The “Cedars” Are Dying! Why?
This, or some variant of it, seems to be a popular headline these days. Minus the quotation marks. I added the quotation marks simply because the shrubby trees everyone is so worried about that grow in this area are not technically cedars at all, they are species of juniper. Juniperus osteosperma, or Utah Juniper and Juniperus monosperma, or one-seed juniper. Both species are endemic to the Southwest and have been used for thousands of years for medicine and firewood. Local wood cutters often refer to both species as “shaggy bark junipers” due to their characteristic shredding bark, unlike the alligator junipers, Juniperus deppeana, which tend to grow in the more mountainous areas and have a chunky, alligator skin-looking bark. All three species can be found together in some areas.
All these species grow incredibly slowly and are very long-lived. Some have been dated at over 600 years! When you observe a 20-footer, you know you are looking at a tree that was here before the settlers came to this area. Generally, these trees add about a half inch of growth each year, so it’s possible that even a six-foot tree was here about the time the first cattle were introduced into the grasslands of our county. This brings us to the point of this blog.
If aerial photography was available a couple hundred years ago, we could compare photos of how things looked before the settlement of the American West. We can still catch a glimpse of it at ground level in some places such as a few miles west of Ash Fork where we see relatively large junipers growing along the washes with a few scattered smaller trees, surrounded by open grassland. It’s hard to believe, but this is what much of the area between Paulden and Ash Fork looked like historically. So, what happened?
Like many observable characteristics of the natural environment which have been altered by humans, we manipulated the ecology to the point where a normally controlled species took over. Within the past 150 years or so, a couple of major changes have happened. In the mid to late 1800s, we introduced cattle grazing to satisfy our craving for hamburgers and shortly thereafter, we started controlling wildfires to satisfy our need for safety, (and probably to protect our new pets, cattle). This had several effects which included a severe reduction in the size of American Pronghorn herds, elk, and other wildlife as well as the introduction of weedy species of plants which would be controlled naturally by fire. It turns out, grass is adapted to fire whereas trees and other species are not.
When natural fires started, usually by lightning, the grassland would burn until there was no more fuel. A few large junipers might survive, but most of the smaller trees would be burned. Weedy species would be cleared out and mostly just the grasses would remain. Along the drainages, not only was there more moisture in the ground for the trees to grow, but it could have been somewhat of a protector during a fire. As a result, the area remained mostly grassland which supported large numbers of wildlife herds. Pronghorn herds were in the hundreds; unlike the 2-3 dozen we see in groups today.
The subject of this blog post is “why” are these trees dying? Hopefully, you can understand why, but basically, they are out of resources. It has little, if anything, to do with climate change, etc. This would happen eventually, even if we were getting regular monsoon rains and good snowpack. They have just become so overcrowded there is not enough to go around. Why now? To the casual observer, it may seem like this is a sudden event. It’s actually been happening for a number of years already and it will continue until the ecology reaches a new balance. In the past, we used various methods to speed up this process.
Again, if we could go back in time with aerial photography, we might see ranchers with a huge chain stretched between two bulldozers raking the junipers out of the ground. Evidence of this “chaining” can still be seen in some areas. However controversial it was at the time, it was quite effective. Today we use bulldozers to push the trees over or we use a “masticator.” This is a skid steer machine with a large chipping contraption on the front which basically mows the trees down and chops up the wood. Again, quite effective, although not ecologically sound by any means. The process leaves large amounts of wood chips everywhere, usually in piles. These chips will take years to break down and keep much of the grass from being able to germinate and grow. It would be better to push the trees over and let woodcutters go in and make firewood to keep humans warm in winter. Incidentally, we use this method to reduce fuel loads in wildfire prone areas and leave a tremendous amount of fresh kindling on the ground. Huh?
Another effective method of juniper reduction and indeed, fuels reduction in general, is fire. No, no, I’m not advocating setting fires in these areas, but fire was very much a part of the ecology of the area before we interfered. Until a prize-winning scientist comes up with a fire analog, we are stuck with the real thing. Perhaps we should be focusing a little more effort on reducing loads in these areas where the junipers are so closely packed, we would never be able to get a wildfire under control; the conflagration would be unprecedented. One idea might be to bulldoze a wide swath around an area and then burn the part inside the perimeter; less bulldozing at least.
The point is, the junipers are not an introduced, non-native species, but are instead an opportunistic invader, much like the weeds in your garden. Sure, there are many weeds which were introduced and have recognizable names like, Siberian elm, Chinese tree-of-heaven, Russian thistle, and Scotch broom. There are almost as many native plants that seem to take advantage of us disturbing the ground just enough for them to take hold and then take over. Sometimes it’s us messing with some other aspect of the growing environment that allows an opportunistic native to take over. The junipers are in this category. It’s not that they don’t belong here, it’s that they have been allowed to take over. And now they are dying out as a result. I say good, but at the same time, a standing dead tree will ignite and burn much faster than a live tree. We should probably do something, sooner than later.
See you in the forest!
The HortiCoach