梨山台灣二葉松地面松針分解及其內部真菌之研究

Abstract

大甲溪事業區45林班地之34年生之台灣二葉松林地由基本熱性質分析及差示掃描熱卡計的測定，提供燃料燃燒的熱傳導及延散特性的資料。各試材除活松針外以103 ℃處理之樣品彈氧熱卡計發熱量皆高於70 ℃處理之發熱量。枯落松針經過分解後總發熱量低於活松針。而燃料化學成分不同，由其DSC曲線特徵之差異，有助了解燃料的基本特性。本研究亦發現在輕質燃料中活松針最易熱解。且由活松針與上下層枯落松針之高低溫熱解曲線之變化，說明松葉腐化過程對林分整體熱含量之減低有其作用。 台灣二葉松(Pinus taiwanensis)針葉經由枝葉包(Litter bag)分解試驗得知，隨處理時間增加，烘乾重持續下降。施加氮肥之枝葉包在分解初期分解速率較未施加氮肥者佳，兩者依照分解速率指數模式算出k值(k value)分解18個月後分別為0.52(+N)、0.52(-N)。醇苯抽出物隨處理時間增加而持續降低；卡拉森(Klason)木質素隨處理時間比例有上升的趨勢。由彈氧熱卡計(Oxygen bomb calorimeter)測得二葉松枯枝單位發熱量(Unit heat)與總發熱量(Total heat)皆有下降之趨勢，且以施加氮肥者下降速度較快，此加速效果持續到處理時間第5個月。施加氮肥可在短時間內加速分解的進行，降低總發熱量。 內生真菌能夠在寄主植物體內達成共生或互生的生活方式，但並不會造成寄主的致病性，而某些真菌有某些程度的寄主專一性(Host specificity)。台灣二葉松林分鬱閉，難以分解的針葉，往往被認為是助長森林火災的重要因子，能加速地面松針的分解，也能降低森林火災蔓延的風險。本研究從台灣二葉松(Pinus taiwanensis)針葉中，依不同形態共分類出58株不同內生真菌。初步鑑定成果，6株屬於Xylaria sp.，12株屬於腔孢菌綱(Coelomycetes)。以分解能力對這些內生真菌中作初步鑑定後，發現對木質素、木聚醣、醯化纖維素、纖維素具有分解能力的菌株分別有20、17、23、25株。上述結果顯示台灣二葉松針內部真菌相具有高度生物多樣性，並能分解各種基質，足証內生真菌在未來應用的潛力。

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.