Search Results (40)

The changes in soil nitrogen mineralization rate induced by litter input can determine the availability of nitrogen for plant growth in the soil. In forest ecosystems, the mixing of different species of litter can alter the chemical properties of the litter, ultimately affecting the rates of soil nitrogen transformation and cycling. In this study, litters with Fraxinus mandshurica Rupr. and Larix gmelinii (Rupr.) Kuzen. and mixed litter with Fraxinus mandshurica and Larix gmelinii were added to dark brown soil and incubated in the lab for 175 days at 25 °C. NH₄⁺-N and NO₃⁻-N contents and nitrogen mineralization rates were periodically measured to explore the effect of mixed litter addition on soil nitrogen mineralization. The results showed that compared to Larix gmelinii litter, Fraxinus mandshurica litter demonstrates higher carbon, nitrogen, and phosphorus contents while exhibiting lower lignin and cellulose contents and lower C/N and lignin/N ratios. Soil inorganic nitrogen content showed a trend of initial decrease followed by an increase. At the end of the incubation, soil NH₄⁺-N and NO₃⁻-N and the total inorganic nitrogen contents were 4.6–7.8 times, 2.2–3.4 times, and 2.9–4.3 times higher than the initial value, respectively. The soil nitrogen mineralization rate exhibited an initial rapid increase followed by stabilization. During days 7–28 of incubation, the nitrogen mineralization rates in litter addition treatments were lower than that in the control, while they were higher than that in the control during days 42–175. The soil nitrogen mineralization rate in the treatments with Fraxinus mandshurica litter and mixed litter were higher than those in the treatment with Larix gmelinii litter. The cumulative net nitrogen mineralization amounts in the Fraxinus mandshurica litter and mixed litter treatments were higher than those in the Larix gmelinii litter treatment, being 1.5 and 1.2 times those of the Larix gmelinii litter treatment, respectively. MBC and MBN presented a trend of first increasing and then decreasing, peaking on days 7 and 14 of incubation, respectively. Correlation analysis revealed that soil inorganic nitrogen content and nitrogen mineralization rate were positively correlated with the litter total nitrogen and soil microbial carbon and nitrogen and negatively correlated with litter C/N and lignin/N. The changes in soil inorganic nitrogen and nitrogen mineralization are primarily associated with soil microbial immobilization. Initially, in the treatments with litter addition, an increase in microbial biomass enhanced the immobilization of soil inorganic nitrogen. Subsequently, as litter mineralization progressed, the amount of litter decreased, leading to reduced microbial biomass and weakened immobilization. This study indicates that the interaction between litter types and soil microorganisms is the key factor affecting soil nitrogen mineralization process and soil mineral nitrogen content. These findings provide a scientific basis for soil fertility management in the forest ecosystems of Northeast China. Full article

This study has been conducted to assess the anthropogenic impact of the ANWIL S.A. nitrogen plants, one of the largest producers of nitrogen fertilizers in Poland, on the activity of arylsulphatase (AR), rhodanese (RDN) and catalase (CAT) related to sulphur transformation in forest soils. Samples of rusty brown soils were collected in the area adjacent to the ANWIL S.A. nitrogen plants in Włocławek. The profiles were located in the vicinity of the following production plants: No. W1—approximately 2.5 km away, No. W2—approximately 2 km away, and No. W3—approximately 0.8 km away. The control profile was established in the Tuchola Forest, which is part of the Biosphere Reserve. In order to recognize the impact caused by pollutants and the capacity of soil for re-generation, the resistance index (RS) and resilience index (RL) were determined. The highest RS value (0.964) was noted for rhodanese activity in layer Bv in W2, where the lowest RS for CAT (0.019) was observed. This study demonstrated the resilience of CAT activity in layer Bv in all the soil profiles adjacent to ANWIL. The highest resilience indicator was soil catalase activity. Enzymatic activity can be used to indicate the anthropogenic impact and the transformation of nutrients in forest soil. Full article

