Parallel PatternsThe beauty, diversity, and complexity of western North American ecosystems perpetually blows my mind. Growing up in San Diego, California, before I delved into my quest of knowing plants and their names, I learned to love the desert chaparral ecosystems of the west coast. I didn’t know the specifics, but I integrated, appreciated, and loved the feelings of these landscapes in my innermost being. As I grew into the farmer / artist / ecologist that I strive to be these days, the *Oaks* took their rightful place as the Keystone Species in my personal catalogue of awe inspiring plants, worthy of my devotion.
Moving to the Pacific Northwest and starting Earth Ecology LLC in my mid-twenties, I began to acquire plant names, and I began to map them out into their native homes. I could eventually grasp how plant species relate to others in their families, and could envision the historical and evolutionary processes of species distinction, hybridization, isolation, and migration. The boundaries of “native” ecosystems have become increasingly harder to isolate across vast stretches of our neighborhood of western states. The vast majority of native plants of the Pacific Northwest are also the same native plants I encounter in Southern California. Quercus, Arctostaphylos, Baccharis, Ceanothus, Cercocarpus, Frangula ...
The Arizona mountains, called “Sky Islands,” are home to plant species one may never expect to find if they were to remain in the desert valleys. Going up in elevation demonstrates a similar effect as going up in latitude. Colder and wetter weather modifies the plant communities, and there are clear observable ecosystem transformations every few hundred feet of elevation change. Mt. Lemmon, towering above Tucson, was my first foray into the sky islands (2021). Every ten feet we drove up the mountain I wanted to stop and look and study. But I don’t just want to look when I get to this state. I wanted to gaze. It is essentially impossible to satisfy my need to gaze at these landscapes, absorbing hidden information of the land and its complex transformation, balance, and beauty, dreaming of future gardens I would like to design, mimicing the plant pallets found in these diverse western wonderlands.
Beginning as desert valley, with one of the most amazing displays of Saguaro cactus, the desert transforms at 4500’ elevation into a landscape reminiscent of Southern California. Oaks begin to dot the landscape in a savannah full of abundance. Quercus oblongifolia, the Mexican Blue Oak, gorgeous and glowing with its evergreen, oval shaped, glaucous blue leaves is among the first to show up, along with Quercus emoryii, intermixed with Arctostaphylos, Frangula, Garrya, Juniperus, Baccharis, grasses, agaves, and yuccas. A few feet higher in elevation and Quercus arizonica shows up, similar in color to Q. oblongifolia but with slight wooly pubescence on the leaf surface, and an indumentum on the bottom side of the leaf, plus Frangula, and ferns!
Further along up the mountain, Quercus hypoleucoides the silver leaf oak, and Quercus rugosa the netleaf oak appear, continuing onward up to the highest elevations of the mountain as the other oaks fade away. But it isn’t just an oak tree game - at higher elevations, species familiar to Pacific Northwest native plant gardeners begin to show up - snowberry, oregon grape, currants, firs, maples, aspens! It was the snowberry that I saw as we turned a corner on the upper elevations of Mt. Lemmon that truly unveiled the potential for harmonious unity between our PNW ecosystems and the beautiful and resilient species of Arizona.
“Chiri”The correlations between Arizona sky islands and Pacific Northwest landscapes have not gone unnoticed, though it doesn’t seem to extend too far back into our PNW garden histories. Sean Hogan of Cistus Nursery was one of the first to plant some of these western native beauties in Portland gardens. One of his favorites, the silver leaf oak (Quercus hypoleucoides) collected from the Chiricahua National Monument, is planted as a street tree in front of his previous home in Portland. Since the first seeds arrived as a gift from his friend, he has been traveling and collecting species from these mountains and growing them for our enjoyment. Now, a keen and discerning eye can notice silver leaf oaks popping up in neighborhood gardens and planted as street trees all around town.
Our PNW native Madrone (Arbutus menziesii) has a cousin in the AZ mountains as well - Arbutus arizonica. Available in specialty nurseries occasionally, the Arizona madrone clone (named “Chiri”) that Sean collected years ago in the Chiricahua is also seen more commonly throughout town (and also in my front yard garden!). I had enjoyed growing “Chiri” for a few years before realizing that Chiri was named after Chiricahua, the range of mountains an hour and a half east of Tucson. It was one of those words that went over my head for a few conversations when I talked about rare oak trees with Sean and Sam. But after visiting Mt. Lemmon and studying some maps of Arizona, I realized the Chiricahua was worthy of a quest!
With the double function of meeting up with my wife Emily’s family in Tucson, we were blessed with the ability to plan a side trip to the Chiricahua, and it did not disappoint. We made our way up to the Echo Valley trailhead loop (Pictured at the top of this writeup) and found ourselves surrounded by plants familiar to the full expanse of the west coast, from Southern California to the Canadian boarder, along with other close relatives, and some unique mysteries that I still haven’t integrated into the growing plant catalogue in my head. Our quest, occurring in early December, maintained a bonus goal of collecting acorns from the blue oaks, Q. oblongifolia primarily, and if we were lucky, Q. Arizonica. Though we didn’t find a single population of Q. oblongifolia on our route through the Chiricahua, I did find fresh and perfect acorns from a Q. arizonica minutes before jumping back into the car to head down the mountain!
The blend of cold tolerance and desert sun tolerance of the Mexican and Arizona oaks makes these species particularly useful and enticing when considering our tasks for designing landscapes for climate change mitigation and adaptation, along with assisted migration. It is clear that the world’s climates are transformng rapidly, and ecologies are bound to evolve. Insects, birds, animals, and humans will all fall into the category of climate refugee in areas that are hit hard by drought, flood, and fires. As restoration ecologists and contractors, we are put to the task of maintaining the stability of our ecosystems by stabilizing the water cycle, and anticipating the patterns of change by selecting particular species that are appropriate to replace diminishing populations of climate change victim species. While the native Oregon White Oak still stand strong in Oregon ecologies, its range has been diminished by up to 97 percent of its original populations. Western oaks of all sorts hold the power to feed and host a wide range of the local fauna and insects. These drought adapted Arizona species, that are already familiar with growing along side our native understories of snowberry, Oregon grape, honeysuckle, ferns, ceanothus, manzanitas, grasses, and wild flowers, etc, hold an interesting potential role of stabilizing our ecosystems amidst climate catastrophe. And if by some miracle humanity can wake up to the global situation and make amends to our systemic impact to create a balanced ecosystem, our biggest problem is to be surrounded by the diversity of beautiful species that make fantastic urban trees with the benefit of supporting local populations of insects and animals. Oaks are a true win-win!