Biological crust in sand and dust storm source areas of Asia and its impact on dust emission

Even though the biological crusts are critical to dust emissions, no sand and dust forecast model have considered the impacts of the biological crust in dust emission scheme. This situation mainly comes from two scientific difficulties: there is no large scale regional biological crust data available that can be used in the forecast model; there is no quantification of how biological crusts impact on sand emission. In this way, we studied the distribution of biological soil crust in sand and dust storm source areas of Central and East Asia using Moderate Resolution Imaging Spectroradiometer satellite surface reflectance data collected in 2000-2019 to determine its potential impact on dust emission according to two empirical schemes. We further evaluated the relationships between soil crust coverage, roughness length, and dust emission to study SDS source areas. We found that biological crust is widely distributed in SDS source areas of Central and East Asia, with coverage rates of 19.8% in Central Asian deserts, 23.1% in the Gobi Desert, and 17.3%-32.8% in Chinese deserts (p > 0.05). Cyanobacteria and lichen coverage has increased in Chinese deserts, reflecting the recent impacts of the Project of Returning Farmland to Grassland and Farmland to Forests. However, biological soil crust coverage has not increased in Central Asian deserts or the Gobi Desert, and that in Central Asian deserts continues to decrease, demonstrating the complexity of the combined effects of human activities and climate change on its distribution. Biological soil crust increased the roughness length of Central and East Asian SDS source areas by 0.14-0.62 mm. The suppression of dust emission due to biological soil crust did not change among years during the study period. The horizontal and vertical dust flux inhibition coefficient (DFIC) were 2.0-11.0 and 1.7-2.9 (p > 0.05), respectively, clearly showing a suppressive effect. Improvement of the ecological environment in some deserts can lead to the ability of these crusts to inhibit dust erosion errors that must be considered in the dust emission scheme for areas where crust coverage has improved.

Automated summary

This study investigated the distribution of biological soil crust in sand and dust storm (SDS) source areas of Central and East Asia, finding varying coverage rates and the ability of biological soil crust to inhibit dust emission by increasing roughness length. The results showed a suppressive effect on dust flux, indicating the importance of considering the impact of biological crust in dust emission schemes in areas where coverage has improved.