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

This dataset contains plot‑level (30 m × 30 m) tree community structure and health data collected from arid riparian forests along the Ulungur River Basin in northwestern China. Field surveys were conducted at 22 sampling sites, with each site containing approximately four plots (a few sites have two or three plots due to field constraints). For each plot, we recorded species composition and measured diameter at breast height (DBH), tree height, crown width, and health status for each tree. From these measurements, we derived stand‑level variables: mean DBH, mean height, total basal area, total crown area, dead ratio, withered ratio, healthy ratio, and mean health score. Environmental predictors include elevation, slope, and stem density (number of individuals per plot). The dataset (Tree community data.xlsx) contains both raw and Z‑score standardized values. Four R scripts are provided to reproduce the main analyses: (1) Mann‑Whitney U test to compare pure vs. mixed forests; (2) negative binomial regression of density against elevation and slope; (3) Gaussian GLM (linear regression) for structural traits, comparing models with and without density; and (4) binomial GLM for health indicators, comparing models with and without density. These analyses assess the relative roles of environmental filtering and density dependence in shaping stand structure and tree health. The data and scripts support transparency, reproducibility, and future comparative studies in arid riparian ecosystems.