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ARS Home » Pacific West Area » Burns, Oregon » Range and Meadow Forage Management Research » Research » Publications at this Location » Publication #303113
Title: Do key dimensions of seed and seedling functional trait variation capture variation in recruitment probability?

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

Submitted to: Oecologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/16/2015
Publication Date: 9/4/2015
Publication URL: http://handle.nal.usda.gov/10113/62963
Citation: Larson, J.E., Sheley, R.L., Hardegree, S.P., Doescher, P.S., James, J.J. 2015. Do key dimensions of seed and seedling functional trait variation capture variation in recruitment probability? Oecologia. 181:39-53. doi: 10.1007/s00442-015-3430-3.

Interpretive Summary: While this study makes progress in describing multidimensional patterns of trait variation during recruitment, the lack of association between trait-based strategies and germination, emergence and survival probabilities highlights the remaining gap in our ability to link functional trait variation to variation in recruitment. Advancement towards this goal presents a major opportunity to further understanding of how traits and trait-tradeoffs differentiate ecological strategies and performance among species.

Technical Abstract: 1. Plant functional traits provide a mechanistic basis for understanding ecological variation among plant species and the implications of this variation for species distribution, community assembly and restoration. 2. The bulk of our functional trait understanding, however, is centered on traits related to resource capture and vegetative growth, and we know comparatively little about seed and seedling trait variation influencing recruitment, or if these traits can be used to define general ecological strategies to predict recruitment outcomes. 3. We measured seed traits, seedling traits, and field probabilities of germination, emergence, and seedling survival for 47 varieties of native and introduced grasses in U.S. western drylands. We used PCA and cluster analysis to identify major dimensions of trait variation and ecological strategies across early life stages and then asked whether the identified strategies also captured variation in life stage transition probabilities. 4. Ordination highlighted four axes of trait variation, highlighting some links between seed and seedling functional traits. The first axis was an extension of the leaf economic spectrum, linking specific leaf area (SLA), relative growth rate (RGR) and root elongation rate (RER) on one end to leaf dry matter content (LDMC), initial root mass, seed mass, and base temperature for germination on the other end. Subsequent axes independently demonstrated negative associations between specific root length (SRL) and root mass ratio (RMR), and between hydrothermal time and base water potential for germination. 5. Cluster analysis separated grasses into six ecological strategies with unique sets of traits independently describing germination rate and seedling growth rate. 6. While recruitment probability varied nearly 20-fold across species, trait-based species clusters did not differ significantly in terms of germination, emergence or survival probabilities. 7. Synthesis While this study makes progress in describing multidimensional patterns of trait variation during recruitment, the lack of association between trait-based strategies and germination, emergence and survival probabilities highlights the remaining gap in our ability to link functional trait variation to variation in recruitment. Advancement towards this goal presents a major opportunity to further understanding of how traits and trait-tradeoffs differentiate ecological strategies and performance among species.