Biomass Carbon Storage Research Articles

广东省森林死木碳库特征

PDF HTML阅读 XML下载 导出引用 引用提醒 广东省森林死木碳库特征 DOI: 10.5846/stxb201701180147 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31370634） Characteristics of the forest deadwood carbon pool in Guangdong Province Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:基于广东省第8次国家森林资源清查的固定样地调查数据和2016年典型抽样的死木调查数据，利用分树种、分腐朽程度的各个组分相兼容的生物量模型以及相对应的地上、地下部分含碳系数，对广东省森林死木碳库动态进行估算，分析死木种类、林分类型和龄组对死木碳库的影响，量化林分生长特性和自然灾害对死木碳库的贡献。结果表明：2007-2012年间广东省乔木林死木碳库新增碳储量5811.86 Pg，占同期乔木林活立木碳库的2.94%，其中枯倒木多于枯立木；阔叶混交林和马尾松林贡献了近70%的死木碳储量；马尾松、其他软阔、湿地松、阔叶混交林和其他硬阔的死木碳储量占同类森林总活立木碳储量的比例较大，均超过4.00%，桉树和杉木比例最小，均不足1.00%；从龄组看，发生在中龄林的死木碳储量占总死木碳储量比例最大，过熟林最小。与同龄组林分的现存碳储量相比，从幼龄林（2.03%）到过熟林（4.56%）基本呈上升趋势。全省新增死木库碳密度为（0.7612 ±3.3988） Mg/hm2。竞争和衰老引起的枯死在林分中普遍存在，占发生死木林分面积的60%以上，但增加到死木碳库的储量不足总量的四分之一，而自然灾害只占发生死木林分面积的10%，对死木碳库的贡献却超过40%。到2016年，2007-2012年间增加到死木库的碳储量下降到785.57 Pg，减少约85%，枯倒木的腐朽程度重于枯立木，不同树种间腐朽程度不一，杉木腐朽程度最低。清林等人为经营活动和死木的腐朽是存量减少的主要原因。 Abstract:We used compatible tree biomass equations for each component grouped by species and decay classes, and carbon fractions of above-ground and below-ground parts, based on the 8th Chinese National Forest Inventory (CNFI) data in Guangdong Province and the deadwood investigation data from typical sampling in 2016, to estimate the dynamics of the forest deadwood carbon pool in Guangdong Province, including the effects of deadwood type, stand type, and age groups. Furthermore, the contribution of stand growth characteristics and natural disasters to the deadwood carbon pool were quantified. The results showed that the carbon storage of the deadwood pool of arbor forests in Guangdong Province increased 5811.86 Pg from 2007 to 2012, which accounted for 2.94% of biomass carbon in arbor forests during the same period. Logs contributed more carbon to deadwood pool than snags. Broad-leaved mixed forests and Pinus massoniana contributed approximately 70% to the deadwood carbon pool. Within the same forest type, the deadwood carbon storage of Pinus massoniana, light hardwoods, Pinus elliottii, broad-leaved mixed forests, and hardwoods accounted for a larger proportion (>4%) of standing carbon stock, whereas Eucalyptus and Cunninghamia lanceolata accounted for a lower proportion (<1%). With respect to age groups, middle-aged stands accounted for the largest proportion of the increased carbon, whereas over-mature stands accounted for the smallest. Comparing the existing biomass carbon storage within the same age group revealed an upward trend from 2.03% for the young-aged to 4.56% for the over-mature stands. The increased carbon density was (0.7612 ±3.3988) Mg/hm2 in the province. Death owing to competition or old age was very common in the stand, and was observed in approximately 60% of the stands with deadwoods, but contributed to less than 1/4 of the increased deadwood carbon. Rather, natural disasters, which only happened in approximately 10% of the stand, contributed more than 40% to the increased deadwood carbon. The increased deadwood carbon from 2007 to 2012 declined until 2016 by approximately 85% to 785.57 Pg. The degree of decay of logs was greater than for snags. The degree of decay varied among different species and was lowest for Cunninghamia lanceolata. Human disturbance, such as over-cleaning, and decay of trees could be the main reasons for the reduced carbon storage. 参考文献 相似文献 引证文献

