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.     

A little REDD model to quickly compare possible baseline and policy scenarios for reducing emissions from deforestation and forest degradation

A simple model allows rapid comparison of typical baseline and policy scenarios which might be considered under international programs to avoid CO₂ emissions caused by forest clearing, such as REDD (Reducing Emissions from Deforestation and Forest Degradation). These tests of REDD policy scenarios can also include CO₂ stored in forest products. The value of avoided emissions can also be determined if expected carbon prices, constant or varying, are included. The paper discusses simple illustrative example comparisons as well as possible feedback effects within larger scale setting of CO₂ offset availability, CO₂ price and emissions reductions.     

On international equity in reducing emissions from deforestation

Reducing emissions from deforestation and forest degradation (REDD) can be an effective and efficient means of mitigating climate change. However, the perceived equity in the distribution of financial incentives for REDD could also emerge as a critical issue in international negotiations. The design of reference levels, which provide the benchmark for crediting emissions reductions, affects the economic incentives for national participation in a REDD mechanism and thus the overall willingness to reach an agreement on REDD. This paper compares the equity impacts of five proposed reference level designs using a partial-equilibrium model. Tradeoffs among equity, environmental effectiveness and cost-efficiency indicate the proposals trigger similar aggregate emissions reductions but lead to different outcomes in efficiency and alternative measures of equity. If equity across countries is measured as the financial incentive provided relative to a country's forest carbon stock, then a REDD mechanism compensating a uniform share of at-risk carbon stocks is the most equitable. On the other hand, if equity is evaluated as the financial incentive relative to the opportunity costs of participating in REDD, then the most equitable approach would be compensating emissions reductions but withholding a part of the payments to compensate for carbon stocks, which also encourages broader country participation under our model.     

Implications of uncertainty and scale in carbon emission estimates on locally appropriate designs to reduce emissions from deforestation and degradation (REDD+)

This study combined uncertainty analysis of carbon emissions with local stakeholders' perspectives to develop an effective Reducing Emission from Deforestation and Degradation (REDD+) scheme at the district level. Uncertainty of carbon emission estimates depends on scale while local stakeholders' views on plausible REDD+ schemes influence and limit transaction costs. The uncertainty analysis formed the basis for determining an appropriate scale for monitoring carbon emission estimates as performance measures for REDD+ incentives. Our analysis of stakeholder’ perspectives explored (i) potential location and activities for lower emission development pathways, and (ii) perceived fair allocation of REDD+incentives. Our case study focused on frontier forest in Tanjung Jabung Barat District, Jambi, Indonesia. The uncertainty analysis used Monte Carlo simulation techniques using known inaccuracy of land cover classification and variation in carbon stocks assessment per land cover type. With decreasing spatial resolution of carbon emission maps, uncertainty in carbon estimates decreased. At 1 km² resolution uncertainty dropped below 5 %, retaining most of the coarser spatial variation in the district. Fairness, efficiency and transaction cost issues in the design of REDD+ mechanisms were readily recognized by local stakeholders, who converged on an equal allocation to short-term efficiency (emission reduction activities) and long-term fairness (alternative livelihood development). A striking difference occurred in desirable transaction costs (which include monitoring, reporting and verification), with Non-Governmental Organizations (NGOs) aiming for 8 %, while government and researchers accepted transaction costs of 40 %. Feasible measures for emission reduction in the district, derived from a participatory planning process, are compatible with the 1 km² spatial resolution of performance measures.     

Drivers of deforestation and REDD+ benefit-sharing: A meta-analysis of the (missing) link

REDD+ (reducing emissions from deforestation and forest degradation and related forest activities) is a climate change mitigation mechanism currently being negotiated under the United Nations Framework Convention on Climate Change (UNFCCC). It calls for developed countries to financially support developing countries for their actions to reduce forest-sector carbon emissions. In this paper, we undertake a meta-analysis of the links, if any, between multiple and diverse drivers of deforestation operating at different levels and the benefits accruing from and being shared through REDD+ projects. We do so by assessing the nature of this link in (a) scholarly analysis, through an in-depth analysis of the posited relationship between drivers and REDD+ benefit-sharing, as examined in the peer-reviewed literature; and (b) in policy practice, through analysing how this link is being conceptualised and operationalised, if at all, in REDD+ project design documents. Our meta-analysis suggests that while some local, direct drivers and a few regional indirect drivers of deforestation and forest degradation are being targeted by specific REDD+ interventions and associated benefit-sharing mechanisms at the project-level, most national and international indirect drivers are not. We conclude that the growing academic analyses of REDD+ projects do not (as yet) advance viable theories of change, i.e. there is currently little focus on how REDD+ benefits could play a transformative role in catalysing action on drivers.     

