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The Western Juniper


Submitted by Nest Bend on

Central Oregon’s beauty inspires in us a sense of belonging, of being a part of something larger than ourselves. Our neighbors are as diverse as the habitats they call home, and can teach us a great deal about co-existing. Here’s your neighbor of the month!

Western Juniper, Juniperus occidentalis, is a very common companion of ours in Central Oregon. And human nature being what it is, sometimes we take for granted the things around us that are in relative abundance. But this species of tree actually has some very important lessons to teach!

Native to both mountain slopes and high plateaus of the Pacific Northwest, it is highly adaptable, therefore it is found at very diverse altitudes of from 500 all the way to around10,000 feet.

An interesting fact about most juniper species is that they are dioecious, a Greek term meaning two houses. What this means is that about half of the trees are male, and the others are female. There is an efficient specialization within this species (in contrast to pine trees): the males produce the pollen and the female trees produce small, round, blue “berries.” Many birds love this valuable food. Despite their appearance, they are actually cones, but with a rather leathery instead of woody texture.

The tree has a very distinctive fragrance caused by its essential oils, which lead some to mistakenly call it “cedar.” This essential oil enables junipers to be superior to most other woods in rot resistance. Therefore it makes great fence posts that don’t rot. OSU has fence post trials that go back to the 20s and 30s. The juniper heartwood fence posts from way back then are still standing!

A major key to its widespread distribution is that Western Juniper is far more drought tolerant than most trees; it can actually spread in some droughts, as other trees die back and new territory becomes available. This is largely due to a key structural adaptation in junipers leading to much greater resistance to cavitation. Cavitation is very damaging to trees and occurs when air bubbles form in the water conducting xylem tissues of plants. The xylem tissues of junipers are actually reinforced with extra woody material to help prevent rupture of these vital conduits.

Partially due to this drought resistance, it is estimated that between 1936 and 1988 the area occupied by Western Juniper in eastern Oregon increased from 420,000 to 2,200,000 acres. Too much of a good thing! Another major reason for this overgrowth is that we’ve changed the way grasslands are managed. Native Americans previously ignited the grasslands to help keep them open and healthy. Now we do our best to suppress fires because they threaten houses, livestock, etc. It is a dilemma, but unfortunately we’ve helped create a juniper invasion.

The multiplying Western Juniper is degrading sage grouse and other wildlife habitat, shading out native grasses, and drying up ground water. Western Juniper is a native species, and thus has a place in Oregon ecosystems. But currently it is out of balance and presents a challenge to forest and range managers as to how to best keep it at a level that is healthy for the overall ecosystem.

Despite this present lack of balance, these trees are capable of teaching us a great deal about adaptation to a wide variety of environments, drought tolerance, and resistance to decay. Seeing them as fellow inhabitants of this special Central Oregon space that we call home provides us with even more incentive to take great care of the natural environment that we all share.