Aboveground Biomass Carbon Research Articles

Structure and Ecosystem Services of Three Common Urban Tree Species in an Arid Climate City

Urban forests play a critical role in improving the quality of life in cities, but in arid environments, little is known about the potential benefits and growth conditions of different tree species. Our study aimed to fill this gap by investigating the relationships between tree dimensions, above-ground biomass carbon storage, and shading potential in three common urban trees in the arid city of Jericho, Palestine, (i.e., Ficus nitida, Delonix regia, and Phoenix dactylifera). The trees were chosen according to their distribution in urban locations and tree vitality, with ages ranging from 20 to 90 years. Based on the results from tree structure measurements, the carbon storage and shading potential were calculated using the City Tree model. The results indicate a moderate to strong relationship between tree height, crown diameter, and crown volume for F. nitida and D. regia (R2 = 0.28–0.66), but no relationship for P. dactylifera (R2 = 0.03–0.06). The findings suggest that the analyzed tree species can considerably contribute to the potential benefits of trees in improving the climate of an arid city: D. regia shows a higher median of above-ground biomass carbon storage of 155 kg C tree−1, while P. dactylifera 91 kg C and F. nitida 76 Kg C. D. regia and F. nitida have a higher median of shading potential, (31 m2–41 m2), respectively. Information on the ecosystem services from urban trees and their relationships in terms of species, age, and tree planting urban location are very important for city planners, in relation to sustainable urban green spaces in arid cities.

Forest structures and carbon stocks of community forests with different forest management in Maha Sarakham Province, Thailand

Abstract. Wannasingha W, Gomontean B, Uttaruk Y. 2023. Forest structures and carbon stocks of community forests with different forest management in Maha Sarakham Province, Thailand. Biodiversitas 24: 799-809. Forest management comprises strategies and practices to regulate human activities and the utilization of forest products. Management and regulations have various effects on forest structure, tree diversity and carbon accumulation. This study was conducted in three community forests with different levels of rule regulations and managed duration in the northeast of Thailand. Thirty of 20×20 m plots were placed for recording all trees with diameter at breast height (dbh) ?4.5 cm and >1.3 m height. One hundred and fifty plots of soil samples at 0-25 cm and 25-50 cm depths were also collected for organic carbon analysis. Forest carbon stocks were calculated from the sum of carbon in aboveground biomass (AGB) and soil organic carbon (SOC). The results showed that tree density, basal area, Shannon diversity index and evenness index of the best practices (BP) plots were higher than the plots in which moderate (MP) and slight practices (SP) were applied. Tree heights of the BP and MP forests were higher than the SP forest. The L-shape of dbh class distribution in all community forests means they were secondary forests; tree density was highest in the small dbh class and declined in the bigger size class. The bigger dbh class tree showed higher aboveground carbon (AGC) despite the lower tree density in all community forests. Most of the BP forest plots had the highest carbon stock (93.89, 80.52 and 54.96 Mg C ha-1) and CO2 absorption (344.25, 295.23 and 201.53 Mg CO2equiv.) compared with the others. Our results demonstrate the importance of forest management in affecting forest structures, carbon sequestration and carbon dioxide absorption from the atmosphere to reduce and mitigate climate change.

Carbonated tiger-high above-ground biomass carbon stock in protected areas and corridors and its observed negative relationship with tiger population density and occupancy in the Terai Arc Landscape, Nepal.

