Biology Reference
In-Depth Information
Chapter 8
Sonic Patterns III: Sounds and Vibrations
from Soils
Soil is a medium rich in acoustic information. Most of the sounds present in the soil
are originated by stridulating animals or are the result of the digging activity of
fossorial organisms. The acoustic information from soil is an important tool to
monitor soil biodiversity in a nondestructive way.
In some reptiles vibrations produced by prey are used for hunting. Vegetation
vibration has been proved to orient fossorial moles toward vegetation clumps rich in
insect food. Soil percussion is also a common mechanism used by elephants to
communicate at great distances.
In insects and arthropods, vibrations are used extensively to communicate or to
escape predators. Well documented is the case of
Diplocardia mississippiensis
,an
earthworm that emerges from the soil after a produced vibration in the soil using a
“grunting device.” This behavior is explained as a strategy utilized by the worms to
escape hunting by moles.
It is disputed if ants have hearing systems or body vibrational sensing, but their
capacity to react to soil vibrations is surprisingly rapid. Substrate-borne vibrations
are used extensively by animals to locate mates, prey, and predators, as in the well-
documented case of antlion larvae.
Despite the scarcity of studies, soil monitoring appears to be a promising field of
research. Sound prospecting of the soil requires that standard microphones be
integrated with piezoelectric microphones, geophones, and accelerometers to cap-
ture airborne and soilborne vibrations.
8.1
Introduction
Soil is the main receptor of chemical pollutants and is a medium exposed to
continuous dramatic anthropogenic-borne modifications of its internal structure
such as logging, plowing, reclamation, and covering with impervious surfaces of
cement and asphalt. Urban sprawl and the associated logistics and transportation
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