Amount Of Organic Carbon Research Articles

Ecological Role of <i>Onthophagus taurus</i> (Schreber) in Soil Nutrient Mobilization

Dung beetles play a major role in the pasture ecosystem. The manure recycling activity of dung beetles is linked to their tunneling behavior. The present study was designed to analyze the tunnel pattern and nutrient mobilization by dung beetles, Onthophagus taurus (Schereber, 1759) in different soil types. A simple type of tunnel pattern was observed in all the four types of soil after 30th day of their introduction (10 pairs of male and female) into the experimental setup. However, the maximum number of tunnels was observed in the sandy and sandy clay loam (no. of openings - 15), followed by loamy soil (no. of openings -13). The physical (texture, water holding capacity, porosity, moisture content) and chemical parameters (pH and nutrients) of all the four types of soils were evaluated. Soil texture analysis revealed the texture to be of sandy (yellow soil), sandy clay loam (red and black soil), and loamy sand (brown soil) types. Water holding capacity and the soil porosity were recorded highest in the sandy soil, whereas moisture content was found maximum in the sandy clay loam. Soil nutrient analysis illustrated a significant increase in the amount of nitrogen (N), phosphorus (P), calcium (Ca), sulfur (S), sodium (Na), potassium (K), organic carbon and organic matter. Thus, the present study confirms that tunneling activity of O. taurus enhances the soil nutrients by carrying out dung decomposition.

Effect of using repeated and siderate crops on soil fertility, yield of cotton varieties, and technological quality indicators of cotton fiber in short rotation cropping systems

In the 1:1 (cotton:grain) system of short-rotation, soybean, bean, mung bean crops were harvested as a repeat crop after winter wheat. Their stem crop and mixed siderate crops (perco, oats, green peas) were planted in the second half of August, and the blue mass crop grown in October-November was harvested for livestock. The lower 15-20 cm part of the stem was plowed under the plow as a blue manure, at the end of one rotation, the amount of organic carbon in the soil increased by 0.041-0.073%, and the total nitrogen content by 0.012-0.016% compared to the initial values. The highest rate of dry mass accumulation of cotton was observed when using short-row rotation 1:1, winter wheat + mixed siderate crops (perco, oat, green pea):cotton system. The dry mass of the leaves of the Navroz variety of cotton was 22.6 g, the dry mass of the stem was 33.4 g, the dry mass of the bolls was 18.5 g, and the dry mass of the cotton was 48.0 g. The total dry mass of 1 plant was equal to 122.5 g. In the 1:1 (cotton:grain) system of short-rotation, when cotton was grown as a repeat crop after legume-cereal (soybean, mung bean) and mixed siderate (perco, oat, green pea) crops, it provided a higher and better quality cotton yield. Cotton yield was 3.2-5.8 tons/ha, fiber output was 1.0-1.5 percent, and 1000 seed mass was 9.0-11.0 g/ha. Besides, the length of the fiber was found to be higher by 1.4-2.0 mm.

Soil Fertility Status of Major Tobacco Growing Lands of Bangladesh

Tobacco cultivation is associated with the destruction of soil quality, productivity, and environmental pollution. An experiment was conducted to know the soil fertility status of tobacco and non-tobacco growing soils of major tobacco growing areas (Manikganj, Kushtia, Lalmonirhat, Nilphamari, Chattogram, Rangamati, Bandarban and Khagrachari) of Bangladesh. Soil samples were examined to check the level of various nutrient components of soil like Organic Carbon (OC), Nitrogen (N), Phosphorus (P), Potassium (K), Zinc (Zn) in the Laboratory of Soil Science at Bangladesh Institute of Nuclear Agriculture. Wet oxidation, Kjeldhal, Olsen, flame photometer and atomic absorption spectrophotometer methods were followed to determine the OC, total N, P, K and Zn respectively of the soil samples. Overall, the results showed a decrease in all the nutrients in the tobacco growing lands compared to non-tobacco growing lands. The amount of OC (p value 0.0271), total N (p value 0.0162) and exchangeable K (p value 0.0006) were significantly lower in the tobacco lands. The organic carbon content of both tobacco and non-tobacco land showed below standard limit (2%). The total nitrogen content of the soil samples for both tobacco and non-tobacco showed below 0.5% except the non-tobacco growing lands of Chattogram and Khagrachari. The available P and Zn content in tobacco lands also showed a decrease in compared to non-tobacco lands but statistically there were no significant differences between them. The available P and Zn content in all the soil were below 50 ppm (except Khagrachari in non-tobacco lands) which was very low. The K content was also low in the tobacco growing lands and low to medium in the non-tobacco growing lands. This result reveals the poor soil condition due to tobacco cultivation in the major tobacco growing areas of Bangladesh. So, effective measures should be taken immediately to retain the soil health.

