Prediction tool shows how forest thinning may increase Sierra Nevada snowpack

University of Nevada, Reno researchers design water quantity tool to help with forest-thinning plans

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IMAGE: University of Nevada, Reno students perform maintenance on data-collection equipment to help with projects to maintain the Sierra Nevada forest. view more  Credit: Photo by Adrian Harpold, University of Nevada, Reno.

RENO, Nev. – The forest of the Sierra Nevada mountains is an important resource for the surrounding communities in Nevada and California. Thinning the forest by removing trees by hand or using heavy machinery is one of the few tools available to manage forests. However, finding the best way to thin forests by removing select trees to maximize the forest’s benefits for water quantity, water quality, wildfire risk and wildlife habitat remains a challenge for resource managers. The U.S. Forest Service is leading an effort to balance all these challenges in landscape-scale forest restoration planning as part of the Lake Tahoe West Restoration Partnership.

As part of this effort, University of Nevada, Reno’s Adrian Harpold recently led a team in developing a modeling tool to focus on the issue of water quantity. The tool predicts how different approaches to thinning the forest impact snowpack accumulation in Lake Tahoe, which controls how much water is available for downstream communities such as Reno.

“The snowpack we’ve relied upon is under pressure from years of fire suppression that increased tree density, combined with the effects of climate change and warming temperatures,” Harpold, natural resources & environmental science assistant professor with the College of Agriculture, Biotechnology & Natural Resources, said.

He explained that too many trees means less snow reaches the ground. In addition, when many trees are clumped together, they warm up and release heat, which can melt the snow on the ground. However, too few trees means the snowpack is less protected from the sun and wind, which also melt snow.

The tool, developed with funding from the College’s Experiment Station and the U.S. Forest Service, was built to specifically model the west shore of Lake Tahoe, which the team felt was a good sample of the Sierra Nevada forest. The team initially created a small-scale high-resolution model using data collected with 3D laser scanners, called “LiDAR.”

“The LiDAR data lets us see individual trees, which we use to ‘virtually thin’ the forest by taking trees out of the model,” he said. “As such, it lets us create a thinning experiment that’s realistic. We can then represent different management actions, such as removing trees below certain heights.”

His team, including the post-doctoral scholar Sebastian Krogh, graduate student Devon Eckberg, undergraduate students Makenzie Kohler and Gary Sterle, the College’s Associate Professor of Remote Sensing Jonathan Greenberg and University of Arizona’s Patrick Broxton, tested the model’s accuracy by conducting thinning experiments and comparing the predictions to measurements in the real forest. Results were discussed in a recently published article on the proof-of-concept for using high-resolution modeling to predict the effect of forest thinning for snow, for which Harpold was the lead author.

Once the team determined the model was working correctly, they increased the model size to represent Lake Tahoe’s western shore. Results are discussed in another recently published article on using the model to predict the effects of forest thinning on the northern Sierra Nevada snowpack, led by Krogh with Harpold, Broxton and the Forest Service’s Patricia Manley as co-authors. Their experiments showed that overall, more trees removed means more snow maintained. However, there are beneficial ways and detrimental ways to remove trees. The method that appeared to be most effective was removing dense trees that had many leaves and branches and were shorter than about 50 feet, leaving behind taller trees. There were also differences in effectiveness depending on the elevation, the slope and the direction the slope was facing.

Harpold plans to continue expanding the model, testing to see if it will work for Lake Tahoe’s eastern shore and in the American River Basin, with the ultimate goal of providing a tool for Forest Service decision-makers and others to inform their forest-thinning plans.

The water-quantity tool is one of many different modeling tools being developed with funding from the Forest Service as part of the Tahoe-Central Sierra Initiative, which aims to quickly restore the forest to improve the health and resilience of Sierra Nevada mountains and maximize the benefits that the forest provides.

“My decision-support tool for water quantity would be a smaller piece in a larger toolkit to help determine how and where to thin the forests,” Harpold said.

Other tools being designed to predict forest-thinning impacts include a tool to predict impact on wildfire spread, a tool to predict impact on smoke, a tool to predict impact on endangered and threatened species, a tool to predict sediment flow into Lake Tahoe and a tool to predict economic impact.


