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

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Phenology al. 1999; Morellato 2000). It makes biologically sense that this occurs more for fruiting than flowering as unripe fruits often take a longer time to mature than flowers. Comparison between phenological transect and fruit trail By selecting trees above a specific size as in the phenological transect, one makes the assumption that trees with a DBH smaller than 5cm are unable of producing fruit. In this way all smaller trees, shrubs, herbs, epiphytes and vines are excluded, although they may influence overall fruiting patterns. Our data revealed that fruiting patterns in general were indeed correlated between both methods. This trend was found as well in a study by Wallace and Painter (2002) when comparing between both methods. However, when considering ripe fruits only it was evident that in Sainte Luce during austral winter smaller vegetation forms carried more ripe fruits than the phenological transect showed. Thus, fruit trail data compensate for the underestimation of smaller trees and shrubs in phenological transects. As both methods are complementary it is useful to include both to get the global picture and reveal different phenological trends for large trees and other life forms. Furthermore fruit trails have the advantage of adding a density effect to the data as this is a more quantitative phenological approach where all trees in fruit encountered on the transect are scored each month. On the contrary, during phenological transects, only phenophases of a fixed number of tree species are scored, which represent only a sub-sample of all tree present in an ecosystem selected on their DBH. Moreover, phenology transects are especially appropriate for scoring resource availability for arboreal frugivores, while fruit trails are more appropriate for terrestrial frugivores (Wallace and Painter 2002). In this respect we can explain the lag in time in periods of fruit scarcity between both methods as in phenology only fruits in the canopy are scored, which are earlier available than the subsequently fallen fruits, that are included in fruit-ontrail-counts (cf. Wallace and Painter 2002). To conclude, combining both methods is ideal to get insight into the complete food availability for the frugivorous guild as a whole. Furthermore, our results show the importance of differentiating between unripe and ripe fruits in both methods, which often lacks in other studies, to indicate the ‘true’ severity of bottlenecks in fruit availability that frugivores face in tropical forests. Comparison with other Malagasy sites Since methodologies and representation of data differ between sites, we restricted our comparison to general phenological patterns. In eastern humid forests (Ranomafana and Sainte Luce, Table 4) flushing coincides with the wettest period of the year. In the dry semi-deciduous and deciduous forests the emergence of young leaves starts at the end of the dry season and attains a peak at the onset of the rainy season (Table 4). Given the much stronger seasonal climate of dry forests, where flushing is restricted in time, young leaves anticipate the first rains and create the possibility for plants to maximally benefit of the favourable rainy season. In all sites flowering seems to occur in October and November. As mentioned before, flushing and flowering occur close in time and are both triggered by high irradiance (Van Schaik et al. 1993), which is elevated in these months when rainfall is ubiquitously low and the sky rarely covered. Fruiting patterns are much more diverse between sites and peaks differ from site to site. In Ranomafana, Nosy Mangabe, Montagne d’Ambre and Sainte Luce fruiting occurred at the same time as flowering and flushing (Table 4). The dry forests may have fruiting peaks in austral summer (Meyers and Wright 1993), winter (Curtis and Zaramody 1998; Rasmussen 1999; Yamashita 2002) or throughout the year (Sorg and Rohner 1996). In summary, the 29
Chapter 1 Malagasy rainforests display an associated pattern for all phenophases, while in the dry forests phenophases are more spaced in time (Kappeler and Ganzhorn 1994; Curtis 1997; Rasmussen 1999). Therefore, the lean fruit period in the littoral forest and mid altitude rainforest does not appear to be compensated by flower and/or young leaf bursts. This pattern together with significant inter-annual variation in food availability may explain the lower frugivore biomass in humid forests as opposed to dry forests (Ganzhorn et al. 1999b; Donati 2002). CONCLUSION While the littoral forest can be considered aseasonal regarding climate, there are however consistent year to year patterns in flowering and fruiting. Intra-annual differences occur in phenophases leading to periods of abundance and scarcity. Typically for the littoral forest and other Malagasy humid forests in general but very different from dry Malagasy forests, is the inter-correlation of all phenophases that peak almost simultaneously in the wettest period (November-February). Irradiance seems to be the most important abiotic factor in triggering phenophases, due to its importance in photosynthetic processes especially at this extreme southern latitude for a tropical wet forest. Fruit trails and phenological transects have shown to be complementary methods by unravelling fruiting patterns of different life forms and different sub-samples of all present plant species, including both fruit data on canopy and ground level. ACKNOWLEDGEMENTS This study was carried out under the Accord de Collaboration between Department of Animal Biology and Department of Anthropology of the University of Antananarivo, the Institute of Zoology of Hamburg University and QIT Madagascar Minerals (QMM). Our thanks go out to QMM for providing logistics and infrastructure at the campsite. In particular we acknowledge Manon Vincelette, Jean-Baptiste Ramanamanjato, Laurent Randrihasipara of the QMM Environmental and Conservation Team for following up phenology and climatic data (QMM unpubl. data) at the site after we left and sharing these data with us. Many thanks as well to Give Sambo and Dauphin Mbola, the two local field assistants who helped with the collection of phenology and fruit trail data. The first author is supported by a grant of the Belgian Fund for Scientific Research, Flanders (FWO). We further thank the Flemish Government for structural support to the Centre for Research and Conservation (CRC) of the Royal Zoological Society of Antwerp (RSZA). The second author was supported by a doctoral grant of the Italian Ministry for Scientific Research (MURST) and the University of Pisa. Many thanks as well to Jörg Ganzhorn, Linda Van Elsacker and Silvana Borgognini Tarli for their support during our research. 30
