Carbon Reserves Research Articles

Proteogenic Dipeptides Are Characterized by Diel Fluctuations and Target of Rapamycin Complex-Signaling Dependency in the Model Plant Arabidopsis thaliana.

As autotrophic organisms, plants capture light energy to convert carbon dioxide into ATP, nicotinamide adenine dinucleotide phosphate (NADPH), and sugars, which are essential for the biosynthesis of building blocks, storage, and growth. At night, metabolism and growth can be sustained by mobilizing carbon (C) reserves. In response to changing environmental conditions, such as light-dark cycles, the small-molecule regulation of enzymatic activities is critical for reprogramming cellular metabolism. We have recently demonstrated that proteogenic dipeptides, protein degradation products, act as metabolic switches at the interface of proteostasis and central metabolism in both plants and yeast. Dipeptides accumulate in response to the environmental changes and act via direct binding and regulation of critical enzymatic activities, enabling C flux distribution. Here, we provide evidence pointing to the involvement of dipeptides in the metabolic rewiring characteristics for the day-night cycle in plants. Specifically, we measured the abundance of 13 amino acids and 179 dipeptides over short- (SD) and long-day (LD) diel cycles, each with different light intensities. Of the measured dipeptides, 38 and eight were characterized by day-night oscillation in SD and LD, respectively, reaching maximum accumulation at the end of the day and then gradually falling in the night. Not only the number of dipeptides, but also the amplitude of the oscillation was higher in SD compared with LD conditions. Notably, rhythmic dipeptides were enriched in the glucogenic amino acids that can be converted into glucose. Considering the known role of Target of Rapamycin (TOR) signaling in regulating both autophagy and metabolism, we subsequently investigated whether diurnal fluctuations of dipeptides levels are dependent on the TOR Complex (TORC). The Raptor1b mutant (raptor1b), known for the substantial reduction of TOR kinase activity, was characterized by the augmented accumulation of dipeptides, which is especially pronounced under LD conditions. We were particularly intrigued by the group of 16 dipeptides, which, based on their oscillation under SD conditions and accumulation in raptor1b, can be associated with limited C availability or photoperiod. By mining existing protein-metabolite interaction data, we delineated putative protein interactors for a representative dipeptide Pro-Gln. The obtained list included enzymes of C and amino acid metabolism, which are also linked to the TORC-mediated metabolic network. Based on the obtained results, we speculate that the diurnal accumulation of dipeptides contributes to its metabolic adaptation in response to changes in C availability. We hypothesize that dipeptides would act as alternative respiratory substrates and by directly modulating the activity of the focal enzymes.

Application of a Panel Data Quantile-Regression Model to the Dynamics of Carbon Sequestration in Pinus kesiya var. langbianensis Natural Forests

Even though studies on forest carbon storage are relatively mature, dynamic changes in carbon sequestration have been insufficiently researched. Therefore, we used panel data from 81 Pinus kesiya var. langbianensis forest sample plots measured on three occasions to build an ordinary regression model and a quantile-regression model to estimate carbon sequestration over time. In the models, the average carbon reserve of the natural forests was taken as the dependent variable and the average diameter at breast height (DBH), crown density, and altitude as independent variables. The effects of the DBH and crown density on the average carbon storage differed considerably among different age groups and with time, while the effect of altitude had a relatively insignificant influence. Compared with the ordinary model, the quantile-regression model was more accurate in residual and predictive analyses and removed large errors generated by the ordinary model in fitting for young-aged and over-mature forests. We are the first to introduce panel-data-based modeling to forestry research, and it appears to provide a new solution to better grasp change laws for forest carbon sequestration.

Comparing statistical and mechanistic models to identify the drivers of mortality within a rear-edge beech population

