Проблема учета поглощающей способности лесов России в Парижском соглашении

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

Decay rates of Quercus sp., Carya sp., Fagusgrandifolia, and Acer sp. coarse woody debris in an old-growth southern Indiana forest were 0.018, 0.035, 0.019, and 0.045 per year, respectively, based on changes in density over a span of 25+ years. Their respective biomass values were 15, 2.3, 0.2, and 0.4 t•ha−1. The greatest differences in decay rates of cellulose were between maple (high) and oak (low), and of lignin were between beech (high) and oak (low). Carbon to nitrogen ratios approached 100 and nitrogen to phosphorus ratios approached 20 in the older age-classes. On average, oak, hickory, beech, and maple logs contained 1.66, 1.10, 0.14, and 0.19 kg nitrogen and 0.056, 0.070, 0.005, and 0.016 kg phosphorus, respectively. Meentemeyer's model based on actual evapotranspiration predicted a decay rate of 0.80 per year, which is 27 times larger than the decay rates calculated on changes in density. Fragmentation loss rates for these four genera were estimated to be 0.288, 0.802, 1.171, and 0.338 per year, respectively. Decay rates based on diameter of coarse woody debris ranged from 0.0027 to 0.0337 per year. All these factors are important in understanding the process of decay of coarse woody debris in this forest. The roles of fragmentation in the decay of coarse woody debris and of fungitoxic extractives need more study.

Background. Organic carbon, which is part of humic substances, is the basis for the fertility of arable soils. The intensity of agriculture has led to an increase in the use of mineral fertilizers, which have a significant impact on soil formation processes. This leads to a disruption of the natural dynamic balance of organic carbon reserves, the process of mineralization of organic matter intensifies, which leads to an increase in carbon dioxide emissions. The accepted concept of “4 ppm” calls on the world society to develop a farming system aimed at increasing the reserves of organic carbon in arable soils. Based on this, studying the influence of various elements of crop cultivation technology on the supply and fixation of organic carbon in arable soils can be considered one of the tasks of modern agricultural science. The purpose of the work is to study the effect of mineral fertilizers on the supply of plant residues and reserves of organic carbon in grain-fallow crop rotation in the conditions of the forest-steppe zone of the Trans-Urals. The novelty of the work lies in the fact that for the first time long-term stationary studies have been carried out on the effect of mineral fertilizers on the supply and reserves of organic carbon in arable soils. In the future, it will be possible to theoretically substantiate the required doses of mineral fertilizers to obtain a positive balance of organic carbon in arable soils of Western Siberia. Materials and methods. The study was carried out in grain-fallow crop rotation (full fallow, spring wheat, oats) from 1995 to 2023 on leached, thin, heavy loamy chernozem. Every year, calculated doses of mineral fertilizers were applied to spring wheat and oats for a planned yield of 3.0; 4.0; 5.0 and 6.0 t/ha of grain, taking into account the actual nutrient content in the soil. Every year, the mass of straw, stubble and root residues was determined for all crop rotation options. In which the content of organic carbon was determined annually and the mass of carbon entering the soil was determined. Before the foundation of experience in 1995, as well as in 2005; 2015 and 2023 soil samples were taken from a depth of 0-10; 10-20; 20-30; 30-40; 40-60; 60-80; 80-100 cm. In which the content of organic carbon was subsequently determined. The reserves of organic carbon in a meter layer of soil were determined using the recalculation method taking into account the equilibrium density. Statistical data processing was carried out using Microsoft Excel. Results. In the option without the use of mineral fertilizers, 117.3 t/ha of plant residues entered the soil during 28 studies. Refusal to use fertilizers led to a negative balance of organic carbon in the soil, where the decrease in reserves was 6.7% relative to the initial values. The application of mineral fertilizers for a planned yield of 3.0 and 4.0 t/ha of grain led to an increase in the flow of by-products into the soil by 25-48% relative to the natural nutrition level. This ensured a positive carbon balance, where the increase in reserves in the meter layer of soil was 4.2-5.1% relative to the initial values. The application of NP to a planned yield of 5.0 and 6.0 t/ha of grain increased the input of plant residues during the study period by 69-75% relative to the control. Despite this, there was a decrease in organic carbon reserves in the meter layer of soil by 4.7-6.4% relative to the initial value. Conclusion. Refusal to use mineral fertilizers when cultivating grain crops leads to a negative balance of organic carbon, where annual carbon losses reach 0.44-0.78 t/ha. Stable application of fertilizers to obtain 3.0 and 4.0 t/ha of grain ensures a positive carbon balance in the soil, the annual increase in reserves ranges from 0.23 to 0.58 t/ha. High doses of fertilizers to obtain a yield of 5.0 to 6.0 t/ha lead to a negative carbon balance in the soil; annual losses range from 0.30 to 0.55 t/ha.

