Spatiotemporal Variation of Vegetation Coverage and Its Response to Climate Factors and Human Activities in Arid and Semi-Arid Areas: Case Study of the Otindag Sandy Land in China

Vegetation coverage is a key variable in terrestrial ecosystem monitoring and climate change research and is closely related to soil erosion and land desertification. In this article, we aimed to resolve two key scientific issues: (1) quantifying the spatial-temporal vegetation dynamics in the Otindag Sandy Land (OSL); and (2) identifying the relative importance of climate factors and human activities in impacting vegetation dynamics. Based on correlation analysis, simple regression analysis, and the partial derivative formula method, we examined the spatiotemporal variation of vegetation coverage in the OSL, belonging to the arid and semiarid region of northern China, and their interaction with climate-human factors. The results showed that the vegetation coverage of the area showed a downward trend with a rate of −0.0006/a during 2001–2017, and gradually decreased from east to west. Precipitation was the main climate factor controlling the overall distribution pattern of vegetation coverage, while the human factors had a more severe impact on the vegetation coverage than the climate factors in such a short period, and the overall impact was negative. Among the human factors, population pressure, urbanization, industrialization, pastoral production activities, and residents’ lifestyles had a negative impact. However, ecological restoration polices alleviated the contradiction between human development and vegetation deterioration. The results of this article provide a scientific basis for restoring grassland systems in arid and semi-arid areas

Dynamic changes of blowout in the fixed dune on the southeastern fringe of Otindag sandy land in recent decade

<p> Desertification is one of the main environmental problems in arid and semi-arid areas. In Otindag sandy land, the activation of fixed sand dunes caused by climate change and human activities is the main reason of the development of desertification, and the activation of fixed sand dunes is first manifested by the formation and evolution of blowouts. In recent years, with the increase of high-resolution image data, it has become possible to make use of dynamic monitoring of terrain and landscape changes in small areas, so as to accurately analyze the interaction between terrains and influencing factors on smaller landscape scales, especially dune-interdune scale. We use the high-resolution satellite image data in 2010, 2013, 2016 and 2019 with the ground survey data as the data source, as well as the ArcGIS software to adopt the visual interpretation method. According to the different developmental positions, the shapes of the blowouts can be divided into saucer, bowl, groove, dustpan and irregular shaped. In the study area, the ways of changes in blowout are mainly based on expansion and amalgamation between 2010 and 2019. The area of blowout increased by 6.47hm<sup>2</sup> from 2010 to 2013. During 2013-2016, the area increased by 4.89hm<sup>2</sup>, following by the next three years, it continued growing by 3.04hm<sup>2</sup>. With little disturbance of human activity, the growth of blowouts in this area is largely affected by the change of climate factors. As the dynamic factor of blowouts, the reduction in sand drift potential, only decreases the development rate and slows down the process. The shapes of the blowout themselves also work as the main influencing factor.</p>