The majority of tree species in tropical rain forests are rare on a local scale. A major problemin ecology is to investigate how these species can persist at such low local density. A related probleminvolves the demographic factors preventing any of the more common species from achieving dominancein the forest such as happens in the temperate zone. To investigate this topic tree populations in threecontrasting mixed dipterocarp forests in Sarawak have been measured at five-year intervals to gain information on rates of tree growth, recruitment and survival. The strengths and weaknesses of our methodology are contrasted with alternative experimental designs to highlight the best approaches for investigations of biodiversity. We have compared the demographic patterns of rare, occasional and commonspecies by combining species into abundance classes. For locally common species we have been able toevaluate population stability using regression analysis of changes in population size over four successiveintervals of five years. Using such approaches, long-term demographic studies can suggest the degree oftemporal stability of rainforest communities and give practical suggestions for preserving tree species innature reserves. These studies are also being used to provide baseline data for comparison with selec-tively logged forests and to assist in effective forest management planning. Such efforts are importantbecause logging and agricultural activities are currently having a major impact on Sarawak’s forests.

View full abstract

On the sand and gravel tailings after tin mining in Takuapa, Phang-nga province, Thailand, Eucalyptus camaldulensis was planted mainly for rehabilitation of the degraded land, and cassava and pineapple were cultivated for demonstrating the possible way of agriculture. This work is a part of "WasteLand Project" (WLP), having been conducted in Thailand for six years. Mulching among others was considered to be the best treatment for both trees and crops based on the following reasons, i) mulching lowered the maximum soil temperature in the hottest period, ii) it kept a good moisture condition throughout the year, iii) mulching materials could be utilized by plants as a source of nutrients as well as enhanced biological activity, and iv) they could be practiced easily, using weeds collectible in situ. As far as rehabilitation of a barren land is mainly concerned, Eucalyptus camaldulensis combined with Imperata mulching proved to be most promising. On the other hand, in order to establish a practical approach to agriculture under the severely poor soil conditions encountered, further exertion is indispensable for the goal, i.e., a reasonable, at least, sustainable yield of cassava and pineapple.

View full abstract

The spatial distributions of fallen fruits, seedlings, and trees of Swintonia schwenkii (T. & B.) T. & B. were studied in plots totaling 1.86 ha in a tropical foothill forest near Padang, West Sumatra.We recorded the positions of al1 fruits (2240 mature and 6715 immature), and 572 trees in the plots inSeptember and October 1989. Swintonia schwenkii was the dominant emergent in the plots, and had eightcanopy-to-emergent trees from 36 to 62 m in height. Seven of them produced fruits. There were no S.schwenkii of 20 < H ≤ 36 m in height. An index of spatial association showed that S. schwenkii in these edling-to-pole layer (0 < H ≤ 20 m) tended to be distributed away from those of conspecific emergent trees.
The mature fruits are 2 g in fresh weight, having five wings 6 × 1 cm in size and one seed inside. In contrast with the distribution of seedlings and small trees, many fruits dropped under the crowns of moth-er trees. The number of fruits decreased exponentially with distance from a mother tree, and fruits dispersed further than 50 m were rare.

View full abstract

The Punan people in Borneo island had traded forest products for the necessities of life withthe Dayak people, who traded them with the brokers. At present, the Kelay Punan people in East Kalimantan trade directly with the brokers and merchants, who control the trade of the forest productsfrom the region. They are degraded to debtors now and sti11 carrying out hunting and gathering to payback the debt. Besides, the introduction of swidden cultivation is one of the most important factors toaffect their life style. Their swidden system might not be so sustainable, since they were not traditionalswidden cultivators 1ike the Kenyah Dayak people.

View full abstract

In 1990 a large eumenid wasp was found on Chichi-jima, Bonin (Ogasawara) Islands. In structure, the wasp well agrees with Bequaert's (1928) concept of the wide-ranging "Eumenes pyriformis" (nowa species of Delta) in both the male and female. However, its color pattern is quite distinctive, easilydistinguished from those of al1 the geographical races of D. pyriforme so far known. Nevertheless, this wasp is considered to have been introduced from somewhere in the South Pacific or Southeast Asia, since no one had seen or collected it unti1 1990. It has now established itself on Chichi-jima and perhaps also on Ani-jima, though not seen on any other island of the Bonin group. Descriptions of the both sexes of this wasp are given together with notes on taxonomy and nesting biology.

View full abstract