Forest Organic Carbon Research Articles

Canopy Leaching Rather than Desorption of PM2.5 From Leaves Is the Dominant Source of Throughfall Dissolved Organic Carbon in Forest

AbstractDissolved organic carbon (DOC) in throughfall plays a vital role in providing carbon and energy to organisms in forests. We utilized carbon isotope analysis to allocate the sources of throughfall DOC, including leaching from plant tissues, PM2.5 deposition on plant foliage, and precipitation. Rainwater, PM2.5, and throughfall samples were collected from pine and oak forests between March and November 2021. The mean concentration of throughfall DOC was 7.9 mg L−1, approximately six times higher than that of rainfall. The mean Δ14C of throughfall DOC was −38.2‰, ∼200‰ higher than that of rainwater or PM2.5. Mass balance estimates revealed that canopy leaching contributed to ∼83% of throughfall DOC, while desorption of PM2.5 and rainwater accounted for only ∼3% and ∼14% of throughfall DOC, respectively. These results clearly highlight canopy leaching as the primary source of carbon input to the forest floor, with a relatively minor contribution from PM2.5 desorption on leaves.

A systematic increase in the slope of the concentration discharge relation for dissolved organic carbon in a forested catchment in Vermont, USA

The production, mobilization and fluvial transport of dissolved organic carbon (DOC) in temperate forests are important components of the carbon cycle that are influenced by ongoing changes in climate. Numerous studies have reported temporal trends in stream water DOC concentrations and have attributed changes in concentrations to climatic and hydrologic variables. Fewer studies have reported trends in concentration-discharge (C-Q) relations for DOC. The goal of this study was to detect and quantify changes in DOC concentration and slope of the C-Q relation from 1991 to 2018 in an intensively sampled forested research watershed in northern Vermont. Stream water DOC concentration and slope of the C-Q relation increased over time as did precipitation, stream discharge, and air temperature. The increases in DOC concentration and slope of the C-Q were substantially greater in the summer and fall (autumn) than in winter and spring. The largest increases in the magnitude of C-Q slopes occurred in the December, October and September. The increases in slope of the C-Q relation in summer and fall were larger for baseflow than for storm flow. The increases in DOC concentration and slope of the C-Q relation over time may be related to increasing temperature, longer growing seasons, and associated increases in production and microbial decomposition of soil organic matter that supplies DOC for mobilization to streams. The results suggest that in a changing climate, C-Q relations may not necessarily be stationary and therefore analyses that attempt to estimate future DOC concentrations and loads should consider potentially changing C-Q relations over time.

Soil Organic Carbon in Forest and Other Land Use Types at Bengkulu City, Indonesia

Conversion of natural forest into agricultural land uses has decreased soil organic carbon (SOC) and increased carbon emission into the atmosphere, but proper management of agricultural land can sequester carbon from the atmosphere and increase the SOC. This study was conducted to estimate the SOC content and storage in a forest, agroforestry land, oil palm plantation, and agricultural experimental field and to analyze the correlation between the SOC and other soil characteristics at Bengkulu City, Indonesia. Soil were sampled from the following depths: 0–10 cm, 10–20 cm, and 20–30 cm. The biomass of litter and ground cover was also sampled. This study found that the forest had the highest average SOC content from the three depths, and 0–30 cm depth SOC storage, while the agroforestry system had the lowest of both SOC content and storage. The 0–10 cm depth had the highest SOC content and storage, while the 20–30 cm depth had the lowest of both variables. The SOC was positively correlated with litter biomass, field capacity, exchangeable potassium, cation exchange capacity, and negatively correlated with bulk density and exchangeable calcium, but not correlated with total nitrogen and available phosphorus. High litter biomass input is the key to the maintenance of high SOC.

