Root- and peat-based CO2 emissions from oil palm plantations

Measured carbon dioxide (CO₂) flux from peat soils using the closed chamber technique combines root-related (autotrophic + heterotrophic where rhizosphere organisms are involved) and peat-based (heterotrophic) respiration. The latter contributes to peat loss while the former is linked to recent CO₂ removal through photosynthesis. The objective of this study was to separate root- from peat-based respiration. The study was conducted on peatland under 6 and 15 year old oil palm (Elaeis guineensis Jacq.) plantations in Jambi Province, Indonesia in 2011 to 2012. CO₂ emissions were measured in the field from 25 cm diameter and 25 cm tall closed chambers using an infrared gas analyser. Root sampling and CO₂ emissions measurements were at distances of 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, and 4.5 m from the centre of the base of the palm tree. The emission rate for the six and 15 year old oil palm plantations at ≥3.0 m from the centre of the tree were 38.2?±?9.5 and 34.1?±?15.9 Mg CO₂ ha^?1 yr^?1, respectively. At distances <2.5 m, total respiration linearly decreased with distances from the trees. Heterotrophic respirations were 86 % of the 44.7?±?11.2 and 71 % of 47.8?±?21.3 Mg CO₂ ha^?1 yr^?1 of weighted surface flux, respectively for the 6 and 15 year old plantations. We propose that CO₂ flux measurements in oil palm plantations made at a distance of ≥3 m from the tree centre be used to represent the heterotrophic respiration that is relevant for the environmental impact assessment.     

CO2 emissions from tropical drained peat in Sumatra,Indonesia

With the increasing use of tropical peatland for agricultural development, documentation of the rate of carbon dioxide (CO₂) emissions is becoming important for national greenhouse gas inventories. The objective of this study was to evaluate soil-surface CO₂ fluxes from drained peat under different land-use systems in Riau and Jambi Provinces, Sumatra, Indonesia. Increase of CO₂ concentration was tracked in measurement chambers using an Infrared Gas Analyzer (IRGA, LI-COR 820 model). The results showed that CO₂ flux under oil palm (Elaeis guineensis) plantations ranged from 34?±?16 and 45?±?25 Mg CO₂ ha^–1 year^–1 in two locations in Jambi province to 66?±?25 Mg CO₂ ha^–1 year^–1 for a site in Riau. For adjacent plots within 3.2 km in the Kampar Peninsula, Riau, CO₂ fluxes from an oil palm plantation, an Acacia plantation, a secondary forest and a rubber plantation were 66?±?25, 59?±?19, 61?±?25, 52?±?17 Mg ha^–1 year^–1, respectively, while on bare land sites it was between 56?±?30 and 67?±?24 Mg CO₂ ha^–1 year^–1, indicating no significant differences among the different land-use systems in the same landscape. Unexplained site variation seems to dominate over land use in influencing CO₂ flux. CO₂ fluxes varied with time of day (p?<?0.001) with the noon flux as the highest, suggesting an overestimate of the mean flux values with the absence of night-time measurements. In general, CO₂ flux increased with the depth of water table, suggesting the importance of keeping the peat as wet as possible.     

Is CO2 flux from oil palm plantations on peatland controlled by soil moisture and/or soil and air temperatures?

Measurements of carbon dioxide (CO₂) flux at the soil surface of oil palm (Elaeis guineensis Jacq.) plantations on peatlands typically exhibit considerable temporal and spatial variation, which challenges the derivation of emission factors required in land use discussions. We tested 20 cm surface soil moisture content, and the diurnal patterns in soil and air temperatures as CO₂ flux controls during an annual measurement schedule in a 15-year-old oil palm plantation in Jambi Province, Sumatra, Indonesia. A total of 480 CO₂ flux measurements were obtained using an Infrared Gas Analyser (IRGA) at six different time intervals each day. Samples were recorded at 20 observation points distributed along four transects located 15, 42, 50, 70, and 84 m from the edge of the drainage canal. Results showed CO₂ flux exhibited no relationship to soil and air temperature, however values tended to increase with volumetric soil moisture content; the highest annual flux of 55 Mg ha^?1 yr^?1 was observed at mid-day, when air temperature was highest, and lowest at dawn when soil and air temperatures were lowest. CO₂ flux decreased consistent with distance from the drainage canal, suggesting a higher flux with a deeper water table. This result indicates a shallow water table must be maintained. The annual mean CO₂ flux of 46?±?30 Mg CO₂ ha^?1 yr^?1 was comparable to other studies, and can be set as a baseline emissions factor for areas with similar land use and peat characteristics.     