Quantification and mapping of the supply of and demand for carbon storage and sequestration service in woody biomass and soil to mitigate climate change in the socio-ecological environment

In this study, the supply of and demand for carbon storage and sequestration of woody biomass in the socio-ecological environment of the Wabe River catchment in Gurage Mountains, Ethiopia, were estimated. This information was subsequently integrated into a map that showed the balance between supply capacities and demand in a spatially explicit manner to inform planners and decision makers on methods used to manage local climate change. Field data for wood biomass and soil were collected, satellite images for land use and land cover (LULC) were classified, and secondary data from statistics and studies for estimation were obtained. Carbon storage, the rate of carbon sequestration and the rate of greenhouse gas (GHG) emissions from diverse sources at different LULCs, was estimated accordingly by several methods. Even though a large amount of carbon was stored in the catchment, the current yearly sequestration was less than the CO2-eq. GHG emissions. Forest and Enset-based agroforestry emissions exhibited the highest amount of woody biomass, and cereal crop and wetland exhibited the highest decrease in soil carbon sequestration. CO2-eq. GHG emissions are mainly caused by livestock, nitrogenous fertilizer consumption, and urban activities. The net negative emissions were estimated for the LULC classes of cereal crop, grazing land, and urban areas. In conclusion, without any high-emission industries, GHG emissions can be greater than the regulatory capacity of ecosystems in the socio-ecological environment. This quantification approach can provide information to policy and decision makers to enable them to tackle climate change at the root level. Thus, measures to decrease emission levels and enhance the sequestration capacity are crucial to mitigate the globally delivered service in a specific area. Further studies on the effects of land use alternatives on net emissions are recommended to obtain in-depth knowledge on sustainable land use planning.

Modeling impacts of climate change and grazing effects on plant biomass and soil organic carbon in the Qinghai–Tibetan grasslands

Abstract. The Qinghai Province supports over 40 % of the human population of the Qinghai–Tibetan Plateau (QTP) but occupies about 29 % of its land area, and thus it plays an important role in the plateau. The dominant land cover is grassland, which has been severely degraded over the last decade due to a combination of increased human activities and climate change. Numerous studies indicate that the plateau is sensitive to recent global climate change, but the drivers and consequences of grassland ecosystem change are controversial, especially the effects of climate change and grazing patterns on the grassland biomass and soil organic carbon (SOC) storage in this region. In this study, we used the DeNitrification-DeComposition (DNDC) model and two climate change scenarios (representative concentration pathways: RCP4.5 and RCP8.5) to understand how the grassland biomass and SOC pools might respond to different grazing intensities under future climate change scenarios. More than 1400 grassland biomass sampling points and 46 SOC points were used to validate the simulated results. The simulated above-ground biomass and SOC concentrations were in good agreement with the measured data (R2 0.71 and 0.73 for above-ground biomass and SOC, respectively). The results showed that climate change may be the major factor that leads to fluctuations in the grassland biomass and SOC, and it explained 26.4 and 47.7 % of biomass and SOC variation, respectively. Meanwhile, the grazing intensity explained 6.4 and 2.3 % variation in biomass and SOC, respectively. The project average biomass and SOC between 2015 and 2044 was significantly smaller than past 30 years (1985–2014), and it was 191.17 g C m−2, 63.44 g C kg−1 and 183.62 g C m−2, 63.37 g C kg−1 for biomass and SOC under RCP4.5 and RCP8.5, respectively. The RCP8.5 showed the more negative effect on the biomass and SOC compared with RCP4.5. Grazing intensity had a negative relationship with biomass and positive relationship with SOC. Compared with the baseline, the biomass and SOC changed by 12.56 and −0.19 % for G0, 7.23 and 0.23 for G−50, and −5.17 and 1.19 % for G+50. In the future, more human activity and management practices should be coupled into the model simulation.

