Woody vegetation groups and diversity along the altitudinal gradient in mountain forest: Case study of Kahuzi-Biega National Park and its surroundings, RD Congo
By: Gérard Imani, Louis Zapfack, John Kalume, Bernard Riera, Legrand Cirimwami, Faustin Boyemba
Key Words: Forest type, Woody distribution, Diversity, Altitude, Mountain forest.
J. Bio. Env. Sci. 8(6), 134-150, June 2016.
This study aims to determine the type of mountain forests in the Albertine Rift, to understand the distribution of woody species DBH ≥ 10 cm and their diversity. The investigations were conducted within 30 plots of 1 hectare located in Kahuzi Biega National Park and surrounding areas in DR Congo into mountain forest only. In total 16 797 individuals belonging to 212 specific taxa, 161 genera and 66 families were asses. Four forests types were identified along an altitudinal gradient using a hierarchical clustering (HCS) coupled to a correspondence analysis (AFC). These types are sub-mountain (1250-1500 m), lower mountain horizon (1500-1800 m), medium mountain horizon (1800-2400 m) and upper mountain horizon (2400-2600 m). Each forest type is characterized by a specific number of indicators species. The Sarcochore is the dissemination mode which dominates in the lower altitudes (1250-1800 m) and the Ballochore within higher altitudes (1800-2600 m). Based on the analyzes of variance (ANOVA), regression and correlation, the results showed that in general woody diversity decreases as altitude increases but exceptionally, only the specific abundance was positively correlated with the elevation. The additional study of the structural variability in forest types distinguished remains important to improve the understanding of functioning of these mountain ecosystems and ensure their better sustainability.