by Steve Reinbrecht
There is a forest stretching through my neighborhood, all
one kind of tree, an invader from East Asia that pushes out the local plants.
Bradford pear trees [Pyrus calleryana] are
pretty. They brighten up our neighborhood this time of year. Also known as Callery
pears, the tree is native to East Asia. Developers installed them among homes
and businesses all over the United States.
But now, experts warn against planting them, mostly because
they break catastrophically if not pruned when they are small. And they grow
happily everywhere, spread by birds, especially starlings [another invasive]
and robins, a native though opportunistic sort of bird.
On Saturday, robins, swarmed the thicket of pears in bloom
south of the Wilson West Middle School. The trees are invading the area, some
of it set aside as educational open space.
A huge swath of the trees winds along the Little Cacoosing
Creek and then across Green Valley Road and along a power-line easement. The
trees are thick and dominant.
They were full of robins Saturday.
But I wonder if other native birds and pollinators feel at
home in the foreign species.
Bradford pear forms dense thickets that push out other
plants, including native species, that can’t tolerate its deep shade or compete
with it for water, soil and space, the National Park Service says.
Its success as an invader results from three things, the
service says. It can produce copious amounts of seed that is dispersed by birds
and possibly small mammals. Its seedlings grow rapidly in disturbed areas. And
it lacks natural controls like insects and diseases, with the exception of fire
blight.
Identifying these species when they are first spreading
could reduce the eventual high cost of their control and eradication.
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