If you're a fan of Groundhog Day, you know that Punxsutawney Phil saw his shadow...
Coast Room renovations.
Renovations in the Coast Room.
Posted on
Sunday, February 26, 2023 at
10:39 PM
Focus Area Tags: Agriculture
Reposted from UC Davis News
Scientists at the University of California, Davis, are taking the temperature — and other measurements — of lakes of all sizes and shapes throughout the mountains of California to see how climate change is affecting them and what, perhaps, can be done about it.
A study published this month in the journal Limnology and Oceanography Letters shows that, despite rapidly warming air temperatures, spring snowpack is the biggest predictor of summer warming in small Sierra Nevada lakes.
The study examined more than 30 years of climate and lake temperature data at Emerald Lake, a long-term study site in Sequoia National Park. It was led by UC Davis with colleagues at UC Santa Barbara and UC Riverside.
Benthic chambers measure sediment metabolism at a small Sierra Nevada lake in August 2018. (E. Suenaga)
High rates of warming air
The researchers found that summer air temperatures at Emerald Lake are warming at a rate of 1.0 degree Celsius, or 1.5 degrees Fahrenheit, per decade.
“That's huge,” said lead author Steven Sadro, a UC Davis assistant professor in the Department of Environmental Science and Policy and a member of the Tahoe Environmental Research Center. “That's as high a rate of warming as nearly anywhere on the planet. It's also consistent with what you'd find in a lot of mountain regions, which are warming at rates as high as those seen in the Arctic, in many cases.”
Yet these small alpine lakes are somewhat buffered from the higher air temperatures because they respond primarily to variation in the snow. The amount of snow controls when the lake becomes free of ice and can absorb radiation from the sun, which heats the water.
“That's not to say that there is no climate warming signal,” said Sadro. “In drought years, when the role of snow is small, we find a warming trend consistent with the rate of warming found in other lakes throughout the world.”
Climate affects phytoplankton, too
A companion study conducted at Emerald Lake and published in June in the journal Water Resources Research found that changes in snowpack also increased the abundance of phytoplankton in Emerald Lake. If droughts continue to be more frequent, high-elevation lakes in the Sierra are expected to become more productive. Researchers are not yet certain how that might affect the lakes. More phytoplankton could mean more food for lake organisms, but it could also impact lake clarity, which is often an indicator of ecosystem health.
Together, the papers show that yes, climate change is impacting these lakes and that its effects are somewhat buffered by snowpack. But what that means for the greater ecology of the area is still unclear.
A current project may provide additional answers.
Adrianne Smits, a NSF postdoctoral fellow at UC Davis, deploys a mooring in a Yosemite lake. (E. Suenaga)
There are upwards of 14,000 small lakes in the Sierra Nevada. This past summer, UC Davis limnologists and colleagues began installing high-frequency instruments in nearly 20 of these lakes, which stretch from Castle Lake in Northern California to Emerald Lake in the southern Sierra.
The project is called the California Mountain Lake Observatory Network, and it's being conducted through Sadro's lab by Adrianne Smits, a National Science Foundation Postdoctoral Fellow at UC Davis.
As weather events occur, be they storm, drought, wildfire or clear skies, the instruments capture data about water temperature, dissolved oxygen, light levels and other factors. Data from these lakes will be used to develop models to help predict how all the other lakes in the Sierra are responding to changes in climate.
“Castle and Emerald lakes are both long-term study sites, and together they provide unique bookends to the entire Sierra Nevada mountain range,” Sadro said. “We're trying to fill in everything in between to better predict how lakes across the Sierra are expected to change.”
This ongoing research could help resource managers identify which lakes are most sensitive to climate impacts and target them for mediation.
The analysis for the two published studies was made possible because of long-term research support for Emerald Lake and the Tokopah watershed since the early 1980s from the National Science Foundation, National Oceanic and Atmospheric Association, National Aeronautics and Space Administration, and the California Air Resource Board.
Co-authors for both studies include John Melack of UC Santa Barbara and James Sickman and Kevin Skeen of UC Riverside.
/h2>/h2>/h2>/h2>
Posted on
Wednesday, December 19, 2018 at
2:08 PM
A few of you growers out there have told me in the past "Lynn, if you want it to rain, hold a field...
