Topographic complexity is the most important factor influencing the acoustic cues of birds in the rainforest

Ecoacoustics is an interdisciplinary science that studies soundscapes and their association with the environment at different temporal and spatial scales. Despite the challenges of data processing (e.g. automated species identification), soundscape monitoring is now recognized as a cost-effective way to measure biodiversity and assess the state of ecosystems in the face of environmental change. However, how biophony (biologically produced sounds) varies with vegetation characteristics and topography remains largely unknown.

In a study published in Ecological Indicators, researchers from the Chinese Academy of Sciences’ Xishuangbanna Tropical Botanical Garden (XTBG) investigated the relationship between birds’ acoustic cues and various environmental factors, including vegetation and topographic features, in a network of southwestern tropical forest dynamics plots. China.

Using stand-alone loggers, the researchers recorded a dynamic rainforest patch network consisting of 22 patches in Xishuangbanna. They assessed the relative importance of tree species richness, six vegetation features, and three topographic features for five acoustic signal complexity indices and three statistical indices that describe properties of the frequency spectrum, at spatial scales. 25m and 50m.

They found that topographic complexity was the most important factor influencing acoustic cues. Horizontal vegetation characteristics, including tree density and basal area, were also important variables related to acoustic cues.

Additionally, they found that the Acoustic Diversity Index (ADI) and Bioacoustic Index (BIO) were not associated with vegetation or topographic features at either spatial scale. Acoustic entropy (H), centroid (CENT) and asymmetry (SKEW) and topographic complexity remained a stable relationship.

“Our results indicate the importance of topographic complexity for acoustic cues. We suggest that topographical complexity should be taken into account in future ecoacoustic studies in other ecosystems,” said HE Xuelian of XTBG.

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Sharon D. Cole