本研究係以惠蓀林場紅檜人工林與闊葉樹次生林之監測調查資料，建構八類物種 知食物網模式，藉此探討以Shannon指數為基礎，結合種內歧異度、種間歧異度 與結構歧異度知生態歧異度的求解方法。於1998年4月至1999年1月期間所調 查知結構歧異度中，各樣區概以1998年7月最高，顯示夏季之生物相最為豐富； 而比較四個樣區之結構歧異度中，又以入侵較多闊葉樹脂紅檜人工林的樣區最具 生物多樣性。各樣區之總種間歧異度的差異，導因於各物種的消長，特別是食蟲 目與腐食性動物，以及肉食性、草食性與腐食性昆蟲於不同季節的明顯變動，然 此等動物之遷移、死亡或生長機制，仍有待深入探討。另比較各樣區之總種內歧 異度，以闊葉樹次生林樣區最高，顯示闊葉樹次生林之各樹種直徑及較具多樣性， 而因紅檜人工林之林齡近似，故其總種內歧異度較低。由結構、總種間與總種內 歧異度累加所得之生態系歧異度，發現各樣區概以夏季最高，而比較四個樣區之 差異，以闊葉樹次生林與入侵較多闊葉樹之紅檜人工林的樣區之生態系歧異度較 高，顯示夏季之生物相最具多樣性，且具不銅樹種與徑級分配之林分能孕育較為 豐富的生物。

　　　　　We constructed a food-web model of eight niche categories to explore the application of ecosystem diversity index based on the summation of Shannon indices of inter-species, intra-species, and structure diversity. The model is based on the practical monitoring data collected in the Taiwan red cypress plantation and a secondary broadleaf forest at Hue-Sun Forest Station in Central Taiwan. The highest structure diversity occurs in the summer for all sampling plots, and the red cypress plantation with the most number of invaded broadleaf trees has the highest structure diversity. The variation of total inter-species diversity among plots is high, possibly due to the seasonal variation of species in several niche categories, especially insectivorous mammals, detritvores, carnvorous insects, and phytophagous insects. The uniformity of tree diameter is the main reason of composite intra-species diversity in the secondary forest plot is higher than any plots of the redcypress. In term of ecosystem diversity, all plots in summer are higher than in other seasons; the secondary forest plot and red cypress plot with the most broadleaf invasion also are higher in ecosystem diversity.