Over the past year the UC Davis Arboretum and Public Garden has managed to cut back water use across campus by over 30% from 2013—that is already well above Governor Brown’s recent 25% water reduction mandate. We are proud of this accomplishment, but we are not planning to stop there. We will continue to seek reductions throughout campus and the Arboretum. In this feature we will give you an insider’s look at how we’ve managed this decrease to date, changes you’ll notice in the near future, and how we are planning for a low-water future which will hopefully give you ideas for how you can do the same.
TARGETED TREE CARE
The benefits of trees are many: they help prevent carbon from being released into the atmosphere, they provide shade, fight erosion, and so much more, but when we reduce water to our lawns that can mean we inadvertently stress the trees living there too. To help alleviate this pressure and maintain tree health we have installed over two hundred slow-release watering bags on young trees throughout campus. Each one of these bags is filled manually from our campus water truck about once a week with approximately 10-15 gallons of water which then seeps slowly from small holes in the botton of the bag into the surrounding soil. This action not only targets young tree roots, it also reduces water run-off and evaporation. Each one of these bags saves about 1000 gallons of water a year per tree. LEARN MORE.
For mature trees, like in our oak grove (see photo top right on page 1), we apply water less frequently, but more deeply. During dry months, arborists recommend watering to a depth of three feet. To assist in this effort, the California Center for Urban Horticulture at UC Davis has developed instructions for how to purchase, assemble and deploy a unique watering device called the tree ring irrigation contraption (TRIC). For more information on gathering the materials necessary to create this device and the process for assembling it, visit http://bit.ly/tric-your-tree.
While most of our main campus landscape irrigation is part of a high-efficiency computerized system, there are still some areas, mostly in the central part of the Arboretum, that require hand watering during the day with hoses and/or spray irrigation. Not only is this method labor intensive—it requires staff who can start, stop, and move it—it’s also inefficient because it often results in overspray and wet guests!
We do have plans to install new irrigation systems in these areas as funding becomes available, however, since installing systems from scratch is very expensive, it will need to be phased in over many years. In the meantime, the university is investing in more efficient, but temporary irrigation systems. These temporary systems will be set up this summer and allow for automated, more precise nighttime watering. As permanent systems are funded and installed, the temporary systems will be removed.
Thanks to the high-efficiency, computerized system that controls watering on most of campus, we can easily target turf for irrigation reductions. Some lawns will even be allowed to go dormant through the summer. However, lawns with high-event use uses like the Quad and fields used for athletics or student recreation will continue to be maintained.
We have also identified lawns for full-scale landscape conversions. Look for this change on the median near the Mondavi Center for Performing Arts. While the trees in the lawn will be maintained, the turf will be replaced with Arboretum All-Stars, California natives, and other regionally-appropriate plants.
When given the option, planting in fall is always our first choice; temperatures are dropping, but the soil is still warm. Those are ideal conditions for root development, plus, with any luck from Mother Nature, seasonal rains should be right around the corner. Plan your new drought-tolerant garden over the summer and visit our plant sales in the fall for a great selection of regionally-appropriate, low-water plants such as Arboretum All-Stars and California natives.
Thank you to “The Best Colleges” website for recognizing the UC Davis Arboretum and Public Garden in their “50 Most Amazing University Botanical Gardens and Arboretums in the U.S.” LEARN MORE.
The article sites that the organizations listed not only beautify their campuses and communities, but also serve as environmental stewards, outdoor classrooms, and living laboratories.
Here is a little bit about what they had to say about the UC Davis Arboretum and Public Garden:
The seventeen gardens that make up UC Davis Arboretum are a beautiful testament to nature’s instruction. Students not only use the 100 acres of sprawling landscape for “peaceful contemplation,” but they can also use the gardens as hands-on learning facilitators in dozens of classes offered by the university. This free resource enables students to get their hands dirty while observing a living textbook or conducting meaningful ecological research. A variety of internships are offered in conjunction with the gardens as well in topics such as sustainable gardening, plant propagation and nursery operations, and Geographical Information Systems (GIS). The arboretum recently received a 4-out-of-4 star accreditation by the Professional Grounds Management Society for outstanding performance in the areas of environmental stewardship, economic performance, and social responsibility.
We appreciate the recognition of our gardens as well as the students and programs that support them.
The Aggie Public Arts Committee, funded in part by ASUCD, commissioned a mural on the sidewalk near the Nelson Gallery, along Arboretum Dive. Conceptually, the mural is based on reimagined landscapes and wildlife, using 3-D illusions of space with an element of fantasy. Next time you are in the Arboretum, we hope you’ll stop by to see it!
