Showing papers in "Tropics in 2006"
TL;DR: Nutrient analysis revealed that red kalakai (wild fern) has the potential nutrient value, and other iron-rich vegetables were sulur keladi and bajey, while other vitamin C- rich vegetables were paria leaves and baja fern.
Abstract: The Dayak people in Central Kalimantan, traditionally consumed local vegetable, either collected from the wild or traditionally cultivated. Unfortunately, many of the traditional vegetables are approaching extinction, even in their local market. This research is intended to conserve the traditional vegetable by collecting nutritional data and cultural information about the vegetable. Nineteen traditional Dayak vegetables were observed in local markets and in wild areas. Taxonomic identification revealed that the vegetables were Passiflora foetida L. (kemot), Diplazium esculentum (Retz). SW. (bajey fern), Spondias pinnata (L.f.) Kurtz (kedondong leaves), Neptunia oleracea Lour (malu-malu leaves), Manihot esculenta Crantz (cassava leaves). Vigna unguiculata (L.) Walp. (talak leaves), Etlingera elatiar (Jack) R.M. Smith (potok shoots, red and green cultivar), Calamus sp. (rotan shoots), Nauclea sp. (Taya leaves), Momordica charantia L. (paria leaves), Gymnopetalum cochinense Kurz (kanjat), Solanum torvum Swartz. (segau fruit), Colocasia esculenta (L.) Schott (sulur keladi shoots), Stenochlaena palutris (Burm.)Bedd. (kalakai leaves; red and white cultivar), lotus shoots (pucuk teratai), and Cnesmone javanica Blume (lampinak leaves). Nutrient analysis revealed that red kalakai (wild fern) has the potential nutrient value. It has a high amount of Fe (41.53 ppm), Cu (4.52 ppm), vitamin C (15.41 mg/100g), protein (2.36%), β-carotene (66.99 ppm), and folic acid (11.30 ppm). Other iron-rich vegetables were sulur keladi (49.25 ppm) and bajey (44.6 ppm). While other vitamin C-rich vegetables were paria leaves (18.34 mg/100 g wb), and bajaj fern (22.05 mg/100g w.b). Sulur keladi and bajey were also rich in folic acid.
22 citations
TL;DR: In this paper, the fluctuation of fertility-related properties of soils throughout land-use stages was analyzed and the soil organic matter (SOM) budget was quantitatively evaluated, with special reference to soil microbial activities.
Abstract: To clarify the various functions of the fallow phase in the shifting cultivation system in northern Thailand, the fluctuation of fertility-related properties of soils throughout land-use stages was analyzed and the soil organic matter (SOM) budget was quantitatively evaluated, with special reference to soil microbial activities. The factors that have ensured the long-term sustainability of the shifting cultivation system can be summarized as follows: (1) Some soil properties relating to soil acidity improve when SOM increases in the late stages of fallow. The litter input may be supplying bases that are obtained via tree roots from further down the soil profile to the surface soil. This simultaneous increase in SOM and bases in the surface soil through forest-litter deposition in the late stages of fallow has an increasing effect on nutritional elements. (2) The decline in soil organic C during the cropping phase may be compensated by litter input during 6-7 years of fallow. With regards to overall budget, the organic matter input through incorporation of initial herbaceous biomass into the soil system after establishment of tree vegetation (approximately in the fourth year) was indispensable for maintaining the SOM level. (3) The succession of the soil microbial community from rapid consumers of resources to stable and slow utilizers, along with the establishment of secondary forest, retards further leaching loss of nitrogen (N) and enhances N accumulation in the forest-like ecosystems. It is noteworthy that during the fallow period, nitrifying activity of soil microbes, which was once activated in the cropping phase, is apparently suppressed. As a result, nitrate (NO3-) effluent from soil layers was remarkably decreased, even in the initial stages of fallow. The functions of the fallow phase listed above can be considered essential to the maintenance of this forest-fallow system. Agricultural production can therefore be maintained with a fallow period of around 10 years, which is somewhat shorter than widely believed. Traditional shifting cultivation in the study village is shown to be well adapted to its soil-ecological condition.
21 citations
TL;DR: The altitudinal distribution patterns of Fagaceae appeared to involve both species coexistence/concentration at particular altitudes and species replacement with changing altitudes, and Lithocarpus showed a remarkably high species richness at 400-700 m in both regions.
