請用此 Handle URI 來引用此文件: http://hdl.handle.net/11455/21516
標題: 野火對臺灣主要森林生態系影響之研究
Effects of wildfires on the main forest ecosystems in Taiwan
作者: 呂金誠
LYU, JIN-CHENG
關鍵字: 野火
台灣
生態系
影響
干擾因子
出版社: 植物學研究所
摘要: 野火是森林生態系主要干擾因子之一。本研究係探討野火對於臺灣主要森林生態系之影響, 包括林火發生情形、對林地之影響、對植物之影響以及火燒後之演替過程等,以作為自然保育與森林經營之參考。綜合研究所得之結果, 摘述如下: 1.臺灣地區於乾季或在某些林型, 火燒發生頻繁。在1967∼1988年間森林 野火平均每年33.6次, 平均每年焚燒1,256.71公頃。近十年來因濫墾引 發之野火明顯下降, 但因炊火、照明以及原因不明等之野火明顯升高。 2.火燒後因林冠疏開及林地吸熱性質的改變, 表土溫度顯著地提高。火燒 區在日間最高溫較對照區為高, 此種差異高達16.2℃。 3.因冠層截留量與土壤孔隙度的下降, 以及枯枝葉層之燒除, 火燒後林地 貯水能力下降, 逕流量和沖蝕量均顯著提高。在束卯山, 火燒後的第一 個雨季逕流量增加45%,而沖蝕量高達每公頃170m 。 4.火燒後初期, 因大量的養分從枯枝葉怪及植物體中釋放至林地, 土壤有 效性養分和pH值均增高。 5.萌蘗為植物在火燒後存活的主要機制。松樹類因缺乏萌蘗能力, 其完全 致死率高達50∼100% 。而闊葉樹類則具胡旺盛之萌蘗能力, 其致死率 僅為1∼19 %左右, 且致死率隨著地際直徑之增加而降低。在萌蘗形式 上, 以根際萌蘗為主, 約占存活闊葉樹類的60∼90%, 其餘呈枝幹萌 蘗。 6.火燒後, 土溫的提高、有效養分的大量增加、光照之增加等為促增植物 大量開花結實的主要原因。蘇鐵蕨在火燒後著生孢子的植株為未火燒區 之23倍, 同時其著生孢子的數量, 亦遠多於未火燒區。火燒區淡竹葉每 一花稈小穗的數目亦較未火燒區多1.7倍。 7.火燒後因林床裸出、表土溫度變化較大、林下光照增加等, 導致植物大 量天然下種。臺灣二葉松、昭和草、蘇鐵蕨等陽性植物在火燒後均有多 量下種的行為。火燒似有助於衡有的蘇鐵蕨之存續。 8.植物為適應火燒之選擇壓力, 乃演化出特殊機制。在臺灣地區堪稱為火 燒適存植群的有臺灣二葉松林及高山草生地, 其主要組成分子如臺灣二 葉松林、芒草類、巒大蕨及玉山箭竹等, 均會累積多量燃料, 促使火燒 發生, 以持續其優勢地位。其他較常火燒之植群, 如相思樹林和熱帶季 風林等, 係人為不慎或為特定目的縱火之波及, 並不屬火燒適存植群。 海岸林投灌叢亦因燃料累積及受人為干擾, 而常引發火燒, 唯火燒對其 優勢之維持並不似臺灣二葉松、玉山箭竹及高山芒之明顯。
wildfere is an important factor disturbing forest ecosystems. The effects of wildfire an Taiwan red-pine forest, Taiwan acacia forest, monsoon forest, alpine grassland and Pandanus shrub were studied. Results obtained are summarized as follows: 1.Forest fire occurred frequently in the dry season, especially at Taiwan red-pine forest and Pandanus shrub community. During 1967~1988, 706 fires occurred and 127,647.73 hectares were burned. During the past 10 yrars, The frequency of fires caused by illegal farming decreased, but those caused by campfire and unknown reasons increased. 2.Dre to crown opening and albedo effect, the highest daytime temperature at surface soil increased up to 16.2@ after burning. 3.Post-fire runoff and erosion increased resulted from the decrease of soilporosity and crown interception as will as the consumption of litter layer. During the first rainy season after fire at Tou-mou Mt., runoff increased by 45% and 170 (圖表省略) /ha surface soil was eroded. 4.Abundant nutrients were released form litter layer and plant body after been burning. Both available nutrients and soil pH value were increased after burning. 5.Mortality of pine trees by fire was 50~100%, but it was only 1~19% for hardwoods due to their vigorous sprouting ability Mortality rate. For survived hardwoods,60~90% showed basal sprouting; the others showed epicorrmic growth. 6.Flowering, fruiting and spore-bearing were enhanced after fire due to the increase of nutrient availability, lighy radiation and soil temperature fluctuation. Following burning, spore-bearing indivedual of Brainea insignis increased by 23 times; spikelet number of Lophatherum gracile increased by 1.7 times. 7.Natural seedlings of shade-intolerant Pinus taiwanensis, Crassocephalum crepidioides, Brainea insignis, etc., were abundant following burning. Periodic fires might be beneficial for the subsistence of rare Brainea insignis. 8.It is suggested that, Taiwan red-pine forest and alpine grassland are fire-dependent communities. Pinus taiwanensis, Miscanthus spp., Pteridium aquilinum subsp.wightianum, and Yushania niitakayamensis cam accumulate abundant fuel and induce the occurence of fires and thus maintaining their dominance. Most fires in Taiwan acacia forest and monsoon forest were incidently man-caused or burned for certain purpose. These two forest types ane not fire-dependent communities. The Pandanus shrub at coastal area could be considered as intermediate to resist. wildfires.
URI: http://hdl.handle.net/11455/21516
顯示於類別:生命科學系所

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