The return of trees to
cultivated tropical zones
Assisted natural regeneration
ssisted natural regeneration (ANR) has
been used in the Sahel region for more
than 20 years. With the assistance of
Cirad, this method has made it possible to
reconstruct complex agroforestry systems covering
hundreds of thousands of hectares in countries such as
Niger and northern Cameroon. The system can also be used
in humid tropical zones, where the forest has been cleared by
large-scale slash and burn. Following this method of clearance
and the growing of crops, the resulting fallows are vulnerable to the
invasive weed Chromolaena odorata and are very low in biodiversity. On the
Batéké plateau in the Democratic Republic of Congo (DRC), the European project Makala
has been working with the local population to test ANR methods in the last remaining
sections of gallery forest.
© R. Peltier, CIRAD
A
Contacts
Selecting which trees
to preserve
T
he first advice given to a farmer wanting
to grow crops in a section of forest or
fallow land containing trees is to clear
the undergrowth. With the help of a project
agent, the farmer can quickly evaluate the
Selecting trees before clearing a plot on the
potential of the trees present. Central to this is
edge of the Batéké plateau in DRC.
© R. Peltier, CIRAD
the consideration of the species on the plot and
their potential role in providing fertiliser or
useful products such as caterpillars, fruit, firewood, timber or use in pharmaceutical
products. Farmers evaluate the abundance of each species and consider which individual
trees will be preserved during the felling, burning and subsequent growing of crops. As a
result of this process, the farmer selects the trees to be preserved, seeking to ensure they
are distributed to best effect across the land available and to ensure at least one tree of
each useful species is kept. This has to be balanced with the need to avoid excessive
shade (depending on the crown of the trees involved, a density of 60 trees per hectare
will provide cover of around 20%). Each tree to be preserved is identified by a cord or a
painted ring.
Régis Peltier
CIRAD, UR BSEF
Tropical Forest Goods and
Ecosystem Services
Research Unit
Campus international de
Baillarguet
34398 Montpellier Cedex 5
France
[email protected]
Pierre Proces
ULG/Gembloux Agro-Bio
Tech, Belgique
Makala Project
57, Avenue des Sénégalais
Kinshasa-Gombé
D.R. Congo
[email protected]
http://makala.cirad.fr
Selective clearing and growing of crops
Unmarked trees are felled and then sawn or cut for charcoal production. Around the
base of each preserved tree, the land is cleared to a radius of two metres. Residual
branches are only burnt after two or three rainfalls (around 50mm). The felling and
burning reduces tree density to around 30 trees per hectare. The plot can then be
sown with cereals, such as maize. Three months later, the cereal crop is harvested
and cassava cuttings are sown to produce a root crop. The farmer will then consider
which of the trees that have grown back (seeds, shoots or suckers) will be kept. These
are marked with a stake. It is a particularly important step in areas where there are
no large trees. The young preserved trees are thinned and pruned by a weeding team.
Following the harvesting of the cassava, these trees are then left to grow during the
fallow period (lasting six to 12 years), during which the land is reserved for pasture,
the gathering of wild foods, hunting and beekeeping etc.
The progressive introduction of an agroforestry system
The project therefore aims to create a system where trees and crops
can successfully coexist. This system, inspired by ancient practices but
adapted to the current possibilities and needs of farmers, best
preserves the soils and biodiversity, while increasing the resources
available to local populations. In DRC, some 40 different species,
including a large proportion of leguminous plants, have been
preserved using the system.
Effects and encouraging this innovative system
© CIRAD, March 2011
The engineer-researchers from the Makala project are studying the effects of ANR in a
number of areas: specific diversity, the growth of species, the rate at which biomass is
reconstructed, carbon stocks, the spontaneous sowing of species not originally
selected for preservation and the perceptions of local people. It remains necessary to
evaluate how ANR is disseminated: how farmers adapt it to their needs and what land
tenure problems it generates between rights holders and farmers. An estimation of the
medium-term impacts on biodiversity and carbon, the sustainability of the agricultural
and forestry systems, and the economy of local households and of the region is being
conducted. It is being compared with a
scenario ‘without Makala’, in other words with
no protection of trees among crops. We also
have to consider how farmers can be
encouraged to continue these efforts beyond
the life of the current project. One of the areas
being explored is that of forestry funds, such as
those available in Europe, which could be
financed by carbon credits such as CDM
(Clean Development Mechanism) or REDD
(Reduced Emissions from Deforestation and
Forest Degradation).
Example of ANR on an anti-erosion strip in
northern Cameroon.
© R. Peltier, CIRAD
Limiting the destruction of forests
due to itinerant slash and burn.
© R. Peltier, CIRAD
Overcoming the exhausting
transportation of firewood, often
the job of women and children.
© R. Peltier, CIRAD
Partners
• CIFOR, Center for
International Forestry
Research, Cameroon
• CRDPI, Centre de
recherche sur la durabilité
des plantations industrielles,
Congo
• Hanns Seidel Foundation,
Germany and DRC
• Jardin botanique de
Kisantu, DRC
• Services nationaux du
reboisement, DRC and
Republic of Congo
• European Union (EuropAid)
• University of LiègeGembloux/Agro-Bio Tech,
Tropical Forestry Laboratory,
Belgium
• Université de Kisangani et
ERAIFT, Ecole régionale post
universitaire d’aménagement
et de gestion intégrée des
forêts et territoires, DRC
www.cirad.fr