Drought: Dry years are not entirely at fault for tree death
(Editors note: Based on the weather this winter, if things don't change, the local area will be experiencing a drought. This is the fifth in a series of articles examining droughts, water use, water storage/sources, personal water footprints and what the impacts of a prolonged drought has done in the past and can do to the eastern Utah in the future).
"I like trees because they seem more resigned to the way they have to live than other things do."
It is a sad sight.
Stands of trees with many of them dead. What caused this? Drought? Pestilence? Insects?
It doesn't matter where you look in the two national forests that surround Carbon County, whether it be the Manti-La Sal or the Ashley, there are a lot of dead trees now. More than anyone ever remembers.
Climb on a four wheeler and drive Skyline Drive. At one point miles south of the entrance to Skyline from Highway 31 is Black's Canyon. It's namesake may have passed into history, but today its name fits its color from a distance. Dead trees still standing, some of them fire scorched by wild fires that burned only a few years ago. In other places the unburned dead outnumber the living, particularly among certain kinds of conifers. The same is true in Huntington Canyon and it's true at the summit of Willow Creek/Indian Canyon.
Most people suppose it was the drought that did it. But which drought? There have been a number of drought cycles on the clock in the last four decades. There have also been many wet years as well. At one time or another a very wet year could be followed by a very dry one. Usually the cycles come and go over a period of years however.
The National Forest Service and the Utah Division of Natural Resources came out with a report in 2010 that spelled out some of what is going on with the forests in the state. The report called Utah Insect and Forest Disease Conditions was broken basically into three parts: (1)The role of insects in problems in the forest; (2) The role of disease in the forest's health and: (3) The role of decline and abiotic (non-living and natural) damage in the forests.
While drought has helped some of these forces along, it has not been the complete problem with why it seems many trees are dying. The information that is often spread amongst locals is that the drought had weakened the trees and that the bark beetles have destroyed them. This is true to an extent, but it is also important to note that there are many kinds of other insects that affect the forest. Those include needle insects like the Pinon Needle Scale. The beetles can have an effect include native bark beetles like the Fir Engraver Beetle, Mountain Pine Beetle, Douglas-fir Beetle, Spruce Beetle, Pinon Engraver Beetle, Western Pine Beetle and Roundheaded Pine Beetle. There are also some non-native insects such as the European Gypsy Moth and Banded Elm Bark Beetle. Not all of these insects are at present active in the state or the local area, but all are a threat.
Disease can also cause huge problems. Stems and branches can be affected by Dwarf Mistletoes, Pinon Blister Rust and White Pine Blister Rust. Roots can be hurt by Annosum Root Disease, Armillara Root Disease, Black Stain Root Disease.
The abiotic damage includes such things as windstorms, frost damage, landslides and avalanches and this is also where drought is included.
The report pointed out that there are four kinds of beetles that can affect the forests in the area (Ashley-Unitah and Manti La Sal). Much of the state was surveyed, but not all of it. Within Carbon County it was determined in the report that 90 trees and 39 acres were killed by the Douglas-fir Beetle, that 170 trees and 85 acres were killed by the Fir Engraver Beetle.
But the watershed for Carbon extends well into other counties which had different and in some cases more problems. Much of the areas watershed lays in Wasatch and Sanpete counties along with some from Duchesne County. In Duchesne the Mountain Pine Beetle killed 122,930 trees on 40,314 acres. Some of that happened in the northern part of the county but the Reservation Ridge/White River area got some of that ill as well. The Douglas-fir Beetle and Spruce Beetle did less damage. Wasatch County also accumulated damage from those same insects. Sanpete County's damage ran much along the same lines as Carbon County.
What most people see when they look at the forest is the dead pine, fir and spruce trees. Most consider the Aspens to be doing just fine. But that isn't necessarily the case. Aspens have also suffered at the hands of drought along with diseases and borers. Aspens live best in deep soil while conifers live well in shallow soil. Many of the public have heard that forest officials are in fear of Aspens taking over the forests as conifers die. However there is a real concern that conifers (which are invasive) can move into Aspen groves and take those areas over by basically draining all the moisture away with their thirsty roots. In addition Aspens are threatened by the Forest Tent Caterpillar, which also likes deciduous trees and shrubs as well. Another threat to that organism is Aspen Leaf Spot disease which defoliates the trees and is a likely factor in Aspen decline in the forest.
The increased death of trees has happened over a long period of time. In that time there were years when the precipitation was normal, and other years, like in the winter of 2010-11 when it was way above normal. But in some periods in the last few decades, some of those years were strung together by one thing, the lack of enough moisture. All flora in the forests have suffered to some extent from this.
So drought isn't necessarily the cause of all the death that has been taking place amongst trees nor is it often the main cause in the mountainous areas.
But it has definitely been a contributing factor over the years.