影響安全島行道樹景觀美質之因素研究

Factors Affecting Landscape Esthetics of Street Trees on Median Strip

本研究主要目的在於評估不同行道樹種之景觀美質，以供行道樹選擇之參考。本研究應用心理物理模式測定受測者對行道樹之偏好，利用從台北市街道拍攝之72張幻燈片，請五組受測者進行評估，其中包括一組專業人員（水土保持班學員）、四組學生。受測者針對幻燈片依其偏好程度給予評值，再將其轉換成景觀美質評值（SBEs, scenic beauty estimation value）,最後應用迴歸分析法分析偏好與各種行道樹屬性間之關係。重要結果如下（I）較受偏好的行道樹是臺灣欒樹、樟樹、垂柳｀菩提樹、茄茗；較不受偏好的是榕樹、白千層。（2）可利用幻燈片評估民眾對行道樹之偏好，雖然各受測組之原始景觀評值間具顯著差異，惟將其轉換成SBEs後，各組間之SBEs呈高度正相關。顯示景觀美質評估法（scenic beauty estimation method）能有效消除受測者評估尺度之差異。（3）學生組與專業者之SBEs高度正相關，顯示過去許多研究利用學生進行景觀評估，足以其結果代表一般市民之偏好。（4）迴歸分析結果顯示解釋能力介於0.692與0.863之間，影響民眾對行道樹景觀偏好之因素及影響程度會因受測者特性而略有不同。整體而言，影響民眾對行道樹景觀偏好之主要因素包括樹冠面積、栽植列數、是否開花、樹型、及枝葉密度。樹冠面積愈大、栽植列數愈多，民眾越偏好。

The purpose of this study is to measure the landscape esthetics of different species of street trees to serve as one criterion for street tree selection. The psychophysical model is applied to measure respondents'preferences for street trees. Seventy-two color slides of street tree taken from Taipei city were presented to five groups of respondents including one professional group and four student groups. Those respondents were asked to rate their preference for every slide. These ratings were transformed into scenic beauty estimates (SBEs) by RMRA TE. Multiple regression analyses were applied to analyze the relationships between preferences and various street tree attributes Some important findings of this study are summarized as follows: (I) The most preferred species of street trees are Koe/reuteria henryi Dumm., Cinnamomum camphora(Linn.) Sieb., Salix babylonica Linn., Ficus religiosa Linn., Bischoffia javanica Linn .. The least preferred species are Ficus血crocarpa L. f. and Melaleuca leucadendra (L.) Linn .. (2) The slides are a reliable medium for measuring public preference for street trees. Although the results show that there are significant differences among respondent groups when comparing the preference ratings given by them, the SBEs of those pictures measured are positively and highly correlated. It suggests that the criterion difference among respondents can effectively be adjusted to the same rating scale by the Scenic Beauty Estimation method. (3) The revealed high correlation among SBEs of student groups and professional group justifies previous approach to measure students'landscape preferences as public preferences. (4) The explanatory capabilities of those regression models are between 0.692 and 0.863. The street tree attributes that affects public preference are area of crown measured from picture, planting rows, tree flowering, tree form, and leaf density of tree. The more crown area in the picture and planting rows the more it is preferred. The influences of these attributes on preference, however, are different for different respondent groups.