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

Chapter 4
Mean temperature is around 24.7°C and relative humidity varies between 58% and 67%
with an average of 63% (Rakotonirina 1996; Sorg and Rohner 1996). The canopy
reaches 10-12m in height. Trees with DBH50%) consists of fruits and/or seeds so
they may be considered as possible seed dispersers. Two lemur species were studied in
more detail for this study. These were Eulemur fulvus rufus in KIR and E. f. collaris in STL
and Cheirogaleus medius at both sites. These species, particularly E. fulvus, are
supposed to represent very important, if not essential, seed dispersers in Malagasy
forests (Ganzhorn et al. 1999a).
Phenology and pluviometry
In STL a phenological transect with a total of 423 individual trees belonging to 95 species
and 43 families was set up by AB and GD and monitored between January 2000 and
January 2001. Trees sampled for phenology had a DBH>5cm and an effort was made to
obtain five individuals per species whenever possible. Twice a month, presence or
absence of young leaves, flowers, unripe and ripe fruits were recorded. A Tru-Check Rain
Gauge was installed at the campsite in December 1999. It was checked and emptied
each morning around 06h00. during the whole study period. For KIR rainfall and
phenological data were taken from Sorg and Rohner (1996) involving 80 individual trees
of 56 species (26 families) monitored over several years (1978-1987). For the present
phenology analysis only large overstory tree species were considered. Small trees,
shrubs, vines and epiphytes were left out in order to allow comparison between sites. A
subsample of both phenologies (STL: 54 spp., KIR: 32 spp.) was extracted to include only
those plant species that had been characterised morphologically (see below).
Plant and fruit characteristics
In STL and KIR fruits of 173 and 171 plant species belonging to 58 and 47 families
Morphological characteristics
Variables used to characterise fruits were:
Growth form of parent plant: large tree, small tree and shrub, others
(including herbs, vines and epiphytes);
Fruit type: berry, drupe, capsule, pod, samara, synconia, others;
Pulp type: juicy soft, juicy fibrous, dry fibrous, aril, no pulp;
(in phenology ‘fleshy’ fruits are characterised as juicy soft, juicy fibrous or arillate; ‘nonfleshy’
fruits are dry fibrous or do not have any pulp);
Colour: yellow-orange, red, purple, brown, green, others (black, grey and white),
(multicoloured fruits were put in the category of the most conspicuous colour present);
Odour: absent, present;
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