雲林沿海地區農地造林樹種之研究

A study on afforestation tree species in the farmlands of Yunlin coastal areas

平地造林主要實施目標為一般農業區內的農牧用地，以較不具競爭力之農地作為造林地，其中尤以沿海地區屬低生產力土地，從事作物生產往往失敗，致農民經營意願低落，須靠政府補助以營基本生活。然農地造林木生長期間長，每年遭強風、鹽霧、鹽分、乾燥及貧瘠等逆境侵襲，因此造林工作更為不易。針對雲林沿海地區2011年申請之農地造林地進行調查，結果顯示濱海鄉鎮的麥寮、臺西、四湖及東勢之土壤屬低鹽度，但其中臺西及四湖已近中鹽度的程度。水林及口湖之土壤則屬高鹽度農地，且兩個地區都屬發生地層下陷且積水嚴重之鄉鎮。透過9項林木健康狀態，經因素分析後建立3個森林健康度指標，分為樹冠及葉部活力指標、病蟲危害指標及林木開花結實指標。2011年新植造林樹種生長情形結果以欖李、茄苳、相思樹、大葉桃花心木、蘭嶼羅漢松、落羽松、木麻黃、臺灣櫸、水黃皮、白千層、小葉南洋杉、樟樹等樹種生長表現較佳，樣區健康等級均屬健康；生長狀況最差為臺灣肖楠及烏心石。整體而言，臺灣肖楠及烏心石建議不宜在濱海地區推廣。

The main targets of implementation on plain afforestation are agricultural and husbandry lands. However, the less competiveness in agricultural lands. Hence, farmers are not willing to work in this area and would rather live off government subsidies. Besides, with the long rotation period, and adversities caused by strong winds, salt spray, salt, dryness and barrenness of the land, it is harder to put afforestation in coastal area into practice. This study present the results of the investigation of agricultural afforestation in Yunlin coastal areas in 2011. Among the sites investigated, low salinity was found in sites of Mailiao, Taihsi, shihu, and Dongshin, with Taihsi and shihu almost reached middle salinity; high salinity was found in Shueilin and Kouhu, both of which have gone through land subsidence and serious hydrops. Using factor analysis, we analyzed nine tree health parameters, and established three forest health indexes, crown and leaf vitality index, disease and insects’ index, and flowering and fruiting index, for evaluating the health condition of afforestation trees. In the newly planted afforestation tree species in 2011, the indexes showed Lumnitzera racemosa, Bischofia javanica, Acacia confusa, Swietenia macropnylla, Podocarpus costalis, Taxodium distichum, Casuarina equisetifolia, Zelkova serrata, Millettia oraria, Melaleuca leucadendra, Araucaria excels, Cinnamomum camphora as healthy, whereas Calocedrus formosana and Michelia compressa were found to be the worst. Overall, C. formosana and M. compressa were not suggested to be planted in the coastal areas.