Consequences of bushmeat hunting in tropical forests

Abstract

This thesis evaluates the effect of bushmeat hunting in southeastern Nigerian rainforests on: 1) adult tree, seedling, and animal community compositions 2) germination and survival among seedlings in association with competition 3) changes in community composition at multiple trophic levels 4) leaf nitrogen concentration (LNC), leaf mass per area (LMA) and stem specific density (SSD) 5) on human reliance on forest resources and rural people use forest resources. Data for the first four evaluations were obtained from surveys, manipulative experiments in seedling plots and collected leaf samples in three pairs of sites with high (hunted sites) and low (protected sites) hunting pressure but with similar adult tree composition. Primate dispersed species dominated in paired sites. Results showed that primates (4-180 kg) were much rarer in hunted sites, while seed predators increased in abundance with hunting. Community composition of birds was similar in paired sites. Seedlings and adult tree composition were similar in protected sites. Abiotically dispersed species dominated in hunted sites and had a higher germination rate only in hunted sites. Seedling communities were significantly related to mammal communities. LNC and SSD increased with hunting but not LMA. Data from questionnaires administered in four villages in and around the Cross River National Park revealed an overwhelming reliance by households on forest resources for sustenance. Contrary to prevailing knowledge, the collection of food resources was the most widespread form of resource extraction and not bushmeat. More primate dispersed trees have utility for human compared to trees with other dispersal modes. Our results reveal a minimal effect of competition among seedlings compared to trees rather that dispersal limitation and altered mammal community composition triggered by the decline of efficient seed dispersing vertebrates majorly mediate changes in seedling communities and that these changes are largely detrimental to forest conservation and human wellbeing.

Abstract (Swedish)

Popular Abstract in English

This thesis presents data from rainforests of southeastern Nigeria. Pairs of protected and hunted of study sites were established in three different but adjacent protected areas: 1. Mbe Mountain Community Forest (MMCF, total area 80 km2); 2. Afi Mountain Wildlife Sanctuary (AMWS, total area 100 km2); and 3. Okwangwo division of the Cross River National Park (CRNP), total area 920 km2). Community compositions of primates, other mammals, birds, mature trees and seedlings were compared between sites in a pair. Hunting had a profound negative effect on primates as large to medium primates were rare in hunted sites while mammalian seed predators such as rodents, rock hyrax and squirrels increased in hunted sites. However, hunting had no effects on birds. The establishment success of seedlings of different plant species was strongly affected by hunting. That is, in protected sites seedling communities were dominated by primate dispersed species, but in hunted sites they were shifted towards a community more dominated by wind dispersed species. The pattern in the hunted forest was largely a consequence of the drastic decline of primates and the loss of their efficient seed dispersal . However, competition among seedlings did not appear important. This implies the rarity of primate-dispersed trees in future tropical forest canopies; a forest less diverse in timber and non-timber resources. Additionally, there was an increase in leaf nitrogen concentration and stem specific density in tree species that gained from hunting but not leaf mass per area. This suggests that changes in nutrient cycles can be expected due to hunting. In turn, this may imply higher productivity, soil fertility and herbivore insect density as well as reduced water quality and natural pest control in hunted tropical forests. However, further investigation is needed to fully evaluate what impact the increase in stem density in plants more common in hunted sites will have on aboveground carbon storage. Finally, I also studied the likely effect of hunting on forest ecosystem services provisioning and rural people use of the forest. A strong reliance on forest resources was found among households in four villages around one of the study areas (CRNP). Contrary to popular idea, bushmeat hunting was not the most widespread form of resource extraction but the extraction of other food resources. More trees dispersed by primates had useful resources for human livelihood compared to trees dispersed by other animals and wind. Findings from this thesis are significant to science and conservation because they shed new light on the detrimental effects of hunting on the ecosystem functions and services provided by tropical forests. It is shown in the thesis that birds or other animals will not take over the role of primates in the event of the extinction of primates. This thesis therefore reiterates the urgency for a solution to the pantropical bushmeat crisis before the forest shift to a steady state where it is severely impoverished of crucial plant species that support fruit eating animals and humans.

• author: Efiom, Edu
• supervisor: Ola Olsson; Henrik Smith
• opponent: Professor Lambert, Joanna, University of Texas, san Antonio
• organization: Biodiversity
• publishing date: 2013
• type: Thesis
• publication status: published
• subject: Ecology; Biological Sciences
• keywords: Tropical rainforests, bushmeat hunting, primates, seedling recruitment, interseedling competition, community composition, functional traits, ecosystem services, human livelihoods
• pages: 142 pages
• defense location: Blue Hall, Ecology Building, 37 Sölvegatan, 223 62 Lund
• defense date: 2013-03-01 13:30:00
• ISBN: 978-91-7473-460-7
• language: English
• LU publication?: yes
• id: 276872a2-7dc6-4587-9c96-b13565ad7005 (old id 3412856)
• date added to LUP: 2016-04-04 10:54:47
• date last changed: 2018-11-21 21:01:31