Forest Carbon Sink Research Articles

Integrated scenario modelling of energy, greenhouse gas emissions and forestry

Preventing dangerous climate change requires actions on several sectors. Mitigation strategies have focused primarily on energy, because fossil fuels are the main source of global anthropogenic greenhouse gas emissions. Another important sector recently gaining more attention is the forest sector. Deforestation is responsible for approximately one fifth of the global emissions, while growing forests sequester and store significant amounts of carbon. Because energy and forest sectors and climate change are highly interlinked, their interactions need to be analysed in an integrated framework in order to better understand the consequences of different actions and policies, and find the most effective means to reduce emissions. This paper presents a model, which integrates energy use, forests and greenhouse gas emissions and describes the most important linkages between them. The model is applied for the case of Finland, where integrated analyses are of particular importance due to the abundant forest resources, major forest carbon sink and strong linkage with the energy sector. However, the results and their implications are discussed in a broader perspective. The results demonstrate how full integration of all net emissions into climate policy could increase the economic efficiency of climate change mitigation. Our numerical scenarios showed that enhancing forest carbon sinks would be a more cost-efficient mitigation strategy than using forests for bioenergy production, which would imply a lower sink. However, as forest carbon stock projections involve large uncertainties, their full integration to emission targets can introduce new and notable risks for mitigation strategies.

Human influence on the temporal dynamics and spatial distribution of forest biomass carbon in China.

Global carbon cycles are impacted by human activity primarily via fossil fuel combustion and forest carbon budget alterations. In this study, the temporal dynamics and spatial distribution of forest biomass carbon (FBC) stock and density in China were analyzed to assess the large‐scale effects of humans on FBC. The results indicated that from 1977 to 2013, the FBC stock increased by 62.9%, from 4,335 to 7,064 Tg C, owing to human‐driven forestation and ecological restoration programs. Because of intensive human impacts, 44.2%–54.6% of the FBC stock was concentrated in four provinces (Heilongjiang, Yunnan, Inner Mongolia, and Sichuan) and the FBC density increased from the densely populated southeastern provinces to the sparsely populated northeastern and western provinces. On a spatial scale, the FBC density was significantly negatively related to population density, and the degree of the dependence of the FBC density on population density has been declining since 1998. This improvement in human–forest relations is related to economic development and programs in China that have promoted forestation and reduced deforestation. These results suggest that human impacts, including forestation, deforestation, population density, and economic development, have played significant roles in determining the temporal and spatial variations of FBC in the anthropogenic era. Moreover, our findings have implications for forest management and improvement of the forest carbon sink in China.

Ecological and environmental effects of land use change in rapid urbanization: The case of hangzhou, China

Land use changes sharply under rapid urbanization, yet its ecological and environmental effects are often neglected in land use decisions. Using the case of Hangzhou, China, we analyze the ecological and environmental effects of land use changes, including ecosystem services value (ESV) and carbon emissions, based on Landsat TM images from 1995, 2000, 2005, 2010, and 2014. We found significant ecological and environmental effects of land use changes under rapid urbanization. The value of ecosystem services in Hangzhou decreased from 546.7 million USD in 1995 to 448.97 million USD in 2014, and the ratio of ESV to GDP decreased from 5.8% to 0.6%. The net carbon emissions associated with land use changes increased from 4.26 million tons in 1995 to 15.10 million tons in 2014, mainly due to the increase of built-up land carbon emissions and the decrease of forest land carbon sink. The ESV is unevenly distributed spatially and low ESV spread from the central to the peripheral area. We use scenario analysis to illustrate that economic growth and environmental protection could be coordinated by bringing ecological and environmental effects into land use decisions.

