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Grantee Research Project Results

Grantee Research Project Results

Wildlife Harvest and the Disruption of Seed Dispersal in the Forest Tree Choerospondias Axillaris (Anacardiaceae)

EPA Grant Number: F5F21901
Title: Wildlife Harvest and the Disruption of Seed Dispersal in the Forest Tree Choerospondias Axillaris (Anacardiaceae)
Investigators: Brodie, Jedediah F.
Institution: University of Montana
EPA Project Officer: Just, Theodore J.
Project Period: September 1, 2005 through August 31, 2008
Project Amount: $111,344
RFA: STAR Graduate Fellowships (2005)
Research Category: Academic Fellowships

Description:

Objective:

My research attempts to discover how illegal wildlife poaching and the removal of different component species of a seed disperser guild influence seed survival, seedling recruitment, and the demography of a dominant rainforest tree, Choerospondias axillaris (Anacardiaceae) in the forests of Thailand. C. axillaris has large seeds that are dispersed exclusively by white-handed gibbons (Hylobates lar), sambar deer (Cervus unicolor) and muntjac deer (Muntiacus muntjac), frugivores that are currently under severe poaching pressure.

Approach:

I am comparing seed dispersal and seedling regeneration across several National Parks where the frugivorous mammals have been reduced or eliminated. Research proposed here will quantify the relative functional ‘effectiveness’ of the different frugivores in the disperser guild. If it turns out that extirpation of one or two of the mammals is compensated for by the persistent activities of the remaining species, seed dispersal and germination should be unaffected. But if the frugivores differ in the efficacy of the dispersal services they provide, losses of crucial species will not be so easily compensated. I am attempting to answer the following questions:

  1. Does Choerospondias axillaris suffer negative demographic impacts in parks with defaunated mammal assemblages, as compared to areas with intact mammal assemblages?
  2. How similar are the three major mammalian frugivores in terms of the fates of seeds they disperse and their impacts on overall C. axillaris demography?
  3. How do different seed dispersal syndromes and light gap dynamics interact to influence the regeneration patterns of C. axillaris?

Expected Results:

Preliminary results suggest that C. axillaris suffers noticeable reductions in seed dispersal in parks where the frugivorous mammals have been reduced. In contrast, seed dispersal levels in parks with abundant frugivores are high, and C. axillaris seedlings are common. While initial results indicate that C. axillaris critically depends on dispersers for regeneration, it appears that the quality of dispersal services may vary greatly between the three primary frugivores.

Supplemental Keywords:

Demography, Interspecific interactions, Mutualism, Poaching, Tropical forests,, RFA, Scientific Discipline, ECOSYSTEMS, Ecosystem Protection/Environmental Exposure & Risk, wildlife, Environmental Monitoring, Species, Ecology and Ecosystems, population stressors, endangered species, forest ecosystem, deer species, Wildlife Risk Assessment, wildlife community structure, White Haired Gibbon, seed dispersal, competitive interactions

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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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