Data for: Investigating the Effects of Tree Species Diversity and Relative Density on Bird Species Richness with Acoustic Indices

Mixed-species forest stands may provide suitable habitats for a greater number of bird species than tree monocultures by increasing the number of niches and resources available. However, assessing the effects of forest diversity on birds over time and across multiple sites using traditional survey methods can be expensive, time-consuming and impractical.
We used passive acoustic monitoring (PAM) and acoustic indices to investigate how tree species diversity, relative density, and other plot characteristics affect the species richness of avian communities in temperate forests. Acoustic surveys were conducted in the Hainich National Park, Germany, using plots which differed in tree species diversity and relative species density.
Of the five acoustic indices assessed, the normalised difference soundscape index (NDSI), the acoustic complexity index (ACI) and bioacoustic index (BI) performed best in separating biophony from other soundscape elements whereas the acoustic evenness index (AEI) and temporal entropy (Ht) were biased towards geophony, anthrophony and silence. NDSI, ACI and BI displayed significant positive relationships with bird species richness but NDSI plateaued at 5 bird species.
Plot tree species diversity had significant positive effects on ACI and BI during dawn, dusk and daytime periods. Increased basal area of sycamore (Acer pseudoplatanus) and, to a lesser degree, beech (Fagus sylvatica), had a negative effect on acoustic indices. These results could potentially be due to the earlier leaf out timings of these tree species in relation to the dates when surveys were performed. While the use of PAM and acoustic indices enabled surveys across multiple sites over longer time periods than would previously have been achievable, our results show that care should be taken when selecting the indices and interpreting acoustic index results.

Article data: This folder contains data files associated with the published article and appendices. Excel files contain ACI and BI values that were calculated for the individual audio files recorded in each plot that were used in analyses. Median values for each time period are also included.
Audio files provided were used to assess acoustic index bias towards soundscape elements other than bird vocalizations, relationships between acoustic index values and bird species richness (Appendix B), and the effect that distance between source and receiver had on acoustic index values (Appendix C).

混交林群落可能为更多鸟类物种提供适宜的栖息地，相较于单一树种栽培，其优势在于增加了可利用的生态位和资源。然而，利用传统调查方法对森林多样性随时间以及在不同地点对鸟类的影响进行评估，往往成本高昂、耗时费力且不切实际。本研究采用被动声学监测（PAM）和声学指数，探讨了树种多样性、相对密度以及其他样地特征如何影响温带森林中鸟类群落的物种丰富度。声学调查在德国哈尼希国家公园进行，选取的样地树种多样性和相对密度存在差异。在评估的五种声学指数中，标准化差异声景指数（NDSI）、声学复杂性指数（ACI）和生物声学指数（BI）在区分生物声音与其他声景元素方面表现最佳，而声学均匀度指数（AEI）和时间熵（Ht）则偏向于地球物理声音、人类声音和寂静。NDSI、ACI和BI与鸟类物种丰富度显示出显著的积极相关性，但NDSI在5种鸟类物种时达到平台期。样地树种多样性在黎明、黄昏和白天时段对ACI和BI有显著的积极影响。山毛榉（Acer pseudoplatanus）基面积的增加以及程度较低的栎树（Fagus sylvatica）基面积的增加对声学指数产生了负面影响。这些结果可能归因于这些树种在调查进行日期之前的早期叶出时间。尽管PAM和声学指数的使用使得在更长时间跨度和多个地点的调查研究成为可能，但我们的结果表明，在选择指数和解读声学指数结果时应谨慎行事。文章数据：本文件夹包含与已发表文章及附录相关的数据文件。Excel文件包含为每个样地中用于分析的独立音频文件计算的ACI和BI值，以及每个时间段的中值。提供的音频文件被用于评估声学指数对除鸟类鸣叫之外声景元素的偏差，声学指数值与鸟类物种丰富度之间的关系（附录B），以及源与接收器之间距离对声学指数值的影响（附录C）。