Study of the Interaction of Dissolved Organic Carbon, Available Nutrients, and Clay Content Driving Soil Carbon Storage in the Rice Rotation Cropping System in Northern Thailand

The appropriate management of crop residues in a rice rotation cropping system (RRCS) can promote carbon storage and contribute to soil health. The objective of this study was to determine and analyze the amount of organic carbon in the soil, the amount of labile carbon in a dissolved state in the soil, and the physicochemical properties of the soil and their relationship with soil organic carbon dynamics under the RRCS in northern Thailand. The RRCS can be divided into the following four categories by pattern: (1) Rice_F (rice (Oryza sativa) followed by a fallow period); (2) Rice_S (rice followed by shallots (Allium cepa L.); (3) Rice_Mixed crop (rice followed by tobacco (Nicotiana tabacum), vegetables, or maize (Zea mays)); and (4) Rice_P (rice followed by potatoes (Solanum tuberosum)). These patterns can be classified according to the dissolved organic carbon (DOC), the availability of nutrients from fertilization, and clay contents. In our study, the Rice-F and Rice-S patterns led to higher soil organic carbon (SOC) and dissolved organic carbon (DOC) in the soil, but when the Rice-P pattern was followed, the soil had a lower clay content, lower available phosphorus (Avail P), the lowest DOC, and high contents of calcium (Ca2+) and magnesium (Mg2+). This study also revealed that on the basis of relationships, clay content, Avail P, and DOC were the most important factors for the formation of SOC, while Ca2+ and Mg2+ were the subordinate factors for the decreased formation of SOC and carbon storage when the RRCS was followed. In addition, low SOC/clay when the Rice-P pattern was followed could reflect carbon saturation, while the percentages of DOC/SOC could indicate the decomposition and formation of SOC.

Physio-chemical characterization of sewage sludge generated from sewage treatment plant at Varanasi, in relation to nutrients and heavy metals for agriculture use

Large amount of sewage sludge is generated during waste water treatment at sewage treatment plant (STP), as a result of the sedimentation and suspension of particles. The safe disposal and management of this concentrated sewage sludge posesa major challenge for town and city municipal corporations. However, this could also be used in agriculture as an input to partially replace recommended doses of fertiliser. Thus, the current study was conducted to investigate the physio-chemical and biological characteristics of sewage sludge (SS) and its potential application in agricultural fields as an organic manure. Sewage sludge samples were collected from sewage treatment plant (STP) at Bhagwanpur, Varanasi, India and sieved in 2 mm mesh before being analysed for various physical and chemical characteristics. The processed sewage sludge possessed both major [total nitrogen (1.76 %), total phosphorous (1.29%), total potassium (1.15%)] and micro nutrients (Fe, Mn, Zn and Cu) and significant amount of organic carbon (8.67 %). However, this sewage sludge was also containing considerable amount of heavy metals like Cadmium (7.3 mg kg-1), chromium (49.2 mg kg-1), nickel (total 27.43 mg kg-1), and lead (39.53 mg kg-1), which were reported to be harmful to human beings, but these were lower than threshold limit recommended by Council of the European Communities, 1988 for agricultural use. Further, Bulk density and water holding capacity was 1.18 g cm-3 and 54.5 % respectively. With respect to microfauna, fungi were found more dominating than actinomycetes and bacteria in this sewage sludge. Therefore,considering use of this sewage sludge for agriculture may decrease the use of chemical fertilisers and make it more sustainable. However, in order to increase soil health without posing an environmental risk, sewage sludge must be carefully evaluated before being applied to soil especially for heavy metals and other hazardous pollutants.

