Saturday, November 17, 2012



Here are some of the trees on my newly acquired land, lining the driveway leading from the barn to the gate:

Unfortunately, the trees are members of the alien species Pyrus calleryana (Bradford pear). Where plants are concerned, I am a nativist and xenophobe, opposed to immigration and naturalization. My guide in these matters is Douglas W. Tallamy, Bringing Nature Home: How You Can Sustain Wildlife with Native Plants (Portland: Timber Press, 2007; rpt. 2009), who writes (pp. 14-15):
Early on in my assault on the aliens in our yard, I noticed a rather striking pattern. The alien plants that were taking over the land—the multiflora roses, the autumn olives, the oriental bittersweets, the Japanese honeysuckles, the Bradford pears, the Norway maples, and the mile-a-minute weeds—all had very little or no leaf damage from insects, while the red maples, black and pin oaks, black cherries, black gums, black walnuts, and black willows had obviously supplied many insects with food. This was alarming because it suggested a consequence of the alien invasion occurring all over North America that neither I—nor anyone else, I discovered, after checking the scientific literature—had considered. If our native insect fauna cannot, or will not, use alien plants for food, then insect populations in areas with many alien plants will be smaller than insect populations in areas with all natives. This may sound like a gardener's dream: a land without insects! But because so many animals depend partially or entirely on insect protein for food, a land without insects is a land without most forms of higher life (Wilson 1987).
The reference is to Edward O. Wilson, "The Little Things That Run the World (The Importance and Conservation of Invertebrates)," Conservation Biology 1.4 (December 1987) 344-346, who writes (at 345):
The truth is that we need invertebrates, but they don't need us. If human beings were to disappear tomorrow, the world would go on with little change. Gaia, the totality of life on Earth, would set about healing itself and return to the rich environmental states of a few thousand years ago. But if invertebrates were to disappear, it is unlikely that the human species could last more than a few months.
For more on Pyrus calleryana see Theresa M. Culley and Nicole A. Hardiman, "The Beginning of a New Invasive Plant: A History of the Ornamental Callery Pear in the United States," BioScience 57.11 (December 2007) 956-964.

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