Ecological Problems Research Articles

Moving toward a decolonial and intersectional notion of justice for socio-ecological problems: the urban agroecology of the Buckets Revolution

ABSTRACT This article analyses the Buckets Revolution, an urban agroecological movement in a Brazilian favela that emerged to address waste management issues. We aim to explore the movement’s achievements in promoting socio—cological justice in a vulnerable community of the Global South through agroecology, investigating: i) what socio-ecological problems and intersected demands for justice boosted the emergence of the Buckets Revolution? and ii) what demands for justice the BR has been dealing with to overcome the socio-ecological injustices borne by the Chico Mendes community? We apply the socio-ecological justice model as our theoretical framework, with a decolonial and feminist intersectional approach to embrace the complexity of the case study. The research methods focus on embracing the local reality and the community views, encompassing bibliographical research, a focus group, and semi-structured interviews. The findings reveal that this agroecological movement has effectively addressed organic waste management, food insecurity, and other socio-ecological issues, contributing to socio-ecological justice in the Chico Mendes community. The study emphasizes the importance of considering the a) interconnections of social and ecological problems, b) intersected dimensions of justice, and c) needs and views of the community when developing environmental urban policies to achieve social justice and ecological sustainability.

Predicting the Duration of Forest Fires Using Machine Learning Methods

For thousands of years forest fires played the role of a regulator in the ecosystem. Forest fires contributed to the ecological balance by destroying old and diseased plant material; but in the modern era fires are a major problem that tests the endurance not only of government agencies around the world, but also have an effect on climate change. Forest fires have become more intense, more destructive, and more deadly; these are known as megafires. They can cause major economic and ecological problems, especially in the summer months (dry season). However, humanity has developed a tool that can predict fire events, to detect them in time, but also to predict their duration. This tool is artificial intelligence, specifically, machine learning, which is one part of AI. Consequently, this paper briefly mentions several methods of machine learning as used in predicting forest fires and in early detection, submitting an overall review of current models. Our main overall objective is to venture into a new field: predicting the duration of ongoing forest fires. Our contribution offers a new way to manage forest fires, using accessible open data, available from the Hellenic Fire Service. In particular, we imported over 72,000 data from a 10-year period (2014–2023) using machine learning techniques. The experimental and validation results are more than encouraging, with Random Forest achieving the lowest value for the error range (8–13%), meaning it was 87–92% accurate on the prediction of forest fire duration. Finally, some future directions in which to extend this research are presented.

The improvement of judicial protection of marine environment in China: based on the analysis of 2,443 judicial cases

With the proliferation of human activities, a series of marine ecological and environmental problems have arisen. Judicial application is important to test legislative achievements, explore judicial difficulties, and examine the compliance with the law. There is no case law in China and the impact of judicial decisions on the protection of marine environment is therefore indirect. Judicial decisions can reflect the implementation of the Marine Environmental Protection Law and play a crucial role in improving the marine environmental protection. An analysis of 2,443 cases related to marine environmental protection heard by courts at all levels across China from 1 January 2019 to 31 December 2023 has been conducted. The findings indicate an overall downward trend in cases related to marine environmental protection, suggesting positive governance outcomes to some extent. However, certain problems remain in the judicial protection of marine environment. Therefore, legislative efficiency should be properly increased and an independent crime for marine environmental pollution should be introduced to further clarify the legal bases for marine environmental protection. The intelligent trial assistance technology should also be applied to shorten trial time, improve trial efficiency, and unify judicial rules. The People’s Courts should play an active role in the provision of evidence and specific evidentiary burden provisions for different types of marine environmental pollutions should be proposed. The data sharing channels between various systems should be facilitated and the functionality for case referral should be developed for the coordination of administrative enforcement and criminal justice within a unified administrative enforcement platform.