Healthy natural forests maintain and/or enhances carbon stock while also providing potential habitat and an array of services to wildlife including large carnivores such as the tiger. This study is the first of its kind in assessing relationships between above-ground biomass carbon stock, tiger density and occupancy probability and its status in protected areas, corridors, and forest connectivity blocks. The dataset used to assess the relationship were: (1) Converged posterior tiger density estimates from camera trap data derived from Bayesian- Spatially Explicit Capture-Recapture model from Chitwan National Park; (2) Site wise probability of tiger occupancy estimated across the Terai Arc Landscape and (3) Habitat wise above-ground biomass carbon stock estimated across the Terai Arc Landscape. Carbon stock maps were derived based on eight habitat classes and conservation units linking satellite (Landsat 7 ETM+) images and field collected sampling data. A significant negative relationship (r = -0.20, p<0.01) was observed between above-ground biomass carbon stock and tiger density in Chitwan National Park and with tiger occupancy (r = -0.24, p = 0.023) in the landscape. Within protected areas, we found highest mean above-ground biomass carbon stock in high density mixed forest (~223 tC/ha) and low in degraded scrubland (~73.2 tC/ha). Similarly, we found: (1) highest tiger density ~ 0.06 individuals per 0.33 km2 in the riverine forest and lowest estimates (~0.00) in degraded scrubland; and (2) predictive tiger density of 0.0135 individuals per 0.33 km2 is equivalent to mean total of 43.7 tC/ha in Chitwan National Park. Comparatively, we found similar above-ground biomass carbon stock among corridors, large forest connectivity blocks (~117 tC/ha), and within in tiger bearing protected areas (~119 tC/ha). Carbon conservation through forest restoration particularly in riverine habitats (forest and grassland) and low transitional state forests (degraded scrubland) provides immense opportunities to generate win-win solutions, sequester more carbon and maintain habitat integrity for tigers and other large predators.

Belowground carbon allocation, root trait plasticity, and productivity during drought and warming in a pasture grass.

Sustaining grassland production in a changing climate requires an understanding of plant adaptation strategies, including trait plasticity under warmer and drier conditions. However, our knowledge to date disproportionately relies on aboveground responses, despite the importance of belowground traits in maintaining aboveground growth, especially in grazed systems. We subjected a perennial pasture grass, Festuca arundinacea, to year-round warming (+3 °C) and cool-season drought (60% rainfall reduction) in a factorial field experiment to test the hypotheses that: (i) drought and warming increase carbon allocation belowground and shift root traits towards greater resource acquisition and (ii) increased belowground carbon reserves support post-drought aboveground recovery. Drought and warming reduced plant production and biomass allocation belowground. Drought increased specific root length and reduced root diameter in warmed plots but increased root starch concentrations under ambient temperature. Higher diameter and soluble sugar concentrations of roots and starch storage in crowns explained aboveground production under climate extremes. However, the lack of association between post-drought aboveground biomass and belowground carbon and nitrogen reserves contrasted with our predictions. These findings demonstrate that root trait plasticity and belowground carbon reserves play a key role in aboveground production during climate stress, helping predict pasture responses and inform management decisions under future climates.

Tree community structure, carbon stocks and regeneration status of disturbed lowland tropical rain forests of Assam, India

Tropical rain forests are global hotspots of biodiversity and key climate change regulators. Despite the decades of conservation efforts, tropical forests are increasingly under continuous threat from human activities. Therefore, understanding the impact of anthropogenic disturbances on biodiversity is necessary for better conservation and management. This study focused on a tropical rainforest located in Kakoi reserve, Assam, in the northeastern Himalayas, aiming to compare tree species composition, diversity, carbon stocks, and regenerating status in two forest sites experiencing disturbance regimes. A total of 55 tree species representing 36 genera and 26 families were recorded in the study area. The tree species richness was slightly higher in moderately disturbed (MD) Dirgha than in the highly disturbed (HD) Kakoi-Rajgarh forest. Tree density and basal area were 582 and 446 individuals ha−1, 38.43, and 32.63 m2 ha−1, respectively, in MD-Dirgha and HD-Kakoi-Rajgarh. Forest stand structure followed a typical reverse J-shaped trend in both sites, with a lesser density of large girth-class (>330 cm girth at breast height) individuals in HD-Kakoi-Rajgarh, reflecting the influence of past onsite disturbances. The analysis of the regeneration strata depicted that seedling and sapling density was 1.8 and 1.4 times lower in HD-Kakoi-Rajgarh compared to MD-Dirgha. Above-ground biomass and total carbon stocks were maximum in MD-Dirgha, followed by HD-Kakoi-Rajgarh. About 63.64% of the recorded tree species, including Critically Endangered Vatica lanceifolia are under IUCN Red List Categories, thus stressing the need for conservation. Our findings suggest that conserving species diversity and carbon reserves in tropical forests would principally depend on minimizing forest loss and degradation.

