Floristic Structure and Diversity of a Tropical Sub-Montane Evergreen Forest, In the Mbam Minkom Massif (Western Yaoundé)

Abstract

The aim of this work was to study the floristic structure and diversity of the sub-montane forest of the Mbam minkom massif of Yaoundé region, in order to establish its structure and its features in relation to the other submontane forests of Africa and Madagascar, and Neotropical zones.We listed all plant species of evergreen sub-montane forests on the upper summits of 12 hills (1000 to 1295m) of the Mbam minkom massif. An area of 0.5 ha was inventoried per hill, using randomly 5 surfaces 25 × 40m (0.1 ha) plots, of a total area of 6 ha. Ligneous plants (≤1 cm diameter at breast height) were inventoried: -324 vascular species, 65 genera and 42 families were recorded; -150 herbaceous species; -122 shrubs 1≤ dbh < 10cm; -146 ligneous species 10cm ≤ dbh.The species-accumulating curves showed a high diversity in the category 10cm ≤ dbh than those of shrubs 1 < dbh >10 cm. The minimal area was reached at 5.5 ha inventoried.For the category 10 cm ≤ dbh, stem density was 544 stems ha -1 and basal area 52.72 m 2 ha -1 .Species diversity as measured by Shannon diversity index was 4.95. Most species (67, at least 77%) were common (densities > 1 stem ha -1 ), and widely distributed among hill forests (36, at least 41%). Gacinia lucida is the species having the highest IVI value (58.52) and Clusiaceae the family having the highest FIV value (60.01), is mesothermal. The forest is also marked by the abundance of Sterculiaceae, Burseraceae, Myristicaceae, Meliaceae, Oleaceae, Leguminosae, Annonaceae, Apocynaceae and Olacaceae. These are megathermal families (or hydromegathermal) that present their maximum occurrence at the basal and average altitudes.The Mbam minkom submontane forest presents the features of an ecotone. The hydromegathermal

The effect of elevation on species richness in tropical forests depends on the considered lifeform: results from an East African mountain forest

“…rainforests (Richardson et al 2004;Kumar et al 2014;Noumi 2015;Koenen et al 2015). Fabaceae is recognized as one of the richest families in African lowlands (Amani 2011;Gonmadje et al 2011;Noumi 2015).…”

Floristic Inventory of Woody Species of the Oku Sacred Forest in the North-West Cameroon, Theoretical and Philosophical Approach

“…Among these last one has in the Oku sacred forest 2 Araliaceae (Schefflera abyssinica and Schefflera mannii) and 2 Moraceae (Ficus chlamydocarpa and Ficus thonningii) whose dbhs reach 2m and more. (Lejoly, 1996); Monte Alèn (Van Reeth, 1997); Dja (Sonke, 1998); Kouoghap (Noumi, 2012); Manengouba (Noumi, 2013); Mbam minkom (Noumi, 2015); Oku (present study, the lower curve). The structure the Oku sacred mountain forest is in a high range as the montane Shola forests of the Nilgiris (Mohandass and Davidar, 2009).…”

“…On the other hand, in Oku sacred forest Araliaceae and Myrtaceae are the much more dominant and more abundant. At the present state of research in the description of the composition of the Cameroonian rainforests of altitude (submontane or transition forests and highlander forests), the above cited families, indicated like being the most representative, distribute themselves in 4 groups on the slopes and the humid and rainy reliefs, as followed (Noumi, 2015): D'Amico and Gautier, 2000), 6 th with an FIV value of 14.71 at Yasuni (Balslev et al, 1987), 10th with an FIV value of 8.3 at Alto Ivon (Boom, 1986), 14 th with an FIV value of 7.79 at Jenera Herrera (Spichiger et al, 1996).…”

“…A similar value (12 species) was found at Andohahela, Madagascar (Rakotomalaza and Messmer, 1999). In the submontane forests the number of species that reach 50% of individuals decreases with the altitude: -17 species (52.01% of individuals) at Messa in Cameroon (Tagne, 2007); -15 species (52.53% of individuals) at Kupe in Cameroon (Tchoua, 2014); -6 species (50% of individuals) at Kala in Cameroon (Madiapevo, 2008); -5 species (54.07 of individuals) at Mbam minkom in Cameroon (Noumi, 2015).…”

“…These studies highlighted quantitative measures for families and the species diversities of these forest types. Some investigations in the submontane and afro-montane forests have been conducted following similar methodology (Mohandass and Davidar, 2009;Noumi, 2012Noumi, , 2013Noumi, and 2015. Could the structural characteristics and the species diversity of the Oku sacred forest permit a singular scientific status just as its current social status?…”