Effects of Habitat Loss on Tenebrionidae in Gravel–Sand Mulching Areas of Desert Steppe in Ningxia, China

The desert steppe in Ningxia is the largest natural steppe type in the region, characterized by a fragile ecological environment and low carrying capacity. Gravel–sand mulching, a local agricultural practice, involves using a sand and gravel covering layer to maintain soil warmth and moisture. However, this method has led to ecological problems, such as habitat loss and biodiversity loss. Tenebrionidae, one of the most widely distributed beetle families, is commonly used to indicate habitat degradation and is a significant steppe pest in desert steppe areas. This study, conducted in the gravel–sand mulching areas of Shapotou District, Zhongwei City, Ningxia, classified the habitat loss from low to high in these areas into five grades (I-V) and examined the effects of habitat loss on Tenebrionidae. We collected 6565 Tenebrionidae, with Blaps femoralis, Anatolica nureti, and Pterocoma vittata being the dominant species. The findings reveal that habitat loss grade I had the highest abundance, diversity index, and evenness index of Tenebrionidae, significantly higher than those of grades II–IV. Habitat loss had a significant negative effect on Tenebrionidae abundance, a significant positive effect on the richness index, no significant effect on the vegetation diversity index, a significant positive effect on soil available potassium (APP), and a significant negative effect on soil total phosphorus (TP). Redundancy analysis indicated a positive correlation between Tenebrionidae abundance and the vegetation diversity index; a negative correlation between Tenebrionidae richness, the diversity index, and vegetation indices; a positive correlation between Tenebrionidae abundance and soil TP; and a negative correlation between the Tenebrionidae diversity index and soil TP and soil APP. These findings will contribute to biodiversity conservation and ecological restoration and provide a theoretical basis for steppe management, sustainable agricultural development, and pest monitoring in desert steppe environments.

Analysis of ecological environment quality heterogeneity across different landform types in Myanmar and its driving forces

Ecological Environmental Quality (EEQ) assessment is a crucial method for understanding regional ecological conditions and identifying ecological problems. Understanding how EEQ responds to various natural and anthropogenic factors under different landform conditions is extremely important to improve the accuracy and usefulness of the assessment. Landforms, as a key natural geographic element, influence not only the spatial distribution of EEQ, but also the nature and intensity of human activities. However, we lack a comprehensive understanding of how different landform types affect the ecological environment. In this paper, we quantitatively assessed the spatial heterogeneity characteristics of EEQ in Myanmar based on the Remote Sensing Ecological Index (RSEI) model, and used Geodetector to reveal the driving mechanisms of EEQ in terms of the whole region and specific landform types. The results showed that: (1) The overall EEQ in Myanmar showed a fluctuating downward trend from 2000 to 2020, and the spatial heterogeneity is obvious. The plains and hills had poor EEQ, while the mountains, highlands and most of the northern regions have better EEQ. (2) The EEQ of different landform types differed significantly. The EEQ was best in middle relief mountains and poorer in plains and high relief mountains. (3) Land use, human footprint and net primary productivity (NPP) were the main factors affecting EEQ in Myanmar, and there are significant spatial and temporal dynamic interactions between different factors. (4) There were significant differences in the factors affecting EEQ between landform types. For example, EEQ in plains, hills, low relief mountains, and middle relief mountains was influenced by a combination of natural and anthropogenic factors. In contrast, upland mountain areas were mainly influenced by natural factors alone. As the degree of landform fluctuation increases, the influence of each factor generally showed a downward trend. This study reveals the spatio-temporal variation characteristics of Myanmar’s EEQ, key driving factors, and differential response mechanisms of ecological environment evolution under different landform types, and provides a scientific basis for formulating ecosystem protection and restoration strategies based on local conditions.

Joint guarantee rate index assessment of the contribution of agricultural water-saving measures to river ecological flow in water shortage areas

Reconciling higher ecological water demands and economic purposes with finite freshwater resources remains one of the great management dilemmas. Low water efficiency and large water consumption in agricultural irrigation hinder the protection of river ecological flow in the water shortage areas of Northwest China. By analyzing the surplus and shortage of river ecological protection targets, the intensity guarantee rate index is innovatively proposed to quantitatively evaluate the important contribution of improved water-saving measures for river flow restoration. It compensates for the shortcomings of the duration guarantee rate index in evaluation that may mask ecological problems. Considering ecological baseflow, fish species, and landscape water demand, the ecological flow interval (6.00–12.42 m3/s) was determined. Three scenarios are highlighted for different typical years and irrigation regimes in combination with planting structure adjustment and irrigation water utilization coefficient. In 75 %, 90 %, and 95 % typical years, the maximum total annual water-savings (Scenario 3) are 57.3, 57.1, and 87.2 million m3 (sufficient irrigation); 32.2, 33.9, and 35.5 million m3 (deficit irrigation) respectively. The guarantee degree of river ecological flow under both irrigation regimes increased from the previous 65.6 % to a maximum of 91.7 % and 81.2 %. The increase in the daily guarantee rate and decrease in the intensity guarantee rate under the aforementioned three scenarios indicate a reduction of damage depth and duration of ecological flow. By using a quantitative study, it is pointed out that improving agricultural water-saving is a reasonable and necessary way to protect the river flow.

