Monoculture: noun – the cultivation of a single crop in a given area.

This is a common topic among agricultural growers because it addresses the importance of crop rotation. Repeatedly planting the same crop in the same field upsets the natural balance of soil by depleting nutrients, beneficial bacteria and microorganisms. A combination of drought and over-farming in this way is what led to the dust bowl in the 1930’s.

Monocultures in tree planting can also result in severe consequences above the soil as well. Pests, diseases and fungal problems can quickly devastate a non-diverse plot of trees. Dutch elm disease quickly wiped out entire populations of street trees in the 1970’s. Unfortunately, the need for trees in the aftermath of DED meant municipalities and homeowners eagerly planted a limited number of fast-growing tree species like silver maples and ash. Now it seems history is repeating itself thanks to the emerald ash borer.

So how do we break the cycle? The answer lies in diversity of species. Many now advocate for plantings to follow the 30-20-10 rule. The goal is to limit the tree canopy of a given space to:

  • No more than 30% of any plant family
  • No more than 20% of any plant species
  • No more than 10% of any plant variety or cultivar

Common tree families:

  • Rosaceae – crabapple, serviceberry, hawthorn, fruit trees
  • Aceraceae – maples
  • Fabaceae – redbud, honeylocust

It may be tempting to go for the traditional red maple lined street or a solid wall of arborvitae for privacy, but focusing on diversity can be a fun way to discover plants you might not have ever considered before!