Purpose. The purpose of this paper was to highlight the results of the study of the influence of the balance of organic carbon in soil and fertilizer systems on the formation of sustainable competitiveness of Ukrainian agricultural enterprises. Methodology / approach. To achieve the purpose, we used such methods: balance (to assess carbon balance in the soil); correlation analysis (to identify and assess the close relationship between the balance of organic carbon in the soil and the Sustainable Competitiveness Index – SCI); econometric modeling (to develop a mathematical model of the dependence of the balance of organic carbon in the soil from the yield of by-products (straw) and the volume of organic fertilizers applied in agricultural enterprises); economic-statistical and monographic (for the assessment and analysis of the influence of the balance of organic carbon in the soil and fertilizer systems on the formation of competitiveness of enterprises); abstract-and-logical (for theoretical generalization and analysis of the research results). The economic database of the 5597 agricultural enterprises located in Ukraine was used as the empirical basis. Results. It was found that one third (33.0 %) of the studied agricultural enterprises of Ukraine had a deficit balance of humus (on average -0.273 t/ha), the rest (67.0 %) had a positive balance of humus, in particular 15.9 % of business entities provided a balance of humus more than 1 t/ha (an average of 1.608 t/ha). This group of enterprises reached an average level of sustainable competitiveness (SCI = 1.296) and was a good example of the formation of competitiveness on the basis of rational land use. The influence of the humus balance on the level of sustainable competitiveness of agricultural enterprises in the markets of three main crops – winter wheat, corn for grain and sunflower – was assessed, which allowed us to identify the industry-specific features of its formation. Originality / scientific novelty. As a result of the study it was identified and quantified, for the first time, the impact of the balance of organic carbon in the soil on the formation of sustainable competitiveness of agricultural enterprises. For the first time, a two-factor linear mathematical model of the dependence of the balance of humus in the soil from the yield of by-products (straw) and the volume of organic fertilizers applied in Ukrainian agricultural enterprises was developed. The provision on the features of the formation of sustainable competitiveness of agricultural enterprises under various fertilizer systems was further developed. Practical value / implications. The main results of the study can be used for (i) rapid assessment, regulation and prediction of the balance of organic carbon in the soil; (ii) identification of reserves for increasing sustainable competitiveness of agricultural enterprises; (ii) improving soil protection policy for regulating the reproduction of organic carbon in the soil.

Soil erosion, organic carbon and nitrogen dynamics in planted forests: A case study in a hilly catchment of Hunan Province, China

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.

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.