A novel green approach for reactive printing of cotton/cellulosic regenerated blended fabrics using trisodium nitrilotriacetate

Owing to their comfort, handle, and aesthetic characteristics, cotton fabrics will always be the first and primary choice for clothing and apparel. In recent years, regenerated cellulosic fabrics like bamboo, Tencel, and modal fabrics have had many natural advantages. Fabrics based on blending cotton fibres with regenerated cellulosic fibres are considered promising products in textile industry sectors. Use of urea poses ecological problems associated with the high nitrogen content of the printing effluent. Therefore, urea reduction or elimination in reactive dye print pastes is of ecological interest. We report the use of trisodium nitrilotriacetate as a complete substitution of urea and alkali in the conventional reactive printing of cotton/cellulosic regenerated blended fabrics. CI Reactive Black 5 was selected for the present study. Three different print pastes containing urea/alkali, trisodium nitrilotriacetate/alkali and trisodium nitrilotriacetate without alkali were thoroughly investigated. Different factors that may affect the printability of cotton/cellulosic regenerated blended fabrics, such as the concentrations of dye, trisodium nitrilotriacetate, urea, absence or presence of alkali and steaming time in the prints obtained, were evaluated concerning colour strength, dye fixation, dye penetration, levelling, colure, and fastness properties. All printed fabrics using three print pastes obtained excellent to good fastness. The results proved the viability of using TNA as an environmentally friendly approach for urea/alkali-free printing of cellulosics with reactive dyes.

Emerging pollutants: Risks in salmon fish migration. A review

The release of pollutants into the environment is a serious ecological problem due to the significant risks they pose both to ecosystems and to human health. The review considers the issues of detection and distribution of new pollutants, as well as sources of their entry into the environment and potential impact on ecosystems. The problem of wastewater pollution is especially urgent in the context of conservation of salmonid fish species. Pharmaceutical and veterinary drugs, components of personal hygiene products, microplastics, per- and polyfluorinated substances, brominated flame retardants, oil and a number of other toxicants enter freshwater bodies, which are especially important for the early stages of the salmon development and its following migration. The presence of pollutants in the aquatic environment depends on a source, their ability to bioaccumulate, as well as to degrade in the processes of biological and abiotic purification. High-resolution mass spectrometry in combination with gas or liquid chromatography can be recommended for detection of new pollutants. Due to high mass measurement accuracy and high specificity, this method is able to effectively identify pollutants even in the complex fish matrix. When conducting non-targeted and targeted screening with highly sensitive full scanning, it is advisable to use high-resolution mass analyzers (TOF, Q-TOF, Q-Orbitrap), which allow determining a number of new compounds. A promising direction in the complex assessment of the impact of pollutants on salmon fish species and the identification of indicators characterizing this impact is metabolomics. It is based on the study of low-molecular organic compounds — metabolites, both intermediate and final metabolic products in body fluids and tissues. Metabolomic profiling allows identifying important markers of the state of a water body under the influence of pollutants, which is necessary for the development of comprehensive regulations and guidelines for the effective handling of these pollutants.

Adaptive divergence in reproductive seasonality and underlying physiological features fit Rattus norvegicus to live as opportunistic breeders.

