We examined regeneration processes within a permanent 0.9 ha tropical rainforest plot located in the West Sumatran Ulu Gadut region at about 630 m altitude. Our study site, the Gajabuih plot (GJB), was heavily logged in 1997. This induced conspicuous decreases in species number and diversity. Logging affected major climax species, few of which survived as standing trees. Species ordination analysis revealed a shift from a mature forest similar to that of a little-disturbed plot in the same region (PIN) to a young regenerating stand dominated by vigorous pioneer secondary forest species, such as Villebrunea rubescens (shade tolerant, random habitat preferences) and Mallotus paniculatus (widely dispersing species). Sprouter species made up 79% of calculated importance values in the regenerating stand. Single-stemmed trees (77% of total basal area) dominated the stand irrespective of species groups (survived or newcomer). Single-stemmed and multi-stemmed trees tended to be located on low slopes and ridge sites, respectively. The life strategy spectrum of the trees suggests that increases in the incidence of sprouting were promoted by heavy disturbance and variation in topographical structure. Sprouting abilities were negatively correlated with potential growth rates, as were shoot mortalities after storm damage. However, sprouting ability was positively correlated with the mechanical strength of trees (stem hardness). Using this information, we explored regeneration capacity by sprouting of tropical forests across environmental gradients of resources and disturbance.

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Understanding the variations in the natural abundance of a nitrogen isotope ratio (δ¹⁵N) within a plant can help determine the reliability of using a plant parts’ δ¹⁵N as an indicator of δ ¹⁵N in the entire plant. However, little is known about patterns of δ ¹⁵N variation, even within major plant organs such as the leaves. The aim of the present study was to determine variations in δ ¹⁵N within the foliage, with emphasis on the positions and nitrogen concentration in the leaves. From two habitats (mud swamp and peat swamp), three leaves of the tropical evergreen tree Combretocarpus rotundatus were collected at each of nine positions (three leaf positions within a branch [apical to basal] three branch positions within a tree [high to low]), and the nitrogen concentration and δ ¹⁵N were examined. In the mud swamp site, leaf δ ¹⁵N varied according to the branch and leaf positions (the variation within the foliage reached 3‰) and higher δ¹⁵N values were obtained from apical leaves on higher branches. At both habitats, the δ¹⁵N variations positively correlated with the leaf nitrogen concentration. The present study indicated that the δ¹⁵N in foliage exhibited position-related large variations associated with the leaf nitrogen concentration. These findings suggested that when using leaf δ¹⁵N as a reliable indicator of the ecophysiological behaviour of plants, variations associated with leaf and branch positions must be taken into account, at least in the case of C. rotundatus growing in the tropics.

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The Sebangau River, which flows west of Palangka Raya City, is one of the main rivers in Central Kalimantan, Indonesia. This paper examines the species composition of the macrozoobenthos community as well as water chemistry in the Sebangau River Basin during September 2004 and March 2006. The sampling on the macrozoobenthos as well as water of the Sebangau River was carried out 4 times from September 2004 to March 2006. The list of macrozoobenthos specimens comprised at least 42 genera belonging to 9 families. In the Sebangau River, insects were abundant and dominated by Diptera. The macrozoobenthos community of the Sebangau River Basin was more abundant and diverse in the upstream area. However, the community in the downstream area, especially in canals, was dominated by Chironomidae. Chironomidae was dominant in the Sebangau River system of which the water showed low pH. Lower diversity of the macrozoobenthos in the lower basin of the Sebangau River could be due to the lower amount of organic material contained in the sediment together with the high contamination of sulfuric acid in the lower basin of the river.

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Since production of non-timber forest products (NTFP) does not involve logging in principle, and provides income, it is expected to contribute for forest conservation as well as local people,s well-being. Studies have been carried out to evolve the factors determining the sustainability of NTFP production. This paper aims to provide additional information on thitsi (Melanorrhoea usitata / Gluta usitata, lacquer resin) production system of Myanmar. Thitsi has been used for centuries, but the production system is not known well. Plot surveys and interviews at three villages in Sagaing Division were conducted to obtain information about the production system of thitsi. Questions were mainly about (1) the method of resin collection, (2) situation of land and forest regulations, property rights and organizations, (3) economic conditions of producers and non-producers. The results showed that the tapping method seemed to have low impact on the thitsi trees at present, but there was no regeneration activity, the legal property rights were not clear, and there was no institution to control the use by people of other villages. The present situation seemed to be retained by the self-sufficient way of the livings of the local people, and the nature of the resin market that was mainly for domestic purposes with a relatively stable demand. However, competition for thitsi trees was observed, so if the people need more cash and the markets drastically expand in the future, it might be difficult to keep control of the use of this forest resource.

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