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Getting To The Root Of The Problem: Planting Trees In Paved Areas

by Erik Evans

Driveways, concrete patios, and park-style walkways look gorgeous when they are first installed. However, landscape design blunders can mean that your beautiful pavement will have not-so-beautiful cracks in it in just a few years. One of the most common causes of pavement damage is tree roots. Soon, your pavement will no longer be smooth, but riddled with heaves as the roots have determinedly pushed the paltry pavement aside in their search for life-sustaining nutrients. So, what can you to to make sure you have lovely trees without sacrificing your hard surfaces? Read on or click here for more information.

Plant Wisely

Some trees have more invasive root systems, while others have roots that remain deep in the soil, not disturbing the ground above. When you're going to pave a space in your yard, or if you're going to plant a new tree close to a paved space, make sure you:

1. Install a root barrier. These will prevent the roots from the newly-transplanted tree from moving horizontally along the surface of the soil, including under your pavement. Root barriers force the root growth downward into more moist soil.

2. Plant trees as far from masonry as possible. One of the reason why pavement is so attractive to trees in because the cool concrete surface traps moisture in the soil underneath, making the dirt below the sidewalk wetter than the topsoil in the rest of your yard. Roots naturally seek moisture, so they gravitate to these cool, wet areas.

3. Plant the right trees. Check the city guidelines for boulevards and street trees, because cities usually choose trees that don't have invasive roots. Also, avoid fast growing trees, as these require a lot of water, and therefore naturally will seek the moisture hidden under your pavement. Examples of water-loving trees include:

  • Poplars. Poplars need plenty of water in order to support explosive growth. Hybrid poplars, like those designed to grow in columns for privacy, are especially invasive. 
  • Weeping willows. Willows traditionally grow alongside swamps, rivers, and lakes. They need a significant amount of water in order to sustain heavy foliage growth and flexible branches. 
  • American elm trees. These trees have powerful root systems that even delve into septic lines in order to get more moisture. 
  • Silver maples. These trees, while not the fastest growing, have shallow root systems that spread along the top of the soil. 

Trees that are less invasive include:

  • Burr oaks. Oaks provide majestic looking shade, and have uniquely shaped leaves.
  • Buckeye trees. Buckeyes are great for warm, humid environments. However, they do drop buckeyes on the lawn, requiring extra maintenance.
  • Amur maples. These bush-like trees have deep roots, attractive orange bark, and small black berries. They are good trees for privacy. 

Consider Suspended Pavement

If your trees were there first, you'll have to either have the trees removed to make sure your hardscape is not damaged, or you'll need to get creative with your paving process. One technique employed in more urban areas is using suspended pavement. Suspended pavement leaves a void space underneath the paved space. The pavement rests on a support system, and the space below is filled with loose soil that allows roots to grow without disturbing the surfaces above them. 

There are many benefits that come from using suspended pavement:

  1. In addition to making sure that your concrete goes unscathed, the roots of the trees are permitted to develop fully, extending the life of your tree. 
  2. Also, trees can be planted nearer to suspended pavement because the roots aren't in danger of causing damage. This allows for much more versatile landscape designs, and makes it possible for you to plant more trees than you might have been able to without it. 
  3. Pavement is less likely to be damaged by flooding, because it doesn't rely on the soil directly below it for support.