Potential and Cost of Carbon Sequestration in the Tanzanian Forest Sector

The forest sector in Tanzania offers ample opportunities to reduce greenhouse gas emissions (GHG) and sequester carbon (C) in terrestrial ecosystems. More than 90% of the country's demand for primary energy is obtained from biomass mostly procured unsustainably from natural forests. This study examines the potential to sequester C through expansion of forest plantations aimed at reducing the dependence on natural forest for wood fuel production, as well as increase the country's output of industrial wood from plantations. These were compared ton conservationoptions in the tropical and miombo ecosystems. Three sequestrationoptions were analyzed, involving the establishment of short rotation and long rotation plantations on about 1.7 × 10⁶ hectares. The short rotation community forestry option has a potential to sequester an equilibrium amount of 197.4 × 10⁶ Mg C by 2024 at a net benefit of 79.5 × 10⁶, while yielding a NPV of 0.46 Mg^-1 C. The long rotation options for softwood and hardwood plantations will reach an equilibrium sequestration of 5.6 and 11.8 × 10⁶ Mg C at a negative NPV of 0.60 Mg^-1 C and 0.32 Mg^-1 C. The three options provide cost competitive opportunities for sequestering about 7.5 × 10⁶ Mg C yr^-1 while providing desired forest products and easing the pressure on the natural forests in Tanzania. The endowment costs of the sequestration options were all found to be cheaper than the emission avoidance cost for conservation options which had an average cost of 1.27 Mg^-1 C, rising to 7.5 Mg^-1 C under some assumptions on vulnerability to encroachment. The estimates shown here may represent the upper bound, because the actual potential will be influenced by market prices for inputs and forest products, land use policy constraints and the structure of global C transactions.     

Reducing emissions from deforestation and forest degradation plus (REDD+) in the Philippines: will it make a difference in financing forest development?

There is a high level of interest in reducing emissions from deforestation and forest degradation plus (REDD+) carbon (C) financing as a way to accelerate forest conservation and development. However, there is very limited information on the potential costs and benefits of REDD+ in developing countries like the Philippines. In this paper, we estimated the range of likely financial benefits of REDD+ implementation in the country under various forest degradation and mitigation scenarios. Our findings show that reducing the rate of forest degradation by a modest 5 to 15 % annually while increasing the doubling the rate of reforestation to 1.5 % annually could reduce C emissions by up to about 60 million t C by 2030. These are equivalent to US$ 97 to 417 million of mean C credits annually at US$ 5 per ton C. These figures are much higher than the total budget of the government and official development assistance for forestry activities in the country which amounted to US$ 46 million in 2005 and US$ 12 million in 2006, respectively. We conclude that REDD+ C credits could be a significant source of financing for forestry projects in developing countries like the Philippines.     

Mercury accumulation and dynamics in montane forests along an elevation gradient in Southwest China

Understanding atmospheric mercury (Hg) accumulation in remote montane forests is critical to assess the Hg ecological risk to wildlife and human health. To quantify impacts of vegetation, climatic and topographic factors on Hg accumulation in montane forests, we assessed the Hg distribution and stoichiometric relations among Hg, carbon (C), and nitrogen (N) in four forest types along the elevation of Mt. Gongga. Our results show that Hg concentration in plant tissues follows the descending order of litter > leaf, bark > root > branch > bole wood, indicating the importance of atmospheric Hg uptake by foliage for Hg accumulation in plants. The foliar Hg/C (from 237.0 ± 171.4 to 56.8 ± 27.7 µg/kg) and Hg/N (from 7.5 ± 3.9 to 2.5 ± 1.2 mg/kg) both decrease along the elevation. These elevation gradients are caused by the heterogeneity of vegetation uptake of atmospheric Hg and the variation of atmospheric Hg° concentrations at different altitudes. Organic soil Hg accumulation is controlled by forest types, topographic and climatic factors, with the highest concentration in the mixed forest (244.9 ± 55.7 µg/kg) and the lowest value in the alpine forest (151.9 ± 44.5 µg/kg). Further analysis suggests that soil Hg is positively correlated to C (r² = 0.66) and N (r² = 0.57), and Hg/C and Hg/N both increase with the soil depth. These stoichiometric relations highlight the combined effects from environmental and climatic factors which mediating legacy Hg accumulation and selective Hg absorption during processes of organic soil mineralization.     