Since several studies have been reporting an increase in the decline of forests, a major issue in ecology is to better understand and predict tree mortality. The interactions between the different factors and the physiological processes giving rise tree mortality, as well as the inter-individual variability in mortality risk, still need to be better assessed. This study investigates mortality in a rear-edge population of European beech (Fagus sylvatica L.) using a combination of statistical and process-based modelling approaches. Based on a survey of 4323 adult beeches since 2002 within a natural reserve, we first used statistical models to quantify the effects of competition, tree growth, size, defoliation and fungi presence on mortality. Secondly, we used an ecophysiological process-based model (PBM) to separate out the different mechanisms giving rise to temporal and inter-individual variations in mortality by simulating depletion of carbon stocks, loss of hydraulic conductance and damage due to late frosts in response to climate. The combination of all these simulated processes was associated with the temporal variations in the population mortality rate. The individual probability of mortality decreased with increasing mean growth, and increased with increasing crown defoliation, earliness of budburst, fungi presence and increasing competition, in the statistical model. Moreover, the interaction between tree size and defoliation was significant, indicating a stronger increase in mortality associated to defoliation in smaller than larger trees. Finally, the PBM predicted a higher conductance loss together with a higher level of carbon reserves for trees with earlier budburst, while the ability to defoliate the crown was found to limit the impact of hydraulic stress at the expense of the accumulation of carbon reserves. We discuss the convergences and divergences obtained between statistical and process-based approaches and we highlight the importance of combining them to characterize the different processes underlying mortality, and the factors modulating individual vulnerability to mortality.

Organic matter of sod-podzolic soil after transition to a fallow state

Soil plays a crucial role in carbon sequestration in terrestrial ecosystems. It is known that the strengthening of carbon sequestration processes occurs with a decrease in the intensity of soil treatments. The study of changes in organic matter and physical properties of sod-podzolic soil 16 years after the transition from arable soils to a fallow state against the background of weak water erosion was carried out. A significant increase in the content and reserves of total carbon in fallow soil compared to arable soil was found, mainly due to carbon of the light fraction. On arable soil, the content of the light fraction in the lower part of the field was significantly higher than in the upper part, due to the washing away of light particles as a result of erosion, these differences were smoothed out on fallow soil. There are no significant changes in the density, density of the solid phase and total porosity in fallow soil at this stage of succession, compared with arable soil. In fallow soil, the content of macro-aggregates (including water-bearing ones) was noticeably higher, and the share of micro-aggregates was lower than in arable soil.

Моніторинг і збереження ґрунтів як компонент системи сталого управління агроекосистемами локального рівня

The article assesses the prospects of local and regional agroecosystems to provide modern measures to improve the quality of land and soils. The authors applied the analysis (induction and deduction) of guiding and normative documents and current publications of both Ukrainian and European on the organization of sustainable use of soils and the priority of their protection. It is important to remember, that the United Nations (U.N.) sustainable development goals (SDGs, indicator 15.3.1) have land degradation neutrality by 2030. A serious aspect of the article is the assessment of the possibilities of Ukrainian agriculture to implement a system of sustainable soil management at the local level in the near future. It is determined that drivers for soil management of agroecosystems, which determine the agenda for all land users and landowners are follows: (1) global processes and geopolitical significance of agriculture; (2) characteristics of soils as a natural object, in particular, their irreplaceability, non-renewability and performance of global biosphere functions; (3) national features, including the lack of real monitoring, gaps in legislation and non-compliance with existing regulations and acts and the land market. Therefore, there is a need for precise legislation to protect and preserve soils, as well as the implementation of agricultural technologies that will ensure a land degradation neutrality and soil sequestration of carbon. Given the uncertainty about the functioning of real soil monitoring at the state level, we consider it promising to organize soil monitoring as a local network. This means that the creation of a components of a specific soil management system should be provided by land users. The authors are convinced that experimental stations in the structure of NAAS should maintain / create their own database. Based on such a database it will be possible to effectively ensure sustainable soil management, namely: to assess soils current state at the moment, ecosystem services from soils, to predict the dynamics of soil indicators, to simulate different variants of their changes and so on. The costs of such a local GIS are offset by gains, including profits from business activities for many years to come. Due to the increased attention to soil organic carbon reserves (introduction of carbon taxes, restrictions on greenhouse gas emissions), it is urgent to assess and forecast the processes of carbon emission-sequestration and appropriate soil capabilities for a particular type of land use. Soil scientists are ready to develop a method of data collection and local GIS, taking into account the specifics of the type of agriculture.

