Topography and soil seed banks jointly influence plant diversity across microhabitats in the forest-grassland ecotone

Description

Summary of the Study Area and Experimental Design for Database Study Area: Yanhe Watershed (36°27′–37°58′ N, 108°41′–110°29′ E), Chinese Loess Plateau, China. Climate: continental monsoon; average annual temperature 8-11°C; annual precipitation: 450-550 mm Sampling Period: 2022 Growing Season Three small watersheds (S1, S2, S3) were chosen along a southeast-northwest transect spanning the forest-steppe transition zone, with three late-successional plant communities investigated in each watershed: Bothriochloa ischaemum (BA, tussock grass), Artemisia gmelinii (AA, semi-shrub), and Sophora davidii (SA, shrub), totaling 9 sampling sites (3 watersheds × 3 communities). Sampling was carried out in two distinct microhabitats within each site: vegetation patches (area extending from plant core to midpoint of canopy edge of dominant species) and open patches (sparse ground between dominant species), with all sites located on uncultivated or abandoned slopes with more than 40 years of succession. For vegetation and seedling surveys, 162 sub-plots (0.5×0.5 m) were established (3 watersheds × 3 communities × 2 patches × 9 replicates), recording species abundance, height, and coverage for vegetation and abundance for seedlings. α-diversity was calculated as species richness per subplot, γ-diversity as total richness per plot, and β-diversity as turnover among three subplots per plot using β = (γ/ᾱ)-1. The soil seed bank sampling collected 54 composite samples (3 watersheds × 3 communities × 2 patches × 3 replicates) by extracting twenty 5 cm-deep cores (5 cm diameter) per patch, mixing them, and using a 5-month germination method after sieving (0.2 mm), spreading samples over sterilized sand in trays with control trays for contamination detection, turning soil at 2 months, and applying gibberellic acid at 4 months to break dormancy. F54 soil samples were collected using a five-point sampling method at 0-10 cm and 10-20 cm depths for organic carbon (K₂Cr₂O₇ oxidation method) and total nitrogen (Kjeldahl method). Undisturbed cores were taken for soil moisture (oven-drying at 105°C), bulk density (core method), and aggregate stability (dry and wet sieving using 2, 1, 0.5, 0.25, and 0.106 mm sieves). Mean growing-season temperature and precipitation were extracted from the National Earth System Science Data Center at 25 m × 25 m resolution.

Institutions

• Shaanxi Normal University

  Shaanxi, Xi'an

Categories

Funders

• National Natural Science Foundation of China

  Grant ID: 42377322
• the Key Research and Development Program of Shaanxi Province

  Grant ID: 2025SF-YBXM-129

Licence