A Numerical Case Study of the Implications of Secondary Circulations to the Interpretation of Eddy-Covariance Measurements Over Small Lakes

We use a large-eddy simulation (LES) to study the airflow patterns associated with a small inland lake surrounded by a forest of height one-tenth the radius of the lake. We combine LES results with scalar dispersion simulations to model potential biases in eddy-covariance measurements due to the heterogeneity of surface fluxes and vertical advection. The lake-to-forest transition can induce a non-zero vertical velocity component, affecting the interpretation of flux measurements. Significant horizontal gradients of mean $$\hbox {CO}_{2}$$ concentration are generated by the forest carbon sink and lake carbon source, which are transported by local roughness-induced circulation. We simulate six hypothetical locations for flux towers along a downwind gradient at various heights, and calculate at each location the effects of both the average vertical advection and average turbulent-flux divergence of $$\hbox {CO}_{2}$$ . We compare our model results with an analytical footprint model to find that the footprint predicted by the analytical model is inaccurate due to the complexities of advection for our test case. Similar small lakes surrounded by forests are likely affected by these phenomena as well. We recommend specialized levelling of sonic anemometers to reduce the effects of non-zero wind components. Flux towers over small water bodies should be constructed at a distance 0.5–0.67 times the diameter of the lake to provide ample separation from the areas affected by the rotor effect of the upwind forest/lake transition and the updraft at the downwind edge. Finally, we also suggest the filtering of wind directions based on the Higgins ratio.

Influence of site index on the relationship between forest net primary productivity and stand age.

Previous studies show that forest net primary productivity (NPP) varies pronouncedly with stand age, and these variations play a crucial role in determining forest carbon sinks or sources at regional scales. Some forest carbon cycling models, eg. InTEC (The integrated terrestrial ecosystem C-budget model), calculates annual forest NPP in the long term according to normalized NPP-age relationships and the reference forest NPP at a given age. Therefore, the accurate NPP-age relationship is important for forest NPP estimation. In this study, NPP at various stand ages for twelve major forest stand types in Heilongjiang Province in northeast China is derived from yield tables with consideration of the total biomass increment and foliage and fine-root turnovers. Similar to previous studies, our results also show that forest NPP increases quickly at young ages, reaches the maximum value at middle age (10–40 years old), and then decreases to a relative stable level at old ages. However, we additionally found that forests under better site conditions have faster growth rates in young ages and steeper declines after reaching the maximum. Therefore, when the NPP-age curves for different site indices are normalized against the maximum value of each curve, there are significant differences among them. These differences have implications on the methodology for estimating the spatial distribution of forest carbon sources and sinks.

Chronic nitrogen deposition influences the chemical dynamics of leaf litter and fine roots during decomposition

Atmospheric nitrogen deposition induces a forest carbon sink across broad parts of the Northern Hemisphere; this carbon sink may partly result from slower litter decomposition. Although microbial responses to experimental nitrogen deposition have been well-studied, evidence linking these microbial responses to changes in the degradation of specific compounds in decaying litter is sparse. We used wet chemistry and Fourier transform infrared spectroscopy (FTIR) methods to study effects of chronic simulated nitrogen deposition on leaf litter and fine root chemistry during a three-year decomposition experiment at four northern hardwood forests in the north-central USA. Leaf litter and fine roots were highly different in initial chemistry, such as concentrations of acid-insoluble fraction (AIF, or Klason lignin) and condensed tannins (CTs). These initial differences persisted over the course of decomposition. Gravimetrically-defined AIF and lignin/carbohydrate reference IR peak ratios both provide evidence that lignin in fine roots was selectively preserved under simulated nitrogen deposition. Lignin/carbohydrate peak ratios were strongly correlated with AIF, suggesting that AIF is a good predictor of lignin. Because AIF is abundant in fine roots, slower AIF degradation was the major driver of the slower fine root decomposition under nitrogen enrichment, explaining 73.5% of the additional root mass retention. Nitrogen enrichment also slowed the loss of CTs and proteins in fine roots. Nitrogen additions initially slowed the loss of AIF, CTs, and proteins in leaf litter, which was comparatively low in AIF, but these effects disappeared at the later stage and did not affect leaf litter mass loss during the experiment. Our results suggest that decomposition of chemical classes subject to oxidative degradation, such as lignin and CTs, is generally inhibited by nitrogen enrichment; but whether this inhibition eventually slows litter mass loss and leads to organic matter accumulation depends on the initial quantities of these classes in litter.

