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Abstract AimTo examine the climatic and biogeographic drivers of plant trait variation across Caribbean tropical dry forests, a system characterised by high rates of plant endemism despite low moisture availability, high rainfall variability and persistent exposure to hurricanes. LocationCaribbean tropical dry forests. TaxonWoody plants. MethodsWe used a database of 572 woody vegetation plots spanning across the Caribbean, including Florida. We then extracted seed mass, specific leaf area and wood density from global trait databases. We supplemented additional trait data from herbaria collections and calculated phylogenetic imputation of traits. Furthermore, we calculated presence–absence community means and functional diversity and correlated these metrics with bioclimatic variables in addition to island and dry forest area using generalised additive models. ResultsDespite occurring in climatically distinct regions, Caribbean tropical dry forests are functionally similar, and the trait space of many dry forests are nested within the functional space of others. In line with island biogeographic theory, island area, dry forest area and island isolation were correlated with functional diversity. Although temperature and precipitation were important determinants of trait variation and functional diversity, environmental variables differently impacted trait variation and the variance explained was generally low. Main ConclusionsThe high functional overlap among Caribbean dry forests is remarkable given the broad climatic gradient across these islands. High functional overlap suggests that environmental and biogeographic filters constrain plant form and function in these intrinsically fascinating systems. The trait space of these insular dry forest systems points to dispersal‐limitation, in addition to high temperature and water limitations, and favouring persistence strategies to withstand high frequency hurricane disturbance.
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Trait‐based signatures of cloud base height in a tropical cloud forest
PremiseClouds have profound consequences for ecosystem structure and function. Yet, the direct monitoring of clouds and their effects on biota is challenging especially in remote and topographically complex tropical cloud forests. We argue that known relationships between climate and the taxonomic and functional composition of plant communities may provide a fingerprint of cloud base height, thus providing a rapid and cost‐effective assessment in remote tropical cloud forests. MethodsTo detect cloud base height, we compared species turnover and functional trait values among herbaceous and woody plant communities in an ecosystem dominated by cloud formation. We measured soil and air temperature, soil nutrient concentrations, and extracellular enzyme activity. We hypothesized that woody and herbaceous plants would provide signatures of cloud base height, as evidenced by abrupt shifts in both taxonomic composition and plant function. ResultsWe demonstrated abrupt changes in taxonomic composition and the community‐ weighted mean of a key functional trait, specific leaf area, across elevation for both woody and herbaceous species, consistent with our predictions. However, abrupt taxonomic and functional changes occurred 100 m higher in elevation for herbaceous plants compared to woody ones. Soil temperature abruptly decreased where herbaceous taxonomic and functional turnover was high. Other environmental variables including soil biogeochemistry did not explain the abrupt change observed for woody plant communities. ConclusionsWe provide evidence that a trait‐based approach can be used to estimate cloud base height. We outline how rises in cloud base height and differential environmental requirements between growth forms can be distinguished using this approach.
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- Award ID(s):
- 1833358
- PAR ID:
- 10377184
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- American Journal of Botany
- Volume:
- 107
- Issue:
- 6
- ISSN:
- 0002-9122
- Format(s):
- Medium: X Size: p. 886-894
- Size(s):
- p. 886-894
- Sponsoring Org:
- National Science Foundation
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