Estimating Aboveground Carbon Dynamic of China Using Optical and Microwave Remote-Sensing Datasets from 2013 to 2019

Over the past 2 to 3 decades, Chinese forests are estimated to act as a large carbon sink, yet the magnitude and spatial patterns of this sink differ considerably among studies. Using 3 microwave (L- and X-band vegetation optical depth [VOD]) and 3 optical (normalized difference vegetation index, leaf area index, and tree cover) remote-sensing vegetation products, this study compared the estimated live woody aboveground biomass carbon (AGC) dynamics over China between 2013 and 2019. Our results showed that tree cover has the highest spatial consistency with 3 published AGC maps (mean correlation value R = 0.84), followed by L-VOD ( R = 0.83), which outperform the other VODs. An AGC estimation model was proposed to combine all indices to estimate the annual AGC dynamics in China during 2013 to 2019. The performance of the AGC estimation model was good (root mean square error = 0.05 Pg C and R 2 = 0.90 with a mean relative uncertainty of 9.8% at pixel scale [0.25°]). Results of the AGC estimation model showed that carbon uptake by the forests in China was about +0.17 Pg C year −1 from 2013 to 2019. At the regional level, provinces in southwest China including Guizhou (+22.35 Tg C year −1 ), Sichuan (+14.49 Tg C year −1 ), and Hunan (+11.42 Tg C year −1 ) provinces had the highest carbon sink rates during 2013 to 2019. Most of the carbon-sink regions have been afforested recently, implying that afforestation and ecological engineering projects have been effective means for carbon sequestration in these regions.

黄河源园区高寒草地碳储量估算及其影响因素

PDF HTML阅读 XML下载 导出引用 引用提醒 黄河源园区高寒草地碳储量估算及其影响因素 DOI: 10.5846/stxb202207152024 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 2021年度全国草原资源调查项目(DD20211601);国家自然科学基金项目(41371125) Estimated carbon storage and influencing factors of alpine grassland in the source region of the Yellow River 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:高寒草地碳储量及其影响因素研究是认识青藏高原草地生态系统乃至陆地生态系统碳循环和气候变化的关键之一。利用2021年8月上旬地面调查数据与同期高分6号遥感数据建立回归关系,在反演研究区植被地上、地下生物量碳密度和0-40cm土壤层有机碳密度基础上,估算了黄河源园区高寒草地有机碳储量,并通过路径分析探讨了土壤理化性质对碳密度的影响驱动机制。结果表明:(1)2021年黄河源园区地上生物量、地下生物量、0-40cm土壤层碳密度分别为37.65g/m2、1305.28g/m2、4769.11g/m2;总碳储量为100.44Tg(1Tg=1012g),植被层和土壤层碳储量分别分为22.06Tg、78.38Tg,占总碳密度的21.96%、78.04%。(2)黄河源园区高寒草甸和高寒草原两种草地类型地上生物量碳密度分别为41.27g/m2、30.76g/m2;地下生物量碳密度分别为1661.41g/m2、618.74g/m2;0-40cm土壤层有机碳密度分别为5790.99g/m2、2804.04g/m2;研究区碳密度总体呈现南高北低的空间分布现状,分布格局与地表植被类型分布特点较为吻合;(3)路径分析表明,研究区土壤理化性质与草地碳密度关系密切,其中地上生物量碳密度主要受土壤全磷含量和土壤含水率驱动,地下生物量碳密度主要受土壤全氮含量和容重驱动,土壤有机碳密度主要受地下生物量碳密度、土壤容重和pH值驱动。 Abstract:The study of alpine grassland carbon storage and its influencing factors is one of the keys to understand the carbon cycle and climate change of grassland ecosystem and even terrestrial ecosystem on the Qinghai Tibet Plateau. In this paper, the regression relationship between the ground survey data in early August 2021 and the remote sensing data of Gaofen-6 in the same period was established. Based on the inversion of the above-ground and below-ground biomass carbon density of vegetation and the organic carbon density of 0-40 cm soil layer in the study area, the organic carbon storage of alpine grassland in the source region of the Yellow River was estimated, and the driving mechanism of the impact of soil physical and chemical properties on carbon density was discussed through path analysis. The results showed that: (1) In 2021, the above-ground biomass, below-ground biomass and carbon density of 0-40 cm soil layer in the source region of the Yellow River were 37.65 g/m2, 1305.28 g/m2 and 4769.11 g/m2, respectively. The total carbon storage was 100.44 Tg (1 Tg=1012 g). The carbon storage of vegetation layer and soil layer was 22.06 Tg and 78.38 Tg, accounting for 21.96% and 78.04% of the total carbon density respectively. (2) The above-ground biomass carbon density of alpine meadow and alpine steppe in the source region of the Yellow River was 41.27 g/m2 and 30.76 g/m2 respectively; The below-ground biomass carbon density was 1661.41 g/m2 and 618.74 g/m2 respectively; The organic carbon density of 0-40 cm soil layer was 5790.99 g/m2 and 2804.04 g/m2 respectively; The spatial distribution of carbon density in the study area was generally high in the south and low in the north, and the distribution pattern was consistent with the distribution characteristics of surface vegetation types. (3) Path analysis showed that the physical and chemical properties of soil in the study area were closely related to the carbon density of grassland. The above-ground biomass carbon density was mainly driven by soil total phosphorus content and soil moisture, the below-ground biomass carbon density was mainly driven by soil total nitrogen content and soil bulk, and the soil organic carbon density was mainly driven by the below-ground biomass carbon density, soil bulk and pH. 参考文献 相似文献 引证文献

