Friday, March 7, 2014

#54 Trophic Cascades and Wolves

Here is a very eye-opening story about a relatively new discovery in research on ecological systems.

Scientists used to believe that conservation efforts to restore ecosystems must follow the pattern of evolution. In other words, you had to start at the bottom in the lowest “trophic” levels. The term, “trophic”, refers to different levels of the food chain, for example plants, insects, etc.

A “cascade” is like a stream falling down a waterfall and breaking into more and more streams with each rock it splinters against.

The concept of “trophic cascade” describes when a large carnivore at the top of the food chain has a cascading effect down to all the lower levels and it spreads out in many, many directions and has many diverse, even unexpected impacts.

The most stunning example to date comes from Yellowstone National Park in Wyoming. There had been no wolves in the park for 70 years until they were re-introduced in 1995 to 1996. If you have 4½ minutes to watch this video, I think you will be astounded:  How Wolves Change Rivers. [1]

Synopsis of the video: Wolves kill some species of animals for sure, but we now know they give life to many others. Elk populations had built up until by grazing they reduced much of the vegetation to almost nothing. Wolves killed some of the elk and it radically changed the behavior of the elk and they avoided certain parts of the park where wolves could kill them easily, especially the valleys and gorges. Vegetation in those areas started to regenerate immediately. [3] The heights of some of the trees multiplied 5 times. In just 6 years aspen, willow, and cottonwoods came back. [4] Birds then started moving in. Songbirds and migratory birds moved in. Beavers started to increase because of the young trees. [5] Beavers built dams in the rivers and provided habitats for otters and muskrats, ducks and fish, reptiles and amphibians. When the wolves killed coyotes, the number of rabbits and mice increased. Then came the hawks, weasels, and foxes to eat those prey. Also badgers, ravens, and bald eagles came to feed on the carcasses left by the wolves and other available small prey. Bears came back too. Bears also killed some of the elk and reinforced the impact of the wolves. Even more amazingly, the wolves changed the behavior of the rivers. Because of the new vegetation, the rivers meandered less. The river banks had been stabilized and collapsed less often. The channels were straighter and became deeper. There was less soil erosion. Pools formed for all the wildlife to drink from.

“Since wild wolves have returned to Yellowstone, the elk and deer are stronger, the aspens and willows are healthier and the grasses taller.  For example, when wolves chase elk during the hunt, the elk are forced to run faster and farther.  As the elk run, their hooves aerate the soil, allowing more grasses to grow.  Since the elk cannot remain stationary for too long, aspens and willows in one area are not heavily grazed, and therefore can fully recover between migrations.  As with the rest of the country, coyote populations were nearly out of control in Yellowstone before the wolves returned.  Now, the coyotes have been out-competed and essentially reduced by 80 percent in areas occupied by wolves.  The coyotes that do remain are more skittish and wary.  With fewer coyotes hunting small rodents, raptors like the eagle and osprey have more prey and are making a comeback.  The endangered grizzly bears successfully steal wolf kills more often than not, thus having more food to feed their cubs.   In essence, we have learned that by starting recovery at the top with predators like wolves, the whole system benefits.  A wild wolf population actually makes for a stronger, healthier and more balanced ecosystem.” [2]

The ecosystems we are seeing are definitely not “survival of the fittest” or a “dog eat dog” world. Even the prey of the wolves, the elk population, was not harmed. As a whole they were hardier and more disease free. [6]

All of the species benefitted: the plants and trees, the insects and birds, small, medium, and large animals, even the fish and amphibians. [7] Even the rivers and streams benefitted.

Scientists following evolutionist models got it wrong. All aspects of nature fit together harmoniously.

Just as I explained about how the intricacies of the First Living Cell [8] had to have been designed, we can see this interconnectedness and co-dependency of all creatures at higher levels of nature and conclude it must have been designed as well. Chance and blind mechanisms could not create such complexity, especially not in such a top-down cascade model.

The wolves in Yellowstone are a marvelous example of an intricate ecological system that is impossible to conceive happened randomly or even by Natural Selection. (See my post on how the mechanism of Natural Selection loses variability not gains it. [9]). When something is designed by intelligence, the final goal is known and all the building block steps support the end goal. In this case, the wolf at the top of the mountain of the trophic cascade was already conceived of before all the other creatures ascending up the food chain were put in place. Otherwise the benefits cascading down would not exist.

But scientists are discovering more and more trophic cascades all the time. [10] Every time a new one is discovered it reinforces the evidence for a designer by new orders of magnitude. It is exponentially more difficult to create two trophic cascades than one.

“When we try to pick out anything by itself, we find it hitched to everything else in the Universe.” – John Muir

There must be God.

[1]  How Wolves Change Rivers.

[2]  A Wolf's Role in the Ecosystem - The Trophic Cascade.

By altering elk browsing patterns, wolves have enabled riparian vegetation to regenerate for the first time in decades, creating habitat for beavers, songbirds, fish, amphibians, and a host of small mammals.  Additionally, wolves have improved the herd health of prey species by selecting young, old, diseased, or physically-impaired animals.

[4]  Wikipedia: Trophic Cascade.
Examples of this phenomenon include:
A 2-3 fold increase in deciduous woody vegetation cover, mostly of willow, in the Soda Butte Creek area between 1995 and 1999. Heights of the tallest willows in the Gallatin River valley increasing from 75 cm to 200 cm between 1998 and 2002. Heights of the tallest willows in the Blacktail Creek area increased from less than 50 cm to more than 250 cm between 1997 and 2003. Additionally, canopy cover over streams increased significantly, from only 5% to a range of 14-73%. In the northern range, tall deciduous woody vegetation cover increased by 170% between 1991 and 2006.

[5]   Wikipedia: Trophic Cascade.
Importantly, the number of beaver (Castor canadensis) colonies in the Park has increased from one in 1996 to twelve in 2009. The recovery is likely due to the increase in willow availability, as they have been feeding almost exclusively on it. As keystone species, the resurgence of beaver is a critical event for the region. The presence of beavers has been shown to positively impact streambank erosion, sediment retention, water tables, nutrient cycling, and both the diversity and abundance of plant and animal life among riparian communities.

The return of the wolf has changed elk behavior and reduced some herds, but overall numbers remain strong in Idaho, Montana and Wyoming. According to Yellowstone biologist Doug Smith, the Yellowstone herds remain healthy despite its smaller size. The number is more in line with historic levels since wolves were reintroduced and grizzly bears and mountain lions returned naturally. Overall elk populations in the states of Idaho, Montana, and Wyoming remain healthy. However, elk populations are now more dynamic with the return of large carnivores and elk distribution has shifted to areas of refuge which make them more difficult to hunt.  Elk populations are affected by many variables including weather, disease, predation, and human mortality.

[7]  Wolves: Good News for Yellowstone Wolves.
Wolves are critical to the overall health of the Greater Yellowstone Ecosystem as a keystone species, restoring ecological balance. Most notably wolves improve the health of their prey through selecting weak, old, diseased and injured animals. Wolves also change the habits of prey such as elk by reducing their numbers and changing distribution. These changes have contributed to a rebirth in the growth of cottonwood, willow, aspen and shrubs, subsequently benefiting grizzly bears, pronghorn, beaver, cutthroat trout, songbirds, scavengers and small mammals.

[8]  Proof for God #41 The First Living Cell.

[9]  Proof for God #35 Natural Selection.

[10] Wikipedia: Trophic Cascade.
One example of the cascade effect caused by the loss of a top predator has to do with sea otters.

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