應用植群分析法評估坡地生態工程之植群復育效益-以新店二叭子植物園為例

Abstract

本研究為了解生態工法於坡地災害復建工程之成效，以植群調查分析為主，選定經邊坡穩定分析達安全標準之生態工法案例，針對坡地生態工程在營造適合植物生長環境的部分，進行深入探討，並評估當地植群演替狀態與找出影響植物生長之環境條件，給予加速植群演替使邊坡環境更加穩定之建議。 研究區域位於台北縣新店市『二叭子植物園』內，於2004年6月間，因連日豪雨致使坑溝發生崩塌。因考量崩塌區位處植物園區內，為能恢復原有植被，採用坡地生態工程進行整治。本研究一共設置了36個樣區，分散於坡地生態工程復育林（14個樣區）及周遭天然林（22個樣區），並調查12種環境因子。經過雙向指標種分析、降趨對應分析以及矩陣群團分析，並配合植群組成，結果顯示本區復育林與天然林之研究區域內植物種類豐富，且大致可判斷研究區域內以水同木-江某為優勢種。此說明工程後復育林已和周遭天然林林相相似，當地的植群已呈現自然演替的狀態，且下邊坡復育程度優於上邊坡。整體復育林中之植物分布的主要受海拔、水分與坡位影響，建議日後在工程施工方面，應較注意上邊坡之工程強度。

To evaluate the effects of ecological engineering applied to the slopeland after restoration due to natural hazards, in this study, a site on a slopeland, stably reconstructed by using ecological engineering was selected to investigate the rehabilitation ability of natural environment by means of the method of vegetation analysis. In addition, the succession condition of local vegetation were also assessed to find out the environment conditions affecting the growth of vegetation, so that these findings may be used for accelerating vegetation succession and stabilizing the slopelands. The selected site was the Er-pa-zi Park, located in Xindion, Taipei county, Taiwan. The site was damaged by a heavy rainfall in June, 2004, and consequently mass movement occurred. Since the mass movement area was in the park, slopeland ecological engineering methods were implemented to reconstruct, so that the original vegetation and environment may be restored. In this study, thirty-six plots were set up and distributed in the site. Among the plots, fourteen were in the area rehabilitated by ecological engineering and twenty-two in the area of the adjacent natural forest. For all plots, twelve environmental factors were surveyed. After the analyses of the Two-Way Indicator Species Analysis （TWINSPAN）, Detrended Correspondence Analysis （DCA）, Matrix Cluster Analysis （MCA） and floristic composition, the results showed that the site had a high level of diversity and the Ficus fistulosa - Schefflera octophylla was identified as the primary vegetation type. It could be stated that after rehabilitation, the restored forest was similar to the adjacent natural forest, indicating that local vegetation was under spontaneous succession. Plant species distribution in the site was mainly affected by altitude, moisture and topography. The results also showed that restoration was more successful on the lower parts of the slope; accordingly it is suggested that more improvements are needed on the upper slopes.