Occurrence, Composition, and Habitat Associations of Terrestrial Herbaceous Plants in a Tropical Forest Community

In tropical forests, niche differentiation in terms of resource partitioning remains a central hypothesis for the maintenance of species diversity. However, all plants require seemingly identical resources, which would appear to limit the number of niche dimensions available for species to inhabit. Woody species continue to be used to characterize the dynamics of tropical forest communities, while herbaceous species remain largely unstudied. This study underscores the need for future research to include terrestrial herbaceous plants when examining habitat partitioning and species coexistence in forest communities to obtain a more accurate picture of the factors driving plant species diversity. We conducted the study in the lowland tropical moist forest of the 50-ha Forest Dynamics Plot on BCI, Panama in which we randomly selected 30 20x20 m quadrats in each of four topographic habitats (high plateau, low plateau, slope, and swamp) in which to survey herbaceous plants. Each 20x20 m quadrat contained 16 1-m2 plots in which we identified all terrestrial herbaceous species and measured the maximum height and percent cover of each species. We tested for species habitat associations for the 13 most common species using both Kruskal-Wallis tests and Generalized Linear Models. In addition, we test whether the 13 most common species co-occurred more or less frequently than expected using Chi-square analysis. We encountered a total of 1,887 herbs of 54 species in the total 1,840 1-m2 plots that were censused. Occurrence was greatest in the moist, well-drained slope habitat and least in the annually inundated swamp habitat. Swamp had the most dissimilar species composition of all topographically defined habitat types, and also had the highest species diversity. Six of the 13 species analyzed had significant habitat associations based on both occurrence and cover data. Three of these species were positively associated with the swamp. Drought-intolerance and flooding-tolerance may be factors contributing to some species being strongly associated with swamps as habitats with low topography probably experience less water stress during the dry season. Co-occurrence results indicate that the only two congeneric species analyzed were negatively associated with each other. This may be evidence of more closely related species partitioning habitats more finely than less related species. Our results contribute to the growing body of evidence suggesting that many species of tropical plants, not just woody species, are associated with topographic habitat types. Thus, it is critical that all forest strata be considered to further our goal of better understanding species coexistence in plant communities. Synthesizing overstory and understory data will be monumental in increasing our knowledge and understanding of forest community dynamics, species coexistence and the effects of future climate change on entire communities from the bottom up.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Evolution, Ecology and Organismal Biology

Grantor dc:publisher

The Ohio State University

Year dc:date

2013

Author dc:creator

• Salpeter, Kara E.

Contributors dc:contributor

• Comita, Liza

• Biology
• Botany
• Biostatistics
• Climate Change
• Ecology
• Environmental Studies

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=osu1366219837

OAI identifier oai:identifier

oai:etd.ohiolink.edu:osu1366219837