Adult trees of a given species distribute sparsely in tropical rain forests due to high tree species diversity, and dispersal and survival of juveniles are important processes to form such a pattern. Dispersal and juvenile survival of seven tree species were studied over 13 years in a 1-ha plot of tropical rain forest in Ulu Gadut, West Sumatra, Indonesia. All individuals of juveniles were marked and examined in 1989, 1998 and 2002. Estimation of dispersal kernel was successful for Calophyllum soulattri having the highest juvenile density among 7 species. Although dispersal kernel was significant in Gonystylus forbesii and Mastixia trichotoma, actual juvenile density was lower than expected in some subplots having high expected sapling density. Significant reduction of the sapling survival rate by neighboring conspecific saplings was detected in Calophyllum soulattri and Hopea dryobalonoides, and that by conspecific trees was detected in Swintonia schwenkii and Cleistanthus glandulosus. The negative effect of conspecific plants on juvenile survival was a more important factor than topography, and may be common in tropical rain forest trees. Aggregated distribution of saplings around mother trees might be formed just after seed dispersal; however, such patterns might be obscured by high mortality around mother trees, and relatively uniform tree distribution may be formed. Since regeneration is a rare phenomenon due to gregarious reproduction, we might be able to observe only limited stages of these processes simultaneously.

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In a region of Lower Northern Thailand, the traditional agricultural system has recently been changing toward a more intensive farming system by shortening the fallow cycle and several years of continuous cropping with significant fertilizer application. This study characterized soil fertility levels under the current intensified shifting cultivation systems, by comparison with the fruit tree plantations in the same area and the traditional shifting cultivation systems reported in the previous studies. Soil samples at surface and subsurface layers were collected from thirty study sites. Those study sites were grouped into 4 locations based on topography and parent material. Based on the PCA analysis of soil properties, soil fertility levels were mainly dependent on locations rather than the differences in land use types. However, some of the soils under maize field and fruit tree plantation showed a very low content of organic matter, suggesting occurrence of soil degradation in terms of organic matter. Burning of biomass still played an important role under the current intensified shifting cultivation systems, which brought positive effects to the soil fertility to alleviate soil acidity and supply exchangeable basis and available phosphorus. In contrast, because appreciable amounts of nitrogen seemed to be lost from soil ecosystems during cropping period, appropriate fertilizing methods should be developed to maintain the level of available nitrogen and to prevent environmental pollution.

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In order to assess the potential of nursery grown tropical tree seedlings for reforestation success in Ghana, we compared growth characteristics and foliar physiological traits of Cedrela odorata L. and Terminalia superba Engl. and Diels in a 2 nutrient × 2 sunlight factorial experiment. After approximately 16 weeks of a pot trial study, we found variations in the effect of light and/or nutrient addition on the parameters examined for C. odorata and T. superba. Both species attained greatest relative height growth rate (RHGR) at 33% sunlight with fertilization. However, the pioneer species, T. superba showed superior RHGR at both light treatments, especially in the fertilized pots. Allocation to leaf and root followed patterns typical of plants growing in sun or shade conditions. Greater root mass ratio was found in fertilized plants of T. superba than in fertilized plants of C. odorata at 100% sunlight. N fertilization enhanced relative Chl content of both species and without fertilization, 100% sunlight-grown foliage of C. odorata showed reduced Chl content. At 100% sunlight, fertilization enhanced F_v/F_m of C. odorata and thus, reduced the specie's susceptibility to photoinhibition. Foliar N concentration of both species was higher in the fertilized than control pots, whereas P concentration response to the light-nutrient treatments was species-specific. Superior biomass production in fertilized plants grown at 100% sunlight suggests that C. odorata and T. superba may be suitable for planting in large gaps and/or exposed sites. Based on our results, we recommend longer hardening periods plus fertilization of the seedlings in an exposed nursery, which may enhance their acclimation and thus, stimulate their growth when planted in the field.

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Low-cost forest management using highly effective microorganisms to promote seedling and tree growth is an important issue in reforestation in Indonesia and other tropical rain forest zones. To survey effective plant growth-promoting rhizobacteria (PGPR) for dipterocarp seedlings and/or saplings, forty-four bacterial strains were isolated from rhizoplane of several Dipterocarpaceae seedlings and saplings in Carita plantation forest located in the western part of Java Island followed by test for their effectiveness on the growth of Shorea selanica. Some isolated rhizobacteria demonstrated growth-promoting activity on dipterocarp seedlings. In the primary bioassay, these rhizobacteria indicated positive, negative or no effect on the plant growth, and 16S rRNA gene sequences of some important isolates were determined for their tentative identification. The most prominent strain isolated from Shorea leprosula was Erwinia. Other effective isolates were tentatively identified as, Rhizobium, Enterobacter, Duganella, an Alcaligeneceae bacterium, an Oxalobacteraceae bacterium, and some yeasts.