The influence of forest management and timber use options on carbon sequestration and the consequences on biodiversity

Abstract The results of scientific studies dealing with the influence of forest management on carbon dynamics are often controversial. Substituting fossil fuels with wood is not always a climate-friendly solution, and besides, it has often a negative impact on biodiversity. The current paper reviews the literature about the influence of different forest management and timber use options on climate change and brings out the accompanying consequences on biodiversity in temperate and boreal climate zones. The forest’s ability to sequestrate and store carbon can be enlarged by appropriate forest management planning and practices. Generally, for mitigation of climate change, the moderate (not intensive) forest management is most favourable, but intensification of management enhances global warming, since forest carbon storage in tree biomass and soil decreases. The mitigation of climate change is just one of the many roles of forest, and climate policy actions cannot come at the expense of species diversity. The complex studies dealing with several forest goals conclude that high carbon store and biodiversity protection do not contradict each other, but the achievement of maximum economic profit at the same time is not possible. The mitigation of climate change and wildlife protection is most effective when it is first of all the forests with a high biodiversity that are managed less intensively. Concerning climate change, the most negative forest biomass use is wood combustion. It is reasonable to burn only such biomass (cut and industrial residues) which cannot be used for producing goods holding carbon for a long time.

Greenhouse gas emissions and carbon sequestration by agroforestry systems in southeastern Brazil

Agrosilvopastoral and silvopastoral systems can increase carbon sequestration, offset greenhouse gas (GHG) emissions and reduce the carbon footprint generated by animal production. The objective of this study was to estimate GHG emissions, the tree and grass aboveground biomass production and carbon storage in different agrosilvopastoral and silvopastoral systems in southeastern Brazil. The number of trees required to offset these emissions were also estimated. The GHG emissions were calculated based on pre-farm (e.g. agrochemical production, storage, and transportation), and on-farm activities (e.g. fertilization and machinery operation). Aboveground tree grass biomass and carbon storage in all systems was estimated with allometric equations. GHG emissions from the agroforestry systems ranged from 2.81 to 7.98 t CO2e ha−1. Carbon storage in the aboveground trees and grass biomass were 54.6, 11.4, 25.7 and 5.9 t C ha−1, and 3.3, 3.6, 3.8 and 3.3 t C ha−1 for systems 1, 2, 3 and 4, respectively. The number of trees necessary to offset the emissions ranged from 17 to 44 trees ha−1, which was lower than the total planted in the systems. Agroforestry systems sequester CO2 from the atmosphere and can help the GHG emission-reduction policy of the Brazilian government.

Cryogenic technology for biogas upgrading combined with carbon capture - a review of systems and property impacts

CO2 makes a major contribution to the climate change, and biomass renewable energy and carbon capture and storage (CCS) can be deployed to mitigate the CO2 emission. Cryogenic process for biogas upgrading combined with carbon capture is one of the most promising technologies. This paper reviewed the state-of-the-art of cryogenic systems for biogas upgrading combined with carbon capture, and introduced the status and progress of property impacts on the cryogenic systems with emphasize on phase equilibrium. The existing cryogenic systems can be classified as flash liquefaction system, distillation system, and liquefaction combined with desublimation system. The flash liquefaction system produces biomethane and CO2 in lower purity than the other two systems. Thermodynamic optimization on the flash liquefaction system and liquefaction combined with desublimation system should be done further, and comprehensive comparison between three cryogenic systems needs to be carried out. As to the phase equilibrium, PR EOS is safe to be used in predicting VLE and SVLE with an independent thermodynamic model describing the fugacity of the solid phase. However, the impacts of binary mixing parameter, different EOS models and mixing rules, on the performance of the cryogenic system need to be identified in the future.

Effect of manipulating animal stocking rate on the carbon storage capacity in a degraded desert steppe

