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

More documents

Recommendations

Info

The Malagasy littoral forest: threats and possible solutions AN BOLLEN, GIUSEPPE DONATI (TO BE PUBLISHED) Conservation ABSTRACT The littoral forest is expected to lose numerous endemic plant and animal species in the near future because of deforestation and resultant habitat changes. A great concern is the disruption of plant-animal interactions. It can be predicted that alterations in the recruitment dynamics of plant species in forest fragments might have unknown consequences for their long-term survival. This paper discusses the characteristics of animal seed dispersal relevant to the regeneration of the littoral forest. Possible management implications are discussed in relation to the existing initiatives. Urgent protection of the largest remaining forest fragments (S9, S17), including a flying fox roost site (S6) is of great importance. Furthermore it is necessary to install corridors to connect the isolated fragments and create plantations to fulfil the need for wood of the local people. INTRODUCTION Worldwide, Madagascar is considered a high priority for global biodiversity protection due to high faunal and floral endemism and biodiversity (Mittermeier et al. 1998). The flora of Madagascar is one of the richest in the world in comparison to its area (Dumetz 1999). About 96% of all plant species present are endemic (Schatz 2001). The avifauna is relatively species poor compared to other tropical islands, but the level of endemism is also extremely high (52% Langrand 1990). For mammals, reptiles and amphibians endemism even raises up to 90% (Garbutt 1999), 95% (Ramanamanjato 2000) and even 99% (Ramanamanjato 2000) respectively. At the same time Madagascar is one of the tropical regions where the effects of deforestation are most worrying (Green and Sussman 1990). Ever since humans first reached the island some 2000 years ago, the native forests have provided them with animals for food, land for cultivation and wood for construction and fuel. Humans have thus dramatically changed the island vegetation. According to Kull (2000) dense endemic rainforests cover only 10% of the island, while total forest cover is about 23%. Deforestation is proceeding most rapidly in the east, where 66% of the original rainforest has been logged or irreversibly converted to land for cultivation (Dumetz 1999; Kull 2000). At these rates it is predicted that in the year 2025 rainforest will only remain on the steepest slopes, in remote areas and nature reserves (Kull 2000). Madagascar receives global attention as a hot spot of biological diversity, 133
Chapter 5 environmental degradation and conservation action (Mittermeier et al. 1998; Kull 2000), but at the moment only 3% of the island has a protected status (Godfrey et al. 1997). The littoral forest of south-eastern Madagascar is one of the ecosystems most threatened on this island and is reduced to its vestiges with only 2500ha remaining today, representing at most 10% of the original forest (Ganzhorn et al. 2001; Vincelette pers. comm.). During the last 50 years more than 5000ha have disappeared (MIR Télédétection Inc 1998). This forest type has been severely degraded due to charcoal production, logging, bushfires and shifting cultivation (slash and burn). At the moment it is represented by severely degraded forest fragments, ranging in size from 3 to 377ha. In the Fort-Dauphin area the existing littoral forests on sandy soils are Petriky, Mandena and Sainte Luce (Fig. 1). Sainte Luce has the highest species diversity and can be considered among the most intact littoral forest remaining in eastern Madagascar (Dumetz 1999; Rabevohitra et al. 1996). A botanical study by Razafimizanilala (1996) and Rabevohitra et al. (1996) in the forest fragment ‘S9’ of Sainte Luce shows that 98% of the 189 plant species monitored are endemic for Madagascar and there are 29 endemic plant species for the south-eastern littoral forest (Lewis Environmental Consultants 1992a). In order to highlight the importance of the littoral forest before it completely vanishes, we present here our current understandings of frugivore-fruit interactions. We further discuss the causes of habitat loss and forest fragmentation and imply our knowledge on seed dispersal for landscape restoration. Finally suggestions concerning conservation applications as well as priorities for future research are made. STUDY SITE In this paper we focus in particular on the situation