Assessing amount of soil organic carbon and some soil properties under different land uses in a semi-arid region of northern Türkiye

The objective of this study is to investigate the effects of representative land use types and land cover (LUT/LC) of heavily deforested areas on soil properties in semi-arid region of Türkiye. Some of the soil properties have been measured on a grid with a 50 m sampling distance on the top-soil (0-15 cm depth). Data has been analyzed by using Ordinary Kriging/Spherical geostatistical model. Results indicated that the soil properties differed in terms of organic carbon (SOC), pH, bulk density, and the amount of sand, depending on the land uses in the study areas. The SOC concentration of top-soil layers has referred a significant difference (P<0.05) according to the land use type. Top-soil SOC concentrations in the four LUTLCs have been in the following order: cultivated areas < grasslands < Scotch pine stands = Uludağ fir stands. The impacts of LUTLC change on SOC and soil properties have not been restricted to the soil surface; however, relative changes have equally been high in the sub-soil, stressing the importance of sufficiently deep sampling. Furthermore, it has been determined that some physical and chemical characteristics of the natural forest soil have been significantly changed after long term and continuous cultivation. SOC loss is remarkable under the land use conversion while cropland has considerable potential to sequester SOC.

Soil microbial trait-based strategies drive the storage and stability of the soil carbon pool in Robinia pseudoacacia plantations

Soil microorganisms play an essential role in soil carbon sequestration and stability in forest ecosystems. However, how trade-offs in distinct microbial traits affect soil carbon storage and stability remains largely unknown, especially for forest soils that stock significant amounts of organic carbon. Here, we assessed the influences of the chronosequence of Robinia pseudoacacia (8, 18, and 30 years) on soil organic carbon (SOC) fractions and further explored the specific roles of microbial taxa in regulating soil carbon sequestration on the Loess Plateau via high-throughput sequencing techniques and analysis of co-occurrence networks and assembly processes. The results showed that the concentrations of soil easily oxidizable carbon (EOC), recalcitrant organic carbon (ROC), and SOC storage increased with stand age. However, the dissolved organic carbon (DOC) and microbial biomass carbon (MBC) concentrations increased from 8 years to 18 years and then decreased after 30 years. Stand age significantly affected the soil bacterial and fungal structures and diversity. Stochastic processes, especially dispersal limitation, were the main assembly processes affecting the bacterial and fungal communities. Soil pH, DOC and the N:P ratio drove bacterial assembly. However, fungal assembly was not affected by soil properties. Moreover, network analysis showed that three major bacterial modules and one major fungal module (Bac_Mod 1, 3, 4 and Fun_Mod 2) showed strong relationships with soil carbon storage and were considered soil carbon pool-associated modules. These modules based on the co-occurrence network analysis were composed of microbial taxa with different taxonomic and functional traits. Both random forest and correlation analyses indicated that increases or decreases in these modules were strongly correlated to variations in SOC fractions. These results demonstrated that with R. pseudoacacia plantation development, the recalcitrant-related module attributed to SOC became more stable.