Проблеми та можливості моделювання потенціалу секвестрації діоксиду карбону грунтами України

The article examines approaches to modelling carbon dioxide sequestration by soils at different scale levels and describes a number of problems encountered in this process. The main problems in the modelling of organic carbon reserves for the territory of Ukraine have been identified, among which: lack of high-resolution data (hard to access), including types of land use; need for harmonization of existing data; the need for predicative modelling of indicators (clay and organic carbon content) for areas where data are not available; significant amounts of machine time for actual modelling. The need for open access to archived data (technical reports) from large-scale soil surveys 1957-1990 is highlighted. Also, the need to access large-scale topographic data as in the form of scanned topographic maps M 1:10000 and vectorized isolines are substantiated. It is shown that calculations of areas based on rasters in the geographical coordinate system to ensure the same pixel size, regardless of the location within Ukraine, it is proposed to use the “Ukraine Albers conic equal area” projection based on the Datum Pulkovo 1942 for which the error in the lengths of the lines is only 0.1%. Within areas can be used as a proposed projection, as well as precise Gauss-Kruger projections (EPSG 28404-28407, 5565-5583). In this case, it is necessary to take into account the likelihood of finding individual areas in several of the listed zones. It is demonstrated that simulation allows to establish territories in which even the best practices of management do not provide neutralization of emission of organic carbon from soils. However, it is necessary to introduce a priority introduction of adaptive management of the soil resources of agro-landscapes that will contribute to carbon sequestration or minimization of its emission.

Mapping the irrecoverable carbon in Earth\u2019s ecosystems

Avoiding catastrophic climate change requires rapid decarbonization and improved ecosystem stewardship at a planetary scale. The carbon released through the burning of fossil fuels would take millennia to regenerate on Earth. Though the timeframe of carbon recovery for ecosystems such as peatlands, mangroves and old-growth forests is shorter (centuries), this timeframe still exceeds the time we have remaining to avoid the worst impacts of global warming. There are some natural places that we cannot afford to lose due to their irreplaceable carbon reserves. Here we map ‘irrecoverable carbon’ globally to identify ecosystem carbon that remains within human purview to manage and, if lost, could not be recovered by mid-century, by when we need to reach net-zero emissions to avoid the worst climate impacts. Since 2010, agriculture, logging and wildfire have caused emissions of at least 4.0 Gt of irrecoverable carbon. The world’s remaining 139.1 ± 443.6 Gt of irrecoverable carbon faces risks from land-use conversion and climate change. These risks can be reduced through proactive protection and adaptive management. Currently, 23.0% of irrecoverable carbon is within protected areas and 33.6% is managed by Indigenous peoples and local communities. Half of Earth’s irrecoverable carbon is concentrated on just 3.3% of its land, highlighting opportunities for targeted efforts to increase global climate security.

The Degradation of the Territories of Snow Polygons

The assessment of the degree of degradation of the soil and vegetation cover in the territory of storage of snow masses was carried out. It is established that in the soils of the polygons there is a decrease in the reserves of organic carbon, an increase in the power of the abiotic alluvial layer, a reduction in the power of the upper part of the soil profile, washouts and algae are formed. It is determined that the soil filtration coefficients are low. Stagnation of water near the surface and prolonged waterlogging against the background of low temperatures during the entire period of snowmelt were revealed. The soils of all snow polygons are characterized as highly degraded. They have lost their valuable functions for humans and need to be reclaimed.

Estimation of Tree Carbon Stocks in the Green Open Space of the Faculty of Forestry, Tanjungpura University

The presence of green open space containing vegetation in urban areas plays a vital role in absorbing and storing carbon in biomass. Tanjungpura University (Untan) Pontianak has a green open area in the New Building of the Faculty of Forestry. This study aimed to describe carbon reserves stored in biomass above ground level (vegetation) in green open areas around the New Building of Faculty of Forestry Untan Pontianak. Data were collected using an inventory survey by non-destructive sampling, which includes recording with fully enumerated data collection on the type and diameter of trees with a continuous line plot system. The data were then analyzed using allometric equations to obtain biomass values. The results found as many as 56 species of trees with a total of 558 individuals dominated by Litsea garciae and Hevea brasiliensis. The results showed the amount of carbon stored at the tree level of 59.06 tons/ha (76.18%), pole level of 13.94 tons/ha (17.99%), and sapling level of 4.52 tons/ha (5.83%), with an average carbon stock of 77.52 tons/ha. Thus, the green open area could store 148.53 tons of carbon in tree biomass. Although it is a small area, this peatland ecosystem could accumulate peat in organic soil and its vegetation and should be managed as peatland forests. Therefore, proper management is essential, and hydrology management is needed mainly due to its nature. Keywords: allometric equation, biomass, carbon stocks, green open space

Nitrogen nutrition addition mitigated drought stress by improving carbon exchange and reserves among two temperate trees