The accurate prediction of the spatial distribution of soil organic carbon (SOC) and the identification of the mechanisms underlying its spatial differentiation are of paramount significance for the conservation and utilization of land and regional sustainable development. A total of 512 soil samples were collected from Wuchang and Shuangcheng County in Harbin City, Heilongjiang Province, China, which served as the study area. Six machine learning models, including Random Forest (RF), AdaBoost, Support Vector Regression (SVR), weighted average, Stacking, and Blending, were utilized to predict the spatial distribution of SOC and analyze its spatial differentiation. The result reveals that 12 environmental variables, including soil type, bulk density, pH, average annual precipitation, average annual temperature, net primary productivity (NPP), land use type, normalized difference vegetation index (NDVI), slope, elevation, soil parent material, and distance to rivers, are effective influencing factors on SOC in the study area. It turns out that the Stacking model, with an R² of 0.4327, performed the best in this study, followed by the weighted average, Blending, RF, AdaBoost, and SVR models; a heterogeneous integrated learning model may be more robust than an individual learner. The predicted SOC content is generally lower in the northwestern arable land and higher in the southeastern forest land. In addition, SOC differentiation shows that forest land and grass land with dark brown soil or swamp soil, soil covering igneous and metamorphic rocks with various minerals, higher elevation and slope, and suitable water-thermal and soil intrinsic conditions for aerobic microbial activity benefit the enrichment of SOC in the study area. The enrichment and depletion of SOC are jointly influenced by pedogenesis, microbial activity, and biodiversity. Full article

Wood-decay fungi, including white- and brown-decay fungi, are well known for their ability to degrade lignin and cellulose, respectively. The combined use of these fungi can increase the decomposition of woody substrates. Research has indicated that these fungi also exhibit inhibitory effects against Bursaphelenchus xylophilus, the causative agent of pine wilt disease (PWD). In this study, we investigated a composite microbial formulation that efficiently decomposes pine wood while inhibiting B. xylophilus. We initially established a correlation between the degradation rate of wood blocks and fungal biomass, underscoring the necessity of optimizing biomass for effective treatment. A systematic approach involving a one-way test, a Plackett–Burman design, a steepest ascent experiment, and a Box–Behnken design, was employed to optimize the fermentation process. Validation trials were conducted in a 10-L fermenter. The bioagent’s efficacy and safety were assessed through field applications in a forest, with a focus on wood degradation capacity and B. xylophilus mortality rate. Additionally, the environmental impact of the microbial products was evaluated by analysing soil quality around treated areas to ensure that the formulation did not adversely affect soil health. Full article

Brown soils, Brown forest soils, Burozems or Cambisols have been studied for more than 100 years, and to this day, their nature, origin and process organization remain controversial. In addition, issues of their geography are quite controversial, especially in such a large country as Russia. A brief review of the literature on the morphological diversity features of the genesis and origin of brown soils in the various geographical locations of Eurasia is given. It was shown that the genesis of brown soils is not as closely related to the type of forest vegetation as previously thought, although, at the same time, the vast majority of brown soils are forest soils. Depending on the geographic situation and local climatic and geogenic conditions, Brown forest soils have related subtypes among adjacent soil types in different natural zones. Thus, in the polar zone, they are close to Entic Podzols, in the subtropics to Cinamonic soil, and in the forest-steppe, they replace zonal Retisols in positions with a relatively less contrasting and even climate. Being to a certain extent intrazonal soils, brown soils are combined with other more intrazonal soils—Rendzinas—and form the so-called Burozem-Rendzinas on uplands, composed of carbonate rocks in various natural zones. The article is illustrated with original photographs of Brown forest soils from various natural zones, taken by the author during numerous expeditions. It has been established that Burozems combine the characteristics of intrazonal soil, which is inherent in all natural zones, and have elements of zonal soils, as well as adjacent intrazonal soils in invariant combinations of soil-forming factors. From this, two conclusions can follow about their further classification fate: a more thorough justification for an independent soil type or a classification of structural metamorphism and in situ transformation of minerals among various existing zonal soil types. Full article