Peat emission control by groundwater management and soil amendments: evidence from laboratory experiments

Peat respiration that releases carbon dioxide (CO₂) to the atmosphere contributes to regional and global change. Aeration associated with soil water content levels controls emission rates, but soil amendments might mitigate respiration. The objectives of this study were to examine the effects of various water content levels and laterite application on microbial (heterotrophic) respiration in peat soil. Bulk samples of surface (0–20 cm depth) and subsurface (30–50 cm depth) layers were collected from an oil palm plantation in Riau Province, Indonesia. Peat water content was adjusted to 20, 40, 60, 80, and 100 % water filled pore space (WFPS). Laterite soil (clay containing high Al and Fe oxides) was applied to 3, 6, and 12 mg g^?1 dry weight (1.2, 2.4, and 4.8 Mg ha^?1) peat samples at 60 % and 100 % WFPS. Results showed peat respiration was notably affected by water content, but less affected by laterite application. Peat respiration increased sharply from wet (≥80 % WFPS) to moist soil (60 to 40 % WFPS), and decreased when soil dried (≤40 % WFPS). Laterite as a peat ameliorant accelerated rather than reduced peat respiration, and is therefore not a viable choice for CO₂ emissions reduction.     

Mediterranean shrublands carbon sequestration: environmental and economic benefits

To date, only a few attempts have been done to estimate the contribution of Mediterranean ecosystems to the global carbon cycle. Within this context, shrub species, composition and structure of the Mediterranean shrublands developing along the Latium coast (Italy) were analyzed in order to evaluate their contribution to carbon (C) sequestration, also taking into consideration the economic benefits at a national level. The considered shrublands had a shrub density of 1,200?±?500 shrubs ha^?1. Shrubs were classified into small (S), medium (M) and large (L), according to their volume (V) and leaf area index (LAI). The total yearly carbon dioxide (CO₂) sequestration per species (SC_y) was calculated multiplying the total photosynthetic leaf surface area (spt) of each species by the mean yearly photosynthetic rate and the total yearly photosynthetic activity time (in hours). Q. ilex and A. unedo had the highest SC_y (46.2?±?15.8 kg CO₂ year^?1, mean value), followed by P. latifolia (17.5?±?6.2 kg CO₂ year^?1), E. arborea, E. multiflora, C. incanus, P. lentiscus, R. officinalis, and S. aspera (6.8?±?4.2 kg CO₂ year^?1, mean value). The total yearly CO₂ sequestration per shrub (SC_shy) was 149?±?5 kg CO₂ year^?1 in L, decreasing 30 % in M and 80 % in S shrubs. Taking into account the frequency of S, M and L and their SC_shy, the total CO₂ sequestration of the Mediterranean maquis was quantified in 80 Mg CO₂ ha^?1?year^?1, corresponding to 22 Mg C ha^?1?year^?1. From a monetary viewpoint, this quantity could be valued to more than 500 US$ ha^?1?year^?1. Extending this benefit to the Mediterranean shrublands throughout the whole country, we obtained a nationwide estimated annual benefit in the order of $500 million.     