of Sainte Luce, where first and second author conducted two PhD researches from September 1999 till February 2001. The campsite is located in the 377 ha-large forest fragment, called ‘S9’ (24º45'S 47º11'E). Littoral forest lies within 5 km of the coast and occurs on sandy soils at an elevation of 0 up to 20m. It is characterised by a relatively open or non-continuous canopy, which is 6 to 8m in height and diameter at breast height (DBH) of trees rarely exceeds 30 to 40cm (Rabevohitra et al. 1996; Dumetz 1999). This forest type is characterised by an average annual rainfall of about 2,690 mm, with a marked rainy season from November through February. No clear dry season could be detected (Bollen and Donati, Chapter 1). Mean monthly temperature is 23°C (QMM unpubl. data). Fruit production is seasonal, with a peak in abundance of ripe fruits in December and January and with periods of fruit scarcity that differ strongly inter-annually (Bollen and Donati, Chapter 1) THREATS Three villages, Ambandrika, Ampanasatomboky and Manafiafy lie within close range of the largest forest fragments of Sainte Luce; S6 (225 ha), S7 (206 ha), S8 (190 ha), S9 (377 ha) and S17 (244 ha)(Fig. 1), which make up half of the remaining south-eastern littoral forest. Some 700 villagers depend on the forest for crop growing, timber and nontimber forest products for subsistence and commercial activities. The main causes responsible for degradation and fragmentation in Sainte Luce are clearance by slash and burn, useless bushfires and unsustainable harvesting of logs. Threats in the near future further include charcoal production by the Antandroy people, a southern tribe, and 134
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 and 34:
Chapter 1 Relation with abiotic fac
Page 35 and 36:
Chapter 1 Malagasy rainforests disp
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
Page 85 and 86:
Chapter 3 Appendix I. All plant spe
Page 87 and 88: Chapter 3 Other SD Hss Rats Rr Ew 8
Page 90 and 91: Pteropus rufus Feeding ecology of P
Page 92 and 93: Pteropus rufus number per species a
Page 94 and 95: Pteropus rufus Table 1 Continued Fr
Page 96 and 97: Pteropus rufus larger number of spe
Page 98 and 99: Table 2 Continued Number of seeds/d
Page 100 and 101: Pteropus rufus Food selection: expl
Page 102 and 103: Pteropus rufus presence. On the oth
Page 104 and 105: Pteropus rufus Marshall (1983). Occ
Page 106 and 107: Coracopsis nigra The feeding ecolog
Page 108 and 109: Coracopsis nigra fruit pulp (70%) b
Page 110 and 111: Coracopsis nigra Table 1 Continued
Page 112 and 113: Coracopsis nigra Table 2. Morpholog
Page 115 and 116: Malagasy proverb Drawing of fruits
Page 117 and 118: Chapter 4 Most seed dispersal studi
Page 119 and 120: Chapter 4 Mean temperature is aroun
Page 121 and 122: Chapter 4 Number of seeds: 1-2, 3-1
Page 123 and 124: Chapter 4 Fig. 2. Monthly fruit ava
Page 125 and 126: Chapter 4 120 Table 3. Soil charact
Page 127 and 128: Chapter 4 Table 4. Morphological ch
Page 129 and 130: Chapter 4 Table 5. Biochemical char
Page 131 and 132: Chapter 4 Chemistry At both sites,
Page 133 and 134: Chapter 4 considering species numbe
Page 137: ’Ny valala tsy indroa mandry eo a
Page 141 and 142: Chapter 5 at a very low density in
Page 143 and 144: Chapter 5 Table 1. A list of plant
Page 145 and 146: Chapter 5 (Ganzhorn et al. 1999a).
Page 147 and 148: Chapter 5 Animals The degree of vul
Page 149 and 150: Chapter 5 comm.). Mixed species pla
Page 151 and 152: Chapter 5 data are needed we believ
Page 153 and 154: General conclusion as in other site
Page 155 and 156: General conclusion selection pressu
Page 157 and 158: General conclusion are consumed by
Page 159 and 160: Samenvatting omstandigheden zijn bo
Page 161 and 162: Samenvatting vruchtkenmerken. Beide
Page 163 and 164: Samenvatting zaadverspreiding moete
Page 165 and 166: Résumé température et précipita
Page 167 and 168: Résumé (Sud-est de Madagascar) et
Page 169 and 170: Résumé des frugivores sur l’év
Page 171 and 172: References Bollen A, Van Elsacker L
Page 173 and 174: References Dowsett JR (2000) Le sta
Page 175 and 176: References Godfrey LR, Junger WL, R
Page 177 and 178: References Janson CH, Chapman CA (1
Page 179 and 180: References Marshall AG (1983) Bats,
Page 181 and 182: References Rabevohitra R, Lowry PP,
Page 183 and 184: References Tattersall I (1982) The
Page 186: family Loganiaceae scientific name
show all

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

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?