Climate change-driven increases in drought and atmospheric nitrogen (N) deposition frequency and severity across the world, and these changes have profound impacts on forest dynamics by affecting tree carbon balance. However, important knowledge gaps persist concerning the interactions between drought and N enrichment on carbon supply and reserve dynamics. We investigated gas exchange and carbohydrate reserve shifts and associated with leaf chemical composition across two temperate tree saplings coping with different levels of drought stress, N nutrition addition and their interactions. Our results showed that drought stress decreased net photosynthetic rate (A) and stomatal conductance (gs), while A and gs were increased by N addition, combined with increased gs under the interactive effects of drought and N addition, indicating that N nutrient availability had suppressing effect on drought stress and improved the drought-induced negative conditions by altering carbon exchange traits. In addition, we found that N addition reduced the concentrations of nonstructural carbohydrate (NSC) and its components in relation to foliar carbon and nitrogen changes and the fast growth of saplings. Under the interaction of drought and N nutrition addition, no variation in carbohydrate concentrations demonstrate that carbon reserves play a critical role in regulating carbon exchange and growth. Our observations provide evidence of N nutrient availability mitigated drought stress by improving carbon exchange and reserves, which is expected to contribute to the predictions of future vegetation dynamics.

Vulnerability of European ecosystems to two compound dry and hot summers in 2018 and 2019

Abstract. In 2018 and 2019, central Europe was affected by two consecutive extreme dry and hot summers (DH18 and DH19). The DH18 event had severe impacts on ecosystems and likely affected vegetation activity in the subsequent year, for example through depletion of carbon reserves or damage from drought. Such legacies from drought and heat stress can further increase vegetation susceptibility to additional hazards. Temporally compound extremes such as DH18 and DH19 can, therefore, result in an amplification of impacts due to preconditioning effects of past disturbance legacies. Here, we evaluate how these two consecutive extreme summers impacted ecosystems in central Europe and how the vegetation responses to the first compound event (DH18) modulated the impacts of the second (DH19). To quantify changes in vegetation vulnerability to each compound event, we first train a set of statistical models for the period 2001–2017, which are then used to predict the impacts of DH18 and DH19 on enhanced vegetation index (EVI) anomalies from MODIS. These estimates correspond to expected EVI anomalies in DH18 and DH19 based on past sensitivity to climate. Large departures from the predicted values can indicate changes in vulnerability to dry and hot conditions and be used to identify modulating effects by vegetation activity and composition or other environmental factors on observed impacts. We find two regions in which the impacts of the two compound dry and hot (DH) events were significantly stronger than those expected based on previous climate–vegetation relationships. One region, largely dominated by grasslands and crops, showed much stronger impacts than expected in both DH events due to an amplification of their sensitivity to heat and drought, possibly linked to changing background CO2 and temperature conditions. A second region, dominated by forests and grasslands, showed browning from DH18 to DH19, even though dry and hot conditions were partly alleviated in 2019. This browning trajectory was mainly explained by the preconditioning role of DH18 on the impacts of DH19 due to interannual legacy effects and possibly by increased susceptibility to biotic disturbances, which are also promoted by warm conditions. Dry and hot summers are expected to become more frequent in the coming decades, posing a major threat to the stability of European forests. We show that state-of-the-art process-based models could not represent the decline in response to DH19 because they missed the interannual legacy effects from DH18 impacts. These gaps may result in an overestimation of the resilience and stability of temperate ecosystems in future model projections.

Transformation of organic matter of Cisbaikal forest-steppe abandoned lands

For the first time, quantitative estimates of the carbon pools (plant residues, microbial biomass, and humus) that provide organic matter reserves in gray forest soils depending on the abandoned age are presented for the region. The pool of C-plant residues, which comprises only carbon reserves in the aboveground part of the herbaceous layer and litter fall, varied from 0.3 to 5.9 t·ha-1. Young fallows were observed to demonstrate the highest values. The increase in the age of the abandoned land was found to be accompanied by the decrease in carbon reserves in the plant pool. The microbial carbon pool (Cmic) varied from 2.1 t·ha-1 on young fallows to 5.2 t·ha-1 on long-term abandoned lands approaching the indicators identified for natural cenoses (6-8 t·ha-1). The largest value (25-72 t·ha-1) characterized the carbon pool in the humus, but no regular changes depending on the abandoned age were identified. The type of humus in the soils after abandonment, as well as in undisturbed soils, was fulvate-humate, and the degree of humification varied from “medium” to “very high”. This indicates the preservation of zonal features of humus formation of gray forest soils in the region during their postagrogenic development.

