Transformation of Organic Matter of the Larch Forest Soils in the Northern Taiga of Nizhne-Tungusskoe Plateau, Central Siberia

The evaluation of biospheric role of the boreal forests in the accumulation of carbon is connected with the evaluation of organic matter (OM) pool in soils. The research sites were larch forests, they are situated on Nizhne-Tungusskoe Plateau. Larch forests of feather-moss and lichen types (110 and 380 years old) were formed on 'ochric podbur' soils. Litter stocks are 3.5–4.5 kg m^{− 2} with thickness 10–25 cm. Cryomezomorphic northern taiga soils contains 38–73 t (carbon) ha^{− 1}. Pool of fast mineralized OM has average value 38.1 t (carbon) ha^{− 1}, including 20.5 and 6.4 t (Carbon) ha^{− 1} of labile compounds on surface and in the soil, and 11.2 t (carbon) ha^{− 1} of mobile OM. Microbial mass reaches 1.78–3.47 t (carbon) ha^{− 1}, its proportion is 3.6–4.9% of the total OM carbon. Zoomass of feather-moss larch forest is 0.20–0.61 * 10^{− 2}, in lichen larch forest −0.01–0.07 * 10^{− 2} t (carbon) ha^{− 1}. A pool of resistant to biological decomposition and bonded to mineral soil matrix OM is 17.7 t (carbon) ha^{− 1} and it varies from 18.6 to 29.0 in feather-moss larch forest, and from 6.4 to 17.0 t (carbon) ha^{− 1} in lichen larch forest. Two-years field experiment has been performed to determine transformation rates of various plant litter fractions and to clarify the role of soil biota in these processes. The results showed participation of all biota groups in the decomposition of plant residues caused weight loss of larch-needles and root mortmass. Isolation of organic matter from all-size invertebrate groups leads to some decrease of decomposition activity.     

A Simulation of Temporal and Spatial Variations in Carbon at Landscape Level: A Case Study for Lake Abitibi Model Forest in Ontario,Canada

Using a case study of the Lake Abitibi Model Forest (LAMF), this study aims to assess the temporal and spatial variability in carbon storage during 1990–2000, and to present a comprehensive estimation of the carbon budget for LAMF's ecosystems. As well, it provided the information needed by local forest managers to develop ecological and carbon-based indicators and monitor the sustainability of forest ecosystems. Temporal and spatial carbon dynamics were simulated at the landscape level using ecosystem model TRIPLEX1.0 and Geographical Information System (GIS). The simulated net primary productivity (NPP) and carbon storage in forest biomass and soil were compared with field data and results from other studies for Canada's boreal forests. The results show that simulated NPP ranged from 3.26 to 3.34 tC ha⁻¹ yr⁻¹ in the 1990s and was consistent with the range measured during the Boreal Ecosystem-Atmosphere Studies (BOREAS) in central Canada. Modeled NPP was also compared with the estimation from remote sensing data. The density of total above-and belowground biomass was 125.3, 111.8, and 106.5 tC ha⁻¹ for black spruce, trembling aspen, and jack pine in the LAMF ecosystem, respectively. The total carbon density of forested land was estimated at 154.4 tC ha⁻¹ with the proportion of 4:6 for total biomass and soil. The analysis of net carbon balance of ecosystem suggested that the LAMF forest ecosystem was acting as a carbon sink with an allowable harvest in the 1990s.     

Carbon Sequestration by Carbonization of Biomass and Forestation: Three Case Studies

