Modeling Phenotypic Trait Variation and Plasticity in Elymus elymoides to Guide Climate-Informed Seed Transfer

Area of Science:

• Ecology
• Conservation Biology
• Plant Science

Background:

• Effective ecological restoration relies on climate-matched seed sourcing.
• Standard seed transfer models lack flexibility and may miss complex trait-climate associations.
• Understanding climate-associated phenotypic variation is crucial for seed sourcing.

Purpose of the Study:

• To characterize climate-associated variation in traits for *Elymus elymoides* (bottlebrush squirreltail).
• To develop novel, flexible seed transfer models (fixed-boundary and focal-point) using advanced methods.
• To create practical seed zone recommendations for restoration in the Intermountain Region.

Main Methods:

• Common garden experiments with 98 *Elymus elymoides* source populations.
• Analysis of phenotypic variation in growth, reproduction, morphology, phenology, and survival.
• Development of seed transfer models using regression trees and random forests.

Main Results:

• Identified distinct trait-climate associations, with larger plants and later flowering from cooler/wetter or milder climates.
• Populations from milder climates showed higher overall trait plasticity.
• Developed 13 hierarchical seed zones, with separate models for two subspecies groups, capturing complex associations.

Conclusions:

• Novel modeling approaches provide more precise focal-point seed transfer zones than standard methods.
• The hierarchical structure aids in balancing restoration risk and practical constraints.
• Findings underscore the importance of climate-trait associations for seed sourcing in a changing global climate.