Influence of different geographical factors on carbon sink functions in the Pearl River Delta

This study analyzed carbon fixation across different land use types in the Pearl River Delta to identify the influence of different geographical factors on carbon fixation ability. The methodology was based on interpreting land use data from TM imagery, MODIS13Q1 data, and climate data, using the improved CASA and GeogDetector models. The results show that: (1) From 2000 to 2013, the total carbon sink increased slightly, from 15.58 × 106 t to 17.52 × 106 t, being spatially low at the center and increasing outwards; (2) Proxy variables (topography and landform characteristics), influencing urbanization, significantly affect the carbon sink function of the Pearl River Delta region. The proportion of urban and other construction land showed increasing effect on the regional carbon sink each year. However, the spatial structure of land in the study area changed from complex to simple, with enhanced stability; consequently, the influence of landscape characteristics (landscape dominance and landscape perimeter area fractal dimension) on the regional carbon sink gradually decreased; (3) The influence of the same factors differed with different land use types. Slope and altitude were found to have the greatest influence on the carbon sink of cultivated land, while landscape perimeter area fractal dimension more significantly affected the forest carbon sink.

近自然化改造对马尾松和杉木人工林生物量及其分配的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 近自然化改造对马尾松和杉木人工林生物量及其分配的影响 DOI: 10.5846/stxb201704030573 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 中央级公益性科研院所基本科研业务费专项资金（CAFYBB2014QA033）；广西林业科技项目（桂林科字[2016]第37号）；广西自然科学基金项目（2014GXNSFBA118100） Effects of close-to-nature transformation on biomass and its allocation in Pinus massoniana and Cunninghamia lanceolata plantations 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:近自然化改造作为森林新增碳汇的最有希望的选择之一，将如何通过改变林分结构影响林分生物量和生产力进而影响林分固碳能力和潜力目前尚不清楚，因此，了解近自然化改造对人工林生物量及其分配的影响，对人工林生态系统碳管理具有重要意义。以马尾松近自然化改造林（P （CN））、马尾松未改造纯林（P （CK））、杉木近自然改造林（C （CN））和杉木未改造纯林（C （CK））4种人工林为研究对象，采用样方调查和生物量实测的方法，分析4种林分生物量差异，旨在揭示近自然化改造对马尾松和杉木人工林生物量及其分配的影响。结果表明：马尾松杉木人工林近自然化改造通过调整林分结构显著提升马尾松和杉木人工林生物量和生产力，8a后马尾松和杉木林分生物量分别增加46.71%和37.24%。乔木层生物量在林分生物量总量中占主导地位（95.48%-98.82%），并对林分生态系统总生物量变化起决定性作用。林分生物量和生产力的增加主要因为近自然化改造改变了林分群落结构，进而提高了乔木层生产力。研究结果表明，合理的经营措施不仅可以改善林分结构，提升林分生产力，并可为增强植被固碳能力创造有利条件。 Abstract:Close-to-nature transformation is considered one of the most promising options for creating new forest carbon sinks, but the mechanism by which it influences the biomass by changing the forest structure and thereby influencing the ability and potential of the forest for carbon sequestration remains unclear. Therefore, there is an urgent need to understand these key effects of close-to-nature transformation on the biomass for carbon management in plantation ecosystems. Based on a close-to-nature forest of Pinus massoniana plantation (P(CN)) and an unimproved pure stand of P. massoniana (P(CK)), and a close-to-nature stand of Cunninghamia lanceolata (C(CN)) and an unimproved pure stand of C. lanceolata (C(CK)) as the research objects, the biomass and allocation difference of the four forest types were studied using the method of quadrat sampling combined with biomass measurement, aiming to reveal the influence of close-to-nature transformation on forest biomass and its allocation patterns in P. massoniana and C. lanceolata plantation. The results indicated that the biomass and productivity of P. massoniana and C. lanceolata plantations can be significantly increased by close-to-nature transformation, and the biomass of P. massoniana and C. lanceolata forest stands can be increased by 46.71% and 37.24%, respectively, after 8 years. The biomass of the arborous layer dominates the total biomass (95.48%-98.82%), which plays a vital role in the overall change in forest stand ecosystem biomass. The increase in biomass and productivity in the forest is mainly due to the change in the forest stand community structure, which increases the productivity of the arborous layer. Taken together, the results indicate that reasonable management measures can not only improve stand structure and productivity, but also create favorable conditions that enhance vegetation carbon fixation capacity and potential. 参考文献 相似文献 引证文献

