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首页> 外文期刊>Ecotropica >Abundance and vigor of three selected understory species along environmental gradients in south-eastern Brazil.
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Abundance and vigor of three selected understory species along environmental gradients in south-eastern Brazil.

机译：巴西东南部沿环境梯度选择的三种林下物种的丰度和活力。

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The majority of floristic and phytosociological studies conducted in the Atlantic Forest are focused on tree species and tree species communities, while only limited research is done on understory species, in particular concerning their interrelationship with environmental factors or their ecological requirements in terms of habitat change due to anthropogenic influences, such as complete and selective logging. In our study, the species abundance and vigor of three representative species of the Atlantic Forest in south-eastern Brazil (Gesneriaceae: Nematanthus crassifolius, Besleria melancholica; Acanthaceae: Stenostephanus lobeliaeformis) were measured in a riverine ecosystem that included different levels of past logging activities along environmental gradients such as altitude, exposure, inclination, and canopy openness. We measured the vigor of the species by counting the total number of shoots and estimating the rate of live shoots. To provide a comprehensive overview we developed a vigor index based on this data which might be useful for future studies on the response to environmental gradients of understory species in the tropics. The results show distinct relationships between various environmental factors and both species distribution patterns and vigor of the investigated species. N. crassifolius is strongly dependant on proximity to watercourses and open canopy conditions. Abundance of S. lobeliaeformis was limited to higher elevations, but according to our data individuals of this species are more vigorous at lower elevations of its distributional range. While being more vigorous with decreasing elevation, S. lobeliaeformis was completely absent at the lower end of the elevation gradient. The abrupt absence of this species at low elevations coincides with a complete forest clearance in the 1940s. S. lobeliaeformis was only found in the selectively logged forest. In contrast, changes in abiotic conditions have little effect on B. melancholica. We conclude that small-scale elevational and microclimatic gradients have differing consequences for the selected understory species. Those natural gradients are disturbed by a land-use gradient, and a scenario like this is typical of the Atlantic Rainforest at this elevation. Therefore a further understanding, especially of the largely undersampled understory plant community, is essential and a first approach in this direction is provided by this study.
机译：在大西洋森林中进行的大多数植物学和植物社会学研究都集中在树种和树种群落上，而对林下种只进行了有限的研究，特别是关于它们与环境因素的相互关系或因栖息地变化而引起的生态要求方面的研究。人为的影响，例如完整和选择性的伐木。在我们的研究中，巴西东南部的三种典型大西洋森林物种的物种丰富度和活力（Gesneriaceae： Nematanthus crassifolius ， Besleria melancholica ; Acanthaceae：在河流生态系统中测量了斑节线虫（Stenostephanus lobeliaeformis），该生态系统包括沿海拔，暴露，倾斜度和树冠开放度等环境梯度变化的过去伐木活动水平。我们通过计算芽的总数并估计活芽的比率来测量物种的活力。为了提供全面的概述，我们根据这些数据开发了一个活力指数，这可能对以后研究热带下层物种对环境梯度的响应可能有用。结果表明，各种环境因素与被调查物种的物种分布模式和活力之间存在明显的关系。 N。十字花科植物在很大程度上取决于靠近水道和开放的树冠条件。 S的丰度。小叶植物仅限于较高的海拔，但根据我们的数据，该物种的个体在其分布范围的较低海拔处更具活力。虽然随着海拔的降低而更加充满活力，但 S。在海拔梯度的下端完全没有叶状花序。该物种在低海拔地区突然消失，恰逢1940年代森林被彻底清除。 S。仅在选择性采伐的森林中发现了叶状花序。相反，非生物条件的变化对B几乎没有影响。忧郁症。我们得出的结论是，小范围的海拔和微气候梯度对选定的林下物种具有不同的后果。这些自然梯度受到土地利用梯度的干扰，这种情况是该海拔地区大西洋雨林的典型情况。因此，有必要进一步了解，尤其是对大部分被采样不足的林下植物群落的了解，本研究为此提供了第一个方法。

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