Tree Diseases and Insects

Bark Beetle Epidemic in Calaveras County

by

 

The bark beetles started their invasion when I used to live there, in Mark Twain’s famous Calaveras County. Now it looks like it has reached epidemic levels, requiring emergency action, from multiple agencies.

http://www.calaverasenterprise.com/news/article_fbc896b8-7d6f-11e9-94ea-7b4b381822a0.html

Even with recent wet winters, tree mortality will remain a pressing issue as long as bark beetle infestations and drought conditions continue, said Brady McElroy, a hazard tree specialist in the Calaveras Ranger District of the Stanislaus National Forest.

“By no means is the issue going away,” McElroy said. “What the Forest Service has to focus on are the high priority areas, the immediate hazards to homes, roads and highways.”

In the long-term, McElroy said the Forest Service hopes to increase the pace and scale of thinning projects to restore overstocked forests that have been allowed for by a century of fire suppression.

“Our forests are overstocked, which increases competition (and) stressors on the trees, (and consequently) their ability to defend against bark beetle,” McElroy said. “The ongoing goal is to thin forests to a healthy kind of pre-European settlement stand to where they’re a little more resilient. We’re focusing on high-priority areas in the wildland-urban interface … We know what happens when these overstocked forests catch fire – we lose them.”

Diana Fredlund, a public affairs officer with the Stanislaus National Forest, said that although federal budget decreases have impacted the scale of the work for the Forest Service, the agency has been able to collaborate with private, county, state and other federal agencies and contractors for tree removal projects.

“We do what we can with what we have,” Fredlund said.

The Forest Service offers its own tree mortality program for homeowners with properties adjacent to Forest Service land. Property owners can fill out a Hazard Tree Evaluation Request Form to be considered for hazard tree abatement.

New Study About Forests Impacted by Extreme Mortality

by

http://academic.oup.com/bioscience/advance-article/doi/10.1093/biosci/bix146/4797261

 

Massive tree mortality has occurred rapidly in frequent-fire-adapted forests of the Sierra Nevada, California. This mortality is a product of acute drought compounded by the long-established removal of a key ecosystem process: frequent, low- to moderate-intensity fire. The recent tree mortality has many implications for the future of these forests and the ecological goods and services they provide to society. Future wildfire hazard following this mortality can be generally characterized by decreased crown fire potential and increased surface fire intensity in the short to intermediate term. The scale of present tree mortality is so large that greater potential for “mass fire” exists in the coming decades, driven by the amount and continuity of dry, combustible, large woody material that could produce large, severe fires. For long-term adaptation to climate change, we highlight the importance of moving beyond triage of dead and dying trees to making “green” (live) forests more resilient.

Massive Crater Lake Wilderness Area Fantasy

by

Oregon Wild has proposed a massive half million acre Wilderness Area, partly to “protect” Crater Lake. The Klamath County Commissioners are saying no, with fears that summer fires would affect public health, and that those unhealthy forests need active management.

P9159024_tonemapped-web

Here is a map of what Oregon Wild wants done.

More Rim Fire Pictures

by

All too often, once a firestorm goes cold, a fickle public thinks the disaster is over with, as the skies clear of smoke. In the situation of the Rim Fire, the public hasn’t had much chance to see the real damages within the fire’s perimeter. All back roads have been closed since the fire was ignited. Besides Highway 120, only Evergreen Road has been opened to the public, within the Stanislaus National Forest.

From my April trip to Yosemite, and Evergreen Road, this unthinned stand burned pretty hot. This would have been a good one where merchantable logs could be traded for small tree removal and biomass. Notice the lack of organic matter in the soil.

P9202313-web

Sometimes people say there is no proof that thinning mitigates fire behavior. It’s pretty clear to me that this stand was too dense and primed for a devastating crown fire. I’m guessing that its proximity to Yosemite National Park and Camp Mather, as well as the views from Evergreen Road have made this area into a “Park buffer”. Now, it becomes a “scenic burn zone”, for at least the next few decades.

