Aridity-dependent regulation of water-use efficiency by leaf vein traits across grassland communities
Data files
Jun 05, 2026 version files 16.53 KB
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Community-level_trait_data.csv
13.79 KB
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README.md
2.74 KB
Abstract
Water transport is a fundamental constraint on plant growth in arid regions. Leaf vein architecture regulates carbon assimilation and transpiration through leaf hydraulic conductance (Kleaf), thereby influencing ecosystem water-use efficiency (WUE) via community-level hydraulic integration. However, most studies have focused on species-level traits, and how community-level leaf vein traits vary along aridity gradients, and regulate ecosystem WUE remains poorly understood.
We selected 20 grassland sites along aridity gradients across the Mongolian Plateau (MP) and Tibetan Plateau (TP), measured leaf vein traits of 185 species, and estimated Kleaf using a modelling approach. Community-weighted trait analyses were conducted to examine variation in leaf vein traits along aridity gradients and their relationships with ecosystem WUE.
On the MP, community-level leaf vein traits exhibited a nonlinear threshold response to aridity, with a breakpoint at ~0.8. Under less arid conditions, vein length per area (VLA), vein diameter (VD), and vein area index (VAI) declined with increasing aridity, whereas vein efficiency (VE) remained relatively stable, and Kleaf explained most variation in WUE. Under more arid conditions, VLA and VE increased, VAI remained stable, and aridity became the dominant driver of WUE variation. This transition coincided with a shift in community composition from high vein-investment, drought-tolerant perennial species to low-investment, high-efficiency, drought-escaping annual species. In contrast, on the TP, where low-temperature constraints are stronger, all traits declined linearly with increasing aridity, with no evident threshold response.
These findings indicate that the regulation of WUE by leaf vein traits and Kleaf is aridity-dependent. Our results provide community-level evidence for grassland responses to climate change and offer guidance for improving arid-region ecosystem models.
Dataset DOI: 10.5061/dryad.866t1g261
Files and variables
File: Community-level_trait_data.csv
Description: This dataset contains community-level leaf vein traits and ecosystem water-use efficiency (WUE) data collected from 20 grassland sites across the Mongolian Plateau (MP) and Tibetan Plateau (TP) in China. The data were used to examine how community-level leaf vein traits vary along aridity gradients and regulate ecosystem WUE. The study covered meadow steppe, typical steppe, and desert steppe, and a total of 185 species were sampled. For each of the 160 plots (8 plots per site × 20 sites), community-level trait values were calculated as the sum of species‑specific trait values weighted by leaf area index (LAI), i.e., Σ(LAIᵢ × traitᵢ).
Note: All leaf vein trait values (VLA, VD, VAI, VE) in this dataset are community‑level values after weighting by leaf area index (LAI), calculated as Σ(LAIᵢ × traitᵢ) per plot.
Variables
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Location: Geographical region of the sampling site: "Mongolian Plateau" (MP) or "Tibetan Plateau" (TP).
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site: Ten sites were established on each plateau (MP01–MP10 on the Mongolian Plateau; TP01–TP10 on the Tibetan Plateau), totaling 20 sites.
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plot: Plot number within each site. Eight 1 × 1 m plots were arranged at equal intervals along a 100 m transect per site, numbered 1 to 8.
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plot-ID: Unique identifier for each plot, formatted as "Plateau-Site-Plot" (e.g., MP01-1).
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VLA (mm mm-2): Vein density (vein length per unit leaf area); values in the dataset are community-weighted traits aggregated by species leaf area index (LAI).
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VD (μm): Vein diameter, measured from microscope images.
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VAI: Vein area index, calculated as VAI = VLA × VD.
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VE (mmol MPa-1 m-2 s-1): Vein efficiency, defined as water transport capacity per unit vein area. Calculated as VE = Kleaf / VAI, where Kleaf is leaf hydraulic conductance estimated from a trait-based model
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WUE (g m-2 mm-1): Water-use efficiency, calculated as WUE = GPP / ET
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Aridity: calculated as Aridity = 1 – AI, where AI (aridity index from CGIAR-CSI database) is the ratio of mean annual precipitation to mean annual potential evapotranspiration (PET). Higher Aridity values indicate drier conditions.
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group: Aridity group classification used for threshold analysis. Based on segmented regression results on the Mongolian Plateau, a breakpoint was identified at Aridity ≈ 0.77. Samples with Aridity < 0.77 are labeled "Aridity<0.77"; those with Aridity ≥ 0.77 are labeled "Aridity≥0.77".