How organisms respond to complex environments is one of the unsolved problems in ecology. Life history patterns of a species provide essential information on how different populations may respond and adapt to environmental changes. Compared to typical seasonal breeders, which have limited distributions, the worldwide distribution of brown rats (Rattus norvegicus) across highly complex and divergent habitats suggests they exhibit exceptional adaptiveness. However, the difference in physiological mechanisms by which brown rats respond and adapt to markedly different environments is seldom investigated. Here, we reveal a significant divergence in reproductive seasonality and environmental responses between two brown rat subspecies: one subspecies, R. n. caraco, lives in the temperate zone, and another subspecies, R. n. norvegicus, lives in the subtropical region. Although R. n. caraco displayed a significantly higher reproductive seasonality than R. n. norvegicus, both subspecies adapted to sub-optimal breeding conditions mainly by regulating the seminal vesicle rather than testis development. Especially in responding to severe winter conditions in high-latitude regions, bodyweight-dependent recovery of testicular development in adults enables R. n. caraco to initiate reproduction more rapidly when conditions are suited. These findings elucidate a regulatory process of how brown rats live as opportunistic breeders by benefiting from enhanced semen production.

Possibilities of Using Environmental Knowledge in the Process of Environmental Protection

Abstract In the globalising world, scientific and technical progress, increase in production areas, industrial and economic development have positively affected society and human life, but have caused serious deterioration of the ecological balance. Every person working in any field should have ecological culture and ecological knowledge. Since chemistry is mostly related to ecology among the subjects taught, the role of chemical production and anthropogenic effects in disrupting the ecological balance is great. In chemistry teaching, importance should be given to providing students with the necessary knowledge and skills about the source of environmental problems, environmental concepts, causes of problems and ways to eliminate them.

Interannual moisture variability on the Qinghai Plateau: Trends, patterns, and implications

Investigating surface dry-wet patterns on the Qinghai Plateau (QP) is crucial for water allocation, ecological sustainability, and climate variability adaptation strategies. Existing discrepancies in the QP dry-wet trends and distribution characteristics underscored the need for a more refined analysis. This study utilized the Thornthwaite Moisture Index (IM) to quantify changes in surface dryness and wetness under prevailing climatic conditions. Linear trend regression and ensemble empirical mode decomposition (EEMD) were applied to study the dynamic and periodic characteristics of the QP from 1980 to 2018.Our findings revealed a decrease from southeast to northwest in IM, with the semi-arid and sub-humid transition line aligning closely with the 400 mm isohyet. The dry-wet transition line exhibited a northwestward trend over the past four decades. Possibly influenced by monsoon circulation and El Niño-Southern Oscillation (ENSO), the annual IM displayed a quasi-cycle of 3 to 5 years, manifested by a dry period (1990–2004) and a wet period (2005–2012). However, spatial differences existed, challenging the universality of the “Dry gets Drier and Wet gets Wetter (DDWW)” pattern. Precipitation (PRCP) changes could predict over 90 % of IM spatiotemporal variations. Additionally, the IM response to Average Temperature (TAVG) exhibited an inverted U-shaped curve, with a boundary (−3.8 °C) below which cooler regions became wetter and above which they became drier. The observed warming and precipitation shifts suggested that continued warming could lead to warmer and wetter climates, potentially causing ecological and environmental problems. Therefore, examining the surface moisture budget is of critical scientific and practical significance, in order to provide a decision-making basis for mitigating and adapting to climate change.

The use of alternative protein sources in quail diets: A review

The growth of the Earth’s population and people’s striving for healthy life style lead to an increase in the global demand for protein food. Quails are a valuable source of protein, which is thought to reduce the risk of obesity and cardiovascular diseases. Inclusion of alternative protein sources into the composition of feeds for quails is an answer to ecological problems associated with the use of traditional protein sources. Plants, insects, algae and mushrooms are among alternative protein sources that are mentioned most frequently in scientific studies. The aim of this review is analysis of scientific literature dedicated to the use of plants, insects, algae and mushrooms as alternative protein sources in feedstuff for quails. Plant sources of protein, such as soya and maize, are successfully used in feedstuff production. However, studies have shown that addition of other sources, including by-products of crop husbandry, will allow increasing sustainability and reducing the dependence of the industry on traditional raw materials. Flour from black soldier fly (Hermetia illucens) larvae is the promising and most widely studied source of protein among insects and can positively affect productivity and health of quails. Among algae, it is necessary to mention spirulina (Spirulina platensis and Arthrospira platensis). Upon addition of 4% of the spirullina powder, productivity parameters in poultry increased. Mushrooms are described as a promising protein source in feedstuff that is also capable of ensuring an increase in productivity and quality of poultry meat. Today, however, there are few studies on this subject. It is recommended to focus further studies of the application of alternative protein sources in quail diets on questions of safety of their use and more detailed analysis of economic feasibility.