P9202306-web

There is some private land along Evergreen Road, which seem to have done OK, at least in this view. Those mountains are within Yosemite National Park. Sadly, the media likes to talk about “reduced burn intensities, due to different management techniques”, within Yosemite National Park. Only a very tiny percentage of the National Park lands within the Rim Fire have had ANY kind of management. Much of the southeastern boundary of the fire butts up against the Big Meadow Fire, generally along the Tioga Pass Road (Highway 120). Additionally, much of the burned Yosemite lands are higher in elevation, as well as having larger trees with thicker bark. You can also see that there will be no lack of snags for the blackbacked woodpecker. Can anyone say, with scientific sincerity, that over-providing six years of BBW habitat will result in a significant bump in birds populations? The question is really a moot point, since the Yosemite acreage, alone, does just that.

P9202301-web

People have, and will continue to compare the Yosemite portion of the Rim Fire to the Stanislaus National Forest portion, pointing at management techniques and burn intensities. IMHO, very little of those comparisons are really valid. Apples versus oranges. Most of the Forest Service portion of the fire is re-burn, and there is no valid Yosemite comparison (other than the 2007 Big Meadow Fire). It has been a few months since I have been up there, and I expect that there are plenty of bark beetles flying, and the trees around here have no defense against them, with this persistent drought. Everything is in motion and “whatever happens” is happening.

Aspen Decline PNAS Study

by

Dying aspen on Mancos-Dolores Ranger District, San Juan National Forest in 2006. Photo by Phil Kemp, US Forest Service, Mancos-Dolores District.

There have been many stories about this but this one I could find easily:

Drought May Be Causing Aspen Tree Die-Off
Trees Developing Embolisms, Researchers Say
Deb Stanley, 7NEWS Producer

DENVER — A mysterious malady has killed off nearly one-fifth of Colorado’s aspens. But forest ecologists have struggled to explain the widespread die-off, known as Sudden Aspen Decline.

The Aspen Daily News reports that a new study from researchers at Stanford University and the University of Utah may provide a breakthrough in understanding the decline and how it kills trees.

The research found that aspens have essentially dehydrated due to a drought that took hold of Colorado from 2000 to 2004. In a delayed reaction to the drought, the systems that carry water through aspen stands broke down.

“If they can’t transport water, they’re kind of screwed,” said Duncan Smith of the University of Utah, who worked on Anderegg’s project and co-authored a paper on it released this month in the Proceedings of the National Academy of Sciences

Researchers pruned dying aspens and studied them in the lab, and listened to their inner workings with microphones as they died.

“Just as there are a number of ways people can die and you can’t always pinpoint it, it’s the same with trees,” said Stanford Ph.D. candidate William Anderegg, who led the research.

Researchers found that in response to drought, the trees were developing embolisms — much like common human blood vessel blockages — which hampered their ability to move water.

In trees affected by the decline, an average of 70 percent of the vascular system was blocked. That’s up from an average of 17 percent in healthy aspens. The trees, researchers found, fought against dehydration for a few years after the drought but lost and eventually died.

The researchers concluded that drought caused widespread failure of water transport systems in the trees.

Their conclusion is a foreboding sign for Aspen’s signature trees in the age of global warming.

Anderegg’s team studied climate records in 51 different aspen-filled areas in Western Colorado from 1900 to 2009. The period from 2000 to 2004 marked the most severe drought in the entire period.

“For aspens, hot temperatures tend to be really stressful,” Anderegg said. “Climate change and global warming will be a real problem for aspen trees anywhere.”

Here’s a link to the article.

My favorite quote is in the text

Physiological mechanisms provide a foundation to understand, predict, and model threshold events that may dominate certain ecosystem responses to climate change and allows us to better project the uncertain future of forest ecosystems in a warming climate. Although more research is needed to better incorporate drought-induced vegetation mortality into models, our results provide insight into the processes that occur during drought stress.

In fact, I have always said that if you want to model how organisms will respond to the environment, it’s good to understand their physiology and genetics. To project the future of ecosystems, though, seems like you would have to know the physiology and genetics of lots of species, and their interactions… which are good to know anyway.

More info on SAD can be found on the Aspen Delineation webpage here.