- Author: Janet Hartin
Welcome to Fall!
It's my favorite season and likely for many of you, as well. Beyond the holidays and extra time with family and friends, nature radiates its beautiful hues. In addition to lovely foliage, deciduous trees often expose exquisitely shaped and sturdy trunks. And, of course, there is the lovely fall foliage showcased by many species.
Did you ever wonder why trees "turn" color in the fall? The short answer: It's primarily a function of long, cool fall nights and short, sunny days. The longer answer? Chlorophyll is responsible for the basic green color of leaves we see in spring and summer and is a necessary component of photosynthesis, which uses sunlight to manufacture sugar (food) that is stored during the dormant period of the year. Carotenoids produce yellow, orange and even brown pigments in crops such as carrots, squash, bananas and many ornamental plants such as daffodils and poppies. Anthocyanins are red and orange in color and are most linked to lavish displays of brilliant fall foliage. They also give rise to coloring of strawberries, plums and cherries.
Here's the kicker: While chlorophyll and carotenoids are present in leaf cell chloroplasts throughout the entire growing season, during fall chlorophyll begins to break down. Voila! The lovely yellow and orange hues we all look forward to seeing are finally exposed. In addition, red hues (called anthocyanins) are produced in fall. So, in reality foliage doesn't "turn" orange or red at all.
Interestingly, the actual timing of color change varies across species and appears to be genetically inherited. The same species will exhibit a similar color scheme in cool temperatures in higher elevations at nearly the same time as it does in warmer lower elevation climates.
The intensity of color can vary quite a bit however. Where do temperatures enter the picture? Both the amount of color and the overall intensity of fall color is very linked to weather conditions that occur prior to and during the actual time the chlorophyll in leaves winds down. The most brilliant displays occur after several warm, sunny days and cool, crisp (above freezing) nights. This is because although lots of sugars are made in leaves during sunny daytime hours, the corresponding cool nights prevent the sugars from moving out. The amount of soil moisture also helps ensure that from year to year fall colors vary even in the same trees. So, either a late spring or a prolonged drought can both delay the display of fall color by a few days or even a few weeks.
What's the recipe for the most brilliant fall display? Most likely a warm, moist spring followed by a warm summer and sunny fall with cool autumn nights. Although fall color is not nearly as spectacular in lower elevations of Southern California compared to other colder areas of the nation, the liquidambar or American sweet gum (Liquidambar styraciflua) offers some pretty impressive fall color and an impressive 300 to 400-year life span. (Did you know that liquidambar got its name because it at one time was a sought-after chewing gum for Native Americans?)
Two “climate-ready” tree species with lovely fall foliage that grow in both the west portion of the county and the desert are the ‘Keith Davey' Pistache, a large street and park tree sporting crimson to scarlet colored foliage and its relative, the ‘Red Push' Pistache, a hybrid between P. atlántica x P. integerrima) which has lovely red foliage as it emerges in Spring as well as Fall. Others include the Raywood Ash (Fraxinus oxycarpa 'Raywood') sporting a reddish-purple hue in the fall, and the ‘Sunburst' Locust (Gleditsia triacanthos var. inermis 'Sunburst') which offers a vivid display of fall color. Unfortunately, it is susceptible to the Invasive Shot-Hole Borer. If you have one of these lovely trees already, take good care of it to help it stand up to this aggressive pest!
Happy Fall! Enjoy the cooler weather, family and friends, and lovely trees!
- Author: Janet Hartin
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)
- Benefits of Plants to Humans and Urban Ecosystems: https://anrcatalog.ucanr.edu/pdf/8726.pdf
-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 (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: 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: Janet Hartin
University of California Cooperative Extension Drought Resources To Keep Your Plants Alive
"Trees Come First Under Drought and Water Restrictions"
Keeping Plants Alive Under Drought and Water Restrictions (English) https://anrcatalog.ucanr.edu/pdf/8553.pdf
Keeping Plants Alive Under Drought and Water Restrictions (Spanish) https://anrcatalog.ucanr.edu/pdf/8628.pdf
Prioritizing Trees During Drought and Water Restrictions (5 minute Youtube)
https://www.youtube.com/watch?v=CTKLlJgdLVk
Tips to Keep Your Landscape Trees Alive Under Drought https://ucanr.edu/b/~IjC
Landscape Tree Irrigation to Maximize Tree Health, Benefits, and Beauty https://ucanr.edu/b/~YjA
Landscape Tree Irrigation 101 https://ucanr.edu/b/~UjA
Top 10 Ways to Conserve Water in Your Landscape and Garden https://ucanr.edu/b/~tTD
Asphalt and Synthetic Turf are Superheating our Cities (in Desert Sun newspaper) https://www.desertsun.com/story/opinion/contributors/valley-voice/2022/04/09/coachella-valleys-asphalt-synthetic-lawn-heat-islands-reach-170/9515857002/
Use of Graywater in Urban Landscapes in California https://anrcatalog.ucanr.edu/pdf/8536.pdf
Need More Help? Speak to a UC Cooperative Extension Master Gardener in Your County of Residence.
- Author: Janet Hartin
In your landscape, your trees and edibles should come first under drought and water restrictions! If there just isn't enough water to go around, your lawn and flowers should be sacrificed instead. Trees are our most valuable landscape resource and take years to maximize their benefits (shade, cooling, habitat/ecosystem enhancement, carbon dioxide storage, energy conservation, pollution filters, etc.).
Just a few slow, deep waterings with a garden hose away from the trunk and slightly beyond the drip line will keep established trees alive, even during summer. Remember to keep trunks dry!
Here are some other tips:
• Spread and maintain 2-4” of mulch around garden plants and trees (3-4” for wood chips, 2” for pebbles, decomposed gravel, etc.) keeping it a few inches away from tree trunks. (Note: dark colored dyed mulches should be avoided in inland and desert areas due to their high surface temperatures that can > 60 degrees F hotter than living plants and lighter colored mulches.)
• Water early in the morning when soil evaporation is minimal.
• Control weeds. They compete with other plants for water.
• Avoid fertilizing. Nitrogen increases growth and the need for more water.
• Don't plant new plants during the summer when temperatures are highest. Even drought-resistant native and non-native plants need regular watering their first season.