Abstract: The altitudinal distribution of Fagaceae in West Sumatra was studied on the basis of herbarium specimens and field tree censuses conducted at Gunung Gadut and Sipisang. Forty-two species were examined (Castanopsis: 8 spp., Quercus: 8 spp., Lithocarpus: 25 spp., and Trigonobalanus verticillata), and it was revealed that altitudinal distribution patterns vary among species and genera. The species richness of Fagaceae in West Sumatra was highest at 400-700 m, decreasing with increasing altitude above 700 m, while about half the total number of species occurred below 400 m. Though the altitudinal distribution patterns of some species were compressed toward a lower altitude in Gunung Gadut, species richness in Gunung Gadut and Sipisang regions were also highest at 400-700 m above sea level (76 % of 33 species were found growing in these regions), and more than half of the species were found at 150-400 m. Quercus showed gradual replacement/overlapping of higher/lower altitudinal species at a range of 700-1100 m, and Lithocarpus showed a remarkably high species richness at 400-700 m in both regions. The altitudinal diversity patterns of Fagaceae appeared to involve both species coexistence/concentration at particular altitudes and species replacement with changing altitudes. The high species richness of Fagaceae at 400-700 m was especially due to the coexistence and concentration of Lithocarpus species.
17 citations
TL;DR: This paper aims to demonstrate the efforts towards in-situ applicability of EMMARM, which aims to provide real-time information about the phytochemical properties of fruits and vegetables that can be processed for human consumption.
Abstract: 1 Department of Plant Breeding, CCS Haryana Agricultural University, Hisar-125004, India 2 Department of Microbiology, CCS Haryana Agricultural University, Hisar-125004, India 3 Department of Genetics, CCS Haryana Agricultural University, Hisar-125004, India 4 Department of Plant Nutrition, Hokkaido University, Sapporo, Japan 5 Creative Research Initiative “Sousei”, Hokkaido University, Sapporo, Japan
14 citations
TL;DR: In this paper, household level subsistence patterns and their variations within a rural society that was subjected to the logging operation in the recent past, in Roviana, Western Province were compared among households and adjusted for the consumer unit (CU) and producer unit (PU), respectively.
Abstract: Since several decades ago, rural societies in Solomon Islands have experienced rapid socioeconomic changes due to the direct and indirect influences of commercial logging operations by foreign companies on their customary lands. This study aims to explore household level subsistence patterns and their variations within a rural society that was subjected to the logging operation in the recent past, in Roviana, Western Province. Crop yield (MJ) and cash income (SBD: Solomon Islands Dollar) were compared among households and adjusted for the consumer unit (CU) and producer unit (PU), respectively. The results indicated large inter-household variations for both of these variables. Multiple regression analyses showed that the variation in crop yield was primarily explained by the available labor force (PU), while that in cash income was determined by the householders’ par ticipation in SDC, a local enterprise founded using a portion of royalty money, as well as the labor force. It is suggested that an individual’s experience in generating and increasing cash income in local environments increases his/her household’s economic level.
13 citations
TL;DR: Indonesia has a vast area of inland waters, consisting mainly of lakes, Reservoirs, rivers and swamps as discussed by the authors, and there are an estimated 14 million ha of inland water, consisting of 220 significant rivers, 50 big lakes and reservoirs.
Abstract: Indonesia has a vast area of inland waters, consisting mainly of lakes, Reservoirs, rivers and swamps. There are an estimated 14 million ha of inland waters, consisting of 220 significant rivers, 50 big lakes and reservoirs, all over the country. The high population density and rapid development in all sectors has raised a lot of environmental issues, including those inland waters. The increasing demand for space, food, water and industrial products, forces Indonesia to its utilization of inland waters. The utilization of inland water resources creates some problems, such as water pollution, siltation, eutrophication and the spreading of aquatic weeds and decreasing of indigenous species. Limnological on Indonesia is still limited. Due to the large extent of inland waters in Indonesia, the have not been studied entirely. Many inland waters have been researched, however data has not been compiled to allow to the construction of an environmental information system, which is crucial to balance development and conservation of inland water resources.
11 citations
TL;DR: Based on correlation analysis, changes in selected hydro–physical properties of peat soils were significantly related to changes in bulk density and fiber contents, and so related to the progress ofpeat decay.
