Tree Inventory of the Dja Faunal Reserve, South Cameroon.

Bonaventure Sonké

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. 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:

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).

Collection of the data in the field was funded by the European Union project ECOFAC.

The dataset was collected between August 1993 and August 1995.

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.

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).

The dataset presented here was collected over a period of three years.

Data was collected in 9 different sites across the reserve as illustrated in Fig. 1.

13.666667 and 2.833333 Latitude; 12.333333 and 3.5 Longitude.

The dataset contains a total of 11546 tagged individuals representing 312 total taxa identified to species level (Table 1) belonging to 54 families and 213 genera (a few photos of selected species are provided in Figs 2, 3). For 60 genera some individuals remained unidentified (marked as sp.). This is mainly related to the poorly known taxonomy of those genera or lack of appropriate material (e.g. flowers) to provide a definite determination. The raw data is available in Suppl. material 1.

a

b

Figure 2.

Selected species found in the Dja Faunal Reserve (1). (Photos: TLP Couvreur)

a: Monodora myristica (Annonaceae)  
b: Amphimas pterocarpoides (Fabaceae)  

a

b

c

d

Figure 3.

Selected species from the Dja Faunal Reserve (2). (Photos: a, b: TLP Couvreur; c, d: B Sonké)

a: Greenwayodendron suaveolens (Annonaceae)  
b: Annickia affinis (Annonaceae)  
c: Rothmannia lateriflora (Rubiaceae)  
d: Pauridiantha floribunda (Rubiaceae)  

Of the 54 families Fabaceae, Rubiaceae and Malvaceae were the most species rich (Table 2) whereas Fabaceae, Phyllantaceae and Ochnaceae were the most abundant families in terms of individuals sampled (Table 3, Fig. 4, Suppl. material 3). Finally, Tabernaemontana crassa (Apocynaceae) was the most abundant species recorded for the reserve with 633 individuals tagged (Table 4). Species diversity and abundance per family for each transect is given in Table 5.