Spatial distribution of carbon dynamics and nutrient enrichment capacity in different layers and tree tissues of Castanopsis eyeri natural forest ecosystem

Biomass Production and Carbon Stocks in Poplar-Crop Agroforestry Chronosequence in Subtropical Central China

Agroforest systems have been widely recognized as an integrated approach to sustainable land use for addressing the climate change problem because of their greater potential to sequester atmospheric CO₂ with multiple economic and ecological benefits. However, the nature and extent of the effects of an age-sequence of agroforestry systems on carbon (C) storage remain largely unknown. To reveal the influence of different aged poplar-crop systems on C stocks, we investigated the variation in biomass and C storage under four aged poplar-crop agroforest systems (3-, 9-, 13-, and 17-year-old) in the Henan province of China. The results showed that stand biomass increased with forest age, ranging from 26.9 to 121.6 t/ha in the corresponding four aged poplar-crop systems. The poplar tree biomass accounted for >80% of the total stand biomass in these poplar-crop agroforestry systems, except in the 3-year-old agroforestry system. The average stand productivity peaked in a 9-year-old poplar-crop system (11.8 t/ha/yr), the next was in 13- and 17-year-old agroforestry systems, and the minimum was found in 3-year-old poplar-crop stands (4.8 t/ha/yr). The total C stocks increased, with aging poplar-crop systems ranging from 99.7 to 189.2 t/ha in the studied agroforestry systems. The proportion of C stocks accounted for about 6, 25, and 69% of the total C stocks in the crop, poplar tree, and soil components in all studied agroforestry ecosystems, respectively. Our results suggested that the poplar-crop system, especially in productive and mature stages, is quite an effective agroforestry model to increase the study site's biomass production and C stocks. This study highlighted the importance of agroforestry systems in C storage. It recommended the poplar-crop agroforest ecosystems as a viable option for sustainable production and C mitigation in the central region of China.

Exploring the role of economic and institutional indicators for carbon and GHG emissions: policy-based analysis for OECD countries

Most of the developed countries across the globe have targeted to attain sustainable economic growth. With this focus, the current study evaluated 29 OECD countries over the time period of 1990 to 2018 to analyze the influence of economic and environmental indicators, i.e., export diversification, institutional quality, macrocosmic variables on carbon dioxide, and greenhouse gas emissions. The current study used the quantile regression and generalized method of moments approach on the selected panel. Our comprehensive econometric approach allows us to reveal that export diversification negatively affects carbon emissions but promotes greenhouse gas emissions. Similarly, institutional quality, economic growth, financial development, and economic growth helps to reduce carbon emissions but increase greenhouse emissions. In comparison, trade openness exhibits a positive influence on carbon emissions but a negative on greenhouse gas emissions. Besides, urbanization is found one of the major reasons for environmental degradation. In light of empirical fact findings, this study commends some innovative policy insights for scholars, governors, and policymakers.

Discovering the evolution of Pollution Haven Hypothesis: A literature review and future research agenda

In order to reduce environmental degradation, there has been an increased focus on identifying the main conftributors to environmental degradation and reducing carbon footprints to promote sustainable development. Although the recent focus on institutional and policy reforms has led to a higher focus on environmental discussion, little is known about the status of research on the Pollution Haven Hypothesis (PHH). Hence, the current study evaluates the research dynamics of this field by recognizing most central researchers and key publication outlets from the perspectives of most citations and productivity, research directions, common keywords, countries with the highest academic contribution, and changes in research matrices. Our selection of 494 journal articles from the WOS indicates that King Saud University and the University of Wah were the most productive research institutions, and China was the most productive geographical region. Environmental Science & Pollution Research was identified as the most common outlet for research publications. We also identified strong academic cooperation, notably between China and Pakistan. Moreover, the co-occurrence network identified the Pollution Haven Hypothesis and economic growth nexus, trade, pollution haven and developing economies and FDI, carbon emissions, and pollution haven nexus as the three main prevailing research themes. Lastly, we provide useful policy implications to maximize the impact of environmental reforms and avoid environmental degradation.

An outlook on the development of renewable energy, policy measures to reshape the current energy mix, and how to achieve sustainable economic growth in the post COVID-19 era

Currently, COVID-19 due to emergence of various variants shows no signs of slowing down and has affected every aspect of life with significant negative impact on economic and energy structures around the world. As a result, the governments around the world have introduced policy responses to help businesses and industrial units to overcome the consequences of compliance with COVID-19 strategies. Our analysis indicates that global energy sector is one of the most severely affected industries as energy price mechanisms, energy demand, and energy supply have shown great uncertainty under these unprecedented economic and social changes. In this regard, we provide brief overview of demand, supply, and pricing structure of energy products as well as policy mechanisms to provide better outlook about how industrial sector can cope with energy consumption in the post pandemic era. We further propose changes in the existing policy mechanisms so that transition towards renewable energy sources under different environmental agreements can be achieved. Moreover, as a reference, we outline major challenges and policy recommendations to ease energy transition from fossil fuels to environmental friendly energy mix.

Influence of Intraspecific Competition Stress on Soil Fungal Diversity and Composition in Relation to Tree Growth and Soil Fertility in Sub-Tropical Soils under Chinese Fir Monoculture

Soil microorganisms provide valuable ecosystem services, such as nutrient cycling, soil remediation, and biotic and abiotic stress resistance. There is increasing interest in exploring total belowground biodiversity across ecological scales to understand better how different ecological aspects, such as stand density, soil properties, soil depth, and plant growth parameters, influence belowground communities. In various environments, microbial components of belowground communities, such as soil fungi, respond differently to soil features; however, little is known about their response to standing density and vertical soil profiles in a Chinese fir monoculture plantation. This research examined the assemblage of soil fungal communities in different density stands (high, intermediate, and low) and soil depth profiles (0–20 cm and 20–40 cm). This research also looked into the relationship between soil fungi and tree canopy characteristics (mean tilt angle of the leaf (MTA), leaf area index (LAI), and canopy openness index (DIFN)), and general growth parameters, such as diameter, height, and biomass. The results showed that low-density stand soil had higher fungal alpha diversity than intermediate- and high-density stand soils. Ascomycota, Basidiomycota, Mucromycota, and Mortierellomycota were the most common phyla of the soil fungal communities, in that order. Saitozyma, Penicillium, Umbelopsis, and Talaromyces were the most abundant fungal genera. Stand density composition was the dominant factor in changing fungal community structure compared to soil properties and soil depth profiles. The most significant soil elements in soil fungal community alterations were macronutrients. In addition, the canopy openness index and fungal community structure have a positive association in the low-density stand. Soil biota is a nutrient cycling driver that can promote better plant growth in forest ecosystems by supporting nutrient cycling. Hence, this research will be critical in understanding soil fungal dynamics, improving stand growth and productivity, and improving soil quality in intensively managed Chinese fir plantations.