Forest Biomass Carbon Density Research Articles

林业活动对区域森林生物量碳源汇格局的影响——以南平市为例

PDF HTML阅读 XML下载 导出引用 引用提醒 林业活动对区域森林生物量碳源汇格局的影响——以南平市为例 DOI: 10.5846/stxb202201110098 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金重大项目（32192434）；"十三五"国家重点研发计划项目（2016YFD0600200） Effects of forestry activities on regional forest biomass carbon source and carbon sink pattern: A case study in Nanping City Author: Affiliation: Fund Project: The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan) 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:林业活动在一定程度上影响着区域森林的时空分布格局和碳汇/源功能。明确并量化林业活动对区域森林碳汇功能的影响与空间分布，对于区域森林碳汇提升和实现区域"碳中和"具有重要意义。以国家级生态示范区福建省南平市为例，以多期森林资源规划调查数据为基础，采用IPCC材积源-生物量法，基于土地利用类型的时空变化和林业活动类型划分，分类分析了南平市森林碳源和碳汇的空间分布特征，并量化了不同林业活动（一直保持为森林、人工造林、自然恢复、毁林和森林退化）对森林碳汇和碳源的影响。研究结果表明，2013年南平市森林碳储量总量为80.84Tg C，2020年森林碳储量总量增加至89.87Tg C，年均变化量为1.29Tg C/a （或4.73Tg CO2/a）。平均胸径、公顷蓄积等林分因子是当前主要影响森林碳储量的因素。在其他影响因素中，暗红壤分布区的森林生物质碳密度较高而在水稻土分布区则较低；此外，高海拔、中等立地质量土地上的森林碳密度较高。对于不同林业活动，2013-2020年南平市一直保持为森林（森林经营）、自然恢复增加的天然林和人工造林分别使森林生物质碳储量增加了0.34Tg C/a、0.85Tg C/a和1.05Tg C/a，同期因毁林和森林退化导致森林生物质碳储量分别减少0.75Tg C/a和0.42Tg C/a，森林生物质碳储量净增加1.09Tg C/a （或3.98Tg CO2/a），明显低于2013-2020森林碳储量净增量。对于土地利用变化较剧烈的区域，本文基于土地利用变化且区分林业活动路径的方法，能更准确地反映森林的碳汇和碳源及时空格局。2013-2020年间南平市一直保持为森林的生物质碳密度仅增长0.22Mg C hm-2 a-1，成熟林、过熟林面积占比增加使森林平均生长速率下降可能是主要原因。而同期通过自然恢复和人工造林使森林生物质碳密度分别增长4.00Mg C hm-2 a-1和4.10Mg C hm-2 a-1。优化龄组结构提升森林生长量、减少毁林和防止森林退化可以作为该区域未来森林增汇减排的有效举措。 Abstract:Forestry activities, to some degree, affect the spatio-temporal pattern of regional forest as a carbon sink or source. With the aim to improve regional forest carbon sink and achieve to "Carbon Neutral" strategically, it is of great significance to clarify and quantify the impacts forestry activities on forest carbon sink or source on spatial level. Taking Nanping City, Fujian Province, a national ecological demonstration, as an example, this paper analyzed the spatial distribution of carbon sources and carbon sinks caused by land use changes and five forest activities, which are remaining forest as forest, afforestation, natural recovery, deforestation and forest degradation, based on the local forest resources planning survey data during 2013-2020 and the IPCC volume-biomass method. The results showed that the total forest carbon storage in Nanping City was 80.84Tg C and 89.87Tg C in 2013 and 2020, respectively, with a mean annual change of 1.29Tg C/a (or 4.73Tg CO2/a). Forest stand characters such as the mean Diameter at Breast Height (DBH) and the growing stock per hectare are the most important factors that mainly affect forest carbon storage. Among other influencing factors, the forest biomass carbon density is higher in the dark red soil distribution area but lower in the paddy soil distribution area, and it is higher in the high altitude, medium-quality sites. For the five forestry activities, the forest remaining as forest, natural restoration and afforestation increased the forest biomass carbon stocks (BCS) by 0.34Tg C/a, 0.85Tg C/a and 1.05Tg C/a respectively, while deforestation and forest degradation decreased BCS by 0.75Tg C/a and 0.42Tg C/a, respectively, which led to a net increase of forest BCS by 1.09Tg C/a (or 3.98Tg CO2/a) in Nanping during 2013-2020. Significantly lower than the net increase in forest carbon storage in 2013-2020. For those regions with intense land use changes, our method based on land use change or forest activities could more accurately estimate regional forest carbon sink and carbon source and their spatial pattern. Forest remaining forest only increased the forest biomass carbon density (BCD) by 0.22Mg C hm-2 a-1 in Nanping during 2013-2020, which was likely due to average forest growth rate decreasing caused by the increase in the area proportion of mature and over-mature forests. However, the BCD was increased by 4.00Mg C hm-2 a-1 and 4.10Mg C hm-2 a-1 for the new natural forests and plantations during 2013-2020. Optimizing forest age group structure to improve forest growth, reducing area of deforestation and forest degradation could be the optional measures to increase regional forest carbon sink and reduce carbon emission from forest. 参考文献 相似文献 引证文献

