Abstract
Aeolian processes in temperate grasslands (TGs) are unique because the plant growth–decay cycle, soil water, and land-use interactions affect the seasonal and inter-annual changes in dust events. Land-use types in Inner Mongolian TGs are unique (settled grazing and grass mowing) compared with those in Mongolian TGs. Since 2003, land use has been controlled by grassland protection legislation, which is intended to prevent desertification and dust storms. In this study, we used process-based ecosystem (DAYCENT) and statistical modeling, along with dust event observations from March to June of 1981–2015, to (1) identify critical land surface factors controlling dust emissions (vegetation components, live grass, standing dead grass, litter, and soil moisture) at typical and desert steppe sites in Inner Mongolia and (2) estimate the impact of controlled land-use legislation on dust events. The DAYCENT model realistically simulated the dynamics of the observed vegetation components and soil moisture in 2005–2015. At both sites, similar significant correlations were obtained between spring dust events and wind speed or a combination of all surface factors that retained anomalies (memory) from the preceding year. Among the surface factors, vegetation was a critical factor that suppressed dust in Inner Mongolian TGs, similar to that in Mongolian TGs. In the desert steppe, standing dead grass had the strongest memory and was significantly correlated with dust events, whereas no significant correlations were observed in the typical steppe. This suggests that, in a typical steppe region, heavy grazing and mowing result in few dead grasses, thereby inhibiting the prevention of dust events. Moreover, the simulations of dust events under controlled (light grazing) and uncontrolled (heavy grazing) land-use conditions demonstrated that the grassland protection legislation reduced the occurrence of dust events in typical and desert steppe sites by 25 and 40%, respectively, since 2003.
Highlights
The arid and semi-arid regions of East Asia, including temperate grasslands (TGs) in Mongolia and Inner Mongolia, are the main source regions of Asian dust (Natsagdorj et al, 2003; Wang et al, 2008; Lee and Sohn, 2011)
The landuse intensity, with moderate grazing throughout the year and mowing during the autumn, and the lower standing dead grass in the spring did not significantly affect dust (Table 2). This suggests that standing dead grass biomass, live grass biomass, and litter grass cover offer different levels of land surface protection with varying efficiencies. These results indicate that the vegetation cover, standing dead grass coverage under low intensity land use, is a critical factor for preventing dust events in Inner Mongolian TGs
We investigated the effects of individual grassland surface factors on the number of dusty days, as well as the impacts of controlled land use under grassland protection legislation on dust events in Inner Mongolian TGs using the DAYCENT ecosystem and statistical models
Summary
The arid and semi-arid regions of East Asia, including temperate grasslands (TGs) in Mongolia and Inner Mongolia, are the main source regions of Asian dust (Natsagdorj et al, 2003; Wang et al, 2008; Lee and Sohn, 2011). Asian dust events influence cloud formation (Huang et al, 2006), precipitation (Creamean et al, 2013), the Earth’s radiation budget (Bat-Oyun et al, 2012), and the global dust cycle (Uno et al, 2009), which affects ecosystems (e.g., land degradation), air pollution (Heft-Neal et al, 2020), and climate (Kok et al, 2018). Strong dust events threaten human and animal health through air pollution and economic losses, and disrupt social and economic activities in both the source and downwind areas (Shao and Dong, 2006; Lee et al, 2014; Kashima et al, 2016). Dust events have become increasingly severe in Mongolian TGs because of the combined effects of climate change and human-induced land degradation (Kurosaki et al, 2011; Nandintsetseg and Shinoda, 2015; Nandintsetseg et al, 2021). In response to increasing food demands, increasing livestock product demands, the grazing management policies in Inner Mongolia have changed since the early 1980s, which has greatly affected the ecological environment (Li et al, 2007)
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