Vegetation patterns in tropical forests of the Rumpi Hills and Kimbi-Fungom National Park, Cameroon, West-Central Africa

Abstract

Western Cameroon is thought to hold rich biodiversity and diverse vegetation types, and contains two important forest reserves: Rumpi Hills Forest Reserve (RHFR), which is lowland to montane forest located in southwestern Cameroon and Kimbi Fungom National Park (KFNP), which is a semi-deciduous and savanna forest located in northwestern Cameroon. These forest blocks form part of the continental Cameroon Mountains. Thus far, few or limited studies have been undertaken at these two sites to characterise their floristic composition, vegetation patterns, biomass, and carbon stock. Hence, the vegetation of RHFR and KFNP were inventoried from February to November 2015 in detail with the view of describing and understanding the biodiversity and vegetation patterns vis-à-vis elevation gradient. This will enable us to answer the main research questions: How does elevation and vegetation patterns influence species composition, diversity, biomass and carbon in selected wet and dry tropical forests of the Congo Basin? Are plant species equitably distributed among life forms and elevations gradient? What are the extent of land cover changes in RHFR and the KFNP? The objectives of this study were: to characterise vegetation patterns, understand how elevation influences species distributions and diversity, and evaluate biomass and carbon stock per hectare. Furthermore, the study intended to assess the vegetation cover changes over the last few decades in RHFR and KFNP in western Cameroon. RHFR and KFNP were chosen as representative forests because limited ecological studies have been carried out on these forests, and each represented a tropical wet or dry forest, respectively. The floristic composition and vegetation patterns of the reserves were studied in 25 1-ha plots in the RHFR and 17 1-ha plots in the KFNP spread along elevation gradient and different vegetation types. In each plot, the dbh of trees and lianas of diameter at breast height ≥10 cm were measured, and dbh of shrubs <10 cm were measured in nested plots of 10 m x 10 m. Remote sensing data (Landsat images) was downloaded from the Global Land Cover Facility (GLCF) and United States Geological Survey (USGS) websites to assess forest cover changes. Forest cover changes over time were compared for both sites. Satellite images from Rumpi Hills (2000 and 2015) and Kimbi Fungom forest (1979 and 2015) were used to compare past and present vegetation (forest cover changes over time). Phytosociological parameters such as basal area, relative density, relative dominance, and relative frequency were used to described forest structure and composition. The statistical program “PAST” version 2.17 was used to calculate species diversity and richness. Allometric equations were used to evaluate above ground biomass and carbon stock.