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We examined the early successional process in a fallow forest following slash-and-burn agriculture in East Kalimantan, Indonesia, to determine the ecological response of tropical secondary forest to human disturbance. Community dynamics and growth of the vegetation were studied during the initial 20 months of succession following the abandonment of slash-and-burn agriculture. The vegetation grew rapidly, and 20 months after the abandonment, plants with diameters ≥ 1 cm at breast height had a community density (number of stems) of 4.1 m^-2 and a basal area of 10.2 cm² m^-2. Populations of some dominant species began to decrease, and replacement of dominant species occurred within 20 months after the abandonment. Weeding of seedlings and sprouts during cultivation affected the composition and growth of the fallow vegetation. The results showed that fallow forests in the tropics have high recuperative potential.

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In South Kalimantan, Indonesia, a large area of rice paddy field is suffered with acid sulfate soil and the productivity of rice is supposed to be low. While in some paddy fields we have found that the yield of rice is larger than 5 ton ha^-1 without any fertilizer. There assumed to be the contribution of nitrogen fixing bacteria for rice production by biological nitrogen fixation (BNF) under those low pH condition. We have screened bacteria from the rhizosphere and rhizoplane of local rice plant growing in natural field based on their growth on nitrogen free medium. We have obtained 26 isolates, and the majority of isolated bacteria belonged to the β-proteobacteria (34.6 %) and others are α-proteobacteria (19.2 %), γ-proteobacteria (0.38 %), Bacilli (19.2 %), and Actinobacteria (23.1 %) based on their 16S rDNA sequence. We have determined their nitrogenase activity and the existence of nifH gene by using PCR technique. Though all of the isolates can grow on nitrogen free medium, only five isolates belong to β-proteobacteria have high nitrogenase activity. The existence of nifH gene was also confirmed in theses five isolates by using PCR technique. We presume that one of the mechanisms of the adaptation of these bacteria under acid sulfate soil is changing the surrounding pH. In bacterial culture medium, the change of pH during the incubation of these isolates was deeply regulated by the existence of several organic acid anions. In rice culture with soil experiments, under initial soil pH 3.5 condition, though rice growth was inhibited with the addition of 500 μM Al, inoculation with obtained isolate significantly alleviated Al stress. It is suggested that beneficial interactions of rice and free living nitrogen fixing bacteria might be operating to reducing root Al stress in acid sulfate soil.

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Dense haze emitted from peatland and forest fires in 1997/98 and 2002 damaged not only the peatland and forests themselves, but also the social activity and human health in many South East Asian countries. Several components of air quality, namely carbon monoxide, sulfur dioxide, nitrogen oxide, nitrogen dioxide, ozone and particulate matter less than 10 μm in diameter, were monitored since 2001 by the Environmental Impact Agency of Palangka Raya at three sites in Palangka Raya, Central Kalimantan. This study focused on daily concentrations of carbon monoxide (CO) and particulate matter less than 10 μm in diameter (PM₁₀) from 2001 to 2004. Clearly, concentrations of CO and PM₁₀ increased during the dry season of every year. The 8 hour average levels of CO concentration were higher than 15 ppm for 42 days during the dry season of 2002, an El Nino year. The MP₁₀ values were also very high during the 2002 dry season. The PM₁₀ values were higher than 250 μg m^-3 for 84 days in 2002. The high levels in air pollutant materials suggest that people living in Palangka Raya were subject to unhealthy conditions for a long time during the dry season in 2002. The rates of solar radiation on the ground (S_r) against extra-terrestrial solar radiation (S₀) showed a good correlation to the PM₁₀ values with a high coefficient of determination (0.92) during the dry season in 2002. The regression curve was applied to solar radiation on the ground in 1997. The result shows that the level of PM₁₀ in Palangka Raya was the same in September and October in both years, but high levels of PM₁₀ continued until November of 1997. The 2002 forest fires were responsible for financial losses at the national level. Merpati Nusantara Airline, Mandala Airline and Dirgantara Air Service lost 10.6 billion Rupiah, 2.8 billion Rupiah and 235 million Rupiah, respectively, while Garuda Indonesia Airline and Bouraq Airline lost 76.8 billion and 954 million Rupiah, respectively. Many schools (kindergartens, basic schools and elementary schools) were closed for one to four weeks. Many very old and very young people became ill and died. The estimated numbers of health cases in Central Kalimantan caused by forest fire are as follows: Death, 29 people; Asthma, 17,270 people; Bronchitis, 3,366 people; and ISPA, 83,772 people. The fires and haze restricted the ability of people to work and 275,660 people were forced to work only occasionally, while 141,714 people stopped working completely for the duration of the forest fires and produce thick smoke.

