陽明山國家公園鋪面步道遊憩衝擊及其衝擊管理有效性研究

Abstract

公園管理者為求提供高品質遊憩環境並確保自然資源免受過度衝擊，會將步道鋪上石材、碎石與其它材料等。然而，目前的步道衝擊研究，很少比較步道鋪面設施如何有效的減緩步道衝擊。本研究目的是在探討步道鋪面管理能達到降低步道環境惡化的有效性，並選擇陽明山國家公園遊憩步道作實證研究。本研究將探討三項課題：(1)步道鋪面成效是否符合原先建構的目的；(2)比較不同的鋪面材料對降低步道環境惡化的有效性；以及(3)影響鋪面管理有效性的原因。 本研究提出步道鋪面有效性指數(Surfacing Effectiveness Index, SEI)，SEI數值範圍為0~100%，計算步道鋪面能達到降低環境衝擊範圍的有效程度，以作為評估鋪面步道管理有效的方法。並探討影響鋪面有效性的相關變因，再以統計分析的方法去瞭解各影響因子之間的關係。研究方法採用20公尺距離之間隔抽樣 (distance-based sampling )，調查步道共16公里長。本研究整合步道「鋪面有效性指數(SEI)」與環境因子(地形與植群)、步道設計因子(鋪面寬度與材質)及使用因子(遊客量)等三方面的影響變數，統計分析SEI與其影響因子的關係。 由研究結果顯示，第一、陽明山國家公園鋪面步道的衝擊問題，主要以步道土壤裸露加寬與步道土壤沖蝕最為嚴重，尤其是步道土壤裸露問題上，木框碎石步道的平均土壤裸露寬度最大，而石階與木框碎石階步道產生的步道沖蝕深度最為明顯。步道分生的問題發生在石板步道最多，而樹根裸露的問題最多則發生在石階步道。碎石步道的SEI比石板步道高。第二、根據逐步迴歸分析結果，影響鋪面管理成效的主要因子是坡向夾角與腹地寬度，坡向夾角與SEI為正相關，步道的腹地寬度與SEI為負相關。第三、植群差異也會影響步道衝擊管理的成效，石板步道與石階步道在草地環境的SEI較好。第四、遊客量較多的步道，有較多的鋪面類型，最多用到四種鋪面類型。第五、經二因子變異數分析結果顯示，較低使用量的步道，鋪面材質與鋪面寬度對SEI有顯著差異的環境條件，是在步道坡度低且步道兩側平緩之處；而較高使用量的步道，則是在步道坡度高且步道兩側陡峭之處。在上述兩種條件之處，也就是步道設計可以發揮之處。本研究為在有限的人力和物力下，在短期內所作出之成果與提出SEI之應用，整體尚有不足之處，但本研究之部分成果仍有助於東亞或台灣國家公園管理單位在進行步道維護或鋪面更新時的決定參考。

Trails and recreational activities occurring on them have negative effects on soil and vegetation resources in national parks. Surfacing of trail treads using rocks, gravels, and other materials is a common solution which park managers use to control resource degradation on and around trails. However, there is a paucity of research on the environmental impacts resulting from different types of trail surfacing and on the effectiveness of trail surfacing in minimizing trail degradation. Using surfaced hiking trails at Yangmingshan National Park in northern Taiwan as examples, this study investigates the influence of environmental, design and use factors on the effectiveness of trail surfacing in reducing recreational impact. Three specific objectives are: 1) to determine the extent to which trail surfacing serves its intended purpose, 2) to compare different surfacing options in term of their effectiveness in limiting trail degradation, and 3) to identify factors that are important in explaining the variation in trail surfacing effectiveness. We adopted an after-the-fact approach to investigate the trail conditions, taking samples at every 20m on eight trails with a total length of 16km. We developed and applied a Surfacing Effectiveness Index (SEI) and associated it with environmental (topography and vegetation), trail design (surface width and materials) and use-related factors using multivariate statistical techniques. Results show that the main forms of recreation impact on trails of Yangmingshan National Park are widening and erosion around surfaced trail treads. In terms of tread widening, the average bare soil width beyond the surfaced treads is the higher in wooden frame turnpike. On the other hand, trails surfaced with rock steps and wooden frame steps exhibited higher levels of erosion. Multiple treads on rock-slab trails and root exposure on rock steps are more evident than other surfacing types. Surfacing with gravels appears to be more effective in controlling bare soil width than surfacing with rock slabs. Results of stepwise multiple regression reveal that slope alignment angle and expansion potential along trail corridors have a significant relationship with trail surfacing effectiveness as indicated by SEI, with the alignment angle showing a positive influence on surfacing effectiveness and expansion potential showing negative. Trails surfaced with rock slabs or rock steps appear to be more effective in minimizing trail impacts in open grassy areas than in forest areas. There are significant differences for each type of surfacing material and surfacing width in SEI through the use of Two-way ANOVAs. Less-used trails are characterized by their low slope and flat trail shoulders, while steeper slope and rough trail shoulders are common attributes on heavily-used trails. Despite the study limitations, this empirical research illustrates the utility of examining trail surfacing effectiveness and the application of SEI. The research findings can inform future decisions in trail surfacing and maintenance in high-use protected areas in Taiwan and East Asia.