Posts Tagged: arborists
Cities in California inland areas must make street tree changes to adapt to future climate
Many common street trees now growing in the interior of California are unlikely to persist in the warmer climate expected in 2099, according to research published in the July 2018 issue of the journal Urban Forestry & Urban Greening.
“Urban foresters in inland cities of California should begin reconsidering their palettes of common street trees to prepare for warmer conditions expected in 2099 due to climate change,” said the study's co-author, Igor Lacan, UC Cooperative Extension environmental horticulture advisor in the Bay Area.
Common trees in Coastal California cities appear to be better suited to withstand the 2099 climate.
“Our research shows that some trees now lining the streets of cities like Fresno, Stockton and Ukiah are likely to perform poorly in 2099,” Lacan said. “Those cities need to look at the conditions – and trees – now found in El Centro, Barstow and Fresno respectively.”
To reach these conclusions, Lacan and co-author, professor Joe McBride of UC Berkeley, used space-for-time substitution. They compared the most common street tree species in cities representing each of the 16 California climate zones with trees in cities that currently have climates that approximate the expected warmer conditions in the 16 cities 80 years from now.
For example, Eureka can expect a climate like Berkeley's today; Fresno's climate will resemble the climate of El Centro today. (Find the complete list of cities below.) The corresponding cities were determined with climate predictions from Cal-Adapt, which synthesizes California climate change scenarios to reach a consensus view of the magnitude of climatic warming.
“We used the mid-range models,” Lacan said. “It's very reasonable to say the warming predicted by the model we used is already ‘baked in,' regardless of any mitigation efforts. While we should take measures to prevent even greater warming – mostly by reducing the use of fossil fuels – this study aims to help adapt California urban forests to the warming that can be reasonably expected to occur.”
Lacan said he and McBride were surprised to find that coastal cities and their warm equivalents contain most of the same common urban tree species, while the warm equivalents of inland cities seemed to lack most and, in some cases, all of the common trees there today.
“It's really a sharp distinction,” Lacan said. “Perhaps they were lucky, but coastal cities are better positioned for the climate of 2099 than the inland cities.”
Climate zone |
City |
Corresponding city |
1 |
Eureka |
Berkeley |
2 |
Ukiah |
Fresno |
3 |
Berkeley |
Santa Ana |
4 |
King City |
Stockton |
5 |
Santa Maria |
Santa Ana |
6 |
Santa Monica |
King City |
7 |
San Diego |
Santa Ana |
8 |
Santa Ana |
Burbank |
9 |
Burbank |
Fresno |
10 |
Riverside |
Barstow |
11 |
Yuba City |
El Centro |
12 |
Stockton |
Barstow |
13 |
Fresno |
El Centro |
14 |
Barstow |
El Centro |
15 |
El Centro |
Furnace Creek |
16 |
Susanville |
Barstow |
For a copy of the complete research report email Igor Lacan, ilacan@ucanr.edu.
Don't Top Trees!
Late in the winter, amateur arborists in Solano County find it an ideal time to prune their trees. It is the time of the year when most of the trees are free of cumbersome leaves which are time consuming to clean up after a trim. Leaves also tend to hinder branch identification by obstructing their view. The fact is the winter is the time of year when deciduous trees are easiest to work with. Consequently, it is also the time of year when we see when catastrophic tree injury caused by an individual, uneducated in horticulture, with a chainsaw and good intentions. Before you set out to prune, remember the serious do’s and don’ts for the amateur arborist to consider before taking that chain saw to that precious tree. The first rule when pruning a tree is not to stub or head the tree branches, instead remove the entire branch so that another branch can assume the new lead-this method is called thinning. An equally important tip is to never top a tree, it ruins the natural shape of the tree and leaves it more vulnerable to pests and disease as it ages. The final piece of advice is to never make a flush cut down to the trunk of a branch, instead leave a small collar at the base of every branch but don’t leave a long stub either (the photo attached shows stubs left far too long). The final piece of tree trimming is to remove any diseased or dead branches and smaller competing limbs. The idea is to thin the branches equally around the entire tree. This is a topic that I recommend you speak with an arborist or master gardener about if you have any questions because trees are such an important investment in your landscape.