Continued from Page 6
Photos by Rebecca Lexa
CLOCKWISE FROM TOP: Scotch broom plants are endemic throughout western Oregon. As the name suggests, common ivy is seen often around
the Columbia-Pacific region. Gorse is an invasive bush seen throughout western Oregon.
One example of this effect can be seen
in the plight of the Oregon silverspot butter-
fly (Speyeria zerene hippolyta). Its historic
coastal range extends from northern Califor-
nia to southern Washington state. The adult
butterfly drinks nectar from a variety of flow-
ers, however the caterpillars’ diet is limited
to the leaves of the early blue violet (Viola
adunca). This limited diet is quite common
among herbivorous insects, which cannot just
instantly adapt to the chemical makeup of
unrelated plants.
Wide swaths of invasive European and
Atlantic beach grass overtook most of the
violet’s meadow habitat, and combined with
fire suppression the grass helped shore pine
forests to advance where coastal meadows
once stood. Today the Oregon silverspot can
be found in only a handful of tiny locations
in Oregon and California, and many meadow
plants like the early blue violet are at risk, as
are the various species dependent on them.
You might be wondering why the loss of
one butterfly species is cause for such alarm.
Well, fewer butterflies lead to fewer pollina-
tors, which lead to fewer plants, resulting in
less food for herbivores and, by extension,
the carnivores that eat them, which lowers the
overall biodiversity in our region over time.
Moreover, many bird species rely on
invertebrates for protein and other nutrients,
and caterpillars are among their best sources.
In fact, the diet of many young songbird spe-
cies consists of up to 75% insects, and with-
out them these baby birds die of malnutri-
tion. With the loss of silverspot caterpillars,
the songbirds now have one less source of
protein, which decreases overall population
numbers. So while one butterfly’s extinction
may seem small, an ecosystem’s connections
mean that similar local and total extinctions
can result in a chain reaction.
So how did beach grass and other inva-
sive plants get here? Some were brought by
early settlerswho carried them on their jour-
ney for their edible or medicinal qualities.
These included dandelions, garlic mustard,
broadleaf and ribwort plantain. Other non-na-
tive species arrived as seeds or sprouts in
shipments of hay and other agricultural sup-
plies. More recently, the gardening indus-
try has deliberately introduced thousands
of non-native ornamental species, some of
which have managed to escape their pots and
wreak havoc on neighboring natural areas.
In my next column, I’ll profile some of the
more pernicious invasive plants found in the
Columbia-Pacific Region, and how they can
be managed.
Rebecca Lexa is an Oregon Master Natu-
ralist, nature educator, tour guide and writer
living on the Long Beach Peninsula. More
about her work may be found at RebeccaL-
exa.com.
THURSDAY, MARCH 3, 2022 // 7