AbstractManaging the stocking rate is considered one of the most important practices influencing carbon storage on rangeland. The effects of four stocking rates consisting of a non‐grazed control (CK), light (0.15 sheep ha−1month−1), moderate (0.30 sheep ha−1month−1) and heavy (0.45 sheep ha−1month−1) were evaluated for impacts on carbon storage taking place on the Desert Steppe of Inner Mongolia, China. Carbon storage was measure in aboveground vegetation, roots and soil in August of 2009, 2011 and 2013. Both aboveground biomass (AGB) and below‐ground biomass (BGB) increased significantly as stocking rate decreased. Stocking rate also had a significant effect on both the aboveground and below‐ground carbon storage in plant biomass, but had no effect on the soil carbon. Compared to the heavy stocking rate typically practiced by local herders, lower stocking rates increased the total above‐ and below‐ground biomass carbon storage by ≥ 7%. Over the 3 year study, compared to the moderate stocking rate, the rate of carbon sequestration with a light stocking rate was 0.7 Mg C ha−1year−1. Thus, reducing stocking rate has the potential to increase C sequestration and storage, as well as maintaining animal numbers at a more sustainable level suitable for the Desert Steppe ecosystem.

Ecosystem C and N dynamics affected by a modified spring barley trait with increased nitrogen use - a simulation case study

ABSTRACTTo what extent might a crop with increased plant N uptake efficiency and/or N demand increase plant biomass and soil carbon storage, decrease N leaching, and reduce the need for N fertilisation? This was assessed for a fertilised sandy loam site in central Sweden cultivated with spring barley for a four year period using a process based crop and soil simulation model (SOILN) calibrated to fit observations of field experiments with non-modified crops. Crop properties were changed in accordance with previous model applications to other crops with higher N uptake and utilisation efficiencies, to resemble potential effects of breeding. For the modified crops a doubling of daily uptake efficiency of soil mineral N and/or increase of radiation use efficiency by 30%, increased plant biomass by 3%–30%, decreased N leaching by 1%–30% and increased soil organic carbon (SOC) content by 1–12 g C m−2 year−1. The larger changes were mainly due to increased uptake efficiency. Fertilisation of the modified spring barley crop could be reduced while still producing the same plant biomass as the non-modified crop. The plant biomass to N leaching ratio of the modified crops increased. The simulated changes in plant biomass and SOC were sensitive to weather conditions suggesting that in situ experiments would need to cover a large range of weather conditions to evaluate the performance of new crop traits under climatic variability. The study suggests a strong need that field experiments are accompanied with model applications, when exploring the potential of the modified crops under variable conditions.

Effects of grassland degradation and precipitation on carbon storage distributions in a semi-arid temperate grassland of Inner Mongolia, China

Environmental degradation influences carbon (C) cycling and storage in grassland ecosystems by altering vegetation productivity. However, the impacts of different degradation intensities on vegetation–soil C distributions in grasslands have not been well documented. We measured C storage in soil, roots, and plants under light, moderate, and severe degradation levels in a typical steppe region of Xilinhot, Inner Mongolia, China in 2011 and 2012. Grassland C storage was highest in soil, followed by roots, and then aboveground plant biomass. Grassland degradation and precipitation significantly influenced C storage distributions. During the dry year (2011), total C storage in vegetation and soil was highest under light degradation. Carbon storage in aboveground plant biomass and roots increased with degradation intensity. During the wet year (2012), C storage was highest in aboveground plant biomass and roots under light degradation. Root biomass tended to be concentrated in the soil surface during the wet year.

Carbon storage in hedge biomass—A case study of actively managed hedges in England

Farmland hedges could be managed for carbon sequestration, but empirical data on their carbon (C) stock in the UK is lacking. Lowland hedges managed by hedge laying and triennial trimming using a mechanical flail formed a dense woody structure (mean 81,368 stems ha−1). Hedges untrimmed for 3 years (mean height 3.5m, widths 2.6–4.2m), contained an above ground biomass (AGB) C stock of 42.0±3.78tCha−1 (14.0±1.94tCkm−1); when trimmed to 2.7m high, and subsequently 1.9m high, AGB C stocks were reduced to 40.6±4.47tCha−1 (11.4tCkm−1) and 32.2±2.76tCha−1 (9.9tCkm−1), respectively. A 4.2m wide hedge contained 9.7tCkm−1 more AGB C stock than a 2.6m wide hedge (mean height 3.5m). Below ground biomass (BGB) was 38.2±3.66tCha−1 (11.5tCkm−1). Near horizontal stems, arranged by hedge laying, 12–18 years prior to sampling, accounted for 5.2tCha−1 (1.6tCkm−1) of AGB C. The empirical data demonstrated how changing management practices to wider/taller hedges sequestered C in AGB. These estimates of hedgerow C stocks fill a knowledge gap on C storage and identified the need for a more comprehensive biomass inventory of hedgerows to strengthen the national carbon accounting of agro-ecosystems in the UK.

