Use of ecoacoustics to determine biodiversity patterns across ecological gradients

Abstract

The variety of local animal sounds characterizes a landscape. We used ecoacoustics to noninvasively assess the species richness of various biotopes typical of an ecofriendly forest plantation with diverse ecological gradients and both nonnative and indigenous vegetation. The reference area was an adjacent large World Heritage Site protected area (PA). All sites were in a global biodiversity hotspot. Our results showed how taxa segregated into various biotopes. We identified 65 singing species, including birds, frogs, crickets, and katydids. Large, natural, protected grassland sites in the PA had the highest mean acoustic diversity (14.1 species/site). Areas covered in nonnative timber or grass species were devoid of acoustic species. Sites grazed by native and domestic megaherbivores were fairly rich (5.1) in acoustic species but none were unique to this habitat type, where acoustic diversity was greater than in intensively managed grassland sites (0.04). Natural vegetation patches inside the plantation mosaic supported high mean acoustic diversity (indigenous forests 7.6, grasslands 8.0, wetlands 9.1), which increased as plant heterogeneity and patch size increased. Indigenous forest patches within the plantation mosaic contained a highly characteristic acoustic species assemblage, emphasizing their complementary contribution to local biodiversity. Overall, acoustic signals determined spatial biodiversity patterns and can be a useful tool for guiding conservation.

The sound of restored soil: Measuring soil biodiversity in a forest restoration chronosequence with ecoacoustics

“…Future studies should pair sampling in time across plots, particularly when degraded and restored plots are within relatively close proximity to each other. Alternatively, mean acoustic diversity might increase as patch size increases, and more complex vegetation is associated with higher diversity (Grant et al 2016). Therefore, it is possible that the minimum habitat patch size in our study was not sufficient to influence acoustic source variability in the treatment groups.…”

Quantifying the impacts of an invasive weed on habitat quality and prey availability for tiger snakes (Notechis scutatus) in urban wetlands

“…This habitat type is a monoculture of dense grass, and structurally very different from the open native vegetation equivalent which is comprised of several structurally diverse plant species and interspersed with bare ground. This is unsurprising, as invasive grass monocultures usually result in a loss of abundance and diversity of native birds (Catling 2005, Skórka et al 2010), reptiles (Valentine et al 2007, Hacking et al 2014), frogs (Grant and Samways. 2016, Falaschi et al 2020) and rodents (Sammon and Wilkins.…”

Adapting the Dragonfly Biotic Index to a katydid (Tettigoniidae) rapid assessment technique: case study of a biodiversity hotspot, the Cape Floristic Region, South Africa

“…Although cryptic and difficult to locate, katydids are perhaps best known for the species-specific songs produced by mature adult males (Bailey and Rentz 1990). There has been considerable research into monitoring and tracking of katydid species, as well as other acoustically communicating insects, through acoustic monitoring (Riede 1993, 1998, Diwakar et al 2007a, Grant and Samways 2016. Acoustic monitoring can be conducted using a variety of techniques, ranging from simple listening exercises (Diwakar et al 2007b) to complex microphone arrays (Stevenson et al 2015).…”

“…Most notably, mature male katydids produce characteristic speciesspecific songs enabling non-invasive species detection in an environment by listening alone (Bailey and Rentz 1990). Combined, these characteristics make katydids an attractive taxon upon which an acoustic rapid assessment method could be based for assessing the quality of terrestrial habitats in South Africa (Grant and Samways 2016).…”