基于人工神经网络与空间仿真模拟的区域森林碳估算比较——以龙泉市为例

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

中国森林碳汇市场竞争机制研究

近年来，森林碳汇市场作为解决生态系统效益补偿的有效机制在国际范围内已经初步建立起来，而中国森林碳汇市场发展缓慢，尤其是森林碳汇市场竞争机制不够完善：政府关注度不够，碳汇投融资渠道狭窄，民众意识薄弱。这些因素反过来又制约了森林碳汇市场竞争机制的发展。本文试从森林碳汇市场参与者的角度分析如何完善我国森林碳汇市场竞争机制。 In recent years, the forest carbon sink market is an effective mechanism to resolve the ecological benefit compensation system and it has initially established in the international scope. China’s forest carbon sink market is developing slowly, especially the forest carbon sink market competition mechanism is not perfect. The government doesn’t pay enough attention to sinks; investment and financing channel is narrow and awareness is weak. These factors restrict the development of forest carbon sequestration market competition mechanism. This paper tries to analyze the perspective of forest carbon sequestration market participants and how to perfect the forest carbon sink market competition mechanism.

近308年来大兴安岭北部森林植被气候生产潜力及其对气候变化的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 近308年来大兴安岭北部森林植被气候生产潜力及其对气候变化的响应 DOI: 10.5846/stxb201510312200 作者: 作者单位: 黑龙江省气象科学研究所,黑龙江省气象科学研究所,黑龙江省气象科学研究所,黑龙江省气象科学研究所,黑龙江省气象科学研究所,黑龙江省气象科学研究所,黑龙江省富裕县气象局 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（41165005，40865005）；黑龙江省气象局重点项目（HQZD2015002）联合资助 Climate-induced potential productivity of forest vegetation during the past 308 years in northern Da Hinggan Mountain region, China Author: Affiliation: Heilongjiang Institute of Meteorological Sciences,Heilongjiang Institute of Meteorological Sciences,Heilongjiang Institute of Meteorological Sciences,Heilongjiang Institute of Meteorological Sciences,Heilongjiang Institute of Meteorological Sciences,, 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:揭示大兴安岭北部气候变化敏感区的气候生产潜力演变及其影响机理，对于维持东北地区生态系统平衡具有重要意义。基于标准树轮年表反演气象资料与研究区13个气象站观测数据组成的1707-2014年气象资料序列，利用Miami模型和小波分析等方法，分析了大兴安岭北部气候生产潜力演变及其对气候变化的响应。结果显示：1707年以来，气温、降水、蒸散和标准气候生产潜力变化均表现极显著增加趋势，标准气候生产潜力（W）变化率为1.79 kg hm-2 a-1，20世纪气候倾向率最大为10.14 kg hm-2 a-1，温度气候生产潜力（WT）与降水气候生产潜力（WR）的比值21世纪最大，水热配比状态最好；4种气候生产潜力存在不同时间尺度的周期变化，但变化一致性较好，主周期均为215-219a；大兴安岭北部W呈现一致的正变化趋势，高值、次高值、低值中心分别在根河、塔河、鄂伦春偏南地区，振幅由西北向东南逐渐递减；W与年气温、降水量、蒸散量正相关显著，年平均气温每升高1℃、年降水量和蒸散量均增加10 mm，W变化率依次为453.71、74.40、219.01 kg/hm2，且气温是影响W的主要因子；未来"暖湿型"气候对森林植被生长有利，而"冷干型"气候对森林植被生长不利，气候生产潜力增加（减少）幅度均为10.9%-21.7%。研究结果不仅可为区域尺度内研究森林植被气候生产潜力提供基础方法，而且对进一步估算森林碳汇、即将实施的碳交易及中国北部边疆生态安全研究和生态功能规划制定等具有重要参考价值。 Abstract:Understanding the evolution and mechanisms of climate-induced potential productivity in the climate change sensitive regions of northern Da Hinggan Mountain are fundamental for maintaining the ecosystem balance of northeastern China. The present study employed a meteorological data series from 1707 to 2014 by using standard tree-ring chronology data collection methods and observations from 13 weather stations in northern Da Hinggan Mountain region. Using a Miami model and wavelet analysis, we analyzed the evolution of climate-induced potential productivity and its response to climate change. Results show that four types of climate-induced potential productivity (air temperature, precipitation, evapotranspiration, and standard climate-induced potential productivity (W)) have increased significantly(P ≤ 0.001) since 1707. W has