We proposed the carbon sink project called “Carbon Sequestration by Forestation and Carbonization (CFC),” which involves biomass utilization and land conservation by incorporating the products of biomass carbonization into the agents for soil improvement, water purification, etc. Our purpose was to demonstrate the potential of the CFC scheme for carbon sequestration, particularly carbon storage in soil. Case studies were conducted in both developing and developed countries. 1. In southern Sumatra, Indonesia, 88,369 Mg-C year⁻¹ of wood residue from a plantation forest and excess bark from a pulp mill would be converted into 15,571 Mg-C year⁻¹ of the net carbon sink by biochar for soil improvement. The fixed carbon recovery of the system is 21.0%. 2. In a semiarid region in western Australia, the carbonization of wood residue was incorporated with multipurpose projects of a mallee eucalyptus plantation that involved the function of salinity prevention. During the project period of 35 years, the total carbon sink would reach 1,035,450 Mg-C with 14.0% by aboveground biomass, 33.1% by belowground biomass and 52.8% by biochar in soil. 3. In southern Kyushu, Japan, the study was focused on the effective use of surplus heat from a garbage incinerator for carbonizing woody materials. Sawdust of 936.0 Mg-C year⁻¹ would be converted into the net carbon sink of 298.5 Mg-C year⁻¹ by carbonization, with the fixed carbon recovery of the system being 31.9%. Consequently, the CFC project could encourage the creation of a carbon sink in soil. However, we recognize that the quality standard of biochar, the stability of biochar in soil, and the methods for monitoring biochar utilization must be clarified before incorporating biochar carbon into the carbon credit system. Throughout this article (except for diagrams and in citation details) carbonized biomass is, with the authors'agreement, called ‘biochar’ in lieu of the commonly used but misleading word ‘charcoal’ (Editor).     

Baseline Carbon Stocks Assessment and Projection of Future Carbon Benefits of a Carbon Sequestration Project in East Timor

Climate change is one of the most pressing environmental problems humanity is facing today. Forest ecosystems serve as a source or sink of greenhouse gases, primarily CO₂. With support from the Canadian Climate Change Fund, the Community-based Natural Resource Management for Carbon Sequestration project in East Timor (CBNRM-ET) was implemented to “maintain carbon (C) stocks and increase C sequestration through the development of community-based resource management systems that will simultaneously improve livelihood security”. Project sites were in the Laclubar and Remexio Sub-districts of the Laclo watershed. The objective of this study was to quantify baseline C stocks and sequestration benefits of project components (reforestation with fast-growing species, primarily Casuarina equisetifolia, and agroforestry involving integration of Paraserianthes falcataria). Field measurements show that mature stands (≥30 years) of P. falcataria and C. equisetifolia contain up to 200 Mg C ha⁻¹ in above ground biomass, indicating the vast potential of project sites to sequester carbon. Baseline C stocks in above ground biomass were very low in both Laclubar (6.2 Mg C ha⁻¹ for reforestation sites and 5.2 Mg C ha⁻¹ for agroforestry sites and Remexio (3.0 Mg C ha⁻¹ for reforestation and 2.5 Mg C ha⁻¹ for agroforestry). Baseline soil organic C levels were much higher reaching up to 160 Mg C ha⁻¹ in Laclubar and 70 Mg C ha⁻¹ in Remexio. For the next 25 years, it is projected that 137 671 Mg C and 84 621 Mg C will be sequestered under high- and low C stock scenarios, respectively.     

Carbon storage versus fossil fuel substitution: a climate change mitigation option for two different land use categories based on short and long rotation forestry in India

Short rotation bioenergy crops for energy production are considered an effective means to mitigate the greenhouse effect, mainly due to their ability to substitute fossil fuels. Alternatively, carbon can be sequestered and stored in the living biomass. This paper compares the two land use categories (forest land and non-forest land) for two management practices (short rotation vs. long rotation) to study mitigation potential of afforestation and fossil fuel substitution as compared to carbon storage. Significant carbon benefit can be obtained in the long run from using lands for growing short rotation energy crops and substituting fossil fuels by the biomass thus produced, as opposed to sequestering carbon in the biomass of the trees. When growth rates are high and harvest is used in a sustainable manner (i.e., replanting after every harvest), the opportunities for net carbon reductions appear to be fossil fuel substitution, rather than storage in ecosystem biomass. Our results suggest that at year 100 a total of 216 Mg C ha⁻¹ is sequestered for afforestation/reforestation using long rotation sal (Shorea robusta Gaertn.f) species, as opposed to offset of 412 Mg C ha⁻¹ for carbon storage and fossil fuel substitution for short rotation poplar (Populus Deltoides Marsh) plantations. The bioenergy option results in a continuous stream of about 3 Mg C ha⁻¹ yr⁻¹ of carbon benefits per year on forest land and 4 Mg C ha⁻¹ yr⁻¹ on non-forest land. Earlier studies have shown that in India waste land availability for establishing energy plantations is in the range of 9.6 to 36.5 Mha. Thus, using the 758 Tg biomass per year generated from 9.6 Mha waste land gives a mitigation potential in the range of 227 to 303 Tg C per year for carbon storage and fossil fuel substitution from poplar plantation for substituting coal based power generation. Depending upon the land availability for plantation, the potential for energy generation is in the range of 11,370 PJ, possibly amounting to a bioenergy supply of 43% of the total projected energy consumption in 2015. Further studies are needed to estimate the mitigation potential of other species with different productivities for overall estimation of the economic feasibility and social acceptability in a tropical country like India.     

