DOI: 10.5061/dryad.3r2280gmx
title: Vertical structural complexity of plant communities represents the combined effects of resource acquisition and environmental stress on the Tibetan Plateau

description: Knowledge of vertical structural complexity (VSC) is important, because
 the resulting spatial partitioning is closely linked to resource
 utilization and environmental adaptation. However, the spatial pattern of
 VSC on large scales and its underlying mechanisms are poorly understood.
 Here, we systematically investigated 2,013 plant communities through grid
 sampling on the Tibetan Plateau (TP). VSC was quantified as the maximum
 plant height within a plot (Height-max), coefficient of variation of plant
 height (Height-var), and Shannon evenness of plant height (Height-even).
 Precipitation dominated the spatial variation in VSC in forests and
 shrublands, supporting the classic physiological tolerance hypothesis
 (PTH). In contrast, for alpine meadows, steppes, and desert grasslands in
 extreme environments, non-resource limiting factors (e.g., wide diurnal
 temperature ranges and strong winds) dominate VSC variation. Generally,
 with the shifting of climate from favorable to extreme, the effect of
 resource availability gradually decreases, but the effect of non-resource
 limiting factors gradually increases, and that the PTH only applicable in
 “favorable conditions”. With the help of machine learning models, maps
 of VSC at 1-km resolution were produced for the TP for the first
 time. Our new findings and maps of VSC provide new insights into
 macroecological studies, especially for adaptation mechanisms and model
 optimization.
description: Field sampling was conducted
 during the high-growth period from mid-July to late August in 2018, 2019,
 and 2020. According to the latitude and longitude, we divided the entire
 Tibetan Plateau (TP) into
 1,000 grids of equal area (0.5° × 0.5°). For alpine grasslands (i.e.,
 alpine meadows, alpine steppes, and alpine desert grasslands), we selected
 the dominant plant communities via visual observation in each grid and
 randomly set up three 1 m × 1 m plots for the field investigation. There
 were 1,527 plots for grassland communities, and the height of the tallest
 plant in each plot was measured. For each species within the plots, we
 recorded their coverage and then randomly selected three plants of each
 species to measure their height (all measurements for less than three
 individuals); in total, 19,320 plants were
 measured. For forests (456 plots) and shrublands (30
 plots), three 20 m× 20 m plots were randomly established in each grid, for
 a total of 486 plots. For forests, we recorded all vascular plants in
 these plots, including trees, shrubs, and herbaceous species. Diameter at
 breast height (DBH) was measured for trees with a DBH of ˃3 cm. A
 telescopic stick was used to measure the tree height, and 17,443 trees
 were measured. Only trees with a DBH &gt; 3 cm were measured, as this
 is a common standard for recording tree layer-related data in forest
 community surveys . For
 shrublands, we recorded their basal diameter and height, and 339 plants
 were measured. Across all vegetation types, a total of 2,013 field plots
 were investigated, and the height of 37,102 plants was used for the
 analysis.
description: # Vertical structural complexity of plant communities represents the
 combined effects of resource acquisition and environmental stress on the
 Tibetan Plateau We
 systematically investigate 2,013 plant communities through grid sampling
 on the Tibetan Plateau. Vertical structural complexity is quantified as
 the maximum plant height within a plot (Height-max), coefficient of
 variation of plant height (Height-var), and Shannon evenness of plant
 height (Height-even). Field sampling was conducted during the high growth
 period of mid-July to late August in 2018, 2019, and 2020. We divided the
 entire TP according to the latitude and longitude into 1,000 grids with
 equal area (0.5° × 0.5°). **Abbreviation list** TP, Tibetan Plateau
 Height-max, the maximum plant height within a plot Height-var, coefficient
 of variation of plant height Height-even, Shannon evenness of plant height
 For more details and citations, see our paper published in Communications
 Biology (Changjin Cheng, 2024).