The interactions among herbaceous diversity, edaphic factors, and topography under typical afforestation in the transition zone between the qinghai–Tibet Plateau and Loess Plateau

摘要

The herbaceous layer plays a crucial role in afforestation and could provide important information in the process of restoration. Thus, we investigated herbaceous communities (composition and diversity), related factors (soil properties and topography), and their interactions in the afforestation of the ‘Grain-for-Green’ program in the transition zone between the Qinghai–Tibet Plateau and Loess Plateau. We found 52 herb species belonging to 41 genera of 18 families, among which perennial herbs dominated. Our results revealed two different restoration mechanisms for Qinghai spruce (Picea crassifolia) and Prince Rupprecht′ s larch (Larix principisrupprechtii). The community in the Qinghai spruce forest was more competitive and mainly comprised xeric herbs, while the Prince Rupprecht′ s larch forest provided shadier conditions with higher herb diversity. Soil available nitrogen (AN), available potassium (AK), available phosphorus (AP), slope position, and elevation were significant factors affecting herbaceous diversity. The upper slope position should be the primary consideration since topography exacerbated nutrient loss. Soil water remains the underlying factor of succession, and Prince Rupprecht′ s larch on hillslopes might be at risk of water stress in the future. Understanding the significance of the herbaceous layer and environmental factors will provide a comprehensive picture of sustainable management on the alpine Loess Plateau.