The world currently contains approximately 4.14 billion hectares of forests, of which 45% are tropical forests. Tropical forests therefore represent the largest forest biome on Earth and are disproportionately important for biodiversity conservation, carbon sequestration, climate regulation and ecosystem functioning [1][2]. Despite their global importance, they continue to face greater deforestation pressure than other forest types, making their conservation a major international priority [3][4].

Tropical forests are characterized by extraordinary biological diversity and complex structural organization. Their multi-layered vegetation, high species richness, and intricate ecological interactions make them among the most productive and important ecosystems on Earth. Understanding their diversity and structure is essential for conservation, sustainable management, and climate-change mitigation [5][6].

These forests are classified into several major types based on climate, rainfall, altitude, and vegetation characteristics. The principal categories include tropical rainforests, moist deciduous forests, dry forests, thorn forests, montane forests and swamp forests. Each type supports distinct plant and animal communities and provides essential ecological services [7].

A cloud forest is a mountain forest characterized by frequent cloud cover at canopy level, high humidity, abundant epiphytes, and exceptional biodiversity [8]. Globally, tropical montane forests cover about 402 million hectares, whereas tropical cloud forests occupy only 50 - 70 million hectares. Cloud forests therefore represent approximately 12% - 17% of tropical montane forest area. Despite their smaller extent, cloud forests are among the most important ecosystems on Earth because of their exceptional biodiversity, high levels of endemism, water-regulation functions, and climate-regulation services [9][10].

Cloud forests are discontinuously distributed across tropical mountain regions of the Americas, Africa, and Asia [8]. In Cameroon, cloud forests are concentrated in the Cameroon Highlands, particularly on Mount Cameroon, Mount Kupe, the Bakossi Mountains, the Rumpi Hills and Mount Oku [11].

The cloud forest of Mount Cameroon is one of Africa’s most remarkable montane ecosystems, occurring mainly between 800 and 2,500 m elevation, and is characterized by persistent cloud cover, rich epiphytic vegetation, high biodiversity, and numerous endemic species [12].

Mount Cameroon lies along the Gulf of Guinea coast in southwestern Cameroon. The mountain’s geology is characterized by its active strato-volcanic nature, built upon an older basement and sedimentary layers. Its topography is a direct result of its volcanic activity, featuring an elongated summit, steep slopes, and numerous secondary volcanic cones scattered around its flanks. The mountain’s location within the Cameroon Volcanic Line and its proximity to the Gulf of Guinea are critical to understanding its geological and topographical evolution [13].

The eruption history of Mount Cameroon is dynamic, with records beginning from the fifth century, when the Carthaginian explorer Hano, the Navigator named it the “CHARIOT OF THE GODS”. Locations and ages of ancient lava flows are not known, because the clear documentation of their eruption history started with the 1909, 1922, 1954, 1959, 1982, 1999, 2000 and up to 2012 when the last eruption occurred with known vents and lava flow tracts. This stratovolcano is thus made up of overlaying and overlapping lavas of varying ages [14]-[16]. Therefore, the soils of Mount Cameroon are predominantly young, highly fertile volcanic soils (Andisols) derived from the weathering of basaltic lava, pyroclastic deposits, and volcanic mudflows (lahars). Periodic volcanic eruptions continually replenish the landscape with fresh volcanic materials, contributing to high soil fertility and making the surrounding region one of the most productive agricultural areas in Cameroon and West Africa [15][17][18].

The mountain is internationally recognized as one of Africa’s most important biodiversity hotspots. The mountain supports more than 3000 - 3500 plant species and a remarkable diversity of mammals, birds, reptiles, and amphibians. Extending from sea level to 4,095 m, its continuous altitudinal gradient encompasses six major vegetation zones, ranging from coastal and lowland rainforest through submontane and montane cloud forests to montane grasslands and alpine vegetation near the summit [17][19]-[21].

The cloud forest of Mount Cameroon is formed by the rapid cooling of warm, moist air as it meets cooler, high-altitude air from the Gulf of Guinea. It is maintained by frequent orographic uplift and mist condensation, but is periodically fractured by volcanic eruptions and harbours an extraordinarily rich ecosystem. The cloud forest coincides with the altitudinal range of Prunus africanaabundance (the bark extract is used for the treatment of prostate hyperplasia), and out of current range of intense deforesting human activities, makes this forest attractive for both long and short-term biodiversity and ecological studies.