Posted on
Monday, January 4, 2016 at
4:38 PM
September 21, 2012
Forest scientists bet on the trifecta SWEEP in the Sierra Nevada
Article reviewed: Forests and water in the Sierra Nevada: Sierra Nevada Watershed Ecosystem Enhancement Project (SWEEP)
By R.C. Bales, J.J. Battles, Y. Chen, M.H. Conklin, E. Holst, K.L. O’Hara, P. Saksa, and W. Stewart
The plot line: [Note that this is a “white paper” (self-published), so I am straying from my typical format of reviewing only peer reviewed articles. Given the relevance for management and the quality of this particular paper, it seems worth making an exception]. This group of forest scientists quite aggressively makes the argument that forests in the Sierra Nevada can be managed for improving both the quantity and quality of water to benefit the commonwealth of California, and that there should be monetary incentives for the landowners who do such management. Their case is built upon the notion that water is of very high value and that several studies done in other similar forests clearly document that lower density forests (i.e. recently harvested) do increase water yield and potentially increase snow pack persistence. They make the case for large-scale studies that can be used in the future to help foresters and landowners meet the triad objectives of water, fire severity reduction, and species restoration (the trifecta SWEEP).
Relevant quote: “The perspective that forest management for water supply is not worth the trouble is ingrained in both upstream and downstream resource managers. The SWEEP team contends that forest management for water supply is worth the trouble…”
Relevance to landowners and stakeholders:
Forest landowners pay attention any time a scientist or economist suggests that they should be paid more for the “ecosystem services” that they provide to society. Forests support wildlife, clean air, and natural beauty that people from the city enjoy. So why shouldn’t the folks that own these forests get paid for it? There is of course a way in which landowners can be paid for protecting their forests. That is, through a conservation easement. But what these scientists are suggesting is something quite different than a conservation easement. Instead of a forest landowner getting paid to do nothing with an easement, they are suggesting that they get paid to do something! Doesn’t that sound more feasible as an economic model?
We are of course a ways away from this actually happening, but this team of scientists is trying to conduct research that will help such a system to develop. Rigorous experiments will have to be done in order to measure with accuracy how much more water can actually come from a forest managed for water quantity and quality (when I say quality, I am referring mainly to the timing of snow melt- if snow melts later in the spring/summer, then it is of higher quality in terms of value).
You can find the arguments for why forest management could be managed for water in any forest ecology text book. A simplified version of it is this:
- All plants have leaves.
- Leaves do photosynthesis, which pulls water from the soil and transpires some of it into the air
- Leaves intercept snow and rain, some of which evaporates directly back into the atmosphere
- The fewer leaves that are present, the less water will be sent into the air, and the more water will leave the site and go into reservoirs or hydro-electric facilities.
Relevance to managers:
I think the relevant quote above says it all for managers. These authors are right- water can no longer be ignored. I have personally heard other scientists and mangers state that forest management simply cannot make a significant difference when it comes to water yield or the timing of runoff. But the large amount of evidence presented in this paper suggests the contrary. And it is no secret that water is becoming a more valuable resource every year, so even small increases in yield can be meaningful. It is only a matter of time before markets force us managers to more explicitly manage forests with water as the objective. If the research these and other scientists propose comes to fruition, then we’ll be more ready for the challenge.
The UC Center for Forestry has been managing for what we call a “water efficient forest” for the past decade. It is at a slightly lower elevation than what these authors say will be optimal for increasing water yield and runoff timing, but they also provide some logic in this paper that suggests these lower elevations could increase yield as well. The easy part was thinning the forest down to a level where one could reasonably expect an increase in throughfall and runoff. In this particular case, we have harvested to a density at about 50% of the maximum that we observe on nearby stands. The density then fluctuates between about 50 and 75% of maximum over time in between harvests. Based on the estimates from this paper, this level of density reduction might result in somewhere between a 9 and 18% increase in water yield and it should mean snow persisting for a little while longer (although for low elevation forests, it is likely more about water yield than the timing of snow melt).
In my experience, the easy part in managing for water has been conducting the commercial thins. After all, it is a productive forest so we can generate revenue from the thins by harvesting commercial sized trees. We have been able to, concurrently or immediately following harvests, reduce the small tree cover and surface fuels to make the forest resistant to high severity fires. According to this paper, this action has resulted in what should be a structure that yields more water (somewhere between 9 and 18% increase). The challenge over time has been in managing the understory vegetation in order to prevent it from developing a significant amount of leaf area that would defeat the purpose of increasing water yield. It is challenging because this means conducting treatments that are not paid for with a commercial harvest. Theoretically, one could save the revenue from the commercial thin and apply it to understory treatments in between thins. This is indeed what we have done in this particular case (in the form of mastication and broadcast burn treatments), but without a financial incentive to do these treatments, I can see the situation occurring where these follow-up treatments simply aren’t done. So the authors make a good point in this paper that a water efficient forest needs to be maintained over time. It is not a one-and-done situation.
Critique (I always have one, no matter how good the article is):
They say that many of the upper watershed forests are zoned as wilderness areas, the implication being that these areas cannot be managed for increased water yield. I would argue that these areas can also be managed for water quality with fire being the mechanism for maintaining low density. Without fire in these areas, they will burn with higher severity fire that could input massive amounts of sediment into downstream watercourses, thus countering any positive effect of water quantity and quality treatments that are done in non-wilderness areas.
