Tree community structure data of arid riparian forests in the Ulungur River Basin

This dataset contains quadrat-level tree community structure and environmental data collected from arid riparian forests in the Ulungur River Basin, northwestern China. The data were obtained from field surveys conducted across 22 sampling sites, with each site including approximately four 30 m × 30 m quadrats (a small number of sites include two to three quadrats due to field constraints). For each quadrat, tree community structure was quantified using a set of stand-level structural indicators, including maximum and mean diameter at breast height, maximum and mean tree height, alive ratio, and mean health score. In addition, key environmental variables describing local habitat conditions were measured, including elevation, slope, and stand density. The dataset was used to investigate the relative contributions of environmental filtering and density dependence to variation in tree community structure at the quadrat scale. Specifically, the data support variance partitioning and redundancy analysis (RDA) to disentangle the independent and shared effects of topographic factors and stand density on forest stand structure in arid river valley ecosystems. All variables are provided in a single Excel file (Tree community structure data.xlsx). Two accompanying R scripts (Variance partitioning analysis R code.txt and RDA analysis R code.txt) reproduce the main statistical analyses reported in the associated manuscript. This dataset is intended to support transparency, reproducibility, and future comparative studies of riparian forest structure and ecological processes in arid environments.