Abstract: The restorat ion and proper agricultural use of tropical peatlands require knowledge of the physical properties of peat soils. Several physical properties related to changes in the hydrological potential of peat soils as affected by agricultural development were investigated. Selected parameters obtained in selectively logged peat swamp forest were compared with those obtained in clear–cut and maize–cultivated peatlands. In all cases, changes in selected hydro– physical properties were evidently in the top 0–15 cm layer of peat soils, and as in developed sites the top layer of peat soils was subjected to more decomposition as shown by an increase in bulk density and a decrease in fiber content. Bulk density of the top 0–15 cm layer was on average 0.14, 0.29, and 0.19 kg dm –3 in selectively logged peat swamp forest, clear–cut peatland and maize– cultivated peatland, respectively. Unrubbed fiber contents were on average 74, 35, and 58% volume basis, respectively. Water release potential, at low suction (high matrix potential), was significantly reduced in the top layer. Based on the three– parameter equation, reducing water release potential was attributed to decreasing the constant rate of water release (kwr) and the maximum volume of water release (Vmax). Values of kwr and Vmax in the top 0–15 cm layer of undeveloped site were 0.0346 cm –1 and 47.69%, whilst in the clear–cut and maize –cultivated sites they were respectively 0,0135 cm –1 and 44.03%, and 0.0363 cm –1 and 41.50%. This three–parameter model of water release potential may further be developed to estimate available water for growing crops on peat soils at dif ferent water table heights. At high matrix potential there was more water volume over air volume of peat soils under developed sites compared with undeveloped sites. This implies that as a growing medium the quality of peat soils decreases with agricultural development. Based on correlation analysis, changes in selected hydro–physical properties of peat soils were significantly related to changes in bulk density and fiber contents, and so related to the progress of peat decay.
11 citations
TL;DR: It is concluded that variations in forest structure, tree species diversity and floristic composition at genus and family levels were small at this spatial scale, and that the results obtained in any single 0.25-ha plot can be reasonably extrapolated to the other stands on similar topography in this area except dominance of species.
Abstract: We examined the variation in forest structure, species diversity and floristic composition of trees for different minimum sizes (≥ 4.8 cm and ≥ 10 cm stem diameter) in six 0.25-ha plots of a tropical montane forest (1600 m above sea level) on Mount Kinabalu, Sabah, Malaysia. Four plots are parts of a 2.74-ha plot, and two are located 75 m and 200 m apart from the others. In all, the six plots are distributed in an area of approximately 8 ha (450 m × 175 m) on similar topography (sideslopes). Forest structure (e.g. stem density, basal area and estimated aboveground biomass) appeared to be similar among the six plots. Tree species richness per plot varied little (91-102 for stems ≥ 4.8 cm diameter and 60-72 for stems ≥ 10 cm diameter). Several indices of species diversity (or evenness) were also within narrow ranges, correlated with species richness. The dominance of species varied greatly among the six plots, but that of genus and family was relatively consistent. Analysis based on the 2.74-ha plot suggested that this reflected different habitat associations with microtopography among congeneric or confamilial species and intraspecific aggregation. Similarity indices based on presence/absence of species (e.g. Jaccard and S.rensen indices) were negatively correlated with spatial distances between plots (for stems ≥ 4.8 cm diameter), but those based on relative abundance of species were not. Indices of species diversity (or evenness) and similarity based on basal area were correlated between two minimum sizes (≥ 4.8 cm and ≥ 10 cm diameter), but those based on number of stem or presence/absence of species were not. We concluded that variations in forest structure, tree species diversity and floristic composition at genus and family levels were small at this spatial scale, and that the results obtained in any single 0.25-ha plot can be reasonably extrapolated to the other stands on similar topography in this area except dominance of species.
11 citations
TL;DR: In this paper, a long-term mangrove research site on Pohnpei Island, the Federated States of Micronesia, was examined on the seaward and landward sides of a longterm MANG to estimate the contribution of litter deposited on the MANG forest floor to carbon accumulation.
Abstract: Litter production, accumulation, and decomposition were examined on the seaward and landward sides of a long-term mangrove research site on Pohnpei Island, the Federated States of Micronesia, to estimate the contribution of litter deposited on the mangrove forest floor to carbon accumulation in mangrove forests. The annual litter production in the forest site was relatively high, 15 Mg ha-1 yr-1. The litterfall was composed of leaves (55%), reproductive organs such as flowers and seeds (34%), and bark and small branches (11%). The seasonal fluctuation of the litter was small. The amounts of litter deposited on the floor were 0.51 Mg ha-1 on the seaward side and 0.76 Mg ha-1 on the landward side. Compared with the mangrove substratum, the litter deposited on the forest floor has an extremely low capacity to act as a carbon sink. During the first year of the leaf decomposition, the mangrove leaves decomposed markedly (k = 7.0 - 18.2) faster than the leaves of the terrestrial mahogany forest (k = 0.3). The mangrove leaves decomposed rapidly, losing more than 60% of their initial weight in the first month. This high rate might result from leaching of labile fraction from the leaves by the high frequency of immersion as well as by the high levels of activity of decomposers on the forest floor at high temperatures and humidity. Moreover, the effect of crab’s feeding on the litter disappearance could not be disregarded. Tidal litter transportation rate was examined by collection of marked leaves along a tide level gradient. The transportation rate was greater as the highest tide level was higher. This study clarified that the disappearance of litter on the mangrove forest floor was strongly influenced by the tide, especially on the seaward side, as well as by the active microbial and faunal decomposability. We concluded that, despite the mangrove forest’s high litter production, litter on the forest floor did not contribute much to carbon accumulation, especially on the seaward side, since litter was disappeared rapidly from forest floor by tidal exportation and strong microbial activity.
