Seed and seedling traits have strong impacts on establishment of a perennial bunchgrass in invaded semi‐arid systems

Abstract

1. Many restoration projects use seeds to found new populations, and understanding phenotypic traits associated with seedling establishment in disturbed and invaded communities is important for restoration efforts world-wide. Focusing on the perennial grass Elymus elymoides, a native species common to sagebrush steppe communities in the Western United States, we asked if seed and seedling traits could predict field establishment.2. We collected seeds from 34 populations from the western Great Basin. In greenhouse studies, we measured variation in seed and seedling characteristics of wild populations and one cultivar. We also quantified abiotic conditions at the collection location and asked if these characteristics predicted survival and other fitness metrics at five planting sites. Planting sites were all near-monocultures of the invasive annual grass Bromus tectorum, and all sites experienced similar, below-average precipitation during the experiment.3. Phenotypic traits were strongly correlated with performance across all sites, with remarkably high predictive power. Seeds from populations with longer roots, larger seeds and earlier emergence were significantly more likely to survive the first growing season (R 2 = 0.66, p < 0.0001). In contrast, while some abiotic variables at the collection location (e.g. 30-year average summer precipitation and fall minimum temperatures) were associated with field performance at some sites, abiotic variables explained less variation in performance than traits (average R 2 = 0.22). Despite the low predictive power of abiotic variables, populations that performed best at each field site were from locations with climate variables similar to planting sites. 4. Synthesis and applications. The best seed sources for restoration of Elymus elymoides in invaded sites were populations with longer roots, larger seeds and earlier emergence. These easily measured traits were strong predictors of survival in disturbed field sites. While the most successful populations were found in areas with similar abiotic conditions as planting sites, there was phenotypic variation even among populations originating from locations with similar conditions. Thus, our results indicate that abiotic conditions are important considerations when selecting seeds, but these conditions may not sufficiently predict which populations

Ecological strategies begin at germination: Traits, plasticity and survival in the first 4 days of plant life

“…We did not explore some important sources of intraspecific trait variation in this study, including local adaptation and maternal effects (in part, because seedlots were collected from diverse growing environments). However, given strong evidence for the importance of maternal effects (Sultan, Barton, & Wilczek, ) and local adaptation (Leger et al, ) for seedling trait expression and performance, these sources of intraspecific variation must be more fully integrated into our understanding of trait expression and responses to drought.…”

“…Studies suggest that inter‐ and intraspecific variation in seedling morphology in the days after germination can be substantial (Evans & Etherington, ; Poorter, Remkes, & Lambers, ) and influence recruitment (Larson et al, ; Leger, Atwater, & James, ). Still, few studies have explicitly linked early seedling traits to drought response despite well‐developed theory (Comita & Engelbrecht, ; Kitajima & Myers, ; Saatkamp et al, ).…”

“…via deeper or longer roots, though evidence is mixed, Comita & Engelbrecht, ). Separately, a drought ‘escape’ strategy could enable a plant to complete its life cycle more quickly and evade stress, for example, via rapid emergence (Leger et al, ) or growth fueled by thin, efficient tissues (i.e. more absorptive surface area for a given mass investment).…”

“…Even when species exhibit structured trait differences on average, several factors can lead to varied stress responses within species (e.g. Leger et al, ). Drought, for example, can induce plastic shifts towards slower growth, thicker tissues and greater root allocation, but with substantial variability (or opposite responses) across species (e.g.…”

Using seedling phenotypic traits to select local seed sources for large-scale restoration: methods and outcomes in a Great Basin case study

“…Our project benefited from previous experiments that focused on identifying the potentially adaptive traits associated with seedling performance of E. elymoides and P. secunda in the presence of the highly competitive exotic annual grass Bromus tectorum L. Through a series of greenhouse and field studies (Appendix 1), we have found a number of traits associated with greater performance or survival of plants in these systems including: earlier emergence, longer roots, higher root mass ratio (RMR; the amount of total biomass allocated to roots), a larger number of root tips, and higher specific root length (SRL; a measure of root length to root weight, with higher values typically indicating greater allocation to fine roots), and smaller seedling size (for E. elymoides) (Leger & Baughman 2015;Leger & Goergen 2017;Leger et al 2019). Seed size has also been important, though the relationship between seed size and success has had mixed outcomes, with larger seeds performing better in some situations, and smaller seeded plants performing better in others (e.g., Kulpa & Leger 2013;Leger et al 2019). We expected that locally-collected populations from disturbed sites would possess a greater number of potentially adaptive traits than widely-available commercial varieties, indicating that there would be value in expending the effort to increase them for use in local restoration.…”