Ecological uniqueness and the determinants in arid desert ecosystems of Northwest China

Ecological uniqueness has important theoretical and practical significance for biodiversity conservation, and it has become a popular research topic in recent years. Species richness and soil nutrients play important roles in ecological uniqueness, but it is still unclear how different life forms, multiple biodiversity attributes, and environmental factors affect ecological uniqueness. In this study, we conducted a community investigation to combine species diversity, functional diversity, phylogenetic diversity, and soil factors to evaluate the impact of biotic and abiotic factors on ecological uniqueness. We verified these different relationships in woody and herbaceous plants. Our results showed that the species contribution to beta diversity (SCBD) of herbaceous plants was higher than that of other species, and SCBD had a strong correlation with species abundance and leaf thickness. Ecological uniqueness can be explained by soil factors and community characteristics, but the relative importance and interpretation of these characteristics differ between communities and between woody and herbaceous plants. Soil factors and community characteristics explained more of the ecological uniqueness in woody plants than herbaceous plants and communities. The community ecological uniqueness was mainly affected by soil pH. Soil moisture content and phylogenetic diversity had extremely significant positive effects on the ecological uniqueness of woody plants, while species richness and functional richness had significant negative effects. pH had a significant positive effect on the ecological uniqueness of herbaceous plants, and soil moisture indirectly affected the herb ecological uniqueness by affecting pH. In brief, the result showed that SCBD is significantly related to plant abundance, functional traits and leaf nutrients. In addition to focusing on sites with high species richness, functional diversity, and phylogenetic diversity, a comprehensive analysis from the perspective of different life forms can fully reflect the ecological uniqueness and proceed with species protection.