For more information on the water-quantity tool, see: “Increasing the efficacy of forest thinning for snow using high-resolution modeling: A proof of concept in the Lake Tahoe Basin, California, USA” in the journal Ecohydrology, and “Using Process Based Snow Modeling and Lidar to Predict the Effects of Forest Thinning on the Northern Sierra Nevada Snowpack” in the journal Frontiers in Forests and Global Change. For more information on the larger forest-thinning project, visit the Lake Tahoe West Restoration Partnership or Tahoe-Central Sierra Initiative websites.

From EurekAlert!

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May 9, 2020 2:33 am

Unlike Kilimanjaro?

Reply to  lee
May 9, 2020 8:57 am

For Kilimanjaro, the moisture was coming from the forests. Cutting down the forests reduced the amount of moisture available.
For the Sierras, most of the moisture is coming from the Pacific. Cutting down the trees doesn’t impact how much falls, but it does impact how long it takes to melt in the spring.

Reply to  lee
May 9, 2020 8:54 pm

There’s a meme in play here which is invalid – that Sierra Nevada snowpacks have dwindled recently due to global warming. Not true, and easily refuted by government data.

May 9, 2020 2:38 am

They have so many tools being designed that they’ll be reclassified as a hardware store if they aren’t careful.

But how unusual, they actually compared their model with observations to see if it was working properly. Whatever next, climate “scientists” actually debating whether their models are good enough?

Take care everyone and practice safe cooking – always use condiments, particularly when parboiling pangolins..

Reply to  Oldseadog
May 9, 2020 7:42 am

The whole concept does not make sense. Do trees somehow prevent snow from falling? Sure they affect how it thaws – but how does it impact the “water quantity”?

Reply to  Curious George
May 9, 2020 8:59 am

The slower the snow melts, the more of it soaks into the ground and evaporates, making less available as run-off.

Reply to  MarkW
May 9, 2020 9:18 am

Are you arguing for more trees? (So would I).

Ron Long
May 9, 2020 3:05 am

Interesting story, maybe even adds to the managing snowpack capability, but I can’t imagine the Kalifornia side of Lake Tahoe “thinning” (brutally murdering our brothers and sisters the trees!) any trees. Wait and see on this one. Stay sane and safe.

Reply to  Ron Long
May 9, 2020 8:52 pm

You might be surprised. Wildfire have spooked many Kalifornians who in forests. WRT Tahoe, there have been many homes on the Kalifornia side lost to fires in recent years due to strict local ordinances against removing trees from private property, and subsequent lawsuits.

M Courtney
May 9, 2020 3:21 am

tested the model’s accuracy by conducting thinning experiments and comparing the predictions to measurements in the real forest

Now that’s how models should be used in science.
A means of comparing our understanding with reality.

Such a pleasant change from the usual climate science where the “understanding” is assumed to be correct and reality ignored until (or if) it ever complies.

Reply to  M Courtney
May 9, 2020 5:21 am

Oh come on!

climate models are being compared
wuwt has enough articles showing poor comparison with real life if they stop the comparison at 2015

When new climate models are generated there will be so many complaints here about fudging the data to fit life it will crash servers.

Just how accurate are the no-global-warming models?

Reply to  ghalfrunt
May 9, 2020 5:47 am

If I recall correctly, the Russian model, with low sensitivity to CO2 is the most accurate. We’re not talking “no-global-warming”, just normal global warming, i.e., not dangerous so sit back and enjoy it.

Oops, can’t eliminate the entire climate alarmism industry. What would all those academics, government employees, UN hacks, environmental groups, weather and subsidy dependent electricity providers, Al Gore, Greta, et. al., do for a living?

Reply to  BobM
May 9, 2020 1:35 pm

If I’m not mistaken, the “warming” predicted in that model, which turned out to be the only accurate model, is so small that it could have been just natural variation, right?

Reply to  ghalfrunt
May 9, 2020 5:53 am

Comparison should not mean adjusting inconvenient data. It should not mean confinement to periods that only agree with models.