Slope aspect and altitude effect on selected soil organic matter characteristics in Beskid Mountains forest soils

Abstract In the era of dynamic climate change, it is important to have knowledge on the interactions between climatic factors and processes occurring in the soil environment. The present study aimed to determine how slope aspect and altitude above sea level influence carbon and nitrogen accumulation and dehydrogenases activity of forest soils. The study was conducted in the Beskid Żywiecki in the south-facing part of Poland. Soils of the same texture, with similar vegetation species composition, in different altitude variants (600, 800, 1000 and 1200 m above sea level) and different north-facing and south-facing slope aspect were selected for the study. For each height and slope aspect variant, samples were collected from the surface horizons of soils for further analyses. The basic chemical properties and dehydrogenases activity of the soil samples were determined. Carbon and nitrogen stocks in the surface horizons of the soils were calculated. The analyses confirmed the influence of location conditions on the carbon and nitrogen stocks in mountain forest soils. The stock of carbon and nitrogen increased with the height up to 1000 m a.s.l. In the soils at the highest altitude, the reserve of carbon and nitrogen decreased regardless of the slope aspect variant. There were no statistically significant differences in carbon and nitrogen stocks between slope aspect variant. The highest dehydrogenases activity was associated with the organic horizons of the soils at the lowest altitude in height gradient. In our study, higher dehydrogenases activity was observed in the north-facing slope soils, and this finding can be explained by more stable thermal conditions.

Large scale mapping of soil organic carbon concentration with 3D machine learning and satellite observations

Canada has extensive forests and peatlands that play key roles in global carbon cycle. Canadian soils and peatlands are assumed to store approximately 20% of the world’s soil carbon stock. However, the spatial and vertical distributions of the soil organic carbon (SOC) concentration in Canada have not been systematically investigated. SOC concentration, expressed in g C kg−1 soil, affects the chemical and physical properties of the soil, such as water infiltration ability, moisture holding capacity, nutrient availability, and the biological activity of microorganisms. In this study, we tested a three dimensional (3D) machine learning approach and 40 spatial predictors derived from 20 years of optical and microwave satellite observations to estimate the spatial and vertical distributions of SOC concentration in Canada in six depth intervals up to 1 m. A quantile regression forest method was used to build an uncertainty map showing 80% of prediction intervals. Results showed that a random forest model associated with 25 covariates was successful in capturing 83% of spatial and vertical SOC variation over the country. Soil depth was the most important covariate to predict SOC concentration, followed by surface temperature and elevation. The SOC concentration in forested areas was highest in the top layers (0–5 cm), but soils located in peatlands showed higher C concentration in all soil depths. Among the terrestrial ecozones of Canada, Pacific Maritime and the Hudson Plain mostly covered by forest trees and peatlands, respectively, show highest SOC concentration, while the lowest concentration are observed in the Prairies and Mixed Wood Plain ecosystems that are the agricultural areas of the country. This study provides a deeper understanding of the major factors controlling SOC concentration in Canada and shows potential areas with high carbon reserves, which are crucial in view of the ongoing climate change. In addition, the presented methodological framework has great potential to be used in future soil carbon storage inventories using satellite observations. Mapping SOC concentration and associated uncertainties in Canada are fundamental to detect trends of gains or losses in SOC linked to recent and future national or global policy decisions related to soil quality and carbon sequestration.

Response of Merlot Grapevine to Drought Is Associated to Adjustments of Growth and Nonstructural Carbohydrates Allocation in above and Underground Organs

Studying changes in partitioning of dry matter and nonstructural carbohydrates (NSC) content in both aboveground and underground perennial tissues in drought-affected grapevines could provide insights into plant response and carbon allocation strategies during stress periods. The analysis of soluble NSC and starch content in leaf petioles, due to their role in hydraulic segmentation, should also be considered. In the present research, these aspects have been investigated in Merlot grapevines grown in pots and subjected to progressive and increasing soil dehydration, and in well-irrigated vines. Drought conditions caused drastic reduction of shoot elongation and total plant leaf area development in favor of a greater biomass allocation and partitioning towards roots, where most of the NSC reserves were also conserved. Dry matter content of the perennial organs increased in stressed vines due to growth reduction, allocation of carbon reserves and possible anatomical modifications. Vines subjected to drought showed a higher NSC content in petioles, supporting the hypothesis that they are involved as compatible solutes in osmotic adjustments.

