TROPICS 3 Ql0:277-293 lssued March, 1994 Vegetatlon and Llst of Plant Specles ldentlfled ln the Nouabal€-Ndokt Forest, Congo* Jean-Marie MOIJ"TSAIEOTE Cente dEnrdes sur les Ressouroes V6g€taleq B.P. l249,Baz.avnb,Curgo Takakar,u YuProro Faculty of Science, Kobe University, Nada, Kobe 657 , Japan Masazumi MIrlNt Division of Ecology, Museum of Nature and Human Activities, Hyogo. Sanda, Hyogo 669-13, Japan TomoaKi NTSHIHARA Laboratory of Human Evolution Studies, Faculty of Science, Kyoto University, Sakyo, Kyoto 606, Japan Shigeru SuzuKI Laboratory of Human Evolution Studies, Faculty of Science, Kyoto University, Sakyo, Kyoto 606, Japan SuehiSA KURODA Laboratory of Human Evolution Studies, Faculty of Science, Kyoto University, Sakyo, Kyoto 606, Japan Abstract This paper lists plant species collected and identified in the Nouabal6-Ndoki Forest in northern Congo in the period from 1988 to 1992. It describes also the vegetation types and parts observed of plant foods eaten by gorillas and chimpanzees. The plant species composition led to grouping three vegetation types in the forest: mixed species forest, swamp forest, and monodominant forest of Gilbertiodcndron dewevrei, Another two vegetation types, secondary forest and riverine forest" exist in the outer fringes ofthe study site. collected plants contained 417 species (278 generu 86 families)' ofwhich 400 were totally identified. Seven plant species were added to the flora of Congo. Key Words: vegetation/ Baka I Gorilla gorilla gorilla I Pan troglodytes ffoglodytes I food plant The Republic of Congo is located in the cenfial part of the African continent. It covers an area of about 342,000 km2, straddling the Equator between 334'N-500'S in latitude and llll'E-1835'E in longitude. The human population was about 2.2 million in 1990. However, about half of the population live in two urban areas, Brazzaville, the capital, and Poinle- Noire, in the south. The density in the northern forested area, on the other hand, is very low, and most areas remain undisturbed. The climate is equatorial, although it varies according to the altitude. Rainfall in the central and southern regions have bimodal peaks in November and May. In the northern regions, the latter peak appears in September through October (IJtouzey, 1968; Vennetier' 1977).111e annual rainfall in the northern regions ranges from 1200 ("Plaines du Niari" in the south) to 2000 mm (around "Plateau Koukouya" in the central near Gabon). The mean annual temperatures are between 23 and 27oC (Letouzey,1968; Vennetier, 1977). There are two major vegetation types, i.e., tropical forest and savannah. The tropical forest covers about *: Reprint is available on request to: Masazumi MTANI, Division of Ecology, Museum of Nuure and Human Activities, Hyogo. Yayoi-ga-oka 6, Sandq Hyogo 669-13' Japan. 278 J. MOUTSAMBOIE, T. YUTT,TOTO, M. MnANI, T. NTSHIHARA, S. Suzuru & S. Kunopa 60Vo of the toal area, i.e., Mayombd forest (37o), Chaillu forest (ll7o), the northern forests (3l%o), and the other forests (ISVo). Savannahs, grasslands and swamps cover about 35Vo of the remainder. Congo is one of the top countries in the world for primate diversity (Mittermeier & Oates, 1985), and among the African countries for amphibian and swallowtail butterfly diversity (McNeely et al.,l99O), although nationwide survey is incomplete yet. Yellow-backed duiker (Ceplalophw sylvicultor Afzelius), bongo (Tragelaphus euryceros Ogilby), western lowland gorilla (Gorilla g. gorilla Savage & Wyman), Tschego chimpanzee (Pan t. toglodytes Blumenbach) and African elephant (Loxodonta africaru Blumenbach) are found in northem forests (see Mitani, l99&a; b). Forest conservation, in particular in the northem regions, is regarded one of the most important goals in Congolese policy and research projects. Botanical surveys in southern and central regions have been canied out, and are under way, except the areas bordering Cabinda and Gabon. The surveys have recorded about 4,500 plant species (c/ Sita & Moutsambotd, 1988). On the other hand, the northem Congo, such as Cuvette, Sangha and Likouala districts, except the southernmost area of Sangha, is least surveyed. This incomplete knowledge of the Congolese flora hinders assessing its degree of diversity and endemism. Botanical survey in the northern Congo started in 1989, mainly in the Nouabald-Ndoki Forest. This action clarified that the northern regions, in particular the Nouabalc-Ndoki Forest, have large potential for plant taxonomy (Moutsambot6, 1991; in press; this study) and other botanical fields. Primatologists have mainly carried out, and still are now conducting studies in the southwest€m part of the forest (Mitani, 1990a; 1990b; 1992; Kuroda, 1992; Nishihara, 1992; Mitani et al., 1993). Fay et al. (1989) and Fay & Agnagna (1992) also reported density estimates of western lowland gorillas for a wider area including the Likouala disrict Elephant ecology is another focus in northern regions in Congo (Fay & Agragna, l99l). The studies of elephant ecology also cover a wider