# Elevation-dependent productivity trade-offs in wild Elymus sibiricus populations across the Qinghai–Tibet Plateau zone

## TL;DR

This study identifies optimal elevations for growing Elymus sibiricus, a valuable grass species, by analyzing its growth traits and yields across different altitudes on the Qinghai–Tibet Plateau.

## Contribution

The study introduces a comprehensive evaluation framework combining multiple statistical methods to determine elevation suitability for Elymus sibiricus.

## Key findings

- E. sibiricus accessions from 3000–4000 m and above 4000 m showed distinct growth patterns.
- Forage yield was influenced by plant height and leaf width, while seed yield was linked to leaf length and tillering.
- Accession 2019−001 from 3147 m elevation demonstrated the highest comprehensive performance.

## Abstract

Elymus sibiricus is a significant native grass species on the Qinghai-Tibet Plateau, recognized for its ecological and forage value. Elevation serves as a critical environmental factor that affects its growth and development. Therefore, identifying optimal elevations for E. sibiricus is essential for its effective selection and utilization.

In this study, a common garden experimental design was adopted. Six wild E. sibiricus accessions originating from different elevations were sown in 2022, and a two−year field trial (2023–2024, i.e., the second and third growth years) was conducted in the eastern Qinghai–Tibet Plateau. By observing agronomic traits and measuring forage and seed yields, we employed Mantel tests, K-means clustering, the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) for comprehensive evaluation, and structural equation modeling to identify optimal elevations for E. sibiricus and to determine the key factors influencing yield.

Agronomic traits and yields were significantly improved with extended cultivation duration. Wild E. sibiricus accessions were categorized into two groups: one from elevations of 3000–4000 m and the other from above 4000 m.

Forage yield was primarily influenced by population morphology, which was determined by plant height and leaf width, while seed yield was driven by the reproductive architecture, supported by leaf length and effective tillering. Accession 2019−001 achieved the highest comprehensive evaluation score and demonstrated optimal performance, indicating that its elevation of 3147 m may represent a suitable altitudinal range for wild E. sibiricus. These findings provide a theoretical foundation and data support for the breeding of E. sibiricus in alpine regions.