Fight the Drought: Plant More Trees

CALIFORNIA PLANNING -It is a truly positive development that so many Angelenos are ripping out their lawns to plant drought tolerant gardens, often turning to native California plants.   Some people install these new yards to reduce their water bills, taking advantage of the recent LADWP rebate program.   Others do it because, if done right, drought tolerant gardens are far more attractive than lawns, a landscaping relic from this country’s European past.   

Unfortunately, few of these drought tolerant gardens include trees, mostly sticking to agaves, cactus, and succulents.  But, this is a mistake because there are many drought tolerant trees.  If planted correctly, they will play an important role in these new gardens.  Furthermore, they also assist our adaption to drought while counteracting climate change. 

This is because trees sequester carbon from atmospheric CO2, the most critical component of the Green House Gases responsible for global warming and climate change.  In addition, trees provide shade, which reduces soil evaporation and also promotes walking when correctly planted to form a sidewalk canopy.   Finally, trees promote the absorption of rain into underground aquifers because they buffer hard rains before they slam into the ground and run off. 

Adapting and mitigating climate change:   We are in the midst of a record drought, and it is likely that this drought will become the new normal.  LA’s average rainfall of 15 inches per year is probably a thing of the past.  This is because California’s natural cycle of wet and dry periods has been intensified by climate change.  This means that weather cycles will become exaggerated for an indefinite time.  In general, though, according to UCLA’s Institute of the Environment and Sustainability (IoES) center, the long-term forecast for nearly all Los Angeles neighborhoods is that the 21^st Century will be hotter and dryer.   We may get an occasional rainstorm or a cool, wet season, but from this point onward, our planning should be based on a climate that will have repeated droughts and heat waves.   

Planting the right tree:  Luckily, the City of Los Angeles’s Urban Forestry Division has already prepared an on-line database of 150 trees they recommend for Los Angeles, two-thirds of which are drought tolerant.   

The list is long, but some trees are particularly desirable because they are California natives that have evolved to withstand periodic droughts.  In other cases the trees have important characteristics, such as shade or flowers that warrant their inclusion.  The most important California native trees and large shrubs are all local oak species, California Sycamore (not the European Sycamore, also called the London Plane tree), California/Western Redbud, Manzanita, Fremont Cottonwood, Pacific Wax Myrtle, California Bay Laurel, and Ceanothus (California lilac—photo above).

Proper planting and tree care:  The Tree People offers detailed on-line guidelines on how to properly plant trees and then care for them during droughts.  These are the basics: 

• The planting hole for the tree should be at least twice the size and depth of its root ball.  The excavated dirt then needs to be mixed with a soil amendment before planting the tree. 

• The excess amended soil should then be used to create a mounded perimeter around the trunk so hand or drip irrigation watering will go directly to the roots and not the surrounding area. 

• The area underneath the tree should be free of grass for at least two feet and covered with mulch to reduce evaporation from the soil.  The City of Los Angeles offers free mulch at the Van Norman Recycling Center, 11701 Blucher Avenue in Granada Hills.  Call 213-923-3109 for an appointment to pick up your free mulch. 

• Watering should be long and slow, never more than once of twice a week for young trees.  If planted and watered correctly, most older trees are on their own after a few years, except for extreme droughts.  In those cases, a long, slow watering every other week should be sufficient.  

It is unfortunate that the LADWP drought tolerate garden rebate program has gone belly-up because its popularity drained its budget.  Hopefully, it will soon be refunded and become an incentive for proper tree planting. 

Less likely, however, is that the City of LA’s Urban Forestry Division will be correctly funded to systematically plant and care for drought tolerant trees on LA’s thousands of miles of under-planted or totally barren streets.  Compared to all other nearby cities, Urban Forestry simply does not have sufficient staffing and resources to tend LA’s urban forest in an era or long-term drought.

 

(Dick Platkin writes, teaches, and consults on city planning issues in Los Angeles. He writes for CityWatch and invites your comments or questions at [email protected].) 

-cw

 

 

 

CityWatch

Vol 13 Issue 58

Pub: Jul 17, 2015