Effective phosphorus (P) management is crucial for optimal blueberry production. However, a comprehensive understanding of phosphorus distribution across soil depths and types after two decades of blueberry cultivation remains a challenge. This study examines pH, EC, SOC (soil organic carbon), Total N (total nitrogen), and phosphorus fractions in soils from Japanese blueberry fields that have been cultivated for over 20 years. The soils selected for this study represent typical soils from long-term blueberry-growing regions in Japan, ensuring the relevance of the findings to these key agricultural areas. Soil samples were gathered from depths of 0–30 cm and 30–60 cm, revealing significant variations in phosphorus content that are influenced by soil properties and fertilization history. Soil types such as KS (Kuroboku soils) and FS (Fluvic soils) show higher Total P accumulation in deeper layers, whereas BFS (Brown Forest soils) and RYS (Red-Yellow soils) accumulate more in shallower layers. Long-term cultivation has led to greater non-labile phosphorus (NLP) accumulation in shallower layers of KS, BFS, and FS soils, indicating strong phosphorus fixation. BFS soil also exhibits increased organic phosphorus (NaOH-Po) at deeper depths. NaOH-Po and NaHCO₃-Po, through their interactions with EC and pH, critically modulate the transformation of NLP into labile phosphorus (LP), thereby influencing overall phosphorus and nitrogen dynamics in the soil. These findings underscore the importance of tailored phosphorus fertilization strategies based on blueberry field characteristics, providing a basis for low-input phosphorus fertilization approaches. Full article

Soil microorganisms are a crucial component of forest ecosystems because of their involvement in the decomposition of organic matter and nutrient cycling and their influence on plant growth and development. Soil type is a fundamental characteristic of soil. In the transitional forest regions from subtropical to temperate zones in China, various soil types can be found, including yellow-brown soils, brown soils, and cinnamon soils. However, the composition and distribution patterns of soil bacterial and fungal communities in different soil types remain uncertain. This study selected a 4.8-hectare plot in Baiyun Mountain Forest National Park, China. To explore the spatial distribution and ecological processes of soil microbial communities across three different soil types, Illumina sequencing was conducted. Results showed that the composition and assembly of bacterial and fungal communities varied substantially among different soil types. Bacteria were more influenced by environmental factors than fungi. Fungal communities consistently demonstrated greater stability compared to bacterial communities across the three soil types. Light was the main environmental factor driving the variation in the assembly of microbial communities among different soil types. This study demonstrates that there are differences in the composition and structure of soil microbial communities among different soil types, providing important insights into the management and sustainable development of soil microorganisms in temperate forests. Full article

Nutrient fertilizer application to agricultural land has led to greenhouse gas emissions and has altered soil nitrogen (N) deposition. In soil, N can be degraded in four ways: entering surface water through water flow, absorption by plants and microorganisms, decomposition into gas, and deposition as minerals. This study proposes the concept of N degradability and aims to clarify how farming activities affect N degradability in soil. Over 260 soil profiles were excavated, and the effective soil depth, coordinates, soil types, and vegetation were recorded at each measurement point. The following characteristics were determined in the soil samples: pH, organic matter, total N, total phosphorus, total potassium, total soluble N, available phosphorus, and available potassium. The sample characteristics were subjected to Pearson correlation analysis, principal component analysis, and one-way analysis of variance. The 260 samples included four soil types: dark brown soil, black soil, albic black soil, and meadow soil. Black soil exhibited more stable N levels compared with the other three soil types, showing a tendency towards N accumulation. Ground vegetation was categorized into seven types: forest, rice, maize, red adzuki bean, grassland, soybean, and others. Forests contributed the most to N deposition. Conversely, planting maize led to a tendency for N loss compared with forests. This study can provide a reference for the sustainable development of agriculture and the balance of ecological protection. Full article

The West Sahel is facing significant threats to its vegetation and wildlife due to the land degradation and habitat fragmentation. It is crucial to assess the regional vegetation greenness dynamics in order to comprehensively evaluate the effectiveness of protection in the natural reserves. This study analyzes the vegetation greenness trends and the driving factors in the Dosso Partial Faunal Reserve in Niger and nearby unprotected regions—one of the most important habitats for endemic African fauna—using satellite time series data from 2001 to 2020. An overall vegetation browning trend was observed throughout the entire region with significant spatial variability. Vegetation browning dominated in the Dosso Reserve with 17.7% of the area showing a significant trend, while the area with significant greening was 6.8%. In a comparison, the nearby unprotected regions to the north and the east were found to be dominated by vegetation browning and greening, respectively. These results suggest that the vegetation protection practice was not fully effective throughout the Dosso Reserve. The dominant drivers were also diagnosed using the Random Forest model-based method and the Partial Dependence Plot tool, showing that water availability (expressed as soil moisture) and land use/land cover change were the most critical factors affecting vegetation greenness in the study region. Specifically, soil moisture stress and specific land management practices associated with logging, grazing, and land clearing appeared to dominate vegetation browning in the Dosso Reserve. In contrast, the vegetation greening in the central Dosso Reserve and the nearby unprotected region to the east was probably caused by the increase in shrubland/forest, which was related to the effective implementation of protection. These findings improve our understanding of how regional vegetation greenness dynamics respond to environmental changes in the Dosso Reserve and also highlight the need for more effective conservation planning and implementation to ensure sustainable socio-ecological development in the West Sahel. Full article