Redox oscillations destabilize and mobilize colloidal soil organic carbon

The onset of oxic-anoxic events in soil induces biogeochemical processes that may have profound influences on the fate and transport of soil organic carbon (OC). An 18-wk long laboratory soil column study was conducted to investigate the influence of static oxic (SO), static anoxic (SA), or redox oscillation (RO) events on the release of OC. Column leachate samples were collected after 9-wk and 18-wk of incubations and separated into dissolved (<2.3 nm), natural nanoparticle (2.3–100 nm), fine colloid (100–450 nm), and particulate (> 450 nm) fractions that were characterized through spectrofluorometric analyses. The concentration of released OC from different treatment columns followed the order of SA > RO > SO. After 9-wk, total OC concentrations in the leachate samples were increased by 4-fold and 54-fold in the SO and SA columns compared to the time-zero control columns, respectively. However, after 18-wk, the released amount of OC doubled in SO but decreased by 50 % in SA columns compared to the 9-wk incubation samples. The RO columns had intermediate OC concentrations between the SO and SA treatments. The RO events further led to widely varied dynamics in the release and molecular composition of the size-fractionated OC compared to static conditions, indicating the effects of redox oscillation on the organo-mineral association in soil. The wide variations in the aromaticity of OC released after the 1st and 2nd RO events further support the notion that alternating redox processes regulate OC cycling differently than the SO or SA condition. The observed increase in fine colloid and particulate OC fractions (i.e., >100 nm) from 7 % to 40 % between 1st and 2nd RO suggests the clustering of nanoaggregates and/or formation of colloidal size aggregates. The composition of the released OC as influenced by redox fluctuations provides a baseline for the size continuum of soil OC and its potential ecological and environmental roles.

Assessment of long-term land use and land cover change effects on soil erosion and soil organic carbon stock in humid ecosystem condition

This study examined the consequences of land use and cover (LULC) changes on soil erosion and soil organic carbon in the Ünye district of Ordu province in the Central Black Sea Region where humid conditions prevailed in 1999, 2009, and 2019. GIS-based Revised Universal Soil Loss Equation (RUSLE) modeling approach, geostatistics and remote sensing techniques were employed in the study. According to the results considering the long years in the study area, the most relative change among LULC species was hazelnut fields with an increase of 167%. In this process, it has been determined that there are few spatial changes that occurred in artificial areas and pasture lands. In addition, in the classes of soil erosion rates defined by RUSLE, the areas classified as Very Low–Low (< 5 tons ha−1 year−1) for many years inhabit the largest area in the study area. The loss in the amount of soil organic carbon (SOC) is determined to have occurred mostly in areas with Very Low and Low erosion rates. However, it has been determined that SOC loss ensues in areas with Very High (> 20 tons ha−1 year−1) erosion rates, albeit slightly. Therefore, even in the areas with very slight erosion, soil conservation practices should be expanded to secure the long-term sustainability of the production system, especially in agriculture and hazelnut areas.

Comparative analysis of soil organic carbon in selected river catchments

The present study deals with the investigation of soil organic carbon in two water catchments in Northern Rila, Western Bulgaria. Field research, combined with analysis, provided sufficient data. Six key sites were selected and sampled in order to estimate and compare the amount of organic and inorganic carbon in the topsoil. The applied criteria for the choice of sites included: vegetation cover, predominant soil group, level of anthropogenization and transport accessibility. A total number of 13 samples from both catchments were collected and analyzed in the Central laboratory of the Institute of Soil Science, Agrotechnologies and Plant Protection (ISSAPP) “N. Pushkarov“. The results concern the amount and composition of soil organic matter in different soils – Cambisols (Albic, Humic, Dystric), Fluvisols and Umbrosols. The total carbon content of all samples varies between 1.23 and 9.69%. The amount of organic carbon ranges between 0.45 and 3.73%. The results of the study prove once again that the preservation of natural vegetation and current condition of the soil is of great importance for carbon sequestration and climate change mitigation.

