To investigate the acid sulfate soil-adapting strategies of South Kalimantan local rice varieties, their rhizoplane pH was preliminarily examined using a glass-made micro-electrode. Although raw acid-sulfate soils in paddocks in South Kalimantan were generally pH 3.5-4.5 and sometimes pH 2.5, pH values of the rhizoplane of living roots directly measured by the microelectrode always converged to approximately 7.0 (variance 0.02-0.22, n=10). On the other hand, the pH of dead roots, which was measured after soil was thoroughly washed from the surface, was relatively low and often close to the soil pH itself. Similarly constant neutral rhizoplane pH was also observed in the major Central Kalimantan tree species, Cratoxyllum arborescens (upland) and Combretocarpus rotundatus (swampy forests). Whilst, two other predominant grasses, Xyris complanata and Imperata cylindrica, inhabiting acidic soils in upland and lowland, had relatively low rhizoplane pH (6.05 and 5.86, respectively), suggesting that these grasses have different strategies than the paddy rice varieties for adapting to acidic conditions. Rhizoplane bacteria are likely to be one of the factors for the maintenance of neutral rhizoplane pH. In fact, some Sphingomonas sp. raised medium pH, originally set at pH 4.0, to 5.5. These findings suggested the importance of cationic charge in the rhizoplane of local rice varieties for adapting to acid-sulfate soil, which is similar to strategy of some arboreal trees inhabiting acidic peat soil.

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Paper mulberry plantations are needed in Thailand due to Thailand’s high demand for paper manufacturing. In this paper, silvicultural systems were investigated to determine for attaining the optimum growth rate and yield. Paper mulberry from five sources (SS, UN, NN, RT and KZ) were planted in eight sites all over Thailand for a provenance trial, while two species (Broussonetia papyrifera and B. kazinoki) were planted at Wiang Sa district, Nan province for a species trial. Moreover, five spacings (1×1m, 2×1 m, 2×2 m, 2×4 m and 4×4 m) were used in RCBD (Randomized Complete Block Design) with three replicates in Wang Chin district, Phare Province for a spacing trial. Survival rate, growth rate, biomass and soil physical and chemical properties were recorded at every site. Paper mulberry can grow in various textures of soil as long as there is a good drainage. Soil fertility had a significant effect on growth and productivity. B. papyrifera had a higher biomass than B. kazinoki with the same growth rate. The number of trees (plant density) had an important effect on biomass. From these data, it is recommended that in paper mulberry plantation narrow spacing is used.

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Natural stands of paper mulberry are the main source of raw material for paper mulberry manufacturing. Stand improvement is needed for proper growth and high yield. Three 5×10 m sample plots (50 m²) of different tree and stem density (low, medium and high density as Plot A, B and C, respectively) were set on Mae Charim district, Nan province, and Wang chin district, Phrae province, Thailand, which are famous for paper mulberry production. Within all plots, soil properties, crown closure, growth and biomass were investigated. In this study, stem density correlated to inner bark biomass; soil fertility and light intensity also contributed to growth enhancement. As for soil nutrients, available phosphorus showed a significant correlation to paper mulberry growth. Although paper mulberry in the Wang chin site had a higher average stem density after the first harvesting than paper mulberry in the Mae Charim site, the former site resulted in a lower inner bark yield that may have been caused by low soil fertility and smaller number of stems in the 1.5 - 3.5 cm DBH class (economical stems) than those in the Mae Charim site, except in plot C.. In both study sites and the two annual harvesting periods, inner bark biomass in Plot C was the highest followed by those in Plot B and then A. . Therefore, among sites with similar soil fertility (site quality), increasing stem density resulted in higher inner bark yield. Applying fertilizer and maintaining 2 - 3 stems m^-2 is recommended for paper mulberry stands in Thailand.

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Changes in wood anatomy linked to canopy height were examined in a Hawaiian wet montane forest along an age gradient of long-term soil-development. The sites have been the location of lava flows 400, 1400, 5000 and 9000 years ago. Lava flows are linked to soil nutrient conditions. The height of the canopy tree, Metrosideros polymorpha was greatest at the 5000-yr site, and was less at the 9000-yr site. The wood density of the canopy tree did not change with substrate age. The vessel frequency increased with substrate age, while the vessel pore area decreased with substrate age. These changes were linked to canopy height. These results suggest that changes in wood anatomy enable effective water transportation at different canopy heights.

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Average air temperature and solar radiation over the past 20 years in Northeast Thailand were mapped using climatic databases, constructed with the daily measurements at meteorological stations, interpolations and GIS tools. The maps made it possible to visualize annual and regional variations in air temperature and solar radiation over a long period. Generally, regional variation in the monthly average of daily mean, maximum and minimum air temperatures, and diurnal air temperature range was small in Northeast Thailand, but in the southern lowland areas and undulating plains, which cover most of this area, were slightly hotter than the northern areas. Solar radiation also showed small regional and yearly variation. Relatively uniform characteristics of air temperature and solar radiation may be one of the reasons for the homogeneous distribution of natural vegetation and agricultural land use in the lowlands and undulating plains of Northeast Thailand, whereas in the mountainous and hilly regions of this area factors other than air temperature and solar radiation may be determinants of its diversified vegetation. Relatively stable and high solar radiation and the warm climate of this region are reasons for its high potential for agricultural productivity, if properly managed.

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Interpolation of rainfall databases of Northeast Thailand of daily measurements at rain stations over 20 years were mapped with GIS tools. Various maps clearly visualized the characteristics of rainfall in this area. Annual and mid-rainy season rainfall showed a descending trend from the northeastern area to the southwestern area, probably due to the southwest monsoon and mountains in Laos and between Central and Northeast Thailand. Yearly variation in annual rainfall in this area was not particularly high, suggesting that its general image as a drought-prone area may be caused by the undulating topography and predominance of sandy soils in this area, which contribute to its vulnerability to flooding and drought. Both mean rainfall amount per rainy day and the number of rainy days in the rainy season showed large regional and yearly variation, but mean rainfall per rainy day was correlated to annual rainfall, whereas the number of rainy days was not strongly correlated to annual rainfall. Large regional variation in the number of rainy days in the rainy season suggests large regional variations in agricultural productivity in this area. The fact that areas near many of the provincial capitals have a high number of rainy days in the rainy season with small yearly variation may indicate relatively high and stable agricultural productivity in such areas that probably supported the establishment of those cities in early days. The duration, onset and end of the rainy season showed small yearly variation, suggesting that these parameters are not solely responsible for the unstable and erratic rainfall in Northeast Thailand.

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Fuels have an important role in fires in forest areas (plantation). Most of the fires that destroy forest plantations are cause by excessive fuels stored in the forest plantation. Those fuels consist mostly of the dead and live fuels (weeds). A live fuel can significantly increase fire risk especially in plots which have predominantly young vegetation before the canopy is close. In this period live fuel is more flammable than dead fuels. Therefore maintenance (weeding) is one method of fire reduction.

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