Tuesday, December 11, 2012

The profound Fraxinus

Species name: Fraxinus profunda

Common name: Pumpkin ash

Location: Ontario

The native range of the pumpkin ash is predominantly in the United States, stretching along the eastern seaboard from Virginia down south to Georgia. There are also isolated populations in Florida, Nebraska, Indiana and Illinois, and very recently there have been a few individuals found in southern Ontario. Normally when you find only a few of a single species the determination of "native plant" is not usually made, but these individuals are growing in old growth forests that have been undisturbed for centuries; the chances of these trees having been planted there as ornamentals is slim to nil. The pumpkin ash is also very rarely used as an ornamental species this far north, so the chances of those trees growing there naturally is quite high. The native range of the pumpkin ash is now highly fragmented, with isolated populations occurring along the coast and very little in the interior due to habitat loss. While this species isn't officially listed as threatened or endangered on any Species At Risk list, the chances of this happening is high unless we start planting more of them. They are by far the largest of the ash species and grow quite quickly at first, so they are great shade plants. They also like swampy areas and so are great alternatives for areas that are prone to flooding.

As for uses of this tree to humans other than ornamental use, I can't think of any. That doesn't mean they are "useless"; many insect species feed on the pumpkin ash, and there are some species of butterfly that lay their eggs exclusively on pumpkin ash leaves for their larvae to feed on once they hatch. Unfortunately, the pumpkin ash is incredibly sensitive to the emerald ash borer since the bark is much thinner than other species; this widespread non-native pest is now helping to contribute to the population decline. Unlike the white ash, there don't seem to be any individual trees that are less susceptible or even resistant to infection, so unless we develop some sort of pesticide to use on these trees they will likely all be lost.

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