSE value (0.63). The predictive ability of SGCS was slightly higher than that of BPNN. The estimation results using BPNN showed that the sum of above-ground carbon is 11042990 Mg and the mean carbon density was 36.10 Mg/hm2 which was higher than the average from the sample plots with a relative error of 8.82%. The SGCS showed that the sum of above-ground carbon was 11388657 Mg with a mean carbon density 37.23 Mg/hm2 which was higher than the average from the sample plots with a relative error of 9.4%. Comparative analysis showed the carbon densities estimated using these two methods are both close to that calculated from the NFI data. However, there were some differences between the two methods with respect to the estimation of the frequency distribution and the carbon distribution in the study area. Predictive value of sample plot obtained using the SGCS method was closer to the plot data value than that obtained using the BPNN. And the correlation between predictive value and the plot data was 0.75, which proved that there were obvious advantages in estimating the spatial distribution of forest carbon. In addition, in terms of carbon density range and frequency distribution, SGCS was more reliable. This study further verifies the effectiveness of the SGSC which could provide effective methods for the estimation of regional forest carbon storage. 参考文献 相似文献 引证文献

Carbon storage in US wetlands.

Wetland soils contain some of the highest stores of soil carbon in the biosphere. However, there is little understanding of the quantity and distribution of carbon stored in our remaining wetlands or of the potential effects of human disturbance on these stocks. Here we use field data from the 2011 National Wetland Condition Assessment to provide unbiased estimates of soil carbon stocks for wetlands at regional and national scales. We find that wetlands in the conterminous United States store a total of 11.52 PgC, much of which is within soils deeper than 30 cm. Freshwater inland wetlands, in part due to their substantial areal extent, hold nearly ten-fold more carbon than tidal saltwater sites—indicating their importance in regional carbon storage. Our data suggest a possible relationship between carbon stocks and anthropogenic disturbance. These data highlight the need to protect wetlands to mitigate the risk of avoidable contributions to climate change.

Soil aggregation and aggregate-associated carbon under four typical halophyte communities in an arid area.

The soil microbial biomass carbon (MBC) is considered as a sensitive index of soil carbon ecosystem. The distribution of aggregate-associated MBC determines the capacity of the soil to store soil organic carbon (SOC). We compared soil aggregate-associated SOC and aggregate-associated MBC under four halophyte communities: Karelinia caspia (Pall.) Less. (Abbr. K. caspia), Bassia dasyphylla (Fisch. et C. A. Mey.) Kuntze. (Abbr. B. dasyphylla), Haloxylon ammodendron (C. A. Mey.) Bunge. (Abbr. H. ammodendron), and Tamarix ramosissima Lour (Abbr. T. ramosissima) on an alluvial fan in the Manasi River Basin, Xinjiang, China. The specific objectives of the study were to determine which aggregate size fraction was the most important for MBC and SOC retention in these soils of four halophyte communities. The results showed that the 0.053-0.25mm fraction contained 47 to 75% of the total soil mass. The amount of soil in the 0.053-0.25mm fraction was significantly greater than that in the >0.25 and the <0.053mm fractions. The >0.25 and the <0.053mm fractions contained 7.8 to 43.0% of the soil mass. Aggregate-associated SOC concentrations ranged from 1.70 to 13.68gkg-1, and the aggregate-associated SOC were the highest under the H. ammodendron and T. ramosissima communities. The aggregate-associated MBC ranged from 55.26 to 217.11gkg-1, and the aggregate-associated MBC were higher under the K. caspia and B. dasyphylla communities. The aggregate-associated SOC concentrations were significantly higher in the >0.25 and the <0.053mm fractions than in the 0.053-0.25mm fraction. The aggregate-associated MBC in the 20-40cm depth was consistent with its law. However, in the 0-20cm depth, the aggregate-associated MBC concentrations were significantly higher in the >0.25mm fraction than the other two aggregate fractions, and there were no significant differences in 0.25-0.053 or <0.053mm fraction. Correlation analyses showed that the aggregate-associated MBC positively correlated with aggregate-associated SOC in >0.25mm fraction (P<0.01). The microbial entropies ranged from 1.12 to 4.17%, and the microbial entropy generally was higher in >0.25mm fraction. Overall, the H. ammodendron community had the higher aggregate-associated SOC and aggregate-associated MBC, but the microbial entropy was low. This suggested that among the four halophyte communities in this study, the H. ammodendron community could be beneficial for soil carbon storage in arid regions.

