Abstract：
Understanding patterns of species diversity is crucial for ecological research and conservation, and this understanding may be improved by studying patterns in the two components of species diversity, species richness and evenness of abundance of species. Variation in species richness and evenness has previously been linked to variation in total abundance of communities as well as productivity gradients. Exploring both components of species diversity is essential because these components could be unrelated or driven by different mechanisms. The aim of this study was to investigate the relationship between species richness and evenness in European bird communities along an extensive latitudinal gradient. We examined their relationships with latitude and Net Primary Productivity, which determines energy and matter availability for heterotrophs, as well as their responses to territory densities (i.e. the number of territories per area) and community biomass (i.e. the bird biomass per area). We applied a multivariate Poisson log-normal distribution to unique long-term, high-quality time-series data, allowing us to estimate species richness of the community as well as the variance of this distribution, which acts as an inverse measure of evenness. Evenness in the distribution of abundance of species in the community was independent of species richness. Species richness increased with increasing community biomass, as well as with increasing density. Since both measures of abundance were explained by NPP, species richness was partially explained by energy-diversity theory (i.e. the more energy, the more species sustained by the ecosystem). However, species richness did not increase linearly with NPP but rather showed a unimodal relationship. Evenness was not explained either by productivity nor by any of the aspects of community abundance. This study highlights the importance of considering both richness and evenness to gain a better understanding of variation in species diversity. We encourage the study of both components of species diversity in future studies, as well as use of simulation studies to verify observed patterns between richness and evenness.
摘要：
了解物种多样性的模式对于生态研究和保护至关重要，这种理解可以通过研究物种多样性的两个组成部分的模式来改善，物种丰富度和物种丰富度的均匀度。以前，物种丰富度和均匀度的变化与群落总丰度和生产力梯度的变化有关。探索物种多样性的两个组成部分是必不可少的，因为这些组成部分可能是不相关的或由不同的机制驱动的。这项研究的目的是调查欧洲鸟类群落中物种丰富度与均匀度之间的关系。我们研究了它们与纬度和净初级生产力的关系，决定了异养生物的能量和物质可用性，以及它们对领土密度（即每个区域的领土数量）和群落生物量（即每个区域的鸟类生物量）的响应。我们将多元泊松对数正态分布应用于唯一的长期，高质量的时间序列数据，允许我们估计群落的物种丰富度以及这种分布的方差，它作为均匀度的逆度量。群落中物种丰度分布的均匀度与物种丰富度无关。物种丰富度随着群落生物量的增加而增加，以及随着密度的增加。由于这两种丰度测量都是由NPP解释的，物种丰富度部分由能量多样性理论解释(即能量越多，生态系统维持的物种越多)。然而,物种丰富度没有随NPP线性增加，而是表现出单峰关系。均匀性既不能用生产力来解释，也不能用社区丰富的任何方面来解释。这项研究强调了考虑丰富度和均匀度以更好地了解物种多样性变化的重要性。我们鼓励在未来的研究中研究物种多样性的两个组成部分，以及使用模拟研究来验证观察到的丰富度和均匀度之间的模式。