Waste carbon conversion and utilization in chemical wastewater treatment process: Experimental approaches from lab-to pilot-scale

Chemical wastewater often contains large amounts of waste organic carbon. The current chemical wastewater treatment plants are an open carbon emission system. Inspired by the topic of CO2 conversion and utilization, this study provided a redesigned flowchart of chemical wastewater treatment process via closed-loop carbon conversion and utilization system for the resource utilization of waste carbon from wastewater. Purified terephthalic acid (PTA) wastewater, a common chemical wastewater, was selected to test the feasibility of the proposed strategy. An integrated closed-loop system involving activated sludge-microalgae-pyrolysis process was employed. Initially, a laboratory-scale wastewater treatment system combining activated sludge with microalgae process was applied for the carbon conversion and utilization in PTA wastewater. The COD removal efficiency was obtained at 93.02%, and over 94% of CO2 was captured. Microbial DNA analysis of the activated sludge indicated that the functional microorganisms mainly included Proteobacteria, Bacteroidetes, and Chloroflexi. Metabolic analysis of the microalgae showed that the abundances of differential metabolites associated with carbon metabolism significantly increased after treatment. Furthermore, a pilot-scale integrated system was applied to test this strategy and in which obtained a good performance in COD removal and CO2 capture. The produced excess biomass during chemical wastewater treatment, which was usually viewed as hazardous solid waste, was converted to biochar and carbonaceous combustible gas via pyrolysis. The produced biochar could be used as photocatalysts to remove antibiotic. The findings provided a new design to simultaneously achieve water pollution control, carbon conversion & utilization, and resource & energy recovery in chemical wastewater treatment process.

Microfluidic Impedance Cytometry for Single-Cell Particulate Inorganic Carbon:Particulate Organic Carbon Measurements of Calcifying Algae.

Calcifying algae, like coccolithophores, greatly contribute to the oceanic carbon cycle and are therefore of particular interest for ocean carbon models. They play a key role in two processes that are important for the effective CO2 flux: The organic carbon pump (photosynthesis) and the inorganic carbon pump (calcification). The relative contribution of calcification and photosynthesis can be measured in algae by the amount of particulate inorganic carbon (PIC) and particulate organic carbon (POC). A microfluidic impedance cytometer is presented, enabling non-invasive and high-throughput assessment of the calcification state of single coccolithophore cells. Gradual modification of the exoskeleton by acidification results in a strong linear fit (R 2= 0.98) between the average electrical phase and the PIC:POC ratio of the coccolithophore Emiliania huxleyi 920/9. The effect of different CO2 treatments on the PIC:POC ratio, however, is inconclusive, indicating that there is no strong effect observed for this particular strain. Lower PIC:POC ratios in cultures that grew to higher cell densities are found, which are also recorded with the impedance-based PIC:POC sensor. The development of this new quantification tool for small volumes paves the way for high-throughput analysis while applying multi-variable environmental stressors to support projections of the future marine carbon cycle.

Mobilization of subsurface carbon pools driven by permafrost thaw and reactivation of groundwater flow: a virtual experiment

Permafrost thaw leads to an increase in groundwater circulation and potential mobilization of organic carbon sequestered in deep Arctic sediments (e.g. 3–25 m below surface). Upon thaw, a portion of this carbon may be transported along new groundwater flow paths to surface waters or be microbially transformed or immobilized by in-situ biogeochemical reactions. The fate of thaw-mobilized carbon impacts surface water productivity and global climate. We developed a numerical model to investigate the effects of subsurface warming, permafrost thaw, and resultant increased groundwater flow on the mobilization and reactive transport of dissolved organic carbon (DOC). Synthetic simulations demonstrate that mobilization and groundwater-borne DOC export are determined by subsurface thermo-chemical conditions that control the interplay of DOC production (organic matter degradation), mineralization, and sorption. Results suggest that peak carbon mobilization from these depths precedes complete permafrost loss, occurring within two centuries of thaw initiation with the development of supra-permafrost groundwater flow systems. Additionally, this study highlights the lack of field data needed to constrain these new models and apply them in real-word site-specific applications, specifically the amount and spatial variability of organic carbon in deep sediments and data to constrain DOC production rates for groundwater systems in degrading permafrost. Modeling results point to key biogeochemical parameters related to organic matter and carbon bioavailability to be measured in the field to bridge the gap between models and observations. This study provides a foundation for further developing a physics-based modeling framework to incorporate the influence of groundwater flow and permafrost thaw on permafrost DOC dynamics and export, which is imperative for advancing understanding and prediction of carbon release and terrestrial-aquatic carbon exchange in warming Artic landscapes in the coming decades.

