By Marilyn Loser: 2013 January 2
In the last column I discussed native Colorado pine trees – the evergreens whose needles grow in bunches. What other evergreens are native to Colorado? Spruce, Juniper, Fir, and Douglas Fir.
Most people are familiar with the Colorado Blue Spruce (picea pungens) – our state tree. In Alamosa, it’s the tallest tree in the landscape. The needles are typically bluish-green, especially the new growth. If you walk up to a Blue Spruce and “shake hands” you’re likely to have a prickly reception. The needles are very stiff and sharp and usually stick out evenly all around the twig, very much like a bottle brush.
The cones tend to cluster in the top third of the tree and they hang down. Mature cones are from 2 – 6 inches long; the ones in Alamosa tend to be around 3 inches long.
Colorado Blue Spruce do well in Alamosa. While they prefer moist conditions, Blue Spruce are drought resistant and can survive extremes of temperature. They do need to be watered in Alamosa. Most of the old, tall spruce in town that look awful are in yards that are no longer watered.
They can tolerate some abuse. The two Blue Spruce in front of the Alamosa police station weren’t watered during the building renovation and building materials were carelessly strewn under them. In spite of that, they seem to be doing well.
Pine scale is can be a problem for spruce. According to Forester Adam Moore, “The most common reason for us to look at Blue Spruce in the valley is for Pine Scale.” If you have concerns about your Blue Spruce, contact the Alamosa office of the Colorado State Forest.
Blue Spruce grow in the mountains surrounding the San Luis Valley, but not usually in extensive stands.
The most abundant spruce on Wolf Creek Pass used to be the Engleman Spruce (picea engelmannii). It usually grows at high altitudes, higher than Alamosa, and in moist conditions. I used to do a lot of back country skiing and camping in the area in the early 1980s. The forest was lush and healthy. This fall I was startled to see so many dead Engleman Spruce. It made me very sad.
Entire stands of Engleman Spruce in Colorado are being devastated by the spruce beetle. To read more about the spruce beetle infestation in Rio Grande and San Juan forests, go to www.ext.colostate.edu and search for “spruce beetle.”
I don’t think I’ve seen Engleman Spruce in Alamosa, but it can be hard to tell. Their needles aren’t quite as stiff and sharp as the Colorado Blue Spruce and its cones are smaller. “Engelmann spruce hybridizes with Blue Spruce, yielding trees with intermediate characteristics,“ says S. K. Wier of westerexplorers.us. He points out that not all botanists agree about this.
Another Colorado native evergreen that is plentiful in our surrounding hills is the Douglas Fir (pseudosuga menziesii). In fact, I’m looking at one in my house right now. The Christmas tree we cut in the forest this year is a Douglas Fir. Douglas Fir isn’t a true fir. It has short, flat and soft needles similar to firs. But the needles taper at the base and have a groove on the upper surface. If you’re in the forest and see a mature “fir” look around for cones underneath the tree. If you see a bunch, the tree is a Douglas fir as true fir cones tend to disintegrate before they reach the forest floor.
Firs that grow in the mountains around us are the White Fir (abies concolor), Corkbark Fir (abies arizonica Merriam), and the Subalpine Fir (abies bifolia Murray). I’m not great at telling them apart. The Corkbark Fir only grows in southern Colorado and northern New Mexico and often has very white bark. As the tree matures, the bark becomes soft and breaks into ridges giving it a cork-like appearance.
White Fir live below 10,000 feet in central and southern Colorado and in northern New Mexico. The needles are longer than the Subalpine Fir.
We also have junipers in our area. You’ll see a number of Rocky Mountain Juniper (juniperus scopulorum) around Alamosa. You can tell them apart from other evergreens as their needles are more triangular and overlapping rather than thin. In the forest, you often find them growing with pinons.
“Trees outstrip most people in the extent and depth of their work for the public good.” Sara Ebenreck, American Forests