10 citations
TL;DR: In this paper, the Cikaniki and Cidikit rivers were sampled in 2001 and 2002, respectively, to study the relationship between the distribution of mercury and humic acid; however, this relation was still unclear.
Abstract: Mercury speciation was studied in the Cikaniki and Cidikit rivers, both of which have been contaminated by mercury as a consequence of gold mining. Sampling was carried out in October 2001 and in September 2002. It is well known that humic acid has the ability to bind metal ions, an environmentally important aspect because complex formation might change the toxicity and movement of mercury.High concentrations of mercury were found in suspended particles at all sampling sites. Scanning Electro Microscope (SEM) images of suspended particles and elemental analysis data by X-Ray spectroscopy showed that the suspended particles were a clay-like mineral. Cationic and anionic species of mercury were also found in the water samples but at relatively low concentrations. Since the presence of humic acid was observed in the river water, the anionic species of mercury seemed to be a complex of mercury with humic acid. The total mercury concentration in the Cikaniki River was higher than the maximum tolerable concentration (0.002 mg ⁄ l) allowed for river water by Indonesian Government regulations. In the Cidikit River, the concentration of mercury was less than the maximum tolerable concentration for river water. Humic acid concentration was also measured to reveal the relationship between the distribution of mercury and humic acid; however, this relation is still unclear.In the laboratory, the conditional stability constant and capacity of humic acid and mercury to form complex were estimated by Scatchard plot, at pH 6, using a 5 mg ⁄ l humic acid and mercury (II) solution in concentration range of 0-0.6 μM. The value of conditional stability constant between mercury (II) and humic acids is log K’= 6.5 at pH 6 and the complexing capacity of mercury (II) is 0.38 μM.
10 citations
TL;DR: In this paper, a tropical hill forest in Ulu Gadut, West Sumatra, Indonesia, was studied based on the tree numbers of common species in 20 × 20m quadrats, habitat axes representing floristic composition were determined by detrended correspondence analysis Axis 1 was significantly related to the slope convexity and stand height of a quadrat.
Abstract: The floristic composition of a tropical hill forest in Ulu Gadut, West Sumatra, Indonesia, was studied High species diversity and differences in the floristic composition compared to other forests in West Malesia were observed Based on the tree numbers of common species in 20 × 20m quadrats, habitat axes representing floristic composition were determined by detrended correspondence analysis Axis 1 was significantly related to the slope convexity and stand height of a quadrat, indicating that the floristic composition is influenced not only by topography but also by growth stage and disturbance The major disturbance in this forest prior to the study was local logging, the influence of which was found not only in the variation in floristic composition but also in vegetation development after disturbance We concluded that the harvest of upper layer trees by local loggers enhanced the growth of lower layer tree species in this forest The estimated original vegetation without logging differed from that of other forest stands in West Malesia because of its relatively low dominance of Dipterocarpaceae and high dominance of Fagaceae This might have been caused by the lower temperature of the plot compared with other forests at similar altitudes in West Malesia regions This climatic feature is also thought to contribute to the high diversity of the plot
TL;DR: Among the invertebrate assemblages, cladocerans and/or copepods dominated in both regions, on the other hand, relative abundances of chironomids and ostracods were significantly higher in CK and WJ, respectively.
Abstract: Composition of meio- and macroinvertebrates associated with aquatic macrophytes was compared between acid waters in a peat swamp area of Central Kalimantan (CK) and neutral waters in West Java (WJ). Among the invertebrate assemblages, cladocerans and/or copepods dominated in both regions. On the other hand, relative abundances of chironomids and ostracods were significantly higher in CK and WJ, respectively. Eighteen taxa of oligochaetes were recorded from the regions, of which 14 ones belonged to the subfamily Naidinae of the family Tubificidae. The oligochaete composition was quite different between CK and WJ, in that Pristina species dominated in CK, while Stylaria fossularis dominated in WJ. WJ harbored more diverse oligochaetes than CK. The difference in oligochaete composition is related to water acidity.
TL;DR: An initial study on the habitat distribution and diversity of plants as feed resources for mouse deer (Tragulus javanicus) and barking deer (Muntiacus muntjak) was conducted at Gunung Halimun National Park.