Regeneration design of mining brownfield based on nature-based solutions

AbstractMining industry once was a strong contributor to the economic development of cities and created economic benefits for human beings, but ecological problems are increasing day by day. This study takes the quarry in Nagykovacsi, Hungary as an example, and through comprehensive evaluation of the site, utilizes nature-based solutions to carry out the design practice of seeking new development vitality and opportunities for the brownfield site after mining. Finally, it summarizes the ecological remediation concepts and strategies suitable for mining brownfield sites, and contributes to the reuse of urban land space and the creation of a favourable ecological environment.

Determinants of energy conservation behaviour in small hospitality firms: application of the extended value belief norm theory

The study aims to investigate the energy conservation behaviour of owners and managers of small hospitality firms by incorporating social norms into an extended Value-Belief-Norm (VBN) model. In addition, the study examines the mediating effects of causal chain of the VBN model in the context of energy conservation behaviour. The world faces serious environmental challenges such as loss of biodiversity, pollution, depletion of natural resources and global warming. One of the causes of these environmental challenges is the production and consumption of energy by households and firms. The hospitality sector uses a significant amount of energy in its operation leading to negative environmental impacts. Reducing energy use will improve environmental and financial sustainability of hospitality firms. Energy conservation behaviour is one of the significant ways to reduce energy consumption. The study adopts the survey method for data collection and the respondents are conveniently sampled. The Partial Least Square Structural Equation Modelling is used for data analysis. Based on a dataset of 360 respondents, the study finds that the extended VBM model that includes social norms is applicable in explaining the energy conservation behaviour of owners/managers of small hospitality firms. The mediating effects of the causal chain of the VBN model are significant. The theoretical implication is the applicability of an extended VBN model that includes social norms to predict energy conservation behaviour. Recommendations on how to improve energy conservation behaviour include improving the level of awareness of ecological problems caused by energy consumption. The study aims to investigate the energy conservation behaviour of owners and managers of small hospitality firms by incorporating social norms into an extended Value-Belief-Norm (VBN) model. In addition, the study examines the mediating effects of causal chain of the VBN model in the context of energy conservation behaviour. The world faces serious environmental challenges such as loss of biodiversity, pollution, depletion of natural resources and global warming. One of the causes of these environmental challenges is the production and consumption of energy by households and firms. The hospitality sector uses a significant amount of energy in its operation leading to negative environmental impacts. Reducing energy use will improve environmental and financial sustainability of hospitality firms. Energy conservation behaviour is one of the significant ways to reduce energy consumption. The study adopts the survey method for data collection and the respondents are conveniently sampled. The Partial Least Square Structural Equation Modelling is used for data analysis. Based on a dataset of 360 respondents, the study finds that the extended VBM model that includes social norms is applicable in explaining the energy conservation behaviour of owners/managers of small hospitality firms. The mediating effects of the causal chain of the VBN model are significant. The theoretical implication is the applicability of an extended VBN model that includes social norms to predict energy conservation behaviour. Recommendations on how to improve energy conservation behaviour include improving the level of awareness of ecological problems caused by energy consumption.

Analysis on Ecological Network Pattern Changes in the Pearl River Delta Forest Urban Agglomeration from 2000 to 2020

