| Abstract: | 野火為一生態系中重要干擾因子,對小型哺乳類直接的影響在於 決定動物是否被燒 死,間接的影響則來自棲地的驟變所造成族群遷入遷 出之反應.適應火後棲地的物種稱之為 火災正傾向種,不適應火後棲地的 物種稱為負傾向種.對於臺灣森林火災生態的研究缺乏. 本研究 目的除 了解小型哺乳類對火災棲地之正負傾向外,並比較火災地與未火災地各小 型哺乳類物種之族群動態是否有差異?另外,就共域性物種而言,亦比較火 災地與未火災地 間,各種類在微棲地資源的選擇利用上是否有不同的區 隔分化現象?由於臺灣山區小型哺乳 類之自然分布狀況受到海拔高度的 明顯影響,因此本研究亦在討論不同海拔高度火災地與 未火災地內之變 差異. 自1995年6月至1996年5月於玉山國家公園塔塔加火災過後地區選 取2800公尺海拔與2000公尺海拔地區之火災地與未火災地各一處,以標記 再捕捉進行小型 哺乳類相對數量估計,並且測量各佈籠點位置24項微棲 地因子來分析微棲地區隔現象. 所捕獲之小型哺乳類共7種, 分別為臺灣 森鼠(Apodemus semotus),高山田鼠(Microtus kikuchii),高山白腹鼠( Niviventer culturatus),黑腹絨鼠(Eothenomys melanogast er),巢鼠( Micromys minutus),長尾鼠句(Soriculus fumidus),短尾鼠句( Anourosorex sq uamipes),其中2800公尺處臺灣森鼠,黑腹絨鼠與短尾鼠 句為火災負傾向種,高山田鼠與巢 鼠為火災正傾向種.2000公尺處唯一有 傾向表現的高山白腹鼠為負傾向.2800公尺海拔處未 火災地小型哺乳類 歧異度較火災跡地為大,2000公尺則火災跡地有較大的歧異度.生物量以 2800公尺火災跡地較未火災地為大,2000公尺則以未火災地較火災地為大. 族群結構中成熟 未成熟個體比例,居留過境個體比也受火災影響,但性別 比例則無明顯變化. 經主成份分 析出倒木,植物豐富度,枯立木,枯枝落 葉層,喬木,地形,樹冠鬱蔽與地表鬱蔽等8類主 要微棲地成份,進行小型 哺乳類物種間微棲地利用,選擇與偏好上的區隔判斷.微棲地利用 的區隔 反應在普遍種與稀有種對微棲地選擇性的兩極化現象上,區隔表現視海拔 不同以較 低海拔處有較明顯之區隔,而火災會減少微棲地的區隔程度.物 種的火災傾向反應被認為是 較高海拔地區微棲地區隔狀況不明顯的可能 原因.物種對微棲地因子選擇偏好均隨視為棲 巨觀棲地不同而改變.對微 棲地選擇性低的森鼠,依微棲地提供量的多少決定使用狀況,被 地的普遍 使用者.黑腹絨鼠在未火災地對喬木與枯立木正選擇,火災地則改為喬木與 枯枝落 葉層.而高山白腹鼠則慣以大型植物結構體有關因子最為偏好.
As most research in fire ecology in Taiwain has emhasixed it effect on pl ants and solls, this research is to understand the species composition, popula tion demography of small mammals in burned vs. unburnded area.Fire affects sm all mammals directly by killing them, and indirectly by influencing emigration patterns. The influence of elevation on the natural distribution of small ma mmalsis also discussed. Population demography and species composition were determined via mark-recapture in the Tatachia area of Yushan National park fro m June 1995 to May1996. There were four grids, two (burned and un burnded) at 2800m in elevation and two (burned and un burnded) at 2000m in elevation. Twe nty four habitat characterisics were measured at each captured site fore analy sis of microhabitat segregation. Seven species of small mammals were traped : Apodemus semotus, Eothenomys melanogaster, Microtus Kikuchii, Micromys minu tus, Niviventer culturatus, Soriculus fumidus and Anouurosorex squamipes. In t he 2880m elevation area, A.semotus, E. melanogaster and A. squamipes were not found in the burned study grids, but M. kikuchii, M. minutus and S. fumidus we re found in the postfire habitat. At 2000m N. culturayus is found only in unbr und habitat. Fire chang diversity, biomass, ratio of mature and immature indiv iduals, and ratio of transient and resient individuals, but does not effect th e sexual ratios of individual species. At 2880m, diversity and ratios of adult to juveniles was greaer at 2000m. Biomass war greater at burnded site at 2880 m rev自sed at unburnded site at 2000m. Treefalls, plant species richness, s tanding dead trees, leaf litter, tree species, topography, canopy cover and g round cover are the eight dominant components as determined by Principal Compo nent Analysis. Microhabitat segregation is significant at high elevation, resu lting from differential habitat selectivity between common species which are g eneralist and rate species which show high selectivity. One way ANOVA tests of the influence offire on micrihabitat segregation are significant (p>0.05) onl y at high elevations. Microhabitat segregation by small mammals may be due to body size and selection for burned habitat. Select pattern and preference between species are different ineach of the four grids. A. semotus is a habita t gengeralist and with E. melanogaster is correlated with tree and dead tree i n burned area, tree and leaf litter in burned areas, and N. culturatus always selects large plant structures. |
