DOI: 10.5061/dryad.08kprr57c
title: Functional traits of young seedlings predict trade-offs in seedling performance in three neotropical forests

description: Understanding the mechanisms that promote the coexistence of hundreds of
 species over small areas in tropical forest remains a challenge. Many
 tropical tree species are presumed to be functionally equivalent
 shade-tolerant species that differ in performance trade-offs between
 survival in shade and the ability to quickly grow in sunlight. Variation
 in plant functional traits related to resource acquisition is thought to
 predict variation in performance among species, perhaps explaining
 community assembly across habitats with gradients in resource
 availability. Many studies have found low predictive power, however, when
 linking trait measurements to species demographic rates. Seedlings face
 different challenges recruiting on the forest floor and may exhibit
 different traits and/or performance trade-offs than older individuals face
 in the eventual adult niche. Seed mass is the typical proxy for seedling
 success, but species also differ in cotyledon strategy (reserve vs
 photosynthetic) or other seedling traits. These can cause species with the
 same average seed mass to have divergent performance in the same habitat.
 We combined long-term studies of seedling dynamics with functional trait
 data collected at a standard developmental stage in three diverse
 neotropical forests to ask whether variation in coordinated suites of
 traits predicts variation among species in demographic performance. Across
 hundreds of species in Ecuador, Panama, and Puerto Rico, we found
 seedlings displayed correlated suites of leaf, stem, and root traits,
 which strongly correlated with seed mass and cotyledon strategy. Variation
 among species in seedling functional traits, seed mass, and cotyledon
 strategy were strong predictors of trade-offs in seedling growth and
 survival. Our findings highlight the importance of cotyledon strategy in
 addition to seed mass as a key component of seed and seedling biology.
 These results also underscore the importance of matching the ontogenetic
 stage of the trait measurement to the stage of demographic dynamics.
 Synthesis: With strikingly consistent patterns across three tropical
 forests, we find strong evidence for the promise of functional traits to
 provide mechanistic links between seedling form and demographic
 performance. 
description: This dataset combines seedling demographic performance with leaf,
 stem, and root functional traits also collected on seedlings.  More
 details on data collection and processing are available in Metz et
 al. <em>Journal of Ecology.</em> 
 <strong>Seedling dynamics data</strong> are
 collected in networks of 1-m<sup>2</sup> plots in large (16-50
 ha) Forest Dynamics Plots at each of three Neotropical forests: Yasuní,
 Ecuador; Luquillo, Puerto Rico; and Barro Colorado Island, Panama.  Each
 year in each plot, we tag and measure all seedlings of woody species
 (including trees, shrubs, palms, and lianas), identify all newly recruited
 seedlings, and determine the fate of previously tagged seedlings. We
 examined survival and growth across the first year for newly recruited
 seedlings from multiple cohorts in the longitudinal study at each site.
   <strong>Functional traits</strong>
 were quantified on young, field-harvested seedlings at each
 site. 
description: # Seedling functional traits and demographic performance from three
 Neotropical forests *** This data table contains functional trait measures
 and growth and survival for seedlings from species in three Neotropical
 forests. Different subsets of species were used in different analyses in
 Metz et al. based on sample size or the availability of different suites
 of traits, as described in the text. ## Description of the data and file
 structure Each row is a species at one of three study sites. Columns are
 as follows. Each of these is described in much further detail in the
 accompanying article. 1. *site*, categorical, values are Yasuni, Luquillo
 or BCI, depending on the study site 2. *sp*, categorical, values are 4-6
 letter codes for the seedling species use. Codes are those used in the
 Forest Dynamics Plot at each site, or as described in the seedling
 demography datasets archived in the Environmental Data Initiative
 repository 3. *SLA*, numeric, specific leaf area; units are dm2/g or
 square decimeters per gram 4. *RS*, numeric, root-to-shoot biomass ratio;
 unitless ratio 5. *seedmass*, numeric, seed mass; units are g or grams 6.
 *density*, numeric, specific stem density; units are g/mL or grams per
 milliliter 7. *SRL*, numeric, specific root length; units are mm/g or
 millimeters per gram 8. *demog.axis*, numeric, PCA axis value representing
 growth-survival trade-off continuum 9. *trait.axis*, numeric, PCA axis
 value representing functional trait suites (SLA, RS, and seed mass) 10.
 *cotType*, categorical, values are PS (photosynthetic, leafy-type
 cotyledons) or NonPS (storage-type cotyledons) 11. *survivors*, integer,
 number of new seedling recruits that survived the first year 12.
 *started*, integer, total number of new seedling recruits encountered in
 the study across cohorts 13. *died*, integer, number of new seedling
 recruits that did not survive the first year 14. *survivorship*, numeric,
 proportion of new seedling recruits that survived the first year 15.
 *av.rgrowth*, numeric, average relative growth rate of new seedling
 recruits that survived the first year; measured as the natural log of the
 ratio of the heights in cm, standardized to one year. Values that have NA
 are missing. ## Sharing/Access information Data was derived from the
 following sources: *
 https://doi.org/10.6073/pasta/45e4817e74b51b9533b1bd4115415569 *
 https://doi.org/10.5061/dryad.j2r53 *
 https://doi.org/10.6073/pasta/2cb969b626c3e276770a4fdc8bb3e375 Please
 contact the authors regarding collaboration with these data.