Wind and Worms: Renewable energy is much easier for most people to embrace when it doesn't require change. That's become a particular problem when it comes to Canadians and wind energy.
Activists now decry windmills with a fervour once reserved for nuclear plants. To some, it seems strange to waste time railing against a power source that does not generate greenhouse gases, is relatively quick to construct and can serve as a powerful symbol of a community's environmental convictions. They say critics are only displaying a modern strain of "Not In My Backyard" syndrome.
Opponents, however, say they are driven by concerns about windmills' effects on everything from bird migration to health to property values to earthworms.
One gets the distinct impression that the environmental concerns are mostly being tossed in as obstacles. Bats are a much bigger concern than birds in most locations. And earthworms--in Canada--after what the Ice Age did?
Pleistocene ice sheets wiped out any native earthworms that may have lived in Canada, leaving North American species, in the family Megascolecidae, only in areas where glaciation was incomplete, such as Vancouver Island and the Richardson Mountains of the Yukon. The twenty or so European species that now live in Canada, in the family Lumbricidae, are thought to have come in the rootstocks of plants imported by settlers or in soil used for ballast in ships. Native North American worms have spread only a little north of the southern limits of glaciation, but the European species have spread widely and rapidly, recently aided by the commercial sale of earthworms for fishing bait.
For instance, none of the nineteen species of earthworms found in Ontario are native there and just two of them are native to North America. And while the above paragraph focuses on European exotics, Canada also has African night crawlers, various Asian earthworms, etc. Considering that robins, moles, the Butler's garter snake, various turtles, etc. subsist predominantly on earthworms in Ontario nowadays, what did they eat before?
Maybe that's a downside to wind turbines possibly harming those invasive earthworms. Or maybe wiping out the exotic earthworms could allow other species to recover. But that would obviously be rather difficult.
Green Vibrators: This article on battling wind turbines in Scotland helps explain why a few folks are worrying about their impact below ground.
Windfarms could destroy bugs and worms that are the basis of the food chain, according to scientists and environmental experts.
They are fearful of a potentially catastrophic gap in knowledge about the industry’s possible effects on the Highland landscape.
One academic has urged the Scottish Government to order a moratorium on onshore windfarms to allow a scientific study to establish whether or not turbine vibration and sub-sonic noise threatens some our tiniest and rarest creatures.
...
John Etherington, a retired reader of ecology at the University of Wales in Cardiff and specialist in environmental science, argued that highly decayed peat can “liquefy” through vibration.
He said: “I am sure vibration might cause liquefaction. In other circumstances it might cause degassing of occluded ‘air’ or methane in peat or compaction of wet mineral soils. All of these would influence organisms.
Etherington is sure it might cause liquefaction?
His concerns could be valid...and the same thought applies to the vibrations from busy highways and airports, industrial facilities, some types of construction, on and on. There's been little research into the topic. However, it's not like there aren't already wind farms operating on and near the soils Etherington mentions...it shouldn't be that hard to gather some relevant data.
Wind farms generate a variety of noises, including low frequencies that can be felt but not heard. Manufacturers have been working to reduce them. For instance...
Many of the earlier types of wind turbine had the rotor placed behind the tower. It was regularly observed that they caused high levels of infrasound and low frequency sound, and neighbours out to quite large distances blamed them for severe annoyance. Present day wind turbines almost exclusively have their rotor in front of the tower.
Some folks claim that these vibrations cause health problems--part of wind turbine syndrome. One of the things they point out is that the term wind farm is deceptive...they're large-scale industrial facilities and need to be treated as such. Hard to argue with that. But, getting back to the exotic earthworms...
Unnatural Decomposition: We're constantly told that earthworms are beneficial species. Yet, that's a viewpoint which is dependent upon one's land use preferences--like farming and gardening. Few of the plants we garden and almost none of the crops we grow come from regions without earthworms. We consider their presence normal and good just about everywhere. But again, they're not native to large swaths of North America...and for instance the Hawaiian Islands. So what happens when earthworms invade such areas? Well, with hardwood forests...