Modelling of the carbon sequestration and its prediction under climate change

The aim of the presented study is to quantify the total carbon stock of habitats in addition the estimation of aboveground and belowground biomass, necromass, and soil organic carbon. Prediction of carbon storage under climate change is based on future land-use changes, identification of new land-use distribution, and evaluation of changes in human impacts on biomass production and carbon storage. Widely used InVEST model was applied to determine the existing carbon stocks and the amount of carbon captured over time. Changes in the carbon storage were calculated from aboveground biomass, belowground biomass, necromass, and soil organic carbon pools. The original model was modified to vector space to better identify land heterogeneity. The values of the four carbon pools for individual land-use categories were derived from literature and experimental investigation. Land Change Modeller was then used to model future land use by applying business-as-usual scenario on data derived from 1990, 2000, 2006, and 2012 Corine Land Cover data. In this contribution, land cover predictions are calculated using three CORDEX climate models and two emission scenarios (RCP 4.5 and RCP 8.5). Results describe current carbon stock by basic carbon pools and prediction of the total amount of carbon stored in four reservoirs in three time period. Results show that the difference in predictions between specific scenarios in each period is increasing and in all predictions, roughly the same proportional carbon ratio is maintained between the individual stocks.

Spatiotemporal Distribution and Driving Factors of Forest Biomass Carbon Storage in China: 1977–2013

Increasing forest vegetation is important for carbon dynamics and to maintain the ecological and environmental balance in China. However, there is little understanding of how socioeconomic factors affect forest biomass carbon storage (FBCS). Here, we used continuous functions for biomass expansion factors and China’s seven completed forest inventories to estimate the changes in FBCS for 31 provinces in mainland China between 1977 and 2013. We developed a model that decomposes the contribution of the different socioeconomic factors driving FBCS. We found China’s FBCS increased from 4972 TgC (1 Tg = 1012g) in 1977–1981 to 7435 TgC in 2009–2013, with a mean growth of 77 TgC/a, and the average forest carbon density increased from 36.0 to 38.9Mg/ha (1 Mg = 106g), mainly due to the arbor forest contribution. Among the seven regions in China, the southwestern region currently accounts for the highest proportion (37.3%) of national FBCS, followed by northeastern (19.7%), northern (12.5%) and eastern region (10.8%). The main socio-economic factors affecting FBCS were forest land dependence, industrial structure and economic development level. Optimizing forest type and age structure, improving forest productivity, and strengthening forest management are feasible options to further increase China’s FBCS.

Carbon storage in biomass, litter, and soil of different native and introduced fast-growing tree plantations in the South Caspian Sea

Replantation of degraded forest using rapid-growth trees can play a significant role in global carbon budget by storing large quantities of carbon in live biomass, forest floor, and soil organic matter. We assessed the potential of 20-year old stands of three rapid-growth tree species, including Alnus subcordata, Populus deltoides and Taxodium distichum, for carbon (C) storage at ecosystem level. In September 2013, 48 replicate plots (16 m × 16 m) in 8 stands of three plantations were established. 36 trees were felled down and fresh biomass of different components was weighed in the field. Biomass equations were fitted using data based on the 36 felled trees. The biomass of understory vegetation and litter were measured by harvesting all the components. The C fraction of understory, litter, and soil were measured. The ecosystem C storage was as follows: A. subcordata (626.5 Mg ha−1) > P. deltoides (542.9 Mg ha−1) > T. distichum (486.8 Mg ha−1) (P < 0.001), of which 78.1–87.4% was in the soil. P. deltoides plantation reached the highest tree biomass (206.6 Mg ha−1), followed by A. subcordata (134.5 Mg ha−1) and T. distichum (123.3 Mg ha−1). The highest soil C was stored in the plantation of A. subcordata (555.5 Mg ha−1). The C storage and sequestration of the plantations after 20 years were considerable (25–30 Mg ha−1 year−1) and broadleaves species had higher potential. Native species had a higher soil C storage while the potential of introduced species for live biomass production was higher.

