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Extramural Research

Grantee Research Project Results

Grantee Research Project Results

The Effect of Logging on Mechanisms That Limit the Recruitment of Tropical Tree Species: Implications for the Maintenance of Biodiversity in Tropical Forests

EPA Grant Number: FP916308
Title: The Effect of Logging on Mechanisms That Limit the Recruitment of Tropical Tree Species: Implications for the Maintenance of Biodiversity in Tropical Forests
Investigators: Clark, Connie J
Institution: University of Florida
EPA Project Officer: Jones, Brandon
Project Period: January 1, 2004 through December 31, 2004
Project Amount: $99,904
RFA: STAR Graduate Fellowships (2004)
Research Category: Fellowship - Terrestrial Ecology and Ecosystems , Academic Fellowships , Ecological Indicators/Assessment/Restoration

Description:

Objective:

The objective of this research project is to examine how tropical tree diversity is affected by logging by gaining a better understanding of the processes that maintain biodiversity and how they are impacted by disturbance. I will examine three primary mechanisms thought to maintain tropical tree diversity, hypothesizing that logging will differentially alter their relative importance. The mechanisms are establishment limitation, dispersal limitation, and Janzen-Connell effects.

Approach:

I will examine the relative importance of establishment limitation, seed-limitation, and Janzen-Connell effects by: (1) experimentally sowing seeds; (2) monitoring seedlings and saplings in logged and unlogged forests; and (3) relating mortality of seeds, seedlings, and saplings with distance from parent trees. All data will be collected from 10 logged sites and 10 unlogged forests. At each site, I will identify, tag, and map all trees greater than 10 cm dbh and all saplings between 2-5 cm dbh for six focal species. I then will use inverse modeling to relate the survivorship of seeds and seedlings monitored by seed augmentation and seedling plots with distance to the nearest conspecific adult, as well as with the density of conspecifics within and across age classes.

I will test the following predictions:

(1) Establishment limitation will be lower in logged than unlogged forest because higher light availability in logged forests will increase the number of suitable establishment sites and thereby lower the extent to which those sites are limiting.

(2) Dispersal limitation will be higher in logged than unlogged forests because removal of fruit-producing trees will place greater limits on the number of seeds available for dispersal, as well as reducing the abundance of seed dispersing animals (which relied on those removed trees for fruit).

(3) Janzen-Connell effects (higher seed and seedling mortality near parent plants) will be less in logged forests than unlogged forests because higher temperatures and greater light availability will decrease the prevalence of host specific fungal pathogens, decreasing mortality by pathogen attack near parents.

Supplemental Keywords:

fellowship, seed limitation, establishment limitation, Janzen-Connell hypothesis, tropical forests, logging, biodiversity, recruitment limitation, Congo,, RFA, Scientific Discipline, ECOSYSTEMS, Ecosystem Protection/Environmental Exposure & Risk, Ecosystem/Assessment/Indicators, Ecosystem Protection, Forestry, Monitoring/Modeling, Ecological Effects - Environmental Exposure & Risk, Ecological Monitoring, Ecological Indicators, ecological effects, seed limitation, Janzen Connell effects, adverse impacts, biodiversity, land cover, terrestrial ecosystems, forest ecosystems, tropical ecosystems, forest land cover, ecological assessment, ecological impacts, logging effects, tropical tree species, ecosystem impacts, changes in forest cover, establishmnet limitation, dispersal limitation, forest conservation, land management

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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