After earthworm invasion, nutrients previously in the forest floor are relocated to the A horizon [top soil] and more rapidly converted to forms that plants can take up (mineralization). The earthworm casts in the new A horizon don't have more nutrients than the forest floor did (since it came from the forest floor, it couldn't) but as the litter passes through the earthworm gut, it gets broken up and colonized by fungi and bacteria. So, more of the nutrients from the litter are converted to forms that plants can easily absorb through their roots. Although the total amount of a given nutrient does not increase, earthworms can increase the proportion of total nutrients made available to plants at any given time. That’s why you so often hear how earthworms increase soil fertility, because they turn more of the nutrients present in a site into a form that plants can take up. In agricultural ecosystems, crop plants are well adapted to take up nutrients rapidly so earthworms often lead to increased plant growth.
Forest plants tend to feed heavily in the spring, but less so the rest of the year. The interlopers don't adjust their schedules to better suit the forests.
After earthworms invade a hardwood forests, the rate of decomposition and nutrient release is faster than the rate of uptake by plants and some of these nutrients are lost through the process of leaching. The end result is that both nitrogen and phosphorous availability decreases in hardwood forests after earthworm invasion. Native plants of hardwood forests are not as well adapted to take up large amounts of nutrients throughout the growing season and when nutrients are in forms that plants can absorb, they are also easily leached through the soil with water. Two things increase the likelihood of nutrient leaching. First, there are not enough plants or root systems to absorb the amount of nutrients available. Second, with all of those earthworm burrows, water can wash the dissolved nutrients down through the soil, below the plant roots or out into adjacent wetlands, rivers and streams. Nutrients that would have been cycled within the hardwood forest ecosystem can either be lost underground or transferred out to another system.
And it's not just the current generation of forest residents that are adversely impacted.
Because the forest floor is made up of loose, organic material such as leaf litter, many of the seeds are protected from predation by small mammals and birds. Also, because the forest floor is moist and full of nutrients, the seeds have a perfect place to germinate. The forest floor and the protection it provides is especially important for some herbaceous plants because their seeds germinate slowly, taking two or more years to develop into a small plant. If not protected from predators, drying out or freezing over a long period of time, the seeds would have no chance of growing into a mature plant.
That's sure a different way of thinning a forest.
Consequences: During an investigation of the increasing scarcity of goblin ferns...
A study by researchers at the University of Minnesota has found dramatic losses of native understory plant species and tree seedlings as exotic Lumbricids invade Sugar Maple/Basswood stands in the Chippewa National Forest of northern Minnesota. Without Earthworms, decomposition of the annual leaf litter in hardwood forests is controlled by fungi and bacteria. Decomposition is slower than accumulation of new litter, resulting in a thick, spongy “duff” on the forest floor. In the first two years of this study, the front of invading Earthworms moved about 10 metres into the forest. The earthworms ate the organic layer out from under the plants and tree seedlings, replacing the duff with a much denser layer of black earthworm castings. The worm-invaded areas lost a dozen species of spring-flowering forest floor herbs, and Sugar Maple seedling densities dropped from over 100 per square metre to almost none.
These changes don’t seem to reverse with time. Earthworm dominated forests don’t support perennial spring-blooming herbs like Bellworts (Uvularia), Trillium, Yellow Violets (Viola pubescens) or Wild Ginger (Asarum canadense), but fast-growing exotics such as Garlic Mustard (Allaria petiolaris) can often dominate a worm-churned site.
As sugar maples die there, they're not being replaced, slowly allowing a new type of forest to develop. By the way, the night crawlers in question consume basswood leaves first, then sugar maple, and finally oak...which happens to mirror the nutrition they have to offer. Hardwood forests generally support more earthworms than do conifers. FYI, earthworms can even change the palatability of plants to herbivores.
Switching to Alberta...
In the aspen and pine forests of Alberta, Canada, where the European earthworm Dendrobaena octaedra was accidentally introduced, the influence of this earthworm on the forest floor was dramatic in terms of microbial characteristics, changes in the community of other invertebrates, changes in nutrient cycling, and even effects on soil horizonation. Further, introduced European earthworms play an important role in litter decomposition in aspen forests in the Rocky Mountains of Colorado, USA.
There are a number of studies documenting that exotic earthworms change the soils in aspen forests, often in ways that aren't good for the trees. Yet, earthworms are rarely mentioned when speculating as to why aspens in many locations are in decline.
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