著者

Bibian Diway Ling Chea Yiing Mohd Effendi Wasli Yayoi Takeuchi

出版者

JAPAN SOCIETY OF TROPICAL ECOLOGY

雑誌

Tropics (ISSN:0917415X)

巻号頁・発行日

vol.32, no.1, pp.1-14, 2023-06-01 (Released:2023-06-01)

参考文献数

54

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In Sarawak, Malaysia, logging is conducted with a 25-year harvesting cycle; however, it remains largely unclear if this cycle length is sufficient for forest recovery. This study aims to investigate how the structure of logged forests recovered along the periods after logging. We conducted this study in the Anap-Muput Forest Management Unit (AMFMU), Sarawak. We first established permanent sample plots with different logging history; that is, from 5 years to more than 37 years after the most recent logging. Using the various sample plots, we assessed the stem density, basal area (BA), proportion of dipterocarps, growth and mortality. To compare the forest structure of the logged over forests with that of primary forests, we used our previous data of a primary forest in Batang Ai National Park. We found significant differences in the stem density, total BA, and the proportion of dipterocarp among the plots. Generally, the stem density and total BA increased with the period after logging and decreased with diameter at breast height (DBH) size classes, except of tree of ≥60 cm DBH in several plots. The growth rates and mortalities were higher in more recent logged forests. These results indicated that logged forest was recovering with periods after logging partly because of higher growth rate; however, even in a forest of 37 years after logging, the forest structure was not fully recovered compared to the primary forest. Thus, we concluded that a 25-year harvesting cycle in the selective logging system would not be sufficient for the AMFMU forest to recover. We further need other effective strategies with systematic monitoring.

著者

Sunittra Aupanun Weeyawat Jaitrong Fuminori Ito

出版者

JAPAN SOCIETY OF TROPICAL ECOLOGY

雑誌

Tropics (ISSN:0917415X)

巻号頁・発行日

vol.30, no.4, pp.63-70, 2022-03-01 (Released:2022-03-01)

参考文献数

33

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Colony composition and behavioral characteristics of the myrmicine ant, Aphaenogaster rugulosa, a species endemic to Yonagunijima Island, were investigated. Colonies nested in rotten woods fallen on the forest floor. All queenright colonies (N=42) were monogynous with one dealate queen. The average colony size in worker number was 140.5±SD 94.9. Under laboratory conditions, workers and larvae fed on both fresh and dried insect preys. The workers used a kind of tool to transport diluted sugar water to the nest chamber. They dropped pine needles and trashes into the diluted sugar water and then transported the food-soaked materials back into the nest chamber, where nest members then sucked on the materials inside the nest chamber. Trophic eggs were laid by the workers, the majority of which were given to the larvae. The queens also fed on trophic eggs as well as insect preys. The workers under an orphan condition laid reproductive eggs that grew up to be males.

著者

Bibian Diway Yasuo Yasui Hideki Innan Yayoi Takeuchi

出版者

JAPAN SOCIETY OF TROPICAL ECOLOGY

雑誌

Tropics (ISSN:0917415X)

巻号頁・発行日

vol.30, no.4, pp.71-82, 2022-03-01 (Released:2022-03-01)

参考文献数

37

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A new Rafflesia population was found in Naha Jaley, Sarawak, in 2012. This study aimed to identify this Rafflesia species and investigate its bud growth. First, we described the flower characteristics and compared them with Rafflesia keithii and R. tuan-mudae, which are candidate species for the flower. Also, we investigated the phylogenetic position of this Rafflesia within Rafflesiaceae using DNA analysis. To estimate bud growth curve, we observed bud development from April 2013 to November 2013 in the field. Based on morphological comparisons and phylogenetic analysis, we confirmed the newly discovered population of the Rafflesia at Naha Jaley was R. tuan-mudae, which is the new locality of the species at the most Eastern side of the known distribution for this species. The results indicated that absolute growth rate was greater in larger buds. We also estimated that it took a year to bloom from the initial bud stage. The mortality in one of our sites was very high, with more than 80 % of buds dead prior to flower opening. This flower would be vulnerable to extinction due to their extraordinary characteristics and anthropogenetic effects. Finally, we discussed how Rafflesia populations in Naha Jaley can be conserved both in-situ and ex-situ.