Institutional effectiveness of REDD+ MRV: Countries progress in implementing technical guidelines and good governance requirements

The UNFCCC requires REDD+ countries wishing to receive results-based payments to measure, report and verify (MRV) REDD+ impacts; and outlines technical guidelines and good governance requirements for MRV. This article examines institutional effectiveness of REDD+ MRV by assessing countries’ progress in implementing these technical guidelines and good governance requirements, from three dimensions. Ownership of technical methods examines whether countries own technical methods for forest area and area change measuring, and for estimating forest carbon stocks; and whether national MRV systems cover all forests, land uses and carbon pools. Administrative capacity examines development of administrative competence to implement MRV. Good governance examines whether countries espouses norms of good governance in their MRV systems. We apply these dimensions to assess and compare progress in 13 REDD+ countries, based on a review of national and international documents. Findings show that REDD+ countries have high to very high ownership of technical methods. However, majority ranks only low to moderate on administrative capacity and good governance. This means that although countries have started developing technical methods for MRV, they are yet to develop the competence necessary to administer MRV and to inculcate good governance in MRV. The article explain the scores and suggest ways of improving implementation of REDD+ MRV.     

Challenges and opportunities for REDD+: A reality check from perspectives of effectiveness,efficiency and equity

Reducing Emissions from Deforestation and forest Degradation (REDD+) is a promising mechanism of payments for ecosystem services with the aim to effectively reduce emissions in an efficient and equitable manner. REDD+ is part of the Paris-agreement reached at the UNFCCC COP21 in December 2015, but questions on whether REDD+ will work and bring multi-benefits are still hotly debated. Moreover, the results and messages from research on REDD+ in different regions are mixed, context-based and fragmented. Here, we employ a survey among REDD+ stakeholders, researchers, and consultants to evaluate the opportunities and challenges of REDD+ for achieving effective, efficient and equitable outcomes and co-benefits (3E+). We substantiate our survey results with a literature review. Results suggest that the challenges in achieving the 3E+ relate to the disproportionality between deforestation drivers and mitigation measures, diverging perceptions of equity among REDD+ stakeholders, complexity of property rights, and fragile willingness of stakeholders to engage in REDD+. If these challenges can be successfully addressed by the involved stakeholder groups, they can be turned into opportunities for realizing REDD+.     

The impact of climate change under different thinning regimes on carbon sequestration in a German forest district

The objective of this paper is to assess how much carbon (C) is currently stored in a forest district in Thuringia, Germany, and how the carbon stocks will develop up to the year 2099 with a changing climate and under various management regimes (including no management), with different assumptions about carbon dioxide (CO₂) fertilization effects. We applied the process-based model 4C and a wood product model to a forest district in Germany and evaluated both models for the period from 2002 to 2010, based on forest inventory data for the stands in the district. Then, we simulated the growth of the stands in the forest district under three different realizations of a climate change scenario, combined with different management regimes. Our simulations show that in 2099, between 630 and 1149 t C ha^?1 will be stored in this district. The simulations also showed that climate change affects carbon sequestration. The no management strategy sequestered the highest amount of carbon (8.7 t C ha^?1 year^?1), which was greater than the management regimes. In the model, the possible fertilization effect of CO₂ is an important factor. However, forest management remains the determining factor in this forest district.     

Carbon reduction potential and cost evaluation of different mitigation approaches in China's coal to olefin Industry

Coal-based olefin (CTO) industry as a complement of traditional petrochemical industry plays vital role in China's national economic development. However, high CO₂ emission in CTO industry is one of the fatal problems to hinder its development. In this work, the carbon emission and mitigation potentials by different reduction pathways are evaluated. The economic cost is analyzed and compared as well. According to the industry development plan, the carbon emissions from China's CTO industry will attain 189.43 million ton CO₂ (MtCO₂) and 314.11 MtCO₂ in 2020 and 2030, respectively. With the advanced technology level, the maximal carbon mitigation potential could be attained to 15.3% and 21.9% in 2020 and 2030. If the other optional mitigation ways are combined together, the carbon emission could further reduce to some extent. In general, the order of mitigation potential is followed as: feedstock alteration by natural gas > CO₂ hydrogenation with renewable electricity applied > CCS technology. The mitigation cost analysis indicates that on the basis of 2015 situation, the economic penalty for feedstock alteration is the lowest, ranged between 186 and 451 CNY/tCO₂, and the cost from CCS technology is ranged between 404 and 562 CNY/tCO₂, which is acceptable if the CO₂ enhanced oil recovery and carbon tax are considered. However, for the CO₂ hydrogenation technology, the cost is extremely high and there is almost no application possibility at present.     

