The increasingly bad news about the "greenhouse effect" and the disappearing ozone layer also carries opportunities for hope. As suggested by the American Forestry Assn. and others, people putting more trees in cities can produce a major impact.
Plant 100 million trees nationwide? Impossible? Perhaps memories are too short. Four years ago, the people of Southern California, supported by the nonprofit group TreePeople, joined with government agencies and private corporations to plant more than 1 million trees in time for the 1984 Summer Olympics. It was achieved on a shoestring budget by a committed public.
Those who remember that campaign will be gratified to know that it became a model for groups around the world. In Australia, for instance, a 200-million-tree campaign is entering the home stretch.
Now more trees are needed, not just any trees, but targeted species precisely placed to accomplish the maximum shading and cooling of buildings and other heat-absorbing surfaces.
We need to plant "unthirsty" species: natives, and in many cases deciduous trees, that protect from the burning summer sun but welcome its warming winter rays. We need trees that will shade three- and four-story buildings, trees recommended by arborists, foresters and the nursery industry.
According to researchers at Lawrence Berkeley Laboratory, summer temperatures in the San Fernando Valley can be lowered as much as 9 degrees if the urban "heat island" effect is successfully broken up by appropriate planting. This translates to a potential saving of 44% of the energy used in air conditioning. An investment in trees could eliminate the need for one 600-megawatt, billion-dollar power plant to handle peak-load air-conditioning demand. Mayor Tom Bradley's goal for Los Angeles is 5 million new trees.
So where, ideally, do we plant to achieve these results? First, at home; houses should be shaded by at least three large trees--two on the south side, one on the west. Then at large heat-absorbing areas like parking lots, streets and school yards. An additional problem makes schools an important target; the disappearing ozone layer means greater exposure to cancer-causing ultraviolet rays. Consider the option of turning Los Angeles' barren school grounds into lush forested environments.
The cost need not be prohibitive. Trees planted around homes can be three-year-old saplings, each costing between $5 and $10. Guided by gardening staffs and community volunteers like TreePeople's trained Citizen Foresters, students could do much of the planting and maintenance at schools. This is the time to expand current curricula to include stewardship of the local environment. Consider the benefits of challenging students to help solve a global problem-- and improve their campus.
Los Angeles needs a comprehensive urban forestry program--including a computerized tree inventory. We shouldn't even consider planting on streets without a tree management and protection system in place. We need to insist on higher standards of pruning to ensure that trees achieve their height, beauty and full shading potential. We need ordinances to protect heritage trees. We must insist on street and parking lot planting for new developments, and retrofitting old parking lots in commercial and industrial areas.
Together, we can do it.