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Southern Nevada Water Authority

Trees, Lawns & Roots

Trees, Lawns and Roots

Once a tree has established itself in a
lawn, any disruption to growing conditions
can cause problems.

Lawns and trees don't always get along. Large tree roots that grow to the surface create safety hazards and mowing obstacles. Below the surface, grass and tree roots compete for sunlight, water, nutrients and oxygen. This struggle often produces poor quality turf and slow-growing young trees.

As they adapt to their environment, trees will begin to rely on the regular, and sometimes excessive, water and fertilizer applied to the turf. Once the tree has established itself in a lawn, any disruption to the growing conditions can cause problems and subject the trees to stress.

When a tree is stressed, it's vulnerable to infestation by insects and diseases.

Common disruptions around trees include:

  • Mechanical root damage from excavation and trenching equipment
  • Physical damage to the trunk, branches or large roots from equipment
  • Extreme changes in the amount and distribution patterns of water and/or nutrients
  • Compacting the soil with heavy equipment or changing the grade around the tree, both of which can smother roots

Tree Root Basics

The root system of a tree performs many vital functions. Roots store food needed to produce spring foliage, absorb and transport water and minerals from the soil, and anchor the tree to the ground.

Trees growing in urban areas seldom develop taproots. Root systems actually consist of larger perennial roots and smaller, short-lived, feeder roots. Large, woody tree roots and their primary branches increase in size and grow horizontally. They are usually located in the top 6 to 24 inches of soil.

The small feeder roots constitute the major portion of the root system's surface area. Feeder roots grow out from large woody roots and usually grow up toward the soil surface. At the surface, feeder roots mix with lawn and shrub roots and compete for the water, oxygen and minerals that are more abundant near the surface.

The major function of feeder roots is the absorption of water and minerals. Feeder roots are located throughout the entire area under the canopy of a tree. As much as 50 percent of the root system grows beyond the drip line and may extend as far as the height of the tree.


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