Quantification of net primary production of Chinese forest ecosystems with spatial statistical approaches

Net primary production (NPP) of terrestrial ecosystems provides food, fiber, construction materials, and energy to humans. Its demand is likely to increase substantially in this century due to rising population and biofuel uses. Assessing national forest NPP is of importance to best use forest resources in China. To date, most estimates of NPP are based on process-based ecosystem modeling, forestry inventory, and satellite observations. There are little efforts in using spatial statistical approaches while large datasets of in-situ observed NPP are available for Chinese forest ecosystems. Here we use the surveyed forest NPP and ecological data at 1,266 sites, the data of satellite forest coverage, and the information of climate and topography to estimate Chinese forest NPP and their associated uncertainties with two geospatial statistical approaches. We estimate that the Chinese forest and woodland ecosystems have total NPP of 1,325 ± 102 and 1,258 ± 186 Tg C year⁻¹ in 1.57 million km² forests with a regression method and a kriging method, respectively. These estimates are higher than the satellite-based estimate of 1,034 Tg C year⁻¹ and almost double the estimate of 778 Tg C year⁻¹ using a process-based terrestrial ecosystem model. Cross-validation suggests that the estimates with the kriging method are more accurate. Our developed geospatial statistical models could be alternative tools to provide national-level NPP estimates to better use Chinese forest resources.     

Potential nitrogen enrichment of soil and surface water by atmospheric ammonia sorption in intensive livestock production areas

Elevated atmospheric NH₃ levels near intensive livestock operations can add significant N to local agroecosystems. In this study, the potential atmospheric NH₃ sorbed by soil and water was assessed over a 2-year period starting October 2000 in an intensive livestock production area in southern Alberta, Canada. Fifty-two uneven grid sampling sites were selected in the 53,905 ha study area. The sorption rate of atmospheric NH₃ was estimated weekly by exposing distilled water and air-dried soil samples to the atmosphere at the sampling sites. The increases in NH₄–N content in the samples after 1-week exposure was regarded as an index of the atmospheric NH₃ sorbed for that week. The NH₃ sorption rates were highly variable across the 52 sites, with water ranging from 4 to 125 kg ha⁻¹ year⁻¹ with a mean of 22 kg N ha⁻¹ year⁻¹ and soil from 5 to 84 kg N ha⁻¹ year⁻¹ with a mean of 20 kg N ha⁻¹ year⁻¹. Considerable variation in NH₃–N sorption across the study area reflects the effects of size, direction (upwind or downwind) and proximity of nearby livestock operations or other NH₃ sources and operators’ activities around the sampling sites. The NH₃ sorption rate at each site also varied considerably in response to weather conditions. The high rate of NH₃ input poses a direct risk of surface water eutrophication in intensive livestock operation areas. If fertilizer recommendations are not reduced to account for NH₃ sorption by soil, excess N may also contribute to eutrophication through runoff and leaching.     

长白山树线交错带的生物量分配和净生产力

随山地垂直带海拔上升,环境恶化会影响到植物生物量的绝对量和相对量的分配,进而影响到生态系统的碳平衡。测定了位于长白山北坡海拔1900m树线交错带的两个林分:长白落叶松混交林和岳桦林的生物量分配和净生产力,并与低海拔相似林分进行了比较,探讨树线特殊环境下树木的生长反应和生态系统的碳投资策略。树线交错带林分生物量和生产力都出现急剧降低,冠层树干生物量比例急剧降低,而枝、叶生物量比例有显著增加。而根系比例和地下/地上生物量比在两种林分表现出不同的反应,树线落叶松混交林出现急剧增加,而树线岳桦林与低海拔岳桦林相比没有显著差别。枝、叶生物量比例增加,特别是叶生物量分配增加有利于在树线恶劣环境的碳吸收和碳平衡,是对树线交错带大风、积雪等恶劣气候的可塑性适应,树木在树线出现多分枝、矮曲生长型。树线地带落叶松混交林和岳桦林的净生产量也出现急剧降低,但根系生产量比例则较低海拔同类林分高,有利于对土壤中水分和养分的吸收。     

