16. TREES: People are walking trees

Every tree is a distinct and unique entity.

In town, people love to grow trees. We love trees because they clean the air and create oxygen.

Trees give shade on hot summer days, and provide a place for songbirds to sit, sing, and raise their young.

The love of greenery, and the serenity it brings, goes back to primeval times.

In town, there are many reasons people do not like trees:

Trees bust up the sidewalk and invade the sewer.

Trees block views and reach out for the high voltage electric cables.

Trees drop messy leaves and fruits.

Trees grow old and weak, and fall on cars, people and houses.

Unfortunately, town folk do not always understand the wild aspect of being a tree, and do not give a tree the care it deserves to survive several human generations. We are conflicted about inviting such a large guest into our surroundings.

Young trees in the forest grow under the shade of the adults. They are often sustained by fungus in the soil, and wait their turn to rise up towards the sun.

Deer may nibble at the tips of trees; nematode worms suck at their roots; fires scar their bark.

Unable to get up and run away, trees embed toxic chemicals and hard fibers in their leaves and bark, grow irritating hairs and spines, bleed sticky saps and gums, and shed their bark of parasites.

Young trees in town face challenges and situations they would not meet in the forest. A car door opening or a vandal with a saw could mean the end of life. The daily stream of dog urine on the roots is not fertilizer, but poison. Humans protect the trees with barriers of wire, wood, and steel. We give young trees rations of water to quench their thirst. We cut and shape the trees to fit in town.

Some species of trees thrive, and reach maturity. My favorites trees in San Francisco are slower growers that take pruning well; trees adapted to our coastal winds and cool summers; trees that serve as food and medicine.

Other trees in town live like tree-zombies, tortured but alive. The human need for control and discipline are evident in our care of trees.

Trees are anchored and chained to the sidewalk.

They are caged by metal.

They are tied and squeezed.

We feed them metal posts and poly rope.

Strangled for life in a 2’ x 2’ square.

Strength in the trunk and stability in the roots come from the tree’s interaction with the world. As the wind blows the tree back and forth, its trunk grows thicker and roots anchor into the earth. A tree that is free is able to strengthen its core.

In town, our invited guests, the trees, need to be pruned time to time. If we do not take responsibility for them as they grow and age that will mean more and more trouble down the line. In town, a healthy tree with good structure and stable roots is a safe tree. A weak tree with rotten branches and a diseased core is a hazard to everyone. Before pruning, observe and learn about:

The tree’s natural structure and form

Dead wood

Crossing branches

Tree defenses

In the old days, people who pruned trees professionally were called “tree toppers”. That is to say, a part of the job entailed cutting the tops off of trees – cutting off the upper growth in the canopy and usually leaving thick, bare, stubs. This was not always the prettiest pruning job, more like a buzz cut or what we might call a “hack” job. Nevertheless, a tree that was too tall was taken down this way. Nowadays, the tree industry is much changed and has strived to improve the standards and aesthetics of tree care. Professionals are now called “arborists”, and topping is strictly forbidden.

Every tree has a different response to having its head cut off, so to speak. In the forest, a falling tree, a lighting strike, or a climbing bear could all break out a tree’s top. When topped, a tree has large wounds open to the interior wood. The tree is then susceptible to infection by bacteria, rot by fungi, and attack by insects. To protect itself, the tree closes off gates and channels to the cut, and activates energy reserves.

This pine gave up living altogether and became an art sculpture.

This New Zealand Christmas trees sprouted vigorously from the topping cut, and its canopy was shaped into round balls.

These Poplars in the Mission district sent up numerous shoots as part of their recovery.

These Sycamores in Golden Gate Park formed hard nub balls of wounded tree tissues. They grow shoots off the nubs. The shoots are pruned off yearly in a style called pollarding. If the shoots are not pruned off, they will grow thicker and thicker every year. These shoots will eventually resemble trunks, and possibly break off in heavy winds.

Can you see where this eucalyptus was topped? Check out the trunks coming off of the old wounds. Keep your eyes on these Eucs, watch for falling branches in a storm!