Spent adsorbents used in As removal treatment may re-leach As. In this study, the effects of soil on spent Mg-based and Ca-based adsorbents were investigated. The spent adsorbents containing arsenite (As(III)) were prepared by adsorbing As(III) on MgO, Mg(OH)₂, CaO, and Ca(OH)₂ powder reagents. Kuroboku soil (Ku), yellow-brown forest soil (YF), Kanuma soil (Ka), river sand (RS), and mountain sand (MS) were used as soil samples. The As leaching ratio was examined in coexistence with soil via shaking tests, and the results were compared with those of a previous study on adsorbents containing arsenate (As(V)). The environmental stability of the spent adsorbents was found to vary greatly depending on the combination of the As valence, adsorbent type, and soil type. However, regardless of the adsorbent or soil type, the spent adsorbents containing As(III) were more likely to leach As than those containing As(V). Additionally, the As leaching ratio was generally lower in Ku and YF and higher in Ka, RS, and MS. For environmentally friendly and sustainable As removal treatment, disposal, and management, the selection of MgO as the adsorbent and treatment involving the oxidation treatment of As(III) to As(V) before adsorbing As onto adsorbents are recommended. Full article

This study investigates the structure of soil bacterial communities in the brown mountain soils beneath the deciduous broadleaf forests of Dongling Mountain and their response to soil physicochemical properties. Aiming to provide a scientific basis for soil conservation and sustainable forest development under deciduous broadleaf forests, this research utilized high-throughput sequencing technology to examine the diversity and community structure of bacteria in soil under different tree species, alongside assessing soil physicochemical properties. The results revealed significant differences in nutrient content between the 0–20 cm and 20–40 cm soil layers. Additionally, the N:P in the brown mountain soils of Dongling Mountain was found to be below the national average, indicating potential nitrogen limitation. Dominant bacterial phylum included Actinobacteria, Proteobacteria, and Acidobacteria. The study also found that soil bacterial community structure was similar under different tree species at the same depth but varied significantly with soil depth. Furthermore, redundancy analysis (RDA) showed that the available potassium (AK), total nitrogen (TN), and ammonium nitrogen (NH₄⁺-N) significantly influenced the structural changes in the soil bacterial community. This research highlights the characteristics of soil bacterial community structure beneath deciduous broadleaf forests and its relationship with soil physicochemical properties, offering valuable insights for regional soil ecosystem conservation and forest management. Full article

Climate change requires the introduction of alternative crops in certain temperate areas due to the warmer and drier growing seasons. Maize, one of the most important crops, is projected to become less tolerant of a drier climate. Therefore, it is necessary to find an alternative species that is less susceptible to environmental stressors. This study compared the germination, growth vigour, and stress tolerance of maize and sorghum grow in six types of soil under three water regimes. The results indicate that sorghum germination is faster and more uniform. The most significant differences in germination rates were found in chernozem (88.9% and 72.2% for sorghum and maize, respectively) and saline solonetz (74.4% and 63.3% for sorghum and maize, respectively). Maize exhibited higher growth vigour only in three cases, i.e., under solonetz–flooding, shifting sand–drought, and brown forest floor–flooding conditions. An ANOVA showed a significant difference between sorghum and maize stress conditions due to soil conditions and water availability (p < 0.0001). Sorghum can be a suitable alternative to maize, but only in areas with hot, dry periods and in areas where the soil is not too prone to waterlogging, regardless of its quality. Full article

