- Author: Janet Hartin
Climate Change Resources for Horticulturists and UCCE Master Gardeners
Updated by Janet Hartin jshartin@ucanr.edu 8/17/2022
University of California UC ANR Green Blog (Climate Change and Other Topics) https://ucanr.edu/blogs/Green/index.cfm?tagname=climate%20change (full index)
Examples:
- Save Trees First: Tips to Keep Them Alive Under Drought https://ucanr.edu/b/~CdD
- Landscaping with Fire Exposure in Mind: https://ucanr.edu/b/~G4D
- Cities in California Inland Areas Must Make Street Tree Changes to adapt to Future Climate https://ucanr.edu/b/~oF7
Drought, Climate Change and California Water Management Ted Grantham, UC Cooperative Extension specialist (23 minutes) https://youtu.be/dlimj75Wn9Q
Climate Variability and Change: Trends and Impacts on CA Agriculture Tapan Pathak, UC Cooperative Extension specialist (24 minutes) https://youtu.be/bIHI0yqqQJc
California Institute for Water Resources (links to blogs, talks, podcasts, water experts, etc.) https://ciwr.ucanr.edu/California_Drought_Expertise/
UC ANR Wildfire Resources (publications, videos, etc.) https://ucanr.edu/News/For_the_media/Press_kits/Wildfire/ (main website)
UC ANR Fire Resources and Information https://ucanr.edu/sites/fire/ (main website)
Preparing Home Landscaping https://ucanr.edu/sites/fire/Prepare/Landscaping/
UC ANR Free Publications https://anrcatalog.ucanr.edu/ (main website)
Keeping Plants Alive Under Drought and Water Restrictions (English version) https://anrcatalog.ucanr.edu/pdf/8553.pdf
(Spanish version) https://anrcatalog.ucanr.edu/pdf/8628.pdf
Use of Graywater in Urban Landscapes https://anrcatalog.ucanr.edu/pdf/8536.pdf
Sustainable Landscaping in California https://anrcatalog.ucanr.edu/pdf/8504.pdf
Other UC (Non-ANR) scientists
Daniel Swain (UCLA): website: https://weatherwest.com/ twitter: @Weather_West
Non-UC Climate Change Resources
Urban Forests and Climate Change. Urban forests play an important role in climate change mitigation and adaptation. Active stewardship of a community's forestry assets can strengthen local resilience to climate change while creating more sustainable and desirable places to live. https://www.fs.usda.gov/ccrc/topics/urban-forests
Examining the Viability of Planting Trees to Mitigate Climate Change (plausible at the forest level) https://climate.nasa.gov/news/2927/examining-the-viability-of-planting-trees-to-help-mitigate-climate-change/
Reports and other information resources coordinated under the auspices of the United Nations and produced through the collaboration of thousands of international scientists to provide a clear and up to date view of the current state of scientific knowledge relevant to climate change. United Nations Climate Action
Scientific reports, programs, action movements and events related to climate change. National Center for Atmospheric Research (National Science Foundation)
Find useful reports, program information and other documents resulting from federally funded research and development into the behavior of the atmosphere and related physical, biological and social systems. Search and find climate data from prehistory through to an hour ago in the world's largest climate data archive. (Formerly the "Climatic Data Center") National Centers for Environmental Information (NOAA)
Think tank providing information, analysis, policy and solution development for addressing climate change and energy issues (formerly known as the: "Pew Center on Global Climate Change"). Center for Climate & Energy Solutions (C2ES)
Mapping Resilience: A Blueprint for Thriving in the Face of Climate Disaster. The Climate Adaptation Knowledge Exchange (CAKE) was launched in July 2010 and is managed by EcoAdapt, a non-profit with a singular mission: to create a robust future in the face of climate change by bringing together diverse players to reshape planning and management in response to rapid climate change. https://www.cakex.org/documents/mapping-resilience-blueprint-thriving-face-climate-disaster
Cal-Adapt provides a way to explore peer-reviewed data that portrays how climate change might affect California at the state and local level. We make this data available through downloads, visualizations, and the Cal-Adapt API for your research, outreach, and adaptation planning needs. Cal-Adapt is a collaboration between state agency funding programs, university and private sector researchers https://cal-adapt.org/
Find reports, maps, data and other resources produced through a confederation of the research arms of 13 Federal departments and agencies that carry out research and develop and maintain capabilities that support the Nation's response to global change. Global Change (U.S. Global Change Research Program)
The Pacific Institute is a global water think tank that combines science-based thought leadership with active outreach to influence local, national, and international efforts to develop sustainable water policies. https://pacinst.org/our-approach/
Making equity real in climate adaptation and community resilience policies and programs: a guidebook. https://greenlining.org/publications/2019/making-equity-real-in-climate-adaption-and-community-resilience-policies-and-programs-a-guidebook/
Quarterly CA Climate Updates and CA Drought Monitor Maps (updated each Thursday) https://www.drought.gov/documents/quarterly-climate-impacts-and-outlook-western-region-june-2022
- Author: Karrie Reid
I attended an informative conference in October that reported on the latest research results on tree root development in urban soils- the Landscape Below Ground. This was the fourth conference on this subject in the last 25 years. Much of the research seemed to confirm findings I had previously read and which have mostly been incorporated into recommendations and practice, at least in the state of California. However, it is always good to have research repeated and confirmed in a variety of scenarios and species, and there were some new and interesting findings as well. I am going to recap some of both in the next couple of posts.
