Show simple item record

Conservation Value of Logging Concession Areas in the Tropical Rainforest of the Korup Region, Southwest Cameroon

Conservation of Tropical Rainforests

dc.contributor.advisorMühlenberg, Michael Prof.
dc.titleConservation Value of Logging Concession Areas in the Tropical Rainforest of the Korup Region, Southwest Cameroonde
dc.title.alternativeConservation of Tropical Rainforestsde
dc.contributor.refereeSchaefer, Matthias Prof.
dc.subject.dnb000 Allgemeines, Wissenschaftde
dc.description.abstractengTropical rainforests are home for renewable natural resources for living and non living things. The dynamic and interdependent nature of tropical rainforest components make it a fragile ecosystem and the scale in which human exercise pressure on these forests has increased over the past decades. Extraction of valuable trees for commercial purpose and other logging activities in tropical rainforest has mainly contributed to the reduction of the size of the rainforest belt. Furthermore, current levels of wildlife exploitation in many parts of tropical West and Central Africa pose serious threats to wildlife populations. While the "bushmeat problem" is one of the major problems in conservations science and management, there are few experiences with wildlife management in tropical rainforests at all, and most of the biological and social pre-conditions for a successful application remain obscure. The broad aims of this study are to evaluate the conservation value of logging concession areas of the Korup region through the assessment of tree communities and wildlife populations and to propose a conservation management concept for wildlife in the region. Many studies are dealing with the effects of selective logging on tree communities, but few studies have attempted to analyse effects of logging at different scale levels and analysed vegetation composition in logged areas in detail. We studied tree assemblages in forests adjacent to Korup National Park in the Southwest of Cameroon. A total of 168 plots of 50 m x 50 m (0.25 ha) were systematically distributed along 24 two-km transects situated within four 16 km2 study areas, of which two were in 10 years-old heavily logged forests and two in relatively undisturbed primary (unlogged) forests. Beside the vegetation, primates and hornbills are described to play an important role in the maintenance of tropical forests and the food resources constitute one of the most limiting factors for most wildlife species including primates and hornbills. We investigated food resources for primates and hornbills following the plot, transect and study site design. In addition we studied the population development of eight primate and two hornbill species using the line transect and the Distance sampling models. A total of 9,134 trees (dbh . 8.0 cm) belonging to 217 species and 55 families were recorded. Community parameters of trees were analysed at plot, transect and study site levels, and compared between logged and unlogged forests. Tree abundance was relatively lower (about 38%) in logged forests compared to unlogged forests. Tree species richness was least affected at the largest sampling scale (16-km2 study site). Species richness was reduced from 188 species (Jackknife index= 208 spp.) to 177 species (Jackknife= 213 spp.) at smaller spatial scales, a reduction of 6%. Along the 2-km transects, an average of 87.5 ( } 5.0) species were found in unlogged compared to 68.5 (±3.0) species in logged forest (reduction of 32%). At plot level (50 x 50 m), 32.4 (±7.6) species were found in unlogged and 22.2 (±5.7) species in logged forest (reduction of 31%). However, species composition differed markedly between logged and unlogged forests as was shown by two-dimensional ordination of the tree assemblages at species level. An analysis at family level, including the twenty one most abundant tree families did not show significant differences in family importance values (FIV) between unlogged (FIV= 222.58 and 221.51) and logged (FIV= 207.52 and 214.64) study sites, suggesting that logging effects are rather at species than at family level. Food trees were relatively more abundant in unlogged forests (2,556 food trees recorded) compared to logged forests (1,864 trees recorded). Primates population densities differed from one species to another but also from unlogged and logged study sites. The C. mona, C. nictitans nictitans, C. pogonias, C. torquatus and P. troglodytes population densities were relatively high in logged (28.73 ind./km2; 23.35 ind./km2; 1.03 ind./km2; 6.65 ind./km2; and 2.03 ind.km2 respectively) forests study sites compared to unlogged (15.24 ind./km2; 17.90 ind./km2; 0.31 ind./km2; 1.01 ind.km2; and 0.02 ind.km2 respectively) forest study sites. C. erythrotis had high estimates in unlogged forests (17.55 ind./km2 ) compared to logged forests (10.93 ind./km2) study sites. However the preuss fs red colobus (P. pennantii preussi) was not observed in logged forest study sites and was estimated at very low density (0.02 ind.km2) in unlogged forest study sites. Compared with earlier studies, the drill (M. leucophaeus) population density has relatively increased in unlogged (1.03 ind.km2) and in logged (0.91 ind./km2). The black-casqued hornbill (C. atrata) population was relatively higher in logged forest study sites (23.15 ind./km2) compared to unlogged forest study sites (21.61 ind./km2). However, the brown-checked hornbill (C. cylindricus) population density was relatively higher in unlogged (25.08 ind/km2) compared to logged (22.43 ind./km2) forest study sites. The relationship between primates and hornbill with their potential food tree resources was investigated. At transect level and in logged II, we found a negative, strong and significant correlation between C. pogonias (R= -088 and P= 0.019) and C. torquatus (R= -0.94 and P= 0.005) and their potential food tree resources. At tree species level, we also found negative, strong and significant correlation between the Pycnanthus angolensis and the C. mona (R= - 0.70 and P= 0.0001), the P. angolensis and Ceratogymna cylindricus (R= -0.82 and P= 0.04). The results of this study support the view that logging in the Korup region has had a negative impact on tree abundance, tree species composition and forest structure. The ecological value of unlogged and logged study sites is not influenced by the difference between unlogged and logged, but by the composition of trees species. The relative differences in food tree abundance between unlogged and logged study sites indicates that logged forest study sites contained a high potential of tree bearing fruits for both primates and hornbills. The relationship between food abundance, primates and hornbills encounter rates, suggest that the studied wildlife species population densities is not influenced by fruit abundance and that food availability is not a limiting factor for primates and hornbills in the Korup region. Other factors such as predation, habitat availability and hunting may contribute to regulate primate and hornbill population densities in the region. Population density of all studied primate species are below carrying capacity observed in tropical rainforests. The studied primate species seem presently not affected by logging activities, however it may require several years before logging to observe significant decline in primates population densities. The low populations densities of primates estimated in this study compared to primates decline earlier observed could be the result of a combination of hunting, logging and extensive farming. Our study suggests the ecological value of secondary forests of the logged study sites compared to grelatively undisturbed (unlogged) forests. These secondary forests may highly contribute to maintain larger populations of primates and hornbills. The management of these disturbed forests as well as the unlogged forests should constitute a priority for the Cameroonian institutions in charge of forests and
dc.contributor.coRefereeKessler, Michael Prof.
dc.subject.topicMathematics and Computer Sciencede
dc.subject.engKorup regionde
dc.affiliation.instituteBiologische Fakultät inkl. Psychologiede
dc.subject.gokfullWNA 500: Tropische Biotope {Biologie, Ökologie}de

Files in this item


This item appears in the following Collection(s)

Show simple item record