Climate change mitigation strategies in agriculture, forestry and other land use sectors in Vietnam

Agriculture, Forestry and Other Land Use (AFOLU) sectors account for 53 % of the domestic greenhouse gas emissions (GHG) in Vietnam in 2000. However, due to political focus on adaptation, Vietnamese government has not formulated particular policy on mitigation in the sectors. This study aims to identify and assess mitigation potential in AFOLU sectors in Vietnam up to 2030 using AFOLU Bottom-up model. Therefore, the results can help government towards building mitigation strategies in the country. The methodology involves: (1) development of future assumptions of crops harvested areas, livestock population and area of land use and land use change and (2) identification of mitigation countermeasures with high potential and assessment of their cost-effectiveness. In 2030, 11 MtCO₂eq/year of emission can be reduced by no-regret countermeasures which take zero or negative cost. In the case of full application of countermeasures, 48 MtCO₂eq/year can be reduced compared to the baseline emission level. Mitigation countermeasures, which have great contribution for GHG reduction in Vietnam, are midseason drainage in rice paddy (7 MtCO₂eq/year), off-season incorporation of rice straw (3 MtCO₂eq/year) and conservation of existing protection forests (17 MtCO₂eq/year). Based on our findings, a package of mitigation countermeasures at 10 USD/tCO₂eq is expected to have the most economic efficiency and high mitigation for GHG mitigation in AFOLU sectors in Vietnam.     

REDD+ and international leakage via food and timber markets: a CGE analysis

This paper studies the effect of international trade in food and timber on land use and potential carbon leakage in the context of actions to reduce emissions from deforestation and forest degradation (REDD+). First a simple analytical model of international leakage is presented that focuses on international competition between firms that produce food and timber. A formula for the leakage rate in the model is derived. The results of the analytical model are then tested with a large Computable General Equilibrium (CGE) model and it is verified that the qualitative results from the analytical model hold. Finally, a scenario of leakage rate trajectories is presented for a number of key tropical forest regions for the next two decades and a sensitivity analysis is performed on key parameters. Computed leakage rates range between 0.5 % for Brazil and 11.3 % for Malaysia and are fairly stable over the projection period. Leakage rates increase with a higher supply elasticity of land and a higher trade elasticity, they decrease with a higher elasticity of input substitution in production and appear to be independent of the rates of forest conservation and absolute prices of food and timber.     

Greenhouse gas emission factors for land use and land-use change in Southeast Asian peatlands

Tropical peat swamp forests, which are predominantly located in Southeast Asia (SEA) and play a prominent role as a global carbon store, are being intensively degraded and converted to agricultural lands and tree plantations. For national inventories, updated estimates of peat emissions of greenhouse gases (GHG) from land use (LU) and land-use change in the tropics are required. In this context, we reviewed the scientific literature and calculated emission factors of peat net emissions of carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) in seven representative LU categories for SEA i.e. intact peat swamp forest, degraded forest (logged, drained and affected by fire), mixed croplands and shrublands, rice fields, oil palm, Acacia crassicarpa and sago palm plantations. Peat net CO₂ uptake from or emissions to the atmosphere were assessed using a mass balance approach. The balance included main peat C inputs through litterfall and root mortality and outputs via organic matter mineralization and dissolved organic carbon. Peat net CO₂ loss rate from degraded forest, croplands and shrublands, rice fields, oil palm, A. crassicarpa and sago palm plantations amounted to 19.4?±?9.4, 41.0?±?6.7, 25.6?±?11.5, 29.9?±?10.6, 71.8?±?12.7 and 5.2?±?5.1 Mg CO₂ ha^?1 y^?1, respectively. Total peat GHG losses amounted to 20.9?±?9.4, 43.8?±?6.8, 36.1?±?12.9, 30.4?±?10.6, 72?±?12.8 and 8.6?±?5.3 Mg CO₂-equivalent ha^?1 y^?1 in the same LU categories, respectively. A single land-clearing fire would result in additional emissions of 493.6?±?156.0 Mg CO₂-equivalent ha^?1.     

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.     

