澎湖群岛海岸防风林植物群落生态调查

Vegetation survey of coastal windbreaks in Pescadores, Taiwan

澎湖群岛建造海岸防风林已有百年历史 ,惟澎湖造林难以成功 ,主要因自然条件不佳 ,季节风导致林木易受盐雾为害 ,台风破坏与人为干扰 ,为防风林碎裂化的主要原因。澎湖现有的防风林 ,林龄近 2 0年 ,部分因干扰严重 ,已失去防风林应有功能。为改善海岸防风林更新及造林方式 ,在澎湖岛划设 2 1个调查样区 ,探讨成熟海岸防风林植物群落结构与外界干扰的影响 ,作为防风林更新规划的依据。植物群落调查 ,共记录 39科 80种植物 ,造林树种以木麻黄为主 ,部分防风林因银合欢入侵 ,与木麻黄混生 ,少部分为混合林。下层植物以银合欢与三角叶西番莲分布最广 ,约 3/ 4调查样区皆曾纪录。木麻黄虽为防风林带的优势种 ,但由于邻近土地利用不同 ,影响下层地被组成 ,相似度分析结果显示 ,样区间物种结构少部分相似性高 ,大部分结构差异大 ,相似度指数约 0～ 87,相似度最高的样区 ,位于林带宽度 5 0m以上的防风林内 ,由于外来干扰较少 ,物种结构较相似。

Pescadores is considered one of the most difficult areas to establish coastal windbreaks in Taiwan Region because of the critical weather condition. The main impact factors, including salty mist, typhoon, and human activities, result in the fragment of existing mature windbreaks. Twenty one sampling plots were established to examine the relationship between vegetation community structure and the disturbance of neighborhood. The improvement of forestation techniques and the ecological progress of windbreaks were also evaluated. Species richness of vegetation, the important value index of trees, and the cover-abundance of groundcovers were analyzed to evaluate the vegetation variation among stands. A total 39 families and 80 plant species were recorded. The main species of plantation was Casuarina equisetifolia and Leucaena leucocephala invaded into most plantations to form as a mixture forest. A quantified similarity coefficient, Motaya coefficient, was used to analyze the species composition among sampling plots. The results showed that the species composition in most windbreaks were quite different. The Motaya coefficients among the plots ranged from 0 to 87, which means the vegetation in some plots were totally different to others and in some plots near 90% of vegetation were the same. It is considered that species diversity of groundcovers among the plots was due to the variant landuse types of neighborhoods.