This will not be a very scientific post because it will be based on folklore as well as some ‘intuitions’.
Whenever I read about the trophic cascades, I imagine the change in pace that the large predators bring about.
Their prey moves about in smaller herds, faster (not leaving for as long in one place).
It seems just like a change in rhythm that we experience, for example, when our boss is around or when we have guests that are staying over for several days (including working days) or when our parents/grandparents come to visit etc.
Everyone pricks up their ears and picks up their pace.
While this obviously results in altered use of habitats, lower browsing levels and perhaps reduced trampling (a result of smaller herds which do not forage for as long in one place but tend to move on and to also move more quietly – supposedly, treading more softly), I cannot help but form an association with some folk songs of my people (Latvians).
In our winter solstice rites, mummery is a customary element.
Mummers are usually dressed in costumes of animals (bear, crane etc.) or spirits (death etc.) and they arrive with great noise and ruckus and they leave with great noise and ruckus.
Everyone is supposed to feast ‘as hard as they can’ and then to use this energy in song and dance (giving their power to the nature for the Sun and growth to return).
While many of the activities occur indoors (dancing, games, riddles, mocking songs), there is an aspect that is pertinent with the outdoors.
First of all, children are urged to run and greet the mummers (or the Winter Solstice) with their feet bare.
Secondly, it is mentioned that the mummers and other folk who engage in the mummer-provoked activities, should stomp their feet very hard on the ground in order to awaken the plants (cereal crops).
It is almost though that the stomping and the dancing and the touching of the ground with warm, nimble feet, and the tapping at the earth with mummer staffs would entice the gradual awakening of vegetation under soil or under snow and it would send some beneficial reverberations down in the soil to stimulate (the roots?) and to encourage prosperous, lush growth in the following season (spring, summer).
This association that I formed made me wonder about the impact of vibrations on the soil (e.g., soil fauna) and the plants (e.g., plant roots).
It is known that some vibrations (especially, heavy pressure) are bad for plants.
There are degrees of disturbance where some tearing at the ground with hooves or paws and claws is beneficial as it aerates the soil, creates barren spots or microspots for seeds to germinate or for less dominant plants to have a better chance, disseminates plant propagules etc.
Meanwhile, heavy disturbance (intensive trampling or heavy machinery) can depauperate the soil by turning plants into dust, releasing soil carbon and other nutrients that can form gaseous compounds, disrupting the beneficial activities of soil fauna (earthworms, beetles), damaging roots or rhizomes (in a non-propagating manner) etc.
Thus, the degree of disturbance matters and slight disturbance (stomping, trampling) might improve certain soil and vegetation processes.
For example, I suppose that large predators deintensify the disturbance caused by large predators in their trampling activities which could translate into healthier soil and improved plant growth.
However, I cannot help and wonder if the increased pace also is beneficial through the vibrations it creates.
With large predators around, herbivores can no longer gather in one spot.
They have to move around, often move around quickly and possibly visiting more types of habitats (optimal and also suboptimal ones due to the redistribution of their activity and avoidance of both herbivore- and predator-favoured sites such as riparian areas).
Also, social predators (such as wolves) themselves cause slight disturbances through playing, otherwise interacting socially, bedding, scent-marking etc.
It seems to me that, with large predators around, there are more of the softer vibrations.
This makes me wonder if, indeed, there is a benefit to vibrations such as has been claimed by the Latvian people in their mummer and winter solstice songs.
Some studies have been dedicated to research vibrations (sound effects) on plants but mostly I have encountered information regarding aboveground biomass.
It is still relevant, of course, because when the earth vibrates, the vibrations affect the aboveground biomass and belowground biomass equally.
It would be interesting to learn if the change in type and intensity of vibrations caused by impacts of large predators on their prey could result in stimuli that are beneficial for plant grown and soil organisms (soil processes).
Perhaps large predators are somewhat like the mummers that invite the local housefolk (large herbivores) to dance around at a certain pace that is proven stirring and invigorating for the land.
I will attempt to follow studies that discuss effects of vibrations on soil fauna, soil aggregate (substrate) and vegetation.
I simply wished to write down this association that I made.
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This review by Jung, J. et al., 2018 discusses the scientific developments regarding sound wave impacts on plant growth and performance.
Mainly, it has been found that some types of sound waves and their respective vibrations can benefit (trigger) plant immunity and improve performance under extreme (drought) conditions as well as benefit growth.
This is thought to happen on a cellular level through hormonal pathways.
The review does not offer information that would significantly contribute to the statements I made above.
However, it provides some evidence that vibrations have certain beneficial (or harmful) effects on plants.
It also made me wonder if plants have different responses to certain natural sounds (e.g., it was mentioned that pea roots can ‘hear’ (react to) underground water flows growing toward the water resource).
It would be interesting to observe plant reactions to sounds of rain, large herbivores (e.g., vocalizations and trampling patterns), beneficial insects, pest insects and perhaps even large predators (the presence of which imply immediate safety from herbivory).
Notes by Ieva 