Degraded tropical rain forests possess valuable carbon storage opportunities in a complex, forested landscape

Tropical forests are major contributors to the terrestrial global carbon pool, but this pool is being reduced via deforestation and forest degradation. Relatively few studies have assessed carbon storage in degraded tropical forests. We sampled 37,000 m2 of intact rainforest, degraded rainforest and sclerophyll forest across the greater Wet Tropics bioregion of northeast Australia. We compared aboveground biomass and carbon storage of the three forest types, and the effects of forest structural attributes and environmental factors that influence carbon storage. Some degraded forests were found to store much less aboveground carbon than intact rainforests, whereas others sites had similar carbon storage to primary forest. Sclerophyll forests had lower carbon storage, comparable to the most heavily degraded rainforests. Our findings indicate that under certain situations, degraded forest may store as much carbon as intact rainforests. Strategic rehabilitation of degraded forests could enhance regional carbon storage and have positive benefits for tropical biodiversity.

Responses of two nonlinear microbial models to warming and increased carbon input

Abstract. A number of nonlinear microbial models of soil carbon decomposition have been developed. Some of them have been applied globally but have yet to be shown to realistically represent soil carbon dynamics in the field. A thorough analysis of their key differences is needed to inform future model developments. Here we compare two nonlinear microbial models of soil carbon decomposition: one based on reverse Michaelis–Menten kinetics (model A) and the other on regular Michaelis–Menten kinetics (model B). Using analytic approximations and numerical solutions, we find that the oscillatory responses of carbon pools to a small perturbation in their initial pool sizes dampen faster in model A than in model B. Soil warming always decreases carbon storage in model A, but in model B it predominantly decreases carbon storage in cool regions and increases carbon storage in warm regions. For both models, the CO2 efflux from soil carbon decomposition reaches a maximum value some time after increased carbon input (as in priming experiments). This maximum CO2 efflux (Fmax) decreases with an increase in soil temperature in both models. However, the sensitivity of Fmax to the increased amount of carbon input increases with soil temperature in model A but decreases monotonically with an increase in soil temperature in model B. These differences in the responses to soil warming and carbon input between the two nonlinear models can be used to discern which model is more realistic when compared to results from field or laboratory experiments. These insights will contribute to an improved understanding of the significance of soil microbial processes in soil carbon responses to future climate change.

Biogeographical diversification of mainland Asian Dendrobium (Orchidaceae) and its implications for the historical dynamics of evergreen broad‐leaved forests

AbstractAimEvergreen broad‐leaved forests (EBLFs) occupy most tropical and subtropical regions of mainland Asia and exhibit high species diversity, productivity and richness. Understanding the historical dynamics of EBLFs is important for biodiversity conservation and regional carbon storage and cycling under global climate change. However, little is known about the historical dynamics of EBLFs in mainland Asia. Dendrobium, an epiphytic orchid genus found in EBLFs, was used to gain new insights of the historical establishment and extension of EBLFs in mainland Asia.LocationMainland Asia.MethodsWe sampled c. 80% of the currently recognized species of Dendrobium found in mainland Asia. A phylogeny was generated using maximum parsimony, maximum likelihood and Bayesian inference methods. A calibrated chronogram was obtained using a Bayesian relaxed‐clock model approach. Biogeographical scenarios were investigated using the statistical dispersal–vicariance analysis and dispersal–extinction–cladogenesis methods. Ancestral states were constructed by mesquite and bayestraits, and diversification of Dendrobium was investigated by APE and LASER packages.ResultsOur results indicate that Asian Dendrobium was present on mainland Asia since the Oligocene, after which this genus diversified in this region and dispersed into higher elevations. The ancestral habit of Dendrobium was epiphytic and terrestrial and lithophytic habits each have multiple, recently independent origins.Main conclusionsOur results support the hypothesis that EBLFs have been established in mainland Asia at least since the Oligocene and further suggest that the EBLFs of mainland Asia expanded into higher elevations prior to the late Cenozoic. The diversification of Asian Dendrobium coincided with a warmer climate during the late Oligocene and middle Miocene and the expansion of key groups (including Fagaceae, Lauraceae, Magnoliaceae and Theaceae) of EBLFs during the early Cenozoic.

