北臺灣公園喬木現況適應性分析與應用

遮陰、乾旱、高溫、強風等氣候變遷，以及人為移植與管理引起之問題，是近年都市裡樹木遭遇到難以抵抗的生長逆境，這些逆境直接衝擊樹木的生育，往往引起生理障礙，除影響景觀效果外，且損害樹木健康甚或是危及大眾生命安全與財產。有鑒於此，本研究首先由14本綠化相關書籍中挑選茄苳等68種公園常用喬木樹種，針對其耐陰性、耐旱性、抗風性、生長適溫及移植存活率等五種生長特性之描述，加以量化整理成為評分標準，採評分後予以加權平均與±1/2標準差之方式，分別得出68種樹種五種生長特性分級表與綜合耐受性分級表。屬耐陰性高者樹種如厚皮香、山菜豆、蒲葵、榕樹、羅漢松、福木及瓊崖海棠。耐旱性高樹種如榔榆、水黃皮、福木、香楠、臺灣赤楠、欖仁、黃槿、棋盤腳、洋紅風鈴木及黃金風鈴木等均屬之。抗風性高喬木例如櫸樹、苦楝、黃連木、羅漢松等。高溫環境則可選擇大葉桃花心木、大花紫薇、鳳凰木、火焰木、木棉、藍花楹、洋紅風鈴木、黃金風鈴木、玉蘭花、阿勃勒等。移植存活率高者樹種有茄苳、九芎、阿勃勒、楓香、榕樹等。依循適地適種的設計選用原則可大幅降低維管成本與獲得較優質的景觀效果。為此提供一套因地制宜、可作為依環境需求適應性不同的篩選樹種之參考。其次，於臺北市的美術公園及青年公園中，擇臺灣欒樹等7種喬木共79株樣本，調查溫度、相對溼度、相對照度、換算樹冠濃密度、風速等氣象因子，及土壤pH值、電導度(Electrical Conductivity；EC)、土壤硬度、土壤含水量(volumetric water contents,VWC)、田間容水量(field capacity, FC)等土壤因子，以及外觀品質分級、葉綠素計讀值(chlorophyll meter reading；CMR)、常態化差異植生指數(normalized difference vegetation index；NDVI）等植株因子。經相關性作一次迴歸分析來進行分析探討，得知各項測定因子與外觀品質之相關性。結果顯示， FC較低時(臺灣欒樹若介於30.8%-38.8%間、阿勃勒為35.6%-40.2%間、樟樹為37.1%-42.1%之間)，樹木呈現較佳的外觀品質，顯示土壤排水不良，可會對樹木生長造成不良影響。樟樹土壤硬度較鬆軟介於 15-23 mm間時，有較佳外觀品質(4-5分)。在EC值部分，阿勃勒、茄苳與小葉南洋杉呈現無相關，顯示這三樹種其外觀品質高低似不受EC影響，適應性高。小葉欖仁、樟樹與苦楝均呈現正相關性，分別在EC≧172µs∙cm-1、≧133µs∙cm-1及≧154.8µs∙cm-1時，外觀品質分級才較佳可達4-5分，顯示應可對小葉欖仁、樟樹與苦楝適當補充肥份以助樹木生長並增進外觀品質。又在土壤硬度方面，樟樹的土壤硬度較夯實在20-27 mm之間時，樹木外觀品質不佳(2-3分)；若土壤較鬆軟15-23 mm間，則有較佳外觀品質(4-5分)。樟樹則建議於種植前須先將生育地周遭土壤掘鬆，或先行添加適當資材以改善其土壤硬度，並避免選擇種植於經常受踐踏處。在喬木外觀品質量化指標之評估部分，多數樹種的樹冠濃密度值、NDVI測值與CMR測值皆與主觀判定的外觀品質分級呈正相關，顯示樹冠濃密度值、NDVI及CMR測值確可作為喬木品質標準判定之量化指標，以利篩選良窳。

