A really common but kind of overlooked tree in the lowlands of the Willamette Valley is the
Oregon Ash. So this is Fraxinus latifolia and it's really easy to identify because
it's the only tree we have in the Willamette Valley that has these pinnately compound leaves.
So, this is a compound leaf made up of these smaller little leaflets... and usually there are a
couple more leaflets on the side, but these trees are starting to drop their leaves and leaflets
so we're starting to lose a few. They also have another pretty distinctive feature which is their
seed. It's quite a bit like the Maple seed except, rather than having those two
samaras that kind of allow it to helicopter down, it only has one little wing attached to the seed.
So, they don't travel quite as far and you can usually find them littering the ground underneath
the Ash tree. These tend to grow in kind of wetter habitats. They're really resistant to flooding. In
fact, the ones behind me frequently get flooded almost every year sometimes up to almost
over my head. So, in the April flooding that we had in 2019, I would be completely
underwater right now and so would the trees behind me. So they're really tolerant of flooding,
but what happens is that they are also frequently prone to heart rot. They tend to rot out from
the center. So they're really prone to breakage--in the winter storms we get, they often lose a lot of
branches or even half of a tree but they're extraordinarily resilient. So that heart rot
doesn't matter for their ability to transport nutrients up and down still... it's only kind of
a structural issue. So as long as they can stay standing, they'll still put out new branches.
If you look closely at Ash trees, particularly around the Arboretum where within the last five
years we've had a couple significant winter storms, many of them have lost their tops.
They have maybe even lost half of the entire tree and are growing back and growing back strongly.
They're a really incredible tree. And the other thing that's great about that... now, not necessarily
great if you've got a house underneath it, but great from a habitat perspective, is that they're
full of cavities, too. So they're great for nesting woodpeckers. They're great for nesting wood ducks.
Great for nesting raccoons. Raccoons love to hang out inside those cavities. So, they are really important
from a habitat perspective. Another common tree that's usually found in lowland areas is the Big
Leaf Maple. This is our kind of dominant Maple. We only otherwise have some vine Maple species.
It's really, really easy to identify. It has that classic Maple leaf.
Often, they can get a lot larger than this one they can get as big as your head sometimes,
hence the name Big Leaf Maple. And that that big leaf size is expressed in its scientific name,
too. It's known as Acer macrophyllum and macrophyllum just literally means "big leaf."
So, it's a pretty fantastic tree. They can get quite large, quite big around, and often develop
burrells around the base which can be used beautifully in woodworking when the tree ends
up dying. These are not very long lived trees overall, and they tend to grow pretty quickly.
This one behind me is, you know, likely less than 100 years old, though quite tall
and a really spectacular tree. Another thing that's really interesting about them is that they
really strongly attract some epiphytes, so plants that grow kind of on the outside of
of the tree, on the bark, and on the branches. One of those is the Licorice fern. This is
a plant that begins growing with the initiation of the fall rains. It usually takes about an inch
to a couple inches of rain to get them to start growing. This fall has been
really dry so far, but we did get a couple heavy rains that were enough to just start them going
and so they're beginning to leaf out. In a couple weeks, they'll look a lot more...
a lot more fully fleshed out and bigger. But they are a pretty spectacular little plant.
We'll find these growing kind of alongside the trunk and then high up into the canopy.
And this whole epiphyte community that consists of these mosses, the ferns, and then
the lichens that grow in the canopy as well, is actually really important to, kind of, the nutrient
base of the tree. And it's not just the fact that they fall down and decompose and break
down and add nutrients to the soil around the tree, but research has found that their
branches high up in the canopy will actually put out little roots into the epiphyte masses.
So, from those high up branches, they're going to extend roots into these mossy masses
and extract some water and nutrients from that epiphyte community. And that seems to be,
in our area, pretty unique to the Big Leaf Maples in terms of their capacity to do that