不同采样密度下县域森林碳储量仿真估计

不同采样密度下县域森林碳储量仿真估计

Assessing the potential impacts of urban expansion on regional carbon storage by linking the LUSD-urban and InVEST models

The timely and effective assessment of the impacts of urban expansion on regional carbon storage is an important issue in the fields of urban ecology and sustainability science. This study used a new model to assess the impacts of urban expansion on regional carbon storage by linking the LUSD-urban and InVEST models. First, the LUSD-urban model was used to simulate urban expansion. Then, the InVEST model was adopted to assess the impacts on regional carbon storage. The linked model combines the strengths of these two models. Not only can it simulate and project the process of urban expansion but it can also assess the impacts of urban expansion on regional carbon storage. A case study in Beijing showed that the relative error between the simulated carbon storage loss and the actual loss was less than 12%. We argue that the linked model can be applied to assess the ecological effects of future urban expansion.

An inexact optimization model for planning regional carbon capture, transportation and storage systems under uncertainty

CO2 capture and storage (CCS) is widely recognized as a climate-change mitigation technology that can significantly sequestrate human-induced CO2 emission. However, there are two main issues that affect the development and deployment of CCS in a region/country: one is the shortage of planning tool for supporting effective decision making regarding timing, sitting and scaling of CCS capture, transport and storage facilities as well as dynamic sink-source matching between capture and storage. The other is uncertainty in technical, economic, political and other dimensions of CCS as the technology is still in early stage of commercialization. Therefore, the objective of this study is to develop an inexact CCS optimization model (ICCSM) for supporting regional carbon capture, transportation and storage planning under interval-format uncertainty with a least-cost strategy. It could address issues related to optimal sink-source matching in a region with multiple capture and storage options. The developed model was then applied to a case study of long term regional CCS planning under uncertainty. To demonstrate its applicability and capability, further scenario analysis indicated that high concentration CO2 from coal-to-chemical/liquids/gas for EOR storage would be early opportunity for CCS in China. In addition, carbon price would be an effective policy instrument for encouraging deployment of CCS. Without sufficient carbon price, it could be difficult for moving CCS from demonstration stage to deployment stage in a short term.

Editorial: Organic carbon pools in permafrost regions on the Qinghai–Xizang (Tibetan) Plateau

Abstract. The current Northern Circumpolar Soil Carbon Database did not include organic carbon storage in permafrost regions on the Qinghai–Xizang (Tibetan) Plateau (QXP). In this study, we reported a new estimation of soil organic carbon (SOC) pools in the permafrost regions on the QXP up to 25 m depth using a total of 190 soil profiles. The SOC pools were estimated to be 17.3 ± 5.3 Pg for the 0–1 m depth, 10.6 ± 2.7 Pg for the 1–2 m depth, 5.1 ± 1.4 Pg for the 2–3 m depth and 127.2 ± 37.3 Pg for the layer of 3–25 m depth. The percentage of SOC storage in deep layers (3–25 m) on the QXP (80%) was higher than that (39%) in the yedoma and thermokarst deposits in arctic regions. In total, permafrost regions on the QXP contain approximately 160 ± 87 Pg SOC, of which approximately 132 ± 77 Pg (83%) stores in perennially frozen soils and deposits. Total organic carbon pools in permafrost regions on the QXP was approximately 8.7% of that in northern circumpolar permafrost region. The present study demonstrates that the total organic carbon storage is about 1832 Pg in permafrost regions on northern hemisphere.