Assessment of aboveground, belowground, and total biomass carbon storage potential of Bambusa vulgaris in a tropical moist forest in Ghana, West Africa

This article reports on a study conducted to assess the carbon storage potential of Bambusa vulgaris, the predominant bamboo species in Ghana. The study aimed to fill a knowledge gap on the potential of bamboo to sequester carbon for climate change mitigation in Ghana. Unlike previous studies that only focused on aboveground biomass, this study assessed belowground, litter, and coarse wood carbon pools. Allometric parameters and models were used to measure the aboveground biomass, while other carbon pools were directly measured. The results showed that the aboveground biomass of B. vulgaris had a carbon stock of 42.85 ± 9.32 Mg C ha−1, which was 73% of the total biomass carbon stock. The carbon stocks of belowground, coarse wood and litter were 8.57, 3.02, and 4.25 Mg C ha−1, respectively. The study also found that B. vulgaris had a high carbon dioxide sequestration potential of 215.39 Mg CO2e ha−1 compared to 147–275 Mg CO2e ha−1 for trees in general. The findings suggest that B. vulgaris could contribute to Ghana's transition to a low-carbon economy through carbon stock monitoring, reporting, and policy development to minimise the impact of climate change. Moreover, the inclusion of relevant carbon pools, including coarse wood and litter, in forest carbon estimates should be encouraged to provide a comprehensive understanding of the plant carbon cycle.

Carbon Stock Sequestration in the Mangrove Forest of Barangay Camudmud MPA, Island Garden City of Samal, Davao Del Norte

The study mainly determined the potential of Barangay Camudmud mangrove forest to sequester carbon dioxide. Five sampling plots were established using the transect line in the study area parallel to the shore. Every sampling plot measured 20 m x 20 m, spaced at 20-m intervals, and covered 2,000 m2. Two true mangrove species were found, namely: Rhizophora stylosa (bakhaw bato) and Sonneratia alba (pagatpat). R. stylosa was more abundant on the site and had a higher value of relative density, frequency, dominance, and importance value index compared to S. alba. Moreover, species diversity in the study area, including the saplings, was low (0.094). Furthermore, based on allometric equations computation for aboveground biomass and belowground organic carbon, R. stylosa sequestered 5.621 Mg ha and 12.528 Mg ha for S. alba. Generally, Barangay Camudmud Marine Protected Area (MPA) mangrove forest had the potential to sequester carbon with a total of 18.149 Mg ha. Although R. stylosa dominated the study area, it sequestered less atmospheric carbon than S. alba. On the other hand, S. alba sequestered more carbon and was less dominant in the area. As a result, the value of r in the Pearson Correlation Coeffi- cient was computed as -0.1717 and was interpreted as a negative correlation that exhibited an inversely proportional relationship between Importance Value Index (IVI) and total carbon sequestration values.

