| Summary: | 碩士 === 國立臺灣大學 === 森林學研究所 === 93 === We can realize the basic properties of Pinus taiwanensis by DSC, and these tests will provide how fuels burn and their heat conductivities. At 120 ℃, carbohydrates will dehydrate first, and decompose above 380 ℃.We can understand the fuels properties by different DSC diagram. At the same time, the second products of trunk after pyrolyzing will pyrolyze again at higher temperature; this potential of continuous burning can’t be neglected. Our research finds that the living needles can pyrolyze easily. The decomposition of needles can result in the total reduction of heat of forest stand from DSC thermogram.
The oven dry weight of Pinus taiwanensis litterbag decreases with treating time. The fertilized litterbag has higher decomposition rate than those of unfertilized ones; the k value is 0.52(+N) and 0.52(-N) after 18 months. Extractive content decrease with time; klason lignin increases oppositely. The unit heat and total heat of Pinus taiwanensis litter decrease estimated by oxygen bomb calorimeter; fertilized litterbag decrease as faster and the effect continued to the fifth month. Fertilization can speed up the decomposition and decrease total heat in a short time.
Endophytes are able to dwell in host plant body by symbiosis and mutalism, but they are not pathogenis. Endophytes are host specific and can be isolated from many softwoods. Endophytes have comprehensive enzyme system, and can play initial role at litter degradation. Crowns of Pinus taiwanensis stands are fully developed, and accumulation of obstinate needles generally thought to assist spread of recent forest fires. Hence, measures to accelerate litter decomposition can decrease risks of fire spread by reducing fuel accumulation. Enzyme systems of fungi have great application potential in pulp and paper industry. This work morphologically isolated 58 endophytes from Pinus taiwanensis; among them, 6 strains belong to Xylaria sp., 12 strains belong to Coelomycetes. After screened by plate assays, 20, 17, 23, 25 strains were found to have degradation capabilities for lignin, xylan, carboxyl methyl cellulose and celluloses, respectively. Hence, this study demonstrated biodiversity of Pinus taiwanensis endophytes and their future applicability.
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