Long-term effects of vegetation restoration and forest management on carbon pools and nutrient storages in northeastern Loess Plateau, China.

It is crucial for understanding the variations of carbon and nutrient pools within the ecosystems during long-term vegetation restoration to accurately assess the effects of different ecological restoration patterns. However, the long-term spatio-temporal variations of carbon and nutrient pools under different vegetation types remain unclear. The sites for long-term natural and planted forests (i.e., Natural secondary forest, Pinus tabulaeformis planted forest, Platycladus orientalis planted forest, and Robinia pseudoacacia planted forest) on the northeastern Loess Plateau, China were selected, to measure and analyze the differences and interannual variations of vegetation attributes at four synusiae and soil properties at 0-100 cm over the period of 12 years (2006-2017). The principal component analysis (PCA) and Mantel test were also conducted to explore the relationships among vegetation attributes, soil properties, and carbon and nutrient pools. The results showed that: compared with the planted forests, the natural secondary forest had lower arborous biomass (84.21 ± 1.53 t hm-2) and higher understory biomass and plant heights. Compared to planted forests, the secondary forest had higher soil carbon and nitrogen contents (13.74 ± 3.50 g kg-1 and 1.16 ± 0.34 g kg-1). The soil carbon pool in the secondary forest was 22.0% higher than planted forests, while the vegetation carbon pool in the P. tabulaeformis was 75.5% higher than other forests. Principal component analysis (PCA) and Mantel test revealed that vegetation attributes and soil properties had significant correlations with carbon and nutrient pools, especially at the arborous synusia (p < 0.01). The findings indicated that in the ecologically fragile Loess Plateau region, the selection of appropriate vegetation restoration types should be guided by varying ecological restoration goals and benefits, aiming to expected ecological outcomes. This insight offers a strategic implication for forest management that is tailored to improve carbon and nutrient pools in areas with similar environmental conditions.

The coupling interaction of soil organic carbon stock and water storage after vegetation restoration on the Loess Plateau, China.

Vegetation restoration may increase the soil organic carbon stock (SOCS) but decrease the soil water storage (SWS) of terrestrial ecosystems in arid and semiarid regions. To guarantee the sustainability of restoration, it is critical to evaluate the coupling interaction of SOCS and SWS. Here, we examined the spatial distributions of SOCS and SWS across a 0-200 cm soil profile in a grassland, forestland and shrubland on the Loess Plateau and determined the driving factors that affected their variations. Our results showed that SOCS and SWS varied across the 0-200 cm soil profile and considerably accumulated in the deep soil layers (100-200 cm). In comparison to SOCS, SWS generally had higher relative benefits in most studied plant communities, which ensured sustainable restoration. In addition, land use played a less important role than local environmental conditions in determining the variations in SOCS and SWS. Specifically, the interaction between SOCS and SWS was mainly strong in the surface soil layers (0-20 cm). Topography was a predominant factor that affected SOCS and SWS in the deep soil layers (100-200 cm), while soil texture was a stable driving factor influencing their variations across the whole soil profile (0-200 cm). Given the low moisture consumption of grasslands and the lowest root mean square deviation (RMSD) of Hippophae rhamnoides, we proposed an advanced scenario for ecological restoration on the Loess Plateau: establishing reasonably large Hippophae rhamnoides patches with fewer edges in a contiguous grassland matrix. Furthermore, this scenario should be tailored to local environmental conditions, such as soil water, texture and topography, followed by natural vegetation succession.

Gentle or rude? A study on China's publicity of epidemic prevention and governance of urban and rural areas based on anti-epidemic slogans.

COVID-19 has swept through the world, challenging countries' ability to respond to crises and their public governance. One of the difficulties of public governance in China is the knowledge gap caused by the urban-rural dual structure. This study takes anti-epidemic slogans in China, a traditional means of information governance as its research object in the context of COVID-19. Independent sample tests and cluster analysis were conducted to measure the knowledge gap between urban and rural residents in acquiring epidemic information, and compare the different slogans posted in urban and rural areas, as well as the feedback they received. Based on this, the study explores the different logic of urban and rural governance in China. The results show that, although slogans cannot convey the latest information, they can make the public aware of the severity of the epidemic. Urban residents were found to give lower evaluations to slogans, although they acknowledged that slogans had the effect of rendering an anti-epidemic atmosphere, whereas rural residents were more accepting of rude and threatening slogans and control measures. Slogans with scientific guidance were more likely to trigger changes in their awareness and behavior. The study is significant as it can be a reference for other regions' and countries' publicity work and governance approaches in the prevention and control of infectious diseases.

Evolution patterns and spatial sources of water and sediment discharge over the last 70 years in the Yellow River, China: A case study in the Ningxia Reach.

