Taos residents love quaking aspen trees (Populus tremuloides). Their care can be challenging during the heat and dryness of the summer.
Let’s start with the aspen tree profile.
Aspen trees range from the Rocky Mountains south to New Mexico, elevations from 6,700 to 10,000 feet and from plant zones 3 through 7. Aspens do not thrive where the summers are too hot. Aspens require severely cold winters to grow well. These requirements can be less than ideal here in Taos.
These aspens are considered pioneer trees. They are the first tree species to grow in high elevations after fires. They help with natural succession and allow conifer tree species to get established.
Aspens grow in clonal groves where the moisture collects. They send out rhizomes, which allow multiple saplings to grow as one organism. One of the largest and oldest organisms is an aspen grove in Utah.
With the summer getting into the 90 degree Fahrenheit range and very low humidity, aspen trees struggle and become stressed. Stress can invite pests.
Aspen trees in our hot, arid desert are susceptible to insects and fungi diseases. Cleaning up tree leaves can reduce insect nest and fungi growth. There are systematic fungicides that can be purchased from our local nurseries to help the aspens fight off the infectious fungi.
Some of these pests come in with our wood purchases. Completely covering mixed firewood with clear plastic or a tarp for four to six weeks will cure the wood of pests that could spread to your trees.
Here are some tips to keep your aspen trees healthy and happy:
• Keep soil temperatures cool and moist. Wood mulch placed 6 to 12 inches away from the tree’s trunk, 2 to 4 inches deep, out to the drip line, cools the soil and retains soil moisture, which promotes healthy root growth. Increase irrigation frequency during the hot summer months.
• Ask your hardware store for misters to attach to your irrigation lines. The misters water a larger area, moistening more of the ground around the trees. You can also use a hose with a spot sprinkler that you move around the trees. These spot sprinklers can cover a 3- to 5-foot area.
• Aspen trees are grove-type trees. They are connected by rhizomes (horizontal underground stems producing roots and new plants). New saplings support the mother tree. Aspen trees in clumps can survive hot and dry conditions because they support each other. Aspens in a grove can reduce the transpiration rate (evaporation of water from plant leaves).
With that being said, aspen tree suppliers and placement for planting are important factors for their survival. New aspens should be purchased from local nurseries; clumped aspen trees with three or four stalks in containers survive better than a single aspen tree stem. Planting location should be on the cooler side of your property; north, northeast and southeast aspects are recommended.
• Remember, caring for trees here in the high desert is challenging. Knowing your tree profile (species requirements) can provide the understanding for healthy trees. Local site conditions on your property are key factors for individual tree survival. Mulching, composting, ground covers, companion plantings and soil moisture retention are some holistic approaches for beneficial tree communities.
Finally, don’t forget that “healthy trees are happy trees.” We are given the opportunity and privilege to care for trees, one of the largest, longest-living organisms on our planet. Let’s do our best.
Jones is a certified arborist and consulting arborist in Taos.