Environmental changes during the MIS 6a–MIS 5e transition: the Parchliny 2016 profile, central Poland

We describe the penultimate glacial – last interglacial transition from the one of the numerous palaeolake successions in central Poland, which have yielded many documented Eemian and Early Weichselian floral records. In the new profile, Parchliny 2016, the lacustrine deposits were analysed lithologically, botanically, zoologically, and geochemically, providing new data that illustrate the environmental transition from the Late Saalian (MIS 6a) to the Eemian interglacial (MIS 5e). Five phases of palaeolake development have been distinguished. The first phase was related to the rapid melting of a dead ice block buried in the tills to form a lake. The second phase documented a Late Saalian initial succession, with the dominance of open steppe communities (Stadial 1), followed by a third phase with gradual increasing density of vegetation, the spread of boreal forests (Zeifen interstadial) and further increase in open communities and the retreat of pine (Kattegat stadial). The fourth phase reflected the beginning of Eemian interglacial by the expansion of pioneering birch-pine and purely birch forests and an increasing proportion of deciduous trees, including oak (Vth phase). Diatom, cladoceran and geochemical studies indicate at least two stages of lake development. The first stage (Late Saalian) was of an open lake (2–4 m deep), in relatively cold conditions and nutrient-poor water with the lowest amounts of organic carbon and nitrogen. The second stage (Eemian interglacial), shows warmer, shallower conditions in which the lake’s primary production increased, the water was well oxygenated, and there were more trophic levels.

Latest avenues and approaches for biohydrogen generation from algal towards sustainable energy optimization: Recent innovations, artificial intelligence, challenges, and future perspectives

The limited resources of fossil fuels and bio energies, along with the environmental pollution caused by their combustion, make it necessary to search for renewable and clean alternative sources and to optimize the available current energies specifically for required energy for using in buildings. This is mandatory for a solution of future energy production issues as huge consumption of energy in buildings and structures is unavoidable in buildings for instance China's higher education buildings consume huge amounts of bioenergy. Most of the attention in the production of biofuel has been focused on the use of plant biomass, agricultural waste, solid waste, and sewage treatment sludge. Today, there are renewable resources to replace fossil fuels such as biofuels for usage in buildings required energy; however, in the last decade, the cultivation of microalgae has been proposed as another option for biomass production. Utilization of algae biomass is more cost-effective than vegetable crops in terms of water consumption and cultivated area and reduces costs and greenhouse gas emissions by replacing fossil fuels. Artificial intelligence is a tool to help for this utilization and becoming much better in recent researches. Many types of microalgae, due to their high ability to consume organic carbon and inorganic nitrogen and phosphorus, can grow in different water environments, including urban, industrial, agricultural wastewaters, and wastewaters containing animal waste, which contain large amounts of organic and inorganic carbon. There are nitrogen, phosphorus and other elements that act as a biological filter that with extensive studies and inventing new methods, cost-effective production of algae-biofuels can be achieved. This review goals to run over the latest innovations and artificial intelligence approaches for biohydrogen generation from algal towards sustainable energy optimization and greener environment for buildings required energy. The current state of the art, existing and upcoming challenges, latest technologies, and solutions to overcome existing limitation are presented in details.