Potassium and Phosphorus Fertilizer Impacts on Alfalfa Taproot Carbon and Nitrogen Reserve Accumulation and Use During Fall Acclimation and Initial Growth in Spring.

Phosphorus (P) and potassium (K) impact alfalfa (Medicago sativa L.) performance, but how these nutrients alter taproot physiology during fall acclimation and subsequent growth in spring is unclear. Our objectives were to: (1) determine seasonal patterns for taproot P and K concentrations during fall acclimation and during initial shoot growth in spring; (2) determine how P and K nutrition impacts accumulation of taproot C and N reserves during fall and their subsequent use when shoot growth resumes in spring; and (3) assess how addition of P and K fertilizer impacts survival and shoot growth in spring. Two P (0 and 75 kg ha−1) and two K (0 and 400 kg ha−1) treatments were applied and taproots were sampled between September and December, and again from March to May over 2 years. Concentrations of taproot sugar, starch, buffer-soluble protein, amino-N, and RNA pools were determined. While P and K fertilizer application increased taproot P and K concentrations two- to three-fold, concentrations of P and K in taproots over time did not change markedly during cold acclimation in fall, however, taproot P declined in spring as plant growth resumed. Compared to the 0K-0P treatment, taproots of plants fertilized with 400K-75P had higher starch, protein, amino-N, and RNA, but reduced sugar concentrations in fall. Concentrations of all these pools, except starch, declined during the initial 2 weeks of sampling beginning in late March as shoot growth resumed in spring. Herbage yield in May was highest for the 400K-75P treatment and least for the 0K-0P treatment, differences that were associated with variation in mass shoot−1 and not shoots m−2. High yield of the 400K-75P plants in May was consistently associated with greater concentrations and use of amino-N, soluble protein, and RNA pools in taproots, and not with accumulation and use of starch and sugar pools. Understanding factors leading to the accumulation of taproot N reserves and RNA during cold acclimation in fall and their use during the initial growth in spring should enhance efforts to improve alfalfa growth and herbage yield in spring.

Storage of carbon reserves in spruce trees is prioritized over growth in the face of carbon limitation

Climate change is expected to pose a global threat to forest health by intensifying extreme events like drought and insect attacks. Carbon allocation is a fundamental process that determines the adaptive responses of long-lived late-maturing organisms like trees to such stresses. However, our mechanistic understanding of how trees coordinate and set allocation priorities among different sinks (e.g., growth and storage) under severe source limitation remains limited. Using flux measurements, isotopic tracing, targeted metabolomics, and transcriptomics, we investigated how limitation of source supply influences sink activity, particularly growth and carbon storage, and their relative regulation in Norway spruce (Picea abies) clones. During photosynthetic deprivation, absolute rates of respiration, growth, and allocation to storage all decline. When trees approach neutral carbon balance, i.e., daytime net carbon gain equals nighttime carbon loss, genes encoding major enzymes of metabolic pathways remain relatively unaffected. However, under negative carbon balance, photosynthesis and growth are down-regulated while sucrose and starch biosynthesis pathways are up-regulated, indicating that trees prioritize carbon allocation to storage over growth. Moreover, trees under negative carbon balance actively increase the turnover rate of starch, lipids, and amino acids, most likely to support respiration and mitigate stress. Our study provides molecular evidence that trees faced with severe photosynthetic limitation strategically regulate storage allocation and consumption at the expense of growth. Understanding such allocation strategies is crucial for predicting how trees may respond to extreme events involving steep declines in photosynthesis, like severe drought, or defoliation by heat waves, late frost, or insect attack.

ECONOMIC ANALYSIS OF THE VALUE OF SOILS IN THE NORTH OF EUROPEAN RUSSIA IN DIFFERENT LAND USE SCENARIOS

The article reports the results of a comprehensive RFBR project which combined research in the fields of soil science, forestry, botany, ecology, microbiology, and economics. The question of monetization of ecosystem services and the challenges that occur when interpreting the results based on the integration of natural sciences and economic approaches in the study of this problem are investigated. This discussion highlights the need for a better statistical tool to shift the focus in measuring economic phenomena to sustainable development. We propose a system of mappings based on model (operational) relationships between functional and structural features of the soil and external data, each of which is characterized by a certain set of interacting processes. The theoretical and empirical background for studying changes in the land-use regime and the carbon balance in ecosystems is explored. Changes in the morphological, basic agrochemical and microbiological properties of soils, as well as the reserves of organic carbon and microbial carbon in the top-meter layer of soil in various land-use scenarios are shown. The total carbon budget was estimated for sites with different land uses on genetically similar soils in the middle-taiga subzone of European Russia. Indicators of the state of the soil system, which can be used for the economic assessment of landuse change are proposed.

