Tree inventory dataset from pure and mixed stands in Lanzhou, Northwest China

This dataset contains tree inventory data collected from eight 20 m × 20 m permanent plots (total area 0.32 ha) in a forest farm in Lanzhou City, Gansu Province, Northwest China (approximately 36.26°–36.28° N, 102.99°–103.00° E). A total of 731 individual trees were measured. The plot design includes four pure stands and four mixed stands with multiple co-occurring species. For each tree, diameter at breast height (DBH, cm) and total height (m) were recorded, along with species identification. Plot-level metadata include stand type, elevation (1670–1700 m), slope (5–8°), stand age, plot area (400 m² each), and survey date (July 2025). The dataset is provided as a Microsoft Excel file with three sheets: Tree-level data (731 rows), Plot metadata and Data dictionary.