Although Mount Cameroon is one of the best-studied tropical mountains in Central Africa, significant gaps remain in our understanding of the diversity and vegetation structure of its cloud forest ecosystem. Most existing research is based on a relatively small network of plots established in the late 1980s and early 1990s, with detailed analyses largely confined to studies by Payton et al. [22], Proctor et al. [17], and Forboseh et al. [20]. These studies have provided valuable baseline information on altitudinal zonation, forest structure and species composition, but several important questions remain unanswered. A recent study by Seraphine et al. [23] on altitudinal changes in the floral diversity and carbon stocks failed to include a species checklist, and of the few species mentioned as important showed inappropriate identification. Consequently, the current status, trajectory, and resilience of Mount Cameroon’s cloud forest vegetation remain poorly understood, highlighting the need for new permanent-plot studies to provide updated baseline data for conservation and climate change.

The current research was designed to document the vegetation composition and structure of the Mt Cameroon Cloud Forest using permanent plots that will in the future provide useful data on these understudied aspects of Mt Cameroon.

This study recorded a total of 4631 tree stands in all size classes for which DBH was measured, made up of 35 species distributed within 29 genera and 22 plant families for both plots 1 and 2. A total of 1219 (26.3%) individuals comprised of tree stems with DBH ≥ 10 cm that all received tags while the remaining 3412 (73.7%) comprised stems with DBH < 10 cm. Rubiaceae was the dominant family represented by 6 species in 6 genera, followed by Moraceae with 4 species in 2 genera and Oleaceae with 3 species in two genera. There were 15 families represented by only one species.

For trees with DBH ≥ 10 cm, plot 1 (2026 m asl) recorded 19 tree species across 19 genera and 16 families for a total of 653 stands, while plot 2 (1858 m asl) was more species-rich with 25 tree species across 23 genera and 17 families, with 566 stands. There were 7 families, 9 genera and 9 species common to both plots 1 and 2. Nine (9) families, 10 genera and 10 species were unique to plot 1 while for plot 2, 12 families, 15 genera and 17 species were unique (Table 1).

The most abundant family of plot 1 was Rubiaceae [181 individuals in three genera; Ixora (132), Psydrax (38) and Pavetta(11)]. The families Aquifoliaceae (75 individuals) and Oleaceae (71 individuals) came in second and third places respectively. Although the family Rutaceae was represented by two genera, the stem count was small (5) just ahead of Primulaceae with only two individuals and Cornaceae represented by one individual (Table 1). In plot 2, Pittosporaceae recorded a stand density of 112 with one species, Oleaceae had 102 stems in three species, followed by Stilbaceae with 81 individuals in one genus and Prunus africana of Rosaceae with 75 individuals.

Among the common Families in the two plots, Nuxia recorded (60 + 81), Prunus (13 + 75) and Olea (71 + 13) as the most abundant genera, while Zanthoxylum (1 + 1) was the least represented (Table 1).

Data from the trees (<10 cm DBH) censored in the two plots revealed a total stem count of 3412, belonging to 15 families, 19 genera and 19 species. There were 8 families common to both plots, with 7 and 6 unique to each of plots 1 and 2 respectively. The family Rubiaceae was the most represented with five genera (Psychotria with 804 stands, Ixora 200, Psydrax 137, Pavetta 124), in both plots. However, Coffea (25) was recorded only in plot 2. The family Oleaceae followed with one species, (Olea capensis), having 144 individuals from both plots and Nuxiacongesta with 112 individuals in plot two only. The least represented family was Bignoniaceae, with single stand of Kigelia Africanain plot 1 only,followed by Rapanea melanophloeosof the family Primulaceae with 6 individuals in plot one only (Table 2).

Several families, genera and species represented in ≥10 cm DBH size class were absent in the lower size class and vice versa. In plot 1, 11 plant families were represented in both size classes ≥ 10 cm and <10 cm DBH, while in plot 2, only 8 families were common to both size classes.

Four and nine families were present at the ≥10 cm DBH class respectively, while Bignoniaceae and Urticaceae were only present in the <10 cm DBH size class for plots 1 and 2 respectively.