The hydrology and sediment processes in large rivers play important roles in maintaining aquatic and coastal ecosystems and advancing civilization and production in human systems. Therefore, quantitatively analyzing the spatiotemporal variability and dynamics of water and sediment discharge in large rivers is essential for improving watershed management and sustainable development in the areas surrounding rivers, especially the Yellow River, which is one of the most sediment-laden rivers in the world. In this study, we analyzed the evolution patterns and spatial sources of water and sediment discharge in the Yellow River from 1951 to 2020 and determined the impacts of different factors on water and sediment discharge variations. The results showed that the annual water and sediment discharge significantly decreased (p < 0.05) over the past 70 years, with an abrupt change occurring in 1986. The first dominant periodicity of water discharge was approximately 29 years, while the first dominant periodicity of sediment discharge was approximately 28 years. In terms of the water and sediment discharge sources, the dominant factor affecting variations in water discharge was water diversion from 1951 to 2020, while the dominant factor affecting variations in sediment discharge was sediment aggradation from 1951 to 1985 and changed to tributary inflow sediment from 1986 to 2020. In addition, the water and sediment discharge changes were also affected by anthropogenic activities, such as water and sediment diversions, dams and reservoirs, and water and soil conservation measures. In particular, the water and sediment interception capabilities of the established soil and water conservation measures gradually became saturated over time. Specifically, the maximum water and sediment interception capabilities of the current soil and water conservation measures were 12.2 billion m3 and 1.9 Gt, respectively. Overall, the results of the present study can help tailor water and sediment regulation countermeasures in the future.

[High-throughput Sequencing Analysis of Soil Bacterial Community in the Grain for Green Project Areas of the Loess Plateau].

This study analyzed the characteristics of the soil bacterial community under different types of vegetation restoration, and explored the role of microorganisms in the vegetation restoration process, within the soil ecosystem of Grain for Green areas of the Loess Plateau. Typical artificial forest (artificial Robinia pseudoacacia forest, Pinus tabulaeformis forest), natural secondary forest, and grassland were selected as the research objects. High-throughput sequencing technology was used to analyze the α diversity and community structure of soil bacteria, and the correlation between soil environmental factors and bacterial communities. The Chinese National Ecosystem Research Network in Jixian County Station was chosen as the research area. The results showed that the bacterial communities of the five types of forest restoration comprised 25 phyla, 66 classes, 129 orders, 240 families, 392 genera, 760 species, and 2213 OTUs. There were significant differences in the abundance of bacterial communities, which could be ranked as follows: CD > CSL > CH2 > CH1 > YS. The dominant bacteria phyla in the different vegetation restoration types were Actinobacteria, Proteobacteria, Acidobacteria, and Chloroflexi. The relative abundances of natural secondary forest, grassland, and plantation were different, but not significantly. The relative abundances of α-Proteobacteria, ß-Proteobacteria, and δ-Proteobacteria were higher in natural secondary forest soilthan in the soil of the other four restoration models, and the relative abundance was the lowest in grassland soil. The dominant bacteria were significantly correlated with soil pH and TN. Among them, TN was significantly positively correlated with Actinobacteria, pH was significantly positively correlated with Proteobacteria and negatively correlated with Actinobacteria, while Acidobacteria was significantly negatively correlated with soil pH and TN. PICRUSt analysis showed that the functional gene families were mainly related to 24 sub-functions, including cell motility, signal transduction mechanisms, amino acid transport and metabolism, as well as coenzyme transport and metabolism. These results can provide a good foundation for the evaluation of vegetation restoration in the Loess Plateau, as well as a scientific basis for the rational management of plantations.

Don't judge toxic weeds on whether they are native but on their ecological effects.

The sharp rise in anthropogenic activities and climate change has caused the extensive degradation of grasslands worldwide, jeopardizing ecosystem function, and threatening human well-being. Toxic weeds have been constantly spreading in recent decades; indeed, their occurrence is considered to provide an early sign of land degeneration. Policymakers and scientific researchers often focus on the negative effects of toxic weeds, such as how they inhibit forage growth, kill livestock, and cause economic losses. However, toxic weeds can have several potentially positive ecological impacts on grasslands, such as promoting soil and water conservation, improving nutrient cycling and biodiversity conservation, and protecting pastures from excessive damage by livestock. We reviewed the literature to detail the adaptive mechanisms underlying toxic weeds and to provide new insight into their roles in degraded grassland ecosystems. The findings highlight that the establishment of toxic weeds may provide a self-protective strategy of degenerated pastures that do not require special interventions. Consequently, policymakers, managers, and other personnel responsible for managing grasslands need to take appropriate actions to assess the long-term trade-offs between the development of animal husbandry and the maintenance of ecological services provided by grasslands.

[Effects of forest vegetation on runoff and sediment production on sloping lands of Loess area].

Based on the 1985 - 2003 fixed-position data in 9 runoff plots of Caijiachuan watershed in the Jixian county of Shanxi Province in loess area, this paper discussed the relationships between vegetation and runoff and sediment production on sloping lands of loess area. The results showed that natural-secondary forest had better function in soil and water conservation than artifical Robinia pseudoacacia forest, with runoff and sediment produced 65% - 82% and 23% - 92%, respectively. Multiple regression analysis indicated that runoff and sediment production had a significant correlation with rainfall and its intensity, but this relationship was decreased gradually with increasing canopy density. Different land-use type had different runoff and sediment production, e. g., Ostryopsis davidiana and natural-secondary forests had the least runoff and sediment production, artificial Robinia pseudoacacia and Pinus tabulaeformis forests had 5 folds of it as much as Ostryopsis davidiana forest, mixed apple trees and crops had 17.14 and 3.96 folds of it than Ostryopsis davidiana forest, respectively, while high-standard soil preparation could decrease the production obviously. Gray correlation analysis suggested that the stand canopy density and the biomass of herb and litter were the most important factors affecting the runoff and sediment production on sloping land, whose gray correlation degrees all exceeded 0.6. Mixed forest with multi-layer stand structure and shrub forest should be developed in vegetation re-construction of loess area, which could help to increase the coverage and litter thickness to dramatically decrease the runoff and sediment production on sloping land.