Carbon Stock Assessment in Silvopastoral Systems along an Elevational Gradient: A Study from Cattle Producers in the Sumaco Biosphere Reserve, Ecuadorian Amazon

Silvopastoral system (SPS) has been considered as a sustainable management system contribute to greenhouse gas (GHG) reduction, among other benefits compared with open pasture. However, little research has been conducted on the soil and tree biomass carbon stored in traditional pasture with dispersed trees (PWT) compared with pasture in monoculture (PM). The present study was conducted in the Ecuadorian Amazon Region (EAR), along an elevational gradient from 400 to 2000 masl., within the buffer and transition zone of the Sumaco Biosphere Reserve (SBR), using 71 temporary circular plots of 2826 m2, where 26 plots were stablished in PWT and 45 plots in PM. The main results in PWT show significant differences (p ≤ 0.01) between aboveground carbon biomass (AGCtrees) from 41.1 (lowlands), 26.5 (Middle hills) and 16.7 (high mountains) Mg ha−1 respectively, with an average of 31.0 Mg ha−1 in the whole study area. The total carbon pool along the altitudinal gradient in five components: (AGCtrees), belowground carbon (BGCtrees), pasture carbon (AGClitter+pasture) and carbon in soil components (0–10 and 10–30 cm) for PWT ranged from 112.80 (lowlands) to 91.34 (high mountains) Mg ha−1; while for the PM systems assessing three components (AGClitter+pasture) and carbon in soil components (0–10 and 10–30 cm) ranged from 52.5 (lowlands) to 77.8 (middle zone) Mg ha−1. Finally, the paper shows the main dominant tree species in pasture systems that contribute to carbon storage along elevational gradient and concludes with recommendations for decision-making aimed at improving cattle ranching systems through a silvopastoral approach to mitigate the effects of climate change.

Decreased precipitation reduced the complexity and stability of bacterial co-occurrence patterns in a semiarid grassland.

Grasslands harbor complex bacterial communities, whose dynamic interactions are considered critical for organic matter and nutrient cycling. However, less is known about how changes in precipitation impact bacterial interactions. We conducted precipitation manipulation experiments in the Eastern Eurasian Steppe in China and constructed co-occurrence networks for bacterial communities. The network topological features of the bacterial communities exhibited considerable differences among increased precipitation, control, and decreased precipitation gradients. The bacterial co-occurrence pattern in the increased precipitation gradient was the most complex and stable, with a large network size, followed by those of the control and decreased precipitation gradients. Soil moisture (SM) was the primary factor influencing the complexity, size, and stability of bacterial networks across different precipitation gradients, followed by total nitrogen (TN), belowground biomass, aboveground biomass, and total carbon (TC). Our results indicate that drought conditions reduce the complexity and stability of the bacterial community, and future changes in precipitation will greatly reshape bacterial interactions in semiarid grasslands. Overall, these findings could enhance our understanding of how microbes respond to changing precipitation patterns by regulating their interactions in water-limited ecosystems and will improve our ability to predict the impacts of precipitation regime change on ecosystem nutrient cycling and feedback between ecosystem processes and global climate change.

Strategic reserves in Oregon’s forests for biodiversity, water, and carbon to mitigate and adapt to climate change

Creating strategic forest reserves is essential for stemming the loss of biodiversity and contributing to climate mitigation and adaptation. Meeting preservation targets of 30% protection by 2030, and 50% by 2050 would lead to greater protection of animal taxa and tree species habitat, carbon stocks and accumulation, and forests that are important sources of drinking water. Here, we develop a regional framework to specifically identify at a fine resolution (30 m) high priority forestlands for preservation in Oregon, USA. We include a resilience metric that represents connectivity and topographic diversity, and identify areas within each ecoregion that are ranked high priority for carbon, biodiversity, resilience and drinking water. Oregon has less than 10% of its forestlands protected at the highest levels, yet its temperate forests are among those with the highest carbon densities in the world. Reserves for surface drinking water sources and forest habitat for birds, mammals, amphibians, and reptiles could increase to 50–70% protection at the highest levels by 2050. Protected aboveground biomass carbon could triple to 635 teragrams of carbon by 2050. The ownership of the high preservation priority lands for carbon and biodiversity is primarily federal (67% by 2050) followed by private (28% by 2050), with much less in the other ownerships. Forest reserves could be established on federal lands through executive action, regulation and rule-making, while private landowners could be incentivized to store more carbon, limit harvest in certain areas and transfer ownership to land trusts. Protecting mature and old forests on federal lands fulfills an urgent need for protection and provides a low-cost way to simultaneously meet national and international goals. This study provides a flexible, dynamic framework for identifying areas that are high priority to protect for climate mitigation and adaptation at regional and sub-regional scales.

