Over the last decade or so, educators, parents and doctors have begun strenuously emphasizing the need for children to get outside and play. Often, the driving force is obesity prevention, but children also benefit psychologically from spending time outdoors.
The Problem with Good Intentions
There is a small problem with this goal. Increased time spent outdoors (particularly in California) means an increase in sun exposure, and increased sun exposure carries significant health risks. According to the Centers for Disease Control and Prevention, as many as 90 percent of all melanomas may be caused from exposure to ultraviolet light. (Centers for Disease Control and Prevention, 2002) Accordingly, it is important to provide children with access to outdoor playgrounds, but those playgrounds should be shaded.
Trees: The Obvious Answer
Trees are the easy answer, and given the additional benefits they provide – such as cooling the area and reducing the amount of particulates in the air – it is hard to envision anything else being as well suited for the task. However, shading a playground is not as simple as buying a few seedlings, sticking them in the ground and waiting for the shade – you must carefully select and place the trees to maximize the amount of shade provided, and minimize the potential for failure and increased labor.
Principles of Placement
The sun’s rays approach California from the South (check out this neat solar calculator to find out exactly where the sun is relative to your location). Yes, the Sun traces a generally east-to-west path across the sky, but the path lies offset to the south. In the summer, the arc occurs higher in the sky, while in the winter, the arc remains closer to the southern horizon. Use this information to your advantage. By placing a group of trees along the southwest side of the playground, the trees will block the sun’s afternoon rays. While trees on the northeast side will certainly provide numerous tangible and intangible benefits, they will not provide very much shade for the playground.
Because they usually require little supplemental water and do not harm the habitat, native species are the preferred choice for shade-tree plantings. If native trees are not available or desired, select non-native trees and plants that have a low potential for spreading. Check out the Cal Poly Tree Selection Guide for more information about specific species.
Avoid sabotaging your efforts by planting species that have significant water requirements. Instead, choose species like redbuds, wax myrtles or any of the native California oak species, which have evolved to tolerate periodic droughts. Be aware that some oaks are “drought deciduous,” meaning that they drop their leaves in response to droughts. Avoid these trees, as they will often lose their leaves when you need shade the most.
Changing of the Seasons
One of the benefits of using trees to provide shade is that with careful selection, you can design a shade concept that changes with the seasons. For example, you can use deciduous trees in places that would benefit from winter sunshine, yet use evergreen species in places in which shade is always desirable. Additionally, because of the educational value alone, it is always a good idea to incorporate a few trees that display excellent fall color changes.
It is important to consider the effect the new trees will have on the local critters. While some animals may be welcome additions to the playground, others tend to spoil the party. For example, oak trees are likely to attract squirrels, jays and woodpeckers, while blackberries, cherries and black locusts may be too popular with bees. While bees are an important part of the terrestrial ecosystem, and children should learn about their value, playgrounds are not the ideal place to teach them these lessons.
Centers for Disease Control and Prevention. (2002). Shade Planning for America’s Schools.