ECOLOGY

Autumn in The Gila, 1 of 3: Trees

Photographs of October in southwestern New Mexico

Inverted photograph from a pond at the Nature Conservancy plot down the road

It’s a really buzzy time because of the US elections, so rather than putting out some writing that’ll just get lost in the noise, I’m offering a 3-part series of photos. I had originally planned just one post, but have been taking so many pictures, I broke it into sections: Trees, Wildflowers and Insects.

I’m currently staying at a friend’s rural property in the upper Gila River valley in southwestern New Mexico. If anyplace can be said to be the home-base in my nomadic existence, this is it. It’s in a remote, sparsely populated location. The pavement ends a mile further down, and the road dead-ends entirely a couple miles later at a campground in the Gila National Forest. From there you can be hiking in the Gila Wilderness in just a few minutes. Also down the road is an old farm owned by the Nature Conservancy where they’re doing passive restoration, where I take walks regularly. It’s also chill enough around here that you can just take off across the pastures to get to the river and nobody pays any mind.

So I’m blessed with a lot of space to explore, full of plants and other creatures, and I’ve been carrying my camera with me so I can share what I find. I hope you enjoy this 3-part visual offering of the more-than-human world.

Arizona Black Walnut (Juglans major)

Wikipedia sez: “grows primarily in canyons or riparian areas, near springs, and other areas with shallow groundwater” which totally describes this location.

The nuts are small, as you can see, but have a robust toasty flavor.

According to Daniel Moerman’s Ethnobotanical database, the nut meats are a traditional food of the Apache, Hualapai, Navajo and Yavapai tribes, and the hulls a source of dyes.

This is the typical leaf shape of a Walnut. Properly described, it’s “pinnately-compound.” This is considered one leaf with many leaflets.

A large specimen (over 40 feet high) at the Nature Conservancy parcel

Range map of Arizona Black Walnut (in flux, like all plant ranges), with red dot marking approximate location of these photos.

Arizona Sycamore (Platanus wrightii)

As observed in the Gila National Forest. Such a beautiful form and strikingly patterned bark. Around here this tree often grows in clumps.

Arizona Sycamore is in the Plane Family (Platanaceae), which contains only one genus, Platanus, with twelve species found around the world. Trees in this family were more common in the Paleocene, 60 million years ago, and date back over 100 million years. Because relatively few species are still with us, and in smaller numbers, the genus is considered a living fossil.

This leaf shape is called “palmate” because it resembles a hand

A clump of young trees, growing next to an irrigation ditch

A clump of mature trees

Range map of Arizona Sycamore (in flux, like all plant ranges), with red dot marking approximate location of these photos.

Velvet Ash (Fraxinus velutina)

Also known as the Arizona Ash or Modesto Ash. This is a tree that’s easy to ID by its seeds, which are called “samaras.” The word “fraxinus” is the Latin name for Ash trees, and also for spears or javelins made from their wood, which is quite strong. Baseball bats are made of Ash. I’m familiar with other species of Ash trees because they are popular city trees, but this one is new to me.

The species is dioecious, meaning that male and female flowering parts appear on different individuals. If the tree has samaras, she is female.

Mature Velvet Ash, about 30 feet tall, which is as big as they get

Young Velvet Ash with pretty foliage. Note the section of branches on the right that are heavily laden with samaras.

Range map of Velvet Ash (in flux, like all plant ranges), with red dot marking approximate location of these photos.

Frémont Cottonwood (Populus fremontii)

Frémont Cottonwood is the most common tree in this area, growing all along the Gila River in open galleries. Throughout the southwest when you see Cottonwoods you know water is close by, usually very close by. This photo is the view from my friend’s property looking over the cow pastures toward the Gila River. The line of trees is a little over 1000 feet away and is mostly Cottonwoods, which are all growing within a few hundred feet of the watercourse.

Indigenous tribes all over the West had a multitude of medicinal and craft uses for various parts of the tree, too many to list here so see Moerman. The tree is named after John C. Frémont (1813–1890) who was a military man and a politician. As a politician he was a slavery abolitionist but as an Army officer he led several massacres against indigenous people. We oughta come up with another name for this tree, which is far more noble than he was.

Trees in places like this are left to just grow and fall apart as they are wont to do. I often think about the fact that city people rarely get to see many trees just grow because they are always getting trimmed for powerlines, roof protection, sidewalk clearance, etc., etc.. All things that, yeah, need to be done, but the result is a lack of familiarity with who trees are as themselves.

The shapes of Cottonwoods often remind me of clouds:

Here is a typical “gallery” of Cottonwoods near the water:

On the Nature Conservancy land there’s a Cottonwood that’s the biggest I’ve ever seen. She’s much wider than tall; yes that’s all one tree.

Here I am, for scale:

I found several places along the river bank where hundreds of seedlings were coming up in dense patches:

What this shows us is that the river’s seasonal flooding regime is fairly intact. Cottonwood seeds are very short-lived and depend on spring flooding from snow melt, which washes them along and deposits them in appropriate places for germination. If the spot is right, they can germinate in less than 24 hours!

Further downstream, the Gila’s flow no longer enjoys these cycles because its flow is diverted for irrigation and many of its tributaries are dammed and no longer flood in the spring. There you’ll find Tamarisk / Saltcedar (Tamarix sp.) and Russian Olive (Elaeagnus angustifolia), who are introduced species of trees whose germination doesn’t depend on flooding, and whose roots can delve down deeper to follow the sinking water table. These species are called “invasive” by some, who claim they have “outcompeted” the Cottonwoods (and Willows). But this claim is incorrect. The Cottonwoods were pushed out by us not the introduced species. Settler-colonial agriculture and industry (namely mining) have totally disrupted most of the river systems of the West over the last century (with said diversions and dams) and in so doing have made these places inhospitable to Cottonwood, but welcoming to Tamarisk and Russian Olive. To add insult to injury, the newcomers are sprayed with herbicides, further degrading the environment.

For a fuller, well-researched account on the myths about Tamarisk and Russian Olive, and how these myths got started (spoiler: by a mining company), see this piece by Nikki Hill and me: “Shooting the messengers: How plants are unfairly blamed for wasteful human water practices in the U.S. West.”

Range map of Frémont Cottonwood (in flux, like all plant ranges), with red dot marking approximate location of these photos. The typically riverside habitat of this tree is quite obvious in the long narrow sections. It’s easy to pick out the Colorado and Rio Grande.