Preliminary report of botanical activities carried out in the Lac Tumba
Landscape, DRC
January - February 2007
Terry Brncic
Université Libre de
Bruxelles
Pisco Menga
Université de Kinshasa
Jean Lejoly
Université Libre de
Bruxelles
Part 1: Botanical survey and collection for the Lac Tumba Landscape
Part 2: Modelling the relationship between modern pollen rain and vegetation in the
Congo basin for interpretation of fossil records
Part 3: Identification of elephant food plants in Mbanzi forest
Part 1: Botanical survey and collection for the Lac Tumba Landscape, Mbanzi
region
The Lac Tumba Landscape contains a wealth of environments, including swamp
forest, terra firma forest, and savannah, providing critically necessary habitat for
populations of bonobos, forest elephants, and forest buffalos, as well as natural
resources for people. In order to better develop management strategies for the
biodiversity of this region, detailed botanical surveys can help us to understand a) the
habitat requirements of flagship mammal species, including the relative abundance of
their food plants, b) the movements of these animals within the landscape, for example
what draws wide-ranging forest elephants to use this area, c) the plant diversity of the
area, including what plants may be endemic and in need of special protection (e.g.
from logging exploitation), d) the dependence of local people on their environment for
food and medicine, and e) the impact that climate change and changes in forest use
might have on the forest and those that rely on it.
The foundation for a robust long-term research strategy towards any of these aims
depends on accurate identification of plants. The scope of this preliminary botanical
survey was not to address the above research questions, but rather to begin to lay this
foundation of botanical knowledge for the Lac Tumba Landscape. To this end, a
preliminary vegetation survey was conducted and voucher specimens were collected,
which are in the process of being accurately identified, preserved and stored at the
University of Kinshasa for easy consultation by future researchers. Doubles of
vouchers were taken to the Laboratoire de Botanique Systématique et de
Phytosociologie at the Université Libre de Bruxelles, Belgium for additional
identifications. A permanent plant dryer was constructed with durable materials and
stored at the WWF base at Tondo.
Plant specimens were collected from both the Botuali area near Lac Tumba, and from
the Malebo area in the Bolobo district. The environments collected in included swamp
forest, seasonally inundated forest, riparian areas, savannah, savannah-forest ecotones,
terra firma forest, and village sites. Whenever possible, fertile specimens were
collected to aid in identification. In total, approximately 500 specimens were collected
at Botuali and 400 at Malebo. A list of specimens with provisional identifications is
attached as an Excel file in Appendix 1. Continuing work on the identification and
preservation of these collections is being carried out by MENGA Pisco at the
University of Kinshasa. He will submit a more complete list and a French version of
the report within the next week. The final product is intended to be a separate storage
cabinet in the herbarium dedicated to WWF research, containing the fully labelled
specimens and a list of species for each area. In order to best preserve these materials,
Bristol paper, card, and storage cabinets are urgently needed. It is hoped that this
collection will be added to and will prove useful for all future scientific research
efforts carried out by WWF in the Lac Tumba Landscape.
Part 2: Modelling the relationship between modern pollen rain and vegetation in
the Congo basin for interpretation of fossil records
Palaeoecological studies of tropical rainforest are providing increasingly specific data
on long-term forest dynamics in response to factors such as climate change, human
disturbance, and natural baseline variability. Interpretation of palynological studies in
species-rich tropical forests is held back by a) a poor understanding of the ecology of
many of the species, b) difficulty in distinguishing pollen taxa within families and
genres, c) a low similarity between modern pollen spectra and modern vegetation, and
d) few modern analogue studies. The objective of this mission in DRC was to address
some of these problems by collecting the data necessary to build a model of the
relationship between modern pollen rain and vegetation for the forests of the Congo
basin. These data will be used to greatly improve the interpretation of palynological
data for this region.
The lack of information on species ecology was addressed in Part 1 by the collection
of botanical samples in savannas, forest, and swamps in the Botuali and Mbanzi areas.
Notes were taken on the habitat for each species collected, which will add to our
knowledge of the ecology of these tropical species. In addition, to improve the
taxonomic resolution of pollen studies, fresh pollen samples were collected wherever
possible from species in the field to be processed and added to an existing pollen
reference collection. The pollen reference collection will be invaluable for identifying
as precisely as possible the pollen found in surface sediments, as well as fossil
sediments. A list of species (provisional identifications) for which pollen was collected
is attached as an Excel file in Appendix 2.
This study approaches the problem of lack of correlation between modern pollen and
vegetation by performing extensive vegetation surveys around two small ponds or
liembos found in logged terra firma forest near Mbanzi. These surveys included counts
of herbs, shrubs, lianas, understorey trees and canopy trees. Surface sediments were
collected from these ponds, from which pollen will be isolated and counted to compare
to the plant survey. These data will be used to calibrate the representativity of each
pollen type with regards to the actual vegetation composition in past environments.
