So this is European Beach grass, Ammophila arenaria.
And it was actually introduced intentionally to
San Francisco in the 1860s.
And then later on down in the Pajaro Valley in the early- 9-teens.
It was introduced to stabilize dunes.
So, people knew what it was going to do.
It's native to Europe.
And it occur's all the way from Scandinavia down to the Mediterranean on
the coastal strand.
Here, in the California, in absence of all of its natural consumers and
pathogens, it does extremely well.
And Ammophila arenaria, or European beachgrass, it's kind of
a poster child for an invader that affects the ecosystem that it invades.
Because it not only changes the plant community,
but also really affects the geomorphology of these dunes.
So you can see that it forms these really, really dense stands.
And if you can imaging, being a beach strawberry, or
a little sand not being able to compete with this beach grass for
light, for space, and maybe also for soil resources.
This beach grass invades the four dunes.
It invades the dunes closest to the ocean,
which is also where you find the most dune adapted pioneer native species.
So there are at least six federally threatened or endangered species
that have been pushed out of many places by this invading beach grass.
Its growth habit is that it puts down these really, really deep roots, and
it spreads mostly by rhizomes.
Its seeds don't do very well in the shifting sand, but
it's able to spread really fast through those rhizomes.
It can go up to a meter every three months.
So, it can cover really really big areas quickly.
And with those deep rhizomes and all of these above ground biomass,
it captures a lot of sand blowing in from the beach and it stabilizes the sand.
The result is that the dune ridges get high and
steep like the ones you can see over here.
And the four dune facing the beach also gets really steep and unstable.
That makes that slope less usable by native plants like the beach bur.
And it also makes the dunes at the front of the dune field
block sand movement to the back.
So you get to the back dunes and there isn't sand coming in there so
much anymore.
And so those communities gradually shift away from the dune adapted
species to the more common grassland species, coastal sage shrub species.
And then invasive species of the inland terrestrial areas that typify
a lot of California's coast.