Rarity and abundance in a diverse African forest

Abstract

We censused all trees ‡1 cm dbh in 50 ha of forest in Korup National Park, southwest Cameroon, in the central African coastal forest known for high diversity and endemism. The plot included 329,519 individuals and 493 species, but 128 of those taxa remain partially identified. Abundance varied over four orders of magnitude, from 1 individual per 50 ha (34 species) to Phyllobotryon spathulatum, with 26,741 trees; basal area varied over six orders of magnitude. Abundance patterns, both the percentage of rare species and the dominance of abundant species were similar to those from 50-ha plots censused the same way in Asia and Latin America. Rare species in the Korup plot were much less likely to be identified than common species: 42% of taxa with <10 individuals in the plot were identified to species, compared to 95% of the abundant taxa. Geographic ranges for all identified species were gleaned from the literature and online flora. Thirteen of the plot species are known only from Korup National Park (all discovered during the plot census), and 39 are restricted to the Nigeria-Cameroon coastal zone. Contrary to expectation, species with narrow geographic ranges were more abundant in the plot than average. The small number of narrow endemics (11% of the species), many locally abundant, mitigates short-term extinction risk, either from demographic stochasticity or habitat loss.

Structure, diversity, and spatial patterns in a permanent plot of a high Restinga forest in Southeastern Brazil

“…Th e considerable change in species rank order among size classes, including changes in the most abundant species in the sample, confi rms that the contribution of a given species also depends on the tree-diameter cutoff (Valencia et al 2004;Kenfack et al 2007). And these changes are not related exclusively to the presence of small-sized species in the understory.…”

Floristic and structural changes in secondary forests following agricultural disturbances: the case of Lama forest reserve in Southern Benin

“…Therefore, the Lama SF recovers the diversity of the OGF. In well diversified forests of Central Africa, Kenfack et al (2007) and Gourlet-Fleury et al (2012) found Fisher's α > 30 and this corresponded to richness of more than 87 species ha -1 against 12 to 16 species ha -1 in Lama forest. Moreover, in the highlands of Lebialem (Bangang forest, Western Cameroun), a 48 to 72 species per ha and a maximal diversity (2.97 < H' < 5.80 bits and 0.52 < Eq < 0.96) was observed by Tiokeng et al (2015).…”

“…The basal area and the diameter of OG1 were low maybe because of past-logging. The basal areas and densities of Lama OGF were less than those of the semi deciduous forest of Central Africa (Kenfack et al, 2007;GourletFleury et al, 2012) and suggested a low stocking of that forest.…”

Demographic variation and habitat specialization of tree species in a diverse tropical forest of Cameroon

“…Elevation within the plot ranges from 150 to 240 m above sea level, covering diverse topography. The southern half is flat, with a valley bottom that contains a permanent stream flowing westward, whereas the northern section is steep, with gullies and large boulders (Thomas et al 2003;Kenfack et al 2007). The vegetation of the plot is a mature, closed-canopy, moist evergreen forest, with no sign of recent or ancient human disturbance.…”

“…The plot had 328,503 individuals in the first census, including 489 distinct taxa. Of these, 395 taxa are now fully identified species, matched with keys and herbarium specimens, including several that are newly described (Kenfack et al 2007), 73 taxa are identified to genus, and 21 taxa remain unknown, yet are consistently recognizable. Fewer than 500 trees remain unidentified, not sorted into any of those 489 taxa.…”