The Carbon Sink Potential of Southern China After Two Decades of Afforestation.

Afforestation and land use changes that sequester carbon from the atmosphere in the form of woody biomass have turned southern China into one of the largest carbon sinks globally, which contributes to mitigating climate change. However, forest growth saturation and available land that can be forested limit the longevity of this carbon sink, and while a plethora of studies have quantified vegetation changes over the last decades, the remaining carbon sink potential of this area is currently unknown. Here, we train a model with multiple predictors characterizing the heterogeneous landscapes of southern China and predict the biomass carbon carrying capacity of the region for 2002-2017. We compare observed and predicted biomass carbon density and find that during about two decades of afforestation, 2.34 PgC have been sequestered between 2002 and 2017, and a total of 5.32 Pg carbon can potentially still be sequestrated. This means that the region has reached 73% of its aboveground biomass carbon carrying capacity in 2017, which is 12% more than in 2002, equal to a decrease of 0.77% per year. We identify potential afforestation areas that can still sequester 2.39 PgC, while old and new forests have reached 87% of their potential with 1.85 PgC remaining. Our work locates areas where vegetation has not yet reached its full potential but also shows that afforestation is not a long-term solution for climate change mitigation.

Reliability of using vegetation optical depth for estimating decadal and interannual carbon dynamics

Vegetation optical depth (VOD) from satellite passive microwave sensors has enabled monitoring of aboveground biomass carbon dynamics by building a relationship with static carbon maps over space and then applying this relationship to VOD time series. However, uncertainty in this relationship arises from changes in water stress, as VOD is mainly determined by vegetation water content, which varies at diurnal to interannual scales, and depends on changes in both biomass and relative moisture content. Here, we studied the reliability of using VOD from various microwave frequencies and temporal aggregation methods for estimating decadal biomass carbon dynamics at the global scale. We used the VOD diurnal variations to represent the magnitude of vegetation water content buffering caused by climatic variations for a constant amount of dry biomass carbon. This magnitude of VOD diurnal variations was then used to evaluate the likelihood of VOD decadal variations in reflecting decadal dry biomass carbon changes. We found that SMOS-IC L-VOD and LPDR X-VOD can be reliably used to estimate decadal carbon dynamics for 76.7% and 69.9% of the global vegetated land surface, respectively, yet cautious use is warranted for some areas such as the eastern Amazon rainforest. Moreover, the annual VOD aggregated from the 95% percentile of the nighttime VOD retrievals was proved to be the most suitable parameter for estimating decadal biomass carbon dynamics among the temporal aggregation methods. Finally, we validated the use of annual VOD for estimating interannual carbon dynamics by comparing VOD changes between adjacent years against eddy covariance estimations of gross primary production from flux sites over several land cover classes across the globe. Despite the large difference in spatial scales between them, the positive correlation obtained supports the capability of satellite VOD in quantifying interannual carbon dynamics.

Topography alters stand structure, carbon stocks and understorey species composition of Cedrela odorata plantation, in a semi-deciduous forest zone, Ghana

