life's forms modify the Earth: wolves vs. beavers (Introduction)

by David Turell @, Tuesday, November 14, 2023, 16:29 (159 days ago) @ David Turell

A study in a Minnesota forest:

Predators can directly and indirectly alter the foraging behaviour of prey through direct predation and the risk of predation, and in doing so, initiate indirect effects that influence myriad species and ecological processes. We describe how wolves indirectly alter the trajectory of forests by constraining the distance that beavers, a central place forager and prolific ecosystem engineer, forage from water. Specifically, we demonstrate that wolves wait in ambush and kill beavers on longer feeding trails than would be expected based on the spatio-temporal availability of beavers. This pattern is driven by temporal dynamics of beaver foraging: beavers make more foraging trips and spend more time on land per trip on longer feeding trails that extend farther from water. As a result, beavers are more vulnerable on longer feeding trails than shorter ones. Wolf predation appears to be a selective evolutionary pressure propelled by consumptive and non-consumptive mechanisms that constrain the distance from water beavers forage, which in turn limits the area of forest around wetlands, lakes and rivers beavers alter through foraging. Thus, wolves appear intricately linked to boreal forest dynamics by shaping beaver foraging behaviour, a form of natural disturbance that alters the successional and ecological states of forests.


"Herein, we describe and demonstrate how wolf predation is a selective pressure that shapes the foraging behaviour of beavers via consumptive and non-consumptive mechanisms in the Greater Voyageurs Ecosystem (GVE), Minnesota. By altering beaver foraging behaviour, wolves invariably alter the ecological trajectory of forests around wetlands and beaver-occupied water sources (e.g. lakes, rivers).


"Beavers are important seasonal prey for wolves in the GVE with beaver constituting up to 42% of wolf pack diets from April to October (the ice-free season) when beavers are vulnerable to predation


"Beaver foraging creates ecological heterogeneity and increases biodiversity around wetlands by increasing forest complexity—particularly by creating ‘messy forests’ with substantial dead and standing wood. This in turn affects nutrient deposition and carbon storage, composition of lichen, bryophyte and plant communities, and habitat for, and abundance of, invertebrates, birds and mammals around beaver-altered environments. Consequently, wolves, by reducing the amount of forest beavers can disturb, alter all of these ecological processes as well."

Comment: as usual the forest ecosystem is highly organized as the last paragraph indicates. No organism is an island unto itself. While each human exists in a local ecosystem, viewed as a whole, the human population lives in a whole Earth ecosystem totally under our control. When viewing the process of evolution as a purposeful development, it is obvious God wished to create the current state of affairs. The end point of evolution is humans and the whole of Earth food supply.

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