山根 正気

市岡 孝朗

松本 崇

松本, 崇

1842

マツモト, タカシ

市岡, 孝朗

1841

イチオカ, タカオ

山根, 正気

1869

ヤマネ, セイキ

MATSUMOTO, Takashi

2065

ITIOKA, Takao

2056

YAMANE, Seiki

2169

Research Institute for Humanity and Nature Repository

3.1. Effects of Forest Use on Biological Community Chapter 3  Effects of Traditional Forest Uses on the Number of Colonies of Army Ants  Takashi Matsumoto1, Takao Itioka1, Seiki Yamane2 1Graduate School of Human and Environmental studies, Kyoto University 2Earth and Environmental Sciences, Faculty of Science, Kagoshima University  Introduction The rapid and widespread loss of biological diversity is a matter of considerable concern. Destruction of tropical rain forests, one of the most diverse terrestrial ecosystems, is one of the major factors responsible for the high rates of species extinction in recent years (Myers 1988). Globally, tropical rain forests are disappearing at a rate of 12 million ha per year (Cyranoski 2007). Furthermore, less than 5% of the total land area of tropical rainforests is protected as reserves or national parks (Western 1989). Thus, the development of methods of using tropical rain forests that can prevent biodiversity loss is urgently needed.  In Southeast Asia, swidden (slash-and-burn) agriculture has been widely used by local residents and is frequently regarded as one of the primary causes of forest degradation and loss (Freeman 1955; Lanly 1982). Others, however, have stated that traditional methods of swidden agriculture are sustainable and maintain the ecosystem because of long fallow periods as well as the complex mosaic pattern of agricultural fields, abandoned fields in various stages of forest regrowth, and primary forest (Salafsky 1993; Aumeerudy and Sanonnens 1994; Coomes et al. 2000). To better understand whether traditional swidden agriculture is sustainable in terms of conservation of biodiversity, we need to examine whether biodiversity in secondary forests recovers to initial levels following cultivation and, if so, how long it takes. In the present study, we compared encounter rates between primary forests and secondary forests with various fallow periods for the top predator found among litter arthropods, the army ant (Aenictus and Leptogenys species). The top predator was chosen as an indicator for biodiversity loss caused by disturbance because it is vulnerable to disturbance and degradation (Noss et al. 1996) and also because it frequently plays an important role in structuring communities (Polis et al. 2000; Schmitz et al. 2000; Schmitz and Suttle 2001).  Material and Methods Study site The study was conducted in and around Lambir Hills National Park, Sarawak, Malaysia (4°20'N, 113°50'E; 150 to 200 m a.s.l.). Details of the park were described in Inoue et al. (1995). Local residents near the park have practiced swidden agriculture to cultivate rice and vegetables for about 100 years (Ichikawa 2002). To examine the effect of traditional swidden agriculture on biodiversity, we established two plots within the park, 11 plots in secondary forests at various developmental stages, and six plots in isolated primary forests near the park. Secondary forests were categorized into three groups depending on time since the abandonment of cultivation: new fallow (NF), <2 years after abandonment (N=3); young secondary forest (NSF), 5 years after abandonment (N=3); and old secondary forest (OSF), >20 years after abandonment 823.1. Effects of Forest Use on Biological Community Chapter 3  (N=5).   Field census We visually located army ant colonies from August to September 2003 and from January to February in 2005. Above-ground ant foraging activity is readily detected by observers because the ants move in coordinated columns on the forest floor, tree trunks, or vines. Three 1-h searches were conducted at each plot during each census period. Censuses were performed between 0800 and 1700 hours on days with good weather. Results from the three 1-h searches were combined for analysis for each census period. Prior to analysis, the numbers of ant colonies were log-transformed (y = log [x + 0.5]) to stabilize the variances (Yamamura 1999).  Results A total of nine Aenictus species was observed in 26 colonies. Aenictus laeviceps morphotypes L1 and L2 were the dominant species (53% of the total colonies in 2003 and 55% in 2005). Aenictus inflatus, A. camposi, A. hottai, and A. cornutus were not detected in the primary forests, and A. gracilis was observed only in the isolated primary forest (Table 1a).  