Pure plantations established across different topographic positions may respond differently and exhibit varied stand characteristics. However, there is limited information on variability of pure plantation stand attributes along topographic gradients, particularly in West Africa. This study examined the stand structure, carbon stocks and understorey woody species composition of relatively older Cedrela plantations on three topographic positions within the deciduous forest zone of Ghana. About 15, 40 × 40 m plots were surveyed in 23-year-old Cedrela odorata plantations located on hill top, flat terrain and valley bottoms in the Tinte Bepo Forest Reserve, Ghana. Data were analysed using ANCOVA, Bayesian modelling of diameter distribution and correspondence analysis.Diameter at breast height (DBH; p<0.0001), total height (p<0.025), and stem density (p<0.001) were significantly different among the three topographic areas. Trees on the valley bottom had the highest DBH, total height, and biomass carbon while the highest stem density and basal area occurred on the flat terrain. Slope explained 63% of the total variability in the stem density of the C. odorata stand. Bayesian modelling of diameter distribution revealed that the 3-parameter Weibull function better fitted the diameter distribution of the trees on the hill top while the Johnson SB was more appropriate at the flat terrain and the valley bottom. Understorey woody species composition was significantly different among geomorphic positions. Differences in aboveground biomass carbon stocks among topographic positions were not significant.The local topography therefore severely alters plantation stand structure, leading to different distribution models being adopted at different topographic positions. Furthermore, cedrela plantations facilitate climate mitigation, species recruitment and functional/trait diversity differences along topographic gradients. This has implications for large scale plantation development especially on heterogeneous terrains.

Above-ground Carbon Stocks of Tectona grandis and Gmelina arborea Plantations in Njala University, Southern Sierra Leone

The unprecedented increase in atmospheric CO2 concentration has attracted global research attention on the potential role of tree plantations in climate change mitigation. There is an urgent need to estimate the above-ground biomass (AGB) and carbon stock in forest plantations. This is particularly essential for Sierra Leone, where above-ground biomass (AGB) and carbon stock data are presently lacking. This study estimated the above-ground biomass accumulation and carbon stock of Tectona grandis Linn.f. and Gmelina arborea Roxb. in the spacing and plantation trials at Njala University, Southern Sierra Leone. The assessment was based on a total inventory of trees having a diameter at breast height (DBH) ≥ 5 cm and tree height. Above-ground biomass (AGB) was estimated using the allometric equation by Chave et al. (2005), and above-ground carbon (AGC) stock was calculated by multiplying the biomass with a conversion factor of 0.5. The result showed that the mean above-ground carbon stock for Gmelina arborea was higher in the plantation trial (25.2 t ha-1) than in the spacing trial (7.5 t ha-1). For Tectona grandis, the mean above-ground carbon stock was similarly higher in the plantation trial (6.6 t ha-1) than in the spacing trial (1.5 t ha-1). The results further suggest that the variation in the means of above-ground carbon stock is not dependent on the tree species type and experimental site because there were no significant differences (P&gt;0.05) between the tree species and experimental sites.

Species Diversity, Aboveground Biomass, and Carbon Storage of Watershed Forest in Phayao Province, Thailand

Restoration of watershed forest ecosystems can perform different disturbance regimes over remnant forests, which can ultimately affect plant diversity, soil formation, and carbon storage. To address an issue, this study assessed tree species diversity, aboveground biomass (AGB), and aboveground carbon (AGC) storage of the watershed forest in Phayao Province, Thailand. Data collection was conducted in 18 plots along nine watersheds along the topographic gradients. Tree height and diameter at breast height (DBH) were collected. AGB of vegetation was estimated by using the allometric equation. Likewise, AGC storage was evaluated from half of AGB. A total of 133 species belonging to 105 genera and 39 families were recorded from the watershed forests (1.8 ha). Mixed deciduous forest (MDF) and dry evergreen forest (DEF) exhibited high density and high diversity index, respectively. The highest value of total AGC storage was found in the MDF with 91.2 ton C/ha, following by DEF (78.3 ton C/ha) and dry dipterocarp forest (DDF) (60.5 ton C/ha). Detrended correspondence analysis (DCA) revealed that the occurrences of Albizia saman, Hopea odorata, Lagerstroemia calyculata, and Acrocarpus fraxinifolius related to AGB, AGC, slope, and tree canopy in the DEF. Intensity of slope influenced tree species occurrence in the watershed forest of Phayao.