Global vulnerability of peatlands to fire and carbon loss

Globally, the amount of carbon stored in peats exceeds that stored in vegetation and is similar in size to the current atmospheric carbon pool. Fire is a threat to many peat-rich biomes and has the potential to disturb these carbon stocks. Peat fires are dominated by smouldering combustion, which is ignited more readily than flaming combustion and can persist in wet conditions. In undisturbed peatlands, most of the peat carbon stock typically is protected from smouldering, and resistance to fire has led to a build-up of peat carbon storage in boreal and tropical regions over long timescales. But drying as a result of climate change and human activity lowers the water table in peatlands and increases the frequency and extent of peat fires. The combustion of deep peat affects older soil carbon that has not been part of the active carbon cycle for centuries to millennia, and thus will dictate the importance of peat fire emissions to the carbon cycle and feedbacks to the climate.

Responses of soil respiration to land use conversions in degraded ecosystem of the semi-arid Loess Plateau

A better understanding of the response of soil respiration to land-use conversion has important practical implications for ecological restoration in degraded regions. In this study, in situ soil respiration was monitored in a typical land-use sequence on a ridge slope in Wangdonggou watershed of the Loess Plateau, China, during a three-year period from 2011 to 2013. The land-use conversion sequences included cropland (control), apple orchard, grassland, and woodland. The results clearly showed that soil respiration and temperature sensitivity (Q10) varied significantly with land-use conversion. Soil respiration was decreased by 10% after conversion of cropland to orchard, and increased by 7–46% after conversion of cropland to grassland and woodland. Q10 was increased by 19% after conversion of cropland to woodland, and decreased by 9–26% after conversion of cropland to grassland and orchard. Soil respiration increased linearly with soil organic carbon (SOC) storage and fine root biomass (<2mm). The results indicated that root biomass and SOC storage were the major factors influencing Q10 after conversion of cropland to non-natural ecosystem, and substrate quality or root system adaptability may be the real reason for the difference in Q10 after conversion of cropland to natural grassland ecosystem. Although soil temperature and moisture significantly influenced soil respiration among the four typical land-use types, their difference derived from land-use conversions could not well explain the difference in soil respiration among land-use conversions. In conclusion, the increases in SOC storage and fine root biomass were the major factors influencing soil respiration among land-use conversions. Thus, conversion of cropland to natural grassland seemed to be the most effective integrated small watershed management to increase soil carbon storage and decrease CO2 concentration in the loess regions of China.

Biomass carbon storage and its sequestration potential of afforestation under natural forest protection program in China

Based on the data from China’s Seventh Forest Inventory for the period of 2004–2008, area and stand volume of different types and age-classes of plantation were used to establish the relationship between biomass density and age of planted forests in different regions of the country. Combined with the plantation area in the first-stage of the Natural Forest Protection (NFP) program (1998–2010), this study calculated the biomass carbon storage of the afforestation in the first-stage of the program. On this basis, the carbon sequestration potential of these forests was estimated for the second stage of the program (2011–2020). Biomass carbon storage of plantation established in the first stage of the program was 33.67 Tg C, which was majority accounted by protection forests (30.26 Tg C). There was a significant difference among carbon storage in different regions, which depended on the relationship of biomass carbon density, forest age and plantation area. Under the natural growth, the carbon storage was forecasted to increase annually from 2011 to 2020, reaching 96.03 Tg C at the end of the second-stage of the program in 2020. The annual growth of the carbon storage was forecasted to be 6.24 Tg C/yr, which suggested that NFP program has a significant potential for enhancing carbon sequestration in plantation forests under its domain.