Variability of Fire Behavior, Fire Effects, and Emissions in Scotch Pine Forests of Central Siberia

As part of the Russian FIRE BEAR (Fire Effects in the Boreal Eurasia Region) Project, replicated 4-ha experimental fires were conducted on a dry Scotch pine (Pinus sylvestris)/lichen (Cladonia sp.)/feathermoss (Pleurozeum schreberi) forest site in central Siberia. Observations from the initial seven surface fires (2000-2001) ignited under a range of burning conditions quantified the different fuel consumption and fire behavior characteristics (e.g., rate of spread, fireline intensity, etc.) possible in this particular forest fuel type. Experimental results and dendrochronological study of local fire history both support the dominance of local fire regimes by low to moderate-intensity surface fires. Carbon released by the experimental fires ranged from 4.8 to 15.4 t C ha^{− 1} depending on fuel conditions and fire severity. Preliminary emission data show a strong correlation between carbon dioxide (CO₂) and carbon monoxide (CO) emissions, which should facilitate accurate estimates of fire impacts on atmospheric chemistry. Carbon concentration in smoke samples was related to fire severity. The short landscape-scale fire-return interval (50 years), combined with typically low fire severity, in pine ecosystems of central Siberia is often associated with low tree mortality and relatively rapid buildup of litter and understory fuels after a fire.     

‘Carbon stocks in a Scots pine afforestation under different thinning intensities management’

Thinning, as a forest management strategy, may contribute towards mitigating climate change, depending on its net effect on forest carbon (C) stocks. Although thinning provides off-site C storage (in the form of wood products) it is still not clear whether it results in an increase, a reduction or no change in on-site C storage. In this study we analyze the effect of thinning on C stocks in a long-term experiment. Different thinning intensities (moderate, heavy and unthinned) have been applied over the last 30 years in a Scots pine (Pinus sylvestris L.) stand, with a thinning rotation period of 10 years. The main C compartments were analyzed: above and belowground tree biomass, deadwood, forest floor and upper 30-cm of the mineral soil and tree biomass removed in thinning treatments. The results revealed that unthinned stands had the highest C stocks with 315 Mg C ha^?1, moderate thinning presented 304 Mg C ha^?1 and heavy thinning 296 Mg C ha^?1, with significant differences between unthinned and heavily thinned stands. These differences were mainly due to C stock in live biomass, which decreased with thinning intensity. However, soil C stocks, forest floor and mineral soil, were not influenced by thinning, all of the stands displaying very similar values 102–107 Mg C ha^?1 for total soil; 15–19 Mg C ha^?1 for forest floor; 87–88 Mg C ha^?1 for mineral soil). These results highlight the sustainability of thinning treatments in terms of C stocks in this pinewood afforestation, and provide valuable information for forest management aimed at mitigating climate change.     

昆明市食物生产消费碳素动态变化

食物生产消费系统中碳素的梯级流动变化会产生一系列环境影响.基于1990—2013年昆明市食物生产消费变化,测算分析了农业生产的碳汇碳排量、城乡居民食物碳消费动态变化及食物碳消费带来的环境负荷变化.结果表明,食物生产系统中碳汇和碳排总量分别由1990年的705.44 Gg·a~(-1)和496.92 Gg·a~(-1)增长至2013年的1195.53 Gg·a~(-1)和1012.33 Gg·a~(-1),净碳汇水平为正值,但呈下降趋势;城镇居民人均食物碳消费量由61.42 kg·人~(-1)·a~(-1)减少至44.65 kg·人~(-1)·a~(-1),农村居民人均食物碳消费量由87.96 kg·人~(-1)·a~(-1)降至48.78 kg·人~(-1)·a~(-1),食物碳消费总量由336.00 Gg·a~(-1)波动下降到294.53 Gg·a~(-1).畜禽养殖粪便排放和肠道发酵是食物生产过程中的主要碳源,占到60%以上,其次是农用物资投入所产生的碳排放,约占30%,并呈增加态势,其中,化肥是农用物资碳排放的主要影响因素.食物消费造成的碳素环境负荷中,损失进入大气的碳素比例最高,占到80%,其次是土壤,最少的是水体.进入大气的碳素由1990年的270.63 Gg·a~(-1)波动下降至2013年的170.68 Gg·a~(-1),减少了36.93%,但进入土壤和水体的碳素明显增长,其中,厨余垃圾碳量由35.42 Gg·a~(-1)增加至129.84 Gg·a~(-1),增加了266.57%.昆明市作为低碳城市试点,需要采取针对性措施发展低碳农业及低碳消费.     