Impacts of land use,restoration, and climate change on tropical peat carbon stocks in the twenty-first century: implications for climate mitigation

The climate mitigation potential of tropical peatlands has gained increased attention as Southeast Asian peatlands are being deforested, drained and burned at very high rates, causing globally significant carbon dioxide (CO₂) emissions to the atmosphere. We used a process-based dynamic tropical peatland model to explore peat carbon (C) dynamics of several management scenarios within the context of simulated twenty-first century climate change. Simulations of all scenarios with land use, including restoration, indicated net C losses over the twenty-first century ranging from 10 to 100 % of pre-disturbance values. Fire can be the dominant C-loss pathway, particularly in the drier climate scenario we tested. Simulated 100 years of oil palm (Elaeis guineensis) cultivation with an initial prescribed burn resulted in 2400–3000 Mg CO₂?ha^?1 total emissions. Simulated restoration following one 25-year oil palm rotation reduced total emissions to 440–1200 Mg CO₂?ha^?1, depending on climate. These results suggest that even under a very optimistic scenario of hydrological and forest restoration and the wettest climate regime, only about one third of the peat C lost to the atmosphere from 25 years of oil palm cultivation can be recovered in the following 75 years if the site is restored. Emissions from a simulated land degradation scenario were most sensitive to climate, with total emissions ranging from 230 to 10,600 Mg CO₂?ha^?1 over 100 years for the wettest and driest dry season scenarios, respectively. The large difference was driven by increased fire probability. Therefore, peat fire suppression is an effective management tool to maintain tropical peatland C stocks in the near term and should be a high priority for climate mitigation efforts. In total, we estimate emissions from current cleared peatlands and peatlands converted to oil palm in Southeast Asia to be 8.7 Gt CO₂ over 100 years with a moderate twenty-first century climate. These emissions could be minimized by effective fire suppression and hydrological restoration.     

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).

     

Will funding to Reduce Emissions from Deforestation and (forest) Degradation (REDD+) stop conversion of peat swamps to oil palm in orangutan habitat in Tripa in Aceh,Indonesia?

Tripa is the last remaining peat-swamp forest that harbours a potentially viable Sumatran orangutan (Pongo abelii) sub-population in a formally but not effectively protected area. It appears to be a simple showcase where current efforts to financially support reducing emissions from deforestation and forest degradation (REDD+) converge with biodiversity and social co-benefits. In practice, however, situation is more complex. REDD+ efforts interact with global palm oil trade and regulatory approaches (the moratorium) to achieve national goals for emissions reduction under umbrella of nationally appropriate mitigation actions (NAMA). To contextualize this debate, we assessed (i) land-use history and formal basis of palm-oil companies’ rights; (ii) carbon (C) stocks, historical emission levels and potential emissions that can be avoided; (iii) economic benefits of land-use options and opportunity costs of avoiding emissions; (iv) biodiversity and environmental services; and (v) alternative options for “high C stock development” and employment generation. Natural forest cover declined (54 % in 1995, 18 % in 2009) while oil palm increased 4–39 %. Aboveground C stocks decreased from 148 Mg ha^?1 in 1990 to 61 Mg ha^?1 in 2009, leading to average annual emissions of 14.5 Mg (carbon dioxide) CO₂e ha^?1 year^?1. While 41 % of these emissions yield less than American Dollar (USD) 5 of current economic benefits per Mg CO₂e emitted and might be compensated by REDD+, nearly all new emissions derive from a breach of existing laws, regulations and voluntary palm-oil standards. Substantial investment in alternative employment is needed, rather than carbon payments per se, to support livelihoods in a low carbon emissions economy.     

Methane and CO2 fluxes from an Indonesian peatland used for sago palm (Metroxylon sagu Rottb.) cultivation: Effects of fertilizer and groundwater level management