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Effects of an invasion of an alien shrub species, Leucaena leucocephala, were investigated on subsequent establishment of a native mid-successional wooden species, Schima mertensiana at early-successional stages after disturbance in a subtropical oceanic island, Chichijima in Japan. Changes in basal areas, densities and size distribution of forests at a site dominated by L. leucocephala were compared with those at a site dominated by native shrub species, Trema orientalis at early-successional stages. Effects of L. leucocephala on germination of seeds and growth of seedlings of S. mertensiana were quantified at the sites. There were few recruited seedlings of S. mertensiana and they did not grow at the site dominated by L. leucocephala. On the other hand, there were a few recruited seedlings within a 1 m x 1 m area and they positively grew at the site dominated by T. orientalis. Germination rates of seeds and growth rates of seedlings of S. mertensiana at the site dominated by L. leucocephala were lower than those at the site dominated by T. orientalis. Germination of seeds and growth of seedlings of S. mertensiana were inhibited by L. leucocephala at the disturbed site, which potentially changed an early successional pathway of the plant community.

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Dayak people have always taken the carrying capacity of the land into full consideration when opening the forest for growing rice (“ladang”). The Dayak use natural signs to decide the location of rice fields and they manage them with local knowledge. Upstream, the Dayak people use only shallow peat (“petak luwau”) near the riverbanks. In coastal areas, they use the “handel” system, which depends upon the hydrological behavior of twice daily tidal movement. The recent decrease in rice production by the over intensive canalization system resulted from the government's ignorance of the success of local people in implementing their local knowledge. The giant canals constructed as part of the Indonesian Central Government's Mega Rice Project to utilize peatland for agriculture were failures when compared with traditional canals in Central Kalimantan, namely, the “handel” and “anjir”. Presidential Decree 32/1990 declared that peatland with peat thickness less than 3 meters could be used for agriculture, while that with more than 3 meters should be conserved. Then, in 1996, the Mega Rice Project (MRP) in Central Kalimantan was established. However, rather than only considering the thickness of the peat layer to determine peatland utilization, land users should also consider information on the chemical properties of the bottom peat layer, hydrological status, local knowledge, culture of communities and marketability of proposed crops. Unfortunately, neglecting these factors when cultivating tropical peatland, especially deep peat in inland areas and also coastal peat, gives rise to unproductive land (“lahan tidur”). Peatland degraded by unsuitable agriculture must be restored using native tree species to achieve ecosystem stabilization. Thus, Presidential Decree 32/1990, which was formulated without first carrying out research, was a major factor leading to the failure of peatland utilization in Indonesia; it must be reformulated using knowledge of peatland's carrying capacity.

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Forest fires in Central Kalimantan are becoming a bigger disaster year after year. Based on experiences suppressing fires in 1997 and 2002, local organizations formulated a concept called the Concept of Fire Fighting Team or the Tim Serbu Api (TSA) Concept. TSA explains how to bring local people together to develop greater awareness and responsibility for the prevention of forest and peat fires and how to develop community environmental education. In 2002, besides totally suppressing fire for an approximately 50-60 ha along the transect, the team also saved. The TSA also made 9 transects (8.75 km long), drilled 21 deep well units, and cut 394 dead trees (“punggu”). Measurements and observations of fire behavior in the field included: (a) vegetation burning followed by peat layer burning, (b) fire depth 0-42.3 cm, (c) fire speed 1.2 m/hour on average, (d) difficulties with fire suppression because need much water, (e) peat fire producing thick smoke, (f) fire spreading through the bottom layer, (g) dead trees (“punggu”) spreading the fire, (h) easy burning vegetation is hampaning (Lithocarpus dasystachyus), (i) burn scarring of peat fire covered by charcoal and ash, and (j) lake-like burn scarring. Without involving local communities and transferring responsibility to them, it is impossible to suppress wild peat fires.

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