Vegetation patterns as early warning signals for shifts in ecosystem multifunctionality in the desert-oasis transition zone of China’s drylands

In China's drylands, deserts and areas prone to desertification constitute 44% of the landscape. The desert-oasis transition zone serves as a critical buffer between the desert interior and the oasis, playing an essential role in managing and preventing desertification. Despite its importance, the question of whether ecosystem functions exhibit multistability and experience regime shifts from functional to desertified states remains unresolved, particularly concerning the relationship between changes in vegetation patterns and ecosystem state transitions at the desert edges of arid and hyper-arid regions. In this study, we examined the stability landscapes of ecosystem multifunctionality and vegetation patterns in response to decreasing precipitation at both the inter-desert scale and within individual deserts, as the distance from the oasis to the desert interior increases. We compared the precipitation and distance thresholds for abrupt changes in vegetation pattern indices with those for regime shifts in ecosystem multifunctionality. Our analysis revealed that ecosystem multifunctionality can exist in both functional and desertified states when precipitation ranges between 104.37 mm and 152.56 mm. However, when precipitation drops below 104.37 mm, a complete shift from a functional to a desertified state occurs. The average precipitation threshold for abrupt changes in vegetation pattern indices—such as the size, shape complexity, and connectivity of vegetation patches, flow length, spatial skewness of the landscape, and the power law range, cutoff, and plexpo of the vegetation patch size distribution—is 201.69 ± 34.87 mm, which is higher than the threshold for ecosystem multifunctionality regime shifts. At the scale of individual deserts, changes in vegetation patterns precede regime shifts in ecosystem multifunctionality. These findings suggest that vegetation pattern indices can serve as early warning indicators for desertification in extremely arid desert-oasis transition zones. This study contributes to the enhancement of early-warning systems and supports the monitoring of desertification processes.