Study shows people perceive biodiversity

A new study published in People and Nature finds that both sight and sound influence perception of biodiversity, and participants were slightly more accurate when assessing forest biodiversity through sound alone than through sight alone. This interdisciplinary research, led by scientists from the German Centre for Integrative Biodiversity Research (iDiv), the Friedrich Schiller University Jena, the Helmholtz Centre for Environmental Research – UFZ, and Leipzig University, brings together methods from environmental psychology and forest and soundscape ecology. 

In a lab-based sorting study, two groups of 48 participants examined either photographs or assessed audio recordings taken from forests with different levels of biodiversity. The participants then categorised the images or sounds based on the amount of diversity they perceived in the pictures and recordings. 

The researchers found that perception of visual diversity was predominantly linked to colour, vegetation density, lighting, and forest structure. Acoustic diversity was linked to birdsong, volume, and seasonal cues, such as the spring choruses of birds. 

The findings build on a previous study by some of the authors involved exploring forest biodiversity - mental health linkages, in which the researchers showed that perceived biodiversity, rather than actual tree species richness, was associated with short-term mental health and well-being outcomes. 

Tuning into biodiversity

In both experiments, the participants’ perceived levels of biodiversity were closely aligned with the actual biodiversity. This suggests that people can recognise variations in species richness and forest structure, especially when provided with other pictures or snippets of audio as reference points. The researchers also found that participants were slightly better at assessing acoustic diversity than visual diversity, likely because the audio recordings contained fewer confounding elements than the forest images. 

“Participants were able to perceive differences in forest biodiversity as they compared and sorted either photographs or audio recordings,” explains Kevin Rozario, co-lead author of the study. “Our results suggest that forest biodiversity perceived through the eyes probably depends on variations in forest density and structure, light conditions and colours, while for the acoustic sense people recognized how melodic the birdsongs were, while also physical properties such as perceived loudness and perceived seasonal characteristics of the recordings mattered.”

This knowledge could inform designing and planning environments that both support species richness and make that richness perceptible to people. For example, these findings suggest that effective conservation and urban greening efforts should also consider how biodiversity is experienced through multiple senses. Incorporating habitat elements that foster more diverse bird calls or visually varied vegetation could enhance public connection to nature and support broader conservation goals. 

“As cities grow and natural spaces evolve, designing urban environments rich in both visual and acoustic biodiversity could enhance human connections to nature, supporting both conservation and well-being”, adds last author Prof Dr Aletta Bonn, head of the Biodiversity and People research group at UFZ, iDiv and the Friedrich Schiller University Jena.

While the study highlights meaningful insights into how people perceive biodiversity, the researchers acknowledge key limitations — including that further studies with broader demographic representation would help strengthen and refine these early findings.