At species level and in plot 1, while the families Primulaceae and Rutaceae were represented at both size classes, their respective species, Maesa lanceolata and Zanthoxylumsp., only occurred at the ≥10 cm DBH class. Psychotria peduncularis of Rubiaceae was only recorded at the ≥10 cm DBH class.

In plot 2, Zanthoxylum was also not represented in the <10 cm DBH size class, while Psychotria, CoffeaandIxorawere only present in the small stem size class.

Table 1. Species composition and frequency of occurrence of stands DBH ≥ 10 cm in two plots within the Mount Cameroon cloud forest.

Table 2. Species composition of stems with diameter < 10 cm in two plots within the Mount Cameroon cloud forest, indicating presence (+) or absence (−).

The herbaceous layer of the cloud forest plots was found to contain 18 plant families, with three (Acanthaceae, Piperaceae and Poaceae) common to both plots. Plot 1 recorded 9 families unique to it, while plot 2 recorded 12 families, with 9 unique. The most abundant family was Acanthaceae with two, followed by Piperaceae with a single species for plot1, while Piperaceae, Aspleniaceae, and Poaceae in that order, recorded the highest counts for plot two. The least represented families were Cyperaceae and Fabaceae for plot 1 and Cyperaceae and Lamiaceae for plot 2 (Figure 1).

Figure 1. Percentage coverage of herbaceous species in plot 1 and plot 2, respectively, of the Mount Cameroon cloud forest.

The calculated values for species richness, Shannon-Wiener index, Pielou’s Equitability index and Simpson’s index for both plots are presented (Table 3).

Table 3. Diversity Indices for species of plot 1 and plot 2 of the Mount Cameroon cloud forest.

Size class distribution for trees with diameter at breast height ≥ 10 cm is presented (Figure 2) for plots 1 and 2 respectively, indicating a reverse J, with more stems at smaller size classes than the very large trees.

Figure 2. Size class distribution of trees plots 1 (A) and 2 (B); Distribution of trees BDH ≥ 10 cm within subplots of plot 1 (C) and plot 2 (D) of the Mount Cameroon cloud forests.

The distribution of woody species with BDH ≥ 10 cm on the forest floor of the two plots showed that subplots 1B, 1C and 1D had the highest number of stems per unit area, while 3A had the lowest for plot 1. Sub plots 3D, 3B and 2C in that order recorded the highest number of stems, while 4A and 2A recorded the least stem count in plot 2 for that DBH class.

Linear dimensions of trees with DBH ≥ 10.1 cm measured in plot 1 mean DBH of 25.9 cm (range 10 - 126.5 cm) for plot 1 and 20.1 cm (range 10.3 - 186.6 cm) for plot 2. The mean height of these same trees in plots 1 and 2 was 20.9 m (range 15 - 27.9 m) and 18.2 m (range 5 - 40 m) respectively (Table 4).

Table 4. Summary statistics of diameter and height of trees with DBH ≥ 10 cm sampled in two 1-ha plots in the Mount Cameroon cloud forest.

Basal area and stand volume calculations for species with DBH ≥ 10 cm indicated a total basal area of 52.057 m² and a stand volume of 601.53 m³ for plot 1. Three species, Ilex matis (BA = 11.98 m², stand volume 138.131 m³), Nuxia congesta (10.002 m², 140.273 m³) and Schefflera manni (8.366 m², 102.442 m³) contributed 58.3% of basal area and 63.3% of the stand volume in this plot. The total basal area and stand volume for the same category of trees in plot 2 were 30.5 m² and 394.7 m³ respectively. Again, three species that contributed a total of 64% of basal area and 67.8% of stand volume in this plot were Strombosia ceylanica(9.922 m², 142.815 m³), Pittosporum undulatum (4.846 m², 56.903 m³) and Prunus africana (4.703 m², 66.406 m³).

The Mount Cameroon cloud forest exhibits many features typical of tropical montane cloud forests. A total of 4631 woody stems were recorded across the two permanent plots, representing 35 species, 29 genera, and 22 families. Of these, 1219 stems had DBH ≥ 10 cm, while 73.7% consisted of smaller stems (<10 cm), indicating active regeneration. Rubiaceae was the dominant family, followed by Moraceae and Oleaceae. The dominance of Rubiaceae is consistent with findings from other African cloud forests, where members of this family are well adapted to cool, humid, and shaded montane environments [39][40].

