Structure, function and floristic relationships of plant communities in stressful habitats marginal to the Brazilian Atlantic rainforest.
Structure, function and floristic relationships of plant communities in stressful habitats marginal to the Brazilian Atlantic rainforest.
复制标题
巴西大西洋雨林边缘压力栖息地植物群落的结构、功能和区系关系。
作者：
F. Scarano
巴西大西洋雨林由山坡上的典型热带雨林组成，因其物种丰富度高和物种特有性高而成为生物多样性热点。这片森林与物种多样性较低的植物群落接壤，主要是由于比梅西奇雨林更极端的环境条件。在山坡和大海之间，沿海平原有沼泽森林，干燥的半落叶林和海洋沙沉积物上的开阔灌木丛植被。在另一个极端，在山顶（海拔2000米以上），雨林被高海拔的田野和岩石露头上的开阔灌木丛植被所取代。因此，雨林边缘的植物群落要么遭受洪水，干旱，海洋或寒冷的冬季温度。结果发现，植物之间的积极相互作用在结构和功能的沼泽森林，沿海桑迪植被和寒冷，高海拔植被在里约热内卢州的重要作用。此外，似乎只有少数物种发挥这种积极作用，因此这些整个系统的运作可能依赖于它们。奇怪的是，这些保育植物通常是热带雨林中的附生植物，在研究地点通常是陆生的。许多人表现出景天科酸代谢。保护计划必须将大西洋沿岸的植被视为一个复合体，而不仅仅是一个雨林。
The Brazilian Atlantic rainforest consists of a typical tropical rainforest on mountain slopes, and stands out as a biodiversity hotspot for its high species richness and high level of species endemism. This forest is bordered by plant communities with lower species diversity, due mostly to more extreme environmental conditions than those found in the mesic rainforest. Between the mountain slopes and the sea, the coastal plains have swamp forests, dry semi-deciduous forests and open thicket vegetation on marine sand deposits. At the other extreme, on top of the mountains (>2000 m a.s.l.), the rainforest is substituted by high altitude fields and open thicket vegetation on rocky outcrops. Thus, the plant communities that are marginal to the rainforest are subjected either to flooding, drought, oceanicity or cold winter temperatures. It was found that positive interactions among plants play an important role in the structuring and functioning of a swamp forest, a coastal sandy vegetation and a cold, high altitude vegetation in the state of Rio de Janeiro. Moreover, only a few species seem to adopt this positive role and, therefore, the functioning of these entire systems may rely on them. Curiously, these nurse plants are often epiphytes in the rainforest, and at the study sites are typically terrestrial. Many exhibit crassulacean acid metabolism. Conservation initiatives must treat the Atlantic coastal vegetation as a complex rather than a rainforest alone.