Large seasonal fluctuations in whole-tree carbohydrate reserves: is storage more dynamic in boreal ecosystems?

Carbon reserves are a critical source of energy and substrates that allow trees to cope with periods of minimal carbon gain and/or high carbon demands, conditions which are prevalent in high-latitude forests. However, we have a poor understanding of carbon reserve dynamics at the whole-tree level in mature boreal trees. We therefore sought to quantify the seasonal changes in whole-tree and organ-level carbon reserve pools in mature boreal Betula papyrifera. Non-structural carbohydrate (NSC; soluble sugars and starch) tissue concentrations were measured at key phenological stages throughout a calendar year in the roots, stem (inner bark and xylem), branches and leaves, and scaled up to estimate changes in organ and whole-tree NSC pool sizes. Fine root and stem growth were also measured to compare the timing of growth processes with changes in NSC pools. The whole-tree NSC pool increased from its spring minimum to its maximum at bud set, producing an average seasonal fluctuation of 0.96 kg per tree. This fluctuation represents a 72 % change in the whole-tree NSC pool, which greatly exceeds the relative change reported for more temperate conspecifics. At the organ level, branches accounted for roughly 48-60 % of the whole-tree NSC pool throughout the year, and their seasonal fluctuation was four to eight times greater than that observed in the stemwood, coarse roots and inner bark. Branches in boreal B. papyrifera were the largest and most dynamic storage pool, suggesting that storage changes at the branch level largely drive whole-tree storage dynamics in these trees. The greater whole-tree seasonal NSC fluctuation in boreal vs. temperate B. papyrifera may result from (1) higher soluble sugar concentration requirements in branches for frost protection, and/or (2) a larger reliance on reserves to fuel new leaf and shoot growth in the spring.

FLEXIBLE SOIL MICROBIAL CARBON METABOLISM ACROSS AN ASIAN ELEVATION GRADIENT

ABSTRACTThe function and change of global soil carbon (C) reserves in natural ecosystems are key regulators of future carbon-climate coupling. Microbes play a critical role in soil carbon cycling and yet there is poor understanding of their roles and C metabolism flexibility in many ecosystems. We wanted to determine whether vegetation type and climate zone influence soil microbial community composition (fungi and bacteria) and carbon resource preference. We used a biomarker (phospholipid fatty acids, PLFAs), natural abundance 13C and 14C probing approach to measure soil microbial composition and C resource use, along a 1900–4167-m elevation gradient on Mount Gongga (7556 m asl), China. Mount Gongga has a vertical mean annual temperature gradient of 1.2–10.1°C and a diversity of typical vegetation zones in the Tibetan Plateau. Soils were sampled at 10 locations along the gradient capturing distinct vegetation types and climate zones from lowland subtropical-forest to alpine-meadow. PLFA results showed that microbial communities were composed of 2.1–51.7% bacteria and 2.0–23.2% fungi across the elevation gradient. Microbial biomass was higher and the ratio of soil fungi to bacteria (F/B) was lower in forest soils compared to meadow soils. δ13C varied between −33‰ to −17‰ with C3 plant carbon sources dominant across the gradient. Soil organic carbon (SOC) turnover did not vary among three soils we measured from three forest types (i.e., evergreen broadleaved subtropical, mixed temperate, coniferous alpine) and dissolved organic carbon (DOC) turnover decreased with soil elevation. Forest soil microbial PLFA 14C and δ13C measurements showed that forest type and climate were related to different microbial C use. The 14C values of microbial PLFAs i15, a15, 16:1, br17 decreased with elevation while those of C16:0, cyC17, and cyC19 did not show much difference among three forest ecosystems. Bacteria and bacillus represented by C16:1 and brC17 showed considerable microbial C metabolism flexibility and tended to use ancient carbon at higher altitudes. Anaerobes represented by cyC17 and cyC19 showed stronger C metabolism selectivity. Our findings reveal specific C source differences between and within soil microbial groups along elevation gradients.