Different slopes of a mountain can determine the structure of ferns and lycophytes communities in a tropical forest of Brazil

A community of Ferns and Lycophytes was investigated by comparing the occurrence of species on different slopes of a paleoisland in Southeastern Brazil. Our goal was to evaluate the hypothesis that slopes with different geographic orientations determine a differentiation of Atlantic Forest ferns and lycophytes community. We recorded these plants at slopes turned towards the continent and at slopes turned towards the open sea. Analysis consisted of a preliminary assessment on fern beta diversity, a Non Metric Multidimensional Scaling (NMDS) and a Student t-test to confirm if sites sampling units ordination was different at each axis. We further used the Pearson coefficient to relate fern species to the differentiation pattern and again Student's t-test to determine if richness, plant cover and abundance varied between the two sites. There was a relatively low number of shared species between the two sites and ferns and lycophytes community variation was confirmed. Some species were detected as indicators of the community variation but we were unable to detect richness, plant cover or abundance differences. Despite the evidence of this variation between the slopes, further works are needed to evaluate which processes are contributing to determine this pattern.本研究针对巴西东南部一座古岛的不同坡向区域开展蕨类与石松类植物群落调查，通过对比不同坡向上的物种出现情况展开分析。本研究旨在验证如下假说：不同地理朝向的坡向会驱动大西洋森林内蕨类与石松类植物群落产生分化。我们分别在朝向大陆的坡向与朝向外海的坡向上记录了此类植物的分布情况。分析方法包括：首先对蕨类植物的β多样性进行初步评估；采用非度量多维标度法（Non Metric Multidimensional Scaling，NMDS）与学生t检验，以验证各轴上的样地采样单元排序是否存在差异。随后，我们利用皮尔逊相关系数（Pearson coefficient）分析蕨类物种与群落分化模式之间的关联，并再次采用学生t检验，以验证两个样地间的物种丰富度、植被盖度及个体多度是否存在差异。两个样地间的共有物种数量相对较少，蕨类与石松类植物群落的分化得到了验证。部分物种被鉴定为群落分化的指示物种，但我们未检测到物种丰富度、植被盖度及个体多度方面的组间差异。尽管本研究证实了不同坡向间的群落分化现象，但仍需开展后续研究以明确驱动该分化格局的具体生态过程。