M Courtney
Reply to  ghalfrunt
May 9, 2020 6:54 am

You should read up on the science before making unjustified statements.

Here is how the IPCC fails to compare models with reality. (Page 894 WG1AR5)

The timing of these residual temperature fluctuations is unpredictable, representing an inescapable source of uncertainty. We can quantify this uncertainty by asking how the gradients of the best-fit surface might vary if El Niño events, for example, had occurred in different years in the observed temperature record. To do this, we repeat the analysis in panel (c), replacing observed temperatures with samples of simulated internal climate variability from control runs of coupled climate models. Grey diamonds in panel (d) show the results: these gradients cluster around zero, because control runs have no anthropogenic or natural forcing, but there is still some scatter. Assuming that internal variability in global temperature simply adds to the response to external forcing, this scatter provides an estimate of uncertainty in the gradients, or scaling factors, required to reproduce the observations, shown by the red cross and ellipse.

But the natural forcing’s are unknown.
Seeing as the climate is an integral of weather and weather is chaotic the natural forcings cannot be known. Butterfly wings do not usually cause hurricanes. Yet sometimes they do.

So they are not comparing against reality; they are comparing against assumed reality.
Which is not the same thing at all.

Finally you ask “Just how accurate are the no-global-warming models?”
And the answer is “Not accurate enough to make policy based on them same as every other climate model”.
Adaptation is the only scientific approach. Which means forgetting about AGW and focussing on reducing poverty.

Reply to  M Courtney
May 9, 2020 7:18 am

how do you adapt 150 year old housing to floods (heat>evaporation>increased rain storms)
How do you adapt coastlines to higher sea levels. How do you adapt flood defences on tidal rivers to higher levels? Normal and then emergency flood defences were over topped in uk this winter.

How do you adapt peoples minds to accept refugees who no longer can grow crops?

Reply to  ghalfrunt
May 9, 2020 9:05 am

There have always been floods, there is no evidence that floods are increasing or getting worse. That’s another “projection” from your models that have been shown to be false.

We have several hundred years to adapt to rising seas, assuming the seas keep rising.

Reply to  ghalfrunt
May 9, 2020 1:38 pm

Why don’t you stop lying about why refugees are refugees?

Reply to  ghalfrunt
May 9, 2020 11:38 pm

Seas have been rising a few mm per year for 150 years. Look at any sea level gauge’s graphic – no acceleration. Slow, steady rise for 8 human generations.

Reply to  M Courtney
May 9, 2020 7:20 am

How does reducing poverty adapt to flooding in uk. How does reducing poverty stop sea level rise?

Pat from kerbob
Reply to  ghalfrunt
May 9, 2020 8:47 am

All the data shows sea level rise is small and continuous and will be many lifetimes until people will actually notice it.
If still not sure why not ask Bill Gates, Obama and the long list of super rich buying seaside properties, they seem to have the answer

Reply to  ghalfrunt
May 9, 2020 9:06 am

Once again the socialist indicates that he places no importance on reducing poverty.
Regardless, reducing poverty gives people the resources to handle whatever happens.

Reply to  ghalfrunt
May 9, 2020 10:25 am

The flooding in the UK is primarily a result of EU policy that restricts dredging of drainage canals and rivers.

Reducing poverty allows adaptation to changes in climate. It also allows the adaptation of currently non-arable land to arable land, such as the building of dikes and the drainage ditches and canals to put wetlands under cultivation, or building irrigation projects to water arid areas.

Reducing poverty allows adaptation to live in climates not conducive to human habitation, whether too hot or too cold, too wet or too dry.

Reducing poverty allows the efficient production, harvest, storage, processing and distribution of food worldwide.

Reducing poverty allows the development, manufacture and distribution of treatments and vaccines against deadly and debilitating disease.

Reducing poverty allows time and resources for education.

Reducing poverty unleashes humanity’s innate ingenuity and ability to adapt.

Reducing poverty generally reduces birthrates — not always a good thing.