increased at a rate of 1.79 kg hm-2 a-1 in this region since 1707. During the 20th century, the change rate of W caused by climate change peaked at 10.14 kg hm-2 a-1. During the 19th century, the change rate of W caused by climate change reached a minimum of 0.50 kg hm-2 a-1. These values of W were in the mid-range for the 18th (0.66 kg hm-2 a-1) and the 21st (4.79 kg hm-2 a-1)) centuries. The value of W for the analyzed centuries was ranked as the 21st > 20th > 18th > 19th century. The ratio of temperature potential productivity (WT) to precipitation potential productivity (WR) peaked in the 21st century; this century also experienced the highest correlation between precipitation and temperature. The different time scales in the four types of climate-induced potential productivity changed periodically in the wavelet analysis, but was relatively consistent. The first major periodic oscillation of the wavelet analysis was 215-219 years, and other major periodic oscillations in wavelet analysis were at 138, 138, 136, 138 years. W showed a consistently positive trend in northern Da Hinggan Mountain, high, sub-high, and low values of W in Genhe, Tahe, and southern Elunchun Counties of northern Da Hinggan Mountain, respectively. That is, the amplitude of the W gradually decreased from northwest to southeast. Therefore, the geographical environment greatly influenced the value of W as it varied significantly across the region. Climate-induced potential productivity was relatively high in the region with a good correlation between temperature and precipitation. The regional ecosystems are obviously dominated by forest vegetation with lush growth in northern area where the original forest landscape remained more intact than in the south where secondary forest vegetation is dominant. In addition, W was significantly positively correlated with annual air temperature, precipitation, and evapotranspiration. A 1℃ increase in mean annual air temperature and 10 mm increase in annual precipitation and evapotranspiration could induce an increase in W by 453.71, 74.40, 219.01 kg/hm2 in standard climate-induced potential productivity, respectively. Overall, air temperature is the main factor influencing any change in W. In the future, a warm-wet climate will be beneficial for the growth of forest vegetation, whereas a cold-dry climate will be unfavorable. Climate change is expected to create a warmer-wetter climate in northern Da Hinggan Mountain region, which could increase the potential productivity. If the temperature increases (or decreases) 1-2℃, precipitation increase would be expected to increase (or decrease) 10%-20%, and the potential productivity based on climatic conditions would increase (or decrease) within a range of 10.9 to 21.7%. These results may provide a basic method for studying potential productivity based on climate change for forest vegetation at regional scales, and an important reference value for future estimations of forest carbon-sinks, implementing carbon trade in the near future, studying ecological security, and formulating ecological function planning in China's northern border. 参考文献 相似文献 引证文献

Edge effects enhance carbon uptake and its vulnerability to climate change in temperate broadleaf forests

