本研究探討南仁山山區相思樹人工林於演替序列上多樣性之發展，利用時空互代法進行取樣，共調查16個0.05ha相思樹人工林樣區與4個0.05ha天然林樣區，相思樹人工林林齡為28年生至60年生。共記錄106科230屬340種維管束植物。將155種木本植物之斷面積和，使用雙向指標種分析與降趨對應分析將樣區切分為演替早期，演替中期及天然林共三個階段。依木本植物於演替序列上分布，區分為先驅種群、演替早期種群、演替中期種群、早期恢復之天然林種群與後期恢復之天然林種群共五個生態種群。相思樹人工林之α多樣性為天然林>演替早期階段>演替中期階段。且各演替階段中不同冠層物種α多樣性之發展趨勢不同，喬木層α多樣性之發展趨勢為天然林>演替中期階段>演替早期階段，灌木層與草本層α多樣性於各演替階段間并無顯著差異。各相思樹人工林之物種組成不同，演替序列之β多樣性，29年生、55年生之相思樹人工林β多樣性達高峰，顯示相思樹人工林之物種組成經過轉換後，其物種組成才趨近於天然林。經由林齡-β多樣性指數直線回歸式，推算出相思樹人工林需經約177年之演替，物種組成即可趨近恢復至天然林。

We studied trends of species diversity along the sere of Acacia confusa plantations of Nanjenshan area. Using the method of time-space mutual substitution, sixteen 0.05ha plots of 28-60 year A. confusa plantations and four 0.05ha plots in natural forests were sampled. A total of 340 vascular plant species in 230 genera and 106 families were recorded. Applying Two Way Indicator Species Analysis (TWINSPAN) and Detrended Correspondence Analysis (DCA) on the basal areas of 155 woody plants, three successional phases were classified: early phase of secondary forest, intermediate phase of secondary forest, and natural forest phase. Based on their distribution along the sere, the 155 woody plants were classified into five ecological species groups: pioneering species, early successional secondary species, late successional secondary species, early recovering natural forest species, and late recovering natural forest species. Alpha diversity was highest in natural forest phase and lowest in intermediate phase of secondary forest. Alpha diversity of tree layer was highest in natural forest phase and, in contrary, lowest in early phase of secondary forest. Alpha diversity of shrub layer did not show significant difference among phases. Beta diversity was highest in 29-year and 55-year A. confusa plantation. Our results revealed that A. confusa plantations need high turnover of species and approximately 177 years to have species composition near natural forest.