This summer, during one of my escapes to the cooler climes of the Sky Islands, I was scrambling under the canopy of mixed conifer forest near the peak of Mount Lemmon, and I was having an appreciation for our native conifers. It is a marvel that in such a short drive, one can find oneself dwarfed by giant trees, enveloped in the piney odors of Tucson’s favorite escape from the heat.
When people think of the Sonoran Desert, they probably don’t think about conifers, especially Douglas fir or ponderosa pine. But these trees are important to this region and crown the mountains that hover over our desert and grassland. Many old Tucson homes even have some Mt. Lemmon timber in their walls and roofs, especially in Barrio Viejo.
The aforementioned Sky Islands, if you aren’t familiar with the term, refer to the scattered mountain ranges that rise above the desert in our region. They bridge the gap between the Rocky Mountain range to the north, and the Sierra Madre to the south, and this position has a lot to do with why our dry desert has so much diversity in organisms.
The best place to become acquainted with our native conifers, in a relatively short trip, is the excursion up the Catalina Highway to Summerhaven, the town near the top of the Santa Catalina mountains where Mount Lemmon resides. From my house at the base of A Mountain, just west of downtown Tucson, it takes about one hour and 20 minutes to get there.
As you rise above the desert and get into the landscapes where grassland and oak woodlands replace the desert landscape, the first conifers you will generally see are the Junipers and Cypress. Not long after that you will see your first pine — the piñon. As you keep ascending past the grasslands, chaparral and oak woodland, and into true forest, the forest get taller, less interrupted, and the pines get more diverse. Finally as you reach the cooler, wetter heights of the Santa Catalinas, the mixed conifer forest, you find the firs and spruces mixed with pines.
As a native plant enthusiast (botanist), I get asked a lot about general identification of these trees. People who wander in the mountains generally want to know the general names of these trees, if not the exact identification.
Below are some general notes and lists of species you will find in our region. Not all of these trees are in every mountain range in the Sky Islands region — Rocky Mountain species dominate the more northerly mountain ranges while the species from the Sierra Madre (sometimes referred to as Madrean species) start to infiltrate the forests in the more southerly ranges. You may notice a difference in species between cooler northern slopes and south-facing, warmer slopes too.
If you really wanna get nerdy and learn to tell the difference between the specific species, consult the Field Key to Southern Arizona Conifer Trees by Richard Brusca and George Ferguson. Don’t let the terminology deter you. It’s really not that hard to learn how to key out a species. For the rest of you, here are the general difference between the conifers, or cone-baring evergreen trees of our region.
The Junipers and Cypress
The foliage on these plants resemble scales rather than needles. Some female plants actually have berry-like cones, and if you love drinking gin you have these “fruits” to thank for gin’s Christmas tree-like flavor. Three Wells Distilling Company actually uses native juniper berries in the production of their local gin. The alligator juniper might be most famous because of its bark, which is responsible for its namesake (the bark on the trunk is checkered into small plates that resemble alligator skin). Juniper and cypress plants are generally found in the mid elevations of the grassland, chaparral and oak woodland. There are many non-native junipers and cypresses that are used in Arizona landscapes, perhaps the most conspicuous being the Italian Cypress which are those columnar trees you see most often in cemeteries and old neighborhoods.
Arizona Cypress (Cupressus arizonica)
Alligator Juniper (Juniperus deppeana)
One Seeded Juniper (Juniperus monosperma)
Arizona Juniper (Juniperus arizonica)
Pines needles, the adult leaves, are green and bundled in clusters called fascicles. The needles can number from one to seven per fascicle, but generally number from two to five. You can tell a pine from a fir (described below) by the basal sheath that the needles emerge from. Pines are probably the most famous conifers, and economically one of the most important trees in the world — pine wood is found in virtually all homes. Traditional pesto is made with the seeds of pinyon pine. Pines start to occur in the grassland, chaparral and oak woodland (the piñon pines) and grow taller and more diverse as you get higher into the sky islands. A few non-native pines are planted throughout Tucson, especially the Aleppo and Eldarica pines. Before people were more aware of native desert landscaping, these pines were widely planted around Tucson. And they make good shade trees once established. They are less often planted these days, though during the holiday season each year, many get planted after being used as live Christmas trees.
Border Piñon (Pinus discolor)
Piñon Pine (Pinus edulis)
Apache Pine (Pinus engelmannii)
Rocky Mountain Ponderosa Pine (Pinus ponderosa)
Arizona Pine (Pinus arizonica)
Chihuahua Pine (Pinus chihuahuana)
Southwestern White Pine (Pinus strobiformis)
Limber Pine (Pinus flexilis)
Spruces can look a lot like pines, but can be identified by their quadrangled needles, especially at the base of the needle. Spruce wood is also an important building material (usually referred to as “North American timber” or “whitewood”). It is even more important as paper pulp and for building musical instruments. The spruces are found in the higher elevations of the sky islands. Spruces really don’t do well in the low desert, so you don’t really see them in landscapes in Tucson. The most famous is maybe the blue spruce, the blue tree you see in the Christmas tree lots during the holidays.
Engelmann Spruce (Picea engelmannii)
Blue Spruce (Picea pungens)
The Firs and the “Firs”
Firs can be distinguished from the pines and spruces by the unique attachment of their flat needle-like leaves to the twig by a base that resembles a small suction cup. In contrast to spruces, even large fir cones do not hang, but are raised like candles. True firs are not considered great building material, and are generally used as pulp for paper or compressed particle wood. Douglas firs, however, are not true firs — true firs have needles that are upturned and not whorled. Douglas firs have needles that are singly wrapped around the twig with a white line underneath, whorled around the branch, and narrowing where they attach. Also unlike true firs, Douglas fir is extensively used for timber, worldwide. The firs occur in the upper elevations of the sky islands. Firs, like spruces, cannot tolerate the low desert heat, and are not found in landscapes in Tucson. However, fir trees (both true firs and Douglas fir) are the most commonly used species as cut Christmas trees (the common green ones anyway).
Rocky Mountain Douglas Fir (Pseudotsuga menziesii)
White Fir (Abies concolor)
Corkbark Fir (Abies bifolia)
Learning to tell the species apart will force you to spend more time in these forests, perhaps help you to become aware of how important they are, and how special and threatened. Global warming is perhaps the biggest threat to our conifer forests since the warmer, drier times we are experiencing bring more wildfire, and insect problems to our region. In recent years in the west, wildfire has become a serious problem, as have explosions of pine bark beetles which wipe out large areas of pine forest. Below normal winter precipitation coupled with normally dry conditions in May and June increase the susceptibility of Arizona’s pines to the beetles as well as other health problems.
I spend as much time as I can in these forests, in the mountains. As a family, we even cut our own christmas trees rather than buying farmed, non-native trees — the Coronado National Forests gives out permits for this each year and it actually helps the health of the forest. Though I am sure if everyone did this, it might be a different story. But let’s be honest, most people are way too lazy to go hike out into the mountains and cut down their own trees.
I believe if more people had a personal relationship with our forests, we’d all be more proactive in preserving them. And the benefits of camping in the mountains are too compelling and manifold to convey in an article. I suggest first hand experimentation to understand the impact the conifer forests can have on you.