Forest fragmentation is a ubiquitous, ongoing global phenomenon with profound impacts on the growing conditions of the world's remaining forest. The temperate broadleaf forest makes a large contribution to the global terrestrial carbon sink but is also the most heavily fragmented forest biome in the world. We use field measurements and geospatial analyses to characterize carbon dynamics in temperate broadleaf forest fragments. We show that forest growth and biomass increase by 89 ± 17% and 64 ± 12%, respectively, from the forest interior to edge, but ecosystem edge enhancements are not currently captured by models or approaches to quantifying regional C balance. To the extent that the findings from our research represent the forest of southern New England in the United States, we provide a preliminary estimate that edge growth enhancement could increase estimates of the region's carbon uptake and storage by 13 ± 3% and 10 ± 1%, respectively. However, we also find that forest growth near the edge declines three times faster than that in the interior in response to heat stress during the growing season. Using climate projections, we show that future heat stress could reduce the forest edge growth enhancement by one-third by the end of the century. These findings contrast studies of edge effects in the world's other major forest biomes and indicate that the strength of the temperate broadleaf forest carbon sink and its capacity to mitigate anthropogenic carbon emissions may be stronger, but also more sensitive to climate change than previous estimates suggest.

Carbon neutral or a sink? Uncertainty caused by gap-filling long-term flux measurements for an old-growth boreal black spruce forest

Old-growth (>100years old) boreal forests are recognized as having accumulated large inventories of terrestrial carbon, but the magnitude of annual net exchange is not well established. Eddy covariance measurements of carbon dioxide exchange were made at a flux tower at the Northern Old Black Spruce forest in Manitoba, Canada, from 1994 to 2008. We evaluated the uncertainty in estimates of annual net ecosystem production by comparing four methods of filling missing measurement periods. Three of the methods were previously developed by groups at Harvard University, the Fluxnet Canada Research Network, and the Max Planck Institute of Biogeochemistry; and the fourth method used the mean of measurements from the dataset selected for the same time and day. Two methods showed carbon losses near the beginning of the period but all four methods estimated carbon gains in the later years. Individual years and methods ranged ±90gCm−2 y−1, demonstrating a wide range of estimates if data had been available from only a single year and a single method. When averaged over multiple years, the mean and standard error among methods gave a net forest carbon sink of 29±10gCm−2 y−1, ranging from 4 to 48gCm−2 y−1. Only the upper (Mean Data and Max Planck Institute of Biogeochemistry methods) and lower (Harvard method) estimates were significantly different, with the Fluxnet Canada Research Network method being the same as all other methods. There was no difference among methods for the January to August period, or for daytime periods. All methods were statistically different from a carbon-neutral forest suggesting that the Northern Old Black Spruce forest was likely a small carbon sink. Methods that estimated high ecosystem respiration also estimated high gross ecosystem production, and the small net differences could not be easily attributed to differences in flux partitioning. For forests that are close to carbon neutral, the use of several gap-filling methods: increases confidence in conclusions regarding the ecosystem carbon balance.

Seeking potential contributions to future carbon budget in conterminous US forests considering disturbances

Currently, US forests constitute a large carbon sink, comprising about 9 % of the global terrestrial carbon sink. Wildfire is the most significant disturbance influencing carbon dynamics in US forests. Our objective is to estimate impacts of climate change, CO2 concentration, and nitrogen deposition on the future net biome productivity (NBP) of US forests until the end of twenty-first century under a range of disturbance conditions. We designate three forest disturbance scenarios under one future climate scenario to evaluate factor impacts for the future period (2011–2100): (1) no wildfires occur but forests continue to age (Saging), (2) no wildfires occur and forest ages are fixed in 2010 (Sfixed_nodis), and (3) wildfires occur according to a historical pattern, consequently changing forest age (Sdis_age_change). Results indicate that US forests remain a large carbon sink in the late twenty-first century under the Sfixed_nodis scenario; however, they become a carbon source under the Saging and Sdis_age_change scenarios. During the period of 2011 to 2100, climate is projected to have a small direct effect on NBP, while atmospheric CO2 concentration and nitrogen deposition have large positive effects on NBP regardless of the future climate and disturbance scenarios. Meanwhile, responses to past disturbances under the Sfixed_nodis scenario increase NBP regardless of the future climate scenarios. Although disturbance effects on NBP under the Saging and Sdis_age_change scenarios decrease with time, both scenarios experience an increase in NBP prior to the 2050s and then a decrease in NBP until the end of the twenty-first century. This study indicates that there is potential to increase or at least maintain the carbon sink of conterminous US forests at the current level if future wildfires are reduced and age structures are maintained at a productive mix. The effects of CO2 on the future carbon sink may overwhelm effects of other factors at the end of the twenty-first century. Although our model in conjunction with multiple disturbance scenarios may not reflect the true conditions of future forests, it provides a range of potential conditions as well as a useful guide to both current and future forest carbon management.