Al Miller
Reply to  ghalfrunt
May 9, 2020 4:16 pm

How can your eyes be opened to see that EVERY single prediction made about warming has proven to be incorrect? You’re still spouting the alarmists industry talking points which are again demonstrably false. Grow up and find a real cause to care about. There are many of them- unless you have a financial interest in useless wind farms or some other Ponzi scheme? In which case why don’t you try being honest?

Robert of Ottawa
Reply to  ghalfrunt
May 9, 2020 8:04 am

I don’t need a no-global-warming model as we have actual reality; no need of a model. The Warmistas should try study that for a couple of hunded years before returning to their models.

Reply to  ghalfrunt
May 9, 2020 9:03 am

Looks like gfront has had his feelings hurt again.
Yes, we compare the output of models to reality. I just wish the people who wrote the models would do the same. They are still claiming that their models work.

Once again gfront tries to pretend that in order to refute his models, we have to create a better one.
That’s not how science works. All we have to do to prove that your models don’t work, is show that they don’t work. Which as you admit, has been done.

May 9, 2020 3:34 am

My first job many years ago involved planting trees in the Sierra Nevada mountains in areas that had been burned off from fires the season before. Later, I went to the University of Nevada at Reno and graduated with a B.S. in range and wildlife management. In those days, the mantra for management was known as “multiple use,” which aimed to make the most use of the environment by humans and wildlife, rather than today’s policy of just total conservation without regard to human use. The tools we used and advocated for included prescribed burning and clearing out overgrown forest areas by clear-cutting and other ways of reducing the fuel for fires in the summer. This article is a great example of another benefit of some kind of multiple use policy that should be used again.

Reply to  D.T. Osborn
May 9, 2020 6:07 am

People seem to be in love with snowpack. The total precipitation doesn’t change. All that changes is the timing of when the snow melts and water comes rushing down the mountains.

Reply to  commieBob
May 9, 2020 7:29 am

As you say, snowpack affects timing of water release. We like to have water year round in Colorado and snowpack acts as a natural reservoir. So, it’s very important for sustaining our lifestyles.

We also like to ski and snowpack is important to that normally, except this year when snow was fantastic but in early March all resorts were closed by government edict.

Reply to  commieBob
May 9, 2020 9:07 am

How much water comes rushing down over a particular period of time is very important.
It’s the difference between a normal year and a flood.

Reply to  commieBob
May 9, 2020 10:43 am

True but in CA the reservoirs are kept at a certain level during winter to help prevent flooding from severe events, which occur. There’s no concern about that for a good 5 month so that’s when I higher snow pack helps.

Reply to  D.T. Osborn
May 9, 2020 2:53 pm

I live on the East Shore of LT. The incredible growth of Reno, and ever greater use by Bay Areans thanks to AirBNB/VRBO, has dramatically increased recreational use of the area. It’s hardly a wilderness anymore; more like a state park adjacent to a major urban area. BTW, the most destructive users are surely the battalions of mountain bikers.

Bill Burrows
May 9, 2020 3:50 am

In my part of the world (northern Australia) more trees means less pasture and less rainfall run-off (snow is not an issue!). So to maximise intake into farm dams landowners usually remove most of the woody plants from the dam catchment area to optimise their water supplies from such sources.
Thinning trees in forest communities (to enhance useful timber yield) adds little to rainfall run-off, as trees retained after ‘thinning’ grow much faster because now there is less competition for soil nutrients and soil moisture. So if extra rainfall run-off is the primary objective trees retained after thinning should be separated by a radius equivalent to twice the height of the tallest tree in the stand. This reflects the fact that for Australian eucalypts (in my example) root systems can extend for this distance in the soil away from the base of the tree. Different tree species on different continents may behave differently – but not by much?
Altering the structure of forests is a good way of achieving the multiple objectives modern societies seek to impose on their management. More research needs to be undertaken into the pros and cons of retaining trees in intact strips and clumps, with remaining areas left with few trees covering the landscape. Such structures can enhance rainfall run-off, reduce catastrophic fire risks, maintain reasonable timber production and enhance flora and fauna diversity. In my patch it can also enhance the productivity of domestic livestock with a more balanced use of our native woodland ecosystems.

