Seed and seedling traits affecting critical life stage transitions and recruitment outcomes in dryland grasses

Authors: LARSON, JULIE - Oregon State University; Sheley, Roger; Hardegree, Stuart; DOESCHER, PAUL - Oregon State University; JAMES, JEREMY - University Of California Agriculture And Natural Resources (UCANR)

Submitted to: Journal of Applied Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/9/2014
Publication Date: 1/20/2015
Publication URL: http://handle.nal.usda.gov/10113/62976
Citation: Larson, J.E., Sheley, R.L., Hardegree, S.P., Doescher, P.S., James, J.J. 2015. Seed and seedling traits affecting critical life stage transitions and recruitment outcomes in dryland grasses. Journal of Applied Ecology. 52:199-209. doi: 10.1111/1365-2664.12350.

Interpretive Summary: The majority of functional trait work has centered on linking leaf and root traits of seedlings and adults to resource acquisition, utilization, and growth. However, our study demonstrates that traits driving processes associated with germination and emergence may have a prevailing influence on restoration outcomes. A portion of these traits have been identified, but there is substantial opportunity to identify other key traits driving these demographic processes. Linking these advancements to our current understanding of trait spectra reflecting resource acquisition and growth can be used to develop a comprehensive trait-based framework for overcoming recruitment barriers.

Technical Abstract: 1. Seeding native plants is a key management practice to counter land degradation across the globe, yet the majority of seeding efforts fail, limiting the ability of this tool to accelerate ecosystem recovery. 2. Seedling recruitment requires transitions through several life stages, some of which may have an overriding influence on restoration outcomes. However, we currently lack a general, mechanistic framework to understand and predict differences in these critical demographic processes among species. This study links variation in key functional traits to variation in seed and seedling life stage transition probabilities to examine how functional traits influence recruitment. 3. We used seed and seedling traits, and field probabilities of germination, emergence, seedling establishment, and survival for 47 varieties of semi-arid grasses under two watering treatments to identify critical life stage transitions and quantify the effect of functional traits on cumulative survival probability through the first growing season. 4. Variation in germination and emergence probabilities explained over 90% of the variation in cumulative survival regardless of watering treatment, with 10 to 23% of the variation in these transition probabilities attributed to variation in coleoptile tissue density and seed mass. Synthesis and Applications. The majority of functional trait work has centered on linking leaf and root traits of seedlings and adults to resource acquisition, utilization, and growth. However, our study demonstrates that traits driving processes associated with germination and emergence may have a prevailing influence on restoration outcomes. A portion of these traits have been identified, but there is substantial opportunity to identify other key traits driving these demographic processes. Linking these advancements to our current understanding of trait spectra reflecting resource acquisition and growth can be used to develop a comprehensive trait-based framework for overcoming recruitment barriers.