To explore the effective countermeasures against the simultaneous degradation, i.e. soil erosion and loss of bases, of land resources in northeast Thailand, we tested the performance an agro-forestry system at Yang Khi Nok Village, Khuangnai District, Ubon Ratchathani Province. Establishment of agro-forestry system aims at a sustainable management of both cropland and forest.
Pineapple (Ananas eomosus (L.) Merr) and kenai (Thai kenai, H sabdariffa L. var. altissma) were cultivated as cash crop and three rows of fruit tree (psidium guajava, Cocos nucifera, Pithecollobium dulce, Punica granitum, Tamarindus indica, and Zizyphus jujuba) were placed among the cash crop rows. Erosion control belt (8 treatments) composed of 3 trees (Phyllanthus acidus, Eucalyptus camaldulensis, and Azadirachta indica), 3 grasses (Vetiveria nemoralis, Cymbopogon citratus, and Sporobus virginicus), rice straw mulching, and control was introduced at the lower end of the subplot. A small catchment was also installed to collect the eroded soil.
Soils in this plot has sandy soil texture with a high erodibility. Soil erosion at the current work was not so severe in all treatments. It was suggested that fruit tree planting area prevented soil erosion because this area was not plowed. Tree treatment plots in the erosion control belt, however, showed a greater soil erosion and a loss of bases, compared with others. This was attributed to an insufficient weed growth to cover the ground surface and low soil moisture content at the erosion control belt in the tree treatment plots. However the mass of eroded soils even in the Eucalyptus plot gradually decreased during the succeeding years (1997-2000) presumably due to tree crown and/or litter coverage on ground surface. Thus it can be considered that, in terms of erosion control, grass species is better but tree species can also have considerable potential for utilization in the long run.

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We investigated the effect of soil heating and rewetting on the characteristics of Ultisols from Pendopo, South Sumatra Province, Indonesia, in a laboratory experiment. Soil samples from the depth of 0-10 cm were subjected to different temperatures (100, 300, and 500°C) for different periods (4, 8, and 12 hr). The heated soils were then either rewetted or un-rewetted with deionized water. Heating significantly changed the color from dark brown to red, and significantly increased sand fraction and decreased clay fraction. The changes in soil fraction were observable during the first four hours of heating. Heating had drastic effect on soil mineralogy, even at lower temperature. Significant changes were also observed in soil chemical characteristics. Total C and N were almost totally eliminated at 500°C regardless of the heating time but increased with watering as compared with those did not receive water treatment. Soil pH also increased with heating up to 300°C in accordance with decreases in exchangeable Al and H of the soil. Watering further increased the pH, which was most likely due to decreases in soluble Al and H. Exchangeable bases and CEC significantly decreased with heating but increased again with watering. P also significantly decreased with increasing temperature. Heating time did not exert significant effect on available P, suggesting that the losses of P occurred mainly within the first 4 hr of heating. The results obtained partly explained immediate fertility degradation of heated soil unless proper management means are employed.

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A quantitative analysis was done for the root system of Xylocarpus granatum with reference to the Pipe model theory of tree form proposed by Shinozaki et al. (1964a, b). For this objective, six root systems of X. granatum were excavated using a water-pump, and the roots were weighed for respective diameter categories. A significant allometric relationship between the squared stem-base diameter and the individual root weight was seen. The coefficient of this relationship was statistically regarded to be 1.0, meaning that the individual root weight is proportional to the squared value of stem-base diameter. We also analyzed the relationship between diameter and number of roots for the six sample trees. The number of roots with a given diameter and length was calculated from the weight and the specific gravity of roots. Significant linear relationships were recognized in this relationship for the six sample trees. For all sample trees, the coefficients of relationships were statistically regarded to be - 2.0. From these analyses based on population and individual level, we conclude that the root system of X. granatum obeys the pipe model. Application of this model is helpful in the estimation of root biomass, since individual root weight can be estimated from a proportional constant and the stem-base diameter of a mangrove tree.