Page 1 and 2: Fruit-frugivore interactions in a M
Page 3 and 4: Cover photographs: Front: Back: -
Page 5 and 6: Table of contents III. General conc
Page 7 and 8: Acknowledgements A special word of
Page 10: PREFACE Preface This work brings to
Page 13 and 14: General introduction Finally, seed
Page 15 and 16: General introduction high as 98% fo
Page 19 and 20: ’Hazo tokana tsy mba ala’ One t
Page 21 and 22: Chapter 1 changes in resource avail
Page 23 and 24: Chapter 1 For analyses we narrowed
Page 25 and 26: Chapter 1 Fig. 2. Seasonal variatio
Page 27 and 28: Chapter 1 80 70 60 50 40 30 20 10 0
Page 29 and 30: Chapter 1 Fig 4. Comparison of data
Page 31 and 32: Chapter 1 Table 4. Data on phenolog
Page 33: Chapter 1 Relation with abiotic fac
Page 37 and 38: Chapter 1 Appendix I Continued Fami
Page 39 and 40: Chapter 1 Appendix I Continued Fami
Page 41 and 42: Malagasy proverb Drawing © Giusepp
Page 43 and 44: Chapter 2 the successful establishm
Page 45 and 46: Chapter 2 40 Table 1. The frugivore
Page 47 and 48: Chapter 2 Statistical analyses To v
Page 49 and 50: Chapter 2 Overall fruit trap data d
Page 51 and 52: Chapter 2 Table 3. Morphological an
Page 53 and 54: Chapter 2 depressed seeds (Fig. 3a)
Page 55 and 56: Chapter 2 Fig. 3. Ordination plot o
Page 57 and 58: Chapter 2 On a community level the
Page 59 and 60: Chapter 2 Appendix II. Plant-animal
Page 63 and 64: Malagasy proverb Lemur drawing © S
Page 65 and 66: Chapter 3 different consumer specie
Page 67 and 68: Chapter 3 Bollen et al. in press, C
Page 69 and 70: Chapter 3 64 Body 1,2 Body lenght (
Page 71 and 72: Chapter 3 dominant plant families s
Page 73 and 74: Chapter 3 Table 4. Morphological an
Page 75 and 76: Chapter 3 Table 4 Continued Paramet
Page 77 and 78: Chapter 3 Besides testing feeding s
Page 79 and 80: Chapter 3 and do not consume the fi
Page 81 and 82: Chapter 3 (1997) already pointed ou
Page 83 and 84: Chapter 3 1989; Galetti 1993; Saini
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Chapter 3 Appendix I. All plant spe
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Chapter 3 Other SD Hss Rats Rr Ew 8
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Pteropus rufus Feeding ecology of P
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Pteropus rufus number per species a
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Pteropus rufus Table 1 Continued Fr
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Pteropus rufus larger number of spe
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Table 2 Continued Number of seeds/d
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Pteropus rufus Food selection: expl
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Pteropus rufus presence. On the oth
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Pteropus rufus Marshall (1983). Occ
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Coracopsis nigra The feeding ecolog
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Coracopsis nigra fruit pulp (70%) b
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Coracopsis nigra Table 1 Continued
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Coracopsis nigra Table 2. Morpholog
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Malagasy proverb Drawing of fruits
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Chapter 4 Most seed dispersal studi
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Chapter 4 Mean temperature is aroun
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Chapter 4 Number of seeds: 1-2, 3-1
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Chapter 4 Fig. 2. Monthly fruit ava
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Chapter 4 120 Table 3. Soil charact
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Chapter 4 Table 4. Morphological ch
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Chapter 4 Table 5. Biochemical char
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Chapter 4 Chemistry At both sites,
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Chapter 4 considering species numbe
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’Ny valala tsy indroa mandry eo a
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Chapter 5 environmental degradation
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Chapter 5 at a very low density in
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Chapter 5 Table 1. A list of plant
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Chapter 5 (Ganzhorn et al. 1999a).
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Chapter 5 Animals The degree of vul
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Chapter 5 comm.). Mixed species pla
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Chapter 5 data are needed we believ
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General conclusion as in other site
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General conclusion selection pressu
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General conclusion are consumed by
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Samenvatting omstandigheden zijn bo
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Samenvatting vruchtkenmerken. Beide
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Samenvatting zaadverspreiding moete
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Résumé température et précipita
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Résumé (Sud-est de Madagascar) et
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Résumé des frugivores sur l’év
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References Bollen A, Van Elsacker L
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References Dowsett JR (2000) Le sta
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References Godfrey LR, Junger WL, R
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References Janson CH, Chapman CA (1
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References Marshall AG (1983) Bats,
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References Rabevohitra R, Lowry PP,
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References Tattersall I (1982) The
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family Loganiaceae scientific name
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