They make an excellent point that, if runoff is delayed because of forest management activity, then hydro-electric energy production can occur later in the summer, when demands are high. I think they missed out on a point to make about the further potential for these treatments to benefit energy production during the summer. If the treatments are done in the summer and involves a biomass harvest of small trees and tops/limbs, then this would also potentially result in energy production during a time when it is most needed. Perhaps this is too speculative, but it is interesting to think about the potential for biomass harvests to by synergistic with water yield treatments from an energy production perspective.
They focus on forests between 5,000 and 12,000 feet elevation as having the most potential for increasing water yield and runoff timing, because they are productive and warm (above freezing). 12,000 feet… really? Any time I’ve been at 12,000 feet in the Sierra Nevada, I have not noticed many trees. At 12,000 feet, I’m catching my breath and enjoying the view because there aren’t many trees, if any at all. And lots of the winter period is cold at this elevation. Given their logic, it seems like this elevation should be shifted downward, perhaps between 4000 and 9000 feet. 4000-5000 foot elevation forests may not be dominated by snow, so the potential to delay runoff timing is less. But based on their logic and points scattered throughout the paper, forests in this elevation could increase yield substantially. The paper could use some clarity in reconciling all of the different factors of water yield and runoff timing in order to justify the 5 to 12,000 foot elevation target.
They report an average basal area in one of their targeted study areas of 400ft2/acre, with an average canopy cover of only 51% and an average canopy height of only 60 feet in a forest dominated by 100 year old trees. These numbers are not adding up in my head. That basal area seems very high for a forest that does not appear to be highly productive (trees growing 60 feet in 100 years). On the other hand, the LAI they report is also exceptionally high. A high LAI is the only way that I can visualize a forest like this having such a high basal area, so perhaps the numbers are good. But their statement about this forest being typical of much of the northern Sierra Nevada is a stretch- especially considering the 5000 to 12000 foot elevation range that they are talking about.
Posted on
Friday, September 21, 2012 at
2:38 PM
New this year – snow in Lathrop!
Christmas carols fill the air, Santa chats with children in the general store full of sweet treats and local crafts and families meet live raindeer and baby farm animals. Meanwhile, a crew of farmworkers-turned-snowmakers work 24 hours a day blowing 100 tons of snow onto a tube-sledding slope. It's all at the Dell’Osso Family Farm right off Highway 5 just south of Lathrop. Welcome to the latest family adventure in the San Joaquin valley, Holidays on the Farm.
![DellOssoholiday sign DellOssoholiday sign](http://ucanr.org/blogs/agritourism/blogfiles/2976.jpg)
Ron and Susan Dell’Osso started taking their October pumpkin patch and corn maze seriously about eight years ago, and last year about 140,000 people showed up to buy pumpkins, enjoy the corn maze, haunted house, pony rides, pumpkin blaster, and otherwise play on Dell’Osso Family Farm. Tourists contributed about 50 percent of the San Joaquin County farm’s gross annual income. The other 50 percent of income comes from 350 acres of pumpkins, Indian corn and other seasonal specialty crops sold wholesale through a broker to grocery stores throughout the Western United States.
This March, the Dell’Ossos started researching Christmas attractions in order to extend their agritourism season. They bought a train and a zipline, built a general store with a bakeshop, learned how to make snow and opened the first annual “Holidays on the Farm” in late November. The train, zipline and store make business sense when they are amortized over both the October and December holiday seasons. The Snow Tube Mountain is already popular, with online reservations recommended for the $15.00 90-minute sessions of tubing, since the hill can only hold 250 tubers each session.
Why would these third-generation farmers turn to corn mazes and snow-making? Susan Dell’Osso explained that agritourism spreads the risk. Commercial farmers hope to make a three percent return on crops like alfalfa or pumpkins, and some years, like last year, 50 percent of the pumpkin crop can be wiped out by wet weather and mold problems.
![DellOssobakery DellOssobakery](http://ucanr.org/blogs/agritourism/blogfiles/2978.jpg)
Holiday attractions like Dell’Osso’s are also great ways to connect to and support the local community and offer low-cost entertainment for local families. Dell’Osso Family Farm tries to keep the prices low. There is no charge for parking or admission and some activities like the hay rides and go-cart speedway are free. They also include more than twenty local non-profit organizations by offering concession opportunities for volunteers to donate their time to benefit organizations including the Lathrop Senior Center, the Lathrop Police and Fire departments and the Lathrop Square Dance Club. In addition to extending the work season for many farmworkers, all of the agritourism employees are hired locally, and the popular operation is a major contributor to the local tax-base.
Watch for more pumpkin patch operators to jump on the December holiday wagon next year!
Posted on
Tuesday, December 22, 2009 at
1:53 PM