Pre-plant Tree Inspection
ladder root system
![ladder root system ladder root system](http://ucanr.edu/blogs/LandscapeLush/blogfiles/56456.jpg)
The health of trees initially, especially the structure of their root system, has a significant impact on the survival rate and growth of trees after planting. Fall is an excellent time for planting trees, so pay attention to this if you are installing this season. The most important aspect of the root system (which you should inspect before planting) can be summed up in this phrase: straight roots, some of them near the surface. What trees need, and what you want is a "ladder" of roots, all of them straight or bending less than 45°. You don't want them all going straight down (diving), or the tree cannot stabilize itself in the ground. For all aspects of a healthy nursery tree, see this: Guidelines for Nursery Tree Quality.
At the nursery, a good root system can be accomplished best by one of two methods: potting up to the next size in a timely manner and shaving all roots to the point where they hit the edge at the time of potting up. This eliminates the bends before they set up in the next size. The second method is to use something called an air pot, which has perforations throughout the surface. When roots reach air, they die at the tip rather than continue to grow in a circular manner around the pot. Demand good stock and give your business to nurseries that provide it. The guidelines for growing quality trees can be found here: Quality Tree Production Strategies.
Soil Preparation
Whenever possible, rip or deep till and incorporate up to 25% organic matter to add carbon and air space for optimal root growth (more than 25% is not better). Shallow tillage has only very brief effects on trees, since roots ideally grow down past the initial 12" rather quickly. Roots grow where they can. Sounds obvious, but without oxygen and carbon dioxide exchange space, without water penetration, roots will not grow out into surrounding soil. Minimum root system means minimum canopy. If tilling cannot be done because of existing trees or other infrastructure, you can add some pore space by deep drilling holes 2' deep and 2" wide and filling with small gravel or biochar, which will maintain the space for oxygen and drainage. Additionally, sufficient space for tree roots should be planned in advance. If pavements must be installed over tree roots' eventual growth area, structural soils can significantly enhance the trees' ability to support healthy growth. To read about a project at UC Davis: UCD Parking Lot Structural Soil. For a complete guide to the first structural soil created by Cornell University researchers and to read research updates (scroll halfway down page): Urban Horticulture Institute.
Mulch
Do it. Time and again research confirms the benefits of organic mulches for improvement of soil structure, water infiltration, moisture retention, temperature buffering for root health, and the health of beneficial soil microbes. The results are still out on whether the source of the mulch makes a difference, and research is ongoing to find out if mimicking the native soil litter for a particular species is more beneficial than non-specific mulch from other species.
Next week we'll discuss Fertilizing, Disease, and Tree Stability.
/h3>/span>/h3>/span>/h3>- Author: Jeannette Warnert
Reposted from UCANR News
The changing climate predicted for California – including less rain and higher day and nighttime temperatures – is expected to cause chronic stress on many street tree species that have shaded and beautified urban areas for decades.
Realizing that popular trees may not thrive under the changing conditions, UC Cooperative Extension scientists are partnering with the U.S. Forest Service in an unprecedented 20-year research study to expand the palette of drought-adapted, climate-ready trees for several of the state's climate zones.
“The idea is to look at available but under-planted, drought-tolerant, structurally sound, pest resistant trees for Southern California that do well in even warmer climates,” said Janet Hartin, UCCE horticulture advisor in San Bernardino County.
Hartin, a 34-year veteran advisor, said the project is her first to stretch to 20 years; it will likely extend past her tenure with UCCE.
“I'd like to retire in five or six years,” she said. “But I'm very excited about being a pioneer in a study that will continue with my successors. I think it's important for our children and our children's children, as well as for the environment.”
At the end of 2019, with three years of data on tree health and growth rates, the scientists expect to be able to publish the first results and make them available to arborists, urban foresters and residents throughout the regions of the study.
Twelve tree species were selected for each climate zone in the comparative study, with several area parks used as control sites. Hartin and her Southern California research collaborators – UCCE advisors Darren Haver of Orange County and Jim Downer of Ventura County – worked closely with UC Davis plant biologist Alison Berry, UC Davis research associate Greg McPherson and USFS research urban ecologist Natalie van Doorn to select promising species.
They looked for trees that are already available at local nurseries, but are underutilized. The trees in the project exhibit drought tolerance and disease resistance, plus produce minimal litter. The researchers also sought trees that would provide ample cooling shade for a long time – ideally 50 years or longer.