Demographic Drivers of Aboveground Biomass Dynamics During Secondary Succession in Neotropical Dry and Wet Forests

The magnitude of the carbon sink in second-growth forests is expected to vary with successional biomass dynamics resulting from tree growth, recruitment, and mortality, and with the effects of climate on these dynamics. We compare aboveground biomass dynamics of dry and wet Neotropical forests, based on monitoring data gathered over 3–16 years in forests covering the first 25 years of succession. We estimated standing biomass, annual biomass change, and contributions of tree growth, recruitment, and mortality. We also evaluated tree species’ contributions to biomass dynamics. Absolute rates of biomass change were lower in dry forests, 2.3 and 1.9 Mg ha−1 y−1, after 5–15 and 15–25 years after abandonment, respectively, than in wet forests, with 4.7 and 6.1 Mg ha−1 y−1, in the same age classes. Biomass change was largely driven by tree growth, accounting for at least 48% of biomass change across forest types and age classes. Mortality also contributed strongly to biomass change in wet forests of 5–15 years, whereas its contribution became important later in succession in dry forests. Biomass dynamics tended to be dominated by fewer species in early-successional dry than wet forests, but dominance was strong in both forest types. Overall, our results indicate that biomass dynamics during succession are faster in Neotropical wet than dry forests, with high tree mortality earlier in succession in the wet forests. Long-term monitoring of second-growth tropical forest plots is crucial for improving estimates of annual biomass change, and for enhancing understanding of the underlying mechanisms and demographic drivers.

Recovery dynamics and climate change effects to future New England forests

Forests throughout eastern North America continue to recover from broad-scale intensive land use that peaked in the nineteenth century. These forests provide essential goods and services at local to global scales. It is uncertain how recovery dynamics, the processes by which forests respond to past forest land use, will continue to influence future forest conditions. Climate change compounds this uncertainty. We explored how continued forest recovery dynamics affect forest biomass and species composition and how climate change may alter this trajectory. Using a spatially explicit landscape simulation model incorporating an ecophysiological model, we simulated forest processes in New England from 2010 to 2110. We compared forest biomass and composition from simulations that used a continuation of the current climate to those from four separate global circulation models forced by a high emission scenario (RCP 8.5). Simulated forest change in New England was driven by continued recovery dynamics; without the influence of climate change forests accumulated 34 % more biomass and succeed to more shade tolerant species; Climate change resulted in 82 % more biomass but just nominal shifts in community composition. Most tree species increased AGB under climate change. Continued recovery dynamics will have larger impacts than climate change on forest composition in New England. The large increases in biomass simulated under all climate scenarios suggest that climate regulation provided by the eastern forest carbon sink has potential to continue for at least a century.