All of the Aenictus colonies detected in this study were on raid and no emigrating colony was observed. The number of Aenictus colonies differed significantly among forest types (repeated ANOVA: F = 6.42, df = 4, P = 0.004; Fig. 1a), with the highest number of colonies found in the primary forest, an intermediate number found in young and old secondary forests, and the lowest number in new fallow (Tukey-Kramer HSD: P < 0.05; Fig 1a). No significant differences were found between years (repeated ANOVA: F = 0.006, df = 1, P = 0.93) or for the interaction between year and forest type (repeated ANOVA: F = 2.08, df = 4, P = 0.13; Fig 1a). For Leptogenys, we detected six species (36 colonies) in 2003 and four species (22 colonies) in 2005 (Table 1b). In contrast with Aenictus, differences in encounter rates with Leptogenys were not significant among forest types, although there was a weak tendency for more Leptogenys to be encountered in primary forests (repeated ANOVA: F = 2.43, df = 4, 14, P = 0.10; Fig 1b). No significant differences were found between years or for the interaction between year and forest type (F = 2.82, df = 1, 1, P = 0.12 for year; F = 0.25, df = 4, 14, P = 0.90 for interaction; Fig 1b).   Discussion When Aenictus was used as a bioindicator, traditional swidden agriculture was shown to have a serious impact on biodiversity in the tropical rain forest of Sarawak. Once an area was farmed using swidden agriculture, the effect of the disturbance lasted more than 20 years, although some Dipterocarp trees recovered at old secondary forests (Momose et al., unpublished data). Vasconcelos (1999) suggested that ground-dwelling ant fauna recovered in as few as 25 years when the intensity of the disturbance was low, so it seems that the impact of traditional swidden agriculture on biodiversity is more severe than was previously expected. It is possible that a longer fallow period would increase the abundance of Aenictus. However, no Aenictus was detected in old secondary forests (>100 years after abandonment). Thus, it seems to be unrealistic to expect that biodiversity will be maintained by extending the fallow period. 833.1. Effects of Forest Use on Biological Community Chapter 3  Some Aenictus colonies were observed in young and old secondary forests, although in smaller numbers than in the primary forest. All of the secondary forests in which army ants were observed, except one, were located proximate to continuous primary forest. This means that remnant primary forest may have contributed to the maintenance of biodiversity in the surrounding area. In terms of managing forest usage to sustain biological diversity, our study suggested that preserving enough primary forest would be more effective than extending the fallow period after traditional swidden agriculture. Four Aenictus species (A. inflatus, A. camposi, A. hottai, and A. cornutus) were observed only in secondary forests. All four species have previously been detected in a continuous primary forest (Yamane and Hashimoto 1999; Yamane, unpublished data). Therefore, it is unlikely that segregation of the Aenictus group occurred between forest types. In contrast to Aenicitus, the number of colonies of Leptogenys did not differ among forest types. Aenictus preys exclusively on immature social insects (Gotward 1976), whereas the diet of Leptogenys is much broader (Maschwitz and Mühlenberg 1975; Suzzoni et al. 2000; but see Mashwitz and Schönegge 1983). Using Eciton burchelli and Labidus praedator, who prey on almost all kinds of arthropods (Rettenmeyer 1963a,b), Roberts et al. (2000) showed that the number of colonies of army ants did not differ significantly between a primary forest and a traditional shady coffee plantation. Future research is required about the relationship between the breadth of diet and the strength of tolerance to artificial disturbance among army ant groups.    Table 1a. List of Aenictus  species encountered during the census in each forest type in 2003 (upper) and 2005 (lower)2003 AenictusForest type total A. laeviceps morpthotype L1 A. laeviceps morpthotype L2 A. gracilis A. dentatus A. inflatus A. camposi A.  hottai A. sp5 of sky A. cornutusNF (n=3) 0 0 0 0 0 0 0 0 0 0YSF (n=3) 0 0 0 0 0 0 0 0 0 0OSF (n=5) 1 0 0 0 0 1 0 0 0 0IPF (n=6) 9 3 2 2 1 0 0 0 0 1CPF (n=2) 5 2 1 0 1 0 0 0 1 02005 AenictusForest type total A. laeviceps morpthotype L1 A. laeviceps morpthotype L2 A. gracilis A. dentatus A. inflatus A. camposi A.  hottai A. sp5 of sky A. cornutusNF (n=3) 0 0 0 0 0 0 0 0 0 0YSF (n=3) 2 0 0 0 0 1 1 0 0 0OSF (n=5) 2 1 0 0 1 0 0 0 0 0IPF (n=6) 4 1 1 0 0 1 0 1 0 0CPF (n=2) 3 2 1 0 0 0 0 0 0 0NF, YSF, OSF, IPF, CPF designated new fallow, young secondary forest, old secondary forest, isolated primary forest, and continuous primary forest, respectively. See M&M for the definition of each forest type.Table 1b. List of Leptogenys  species encountered during the census in each forest type in 2003 (upper) and 2005 (lower)2003 LeptogenysForest type total L. processionalis L. diminuta L. sp39 