Abstract: An initial study on the habitat distribution and diversity of plants as feed resources for mouse deer (Tragulus javanicus) and barking deer (Muntiacus muntjak) was conducted at Gunung Halimun National Park. The survey was carried out by visiting places where mouse deer and barking deer are usually seen, and collecting specimens of the plant species on which those animals feed. In Gunung Kendeng the mouse deer prefers forest habitats up to a height of 1,100 m asl, such as dense bush, rock crevices or tree hollows, dense tea plantations, and bush areas not far from rivers. Barking deer prefer forests up to a height of 1,100 m asl in Gunung Kendeng, but up to 1,600 m asl in Gunung Botol. Barking deer prefer dense bush on the forest edges. Results showed 50 plant species consisting of 22 families as possible feed resources for mouse deer and barking deer.
TL;DR: In this paper, seasonal discharge measurements and water samplings were carried out at the upper reaches of the Sebangau River in Central Kalimantan, Indonesia, in order to clarify the relationship between river discharge (flux) and water chemistry.
Abstract: Seasonal discharge measurements and water samplings were carried out at the upper reaches of the Sebangau River in Central Kalimantan, Indonesia. The samples were analyzed for chemical contents and total suspended solids, in order to clarify the relationship between river discharge (flux) and water chemistry. The river runs through tropical peat forest in Palangka Raya, Central Kalimantan. The Sebangau River flux was classified into dry season flux and rainy season flux by flow quantity. But water quality did not differ greatly between the two seasons. The great rainfall-retentiveness of tropical peat bogs may contribute to stability of the runoff load factor.
TL;DR: In the soft gel medium, EC–K013 stimulated the growth of a root–associating fungus, tentatively identified as Nectria sp.
Abstract: The rhizoplane microorganisms of Melastoma malabathricum, distributing throughout the acid sulfate and peat soils of South Kalimantan, Indonesia, were investigated, using a soft gel media of N–free Winogradsky’s mineral solution solidified with 0.3 % gellan gum. Two bacteria, Sphingomonas rosa EC–K013 and Burkholderia cepacia EC–K014 belonging to the subclasses of α– and β–Proteobacteria, respectively, emerged in the nitrogen–free medium. Inoculation of S. rosa EC–K013 in the M. malabathricum seedlings grown in N–free, 1/4 Hoagland’s No. 2 medium (pH 3.0) resulted in better growth of the seedlings. In the soft gel medium, EC–K013 also stimulated the growth of a root–associating fungus, tentatively identified as Nectria sp. and a nitrogen–fixer, Mesorhizobium sp., suggesting that S. rosa plays an important role in promotion of microfloral devlopment around the rhizosphere of some acidic soil–adapting plants.
TL;DR: In this paper, the authors studied the altitudinal gradient of vegetation of the Barisan range in a coastal region near Padang, West Sumatra, in 10 plots distributed from 600 to 1780 m.
Abstract: The altitudinal gradient of vegetation of the Barisan range in a coastal region near Padang, West Sumatra, was studied in 10 plots (0.1-6.55 ha) distributed from 600 to 1780 m. Trees with a diameter at breast height of more than 10 cm were employed for classification of the vegetation. Four vegetation zones, two types of montane and two types of lowland vegetation, were recognized based on cluster analysis, floristic information, and the physiognomy of these forest stands. An upper zone of montane vegetation (Lower montane Fago-Myrtaceous forest) was distinguishable from a lower zone (Sub-montane Fago-Myrtaceous forest) due to the remarkable dominance of several species of Fagaceae and Myrtaceae, and its lower canopy height. The two zones of lowland vegetation (Upper hill dipterocarp forest and Mid-hill dipterocarp forest) were distinguishable by their species composition of Dipterocarpaceae and stratification of the stand. The altitudinal zonation corresponded well with classic zonation patterns previously reported for West Malesia, but the critical threshold altitudes were lower in comparison with those in other regions. The borderline between the lowland and montane vegetation, corresponding to a Kira’s warmth index of WI = 180 °C · month, was around 200 m lower in Padang than in other regions of West Malesia, and the critical altitude between the two zones of lowland vegetation was also around 300 m lower in Padang than on Mt. Kinabalu. The characteristics of altitudinal zonation in Padang were discussed with reference to the climatic features of this region, namely, the low temperature and hyperhumidity.
TL;DR: The aggressive reproduction strategy of the naturalized shrub Piper aduncum L., introduced from humid Neotropical regions, was studied in Sumatra paying special attention to fruit production and leaf longevity and a mathematical model for optimum leaf longevity took into account the maintenance costs of a single branch.
