By Eliot Patton
When most people think of New Mexico, they are likely to imagine an arid desert with a few saguaros, maybe a tumbleweed here and there. However, running right through the middle of the state flows the fourth longest river in the United States. The Río Grande. In what is known as the Middle Rio Grande Valley, in central New Mexico, grows a large cottonwood forest, more commonly called The Bosque. Gnarly, twisted cottonwood trees (Populus deltoides wislizenii, spp.), the Bosque's dominant species, grow all along the river. People use this forest for recreation, education, and for some it even has spiritual meaning. The cottonwood tree, specifically is held sacred in many tribes of the southwest.
According to wildlife biologist and Bosque School science teacher, Sarah Hooper, "Cottonwoods we consider the Heart of the Bosque. Just like your heart, they keep you alive. The cottonwoods keep the Bosque alive. [They] help provide structure to the forest. There's the grasses below, then shrubs underneath, and big trees overhead. That allows lots of different types of animals to live there that couldn't normally live in the desert. Things like porcupines, eagles, small songbirds, that need to live in a place that has lots and lots of trees."
Ms. Hooper's colleague, Dan Shaw, is the co-director of Bosque Ecosystem Monitoring Program (BEMP). This program involves schools all over New Mexico in work that monitors insect and rodent population, rainfall, leaf litter, depth to ground water, and more. Mr. Shaw agrees, "Cottonwoods as an essential part of the Bosque, play a huge role for habitat, for cooling, for temperature regulation, because you've got this canopy and the shade. If you don't have some sort of shading tree, it going to get hotter. So, there are elements about thermal regulation, in terms of temperature. There issues for animals and their habitats, utilization of that space, and also just the other plants that are associated with that," he says, "You end up with a community that's cottonwood dominated, but it also has other species that are associated with it that are able to survive because of the cottonwood." These majestic trees, the heart of the Bosque and home to a diverse range of animals are nearing the end of their life span. The Rio Grande Cottonwood has a life expectancy of 80-100 years and the trees that we know and love are already 75 years old. The future of the cottonwood and the bosque as we know it is looking bleak.
In fall, cottonwoods become a radiant shade of yellow. In summer, lush shade of green. Photo credit: Anna Gilboard
The biggest factor in the bosque’s future has been human impact. In the late 1800s, the people living near the then wild, meandering Rio Grande were getting tired of the constant flooding. By 1920, they had established levees that confined the river and drainage ditches as well. What they didn't know was that they were also removing a large amount of cattails, cottonwood seedlings, and even species of fish. In 1941, the last of the great floods in the Bosque took place. After this, the people took action. They built a dam to control flooding and laid down jetty-jacks in order to limit debris damage. Finally, they added non-native plant species that require lots of water, as an added protection against flooding.
Now, the adult cottonwoods of the Bosque are nearing death. Due to the lack of flooding, the river has not created new habitats for cottonwood seedlings to grow into saplings and mature trees. Instead, what is replacing them is invasive species, such as Salt Cedar and Russian Olive. If we continue to let this happen, the heart of the Bosque, the Tree of Life, the sacred cottonwood will no longer support the beautiful Bosque ecosystem. “I think one of the things to do is to think of the Bosque of more than just what it is now and to be open to the idea that the Bosque is going to change. What will that change look like?” Asks Dan Shaw, “What will give the best environmental menu of options for animals and other oraganisms to survive in the context of climate change, drought, less water, more competition from humans for that water? All of those pieces. And then keeping water in the Rio Grande. The river isn’t necessarily guaranteed water. There should be a way that humans can get our own needs and respect the river having it’s own water. It’s vital to us to protect the environment for our own good. What can people do? Learn. Act. Teach others. Look for ways to demand that our environment is cared for...”
Data showing canopy coverage as of 2015 and future predictions. Credit: BEMP
Additionally, measures are being taken by students in BEMP, members of Sandia and Santa Ana Pueblos, Albuquerque Open Space, and Rocky Mountain Youth Corps, an organization devoted to many restoration and preservation projects. Individuals can contact one of these organizations to help plant trees, to remove exotic plants, or to learn more about the beautiful Bosque ecosystem and the cottonwood tree.
Students plant trees along the river. Photo Credit: Sarah Hooper