Tropical peatland is a vast potential land source for biological production, but peatland is a major natural source of greenhouse gases, especially methane (CH₄). It is important to evaluate the changes in greenhouse gas emissions induced by cultivation practices for sustainable agricultural use of tropical peatland. We investigated the effects of fertilizer application and the groundwater level on CH₄ and carbon dioxide (CO₂) fluxes in an Indonesian peat soil. The crop cultivated was sago palm (Metroxylon sagu Rottb.), which can grow on tropical peat soil without drainage and yield great amounts of starch. CH₄ emission through sago palm plants was first estimated by collecting gas samples immediately after cutting sago suckers using the closed chamber method. The CH₄ fluxes ranged from negative values to 1.0 mg C m⁻² h⁻¹. The mean CH₄ flux from treatment with macroelements (N, P, and K) and microelements (B, Cu, Fe, and Zn) applied at normal rates did not differ significantly from that of the No fertilizer treatment, although increasing the application rates of macroelements or microelements by 10-fold increased the CH₄ flux by a factor of two or three. The relationship between CH₄ flux and the groundwater table was regressed to a logarithmic equation, which indicated that to maintain a small CH₄ flux, the groundwater table should be maintained at <−45 cm. The CO₂ fluxes ranged between 24 and 150 mg C m⁻² h⁻¹, and were not significantly affected by either fertilizer treatments or the groundwater level. The inclusion of sago palm suckers in a chamber increased CH₄ emission from the peat soil significantly. Thus, gas emissions mediated by certain kinds of palm plants should not be disregarded.     

Estimating soil carbon storage and mitigation under temperate coniferous forests in the southern region of Kashmir Himalayas

Soil physical and chemical properties were quantified to assess soil organic carbon (SOC) density (t ha^-1) and SOC CO2 mitigation (t ha^-1) under six forest strata Cedrus deodara (closed) (S1), Cedrus deodara (open) (S2), Abies pindrow-Picea smithiana (closed) (S3), Abies pindrow-Picea smithiana (open) (S4), Pinus wallichiana (closed) (S5) and Pinus wallichiana (open) (S6) in the southern region of Kashmir Himalayas India. Lowest average bulk density (D_b) of 0.95 was found same in S3 (σ?±?0.07) and S5 (σ?±?0.09) and highest D_b (1.08) was observed in S2 (σ?±?0.05). A relatively higher coarse fraction was observed in all the six strata ranging from 19.23 (SD?±?4.66) in S3 to 29.37 (σ?±?6.12) in S6. Soil pH ranged from 6.09 (σ?±?0.64) in S4 to 6.97 (σ?±?0.53) in S2. The region under biotic interference has observed significant deforestation and degradation in the past two decades leading to lower SOC% values compared to other studies in the adjoining regions of Indian Himalayas and temperate coniferous forests in general. SOC% values were observed to range from 1.03 (σ?±?0.22) in S2 to 2.25 (σ?±?0.23) in S3. SOC density ranged between 25.11 (σ?±?5.41) t ha^-1 in S2 and 51.93 (σ?±?5.24) t ha^-1 in S3. SOC CO2 mitigation density was found highest 190.59 (σ?±?19.23) t ha^-1 in S3 and lowest 92.16 (σ?±?19.86) t ha^-1 in S2. A significant variation was observed in SOC density within strata. SOC density values in closed strata in general exceed to those in open strata. Primary results indicate that the average SOC stock for all the strata is low due to continuous biotic pressure in the last two decades making it a potential region for SOC buildup under plus options of REDD + (Reducing emissions from deforestation and forest degradation) which includes conservation, sustainable management of forests and enhancement of forest carbon (C) stocks.     