The varieties come from areas around the world with climates similar to California. Two trees planted in replicated plots at the UC Riverside Citrus Field Station are native to Australia, two are native to Oklahoma and Texas, one is native to Asia and two are non-native crosses of other trees. Three of the trees are native to California: the netleaf hackberry, Catalina cherry and island oak.
“Trees are a long-term investment,” Hartin said. “A tree will live 50, 70, 90 years. The proper selection is very important to help ensure longevity.”
Making the long-term investment with the proper selection yields considerable returns. In a warming world, trees are natural air conditioners.
“Urban areas create heat islands, with dark asphalt surfaces reradiating heat. Cities can be 10 to 20 degrees warmer than the surrounding environment,” Hartin said.
Other tree benefits include soil health and stability, wildlife habitat and aesthetic beauty.
Following are a sampling of trees that are part of the comparative study:
Acacia – A 20-foot-tall, 20-foot wide evergreen that is drought resistant, and withstands moderate irrigation. Native of Australia.
Blue palo verde – A tree that reaches about 25 feet in height, the Blue palo verde is drought resistance and lives 50 to 150 years. Its trunk, branches and leaves have a blue-green hue. Native to the southwestern U.S. and Mexico.
Brazilian cedarwood – A native of Brazil and Paraguay, the deciduous tree grows to 50 to 65 feet. The tree produces pale yellow tubular flowers in the spring.
Catalina cherry – Native to the chaparral areas of coastal California, the Catalina cherry grows to 30 feet high. The evergreen tree tolerates drought when mature. It produces sweet purple-to-black edible fruit.
Chinese pistache – A deciduous tree with beautiful fall color. Grows to 35 feet tall, 30 feet wide. Drought resistant, but tolerates moist soil. Native to central and western China.
Desert willow – Growing to 30 feet tall and living 40 to 150 years, the desert willow tolerates highly alkaline soil and some salinity. A deciduous tree, it boasts large pink flowers all summer that attract hummingbirds and other wildlife. Native to the southwestern U.S. and northern Mexico.
Escarpment live oak – Native to west Texas, this tree is cold hardy and drought tolerant. Typically evergreen, it can be deciduous in colder climates.
Ghost gum – Very tall at maturity and drought tolerant. An Australia native.
Indian laurel – Commonly called a ficus, this is a 35-foot-tall, 35-foot-wide tree at maturity that is drought resistant and tolerates highly alkaline and saline soils. Shade potential is high. Native of Asia and Hawaii.
Ironwood – A southwestern and northern Mexico native, Ironwood is semi-drought resistant once mature and tolerates alkaline soil. Ironwood, which grows to about 33 feet tall, can live 50 to 150 years.
Island oak – This tree is native to five of six California off-shore islands. Drought tolerant, it grows to nearly 70 feet tall when mature.
Maverick mesquite – Native to the southwestern U.S. and northern Mexico, this tree does well in full sun and is drought resistant once established. The tree grows to 35 feet tall. The Maverick mesquite is a thornless variety.
Mulga – A versatile and hardy tree that grows 15 to 20 feet in height, the mulga – a Western Australia native – tolerates hot and dry conditions. The leaves are evergreen and the tree has yellow elongated fluffy flowers in spring.
Netleaf hackberry – A California native, the netleaf hackberry grows to 30 feet. Its deep root systems and heat resistance makes the tree idea for urban conditions.
Rosewood – Native to southern Iran, Indian rosewood grows to 65 feet tall, and 40 feet wide. Evergreen. Semi drought resistant and intolerant of alkaline soil.
Shoestring Acacia – Evergreen and 30 feet tall when mature, shoestring acacia is drought resistant and thrives in slightly acidic to highly alkaline soils. Native to Australia.
Tecate cypress – A native of Southern California and Mexico, the Tecate cypress is very drought tolerant. Its foliage is bright green. Young trees are pyramidal in shape, becoming more rounded or contorted with age.
Partners in the tree study are Los Angeles Beautification Team volunteers, LA Parks and Recreation team, Chino Basin Water Conservation District, and Mountain States Wholesale Nursery.
Funding and other support is provided by LA Center for Urban Natural Resources Sustainability, ISA Western Chapter, Britton Fund, USFS Pacific Southwest Research Station, and the UC system.
The University of Minnesota Extension and the National Urban Extension Leaders have announced a call for proposals for the National Urban Extension Conference on “Engaging in Collective Purpose,” which will be held in Bloomington, Minn., May 7-11, 2017.
Proposals may include, but are not limited to, examples and impacts based on how extension operates in city or regional centers, city neighborhoods through shared partnered offices or through traditional county operations.
The full call for proposals is at https://sites.google.com/a/umn.edu/urbanextensionconference2017/call-for-proposals.
The deadline for submissions is Sept. 30, 2016.
For more information about the National Urban Extension Conference, visit the conference website.