Papers by Takakazu Yumoto
We propose page set ranking, whose ranking target is a page set. However, the discussion is not e... more We propose page set ranking, whose ranking target is a page set. However, the discussion is not enough about how to present the search results for users. In this paper, we propose a new method to present search results of page set ranking. This method considers the relationships between Web pages that compose a page set. We discuss about the model to express these relationships and how to apply to presentation method of page set ranking. This presentation method enables the users to browse Web pages obtained by page set ranking efficiently and effectively.
Japanese Journal of Conservation Ecology, 2011
International Forestry Review, 2019
To reconstruct the history of forest loss in Cambodia, the literature and national/provincial sta... more To reconstruct the history of forest loss in Cambodia, the literature and national/provincial statistics of landuse patterns and the socio-economic situation were investigated. Forest cover in the 1960s was 73.3 % (13.3 Mha). However, this drastically decreased to 47.3% (8.6 Mha) in 2016. In the 1960s, the forest was less-disturbed. From 1970 to 1993, the forest was lost gradually owing to the political instability caused by the Cambodian Civil War. In the post-war reconstruction period from 1993 to around 2002, the need for reconstruction, international demand for timber, and forest logging concessions led to a significant increase in timber production. In the rapid economic growth period from 2002 until present, while several political actions were taken to combat rapid deforestation, economic land concessions, which promoted agroindustrial plantations, as well as small-scale agriculture has been leading to the rapid expansion of arable land and deforestation since 2009.
One of the goals for primate feeding ecology is to understand the factors that affect inter-and i... more One of the goals for primate feeding ecology is to understand the factors that affect inter-and intra-specific variations. Therefore, a detailed description of basic feeding ecology in as many populations and sites as possible is necessary and warrants further understanding. The black-and-white colobus (Colobus guereza) or guereza is widely distributed in Africa and is one of the well-studied colobines in terms of their feeding; they demonstrate considerable variation in their diets in response to local conditions. We studied the diet of a group of guerezas in the Kalinzu Forest, Uganda, for over 30 consecutive months using behavioural observation (4,308 h total), phenology, and vegetation surveys. A total of 31 plant species were consumed by the study group. This study group was predominantly folivorous; the majority of their feeding time was involved in feeding on young leaves (87%). However, during certain times of the year, fruits and seeds accounted for 45% of monthly feeding time. Young leaves of Celtis durandii were by far the most important food, which constituted 58% of the total feeding records. There was a significant increase in the consumption of fruits and flowers once young leaf availability was low, but their consumption of fruits did not significantly increase even when fruit availability was high. Their monthly dietary diversity increased as the number of available plants with young leaves declined, suggesting that much of the dietary diversity in the study group may be attributable to the young leaf portion of their diet. Our findings may help contribute to a better understanding of the dietary adaptations and feeding ecology of guerezas in response to local environmental conditions.
Satoyama-Satoumi Ecosystems and Human Well-Being, 2013
In Chapter 3, the direct and indirect drivers and current status of satoyama and satoumi were dis... more In Chapter 3, the direct and indirect drivers and current status of satoyama and satoumi were discussed. In this chapter, we will describe how the changes in satoyama and satoumi ecosystem services have affected biodiversity and human well-being. Based on these changes, we will review why change in satoyama and satoumi is a concern.
Journal of Tropical Ecology, 2007
... Table 1. Frequency and abundances of plant seed recorded in the dung of Asian elephants (Elep... more ... Table 1. Frequency and abundances of plant seed recorded in the dung of Asian elephants (Elephas maximus) in Khao Yai National Park ... Fallen fig consumption by elephants around large strangler figs has been recorded for at least two fig species (Ficus altissima and F. cf. ...
Tropics, 2005
Abstract;Seed dispersal by animals plays a crucial role in the tropics. Fruit-bearing plants serv... more Abstract;Seed dispersal by animals plays a crucial role in the tropics. Fruit-bearing plants serve not only as nutritional sources for frugivores, but also as seed sources for forest regeneration and as important foci for the re-establishment of other plant species by attracting seed-...
