Dear HCN,
“Tackling Tamarisk” (HCN,
5/25/98) lifts the lid on a nasty can of worms, namely the invasion
of Western wildlands by alien plants – those dreaded weeds. Paul
Larmer credits tamarisks with spreading into “virtually every river
system in the West.” Could be, depending on the definition of
“river system.” More to the point is how many miles of rivers are
lined with stands of tamarisk? Many river systems have loads of
tamarisk in the lower reaches yet are free in the middle and/or
upper portions.
Second point is treating several
species of tamarisk as a single entity. Certainly there are
thousands of miles of good waters unsullied by this curse. Tamarix
rammosissimum and its cohorts that form mostly tall shrubs and
spread by underground root sprouts are the major culprits. Your
photo of the chainsaw-cut trunk is clearly Tamarix aphylla, the
athel tamarisk, which makes a good-sized tree, spreads very slowly
(if at all without man’s help) and really makes a decent ornamental
for some areas, although it is tarred with the brush of being a
hated tamarisk. One thing is near certain – all escaped Western
species of tamarisk don’t have the same
autecology.
While the change in regimen of
Western watercourses has certainly made some ideal habitats for the
shrubby tamarisks, I am convinced that if we lacked alien woody
plants, native shrubs would be able to fill the vacuum that we all
know nature abhors. But, the aliens have landed and we can’t turn
back. On many a Western riparian zone, should the tamarisks be
eliminated or weakened, Russian olive would fill considerable of
the gaps. After all, it has naturalized from the Mexican to the
Canadian border, and in all 17 Western states. I’d guess that more
miles of Western streamsides are dominated by Russian olive than by
tamarisks. Which of these two is better or which the worse will
foster a great debate.
For a map of the extent of
Russian olive’s hold on the West, see: “Naturalization of Russian
olive in Western United States,” Western Jour. Applied Forestry,
I(3) 1986. While tamarisks are a new invader to the Snake River
Plain in southern Idaho, the spread at this northern limit is
rapid. See “Wild Trees of Idaho” (U. Idaho Press, 1995).
And, folks, we haven’t touched starthistle,
skeleton weed, halogeton, cheatgrass, spotted knapweed, et cetera,
et cetera, et cetera!
Fred
Johnson
Moscow,
Idaho
This article appeared in the print edition of the magazine with the headline All tamarisk isn’t the same.
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