著者

Yasuyuki Kosaka Bhaskar Saikia C. K. Rai Komo Hage Haruhisa Asada Tag Hui Tomo Riba Kazuo Ando

出版者

JAPAN SOCIETY OF TROPICAL ECOLOGY

雑誌

Tropics (ISSN:0917415X)

巻号頁・発行日

vol.24, no.2, pp.75-90, 2015 (Released:2015-09-01)

参考文献数

34

被引用文献数

1

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The transformation of land from swidden based to permanent agriculture is an important issue related to the sustainable livelihood and land use system of people in mountain environments. This paper reports the introduction of paddy rice cultivation and its consequences in four swiddener communities in Arunachal Pradesh, India, by focusing on cultivation techniques. The Indian government introduced paddy rice cultivation to Arunachal Pradesh in the 1950s by teaching the required techniques and supplying seed and agricultural tools. However, few swiddeners began rice cultivation because they disliked working in muddy paddies that could not produce non-rice crops. During the “green revolution” in the 1970s, many people decided to create paddy fields after observing the remarkably high yield of new rice varieties. Over 60 years of trial and error, many swiddener communities have developed a unique cultivation system suited to their local environment, while often learning from their neighboring communities of Ahom and Apatani that already practiced paddy rice cultivation. The paddy field has become a symbol of wealth and social status because of the high and stable yield of paddy rice and escalating land prices. However, the communities usually continue some aspects of swidden cultivation, because only a limited amount of land is suitable for paddy rice, people need non-rice crops, or because older people prefer swidden cultivation work and the taste of upland rice. This case study shows the importance of local needs and knowledge of skilled farmers in swidden transformation.

著者

Erianto Indra PUTRA Hiroshi

出版者

JAPAN SOCIETY OF TROPICAL ECOLOGY

雑誌

Tropics (ISSN:0917415X)

巻号頁・発行日

vol.19, no.4, pp.145-156, 2011 (Released:2012-02-01)

参考文献数

20

被引用文献数

9 37

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Indonesia has experienced severe tropical forest fires from a long time ago, mainly in El Niño years. However, previous studies showed that after 1997 forest and peat fires in Indonesia tend to occur every year in the dry season, even in non El Niño years. To clarify this recent pattern of incidence, we studied the fire situation in the Mega Rice Project (MRP) area, Central Kalimantan where large scale development of tropical swamp-forest has been carried out since 1996. To identify the causes of the recent severe peat fires, weather data for Palangkaraya from 1978 to 2007, hotspot data captured by the MODIS satellite, monthly Niño 3.4 sea surface temperature (SST) anomalies, and ground water level (GWL) data were analyzed. The results of the analysis clearly showed a relationship among the precipitation pattern of the dry season, GWL change, Niño 3.4 SST Anomalies, and fire occurrences. A pattern of low precipitation in the dry season decreased GWL and caused a peat fire peak in the middle of August when daily precipitation reached the minimum. These results suggest that large areas of bared peat in the MRP now has a high susceptibility to fire coupled with the precipitation pattern of the dry season.

著者

Yasuhiro Nakanishi Tatsuma Matsutani Ko Hinokidani Takashi Nagai Mami Irie

出版者

JAPAN SOCIETY OF TROPICAL ECOLOGY

雑誌

Tropics (ISSN:0917415X)

巻号頁・発行日

vol.28, no.4, pp.91-97, 2020-02-01 (Released:2020-02-01)

参考文献数

31

被引用文献数

2

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Iron solubilization in mangrove soils associated with polyphenols leached out from leaf-litter can improve iron bioavailability. In this context, the leaf-removing process by mangrove crabs would increase reacting frequency of the polyphenols in mangrove leaves with iron in the soils. In this study, we investigated ecological roles of a leaf-removing crab, Neosarmatium smithi, on the iron solubilization process. After the fallen leaves carried by the crabs to their burrows and eaten by them, polyphenols may be remained in their feces. If so, contact of polyphenols in the feces with mangrove soils could promote elution of dissolved iron from the soils. In order to demonstrate this hypothesis, we firstly surveyed the appearance ratio of the black part in crab burrows and measured total phenolic content in feces of N. smithi as well as in the black part soil. Then, we examined influences of the crab feces on dissolved iron elution from mangrove soils. As the results, the appearance ratio of the black part in the burrow was 67% and the phenolic content in the feces, the black part, and the yellow part in crab burrows were 9.93, 0.49, and 0.12mg g-1, respectively. Dissolved iron content in the solution (soil+water extract from feces) was 0.65μg g-1 and this content was 4.5 times higher than the control (soil+distilled water). We suggest that the polyphenols remained in the feces affect to solubilize insoluble forms of iron by iron reduction and chelating properties.

著者

Shumpei KITAMURA Takakazu YUMOTO Pilai POONSWAD Phitaya CHUAILUA Kamol PLONGMAI Naohiko NOMA Tamaki MARUHASHI Prawat WOHANDEE

出版者

JAPAN SOCIETY OF TROPICAL ECOLOGY

雑誌

Tropics (ISSN:0917415X)

巻号頁・発行日

vol.14, no.4, pp.345-355, 2005 (Released:2008-09-30)

参考文献数

65

被引用文献数

7 9

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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-dispersing frugivores to their vicinity. However, opportunities for investigating the interactions between a diverse fruit flora and disperser fauna are rapidly disappearing in Southeast Asia. We observed the behaviors of 28 species of frugivorous visitors to 15 fruit-bearing plant species in a moist evergreen forest in Khao Yai National Park, Thailand, to determine their potential quality as seed dispersers. Behavioral observations included the frequency and duration of visits by each forager and their fruit-handling techniques. The highest numbers of frugivores were recorded at strangler figs, confirming their role as an important resource for frugivores at Khao Yai. Mammals and non-passerine birds spent significantly more time at food plants than did passerine birds. Our study provides a preliminary inventory of plant-frugivore interactions that is comparable to other study sites in Southeast Asia. Since fruit-frugivore interactions may differ among the forests, these kinds of studies need to be replicated at faunally intact forests, as well as depleted forests, in Southeast Asia.