Bird Conservation International, 2004
Asian hornbills are primarily frugivorous. We studied the characteristics of fruits consumed by f... more Asian hornbills are primarily frugivorous. We studied the characteristics of fruits consumed by four sympatric hornbill species in Thailand: Great Hornbill (Buceros bicornis), Wreathed Hornbill (Aceros undulatus), Austin's Brown Hornbill (Anorrhinus austeni) and Oriental Pied Hornbill (Anthracoceros albirostris). We compared the frequency of distribution of 11 variables for all fruit species collected in the study area (n = 259) and fruit species consumed by hornbills (n = 73). Our analysis revealed that fruits consumed by hornbills are: (1) large, (2) easily accessible within the canopy, (3) red, purple or black and (4) dehiscent or indehiscent with a thin husk. The range of fruit sizes eaten by hornbills in our study is comparable to that reported from other sites in Southeast Asia and Africa. The large gape width of hornbills enables them to consume large fruits that small frugivores would find difficult to consume. SHUMPEI KITAMURA1,
International Journal of Primatology, 2005
We describe the diet of a semihabituated group of Grauer's gorillas (Gorilla beringei graueri) in... more We describe the diet of a semihabituated group of Grauer's gorillas (Gorilla beringei graueri) inhabiting the montane forest of Kahuzi-Biega National Park, Democratic Republic of Congo, based on direct observations, feeding remains in their fresh trails, and fecal samples collected over 9 yr. We examined fruit availability in their habitat; consumption of fruit, vegetative, and animal food; and daily intake of vegetative plant food using a transect, fruit monitoring trails, fecal analysis, and tracing of the animal's daily trails between consecutive nest sites. The fruit food repertoire of Kahuzi gorillas resembles that of western and eastern lowland gorillas inhabiting lowland tropical forests, while their vegetative food repertoire resembles that of mountain gorillas inhabiting montane forests. Among 236 plant foods (116 species), leaves, pith, and barks constitute the major parts (70.2%), with fruit making up the minor part (19.7%). About half (53.2%) of the total fecal samples included fruit remains. The gorillas used leaves, stems and other vegetative plant parts as staples. Their fruit intake was similar to that reported for mountain gorillas in Bwindi. They ate animal foods, including earthworms, on rare occasions. Variation in fruit consumption was positively associated with variation in fruit production. The gorillas ate fig fruits frequently; fig intake is positively correlated with that of other fruits, and figs were not fallback foods. They relied heavily on bamboo shoots on a seasonal basis; however, no bamboo shoots were available for several years after a major 1346 Yamagiwa, Basabose, Kaleme, and Yumoto flowering event. Our results support the argument that variation in gorilla diets mostly reflects variation in vegetational composition of their habitats.
Primates, 1998
Seed dispersal by Japanese monkeys (Macaca fuscata yakui) via cheek-pouch was studied in a warm t... more Seed dispersal by Japanese monkeys (Macaca fuscata yakui) via cheek-pouch was studied in a warm temperate evergreen forest on Yakushima Island. Plant list was compiled based on a study during 1986-1995, of which troops of monkeys have been habituated without artificial feeding. We followed the well-habituated monkeys in 1993 and 1994 to observe the feeding behavior and their treatments of fruits and seeds, and collected seeds dispersed by monkeys to record the distance carried from the mother trees. We checked the difference of germination ratio between seeds dispersed via cheek-pouch and seeds taken from mother trees by sowing experiments. Seeds and acorns of 22 species were observed to be dispersed via cheek-pouch of monkeys. Among them, three species with acorns were never dispersed via feces, and 15 species with drupes were seldom dispersed via feces. Plant species of which seeds are dispersed only via cheek-pouch had larger seeds than those of dispersed both via cheek-pouch and via feces, and typically had only one or two seeds in a fruit. As for one of cheek-pouch dispersal species, Persea thunbergii, the mean distance when seeds were carried from the mother trees via cheek-pouch was 19.7 m, and the maximum distance was as long as 105 m although more than 80% of seeds were dispersed within 30 m from mother trees. And 82% of seeds dispersed via cheek-pouch germinated. The easy separation of seeds from other parts of the fruit seems to facilitate cheek-pouch dispersal more than dispersal via feces. Cheek-pouch dispersal by monkeys has possibly enhanced the natural selection for larger seeds which bring forth larger seedlings with high shade-tolerance. In conclusion, cheek-pouch dispersal by monkeys is quite an important mode for trees in the mature stand in a warm temperate evergreen forest on Yakushima Island.
Ecological Research, 1997
Abstract The fruiting phenology of animal-dispersed plants was observed in a warm temperate, ever... more Abstract The fruiting phenology of animal-dispersed plants was observed in a warm temperate, evergreen forest on Yakushima Island. The number of ripe fruits was counted for 22 trees, four lianas and one parasitic epiphyte species with sapfruit. These fruits were ...
Primates, 1994
Details are presented of the composition of the diet of eastern lowland gorillas, derived mainly ... more Details are presented of the composition of the diet of eastern lowland gorillas, derived mainly from a study of their fresh trails and fecal analysis, during the course of an entire year in the tropical lowland forests of the Itebero region, Zaire. Gorillas ate 194 plant foods from 121 species and 45 families. They consumed 48 species of fruits; and 89~ of fecal samples contained fruit seeds, but fruits were a relatively small part (25070) of the total number of food items. The composition of their diet changed seasonally. When consumption of fruit decreased in the long rainy and the long dry seasons, the gorillas ate, in addition to Zingiberaceae and Marantaceae, many kinds of leaf and bark, which may be an important buffer against the shortage of fruits. Gorillas also fed regularly on ants (Ponerinae), and the frequency of consumption showed small seasonal variations. From a comparison of diet composition, eastern lowland gorillas appeared to be intermediate between the other two subspecies. The choice of food showed differences in preference of fruits and insects between subspecies and may reflect high similarities within subspecies in lowland and montane forests.
Primates, 1991
Evidence was obtained that Eastern lowland gorillas feed regularly on ants in the lowland forests... more Evidence was obtained that Eastern lowland gorillas feed regularly on ants in the lowland forests of eastern Zaire. The six species of ants that may have been consumed by the gorillas were identified as Ponerinae, which possess a painful sting. Gorillas consumed the ants in both rainy and dry seasons, and fragments of ants were found in fecal samples from gorillas of all age-sex classes. Field signs indicated that the gorillas search intensively ants in primary and ancient secondary forests. Such searching may stimulate the gorillas to range through various types of vegetation and, thus, it may contribute to elongation of the distances that they travel daily.
Journal of Tropical Ecology
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Papers by Takakazu Yumoto