The Relationship Between the Distribution Characteristics of Ancient Tree Resources and Environmental Factors in the Main Urban Area of Qujing City

Based on the survey data of ancient trees in the main urban area of Qujing City, the nearest neighbor index and kernel density analysis methods were used to explore the spatial distribution characteristics of ancient trees in depth; At the same time, combined with remote sensing image data, the radiative transfer equation method is used to invert surface temperature, and DEM data is analyzed for altitude, slope, and aspect to reveal the correlation between environmental factors and ancient tree distribution.The results indicate that:The number of Ancient trees in the main urban area of Qujing City totaled 655, belonging to 32 families, 48 genera and 74 species, with the third grade old trees accounting for 90.84%, and the overall age of the trees was small. The nearest neighbor index is 0.217, and the coefficient of variation is 262.89%, the distribution characteristics of ancient trees belong to the type of strong spatial aggregation. Kernel density analysis reveals that ancient trees are significantly aggregated in space, exhibiting a distribution pattern that combines both "scattered" and "clustered" forms. Ancient trees are mainly concentrated in areas with low population density, deep soil layers, and less soil erosion, with the highest distribution of ancient trees in mountainous red soil. The distribution of ancient trees in areas of lower altitude is higher, and the higher the altitude the lower the number of ancient trees. The correlation between Shannon–Wiener Species Diversity Index and altitude is significant, with low values in low and high altitude areas, while the Pielou evenness index shows no significant change with elevation. The number of ancient trees is highest in slopes ranging from 0°～15°, and decreases sharply with increasing slope. Ancient trees are mainly concentrated in the moderately warm and sub-high temperature zones, with the least number in the low-temperature zone, which indicates that the distribution of ancient trees is concentrated within a certain temperature range. Temperatures that are either too low or too high are not suitable for the growth of ancient trees. Analyzing the ancient tree resources and their spatial distribution characteristics can provide a reference for the protection and management of ancient trees.