Trees can extend the life of surface materials simply by shading that material from direct sunlight. As someone stands in the sun too long, he or she becomes burned from the sunlight. The same is true for natural and man-made items. Even tree leaves can be "scorched" from direct sunlight under certain conditions.
Ultra-violet (UV) radiation is the wavelength of light responsible for breaking down many materials over the course of weeks, months and years. Shade from trees reduces the temperature and blocks UV radiation; thus, in many cases, extending the service life of materials left outdoors. In this way, the shade from trees can also moderate high and low temperature extremes that contribute to material wear over time.