Wednesday, October 04, 2006
Worms as gardeners...who would've thought it? Ohio State University Extension has issued a press release describing the odd behavior of the non-native nightcrawlers (Lumbricus terrestris) in their state. The earthworms have apparently been gathering seed from giant ragweed (Ambrosia trifida) and carrying it back to their burrows. While large ragweed is not the only seed the earthworms like to grab, it seems to be the most popular, a fact made all the more interesting when you consider that giant ragweed is a native plant. What makes the seeds so popular among the nightcrawler crowd? Scientists aren't yet sure, but they have hypothesized that the earthworms might be using the seeds to strengthen their burrows, or as a future food source once the seeds start to decay. Either way, the resulting effect is similar to the squirrel-acorn relationship: many of these buried seeds go on to germinate, and it is thought that the activities of the earthworms have greatly contributed to the spread of giant ragweed.
By coincidence I thought I was coming down with a cold a few days ago, but now think it was ragweed (I know better than to blame goldenrod).
That's an amazing observation with the earthworms. I've run across the issues with the nonnative L. terrestris crowding out the natives, but this is something new. I wonder if the natives select seeds?
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