ABSTRACT

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 principis-rupprechtii). 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.

摘要

草本层在造林中起着至关重要的作用，并可以在恢复过程中提供重要的信息。因此，我们在青藏高原和黄土高原之间的过渡带中调查了“绿色换粮”计划造林中的草本群落（组成和多样性），相关因素（土壤性质和地形）及其相互作用。 。我们发现52种草本植物属于18个科的41属，其中多年生草本植物占主导地位。我们的研究结果揭示了青海云杉（云杉云杉）和鲁普普雷希特王子的落叶松（Larix principis-rupprechtii）的两种不同修复机制。）。青海云杉林的社区竞争更激烈，主要由旱生草本植物组成，而鲁普普雷希特王子的落叶松林则提供了较黑的条件，具有较高的草本植物多样性。土壤有效氮（AN），有效钾（AK），有效磷（AP），坡位和海拔是影响草本多样性的重要因素。上坡位置应该是主要考虑因素，因为地形会加剧养分流失。土壤水仍然是演替的基本因素，将来鲁珀普里希特王子在山坡上的落叶松可能面临水分胁迫的风险。了解草本层的重要性和环境因素将为高山黄土高原的可持续管理提供一幅全面的图景。