The truth about cedars

There's a lot of misinformation circulating about the ashe juniper, or native Austin area juniper.  This tree (commonly refereed to locally as the cedar) is closely related to the eastern and western red cedars (also junipers).  It is found growing in the rocky soils of a large limestone belt, (the Edwards Plateau) running west to east through the Austin area. This area used to be a coral reef, as large as the great barrier reef, millions of years ago when this area was under the ocean. Due to the unusual limestone soil conditions here, this tree is found here and no where else in the US or the world. A migrating species, the cedar waxwing feeds on the female tree's berries, which are its main source of food when they overwinter here in the juniper forests. 

Contrary to what you may have heard, this species is NOT introduced, but evolved here naturally. The Juniper is referred to as a ‘pioneer species’ and is one of the first species to populate rocky, barren sites. Over time, the species breaks up the rock and forms better soils, allowing for the higher species such as the hardwoods (oaks and elms) to move in. They of course have a bad rap in the Austin area due to cedar fever, caused by the yellow-green pollen they put out in the spring, debilitating to many people with allergies. 

Cedars are also extremely efficient at water uptake, and in forest edge and open areas they can compete with native oaks and other trees for water. This is much more prevalent when areas are partially cleared for landscaping around homes. When cedars grow in a greenbelt forest among other species such as live oaks, ash trees and red oaks, they actually help create a sub-canopy microclimate, which helps cool the roots and reduce water consumption. In the case of Spanish oaks, the cedars actually do more good than harm with the cooling effect they provide to the roots. This effect is much more noticeable during extremely hot drought conditions, as the greenbelt trees are mostly thriving and the trees in low-irrigation partially cleared rocky slopes and ridge tops are burning up.

Cedars (ashe junipers) are different, physiologically, from hardwoods.  They do not heal over when a limb is removed.  Cedars have tannins in the wood, which reduce rot, repel insects and allow open wounds or large pruning cuts to remain open to the air without rotting, so the branch collars never close off the wound.  This is also why cedar wood chips are often used on flower beds and in landscapes to keep insects and weeds down.  Due to their specific physiology, dead wood removal with respect to cedars is considered more of an aesthetic practice than for beneficial health reasons.  Locally, fence posts, shingles and pickets (among other things) are often made of local cedar due to the availability and resistance to rot.

In the spring, everyone has experienced sneezing or severe allergies from the cedar pollen. Many people cut the cedars down on their properties in Austin area neighborhoods in hopes of reducing the cedar pollen in the air. The problem however, is that the high number of cedars in the greenbelts means removals around homes really make no difference at all to the pollen count. Hard to believe, but true.

People seem to either hate cedars or love them. They definitely get a bad rap locally with respect to their competition for water and how it can affect more valued trees in landscapes. This is mostly unwarranted within many landscapes due to sprinkler irrigation and amended soils. People should learn more about these remarkable native trees and how they fit into the local ecosystems.They hold together the slopes, grow where little else does and actually benefit other local native species in the greenbelts. They also make great building material!