Greenhouse gas emissions in restored secondary tropical peat swamp forests

Restoration of deforested and drained tropical peat swamp forests is globally relevant in the context of reducing emissions from deforestation and forest degradation. The seasonal flux of carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) in a restoration concession in Central Kalimantan, Indonesia, was measured in the two contrasting land covers: shrubs and secondary forests growing on peatlands. We found that land covers had high, but insignificantly different, soil carbon stocks of 949?+?56 and 1126?+?147 Mg ha^?1, respectively. The mean annual CO₂ flux from the soil of shrub areas was 52.4?±?4.1 Mg ha^?1 year^?1, and from secondary peat swamp forests was 42.9?±?3.6 Mg ha^?1 year^?1. The significant difference in mean soil temperature in the shrubs (31.2 °C) and secondary peat swamp forests (26.3 °C) was responsible for the difference in total CO₂ fluxes of these sites. We also found the mean annual total soil respiration was almost equally partitioned between heterotrophic respiration (20.8?+?1.3 Mg ha^?1 year^?1) and autotrophic respiration (22.6?+?1.5 Mg ha^?1 year^?1). Lowered ground water level up to ??40 cm in both land covers caused the increase of CO₂ fluxes to 40–75%. These numbers contribute to the provision of emission factors for rewetted organic soils required in the national reporting using the 2013 Supplement of the 2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines for wetlands as part of the obligation under the United Nations Framework Convention on Climate Change (UNFCCC).

     

Global warming potential of emissions from rice paddies in Northeastern China

In this study, paddy fields in Jilin province which are flooded parcel of arable lands used for growing rice (Oryza sativa Linn.) were selected as the object. Long-term exploitation of paddy fields led to variations of soil organic carbon (SOC) and green house gases (GHGs) emissions which might contribute to global warming. In order to calculate the amount of global warming potentials (GWPs) of emissions from ricepaddies and find the correlations among rice yield, SOC storage and GWP, DeNitrification-DeComposition (DNDC) model was used to simulate SOC densities and fluxes of main GHGs emitted from paddy fields. After verification, simulation results were used to calculate SOC storages and 100-year GWPs from 1949 to 2009. Results indicated that SOC densities in depths of 0–10 cm, 10–20 cm and 20–30 cm all kept increasing. Average methane (CH₄) and nitrous oxide (N₂O) fluxes were 278.55 kg carbon (kgC) ha⁻¹ a⁻¹ and 2.22 kg nitrogen (kgN) ha⁻¹ a⁻¹. The SOC storage (0–30 cm) had increased from 3.96 × 10⁹kgC in 1949 to 47.85 × 10⁹kgC in 2009. In addition, GWP emission was increasing exponentially in the past 61 years, from 0.16 × 10⁶ Mg carbon dioxide equivalents (CO₂-equivalents) to 66.36 × 10⁶ Mg CO₂-equivalents. Both SOC storage and GWP presented obviously linear relation to rice yields. Overall, the research suggested that long-term rice yields could be used to estimate the SOC storage and GWP variations.     

Nutrient cycling within the developing oil palm-legume ecosystem

Oil palms (Elaeis guineensis Jacq.) are normally planted in fields stripped of all other vegetation. Leguminous cover crops are planted simultaneously to protect the soil surface and to provide other, less tangible benefits. Nutrient cycling, especially of nitrogen, was followed in a commercial oil palm plantation and showed that: (a) legumes contribute about 150 kg nitrogen ha^?1 year^?1 to the system through nitrogen fixation; (b) during the early stages of oil palm growth the legumes absorb 149 kg nitrogen ha^?1 year^?1 from the soil; (c) with a loss of nitrogen through litter fall of 123 kg nitrogen ha^?1 year^?1, legumes accumulate a net amount of 176 kg nitrogen ha^?1 year^?1 in their foliage; (d) in comparison with “natural” covers, leguminous covers reduce leaching losses by 63 kg nitrogen ha^?1 year ^?1 so that the total benefits of leguminous covers amount to 239 kg nitrogen ha^?1 year^?1; (e) the combined inputs from fertilization and oil palm debris in plots without legumes is 208 kg nitrogen ha^?1 year^?1; and (f) during the initial growth phase, oil palms need only 175 kg nitrogen ha^?1 year^?1. Since legumes fix nitrogen and thoroughly scavenge the soil for minerals they eventually provide more nitrogen to the oil palms than is needed for growth. This surplus nitrogen is “banked” in the legume foliage. Then, when the rooting system of the oil palms has grown under the inter-rows, competition for nutrients causes a gradual decline in the cover-crop. Nutrients “deposited” in the legumes are thus slowly re-released stimulating root-growth and general development of the oil palm.     