Carbon storage and sequestration potential of selected tree species in India

A dynamic growth model (CO2FIX) was used for estimating the carbon sequestration potential of sal (Shorea Robusta Gaertn. f.), Eucalyptus (Eucalyptus Tereticornis Sm.), poplar (Populus Deltoides Marsh), and teak (Tectona Grandis Linn. f.) forests in India. The results indicate that long-term total carbon storage ranges from 101 to 156 Mg C?ha^?1, with the largest carbon stock in the living biomass of long rotation sal forests (82 Mg C?ha^?1). The net annual carbon sequestration rates were achieved for fast growing short rotation poplar (8 Mg C?ha^?1?yr^?1) and Eucalyptus (6 Mg C?ha^?1?yr^?1) plantations followed by moderate growing teak forests (2 Mg C?ha^?1?yr^?1) and slow growing long rotation sal forests (1 Mg C?ha^?1?yr^?1). Due to fast growth rate and adaptability to a range of environments, short rotation plantations, in addition to carbon storage rapidly produce biomass for energy and contribute to reduced greenhouse gas emissions. We also used the model to evaluate the effect of changing rotation length and thinning regime on carbon stocks of forest ecosystem (trees?+?soil) and wood products, respectively for sal and teak forests. The carbon stock in soil and products was less sensitive than carbon stock of trees to the change in rotation length. Extending rotation length from the recommended 120 to 150 years increased the average carbon stock of forest ecosystem (trees?+?soil) by 12%. The net primary productivity was highest (3.7 Mg ha^?1?yr^?1) when a 60-year rotation length was applied but decreased with increasing rotation length (e.g., 1.7 Mg ha^?1?yr^?1) at 150 years. Goal of maximum carbon storage and production of more valuable saw logs can be achieved from longer rotation lengths. ‘No thinning’ has the largest biomass, but from an economical perspective, there will be no wood available from thinning operations to replace fossil fuel for bioenergy and to the pulp industry and such patches have high risks of forest fires, insects etc. Extended rotation lengths and reduced thinning intensity could enhance the long-term capacity of forest ecosystems to sequester carbon. While accounting for effects of climate change, a combination of bioenergy and carbon sequestration will be best to mitigation of CO₂ emission in the long term.     

The Tropical Peatland Plantation-Carbon Assessment Tool: estimating CO2 emissions from tropical peat soils under plantations

Land use change on Indonesian peatlands contributes to global anthropogenic greenhouse gas (GHG) emissions. Accessible predictive tools are required to estimate likely soil carbon (C) losses and carbon dioxide (CO₂) emissions from peat soils under this land use change. Research and modelling efforts in tropical peatlands are limited, restricting the availability of data for complex soil model parameterisation and evaluation. The Tropical Peatland Plantation-Carbon Assessment Tool (TROPP-CAT) was developed to provide a user friendly tool to evaluate and predict soil C losses and CO₂ emissions from tropical peat soils. The tool requires simple input values to determine the rate of subsidence, of which the oxidising proportion results in CO₂ emissions. This paper describes the model structure and equations, and presents a number of evaluation and application runs. TROPP-CAT has been applied for both site specific and national level simulations, on existing oil palm and Acacia plantations, as well as on peat swamp forest sites to predict likely emissions from future land use change. Through an uncertainty and sensitivity analysis, literature reviews and comparison with other methods of estimating soil C losses, the paper identifies opportunities for future model development, bridging between different approaches to predicting CO₂ emissions from tropical peatlands under land use change. TROPP-CAT can be accessed online from www.redd-alert.eu in both English and Bahasa Indonesia.     

An assessment of carbon stock for various land use system in Aravally mountains, Western India

Reducing carbon emissions from deforestation and degradation in developing countries is of the central importance in efforts to combat climate change. A study was conducted to measure carbon stocks in various land-use systems including forms and reliably estimates the impact of land use on carbon (C) stocks in the forest of Rajasthan, western India (23°3′–30°12′N longitude and 69°30′–78°17′E). 22.8% of India is forested and 0.04% is the deforestation rate of India. In Indian forest sector of western India of Aravally mountain range covered large area of deciduous forest and it’s very helpful in carbon sequestration at global level. The carbon stocks of forest, plantation (reforestation) and agricultural land in aboveground, soil organic and fine root within forest were estimated through field data collection. Results revealed that the amount of total carbon stock of forests (533.64?±?37.54 Mg·ha^?1, simplified expression of Mg (carbon) ·ha^?1) was significantly greater (P?<?0.05) than the plantation (324.37?±?15.0 Mg·ha^?1) and the agricultural land (120.50?±?2.17 Mg·ha^?1). Soil organic carbon in the forests (172.84?±?3.78 Mg·ha^?1) was also significantly greater (P?<?0.05) than the plantation (153.20?±?7.48 Mg·ha^?1) and the agricultural land (108.71?±?1.68 Mg·ha^?1). The differences in carbon stocks across land-use types are the primary consequence of variations in the vegetation biomass and the soil organic matter. Fine root carbon was a small fraction of carbon stocks in all land-use types. Most of the soil organic carbon and fine root carbon content was found in the upper 30-cm layer and decreased with soil depth. The aboveground carbon (ABGC): soil organic carbon (SOC): fine root carbon ratios (FRC), was 8:4:1, 4:5:1, and 3:37:1 for the forest, plantation and agricultural land, respectively. These results indicate that a relatively large proportion of the C loss is due to forest conversion to agricultural land.     