Abstract: The aggressive reproduction strategy of the naturalized shrub Piper aduncum L., introduced from humid Neotropical regions, was studied in Sumatra paying special attention to fruit production and leaf longevity. A single piper shrub produced inflorescences throughout the year and the annual production of a mature inflorescence was estimated at 7.8 ton ha-1 yr-1. It was also shown to consume 100 kg of nitrogen per hectare for annual fruit production on the basis of its crown projection area, while 60 % of nitrogen in leaves and branches was reabsorbed with senescence and death. Average leaf longevity was 158 ± 48 days with an average turnover rate of 2.5 ± 0.51 yr-1. This high turnover rate is considered advantageous for continuous fruit production from early growth stages through effective allocation and reabsorption of energy and nutrients. Next, a mathematical model for optimum leaf longevity was proposed taking into account the maintenance costs of a single branch. The model showed that the observed leaf longevity approximately satisfied the expected minimum maintenance cost of a mature branch. A short leaf life span could save stem and branch construction costs through effective leaf production with low biomass. Economical branch structures in terms of energy and nutrient use could allow allocation of more resources to fruit production. This prioritization of fruit production over construction of a durable stem and branches could be evaluated as an adaptive living strategy of this shrubby pioneer species. Based on the proposed model, the adaptive survival strategies of other species were discussed with special reference to the relationship between leaf longevity and branch structure.
TL;DR: Rice production has been monitored at 8005 plots of rain-fed paddy field in a village in Northeast Thailand for the period from 1978 to 2002 as discussed by the authors, and rice crop was evaluated and classified into 4 classes, i.e. "good", "poor", "crop failure", and "no planting".
Abstract: Rice production has been monitored at 8005 plots of rain-fed paddy field in a village in Northeast Thailand for the period from 1978 to 2002. Rice crop was evaluated and classified into 4 classes, i.e. “good”, “poor”, “crop failure” and “no planting”. Distribution mapping of crop performances showed a large variability among plots, and also extreme changes among years mainly due to flood and drought. All paddy fields were classified into 8 types by cluster analysis. Lower and unstable production was observed in upper paddy fields. Areas with poor yield and no planting paddy fields have decreased in recent years owing to expanding supplementary irrigation and the direct seeding method. Supplementary irrigation is carried out by purchasing water from canals or sucking up river water using engine driving pumps at planting time or severe drought. This indicates that a gradual improvement in rice production is possible with rain-fed rice cultivation. However, large crop failure still occurs frequently especially in areas nearer to rivers.
TL;DR: Sphingomonads are found as the most dominant rhizobacteria in local rice and also in weeds that are adapted to the strongly acidic wet soil, and studies of these acid-tolerant, root-associating, and often nitrogen -fixing, rhizospherous bacteria are likely to be important key factors.
Abstract: We preliminarily investigated the correlation between productivity and the diversity of free-living nitrogen-fixing bacteria on the rhizoplane of local rice varieties, including Siam Unus, Siam Adil and Siam Pandak, all tolerable to acid-sulfate soil in South Kalimantan, Indonesia. The rhizobacteria of some unidentified weeds of native-grown in the acidic paddocks were also searched. Subsequently, sphingomonads, including Sphingomonas spp. and Sphingobium spp., are found as the most dominant rhizobacteria in local rice and also in weeds that are adapted to the strongly acidic wet soil. Other unique rhizobacteria are Alcaligenes spp. that powerfully neutralized their cultured media. To understand how the local variety of paddy rice can tolerate acid-sulfate soils with very low soil pH (2.5-3.5), studies of these acid-tolerant, root-associating, and often nitrogen -fixing, rhizospherous bacteria are likely to be important key factors.
TL;DR: In this paper, a 153 cm peat swamp forest core in Central Kalimantan provides a picture of environmental change and fire history from 8440 to 6540 yr BP.
Abstract: A pollen and charcoal record from a 153 cm peat swamp forest core in Central Kalimantan provides a picture of environmental change and fire history from 8440 yr BP to 6540 yr BP. The existence of charcoal in all sample layers indicates that fire occurred in the tropical peat swamp forest throughout the period. In the earliest period, from ca. 8440 to 8000 yr BP, there was a Camnosperm comp.-Cratoxylum forest. Palaquium comp. and Sandoricum comp. were also important constituents in this forest. Subsequently, dry climatic conditions prevailed between 7240∼8000 yr BP. These climatic conditions increased the fire frequency and intensity causing vegetation change, i.e. the encroachment of Palaquium comp. and the replacement of the Camnosperma comp.-Cratoxylum forest with a Palaquium comp.-Cratoxylum forest. A Camnosperma comp.-Cratoxylum forest with more prominent representation of Elaeocarpus, Ilex, Randia, Rubiaceae and Sterculiaceae returned to the site when wet climatic conditions prevailed again at ca. 7240-6540 yrs BP. Returning wet climatic conditions reduced fire frequency, prevented intensive fires and allowed for more extensive growth of Camnosperma comp., Elaeocarpus and Ilex, but limited the growth of Palaquium comp. and Sandoricum comp.
