Personnel

Bonaventure Sonké

Study area description

The dataset contains tree inventory of nine 5 km long 5 meters wide transects across the Dja Faunal Reserve. The Dja Forest Reserve is situated at 2°50 – 3°30 N and 12°20 – 13°40 E in southeastern Cameroon, bounded on three sides by the Dja River (Fig. ​(Fig.1),1), a major tributary of the Congo river, within the area known as the southern plateau. Most of the Dja Faunal Reserve is situated at 600–700 m above the sea level and covers 526,000 ha making it one of the largest and best protected areas of lowland rainforest across tropical Africa. The monthly average temperature lies between 23.5 °C and 24.5 °C and the annual rainfall between 1180 mm and 2350 mm. There are four major vegetation types in the Dja: primary terra firme primary forest (74% of total individuals collected occurring in this vegetation type); (ii) secondary forest (8% of total individuals); (iii) gaps (4% of total individuals). Finally, two hydromorphic types were defined as (iv) swamps (11%) and (v) flooded forest (3%). The different vegetation types across each transect are provided in Suppl. material 2. Transects were placed at the following coordinates:

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Figure 1.

The Dja Faunal Reserve, South Cameroon, with the location of the 9 transects (T1-T9). Dark blue lines represent rivers. Light blue lines represent the delimitation of the Dja Faunal Reserve. Yellow patches are degraded vegetation while green and dark green patches represent tropical rain forest. Finer scale vegetation patterns are note represented here. Vegetation types based on Guillaumet, Chevillotte & Valton (IRD; MNHN).

T1: start: 12.8573; 3.3243; end: 12.8622; 3.2824

T2: start: 12.8637; 3.2303; end: 12.8622; 3.2726

T3: start: 12.8695; 3.1752; end: 12.8636; 3.2183

T4: start: 12.8846; 3.0895; end: 12.8787; 3.1325

T5: start: 12.5367; 3.1816; end: 12.5866; 3.1787

T6: start: 12.5958; 3.1936; end: 12.6447; 3.1925

T7: start: 13.3293; 2.9203; end: 13.3301; 2.8792

T8: start: 13.3105; 2.9787; end: 13.3133; 2.9403

T9: start: 13.5287; 3.0510; end: 13.5817; 3.0498

There are local Baka people living in the forest practicing subsistence hunting and gathering, thus there is some minimal human pressure on the forest. The forest has its full compliment of large animals, including Western Lowland Gorillas (Gorilla gorilla gorilla) and African forest elephants (Loxodonto Africana cyclotis) (Dupain et al. 2004).

Sampling description

A line transect approach was chosen to sample forest diversity because it covers the heterogeneity of the forest better than a square plot. We used standardized methods to install the transects, identify, map, measure and re-measure the trees (Baker et al. 2004). Each transect line was 5 meters wide and 5 km long. A total of 9 such transects were done at different places across the reserve Fig. 1. All trees ≥ 10 cm dbh (diameter at breast height, 1.3 m or above all deformities, notable buttresses, if present), were identified, mapped, individually numbered with an aluminium tag and nail, and measured with a diameter tape, or estimated if this the correct point of measurement was not possible to reach. Trees were identified up to species level, and in some cases just up to genus level. Voucher specimens were collected and deposited in different herbaria (mainly YA) and in case of any doubt, supplementary material was collected for further identifications.

Quality control

The present dataset was updated to match the APG III classification of angiosperm families (APGIII 2003) and all species names were checked for validity (spelling and authorship) against online databses (http://tnrs.iplantcollaborative.org/index.html, http://ipni.org; http://plants.jstor.org/; http://www.ville-ge.ch/musinfo/bd/cjb/africa/recherche.php).