CH4 emission model from the waste of Sus Domesticus and Gallus Domesticus in Nigerian local farms: environmental implications and prospects

The potential of CH₄ (methane) greenhouse gas (GHG) emissions based on a model of prevailing behavioural pattern of livestock waste management in Nigerian local farms was investigated in this paper. Livestock waste, from Sus domesticus, pig, and Gallus domesticus, poultry, were employed as substrates in the study which uses water from a fish rearing farm as the matrix medium to simulate wastewater pool/river environment. A substrate to fish-water ratio of 1:3 by mass was used in developed laboratory-size digesting reactor system with U-tube water displacement, to facilitate volumetric readings of gas production, for each mix of the livestock waste. Volumetric readings from these, at ambient temperature conditions in the retention time of 32 days, follow the Normal probability density function, in accordance with Kolmogorov-Smirnov goodness-of-fit criteria. These readings showed that CH₄-containing gas as high as 67.3?×?10^?3 dm³ was produced on the 14th day from the pig and 86.8?×?10^?3 dm³ on the 13th day from the poultry substrates. The overall CH₄-containing gas productions of 255.4?×?10^?3 dm³/kg and 323.58?×?10^?3 dm³/kg were observed for the pig and the poultry substrates, respectively. A 70% scale-up analysis, modelled from these results, for the nation yield potential emission of about 4 kg CH₄ (that could be as potent as 84 kg CO₂-equivalent) annually. The environmental implications on global warming and possible prospects of recoverable domestic benefits from the waste through the adoption of sustainable policy of livestock waste managements for mitigating the CH₄ emissions in Nigerian local farms are presented.     

Low carbon emission development strategies for Jambi,Indonesia: simulation and trade-off analysis using the FALLOW model

Economic growth in rural areas has to align with preservation of land uses that optimise environmental services. This means that trade-offs between economic and ecological priorities need to be understood, quantified and managed. We aimed to estimate the trade-off in the Tanjung Jabung Barat district of Jambi province Indonesia, where traditional agroforestry systems on both peat and mineral soils and logged-over forests give way to monocultural plantations of pulpwood and oil palm (Elaeis guineensis). Simulations of a 30-year time period of four scenarios using the FALLOW (Forests, Agroforests, Low-value-Landscape, Or, Wastelands) model show that a business-as-usual scenario of economic growth unhindered by the application of conservation scenarios will lead to high carbon dioxide CO₂ emissions. The forest and agroforest protection scenario, with moderate assumptions for peat-based emissions, had opportunity costs of 3–100 USD/t CO₂e. This occurred especially when the establishment of oil palm plantations, which are currently the most profitable land use option in the area, is directed solely to under utilized mineral soils. The high trade-off values are difficult to reconcile when relying only on C trading mechanism to offset economic opportunity costs of not converting forests and/or agroforests to plantations. We conclude that law-based protection of existing forests, investment in intermediate intensity agroforestry options that utilize locally adapted trees and do not require drainage of peatlands, and re-introduction of tapping Jelutung (Dyera sp) latex as non-timber peat forest product, are needed in the Tanjabar district to provide options that are sustainable from both ecological and economic perspectives.     

Government environmental control measures on CO2 emission during the 2014 Youth Olympic Games in Nanjing: Perspectives from a top-down approach

Strict air pollution control measures were conducted during the Youth Olympic Games（YOG） period at Nanjing city and surrounding areas in August 2014.This event provides a unique chance to evaluate the effect of government control measures on regional atmospheric pollution and greenhouse gas emissions.Many previous studies have observed significant reductions of atmospheric pollution species and improvement in air quality,while no study has quantified its synergism on anthropogenic CO₂...     