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One of the most important biogeochemical processes in estuary sediment is microbial sulfate reduction, producing iron sulfide (pyrite) - the significant form of sedimentary sulfur. The oxidation of iron sulfide causes acidification of the environment. To study these biogeochemical processes, estuary water salinity and sulfate concentrations were determined and sediments from the Klong Ngao mangrove estuary were sampled during the August 2000 wet season. In situ sediment pH and the sediment oxidation-reduction potential were measured. Organic matter concentrations and total sulfur concentrations of the air-dried sediments and the chemical properties of the sediment water were investigated. The estuary water salinity and sulfate concentrations at the head were remarkably lower than at the mouth of the estuary. The in situ pH of mangrove sediments was neutral and the sediment metabolism was anaerobic. The sedimentary organic matter concentrations were relatively high. The amount of sulfur deposited in the sediments at the head was higher than at the mouth of the estuary. Dissolved iron and soluble sulfate, as well as an acid solution, were clearly found in the sediment water at the head of the estuary, whereas the sediment water pH at the mouth remained neutral apparently in association with the presence of soluble bicarbonate ions, and accordingly, dissolved iron was not found in the solution.

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This study reviewed one of the most innovative forest conservation strategies in the Amazonintroducing a timber harvesting management system among rubber tappers. It focused on traditional rubber tapping extractivist population residing within the area demarcated for Porto Dias Extractivist Settlement Project (PAE) in Acre in northwestern part of Brazil. The PAE functions as an extractive reserve administered by the INCRA National Institute of Colonization and Agrarian Reform.
Presenting the base-line study results concerning the household, land tenure, subsistence economy as well as forest use, a series of comparative analysis was conducted for the two classified population targets; those who are participants to the forest management project aiming at sustainable timber harvesting, and those who are not participants to the project. The study tried to identify and examine the determining factors governing the introduction of community forestry management systems for rubber tappers in the region.
Among a variety of land use options concerning the forest use including extractivism of forest produce, agriculture and livestock raising, a specific consideration was given to the extractivism -harvesting of a diverse array of produce to be consumed and potentially commercialized, such as latex, raisin, edible fruits, medicinal oil and plants, fibers and dyes, in addition to animal and fish products.
The study results affirmed that rubber tappers showed a strong orientation towards forest extractivism for a cash earning strategy. Further, it was found that they were maintaining a subsistence economy to the extent their nonmonetary economic values greatly surpass their cash revenues obtained by commercializing available forest and agricultural products and livestock.
Further, ‘the forest dependency’-defined as the degree of dependency on forest extractivism both on monetary and non-monetary terms-was measured and comparatively analyzed between forest management participants and non-participants. Two significant implications were derived. First, a rather homogenous nature in forest use and the resource dependency was identified among rubber tappers for both the participants to the forest management and non-participants within the Porto Dias PAE area in Acre. Second, due to the homogeneity in forest use for the two groups, the incentive for introducing forest management systems may arise influenced by factors independent of the degree of forest dependency, such as access to policy incentives, the degree of social organization and organizational strength of the local population.

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Little Andaman is a small island among the islands of the Andaman and Nicobar islands, a Union Territory of India with geographical area of 73440 ha. The climatic conditions of this island is best suited for red oil palm plantation having annual rain fall of 3500-4000 mm and temperature between 22°C-35°C having 5-7 hours sun shine. In 1979, a project of raising red oil palm plantation over 2400 ha, was sanctioned and the job was entrusted to the Andaman and Nicobar Forest and Plantation Development Corporation. A Tenera seeds were imported from different countries and plantation raised from 1973-86 over an area of 1593 ha. N, P, K, Mg fertilizers used in ratio of 7: 7: 14: 7. In 1981 red oil palm was harvested, but the fruits could not processed due to the absence of factory. In 1983 oil extraction press was installed and a regular processing started in 1984 on wards. A pollinating weevil (Elacidobius kamerunicus) was introduced for efficient pollination in September 1986. Rat, rhinoceros beetle, nettle caterpillar, etc gave the common damage to the palm. To control the rodents, owls were introduced in the plantation in 1991. Parakeets also damage the half ripen fruits. Apart from common diseases of red oil plantation, rot spoil the fruits and bunches. Fungus mycelium attacks the bunch and spoils it. Seeing the adverse impact of red palm oil plantation in the Little Andaman, the India Government has withdrawn the further extention of plantation in different islands of the Andaman and Nicobar islands.

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