Gary Pearse
May 9, 2020 4:29 am

I’m sure they considered the problem of the weather variable. The model basically needs to be tested for 20 to 30 years along with adjacent control areas. A permanent station would allow experiments on sub-areas to improve the model and discover other factors that might be important. Gee, maybe climate models … nah they have already had 40 years, they must be as good as they can get.

I note they mention the thickening of growth due to climate change and temperature which is a redundancy. This is probably as close as they want to get to naming carbon dioxide as a factor in vigorous plant growth.

Tim Gorman
May 9, 2020 4:58 am

Freeman Dyson criticized climate models for not being holitic. The same criticism could be leveled here. A model based solely on increasing snowpack leaves a lot of holes that aren’t being considered. Will the thinning solution cause increased brush growth because of less shadeing (i.e. fuel for fires). Will the thinning solution cause increased erosioon from rainfall directly impinging on the soil instead of being slowed down by the tree foilige? What impact will the thinning solution have on the growth of the trees that are left?

Models that focus intently on one single thing makes the modlers blind to the overall environment – thus the models themselves become blind to the entire environment as a whole.

I just have to wonder how many unintended consequences the model based solely on increasing snowpack will have as time goes on.

Reply to  Tim Gorman
May 9, 2020 9:11 am

Are you arguing that unless a model covers every possible thing, then we shouldn’t have models?

Joseph Zorzin
Reply to  MarkW
May 10, 2020 10:12 am

It’s OK to have models that don’t cover every thing because none do- but it’s not OK to base hugely important policies on those models.

Tim Gorman
Reply to  MarkW
May 11, 2020 3:23 pm

Joseph answered pretty well.

Would you believe a model for a race car that focused *only* on car weight? You’d probably wind up with a model that suggests a car with no body or engine would go around the track the fastest!

Would you believe a model for a transformer that only focused on the weight of the core and not the permeability of the core material or its saturation point?

Models have to at least *try* to account for all the confounding variables that contribute to the final result or they are useless.

The model being discussed *is* pretty much useless if it doesn’t focus at least on the factors I mentioned. There are probably lots of others I didn’t think of.

May 9, 2020 5:01 am

Once the team determined the model was working correctly, they increased the model size to represent Lake Tahoe’s western shore.

And how did they determine the model was working correctly? Unimportant. Move along.

Reply to  Gary
May 9, 2020 7:13 am

Well, to be fair they say they compared predictions with measurements.

May 9, 2020 5:24 am

So with trees you get runoff little by little, without them you get it all at once in the spring, right?

Rick C PE
Reply to  pochas94
May 9, 2020 9:07 am

As I understand it, evergreen trees collect a significant proportion of snow falls on their branches. This spreads the snow surface over a much greater area and results in more snow sublimating instead of melting. Hence reducing trees results in more snow piling up on the ground, compacting and then taking longer to melt when it warms up.

Reply to  Rick C PE
May 9, 2020 10:48 am

It’s common sense. After a storm the trees are covered, but when the weather clears it disappears off the trees rapidly but can stay in the ground well into warm spring and summer days. A lot of that snow doesn’t melt off the trees though, it falls as snow and ice. I’m skeptical but if it encourages thinning, I’m all for it.

Reply to  pochas94
May 9, 2020 12:02 pm

Where I live trees act like solar collectors thermalizing the sun’s heat and radiating it downward as infrared, melting the snow beneath. The snow is gone beneath the trees before it is gone in the open fields. On skiing trips in the Rockies I remember seeing pine trees that had melted a pit below them in four feet of snow. But if the amount of precipitation is the same the trees will affect when it runs off, not the total amount of runoff.

Reply to  pochas94
May 9, 2020 1:09 pm

Where do you live? Where I live, snow lasts longer in forests.

Reply to  Curious George
May 9, 2020 3:23 pm

In my experience pochas94 is right. Hitting trails in the Cascades during spring we’ll be busting snow drifts in the meadows/openings while it’s clear under the trees. In heavy snow years we might still be busting snow drifts into July. Then look at all the mountains above the tree line, yep I see fields of snow.