Species richness varied between plots, with the lower-elevation plot (1858 m) recording 25 species compared with 19 species in the higher-elevation plot (2026 m). This pattern supports the commonly observed decline in species richness with increasing elevation due to harsher environmental conditions such as lower temperatures, persistent cloud cover, and nutrient limitations [39][40]. Only nine species were common to both plots, indicating high floristic turnover and strong beta diversity, characteristics typical of tropical montane cloud forests [10].

The regeneration layer (DBH < 10 cm) also displayed considerable floristic heterogeneity. Common regenerating species included Ilex mitis, Olea capensis, Prunus africana, and several Rubiaceae species, suggesting broad ecological tolerance and their importance in forest regeneration. Numerous species occurred exclusively in individual plots, reflecting habitat specialization and the influence of local environmental conditions on regeneration dynamics [39][41]. The occurrence of Prunus africana is particularly significant because this economically valuable and threatened species is heavily exploited throughout Africa for medicinal bark. Its substantial contribution to stand structure and biomass, especially in plot 2, highlights the Mount Cameroon cloud forest as an important refuge for Afromontane biodiversity and a priority area for conservation [42][43].

The herbaceous layer exhibited similarly high spatial heterogeneity. Eighteen herbaceous families were recorded, but only three families were common to both plots. Acanthaceae, Piperaceae, and Poaceae dominated the understory, while many families were poorly represented. Such patterns indicate strong environmental filtering and microhabitat specialization, which are common features of cloud forest understories [44][45]. The predominance of shade-tolerant and moisture-dependent taxa further confirms the cloud forest character of the study area.

Diversity indices indicated moderate species diversity but low species evenness. Plot 2 exhibited higher species richness (50 species) and Shannon diversity ( H ′ = 1.9) than plot 1 (31 species; H ′ = 1.6), suggesting that lower elevations support greater species coexistence. However, very low Pielou’s equitability values revealed strong dominance by a few species. Similar Simpson’s index values (0.9) in both plots indicate relatively high overall diversity despite uneven species distributions, a common feature of cloud forests where environmental conditions favor a limited number of highly adapted taxa [10][46].

Structural analyses revealed characteristics of mature montane forest. Mean DBH values were 25.9 cm and 20.1 cm in plots 1 and 2, respectively, while mean tree heights ranged from 18.2 to 20.9 m. These values fall within the range commonly reported for African montane cloud forests, which generally possess shorter canopies than lowland forests because of cooler temperatures, persistent fog, and strong winds [47]. The presence of very large trees, with diameters exceeding 120 cm, suggests the persistence of old-growth individuals and relatively low levels of disturbance.

Basal area and stand volume further demonstrated the structural importance of the Mount Cameroon cloud forest. Plot 1 recorded a basal area of 52.06 m²∙ha⁻¹ and stand volume of 601.53 m³∙ha⁻¹, while plot 2 recorded 30.5 m²∙ha⁻¹ and 394.7 m³∙ha⁻¹, respectively. In both plots, a few species contributed disproportionately to total biomass. Ilex mitis, Nuxia congesta, and Schefflera mannii dominated plot 1, whereas Strombosia ceylanica, Pittosporum undulatum, and Prunus africana dominated plot 2. Such biomass concentration in a few dominant taxa is typical of tropical montane cloud forests and reflects strong environmental filtering [45][48].

Overall, the Mount Cameroon cloud forest shares many characteristics with other African cloud forests, including high beta diversity, strong elevational zonation, and dominance by a few ecologically important species. However, the exceptionally high species turnover, significant populations of Prunus africana, and the influence of volcanic history make this ecosystem particularly unique and underscore the need for conservation across the entire elevational gradient.

Its structural analysis reveals a forest with good regeneration, an indication of high potential for carbon sequestration and livelihood of local populations if well managed.

The authors are indebted to Mr. Fancis Luma, Tetuh Elvis, Ameh Kingsley, Kifon Precious, Barry Ashu, Asoh Bian and Mokake, Atembe Juspain for their tireless assistance during the field phase of this work. We also appreciate the Limbe Botanic Garden Herbarium management for their collaboration in identification.