of sky L. sp 6 of sky L. mutabilis L. chalybaeaNF (n=3) 5 4 1 0 0 0 0YSF (n=3) 1 0 0 1 0 0 0OSF (n=5) 10 5 1 4 0 0 0IPF (n=6) 11 2 5 3 1 0 0CPF (n=2) 9 3 3 1 0 1 12005 LeptogenysForest type total L. processionalis L. diminuta L. sp39 of sky L. sp 6 of sky L. mutabilis L. chalybaeaNF (n=3) 2 2 0 0 0 0 0YSF (n=3) 1 0 1 0 0 0 0OSF (n=5) 5 2 2 1 0 0 0IPF (n=6) 7 2 3 2 0 0 0CPF (n=2) 7 3 2 1 0 0 1NF, YSF, OSF, IPF, CPF designated new fallow, young secondary forest, old secondary forest, isolated primary forest, and continuous primary forest, respectively. See M&M for the definition of each forest type.843.1. Effects of Forest Use on Biological Community Chapter 3   Acknowledgments We thank L. Chong (Sarawak Forestry Corporation), Dr. J. Kendawang (Forest Department Sarawak), and the staff of Lambir Hills National Park for allowing us to perform our study. We also thank H. Kaliang (Sarawak Forestry Corporation) for helping us take specimens from Sarawak for identification and Deline for mounting the ant specimens. This study was financially supported by RIHN research project 2-2 and a JSPS Research Fellowship for Young Scientists to T. M.  References Aummeeruddy Y, Sansonnens B (1994) Shifting from simple to complex agroforestry systems: an example for buffer zone management from Kerinci. Agrofor Ayst 28:113–141 Coomes OT, Grimard F, Burt G (2000) Tropical forests and shifting cultivation: secondary forest fallow dynamics among traditional formers of the Peruvian Amazon. Ecol Econ 32:109–124 Cyranoski D (2007) Logging: the new conservation. Nature 446:608–610 Freeman JD (1955) Iban agriculture: a report on the shifting cultivation of hill rice by the Iban of Sarawak. HMSO, London Gotward WHJr (1976) Behavioral observations on African army ants of the genus Aenictus (Hymenoptera: Formicidae). Biotropica 8:59–65 Ichikawa M (2002) Studies on uses of ecological resources at an Iban village in Bakong river basin, Sarawak. Ph D Thesis Kyoto University (in Japanese) Inoue T, Yumoto T, Hamid AA, Seng LH, Ogino K (1995). Construction of a canopy observation system in a tropical rainforest of Sarawak. Selbyana 16:24–35. Lanly JP (1982) Tropical forest resources. FAO Forestry Paper 30, FAO, Rome Maschwitz U, Mühlenberg M (1975) Zur Jagdstrategie einiger orientalischer Leptogenys-Arten (Formicidae: Ponerinae). Oeocologia 20:65–83 (in German with an English summary) Maschwitz U, Schönegge P (1983) Forage communication, nest moving recruitment, and prey specialization in the oriental ponerine Leptogenys chinensis. Oecologia 57:175–182 Myers N (1988) Tropical deforestation and climatic-change. 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Am Nat 155:141–153 Schmitz OJ, Suttle KB (2001) Effects of top predator species on direct and indirect interactions in a food web. Ecology 82:2072–2081  Suzzoni JP, Schatz B, Dejean A (2000) Essential and alternative prey in a ponerine ant: variations according to the colony cycle. Life Sciences 32:1003–1008 Vasconcelos HL (1999) Effects of forest disturbance on the structure of ground-foraging ant communities in central Amazonia. Biodivers Conserv 8:407–418 Western D (1989) Conservation without parks: wildlife in a rural landscape. In: Western D, Pearl MC (eds) Conservation for the twenty-first century. Oxford University Press, New York, pp 158–165 Yamane S, Hashimoto Y (1999) A remarkable new species of the army ant genus Aenictus (Hymenoptera, Formicidae) with a polymorphic worker caste. Tropics 8:427–432    853.1. Effects of Forest Use on Biological Community Chapter 3  -0.4-0.200.20.40.6log(No. of Aenictus colonies)    a        ab       ab        bc        c Forest typesNF       YSF       OSF       IPF        CPF  Figure 1a. Mean (±S.E.) of log-transformed encounter rates  with Aenictus species within each forest type in 2003 (open circle)  and 2005 (solid circle). Different letters among circle designated  significant difference among forest types. NF, YSF, OSF, IPF, CPF  designated new fallow, young secondary forest, old secondary  forest, isolated primary forest, and continuous primary forest,  respectively. See M&M for the definition of each forest type.  Figure 1b. Mean (±S.E.) of log-transformed encounter  rates with Leptogenys species within each forest type in 2003  (open circle) and 2005 (solid circle). NF, YSF, OSF, IPF, CPF  designated new fallow, young secondary forest, old secondary  forest, isolated primary forest, and continuous primary forest,  respectively. See M&M for the definition of each forest type. 86

Effects of traditional forest uses on the number of colonies of army ants

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Effects of traditional forest uses on the number of colonies of army ants

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