National-scale spectroscopic assessment of soil organic carbon in forests of the Czech Republic

Soil Carbon (C) is central to the functioning of ecosystems and climate change mitigation. It represents the largest terrestrial pool and much of it, is stored in forest soils. Soil Organic Carbon (SOC) in a forest varies not only laterally, but also vertically (i.e., with depth). However, the SOC content of forest soil horizons has not been investigated over large scales, despite its importance for framing our understanding of soil function. Visible–Near Infrared (vis–NIR) reflectance spectroscopy enables rapid and cost-effective examination of forest SOC distribution, both laterally and vertically. This study aims to evaluate the potential of vis–NIR spectroscopy for classifying and predicting the SOC concentration of organic and mineral horizons in forests of the Czech Republic. We investigated 1080 forest sites across the country, each with five soil horizons, representing the Litter (L), Fragmented (F), and Humus (H) organic horizons, as well as the A1 (depth of 2–10 cm) and A2 (depth of 10–40 cm) mineral horizons. We, then, used Support Vector Machines (SVMs) to classify the soil horizons based on their spectra and also to model the SOC concentration of (i) the profile (organic and mineral horizons together), (ii) only the organic horizons, (iii) only the mineral horizons, and (iv) each individual horizon separately. The models were validated using 10-repeated 10-fold cross-validation. Results show that the SVM with radial basis kernel could accurately classify the soil horizons (Correct Classification Rate (CCR) of 70% and Kappa coefficient of 0.63). The SOC model developed for the soil profile performed well (R2 = 0.76 and RMSE = 1.63%). The model of the combined organic horizons was considerably more accurate than that of the combined mineral horizons (R2 = 0.78 and R2 = 0.53, respectively). Estimates of SOC in the individual soil horizons had R2 values greater than 0.63 but those of the F and A1 models were better with R2 > 0.70. The study indicates that vis–NIR spectroscopy can effectively characterize the SOC concentration of the highly variable forest soil horizons in the Czech Republic.

A New Approach Using Modeling to Interpret Measured Changes in Soil Organic Carbon in Forests; The Case of a 200 Year Pine Chronosequence on a Podzolic Soil in Scotland

Scotland is continuing to afforest land in order to combat climate change, but the long-term capacity for carbon sequestration in forest soils is still uncertain. Soil organic carbon stock changes were studied in a >120 year-old Scots pine chronosequence and adjacent grassland sites on podzolic soils. Significant differences were observed in the top organic soil horizons, while no changes were noted in the deeper mineral soil horizons. Simulations with the RothC-26.3 model revealed that pine forests could lose a significant amount of soil organic carbon through management operations. The lowest modelled stocks of soil organic carbon were not in the young sites (0-25 years old), but at 43 years since reforestation. Using measured data from our study site, simulations of grassland afforestation suggested that accumulation of organic carbon under forest is mainly in the organic horizons, while the deeper mineral soil horizons are likely to become depleted in soil organic carbon compared to grasslands. Our simulations suggest that afforestation of grasslands would increase overall soil carbon stocks but deplete the more stable carbon pools in the deeper mineral soils, which is not a desirable outcome in the context of climate change. The measurements provide comparative estimates of SOC in grassland and forestry sites at steady state; few studies provide these comparative measures. This study presents a new method for simulating soils that are accumulating carbon using the assumption of steady state with respect to the rate of accumulation. The approach has never been presented before and could have important implications for estimates of impacts of land use and climate change on the large SOC stocks held in highly organic soils. Subsequent simulations provide a new method for interpolating measurements that allow the losses due to management operations to be determined.

Effects of nitrogen addition on microbial residues and their contribution to soil organic carbon in China's forests from tropical to boreal zone.

Atmospheric nitrogen (N) deposition has a significant influence on soil organic carbon (SOC) accumulation in forest ecosystems. Microbial residues, as by-products of microbial anabolism, account for a significant fraction of soil C pools. However, how N deposition affects the accumulation of soil microbial residues in different forest biomes remains unclear. Here, we investigated the effects of six/seven-year N additions on microbial residues (amino sugar biomarkers) in eight forests from tropical to boreal zone in eastern China. Our results showed a minor change in the soil microbial residue concentrations but a significant change in the contribution of microbial residue-C to SOC after N addition. The contribution of fungal residue-C to SOC decreased under low N addition (50kgN ha-1 yr-1) in the tropical secondary forest (-19%), but increased under high N addition (100kgN ha-1 yr-1) in the temperate Korean pine mixed forest (+21%). The contribution of bacterial residue-C to SOC increased under the high N addition in the subtropical Castanopsis carlesii forest (+26%) and under the low N addition in the temperate birch forest (+38%), respectively. The responses of microbial residue-C in SOC to N addition depended on the changes in soil total N concentration and fungi to bacteria ratio under N addition and climate. Taken together, these findings provide the experimental evidence that N addition diversely regulates the formation and composition of microbial-derived C in SOC in forest ecosystems.