The advancement of urbanization has led to a decline in the ecological function and environmental quality of cities, seriously reducing the services and sustainable development capacity of urban ecosystems. The construction of the National Forest Urban Agglomeration of China is conducive to alleviating the ecological and environmental problems brought about by rapid urbanization and promoting sustainable urban development. A time series analysis of ecological network changes can quickly and effectively explore the development and changes of ecological spatial patterns over time. Identifying ecological protection and restoration areas in urban agglomerations is an important way to promote ecosystem restoration and optimize ecological networks. This paper takes the Pearl River Delta forest urban agglomeration as the research area, uses multi-source remote sensing data from 2000 to 2020 (every 5 years), identifies ecological sources based on the morphological spatial pattern analysis (MSPA) method, generates ecological corridors based on the minimum cumulative resistance (MCR) model, constructs a time series ecological network pattern in the Pearl River Delta region, and analyzes the evolution process of the ecological network pattern over time. The results indicate that over time, the core green area in the ecological network pattern of the Pearl River Delta first decreased and then increased, and the complexity of ecological corridors first decreased and then increased. The main reason is that the urbanization process in the early 21st century led to severe ecological fragmentation. Under the promotion of the national forest urban agglomeration construction, the ecological network pattern of the Pearl River Delta was restored in 2015 and 2020. The time series analysis of the ecological network pattern in the Pearl River Delta region of this research confirms the effectiveness of the construction of forest urban agglomerations, providing a scientific reference for the identification of ecological networks and optimization of spatial patterns in forest urban agglomerations.

Occurrence and effect of dwarf mistletoe (Arceuthobium globosum and A. vaginatum) in high-elevation forests in México

Climate change has very important effects on high mountain forests (>3500 masl), which face various ecological problems associated with global change including the proliferation of pests and parasitic plants. These sensitive ecological systems cover approximately 39,000 ha of Mexican territory and occur around some of the highest volcanoes in the country. The objective of this research was to determine the spatial distribution and infestation levels of dwarf mistletoe (Arceuthobium spp.) in the main populations of Pinus hartwegii in five mountains of the Trans-Mexican Volcanic System (Pico de Orizaba, Nevado de Toluca, Cofre de Perote, Nevado de Colima and Monte Tláloc) and identify infestation patterns in relation to the structure of the forest. In the study, 2658 sampling sites (1000 m² each) were installed using the contour lines as access transects to the forest, distributed at every 100 of altitude, between 3500 and 4000 masl. Approximately 32 % of the sampled area had some level of attack by dwarf mistletoe, distributed across all diameter categories of the trees. The infestations affected the establishment of natural regeneration and rates of tree mortality.

Ex vivo and in vitro methods as a platform for studying anthropogenic effects on marine mammals: four challenges and how to meet them

Marine mammals are integral to global biodiversity and marine health through their roles in coastal, benthic, and pelagic ecosystems. Marine mammals face escalating threats from climate change, pollution, and human activities, which perturb their oceanic environment. The diverse biology and extreme adaptations evolved by marine mammals make them important study subjects for understanding anthropogenic pressures on marine ecosystems. However, ethical and logistical constraints restrict the tractability of experimental research with live marine mammals. Additionally, studies on the effects of changing ocean environments are further complicated by intricate gene-environment interactions across populations and species. These obstacles can be overcome with a comprehensive strategy that involves a systems-level approach integrating genotype to phenotype using rigorously defined experimental conditions in vitro and ex vivo. A thorough analysis of the interactions between the genetics of marine mammals and their exposure to anthropogenic pressures will enable robust predictions about how global environmental changes will affect their health and populations. In this perspective, we discuss four challenges of implementing such non-invasive approaches across scientific fields and international borders: 1) practical and ethical limitations of in vivo experimentation with marine mammals, 2) accessibility to relevant tissue samples and cell cultures; 3) open access to harmonized methods and datasets and 4) ethical and equitable research practices. Successful implementation of the proposed approach has the potential impact to inspire new solutions and strategies for marine conservation.

Urban Habitat Quality Enhancement and Optimization under Ecological Network Constraints

The process of urbanization leads to the rapid expansion of construction land and brings a series of ecological and environmental problems. The ecological network, as a linear landscape element, is of great significance to improve the quality of the regional ecological environment. In this study, the Morphological Spatial Pattern Analysis (MSPA) and the model of Minimum Cumulative Resistance (MCR) were used to construct the ecological corridors in the central city of Fuzhou, and the land use pattern under the constraints of the ecological network was simulated and quantified by the patch-level land use simulation (PLUS) tool with the results of the identification of ecological corridors. Meanwhile, with the help of InVEST habitat quality model, the regional habitat quality under different development scenarios was compared. The results show that (1) 19 ecological sources and 35 ecological corridors were identified; (2) under the constraints of ecological corridors, the area of forested land in the study area in 2027 was increased by 1.57% and the area of built-up land was reduced by 0.55% compared with that in 2022; (3) and under the constraints of ecological corridors, the mean value of habitat quality in Fuzhou City improved by 0.0055 and 0.0254 compared with 2022 and 2027 natural evolution scenarios, respectively. The study provides decision-making assistance for the construction of ecological corridors from the perspective of land use planning.