Spatially explicit changes in forest biomass carbon of China over the past 4 decades: Coupling long-term inventory and remote sensing data

Quantification of the spatial pattern of forest carbon (C) sinks in high resolution is helpful to reveal the factors that affect the C cycle and provides valuable information for developing sustainable forest management policies. Here we developed a method using the data of long-term forest inventories (1977–2018) and spatially-explicit remotely sensed information from land-use maps and the Normalized Difference Vegetation Index (NDVI) datasets, to estimate the spatial and temporal variation of forest biomass C in China. At first, we calculated forest biomass C stocks using the refined Continuous Biomass Expansion Factor (CBEF) model with parameters for each forest type based on eight national forest inventories. Secondly, based on multi-temporal land-use remote sensing and national forest inventory datasets, we obtained forest coverage datasets with high resolution (1 km*1 km). Thirdly, we downscaled the forest biomass C density using the calibrated forest coverage maps and the maximum NDVI values derived from GIMMS-NDVI3g imagery. Our results showed that China's forest functioned as a C sink of 3777.73 Tg C, and the C density of forest stands increased from 35.41 Mg C ha−1 during 1977–1981 to 43.95 Mg C ha−1 during 2014–2018. In addition, the validation results for most of the provinces based on published inventory estimates during the eight periods showed that the forest area at the pixel scale was successfully calibrated. From this, we produced the maps with a finer resolution for a series of spatially continuous forest biomass carbon density distribution and carbon sinks. Notably eight major forest projects have accounted for 44%–51% of the forest C stocks added in China from 1977 to 2018. Our research provides new insights for understanding and monitoring the spatiotemporal variations in of forest biomass and key information to support the development of new afforestation policies moving forward.

Mapping aboveground biomass and carbon in Shanghai's urban forest using Landsat ETM+ and inventory data

Quantifying the spatiotemporal distribution of forest biomass carbon (FBC) is vital for the management of urban forests in accordance with the rapid urbanization. This paper presents a method for quantifying and estimating the urban FBC in Shanghai, China, between 2005 and 2015, using data from 93 sampling forest plots and Landsat ETM + data. Our study included an analysis of the choice of predicted factors to estimate FBC and the method of carbon density estimation employed in the estimation. The results showed that combining regression analysis and spatial analysis to map forest carbon stocks at city level make available FBC estimates for the urban forests of Shanghai, China. Based on the proposal method, there was a decreasing trend of carbon density from downtown areas to outer suburban areas. About 92 % of the overall FBC storage in Shanghai distributed in the suburban areas whereas the urban areas shared a fraction amounting to only 8 % in 2015. From 2011–2015, the total urban forest carbon storage gradually increased by 32.3 %, whereas the average carbon density gradually decreased by 8.21 % in the urban areas. The associated values both increased continuously from 2005–2011, from 2005 to 2011, but the average carbon storage density decreased in the suburban districts. The total carbon stocks in the estimated forest biomass across Shanghai were about 1.5 Tg in 2005 and 2008, and 1.7 Tg in 2011 and 2015, while the associated average FBC density remained at about 17.5 t/ha from 2005 to 2015. This study provides important information required to manage the urban forest stand for optimal carbon sequestration.

