ABSTRACT Composition and richness of coastal vegetation differs with distance from the water and sheltering by topography. Transition from pioneer beach plants to mature forests is expected to be narrow on low wave energy coasts with a tropical climate favorable to vegetation growth. The goal of this paper is to determine whether vegetation on the beach and foredune will be denser and have a greater number of species and more woody shrubs near the water as wave and wind stresses diminish because of favorable shoreline orientation within a pocket beach. Field data on beach width, beach mobility, dune height, vegetation species, vegetation height and percent vegetation cover were collected in Puerto Rico along six cross-shore transects. Beaches are more stable at transects in the lee of an eolianite barrier and a tombolo. The vegetation gradient there is compressed, with denser, taller, more diverse vegetation and more tree species close to the waterline than at more exposed sites. The lack of mobility of the beaches and dunes and lack of geomorphically significant disturbance events is in contrast to the conspicuous feedbacks between overwash, topography, and vegetation on exposed mid-latitude coasts, revealing the need for more study of low-energy beach environments.

中文翻译：

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热带口袋海滩上植被特征与海岸线位置的差异

摘要 沿海植被的组成和丰富度因距水面的距离和地形的遮蔽而异。在低波能海岸，热带气候有利于植被生长，从先锋海滩植物到成熟森林的过渡预计会很窄。本文的目标是确定海滩和前滩上的植被是否会随着波浪和风应力的减小而变得更加密集，并且在水边拥有更多的物种和更多的木本灌木，因为口袋海滩内的海岸线方向有利。在波多黎各沿六个跨岸横断面收集了有关海滩宽度、海滩流动性、沙丘高度、植被种类、植被高度和植被覆盖百分比的实地数据。海滩在风吹石屏障和连片岩背风处的横断面更稳定。那里的植被梯度被压缩，与更多暴露的地点相比，靠近水线的植被更密集、更高、更多样化和更多的树种。海滩和沙丘缺乏流动性，缺乏地貌上显着的扰动事件，与暴露的中纬度海岸上的淹没、地形和植被之间的显着反馈形成鲜明对比，这表明需要对低能量海滩环境进行更多研究。