Effects of Microplastics on Soil N2O Emission and Nitrogen Transformations from Tropical Agricultural Soils

A widespread concern had been there regarding soil ecological and environmental problems caused by microplastic pollution in agricultural soils. A controlled laboratory incubation experiment was performed to examine the effects of different types of microplastics on soil properties, N2O emissions, and nitrogen （N） transformations in tropical arable soils from a pepper-corn cropping system in Hainan Province. Three treatments were done： soil without microplastics （CK） and soil amended with 5% of polyethylene （PE） or with 5% of polybutylene adipate co-terephthalate （PBAT）. The results showed that both types of microplastic addition increased soil pH, soil organic carbon （SOC）, and dissolved organic carbon （DOC） contents, with stronger treatment effects observed for PBAT than those for the PE treatment. In addition, the PE and PBAT treatments increased soil ammonium nitrogen （NH4+-N） contents by 66.07% and 119.65% and decreased nitrate nitrogen （NO3--N） contents by 8.56% and 29.68%, respectively. Compared to those in the CK treatment, the addition of PBAT significantly increased soil N2O emissions by 254.92% （P < 0.05）, whereas that of PE produced no significant effects. Furthermore, both the PE and PBAT treatments increased soil net nitrogen mineralization rate （NMR） and decreased soil net nitrification rate （NNR）, with more obvious treatment effects observed in PBAT than in the PE treatment. PBAT addition increased the abundance of ureC, while PE had no significant effects. Microplastic addition reduced the abundance of nitrifying gene abundances （AOA-amoA, AOB-amoA, and nxrA）, with more obvious treatment effects found in the PBAT treatment. Further, PBAT addition significantly increased the gene abundances of nirK, nirS, nosZ, and fungal nirK （P < 0.05）, whereas the addition of PE had no significant effect on those gene abundances. Soil N2O emissions had positive relationships with NH4+-N intensity, pH, DOC, SOC, and nirS abundance. In conclusion, biodegradable microplastics addition produced stronger influences on soil properties and N transformations than the non-biodegradable one in tropical arable soils and aggravated soil N2O emissions mainly by promoting denitrification.

Unveiling the main drivers of tree decline in Zagros semi-arid forests

Abstract Tree decline in arid and semi-arid forest ecosystems causes severe socioeconomic and ecological problems and thus needs to be thoroughly quantified and monitored across space and time. This study investigates tree and forest decline in Iran’s Zagros forests, considering environmental factors (e.g. topographic, soil, and climatic variables). We used field data from Chaharmahal-and-Bakhtiari (a study area covering 165 km2) and environmental data derived from freely available databases. Relationships between tree, forest decline, and environmental data were analyzed using generalized additive models. Our findings reveal that slope and the BioClim-16 variable (precipitation of the wettest quarter) significantly influence tree decline across various decline classes (P-values: slope = .009, BioClim-16 = .02). The best multivariate model for forest decline incorporated soil organic carbon and silt as predictive variables, with soil organic carbon emerging as the key factor (P-value = .04). Additionally, a spectral analysis of bare soil in declining and non-declining areas consistently demonstrated reduced reflectance values in declining regions across 10 Sentinel-2 bands, with VNIR-3, SWIR-2, red, green, and blue bands consistently showing significant differences as unveiled by the Wilcoxon test in all seasons except winter. These reduced reflectance values may indicate that forests stocked on soils with larger grain size (a higher fraction of sand) and/or higher organic carbon content may be more vulnerable to decline. This study contributes to our hitherto understanding of the main drivers of tree and forest decline in semi-arid forests, among others underscoring the potential utility of the spectral properties of bare soil in sparse semi-arid forests to predict the likelihood of tree decline.