關鍵字

耐陰性；耐旱性；抗風性；移植存活率；外觀品質分級；常態化差異植生指數；葉綠素計讀值

並列摘要

Environmental conditions such as shading, drought, high temperature, gale, occurred by climate changes or human management, are harsh growth challenges that urban trees face in recent years. These adverse conditions have direct impact on plant development, and often cause physiological stress on plant; more over, they would affect adversely on landscape beauty, be harmful for tree health or even for human lives and property. For the reasons above, two trials were conducted in this study. In the first trial, 68 kinds of arborous trees species such as Bischofia javanica Blume were selected from 14 green books, and five growth characteristics of them such as shade tolerance, drought tolerance, wind resistance, optimum temperature, and transplant survival rate were quantified, graded and reorganized from the descriptions in the books. After grading, the weighted average score and ± 1⁄2 standard deviations were used to obtain the five growth characteristics grading table and integrated tolerance grading table of 68 tree species. Providing a convenience retrieval for quick search of tree species in different environments. High shade tolerance trees include Ternstroemia gymnanthera (Wight & Arn.) Sprague, Radermachia sinica (Hance) Hemsl., Livistona chinensis R. Br. var. subglobosa (Mart.) Becc., Ficus microcarpa L. f., Podocarpus macrophyllus (Thunb.) Sweet , Garcinia subelliptica Merr. and Calophyllum inophyllum L. etc. They are suitable for middle and lower layer planting or even indoor green planting. High drought tolerance trees include Ulmus parvifolia Jacq., Pongamia pinnata (L.) Pierre, Garcinia subelliptica Merr., Machilus zuihoensis Hayata, Syzygium formosanum (Hayata) Mori, Terminalia catappa L., Hibiscus tiliaceus L., Barringtonia asiatica (L.) Kurz, Tabebuia pentaphylla (L.) Hemsl.and Tabebuia chrysantha ( Jacq.) G. Nicholson etc. Follow right plant in the right place principle of design, it can significantly reduce the cost of maintenance and obtain better quality landscape effects. It can provide a set of convenient and fast search criteria that can be adapted to local conditions and can be used as screening trees according to different environmental needs. In the second trial, 7 kinds of trees species such as Koelreuteria formosana Hayata, a total of 79 trees were investigated in the Fine Arts Park and the Youth Park. Survey items include environmental factors such as temperature, relative humidity, full illuminance, illuminance under canopy, wind speed etc; and soil factors such as soil pH, EC value, soil hardness, volumetric water contents (VWC); and field capacity (FC), appearance quality grade, chlorophyll meter reading (CMR), normalized difference value (NDVI)… etc. Correlation of soil hardness, VWC, FC, soil EC value and appearance quality grade were linear regression analyzed. For example, if appearance quality grade of trees were graded for 4 to 5 points, and FC was between 30.8% and 38.8% of Koelreuteria formosana Hayata, between 35.6% and 40.2% of Cassia fistula L., between 37.1% and 42.1% of Cinnamomum camphora (L.) J. Presl. The results indicates that when park's soil was temporarily stagnant after the rain, in most of the time, it did not adversely affect the growth of the trees but used as the function of conserving moisture and slowing runoff. If appearance quality grade of trees was graded for 4 to 5 points, and soil hardness was 15-23 mm of Cinnamomum camphora (L.) J. Presl. For another planting recommending example, the soil hardness of Cinnamomum camphora (L.) J. Presl was negatively correlated with its appearance quality grade, therefore, it is recommended that the soil should be excavated before planting, or appropriate materials should be added to the soil beforehand to improve the soil hardness and avoid stamping. In the aspect of the quantitative evaluation of appearance quality in trees, showed that crown density, NDVI and CMR values of nearly seven species were positively correlated with the appearance quality. Indicating that crown density, NDVI and CMR could be used as quantitative indexes for determining trees growing quality.

並列關鍵字

shade tolerance ； drought tolerance ； wind resistance ； transplant survival rate ； chlorophyll meter reading (CMR) ； normalized difference value indexindex (NDVI)