area which includes the northwestern paxt of Cuvette district and the Dzanga-sangha reserve in C.A.R. (Caroll, 1988; Fay, 1989; Fay, l99l), an adjacent reserve ofthe present study site across the country boarder. himatological studies are also under way in the Dzanga-sangha reserve (Carroll, 1986; 1988; Fay, 1989; Remis, 1993). STUDY SITE AND METHODS The Nouabal6.Ndoki Forest The Nouabald-Ndoki Forest, which covers an arca of about 400,000 ha, is located between 2IO'N-300'N in latitude and 1611'E-17m'E in longitude. The forest became the Nouabal6- Ndoki National Park in September 1993 (WCS, 1993). The forest has no pennanent human population. The site is near the border to C.A.R. and Cameroon (for location of the study site, see Fig. 1 in Mitani et al.,1993\. The geomorphology consists primarily of plateaus traversed by slightly sloped valleys (300-600 m a.s.l.). In the southwest of the area the elevation decreases. Rivers have wide flood plains dominated by swamp forest along them. The soils on the plateaus are primarily ferric oxisols, and the valleys mostly hydromorphic ferric oxisols. Sampling methods and the ptant list All botanical samples were collected in the southwestem part of the forest, from both right Plant list in Nouabal6-Ndoki, Congo and left banks of the upper Ndoki River. Samplings were made both systematically (along transects) and opportunistically. (The data from the transects are now under study.) J.-M. Moutsambot6 identified the specimens at Centre d'Etudes sur les Ressources Vdg6tales (C.E.R.V.E.) in Brazzaville. Voucher specimens ale deposited in the Herbarium of C.E.R.V.E. (BZV) in Congo, and the Herbarium of the Museum of Nature and Human Activities, Hyogo (HYO) in Japan. For describing dominant tee species, nees 30 cm or more in DBH were selected. The list of plants (Table l) shows the following: scientific name, life form, vernacular name (Baka), parr eaten by apes. Nomenclature follows the CRONQUIST system and partly follows Tutin et at. (1994) (see Yumoto et al., 1994). Life form was defined as follows: Herb (H): Non- woody monocotyledons and dicotyledons, including sedges, grasses and herbaceous vines' Fern (F): Members of the Pteridophyta. Palm (Pal): Members of the Palmae. Liana (L): Climbing woody plants that depend on other plants for support. Shrub (S): Woody plants that do not exceed 2 m in height. Tree (T): Woody plants that exceed 2 m in height. Epiphyte (E): Plants that require support of host. Parasitic epiphyte (PE): Members of the Loranthaceae. Parasite (Par): parasites without photosynthetic organs. Abbreviations of plant parts eaten by apes (G: gorillas; C: chimpanzees) are F: ftuit; S: seed; Vy': flower; L: leaf; P: pittt/ stem/ twig; B: bark; and R: root. RESULTS AND DISCUSSION Vegetation types The following three vegetation types are distinguished in the study site by species composition (for distibution of the vegetation types, see Fig. 2 in Mitani et al.,1993). Mixed specics forest (Fig. 1-a, b) occupies the largest area in the study site. This type is more diverse in plant species composition than the other types. Canopy is not always continuous Fig. 1-a Up view oI Mixed species forest with terrestrial vegetation and understory of Palisota spp. ( Commelinaces€), P s e uderanthemam ladovic ianum (Acanthaceae), and Tabernaemontana penduliflora (Apocynaoeae). Fig. 1-b. Forest floor oJ Mixed srycics forest. A clean understory with Pleiocarpa mutica (Apocynaceae) and Tabemaenontaru pendalillora (Apocynaoeae) is seen in this picture. 280 J. Moursnwore, T. Yutvtoro, M. MnANr, T. NIsHTHARA, S. Suzuru & S. Kunope Table l. A Check-List of Plants Identified in the Nouabat6-Ndoki Forest Local name: named by Baka people; - indicates that local names werc not collected; and / indicates when plural local names were collected. See STUDY SITE AND METHODS for definitions of Life form and Part-eaten by apes, e.g., G(F) means that gorillas were observed to eat fruits of the species, and C(L,B) means chimpanzees were observed to eat leaves and bark of the species. * indicates expected ape species from trace. Plant species Local name Life Part-eaten form by apes PTERIDOPHYTA Adiantaceae P ity r o gr ammo c alome lanos (L.) Link jefame Davalliaceae Arthropteris monocarpa (Cord.) C. Chr. tele/kopozo F Oleandra distentaKtzn jafame F Lomariopsidaceae B olbitis gaboonensis (Hook.) Alston japame F,E Lomnriop sis c on goensis Holtt. F,E Nephrolepidaceae Nephrolepis bisserata (Sw.) Chott jefame F Polypodiaceae Lonchitis currori (Hook.f.) Mett. ex Kuhn jafame F Platycerium angolense Welw. ex Hook. F Platycerium stemoria (P. Beauv.) Desc. :ru F Pteridaceae Pteridium aquilinum vu. caudatum (L.) Kuhn uya F GYMNOSPERMAE Gnetaceae Gnetwn africanun Welw. koko/ekali L c(L) Gnetwn buc hholzianum Engl. koko L ANGIOSPERMAE DICOTYLEDONEAE Acanthaceae Acanthus montanras (Nees) T. Anders. mbaka H Adathoda buchholzi (Lindau) S. Moore ndolu H C ros sandra guineensis Nees gindi s c(L) P s e ude r ant hemwn ludovianurn (B uttner) Lindau H Thomandersia laurifulia (T.