Dynamics of forest biomass carbon stocks from 1949 to 2008 in Henan Province, east-central China

We estimated forest biomass carbon storage and carbon density from 1949 to 2008 based on nine consecutive forest inventories in Henan Province, China. According to the definitions of the forest inventory, Henan forests were categorized into five groups: forest stands, economic forests, bamboo forests, open forests, and shrub forests. We estimated biomass carbon in forest stands for each inventory period by using the continuous biomass expansion factor method. We used the mean biomass density method to estimate carbon stocks in economic, bamboo, open and shrub forests. Over the 60-year period, total forest vegetation carbon storage increased from 34.6 Tg (1 Tg = 1 × 1012 g) in 1949 to 80.4 Tg in 2008, a net vegetation carbon increase of 45.8 Tg. By stand type, increases were 39.8 Tg in forest stands, 5.5 Tg in economic forests, 0.6 Tg in bamboo forests, and −0.1 Tg in open forests combine shrub forests. Carbon storage increased at an average annual rate of 0.8 Tg carbon over the study period. Carbon was mainly stored in young and middle-aged forests, which together accounted for 70–88% of the total forest carbon storage in different inventory periods. Broad-leaved forest was the main contributor to forest carbon sequestration. From 1998 to 2008, during implementation of national afforestation and reforestation programs, the carbon storage of planted forest increased sharply from 3.9 to 37. 9 Tg. Our results show that with the growth of young planted forest, Henan Province forests realized large gains in carbon sequestration over a 60-year period that was characterized in part by a nation-wide tree planting program.

Enhanced carbon storage through management for old‐growth characteristics in northern hardwood‐conifer forests

AbstractForest management practices emphasizing stand structural complexity are of interest across the northern forest region of the United States because of their potential to enhance carbon storage. Our research is part of a long‐term study evaluating silvicultural treatments that promote late‐successional forest characteristics in northern hardwood‐conifer forests. We are testing the hypothesis that aboveground biomass development (carbon storage) is greater in structural complexity enhancement (SCE) treatments when compared to conventional uneven‐aged treatments. Structural complexity enhancement treatments were compared against selection systems (single‐tree and group) modified to retain elevated structure. Manipulations and controls were replicated across 2‐ha treatment units at two study areas in Vermont, United States. Data on aboveground biomass pools (live trees, standing dead, and downed wood) were collected pre‐ and post‐treatment, then again a decade later. Species group‐specific allometric equations were used to estimate live and standing dead biomass, and downed log biomass was estimated volumetrically. We used the Forest Vegetation Simulator to project “no‐treatment” baselines specific to treatment units, allowing measured carbon responses to be normalized against differences in site characteristics affecting tree growth and pre‐treatment stand structure. Results indicate that biomass development and carbon storage 10 yr post‐treatment were greatest inSCEtreatments compared to conventional treatments, with the greatest increases in coarse woody material (CWM) pools. Structural complexity enhancement treatments contained 12.67 Mg/ha carbon inCWMcompared to 6.62 Mg/ha in conventional treatments and 8.84 Mg/ha in areas with no treatment. Percentage differences between post‐treatment carbon and simulated/projected baseline values indicate that carbon pool values inSCEtreatments returned closest to pre‐harvest or untreated levels over conventional treatments. Total carbon storage inSCEaboveground pools was 15.90% less than that projected for no‐treatment compared to 44.94% less in conventionally treated areas. Results from classification and regression tree models indicated treatment as the strongest predictor of aboveground C storage followed by site‐specific variables, suggesting a strong influence of both on carbon pools. Structural enhancement treatments have the potential to increase carbon storage in managed northern hardwoods. They offer an alternative for sustainable management integrating carbon, associated climate change mitigation benefits, and late‐successional forest structure and habitat.