Overall the plots showed high diversity, with as many as 125 species identified around
the first liembo. Ten of the most abundant tree species >10 cm dbh (diameter at breast
height = 1.3 m high) in the Mbanzi forest are Plagiostyles africana, called ‘Enenge’
locally (Euphorbiaceae), Garcinia punctata/epunctata ‘Bosefe’ (Clusiaceae),
Greenwayodendron suaveolens ‘Bolinda’ (Annonaceae), an unidentified ‘Esau-sau’
(Burseraceae), Diogoa zenkeri ‘Bolonda’ (Olacaceae), Millettia laurentii ‘Wenge’
(Papilionoideae), Chaetocarpus africanus (Euphorbiaceae), Isolona hexaloba
‘Bosange’ (Annonaceae), Entandrophragma sp. ‘Kosipo’ (Meliaceae) and
Strombosiopsis tetrandra ‘Eko’ (Olacaceae). The results of the vegetation survey will
be analysed in detail with the pollen data from the liembos and published in a scientific
journal. In addition, the survey data will be used in completing the DEA Mémoire of
MENGA Pisco.
In order to further improve the interpretation of pollen records for Congo basin forests,
we aimed to create modern pollen analogues for a variety of sedimentary basins in a
range of vegetation, soil, drainage and climate types. Surface samples were taken from
multiple sedimentary basins located across a variety of climatic, edaphic, soil,
vegetation, and disturbance types in the lowland forest/swamp/savannah region of
Botuali and Mbanzi. The sites were 24 liembos, forest hollows, and seasonal
streambeds in various habitats, including savannah, old village sites with secondary
forest and cacao plantations, logged and unlogged terra firma forest, swamp forest,
villages and cultivation. These surface samples will be analysed along with samples
already taken from the Nouabalé-Ndoki region of northern Congo-Brazzaville. Pollen
will be extracted from the surface samples and counted to determine the pollen
spectrum for each of the approximately 30 sites. Statistical analysis of the pollen
spectra and multiple environmental factors will be used to create direct environmental
interpretation for fossil pollen spectra. This is the first modern pollen analogue study to
focus on sedimentary basins and provides clearer interpretations for the fossil record.
In addition to the surface samples, short sedimentary sequences were taken using an
improvised bamboo coring apparatus from two liembos and Lac Tumba. These may be
counted in the future and used as preliminary data for future research proposals.
Part 3: Identification of elephant food plants in Mbanzi forest
Research efforts are currently underway in the forest near Mbanzi in order to assess the
status of forest elephant populations. Part of the research strategy is to determine the
habitat use of elephants in relation to their seasonal migrations. To this end,
understanding the diet of elephants is important as the seasonal and long-term
availability of important elephant foods may determine their presence in the area.
While at Mbanzi we examined elephant dung for food remains and were able to
identify seeds from 8 fruit species commonly consumed by elephants in the month of
February, as well as identify other plant species previously observed by WWF
consultant Menard MBENDA to be consumed. This list is from Menard MBENDA
and only some of the scientific names were completed by us.
Family
Annonaceae
Annonaceae
Apocynaceae
Apocynaceae
Burseraceae
Cecropiaceae
Dioscoreaceae
Genus
Annonidium
Desplatsia
Landolphia
Picralima
Santiria
Myrianthus
Dioscorea
species
mannii
dewevrei
nitida
trimera
arboreus
spp.
Local name
Bonenge
Balemo
Notes
seeds in dung
seeds in dung
savannah sp.
seeds in dung
Bokomu
Liane
Euphorbiaceae
Euphorbiaceae
Irvingiaceae
Irvingiaceae
Irvingiaceae
Irvingiaceae
Moraceae
Moraceae
Sapotaceae
Sapotaceae
Unknown
Drypetes
Plagiostyles
Irvingia
Irvingia
Klainodoxa
Klainodoxa
Musanga
Treculia
Autranella
Gambeya
sp.
africana
cf. wombolu
cf. gabonensis
gabonensis
cf. trillesia
cecropioides
africana
congolensis
cf. lecourtiana
seeds in dung
Enenge
Lokengo/Bolenge
Lokengo/Bolenge
Lokengo
Lokengo
Boimbo/mbimbo
Bikoso
Mofambu
Bofalanga
seeds in dung
syn wombolu?
seeds in dung
seeds in dung
seeds in dung
Appendix 1 – Attached Excel file.
Preliminary list of herbarium specimens collected in the Lac Tumba Landscape, JanFeb 2007 (provisional identifications). The list of Menga specimens has been modified
and will be submitted by mid-May.
Appendix 2 – Attached Excel file.
List of plant species (provisional identifications) from which pollen was collected for a
pollen reference collection.