In this study, carbon and nitrogen contents in the undisturbed terrestrial ecosystems in the northern taiga zone of Russia’s Murmansk region were estimated. The goal of this study was to examine the carbon and nitrogen dynamics in atmospheric precipitation, assimilating organs of coniferous trees (Picea obovata and Pinus sylvestris), needle litter, soils, and soil water. The objects of our research were the most common dwarf shrub-green moss spruce forests and lichen-dwarf shrub pine forests of the boreal zone. The study was carried out on permanent plots between 1999 and 2020. The long-term dynamics of carbon concentrations in snow demonstrated a trend towards increasing carbon concentrations in forested and treeless areas of the Murmansk region. It was shown that in representative spruce and pine forests, the concentrations and atmospheric precipitation of carbon compounds and carbon leaching with soil water were higher below the tree crowns, compared to between the crowns. In soil water, a decrease was found in carbon concentration with the soil profile depth. For soils, the highest carbon concentrations were found in the organic and illuvial soil horizons. The main soil sinks of carbon and nitrogen in northern taiga forests were found to be located in the organic soil horizon below the crowns. In northern taiga forests, the carbon content of living Picea obovata and Pinus sylvestris needles and Pinus sylvestris needle litter had minor variability; no significant interbiogeocoenotic and age differences were found. We found that the nitrogen content in brown needles and needle litter was significantly lower compared to photosynthetically active needles, probably due to retranslocation processes (withdrawal before needle abscission), corroborating the literature in the results session. The largest stocks of carbon and nitrogen in northern taiga forests are concentrated in the soil organic horizon, and the removal of these elements with soil water is insignificant. Carbon and nitrogen stocks in living and fallen needles are lower than in soil. The least amount of carbon and nitrogen is contained in atmospheric precipitation. Full article

The purpose of this article was to assess the participation of young soils of ash dump forest communities in carbon sequestration by soils of southern taiga forests, considering the physico-chemical properties of the ash substrate and forest litter (pH, TOC, TN, content of P and K mobile compounds, and exchangeable Ca and Mg ions). It was revealed that on three Middle Ural ash dumps (composed of fly ash from various brown coals) over 50–60 years, forest communities spontaneously formed according to the zonal type (with the dominance of Betula pendula Roth and Populus tremula L.) with poorly differentiated young soils—technosols. For the first time, as a result of using an integrated approach to assess the direction of forest ecosystem formation on fly ash dumps, a tendency to increase carbon stocks in technogenic soils that have not reached the level of zonal soils was revealed, as well as the dependence of C accumulation on some physico-chemical characteristics of ash was established. Carbon stocks in Technosols are on average equal to 44 t/ha but vary significantly. It was shown that there is a medium negative relationship between the content and stocks of organic carbon in soils formed on a technogenic substrate and the content of mobile phosphorus compounds in them (the correlation coefficient is −0.58 and −0.53, respectively). The average carbon stocks in the litter of technosols, which is the main source of organic carbon in forest soils, are 3.2 t/ha. It was revealed that the carbon stocks in the litter are most influenced by the content of exchangeable calcium cations and magnesium in it (the correlation coefficients are −0.68 and −0.69, respectively). Any correlation between the studied litter parameters and carbon accumulation in the soils of ash dumps was found. The study revealed that the carbon stocks in the technosols of ash dump forest communities are two times less than the carbon stocks in the zonal forest soils of the Middle Ural southern taiga. The stocks of this element in the litter of young soils are equal to 1/3 of the litter of zonal soils. The composition of the humus substance system formed in the soils of forest areas of ash dumps and zonal soils is similar. The results of this study can serve to fill gaps in the knowledge about carbon sequestration by soils and aim to draw attention to forest communities of technogenic ecosystems to consider the contribution of their components to carbon sequestration. Full article

The discharge of raw industrial wastewater (IWW) into ecosystems is a major environmental problem that adversely affects water quality, soil physicochemical properties, the food chain and, therefore, human health. Injection of treated IWW into irrigation and “fertigation” systems is an ecological, sustainable and economical approach for its appropriate disposal. Seedlings of two forest species (Salix alba, Casuarina glauca) were grown hydroponically and subjected to 25% diluted IWW and control (tap water) treatments for 35 days. Morphological and physiological traits were evaluated, including leaf symptoms, stem and root dry masses, leaf water potential, relative water content, chlorophyll content, photosystem II efficiency, hydrogen peroxide, thiobarbituric acid reactive substances, bioaccumulation and translocation factor estimates and removal efficiency for various heavy metals. Application of 25% IWW stress affected many aspects of plant morphology: chlorosis and necrosis in leaves, epinasty, leaf curling, early leaf senescence and root browning. In both species, the 25% IWW treatment reduced leaf, stem and root dry masses relative to controls. S. alba exhibited greater removal capacity for heavy metal ions and could be effective as a remediator of toxic-metal-polluted industrial effluent water. Full article