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The water use efficiency (WUE) is an essential indicator of carbon–water coupling between terrestrial ecosystems and the atmosphere, and it is an important parameter for studying ecosystem responses to global climate change. A comprehensive understanding of the water–carbon coupling process in the Loess Plateau can reflect the balance between the “...
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... mainly includes Shanxi and Shaanxi, as well as parts of Gansu, Qinghai, Ningxia, and Henan provinces, accounting for 70% of the distribution of loess in the world, and it is the largest loess accumulation area in the world [22]. The total area of the region is 63.5 × 104 km 2 , of which 45.4 × 104 km 2 is a soil erosion area, which is the most serious soil erosion area and the most fragile ecological environment in China and even in the world (Figure 1). The region belongs to a typical arid and semi-arid continental monsoon climate zone with an average annual temperature range of 3.6~14.3 ...
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... The Loess Plateau is located in the north-central region of China, which has the largest loess coverage area in the world [11]. In recent years, due to unreasonable human behavior, such as over-farming and over-grazing, soil and water loss on the Loess Plateau has become increasingly severe, and the environment is relatively fragile [12]. A number of scholars have monitored POPs on the Loess Plateau. ...
The Loess Plateau has been a focus of public discussion and environmental concerns over the past three decades. In this study, in order to investigate the effect of OCP pollution in water of the Beiluo River, concentrations of 25 OCPs at 17 locations in the water were examined. The results showed that the concentration of ∑OCPs in the water ranged from 1.76 to 32.57 ng L−1, with an average concentration of 7.23 ng L−1. Compared with other basins in China and abroad, the OCP content in the Beiluo River was at a medium level. Hexachlorocyclohexane (HCH) pollution in the Beiluo River was mainly from the mixed input of lindane and technical HCHs. Dichlorodiphenyltrichloroethane (DDT) pollution was mainly from the mixed input of technical DDTs and dicofol. Most of the OCP pollution came from historical residues. The risk assessment results showed that hexachlorobenzene (HCB) and endosulfan had high ecological risks in the middle and lower reaches of the Beiluo River. Most residual OCPs were not sufficient to pose carcinogenic and non-carcinogenic health risks to humans. The results of this study can provide a reference for OCP prevention and control and watershed environmental management.
... Since the diffusion resistance of water vapor is greater than that of carbon dioxide [50], when stomatal conductance decreases, the decrease in water vapor escaping from the leaves is less than the decrease in carbon dioxide uptake, leading to an increase in WUE; accordingly, CUE and WUE decrease when stomatal conductance increases [51]. Nonstomatal factors refer to the inhibition of the physiological functions of plants' photosynthetic organs by drought, the decrease in photosynthetic enzyme activity, the decrease in the photosynthetic rate, and the decrease in carbon sequestration capacity, which ultimately affect CUE and WUE [52,53]. ...
The dynamics of plants’ carbon and water use efficiency and their responses to drought are crucial to the sustainable development of arid and semi-arid environments. This study used trend analysis and partial correlation analysis to examine the carbon use efficiency (CUE) and water use efficiency (WUE) of Inner Mongolia’s vegetation from 2001 to 2020. MODIS data for gross primary productivity (GPP), net primary productivity (NPP), potential evapotranspiration (PET), evapotranspiration (ET), drought severity index (DSI), and plant type were used. Altered trends were observed for drought during 2001–2020 in the study area. The results revealed that 98.17% of the research area’s drought trend was from dry to wet and 1.83% was from wet to dry, and the regions with decreased drought regions were broadly dispersed. In 2001–2020, CUE in Inner Mongolia declined by 0.1%·year−1, whereas WUE reduced by 0.008 g C·mm−1·m−2·year−1, but the total change was not significant. CUE decreased from west to east, whereas WUE increased from southwest to northeast. DSI and CUE had the highest negative connection, accounting for 97.96% of the watershed area, and 71.6% passed the significance test. The correlation coefficients of DSI and WUE were spatially opposite to those of CUE and DSI. In total, 54.21% of the vegetation cover exhibited a negative connection with DSI. The CUE and WUE of different vegetation types in Inner Mongolia were negatively correlated with the DSI index except for grasslands (GRA). Drought in Inner Mongolia mostly influenced the CUE of different plant types, which had a higher negative correlation than WUE. The study’s findings can inform climate change research on Inner Mongolia’s carbon and water cycles.
... With the restoration of vegetation in the LP and the implementation of a series of other eco-environmental protection measures, soil erosion in the LP has been weakened [62,63], and sediment input to the Yellow River has been reduced [18], soil erosion has been effectively curbed, and ecosystem services and carrying capacity have been gradually enhanced [24,64]. For example, the monitoring data from the Tongguan hydrological station show that the average annual sand transport of the Yellow River has decreased from 790 million tons in the 1990s to less than 200 million tons in the 2010s [65]. ...
Vegetation change and ecological quality of the Loess Plateau (LP) are directly related to ecological protection and high-quality development of the Yellow River Basin. Based on LP ecological zoning and multisource remote sensing data, we analyzed vegetation change and its relationship with climate, terrestrial water storage (TWS), and land use/cover change from 2000 to 2020, using the normalized difference vegetation index (NDVI), fraction of vegetation cover (FVC), and net primary productivity (NPP). And ecological environmental quality was evaluated based on the remote sensing ecological index (RSEI). The results showed that the spatial distribution pattern of NDVI, FVC and NPP decreased from southeast to northwest in the LP as a whole. Vegetation in the LP recovered significantly, and NDVI, FVC, and NPP showed significant increases of 35.66%, 34%, and 54.69%, respectively. The average NDVI and FVC in the earth–rocky mountainous region and river valley plain region (Area D) were the highest, but the growth rate was the slowest. The average NDVI, FVC, and growth rates in the loess hilly and gully regions (Area B) were slightly higher than those in the loess sorghum gully region (Area A). The average NDVI, FVC, and NPP in the sandy land and agricultural irrigation regions (Area C) were the lowest but showed significant increase. RSEI in most LP areas changed from poor to medium, increasing by 43.45%. Precipitation is the basic factor affecting vegetation cover pattern, with the increase (40.79 mm/10a) promoting vegetation restoration in the LP. Vegetation restoration lost much TWS (−0.6 mm/month), and Area D had the highest average NDVI, FVC, and NPP but the largest TWS loss. Anthropogenic land use/cover change (LUCC) (decrease in cultivated land and unused land; increase in forest, grassland, and construction land) is the primary factor affecting LP vegetation change. This study provides a scientific reference for further vegetation restoration in the LP.