Forest fragmentation reduced carbon storage in a moist tropical forest in Bangladesh: Implications for policy development

Forest fragmentation is continued to be widespread in the tropics resulting in reduced ecosystem services including carbon storage. However, the effect of forest fragmentation is not considered in the current carbon policy. We investigated the effect of forest fragmentation on tree biomass carbon and soil organic carbon (SOC) storage in a moist tropical forest in Bangladesh. Above and below-ground tree biomass carbon were calculated by using widely accepted allometric equations and SOC was measured by sampling soils up to 10cm depth and analyzing them in a soil laboratory. Results showed that carbon storage in tree biomass was significantly lower in fragmented forests (16.3±1.37tCha−1) than in contiguous forests (31.21±2.75tCha−1) (p<0.001). Likewise, a significantly lower SOC was contained in the soils of fragmented forests (17.26±0.83tCha−1) than in contiguous forests (21.62±0.78tCha−1) (p<0.001). Thus a total of 36% less carbon retained in tree biomass and soils in fragmented forests than in contiguous forests. Backward multiple linear regression analysis revealed tree density, tree height, tree DBH, height-diameter ratio (H/D) and tree species richness as influential factors of carbon variation in fragmented forests. All these structural parameters except tree species richness were significantly lower in fragmented forests, were positively associated with carbon storage and explained together 69% of the carbon storage variation. These findings suggest that the altered stand structure and tree allometry likely caused reduced carbon storage in fragmented forests and highlight the importance of landscape scale management intervention in the tropics. Here, we provided with the evidence of strong negative impact of forest fragmentation on carbon storage and argue that this effect should be in consideration which is currently overlooked in existing carbon accounting systems for tropical forests.

Biomass stocks and carbon storage in Barringtonia acutangula floodplain forests in North East India

Floodplain forests serve a critical function in flood regulation and the global carbon (C) cycle due to their important role in C sink management. Barringtonia acutangula, a tree species adapted to floodplains has been managed traditionally over millennia as family and community forest in North East India. Prevailing traditional management of the Barringtonia forest restricts felling of trees while promoting uses of tree branches in fishery management and fuel wood production. Such management systems might have helped in sustaining floodplain family forests with a steady stock of biomass. However, our knowledge of their role in biomass stocks and C storage is still scanty. Therefore, the present study was undertaken to estimate the biomass and carbon stocks of Barringtonia forests and to understand their role in carbon sink management. The floodplain forest at the study site was stocked with 3204 trees ha−1 of Barringtonia. Allometric models were developed using harvested tree, and these were used for estimation of biomass and vegetation carbon stocks. Among the various models tested the power model using diameter at breast height (DBH) as an independent variable fitted tree biomass in different tree components (bole, sprout, branch and leaves) adequately. Total dry above ground biomass (AGB) estimated at 552 ± 23 Mg ha−1 in the Barringtonia floodplain forests was much larger than AGB reported for various forest types and agroforestry systems in North East India. Biomass allocation patterns revealed that out of the total biomass, the bole contributed the highest proportion (45%) followed by sprouts (27%), branches (24%) and leaves (4%). The above-ground carbon stock was estimated at 263 ± 11 Mg ha−1. The quantity of biomass stock and the carbon storage in vegetation cover of Barringtonia forest suggest its direct influence on local, regional and even global climate.

Is crop biomass and soil carbon storage sustainable with long-term application of full plastic film mulching under future climate change?