Predicting aboveground biomass carbon sequestration potential in hybrid poplar clones under afforestation plantation management in southern Ontario, Canada

Afforestation systems as a pathway for natural climate solutions contributing to terrestrial C sequestration are influenced by agroclimatic conditions, tree species and clones. This study validated a regression equation to predict aboveground biomass C (AGBC) sequestration potentials of hybrid poplar clones under afforestation plantation and compared these clones’ adaptability to three levels of land suitability in four afforestation sites in southern Ontario, Canada. Results validated the proven ability of the GenOnBio model to reasonably predict AGBC content in all tested clones. This research suggests that DN154 and FFC1 having C sequestration rates of 2.19 and 2.13 Mg C ha-1 y-1, respectively, are suitable for marginal lands having high land suitability condition. In contrast, DTAC29, and DTAC26 (0.56 and 0.88 Mg C ha-1 y-1, respectively) should not be selected for the above land suitability. On marginal lands with severe limitations, NM6 (1.53 Mg C ha-1 y-1) showed the highest adaptability for AGBC sequestration. Our findings confirm that poplar afforestation on marginal lands in southern Ontario, at least up to the age of 15 years, can significantly contribute to AGBC sequestration, which in turn can have significant positive influence on the current 2 billion tree planting program initiated by the federal government.

Fractions, stability, and influencing factors of soil organic carbon under different land-use in sodic soils

Salt-affected soils have considerable carbon sequestration potential in aboveground biomass and soil organic carbon (SOC). However, organic carbon pool characteristics and the significant important factors affecting the land use of sodic soils have not been clearly elucidated. In this study, 252 samples were collected from 20 typical sodic soil sites across the western Songnen Plain, China. This study investigated the effects of five land-use types, that is, saline wasteland (SWL), degraded grassland (GL), forestland (FL), upland (UL), and paddy fields (PF), on sodic soil SOC fractions and stabilities to find that UL and PF decreased salinity and alkalinity, but increased soil nutrient and water stability aggregate (WSA) contents and stability. Compared with degraded natural land-use types (SWL and GL), FL and croplands (UL and PF) increased the physical protection of SOC and aggregate-associated SOC contents. Furthermore, cropland, especially PF, increased nonlabile organic carbon (NOC) (7.47 g kg−1), labile organic carbon (LOC) (3.79 g kg−1), dissolved organic carbon (DOC) (0.16 g kg−1), and mineralizable organic carbon (MOC) (0.41 g kg−1) fractions. Furthermore, compared with degraded natural lands, PF increased NOC ratios (59.65%) and carbon management index (CMI) (126.1), thus increasing organic carbon content and stability. Structural equation modelling revealed that improvements in soil properties, total nitrogen (TN), WSA, electrical conductivity (EC), and pH were the crucial factors for increasing SOC stock in sodic soils. We concluded that the positive effect that PF had on SOC content and stability were much greater than that of the other land-use types, and that PF was the optimal management practice for increasing SOC sequestration capacity in sodic soils.

Evaluation of Carbon Stock, Nitrogen, and Phosphorus Contents in Forest Soil and Litter at Bintulu’s Acacia mangium Chronosequence Age Stand Plantation, Sarawak, Malaysia

Acacia mangium is the major species used in the forest plantation industry due to its fast-growing feature. However, there is still a lack of research on the nutrient concentration, specifically nitrogen (N) and phosphorus (P), as well as carbon content in Malaysia’s forest plantations. Hence, this study aimed to assess the total N and P concentrations in the soil and forest litter. Carbon content in different ages (Year 2, Year 4, and Year 9) of A. mangium plantation (together with a natural forest as a comparison) was also determined. This study was conducted in a Licensed Planted Forest, Bintulu, Sarawak, Malaysia. The natural forest was a control variable in this study. The Kjeldahl method was used to determine the total N. In contrast, dry ashing and double acid (Mehlich-1) methods were used to determine the total P in forest litter and available P in forest soil. The allometric biomass equations were used to estimate the carbon content. Total N in forest litter and forest soil was similar in all treatments. Total P in the Year 4 stand was significantly higher than in the Year 2 stand, yet, no differences were observed when compared with the control. Whereas soil available P showed no significant difference among all treatments. Acacia mangium stands recorded significantly lower total carbon content compared to the control. Old plantation stands contained much more total carbon stock than the younger stands. Also, deadwood is important in determining total carbon stock when it can account for almost 59% of above-ground biomass (AGB) carbon stock. This study revealed that forest plantations could function well in providing an adequate supply of available nutrients as well as have a potential role in carbon sink.