闽江河口潮汐沼泽湿地CO_2排放通量特征

以闽江河口区面积最大的鳝鱼滩湿地分布的3种植物沼泽湿地：土著种咸草（Cyperus malaccensis Lam.var.brevifolius Bocklr.）沼泽湿地、芦苇（Phragmites australis）沼泽湿地及外来入侵种互花米草（Spartina alterniflora Loisel.）沼泽湿地...     

Palm oil and the emission of carbon-based greenhouse gases

The current use of South Asian palm oil as biofuel is far from climate neutral. Dependent on assumptions, losses of biogenic carbon associated with ecosystems, emission of CO₂ due to the use of fossil fuels and the anaerobic conversion of palm oil mill effluent currently correspond in South Asia with an emission of about 2.8–19.7 kg CO₂ equivalent per kg of palm oil. Using oil palm and palm oil processing wastes for the generation of energy and preventing further conversion of tropical forest into oil palm plantations by establishing new plantations on non-peaty degraded soils can, however, lead to large cuts in the emission of carbon-based greenhouse gases currently associated with the palm oil lifecycle.     

Planning hydrological restoration of peatlands in Indonesia to mitigate carbon dioxide emissions

Extensive degradation of Indonesian peatlands by deforestation, drainage and recurrent fires causes release of huge amounts of peat soil carbon to the atmosphere. Construction of drainage canals is associated with conversion to other land uses, especially plantations of oil palm and pulpwood trees, and with widespread illegal logging to facilitate timber transport. A lowering of the groundwater level leads to an increase in oxidation and subsidence of peat. Therefore, the groundwater level is the main control on carbon dioxide emissions from peatlands. Restoring the peatland hydrology is the only way to prevent peat oxidation and mitigate CO₂ emissions. In this study we present a strategy for improved planning of rewetting measures by dam constructions. The study area is a vast peatland with limited accessibility in Central Kalimantan, Indonesia. Field inventory and remote sensing data are used to generate a detailed 3D model of the peat dome and a hydrological model predicts the rise in groundwater levels once dams have been constructed. Successful rewetting of a 590 km2 large area of drained peat swamp forest could result in mitigated emissions of 1.4–1.6 Mt CO₂ yearly. This equates to 6% of the carbon dioxide emissions by civil aviation in the European Union in 2006 and can be achieved with relatively small efforts and at low costs. The proposed methodology allows a detailed planning of hydrological restoration of peatlands with interesting impacts on carbon trading for the voluntary carbon market.     

Anthropogenic land use substantially increases riverine CO2 emissions

Carbon dioxide (CO₂) emissions from inland waters to the atmosphere are a pivotal component of the global carbon budget. Anthropogenic land use can influence riverine CO₂ emissions, but empirical data exploring cause-effect relationships remain limited. Here, we investigated CO₂ partial pressures (pCO₂) and degassing in a monsoonal river (Yue River) within the Han River draining to the Yangtze in China. Almost 90% of river samples were supersaturated in CO₂ with a mean ± standard deviation of 1474 ± 1614 µatm, leading to emissions of 557 - 971 mmol/m²/day from river water to the atmosphere. Annual CO₂ emissions were 1.6 - 2.8 times greater than the longitudinal exports of riverine dissolved inorganic and organic carbon. pCO₂ was positively correlated to anthropogenic land use (urban and farmland), and negatively correlated to forest cover. pCO₂ also had significant and positive relationships with total dissolved nitrogen and total dissolved phosphorus. Stepwise multiple regression models were developed to predict pCO₂. Farmland and urban land released nutrients and organic matter to the river system, driving riverine pCO₂ enrichment due to enhanced respiration in these heterotrophic rivers. Overall, we show the crucial role of land use driving riverine pCO₂, which should be considered in future large-scale estimates of CO₂ emissions from streams. Land use change can thus modify the carbon balance of urban-river systems by enhancing river emissions, and reforestation helps carbon neutral in rivers.