Mapping global forest biomass and its changes over the first decade of the 21st century

Forests played an important role in carbon sequestration during the past two decades. Using a model tree ensemble method (MTE) to regress the seven reflectance bands of EOS-Terra-MODIS satellite data against country level forest biomass carbon density (BCD) of 2001–2005 provided by United Nations’s Forest Resource Assessment (FRA), we developed a global map of forest BCD at 1 km ×1 km resolution for both 2001–2005 and 2006–2010. For 2006–2010, the total global forest biomass carbon stock is estimated as 279.6±7.1 Pg C, and the tropical forest biomass carbon stock is estimated as 174.4±5.4 Pg C. During the first decade of the 21st century, we estimated an increase of global forest biomass of 0.28±0.75 Pg C yr−1. Tropical forest biomass carbon stock slightly decreased (−0.31±0.60 Pg C yr−1); by contrast, temperate and boreal forest biomass increased (0.58±0.28 Pg C yr−1) during the same period. Our estimation of the global forest biomass carbon stock and its changes is subject to uncertainties due to lack of extensive ground measurements in the tropics, spatial heterogeneity in large countries, and different definitions of forest. The continuously monitoring of forest biomass carbon stock with MODIS satellite data will provide useful information for detecting forest changes.

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.

Effects of Drought Disturbance on Forest Biomass in Southwestern China

Forest growth is easily influenced and disturbed by extreme climate change. Exploring the spatial and temporal changes of forest biomass and its response to climate change is of significant importance to assess the carbon dynamics of terrestrial ecosystem. During 2009-2012, continuous severe drought happened in southwestern China, and large-scale extreme drought occurred in 2009 and 2010. Although previous studies have revealed the responses of vegetation to the drought in southwestern China, there is no study on quantifying the effects of drought disturbance on forest biomass. In this study, annual forest Biomass Carbon Density (BCD) was estimated first using forest resources statistics of China (1984-2013), the Global Inventory Modeling and Mapping Studies (GIMMS) Normalized Difference Vegetation Index (NDVI) and elevation data in southwestern China. Then the effects of drought disturbance on forest biomass were evaluated through correlation analysis combined with the Palmer Drought Severity Index (PDSI) data. The results showed that: (1) the accuracy of forest BCD was enhanced by using Inventory-satellite-based method, and the accuracy reached R2=0.86 (P<0.001); (2) from 2000 to 2013, the mean BCD in southwestern China was 38.66 Mg C/ha, and was increasing annually with rate of 0.102 Mg C/ha; (3) forest BCD continuously declined due to the drought from 2010 to 2012, and in the extreme drought year 2010, BCD anomaly reduced to -1.004 and returned to 0.371 in 2013. Our results indicate that drought disturbances could significantly impact the forest biomass and the carbon dynamics of terrestrial ecosystem.

Influence of Tree Species Composition and Community Structure on Carbon Density in a Subtropical Forest.

We assessed the impact of species composition and stand structure on the spatial variation of forest carbon density using data collected from a 4-ha plot in a subtropical forest in southern China. We found that 1) forest biomass carbon density significantly differed among communities, reflecting a significant effect of community structure and species composition on carbon accumulation; 2) soil organic carbon density increased whereas stand biomass carbon density decreased across communities, indicating that different mechanisms might account for the accumulation of stand biomass carbon and soil organic carbon in the subtropical forest; and 3) a small number of tree individuals of the medium- and large-diameter class contributed predominantly to biomass carbon accumulation in the community, whereas a large number of seedlings and saplings were responsible for a small proportion of the total forest carbon stock. These findings demonstrate that both biomass carbon and soil carbon density in the subtropical forest are sensitive to species composition and community structure, and that heterogeneity in species composition and stand structure should be taken into account to ensure accurate forest carbon accounting.