May 9, 2020 5:45 am

Melbourne’s water catchment is almost entirely national park, crown land managed by Melbourne Water in conjunction with the parks department (DEWLP) or wholly-owned by MW.

Almost all of that is heavily forested (such as mountain ash eucalypt). Less than a quarter of one per cent is logged.

I don’t know the rate of prescribed burning conducted on this land as our Socialist Left faction Premier is not one to meet the set targets or even to have a debate regarding the sufficiency of such targets, the latter requiring more publicly-available information than the premier is comfortable with. Nor is fire-fighting access as good as it should be.

In short, the water catchment sits and waits to be razed to the ground, after which runoff surely increases for a while along with impurities such as soil and ash. As trees regrow, runoff must decrease. Old-growth forest will take decades, yet it is their desired setting.

The immediate catchment management policies appear, therefore, to be questionable. Given the deep green streak of environmentalism that pervades most of the Victorian media, such questions are not likely to be adequately put, however.

randy julander
May 9, 2020 6:41 am

great study by an excellent researcher i know personally. taking what is known by many studies – vegetation impacts snow catch and creating a tool/model that can perhaps predict a future state. this model might be useful. particularly when there is so much focus on the disappearing snowpacks due to ‘climate change’ … and a multiplicity of other factors, chief among them, vegetation change in density and composition. it is a well documented phenom that going from an open meadow to aspen will result in a decrease in snow accumulation, up to 25% and going from aspen to conifer will result in another substantial decrease in snow accumulation, up to 40%. smokey bear is the reason for the greatest landscape scale change in western vegetation and hence ecosystems over the past 60 years. the colorado basin has lost 2.5 million acres of aspen land to conifer encroachment. aspens (ryel et al) have about 40% more potential water/runoff than do conifers stands when comparing both snow accumulation and soil moisture. julander and clayton showed that up to 99% of all runoff in the intermountain west is snowmelt in origin. summer precipitation is basically completely consumed by vegetation and accounts for minimal runoff – so yes, snowpack is king. predicting impacts from vegetation change is huge and can be an important tool in showing many misguided environmentalists that appropriate logging is essential to watershed health.

Reply to  randy julander
May 9, 2020 7:44 am

Wait… There’s a correlation between snowmelt and runoff????

Moderately Cross of East Anglia
May 9, 2020 9:04 am

Is this snow that is alleged not to be reaching the ground anymore because of very big naughty trees theoretical snow or the real stuff that we don’t have any more?

Ed Zuiderwijk
May 9, 2020 11:09 am

Wasn’t ‘forest thinning’ the cause of the disappearing snows on Kilimanjaro?

Reply to  Ed Zuiderwijk
May 10, 2020 2:07 am

You have to consider the gradient. To thin properly means to make less dense such as thinning fruit from orchard trees during early growth to promote fewer but larger and healthier fruit with a greater overall harvest.
Thinning a forest is not clear cutting.

Joseph Zorzin
Reply to  AndyHce
May 10, 2020 10:05 am


May 9, 2020 12:42 pm

Further reading on forests and rainfall:

Do forests drive wind and bring rain? Is there a major man-made climate driver the models miss?

Land clearing caused drop in rainfall in South West of Australia

Bill Parsons
May 9, 2020 3:07 pm

Tim Gorman,

I second your question about unintended consequences. Seems like this research is all about increasing runoff without much consideration for anything else. Forests preserve snowpack so that the meltwater is dispersed more slowly and evenly over the hot days of summer. In doing so, soil erosion is kept to a minimum and mountain run-off is purified through subsoil root systems. Faster runoff equals more pollution and erosion.

The water-quantity tool is one of many different modeling tools being developed with funding from the Forest Service as part of the Tahoe-Central Sierra Initiative, which aims to quickly restore the forest to improve the health and resilience of Sierra Nevada mountains and maximize the benefits that the forest provides.

This kind of euphemistic double-speak sounds all too familiar for those who want to “restore” our air by ridding it of CO2. What aspect of the Tahoe-Sierra forests needs “restoration”? Also, the proposal above appears to be targeting healthy, living trees rather than thinning and culling combustible dead timber with the (apparently forgotten) goal of reducing forest fires.

