Functional traits of young seedlings predict trade-offs in seedling performance in three neotropical forests
Data files
Sep 06, 2023 version files 38.05 KB
Abstract
- 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.
README: 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.
- site, categorical, values are Yasuni, Luquillo or BCI, depending on the study site
- 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
- SLA, numeric, specific leaf area; units are dm2/g or square decimeters per gram
- RS, numeric, root-to-shoot biomass ratio; unitless ratio
- seedmass, numeric, seed mass; units are g or grams
- density, numeric, specific stem density; units are g/mL or grams per milliliter
- SRL, numeric, specific root length; units are mm/g or millimeters per gram
- demog.axis, numeric, PCA axis value representing growth-survival trade-off continuum
- trait.axis, numeric, PCA axis value representing functional trait suites (SLA, RS, and seed mass)
- cotType, categorical, values are PS (photosynthetic, leafy-type cotyledons) or NonPS (storage-type cotyledons)
- survivors, integer, number of new seedling recruits that survived the first year
- started, integer, total number of new seedling recruits encountered in the study across cohorts
- died, integer, number of new seedling recruits that did not survive the first year
- survivorship, numeric, proportion of new seedling recruits that survived the first year
- 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.
Methods
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. Journal of Ecology.
- Seedling dynamics data are collected in networks of 1-m2 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.
- Functional traits were quantified on young, field-harvested seedlings at each site.