Changes in forest biomass over China during the 2000s and implications for management

Abstract By integrating the reflectance of 7 spectral bands of the MODerate-resolution Imaging Spectroradiaometer (MODIS) and forest inventory data with an empirical statistical model, we mapped the spatial distribution of total forest biomass carbon density (BCD) at 1 km resolution in China during the past decade. The empirical statistical model can explain 75% of the variation in BCD across 29 provinces in China (R2 = 0.75, P

Spatial Variation of Biomass Carbon Density in a Subtropical Region of Southeastern China

Spatial pattern information of forest biomass carbon (FBC) density in forest ecosystems plays an important role in evaluating carbon sequestration potentials and forest management. The spatial variation of FBC density in a subtropical region of southeastern China was studied using geostatistics combined with Moran’s I and geographical information systems (GIS). Forest biomass carbon density values were variable, ranging from 0.12 Mg ha−1 to 182.12 Mg ha−1, with an average of 27.33 Mg ha−1. The FBC density had the strongest positive correlation with forest age, followed by forest litter and elevation. The FBC density had significant positive spatial autocorrelation revealed by global Moran’s I. Clear spatial patterns were observed based on local Moran’s I. High FBC density values were mainly distributed in the northwestern and southwestern parts of Zhejiang province, which were related to adopting long-term policy of forest conservation in these areas, while low FBC density values located in the middle part and southeastern coastal area of the study area due to low forest coverage and intensive management of economic forests. The Moran’s I combined with geostatistical interpolation proved to be a useful tool for studying spatial variation of FBC density.

我国东北天然林保护工程区森林植被碳储量研究

以东北天然林保护工程区森林生态系统为对象，通过对其主要森林类型进行调查，探讨天保工程经营区划对森林植被固碳现状的影响，并结合已有的东北林区生物量与蓄积量数据库，建立了东北林区主要树种组的生物量-蓄积量回归模型，然后以第7次森林资源清查为基础，对东北天保工程区森林植被碳储量进行估算，以期为全国森林生物量的估算和天保工程的评估提供参考。结果表明，不同经营区之间（重点公益林、一般公益林和商品林）森林植被碳密度的差异并不显著，这可能与天然林保护工程实施初期经营区划的标准、样地的选择以及天保工程实施过程中粗放的管理方式有关。东北天保工程区森林植被碳储量为1045 TgC，占东北、内蒙古三省森林植被总碳储量的68%；工程区以天然林为主，占工程区总植被碳储量的97%。工程区森林植被平均碳密度为41 Mg/hm²，较东北、内蒙古三省平均植被碳密度高14%；工程区植被碳密度随林龄的增加逐渐增大，由幼龄林的13 Mg/hm²到过熟林的63 Mg/hm²。因此，继续加强天然林保护工程的实施，提高其林分质量，这对未来我国森林碳汇潜力的增加和森林的可持续发展都具有重要的意义。;The Natural Forest Protection Program (NFPP), which aims at protecting ecological resources and achieving sustainable forest management, has been implemented for 10 years in Northeast China. Under the program forest ecosystems in the region have been divided into three management areas-Key conservation, General conservation and Commercial forest. Each of these three types of forest land is subject to different management measures (protecting or logging). Estimating carbon storage of forest vegetation in these areas is important both for understanding the capacity of forests in the Northeast region for carbon sequestration and as an aid to assessing the effectiveness of the NFPP in meeting its goals. To address this important need, this study selected five major forest types in the Northeast forest region-larch forest, birch forest, coniferous mixed forest, broadleaved mixed forest, coniferous and broadleaved mixed forest. Each forest type was divided into four age classes-young, mid-aged, premature and over mature forest. Tree biomass was calculated through species-specific allometric equation models based on field measurement in the Daxing'anling, Xiaoxing'anling and Changbai mountains. At the same time, an dataset on biomass and volume of the main forest types in the Northeast forest region was established based on existing data from former studies. Since some studies have found that the relationship between forest biomass and volume fits relatively well within a liner regression framework, this study utilized this two data sources noted above to establish biomass-volume line regression models of the main tree species groups in the Northeast, focusing primarily on the five major forest types identified above. Forest biomass carbon storage in areas under the NFPP in the Northeast region was subsequently estimated based on data from the 7th National Forest Resource Inventory. Results showed that forest biomass carbon storage based on field measurement did not varied significantly with management areas, which likely reflects both the classification standard for the management areas and the relatively short period since the NFPP have been implemented. On the other hand, forest biomass carbon storage of lands under the NFPP was 1045 TgC, which accounted for 68% of total forest biomass carbon storage in the Northeast provinces of Jilin, Heilongjiang and Inner Mongolia. Moreover, forest biomass carbon density of lands under the program (41 Mg/hm²) exceeded that of the average biomass carbon density in Northeast provinces (36 Mg/hm²). Simultaneously, in the lands of the NFPP, forest biomass C density increased with forest age class, from 16.4 Mg/hm² in young to 63.0 Mg/hm² in over mature forest, thus the relative large areas of young and mid-aged forests (together accounted for 61% of total forest area), implying its great C sequestration potential in the future. In addition, forest biomass carbon storage was dominated by natural forest, which accounted for 97% of total biomass carbon storage under the NFPP. On an overall basis, the Natural Forest Protection Program acts an important role in the Northeast forest region, and it should be played an increasingly important role in forest ecosystem carbon sequestration and sustainable forest management in the next implemented decade.