Thank you Kari Kiyono for creating such a beautiful mural for us to enjoy.
Planning a vacation or trip? Don’t forget to take along your Friends membership card! Members of the Friends of the UC Davis Arboretum and Public Garden can take advantage of great perks at gardens and museums across North America. Many offer FREE or reduced admission and other special discounts to Friends members through reciprocal admission programs. Here are the details:
- Friends members at all membership levels qualify for the American Horticultural Society Reciprocal Admission Program (AHS RAP) with nearly 300 participating gardens in North America and the Cayman Islands. To search the directory of all AHS RAP participating gardens visit: http://www.ahs.org/gardening-programs/rap
- Friends members at the Manzanita level ($100) or above qualify for the North American Reciprocal Museum Association (NARM) program with over 780 participating museums and cultural institutions across North America. Even if you’re staying close to home this summer, there are lots of participating museums in northern California, including the de Young Museum, the Oakland Museum of California, The Crocker Art Museum and the California State Railroad Museum. To search the map of all NARM participating museums and cultural institutions or print a condensed list visit: http://narmassociation.org/
NOTE: The NARM program was added as a new benefit for Friends members earlier this spring. If your membership card at the Manzanita level and above does not yet show the NARM logo, stop by our office to get a NARM sticker for your card to take advantage of this great program.
Not a Friends member? Or interested in upgrading your membership to the Manzanita level? Call us at
(530) 752-4880 or stop by the Arboretum Headquarters office in the Valley Oak Cottage on La Rue on campus during regular business hours M-F 8 a.m.-noon and 1-5 p.m. to join or upgrade.
As you are aware, California is experiencing its fourth year of drought. As a result, people are very conscious of watering practices, both at their own homes and public facilities such as the UC Davis campus. While every unit on campus is working to conserve water, the information in this article addresses how the UC Davis Arboretum and Public Garden is working to conserve water in its landscapes throughout campus as well as in the Arboretum.
Q: How are you committed to saving and reducing water?
A: Per the Governor’s mandate, the entire UC Davis campus has a 25% water savings mandate over 2013 water use numbers. To date the Arboretum and Public Garden has already achieved a 30% water reduction and we are on target to exceed this goal in 2015. We are also actively working on converting turf areas into very-low water use landscapes that include Arboretum All-Stars, California natives, and other region-appropriate plants. We have cut back on irrigation schedules and run times across campus, we are using the minimum amount of water necessary to keep the campus tree canopy alive, and we are letting some of our turf areas go dormant.
The key component in our ability to reduce irrigation so quickly without the loss of our campus landscape has been our investment in a centralized “smart” irrigation system. Over ten years ago we started converting our manual system to one that automatically alters water use based on weather data, soil, and plant type. This change has allowed us to reduce our water use despite the addition of new landscapes and growth on campus.
Q: Where, what, and when do you water?
A: The campus waters all of its landscaping, but not all landscaping is watered equally. Areas that get little public use, such as turf next to a building, is watered only enough to keep it alive and to prevent erosion. Areas like the Quad, or other high-use areas, such as sports and intramural fields receive more water. By being smart about our water use, we can still recognize significant water savings while maintaining places the public and student body can use for recreation.
Watering typically takes place between midnight and 6 a.m. However, there are places where you might see irrigation during the day. On grass areas, this could be during system testing or to prepare a sports field before a game.
Q: Why do I see some areas along the Arboretum being watered during the day? Why is there overspray in these areas?
A: On some areas of the campus, but primarily within the Arboretum’s scientific collections and demonstration gardens, the irrigation system is old, or does not exist. These areas require hand-watering with hoses and/or portable sprinklers. Because these systems require people to manually start, stop and move them, you will see them being used during the day. This type of irrigation is not as efficient, which is why you see overspray onto paths—wind can also create overspray. Installing new irrigation systems from scratch is very expensive, and will need to be phased in over many years. However, in order to be immediately responsive to the drought conditions, the university is investing in temporary irrigation systems within the Arboretum. These temporary systems will be set up over the summer of 2015 and allow for automated, more precise nighttime watering to reduce overspray and water use. As permanent systems are funded and installed, the temporary systems will be removed.
Q: Where are you cutting back?
A: We are cutting back in almost all areas with the exception of heavily used fields for sports programs and event spaces, such as the Quad.