TL;DR: In this paper, the macro-and micro-nutrient status of tropical peat soils in natural forests and under cultivation was studied in Malay peninsular and Sarawak.
Abstract: Most tropical peat soil is classified as Oligotrophic peat due to their low N, P, K, and Ca content. The macroand micro-nutrient status of tropical peat soils in natural forests and under cultivation was studied in Malay peninsular and Sarawak. The average concentrations of P, K, Ca, Mg, and Fe of tropical peat were significantly lower than those of grass peat in Japan. The P, K, Ca, Fe, Mn, and Zn concentrations of surface soils were higher than those of subsoils. Average concentrations of Ca, Mg, and Fe in Sarawak soils were lower than those of Malay peninsular soils for both surface and subsoils. Based on the analysis of the distribution o f the meta l for ms, most Cu and Fe occurred in strongly chelated and nonextractable forms (non-available form). The concentrations of water soluble and exchangeable forms (available form) of Mn, Zn, and Cu were very low. In the case of fertilized soil, heavy metal content of the surface soils were about 3 to 15 times as high as those of the subsoil. Most of this was accounted for by the weakly chelated, strongly chelated, or non-extractable forms, because the pH of the surface soil was higher than that of the subsoil. As the chelating ef fect of humic substances is likely to be pronounced for high soil pH, heavy metals applied in fertilizers were changed into nonavailable forms. The concentrations of N and P were fairly high in the soil solution in tropical peat profile, except for P in the profile near the center of the peat dome in a climax forest. Dissolved P consisted mostly of or tho phosphate, whereas a large part of N was in organic forms. K concentration was not low in the soil solution in the forest as compared with the global average of river water. Low K in soil solution profile was observed at the Sago plantation field in deep peat. Forest clear-cutting disturbs the K cycling in an ecosystem. The concentrations of Ca, Mg, and Fe were fairly low in the soil solution of peat profile as compared with the average of river water in Japan. The potential capacity to supply K, Ca, and P was not necessarily high, in spite of the apparent high level obser ved for the soil solution composition. Therefore, from the viewpoint of nutrient dynamics, the potential for using reclaimed peat land is rather limited, especially under low input management.
TL;DR: In this paper, there were no differences in water use rate, vulnerability to embolism, maximum rooting depth of sapling-sized plants, or basal area increment of trees in a dipterocarp forest and a tropical heath forest.
Abstract: Contrary to conventional wisdom or hypotheses following from it, there were no differences in water use rate, vulnerability to embolism, maximum rooting depth of sapling-sized plants, or basal area increment of trees in a dipterocarp forest and a tropical heath forest. There is strong anecdotal evidence for water use partitioning in heath forest leading to strikingly different susceptibilities to drought-induced mortality among species. Good management of heath forest sites requires the maintenance of closed canopy over large areas and protection from fire and whatever else might destroy the surface organic layer.
TL;DR: The relationship between humans and plants at this study site was flexible and influenced mainly by topography and land-use and partly by socioeconomic conditions and invasion of naturalized species.
Abstract: Land-use patterns and plant use were recorded at two neighboring villages in central Laos. Bak village is located upland and surrounding land includes an extensive forest area, fallow fields, shifting cultivation fields, grassland, waterside, and paddy fields. During the study period the forest area supplied the largest number of useful plants. Nakhou village is, by contrast, in a lowland area and utilized land included small areas of remnant forest, grassland, waterside, and extensive paddy fields. Paddy fields contained the largest number of useful plants, followed by forest. Villagers compensated for the lack of forest resources in Nakhou village by maintaining and managing a diversity of trees within the paddy field land-use class. In addition, residents of the surrounding villages made the most of locally available plant resources and supplemented each other’s resources through trading. Analysis of local plant use at different geographical scales showed that the relationship between humans and plants at this study site was flexible and influenced mainly by topography and land-use and partly by socio-economic conditions and invasion of naturalized species. Species inventories and descriptions of the external factors influencing plant use at different geographical scales within a spatially heterogeneous landscape, will form an important basis for management and conservation of the plant resources of local communities.
TL;DR: Tropical trees that adapt well to these soils were able to secrete oxalic and citric acids to acquire P by solubilizing of Fe-P and Al-P, whereas tropical pastures or grasses showed high P utilization efficiency and high root-shoot ratio by P deficiency.
