Invasive earthworms of North America

Invasive species of earthworms from the suborder Lumbricina have been expanding their range in North America. Earthworms are considered one of the most abundant macroinvertebrates in the soil of ecosystems in temperate and tropical climates. There are around 3,000 species known worldwide. They are considered keystone species in their native habitats of Asia and Europe because, as detritivores, they alter many different variables of their ecosystem. Their introduction to North America has had marked effects on the nutrient cycles and soil profiles in temperate forests. These earthworms increase the cycling and leaching of nutrients by breaking up decaying organic matter and spreading it into the soil. This thins out the soil rapidly because earthworms population can grow quickly since most earthworms have large broods, short time to sexual maturity, resilient cocoons, are hermaphrodites and a few such as Amynthas do not need mates through asexual reproduction called parthenogenesis. Since plants native to these northern forests are evolutionarily adapted to the presence of thick layers of decaying organic matter, the introduction of worms can lead to a loss of biodiversity as young plants face less nutrient-rich conditions. Some species of trees and other plants may be incapable of surviving such changes in available nutrients. This change in the plant diversity in turn affects other organisms and often leads to increased invasions of other exotic species as well as overall forest decline. They are considered one of the most invasive animals in the Midwestern United States along with feral swine.

Earthworms and range shifts

Earthworms are shifting their ranges northwards into forests between 45° and 69° latitude in North America that have lacked native earthworms since the last ice age. Among these, Lumbricus terrestris, L. rubellus, L. friendi, Amynthas agrestis, and Dendrobaena octaedra have been studied for their ability to invade previously uninhabited locations and disturb the local ecosystems and nutrient cycles. ==Influence on nutrient cycles and soil profiles==

Influence on nutrient cycles and soil profiles

When organisms die and plants undergo senescence, their detritus fall to the forest floor, where they begin decomposing into their constituent nutrients. In the absence of efficient detritivores such as earthworms, a thick layer of such organic matter accumulates. Most northern forests in North America lack native earthworms, which were largely wiped out when the ice sheets of the Wisconsin glaciation scoured much of the continent down to the bedrock. A deep detritus layer is thus characteristic of the native ecosystem of the region, and many native plants have evolved to rely on it. They often mix the nutrients into the soil, out of the reach of all but the deeper tree roots. Nutrients may then be leached and lost from the ecosystem entirely. Overall effects include a decrease in the thickness of the organic layer, increased mineralization, increased bulk density, spreading of the organic matter and humus, and increased rate of decomposition. ==Effects==

Effects

Invasive earthworms have caused a decrease in diversity, seedling populations, forest floor organic matter volume, and overall habitat quality. In addition, there is often an increase in invasive species and a decreased diversity of non-plant organisms. Some species that provide important biological niches to the ecosystem may be eradicated. Effects on plants Because earthworms take away valuable nutrients needed by plants, Specifically, trees like poplar, birch, and maple are disfavored by the change in habitat, as are many forest herbs like Aralia, Viola, and Botrychium. These plants are strongly negatively effected by the activity of invading earthworms. When a decrease in overall ground cover and canopy vegetation occurs, the few plants remaining are often eaten shortly after germination. For example, in newly invaded forests buckthorn and garlic mustard, both invasive species, increase notably in population density. Moreover, the decrease in plant biomass due to species richness affects earthworms is directly related to trophic levels. The lower trophic levels are affected less than the higher trophic levels. ==Origins==

Origins

Most of the invasive earthworms are European or Asian and came over in soil during the 18th century as Europeans began settling the North American continent. The worms were originally transferred through the horticultural trade, probably in the soil bulbs of European plants carried to the Americas. Some earthworms have been brought over to be used as bait for fishing and escaped or got released. For example, at least one species of earthworm was introduced in Alaska as bait for anglers.'''' The lack of competition from native earthworms allowed the invaders to flourish. Now recreational practices and construction methods are the primary mode of transportation for the earthworms. Particularly of the genera Amynthas and Metaphire''. These earthworms have a variety of nicknames due to their characteristic thrashing behavior, including "Asian jumping worms", "Alabama jumpers", "crazy worms", and "snake worms". The effects of invasive Asian earthworm species are much less documented than those of European lumbricid earthworms, but there is greater concern over the potential effects of jumping worms on soil structure and chemistry, nutrient cycling, forest regeneration, and animal and plant communities. reproduce more quickly, and have greater flexibility in their diet than European species. They can also exist at higher densities than European earthworm species. These characteristics may allow jumping worms to outcompete their European earthworm competitors. These traits mean that jumping worms can consume organic matter more rapidly, stripping the forest floor of organic matter and temporarily flooding the system with nutrients. Northeastern forests evolved under the slow decomposition and release of nutrients, and it is still unclear how forests are responding to the rapid breakdown of organic material. ==Prevention ==

Removal

. One way invasive earthworms can be removed from the environment is worm grunting. Worm grunting is the act of vibrating a wooden stake that has been driven into soil to bring worms to the surface where they can be collected by hand. Another way to remove invasive earthworms are mustard pours. Mustard pours are of water and ground yellow mustard seed mixed together. This is better for gardens because it can be poured over soil to drive worms to the surface without harming any plants. ==See also==

Source: Wikipedia ↗

tickerdossier.com tickerdossier.substack.com