Bamboo in climate change and rural livelihoods

Climate change negotiations, assessments, and greenhouse gas inventory guidelines have all but bypassed bamboo. Disallowing stands of tree-like bamboos as forests disparages their function in the carbon (C) cycle, and disregards pillars of smallholder livelihoods. Exposing bamboo not as a panacea, but as an overlooked option for C conservation, sequestration, and adaptation, we screen details of distribution, morphology, growth, physiology, and impacts for pertinence to climate change. Additional to 40 million hectares of existing bamboo forests, many potential host countries for C projects harbor suitable sites. Definitions, methods and default values, such as the root/shoot- ratio, biomass conversion factors, allometric equations and sampling variables need adjusting. Rapid maturation, persistent rhizomes, a rich palette of species, and wind-firmness may mitigate risk. Bamboos can accommodate agro-and urban forestry, and reign in unsustainable shifting cultivation. Distribution functions of bamboo biomass stocks and growths do not deviate drastically from those of trees. If anything, bamboo stocks are slightly lower, and growths slightly higher, with medians of 87 t*ha⁻¹ and 10.5 t*ha⁻¹*yr⁻¹, respectively. However, bamboo’s outstanding socio-economic effects might well determine its future in mitigation and adaptation. Early, continuous yields, selective harvesting on even small parcels of land, low capital and high labor intensity, virtually 100% conversion efficiency to about 1,500 products, and, typically, 75% of economic returns benefiting rural people are advantageous attributes. Regional studies on suitability, silviculture, yields, economics, risk, and C assessment would strengthen bamboo’s function as ‘the poor man’s timber’ and promote its niche as the smallholder’s C sink.     

Greenhouse gas emissions from rice based cropping systems: Economic and technologic challenges and opportunities

Recent market slump in rice, less rainfall during monsoon, high temperature and scarcity of water during dry season leads to lower grain yield and less profit from rice cultivation in India. Farmers’ grow upland crops like chickpea (Cicer arietinum), greengram (Vigna radiate), mustard (Brassica nigra), corn (Zea maize), pigeonpea (Cajanus cajan), potato (Solanum tuberosum), sunflower (Helianthus annuus) etc. along with rice (Oryza sativa) during the dry season. However, knowledge of greenhouse gas (GHG) emission from these rice based cropping systems is very limited. In the present study four rice based cropping systems was studied along with rice-rice rotation system as control in respect of GHG emission, yield potential and economic feasibility. Conventional plantation and fertilizer application methodology was followed for each crop. Methane (CH₄) and nitrous oxide (N₂O) flux from field plots were studied with conventional closed chamber method using gas chromatograph. CH₄ flux was recorded highest from rice-rice rotation plots (304.25 kg ha⁻¹). N₂O flux was recorded 1.02 kg ha⁻¹ from rice-rice rotation system during wet season. However, during wet season, higher N₂O flux (1.93 kg ha⁻¹) was recorded from rice-potato-sesame rotation plots. Annual N₂O flux was also recorded significantly low (3.42 kg ha⁻¹) from rice-rice rotation plots and high (6.19 kg ha⁻¹) from rice-chickpea-greengram rotation plots. Significantly lower annual grain yield was recorded from rice-rice rotation plots (9.25 Mg ha⁻¹) whereas it was 18.84 Mg rice eq ha⁻¹ from rice-potato-sesame rotation system. The global warming potential (GWP) of rice-rice rotation system was recorded significantly high (8.62 Mg CO₂ ha⁻¹) compare to plots with different rice based cropping systems. Computing all C-emission from cradle-to-grave, highest total C-cost was recorded from the rice-rice rotation system ($62.00 ha⁻¹). We have made an attempt to calculate the C-credit of different rice based cropping systems by considering the difference of C-cost with control. The study suggests that the rice-potato-sesame is most sustainable among different cropping system studied in terms of economic profit ($62.00 ha⁻¹). We have made an attempt to calculate the C-credit of different rice based cropping systems by considering the difference of C-cost with control. The study suggests that the rice-potato-sesame is most sustainable among different cropping system studied in terms of economic profit (1248.21 ha⁻¹) and C-credit ($38.60 ha⁻¹). The result of the study may be limited to the study region; however, the study has potential use in respect to the development of agriculture practice for adaptation to climate change.     