Depth distribution pattern of soil organic carbon in forest from Taowan basin of Funiu Mountain area.

Depth distribution pattern of soil organic carbon in forest from Taowan basin of Funiu Mountain area.

Concentration and mineralization of organic carbon in forest soils along a climatic gradient

Forty-four percent of the organic carbon (OC) in the world's forests is stored in soils. However, the distribution and stability of OC in forest soils along a climatic gradient remain largely unclear, hindering our understanding and the accurate prediction of biogeochemical cycles in forest ecosystems in a changing world. To address these uncertainties, we measured OC and nitrogen (N) concentrations and mineralization of OC in soils from broadleaved and coniferous forests along a wide-ranging climatic gradient in China and related these to experimental N addition and climatic conditions. An 85-day incubation was conducted under 25 °C and 60% of soil moisture at field capacity to determine the mineralization of soil OC. We hypothesized that the concentrations of OC and N would be higher but the mineralization of OC would be lower in soils from colder and drier forests and that the mineralization would be positively responsive to N addition. In support of these hypotheses, the concentrations of OC and N decreased, while the mineralization of OC measured under standard laboratory condition increased, with mean annual precipitation (MAP) and temperature (MAT). These metrics were not affected by forest type or the interaction between forest type and site. Nitrogen addition increased the cumulative mineralized OC (Cm, g kg−1) by 6–67%, and the effects varied with site and soil depth, but were similar between the broadleaved and coniferous forests. The Cm decreased with increasing soil OC concentration, C/N ratio and mineral N, while the rate constant of OC mineralization (k, day−1) showed opposite relationships with these metrics. The addition of N did not change the slopes of the relationships of Cm and k with the C/N ratio, MAP, and MAT; however, it strengthened the negative relationship of Cm with OC and mineral N concentrations. The results from this study suggested that the mineralization of OC was limited by N availability in the studied forested soils, and the response of OC mineralization to N addition was independent of climatic conditions.

Changes of Soil Organic Carbon in Forest and Arable Soil Under Different Altitude Levels

Changes of Soil Organic Carbon in Forest and Arable Soil Under Different Altitude Levels

Проблема учета поглощающей способности лесов России в Парижском соглашении

Проблема учета поглощающей способности лесов России в Парижском соглашении

Toward inventory-based estimates of soil organic carbon in forests of the United States.

Soil organic carbon (SOC) is the largest terrestrial carbon (C) sink on Earth; this pool plays a critical role in ecosystem processes and climate change. Given the cost and time required to measure SOC, and particularly changes in SOC, many signatory nations to the United Nations Framework Convention on Climate Change report estimates of SOC stocks and stock changes using default values from the Intergovernmental Panel on Climate Change or country-specific models. In the United States, SOC in forests is monitored by the national forest inventory (NFI) conducted by the Forest Inventory and Analysis (FIA) program within the U.S. Department of Agriculture, Forest Service. The FIA program has been consistently measuring soil attributes as part of the NFI since 2001 and has amassed an extensive inventory of SOC in forest land in the conterminous United States and southeast and southcentral coastal Alaska. That said, the FIA program has been using country-specific predictions of SOC based, in part, upon a model using SOC estimates from the State Soil Geographic (STATSGO) database compiled by the Natural Resources Conservation Service. Estimates obtained from the STATSGO database are averages over large map units and are not expected to provide accurate estimates for specific locations, e.g., NFI plots. To improve the accuracy of SOC estimates in U.S. forests, NFI SOC observations were used for the first time to predict SOC density to a depth of 100cm for all forested NFI plots. Incorporating soil-forming factors along with observations of SOC into a new estimation framework resulted in a 75% (48±0.78Mg/ha) increase in SOC densities nationally. This substantially increases the contribution of the SOC pool, from approximately 44% (17Pg) of the total forest ecosystem C stocks to 56% (28Pg), in the forest C budget of the United States.

