Yellow River
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2022 ◽  
Vol 9 ◽  
Zeyu Zhang ◽  
Junrui Chai ◽  
Zhanbin Li ◽  
Li Chen ◽  
Kunxia Yu ◽  

With years of vegetation restoration and check dam construction on the Loess Plateau, the sediment load of the middle reaches of the Yellow River have decreased sharply; however, the effects of check dam on this decrease of sediment load with such extensive vegetation restoration remains unclear. In order to further clarify the effects of check dam on sediment load reduction under vegetation restoration, we calculated vegetation coverage and check dam index based on multi-source remote sensing data, and calculated sediment reduction rate caused by human activities by Mann-Kendall statistical test and double cumulative curve, then established regression equations incorporating the check dam index and the sediment reduction rate using data from different geomorphic regions with different vegetation coverages. The results showed that sediment load in the Hekou-Longmen region and its 17 tributaries decreased significantly every year, and the change in sediment load could be divided into 3 typical periods: the base period (P1), the period mainly impacted by check dam construction (P2) and the period with comprehensive impact of check dam construction and vegetation restoration (P3). Compared with sediment load of the tributaries during P1, the sediment load decreased by 60.96% during P2 and by 91.76% during P3. Compared with the contribution of human activities to the reduction in sediment load in P2, the contribution of human activities in P3 increased significantly, while that of precipitation decreased slightly. The sediment reduction effect of check dams is greater in basins with low vegetation coverage than in basins with high vegetation coverage. There are differences in sediment reduction effect of vegetation restorations in different geomorphic regions, and the effect of vegetation restoration alone have certain upper limits. Such as, the upper limit of sediment reduction rate of vegetation restoration for rivers flowing through the sandstorm region is 47.86%. Hence, only combined the construction of check dam with vegetation restoration can it achieve more significant sediment reduction benefit and control soil erosion more effectively.

Land ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 127
Xu Zhang ◽  
Chunjuan Lyu ◽  
Xiang Fan ◽  
Rutian Bi ◽  
Lu Xia ◽  

China has set up ecological protection and high-quality development of the Yellow River Basin as its national strategy. However, the fragile natural ecosystem and intensive human disturbances pose challenges to it. This study evaluates habitat quality change and analyzes its drivers in a representative county of this region, aiming to provide scientific basis for ecological protection and sustainable development. We took Liulin, a representative county of middle Yellow River Basin as the study area and evaluated the spatiotemporal variation of habitat quality from 2000 to 2020 with the InVEST model. Further, the influencing factors of habitat quality pattern were explored using GeoDetector, and their gradient ranges dominating the habitat quality change were determined by gradient analysis. The results showed that: (1) Areas of low and medium-low habitat quality grades were distributed interactively in the whole county; medium grade areas were scattered in the northeast and southwest parts of the county; and medium-high and high grades area were distributed sporadically along the Yellow River and its branches. (2) Habitat quality of the county almost unchanged from 2000 to 2010. However, from 2010 to 2020, with the rapid expansion of construction land (increased by 9.62 times), the area proportion of medium, medium-high, and high habitat quality grades decreased from 7.01% to 5.31%, while that of low and medium-low habitat quality grades increased from 92.99% to 94.69%. (3) The habitat quality was influenced by multiple natural-human factors. The main influencing factor was land use, followed by elevation. (4) Most changes of habitat quality occurred in areas with lower elevation, gentler slope, and higher vegetation coverage, which were affected by intensive human activities. These results suggest that in future land use policy making and, the construction land expansion in Liulin County should be restricted and differentiated ecological protection and restoration strategies should be implemented in areas with different habitat quality.

2022 ◽  
Vol 9 ◽  
Yinghan Zhao ◽  
Tian Li ◽  
Pengshuai Shao ◽  
Jingkuan Sun ◽  
Wenjing Xu ◽  

Soil microorganisms play the important role in driving biogeochemical cycles. However, it is still unclear on soil microbial community characteristics and microbial driving mechanism in rhizosphere and bulk soils of different halophyte species. In this study, we analyzed bacterial communities in the rhizosphere and bulk soils of three typical halophytes in the Yellow River Delta, i.e., Phragmites communis, Suaeda salsa, and Aeluropus sinensis, by high-throughput sequencing. The contents of total carbon, total nitrogen, and available phosphorus in rhizosphere soils of the three halophytes were significantly higher than those in bulk soils, which suggested a nutrient enrichment effect of the rhizosphere. Rhizosphere soil bacterial α-diversity of P. communis was higher than that in bulk soil, whereas bacterial α-diversity in rhizosphere soil of S. salsa and A. sinensis was lower than those in bulk soil. The dominant bacterial phyla were Proteobacteria, Actinobacteria, Chloroflexi, and Bacteroidetes, which accounted for 31, 20.5, 16.3, and 10.3%, respectively. LDA effect size (LEfSe) analysis showed that the bacterial species with significant differences in expression abundance was obviously different in the rhizosphere and bulk soil of three halophytes. The principal component analysis (PCoA) showed that bacterial community composition was greatly different between rhizosphere and bulk soils of P. communis and S. salsa, while no difference in A. sinensis. Changed bacterial community composition was mainly ascribed to salinity in rhizosphere and bulk soils. Additionally, salinity was positively correlated with Bacteroidetes and negatively correlated with Actinobacteria and Acidobacteria. Our study clarified the variation in bacterial community structure between rhizosphere and bulk soils with soil physicochemical properties, which proved a biological reference to indicate the characteristics of saline and alkaline land.

2022 ◽  
Vol 14 (2) ◽  
pp. 789
Can Yang ◽  
Tianxing Wei ◽  
Yiran Li

The Yellow River Basin (YRB), located in the northern region of China, has a fragile ecological environment. With the construction of urbanization and ecological restoration projects, the YRB LULC has undergone significant change. In this study, we used the coupled Markov-FLUS model by combining natural and social driver factors to predict and simulate the LULC of the YRB in 2030, and then the LULC transfer matrix was used to analyze the characteristics of LULC change in the YRB from 1990 to 2030. The results of the study are as follows. (1) For the simulated result of LULC compared with the same period observed result, the Kappa coefficient is 0.92, indicating the coupled Markov-FLUS model has good applicability in the YRB. (2) The LULC in the YRB shows significant spatial autocorrelation. The cropland is mainly distributed in the eastern region, which is dominated by plain; woodland is mainly distributed in the central region; grassland is mainly distributed in the northern, central, and western region; waterbody is mainly distributed in the western region; built-up land is mainly distributed in the northern, south-central, and eastern region; unused land is mainly distributed in the central, northern, and western region. (3) From 1990 to 2000, the area of cropland transferred in significantly and the area of grassland transferred out significantly; from 2000 to 2015, the area of construction land transferred in significantly and the area of cultivated land transferred out significantly; from 2015 to 2030, the amount of cropland transferred out will be large, and the conversion of each other LULC type will be not significant compared with the previous periods, and the conversion structure of LULC will tend to be stable. This study is a crucial reference value for the high-quality development of the Yellow River Basin.

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