著者

Wataru Nakai Naoki Okada Masaki Sano Takeshi Nakatsuka

出版者

JAPAN SOCIETY OF TROPICAL ECOLOGY

雑誌

Tropics (ISSN:0917415X)

巻号頁・発行日

vol.27, no.2, pp.49-58, 2018 (Released:2018-09-01)

参考文献数

26

被引用文献数

9

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Radial variation of δ18O before and after cellulose extraction was assessed in Acacia auriculiformis, Eucalyptus camaldulensis, and Celtis timorensis growing in northeastern Thailand to examine the necessity of extracting α-cellulose to detect annual rings from trees without visible rings. Optimum sampling resolution to detect peaks in the radial variation of δ18O values was also examined. Cored samples were sectioned into 0.2mm thickness in the radial direction. Each circular section sliced from a wood core sample were divided along wood grain into two semicircular sections, both of which were located at the same radial and longitudinal positions, and were side-by-side tangentially. One half was used for bulk analysis and the other for extraction. Peak positions were assigned from the seasonal variation of δ18O. The δ18O values cyclically changed in both bulk wood and α-cellulose. The correlation coefficient between bulk wood and α-cellulose δ18O was high in every species, and the offset was almost constant across the radial position. The mean cycle length of one sample was longer than those of the other two samples, although annual increment based on dendrometer monitoring was smaller than those of the other two samples. That is, the seasonal variation in δ18O values recorded in the xylem was not completely detected because of low amplitude or insufficient radial resolution. Therefore, we concluded that α-cellulose extraction is unnecessary for annual ring detection. It is necessary to determine an appropriate sampling resolution based on growth rate for effective peak detection.

著者

WATANABE Natsuki M. SUZUKI Eizi SIMBOLON Herwint

出版者

JAPAN SOCIETY OF TROPICAL ECOLOGY

雑誌

Tropics (ISSN:0917415X)

巻号頁・発行日

vol.18, no.1, pp.13-21, 2009

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We quantified the reestablishment of rattans (climbing palms) after severe forest fires in 1997-1998 caused by the El Niño Southern Oscillation event in Bukit Bangkirai, East Kalimantan, Borneo. We established a 1-ha study plot in unburned forest (K1) and two 1-ha plots in burned forest (LD2 and HD2, 200 and 800 m away from unburned forest, respectively). In 2006 the number of species and stem density of rattans including seedlings were 16 and 8 species ha^-1 and 88 and 24 stems ha^-1 in LD2, and HD2, respectively. These values were lower than those in K1, where 23 species and 3321 stems were recorded. The dominant species in burned plots were Ceratolobus concolor, Korthalsia debilis, and Plectocomiopsis geminiflora, which were minor components in the unburned plot. Rattans likely recolonized burned forest sites by seeds transferred from neighboring unburned forest by birds and animals. The distance from unburned forest appeared to affect the speed of the recovery in the burned plots. Although recovery of the stem density of rattans was slower than that of trees in burned plots, it will likely increase gradually because the number of recruits consistently exceeded mortality during our study period (February 2006 to August 2007). However, it is not clear whether species composition and the density in burned forests recover to preburned levels.

著者

成田 憲二 Mertia R.S. Kumar Shuresh 市河 三英 古川 昭雄

出版者

JAPAN SOCIETY OF TROPICAL ECOLOGY

雑誌

Tropics (ISSN:0917415X)

巻号頁・発行日

vol.7, no.1, pp.105-114, 1997-10-30

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インドのタール膿内の轍地(年降水量150mm)および半乾燥地(同450mm)の草本植生において,ヒツジの被食が草本群集の構成と被度に与える影響を被食圧の勾配に沿って調査した。両調査地1ヘクタール当たり8,6,3頭とコントロールの4段階の被食圧のプロットを設定し,ヒツジの導入後の季節変化を種構成,被度について調査した。草本植生の被度,構成種数共に半乾燥地の方が高く,季節変化も少なかった。乾燥地の植生は被度の季節変動が大きく,ヒツジによる被食の影響は乾燥地でより強く現れた。乾燥地では,雨期中期に優占する一年生広葉草本Indigofera属の3種がヒツジの被食に応じて被度が減少し,この3種の変動だけで被食による群集全体の被度影響の92.5%が説明された。半乾燥地にもこれらの種が生育していたが被度も低く,また,被食圧に沿った被度の減少は見られなかった。