Although Mt. Pleasant Elementary School is not much like a typical urban environment, downtown Roanoke is not far off. The trees that grow in downtown Roanoke face many challenges that the trees at your school do not. In general, trees in city settings are not given an adequate amount of soil for their roots to grow in. (You have all seen trees planted along the sidewalk surrounded on all sides by endless concrete and pavement.) Less space for a tree's roots to spread throughout means less water and nutrients available for the tree's survival. In the city, even when it does rain, water does not usually get a chance to soak into the ground like it would under more natural (less paved) conditions. Cities are designed with storm water systems to channel rain water into sewers. So a rainstorm in the city does not necessarily mean a tree's roots will be bathed in moist soil for any extended period of time - more likely, most of the rain will have flowed across the pavement, away from the tree and down the gutter, without the soil surrounding the tree ever getting the chance to become saturated. Since it is just the surface of the soil that is wet, when the sun comes out again the soil will dry out very quickly. Because of these water limitations trees in the urban environment are more vulnerale to drought than their suburban and country counterparts. To make matters worse, city environments commonly get much hotter than areas outside of the city limits. All the asphalt and concrete expanses absorb and retain the sun's heat much more than do grass and otherwise vegetated areas. This heat and the lack of necessary water and nutrients makes a tree weaker than it would be under more ideal circumstances. And just like with us humans, the less strong and healthy trees are, the more vulnerable they become to disease by microscopic organisms and attack by insects. Next time you find yourself in Roanoke on a hot summer day, look up and be thankful for the poor thirsty tree that is giving you shade.