Bio-char Sequestration in Terrestrial Ecosystems – A Review

The application of bio-char (charcoal or biomass-derived black carbon (C)) to soil is proposed as a novel approach to establish a significant, long-term, sink for atmospheric carbon dioxide in terrestrial ecosystems. Apart from positive effects in both reducing emissions and increasing the sequestration of greenhouse gases, the production of bio-char and its application to soil will deliver immediate benefits through improved soil fertility and increased crop production. Conversion of biomass C to bio-char C leads to sequestration of about 50% of the initial C compared to the low amounts retained after burning (3%) and biological decomposition (< 10–20% after 5–10 years), therefore yielding more stable soil C than burning or direct land application of biomass. This efficiency of C conversion of biomass to bio-char is highly dependent on the type of feedstock, but is not significantly affected by the pyrolysis temperature (within 350–500 ^∘C common for pyrolysis). Existing slash-and-burn systems cause significant degradation of soil and release of greenhouse gases and opportunies may exist to enhance this system by conversion to slash-and-char systems. Our global analysis revealed that up to 12% of the total anthropogenic C emissions by land use change (0.21 Pg C) can be off-set annually in soil, if slash-and-burn is replaced by slash-and-char. Agricultural and forestry wastes such as forest residues, mill residues, field crop residues, or urban wastes add a conservatively estimated 0.16 Pg C yr⁻¹. Biofuel production using modern biomass can produce a bio-char by-product through pyrolysis which results in 30.6 kg C sequestration for each GJ of energy produced. Using published projections of the use of renewable fuels in the year 2100, bio-char sequestration could amount to 5.5–9.5 Pg C yr⁻¹ if this demand for energy was met through pyrolysis, which would exceed current emissions from fossil fuels (5.4 Pg C yr⁻¹). Bio-char soil management systems can deliver tradable C emissions reduction, and C sequestered is easily accountable, and verifiable.     

Simulated dynamics of carbon stocks driven by changes in land use, management and climate in a tropical moist ecosystem of Ghana

Sub-Saharan Africa is large and diverse with regions of food insecurity and high vulnerability to climate change. This project quantifies carbon stocks and fluxes in the humid forest zone of Ghana, as a part of an assessment in West Africa. The General Ensemble biogeochemical Modeling System (GEMS) was used to simulate the responses of natural and managed systems to projected scenarios of changes in climate, land use and cover, and nitrogen fertilization in the Assin district of Ghana. Model inputs included historical land use and cover data, historical climate records and projected climate changes, and national management inventories. Our results show that deforestation for crop production led to a loss of soil organic carbon (SOC) by 33% from 1900 to 2000. The results also show that the trend of carbon emissions from cropland in the 20th century will continue through the 21st century and will be increased under the projected warming and drying scenarios. Nitrogen (N) fertilization in agricultural systems could offset SOC loss by 6% with 30 kg N ha⁻¹ year⁻¹ and by 11% with 60 kg N ha⁻¹ year⁻¹. To increase N fertilizer input would be one of the vital adaptive measures to ensure food security and maintain agricultural sustainability through the 21st century.     