Evaluation of the carbon capacity of single breed wood stands – elements of the green infrastructure of Kharkiv

The value of the carbon capacity of the elements of the green infrastructure makes it possible to find out the amount of accumulated carbon in plants throughout their life, and, as a result, to establish the provision of the city with green spaces. Purpose. To investigate the carbon capacity of the green infrastructure of the Kharkiv city. Methods. Statistical, modeling methods, methods of measurement and comparison. Results. Six objects of single-breed tree stands of the green infrastructure of the city of Kharkiv were studied: linear protective plantings, green boulevards, where the main species is maple (Acer platanoides) and on the territory of the objects of the nature reserve fund - a regional landscape park and a forest reserve, where the main the species is pedunculated oak (Quercus robur). It was determined that about 60-80% of the total amount of carbon accumulates in the living phytomass of plants, litter deposits from 1 to 7% of carbon, and the rest accumulates in the soil. In living phytomass, the largest share of carbon is accumulated in the trunk of the plant, and the smallest amount is in the leaves. There is a direct dependence of the amount of deposited carbon on the area of green spaces, which increases along with the increase in the area of the facility. The total mass of deposited carbon on six researched objects, with a total area of 252.1 ha, is 48357.47 t, or 191.84 t/ha. Conclusions. A direct relationship between the area of green infrastructure objects and the amount of organic carbon deposited in them has been established. The most carbon accumulates in the living phytomass of plants, namely in the trunk of plants, and the least in the leaves of plants. Oak plantations store more carbon than maple plantations.

Research Progress on Dormancy Mechanism and Germination Technology of Kobresia Seeds.

Kobresia is a subfamily of Cyperaceae, a perennial herbaceous plant that stores a large amount of organic carbon and nutrients (nitrogen, phosphorus, etc.) in the soil. This type of grass is soft and appreciated by all kinds of farm animals. It is one of the predominantly excellent fodder on the Qinghai-Tibet Plateau. Its good growth plays an important role in developing the local economy and maintaining ecological balance on the Qinghai-Tibet Plateau as well. The main objectives of this review are to systematically present and analyze the factors responsible for the low germination rate of Kobresia and to analyze the physical and chemical methods that are used in order to alleviate dormancy and to improve the germination rate of Kobresia seeds. This is performed in order to lay the foundation for future research in this field. At the same time, we have analyzed the research deficiencies and formulated recommendations for the future. This review will provide comprehensive information in order to reduce the cost of planting Kobresia, as well as to provide theoretical support and technical guidance for the purposes of ecosystem restoration and livestock development.

Dynamics of Vegetation Productivity in Relation to Surface Meteorological Factors in the Altay Mountains in Northwest China

Vegetation productivity, as the basis of the material cycle and energy flow in an ecosystem, directly reflects the information of vegetation change. At the ecosystem level, the gross primary productivity (GPP) refers to the amount of organic carbon fixed by plant bodies. How to accurately estimate the spatiotemporal variation of vegetation productivity of the forest ecosystem in the Altay Mountains in northwest China has become a critical issue to be addressed. The Altay Mountains, with rich forest resources, are located in a semi-arid climate zone and are sensitive to global climate changes, which will inevitably have serious impacts on the function and structure of forest ecosystems in northwest China. In this paper, to reveal the variation trends of vegetation gross primary productivity (GPP) and its response to surface meteorological factors in the Altay Mountains in northwest China, daily temperature and precipitation data from the period of 2000–2017 were collected from seven meteorological stations in Altay prefecture and its surrounding areas; the data were analyzed by using the MODIS GPP model, moving average trend analysis, linear regression analysis and the climate tendency rate method. The results show that: (1) The spatial distribution pattern of GPP in the whole year was almost the same as that in the growing season of vegetation in the Altay Mountains. In the whole mountain range, the proportion of the area which had a GPP value of 400–600 g c/m2 had the highest value; the proportion of the annual and growing season of this area was 41.10% and 40.88%, respectively, which was mainly distributed in the middle and west alpine areas of the Altay Mountains. (2) There was a big gap in the GPP value in the different stages of the vegetation growing season (April to September), which reached the highest value in July, the area with a GPP of 100–150 g c/m2 was the highest, with 36.15%. (3) The GPP of the Altay Mountains showed an overall increasing trend, but the annual fluctuation was relatively large. In 2003, 2008, 2009 and 2014, the GPP showed lower values, which were 385.18 g c/m2, 384.90 g c/m2, 384.49 g c/m2 and 393.10 g c/m2, respectively. In 2007, 2011 and 2016, the GPP showed higher values, which were 428.49 g c/m2, 428.18 g c/m2 and 446.61 g c/m2. (4) In 64.85% of the area of the Altay Mountains, the GPP was positively correlated with annual average temperature, and in 36.56% of the area, the correlation coefficient between temperature and GPP ranged from −0.2 to 0. In 71.61% of the area of the Altay Mountains, the GPP was positively correlated with annual accumulated precipitation, and in 28.39% of the area, the GPP was negatively correlated with annual accumulated precipitation. Under the scenario of global climate change, our study has quantitatively analyzed the long-term dynamics of vegetation GPP and its responses to meteorological factors in the Altay Mountains, which would be helpful for evaluating and estimating the variation trends of forest ecosystems in China, and has important guiding significance for policy formulation to protect forest resources and improve the local ecological environment.

