Fruit-frugivore interactions in a Malagasy littoral forest - Universiteit ...

Conservation
contribute disproportionately to the diets of certain species, detailed data on food supply
are indispensable (Chapman and Peres 2001).
Corridors and plantations
As degradation and fragmentation are quite advanced in the littoral forest, active
protection of the remaining intact forest and control of hunting, logging and fires is not
enough to conserve and restore this ecosystem. Furthermore, natural regeneration via
secondary forests is too slow to counteract the loss of primary forests. Therefore, it is
necessary to accelerate the natural recovery process. In this respect, creation of corridors
that connect isolated primary forest remnants with thin strips of habitat is considered a
prime target for conservation activities (Ganzhorn et al. 1997; Beier and Noss 1998). In
this respect, QIT Madagascar Minerals (2001) has installed a corridor in 1999 in between
M4 and M5 in Mandena with 20% endemic species and 80% exotic species. Corridors
are valuable conservation tools, promoting increased plant and animal movement among
patches that will enhance population viability and likelihood of recolonisation, as well as
facilitation of pollination and seed dispersal (Beier and Noss 1998; Tewksbury et al. 2002)
As some species readily move between fragments, using habitat corridors, others do not
(Chapman and Peres 2001). Reasonably, seed of forest plant species will be dispersed
at greater distances from their source through continuous forest than through open field
or pasture, so corridors should ideally be contiguous with the native forest seed source
(Wunderle 1997).
In Sainte Luce, S9, S17, S6 and S7 are not too far apart and could ideally be linked
by corridors in the near future so that reforestation can happen from these nuclei. Birds
and flying foxes are of great importance during first succession stages dispersing pioneer
and heliophil species. After three years the ground is effectively shaded by their canopy
that climax species will then predominate in seedling growth, provided the seed source is
brought into these parcels by flying foxes, fruit pigeons, bulbuls and in a later phase even
mouse lemurs. As the corridor gets more ample dwarf lemurs and eventually E. f. collaris
will make use of them as well, dispersing certain seeds. If we depend entirely on natural
seed dispersal to bring tree species to a site, this may result in a secondary forest
dominated by a well-dispersed subset of the forest flora. Unassisted succession has
proven to be better at restoring biomass than biodiversity (Corlett 2002). In this respect
large-seeded plant species (for example Canarium boivinii, Diospyros sp., Apodytes sp.
nov.)(Table 1) are less easily dispersed than small-seeded trees and because they have
fewer dispersers, they require planting in subsequent efforts (Terborgh 1983; Janzen
1988; Wunderle 1997; Kitamura et al. 2002. Ingle 2003).
Besides creating corridors, plantations of both native and exotic species can help
regeneration as well while at the same time providing an alternative wood source for the
local people. In this respect QIT Madagascar Minerals has carried out experiments in a
tree nursery for 10 years with different exotic tree species such as Eucalyptus, Acacia
and Casuarina species (QIT Madagascar Minerals 2001), which were found to be
suitable in landscape restoration. They even accelerate natural forest succession by
ameliorating harsh soil and understory microclimatic conditions, suppressing dominant
grasses, improving soil fertility and nutrient availability and attracting seed dispersers
(Wunderle 1997; Holl et al. 2000; Corlett 2002). In the near area of Mandena there are
about 1930ha of plantations, either private, state property or installed by QMM. QMM has
installed 200ha of plantations in Mandena and 2ha in Sainte Luce. So far there are no
plantations in Petriky. QMM intends to grow more plantations every year (Vincelette pers.
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