ABSTRACTAnthropogenic nitrogen (N) deposition significantly alters soil aggregate (SA) stability and soil organic carbon (SOC) dynamics in grassland ecosystems, though the effects of varying N deposition levels remain inadequately understood. Here we evaluate the effect of varying N addition levels on SA and organic carbon stability. A 6‐year N addition experiment was conducted in a desert steppe, comprising CK (0 g·m−2·yr.−1), low N (5 and 10 g·m−2·yr.−1), medium N (20 g·m−2·yr.−1), and high N (40 g·m−2·yr.−1) treatments. This research examined SA stability, GRSP, SOC dynamics, and carbon flow pathways using Fourier transform infrared and 13C stable isotope analysis. Medium N addition enhanced macro‐SA content (> 0.25 mm) by 20.5% and improved SA stability through increased SOC accumulation, while high N addition decreased macro‐SA content by 7.47%. SOC concentrations in micro‐SA (0.25–0.053 mm) and silt + clay (SC) (< 0.053 mm) increased substantially under low and medium N inputs. Polysaccharide‐C levels were elevated in macro‐SA, whereas phenolics‐C and aliphatic‐C predominated in micro‐SA. Low N addition increased aliphatic‐C in SA, while medium and high N levels reduced it. N addition elevated phenolics‐C and aromatic‐C, particularly in macro‐SA. Both easy extractable GRSP (EE‐GRSP) (r = 0.71*) and T‐GRSP (r = 0.59*) correlated positively with SOC, emphasizing GRSP's importance in SOC accumulation. N addition enhanced carbon flow among SA through microbial decomposition and anabolic processes, with plant‐derived carbon preferentially accumulating in macro‐SA and SC. Medium N input optimally promotes SA stability and SOC in desert steppes, providing important insights for understanding N deposition's role in climate change mitigation.

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

Глубина прогорания торфа и потери углерода при лесном подземном пожаре

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

Soil organic carbon (SOC) represents a significant fraction of the global carbon pool and is vital for understanding the ecosystem functions that occur in soils. Forest types and management can have a significant impact on soil organic matter and, as a result, soil organic carbon. However, comparative studies of SOC with respect to forest management have been carried out to a limited extent. Thus, the study was carried out in the Shivapuri-Nagarjun forest and the pine forest of Gokarneshwor with the aim of comparing the SOC of the Shivapuri forest of Shivapuri Nagarjun National Park and the pine forest of Gokarneshwor. Soil samples were collected by the stratified random sampling method. The composite samples from the depths of 0–10 cm and 10–15 cm were taken, mixed properly, air dried, and tested in the laboratory. Soil organic carbon was measured using the modified Walkley and Black methods. The soil organic carbon of the Shivapuri-Nagarjun forest was found to be 91.11 tons/ha, and the pine forest was found to be 34.77 tons/ha on average. Further analysis interlinking plant residue and microbial activities and their implications for soil organic carbon could be beneficial in forest management decisions

Litter is one of the most important factors controlling the accumulation, stabilization, and turnover of soil organic carbon (SOC) in forests. There is a knowledge gap of the impacts of aboveground and belowground litter inputs on the balance of new and old SOC under different forests in subtropical region. We examined the effects of aboveground and belowground litter inputs on SOC turnover using isotopic tracing technique, based on a 3-year C3 plants/C4 soil replacement experiment in natural forest (NF), Masson pine (Pinus massoniana) plantation (PM) and Chinese fir (Cunninghamia lanceolata) plantation (CL). Our results showed that forest types, litter treatments, and sampling time significantly affected SOC contents, δ13C, new and old SOC contents. Moreover, there were significant interactions between forest types and litter treatments. Litter input increased SOC content and net SOC increment, with higher sensitivity of NF than CL. Litter inputs decreased soil δ13C, with lower values in NF and PM compared to CL. For PM, the new SOC content in belowground litter treatment was significantly higher than that in aboveground litter treatment. The contents of old SOC were lower in belowground litter treatment than aboveground litter treatment in the NF and CL. Above- and below-ground biomass were positively correlated with SOC content and net increment. Belowground litter biomass were positively correlated with soil C/N ratio and new SOC content. Our results implied that belowground litter input had stronger effects on SOC turnover compared to aboveground litter input, with the effects varying among different forests. Our results provided new information on SOC accumulation and on sustainable management of the typical forests in subtropical region.

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