Impacts of climate change on savannah woodland biomass carbon density and water-use: a modelling study of the Sudanese gum belt region

This paper analyzes potential impacts of climate change on biomass carbon (C) density and water-use (actual evapotranspiration, AET) of savannah woodlands in Sudan. Climate change scenarios were developed from five General Circulation Models (GCMs; CGCM2, CSIRO2, ECHam4, HadCM3 and PCM) under two IPCC (Intergovernmental Panel on Climate Change) emission scenarios (A1FI and B1). Baseline (1961-90) climate and climate change scenarios for 2080s for eight map sheet grids (1° latitude x 1.5° longitude) were constructed. Compared to baseline values, mean annual precipitation (MAP) showed both increases (+112 to +221 mm) and decreases (?13 to ?188 mm) but mean annual temperature (MAT) only showed increases (+1.2 to +8.3 °C). Baseline biomass C densities showed an exponential relationship with MAP (y?=?6.798 e ^0.0054x, R²?=?0.70). Depending on climate change MAP, biomass C densities increased (+14 to +241 g C m^?2) or decreased (?1 to ?148 g?C m^?2). However, because of uncertainty in biomass C density estimates, the changes were only significant (P <0.05) for some of the climate change scenarios and for grids with MAP >260 mm. Under A1FI emission scenarios, only HadCM3 did not have a significant effect while under B1 emission scenarios, only CGCM2 and ECHam4 had a significant effect on biomass C density. AET also showed both increases (+100 to +145 mm for vertisols and +82 to +197 mm for arenosols) and decreases (?12 to ?178 mm for vertisols and ?12 to ?132 mm for arenosols). The largest relative changes in AET (up to 31 %) were associated with grids receiving the lowest rainfall. Thus, even if MAP increases across the study region, the increase will have little impact on biomass levels in the driest areas of the region, emphasizing the need for improved management and use of savannah woodlands.     

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.     

Climate change mitigation strategies in the forest sector: biophysical impacts and economic implications in British Columbia,Canada

Managing forests to increase carbon sequestration or reduce carbon emissions and using wood products and bioenergy to store carbon and substitute for other emission-intensive products and fossil fuel energy have been considered effective ways to tackle climate change in many countries and regions. The objective of this study is to examine the climate change mitigation potential of the forest sector by developing and assessing potential mitigation strategies and portfolios with various goals in British Columbia (BC), Canada. From a systems perspective, mitigation potentials of five individual strategies and their combinations were examined with regionally differentiated implementations of changes. We also calculated cost curves for the strategies and explored socio-economic impacts using an input-output model. Our results showed a wide range of mitigation potentials and that both the magnitude and the timing of mitigation varied across strategies. The greatest mitigation potential was achieved by improving the harvest utilization, shifting the commodity mix to longer-lived wood products, and using harvest residues for bioenergy. The highest cumulative mitigation of 421 MtCO₂e for BC was estimated when employing the strategy portfolio that maximized domestic mitigation during 2017–2050, and this would contribute 35% of BC’s greenhouse gas emission reduction target by 2050 at less than $100/tCO₂e and provide additional socio-economic benefits. This case study demonstrated the application of an integrated systems approach that tracks carbon stock changes and emissions in forest ecosystems, harvested wood products (HWPs), and the avoidance of emissions through the use of HWPs and is therefore applicable to other countries and regions.     

湿润亚热带典型白云岩流域不同土地利用下的试片溶蚀速率及岩溶碳汇

土地利用对石灰岩溶蚀速率的影响已有较多研究报道,但白云岩溶蚀速率对于土地利用的响应研究却罕见相关报道。因此,探究不同土地利用对白云岩溶蚀速率的影响具有一定的意义,并可为评估白云岩地区的岩溶碳汇效应积累基础数据。本文以湿润亚热带典型白云岩小流域——贵州施秉黄洲河白云岩小流域为研究区,利用白云岩溶蚀试片对流域内不同土地利用下的白云岩溶蚀速率及其影响因素进行了研究。结果表明：不同土地利用条件下白云岩试片溶蚀速率的大小为旱地（4.25 mg/（cm²·a））>林地（1.01 mg/（cm²·a））>水田（0.14 mg/（cm²·a））;白云岩试片溶蚀速率随土壤有机质含量增加、土壤pH值减少而增大;但其与土壤CO₂浓度呈相反的变化趋势;土壤含水量、容重对溶蚀速率的影响不大。由白云岩试片的溶蚀速率估算该白云岩流域的岩溶碳汇总量为351.70 tCO₂/a,岩溶碳汇通量为7.31 tCO₂/（km²·a）,与前人利用水化学径流法计算相比明显较小。与以往在石灰岩区使用溶蚀试片法和水化学径流法计算的岩溶碳汇强度差异大致相同。