To summarize: harvesting live healthy trees could well create faster run-off, but it would also result in soil erosion, reduce the steady supply of clean water throughout the hottest days of summer when those hot, dry hillsides of the Sierras need all the ground moisture they can to help mitigate wildfires.

This idea might serve the water-hungry mega industries, including Tesla’s lithium ion battery plant, which are spreading across the deserts east of Reno. From what I read, they are dependent upon the Truckee River water. But the plan doesn’t seem too healthy for most people downstream.

Reply to  Bill Parsons
May 10, 2020 2:19 am

I’ve seen areas in the Sierra Nevada where new trees are coming up looking like grass there are so many per square foot. While many of those could not possibly survive, I’ve seen many places where larger twisted stunted trees are growing so close together it is impossible to get through. None can grow well or very large.

I’ve been in maintained areas that are almost like a park. Each tree has growing room, there are many large, straight trees. Shrubbery is in clumps here and there but walking through the forest doesn’t even require a path; there is always plenty of room to continue forward.

Mike Dubrasich
May 9, 2020 8:50 pm

I have managed watershed properties in the PNW. We practice thinning-from-below, which means removing small trees and leaving dominant and co-dominant trees at wide (2 crown width) spacings. We call that “restoration forestry” because we attempt to restore pre-Contact conditions: widely-spaced open and park-like stands maintained by historical indigenous (anthropogenic) fires.

This type of management decreases sublimation (snow evaporation off crowns) and increases deep percolation (charging aquifers and increasing summer flows).

Restoration forestry also reduces the fire hazard by removing ground and ladder fuels and decreasing the chance of crown-to-crown fire spread. Fires when they occur will go to ground rather than crown across tracts. We also pile and burn small thinned material and occasionally (rarely) do some broadcast burning as well. We also create fire breaks with road access to help in fire fighting if and when fires happen.

Restoration involves selecting as leave trees the larger (older) trees with thicker bark that are less likely to die in ground fires.

Preventing 100% mortality fires is essential in watershed tracts. Severe fires alter water chemistry (ash increases pH) and seal soils (which leads to increased erosion) in post-fire precipitation events. Severely burned tracts tend to have rapid runoff events with erosion that can cause damaging flash floods downstream.

The art of selecting leave trees is more than following a prescriptive model, however. It requires on-the-ground expert judgement that takes into account (at a minimum) engineering, economics, esthetics, wildlife ecology, and ethno-botany as well as hydrology. Two seasoned experts can disagree over tree selection as they mark the stand — and those debates can be very educational for novice observers.

The Reno students are on the right track. Hopefully they will graduate and get real forest management jobs where their skills can be honed in real forests with expert guidance. When the full responsibility for stewardship is on their shoulders, they will have the education, training, and experience to make wise decisions.

Joseph Zorzin
Reply to  Mike Dubrasich
May 10, 2020 10:02 am

Good to see another forester here. In Massachusetts, climate alarmists are trying very hard to stop all forestry saying it’s a major cause of climate change!

Bill Parsons
May 10, 2020 3:49 pm

Thanks for the richly detailed description of “restoration forestry” in this context. Given your knowledge of forestry, I’m sure such an operation could achieve its goal of increasing run-off while maintaining the forest’s natural ecosystems.

Still, the University of Reno’s Adrian Harpold, guiding researcher and lead author of the paper, identifies increased run-off as the chief objective, with the intent of increasing flow to Reno. He has created “… a modeling tool to focus on the issue of water quantity. The tool predicts how different approaches to thinning the forest impact snowpack accumulation in Lake Tahoe, which controls how much water is available for downstream communities such as Reno.” Other “tools”, he says concern themselves with water quality, wild fire prevention, wildlife habitat, etc. I just wonder if foresters can do commercially viable tree thinning with minimal road access, at the same time that they maintain habitat, lessen wildfire dangers and create more stream flow as well. I’m in favor of the tree harvests, just not sure how it would be done.