Q: What water savings have you achieved to date?
In 2014 the Arboretum and Public Garden reduced its water use by over 100 million gallons and is on track to exceed that again in 2015. This represents a 30% savings in water use over our 2013 numbers.
Q: Why do I see irrigation in construction areas on what look like weeds?
A: Some areas of construction are mandated by the State to have vegetative cover of a certain percentage to mitigate potential soil erosion. Irrigation in these areas is required to meet this goal even if the vegetation is weedy; areas like these will not be watered during the summer.
Q: Why do I see some areas around trees that look like they are soaked or muddy?
A: The best way to irrigate trees during drought is to apply water less frequently, but more deeply. In other words, the frequency of watering is reduced, but when watering does occur, it will be for longer. This method soaks the root zone to allow the water to penetrate deeper into the soil; here, a smaller amount water is lost to evaporation so it stays available to the tree for longer. Overall, less water is used, but the area around the trees can look soaked or muddy for a period of time.
Q: Why are there green bags around some trees?
A: In areas where we have younger trees in turf areas, slow-release watering bags allow for a targeted application of water on the new trees while the surrounding turf areas go dormant or partially dormant due to reductions in water application. These bags allow the trees to survive and become established with less total water to the site. These types of bags are used in dry environments without tree-specific irrigation systems, and are very efficient users of water. Each of the 240 bags the campus is currently using is estimated to save 1000 gallons of water annually.
Q: Why is there water in the Arboretum waterway? With the drought, can we afford to have water there? Shouldn’t it be dry?
A: During the winter months, stormwater flows into the waterway. In the summer months, all the water in the Arboretum waterway is campus recycled wastewater. Rather than discharging the treated wastewater directly into Putah Creek, it first flows through the Arboretum waterway, then goes to the creek. This use of the recycled water provides habitat for the fish, otters, turtles, and birds that live along the waterway, keeps the riparian plants healthy, and creates a park-like atmosphere along the Arboretum.
Q: Couldn’t you irrigate with the recycled water?
A: Some landscaped areas in south campus do use recycled water for irrigation. This kind of water only works on landscapes with plants that can tolerate the high salt levels found in recycled water. If it were used on existing campus landscapes, it could kill our trees and plants over time. While the salt levels won’t harm the wildlife or plants along the creek banks, if it were used outside of this area, the wetting and drying cycles involved with regular irrigation would cause the salts to concentrate in the soil over time.
Q: How can I help?
A: If you see broken irrigation heads or lines, or irrigation running that doesn’t seem to fit the above-referenced exceptions, please call the campus work order desk at (530) 752-1655.
Please know we not only have an active conservation plan, but a reason behind each irrigation choice we make. With your help and an eye on maximum water savings, we are confident that our water saving landscape planning and practices can become a model for other universities and cities throughout the state.
We take our campus trees seriously. They are valuable both environmentally and aesthetically, but they’re at risk because we’re dialing down the irrigation on the lawn around them. To avoid this conundrum teams from the UC Davis Arboretum and Public Garden’s grounds and landscape services team have started irrigating our younger trees with slow-release watering bags—a fancy description for those big green zippered sacks starting to appear at the base of young trees throughout campus.
Cary Avery, associate director of UC Davis grounds and landscape services, ordered about 240 of these bags and plans to reuse and rotate them throughout campus in an effort to get our trees through the summer while trying to save more water.
“We can’t rely on our sprinkler systems anymore to water our trees, especially since we’re cutting back watering our lawns even more dramatically than last year,” says Avery. “Instead, on young trees—those with trunks about 5 inches or less in diameter—we’re using SaplingSoakers and filling them up manually using our water truck.
Holes in the bottom of the bag allow the water to release slowly, giving the soil around the tree a chance to receive a deep water saturation with every irrigation, explains Avery. That’s what trees need plus, with this method, we see little if any run-off, and don’t lose water due to evaporation.”
Matt Forrest, irrigation supervisor for UC Davis grounds and landscape services estimates that these bags will save an average of at least 1000 gallons of water a year per tree.
“The water savings comes from the fact that we don’t have to water the lawn just to get young trees established,” explains Forrest.
Avery and Forrest know a thing or two about saving water in landscapes. Their teams have already cut back the campus’s utility (landscape) water use by over 30%—well ahead of Governor Brown’s 25% reduction mandate.
Have an older tree? TRIC it out using the Tree Ring Irrigation Contraption. LEARN MORE here.