Friday, July 22, 2011

Science Video Friday: Invasive species are a nuisance


Invasive species: from North America to New Zealand to Antarctica, they're a problem. Invasive species, when transported to a new environment, have the capacity to overwhelm the ecosystem and throw it off the natural balance that has been reached by the indigenous organisms. This causes severe damage to the ecosystem, and can have many unforeseen consequences: among them local extinction of native organisms and even increased flooding due to increased storm water runoff.

Here in Southeastern Ohio, some of the more common invasive organisms I see are Tree of Heaven (Ailanthus altissima), Japanese honeysuckle (Lonicera japonica), and the dreaded Japanese knotweed (Fallopia japonica). From what I've seen, Japanese honeysuckle and knotweed are especially nasty invaders, and can take over forests and other areas without prejudice. In the case of Japanese knotweed, it spreads via rhizomes, making it even more difficult to eradicate. One of the major problems of invasive plants, and also the reason why they can propagate so efficiently, is that they don't have many insects that feed on them. The native insects don't have the machinery to digest the invasive plants like they do for the natives, so the invasives spread without much stopping them. Some insects do feed on these invasives, but it's not to the extent of the number that feed on them in their native environment.

Interestingly enough, I've observed Japanese beetles (Popillia japonica) feeding on the leaves of Japanese knotweed. Unfortunately, Japanese beetles themselves are an invasive species, so that's not really a solution to the problem.

While much of what's published on invasive species is about their detrimental effects on the environment, they're not all bad. As discussed in this article from Penn State University, some invasive species can have positive effects for birds. Unfortunately, this positive effect is inconsequential when compared to all the harm invasive species bring to the environments they colonize.

While many of the examples I used were invasive species native Japan, it of course doesn't mean that that is the only place our invasives come from. We have invasive species from all over the world, these examples were just the most well-known to me. Besides, our indigenous North American species have become invasive on other continents as well. Ah, globalization!

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