Higher Temperature Sensitivity of Ecosystem Respiration in Low Marsh Compared to High Elevation Marsh Ecosystems

AbstractSalt marsh habitats contain some of the highest quantities of soil organic carbon (C) per unit area, but increasing anthropogenic stressors threaten their ability to maintain themselves as large C reservoirs in some regions. We quantify rates of C gas exchange (methane [CH4] and carbon dioxide [CO2]) monthly across a 16‐month period from a low nitrogen “reference” salt marsh on Cape Cod in New England using static chambers. While the summer period is the most dynamic period of marsh C gas exchange, we observed substantial fluxes in the early summer through late fall, highlighting the importance of including shoulder seasons in studies of marsh C exchange. We estimate annual ecosystem respiration between 108 and 252 g C m−2 yr−1, which varied based on temperature and elevation. This flux is lower than in other nearby marshes, which we attribute to the frequently inundated, microtidal nature of the site, resulting in the majority of respired CO2 being exported via lateral, not vertical, fluxes from this marsh. We observed significantly higher temperature sensitivity from the low elevation of the marsh compared to the high marsh. Recent acceleration in the rate of sea level rise is leading to a well‐documented expansion of low marsh into high marsh vegetation zones in this marsh system and others in the region. While rates of C burial are higher in the low marsh compared to the high marsh, the higher temperature sensitivity of respiration in the low marsh may diminish the longevity of marsh C stocks with climate warming.

What makes soil landscape robust? Landscape sensitivity towards land use changes in a Swiss southern Alpine valley

Landscape sensitivity is a concept referring to the likelihood that changes in land use may affect in an irreversible way physical and chemical soil properties of the concerned landscape. The objective of this study is to quantitatively assess the sensitivity of the southern Alpine soil landscape regarding land use change-induced perturbations. Alpine soil landscapes can be considered as particularly sensitive to land use changes because their effects tend to be enhanced by frequent extreme climatic and topographic conditions as well as intense geomorphologic activity. In detail, the following soil key properties for soil vulnerability were analysed: (i) soil texture, (ii) bulk density, (iii) soil organic carbon (SOC), (iv) saturated hydraulic conductivity (Ksat), (v) aggregate stability and (vi) soil water repellency (SWR). The study area is characterized by a steep, east-west oriented valley, strongly anthropized in the last centuries followed by a progressive abandonment. This area is particularly suitable due to constant lithological conditions, extreme topographic and climatic conditions as well as historic land use changes. The analysis of land use change effects on soil properties were performed through a linear mixed model approach due to the nested structure of the data. Our results show a generally high stability of the assessed soils in terms of aggregate stability and noteworthy thick soils. The former is remarkable, since aggregate stability, which is commonly used for detecting land use-induced changes in soil erosion susceptibility, was always comparably high irrespective of land use. The stability of the soils is mainly related to a high amount of soil organic matter favouring the formation of stable soil aggregates, decreasing soil erodibility and hence, reducing soil loss by erosion. However, the most sensitive soil property to land use change was SWR that is partly influenced by the amount of soil organic carbon and probably by the quality and composition of SOM.