秦岭南坡红桦林土壤有机碳密度影响因素

PDF HTML阅读 XML下载 导出引用 引用提醒 秦岭南坡红桦林土壤有机碳密度影响因素 DOI: 10.5846/stxb201406271326 作者: 作者单位: 西北农林科技大学林学院,西北农林科技大学林学院,西北农林科技大学林学院,西北农林科技大学林学院 作者简介: 通讯作者: 中图分类号: 基金项目: 林业公益性行业科研专项项目(201204502) Factors affecting soil organic carbon density in Betula albo-sinensis forests on the southern slope of the Qinling Mountains Author: Affiliation: College of Forestry,Northwest A&F University,Yangling,College of Forestry,Northwest A&F University,Yangling,College of Forestry,Northwest A&F University,Yangling,College of Forestry,Northwest A&F University,Yangling 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:以秦岭南坡红桦林为研究对象,利用标准地调查法获得林分、地形、土壤相关数据,分析红桦林土壤有机碳密度(SOCD)分异特征及其与林分因子和地形因子间的关系。结果表明:秦岭南坡红桦林土壤有机碳密度总体均值为(69.02±12.90)t/hm2,原始红桦林土壤有机碳密度均值为(76.21±10.83)t/hm2,次生红桦林为(65.24±12.32)t/hm2,原始红桦林土壤有机碳密度比次生红桦林高16.81%,t-检验结果显示两者存在显著差异;在不同林区间,红桦林土壤有机碳密度亦存在显著差异(P < 0.05)。从地形因子看,红桦林土壤有机碳密度在不同坡位和坡向间未表现出显著差异,而海拔和坡度对红桦林土壤有机碳密度有较为显著的影响。土壤有机碳密度与海拔、林龄、乔木生物量和草本生物量呈显著正相关,与坡度和林分密度呈显著负相关;主成分分析表明:特征值大于1的四个主成分对土壤有机碳密度的方差累积贡献率为85.62%,海拔、坡度、林分密度和郁闭度是影响秦岭南坡红桦林土壤有机碳密度的主要因子;通过逐步回归分析得到利用海拔、坡度、林龄、林分密度、乔木生物量和草本生物量估算红桦林土壤有机碳密度的模型:SOCD=0.015E-0.332G-0.026FD+0.304SA+0.105BA+21.673BH+36.358。 Abstract:Soil organic carbon, the main part of the terrestrial ecosystem carbon pool, is an essential component of the terrestrial carbon cycle, and one of the most important components of research on global change. Accurate estimation of soil organic carbon storage is important for determining the role that soil organic carbon plays in the terrestrial ecosystem carbon cycle, and thus in changes in the global environment. Forest soil organic carbon storage changes according to topography and forest conditions; therefore, research on forest organic carbon in a variety of such conditions is essential to determine the relationship between soil organic carbon storage, and factors related to topography and forest conditions. Betula albo-sinensis forest is one of the principal forest types in the Qinling Mountains. This study aimed to analyze the distribution patterns of soil organic carbon density (SOCD), and to reveal the relationship between soil organic carbon density and factors influencing Betula albo-sinensis forest on the southern slopes of the Qinling Mountains. We investigated topographical, stand, and soil factors of 122 plots, each of which was 20×30 m. Inventory data (i.e., elevation, gradient, slope position, slope aspect, canopy density, plant cover, biomass, mean height, and mean diameter at breast height) of Betula albo-sinensis individuals in each plot were measured and recorded. Soil samples were tested for SOCD, moisture density, and bulk density. Results indicated that the average SOCD was (69.02±12.90) t/hm2. In virgin forest, the average SOCD was (76.21±10.83) t/hm2, in secondary forest, (65.24±12.32) t/hm2. The difference in average SOCD between them was significant. The average SOCD decreased with soil depth increasing, and the average SOCD for soil layers A-C was (31.52±6.57), (27.18±6.49), and (10.32±2.65) t/hm2, respectively. The average SOCD (t/hm2) differed by forest region (Xunyangba=(58.80±10.29), Huoditang=(67.95±10.25), Huangbaiyuan=(69.63±12.78), and Guanyinshan=(75.82±12.30)). One-way ANOVA analysis showed that differences in average SOCD were significant for the four forest regions and soil layers, but not significant for slope positions. Differences in SOCD between shady and sunny slopes were insignificant, based on t-tests. Correlation analysis showed that SOCD was positively correlated with elevation, stand age, arbor biomass, and herb biomass, but negatively correlated with surface gradient and forest density. Principal component analysis showed that elevation and gradient were the first principal components affecting SOCD. Canopy density and forest density were the second principal components, stand age the third, and arbor biomass and herb biomass the fourth. These four principal components accounted for 85.62% of the variance of SOCD. Stepwise regression analysis showed that the effect of different factors on soil organic carbon density was unclear. However, stand age, elevation, gradient, arbor biomass, and herb biomass were the predominant factors affecting SOCD. 参考文献 相似文献 引证文献