Abstract: It is known that the tropical pastures or grasses; Arachis pintoi, Brachiaria ruziziensis, Panicum maximum, Panicum repensi, Pueraria phaseoloides, and Stylosanthes hamata, and the tropical trees; Acacia mangium, Anacardium occidentale, Hevea brasiliensis, and Melaleuca cajuputi adapt well to acid soils which have low phosphorus (P) and high aluminum (Al). In this study, top and sub soils were collected from highly weathered soils in peninsular Thailand for chemical analysis and phosphorus fractionation, and the adaptive mechanisms of these plants were examined from the aspect of phosphorus utilization efficiency and root exudation of organic acids and acid phosphatase by culturing plant seedling in complete, phosphorus deficient (-P), high Aluminum (+Al), and P deficient / high Al (-P/+Al) solutions. Results showed that both available P and total P in soils were low, and organic P was the main fraction. Fe-P and Al-P were the dominant inorganic P sources in these soils. The secretion of acid phosphatase increased distinctly in -P treatment from roots of Stylosanthes hamata only. Tropical trees that adapt well to these soils were able to secrete oxalic and citric acids to acquire P by solubilizing of Fe-P and Al-P, whereas tropical pastures or grasses showed high P utilization efficiency and high root-shoot ratio by P deficiency.
TL;DR: Indonesia is the second largest country in the world in terms of tropical rain forest areas, after Brazil in South America, which consist of many forest types and also very rich biological diversity.
Abstract: Indonesia is the second largest country in the world in terms of tropical rain forest areas, after Brazil in South America, which consist of many forest types and also very rich biological diversity. Indonesia is one of the main world centers for biodiversity and it can be said to have “mega diversity”. The high pressure on tropical forest ecosystems in the form of natural and man-made disturbances, i.e. deforestation and other practices has caused the high rate of biodiversity losses on an unprecedented scale. To curtail this problem, we must be aware, do more research and act to save our biodiversity, which includes ecosystem, species and genetic diversity. Loss of biodiversity also means loss of human traditional knowledge on biodiversity. This paper will discuss awareness, research on biodiversity (government and non-government) and what kind action and regulation have been made by the Indonesian government, in connection with saving, protecting and conserving biodiversity.
TL;DR: In this paper, the balance between soil N supply from the mineralization and crop N uptake in the local transplanting system in South Kalimantan was studied, where the experiment took place in Tambaksirang Baru (03°26’31”S, 114°35’29”E), Gambut District, West Java, Indonesia.
Abstract: Most of acid sulfate soil areas in South Kalimantan are recommended for growing rice. Due to unfavourable soil conditions such as low pH and unpredictable water level, farmers grow local rice varieties. The farmers use a multiple transplanting system not only to multiply the seedling population but also to cope with the conditions. In addition, most farmers do not apply fertilizer after the last transplanting, but the yield level is not low. Nutrient (particularly nitrogen, N) availability and utilization by the rice crop are the key for this, but N balance in the local multiple transplanting system has been poorly understood. We therefore studied the balance between soil N supply from the mineralization and crop N uptake in the local transplanting system in South Kalimantan. The experiment took place in Tambaksirang Baru (03°26’31”S, 114°35’29”E), Gambut District South Kalimantan. Two farmers, paddocks separated by a village road were chosen for the study. The N mineralisation measurements were carried out on a monthly basis after the planting. At each sampling date, above and belowground parts of rice plants were collected for biomass and N content determination. At the end of the growing season, we observed that the biomass, N uptake and release from the soil were 9.5 and 7.1 Mg DM ha-1; 36.0 and 27.8 kg N ha-1; and 13.37 and 8.32 kg N ha-1 for plot 1 and 2 respectively. The higher N in the crop than that supplied by soil indicates that there are other sources of N for local rice grown in acid sulfate soil.
TL;DR: The findings indicate that low survival rate and poor growth of the trees can be attributed to both ground level and biotic disturbances.
Abstract: The aim of this study is to clarify the survival and growth performances of six native mangrove species (Avicennia officinalis, Avicennia marina, Bruguiera sexangula, Heritiera fomes, Rhizophora apiculata and Sonneratia apetala) that were replanted on abandoned paddy fields in the Ayeyarwady (AYWD) Delta of Myanmar where natural mangroves once existed. The findings indicate that low survival rate and poor growth of the trees can be attributed to both ground level and biotic disturbances. The growth of trees at low ground was obviously better than that of trees at high ground. At low ground, S. apetala demonstrated the best growth and R. apiculata had the highest survival rate. At high ground, the survival and growth rates of A. officinalis were the best. All the species replanted showed the highest increments of tree height from the middle of rainy season to the beginning of winter.