长白山自然保护区生态系统碳平衡研究

运用已建立的EPPML生物地球化学循环模型,对1995年长白山自然保护区生态系统的碳平衡状况进行了模拟.模拟结果表明,该保护区植被的年净初级生产力[NPP(碳量)]为1.332×10⁶t·a^-1,以阔叶红松林和云冷杉林最高,分别为0.540×10⁶t·a^-1和0.428×10⁶t·a^-1.这2种林型是长白山面积最大、生产力最高的林型,其生产力的模拟结果对整个保护区的碳循环和碳平衡影响最大,前者的准确性决定了后者的可靠性.总的来说,模拟值不仅在整个保护区不同植被带和气候带的相对比较中是符合常规的,而且在与相当分散的实测数据的绝对比较中也是比较准确的.该保护区的植被具有明显的碳汇功能,主要表现为植被碳量的增长,每年增长约1.058×10⁶t·a^-1.阔叶红松林的年碳量增长最大(0.452 × 10⁶t·a^-1),云冷杉林其次(0.339×10⁶t·a^-1)这2种林型对整个保护区的碳汇功能起着至关重要的决定性作用.其它依次为:长白落叶松林、阔叶林、草甸、灌丛、高山苔原、岳桦林和高山流砾滩草类.1995年该保护区土壤有机质的分解碳量比凋落物碳量高0.169×10⁶t·a^-1,除草灌土壤出现有机质的积累,高山苔原和高山流砾滩土壤有机质的分解与积累处于近似平衡状态外,乔木林下土壤有机质的分解量均为凋落物量的1.5～2.0倍.     

Estimating net primary production and annual plant carbon inputs, and modelling future changes in soil carbon stocks in arable farmlands of northern Japan

Soil C sequestration in croplands is deemed to be one of the most promising greenhouse gas mitigation options for Japan's agriculture. In this context, changes in soil C stocks in northern Japan's arable farming area over the period of 1971-2010, specifically in the region's typical Andosol (volcanic ash-derived) and non-Andosol soils, were simulated using soil-type-specific versions of the Rothamsted carbon model (RothC). The models were then used to predict the effects, over the period of 2011-2050, of three potential management scenarios: (i) baseline: maintenance of present crop residue returns and green manure crops, as well as composted cattle manure C inputs (24-34 Mg ha⁻¹ yr⁻¹ applied on 3-55% of arable land according to crop), (ii) cattle manure: all arable fields receive 20 Mg ha⁻¹ yr⁻¹ of composted cattle manure, increased C inputs from crop residues and present C inputs from green manure are assumed, and (iii) minimum input: all above-ground crop residues removed, no green manure crop, no cattle manure applied. Above- and below-ground residue biomass C inputs contributed by 8 major crops, and oats employed as a green manure crop, were drawn from yield statistics recorded at the township level and crop-specific allometric relationships (e.g. ratio of above-ground residue biomass to harvested biomass on a dry weight basis). Estimated crop net primary production (NPP) ranged from 1.60 Mg C ha⁻¹ yr⁻¹ for adzuki bean to 8.75 Mg C ha⁻¹ yr⁻¹ for silage corn. For the whole region (143 × 10³ ha), overall NPP was estimated at 952 ± 60 Gg C yr⁻¹ (6.66 ± 0.42 Mg C ha⁻¹ yr⁻¹). Plant C inputs to the soil also varied widely amongst the crops, ranging from 0.50 Mg C ha⁻¹ yr⁻¹ for potato to 3.26 Mg C ha⁻¹ yr⁻¹ for winter wheat. Annual plant C inputs to the soil were estimated at 360 ± 45 Gg C yr⁻¹ (2.52 ± 0.32 Mg C ha⁻¹ yr⁻¹), representing 38% of the cropland NPP. The RothC simulations suggest that the region's soil C stock (0-30 cm horizon), across all soils, has decreased from 13.96 Tg C (107.5 Mg C ha⁻¹ yr⁻¹) in 1970 to 12.46 Tg C (96.0 Mg C ha⁻¹ yr⁻¹) in 2010. For the baseline, cattle manure and minimum input scenarios, soil C stocks of 12.13, 13.27 and 9.82 Tg C, respectively, were projected for 2050. Over the period of 2011-2050, compared to the baseline scenario, soil C was sequestered (+0.219 Mg C ha⁻¹ yr⁻¹) by enhanced cattle manure application, but was lost (−0.445 Mg C ha⁻¹ yr⁻¹) under the minimum input scenario. The effect of variations of input data (monthly mean temperature, monthly precipitation, plant C inputs and cattle manure C inputs) on the uncertainty of model outputs for each scenario was assessed using a Monte Carlo approach. Taking into account the uncertainty (standard deviation as % of the mean) for the model's outputs for 2050 (5.1-6.1%), it is clear that the minimum input scenario would lead to a rapid decrease in soil C stocks for arable farmlands in northern Japan.