Satellite Data-Based Phenological Evaluation of the Nationwide Reforestation of South Korea

Through the past 60 years, forests, now of various age classes, have been established in the southern part of the Korean Peninsula through nationwide efforts to reestablish forests since the Korean War (1950–53), during which more than 65% of the nation's forest was destroyed. Careful evaluation of long-term changes in vegetation growth after reforestation is one of the essential steps to ensuring sustainable forest management. This study investigated nationwide variations in vegetation phenology using satellite-based growing season estimates for 1982–2008. The start of the growing season calculated from the normalized difference vegetation index (NDVI) agrees reasonably with the ground-observed first flowering date both temporally (correlation coefficient, r = 0.54) and spatially (r = 0.64) at the 95% confidence level. Over the entire 27-year period, South Korea, on average, experienced a lengthening of the growing season of 4.5 days decade−1, perhaps due to recent global warming. The lengthening of the growing season is attributed mostly to delays in the end of the growing season. The retrieved nationwide growing season data were used to compare the spatial variations in forest biomass carbon density with the time-averaged growing season length for 61 forests. Relatively higher forest biomass carbon density was observed over the regions having a longer growing season, especially for the regions dominated by young (<30 year) forests. These results imply that a lengthening of the growing season related to the ongoing global warming may have positive impacts on carbon sequestration, an important aspect of large-scale forest management for sustainable development.

Terrestrial vegetation carbon sinks in China, 1981–2000

Using China’s ground observations, e.g., forest inventory, grassland resource, agricultural statistics, climate, and satellite data, we estimate terrestrial vegetation carbon sinks for China’s major biomes between 1981 and 2000. The main results are in the following: (1) Forest area and forest biomass carbon (C) stock increased from 116.5×106 ha and 4.3 Pg C (1 Pg C = 1015 g C) in the early 1980s to 142.8×106 ha and 5.9 Pg C in the early 2000s, respectively. Forest biomass carbon density increased form 36.9 Mg C/ha (1 Mg C = 106 g C) to 41.0 Mg C/ha, with an annual carbon sequestration rate of 0.075 Pg C/a. Grassland, shrub, and crop biomass sequestrate carbon at annual rates of 0.007 Pg C/a, 0.014–0.024 Pg C/a, and 0.0125–0.0143 Pg C/a, respectively. (2) The total terrestrial vegetation C sink in China is in a range of 0.096–0.106 Pg C/a between 1981 and 2000, accounting for 14.6%–16.1% of carbon dioxide (CO2) emitted by China’s industry in the same period. In addition, soil carbon sink is estimated at 0.04–0.07 Pg C/a. Accordingly, carbon sequestration by China’s terrestrial ecosystems (vegetation and soil) offsets 20.8%–26.8% of its industrial CO2 emission for the study period. (3) Considerable uncertainties exist in the present study, especially in the estimation of soil carbon sinks, and need further intensive investigation in the future.