The ridge–furrow with full plastic film mulching system (PM) is one of the most popular and widely applied field management techniques in dryland areas of China. There is concern for soil carbon storage and crop productivity dynamics under the long-term application of this management, specifically given the background of global climate change. However, the long term effects of this management practice are still poorly understood. More evaluation is required. A process-based biogeochemical model revised through four years of field experiments and a model drive by RCP (Representative Concentration Pathway) projection was applied to explore how soil carbon storage and maize productivity would change under future climate change projections. The field experiment showed that biomass was significantly higher in the PM than cultivation without mulching (CK), and their four-year average biomass values were 4996±967 and 2850±817kgCha−1, respectively. Meanwhile, the four-year average soil organic carbon (SOC) storage was 5.93gCkg−1 soil, 5.95gCkg−1 soil and 5.40gCkg−1 soil for (CK) and 5.83gCkg−1 soil, 5.78gCkg−1 soil and 5.58gCkg−1 soil for PM at depths of 0–10, 10–20 and 20–30cm, respectively. SOC did not significantly differ between the two treatments within the four years of the experiment. The model simulation with various rainfall and temperature change scenarios indicated that SOC (0–30cm) and biomass were more affected by climate change in CK compared to PM. During years 2016–2100, SOC and maize biomass constantly increased under PM and CK for the RCP 4.5 and RCP 8.5 scenarios, and biomass was higher for PM than CK. However, under the highest carbon dioxide emission scenario of RCP 8.5, the improved biomass and SOC in PM decreased when temperature increased by more than 2.85°C after year 2060. The modeling results showed that the PM cultivation system maintained high productivity and increasing trends of SOC under the high and medium greenhouse gas emission scenarios, derived from climate change projections for before the year 2060. The PM is currently an effective way to increase productivity and is a possible measure for dryland agriculture to adapt to near future climate change.

Tagasaste (Cytisus proliferus Link.) reforestation as an option for carbon mitigation in dryland farming systems

The Agriculture, Forestry and Other Land Use Sector (AFOLU) plays a major role in national and international strategies to manage increasing global greenhouse gas emissions. This study investigated the option of increasing carbon storage in biomass and poorly productive soils in dryland agricultural systems, while avoiding competition with food production, using tagasaste (Cytisus proliferus Link.), a woody N-fixing perennial species. Perennial plants often have deeper and more extensive root systems than annual plants, and therefore may increase soil organic carbon (SOC) stocks deeper than the IPCC standard sampling depth of 0.3m. Above- and below-ground biomass carbon and SOC to a depth of 2m were measured on a 22-yr-old replicated field experiment in Western Australia (mean annual rainfall, 498mmyr−1) comparing unmanaged plantations of tagasaste with conventional annual crop and pasture rotations. Carbon sequestration was 2.5MgCha−1yr−1 over the 22-yr lifespan for the tagasaste treatments, with a change of 0.9MgCha−1yr−1 in SOC and 1.6MgCha−1yr−1 in biomass. Tagasaste plots contained significantly larger SOC stocks compared with control plots for soil to 0.9m, however beyond this depth, treatment differences were not significant. It is recommended that soil sampling be extended to depths of 1m under such perennial systems with no benefit from sampling to depths deeper than this. In contrast to its current use as a fodder supplement for livestock, this study clearly demonstrates the potential of tagasaste for carbon mitigation within dryland farming systems, especially on soils marginal for conventional agriculture.

Mapping individual tree health using full-waveform airborne laser scans and imaging spectroscopy: A case study for a floodplain eucalypt forest

Abstract Declining forest health can affect crucial ecosystem functions, such as carbon storage in biomass and soils, the regulation of water regimes, the modulation of regional climate and conservation of biodiversity. Airborne laser scanning (ALS) and imaging spectroscopy (IS) are two potentially complementary remote sensing technologies capable of characterizing and monitoring regional forest health. However, the combined use of ALS and IS data to classify the health of individual trees has not yet been assessed. In this study we propose a new approach utilizing ALS and IS combined to characterize the health of individual trees. Firstly, we applied a recently developed bottom-up individual tree delineation algorithm across a structurally complex floodplain eucalypt forest that has experienced episodes of severe dieback over the past six decades. We further calculated ALS and IS indices for delineated tree crowns and used them as predictor variables in machine learning models. We trained and evaluated an object-oriented random forest classifier against field-measured tree crown dieback and transparency ratios, as indicators of eucalypt tree health and crown density, respectively. Our results showed that dieback levels of individual trees can be classified using ALS and IS with an overall accuracy of 81% and a kappa score of 0.66, while the classification of tree crown transparency levels had an overall accuracy of 70% and a kappa score of 0.5. Returned pulse width, intensity and density related ALS indices were the most important predictors in the tree health classification, as they accounted for > 40% of the variance in the data. At the forest level in terms of dieback, 81.5% of correctly delineated trees were classified as healthy, 12.3% as declining and 6.2% as dying or dead. Dieback occurred primarily in areas that were flooded