In the context of global climate change, desertification, primarily due to perturbations in hydrological factors, has become a salient environmental risk affecting sandy grasslands [1]. Desertification and soil degradation severely reduce potential productivity of land and lead to degradation of ecosystems and their associated ecosystem services[2, 3]. In 2019, China conducted the sixth nationwide survey on land desertification. As of that year, the area of desertified land in China was 2,573,700 km2 and the area of sanded land was 1,687,800 km2. The average vegetation cover of sanded land was 20.22%, and the sanded land with vegetation cover exceeding 40% had significantly expanded. The report demonstrated the urgent necessity of managing sanded land sustainably and over long term time scales.
Desertification begins with blowouts which also signal the beginning of fixed dune formation. Local, regional and global studies have described spatial alterations[4], morphological features[5, 6] and evolution[7, 8] of blowouts. Much international research has focused on coastal blowouts [9]. Chinese scholars have described coastal blowouts around Haidan Island, Fujian Province[10] but have primarily focused on blowouts affecting continental sandy grasslands[11].
Some scholars use Fragstats software to select landscape pattern indices relevant to ecology in order to derive changes in the spatial distribution of blowouts. Huercha used ALOS satellite remote sensing and field survey data to construct 12 landscape indices entered into Fragstats to show that that sandy grassland blowouts around Hunshandak occurred over a broadly distributed but locally clustered area[12]. A study of blowouts affecting the northern edge of the Taklamakan Desert using six indicators, including the number of patches (NP), patch density (PD) in the patch type index and landscape level index, found that blowouts in initial stages of development occupied small localized areas but added up to a large number of patches[13]. The studies described above only considered changes in blowouts over relatively short timescales. Few studies have considered large scale or long term morphological changes in blowouts. Continued research has found that airflow is the main factor affecting blowout occurrence and development. Recent research has focused on combining high-resolution remote sensing image data with wind tunnel test data, numerical simulations, modelling and other pertinent methods[14–16]. Du Huishi and other scholars for example used surface numerical simulation, cellular automata (CA), gray prediction, Markov chain methods, FLUS and other models in their "Land-cover landscape changes of blowout distribution in the Hulun Buir grassland" to predict blowouts from 2012 to 2022[17].
One of four major grasslands in China, the Xilingol grassland represents a typical arid to semi-arid pastoral area and forms a critical ecological barrier around the Beijing-Tianjin and northern regions of China[18]. In recent years, development, over-utilisation of mineral resources and increasingly arid conditions associated with global climate change have severely disturbed the Xilingol grassland through desertification[19] evident as blowouts or increases in grassland sand.
The present research sought to clarify the spatial distribution and evolution of blowouts around Xilingol grassland over a broad area and on decadal timescales. Longer term time series and high-resolution remote sensing image data showing morphological aspects of blowouts served as inputs to a classic ecological landscape analysis approach, the Landscape Pattern Index Method. Combined with FLUS modelling, this method was used to analyze and predict spatial patterns in blowouts and landscape changes affecting Xilingol sandy grassland over the last 60 years. Results enhance understanding of blowout management efficacy and sustainable use of grassland resources.