火烧对森林土壤有机碳的影响研究进展

火烧对森林土壤有机碳的影响研究进展

Total, cold and hot water extractable organic carbon in soil profile: impact of land-use change

The content of labile, especially water extractable organic carbon (WEOC) is a sensible indicator of soil organic matter quality. The main objectives of this study were: i) to investigate the profile changes of cold and hot water extractable organic carbon in forest and arable soils; ii) to evaluate the correlation between these labile fractions of soil organic matter and total organic carbon content. The experiments were carried out on a Gleyic Albeluvisol (ABg) in the upper part of Dniester basin, Western Ukraine. The soil samples were taken from 50-cm depth soil profile with 5-cm step. Total organic carbon (TOC), cold water extractable organic carbon (CWEOC) and hot water extractable organic carbon (HWEOC) contents in soil were determined as well as pH (H 2 O) and electrical conductivity of soil:water suspensions. The results of this study showed that in 0–50 cm layer of arable soil TOC content decreased by 32%, CWEOC – by 23% and HWEOC – by 74% compared to forest soil that confirmed a high informative role of HWEOC fraction. The profile changes of WEOC percentage were analysed. They also show that HWEOC is much more informative indicator of soil organic matter quality than CWEOC. The most prominent changes of soil chemical properties, TOC, CWEOC and HWEOC contents in response to deforestation were observed in the top 5-cm soil layer. We suggested this thin soil layer to be defined as soil stress-sensitive zone.

Dynamics of aggregate-associated organic carbon following conversion of forest to cropland

The conversion of natural forest to cropland generally results in the loss of soil organic carbon (OC) and an increase in CO2 flux to the atmosphere. The dynamics of aggregate-associated OC after conversion to cropland are still not well understood. Such an understanding is essential for accurately estimating C flux between soil and the atmosphere. To learn more about OC dynamics after cultivation of natural forest land, we measured total soil and aggregate-associated OC in paired forest and cropland plots in Shaanxi Province, China. The cropland had been converted from adjacent forest 4, 50, and 100 yrs previously. As expected, the conversion to cropland resulted in significant declines in total soil OC concentrations and stocks. The largest decreases occurred during the early stages of cultivation. A century of cultivation decreased total soil OC stocks in the 0–20 cm depth by 0.77 kg m−2. Macroaggregate-associated OC stocks decreased, but microaggregate-associated OC stocks increased following the conversion of forest to cropland. Silt + clay-associated OC stocks were not affected. The reduction in macroaggregate-associated OC stocks was caused by declines in both the amount of soil in the macroaggregate fraction and by decreases in the concentration of macroaggregate-associated OC. The results of this study indicate the conversion of forest to cropland not only reduced total soil OC stocks, but also caused a percentage shift in the distribution of total soil OC among aggregate size classes and among soil depths. These shifts would delay the loss of OC, so the loss of OC in forest soil due to cultivation might thus be lower than expected.

Phosphorus and bacterial growth in drinking water.

The availability of organic carbon is considered the key factor to regulate microbial regrowth in drinking water network. However, boreal regions (northern Europe, Russia, and North America) contain a large amount of organic carbon in forests and peatlands. Therefore, natural waters (lakes, rivers, and groundwater) in the northern hemisphere generally have a high content of organic carbon. We found that microbial growth in drinking water in Finland is highly regulated not only by organic carbon but also by the availability of phosphorus. Microbial growth increased up to a phosphate concentration of 10 micrograms of PO4-P liter-1. Inorganic elements other than phosphorus did not affect microbial growth in drinking water. This observation offers novel possibilities to restrict microbial growth in water distribution systems by developing technologies to remove phosphorus efficiently from drinking water.