My skepticism is of the effort to silo these respective “tools” which raises the question of whether one must be achieved at the expense of others. As I also noted in my comment above, I wonder what use the additional water is being put to. See

Mike Dubrasich
May 10, 2020 5:24 pm

“Runoff” is surface meltwater in the spring. More runoff leads to high spring flows, low summer flows. Deep percolation is infiltration of melting snow into the aquifer. More deep percolation leads to somewhat less spring flows and somewhat greater summer flows. That’s the theory anyway.

The article above is written by a science publicist. I think he or she gets many details wrong. It’s unfortunate, and perhaps incorrect to place much stock in quotes from the article.

The abstract of the research paper is available, but the main text is behind a paywall.

The abstract does not mention “runoff”. Instead it is concerned with “melt volume” and increasing that by reducing “snowpack sublimation losses”. A model was used to simulate snow depth:

Here, we apply the high-resolution Snow Physics and Lidar Mapping (SnowPALM) model to simulate snow mass and energy budgets at 1-m scale over a 1,200 by 1,200 m domain on the west shore of Lake Tahoe, Sierra Nevada, USA. The SnowPALM model verifies well against observations of snow depth and snow temperature in open and under canopy locations.

Then thinning was “simulated” and used to predict reductions in sublimation. No forests were actually thinned in this research. No on-the-ground measurements of sublimation were made. No “additional water” has been realized.

Foresters can and do practice restoration forestry for multiple objectives. It’s quite different from “tree farming”, and different from “no touch”. Restoration forestry is the wave of the future, IMHO. At least I hope so, especially on public forestlands.

Bill Parsons
May 10, 2020 6:16 pm

Your description (and that of AndyHCE above) of cleared understory, or “forest parkland” is also interesting – interesting because that definition of “restoration” suggests something quite old. I’m not sure what you mean by “pre-contact” if the parkland condition is maintained by anthropogenic fires, but I know that in medieval Europe, forest parklands were achieved partly by animal browsers and abetted by human scavengers (legal as well as illegal) taking low branches for firewood. Feudal serfs coppiced willows for wattle and daub hut construction, and the seigneurs who owned the forests allowed them rights to gather deadwood and to panage pigs beneath beach and oak, so no seedlings. So large tracts of forests by the 13th century and later were rather heavily managed, and from what I can gather, had this “parkland” quality. Literature of the day refers to large tracts of forest chases and parks. How this ecosystem affected accidental fires would be interesting to know, but they certainly practiced deliberate woodland burning as well, utilizing the clearings and meadows for crops. WUWT commenters discussed some of this last year as a way of addressing the forest fires.

Mike Dubrasich
May 10, 2020 8:09 pm

The word “pre-Contact” is used by anthropologists to refer to indigenous American cultures before Europeans arrived. “Contact” may mean actual meet-and-greet events (such as Pilgrims and Indians) or more loosely when Old World influences (such as diseases) first impacted Indians.

“Restore” means different things to different people. Restoration forestry seeks to restore the type of forest we think was prevalent pre-Contact, but for a variety of reasons beyond merely historical accuracy. History is more of a guide than a goal in this case.

Anthropogenic fire was a principal land use tool here and across the world, including Europe. Certainly many such fires were more or less accidental (or accidents waiting to happen). How much is actually a point of scholarly debate (scholars have little else to do, apparently).

In any case, landscapes subject to frequent human-set fires were less likely to broadly burn when lightning struck. Lightning fires tended to be confined within the pre-burned patch system. This is the basic consideration used in prescribed burning today. One advantage of patchy anthropogenic fire to Neolithic cultures was that their landscape (grocery and hardware store) was less likely to be entirely consumed by a single lightning or accidental fire. Deliberate burning was thus a survival technique (in more ways than one).

We are living in a period of megafires. We (I’m attempting to spread the blame) have allowed fuels and fuel continuity to accumulate. Public lands are not patchy any more. Fires get going and spread over vast areas. That’s not the historical norm. Megafires are hugely destructive, but they need not happen at all. We (there it is again) can prevent megafires by restoring the patchwork of pre-burned, open and park-like forests. That’s the promise of restoration forestry.

PS – thanks for the opportunity to explain all this. Hope it is clear and mostly succinct.

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