Effects of soil nutrient availability on the development of tropical monodominance and subordinate species composition in montane forests

Although tropical forests are well known for harbouring some of the highest levels of plant diversity in the world, natural areas occur where a single tree species dominates the forest stand. The presence of these monodominant forests therefore represents an unusual and intriguing phenomenon. Several studies over the past 30 years have attempted to explain how monodominance arises and how monodominant species persist in otherwise highly diverse tropical forests. Proposed mechanisms can be grouped into the “exceptional trait” and “ecosystem modification” hypotheses. Using the framework of these hypotheses, this study aimed to understand how an ectomycorrhizal tree species, Oreomunnea mexicana, achieves high abundance. The study assessed soil properties along with species composition using a paired plot design consisting of mixed forest and nearby Oreomunnea-dominated forest sampled at four sites in montane forest in western Panama. We found support for the “ecosystem modification” hypothesis as Oreomunnea-dominated stands mostly differed in soil properties from mixed forest stands that shared the same soil parent material. Alterations to soil conditions via a positive plant-soil feedback were also associated with differences in the composition of the subordinate tree species community. Species diversity not affected by the presence of Oreomunnea, and compositional beta-diversity was lower across Oreomunnea-dominated forests, suggesting that the plant-soil feedback imposed additional environmental filtering on the tree community. However, the capacity to generate plant soil feedback is itself a consequence of an “exceptional trait”, the presence of ectomycorrhizal fungi associations in Oreomunnea-dominated forests, in a community otherwise consisting of trees that form arbuscular mycorrhizal associations.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Plant Biology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Mijango Ramos, Zarluis Miguel

Contributors dc:contributor

• Dalling, James W
• Heath, Katy D
• O'Dwyer, James P

• Tropical monodominance
• Species diversity
• Oreomunnea mexicana

Statement dc:rights

• Copyright 2021 Zarluis Mijango-Ramos

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/113055

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/113055