Model and Simulation of Interaction Relationship between Forest Carbon Sinks and Economic Growth

Model and Simulation of Interaction Relationship between Forest Carbon Sinks and Economic Growth

Carbon dynamics of China’s forests during 1901–2010: The importance of forest age

The forest ecosystem plays a significant role in long-term carbon sequestration. The magnitude of a forest carbon sink is determined by the combination of intrinsic biotic factors (i.e. forest age) and extrinsic environmental driving factors (i.e. temperature, precipitation, nitrogen deposition). The mechanism of how forest age affects the carbon balance is still unclear. Furthermore, forest age is a useful surrogate variable for analyses of the impact of disturbances on forest carbon and an important parameter for assessing carbon mitigation potential of forests at regional scale. Without considering forest age, large uncertainties exist in the simulating forest carbon cycle at regional scale. In this study, we analyzed the effect of forest age information on carbon uptake of China’s forests based on a process-based model (Integrated Terrestrial Ecosystem Carbon budget, InTEC model) in the last century, with integration of two forest age maps at 1 km spatial resolution which were derived from inventory data and remote sensing AVHRR NDVI. Inter-annual variability of net primary productivity in China’s forests during 1901–2010 based on InTEC model coupled with inventory data and remote sensing data was similar with each other. Meanwhile, the comparison approach indicated that the errors of 5 years in forest age might cause uncertainties of 25% in simulated net ecosystem productivity of China’s forests. We also discussed the significance of forest age in ecosystem process-based model and the uncertainties of carbon balance of China’s forest ecosystem during 1901–2010. Besides, the hypothesis assumed that no large-scale deforestation occurred since1950s and mature forests (and older forests) were covered the whole China. We adjusted forest age structure for different forest types and regions to simulate the effect of changes in forest age on distribution of carbon balance in China. The important finding is that the loss of carbon sink in China’s forests induced by disturbances (i.e. deforestation, afforestation or natural disturbances) is about 3.80 Pg C during last century. Based this hypothesis, China’s forests in the last two decade manifested a large carbon sink (0.23 Pg C a - 1). Currently, many process-based models are not capable of reflecting the impact of land disturbances because the explicit forest age information are lacking. Our study incorporated the forest age in models successfully and explored the effect of forest age on the simulating carbon balance of forests. The application of forest age in large-scale carbon modeling can improve the accuracy of simulated carbon dynamics and explore the uncertainties in carbon cycle models.

Valuation of forest carbon sinks in China within the framework of the system of national accounts

To better promote forest resource management and strengthen the development of forest carbon sink marketization, this paper studied the accounting of forest carbon sinks from 2003 to 2008 based on a system of national accounts (SNA) and data from the latest forest resources inventory in China. The study calculated the value of forest carbon stocks at a total of RMB 817.13 × 109 yuan in 2003 and RMB 839.93 × 109 yuan in 2008, with an average annual increase of 0.55 % from an increase in physical carbon sinks. The total value of forest carbon sinks in 2003 and 2008 was RMB 26.73 × 109 yuan and RMB 29.77 × 109 yuan, respectively, with an average annual growth of 2.18 %. From 2003 to 2008, both stock and flow value of forest carbon sinks increased, but the total net flow value of carbon sinks decreased. The growth rate for the environmentally adjusted Gross Domestic Product (eaGDP) for China’s forest carbon sinks was 17.23 %, outstripping the average growth rate of 9.5 % for the GDP during the same period. The study also indicates that China’s forest carbon sinks affects the GDP in the range of 0.25–0.26 %, and its economic potential is not relatively huge.

Incorrect interpretation of carbon mass balance biases global vegetation fire emission estimates.

Vegetation fires are a complex phenomenon in the Earth system with many global impacts, including influences on global climate. Estimating carbon emissions from vegetation fires relies on a carbon mass balance technique that has evolved with two different interpretations. Databases of global vegetation fire emissions use an approach based on ‘consumed biomass', which is an approximation to the biogeochemically correct ‘burnt carbon' approach. Here we show that applying the ‘consumed biomass' approach to global emissions from vegetation fires leads to annual overestimates of carbon emitted to the atmosphere by 4.0% or 100 Tg compared with the ‘burnt carbon' approach. The required correction is significant and represents ∼9% of the net global forest carbon sink estimated annually. Vegetation fire emission studies should use the ‘burnt carbon' approach to quantify and understand the role of this burnt carbon, which is not emitted to the atmosphere, as a sink enriched in carbon.